Changelog from V10:
* Replaced function pointers in user_bkpt structure with weak
functions as suggested by Peter Zijlstra.
* CONFIG_PROBE_EVENTS now selects uprobe-tracer and kprobe-tracer
as suggested by Frederic.
* Split perf-probe listing patches into smaller patches.
Changelog from V9:
* Resolved comments from Arnaldo on perf support for uprobes.
* perf probe -S will now list only global binding functions as
requested by Christoph Hellwig.
* Moved Changelog to below Signed-off-by: line, so that its not part
of the patch description. (Suggested by Christoph.)
Changelog from V8:
* Fix build issues reported by Christoph.
* List available probes in a file without need to specify pid.
Changelog from V7:
* New feature: perf probe lists available probes.
* Fix perf probes for uprobes to exit with a error message on dwarf
based probes.
* Merge changes to kprobes traceevent infrastructure.
* Merge changes to perf.
Changelog from V6:
* Remove perf adjust symbols patch.
Changelog from V5:
* Merged user_bkpt and user_bkpt_xol into uprobes.
* Addressed comments till now.
Changelog from V4:
* Rebased to tip tree. (2.6.35-rc3-tip)
Changelog from v3:
* Reverted to background page replacement as suggested by Peter Zijlstra.
* Dso in 'perf probe' can be either be a short name or a absolute path.
* Addressed comments from Masami, Frederic, Steven on traceevents and perf
Changelog from v2:
* Addressed comments from Oleg, including removal of interrupt context
handlers, reverting background page replacement in favour of
access_process_vm().
* Provides perf interface for uprobes.
Changelog from v1:
* Added trace_event interface for uprobes.
* Addressed comments from Andrew Morton and Randy Dunlap.
For previous posting: please refer:
http://lkml.org/lkml/2010/7/27/121, http://lkml.org/lkml/2010/7/12/67,
http://lkml.org/lkml/2010/7/8/239, http://lkml.org/lkml/2010/6/29/299,
http://lkml.org/lkml/2010/6/14/41, http://lkml.org/lkml/2010/3/20/107
and http://lkml.org/lkml/2010/5/18/307
This patchset implements Uprobes which enables you to dynamically break
into any routine in a user space application and collect information
non-disruptively.
This patchset is a rework based on suggestions from discussions on lkml
in January and March 2010 (http://lkml.org/lkml/2010/1/11/92,
http://lkml.org/lkml/2010/1/27/19, http://lkml.org/lkml/2010/3/20/107
and http://lkml.org/lkml/2010/3/31/199 ). This implementation of
uprobes doesnt depend on utrace.
When a uprobe is registered, Uprobes makes a copy of the probed
instruction, replaces the first byte(s) of the probed instruction with a
breakpoint instruction. (Uprobes uses background page replacement
mechanism and ensures that the breakpoint affects only that process.)
When a CPU hits the breakpoint instruction, Uprobes gets notified of
trap and finds the associated uprobe. It then executes the associated
handler. Uprobes single-steps its copy of the probed instruction and
resumes execution of the probed process at the instruction following the
probepoint. Instruction copies to be single-stepped are stored in a
per-process "execution out of line (XOL) area". Currently XOL area is
allocated as one page vma.
Advantages of uprobes over conventional debugging include:
1. Non-disruptive.
Unlike current ptrace based mechanisms, uprobes tracing wouldnt
involve signals, stopping threads and context switching between the
tracer and tracee.
2. Much better handling of multithreaded programs because of XOL.
Current ptrace based mechanisms use single stepping inline, i.e they
copy back the original instruction on hitting a breakpoint. In such
mechanisms tracers have to stop all the threads on a breakpoint hit or
tracers will not be able to handle all hits to the location of
interest. Uprobes uses execution out of line, where the instruction to
be traced is analysed at the time of breakpoint insertion and a copy
of instruction is stored at a different location. On breakpoint hit,
uprobes jumps to that copied location and singlesteps the same
instruction and does the necessary fixups post singlestepping.
3. Multiple tracers for an application.
Multiple uprobes based tracer could work in unison to trace an
application. There could one tracer that could be interested in
generic events for a particular set of process. While there could be
another tracer that is just interested in one specific event of a
particular process thats part of the previous set of process.
4. Corelating events from kernels and userspace.
Uprobes could be used with other tools like kprobes, tracepoints or as
part of higher level tools like perf to give a consolidated set of
events from kernel and userspace. In future we could look at a single
backtrace showing application, library and kernel calls.
Here is the list of TODO Items.
- Perf automatically adds probes for high-overhead functions.
- Allow trace scripts to insert probes
- Syscall integration and TRACE_EVENT() universe.
(Need clarity/discussion on API)
- Allowing probes across fork.
- Allowing probes per-executable/per dso.
- Allow multiple probes to share a probepoint.
- Return probes.
- Support for other architectures.
- Uprobes booster.
- Merge uprobes and kprobes trace_event.
- replace macro W with bits in inat table.
Please do provide your valuable comments.
Thanks in advance.
Srikar
---
Srikar Dronamraju(15)
1: mm: Move replace_page() / write_protect_page() to mm/memory.c
2: uprobes: Breakpoint insertion/removal in user space applications.
3: uprobes: Slot allocation for Execution out of line(XOL)
4: uprobes: x86 specific functions for user space breakpointing.
5: uprobes: Uprobes (un)registration and exception handling.
6: uprobes: X86 support for Uprobes
7: uprobes: Uprobes Documentation
8: tracing: Extract out common code for kprobes/uprobes traceevents.
9: tracing: uprobes trace_event interface
10: tracing: config option to enable both kprobe-tracer and uprobe-tracer.
11: perf: list symbols in a dso in ascending order.
12: perf: show possible probes in a given file.
13: perf: Loop thro each of the maps in a map_group.
14: perf: perf interface for uprobes
15: perf: Show Potential probe points.
Documentation/uprobes.txt | 188 +++++
arch/Kconfig | 6 +
arch/x86/Kconfig | 1 +
arch/x86/include/asm/thread_info.h | 2 +
arch/x86/include/asm/uprobes.h | 43 ++
arch/x86/kernel/Makefile | 2 +
arch/x86/kernel/signal.c | 13 +
arch/x86/kernel/uprobes.c | 613 ++++++++++++++++
fs/exec.c | 4 +
include/linux/mm.h | 4 +
include/linux/mm_types.h | 4 +
include/linux/sched.h | 3 +
include/linux/uprobes.h | 305 ++++++++
kernel/Makefile | 1 +
kernel/fork.c | 21 +
kernel/trace/Kconfig | 61 ++-
kernel/trace/Makefile | 2 +
kernel/trace/trace.h | 5 +
kernel/trace/trace_kprobe.c | 752 +-------------------
kernel/trace/trace_probe.c | 654 +++++++++++++++++
kernel/trace/trace_probe.h | 157 ++++
kernel/trace/trace_uprobe.c | 739 +++++++++++++++++++
kernel/uprobes.c | 1405 ++++++++++++++++++++++++++++++++++++
mm/ksm.c | 112 ---
mm/memory.c | 120 +++
tools/perf/builtin-probe.c | 55 ++-
tools/perf/util/map.h | 27 +
tools/perf/util/probe-event.c | 503 +++++++++++--
tools/perf/util/probe-event.h | 13 +-
tools/perf/util/symbol.c | 22 +
tools/perf/util/symbol.h | 2 +
31 files changed, 4886 insertions(+), 953 deletions(-)
User bkpt will use background page replacement approach to insert/delete
breakpoints. Background page replacement approach will be based on
replace_page and write_protect_page.
Now replace_page() loses its static attribute.
Signed-off-by: Srikar Dronamraju <[email protected]>
Signed-off-by: Ananth N Mavinakayanahalli <[email protected]>
---
include/linux/mm.h | 4 ++
mm/ksm.c | 112 -------------------------------------------------
mm/memory.c | 120 ++++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 124 insertions(+), 112 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 831c693..3f014e4 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -863,6 +863,10 @@ void account_page_dirtied(struct page *page, struct address_space *mapping);
int set_page_dirty(struct page *page);
int set_page_dirty_lock(struct page *page);
int clear_page_dirty_for_io(struct page *page);
+int replace_page(struct vm_area_struct *vma, struct page *page,
+ struct page *kpage, pte_t orig_pte);
+int write_protect_page(struct vm_area_struct *vma, struct page *page,
+ pte_t *orig_pte);
extern unsigned long move_page_tables(struct vm_area_struct *vma,
unsigned long old_addr, struct vm_area_struct *new_vma,
diff --git a/mm/ksm.c b/mm/ksm.c
index e2ae004..8a792d0 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -694,118 +694,6 @@ static inline int pages_identical(struct page *page1, struct page *page2)
return !memcmp_pages(page1, page2);
}
-static int write_protect_page(struct vm_area_struct *vma, struct page *page,
- pte_t *orig_pte)
-{
- struct mm_struct *mm = vma->vm_mm;
- unsigned long addr;
- pte_t *ptep;
- spinlock_t *ptl;
- int swapped;
- int err = -EFAULT;
-
- addr = page_address_in_vma(page, vma);
- if (addr == -EFAULT)
- goto out;
-
- ptep = page_check_address(page, mm, addr, &ptl, 0);
- if (!ptep)
- goto out;
-
- if (pte_write(*ptep)) {
- pte_t entry;
-
- swapped = PageSwapCache(page);
- flush_cache_page(vma, addr, page_to_pfn(page));
- /*
- * Ok this is tricky, when get_user_pages_fast() run it doesnt
- * take any lock, therefore the check that we are going to make
- * with the pagecount against the mapcount is racey and
- * O_DIRECT can happen right after the check.
- * So we clear the pte and flush the tlb before the check
- * this assure us that no O_DIRECT can happen after the check
- * or in the middle of the check.
- */
- entry = ptep_clear_flush(vma, addr, ptep);
- /*
- * Check that no O_DIRECT or similar I/O is in progress on the
- * page
- */
- if (page_mapcount(page) + 1 + swapped != page_count(page)) {
- set_pte_at(mm, addr, ptep, entry);
- goto out_unlock;
- }
- entry = pte_wrprotect(entry);
- set_pte_at_notify(mm, addr, ptep, entry);
- }
- *orig_pte = *ptep;
- err = 0;
-
-out_unlock:
- pte_unmap_unlock(ptep, ptl);
-out:
- return err;
-}
-
-/**
- * replace_page - replace page in vma by new ksm page
- * @vma: vma that holds the pte pointing to page
- * @page: the page we are replacing by kpage
- * @kpage: the ksm page we replace page by
- * @orig_pte: the original value of the pte
- *
- * Returns 0 on success, -EFAULT on failure.
- */
-static int replace_page(struct vm_area_struct *vma, struct page *page,
- struct page *kpage, pte_t orig_pte)
-{
- struct mm_struct *mm = vma->vm_mm;
- pgd_t *pgd;
- pud_t *pud;
- pmd_t *pmd;
- pte_t *ptep;
- spinlock_t *ptl;
- unsigned long addr;
- int err = -EFAULT;
-
- addr = page_address_in_vma(page, vma);
- if (addr == -EFAULT)
- goto out;
-
- pgd = pgd_offset(mm, addr);
- if (!pgd_present(*pgd))
- goto out;
-
- pud = pud_offset(pgd, addr);
- if (!pud_present(*pud))
- goto out;
-
- pmd = pmd_offset(pud, addr);
- if (!pmd_present(*pmd))
- goto out;
-
- ptep = pte_offset_map_lock(mm, pmd, addr, &ptl);
- if (!pte_same(*ptep, orig_pte)) {
- pte_unmap_unlock(ptep, ptl);
- goto out;
- }
-
- get_page(kpage);
- page_add_anon_rmap(kpage, vma, addr);
-
- flush_cache_page(vma, addr, pte_pfn(*ptep));
- ptep_clear_flush(vma, addr, ptep);
- set_pte_at_notify(mm, addr, ptep, mk_pte(kpage, vma->vm_page_prot));
-
- page_remove_rmap(page);
- put_page(page);
-
- pte_unmap_unlock(ptep, ptl);
- err = 0;
-out:
- return err;
-}
-
/*
* try_to_merge_one_page - take two pages and merge them into one
* @vma: the vma that holds the pte pointing to page
diff --git a/mm/memory.c b/mm/memory.c
index 135a596..afa51a2 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2589,6 +2589,126 @@ void unmap_mapping_range(struct address_space *mapping,
}
EXPORT_SYMBOL(unmap_mapping_range);
+/**
+ * replace_page - replace page in vma by new ksm page
+ * @vma: vma that holds the pte pointing to page
+ * @page: the page we are replacing by kpage
+ * @kpage: the ksm page we replace page by
+ * @orig_pte: the original value of the pte
+ *
+ * Returns 0 on success, -EFAULT on failure.
+ */
+int replace_page(struct vm_area_struct *vma, struct page *page,
+ struct page *kpage, pte_t orig_pte)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *ptep;
+ spinlock_t *ptl;
+ unsigned long addr;
+ int err = -EFAULT;
+
+ addr = page_address_in_vma(page, vma);
+ if (addr == -EFAULT)
+ goto out;
+
+ pgd = pgd_offset(mm, addr);
+ if (!pgd_present(*pgd))
+ goto out;
+
+ pud = pud_offset(pgd, addr);
+ if (!pud_present(*pud))
+ goto out;
+
+ pmd = pmd_offset(pud, addr);
+ if (!pmd_present(*pmd))
+ goto out;
+
+ ptep = pte_offset_map_lock(mm, pmd, addr, &ptl);
+ if (!pte_same(*ptep, orig_pte)) {
+ pte_unmap_unlock(ptep, ptl);
+ goto out;
+ }
+
+ get_page(kpage);
+ page_add_anon_rmap(kpage, vma, addr);
+
+ flush_cache_page(vma, addr, pte_pfn(*ptep));
+ ptep_clear_flush(vma, addr, ptep);
+ set_pte_at_notify(mm, addr, ptep, mk_pte(kpage, vma->vm_page_prot));
+
+ page_remove_rmap(page);
+ put_page(page);
+
+ pte_unmap_unlock(ptep, ptl);
+ err = 0;
+out:
+ return err;
+}
+
+/**
+ * write_protect_page - mark the page readonly
+ * @vma: vma that holds the page we want to mark
+ * @page: page that needs to be marked readonly
+ * @orig_pte: pte for the protected page.
+ *
+ * Returns 0 on success, -EFAULT on failure.
+ */
+int write_protect_page(struct vm_area_struct *vma, struct page *page,
+ pte_t *orig_pte)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ unsigned long addr;
+ pte_t *ptep;
+ spinlock_t *ptl;
+ int swapped;
+ int err = -EFAULT;
+
+ addr = page_address_in_vma(page, vma);
+ if (addr == -EFAULT)
+ goto out;
+
+ ptep = page_check_address(page, mm, addr, &ptl, 0);
+ if (!ptep)
+ goto out;
+
+ if (pte_write(*ptep)) {
+ pte_t entry;
+
+ swapped = PageSwapCache(page);
+ flush_cache_page(vma, addr, page_to_pfn(page));
+ /*
+ * Ok this is tricky, when get_user_pages_fast() run it doesnt
+ * take any lock, therefore the check that we are going to make
+ * with the pagecount against the mapcount is racey and
+ * O_DIRECT can happen right after the check.
+ * So we clear the pte and flush the tlb before the check
+ * this assure us that no O_DIRECT can happen after the check
+ * or in the middle of the check.
+ */
+ entry = ptep_clear_flush(vma, addr, ptep);
+ /*
+ * Check that no O_DIRECT or similar I/O is in progress on the
+ * page
+ */
+ if (page_mapcount(page) + 1 + swapped != page_count(page)) {
+ set_pte_at(mm, addr, ptep, entry);
+ goto out_unlock;
+ }
+ entry = pte_wrprotect(entry);
+ set_pte_at_notify(mm, addr, ptep, entry);
+ }
+ *orig_pte = *ptep;
+ err = 0;
+
+out_unlock:
+ pte_unmap_unlock(ptep, ptl);
+out:
+ return err;
+}
+
int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end)
{
struct address_space *mapping = inode->i_mapping;
Provides a mechanism in kernel to insert/remove breakpoints in
user space applications including
- architecture independent mechanism to establish breakpoints in
userspace applications.
- helper functions for reading/writing/validating data/opcodes from
target process's address space.
- wrappers and default implementation(whereever possible) of
architecture dependent functions(setting breakpoint)
- preprocessing and postprocessing of singlestep on breakpoint hit
Single stepping inline is the traditional method where original
instructions replace the breakpointed instructions on a breakpoint
hit. This method works well with single threaded applications.
However its racy with multithreaded applications.
In execution out of line, threads single steps on a copy of the
instruction. This method works well for both single-threaded and
multithreaded applications.
Uprobes uses execution out of line method.
There could be other strategies like emulating an instruction. However
they are currently not implemented.
Insertion and removal of breakpoints is by "Background page
replacement". i.e make a copy of the page, modify its the contents,
set the pagetable and flush the tlbs. This page uses enhanced
replace_page to cow the page. Modified page is only reflected for the
interested process. Others sharing the page will still see the old
copy.
You need to follow this up with the uprobes patch for your
architecture to define architecture specific functionality for
reading/writing/validating data/opcodes.
Signed-off-by: Jim Keniston <[email protected]>
Signed-off-by: Srikar Dronamraju <[email protected]>
---
Changelog from V10: (replace function pointers with weak functions)
* Removed architecture specific function pointers in user_bkpt
structure and replaced them with weak functions as suggested by
Peter Zijlstra.
Changelog from V5: (Merge user_bkpt into uprobes)
* Merged user_bkpt into uprobes as suggested by Christoph Hellwig
and Peter Zijlstra.
Changelog from V3: (reimplement background page replacement)
* Replemented background page replacement based on inputs
from Peter Zijlstra.
Changelog from v2: (addressing comments from Oleg)
* Use access_process_vm instead of replace_page based
background page replacement.
Changelog from v1:
* Use k(un)map_atomic instead of k(un)map.
* Remove BUG_ON.
* Few parameter changes to be more consistent with sparse.
* Added kernel-doc comments whereever necessary.
* Introduce a check to detect if post_xol can sleep.
arch/Kconfig | 14 +
include/linux/uprobes.h | 160 ++++++++++++++++
kernel/Makefile | 1
kernel/uprobes.c | 475 +++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 650 insertions(+), 0 deletions(-)
create mode 100644 include/linux/uprobes.h
create mode 100644 kernel/uprobes.c
diff --git a/arch/Kconfig b/arch/Kconfig
index 4877a8c..87bd26b 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -47,6 +47,17 @@ config OPTPROBES
depends on !PREEMPT
select KALLSYMS_ALL
+config UPROBES
+ bool "User-space probes (EXPERIMENTAL)"
+ depends on ARCH_SUPPORTS_UPROBES
+ depends on MMU
+ help
+ Uprobes enables kernel subsystems to establish probepoints
+ in user applications and execute handler functions when
+ the probepoints are hit. For more information, refer to
+ Documentation/uprobes.txt.
+ If in doubt, say "N".
+
config HAVE_EFFICIENT_UNALIGNED_ACCESS
bool
help
@@ -80,6 +91,9 @@ config USER_RETURN_NOTIFIER
Provide a kernel-internal notification when a cpu is about to
switch to user mode.
+config ARCH_SUPPORTS_UPROBES
+ def_bool n
+
config HAVE_IOREMAP_PROT
bool
diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
new file mode 100644
index 0000000..faacb2f
--- /dev/null
+++ b/include/linux/uprobes.h
@@ -0,0 +1,160 @@
+#ifndef _LINUX_UPROBES_H
+#define _LINUX_UPROBES_H
+/*
+ * Userspace Probes (UProbes)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2008-2010
+ * Authors:
+ * Srikar Dronamraju
+ * Jim Keniston
+ */
+
+#ifdef CONFIG_ARCH_SUPPORTS_UPROBES
+#include <asm/uprobes.h>
+#else
+/*
+ * ARCH_SUPPORTS_UPROBES has not be defined.
+ */
+typedef u8 user_bkpt_opcode_t;
+#define UPROBES_XOL_SLOT_BYTES 1
+
+struct bkpt_arch_info {};
+struct user_bkpt_task_arch_info {};
+struct user_bkpt_arch_info;
+#endif
+
+
+struct task_struct;
+struct pt_regs;
+
+/**
+ * struct user_bkpt - user-space breakpoint/probepoint
+ *
+ * @vaddr: virtual address of probepoint
+ * @xol_vaddr: virtual address of XOL slot assigned to this probepoint
+ * @opcode: copy of opcode at @vaddr
+ * @insn: typically a copy of the instruction at @vaddr. More
+ * precisely, this is the instruction (stream) that will be
+ * executed in place of the original instruction.
+ * @fixups: set of fixups to be executed by @post_xol()
+ * @arch_info: architecture-specific info about this probepoint
+ */
+struct user_bkpt {
+ unsigned long vaddr;
+ unsigned long xol_vaddr;
+ user_bkpt_opcode_t opcode;
+ u8 insn[UPROBES_XOL_SLOT_BYTES];
+ u16 fixups;
+ struct bkpt_arch_info arch_info;
+};
+
+/* Post-execution fixups. Some architectures may define others. */
+
+/* No fixup needed */
+#define UPROBES_FIX_NONE 0x0
+/* Adjust IP back to vicinity of actual insn */
+#define UPROBES_FIX_IP 0x1
+/* Adjust the return address of a call insn */
+#define UPROBES_FIX_CALL 0x2
+/* Might sleep while doing Fixup */
+#define UPROBES_FIX_SLEEPY 0x4
+
+#ifndef UPROBES_FIX_DEFAULT
+#define UPROBES_FIX_DEFAULT UPROBES_FIX_IP
+#endif
+
+/**
+ * struct user_bkpt_arch_info - architecture-specific parameters and
+ * functions
+ *
+ * @bkpt_insn:
+ * The architecture's breakpoint instruction. This is used by
+ * the default versions of @set_bkpt(), @set_orig_insn(), and
+ * @is_bkpt_insn().
+ * @ip_advancement_by_bkpt_insn:
+ * The number of bytes the instruction pointer is advanced by
+ * this architecture's breakpoint instruction. For example, after
+ * the powerpc trap instruction executes, the ip still points to the
+ * breakpoint instruction (ip_advancement_by_bkpt_insn = 0); but the
+ * x86 int3 instruction (1 byte) advances the ip past the int3
+ * (ip_advancement_by_bkpt_insn = 1).
+ * @max_insn_bytes:
+ * The maximum length, in bytes, of an instruction in this
+ * architecture. This must be <= UPROBES_XOL_SLOT_BYTES;
+ */
+
+struct user_bkpt_arch_info {
+ user_bkpt_opcode_t bkpt_insn;
+ u8 ip_advancement_by_bkpt_insn;
+ u8 max_insn_bytes;
+};
+
+/* Unexported functions & macros for use by arch-specific code */
+#define user_bkpt_opcode_sz (sizeof(user_bkpt_opcode_t))
+extern unsigned long uprobes_read_vm(struct task_struct *tsk,
+ void __user *vaddr, void *kbuf,
+ unsigned long nbytes);
+extern unsigned long uprobes_write_data(struct task_struct *tsk,
+ void __user *vaddr, const void *kbuf,
+ unsigned long nbytes);
+
+/*
+ * Most architectures can use the default versions of @read_opcode(),
+ * @set_bkpt(), @set_orig_insn(), and @is_bkpt_insn();
+ * All functions (including @validate_address()) can assume
+ * that the caller has verified that the probepoint's virtual address
+ * resides in an executable VM area.
+ * @set_ip:
+ * Set the instruction pointer in @regs to @vaddr.
+ * @analyze_insn:
+ * Analyze @user_bkpt->insn. Return 0 if @user_bkpt->insn is an
+ * instruction you can probe, or a negative errno (typically -%EPERM)
+ * otherwise. Determine what sort of
+ * XOL-related fixups @post_xol() (and possibly @pre_xol()) will need
+ * to do for this instruction, and annotate @user_bkpt accordingly.
+ * You may modify @user_bkpt->insn (e.g., the x86_64 port does this
+ * for rip-relative instructions).
+ * @post_xol:
+ * Called after executing the instruction associated with
+ * @user_bkpt out of line. @post_xol() should perform the fixups
+ * specified in @user_bkpt->fixups, which includes ensuring that the
+ * instruction pointer in @regs points at the next instruction in
+ * the probed instruction stream. @tskinfo is as for @pre_xol().
+ * You must provide this function.
+ */
+
+int read_opcode(struct task_struct *tsk, unsigned long vaddr,
+ user_bkpt_opcode_t *opcode);
+int set_bkpt(struct task_struct *tsk, struct user_bkpt *user_bkpt);
+int set_orig_insn(struct task_struct *tsk,
+ struct user_bkpt *user_bkpt, bool verify);
+int validate_address(struct task_struct *tsk, unsigned long vaddr);
+bool is_bkpt_insn(struct user_bkpt *user_bkpt);
+int pre_xol(struct task_struct *tsk, struct user_bkpt *user_bkpt,
+ struct user_bkpt_task_arch_info *tskinfo,
+ struct pt_regs *regs);
+
+extern void set_ip(struct pt_regs *regs, unsigned long vaddr);
+extern int analyze_insn(struct task_struct *tsk, struct user_bkpt *user_bkpt);
+extern int post_xol(struct task_struct *tsk,
+ struct user_bkpt *user_bkpt,
+ struct user_bkpt_task_arch_info *tskinfo,
+ struct pt_regs *regs);
+
+extern struct user_bkpt_arch_info user_bkpt_arch_info;
+
+#endif /* _LINUX_UPROBES_H */
diff --git a/kernel/Makefile b/kernel/Makefile
index 17046b6..af4ec3f 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -105,6 +105,7 @@ obj-$(CONFIG_PERF_EVENTS) += perf_event.o
obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
obj-$(CONFIG_USER_RETURN_NOTIFIER) += user-return-notifier.o
obj-$(CONFIG_PADATA) += padata.o
+obj-$(CONFIG_UPROBES) += uprobes.o
ifneq ($(CONFIG_SCHED_OMIT_FRAME_POINTER),y)
# According to Alan Modra <[email protected]>, the -fno-omit-frame-pointer is
diff --git a/kernel/uprobes.c b/kernel/uprobes.c
new file mode 100644
index 0000000..8a659c9
--- /dev/null
+++ b/kernel/uprobes.c
@@ -0,0 +1,475 @@
+/*
+ * Userspace Probes (UProbes)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2008-2010
+ * Authors:
+ * Srikar Dronamraju
+ * Jim Keniston
+ */
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/ptrace.h>
+#include <linux/mm.h>
+#include <linux/uprobes.h>
+#include <linux/uaccess.h>
+#include <linux/highmem.h>
+#include <linux/pagemap.h>
+
+struct user_bkpt_arch_info *arch = &user_bkpt_arch_info;
+
+/**
+ * uprobes_read_vm - Read @nbytes at @vaddr from @tsk into @kbuf.
+ * @tsk: The probed task
+ * @vaddr: Source address, in user space to be read.
+ * @kbuf: Destination address, in kernel space.
+ *
+ * Context: This function may sleep.
+ *
+ * Returns number of bytes that could be copied.
+ */
+unsigned long uprobes_read_vm(struct task_struct *tsk, void __user *vaddr,
+ void *kbuf, unsigned long nbytes)
+{
+ if (tsk == current) {
+ unsigned long nleft = copy_from_user(kbuf, vaddr, nbytes);
+ return nbytes - nleft;
+ } else
+ return access_process_vm(tsk, (unsigned long) vaddr, kbuf,
+ nbytes, 0);
+}
+
+/**
+ * uprobes_write_data - Write @nbytes from @kbuf at @vaddr in @tsk.
+ * Can be used to write to stack or data VM areas, but not instructions.
+ * Not exported, but available for use by arch-specific uprobes code.
+ * @tsk: The probed task
+ * @vaddr: Destination address, in user space.
+ * @kbuf: Source address, in kernel space to be read.
+ *
+ * Context: This function may sleep.
+ *
+ * Return number of bytes written.
+ */
+unsigned long uprobes_write_data(struct task_struct *tsk,
+ void __user *vaddr, const void *kbuf,
+ unsigned long nbytes)
+{
+ unsigned long nleft;
+
+ if (tsk == current) {
+ nleft = copy_to_user(vaddr, kbuf, nbytes);
+ return nbytes - nleft;
+ } else
+ return access_process_vm(tsk, (unsigned long) vaddr,
+ (void *) kbuf, nbytes, 1);
+}
+
+static int write_opcode(struct task_struct *tsk, unsigned long vaddr,
+ user_bkpt_opcode_t opcode)
+{
+ struct mm_struct *mm;
+ struct vm_area_struct *vma;
+ struct page *old_page, *new_page;
+ void *vaddr_old, *vaddr_new;
+ pte_t orig_pte;
+ int ret = -EINVAL;
+
+ if (!tsk)
+ return ret;
+
+ mm = get_task_mm(tsk);
+ if (!mm)
+ return ret;
+
+ down_read(&mm->mmap_sem);
+
+ /* Read the page with vaddr into memory */
+ ret = get_user_pages(tsk, mm, vaddr, 1, 1, 1, &old_page, &vma);
+ if (ret <= 0)
+ goto mmput_out;
+
+ /*
+ * check if the page we are interested is read-only mapped
+ * Since we are interested in text pages, Our pages of interest
+ * should be mapped read-only.
+ */
+ if ((vma->vm_flags && (VM_READ|VM_WRITE)) != VM_READ) {
+ ret = -EINVAL;
+ goto put_out;
+ }
+
+ /* If its VM_SHARED vma, lets not write to such vma's. */
+ if (vma->vm_flags & VM_SHARED) {
+ ret = -EINVAL;
+ goto put_out;
+ }
+
+ /* Allocate a page */
+ new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr);
+ if (!new_page) {
+ ret = -ENOMEM;
+ goto put_out;
+ }
+
+ /*
+ * lock page will serialize against do_wp_page()'s
+ * PageAnon() handling
+ */
+ lock_page(old_page);
+ /* mark page RO so any concurrent access will end up in do_wp_page() */
+ if (write_protect_page(vma, old_page, &orig_pte))
+ goto unlock_out;
+
+ /* copy the page now that we've got it stable */
+ vaddr_old = kmap_atomic(old_page, KM_USER0);
+ vaddr_new = kmap_atomic(new_page, KM_USER1);
+
+ memcpy(vaddr_new, vaddr_old, PAGE_SIZE);
+ /* poke the new insn in, ASSUMES we don't cross page boundary */
+ vaddr &= ~PAGE_MASK;
+ memcpy(vaddr_new + vaddr, &opcode, user_bkpt_opcode_sz);
+
+ kunmap_atomic(vaddr_new, KM_USER1);
+ kunmap_atomic(vaddr_old, KM_USER0);
+
+ lock_page(new_page);
+ /* flip pages, do_wp_page() will fail pte_same() and bail */
+ ret = replace_page(vma, old_page, new_page, orig_pte);
+
+unlock_out:
+ unlock_page(new_page);
+ unlock_page(old_page);
+ if (ret != 0)
+ page_cache_release(new_page);
+
+put_out:
+ put_page(old_page); /* we did a get_page in the beginning */
+
+mmput_out:
+ up_read(&mm->mmap_sem);
+ mmput(mm);
+ return ret;
+}
+
+/**
+ * read_opcode - read the opcode at a given virtual address.
+ * @tsk: the probed task.
+ * @vaddr: the virtual address to store the opcode.
+ * @opcode: location to store the read opcode.
+ *
+ * For task @tsk, read the opcode at @vaddr and store it in @opcode.
+ * Return 0 (success) or a negative errno.
+ */
+int __weak read_opcode(struct task_struct *tsk, unsigned long vaddr,
+ user_bkpt_opcode_t *opcode)
+{
+ unsigned long bytes_read;
+
+ bytes_read = uprobes_read_vm(tsk, (void __user *) vaddr, opcode,
+ user_bkpt_opcode_sz);
+ return (bytes_read == user_bkpt_opcode_sz ? 0 : -EFAULT);
+}
+
+/**
+ * set_bkpt - store breakpoint at a given address.
+ * @tsk: the probed task
+ * @user_bkpt: the probepoint information
+ *
+ * For task @tsk, store the breakpoint instruction at
+ * @user_bkpt->vaddr.
+ * Return 0 (success) or a negative errno.
+ */
+int __weak set_bkpt(struct task_struct *tsk, struct user_bkpt *user_bkpt)
+{
+ return write_opcode(tsk, user_bkpt->vaddr, arch->bkpt_insn);
+}
+
+/**
+ * set_orig_insn - Restore the original instruction.
+ * @tsk: the probed task
+ * @user_bkpt: the probepoint information
+ * @verify: if true, verify existance of breakpoint instruction.
+ *
+ * For task @tsk, restore the original opcode (@user_bkpt->opcode) at
+ * @user_bkpt->vaddr.
+ * Return 0 (success) or a negative errno.
+ */
+int __weak set_orig_insn(struct task_struct *tsk,
+ struct user_bkpt *user_bkpt, bool verify)
+{
+ if (verify) {
+ user_bkpt_opcode_t opcode;
+ int result = read_opcode(tsk, user_bkpt->vaddr, &opcode);
+ if (result)
+ return result;
+ if (opcode != arch->bkpt_insn)
+ return -EINVAL;
+ }
+ return write_opcode(tsk, user_bkpt->vaddr, user_bkpt->opcode);
+}
+
+/**
+ * check_vma - verify if the address is in a executable vma.
+ * @tsk: the probed task
+ * @vaddr: virtual address of the instruction to be verified.
+ *
+ * Return 0 if vaddr is in an executable VM area,
+ * or -EINVAL otherwise.
+ */
+static int check_vma(struct task_struct *tsk, unsigned long vaddr)
+{
+ struct vm_area_struct *vma;
+ struct mm_struct *mm;
+ int ret = -EINVAL;
+
+ mm = get_task_mm(tsk);
+ if (!mm)
+ return -EINVAL;
+ down_read(&mm->mmap_sem);
+ vma = find_vma(mm, vaddr);
+ if (vma && vaddr >= vma->vm_start && (vma->vm_flags & VM_EXEC))
+ ret = 0;
+ up_read(&mm->mmap_sem);
+ mmput(mm);
+ return ret;
+}
+
+static void print_insert_fail(struct task_struct *tsk,
+ struct user_bkpt *user_bkpt, const char *why)
+{
+ printk(KERN_ERR "Can't place breakpoint at pid %d vaddr %#lx: %s\n",
+ tsk->pid, user_bkpt->vaddr, why);
+}
+
+/**
+ * validate_address - validate instruction address.
+ * @tsk: the probed task
+ * @vaddr: virtual address of the instruction to be verified.
+ *
+ * Returns 0 if the vaddr is a valid instruction address.
+ * Possible errors:
+ * -%EINVAL: Instruction passed is not a valid instruction address.
+ */
+int __weak validate_address(struct task_struct *tsk, unsigned long vaddr)
+{
+ return check_vma(tsk, vaddr);
+}
+
+/*
+ * __insert_bkpt - insert breakpoint
+ * Insert a breakpoint into the process that includes @tsk, at the
+ * virtual address @user_bkpt->vaddr.
+ *
+ * All threads of the probed process must be stopped while
+ * @__insert_bkpt() runs.
+ *
+ * Possible errors:
+ * -%ENOSYS: user_bkpt not supported for this architecture
+ * -%EINVAL: invalid instruction address
+ * -%EEXIST: breakpoint instruction already exists at that address
+ * -%EPERM: cannot probe this instruction
+ * -%EFAULT: failed to insert breakpoint instruction
+ */
+static int __insert_bkpt(struct task_struct *tsk,
+ struct user_bkpt *user_bkpt)
+{
+ int result;
+ unsigned long len;
+
+ result = validate_address(tsk, user_bkpt->vaddr);
+ if (result != 0)
+ return result;
+
+ /*
+ * If uprobes_read_vm() transfers fewer bytes than the maximum
+ * instruction size, assume that the probed instruction is smaller
+ * than the max and near the end of the last page of instructions.
+ * But there must be room at least for a breakpoint-size instruction.
+ */
+ len = uprobes_read_vm(tsk, (void __user *) user_bkpt->vaddr,
+ user_bkpt->insn, arch->max_insn_bytes);
+ if (len < user_bkpt_opcode_sz) {
+ print_insert_fail(tsk, user_bkpt,
+ "error reading original instruction");
+ return -EFAULT;
+ }
+ memcpy(&user_bkpt->opcode, user_bkpt->insn, user_bkpt_opcode_sz);
+ if (is_bkpt_insn(user_bkpt)) {
+ print_insert_fail(tsk, user_bkpt,
+ "bkpt already exists at that addr");
+ return -EEXIST;
+ }
+
+ result = analyze_insn(tsk, user_bkpt);
+ if (result < 0) {
+ print_insert_fail(tsk, user_bkpt,
+ "instruction type cannot be probed");
+ return result;
+ }
+
+ result = set_bkpt(tsk, user_bkpt);
+ if (result < 0) {
+ print_insert_fail(tsk, user_bkpt,
+ "failed to insert bkpt instruction");
+ return result;
+ }
+ return 0;
+}
+
+/*
+ * pre_sstep - prepare to single-step the probed instruction
+ * @tsk: the probed task
+ * @user_bkpt: the probepoint information, as returned by
+ * @__insert_bkpt(). @user_bkpt->xol_vaddr must be the
+ * address of an XOL instruction slot that is allocated to this
+ * probepoint at least until after the completion of
+ * @uprobes_post_sstep(), and populated with the contents of
+ * @user_bkpt->insn.
+ * @tskinfo: points to a @user_bkpt_task_arch_info object for @tsk.
+ * @regs: reflects the saved user state of @tsk. pre_sstep()
+ * adjusts this. In particular, the instruction pointer is set
+ * to the instruction to be single-stepped.
+ * Possible errors:
+ * -%EFAULT: Failed to read or write @tsk's address space as needed.
+ *
+ * The client must ensure that the contents of @user_bkpt are not
+ * changed during the single-step operation -- i.e., between when
+ * @uprobes_pre_sstep() is called and when @uprobes_post_sstep() returns.
+ */
+static int pre_sstep(struct task_struct *tsk, struct user_bkpt *user_bkpt,
+ struct user_bkpt_task_arch_info *tskinfo, struct pt_regs *regs)
+{
+ return pre_xol(tsk, user_bkpt, tskinfo, regs);
+}
+
+/*
+ * post_sstep - prepare to resume execution after single-step
+ * @tsk: the probed task
+ * @user_bkpt: the probepoint information, as with @user_bkpt_pre_sstep()
+ * @tskinfo: the @user_bkpt_task_arch_info object, if any, passed to
+ * @pre_sstep()
+ * @regs: reflects the saved state of @tsk after the single-step
+ * operation. @post_sstep() adjusts @tsk's state as needed,
+ * including pointing the instruction pointer at the instruction
+ * following the probed instruction.
+ * Possible errors:
+ * -%EFAULT: Failed to read or write @tsk's address space as needed.
+ */
+static int post_sstep(struct task_struct *tsk, struct user_bkpt *user_bkpt,
+ struct user_bkpt_task_arch_info *tskinfo, struct pt_regs *regs)
+{
+ return post_xol(tsk, user_bkpt, tskinfo, regs);
+}
+
+/**
+ * uprobes_get_bkpt_addr - compute address of bkpt given post-bkpt regs
+ * @regs: Reflects the saved state of the task after it has hit a breakpoint
+ * instruction.
+ * Return the address of the breakpoint instruction.
+ */
+unsigned long uprobes_get_bkpt_addr(struct pt_regs *regs)
+{
+ return instruction_pointer(regs) - arch->ip_advancement_by_bkpt_insn;
+}
+
+/*
+ * __remove_bkpt - remove breakpoint
+ * For the process that includes @tsk, remove the breakpoint specified
+ * by @user_bkpt, restoring the original opcode.
+ *
+ * Possible errors:
+ * -%EINVAL: @user_bkpt->vaddr is not a valid instruction address.
+ * -%ENOENT: There is no breakpoint instruction at @user_bkpt->vaddr.
+ * -%EFAULT: Failed to read/write @tsk's address space as needed.
+ */
+static int __remove_bkpt(struct task_struct *tsk,
+ struct user_bkpt *user_bkpt)
+{
+ if (validate_address(tsk, user_bkpt->vaddr) != 0)
+ return -EINVAL;
+ return set_orig_insn(tsk, user_bkpt, true);
+}
+
+/*
+ * uprobes_resume_can_sleep - Check if fixup might result in sleep.
+ * @user_bkpt: the probepoint information.
+ *
+ * Returns true if fixup might result in sleep.
+ */
+static bool uprobes_resume_can_sleep(struct user_bkpt *user_bkpt)
+{
+ return user_bkpt->fixups & UPROBES_FIX_SLEEPY;
+}
+
+/**
+ * is_bkpt_insn - check if instruction is breakpoint instruction.
+ * @user_bkpt: the probepoint information.
+ * Default implementation of is_bkpt_insn
+ * Returns true if @user_bkpt->opcode is @bkpt_insn.
+ */
+bool __weak is_bkpt_insn(struct user_bkpt *user_bkpt)
+{
+ return (user_bkpt->opcode == arch->bkpt_insn);
+}
+
+/**
+ * pre_xol - prepare to execute out of line.
+ * @tsk: the probed task
+ * @user_bkpt: the probepoint information.
+ * @tskinfo: points to a @user_bkpt_task_arch_info object for @tsk.
+ * @regs: reflects the saved user state of @tsk.
+ *
+ * Called just before executing the instruction associated
+ * with @user_bkpt out of line. @user_bkpt->xol_vaddr is the address
+ * in @tsk's virtual address space where @user_bkpt->insn has been
+ * copied.
+ * Always returns true.
+ */
+int __weak pre_xol(struct task_struct *tsk,
+ struct user_bkpt *user_bkpt,
+ struct user_bkpt_task_arch_info *tskinfo,
+ struct pt_regs *regs)
+{
+ set_ip(regs, user_bkpt->xol_vaddr);
+ return 0;
+}
+
+/* Validate arch-specific info during uprobes initialization. */
+static int bad_arch_param(const char *param_name, int value)
+{
+ printk(KERN_ERR "uprobes: bad value %d/%#x for parameter %s"
+ " in user_bkpt_arch_info\n", value, value, param_name);
+ return -ENOSYS;
+}
+
+static int __init init_uprobes(void)
+{
+ int result = 0;
+
+ /* Accept any value of bkpt_insn. */
+ if (arch->max_insn_bytes < 1)
+ result = bad_arch_param("max_insn_bytes",
+ arch->max_insn_bytes);
+ if (arch->ip_advancement_by_bkpt_insn > arch->max_insn_bytes)
+ result = bad_arch_param("ip_advancement_by_bkpt_insn",
+ arch->ip_advancement_by_bkpt_insn);
+ return result;
+}
+
+module_init(init_uprobes);
Provides x86 specific functions for instruction analysis and
instruction validation and x86 specific pre-processing and
post-processing of singlestep especially for RIP relative
instructions. Uses "x86: instruction decoder API" for validation and
analysis of user space instructions. This analysis is used at the time
of post-processing of breakpoint hit to do the necessary fix-ups.
There is support for breakpointing RIP relative instructions. However
there are still few instructions that cannot be singlestepped.
Also defines TIF_UPROBE flag for x86.
This patch requires "x86: instruction decoder API"
http://lkml.org/lkml/2009/6/1/459
Signed-off-by: Jim Keniston <[email protected]>
Signed-off-by: Srikar Dronamraju <[email protected]>
---
Changelog from V10: (replace function pointers with weak function
* Removed architecture specific function pointers in user_bkpt
structure and replaced them with weak functions as suggested
Peter Zijlstra.
Changelog from V5: Merged into uprobes layer.
Changelog from V1:
set UPROBES_FIX_SLEEPY if post_xol might sleep.
---
arch/x86/Kconfig | 1
arch/x86/include/asm/thread_info.h | 2
arch/x86/include/asm/uprobes.h | 43 +++
arch/x86/kernel/Makefile | 2
arch/x86/kernel/uprobes.c | 561 ++++++++++++++++++++++++++++++++++++
5 files changed, 609 insertions(+), 0 deletions(-)
create mode 100644 arch/x86/include/asm/uprobes.h
create mode 100644 arch/x86/kernel/uprobes.c
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index f0ee331..4710268 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -54,6 +54,7 @@ config X86
select HAVE_KERNEL_LZO
select HAVE_HW_BREAKPOINT
select HAVE_MIXED_BREAKPOINTS_REGS
+ select ARCH_SUPPORTS_UPROBES
select PERF_EVENTS
select HAVE_PERF_EVENTS_NMI
select ANON_INODES
diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index f0b6e5d..5b9c9f0 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -84,6 +84,7 @@ struct thread_info {
#define TIF_SECCOMP 8 /* secure computing */
#define TIF_MCE_NOTIFY 10 /* notify userspace of an MCE */
#define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */
+#define TIF_UPROBE 12 /* breakpointed or singlestepping */
#define TIF_NOTSC 16 /* TSC is not accessible in userland */
#define TIF_IA32 17 /* 32bit process */
#define TIF_FORK 18 /* ret_from_fork */
@@ -107,6 +108,7 @@ struct thread_info {
#define _TIF_SECCOMP (1 << TIF_SECCOMP)
#define _TIF_MCE_NOTIFY (1 << TIF_MCE_NOTIFY)
#define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY)
+#define _TIF_UPROBE (1 << TIF_UPROBE)
#define _TIF_NOTSC (1 << TIF_NOTSC)
#define _TIF_IA32 (1 << TIF_IA32)
#define _TIF_FORK (1 << TIF_FORK)
diff --git a/arch/x86/include/asm/uprobes.h b/arch/x86/include/asm/uprobes.h
new file mode 100644
index 0000000..035c2c9
--- /dev/null
+++ b/arch/x86/include/asm/uprobes.h
@@ -0,0 +1,43 @@
+#ifndef _ASM_UPROBES_H
+#define _ASM_UPROBES_H
+/*
+ * Userspace Probes (UProbes) for x86
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2008-2010
+ * Authors:
+ * Srikar Dronamraju
+ * Jim Keniston
+ */
+
+typedef u8 user_bkpt_opcode_t;
+#define MAX_UINSN_BYTES 16
+#define UPROBES_XOL_SLOT_BYTES (MAX_UINSN_BYTES)
+
+#ifdef CONFIG_X86_64
+struct bkpt_arch_info {
+ unsigned long rip_target_address;
+ u8 orig_insn[MAX_UINSN_BYTES];
+};
+struct user_bkpt_task_arch_info {
+ unsigned long saved_scratch_register;
+};
+#else
+struct bkpt_arch_info {};
+struct user_bkpt_task_arch_info {};
+#endif
+
+#endif /* _ASM_UPROBES_H */
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 801127c..4ef1efa 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -115,6 +115,8 @@ obj-$(CONFIG_X86_CHECK_BIOS_CORRUPTION) += check.o
obj-$(CONFIG_SWIOTLB) += pci-swiotlb.o
+obj-$(CONFIG_UPROBES) += uprobes.o
+
###
# 64 bit specific files
ifeq ($(CONFIG_X86_64),y)
diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
new file mode 100644
index 0000000..ceaedc9
--- /dev/null
+++ b/arch/x86/kernel/uprobes.c
@@ -0,0 +1,561 @@
+/*
+ * Userspace Probes (UProbes) for x86
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2008-2010
+ * Authors:
+ * Srikar Dronamraju
+ * Jim Keniston
+ */
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/ptrace.h>
+#include <linux/uprobes.h>
+
+#include <asm/insn.h>
+
+#ifdef CONFIG_X86_32
+#define is_32bit_app(tsk) 1
+#else
+#define is_32bit_app(tsk) (test_tsk_thread_flag(tsk, TIF_IA32))
+#endif
+
+#define UPROBES_FIX_RIP_AX 0x8000
+#define UPROBES_FIX_RIP_CX 0x4000
+
+/* Adaptations for mhiramat x86 decoder v14. */
+#define OPCODE1(insn) ((insn)->opcode.bytes[0])
+#define OPCODE2(insn) ((insn)->opcode.bytes[1])
+#define OPCODE3(insn) ((insn)->opcode.bytes[2])
+#define MODRM_REG(insn) X86_MODRM_REG(insn->modrm.value)
+
+/*
+ * @reg: reflects the saved state of the task
+ * @vaddr: the virtual address to jump to.
+ * Return 0 on success or a -ve number on error.
+ */
+void set_ip(struct pt_regs *regs, unsigned long vaddr)
+{
+ regs->ip = vaddr;
+}
+
+#ifdef CONFIG_X86_64
+static bool is_riprel_insn(struct user_bkpt *user_bkpt)
+{
+ return ((user_bkpt->fixups &
+ (UPROBES_FIX_RIP_AX | UPROBES_FIX_RIP_CX)) != 0);
+}
+
+#endif /* CONFIG_X86_64 */
+
+#define W(row, b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, ba, bb, bc, bd, be, bf)\
+ (((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \
+ (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \
+ (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \
+ (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \
+ << (row % 32))
+
+
+static const u32 good_insns_64[256 / 32] = {
+ /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
+ /* ---------------------------------------------- */
+ W(0x00, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) | /* 00 */
+ W(0x10, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) , /* 10 */
+ W(0x20, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) | /* 20 */
+ W(0x30, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) , /* 30 */
+ W(0x40, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 40 */
+ W(0x50, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 50 */
+ W(0x60, 0, 0, 0, 1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* 60 */
+ W(0x70, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 70 */
+ W(0x80, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 80 */
+ W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */
+ W(0xa0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* a0 */
+ W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* b0 */
+ W(0xc0, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0) | /* c0 */
+ W(0xd0, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* d0 */
+ W(0xe0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* e0 */
+ W(0xf0, 0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1) /* f0 */
+ /* ---------------------------------------------- */
+ /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
+};
+
+/* Good-instruction tables for 32-bit apps */
+
+static const u32 good_insns_32[256 / 32] = {
+ /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
+ /* ---------------------------------------------- */
+ W(0x00, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0) | /* 00 */
+ W(0x10, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0) , /* 10 */
+ W(0x20, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1) | /* 20 */
+ W(0x30, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1) , /* 30 */
+ W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */
+ W(0x50, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 50 */
+ W(0x60, 1, 1, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* 60 */
+ W(0x70, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 70 */
+ W(0x80, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 80 */
+ W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */
+ W(0xa0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* a0 */
+ W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* b0 */
+ W(0xc0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0) | /* c0 */
+ W(0xd0, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* d0 */
+ W(0xe0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* e0 */
+ W(0xf0, 0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1) /* f0 */
+ /* ---------------------------------------------- */
+ /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
+};
+
+/* Using this for both 64-bit and 32-bit apps */
+static const u32 good_2byte_insns[256 / 32] = {
+ /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
+ /* ---------------------------------------------- */
+ W(0x00, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1) | /* 00 */
+ W(0x10, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1) , /* 10 */
+ W(0x20, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1) | /* 20 */
+ W(0x30, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 30 */
+ W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */
+ W(0x50, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 50 */
+ W(0x60, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 60 */
+ W(0x70, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1) , /* 70 */
+ W(0x80, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 80 */
+ W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */
+ W(0xa0, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 1) | /* a0 */
+ W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1) , /* b0 */
+ W(0xc0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* c0 */
+ W(0xd0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* d0 */
+ W(0xe0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* e0 */
+ W(0xf0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0) /* f0 */
+ /* ---------------------------------------------- */
+ /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
+};
+#undef W
+
+/*
+ * opcodes we'll probably never support:
+ * 6c-6d, e4-e5, ec-ed - in
+ * 6e-6f, e6-e7, ee-ef - out
+ * cc, cd - int3, int
+ * cf - iret
+ * d6 - illegal instruction
+ * f1 - int1/icebp
+ * f4 - hlt
+ * fa, fb - cli, sti
+ * 0f - lar, lsl, syscall, clts, sysret, sysenter, sysexit, invd, wbinvd, ud2
+ *
+ * invalid opcodes in 64-bit mode:
+ * 06, 0e, 16, 1e, 27, 2f, 37, 3f, 60-62, 82, c4-c5, d4-d5
+ *
+ * 63 - we support this opcode in x86_64 but not in i386.
+ *
+ * opcodes we may need to refine support for:
+ * 0f - 2-byte instructions: For many of these instructions, the validity
+ * depends on the prefix and/or the reg field. On such instructions, we
+ * just consider the opcode combination valid if it corresponds to any
+ * valid instruction.
+ * 8f - Group 1 - only reg = 0 is OK
+ * c6-c7 - Group 11 - only reg = 0 is OK
+ * d9-df - fpu insns with some illegal encodings
+ * f2, f3 - repnz, repz prefixes. These are also the first byte for
+ * certain floating-point instructions, such as addsd.
+ * fe - Group 4 - only reg = 0 or 1 is OK
+ * ff - Group 5 - only reg = 0-6 is OK
+ *
+ * others -- Do we need to support these?
+ * 0f - (floating-point?) prefetch instructions
+ * 07, 17, 1f - pop es, pop ss, pop ds
+ * 26, 2e, 36, 3e - es:, cs:, ss:, ds: segment prefixes --
+ * but 64 and 65 (fs: and gs:) seem to be used, so we support them
+ * 67 - addr16 prefix
+ * ce - into
+ * f0 - lock prefix
+ */
+
+/*
+ * TODO:
+ * - Where necessary, examine the modrm byte and allow only valid instructions
+ * in the different Groups and fpu instructions.
+ */
+
+static bool is_prefix_bad(struct insn *insn)
+{
+ int i;
+
+ for (i = 0; i < insn->prefixes.nbytes; i++) {
+ switch (insn->prefixes.bytes[i]) {
+ case 0x26: /*INAT_PFX_ES */
+ case 0x2E: /*INAT_PFX_CS */
+ case 0x36: /*INAT_PFX_DS */
+ case 0x3E: /*INAT_PFX_SS */
+ case 0xF0: /*INAT_PFX_LOCK */
+ return 1;
+ }
+ }
+ return 0;
+}
+
+static void report_bad_prefix(void)
+{
+ printk(KERN_ERR "uprobes does not currently support probing "
+ "instructions with any of the following prefixes: "
+ "cs:, ds:, es:, ss:, lock:\n");
+}
+
+static void report_bad_1byte_opcode(int mode, user_bkpt_opcode_t op)
+{
+ printk(KERN_ERR "In %d-bit apps, "
+ "uprobes does not currently support probing "
+ "instructions whose first byte is 0x%2.2x\n", mode, op);
+}
+
+static void report_bad_2byte_opcode(user_bkpt_opcode_t op)
+{
+ printk(KERN_ERR "uprobes does not currently support probing "
+ "instructions with the 2-byte opcode 0x0f 0x%2.2x\n", op);
+}
+
+static int validate_insn_32bits(struct user_bkpt *user_bkpt, struct insn *insn)
+{
+ insn_init(insn, user_bkpt->insn, false);
+
+ /* Skip good instruction prefixes; reject "bad" ones. */
+ insn_get_opcode(insn);
+ if (is_prefix_bad(insn)) {
+ report_bad_prefix();
+ return -EPERM;
+ }
+ if (test_bit(OPCODE1(insn), (unsigned long *) good_insns_32))
+ return 0;
+ if (insn->opcode.nbytes == 2) {
+ if (test_bit(OPCODE2(insn),
+ (unsigned long *) good_2byte_insns))
+ return 0;
+ report_bad_2byte_opcode(OPCODE2(insn));
+ } else
+ report_bad_1byte_opcode(32, OPCODE1(insn));
+ return -EPERM;
+}
+
+static int validate_insn_64bits(struct user_bkpt *user_bkpt, struct insn *insn)
+{
+ insn_init(insn, user_bkpt->insn, true);
+
+ /* Skip good instruction prefixes; reject "bad" ones. */
+ insn_get_opcode(insn);
+ if (is_prefix_bad(insn)) {
+ report_bad_prefix();
+ return -EPERM;
+ }
+ if (test_bit(OPCODE1(insn), (unsigned long *) good_insns_64))
+ return 0;
+ if (insn->opcode.nbytes == 2) {
+ if (test_bit(OPCODE2(insn),
+ (unsigned long *) good_2byte_insns))
+ return 0;
+ report_bad_2byte_opcode(OPCODE2(insn));
+ } else
+ report_bad_1byte_opcode(64, OPCODE1(insn));
+ return -EPERM;
+}
+
+/*
+ * Figure out which fixups post_xol() will need to perform, and annotate
+ * user_bkpt->fixups accordingly. To start with, user_bkpt->fixups is
+ * either zero or it reflects rip-related fixups.
+ */
+static void prepare_fixups(struct user_bkpt *user_bkpt, struct insn *insn)
+{
+ bool fix_ip = true, fix_call = false; /* defaults */
+ insn_get_opcode(insn); /* should be a nop */
+
+ switch (OPCODE1(insn)) {
+ case 0xc3: /* ret/lret */
+ case 0xcb:
+ case 0xc2:
+ case 0xca:
+ /* ip is correct */
+ fix_ip = false;
+ break;
+ case 0xe8: /* call relative - Fix return addr */
+ fix_call = true;
+ break;
+ case 0x9a: /* call absolute - Fix return addr, not ip */
+ fix_call = true;
+ fix_ip = false;
+ break;
+ case 0xff:
+ {
+ int reg;
+ insn_get_modrm(insn);
+ reg = MODRM_REG(insn);
+ if (reg == 2 || reg == 3) {
+ /* call or lcall, indirect */
+ /* Fix return addr; ip is correct. */
+ fix_call = true;
+ fix_ip = false;
+ } else if (reg == 4 || reg == 5) {
+ /* jmp or ljmp, indirect */
+ /* ip is correct. */
+ fix_ip = false;
+ }
+ break;
+ }
+ case 0xea: /* jmp absolute -- ip is correct */
+ fix_ip = false;
+ break;
+ default:
+ break;
+ }
+ if (fix_ip)
+ user_bkpt->fixups |= UPROBES_FIX_IP;
+ if (fix_call)
+ user_bkpt->fixups |=
+ (UPROBES_FIX_CALL | UPROBES_FIX_SLEEPY);
+}
+
+#ifdef CONFIG_X86_64
+static int handle_riprel_insn(struct user_bkpt *user_bkpt, struct insn *insn);
+#endif
+
+/**
+ * analyze_insn - instruction analysis including validity and fixups.
+ * @tsk: the probed task.
+ * @user_bkpt: the probepoint information.
+ * Return 0 on success or a -ve number on error.
+ */
+int analyze_insn(struct task_struct *tsk, struct user_bkpt *user_bkpt)
+{
+ int ret;
+ struct insn insn;
+
+ user_bkpt->fixups = 0;
+#ifdef CONFIG_X86_64
+ user_bkpt->arch_info.rip_target_address = 0x0;
+#endif
+
+ if (is_32bit_app(tsk))
+ ret = validate_insn_32bits(user_bkpt, &insn);
+ else
+ ret = validate_insn_64bits(user_bkpt, &insn);
+ if (ret != 0)
+ return ret;
+#ifdef CONFIG_X86_64
+ ret = handle_riprel_insn(user_bkpt, &insn);
+ if (ret == -1)
+ /* rip-relative; can't XOL */
+ return 0;
+#endif
+ prepare_fixups(user_bkpt, &insn);
+ return 0;
+}
+
+#ifdef CONFIG_X86_64
+/*
+ * If user_bkpt->insn doesn't use rip-relative addressing, return 0. Otherwise,
+ * rewrite the instruction so that it accesses its memory operand
+ * indirectly through a scratch register. Set user_bkpt->fixups and
+ * user_bkpt->arch_info.rip_target_address accordingly. (The contents of the
+ * scratch register will be saved before we single-step the modified
+ * instruction, and restored afterward.) Return 1.
+ *
+ * We do this because a rip-relative instruction can access only a
+ * relatively small area (+/- 2 GB from the instruction), and the XOL
+ * area typically lies beyond that area. At least for instructions
+ * that store to memory, we can't execute the original instruction
+ * and "fix things up" later, because the misdirected store could be
+ * disastrous.
+ *
+ * Some useful facts about rip-relative instructions:
+ * - There's always a modrm byte.
+ * - There's never a SIB byte.
+ * - The displacement is always 4 bytes.
+ */
+static int handle_riprel_insn(struct user_bkpt *user_bkpt, struct insn *insn)
+{
+ u8 *cursor;
+ u8 reg;
+
+ if (!insn_rip_relative(insn))
+ return 0;
+
+ memcpy(user_bkpt->arch_info.orig_insn, user_bkpt->insn,
+ MAX_UINSN_BYTES);
+
+ /*
+ * Point cursor at the modrm byte. The next 4 bytes are the
+ * displacement. Beyond the displacement, for some instructions,
+ * is the immediate operand.
+ */
+ cursor = user_bkpt->insn + insn->prefixes.nbytes
+ + insn->rex_prefix.nbytes + insn->opcode.nbytes;
+ insn_get_length(insn);
+
+ /*
+ * Convert from rip-relative addressing to indirect addressing
+ * via a scratch register. Change the r/m field from 0x5 (%rip)
+ * to 0x0 (%rax) or 0x1 (%rcx), and squeeze out the offset field.
+ */
+ reg = MODRM_REG(insn);
+ if (reg == 0) {
+ /*
+ * The register operand (if any) is either the A register
+ * (%rax, %eax, etc.) or (if the 0x4 bit is set in the
+ * REX prefix) %r8. In any case, we know the C register
+ * is NOT the register operand, so we use %rcx (register
+ * #1) for the scratch register.
+ */
+ user_bkpt->fixups = UPROBES_FIX_RIP_CX;
+ /* Change modrm from 00 000 101 to 00 000 001. */
+ *cursor = 0x1;
+ } else {
+ /* Use %rax (register #0) for the scratch register. */
+ user_bkpt->fixups = UPROBES_FIX_RIP_AX;
+ /* Change modrm from 00 xxx 101 to 00 xxx 000 */
+ *cursor = (reg << 3);
+ }
+
+ /* Target address = address of next instruction + (signed) offset */
+ user_bkpt->arch_info.rip_target_address = (long) user_bkpt->vaddr +
+ insn->length + insn->displacement.value;
+ /* Displacement field is gone; slide immediate field (if any) over. */
+ if (insn->immediate.nbytes) {
+ cursor++;
+ memmove(cursor, cursor + insn->displacement.nbytes,
+ insn->immediate.nbytes);
+ }
+ return 1;
+}
+
+/*
+ * pre_xol - prepare to execute out of line.
+ * @tsk: the probed task
+ * @user_bkpt: the probepoint information.
+ * @tskinfo: points to a @user_bkpt_task_arch_info object for @tsk.
+ * @regs: reflects the saved user state of @tsk.
+ *
+ * If we're emulating a rip-relative instruction, save the contents
+ * of the scratch register and store the target address in that register.
+ *
+ * Returns true if @user_bkpt->opcode is @bkpt_insn.
+ */
+int pre_xol(struct task_struct *tsk, struct user_bkpt *user_bkpt,
+ struct user_bkpt_task_arch_info *tskinfo, struct pt_regs *regs)
+{
+ BUG_ON(!user_bkpt->xol_vaddr);
+ regs->ip = user_bkpt->xol_vaddr;
+ if (user_bkpt->fixups & UPROBES_FIX_RIP_AX) {
+ tskinfo->saved_scratch_register = regs->ax;
+ regs->ax = user_bkpt->arch_info.rip_target_address;
+ } else if (user_bkpt->fixups & UPROBES_FIX_RIP_CX) {
+ tskinfo->saved_scratch_register = regs->cx;
+ regs->cx = user_bkpt->arch_info.rip_target_address;
+ }
+ return 0;
+}
+#endif
+
+/*
+ * Called by post_xol() to adjust the return address pushed by a call
+ * instruction executed out of line.
+ */
+static int adjust_ret_addr(struct task_struct *tsk, unsigned long sp,
+ long correction)
+{
+ int rasize, ncopied;
+ long ra = 0;
+
+ if (is_32bit_app(tsk))
+ rasize = 4;
+ else
+ rasize = 8;
+ ncopied = uprobes_read_vm(tsk, (void __user *) sp, &ra, rasize);
+ if (unlikely(ncopied != rasize))
+ goto fail;
+ ra += correction;
+ ncopied = uprobes_write_data(tsk, (void __user *) sp, &ra, rasize);
+ if (unlikely(ncopied != rasize))
+ goto fail;
+ return 0;
+
+fail:
+ printk(KERN_ERR
+ "uprobes: Failed to adjust return address after"
+ " single-stepping call instruction;"
+ " pid=%d, sp=%#lx\n", tsk->pid, sp);
+ return -EFAULT;
+}
+
+/*
+ * Called after single-stepping. user_bkpt->vaddr is the address of the
+ * instruction whose first byte has been replaced by the "int3"
+ * instruction. To avoid the SMP problems that can occur when we
+ * temporarily put back the original opcode to single-step, we
+ * single-stepped a copy of the instruction. The address of this
+ * copy is user_bkpt->xol_vaddr.
+ *
+ * This function prepares to resume execution after the single-step.
+ * We have to fix things up as follows:
+ *
+ * Typically, the new ip is relative to the copied instruction. We need
+ * to make it relative to the original instruction (FIX_IP). Exceptions
+ * are return instructions and absolute or indirect jump or call instructions.
+ *
+ * If the single-stepped instruction was a call, the return address that
+ * is atop the stack is the address following the copied instruction. We
+ * need to make it the address following the original instruction (FIX_CALL).
+ *
+ * If the original instruction was a rip-relative instruction such as
+ * "movl %edx,0xnnnn(%rip)", we have instead executed an equivalent
+ * instruction using a scratch register -- e.g., "movl %edx,(%rax)".
+ * We need to restore the contents of the scratch register and adjust
+ * the ip, keeping in mind that the instruction we executed is 4 bytes
+ * shorter than the original instruction (since we squeezed out the offset
+ * field). (FIX_RIP_AX or FIX_RIP_CX)
+ */
+int post_xol(struct task_struct *tsk, struct user_bkpt *user_bkpt,
+ struct user_bkpt_task_arch_info *tskinfo,
+ struct pt_regs *regs)
+{
+ /* Typically, the XOL vma is at a high addr, so correction < 0. */
+ long correction = (long) (user_bkpt->vaddr - user_bkpt->xol_vaddr);
+ int result = 0;
+
+#ifdef CONFIG_X86_64
+ if (is_riprel_insn(user_bkpt)) {
+ if (user_bkpt->fixups & UPROBES_FIX_RIP_AX)
+ regs->ax = tskinfo->saved_scratch_register;
+ else
+ regs->cx = tskinfo->saved_scratch_register;
+ /*
+ * The original instruction includes a displacement, and so
+ * is 4 bytes longer than what we've just single-stepped.
+ * Fall through to handle stuff like "jmpq *...(%rip)" and
+ * "callq *...(%rip)".
+ */
+ correction += 4;
+ }
+#endif
+ if (user_bkpt->fixups & UPROBES_FIX_IP)
+ regs->ip += correction;
+ if (user_bkpt->fixups & UPROBES_FIX_CALL)
+ result = adjust_ret_addr(tsk, regs->sp, correction);
+ return result;
+}
+
+struct user_bkpt_arch_info user_bkpt_arch_info = {
+ .bkpt_insn = 0xcc,
+ .ip_advancement_by_bkpt_insn = 1,
+ .max_insn_bytes = MAX_UINSN_BYTES,
+};
The uprobes infrastructure enables a user to dynamically establish
probepoints in user applications and collect information by executing
a handler function when a probepoint is hit.
The user specifies the virtual address and the pid of the process of
interest along with the action to be performed. Uprobes uses the
execution out of line strategy and follows lazy slot allocation. I.e,
on the first probe hit for that process, a new vma (to hold the probed
instructions for execution out of line) is allocated. Once allocated,
this vma remains for the life of the process, and is reused as needed
for subsequent probes. A slot in the vma is allocated for a
probepoint when it is first hit.
A slot is marked for reuse only when the probe gets unregistered and
there are no threads in the vicinity.
In a multithreaded process, a probepoint once registered is active for
all threads of a process. If a thread specific action for a probepoint
is required then the handler should be implemented to do the same.
If a breakpoint already exists at a particular address (irrespective
of who inserted the breakpoint including uprobes), uprobes will refuse
to register any more probes at that address.
You need to follow this up with the uprobes patch for your
architecture.
For more information: please refer to Documentation/uprobes.txt
TODO:
1. Allow multiple probes at a probepoint.
2. Booster probes.
3. Allow probes to be inherited across fork.
4. probing function returns.
Signed-off-by: Srikar Dronamraju <[email protected]>
Signed-off-by: Jim Keniston <[email protected]>
---
Changelog from V5:
- Merged user_bkpt and user_bkpt_xol layers into uprobes.
Changelog from V2:
- Introduce TIF_UPROBE flag.
- uprobes hooks now in fork/exec/exit paths instead of tracehooks.
- uprobe_process is now part of the mm struct and is shared between
processes that share the mm.
- per thread information is now allocated on the fly.
* Hence allocation and freeing of this information is lockless.
- find_probept() takes the spinlock; unlike previously when it was
expected that the spinlock was taken before calling it.
- For now run the handler in task context. The reasons for this
change being.
* utask (per task meta data structure is now allocated on the
fly. Hence first request on the thread and first request for
the breakpoint have to be anyway allocated in task context.
* Measurements showed task based handler had negligible
overhead over interrupt based handlers.
* Feedback from Oleg and few others.
* Feedback at LFCS.
* Simplicity atleast till uprobes stabilizes.
(However we introduce interrupt based handlers at a later time.)
Changelog from v1:
- If fixup might sleep; then do the post singlestep
processing in task context.
arch/Kconfig | 1
fs/exec.c | 4
include/linux/mm_types.h | 4
include/linux/sched.h | 3
include/linux/uprobes.h | 143 ++++++++++
kernel/fork.c | 21 +
kernel/uprobes.c | 653 ++++++++++++++++++++++++++++++++++++++++++++++
7 files changed, 826 insertions(+), 3 deletions(-)
diff --git a/arch/Kconfig b/arch/Kconfig
index 87bd26b..c8c8e3f 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -49,6 +49,7 @@ config OPTPROBES
config UPROBES
bool "User-space probes (EXPERIMENTAL)"
+ default n
depends on ARCH_SUPPORTS_UPROBES
depends on MMU
help
diff --git a/fs/exec.c b/fs/exec.c
index 2d94552..d7e64d0 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1053,6 +1053,10 @@ void setup_new_exec(struct linux_binprm * bprm)
flush_signal_handlers(current, 0);
flush_old_files(current->files);
+#ifdef CONFIG_UPROBES
+ if (unlikely(current->utask))
+ uprobe_free_utask(current);
+#endif
}
EXPORT_SYMBOL(setup_new_exec);
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index cb57d65..8f79e51 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -12,6 +12,7 @@
#include <linux/completion.h>
#include <linux/cpumask.h>
#include <linux/page-debug-flags.h>
+#include <linux/uprobes.h>
#include <asm/page.h>
#include <asm/mmu.h>
@@ -310,6 +311,9 @@ struct mm_struct {
#ifdef CONFIG_MMU_NOTIFIER
struct mmu_notifier_mm *mmu_notifier_mm;
#endif
+#ifdef CONFIG_UPROBES
+ struct uprobe_process *uproc; /* per mm uprobes info */
+#endif
};
/* Future-safe accessor for struct mm_struct's cpu_vm_mask. */
diff --git a/include/linux/sched.h b/include/linux/sched.h
index e18473f..e237ba2 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1496,6 +1496,9 @@ struct task_struct {
unsigned long memsw_bytes; /* uncharged mem+swap usage */
} memcg_batch;
#endif
+#ifdef CONFIG_UPROBES
+ struct uprobe_task *utask;
+#endif
};
/* Future-safe accessor for struct task_struct's cpus_allowed. */
diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
index 84a078c..a85cd36 100644
--- a/include/linux/uprobes.h
+++ b/include/linux/uprobes.h
@@ -23,6 +23,14 @@
* Jim Keniston
*/
+#include <linux/types.h>
+#include <linux/list.h>
+#include <linux/rcupdate.h>
+#include <linux/mutex.h>
+#include <linux/wait.h>
+#include <linux/spinlock_types.h>
+#include <asm/atomic.h>
+
#ifdef CONFIG_ARCH_SUPPORTS_UPROBES
#include <asm/uprobes.h>
#else
@@ -159,4 +167,139 @@ extern int post_xol(struct task_struct *tsk,
extern struct user_bkpt_arch_info user_bkpt_arch_info;
+struct task_struct;
+struct pid;
+struct pt_regs;
+
+/* This is what the user supplies us. */
+struct uprobe {
+ /*
+ * The pid of the probed process. Currently, this can be the
+ * thread ID (task->pid) of any active thread in the process.
+ */
+ pid_t pid;
+
+ /* Location of the probepoint */
+ unsigned long vaddr;
+
+ /* Handler to run when the probepoint is hit */
+ void (*handler)(struct uprobe*, struct pt_regs*);
+};
+
+/*
+ * uprobe_process -- not a user-visible struct.
+ * A uprobe_process represents a probed process. A process can have
+ * multiple probepoints (each represented by a uprobe_probept) and
+ * one or more threads (each represented by a uprobe_task).
+ *
+ * All processes/threads that share a mm share the same uprobe_process.
+ */
+struct uprobe_process {
+ /*
+ * mutex locked for any change to the uprobe_process's
+ * graph (including uprobe_probept, taking a slot in xol_area) --
+ * e.g., due to probe [un]registration or special events like exit.
+ */
+ struct mutex mutex;
+
+ /* Table of uprobe_probepts registered for this process */
+ struct list_head uprobe_list;
+
+ atomic_t refcount;
+
+ /* lock held while traversing/modifying uprobe_list and n_ppts */
+ spinlock_t pptlist_lock; /* protects uprobe_list */
+
+ /* number of probept allocated for this process */
+ int n_ppts;
+
+ /*
+ * Manages slots for instruction-copies to be single-stepped
+ * out of line.
+ */
+ void *xol_area;
+};
+
+/*
+ * uprobe_probept -- not a user-visible struct.
+ * A uprobe_probept represents a probepoint.
+ * Guarded by uproc->lock.
+ */
+struct uprobe_probept {
+ /* breakpoint/XOL details */
+ struct user_bkpt user_bkpt;
+
+ /*
+ * ppt goes in the uprobe_process->uprobe_table when registered --
+ * even before the breakpoint has been inserted.
+ */
+ struct list_head ut_node;
+
+ atomic_t refcount;
+
+ /* The parent uprobe_process */
+ struct uprobe_process *uproc;
+
+ struct uprobe *uprobe;
+};
+
+enum uprobe_task_state {
+ UTASK_RUNNING,
+ UTASK_BP_HIT,
+ UTASK_SSTEP
+};
+
+/*
+ * uprobe_utask -- not a user-visible struct.
+ * Corresponds to a thread in a probed process.
+ * Guarded by uproc->mutex.
+ */
+struct uprobe_task {
+ struct user_bkpt_task_arch_info arch_info;
+
+ enum uprobe_task_state state;
+
+ struct uprobe_probept *active_ppt;
+};
+
+#ifdef CONFIG_UPROBES
+extern int uprobes_exception_notify(struct notifier_block *self,
+ unsigned long val, void *data);
+extern int uprobe_bkpt_notifier(struct pt_regs *regs);
+extern int uprobe_post_notifier(struct pt_regs *regs);
+extern void uprobe_notify_resume(struct pt_regs *regs);
+extern void arch_uprobe_enable_sstep(struct pt_regs *regs);
+extern void arch_uprobe_disable_sstep(struct pt_regs *regs);
+extern int register_uprobe(struct uprobe *u);
+extern void unregister_uprobe(struct uprobe *u);
+extern void uprobe_free_utask(struct task_struct *tsk);
+extern void uprobe_handle_fork(struct task_struct *child);
+extern void uprobe_put_uprocess(struct mm_struct *mm);
+#else /* CONFIG_UPROBES */
+
+/*
+ * Only register_uprobe() and unregister_uprobe() are part of
+ * the client API.
+ */
+static inline int register_uprobe(struct uprobe *u)
+{
+ return -ENOSYS;
+}
+static inline void unregister_uprobe(struct uprobe *u)
+{
+}
+static inline void uprobe_free_utask(void)
+{
+}
+static inline void uprobe_handle_fork(struct task_struct *child)
+{
+}
+static inline void uprobe_notify_resume(struct pt_regs *regs)
+{
+}
+static inline void uprobe_put_uprocess(struct mm_struct *mm)
+{
+}
+#endif /* CONFIG_UPROBES */
#endif /* _LINUX_UPROBES_H */
+
diff --git a/kernel/fork.c b/kernel/fork.c
index b7e9d60..d78cf5d 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -187,6 +187,11 @@ void __put_task_struct(struct task_struct *tsk)
delayacct_tsk_free(tsk);
put_signal_struct(tsk->signal);
+#ifdef CONFIG_UPROBES
+ if (unlikely(tsk->utask))
+ uprobe_free_utask(tsk);
+#endif
+
if (!profile_handoff_task(tsk))
free_task(tsk);
}
@@ -525,6 +530,10 @@ void __mmdrop(struct mm_struct *mm)
mm_free_pgd(mm);
destroy_context(mm);
mmu_notifier_mm_destroy(mm);
+#ifdef CONFIG_UPROBES
+ if (unlikely(mm->uproc))
+ uprobe_put_uprocess(mm);
+#endif
free_mm(mm);
}
EXPORT_SYMBOL_GPL(__mmdrop);
@@ -683,6 +692,9 @@ struct mm_struct *dup_mm(struct task_struct *tsk)
if (mm->binfmt && !try_module_get(mm->binfmt->module))
goto free_pt;
+#ifdef CONFIG_UPROBES
+ mm->uproc = NULL;
+#endif
return mm;
free_pt:
@@ -1190,6 +1202,9 @@ static struct task_struct *copy_process(unsigned long clone_flags,
INIT_LIST_HEAD(&p->pi_state_list);
p->pi_state_cache = NULL;
#endif
+#ifdef CONFIG_UPROBES
+ p->utask = NULL;
+#endif
/*
* sigaltstack should be cleared when sharing the same VM
*/
@@ -1288,6 +1303,12 @@ static struct task_struct *copy_process(unsigned long clone_flags,
proc_fork_connector(p);
cgroup_post_fork(p);
perf_event_fork(p);
+#ifdef CONFIG_UPROBES
+ if ((current->mm) && !(clone_flags & CLONE_VM)) {
+ if (unlikely(current->mm->uproc))
+ uprobe_handle_fork(p);
+ }
+#endif
return p;
bad_fork_free_pid:
diff --git a/kernel/uprobes.c b/kernel/uprobes.c
index 230adf3..38c7abb 100644
--- a/kernel/uprobes.c
+++ b/kernel/uprobes.c
@@ -21,6 +21,7 @@
* Jim Keniston
*/
#include <linux/kernel.h>
+#include <linux/types.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/sched.h>
@@ -36,6 +37,9 @@
#include <linux/file.h>
#include <linux/pid.h>
#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/kdebug.h>
+
struct user_bkpt_arch_info *arch = &user_bkpt_arch_info;
@@ -345,7 +349,7 @@ static int __insert_bkpt(struct task_struct *tsk,
* @__insert_bkpt(). @user_bkpt->xol_vaddr must be the
* address of an XOL instruction slot that is allocated to this
* probepoint at least until after the completion of
- * @uprobes_post_sstep(), and populated with the contents of
+ * @post_sstep(), and populated with the contents of
* @user_bkpt->insn.
* @tskinfo: points to a @user_bkpt_task_arch_info object for @tsk.
* @regs: reflects the saved user state of @tsk. pre_sstep()
@@ -356,7 +360,7 @@ static int __insert_bkpt(struct task_struct *tsk,
*
* The client must ensure that the contents of @user_bkpt are not
* changed during the single-step operation -- i.e., between when
- * @uprobes_pre_sstep() is called and when @uprobes_post_sstep() returns.
+ * @pre_sstep() is called and when @post_sstep() returns.
*/
static int pre_sstep(struct task_struct *tsk, struct user_bkpt *user_bkpt,
struct user_bkpt_task_arch_info *tskinfo, struct pt_regs *regs)
@@ -610,7 +614,7 @@ static unsigned long xol_take_insn_slot(struct uprobes_xol_area *area)
/*
* xol_get_insn_slot - If user_bkpt was not allocated a slot, then
- * allocate a slot. If uprobes_insert_bkpt is already called, (i.e
+ * allocate a slot. If insert_bkpt is already called, (i.e
* user_bkpt.vaddr != 0) then copy the instruction into the slot.
* @user_bkpt: probepoint information
* @xol_area refers the unique per process uprobes_xol_area for
@@ -741,6 +745,642 @@ validate_end:
}
/* end of slot allocation for XOL */
+
+struct notifier_block uprobes_exception_nb = {
+ .notifier_call = uprobes_exception_notify,
+ .priority = 0x7ffffff0,
+};
+
+typedef void (*uprobe_handler_t)(struct uprobe*, struct pt_regs*);
+
+/* Guards lookup, creation, and deletion of uproc. */
+static DEFINE_MUTEX(uprobe_mutex);
+
+static inline void get_probept(struct uprobe_probept *ppt)
+{
+ atomic_inc(&ppt->refcount);
+}
+
+/*
+ * Creates a uprobe_probept and connects it to uprobe and uproc.
+ * Runs with uproc->mutex locked.
+ */
+static struct uprobe_probept *add_probept(struct uprobe *u,
+ struct uprobe_process *uproc)
+{
+ struct uprobe_probept *ppt;
+
+ ppt = kzalloc(sizeof *ppt, GFP_USER);
+ if (unlikely(ppt == NULL))
+ return ERR_PTR(-ENOMEM);
+
+ ppt->user_bkpt.vaddr = u->vaddr;
+ ppt->uprobe = u;
+ ppt->user_bkpt.xol_vaddr = 0;
+
+ ppt->uproc = uproc;
+ INIT_LIST_HEAD(&ppt->ut_node);
+ spin_lock(&uproc->pptlist_lock);
+ list_add(&ppt->ut_node, &uproc->uprobe_list);
+ uproc->n_ppts++;
+ spin_unlock(&uproc->pptlist_lock);
+ atomic_set(&ppt->refcount, 1);
+ return ppt;
+}
+
+static void put_probept(struct uprobe_probept *ppt)
+{
+ struct uprobe_process *uproc;
+
+ uproc = ppt->uproc;
+ if (atomic_dec_and_lock(&ppt->refcount, &uproc->pptlist_lock)) {
+ list_del(&ppt->ut_node);
+ uproc->n_ppts--;
+ xol_free_insn_slot(ppt->user_bkpt.xol_vaddr, uproc->xol_area);
+ spin_unlock(&uproc->pptlist_lock);
+ kfree(ppt);
+ }
+}
+
+/*
+ * In the given uproc's table of probepoints, find the one with the
+ * specified virtual address.
+ * Called with uproc->pptlist_lock acquired.
+ */
+static struct uprobe_probept *find_probept(struct uprobe_process *uproc,
+ unsigned long vaddr)
+{
+ struct uprobe_probept *ppt;
+
+ spin_lock(&uproc->pptlist_lock);
+ list_for_each_entry(ppt, &uproc->uprobe_list, ut_node) {
+ if (ppt->user_bkpt.vaddr == vaddr) {
+ spin_unlock(&uproc->pptlist_lock);
+ return ppt;
+ }
+ }
+ spin_unlock(&uproc->pptlist_lock);
+ return NULL;
+}
+
+/*
+ * Save a copy of the original instruction (so it can be single-stepped
+ * out of line), insert the breakpoint instruction.
+ * Runs with uproc->mutex locked.
+ */
+static int insert_bkpt(struct uprobe_probept *ppt, struct task_struct *tsk)
+{
+ int result;
+
+ if (tsk)
+ result = __insert_bkpt(tsk, &ppt->user_bkpt);
+ else
+ /* No surviving tasks associated with ppt->uproc */
+ result = -ESRCH;
+ return result;
+}
+
+/* Runs with uproc->mutex locked. */
+static void remove_bkpt(struct uprobe_probept *ppt, struct task_struct *tsk)
+{
+ if (!tsk)
+ return;
+
+ if (__remove_bkpt(tsk, &ppt->user_bkpt) != 0) {
+ printk(KERN_ERR "Error removing uprobe at pid %d vaddr %#lx:"
+ " can't restore original instruction\n",
+ tsk->tgid, ppt->user_bkpt.vaddr);
+ /*
+ * This shouldn't happen, since we were previously able
+ * to write the breakpoint at that address. There's not
+ * much we can do besides let the process die with a
+ * SIGTRAP the next time the breakpoint is hit.
+ */
+ }
+}
+
+/* Runs with the uprobe_mutex held. */
+static struct uprobe_process *find_uprocess(struct pid *tg_leader)
+{
+ struct uprobe_process *uproc = NULL;
+ struct task_struct *tsk;
+
+ rcu_read_lock();
+ tsk = pid_task(tg_leader, PIDTYPE_PID);
+ if (!tsk || !tsk->mm)
+ goto end;
+
+ uproc = tsk->mm->uproc;
+ if (uproc)
+ atomic_inc(&uproc->refcount);
+
+end:
+ rcu_read_unlock();
+ return uproc;
+}
+
+/*
+ * uproc's process is exiting or exec-ing.
+ * The last thread of uproc's process is about to die, and its
+ * mm_struct is about to be released.
+ * Hence do the cleanup without holding locks.
+ *
+ * Called with no locks held.
+ */
+static int free_uprocess(struct uprobe_process *uproc)
+{
+ struct uprobe_probept *ppt, *pnode;
+
+ list_for_each_entry_safe(ppt, pnode, &uproc->uprobe_list, ut_node) {
+ put_probept(ppt);
+ }
+ if (uproc->xol_area)
+ xol_free_area(uproc->xol_area);
+
+ kfree(uproc);
+ return 0;
+}
+
+/* Called with no locks held */
+static void put_uprocess(struct uprobe_process *uproc)
+{
+ if (atomic_dec_and_test(&uproc->refcount))
+ free_uprocess(uproc);
+}
+
+/*
+ * Called with no locks held.
+ * Called in context of a exiting or a exec-ing thread.
+ */
+void uprobe_free_utask(struct task_struct *tsk)
+{
+ if (!tsk->utask)
+ return;
+
+ if (tsk->utask->active_ppt)
+ put_probept(tsk->utask->active_ppt);
+ kfree(tsk->utask);
+ tsk->utask = NULL;
+}
+
+/*
+ * Callback from mmput() when mm->users count reduces to zero.
+ */
+void uprobe_put_uprocess(struct mm_struct *mm)
+{
+ put_uprocess(mm->uproc);
+ mm->uproc = NULL;
+}
+
+/*
+ * Allocate a uprobe_task object for the task.
+ * Called with t "got" and uprobe_mutex locked.
+ * Called when the thread hits a breakpoint for the first time.
+ *
+ * Returns:
+ * - pointer to new uprobe_task on success
+ * - negative errno otherwise
+ */
+static struct uprobe_task *add_utask(struct uprobe_process *uproc)
+{
+ struct uprobe_task *utask;
+
+ utask = kzalloc(sizeof *utask, GFP_KERNEL);
+ if (unlikely(utask == NULL))
+ return ERR_PTR(-ENOMEM);
+
+ utask->active_ppt = NULL;
+ current->utask = utask;
+ atomic_inc(&uproc->refcount);
+
+ return utask;
+}
+
+/* Runs with uprobe_mutex held; */
+static struct uprobe_process *create_uprocess(struct pid *tg_leader)
+{
+ struct uprobe_process *uproc = ERR_PTR(-ENOMEM);
+ struct task_struct *tsk;
+ struct mm_struct *mm = NULL;
+
+ tsk = get_pid_task(tg_leader, PIDTYPE_PID);
+ if (tsk)
+ mm = get_task_mm(tsk);
+ if (!mm) {
+ if (tsk)
+ put_task_struct(tsk);
+ return ERR_PTR(-ESRCH);
+ }
+
+ uproc = kzalloc(sizeof *uproc, GFP_KERNEL);
+ if (unlikely(uproc == NULL)) {
+ uproc = ERR_PTR(-ENOMEM);
+ goto end;
+ }
+
+ /* Initialize fields */
+ mutex_init(&uproc->mutex);
+ spin_lock_init(&uproc->pptlist_lock);
+ atomic_set(&uproc->refcount, 1);
+ INIT_LIST_HEAD(&uproc->uprobe_list);
+
+ BUG_ON(mm->uproc);
+ mm->uproc = uproc;
+
+ /*
+ * Incrementing the refcount saves us from calling find_uprocess
+ * in register_uprobe path.
+ */
+ atomic_inc(&uproc->refcount);
+
+end:
+ put_task_struct(tsk);
+ mmput(mm);
+ return uproc;
+}
+
+/*
+ * Given a numeric thread ID, return a ref-counted struct pid for the
+ * task-group-leader thread.
+ */
+static struct pid *get_tg_leader(pid_t p)
+{
+ struct pid *pid = NULL;
+
+ rcu_read_lock();
+ pid = find_vpid(p);
+ if (pid) {
+ struct task_struct *t = pid_task(pid, PIDTYPE_PID);
+
+ if (!t)
+ pid = NULL;
+ else
+ pid = get_pid(task_tgid(t));
+ }
+ rcu_read_unlock();
+ return pid;
+}
+
+/* See Documentation/uprobes.txt. */
+int register_uprobe(struct uprobe *u)
+{
+ struct uprobe_process *uproc;
+ struct uprobe_probept *ppt;
+ struct pid *p;
+ int ret = 0;
+
+ if (!u || !u->handler)
+ return -EINVAL;
+
+ p = get_tg_leader(u->pid);
+ if (!p)
+ return -ESRCH;
+
+ /* Get the uprobe_process for this pid, or make a new one. */
+ mutex_lock(&uprobe_mutex);
+ uproc = find_uprocess(p);
+
+ if (!uproc) {
+ uproc = create_uprocess(p);
+ if (IS_ERR(uproc)) {
+ ret = (int) PTR_ERR(uproc);
+ mutex_unlock(&uprobe_mutex);
+ goto fail_tsk;
+ }
+ }
+ mutex_unlock(&uprobe_mutex);
+ mutex_lock(&uproc->mutex);
+
+ if (uproc->n_ppts >= MAX_UPROBES_XOL_SLOTS)
+ goto fail_uproc;
+
+ ret = xol_validate_vaddr(p, u->vaddr, uproc->xol_area);
+ if (ret < 0)
+ goto fail_uproc;
+
+ /* See if we already have a probepoint at the vaddr. */
+ ppt = find_probept(uproc, u->vaddr);
+ if (ppt) {
+ /*
+ * A uprobe already exists at that address.
+ */
+ ret = -EALREADY;
+ goto fail_uproc;
+ } else {
+ struct task_struct *t;
+
+ ppt = add_probept(u, uproc);
+ if (IS_ERR(ppt)) {
+ ret = (int) PTR_ERR(ppt);
+ goto fail_uproc;
+ }
+
+ t = get_pid_task(p, PIDTYPE_PID);
+ if (!t)
+ goto fail_uproc;
+
+ ret = insert_bkpt(ppt, t);
+ put_task_struct(t);
+ if (ret != 0)
+ goto fail_uproc;
+ }
+
+fail_uproc:
+ mutex_unlock(&uproc->mutex);
+ put_uprocess(uproc);
+
+fail_tsk:
+ put_pid(p);
+ return ret;
+}
+
+/* See Documentation/uprobes.txt. */
+void unregister_uprobe(struct uprobe *u)
+{
+ struct uprobe_process *uproc;
+ struct uprobe_probept *ppt;
+ struct task_struct *t;
+ struct pid *p;
+
+ if (!u)
+ return;
+ p = get_tg_leader(u->pid);
+ if (!p)
+ return;
+
+ /* Get the uprobe_process for this pid. */
+ mutex_lock(&uprobe_mutex);
+ uproc = find_uprocess(p);
+ mutex_unlock(&uprobe_mutex);
+ if (!uproc) {
+ put_pid(p);
+ return;
+ }
+
+ /*
+ * Lock uproc before walking the graph, in case the process
+ * we're probing is exiting.
+ */
+ mutex_lock(&uproc->mutex);
+
+ ppt = find_probept(uproc, u->vaddr);
+ if (!ppt)
+ /*
+ * This probe was never successfully registered, or
+ * has already been unregistered.
+ */
+ goto done;
+
+ if (ppt->uprobe != u)
+ /*
+ * unregister request doesnt correspond to successful
+ * register request.
+ */
+ goto done;
+
+ t = get_pid_task(p, PIDTYPE_PID);
+ if (!t)
+ goto done;
+
+ remove_bkpt(ppt, t);
+ put_task_struct(t);
+
+ /*
+ * Breakpoint is removed; however a thread could have hit the
+ * same breakpoint and yet to find its corresponding probepoint.
+ * Before we remove the probepoint, give the breakpointed thread a
+ * chance to find the probepoint.
+ */
+ mutex_unlock(&uproc->mutex);
+ synchronize_sched();
+ mutex_lock(&uproc->mutex);
+ put_probept(ppt);
+
+done:
+ mutex_unlock(&uproc->mutex);
+ put_uprocess(uproc);
+ put_pid(p);
+}
+
+/* Prepare to single-step ppt's probed instruction out of line. */
+static int pre_ssout(struct uprobe_probept *ppt, struct pt_regs *regs)
+{
+ struct uprobe_process *uproc = current->mm->uproc;
+
+ if (unlikely(!ppt->user_bkpt.xol_vaddr)) {
+ mutex_lock(&uproc->mutex);
+ if (unlikely(!uproc->xol_area))
+ uproc->xol_area = xol_alloc_area();
+ if (uproc->xol_area && !ppt->user_bkpt.xol_vaddr)
+ xol_get_insn_slot(&ppt->user_bkpt, uproc->xol_area);
+ if (unlikely(!ppt->user_bkpt.xol_vaddr))
+ goto fail;
+ mutex_unlock(&uproc->mutex);
+ }
+ pre_sstep(current, &ppt->user_bkpt,
+ ¤t->utask->arch_info, regs);
+ set_ip(regs, ppt->user_bkpt.xol_vaddr);
+ return 0;
+
+/*
+ * We failed to execute out of line.
+ * reset the instruction pointer and remove the breakpoint.
+ */
+fail:
+ remove_bkpt(ppt, current);
+ mutex_unlock(&uproc->mutex);
+ set_ip(regs, ppt->user_bkpt.vaddr);
+ put_probept(ppt);
+ return -1;
+}
+
+/* Prepare to continue execution after single-stepping out of line. */
+static int post_ssout(struct uprobe_probept *ppt, struct pt_regs *regs)
+{
+ return post_sstep(current, &ppt->user_bkpt,
+ ¤t->utask->arch_info, regs);
+}
+
+/*
+ * Verify from Instruction Pointer if singlestep has indeed occurred.
+ * If Singlestep has occurred, then do post singlestep fix-ups.
+ */
+static bool sstep_complete(struct pt_regs *regs,
+ struct uprobe_probept *ppt)
+{
+ unsigned long vaddr = instruction_pointer(regs);
+
+ /*
+ * If we have executed out of line, Instruction pointer
+ * cannot be same as virtual address of XOL slot.
+ */
+ if (vaddr == ppt->user_bkpt.xol_vaddr)
+ return false;
+ post_ssout(ppt, regs);
+ return true;
+}
+
+/*
+ * Fork callback: The current task has spawned a process.
+ * NOTE: For now, we don't pass on uprobes from the parent to the
+ * child. We now do the necessary clearing of breakpoints in the
+ * child's address space.
+ * This function handles the case where vm is not shared between
+ * the parent and the child.
+ *
+ * TODO:
+ * - Provide option for child to inherit uprobes.
+ */
+void uprobe_handle_fork(struct task_struct *child)
+{
+ struct uprobe_process *uproc;
+ struct uprobe_probept *ppt;
+ int ret;
+
+ uproc = current->mm->uproc;
+
+ /*
+ * New process spawned by parent but not sharing the same mm.
+ * Remove the probepoints in the child's text.
+ *
+ * We also hold the uproc->mutex for the parent - so no
+ * new uprobes will be registered 'til we return.
+ */
+ mutex_lock(&uproc->mutex);
+ list_for_each_entry(ppt, &uproc->uprobe_list, ut_node) {
+ ret = __remove_bkpt(child, &ppt->user_bkpt);
+ if (ret && ret != -EINVAL) {
+ /* Ratelimit this? */
+ printk(KERN_ERR "Pid %d forked %d; failed to"
+ " remove probepoint at %#lx in child\n",
+ current->pid, child->pid,
+ ppt->user_bkpt.vaddr);
+ }
+ }
+ mutex_unlock(&uproc->mutex);
+}
+
+/*
+ * uprobe_notify_resume gets called in task context just before returning
+ * to userspace.
+ *
+ * If its the first time the probepoint is hit, slot gets allocated here.
+ * If its the first time the thread hit a breakpoint, utask gets
+ * allocated here.
+ */
+void uprobe_notify_resume(struct pt_regs *regs)
+{
+ struct uprobe_process *uproc;
+ struct uprobe_probept *ppt;
+ struct uprobe_task *utask;
+ struct uprobe *u;
+ unsigned long probept;
+
+ utask = current->utask;
+ uproc = current->mm->uproc;
+ if (unlikely(!utask)) {
+ utask = add_utask(uproc);
+
+ /* Failed to allocate utask for the current task. */
+ BUG_ON(!utask);
+ probept = uprobes_get_bkpt_addr(regs);
+ ppt = find_probept(uproc, probept);
+
+ /*
+ * The probept was refcounted in uprobe_bkpt_notifier;
+ * Hence it would be mysterious to miss ppt now
+ */
+ WARN_ON(!ppt);
+ utask->active_ppt = ppt;
+ utask->state = UTASK_BP_HIT;
+ } else
+ ppt = utask->active_ppt;
+
+ if (utask->state == UTASK_BP_HIT) {
+ utask->state = UTASK_SSTEP;
+ u = ppt->uprobe;
+ if (u && u->handler)
+ u->handler(u, regs);
+
+ if (!pre_ssout(ppt, regs))
+ arch_uprobe_enable_sstep(regs);
+ } else if (utask->state == UTASK_SSTEP) {
+ if (sstep_complete(regs, ppt)) {
+ put_probept(ppt);
+ utask->active_ppt = NULL;
+ utask->state = UTASK_RUNNING;
+ arch_uprobe_disable_sstep(regs);
+ }
+ }
+}
+
+/*
+ * uprobe_bkpt_notifier gets called from interrupt context
+ * it gets a reference to the ppt and sets TIF_UPROBE flag,
+ */
+int uprobe_bkpt_notifier(struct pt_regs *regs)
+{
+ struct uprobe_process *uproc;
+ struct uprobe_probept *ppt;
+ struct uprobe_task *utask;
+ unsigned long probept;
+
+ if (!current->mm || !current->mm->uproc)
+ /* task is currently not uprobed */
+ return 0;
+
+ uproc = current->mm->uproc;
+ utask = current->utask;
+ probept = uprobes_get_bkpt_addr(regs);
+ ppt = find_probept(uproc, probept);
+ if (!ppt)
+ return 0;
+ get_probept(ppt);
+ if (utask) {
+ utask->active_ppt = ppt;
+ utask->state = UTASK_BP_HIT;
+ }
+#ifdef CONFIG_ARCH_SUPPORTS_UPROBES
+ set_thread_flag(TIF_UPROBE);
+#endif
+ return 1;
+}
+
+/*
+ * uprobe_post_notifier gets called in interrupt context.
+ * It completes the single step operation.
+ */
+int uprobe_post_notifier(struct pt_regs *regs)
+{
+ struct uprobe_probept *ppt;
+ struct uprobe_task *utask;
+
+ if (!current->mm || !current->mm->uproc || !current->utask)
+ /* task is currently not uprobed */
+ return 0;
+
+ utask = current->utask;
+
+ ppt = utask->active_ppt;
+ if (!ppt)
+ return 0;
+
+ if (uprobes_resume_can_sleep(&ppt->user_bkpt)) {
+#ifdef CONFIG_ARCH_SUPPORTS_UPROBES
+ set_thread_flag(TIF_UPROBE);
+#endif
+ return 1;
+ }
+ if (sstep_complete(regs, ppt)) {
+ put_probept(ppt);
+ arch_uprobe_disable_sstep(regs);
+ utask->active_ppt = NULL;
+ utask->state = UTASK_RUNNING;
+ return 1;
+ }
+ return 0;
+}
+
static int __init init_uprobes(void)
{
int result = 0;
@@ -752,7 +1392,14 @@ static int __init init_uprobes(void)
if (arch->ip_advancement_by_bkpt_insn > arch->max_insn_bytes)
result = bad_arch_param("ip_advancement_by_bkpt_insn",
arch->ip_advancement_by_bkpt_insn);
+
+ register_die_notifier(&uprobes_exception_nb);
return result;
}
+static void __exit exit_uprobes(void)
+{
+}
+
module_init(init_uprobes);
+module_exit(exit_uprobes);
Provides x86 specific details for uprobes.
This includes interrupt notifier for uprobes, enabling/disabling
singlestep.
Signed-off-by: Srikar Dronamraju <[email protected]>
Signed-off-by: Ananth N Mavinakayanahalli <[email protected]>
---
Changelog from V5: Using local_irq_enable() instead of
native_irq_enable and no more disabling irqs as suggested by Oleg
Nesterov.
arch/x86/kernel/signal.c | 13 +++++++++++
arch/x86/kernel/uprobes.c | 52 +++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 65 insertions(+), 0 deletions(-)
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 4fd173c..3657563 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -848,6 +848,19 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
if (thread_info_flags & _TIF_SIGPENDING)
do_signal(regs);
+ if (thread_info_flags & _TIF_UPROBE) {
+ clear_thread_flag(TIF_UPROBE);
+#ifdef CONFIG_X86_32
+ /*
+ * On x86_32, do_notify_resume() gets called with
+ * interrupts disabled. Hence enable interrupts if they
+ * are still disabled.
+ */
+ local_irq_enable();
+#endif
+ uprobe_notify_resume(regs);
+ }
+
if (thread_info_flags & _TIF_NOTIFY_RESUME) {
clear_thread_flag(TIF_NOTIFY_RESUME);
tracehook_notify_resume(regs);
diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index ceaedc9..6985b4c 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -26,6 +26,7 @@
#include <linux/ptrace.h>
#include <linux/uprobes.h>
+#include <linux/kdebug.h>
#include <asm/insn.h>
#ifdef CONFIG_X86_32
@@ -559,3 +560,54 @@ struct user_bkpt_arch_info user_bkpt_arch_info = {
.ip_advancement_by_bkpt_insn = 1,
.max_insn_bytes = MAX_UINSN_BYTES,
};
+
+/*
+ * Wrapper routine for handling exceptions.
+ */
+int uprobes_exception_notify(struct notifier_block *self,
+ unsigned long val, void *data)
+{
+ struct die_args *args = data;
+ struct pt_regs *regs = args->regs;
+ int ret = NOTIFY_DONE;
+
+ /* We are only interested in userspace traps */
+ if (regs && !user_mode_vm(regs))
+ return NOTIFY_DONE;
+
+ switch (val) {
+ case DIE_INT3:
+ /* Run your handler here */
+ if (uprobe_bkpt_notifier(regs))
+ ret = NOTIFY_STOP;
+ break;
+ case DIE_DEBUG:
+ if (uprobe_post_notifier(regs))
+ ret = NOTIFY_STOP;
+ default:
+ break;
+ }
+ return ret;
+}
+
+void arch_uprobe_enable_sstep(struct pt_regs *regs)
+{
+ /*
+ * Enable single-stepping by
+ * - Set TF on stack
+ * - Set TIF_SINGLESTEP: Guarantees that TF is set when
+ * returning to user mode.
+ * - Indicate that TF is set by us.
+ */
+ regs->flags |= X86_EFLAGS_TF;
+ set_thread_flag(TIF_SINGLESTEP);
+ set_thread_flag(TIF_FORCED_TF);
+}
+
+void arch_uprobe_disable_sstep(struct pt_regs *regs)
+{
+ /* Disable single-stepping by clearing what we set */
+ clear_thread_flag(TIF_SINGLESTEP);
+ clear_thread_flag(TIF_FORCED_TF);
+ regs->flags &= ~X86_EFLAGS_TF;
+}
Uprobes Documentation.
Signed-off-by: Jim Keniston <[email protected]>
Signed-off-by: Srikar Dronamraju <[email protected]>
---
Changelog from V5: Removed references to Modules, Samples, and
probe Overhead.
Changelog from v3: Updated measurements.
Changelog from v2: Updated measurements.
Changelog from v1: Addressed comments from Randy Dunlap.
: Updated measurements.
Documentation/uprobes.txt | 188 +++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 188 insertions(+), 0 deletions(-)
create mode 100644 Documentation/uprobes.txt
diff --git a/Documentation/uprobes.txt b/Documentation/uprobes.txt
new file mode 100644
index 0000000..5b620d8
--- /dev/null
+++ b/Documentation/uprobes.txt
@@ -0,0 +1,188 @@
+Title : User-Space Probes (Uprobes)
+Authors : Jim Keniston <[email protected]>
+ : Srikar Dronamraju <[email protected]>
+
+CONTENTS
+
+1. Concepts: Uprobes
+2. Architectures Supported
+3. API Reference
+4. Uprobes Features and Limitations
+5. TODO
+6. Uprobes Team
+
+1. Concepts: Uprobes
+
+Uprobes enables you to dynamically break into any routine in a
+user application and collect debugging and performance information
+non-disruptively. You can trap at any code address, specifying a
+kernel handler routine to be invoked when the breakpoint is hit.
+
+A uprobe can be inserted on any instruction in the application's
+virtual address space. The registration function register_uprobe()
+specifies which process is to be probed, where the probe is to be
+inserted, and what handler is to be called when the probe is hit.
+
+1.1 How Does a Uprobe Work?
+
+When a uprobe is registered, Uprobes makes a copy of the probed
+instruction, stops the probed application, replaces the first byte(s)
+of the probed instruction with a breakpoint instruction (e.g., int3
+on i386 and x86_64), and allows the probed application to continue.
+(When inserting the breakpoint, Uprobes uses background page
+replacement mechanism, so that the breakpoint affects only that
+process, and not any other process running that program. This is
+true even if the probed instruction is in a shared library.)
+
+When a CPU hits the breakpoint instruction, a trap occurs, the CPU's
+user-mode registers are saved, and uprobes notifier code finds the
+associated uprobe. It then executes the handler associated with the
+uprobe, passing the handler the addresses of the uprobe struct and the
+saved registers. The handler can run either in interrupt context or in
+task context; this is specified by the user at the time of registration.
+When run in task context, the handler may block, but keep in mind that
+the probed thread remains stopped while your handler runs.
+
+Next, Uprobes single-steps its copy of the probed instruction and
+resumes execution of the probed process at the instruction following
+the probepoint. (It would be simpler to single-step the actual
+instruction in place, but then Uprobes would have to temporarily
+remove the breakpoint instruction. This would create problems in a
+multithreaded application. For example, it would open a time window
+when another thread could sail right past the probepoint.)
+
+Instruction copies to be single-stepped are stored in a per-process
+"execution out of line (XOL) area," which is a little VM area
+created by Uprobes in each probed process's address space.
+
+Uprobes handles interesting events in the lifetime of the probed
+process, such as fork, clone, exec, and exit.
+
+1.2 Multithreaded Applications
+
+Uprobes supports the probing of multithreaded applications. Uprobes
+imposes no limit on the number of threads in a probed application.
+All threads in a process use the same text pages, so every probe
+in a process affects all threads; of course, each thread hits the
+probepoint (and runs the handler) independently. Multiple threads
+may run the same handler simultaneously. If you want a particular
+thread or set of threads to run a particular handler, your handler
+should check current or current->pid to determine which thread has
+hit the probepoint.
+
+When a process clones a new thread, that thread automatically shares
+all current and future probes established for that process.
+
+2. Architectures Supported
+
+This user_bkpt based version of Uprobes is implemented on the following
+architectures:
+
+- x86
+
+3. API Reference
+
+The Uprobes API includes a "register" function and an "unregister"
+function for uprobes. Here are terse, mini-man-page specifications for
+these functions and the associated probe handlers that you'll write.
+See the latter half of this document for examples.
+
+3.1 register_uprobe
+
+#include <linux/uprobes.h>
+int register_uprobe(struct uprobe *u);
+
+Sets a breakpoint at virtual address u->vaddr in the process whose
+pid is u->pid. When the breakpoint is hit, Uprobes calls u->handler.
+If u->handler_in_interrupt is set, the handler runs in interrupt
+context. Otherwise it runs in task context.
+
+register_uprobe() returns 0 on success, or a negative errno
+otherwise.
+
+User's handler (u->handler):
+#include <linux/uprobes.h>
+#include <linux/ptrace.h>
+void handler(struct uprobe *u, struct pt_regs *regs);
+
+Called with u pointing to the uprobe associated with the breakpoint,
+and regs pointing to the struct containing the registers saved when
+the breakpoint was hit.
+
+3.2 unregister_uprobe
+
+#include <linux/uprobes.h>
+void unregister_uprobe(struct uprobe *u);
+
+Removes the specified probe. The unregister function can be called
+at any time after the probe has been registered, and can be called
+from a uprobe handler.
+
+4. Uprobes Features and Limitations
+
+The user is expected to assign values to the following members
+of struct uprobe: pid, vaddr, handler.
+Uprobes may produce unexpected results if you:
+- change the contents of a uprobe object while it is registered; or
+- attempt to register a uprobe that is already registered.
+
+In this implementation, Uprobes allows only one uprobe at a particular
+address.
+
+Uprobe clients may be used to probe a particular process
+simultaneously, or probe any number of processes simultaneously.
+
+Probes are shared by all threads in a process (including newly
+created threads).
+
+If a probed process exits or execs, Uprobes automatically
+unregisters all uprobes associated with that process. Subsequent
+attempts to unregister these probes will be treated as no-ops.
+
+On the other hand, if a probed memory area is removed from the
+process's virtual memory map (e.g., via dlclose(3) or munmap(2)),
+it's currently up to you to unregister the probes first.
+
+There is no way to specify that probes should be inherited across fork;
+Uprobes removes all probepoints in the newly created child process.
+
+To avoid interfering with interactive debuggers, Uprobes will refuse
+to insert a probepoint where a breakpoint instruction already exists.
+Some architectures may refuse to insert probes on other types of
+instructions.
+
+If you install a probe in an inline-able function, Uprobes makes
+no attempt to chase down all inline instances of the function and
+install probes there. gcc may inline a function without being asked,
+so keep this in mind if you're not seeing the probe hits you expect.
+
+A probe handler can modify the environment of the probed function
+-- e.g., by modifying data structures, or by modifying the
+contents of the pt_regs struct (which are restored to the registers
+upon return from the breakpoint). So Uprobes can be used, for example,
+to install a bug fix or to inject faults for testing. Uprobes, of
+course, has no way to distinguish the deliberately injected faults
+from the accidental ones. Don't drink and probe.
+
+When Uprobes establishes a probepoint on a previous unprobed page of
+text, Linux creates a new copy of the page via background page
+replacement mechanism. When probepoints are removed, Uprobes makes
+no attempt to consolidate identical copies of the same page. This
+could affect memory availability if you probe many, many pages in
+many, many long-running processes.
+
+5. TODO
+
+a. Support for other architectures.
+b. Support for multiple probes at the same address.
+c. Support for boosted probes.
+d. Support return probes.
+
+6. Uprobes Team
+
+The following people have made major contributions to Uprobes:
+Jim Keniston - [email protected]
+Srikar Dronamraju - [email protected]
+Ananth Mavinakayanahalli - [email protected]
+Prasanna Panchamukhi - [email protected]
+Dave Wilder - [email protected]
Move parts of trace_kprobe.c that can be shared with upcoming
trace_uprobe.c. Common code to kernel/trace/trace_probe.h and
kernel/trace/trace_probe.c.
TODO: Merge both events to a single probe event.
Signed-off-by: Srikar Dronamraju <[email protected]>
---
Changelog from V10: delete references to is_kprobe and make
is_return a bool.
Changelog from V7: Merge changes due to string support in kprobes
traceevent.
Changelog from V5: Addressed comments from Masami Hiramatsu
and Steven Rostedt. Also shared lot more code from kprobes
traceevents.
kernel/trace/Kconfig | 4
kernel/trace/Makefile | 1
kernel/trace/trace_kprobe.c | 752 +------------------------------------------
kernel/trace/trace_probe.c | 648 +++++++++++++++++++++++++++++++++++++
kernel/trace/trace_probe.h | 155 +++++++++
5 files changed, 822 insertions(+), 738 deletions(-)
create mode 100644 kernel/trace/trace_probe.c
create mode 100644 kernel/trace/trace_probe.h
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 538501c..d709697 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -353,6 +353,7 @@ config KPROBE_EVENT
depends on HAVE_REGS_AND_STACK_ACCESS_API
bool "Enable kprobes-based dynamic events"
select TRACING
+ select PROBE_EVENTS
default y
help
This allows the user to add tracing events (similar to tracepoints)
@@ -365,6 +366,9 @@ config KPROBE_EVENT
This option is also required by perf-probe subcommand of perf tools.
If you want to use perf tools, this option is strongly recommended.
+config PROBE_EVENTS
+ def_bool n
+
config DYNAMIC_FTRACE
bool "enable/disable ftrace tracepoints dynamically"
depends on FUNCTION_TRACER
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index 53f3381..95d2043 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -56,5 +56,6 @@ obj-$(CONFIG_EVENT_TRACING) += power-traces.o
ifeq ($(CONFIG_TRACING),y)
obj-$(CONFIG_KGDB_KDB) += trace_kdb.o
endif
+obj-$(CONFIG_PROBE_EVENTS) +=trace_probe.o
libftrace-y := ftrace.o
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 8b27c98..e66450d 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -19,463 +19,15 @@
#include <linux/module.h>
#include <linux/uaccess.h>
-#include <linux/kprobes.h>
-#include <linux/seq_file.h>
-#include <linux/slab.h>
-#include <linux/smp.h>
-#include <linux/debugfs.h>
-#include <linux/types.h>
-#include <linux/string.h>
-#include <linux/ctype.h>
-#include <linux/ptrace.h>
-#include <linux/perf_event.h>
-#include <linux/stringify.h>
-#include <linux/limits.h>
-#include <linux/uaccess.h>
-#include <asm/bitsperlong.h>
-#include "trace.h"
-#include "trace_output.h"
+#include "trace_probe.h"
-#define MAX_TRACE_ARGS 128
-#define MAX_ARGSTR_LEN 63
-#define MAX_EVENT_NAME_LEN 64
-#define MAX_STRING_SIZE PATH_MAX
#define KPROBE_EVENT_SYSTEM "kprobes"
-/* Reserved field names */
-#define FIELD_STRING_IP "__probe_ip"
-#define FIELD_STRING_RETIP "__probe_ret_ip"
-#define FIELD_STRING_FUNC "__probe_func"
-
-const char *reserved_field_names[] = {
- "common_type",
- "common_flags",
- "common_preempt_count",
- "common_pid",
- "common_tgid",
- "common_lock_depth",
- FIELD_STRING_IP,
- FIELD_STRING_RETIP,
- FIELD_STRING_FUNC,
-};
-
-/* Printing function type */
-typedef int (*print_type_func_t)(struct trace_seq *, const char *, void *,
- void *);
-#define PRINT_TYPE_FUNC_NAME(type) print_type_##type
-#define PRINT_TYPE_FMT_NAME(type) print_type_format_##type
-
-/* Printing in basic type function template */
-#define DEFINE_BASIC_PRINT_TYPE_FUNC(type, fmt, cast) \
-static __kprobes int PRINT_TYPE_FUNC_NAME(type)(struct trace_seq *s, \
- const char *name, \
- void *data, void *ent)\
-{ \
- return trace_seq_printf(s, " %s=" fmt, name, (cast)*(type *)data);\
-} \
-static const char PRINT_TYPE_FMT_NAME(type)[] = fmt;
-
-DEFINE_BASIC_PRINT_TYPE_FUNC(u8, "%x", unsigned int)
-DEFINE_BASIC_PRINT_TYPE_FUNC(u16, "%x", unsigned int)
-DEFINE_BASIC_PRINT_TYPE_FUNC(u32, "%lx", unsigned long)
-DEFINE_BASIC_PRINT_TYPE_FUNC(u64, "%llx", unsigned long long)
-DEFINE_BASIC_PRINT_TYPE_FUNC(s8, "%d", int)
-DEFINE_BASIC_PRINT_TYPE_FUNC(s16, "%d", int)
-DEFINE_BASIC_PRINT_TYPE_FUNC(s32, "%ld", long)
-DEFINE_BASIC_PRINT_TYPE_FUNC(s64, "%lld", long long)
-
-/* data_rloc: data relative location, compatible with u32 */
-#define make_data_rloc(len, roffs) \
- (((u32)(len) << 16) | ((u32)(roffs) & 0xffff))
-#define get_rloc_len(dl) ((u32)(dl) >> 16)
-#define get_rloc_offs(dl) ((u32)(dl) & 0xffff)
-
-static inline void *get_rloc_data(u32 *dl)
-{
- return (u8 *)dl + get_rloc_offs(*dl);
-}
-
-/* For data_loc conversion */
-static inline void *get_loc_data(u32 *dl, void *ent)
-{
- return (u8 *)ent + get_rloc_offs(*dl);
-}
-
-/*
- * Convert data_rloc to data_loc:
- * data_rloc stores the offset from data_rloc itself, but data_loc
- * stores the offset from event entry.
- */
-#define convert_rloc_to_loc(dl, offs) ((u32)(dl) + (offs))
-
-/* For defining macros, define string/string_size types */
-typedef u32 string;
-typedef u32 string_size;
-
-/* Print type function for string type */
-static __kprobes int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq *s,
- const char *name,
- void *data, void *ent)
-{
- int len = *(u32 *)data >> 16;
-
- if (!len)
- return trace_seq_printf(s, " %s=(fault)", name);
- else
- return trace_seq_printf(s, " %s=\"%s\"", name,
- (const char *)get_loc_data(data, ent));
-}
-static const char PRINT_TYPE_FMT_NAME(string)[] = "\\\"%s\\\"";
-
-/* Data fetch function type */
-typedef void (*fetch_func_t)(struct pt_regs *, void *, void *);
-
-struct fetch_param {
- fetch_func_t fn;
- void *data;
-};
-
-static __kprobes void call_fetch(struct fetch_param *fprm,
- struct pt_regs *regs, void *dest)
-{
- return fprm->fn(regs, fprm->data, dest);
-}
-
-#define FETCH_FUNC_NAME(method, type) fetch_##method##_##type
-/*
- * Define macro for basic types - we don't need to define s* types, because
- * we have to care only about bitwidth at recording time.
- */
-#define DEFINE_BASIC_FETCH_FUNCS(method) \
-DEFINE_FETCH_##method(u8) \
-DEFINE_FETCH_##method(u16) \
-DEFINE_FETCH_##method(u32) \
-DEFINE_FETCH_##method(u64)
-
-#define CHECK_FETCH_FUNCS(method, fn) \
- (((FETCH_FUNC_NAME(method, u8) == fn) || \
- (FETCH_FUNC_NAME(method, u16) == fn) || \
- (FETCH_FUNC_NAME(method, u32) == fn) || \
- (FETCH_FUNC_NAME(method, u64) == fn) || \
- (FETCH_FUNC_NAME(method, string) == fn) || \
- (FETCH_FUNC_NAME(method, string_size) == fn)) \
- && (fn != NULL))
-
-/* Data fetch function templates */
-#define DEFINE_FETCH_reg(type) \
-static __kprobes void FETCH_FUNC_NAME(reg, type)(struct pt_regs *regs, \
- void *offset, void *dest) \
-{ \
- *(type *)dest = (type)regs_get_register(regs, \
- (unsigned int)((unsigned long)offset)); \
-}
-DEFINE_BASIC_FETCH_FUNCS(reg)
-/* No string on the register */
-#define fetch_reg_string NULL
-#define fetch_reg_string_size NULL
-
-#define DEFINE_FETCH_stack(type) \
-static __kprobes void FETCH_FUNC_NAME(stack, type)(struct pt_regs *regs,\
- void *offset, void *dest) \
-{ \
- *(type *)dest = (type)regs_get_kernel_stack_nth(regs, \
- (unsigned int)((unsigned long)offset)); \
-}
-DEFINE_BASIC_FETCH_FUNCS(stack)
-/* No string on the stack entry */
-#define fetch_stack_string NULL
-#define fetch_stack_string_size NULL
-
-#define DEFINE_FETCH_retval(type) \
-static __kprobes void FETCH_FUNC_NAME(retval, type)(struct pt_regs *regs,\
- void *dummy, void *dest) \
-{ \
- *(type *)dest = (type)regs_return_value(regs); \
-}
-DEFINE_BASIC_FETCH_FUNCS(retval)
-/* No string on the retval */
-#define fetch_retval_string NULL
-#define fetch_retval_string_size NULL
-
-#define DEFINE_FETCH_memory(type) \
-static __kprobes void FETCH_FUNC_NAME(memory, type)(struct pt_regs *regs,\
- void *addr, void *dest) \
-{ \
- type retval; \
- if (probe_kernel_address(addr, retval)) \
- *(type *)dest = 0; \
- else \
- *(type *)dest = retval; \
-}
-DEFINE_BASIC_FETCH_FUNCS(memory)
-/*
- * Fetch a null-terminated string. Caller MUST set *(u32 *)dest with max
- * length and relative data location.
- */
-static __kprobes void FETCH_FUNC_NAME(memory, string)(struct pt_regs *regs,
- void *addr, void *dest)
-{
- long ret;
- int maxlen = get_rloc_len(*(u32 *)dest);
- u8 *dst = get_rloc_data(dest);
- u8 *src = addr;
- mm_segment_t old_fs = get_fs();
- if (!maxlen)
- return;
- /*
- * Try to get string again, since the string can be changed while
- * probing.
- */
- set_fs(KERNEL_DS);
- pagefault_disable();
- do
- ret = __copy_from_user_inatomic(dst++, src++, 1);
- while (dst[-1] && ret == 0 && src - (u8 *)addr < maxlen);
- dst[-1] = '\0';
- pagefault_enable();
- set_fs(old_fs);
-
- if (ret < 0) { /* Failed to fetch string */
- ((u8 *)get_rloc_data(dest))[0] = '\0';
- *(u32 *)dest = make_data_rloc(0, get_rloc_offs(*(u32 *)dest));
- } else
- *(u32 *)dest = make_data_rloc(src - (u8 *)addr,
- get_rloc_offs(*(u32 *)dest));
-}
-/* Return the length of string -- including null terminal byte */
-static __kprobes void FETCH_FUNC_NAME(memory, string_size)(struct pt_regs *regs,
- void *addr, void *dest)
-{
- int ret, len = 0;
- u8 c;
- mm_segment_t old_fs = get_fs();
-
- set_fs(KERNEL_DS);
- pagefault_disable();
- do {
- ret = __copy_from_user_inatomic(&c, (u8 *)addr + len, 1);
- len++;
- } while (c && ret == 0 && len < MAX_STRING_SIZE);
- pagefault_enable();
- set_fs(old_fs);
-
- if (ret < 0) /* Failed to check the length */
- *(u32 *)dest = 0;
- else
- *(u32 *)dest = len;
-}
-
-/* Memory fetching by symbol */
-struct symbol_cache {
- char *symbol;
- long offset;
- unsigned long addr;
-};
-
-static unsigned long update_symbol_cache(struct symbol_cache *sc)
-{
- sc->addr = (unsigned long)kallsyms_lookup_name(sc->symbol);
- if (sc->addr)
- sc->addr += sc->offset;
- return sc->addr;
-}
-
-static void free_symbol_cache(struct symbol_cache *sc)
-{
- kfree(sc->symbol);
- kfree(sc);
-}
-
-static struct symbol_cache *alloc_symbol_cache(const char *sym, long offset)
-{
- struct symbol_cache *sc;
-
- if (!sym || strlen(sym) == 0)
- return NULL;
- sc = kzalloc(sizeof(struct symbol_cache), GFP_KERNEL);
- if (!sc)
- return NULL;
-
- sc->symbol = kstrdup(sym, GFP_KERNEL);
- if (!sc->symbol) {
- kfree(sc);
- return NULL;
- }
- sc->offset = offset;
-
- update_symbol_cache(sc);
- return sc;
-}
-
-#define DEFINE_FETCH_symbol(type) \
-static __kprobes void FETCH_FUNC_NAME(symbol, type)(struct pt_regs *regs,\
- void *data, void *dest) \
-{ \
- struct symbol_cache *sc = data; \
- if (sc->addr) \
- fetch_memory_##type(regs, (void *)sc->addr, dest); \
- else \
- *(type *)dest = 0; \
-}
-DEFINE_BASIC_FETCH_FUNCS(symbol)
-DEFINE_FETCH_symbol(string)
-DEFINE_FETCH_symbol(string_size)
-
-/* Dereference memory access function */
-struct deref_fetch_param {
- struct fetch_param orig;
- long offset;
-};
-
-#define DEFINE_FETCH_deref(type) \
-static __kprobes void FETCH_FUNC_NAME(deref, type)(struct pt_regs *regs,\
- void *data, void *dest) \
-{ \
- struct deref_fetch_param *dprm = data; \
- unsigned long addr; \
- call_fetch(&dprm->orig, regs, &addr); \
- if (addr) { \
- addr += dprm->offset; \
- fetch_memory_##type(regs, (void *)addr, dest); \
- } else \
- *(type *)dest = 0; \
-}
-DEFINE_BASIC_FETCH_FUNCS(deref)
-DEFINE_FETCH_deref(string)
-DEFINE_FETCH_deref(string_size)
-
-static __kprobes void free_deref_fetch_param(struct deref_fetch_param *data)
-{
- if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
- free_deref_fetch_param(data->orig.data);
- else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
- free_symbol_cache(data->orig.data);
- kfree(data);
-}
-
-/* Default (unsigned long) fetch type */
-#define __DEFAULT_FETCH_TYPE(t) u##t
-#define _DEFAULT_FETCH_TYPE(t) __DEFAULT_FETCH_TYPE(t)
-#define DEFAULT_FETCH_TYPE _DEFAULT_FETCH_TYPE(BITS_PER_LONG)
-#define DEFAULT_FETCH_TYPE_STR __stringify(DEFAULT_FETCH_TYPE)
-
-/* Fetch types */
-enum {
- FETCH_MTD_reg = 0,
- FETCH_MTD_stack,
- FETCH_MTD_retval,
- FETCH_MTD_memory,
- FETCH_MTD_symbol,
- FETCH_MTD_deref,
- FETCH_MTD_END,
-};
-
-#define ASSIGN_FETCH_FUNC(method, type) \
- [FETCH_MTD_##method] = FETCH_FUNC_NAME(method, type)
-
-#define __ASSIGN_FETCH_TYPE(_name, ptype, ftype, _size, sign, _fmttype) \
- {.name = _name, \
- .size = _size, \
- .is_signed = sign, \
- .print = PRINT_TYPE_FUNC_NAME(ptype), \
- .fmt = PRINT_TYPE_FMT_NAME(ptype), \
- .fmttype = _fmttype, \
- .fetch = { \
-ASSIGN_FETCH_FUNC(reg, ftype), \
-ASSIGN_FETCH_FUNC(stack, ftype), \
-ASSIGN_FETCH_FUNC(retval, ftype), \
-ASSIGN_FETCH_FUNC(memory, ftype), \
-ASSIGN_FETCH_FUNC(symbol, ftype), \
-ASSIGN_FETCH_FUNC(deref, ftype), \
- } \
- }
-
-#define ASSIGN_FETCH_TYPE(ptype, ftype, sign) \
- __ASSIGN_FETCH_TYPE(#ptype, ptype, ftype, sizeof(ftype), sign, #ptype)
-
-#define FETCH_TYPE_STRING 0
-#define FETCH_TYPE_STRSIZE 1
-
-/* Fetch type information table */
-static const struct fetch_type {
- const char *name; /* Name of type */
- size_t size; /* Byte size of type */
- int is_signed; /* Signed flag */
- print_type_func_t print; /* Print functions */
- const char *fmt; /* Fromat string */
- const char *fmttype; /* Name in format file */
- /* Fetch functions */
- fetch_func_t fetch[FETCH_MTD_END];
-} fetch_type_table[] = {
- /* Special types */
- [FETCH_TYPE_STRING] = __ASSIGN_FETCH_TYPE("string", string, string,
- sizeof(u32), 1, "__data_loc char[]"),
- [FETCH_TYPE_STRSIZE] = __ASSIGN_FETCH_TYPE("string_size", u32,
- string_size, sizeof(u32), 0, "u32"),
- /* Basic types */
- ASSIGN_FETCH_TYPE(u8, u8, 0),
- ASSIGN_FETCH_TYPE(u16, u16, 0),
- ASSIGN_FETCH_TYPE(u32, u32, 0),
- ASSIGN_FETCH_TYPE(u64, u64, 0),
- ASSIGN_FETCH_TYPE(s8, u8, 1),
- ASSIGN_FETCH_TYPE(s16, u16, 1),
- ASSIGN_FETCH_TYPE(s32, u32, 1),
- ASSIGN_FETCH_TYPE(s64, u64, 1),
-};
-
-static const struct fetch_type *find_fetch_type(const char *type)
-{
- int i;
-
- if (!type)
- type = DEFAULT_FETCH_TYPE_STR;
-
- for (i = 0; i < ARRAY_SIZE(fetch_type_table); i++)
- if (strcmp(type, fetch_type_table[i].name) == 0)
- return &fetch_type_table[i];
- return NULL;
-}
-
-/* Special function : only accept unsigned long */
-static __kprobes void fetch_stack_address(struct pt_regs *regs,
- void *dummy, void *dest)
-{
- *(unsigned long *)dest = kernel_stack_pointer(regs);
-}
-
-static fetch_func_t get_fetch_size_function(const struct fetch_type *type,
- fetch_func_t orig_fn)
-{
- int i;
-
- if (type != &fetch_type_table[FETCH_TYPE_STRING])
- return NULL; /* Only string type needs size function */
- for (i = 0; i < FETCH_MTD_END; i++)
- if (type->fetch[i] == orig_fn)
- return fetch_type_table[FETCH_TYPE_STRSIZE].fetch[i];
-
- WARN_ON(1); /* This should not happen */
- return NULL;
-}
-
/**
* Kprobe event core functions
*/
-struct probe_arg {
- struct fetch_param fetch;
- struct fetch_param fetch_size;
- unsigned int offset; /* Offset from argument entry */
- const char *name; /* Name of this argument */
- const char *comm; /* Command of this argument */
- const struct fetch_type *type; /* Type of this argument */
-};
-
-/* Flags for trace_probe */
-#define TP_FLAG_TRACE 1
-#define TP_FLAG_PROFILE 2
-
struct trace_probe {
struct list_head list;
struct kretprobe rp; /* Use rp.kp for kprobe use */
@@ -513,19 +65,6 @@ static LIST_HEAD(probe_list);
static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs);
static int kretprobe_dispatcher(struct kretprobe_instance *ri,
struct pt_regs *regs);
-
-/* Check the name is good for event/group */
-static int check_event_name(const char *name)
-{
- if (!isalpha(*name) && *name != '_')
- return 0;
- while (*++name != '\0') {
- if (!isalpha(*name) && !isdigit(*name) && *name != '_')
- return 0;
- }
- return 1;
-}
-
/*
* Allocate new trace_probe and initialize it (including kprobes).
*/
@@ -534,7 +73,7 @@ static struct trace_probe *alloc_trace_probe(const char *group,
void *addr,
const char *symbol,
unsigned long offs,
- int nargs, int is_return)
+ int nargs, bool is_return)
{
struct trace_probe *tp;
int ret = -ENOMEM;
@@ -585,22 +124,12 @@ error:
return ERR_PTR(ret);
}
-static void free_probe_arg(struct probe_arg *arg)
-{
- if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))
- free_deref_fetch_param(arg->fetch.data);
- else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))
- free_symbol_cache(arg->fetch.data);
- kfree(arg->name);
- kfree(arg->comm);
-}
-
static void free_trace_probe(struct trace_probe *tp)
{
int i;
for (i = 0; i < tp->nr_args; i++)
- free_probe_arg(&tp->args[i]);
+ traceprobe_free_probe_arg(&tp->args[i]);
kfree(tp->call.class->system);
kfree(tp->call.name);
@@ -674,191 +203,6 @@ end:
return ret;
}
-/* Split symbol and offset. */
-static int split_symbol_offset(char *symbol, unsigned long *offset)
-{
- char *tmp;
- int ret;
-
- if (!offset)
- return -EINVAL;
-
- tmp = strchr(symbol, '+');
- if (tmp) {
- /* skip sign because strict_strtol doesn't accept '+' */
- ret = strict_strtoul(tmp + 1, 0, offset);
- if (ret)
- return ret;
- *tmp = '\0';
- } else
- *offset = 0;
- return 0;
-}
-
-#define PARAM_MAX_ARGS 16
-#define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
-
-static int parse_probe_vars(char *arg, const struct fetch_type *t,
- struct fetch_param *f, int is_return)
-{
- int ret = 0;
- unsigned long param;
-
- if (strcmp(arg, "retval") == 0) {
- if (is_return)
- f->fn = t->fetch[FETCH_MTD_retval];
- else
- ret = -EINVAL;
- } else if (strncmp(arg, "stack", 5) == 0) {
- if (arg[5] == '\0') {
- if (strcmp(t->name, DEFAULT_FETCH_TYPE_STR) == 0)
- f->fn = fetch_stack_address;
- else
- ret = -EINVAL;
- } else if (isdigit(arg[5])) {
- ret = strict_strtoul(arg + 5, 10, ¶m);
- if (ret || param > PARAM_MAX_STACK)
- ret = -EINVAL;
- else {
- f->fn = t->fetch[FETCH_MTD_stack];
- f->data = (void *)param;
- }
- } else
- ret = -EINVAL;
- } else
- ret = -EINVAL;
- return ret;
-}
-
-/* Recursive argument parser */
-static int __parse_probe_arg(char *arg, const struct fetch_type *t,
- struct fetch_param *f, int is_return)
-{
- int ret = 0;
- unsigned long param;
- long offset;
- char *tmp;
-
- switch (arg[0]) {
- case '$':
- ret = parse_probe_vars(arg + 1, t, f, is_return);
- break;
- case '%': /* named register */
- ret = regs_query_register_offset(arg + 1);
- if (ret >= 0) {
- f->fn = t->fetch[FETCH_MTD_reg];
- f->data = (void *)(unsigned long)ret;
- ret = 0;
- }
- break;
- case '@': /* memory or symbol */
- if (isdigit(arg[1])) {
- ret = strict_strtoul(arg + 1, 0, ¶m);
- if (ret)
- break;
- f->fn = t->fetch[FETCH_MTD_memory];
- f->data = (void *)param;
- } else {
- ret = split_symbol_offset(arg + 1, &offset);
- if (ret)
- break;
- f->data = alloc_symbol_cache(arg + 1, offset);
- if (f->data)
- f->fn = t->fetch[FETCH_MTD_symbol];
- }
- break;
- case '+': /* deref memory */
- case '-':
- tmp = strchr(arg, '(');
- if (!tmp)
- break;
- *tmp = '\0';
- ret = strict_strtol(arg + 1, 0, &offset);
- if (ret)
- break;
- if (arg[0] == '-')
- offset = -offset;
- arg = tmp + 1;
- tmp = strrchr(arg, ')');
- if (tmp) {
- struct deref_fetch_param *dprm;
- const struct fetch_type *t2 = find_fetch_type(NULL);
- *tmp = '\0';
- dprm = kzalloc(sizeof(struct deref_fetch_param),
- GFP_KERNEL);
- if (!dprm)
- return -ENOMEM;
- dprm->offset = offset;
- ret = __parse_probe_arg(arg, t2, &dprm->orig,
- is_return);
- if (ret)
- kfree(dprm);
- else {
- f->fn = t->fetch[FETCH_MTD_deref];
- f->data = (void *)dprm;
- }
- }
- break;
- }
- if (!ret && !f->fn) { /* Parsed, but do not find fetch method */
- pr_info("%s type has no corresponding fetch method.\n",
- t->name);
- ret = -EINVAL;
- }
- return ret;
-}
-
-/* String length checking wrapper */
-static int parse_probe_arg(char *arg, struct trace_probe *tp,
- struct probe_arg *parg, int is_return)
-{
- const char *t;
- int ret;
-
- if (strlen(arg) > MAX_ARGSTR_LEN) {
- pr_info("Argument is too long.: %s\n", arg);
- return -ENOSPC;
- }
- parg->comm = kstrdup(arg, GFP_KERNEL);
- if (!parg->comm) {
- pr_info("Failed to allocate memory for command '%s'.\n", arg);
- return -ENOMEM;
- }
- t = strchr(parg->comm, ':');
- if (t) {
- arg[t - parg->comm] = '\0';
- t++;
- }
- parg->type = find_fetch_type(t);
- if (!parg->type) {
- pr_info("Unsupported type: %s\n", t);
- return -EINVAL;
- }
- parg->offset = tp->size;
- tp->size += parg->type->size;
- ret = __parse_probe_arg(arg, parg->type, &parg->fetch, is_return);
- if (ret >= 0) {
- parg->fetch_size.fn = get_fetch_size_function(parg->type,
- parg->fetch.fn);
- parg->fetch_size.data = parg->fetch.data;
- }
- return ret;
-}
-
-/* Return 1 if name is reserved or already used by another argument */
-static int conflict_field_name(const char *name,
- struct probe_arg *args, int narg)
-{
- int i;
- for (i = 0; i < ARRAY_SIZE(reserved_field_names); i++)
- if (strcmp(reserved_field_names[i], name) == 0)
- return 1;
- for (i = 0; i < narg; i++)
- if (strcmp(args[i].name, name) == 0)
- return 1;
- return 0;
-}
-
static int create_trace_probe(int argc, char **argv)
{
/*
@@ -881,7 +225,7 @@ static int create_trace_probe(int argc, char **argv)
*/
struct trace_probe *tp;
int i, ret = 0;
- int is_return = 0, is_delete = 0;
+ bool is_return = false, is_delete = false;
char *symbol = NULL, *event = NULL, *group = NULL;
char *arg, *tmp;
unsigned long offset = 0;
@@ -890,11 +234,11 @@ static int create_trace_probe(int argc, char **argv)
/* argc must be >= 1 */
if (argv[0][0] == 'p')
- is_return = 0;
+ is_return = false;
else if (argv[0][0] == 'r')
- is_return = 1;
+ is_return = true;
else if (argv[0][0] == '-')
- is_delete = 1;
+ is_delete = true;
else {
pr_info("Probe definition must be started with 'p', 'r' or"
" '-'.\n");
@@ -958,7 +302,7 @@ static int create_trace_probe(int argc, char **argv)
/* a symbol specified */
symbol = argv[1];
/* TODO: support .init module functions */
- ret = split_symbol_offset(symbol, &offset);
+ ret = traceprobe_split_symbol_offset(symbol, &offset);
if (ret) {
pr_info("Failed to parse symbol.\n");
return ret;
@@ -1010,7 +354,8 @@ static int create_trace_probe(int argc, char **argv)
if (tmp)
*tmp = '_'; /* convert : to _ */
- if (conflict_field_name(tp->args[i].name, tp->args, i)) {
+ if (traceprobe_conflict_field_name(tp->args[i].name,
+ tp->args, i)) {
pr_info("Argument%d name '%s' conflicts with "
"another field.\n", i, argv[i]);
ret = -EINVAL;
@@ -1018,7 +363,8 @@ static int create_trace_probe(int argc, char **argv)
}
/* Parse fetch argument */
- ret = parse_probe_arg(arg, tp, &tp->args[i], is_return);
+ ret = traceprobe_parse_probe_arg(arg, &tp->size, &tp->args[i],
+ is_return);
if (ret) {
pr_info("Parse error at argument%d. (%d)\n", i, ret);
kfree(tp->args[i].name);
@@ -1108,70 +454,11 @@ static int probes_open(struct inode *inode, struct file *file)
return seq_open(file, &probes_seq_op);
}
-static int command_trace_probe(const char *buf)
-{
- char **argv;
- int argc = 0, ret = 0;
-
- argv = argv_split(GFP_KERNEL, buf, &argc);
- if (!argv)
- return -ENOMEM;
-
- if (argc)
- ret = create_trace_probe(argc, argv);
-
- argv_free(argv);
- return ret;
-}
-
-#define WRITE_BUFSIZE 128
-
static ssize_t probes_write(struct file *file, const char __user *buffer,
size_t count, loff_t *ppos)
{
- char *kbuf, *tmp;
- int ret;
- size_t done;
- size_t size;
-
- kbuf = kmalloc(WRITE_BUFSIZE, GFP_KERNEL);
- if (!kbuf)
- return -ENOMEM;
-
- ret = done = 0;
- while (done < count) {
- size = count - done;
- if (size >= WRITE_BUFSIZE)
- size = WRITE_BUFSIZE - 1;
- if (copy_from_user(kbuf, buffer + done, size)) {
- ret = -EFAULT;
- goto out;
- }
- kbuf[size] = '\0';
- tmp = strchr(kbuf, '\n');
- if (tmp) {
- *tmp = '\0';
- size = tmp - kbuf + 1;
- } else if (done + size < count) {
- pr_warning("Line length is too long: "
- "Should be less than %d.", WRITE_BUFSIZE);
- ret = -EINVAL;
- goto out;
- }
- done += size;
- /* Remove comments */
- tmp = strchr(kbuf, '#');
- if (tmp)
- *tmp = '\0';
-
- ret = command_trace_probe(kbuf);
- if (ret)
- goto out;
- }
- ret = done;
-out:
- kfree(kbuf);
- return ret;
+ return traceprobe_probes_write(file, buffer, count, ppos,
+ create_trace_probe);
}
static const struct file_operations kprobe_events_ops = {
@@ -1429,17 +716,6 @@ static void probe_event_disable(struct ftrace_event_call *call)
}
}
-#undef DEFINE_FIELD
-#define DEFINE_FIELD(type, item, name, is_signed) \
- do { \
- ret = trace_define_field(event_call, #type, name, \
- offsetof(typeof(field), item), \
- sizeof(field.item), is_signed, \
- FILTER_OTHER); \
- if (ret) \
- return ret; \
- } while (0)
-
static int kprobe_event_define_fields(struct ftrace_event_call *event_call)
{
int ret, i;
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
new file mode 100644
index 0000000..4ca48c6
--- /dev/null
+++ b/kernel/trace/trace_probe.c
@@ -0,0 +1,648 @@
+/*
+ * Common code for probe-based Dynamic events.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Copyright (C) IBM Corporation, 2010
+ * Author: Srikar Dronamraju
+ *
+ * Derived from kernel/trace/trace_kprobe.c written by
+ * Masami Hiramatsu <[email protected]>
+ */
+
+#include "trace_probe.h"
+
+const char *reserved_field_names[] = {
+ "common_type",
+ "common_flags",
+ "common_preempt_count",
+ "common_pid",
+ "common_tgid",
+ "common_lock_depth",
+ FIELD_STRING_IP,
+ FIELD_STRING_RETIP,
+ FIELD_STRING_FUNC,
+};
+
+/* Printing function type */
+#define PRINT_TYPE_FUNC_NAME(type) print_type_##type
+#define PRINT_TYPE_FMT_NAME(type) print_type_format_##type
+
+/* Printing in basic type function template */
+#define DEFINE_BASIC_PRINT_TYPE_FUNC(type, fmt, cast) \
+static __kprobes int PRINT_TYPE_FUNC_NAME(type)(struct trace_seq *s, \
+ const char *name, \
+ void *data, void *ent)\
+{ \
+ return trace_seq_printf(s, " %s=" fmt, name, (cast)*(type *)data);\
+} \
+static const char PRINT_TYPE_FMT_NAME(type)[] = fmt;
+
+DEFINE_BASIC_PRINT_TYPE_FUNC(u8, "%x", unsigned int)
+DEFINE_BASIC_PRINT_TYPE_FUNC(u16, "%x", unsigned int)
+DEFINE_BASIC_PRINT_TYPE_FUNC(u32, "%lx", unsigned long)
+DEFINE_BASIC_PRINT_TYPE_FUNC(u64, "%llx", unsigned long long)
+DEFINE_BASIC_PRINT_TYPE_FUNC(s8, "%d", int)
+DEFINE_BASIC_PRINT_TYPE_FUNC(s16, "%d", int)
+DEFINE_BASIC_PRINT_TYPE_FUNC(s32, "%ld", long)
+DEFINE_BASIC_PRINT_TYPE_FUNC(s64, "%lld", long long)
+
+static inline void *get_rloc_data(u32 *dl)
+{
+ return (u8 *)dl + get_rloc_offs(*dl);
+}
+
+/* For data_loc conversion */
+static inline void *get_loc_data(u32 *dl, void *ent)
+{
+ return (u8 *)ent + get_rloc_offs(*dl);
+}
+
+/* For defining macros, define string/string_size types */
+typedef u32 string;
+typedef u32 string_size;
+
+/* Print type function for string type */
+static __kprobes int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq *s,
+ const char *name,
+ void *data, void *ent)
+{
+ int len = *(u32 *)data >> 16;
+
+ if (!len)
+ return trace_seq_printf(s, " %s=(fault)", name);
+ else
+ return trace_seq_printf(s, " %s=\"%s\"", name,
+ (const char *)get_loc_data(data, ent));
+}
+static const char PRINT_TYPE_FMT_NAME(string)[] = "\\\"%s\\\"";
+
+#define FETCH_FUNC_NAME(method, type) fetch_##method##_##type
+/*
+ * Define macro for basic types - we don't need to define s* types, because
+ * we have to care only about bitwidth at recording time.
+ */
+#define DEFINE_BASIC_FETCH_FUNCS(method) \
+DEFINE_FETCH_##method(u8) \
+DEFINE_FETCH_##method(u16) \
+DEFINE_FETCH_##method(u32) \
+DEFINE_FETCH_##method(u64)
+
+#define CHECK_FETCH_FUNCS(method, fn) \
+ (((FETCH_FUNC_NAME(method, u8) == fn) || \
+ (FETCH_FUNC_NAME(method, u16) == fn) || \
+ (FETCH_FUNC_NAME(method, u32) == fn) || \
+ (FETCH_FUNC_NAME(method, u64) == fn) || \
+ (FETCH_FUNC_NAME(method, string) == fn) || \
+ (FETCH_FUNC_NAME(method, string_size) == fn)) \
+ && (fn != NULL))
+
+/* Data fetch function templates */
+#define DEFINE_FETCH_reg(type) \
+static __kprobes void FETCH_FUNC_NAME(reg, type)(struct pt_regs *regs, \
+ void *offset, void *dest) \
+{ \
+ *(type *)dest = (type)regs_get_register(regs, \
+ (unsigned int)((unsigned long)offset)); \
+}
+DEFINE_BASIC_FETCH_FUNCS(reg)
+/* No string on the register */
+#define fetch_reg_string NULL
+#define fetch_reg_string_size NULL
+
+#define DEFINE_FETCH_stack(type) \
+static __kprobes void FETCH_FUNC_NAME(stack, type)(struct pt_regs *regs,\
+ void *offset, void *dest) \
+{ \
+ *(type *)dest = (type)regs_get_kernel_stack_nth(regs, \
+ (unsigned int)((unsigned long)offset)); \
+}
+DEFINE_BASIC_FETCH_FUNCS(stack)
+/* No string on the stack entry */
+#define fetch_stack_string NULL
+#define fetch_stack_string_size NULL
+
+#define DEFINE_FETCH_retval(type) \
+static __kprobes void FETCH_FUNC_NAME(retval, type)(struct pt_regs *regs,\
+ void *dummy, void *dest) \
+{ \
+ *(type *)dest = (type)regs_return_value(regs); \
+}
+DEFINE_BASIC_FETCH_FUNCS(retval)
+/* No string on the retval */
+#define fetch_retval_string NULL
+#define fetch_retval_string_size NULL
+
+#define DEFINE_FETCH_memory(type) \
+static __kprobes void FETCH_FUNC_NAME(memory, type)(struct pt_regs *regs,\
+ void *addr, void *dest) \
+{ \
+ type retval; \
+ if (probe_kernel_address(addr, retval)) \
+ *(type *)dest = 0; \
+ else \
+ *(type *)dest = retval; \
+}
+DEFINE_BASIC_FETCH_FUNCS(memory)
+/*
+ * Fetch a null-terminated string. Caller MUST set *(u32 *)dest with max
+ * length and relative data location.
+ */
+static __kprobes void FETCH_FUNC_NAME(memory, string)(struct pt_regs *regs,
+ void *addr, void *dest)
+{
+ long ret;
+ int maxlen = get_rloc_len(*(u32 *)dest);
+ u8 *dst = get_rloc_data(dest);
+ u8 *src = addr;
+ mm_segment_t old_fs = get_fs();
+ if (!maxlen)
+ return;
+ /*
+ * Try to get string again, since the string can be changed while
+ * probing.
+ */
+ set_fs(KERNEL_DS);
+ pagefault_disable();
+ do
+ ret = __copy_from_user_inatomic(dst++, src++, 1);
+ while (dst[-1] && ret == 0 && src - (u8 *)addr < maxlen);
+ dst[-1] = '\0';
+ pagefault_enable();
+ set_fs(old_fs);
+
+ if (ret < 0) { /* Failed to fetch string */
+ ((u8 *)get_rloc_data(dest))[0] = '\0';
+ *(u32 *)dest = make_data_rloc(0, get_rloc_offs(*(u32 *)dest));
+ } else
+ *(u32 *)dest = make_data_rloc(src - (u8 *)addr,
+ get_rloc_offs(*(u32 *)dest));
+}
+/* Return the length of string -- including null terminal byte */
+static __kprobes void FETCH_FUNC_NAME(memory, string_size)(struct pt_regs *regs,
+ void *addr, void *dest)
+{
+ int ret, len = 0;
+ u8 c;
+ mm_segment_t old_fs = get_fs();
+
+ set_fs(KERNEL_DS);
+ pagefault_disable();
+ do {
+ ret = __copy_from_user_inatomic(&c, (u8 *)addr + len, 1);
+ len++;
+ } while (c && ret == 0 && len < MAX_STRING_SIZE);
+ pagefault_enable();
+ set_fs(old_fs);
+
+ if (ret < 0) /* Failed to check the length */
+ *(u32 *)dest = 0;
+ else
+ *(u32 *)dest = len;
+}
+
+/* Memory fetching by symbol */
+struct symbol_cache {
+ char *symbol;
+ long offset;
+ unsigned long addr;
+};
+
+static unsigned long update_symbol_cache(struct symbol_cache *sc)
+{
+ sc->addr = (unsigned long)kallsyms_lookup_name(sc->symbol);
+ if (sc->addr)
+ sc->addr += sc->offset;
+ return sc->addr;
+}
+
+static void free_symbol_cache(struct symbol_cache *sc)
+{
+ kfree(sc->symbol);
+ kfree(sc);
+}
+
+static struct symbol_cache *alloc_symbol_cache(const char *sym, long offset)
+{
+ struct symbol_cache *sc;
+
+ if (!sym || strlen(sym) == 0)
+ return NULL;
+ sc = kzalloc(sizeof(struct symbol_cache), GFP_KERNEL);
+ if (!sc)
+ return NULL;
+
+ sc->symbol = kstrdup(sym, GFP_KERNEL);
+ if (!sc->symbol) {
+ kfree(sc);
+ return NULL;
+ }
+ sc->offset = offset;
+
+ update_symbol_cache(sc);
+ return sc;
+}
+
+#define DEFINE_FETCH_symbol(type) \
+static __kprobes void FETCH_FUNC_NAME(symbol, type)(struct pt_regs *regs,\
+ void *data, void *dest) \
+{ \
+ struct symbol_cache *sc = data; \
+ if (sc->addr) \
+ fetch_memory_##type(regs, (void *)sc->addr, dest); \
+ else \
+ *(type *)dest = 0; \
+}
+DEFINE_BASIC_FETCH_FUNCS(symbol)
+DEFINE_FETCH_symbol(string)
+DEFINE_FETCH_symbol(string_size)
+
+/* Dereference memory access function */
+struct deref_fetch_param {
+ struct fetch_param orig;
+ long offset;
+};
+
+#define DEFINE_FETCH_deref(type) \
+static __kprobes void FETCH_FUNC_NAME(deref, type)(struct pt_regs *regs,\
+ void *data, void *dest) \
+{ \
+ struct deref_fetch_param *dprm = data; \
+ unsigned long addr; \
+ call_fetch(&dprm->orig, regs, &addr); \
+ if (addr) { \
+ addr += dprm->offset; \
+ fetch_memory_##type(regs, (void *)addr, dest); \
+ } else \
+ *(type *)dest = 0; \
+}
+DEFINE_BASIC_FETCH_FUNCS(deref)
+DEFINE_FETCH_deref(string)
+DEFINE_FETCH_deref(string_size)
+
+static __kprobes void free_deref_fetch_param(struct deref_fetch_param *data)
+{
+ if (CHECK_FETCH_FUNCS(deref, data->orig.fn))
+ free_deref_fetch_param(data->orig.data);
+ else if (CHECK_FETCH_FUNCS(symbol, data->orig.fn))
+ free_symbol_cache(data->orig.data);
+ kfree(data);
+}
+
+/* Default (unsigned long) fetch type */
+#define __DEFAULT_FETCH_TYPE(t) u##t
+#define _DEFAULT_FETCH_TYPE(t) __DEFAULT_FETCH_TYPE(t)
+#define DEFAULT_FETCH_TYPE _DEFAULT_FETCH_TYPE(BITS_PER_LONG)
+#define DEFAULT_FETCH_TYPE_STR __stringify(DEFAULT_FETCH_TYPE)
+
+#define ASSIGN_FETCH_FUNC(method, type) \
+ [FETCH_MTD_##method] = FETCH_FUNC_NAME(method, type)
+
+#define __ASSIGN_FETCH_TYPE(_name, ptype, ftype, _size, sign, _fmttype) \
+ {.name = _name, \
+ .size = _size, \
+ .is_signed = sign, \
+ .print = PRINT_TYPE_FUNC_NAME(ptype), \
+ .fmt = PRINT_TYPE_FMT_NAME(ptype), \
+ .fmttype = _fmttype, \
+ .fetch = { \
+ASSIGN_FETCH_FUNC(reg, ftype), \
+ASSIGN_FETCH_FUNC(stack, ftype), \
+ASSIGN_FETCH_FUNC(retval, ftype), \
+ASSIGN_FETCH_FUNC(memory, ftype), \
+ASSIGN_FETCH_FUNC(symbol, ftype), \
+ASSIGN_FETCH_FUNC(deref, ftype), \
+ } \
+ }
+
+#define ASSIGN_FETCH_TYPE(ptype, ftype, sign) \
+ __ASSIGN_FETCH_TYPE(#ptype, ptype, ftype, sizeof(ftype), sign, #ptype)
+
+#define FETCH_TYPE_STRING 0
+#define FETCH_TYPE_STRSIZE 1
+
+/* Fetch type information table */
+static const struct fetch_type fetch_type_table[] = {
+ /* Special types */
+ [FETCH_TYPE_STRING] = __ASSIGN_FETCH_TYPE("string", string, string,
+ sizeof(u32), 1, "__data_loc char[]"),
+ [FETCH_TYPE_STRSIZE] = __ASSIGN_FETCH_TYPE("string_size", u32,
+ string_size, sizeof(u32), 0, "u32"),
+ /* Basic types */
+ ASSIGN_FETCH_TYPE(u8, u8, 0),
+ ASSIGN_FETCH_TYPE(u16, u16, 0),
+ ASSIGN_FETCH_TYPE(u32, u32, 0),
+ ASSIGN_FETCH_TYPE(u64, u64, 0),
+ ASSIGN_FETCH_TYPE(s8, u8, 1),
+ ASSIGN_FETCH_TYPE(s16, u16, 1),
+ ASSIGN_FETCH_TYPE(s32, u32, 1),
+ ASSIGN_FETCH_TYPE(s64, u64, 1),
+};
+
+static const struct fetch_type *find_fetch_type(const char *type)
+{
+ int i;
+
+ if (!type)
+ type = DEFAULT_FETCH_TYPE_STR;
+
+ for (i = 0; i < ARRAY_SIZE(fetch_type_table); i++)
+ if (strcmp(type, fetch_type_table[i].name) == 0)
+ return &fetch_type_table[i];
+ return NULL;
+}
+
+/* Special function : only accept unsigned long */
+static __kprobes void fetch_stack_address(struct pt_regs *regs,
+ void *dummy, void *dest)
+{
+ *(unsigned long *)dest = kernel_stack_pointer(regs);
+}
+
+static fetch_func_t get_fetch_size_function(const struct fetch_type *type,
+ fetch_func_t orig_fn)
+{
+ int i;
+
+ if (type != &fetch_type_table[FETCH_TYPE_STRING])
+ return NULL; /* Only string type needs size function */
+ for (i = 0; i < FETCH_MTD_END; i++)
+ if (type->fetch[i] == orig_fn)
+ return fetch_type_table[FETCH_TYPE_STRSIZE].fetch[i];
+
+ WARN_ON(1); /* This should not happen */
+ return NULL;
+}
+
+/* Split symbol and offset. */
+int traceprobe_split_symbol_offset(char *symbol, unsigned long *offset)
+{
+ char *tmp;
+ int ret;
+
+ if (!offset)
+ return -EINVAL;
+
+ tmp = strchr(symbol, '+');
+ if (tmp) {
+ /* skip sign because strict_strtol doesn't accept '+' */
+ ret = strict_strtoul(tmp + 1, 0, offset);
+ if (ret)
+ return ret;
+ *tmp = '\0';
+ } else
+ *offset = 0;
+ return 0;
+}
+
+
+#define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
+
+static int parse_probe_vars(char *arg, const struct fetch_type *t,
+ struct fetch_param *f, bool is_return)
+{
+ int ret = 0;
+ unsigned long param;
+
+ if (strcmp(arg, "retval") == 0) {
+ if (is_return)
+ f->fn = t->fetch[FETCH_MTD_retval];
+ else
+ ret = -EINVAL;
+ } else if (strncmp(arg, "stack", 5) == 0) {
+ if (arg[5] == '\0') {
+ if (strcmp(t->name, DEFAULT_FETCH_TYPE_STR) == 0)
+ f->fn = fetch_stack_address;
+ else
+ ret = -EINVAL;
+ } else if (isdigit(arg[5])) {
+ ret = strict_strtoul(arg + 5, 10, ¶m);
+ if (ret || param > PARAM_MAX_STACK)
+ ret = -EINVAL;
+ else {
+ f->fn = t->fetch[FETCH_MTD_stack];
+ f->data = (void *)param;
+ }
+ } else
+ ret = -EINVAL;
+ } else
+ ret = -EINVAL;
+ return ret;
+}
+
+/* Recursive argument parser */
+static int parse_probe_arg(char *arg, const struct fetch_type *t,
+ struct fetch_param *f, bool is_return)
+{
+ int ret = 0;
+ unsigned long param;
+ long offset;
+ char *tmp;
+
+ switch (arg[0]) {
+ case '$':
+ ret = parse_probe_vars(arg + 1, t, f, is_return);
+ break;
+ case '%': /* named register */
+ ret = regs_query_register_offset(arg + 1);
+ if (ret >= 0) {
+ f->fn = t->fetch[FETCH_MTD_reg];
+ f->data = (void *)(unsigned long)ret;
+ ret = 0;
+ }
+ break;
+ case '@': /* memory or symbol */
+ if (isdigit(arg[1])) {
+ ret = strict_strtoul(arg + 1, 0, ¶m);
+ if (ret)
+ break;
+ f->fn = t->fetch[FETCH_MTD_memory];
+ f->data = (void *)param;
+ } else {
+ ret = traceprobe_split_symbol_offset(arg + 1, &offset);
+ if (ret)
+ break;
+ f->data = alloc_symbol_cache(arg + 1, offset);
+ if (f->data)
+ f->fn = t->fetch[FETCH_MTD_symbol];
+ }
+ break;
+ case '+': /* deref memory */
+ case '-':
+ tmp = strchr(arg, '(');
+ if (!tmp)
+ break;
+ *tmp = '\0';
+ ret = strict_strtol(arg + 1, 0, &offset);
+ if (ret)
+ break;
+ if (arg[0] == '-')
+ offset = -offset;
+ arg = tmp + 1;
+ tmp = strrchr(arg, ')');
+ if (tmp) {
+ struct deref_fetch_param *dprm;
+ const struct fetch_type *t2 = find_fetch_type(NULL);
+ *tmp = '\0';
+ dprm = kzalloc(sizeof(struct deref_fetch_param),
+ GFP_KERNEL);
+ if (!dprm)
+ return -ENOMEM;
+ dprm->offset = offset;
+ ret = parse_probe_arg(arg, t2, &dprm->orig, is_return);
+ if (ret)
+ kfree(dprm);
+ else {
+ f->fn = t->fetch[FETCH_MTD_deref];
+ f->data = (void *)dprm;
+ }
+ }
+ break;
+ }
+ if (!ret && !f->fn) { /* Parsed, but do not find fetch method */
+ pr_info("%s type has no corresponding fetch method.\n",
+ t->name);
+ ret = -EINVAL;
+ }
+ return ret;
+}
+
+/* String length checking wrapper */
+int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
+ struct probe_arg *parg, bool is_return)
+{
+ const char *t;
+ int ret;
+
+ if (strlen(arg) > MAX_ARGSTR_LEN) {
+ pr_info("Argument is too long.: %s\n", arg);
+ return -ENOSPC;
+ }
+ parg->comm = kstrdup(arg, GFP_KERNEL);
+ if (!parg->comm) {
+ pr_info("Failed to allocate memory for command '%s'.\n", arg);
+ return -ENOMEM;
+ }
+ t = strchr(parg->comm, ':');
+ if (t) {
+ arg[t - parg->comm] = '\0';
+ t++;
+ }
+ parg->type = find_fetch_type(t);
+ if (!parg->type) {
+ pr_info("Unsupported type: %s\n", t);
+ return -EINVAL;
+ }
+ parg->offset = *size;
+ *size += parg->type->size;
+ ret = parse_probe_arg(arg, parg->type, &parg->fetch, is_return);
+
+ if (ret >= 0) {
+ parg->fetch_size.fn = get_fetch_size_function(parg->type,
+ parg->fetch.fn);
+ parg->fetch_size.data = parg->fetch.data;
+ }
+ return ret;
+}
+
+/* Return 1 if name is reserved or already used by another argument */
+int traceprobe_conflict_field_name(const char *name,
+ struct probe_arg *args, int narg)
+{
+ int i;
+ for (i = 0; i < ARRAY_SIZE(reserved_field_names); i++)
+ if (strcmp(reserved_field_names[i], name) == 0)
+ return 1;
+ for (i = 0; i < narg; i++)
+ if (strcmp(args[i].name, name) == 0)
+ return 1;
+ return 0;
+}
+
+void traceprobe_free_probe_arg(struct probe_arg *arg)
+{
+ if (CHECK_FETCH_FUNCS(deref, arg->fetch.fn))
+ free_deref_fetch_param(arg->fetch.data);
+ else if (CHECK_FETCH_FUNCS(symbol, arg->fetch.fn))
+ free_symbol_cache(arg->fetch.data);
+ kfree(arg->name);
+ kfree(arg->comm);
+}
+
+static int command_trace_probe(const char *buf,
+ int (*createfn)(int, char**))
+{
+ char **argv;
+ int argc = 0, ret = 0;
+
+ argv = argv_split(GFP_KERNEL, buf, &argc);
+ if (!argv)
+ return -ENOMEM;
+
+ if (argc)
+ ret = createfn(argc, argv);
+
+ argv_free(argv);
+ return ret;
+}
+
+#define WRITE_BUFSIZE 128
+
+ssize_t traceprobe_probes_write(struct file *file, const char __user *buffer,
+ size_t count, loff_t *ppos, int (*createfn)(int, char**))
+{
+ char *kbuf, *tmp;
+ int ret = 0;
+ size_t done = 0;
+ size_t size;
+
+ kbuf = kmalloc(WRITE_BUFSIZE, GFP_KERNEL);
+ if (!kbuf)
+ return -ENOMEM;
+
+ while (done < count) {
+ size = count - done;
+ if (size >= WRITE_BUFSIZE)
+ size = WRITE_BUFSIZE - 1;
+ if (copy_from_user(kbuf, buffer + done, size)) {
+ ret = -EFAULT;
+ goto out;
+ }
+ kbuf[size] = '\0';
+ tmp = strchr(kbuf, '\n');
+ if (tmp) {
+ *tmp = '\0';
+ size = tmp - kbuf + 1;
+ } else if (done + size < count) {
+ pr_warning("Line length is too long: "
+ "Should be less than %d.", WRITE_BUFSIZE);
+ ret = -EINVAL;
+ goto out;
+ }
+ done += size;
+ /* Remove comments */
+ tmp = strchr(kbuf, '#');
+ if (tmp)
+ *tmp = '\0';
+
+ ret = command_trace_probe(kbuf, createfn);
+ if (ret)
+ goto out;
+ }
+ ret = done;
+out:
+ kfree(kbuf);
+ return ret;
+}
+
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
new file mode 100644
index 0000000..74311ea
--- /dev/null
+++ b/kernel/trace/trace_probe.h
@@ -0,0 +1,155 @@
+/*
+ * Common header file for probe-based Dynamic events.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Copyright (C) IBM Corporation, 2010
+ * Author: Srikar Dronamraju
+ *
+ * Derived from kernel/trace/trace_kprobe.c written by
+ * Masami Hiramatsu <[email protected]>
+ */
+
+#include <linux/seq_file.h>
+#include <linux/slab.h>
+#include <linux/smp.h>
+#include <linux/debugfs.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/ctype.h>
+#include <linux/ptrace.h>
+#include <linux/perf_event.h>
+#include <linux/kprobes.h>
+#include <linux/stringify.h>
+#include <linux/limits.h>
+#include <linux/uaccess.h>
+#include <asm/bitsperlong.h>
+
+#include "trace.h"
+#include "trace_output.h"
+
+#define MAX_TRACE_ARGS 128
+#define MAX_ARGSTR_LEN 63
+#define MAX_EVENT_NAME_LEN 64
+#define MAX_STRING_SIZE PATH_MAX
+
+/* Reserved field names */
+#define FIELD_STRING_IP "__probe_ip"
+#define FIELD_STRING_RETIP "__probe_ret_ip"
+#define FIELD_STRING_FUNC "__probe_func"
+
+#undef DEFINE_FIELD
+#define DEFINE_FIELD(type, item, name, is_signed) \
+ do { \
+ ret = trace_define_field(event_call, #type, name, \
+ offsetof(typeof(field), item), \
+ sizeof(field.item), is_signed, \
+ FILTER_OTHER); \
+ if (ret) \
+ return ret; \
+ } while (0)
+
+
+/* Flags for trace_probe */
+#define TP_FLAG_TRACE 1
+#define TP_FLAG_PROFILE 2
+
+
+/* data_rloc: data relative location, compatible with u32 */
+#define make_data_rloc(len, roffs) \
+ (((u32)(len) << 16) | ((u32)(roffs) & 0xffff))
+#define get_rloc_len(dl) ((u32)(dl) >> 16)
+#define get_rloc_offs(dl) ((u32)(dl) & 0xffff)
+
+/*
+ * Convert data_rloc to data_loc:
+ * data_rloc stores the offset from data_rloc itself, but data_loc
+ * stores the offset from event entry.
+ */
+#define convert_rloc_to_loc(dl, offs) ((u32)(dl) + (offs))
+
+/* Data fetch function type */
+typedef void (*fetch_func_t)(struct pt_regs *, void *, void *);
+/* Printing function type */
+typedef int (*print_type_func_t)(struct trace_seq *, const char *, void *,
+ void *);
+
+/* Fetch types */
+enum {
+ FETCH_MTD_reg = 0,
+ FETCH_MTD_stack,
+ FETCH_MTD_retval,
+ FETCH_MTD_memory,
+ FETCH_MTD_symbol,
+ FETCH_MTD_deref,
+ FETCH_MTD_END,
+};
+
+/* Fetch type information table */
+struct fetch_type {
+ const char *name; /* Name of type */
+ size_t size; /* Byte size of type */
+ int is_signed; /* Signed flag */
+ print_type_func_t print; /* Print functions */
+ const char *fmt; /* Fromat string */
+ const char *fmttype; /* Name in format file */
+ /* Fetch functions */
+ fetch_func_t fetch[FETCH_MTD_END];
+};
+
+struct fetch_param {
+ fetch_func_t fn;
+ void *data;
+};
+
+struct probe_arg {
+ struct fetch_param fetch;
+ struct fetch_param fetch_size;
+ unsigned int offset; /* Offset from argument entry */
+ const char *name; /* Name of this argument */
+ const char *comm; /* Command of this argument */
+ const struct fetch_type *type; /* Type of this argument */
+};
+
+static inline __kprobes void call_fetch(struct fetch_param *fprm,
+ struct pt_regs *regs, void *dest)
+{
+ return fprm->fn(regs, fprm->data, dest);
+}
+
+/* Check the name is good for event/group */
+static inline int check_event_name(const char *name)
+{
+ if (!isalpha(*name) && *name != '_')
+ return 0;
+ while (*++name != '\0') {
+ if (!isalpha(*name) && !isdigit(*name) && *name != '_')
+ return 0;
+ }
+ return 1;
+}
+
+extern int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
+ struct probe_arg *parg, bool is_return);
+
+extern int traceprobe_conflict_field_name(const char *name,
+ struct probe_arg *args, int narg);
+
+extern void traceprobe_free_probe_arg(struct probe_arg *arg);
+
+extern int traceprobe_split_symbol_offset(char *symbol, unsigned long *offset);
+
+extern ssize_t traceprobe_probes_write(struct file *file,
+ const char __user *buffer, size_t count, loff_t *ppos,
+ int (*createfn)(int, char**));
Provides slot allocation mechanism for execution out of line for use
with user space breakpointing.
Traditional method of replacing the original instructions on
breakpoint hit are racy when used on multithreaded applications.
Alternatives for the traditional method include:
- Emulating the breakpointed instruction.
- Execution out of line.
Emulating the instruction:
This approach would use a in-kernel instruction emulator to
emulate the breakpointed instruction. This approach could be looked in
at a later point of time.
Execution out of line:
In execution out of line strategy, a new vma is injected into
the target process, a copy of the instructions which are breakpointed
is stored in one of the slots. On breakpoint hit, the copy of the
instruction is single-stepped leaving the breakpoint instruction as
is. This method is architecture independent.
This method is useful while handling multithreaded processes.
This patch allocates one page per process for slots to be used to copy
the breakpointed instructions.
Current slot allocation mechanism:
1. Allocate one dedicated slot per user breakpoint. Each slot is big
enuf to accomodate the biggest instruction for that architecture. (16
bytes for x86).
2. We currently allocate only one page for slots. Hence the number of
slots is limited to active breakpoint hits on that process.
3. Bitmap to track used slots.
Signed-off-by: Jim Keniston <[email protected]>
Signed-off-by: Srikar Dronamraju <[email protected]>
---
Changelog from V5: Merged into uprobes.
Changelog form V3:
* Added a memory barrier after the slot gets initialized.
Changelog from V2: (addressing Oleg's comments)
* Removed code in !CONFIG_UPROBES_XOL
* Functions now pass pointer to uprobes_xol_area instead of pointer
to void.
include/linux/uprobes.h | 2
kernel/uprobes.c | 283 +++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 285 insertions(+), 0 deletions(-)
diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
index faacb2f..84a078c 100644
--- a/include/linux/uprobes.h
+++ b/include/linux/uprobes.h
@@ -37,6 +37,8 @@ struct user_bkpt_task_arch_info {};
struct user_bkpt_arch_info;
#endif
+#define UINSNS_PER_PAGE (PAGE_SIZE/UPROBES_XOL_SLOT_BYTES)
+#define MAX_UPROBES_XOL_SLOTS UINSNS_PER_PAGE
struct task_struct;
struct pt_regs;
diff --git a/kernel/uprobes.c b/kernel/uprobes.c
index 8a659c9..230adf3 100644
--- a/kernel/uprobes.c
+++ b/kernel/uprobes.c
@@ -30,6 +30,12 @@
#include <linux/uaccess.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/mman.h>
+#include <linux/file.h>
+#include <linux/pid.h>
+#include <linux/slab.h>
struct user_bkpt_arch_info *arch = &user_bkpt_arch_info;
@@ -458,6 +464,283 @@ static int bad_arch_param(const char *param_name, int value)
return -ENOSYS;
}
+/* Slot allocation for XOL */
+
+/*
+ * Every probepoint gets its own slot. Once it's assigned a slot, it
+ * keeps that slot until the probepoint goes away. Only definite number
+ * of slots are allocated.
+ */
+
+struct uprobes_xol_area {
+ spinlock_t lock; /* protects bitmap and slot (de)allocation*/
+ unsigned long *bitmap; /* 0 = free slot */
+
+ /*
+ * We keep the vma's vm_start rather than a pointer to the vma
+ * itself. The probed process or a naughty kernel module could make
+ * the vma go away, and we must handle that reasonably gracefully.
+ */
+ unsigned long vaddr; /* Page(s) of instruction slots */
+};
+
+static int xol_add_vma(struct uprobes_xol_area *area)
+{
+ struct vm_area_struct *vma;
+ struct mm_struct *mm;
+ struct file *file;
+ unsigned long addr;
+
+ mm = get_task_mm(current);
+ if (!mm)
+ return -ESRCH;
+
+ down_write(&mm->mmap_sem);
+ /*
+ * Find the end of the top mapping and skip a page.
+ * If there is no space for PAGE_SIZE above
+ * that, mmap will ignore our address hint.
+ *
+ * We allocate a "fake" unlinked shmem file because
+ * anonymous memory might not be granted execute
+ * permission when the selinux security hooks have
+ * their way.
+ */
+ vma = rb_entry(rb_last(&mm->mm_rb), struct vm_area_struct, vm_rb);
+ addr = vma->vm_end + PAGE_SIZE;
+ file = shmem_file_setup("uprobes/xol", PAGE_SIZE, VM_NORESERVE);
+ if (!file) {
+ printk(KERN_ERR "uprobes_xol failed to setup shmem_file "
+ "while allocating vma for pid/tgid %d/%d for "
+ "single-stepping out of line.\n",
+ current->pid, current->tgid);
+ goto fail;
+ }
+ addr = do_mmap_pgoff(file, addr, PAGE_SIZE, PROT_EXEC, MAP_PRIVATE, 0);
+ fput(file);
+
+ if (addr & ~PAGE_MASK) {
+ printk(KERN_ERR "uprobes_xol failed to allocate a vma for "
+ "pid/tgid %d/%d for single-stepping out of "
+ "line.\n", current->pid, current->tgid);
+ goto fail;
+ }
+ vma = find_vma(mm, addr);
+
+ /* Don't expand vma on mremap(). */
+ vma->vm_flags |= VM_DONTEXPAND | VM_DONTCOPY;
+ area->vaddr = vma->vm_start;
+ up_write(&mm->mmap_sem);
+ mmput(mm);
+ return 0;
+
+fail:
+ up_write(&mm->mmap_sem);
+ mmput(mm);
+ return -ENOMEM;
+}
+
+/*
+ * xol_alloc_area - Allocate process's uprobes_xol_area.
+ * This area will be used for storing instructions for execution out of
+ * line.
+ *
+ * Called with mm->uproc->mutex locked.
+ * Returns the allocated area or NULL.
+ */
+static struct uprobes_xol_area *xol_alloc_area(void)
+{
+ struct uprobes_xol_area *area = NULL;
+
+ area = kzalloc(sizeof(*area), GFP_USER);
+ if (unlikely(!area))
+ return NULL;
+
+ area->bitmap = kzalloc(BITS_TO_LONGS(UINSNS_PER_PAGE) * sizeof(long),
+ GFP_USER);
+
+ if (!area->bitmap)
+ goto fail;
+ if (xol_add_vma(area)) {
+ kfree(area->bitmap);
+ goto fail;
+ }
+ spin_lock_init(&area->lock);
+ return area;
+
+fail:
+ kfree(area);
+ return NULL;
+}
+
+/*
+ * xol_free_area - Free the area allocated for slots.
+ * @xol_area refers the unique per process uprobes_xol_area for
+ * this process.
+ *
+ */
+static void xol_free_area(struct uprobes_xol_area *xol_area)
+{
+ kfree(xol_area->bitmap);
+ kfree(xol_area);
+}
+
+/*
+ * Find a slot
+ * - searching in existing vmas for a free slot.
+ * - If no free slot in existing vmas, return 0;
+ *
+ * Called when holding xol_area->lock
+ */
+static unsigned long xol_take_insn_slot(struct uprobes_xol_area *area)
+{
+ unsigned long slot_addr;
+ int slot_nr;
+
+ slot_nr = find_first_zero_bit(area->bitmap, UINSNS_PER_PAGE);
+ if (slot_nr < UINSNS_PER_PAGE) {
+ set_bit(slot_nr, area->bitmap);
+ slot_addr = area->vaddr +
+ (slot_nr * UPROBES_XOL_SLOT_BYTES);
+ return slot_addr;
+ }
+
+ return 0;
+}
+
+/*
+ * xol_get_insn_slot - If user_bkpt was not allocated a slot, then
+ * allocate a slot. If uprobes_insert_bkpt is already called, (i.e
+ * user_bkpt.vaddr != 0) then copy the instruction into the slot.
+ * @user_bkpt: probepoint information
+ * @xol_area refers the unique per process uprobes_xol_area for
+ * this process.
+ *
+ * Called with mm->uproc->mutex locked.
+ * Returns the allocated slot address or 0.
+ */
+static unsigned long xol_get_insn_slot(struct user_bkpt *user_bkpt,
+ struct uprobes_xol_area *xol_area)
+{
+ unsigned long flags, xol_vaddr = 0;
+ int len;
+
+ if (unlikely(!xol_area))
+ return 0;
+
+ if (user_bkpt->xol_vaddr)
+ return user_bkpt->xol_vaddr;
+
+ spin_lock_irqsave(&xol_area->lock, flags);
+ xol_vaddr = xol_take_insn_slot(xol_area);
+ spin_unlock_irqrestore(&xol_area->lock, flags);
+
+ /*
+ * Initialize the slot if user_bkpt->vaddr points to valid
+ * instruction slot.
+ */
+ if (likely(xol_vaddr) && user_bkpt->vaddr) {
+ len = access_process_vm(current, xol_vaddr, user_bkpt->insn,
+ UPROBES_XOL_SLOT_BYTES, 1);
+ if (unlikely(len < UPROBES_XOL_SLOT_BYTES))
+ printk(KERN_ERR "Failed to copy instruction at %#lx "
+ "len = %d\n", user_bkpt->vaddr, len);
+ }
+
+ /*
+ * Update user_bkpt->xol_vaddr after giving a chance for the slot to
+ * be initialized.
+ */
+ mb();
+ user_bkpt->xol_vaddr = xol_vaddr;
+ return user_bkpt->xol_vaddr;
+}
+
+/*
+ * xol_free_insn_slot - If slot was earlier allocated by
+ * @xol_get_insn_slot(), make the slot available for
+ * subsequent requests.
+ * @slot_addr: slot address as returned by
+ * @xol_get_insn_area().
+ * @xol_area refers the unique per process uprobes_xol_area for
+ * this process.
+ */
+static void xol_free_insn_slot(unsigned long slot_addr,
+ struct uprobes_xol_area *xol_area)
+{
+ unsigned long vma_end;
+ int found = 0;
+
+ if (unlikely(!slot_addr || IS_ERR_VALUE(slot_addr)))
+ return;
+
+ if (unlikely(!xol_area))
+ return;
+
+ vma_end = xol_area->vaddr + PAGE_SIZE;
+ if (xol_area->vaddr <= slot_addr && slot_addr < vma_end) {
+ int slot_nr;
+ unsigned long offset = slot_addr - xol_area->vaddr;
+ unsigned long flags;
+
+ BUG_ON(offset % UPROBES_XOL_SLOT_BYTES);
+
+ slot_nr = offset / UPROBES_XOL_SLOT_BYTES;
+ BUG_ON(slot_nr >= UINSNS_PER_PAGE);
+
+ spin_lock_irqsave(&xol_area->lock, flags);
+ clear_bit(slot_nr, xol_area->bitmap);
+ spin_unlock_irqrestore(&xol_area->lock, flags);
+ found = 1;
+ }
+
+ if (!found)
+ printk(KERN_ERR "%s: no XOL vma for slot address %#lx\n",
+ __func__, slot_addr);
+}
+
+/*
+ * xol_validate_vaddr - Verify if the specified address is in an
+ * executable vma, but not in an XOL vma.
+ * - Return 0 if the specified virtual address is in an
+ * executable vma, but not in an XOL vma.
+ * - Return 1 if the specified virtual address is in an
+ * XOL vma.
+ * - Return -EINTR otherwise.(i.e non executable vma, or
+ * not a valid address
+ * @pid: the probed process
+ * @vaddr: virtual address of the instruction to be validated.
+ * @xol_area refers the unique per process uprobes_xol_area for
+ * this process.
+ */
+static int xol_validate_vaddr(struct pid *pid, unsigned long vaddr,
+ struct uprobes_xol_area *xol_area)
+{
+ struct task_struct *tsk;
+ unsigned long vma_end;
+ int result;
+
+ if (unlikely(!xol_area))
+ return 0;
+
+ tsk = get_pid_task(pid, PIDTYPE_PID);
+ if (unlikely(!tsk))
+ return -EINVAL;
+
+ result = validate_address(tsk, vaddr);
+ if (result != 0)
+ goto validate_end;
+
+ vma_end = xol_area->vaddr + PAGE_SIZE;
+ if (xol_area->vaddr <= vaddr && vaddr < vma_end)
+ result = 1;
+
+validate_end:
+ put_task_struct(tsk);
+ return result;
+}
+/* end of slot allocation for XOL */
+
static int __init init_uprobes(void)
{
int result = 0;
Implements trace_event support for uprobes. In its
current form it can be used to put probes at a specified text address
in a process and dump the required registers when the code flow reaches
the probed address.
TODO: Documentation/trace/uprobetrace.txt
Signed-off-by: Srikar Dronamraju <[email protected]>
---
Changelog from v5: Addressed comments from Masami Hiramatsu and Steven
Rostedt. Some changes because of changes in common probe events.
Changelog from v4: (Merged to 2.6.35-rc3-tip)
Changelog from v2/v3: (Addressing comments from Steven Rostedt
and Frederic Weisbecker)
* removed pit field from uprobe_trace_entry.
* share common parts with kprobe trace events.
* use trace_create_file instead of debugfs_create_file.
The following example shows how to dump the instruction pointer and %ax a
register at the probed text address.
Start a process to trace. Get the address to trace.
[Here pid is asssumed as 6016]
[Address to trace is 0x0000000000446420]
[Registers to be dumped are %ip and %ax]
# cd /sys/kernel/debug/tracing/
# echo 'p 6016:0x0000000000446420 %ip %ax' > uprobe_events
# cat uprobe_events
p:uprobes/p_6016_0x0000000000446420 6016:0x0000000000446420 %ip=%ip %ax=%ax
# cat events/uprobes/p_6016_0x0000000000446420/enable
0
[enable the event]
# echo 1 > events/uprobes/p_6016_0x0000000000446420/enable
# cat events/uprobes/p_6016_0x0000000000446420/enable
1
# #### do some activity on the program so that it hits the breakpoint
# cat uprobe_profile
6016 p_6016_0x0000000000446420 234
# tracer: nop
#
# TASK-PID CPU# TIMESTAMP FUNCTION
# | | | | |
zsh-6016 [004] 227931.093579: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79
zsh-6016 [005] 227931.097541: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79
zsh-6016 [000] 227931.124909: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79
zsh-6016 [001] 227933.128565: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79
zsh-6016 [004] 227933.132756: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79
zsh-6016 [000] 227933.158802: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79
zsh-6016 [001] 227935.161602: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79
zsh-6016 [004] 227935.165229: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79
arch/Kconfig | 11 -
kernel/trace/Kconfig | 16 +
kernel/trace/Makefile | 1
kernel/trace/trace.h | 5
kernel/trace/trace_kprobe.c | 4
kernel/trace/trace_probe.c | 14 +
kernel/trace/trace_probe.h | 4
kernel/trace/trace_uprobe.c | 739 +++++++++++++++++++++++++++++++++++++++++++
8 files changed, 777 insertions(+), 17 deletions(-)
create mode 100644 kernel/trace/trace_uprobe.c
diff --git a/arch/Kconfig b/arch/Kconfig
index c8c8e3f..af167f8 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -48,16 +48,7 @@ config OPTPROBES
select KALLSYMS_ALL
config UPROBES
- bool "User-space probes (EXPERIMENTAL)"
- default n
- depends on ARCH_SUPPORTS_UPROBES
- depends on MMU
- help
- Uprobes enables kernel subsystems to establish probepoints
- in user applications and execute handler functions when
- the probepoints are hit. For more information, refer to
- Documentation/uprobes.txt.
- If in doubt, say "N".
+ def_bool n
config HAVE_EFFICIENT_UNALIGNED_ACCESS
bool
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index d709697..55ba474 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -366,6 +366,22 @@ config KPROBE_EVENT
This option is also required by perf-probe subcommand of perf tools.
If you want to use perf tools, this option is strongly recommended.
+config UPROBE_EVENT
+ bool "Enable uprobes-based dynamic events"
+ depends on ARCH_SUPPORTS_UPROBES
+ depends on MMU
+ select UPROBES
+ select PROBE_EVENTS
+ select TRACING
+ default n
+ help
+ This allows the user to add tracing events on top of userspace dynamic
+ events (similar to tracepoints) on the fly via the traceevents interface.
+ Those events can be inserted wherever uprobes can probe, and record
+ various registers.
+ This option is required if you plan to use perf-probe subcommand of perf
+ tools on user space applications.
+
config PROBE_EVENTS
def_bool n
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index 95d2043..67a12e3 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -57,5 +57,6 @@ ifeq ($(CONFIG_TRACING),y)
obj-$(CONFIG_KGDB_KDB) += trace_kdb.o
endif
obj-$(CONFIG_PROBE_EVENTS) +=trace_probe.o
+obj-$(CONFIG_UPROBE_EVENT) += trace_uprobe.o
libftrace-y := ftrace.o
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index d39b3c5..c5be8cb 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -97,6 +97,11 @@ struct kretprobe_trace_entry_head {
unsigned long ret_ip;
};
+struct uprobe_trace_entry_head {
+ struct trace_entry ent;
+ unsigned long ip;
+};
+
/*
* trace_flag_type is an enumeration that holds different
* states when a trace occurs. These are:
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index e66450d..8b1e55e 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -363,8 +363,8 @@ static int create_trace_probe(int argc, char **argv)
}
/* Parse fetch argument */
- ret = traceprobe_parse_probe_arg(arg, &tp->size, &tp->args[i],
- is_return);
+ ret = traceprobe_parse_probe_arg(arg, &tp->size,
+ &tp->args[i], is_return, true);
if (ret) {
pr_info("Parse error at argument%d. (%d)\n", i, ret);
kfree(tp->args[i].name);
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 4ca48c6..5123d1c 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -443,13 +443,17 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t,
/* Recursive argument parser */
static int parse_probe_arg(char *arg, const struct fetch_type *t,
- struct fetch_param *f, bool is_return)
+ struct fetch_param *f, bool is_return, bool is_kprobe)
{
int ret = 0;
unsigned long param;
long offset;
char *tmp;
+ /* Until uprobe_events supports only reg arguments */
+ if (!is_kprobe && arg[0] != '%')
+ return -EINVAL;
+
switch (arg[0]) {
case '$':
ret = parse_probe_vars(arg + 1, t, f, is_return);
@@ -500,7 +504,8 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
if (!dprm)
return -ENOMEM;
dprm->offset = offset;
- ret = parse_probe_arg(arg, t2, &dprm->orig, is_return);
+ ret = parse_probe_arg(arg, t2, &dprm->orig, is_return,
+ is_kprobe);
if (ret)
kfree(dprm);
else {
@@ -520,7 +525,7 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
/* String length checking wrapper */
int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
- struct probe_arg *parg, bool is_return)
+ struct probe_arg *parg, bool is_return, bool is_kprobe)
{
const char *t;
int ret;
@@ -546,7 +551,8 @@ int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
}
parg->offset = *size;
*size += parg->type->size;
- ret = parse_probe_arg(arg, parg->type, &parg->fetch, is_return);
+ ret = parse_probe_arg(arg, parg->type, &parg->fetch, is_return,
+ is_kprobe);
if (ret >= 0) {
parg->fetch_size.fn = get_fetch_size_function(parg->type,
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index 74311ea..d905386 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -48,6 +48,7 @@
#define FIELD_STRING_IP "__probe_ip"
#define FIELD_STRING_RETIP "__probe_ret_ip"
#define FIELD_STRING_FUNC "__probe_func"
+#define FIELD_STRING_PID "__probe_pid"
#undef DEFINE_FIELD
#define DEFINE_FIELD(type, item, name, is_signed) \
@@ -64,6 +65,7 @@
/* Flags for trace_probe */
#define TP_FLAG_TRACE 1
#define TP_FLAG_PROFILE 2
+#define TP_FLAG_UPROBE 4
/* data_rloc: data relative location, compatible with u32 */
@@ -141,7 +143,7 @@ static inline int check_event_name(const char *name)
}
extern int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
- struct probe_arg *parg, bool is_return);
+ struct probe_arg *parg, bool is_return, bool is_kprobe);
extern int traceprobe_conflict_field_name(const char *name,
struct probe_arg *args, int narg);
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
new file mode 100644
index 0000000..3aadac7
--- /dev/null
+++ b/kernel/trace/trace_uprobe.c
@@ -0,0 +1,739 @@
+/*
+ * uprobes-based tracing events
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Copyright (C) IBM Corporation, 2010
+ * Author: Srikar Dronamraju
+ */
+
+#include <linux/module.h>
+#include <linux/uaccess.h>
+#include <linux/uprobes.h>
+
+#include "trace_probe.h"
+
+#define UPROBE_EVENT_SYSTEM "uprobes"
+
+/**
+ * uprobe event core functions
+ */
+
+struct trace_uprobe {
+ struct list_head list;
+ struct uprobe up;
+ unsigned long nhit;
+ unsigned int flags; /* For TP_FLAG_* */
+ struct ftrace_event_class class;
+ struct ftrace_event_call call;
+ ssize_t size; /* trace entry size */
+ unsigned int nr_args;
+ struct probe_arg args[];
+};
+
+#define SIZEOF_TRACE_UPROBE(n) \
+ (offsetof(struct trace_uprobe, args) + \
+ (sizeof(struct probe_arg) * (n)))
+
+static int register_uprobe_event(struct trace_uprobe *tp);
+static void unregister_uprobe_event(struct trace_uprobe *tp);
+
+static DEFINE_MUTEX(uprobe_lock);
+static LIST_HEAD(uprobe_list);
+
+static void uprobe_dispatcher(struct uprobe *up, struct pt_regs *regs);
+
+/*
+ * Allocate new trace_uprobe and initialize it (including uprobes).
+ */
+static struct trace_uprobe *alloc_trace_uprobe(const char *group,
+ const char *event,
+ void *addr,
+ pid_t pid, int nargs)
+{
+ struct trace_uprobe *tp;
+
+ if (!event || !check_event_name(event))
+ return ERR_PTR(-EINVAL);
+
+ if (!group || !check_event_name(group))
+ return ERR_PTR(-EINVAL);
+
+ tp = kzalloc(SIZEOF_TRACE_UPROBE(nargs), GFP_KERNEL);
+ if (!tp)
+ return ERR_PTR(-ENOMEM);
+
+ tp->up.vaddr = (unsigned long)addr;
+ tp->up.pid = pid;
+ tp->up.handler = uprobe_dispatcher;
+
+ tp->call.class = &tp->class;
+ tp->call.name = kstrdup(event, GFP_KERNEL);
+ if (!tp->call.name)
+ goto error;
+
+ tp->class.system = kstrdup(group, GFP_KERNEL);
+ if (!tp->class.system)
+ goto error;
+
+ INIT_LIST_HEAD(&tp->list);
+ return tp;
+error:
+ kfree(tp->call.name);
+ kfree(tp);
+ return ERR_PTR(-ENOMEM);
+}
+
+static void free_trace_uprobe(struct trace_uprobe *tp)
+{
+ int i;
+
+ for (i = 0; i < tp->nr_args; i++)
+ traceprobe_free_probe_arg(&tp->args[i]);
+
+ kfree(tp->call.class->system);
+ kfree(tp->call.name);
+ kfree(tp);
+}
+
+static struct trace_uprobe *find_probe_event(const char *event,
+ const char *group)
+{
+ struct trace_uprobe *tp;
+
+ list_for_each_entry(tp, &uprobe_list, list)
+ if (strcmp(tp->call.name, event) == 0 &&
+ strcmp(tp->call.class->system, group) == 0)
+ return tp;
+ return NULL;
+}
+
+/* Unregister a trace_uprobe and probe_event: call with locking uprobe_lock */
+static void unregister_trace_uprobe(struct trace_uprobe *tp)
+{
+ if (tp->flags & TP_FLAG_UPROBE)
+ unregister_uprobe(&tp->up);
+ list_del(&tp->list);
+ unregister_uprobe_event(tp);
+}
+
+/* Register a trace_uprobe and probe_event */
+static int register_trace_uprobe(struct trace_uprobe *tp)
+{
+ struct trace_uprobe *old_tp;
+ int ret;
+
+ mutex_lock(&uprobe_lock);
+
+ /* register as an event */
+ old_tp = find_probe_event(tp->call.name, tp->call.class->system);
+ if (old_tp) {
+ /* delete old event */
+ unregister_trace_uprobe(old_tp);
+ free_trace_uprobe(old_tp);
+ }
+ ret = register_uprobe_event(tp);
+ if (ret) {
+ pr_warning("Failed to register probe event(%d)\n", ret);
+ goto end;
+ }
+
+ list_add_tail(&tp->list, &uprobe_list);
+end:
+ mutex_unlock(&uprobe_lock);
+ return ret;
+}
+
+static int create_trace_uprobe(int argc, char **argv)
+{
+ /*
+ * Argument syntax:
+ * - Add uprobe: p[:[GRP/]EVENT] VADDR@PID [%REG]
+ *
+ * - Remove uprobe: -:[GRP/]EVENT
+ */
+ struct trace_uprobe *tp;
+ int i, ret = 0;
+ int is_delete = 0;
+ char *arg = NULL, *event = NULL, *group = NULL;
+ void *addr = NULL;
+ pid_t pid = 0;
+ char buf[MAX_EVENT_NAME_LEN];
+ char *tmp;
+
+ /* argc must be >= 1 */
+ if (argv[0][0] == '-')
+ is_delete = 1;
+ else if (argv[0][0] != 'p') {
+ pr_info("Probe definition must be started with 'p', 'r' or"
+ " '-'.\n");
+ return -EINVAL;
+ }
+
+ if (argv[0][1] == ':') {
+ event = &argv[0][2];
+ if (strchr(event, '/')) {
+ group = event;
+ event = strchr(group, '/') + 1;
+ event[-1] = '\0';
+ if (strlen(group) == 0) {
+ pr_info("Group name is not specified\n");
+ return -EINVAL;
+ }
+ }
+ if (strlen(event) == 0) {
+ pr_info("Event name is not specified\n");
+ return -EINVAL;
+ }
+ }
+ if (!group)
+ group = UPROBE_EVENT_SYSTEM;
+
+ if (is_delete) {
+ if (!event) {
+ pr_info("Delete command needs an event name.\n");
+ return -EINVAL;
+ }
+ mutex_lock(&uprobe_lock);
+ tp = find_probe_event(event, group);
+ if (!tp) {
+ mutex_unlock(&uprobe_lock);
+ pr_info("Event %s/%s doesn't exist.\n", group, event);
+ return -ENOENT;
+ }
+ /* delete an event */
+ unregister_trace_uprobe(tp);
+ free_trace_uprobe(tp);
+ mutex_unlock(&uprobe_lock);
+ return 0;
+ }
+
+ if (argc < 2) {
+ pr_info("Probe point is not specified.\n");
+ return -EINVAL;
+ }
+ if (isdigit(argv[1][0])) {
+ /* an address specified */
+ arg = strchr(argv[1], ':');
+ if (!arg)
+ goto fail_address_parse;
+
+ *arg++ = '\0';
+ ret = strict_strtoul(&argv[1][0], 0, (unsigned long *)&pid);
+ if (ret)
+ goto fail_address_parse;
+
+ ret = strict_strtoul(arg, 0, (unsigned long *)&addr);
+ if (ret)
+ goto fail_address_parse;
+ }
+ argc -= 2; argv += 2;
+
+ /* setup a probe */
+ if (!event) {
+ snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%d_0x%p", 'p',
+ pid, addr);
+ event = buf;
+ }
+ tp = alloc_trace_uprobe(group, event, addr, pid, argc);
+ if (IS_ERR(tp)) {
+ pr_info("Failed to allocate trace_uprobe.(%d)\n",
+ (int)PTR_ERR(tp));
+ return PTR_ERR(tp);
+ }
+
+ /* parse arguments */
+ ret = 0;
+ for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
+ /* Parse argument name */
+ arg = strchr(argv[i], '=');
+ if (arg)
+ *arg++ = '\0';
+ else
+ arg = argv[i];
+
+ tp->args[i].name = kstrdup(argv[i], GFP_KERNEL);
+ if (!tp->args[i].name) {
+ pr_info("Failed to allocate argument%d name '%s'.\n",
+ i, argv[i]);
+ ret = -ENOMEM;
+ goto error;
+ }
+ tmp = strchr(tp->args[i].name, ':');
+ if (tmp)
+ *tmp = '_'; /* convert : to _ */
+
+ if (traceprobe_conflict_field_name(tp->args[i].name,
+ tp->args, i)) {
+ pr_info("Argument%d name '%s' conflicts with "
+ "another field.\n", i, argv[i]);
+ ret = -EINVAL;
+ goto error;
+ }
+
+ /* Parse fetch argument */
+ ret = traceprobe_parse_probe_arg(arg, &tp->size, &tp->args[i],
+ false, false);
+ if (ret) {
+ pr_info("Parse error at argument%d. (%d)\n", i, ret);
+ kfree(tp->args[i].name);
+ goto error;
+ }
+
+ tp->nr_args++;
+ }
+
+ ret = register_trace_uprobe(tp);
+ if (ret)
+ goto error;
+ return 0;
+
+error:
+ free_trace_uprobe(tp);
+ return ret;
+
+fail_address_parse:
+ pr_info("Failed to parse address.\n");
+ return ret;
+}
+
+static void cleanup_all_probes(void)
+{
+ struct trace_uprobe *tp;
+
+ mutex_lock(&uprobe_lock);
+ /* TODO: Use batch unregistration */
+ while (!list_empty(&uprobe_list)) {
+ tp = list_entry(uprobe_list.next, struct trace_uprobe, list);
+ unregister_trace_uprobe(tp);
+ free_trace_uprobe(tp);
+ }
+ mutex_unlock(&uprobe_lock);
+}
+
+
+/* Probes listing interfaces */
+static void *probes_seq_start(struct seq_file *m, loff_t *pos)
+{
+ mutex_lock(&uprobe_lock);
+ return seq_list_start(&uprobe_list, *pos);
+}
+
+static void *probes_seq_next(struct seq_file *m, void *v, loff_t *pos)
+{
+ return seq_list_next(v, &uprobe_list, pos);
+}
+
+static void probes_seq_stop(struct seq_file *m, void *v)
+{
+ mutex_unlock(&uprobe_lock);
+}
+
+static int probes_seq_show(struct seq_file *m, void *v)
+{
+ struct trace_uprobe *tp = v;
+ int i;
+
+ seq_printf(m, "%c", 'p');
+ seq_printf(m, ":%s/%s", tp->call.class->system, tp->call.name);
+
+ seq_printf(m, " %d:0x%p", tp->up.pid, (void *)tp->up.vaddr);
+
+ for (i = 0; i < tp->nr_args; i++)
+ seq_printf(m, " %s=%s", tp->args[i].name, tp->args[i].comm);
+ seq_printf(m, "\n");
+
+ return 0;
+}
+
+static const struct seq_operations probes_seq_op = {
+ .start = probes_seq_start,
+ .next = probes_seq_next,
+ .stop = probes_seq_stop,
+ .show = probes_seq_show
+};
+
+static int probes_open(struct inode *inode, struct file *file)
+{
+ if ((file->f_mode & FMODE_WRITE) &&
+ (file->f_flags & O_TRUNC))
+ cleanup_all_probes();
+
+ return seq_open(file, &probes_seq_op);
+}
+
+static ssize_t probes_write(struct file *file, const char __user *buffer,
+ size_t count, loff_t *ppos)
+{
+ return traceprobe_probes_write(file, buffer, count, ppos,
+ create_trace_uprobe);
+}
+
+static const struct file_operations uprobe_events_ops = {
+ .owner = THIS_MODULE,
+ .open = probes_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = seq_release,
+ .write = probes_write,
+};
+
+/* Probes profiling interfaces */
+static int probes_profile_seq_show(struct seq_file *m, void *v)
+{
+ struct trace_uprobe *tp = v;
+
+ seq_printf(m, " %d %-44s %15lu\n", tp->up.pid, tp->call.name,
+ tp->nhit);
+ return 0;
+}
+
+static const struct seq_operations profile_seq_op = {
+ .start = probes_seq_start,
+ .next = probes_seq_next,
+ .stop = probes_seq_stop,
+ .show = probes_profile_seq_show
+};
+
+static int profile_open(struct inode *inode, struct file *file)
+{
+ return seq_open(file, &profile_seq_op);
+}
+
+static const struct file_operations uprobe_profile_ops = {
+ .owner = THIS_MODULE,
+ .open = profile_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = seq_release,
+};
+
+/* uprobe handler */
+static void uprobe_trace_func(struct uprobe *up, struct pt_regs *regs)
+{
+ struct trace_uprobe *tp = container_of(up, struct trace_uprobe, up);
+ struct uprobe_trace_entry_head *entry;
+ struct ring_buffer_event *event;
+ struct ring_buffer *buffer;
+ u8 *data;
+ int size, i, pc;
+ unsigned long irq_flags;
+ struct ftrace_event_call *call = &tp->call;
+
+ tp->nhit++;
+
+ local_save_flags(irq_flags);
+ pc = preempt_count();
+
+ size = sizeof(*entry) + tp->size;
+
+ event = trace_current_buffer_lock_reserve(&buffer, call->event.type,
+ size, irq_flags, pc);
+ if (!event)
+ return;
+
+ entry = ring_buffer_event_data(event);
+ entry->ip = (unsigned long)up->vaddr;
+ data = (u8 *)&entry[1];
+ for (i = 0; i < tp->nr_args; i++)
+ call_fetch(&tp->args[i].fetch, regs,
+ data + tp->args[i].offset);
+
+ if (!filter_current_check_discard(buffer, call, entry, event))
+ trace_buffer_unlock_commit(buffer, event, irq_flags, pc);
+}
+
+/* Event entry printers */
+enum print_line_t
+print_uprobe_event(struct trace_iterator *iter, int flags,
+ struct trace_event *event)
+{
+ struct uprobe_trace_entry_head *field;
+ struct trace_seq *s = &iter->seq;
+ struct trace_uprobe *tp;
+ u8 *data;
+ int i;
+
+ field = (struct uprobe_trace_entry_head *)iter->ent;
+ tp = container_of(event, struct trace_uprobe, call.event);
+
+ if (!trace_seq_printf(s, "%s: (", tp->call.name))
+ goto partial;
+
+ if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
+ goto partial;
+
+ if (!trace_seq_puts(s, ")"))
+ goto partial;
+
+ data = (u8 *)&field[1];
+ for (i = 0; i < tp->nr_args; i++)
+ if (!tp->args[i].type->print(s, tp->args[i].name,
+ data + tp->args[i].offset, field))
+ goto partial;
+
+ if (!trace_seq_puts(s, "\n"))
+ goto partial;
+
+ return TRACE_TYPE_HANDLED;
+partial:
+ return TRACE_TYPE_PARTIAL_LINE;
+}
+
+
+static int probe_event_enable(struct ftrace_event_call *call)
+{
+ int ret = 0;
+ struct trace_uprobe *tp = (struct trace_uprobe *)call->data;
+
+ if (!(tp->flags & TP_FLAG_UPROBE)) {
+ ret = register_uprobe(&tp->up);
+ if (!ret)
+ tp->flags |= (TP_FLAG_UPROBE | TP_FLAG_TRACE);
+ }
+ return ret;
+}
+
+static void probe_event_disable(struct ftrace_event_call *call)
+{
+ struct trace_uprobe *tp = (struct trace_uprobe *)call->data;
+
+ if (tp->flags & TP_FLAG_UPROBE) {
+ unregister_uprobe(&tp->up);
+ tp->flags &= ~(TP_FLAG_UPROBE | TP_FLAG_TRACE);
+ }
+}
+
+static int uprobe_event_define_fields(struct ftrace_event_call *event_call)
+{
+ int ret, i;
+ struct uprobe_trace_entry_head field;
+ struct trace_uprobe *tp = (struct trace_uprobe *)event_call->data;
+
+ DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
+ /* Set argument names as fields */
+ for (i = 0; i < tp->nr_args; i++) {
+ ret = trace_define_field(event_call, tp->args[i].type->fmttype,
+ tp->args[i].name,
+ sizeof(field) + tp->args[i].offset,
+ tp->args[i].type->size,
+ tp->args[i].type->is_signed,
+ FILTER_OTHER);
+ if (ret)
+ return ret;
+ }
+ return 0;
+}
+
+static int __set_print_fmt(struct trace_uprobe *tp, char *buf, int len)
+{
+ int i;
+ int pos = 0;
+
+ const char *fmt, *arg;
+
+ fmt = "(%lx)";
+ arg = "REC->" FIELD_STRING_IP;
+
+ /* When len=0, we just calculate the needed length */
+#define LEN_OR_ZERO (len ? len - pos : 0)
+
+ pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", fmt);
+
+ for (i = 0; i < tp->nr_args; i++) {
+ pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=%s",
+ tp->args[i].name, tp->args[i].type->fmt);
+ }
+
+ pos += snprintf(buf + pos, LEN_OR_ZERO, "\", %s", arg);
+
+ for (i = 0; i < tp->nr_args; i++) {
+ pos += snprintf(buf + pos, LEN_OR_ZERO, ", REC->%s",
+ tp->args[i].name);
+ }
+
+#undef LEN_OR_ZERO
+
+ /* return the length of print_fmt */
+ return pos;
+}
+
+static int set_print_fmt(struct trace_uprobe *tp)
+{
+ int len;
+ char *print_fmt;
+
+ /* First: called with 0 length to calculate the needed length */
+ len = __set_print_fmt(tp, NULL, 0);
+ print_fmt = kmalloc(len + 1, GFP_KERNEL);
+ if (!print_fmt)
+ return -ENOMEM;
+
+ /* Second: actually write the @print_fmt */
+ __set_print_fmt(tp, print_fmt, len + 1);
+ tp->call.print_fmt = print_fmt;
+
+ return 0;
+}
+
+#ifdef CONFIG_PERF_EVENTS
+
+/* uprobe profile handler */
+static void uprobe_perf_func(struct uprobe *up,
+ struct pt_regs *regs)
+{
+ struct trace_uprobe *tp = container_of(up, struct trace_uprobe, up);
+ struct ftrace_event_call *call = &tp->call;
+ struct uprobe_trace_entry_head *entry;
+ struct hlist_head *head;
+ u8 *data;
+ int size, __size, i;
+ int rctx;
+
+ __size = sizeof(*entry) + tp->size;
+ size = ALIGN(__size + sizeof(u32), sizeof(u64));
+ size -= sizeof(u32);
+ if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
+ "profile buffer not large enough"))
+ return;
+
+ entry = perf_trace_buf_prepare(size, call->event.type, regs, &rctx);
+ if (!entry)
+ return;
+
+ entry->ip = (unsigned long)up->vaddr;
+ data = (u8 *)&entry[1];
+ for (i = 0; i < tp->nr_args; i++)
+ call_fetch(&tp->args[i].fetch, regs,
+ data + tp->args[i].offset);
+
+ head = this_cpu_ptr(call->perf_events);
+ perf_trace_buf_submit(entry, size, rctx, entry->ip, 1, regs, head);
+}
+
+static int probe_perf_enable(struct ftrace_event_call *call)
+{
+ int ret = 0;
+ struct trace_uprobe *tp = (struct trace_uprobe *)call->data;
+
+ if (!(tp->flags & TP_FLAG_UPROBE)) {
+ ret = register_uprobe(&tp->up);
+ if (!ret)
+ tp->flags |= (TP_FLAG_UPROBE | TP_FLAG_PROFILE);
+ }
+ return ret;
+}
+
+static void probe_perf_disable(struct ftrace_event_call *call)
+{
+ struct trace_uprobe *tp = (struct trace_uprobe *)call->data;
+
+ if (tp->flags & TP_FLAG_UPROBE) {
+ unregister_uprobe(&tp->up);
+ tp->flags &= ~(TP_FLAG_UPROBE | TP_FLAG_PROFILE);
+ }
+}
+#endif /* CONFIG_PERF_EVENTS */
+
+static
+int uprobe_register(struct ftrace_event_call *event, enum trace_reg type)
+{
+ switch (type) {
+ case TRACE_REG_REGISTER:
+ return probe_event_enable(event);
+ case TRACE_REG_UNREGISTER:
+ probe_event_disable(event);
+ return 0;
+
+#ifdef CONFIG_PERF_EVENTS
+ case TRACE_REG_PERF_REGISTER:
+ return probe_perf_enable(event);
+ case TRACE_REG_PERF_UNREGISTER:
+ probe_perf_disable(event);
+ return 0;
+#endif
+ }
+ return 0;
+}
+
+static void uprobe_dispatcher(struct uprobe *up, struct pt_regs *regs)
+{
+ struct trace_uprobe *tp = container_of(up, struct trace_uprobe, up);
+
+ if (tp->flags & TP_FLAG_TRACE)
+ uprobe_trace_func(up, regs);
+#ifdef CONFIG_PERF_EVENTS
+ if (tp->flags & TP_FLAG_PROFILE)
+ uprobe_perf_func(up, regs);
+#endif
+}
+
+
+static struct trace_event_functions uprobe_funcs = {
+ .trace = print_uprobe_event
+};
+
+static int register_uprobe_event(struct trace_uprobe *tp)
+{
+ struct ftrace_event_call *call = &tp->call;
+ int ret;
+
+ /* Initialize ftrace_event_call */
+ INIT_LIST_HEAD(&call->class->fields);
+ call->event.funcs = &uprobe_funcs;
+ call->class->define_fields = uprobe_event_define_fields;
+ if (set_print_fmt(tp) < 0)
+ return -ENOMEM;
+ ret = register_ftrace_event(&call->event);
+ if (!ret) {
+ kfree(call->print_fmt);
+ return -ENODEV;
+ }
+ call->flags = 0;
+ call->class->reg = uprobe_register;
+ call->data = tp;
+ ret = trace_add_event_call(call);
+ if (ret) {
+ pr_info("Failed to register uprobe event: %s\n", call->name);
+ kfree(call->print_fmt);
+ unregister_ftrace_event(&call->event);
+ }
+ return ret;
+}
+
+static void unregister_uprobe_event(struct trace_uprobe *tp)
+{
+ /* tp->event is unregistered in trace_remove_event_call() */
+ trace_remove_event_call(&tp->call);
+ kfree(tp->call.print_fmt);
+}
+
+/* Make a trace interface for controling probe points */
+static __init int init_uprobe_trace(void)
+{
+ struct dentry *d_tracer;
+ struct dentry *entry;
+
+ d_tracer = tracing_init_dentry();
+ if (!d_tracer)
+ return 0;
+
+ entry = trace_create_file("uprobe_events", 0644, d_tracer,
+ NULL, &uprobe_events_ops);
+ /* Profile interface */
+ entry = trace_create_file("uprobe_profile", 0444, d_tracer,
+ NULL, &uprobe_profile_ops);
+ return 0;
+}
+fs_initcall(init_uprobe_trace);
Given a dso, list the symbols in ascending order. Needed for listing
available symbols from perf-probe.
Signed-off-by: Srikar Dronamraju <[email protected]>
---
tools/perf/util/symbol.c | 14 ++++++++++++++
tools/perf/util/symbol.h | 1 +
2 files changed, 15 insertions(+), 0 deletions(-)
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 1a36773..ca22032 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -388,6 +388,20 @@ size_t dso__fprintf_buildid(struct dso *self, FILE *fp)
return fprintf(fp, "%s", sbuild_id);
}
+size_t dso__fprintf_symbols(struct dso *self, enum map_type type, FILE *fp)
+{
+ size_t ret = 0;
+ struct rb_node *nd;
+ struct symbol_name_rb_node *pos;
+
+ for (nd = rb_first(&self->symbol_names[type]); nd; nd = rb_next(nd)) {
+ pos = rb_entry(nd, struct symbol_name_rb_node, rb_node);
+ fprintf(fp, "%s\n", pos->sym.name);
+ }
+
+ return ret;
+}
+
size_t dso__fprintf(struct dso *self, enum map_type type, FILE *fp)
{
struct rb_node *nd;
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index b7a8da4..72ef973 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -181,6 +181,7 @@ size_t machines__fprintf_dsos(struct rb_root *self, FILE *fp);
size_t machines__fprintf_dsos_buildid(struct rb_root *self, FILE *fp, bool with_hits);
size_t dso__fprintf_buildid(struct dso *self, FILE *fp);
+size_t dso__fprintf_symbols(struct dso *self, enum map_type type, FILE *fp);
size_t dso__fprintf(struct dso *self, enum map_type type, FILE *fp);
enum dso_origin {
Introduces -S/--show_functions option for perf-probe.
This lists function names in a File. If no file is specified, then lists
functions in the current running kernel.
Signed-off-by: Srikar Dronamraju <[email protected]>
---
Changelog from V10: As suggested by Arnaldo, filtering is now
based on sym.binding.
Changelog from V9: Filter labels, weak, and local binding functions
from listing as suggested by Christoph Hellwig.
Show last 10 functions in /bin/zsh.
# perf probe -S -D /bin/zsh | tail
zstrtol
ztrcmp
ztrdup
ztrduppfx
ztrftime
ztrlen
ztrncpy
ztrsub
zwarn
zwarnnam
Show first 10 functions in /lib/libc.so.6
# perf probe -S -D /lib/libc.so.6 | head
_IO_adjust_column
_IO_adjust_wcolumn
_IO_default_doallocate
_IO_default_finish
_IO_default_pbackfail
_IO_default_uflow
_IO_default_xsgetn
_IO_default_xsputn
_IO_do_write@@GLIBC_2.2.5
_IO_doallocbuf
Show last 10 functions in kernel.
# perf probe -S | tail
zlib_inflateInit2
zlib_inflateReset
zlib_inflate_blob
zlib_inflate_table
zlib_inflate_workspacesize
zone_pcp_update
zone_reclaim
zone_reclaimable_pages
zone_statistics
zone_watermark_ok
tools/perf/builtin-probe.c | 43 ++++++++++++++++++++++++
tools/perf/util/probe-event.c | 72 +++++++++++++++++++++++++++++++++++++++++
tools/perf/util/probe-event.h | 1 +
tools/perf/util/symbol.c | 8 +++++
tools/perf/util/symbol.h | 1 +
5 files changed, 124 insertions(+), 1 deletions(-)
diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
index 199d5e1..fa63245 100644
--- a/tools/perf/builtin-probe.c
+++ b/tools/perf/builtin-probe.c
@@ -50,9 +50,11 @@ static struct {
bool list_events;
bool force_add;
bool show_lines;
+ bool list_functions;
int nevents;
struct perf_probe_event events[MAX_PROBES];
struct strlist *dellist;
+ struct strlist *limitlist;
struct line_range line_range;
int max_probe_points;
} params;
@@ -132,6 +134,19 @@ static int opt_show_lines(const struct option *opt __used,
}
#endif
+static int opt_limit_dsos(const struct option *opt __used,
+ const char *str, int unset __used)
+{
+ if (str) {
+ if (!params.limitlist)
+ params.limitlist = strlist__new(true, NULL);
+ if (!params.limitlist)
+ return -1;
+ strlist__add(params.limitlist, str);
+ }
+ return 0;
+}
+
static const char * const probe_usage[] = {
"perf probe [<options>] 'PROBEDEF' ['PROBEDEF' ...]",
"perf probe [<options>] --add 'PROBEDEF' [--add 'PROBEDEF' ...]",
@@ -188,6 +203,10 @@ static const struct option options[] = {
OPT__DRY_RUN(&probe_event_dry_run),
OPT_INTEGER('\0', "max-probes", ¶ms.max_probe_points,
"Set how many probe points can be found for a probe."),
+ OPT_BOOLEAN('S', "show_functions", ¶ms.list_functions,
+ "Show potential probes."),
+ OPT_CALLBACK('D', "limit_dsos", NULL, "DSO",
+ "Limit Dsos.", opt_limit_dsos),
OPT_END()
};
@@ -213,7 +232,7 @@ int cmd_probe(int argc, const char **argv, const char *prefix __used)
params.max_probe_points = MAX_PROBES;
if ((!params.nevents && !params.dellist && !params.list_events &&
- !params.show_lines))
+ !params.show_lines && !params.list_functions))
usage_with_options(probe_usage, options);
if (params.list_events) {
@@ -225,12 +244,34 @@ int cmd_probe(int argc, const char **argv, const char *prefix __used)
pr_err(" Error: Don't use --list with --line.\n");
usage_with_options(probe_usage, options);
}
+ if (params.list_functions) {
+ pr_warning(" Error: Don't use --list with"
+ " --show_functions.\n");
+ usage_with_options(probe_usage, options);
+ }
ret = show_perf_probe_events();
if (ret < 0)
pr_err(" Error: Failed to show event list. (%d)\n",
ret);
return ret;
}
+ if (params.list_functions) {
+ if (params.nevents != 0 || params.dellist) {
+ pr_err(" Error: Don't use --show_functions with"
+ " --add/--del.\n");
+ usage_with_options(probe_usage, options);
+ }
+ if (params.show_lines) {
+ pr_err(" Error: Don't use --show_functions with"
+ " --line.\n");
+ usage_with_options(probe_usage, options);
+ }
+ ret = show_possible_probes(params.limitlist);
+ if (ret < 0)
+ pr_err(" Error: Failed to show possible"
+ " probes (%d).\n", ret);
+ return ret;
+ }
#ifdef DWARF_SUPPORT
if (params.show_lines) {
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index e72f05c..2efbe4b 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -31,6 +31,7 @@
#include <string.h>
#include <stdarg.h>
#include <limits.h>
+#include <gelf.h>
#undef _GNU_SOURCE
#include "util.h"
@@ -46,6 +47,7 @@
#include "trace-event.h" /* For __unused */
#include "probe-event.h"
#include "probe-finder.h"
+#include "session.h"
#define MAX_CMDLEN 256
#define MAX_PROBE_ARGS 128
@@ -1752,3 +1754,73 @@ int del_perf_probe_events(struct strlist *dellist)
return ret;
}
+/*
+ * If a symbol corresponds to a function with global binding return 0.
+ * For all others return 1.
+ */
+static int filter_non_global_functions(struct map *map __unused,
+ struct symbol *sym)
+{
+ if (sym->binding != STB_GLOBAL)
+ return 1;
+
+ return 0;
+}
+
+static int print_list_available_symbols(struct map *map,
+ const char *name __unused)
+{
+ if (map__load(map, filter_non_global_functions) < 0)
+ return -EINVAL;
+ if (!dso__sorted_by_name(map->dso, map->type))
+ dso__sort_by_name(map->dso, map->type);
+
+ dso__fprintf_symbols(map->dso, map->type, stdout);
+ return 0;
+}
+
+int show_possible_probes(struct strlist *limitlist)
+{
+ struct str_node *ent;
+ struct map *map = NULL;
+ char *str;
+ int ret = -EINVAL;
+
+ if (!limitlist) { /* Show functions in kernel */
+ ret = init_vmlinux();
+ if (ret < 0)
+ return ret;
+ return print_list_available_symbols(
+ machine.vmlinux_maps[MAP__FUNCTION], NULL);
+ }
+
+ symbol_conf.try_vmlinux_path = false;
+ symbol_conf.sort_by_name = true;
+ ret = symbol__init();
+ if (ret < 0) {
+ pr_debug("Failed to init symbol map.\n");
+ return ret;
+ }
+
+ strlist__for_each(ent, limitlist) {
+ str = strdup(ent->s);
+ if (!str) {
+ ret = -ENOMEM;
+ goto out_delete;
+ }
+
+ map = dso__new_map(str);
+ ret = print_list_available_symbols(map, NULL);
+ if (ret)
+ pr_warning("No Symbols in dso %s.\n", str);
+
+ dso__delete(map->dso);
+ map__delete(map);
+ free(str);
+ }
+
+out_delete:
+ if (ret)
+ pr_warning("Failed to list available probes.\n");
+ return ret;
+}
diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
index 5af3924..fcd0f08 100644
--- a/tools/perf/util/probe-event.h
+++ b/tools/perf/util/probe-event.h
@@ -115,6 +115,7 @@ extern int add_perf_probe_events(struct perf_probe_event *pevs, int npevs,
extern int del_perf_probe_events(struct strlist *dellist);
extern int show_perf_probe_events(void);
extern int show_line_range(struct line_range *lr);
+extern int show_possible_probes(struct strlist *availlist);
/* Maximum index number of event-name postfix */
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index ca22032..385f0a4 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -2464,3 +2464,11 @@ int machine__load_vmlinux_path(struct machine *self, enum map_type type,
return ret;
}
+
+struct map *dso__new_map(char *name)
+{
+ struct dso *dso = dso__new(name);
+ struct map *map = map__new2(0, dso, MAP__FUNCTION);
+
+ return map;
+}
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index 72ef973..52a8126 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -202,6 +202,7 @@ char dso__symtab_origin(const struct dso *self);
void dso__set_long_name(struct dso *self, char *name);
void dso__set_build_id(struct dso *self, void *build_id);
void dso__read_running_kernel_build_id(struct dso *self, struct machine *machine);
+struct map *dso__new_map(char *name);
struct symbol *dso__find_symbol(struct dso *self, enum map_type type, u64 addr);
struct symbol *dso__find_symbol_by_name(struct dso *self, enum map_type type,
const char *name);
Selecting CONFIG_PROBE_EVENTS enables both kprobe-based and
uprobes-based dynamic events. However kprobe-tracer or uprobe-tracer
can still be individually selected or disabled.
Signed-off-by: Srikar Dronamraju <[email protected]>
Suggested-by: Frederic Weisbecker <[email protected]>
---
kernel/trace/Kconfig | 51 +++++++++++++++++++++++++++++---------------------
1 files changed, 30 insertions(+), 21 deletions(-)
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 55ba474..205c12b 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -76,7 +76,7 @@ config RING_BUFFER_ALLOW_SWAP
# All tracer options should select GENERIC_TRACER. For those options that are
# enabled by all tracers (context switch and event tracer) they select TRACING.
# This allows those options to appear when no other tracer is selected. But the
-# options do not appear when something else selects it. We need the two options
+# options do not appear when something else selects it. We need the two option
# GENERIC_TRACER and TRACING to avoid circular dependencies to accomplish the
# hiding of the automatic options.
@@ -162,7 +162,7 @@ config IRQSOFF_TRACER
This option measures the time spent in irqs-off critical
sections, with microsecond accuracy.
- The default measurement method is a maximum search, which is
+ The default measurement method is a maximum search, which i
disabled by default and can be runtime (re-)started
via:
@@ -184,7 +184,7 @@ config PREEMPT_TRACER
This option measures the time spent in preemption-off critical
sections, with microsecond accuracy.
- The default measurement method is a maximum search, which is
+ The default measurement method is a maximum search, which i
disabled by default and can be runtime (re-)started
via:
@@ -228,7 +228,7 @@ choice
prompt "Branch Profiling"
default BRANCH_PROFILE_NONE
help
- The branch profiling is a software profiler. It will add hooks
+ The branch profiling is a software profiler. It will add hook
into the C conditionals to test which path a branch takes.
The likely/unlikely profiler only looks at the conditions that
@@ -252,12 +252,12 @@ config PROFILE_ANNOTATED_BRANCHES
bool "Trace likely/unlikely profiler"
select TRACE_BRANCH_PROFILING
help
- This tracer profiles all the the likely and unlikely macros
+ This tracer profiles all the the likely and unlikely macro
in the kernel. It will display the results in:
/sys/kernel/debug/tracing/profile_annotated_branch
- Note: this will add a significant overhead; only turn this
+ Note: this will add a significant overhead; only turn thi
on if you need to profile the system's use of these macros.
config PROFILE_ALL_BRANCHES
@@ -333,7 +333,7 @@ config BLK_DEV_IO_TRACE
select GENERIC_TRACER
select STACKTRACE
help
- Say Y here if you want to be able to trace the block layer actions
+ Say Y here if you want to be able to trace the block layer action
on a given queue. Tracing allows you to see any traffic happening
on a block device queue. For more information (and the userspace
support tools needed), fetch the blktrace tools from:
@@ -351,9 +351,8 @@ config BLK_DEV_IO_TRACE
config KPROBE_EVENT
depends on KPROBES
depends on HAVE_REGS_AND_STACK_ACCESS_API
+ depends on PROBE_EVENTS
bool "Enable kprobes-based dynamic events"
- select TRACING
- select PROBE_EVENTS
default y
help
This allows the user to add tracing events (similar to tracepoints)
@@ -370,10 +369,9 @@ config UPROBE_EVENT
bool "Enable uprobes-based dynamic events"
depends on ARCH_SUPPORTS_UPROBES
depends on MMU
+ depends on PROBE_EVENTS
select UPROBES
- select PROBE_EVENTS
- select TRACING
- default n
+ default y
help
This allows the user to add tracing events on top of userspace dynamic
events (similar to tracepoints) on the fly via the traceevents interface.
@@ -383,7 +381,18 @@ config UPROBE_EVENT
tools on user space applications.
config PROBE_EVENTS
- def_bool n
+ bool "Enable kprobes and uprobe based dynamic events"
+ select TRACING
+ default n
+ help
+ This allows a user to add dynamic tracing events in
+ kernel using kprobe-tracer and in userspace using
+ uprobe-tracer. However users can still selectively
+ disable one of these events.
+
+ For more information on kprobe-tracer and uprobe-tracer
+ please refer help under KPROBE_EVENT and UPROBE_EVENT
+ respectively.
config DYNAMIC_FTRACE
bool "enable/disable ftrace tracepoints dynamically"
@@ -393,14 +402,14 @@ config DYNAMIC_FTRACE
help
This option will modify all the calls to ftrace dynamically
(will patch them out of the binary image and replace them
- with a No-Op instruction) as they are called. A table is
+ with a No-Op instruction) as they are called. A table i
created to dynamically enable them again.
This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but
otherwise has native performance as long as no tracing is active.
The changes to the code are done by a kernel thread that
- wakes up once a second and checks to see if any ftrace calls
+ wakes up once a second and checks to see if any ftrace call
were made. If so, it runs stop_machine (stops all CPUS)
and modifies the code to jump over the call to ftrace.
@@ -432,7 +441,7 @@ config FTRACE_STARTUP_TEST
select FTRACE_SELFTEST
help
This option performs a series of startup tests on ftrace. On bootup
- a series of tests are made to verify that the tracer is
+ a series of tests are made to verify that the tracer i
functioning properly. It will do tests on all the configured
tracers of ftrace.
@@ -441,12 +450,12 @@ config EVENT_TRACE_TEST_SYSCALLS
depends on FTRACE_STARTUP_TEST
help
This option will also enable testing every syscall event.
- It only enables the event and disables it and runs various loads
+ It only enables the event and disables it and runs various load
with the event enabled. This adds a bit more time for kernel boot
up since it runs this on every system call defined.
TBD - enable a way to actually call the syscalls as we test their
- events
+ event
config MMIOTRACE
bool "Memory mapped IO tracing"
@@ -465,7 +474,7 @@ config MMIOTRACE_TEST
tristate "Test module for mmiotrace"
depends on MMIOTRACE && m
help
- This is a dumb module for testing mmiotrace. It is very dangerous
+ This is a dumb module for testing mmiotrace. It is very dangerou
as it will write garbage to IO memory starting at a given address.
However, it should be safe to use on e.g. unused portion of VRAM.
@@ -477,9 +486,9 @@ config RING_BUFFER_BENCHMARK
help
This option creates a test to stress the ring buffer and benchmark it.
It creates its own ring buffer such that it will not interfere with
- any other users of the ring buffer (such as ftrace). It then creates
+ any other users of the ring buffer (such as ftrace). It then create
a producer and consumer that will run for 10 seconds and sleep for
- 10 seconds. Each interval it will print out the number of events
+ 10 seconds. Each interval it will print out the number of event
it recorded and give a rough estimate of how long each iteration took.
It does not disable interrupts or raise its priority, so it may be
Introduces map_groups_for_each_map that iterates over a map_group.
This is useful while listing functions through perf-probe.
Signed-off-by: Srikar Dronamraju <[email protected]>
Suggested-by: Arnaldo Carvalho de Melo <[email protected]>
---
tools/perf/util/map.h | 27 +++++++++++++++++++++++++++
1 files changed, 27 insertions(+), 0 deletions(-)
diff --git a/tools/perf/util/map.h b/tools/perf/util/map.h
index 7857579..45b5f50 100644
--- a/tools/perf/util/map.h
+++ b/tools/perf/util/map.h
@@ -54,6 +54,33 @@ struct map_groups {
struct machine *machine;
};
+/* For map_groups iteration */
+static inline struct map *map__first(struct map_groups *self,
+ enum map_type type)
+{
+ struct rb_node *rn = rb_first(&self->maps[type]);
+ return rn ? rb_entry(rn, struct map, rb_node) : NULL;
+}
+
+static inline struct map *map__next(struct map *map)
+{
+ struct rb_node *rn;
+ if (!map)
+ return NULL;
+ rn = rb_next(&map->rb_node);
+ return rn ? rb_entry(rn, struct map, rb_node) : NULL;
+}
+
+/**
+ * map_groups__for_each_map - iterate over a map_group
+ * @pos: the &struct map to use as a loop cursor.
+ * @type: the map type.
+ * @self: the &struct map_groups for loop.
+ */
+#define map_groups__for_each_map(pos, type, self) \
+ for (pos = map__first(self, type); pos; \
+ pos = map__next(pos))
+
/* Native host kernel uses -1 as pid index in machine */
#define HOST_KERNEL_ID (-1)
#define DEFAULT_GUEST_KERNEL_ID (0)
Introduces an option to list potential probes to probe using perf probe
command. Also introduces an option to limit the dso to list the potential
probes. Listing of potential probes is sorted by dso and
alphabetical order.
Signed-off-by: Srikar Dronamraju <[email protected]>
---
Changelog from V9:
Filter labels, weak, and local binding functions from listing
as suggested by Christoph Hellwig.
Incorporated comments from Arnaldo on Version 9 of patchset.
Show all potential probes in the current running kernel and limit to
the last 10 functions.
# perf probe -S | tail
zlib_inflateInit2
zlib_inflateReset
zlib_inflate_blob
zlib_inflate_table
zlib_inflate_workspacesize
zone_pcp_update
zone_reclaim
zone_reclaimable_pages
zone_statistics
zone_watermark_ok
Show all potential probes in a process by pid 3104 across all dsos
and limit to the last 10 functions.
# perf probe -S -p 3104 | tail
_nss_files_setgrent
_nss_files_sethostent
_nss_files_setnetent
_nss_files_setnetgrent
_nss_files_setprotoent
_nss_files_setpwent
_nss_files_setrpcent
_nss_files_setservent
_nss_files_setspent
_nss_netgroup_parseline
Show all potentail probes in a process by pid 3104 limit to zsh dso
and limit to the last 10 functions.
# perf probe -S -p 3104 -D zsh | tail
zstrtol
ztrcmp
ztrdup
ztrduppfx
ztrftime
ztrlen
ztrncpy
ztrsub
zwarn
zwarnnam
tools/perf/builtin-probe.c | 2 +
tools/perf/util/probe-event.c | 68 +++++++++++++++++++++++++++++++++--------
tools/perf/util/probe-event.h | 4 +-
3 files changed, 56 insertions(+), 18 deletions(-)
diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
index afca6ae..f5893d9 100644
--- a/tools/perf/builtin-probe.c
+++ b/tools/perf/builtin-probe.c
@@ -274,7 +274,7 @@ int cmd_probe(int argc, const char **argv, const char *prefix __used)
" --line.\n");
usage_with_options(probe_usage, options);
}
- ret = show_possible_probes(params.limitlist);
+ ret = show_possible_probes(params.limitlist, params.upid);
if (ret < 0)
pr_err(" Error: Failed to show possible"
" probes (%d).\n", ret);
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 17a89b1..58146a7 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -1923,7 +1923,6 @@ int del_perf_probe_events(struct strlist *dellist, pid_t pid)
struct str_node *ent;
struct strlist *namelist = NULL, *unamelist = NULL;
-
/* Get current event names */
if (!pid) {
kfd = open_kprobe_events(true);
@@ -2014,27 +2013,46 @@ static int print_list_available_symbols(struct map *map,
return 0;
}
-int show_possible_probes(struct strlist *limitlist)
+int show_possible_probes(struct strlist *limitlist, pid_t pid)
{
+ struct perf_session *session = NULL;
+ struct thread *thread = NULL;
struct str_node *ent;
struct map *map = NULL;
- char *str;
+ char *name = NULL, *tmpname = NULL, *str;
int ret = -EINVAL;
- if (!limitlist) { /* Show functions in kernel */
+ if (!pid && !limitlist) { /* Show functions in kernel */
ret = init_vmlinux();
if (ret < 0)
return ret;
return print_list_available_symbols(
machine.vmlinux_maps[MAP__FUNCTION], NULL);
+ } else {
+ ret = init_perf_uprobes();
+ if (ret < 0)
+ return ret;
}
-
- symbol_conf.try_vmlinux_path = false;
- symbol_conf.sort_by_name = true;
- ret = symbol__init();
- if (ret < 0) {
- pr_debug("Failed to init symbol map.\n");
- return ret;
+ if (pid) {
+ session = perf_session__new(NULL, O_WRONLY, false, false);
+ if (!session) {
+ ret = -ENOMEM;
+ goto out_delete;
+ }
+ event__synthesize_thread(pid, event__process, session);
+ thread = perf_session__findnew(session, pid);
+ if (!thread)
+ goto out_delete;
+ if (!limitlist) {
+ map_groups__for_each_map(map, MAP__FUNCTION,
+ &thread->mg) {
+ ret = print_list_available_symbols(map, NULL);
+ if (ret)
+ pr_warning("No Symbols in dso %s.\n",
+ map->dso->short_name);
+ }
+ goto out_delete;
+ }
}
strlist__for_each(ent, limitlist) {
@@ -2044,18 +2062,40 @@ int show_possible_probes(struct strlist *limitlist)
goto out_delete;
}
- map = dso__new_map(str);
+ if (pid) {
+ tmpname = realpath(str, NULL);
+ if (tmpname)
+ name = basename(tmpname);
+ if (!name)
+ name = str;
+ map = map_groups__find_by_name(&thread->mg,
+ MAP__FUNCTION, name);
+ if (tmpname)
+ free(tmpname);
+ if (!map) {
+ pr_warning("Skip probe listing in %s DSO.\n",
+ str);
+ free(str);
+ continue;
+ }
+ } else
+ map = dso__new_map(str);
+
ret = print_list_available_symbols(map, NULL);
if (ret)
pr_warning("No Symbols in dso %s.\n", str);
- dso__delete(map->dso);
- map__delete(map);
+ if (!pid) {
+ dso__delete(map->dso);
+ map__delete(map);
+ }
free(str);
}
out_delete:
if (ret)
pr_warning("Failed to list available probes.\n");
+ if (session)
+ perf_session__delete(session);
return ret;
}
diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
index 9cf1bcc..4a40d2c 100644
--- a/tools/perf/util/probe-event.h
+++ b/tools/perf/util/probe-event.h
@@ -111,14 +111,12 @@ extern void clear_perf_probe_event(struct perf_probe_event *pev);
/* Command string to line-range */
extern int parse_line_range_desc(const char *cmd, struct line_range *lr);
-
extern int add_perf_probe_events(struct perf_probe_event *pevs, int npevs,
bool force_add, int max_probe_points);
extern int del_perf_probe_events(struct strlist *dellist, pid_t pid);
extern int show_perf_probe_events(void);
extern int show_line_range(struct line_range *lr);
-extern int show_possible_probes(struct strlist *availlist);
-
+extern int show_possible_probes(struct strlist *availlist, pid_t pid);
/* Maximum index number of event-name postfix */
#define MAX_EVENT_INDEX 1024
Enhances perf probe to accept pid and user vaddr.
Provides very basic support for uprobes.
TODO:
Update perf-probes.txt.
Global tracing.
Signed-off-by: Srikar Dronamraju <[email protected]>
---
Changelog from V10: split few independent hunks into different
patches as suggested by Arnaldo.
Changelog from v9: Renaming common fields/functions to refer to
probe instead of kprobe. This was suggested by Arnaldo.
Changelog from v8: Fixed a build break reported by Christoph Hellwig.
Changelog from v6: Changelog from v6: Fixed a bug reported by Masami.
i.e Throw an error message and exit if perf probe is for a dwarf
based probes.
Changelog from v4: Merged to 2.6.35-rc3-tip.
Changelog from v3: (addressed comments from Masami Hiramatsu)
* Every process id has a different group name.
* event name starts with function name.
* If vaddr is specified, event name has vaddr appended
along with function name, (this is to avoid subsequent probes
using same event name.)
* warning if -p and --list options are used together.
Also dso can either be a short name or absolute path.
Here is a terminal snapshot of placing, using and removing a probe on a
process with pid 3591 (corresponding to zsh)
[ Probing a function in the executable using function name ]
-------------------------------------------------------------
[root@ABCD]# perf probe -p 3591 zfree@zsh
Added new event:
probe_3591:zfree (on 0x446420)
You can now use it on all perf tools, such as:
perf record -e probe_3591:zfree -a sleep 1
[root@ABCD]# perf probe --list
probe_3591:zfree (on 3591:0x0000000000446420)
[root@ABCD]# cat /sys/kernel/debug/tracing/uprobe_events
p:probe_3591/zfree 3591:0x0000000000446420
[root@ABCD]# perf record -f -e probe_3591:zfree -a sleep 10
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.039 MB perf.data (~1716 samples) ]
[root@ABCD]# perf probe -p 3591 --del probe_3591:zfree
Remove event: probe_3591:zfree
[root@ABCD]# perf report
# Samples: 447
#
# Overhead Command Shared Object Symbol
# ........ ............... ............. ......
#
100.00% zsh zsh [.] zfree
#
# (For a higher level overview, try: perf report --sort comm,dso)
#
[ Probing a function + offset ]
-------------------------------
[root@ABCD]# perf probe -p 3591 zfree@zsh+5
Added new event:
probe_3591:zfree (on 0x446425)
You can now use it on all perf tools, such as:
perf record -e probe_3591:zfree -a sleep 1
[root@ABCD]# perf probe --list
probe_3591:zfree (on 3591:0x0000000000446425)
[root@ABCD]# cat /sys/kernel/debug/tracing/uprobe_events
p:probe_3591/zfree 3591:0x0000000000446425
[root@ABCD]# perf record -f -e probe_3591:zfree -a sleep 10
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.036 MB perf.data (~1590 samples) ]
[root@ABCD]# perf probe -p 3591 --del probe_3591:zfree
Remove event: probe_3591:zfree
[root@ABCD]# perf report
# Samples: 18
#
# Overhead Command Shared Object Symbol
# ........ ............... ............. ......
#
100.00% zsh zsh [.] zfree
#
# (For a higher level overview, try: perf report --sort comm,dso)
#
[ Probing a library function using function name ]
--------------------------------------------------
[root@ABCD]# perf probe -p 3591 [email protected]
Added new event:
probe_3591:write (on 0x36010c6060)
You can now use it on all perf tools, such as:
perf record -e probe_3591:write -a sleep 1
[root@ABCD]# perf probe --list
probe_3591:write (on 3591:0x00000036010c6060)
[root@ABCD]# cat /sys/kernel/debug/tracing/uprobe_events
p:probe_3591/write 3591:0x00000036010c6060
[root@ABCD]# perf record -f -e probe_3591:write -a sleep 10
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.040 MB perf.data (~1738 samples) ]
[root@ABCD]# perf probe -p 3591 --del probe_3591:write
Remove event: probe_3591:write
[root@ABCD]# perf report
# Samples: 11
#
# Overhead Command Shared Object Symbol
# ........ ............... .................. ......
#
100.00% zsh libc-2.5.so [.] __GI___libc_write
#
# (For a higher level overview, try: perf report --sort comm,dso)
#
[ Probing a library function using function name and absolute path ]
---------------------------------------------------------------------
[root@ABCD]# perf probe -p 3591 write@/lib64/libc-2.5.so
Added new event:
probe_3591:write (on 0x36010c6060)
You can now use it on all perf tools, such as:
perf record -e probe_3591:write -a sleep 1
[root@ABCD]# perf probe --list
probe_3591:write (on 3591:0x00000036010c6060)
[root@ABCD]# cat /sys/kernel/debug/tracing/uprobe_events
p:probe_3591/write 3591:0x00000036010c6060
[root@ABCD]# perf record -f -e probe_3591:write -a sleep 10
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.040 MB perf.data (~1738 samples) ]
[root@ABCD]# perf probe -p 3591 --del probe_3591:write
Remove event: probe_3591:write
[root@ABCD]# perf report
# Samples: 11
#
# Overhead Command Shared Object Symbol
# ........ ............... .................. ......
#
100.00% zsh libc-2.5.so [.] __GI___libc_write
#
# (For a higher level overview, try: perf report --sort comm,dso)
#
[ Probing using vaddr 0x0000000000446420 (corresponding to zfree)]
-------------------------------------------------------------------
[root@ABCD]# perf probe -p 3591 0x0000000000446420
Added new event:
probe_3591:zfree_446420 (on 0x0000000000446420)
You can now use it on all perf tools, such as:
perf record -e probe_3591:zfree_446420 -a sleep 1
[root@ABCD]# perf record -e probe_3591:zfree_446420 -a sleep 10
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.041 MB perf.data (~1797 samples) ]
[root@ABCD]# perf report
#
# Samples: 628
#
# Overhead Command Shared Object Symbol
# ........ ............... ............. ......
#
100.00% zsh zsh [.] zfree
#
# (For a higher level overview, try: perf report --sort comm,dso)
#
[root@ABCD]# perf report --sort comm,dso
# Samples: 628
#
# Overhead Command Shared Object
# ........ ............... .............
#
100.00% zsh zsh
[root@ABCD]# perf probe --list
probe_3591:zfree_446420 (on 3591:0x0000000000446420)
[root@ABCD]# perf list | grep probe
probe_3591:zfree_446420 [Tracepoint event]
[root@ABCD]# perf probe -p 3591 --del probe_3591:zfree_446420
Remove event: probe_3591:zfree_446420
[root@ABCD]#
Another example for a shared library: write stub in libc. (corresponds to
0x00000036010c6060)
on a vaddr
[ Probing a libc vaddr 0x00000036010c6060 (corresponding to write) ]
[root@ABCD]# perf probe -p 3591 0x00000036010c6060
dded new event:
probe_3591:__GI___libc_write_36010c6060 (on 0x00000036010c6060)
You can now use it on all perf tools, such as:
perf record -e probe_3591:__GI___libc_write_36010c6060 -a sleep 1
[root@ABCD]# perf record -f -e probe_3591:__GI___libc_write_36010c6060 -a sleep 10
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.040 MB perf.data (~1748 samples) ]
[root@ABCD]# perf report
# Samples: 24
#
# Overhead Command Shared Object Symbol
# ........ ............... .................. ......
#
100.00% zsh libc-2.5.so [.] __GI___libc_write
#
# (For a higher level overview, try: perf report --sort comm,dso)
#
[root@ABCD]#
[ Probing using a function without specifying a dso (corresponding to zfree)]
-------------------------------------------------------------------
[root@ABCD]# perf probe -p 3591 zfree
Added new event:
probe_3591:zfree (on 0x0000000000446420)
You can now use it on all perf tools, such as:
perf record -e probe_3591:zfree -a sleep 1
[root@ABCD]# perf record -e probe_3591:zfree -a sleep 10
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.041 MB perf.data (~1797 samples) ]
[root@ABCD]# perf report
#
# Samples: 628
#
# Overhead Command Shared Object Symbol
# ........ ............... ............. ......
#
100.00% zsh zsh [.] zfree
#
# (For a higher level overview, try: perf report --sort comm,dso)
#
[root@ABCD]#
tools/perf/builtin-probe.c | 12 +
tools/perf/util/probe-event.c | 389 +++++++++++++++++++++++++++++++++--------
tools/perf/util/probe-event.h | 10 +
3 files changed, 328 insertions(+), 83 deletions(-)
diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
index fa63245..afca6ae 100644
--- a/tools/perf/builtin-probe.c
+++ b/tools/perf/builtin-probe.c
@@ -57,6 +57,7 @@ static struct {
struct strlist *limitlist;
struct line_range line_range;
int max_probe_points;
+ pid_t upid;
} params;
@@ -75,6 +76,7 @@ static int parse_probe_event(const char *str)
/* Parse a perf-probe command into event */
ret = parse_perf_probe_command(str, pev);
pr_debug("%d arguments\n", pev->nargs);
+ pev->upid = params.upid;
return ret;
}
@@ -207,6 +209,8 @@ static const struct option options[] = {
"Show potential probes."),
OPT_CALLBACK('D', "limit_dsos", NULL, "DSO",
"Limit Dsos.", opt_limit_dsos),
+ OPT_INTEGER('p', "pid", ¶ms.upid,
+ "Specify pid of process where probe will be added"),
OPT_END()
};
@@ -249,6 +253,10 @@ int cmd_probe(int argc, const char **argv, const char *prefix __used)
" --show_functions.\n");
usage_with_options(probe_usage, options);
}
+ if (params.upid) {
+ pr_warning(" Error: Don't use --list with --pid.\n");
+ usage_with_options(probe_usage, options);
+ }
ret = show_perf_probe_events();
if (ret < 0)
pr_err(" Error: Failed to show event list. (%d)\n",
@@ -274,7 +282,7 @@ int cmd_probe(int argc, const char **argv, const char *prefix __used)
}
#ifdef DWARF_SUPPORT
- if (params.show_lines) {
+ if (params.show_lines && !params.upid) {
if (params.nevents != 0 || params.dellist) {
pr_warning(" Error: Don't use --line with"
" --add/--del.\n");
@@ -289,7 +297,7 @@ int cmd_probe(int argc, const char **argv, const char *prefix __used)
#endif
if (params.dellist) {
- ret = del_perf_probe_events(params.dellist);
+ ret = del_perf_probe_events(params.dellist, params.upid);
strlist__delete(params.dellist);
if (ret < 0) {
pr_err(" Error: Failed to delete events. (%d)\n", ret);
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 2efbe4b..17a89b1 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -74,6 +74,7 @@ static int e_snprintf(char *str, size_t size, const char *format, ...)
}
static char *synthesize_perf_probe_point(struct perf_probe_point *pp);
+static int convert_name_to_addr(struct perf_probe_event *pev);
static struct machine machine;
/* Initialize symbol maps and path of vmlinux */
@@ -111,6 +112,32 @@ out:
return ret;
}
+static int init_perf_uprobes(void)
+{
+ int ret = 0;
+
+ symbol_conf.try_vmlinux_path = false;
+ symbol_conf.sort_by_name = true;
+ ret = symbol__init();
+ if (ret < 0)
+ pr_debug("Failed to init symbol map.\n");
+
+ return ret;
+}
+
+
+static int convert_to_perf_probe_point(struct probe_trace_point *tp,
+ struct perf_probe_point *pp)
+{
+ pp->function = strdup(tp->symbol);
+ if (pp->function == NULL)
+ return -ENOMEM;
+ pp->offset = tp->offset;
+ pp->retprobe = tp->retprobe;
+
+ return 0;
+}
+
#ifdef DWARF_SUPPORT
static int open_vmlinux(void)
{
@@ -163,6 +190,15 @@ static int try_to_find_probe_trace_events(struct perf_probe_event *pev,
bool need_dwarf = perf_probe_event_need_dwarf(pev);
int fd, ntevs;
+ if (pev->upid) {
+ if (need_dwarf) {
+ pr_warning("Debuginfo-analysis is not yet supported"
+ " with -p/--pid option.\n");
+ return -ENOSYS;
+ }
+ return convert_name_to_addr(pev);
+ }
+
fd = open_vmlinux();
if (fd < 0) {
if (need_dwarf) {
@@ -385,13 +421,7 @@ end:
static int kprobe_convert_to_perf_probe(struct probe_trace_point *tp,
struct perf_probe_point *pp)
{
- pp->function = strdup(tp->symbol);
- if (pp->function == NULL)
- return -ENOMEM;
- pp->offset = tp->offset;
- pp->retprobe = tp->retprobe;
-
- return 0;
+ return convert_to_perf_probe_point(tp, pp);
}
static int try_to_find_probe_trace_events(struct perf_probe_event *pev,
@@ -402,6 +432,9 @@ static int try_to_find_probe_trace_events(struct perf_probe_event *pev,
pr_warning("Debuginfo-analysis is not supported.\n");
return -ENOSYS;
}
+ if (pev->upid)
+ return convert_name_to_addr(pev);
+
return 0;
}
@@ -477,6 +510,109 @@ static bool check_event_name(const char *name)
return true;
}
+/*
+ * uprobe_events only accepts address:
+ * Convert function and any offset to address
+ */
+static int convert_name_to_addr(struct perf_probe_event *pev)
+{
+ struct perf_probe_point *pp = &pev->point;
+ struct perf_session *session;
+ struct thread *thread;
+ struct symbol *sym;
+ struct map *map;
+ char *name = NULL, *tmpname = NULL;
+ int ret = -EINVAL;
+ unsigned long long vaddr;
+
+ /* check if user has specifed a virtual address */
+ vaddr = strtoul(pp->function, NULL, 0);
+ session = perf_session__new(NULL, O_WRONLY, false, false);
+ if (!session) {
+ pr_warning("Cannot initialize perf session.\n");
+ return -ENOMEM;
+ }
+
+ event__synthesize_thread(pev->upid, event__process, session);
+ thread = perf_session__findnew(session, pev->upid);
+ if (!thread) {
+ pr_warning("Cannot initialize perf session.\n");
+ goto free_session;
+ }
+
+ if (vaddr) {
+ if (pev->event) {
+ ret = 0;
+ goto free_session;
+ }
+
+ pev->event = zalloc(sizeof(char *) * MAX_PROBE_ARGS);
+ if (!pev->event) {
+ ret = -ENOMEM;
+ pr_warning("Cannot allocate memory for event.\n");
+ goto free_session;
+ }
+
+ sym = map_groups__find_symbol(&thread->mg, MAP__FUNCTION,
+ vaddr, NULL, NULL);
+ if (!sym)
+ snprintf(pev->event, MAX_PROBE_ARGS, "p_%llx", vaddr);
+ else
+ snprintf(pev->event, MAX_PROBE_ARGS, "%s_%llx",
+ sym->name, vaddr);
+ ret = 0;
+ goto free_session;
+ }
+
+ if (!pp->file)
+ /* Lets find the function in the executable. */
+ name = thread->comm;
+ else {
+ tmpname = realpath(pp->file, NULL);
+ if (tmpname)
+ name = basename(tmpname);
+ else
+ name = pp->file;
+ }
+
+ map = map_groups__find_by_name(&thread->mg, MAP__FUNCTION, name);
+ if (pp->file && tmpname)
+ free(tmpname);
+ if (!map) {
+ pr_warning("Cannot find appropriate DSO.\n");
+ goto free_session;
+ }
+
+ sym = map__find_symbol_by_name(map, pp->function, NULL);
+ if (!sym) {
+ pr_warning("Cannot find appropriate DSO.\n");
+ goto free_session;
+ }
+
+ if (map->start > sym->start)
+ vaddr = map->start;
+ vaddr += sym->start + pp->offset + map->pgoff;
+ pp->offset = 0;
+
+ if (!pev->event)
+ pev->event = pp->function;
+ else
+ free(pp->function);
+ pp->function = zalloc(sizeof(char *) * MAX_PROBE_ARGS);
+ if (!pp->function) {
+ ret = -ENOMEM;
+ pr_warning("Failed to allocate memory by zalloc.\n");
+ goto free_session;
+ }
+ e_snprintf(pp->function, MAX_PROBE_ARGS, "0x%llx", vaddr);
+ ret = 0;
+
+free_session:
+ if (session)
+ perf_session__delete(session);
+ return ret;
+}
+
/* Parse probepoint definition. */
static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
{
@@ -616,6 +752,11 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
return -EINVAL;
}
+ if (pev->upid && !pp->function) {
+ semantic_error("No function specified for uprobes");
+ return -EINVAL;
+ }
+
if ((pp->offset || pp->line || pp->lazy_line) && pp->retprobe) {
semantic_error("Offset/Line/Lazy pattern can't be used with "
"return probe.");
@@ -625,6 +766,11 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
pr_debug("symbol:%s file:%s line:%d offset:%lu return:%d lazy:%s\n",
pp->function, pp->file, pp->line, pp->offset, pp->retprobe,
pp->lazy_line);
+
+ if (pev->upid && perf_probe_event_need_dwarf(pev)) {
+ semantic_error("no dwarf based probes for uprobes.");
+ return -EINVAL;
+ }
return 0;
}
@@ -776,7 +922,8 @@ bool perf_probe_event_need_dwarf(struct perf_probe_event *pev)
{
int i;
- if (pev->point.file || pev->point.line || pev->point.lazy_line)
+ if ((pev->point.file && !pev->upid) || pev->point.line ||
+ pev->point.lazy_line)
return true;
for (i = 0; i < pev->nargs; i++)
@@ -1067,10 +1214,22 @@ char *synthesize_probe_trace_command(struct probe_trace_event *tev)
if (buf == NULL)
return NULL;
- len = e_snprintf(buf, MAX_CMDLEN, "%c:%s/%s %s+%lu",
- tp->retprobe ? 'r' : 'p',
- tev->group, tev->event,
- tp->symbol, tp->offset);
+ if (tev->upid)
+ len = e_snprintf(buf, MAX_CMDLEN, "%c:%s/%s %d:%s",
+ tp->retprobe ? 'r' : 'p',
+ tev->group, tev->event,
+ tev->upid, tp->symbol);
+ else if (tp->offset)
+ len = e_snprintf(buf, MAX_CMDLEN, "%c:%s/%s %s+%lu",
+ tp->retprobe ? 'r' : 'p',
+ tev->group, tev->event,
+ tp->symbol, tp->offset);
+ else
+ len = e_snprintf(buf, MAX_CMDLEN, "%c:%s/%s %s",
+ tp->retprobe ? 'r' : 'p',
+ tev->group, tev->event,
+ tp->symbol);
+
if (len <= 0)
goto error;
@@ -1089,7 +1248,7 @@ error:
}
static int convert_to_perf_probe_event(struct probe_trace_event *tev,
- struct perf_probe_event *pev)
+ struct perf_probe_event *pev, bool is_kprobe)
{
char buf[64] = "";
int i, ret;
@@ -1101,7 +1260,11 @@ static int convert_to_perf_probe_event(struct probe_trace_event *tev,
return -ENOMEM;
/* Convert trace_point to probe_point */
- ret = kprobe_convert_to_perf_probe(&tev->point, &pev->point);
+ if (is_kprobe)
+ ret = kprobe_convert_to_perf_probe(&tev->point, &pev->point);
+ else
+ ret = convert_to_perf_probe_point(&tev->point, &pev->point);
+
if (ret < 0)
return ret;
@@ -1195,7 +1358,7 @@ static void clear_probe_trace_event(struct probe_trace_event *tev)
memset(tev, 0, sizeof(*tev));
}
-static int open_kprobe_events(bool readwrite)
+static int open_probe_events(bool readwrite, bool is_kprobe)
{
char buf[PATH_MAX];
const char *__debugfs;
@@ -1206,8 +1369,13 @@ static int open_kprobe_events(bool readwrite)
pr_warning("Debugfs is not mounted.\n");
return -ENOENT;
}
+ if (is_kprobe)
+ ret = e_snprintf(buf, PATH_MAX, "%stracing/kprobe_events",
+ __debugfs);
+ else
+ ret = e_snprintf(buf, PATH_MAX, "%stracing/uprobe_events",
+ __debugfs);
- ret = e_snprintf(buf, PATH_MAX, "%stracing/kprobe_events", __debugfs);
if (ret >= 0) {
pr_debug("Opening %s write=%d\n", buf, readwrite);
if (readwrite && !probe_event_dry_run)
@@ -1218,16 +1386,29 @@ static int open_kprobe_events(bool readwrite)
if (ret < 0) {
if (errno == ENOENT)
- pr_warning("kprobe_events file does not exist - please"
- " rebuild kernel with CONFIG_KPROBE_EVENT.\n");
+ pr_warning("%s file does not exist - please"
+ " rebuild kernel with CONFIG_%s_EVENT.\n",
+ is_kprobe ? "kprobe_events" : "uprobe_events",
+ is_kprobe ? "KPROBE" : "UPROBE");
else
- pr_warning("Failed to open kprobe_events file: %s\n",
- strerror(errno));
+ pr_warning("Failed to open %s file: %s\n",
+ is_kprobe ? "kprobe_events" : "uprobe_events",
+ strerror(errno));
}
return ret;
}
-/* Get raw string list of current kprobe_events */
+static int open_kprobe_events(bool readwrite)
+{
+ return open_probe_events(readwrite, 1);
+}
+
+static int open_uprobe_events(bool readwrite)
+{
+ return open_probe_events(readwrite, 0);
+}
+
+/* Get raw string list of current kprobe_events or uprobe_events */
static struct strlist *get_probe_trace_command_rawlist(int fd)
{
int ret, idx;
@@ -1292,36 +1473,26 @@ static int show_perf_probe_event(struct perf_probe_event *pev)
return ret;
}
-/* List up current perf-probe events */
-int show_perf_probe_events(void)
+static int __show_perf_probe_events(int fd, bool is_kprobe)
{
- int fd, ret;
+ int ret = 0;
struct probe_trace_event tev;
struct perf_probe_event pev;
struct strlist *rawlist;
struct str_node *ent;
- setup_pager();
- ret = init_vmlinux();
- if (ret < 0)
- return ret;
-
memset(&tev, 0, sizeof(tev));
memset(&pev, 0, sizeof(pev));
- fd = open_kprobe_events(false);
- if (fd < 0)
- return fd;
-
rawlist = get_probe_trace_command_rawlist(fd);
- close(fd);
if (!rawlist)
return -ENOENT;
strlist__for_each(ent, rawlist) {
ret = parse_probe_trace_command(ent->s, &tev);
if (ret >= 0) {
- ret = convert_to_perf_probe_event(&tev, &pev);
+ ret = convert_to_perf_probe_event(&tev, &pev,
+ is_kprobe);
if (ret >= 0)
ret = show_perf_probe_event(&pev);
}
@@ -1331,6 +1502,31 @@ int show_perf_probe_events(void)
break;
}
strlist__delete(rawlist);
+ return ret;
+}
+
+/* List up current perf-probe events */
+int show_perf_probe_events(void)
+{
+ int fd, ret;
+
+ setup_pager();
+ fd = open_kprobe_events(false);
+ if (fd < 0)
+ return fd;
+
+ ret = init_vmlinux();
+ if (ret < 0)
+ return ret;
+
+ ret = __show_perf_probe_events(fd, true);
+ close(fd);
+
+ fd = open_uprobe_events(false);
+ if (fd >= 0) {
+ ret = __show_perf_probe_events(fd, false);
+ close(fd);
+ }
return ret;
}
@@ -1440,7 +1636,10 @@ static int __add_probe_trace_events(struct perf_probe_event *pev,
const char *event, *group;
struct strlist *namelist;
- fd = open_kprobe_events(true);
+ if (pev->upid)
+ fd = open_uprobe_events(true);
+ else
+ fd = open_kprobe_events(true);
if (fd < 0)
return fd;
/* Get current event names */
@@ -1454,17 +1653,26 @@ static int __add_probe_trace_events(struct perf_probe_event *pev,
printf("Add new event%s\n", (ntevs > 1) ? "s:" : ":");
for (i = 0; i < ntevs; i++) {
tev = &tevs[i];
- if (pev->event)
- event = pev->event;
- else
- if (pev->point.function)
- event = pev->point.function;
- else
- event = tev->point.symbol;
+
if (pev->group)
group = pev->group;
- else
+ else if (!pev->upid)
group = PERFPROBE_GROUP;
+ else {
+ /*
+ * For uprobes based probes create a group
+ * probe_<pid>.
+ */
+ snprintf(buf, 64, "%s_%d", PERFPROBE_GROUP, pev->upid);
+ group = buf;
+ }
+
+ if (pev->event)
+ event = pev->event;
+ else if (pev->point.function)
+ event = pev->point.function;
+ else
+ event = tev->point.symbol;
/* Get an unused new event name */
ret = get_new_event_name(buf, 64, event,
@@ -1572,6 +1780,11 @@ static int convert_to_probe_trace_events(struct perf_probe_event *pev,
}
}
+ if (pev->upid) {
+ tev->upid = pev->upid;
+ return 1;
+ }
+
/* Currently just checking function name from symbol map */
sym = map__find_symbol_by_name(machine.vmlinux_maps[MAP__FUNCTION],
tev->point.symbol, NULL);
@@ -1599,15 +1812,19 @@ struct __event_package {
int add_perf_probe_events(struct perf_probe_event *pevs, int npevs,
bool force_add, int max_tevs)
{
- int i, j, ret;
+ int i, j, ret = 0;
struct __event_package *pkgs;
pkgs = zalloc(sizeof(struct __event_package) * npevs);
if (pkgs == NULL)
return -ENOMEM;
- /* Init vmlinux path */
- ret = init_vmlinux();
+ if (!pevs->upid)
+ /* Init vmlinux path */
+ ret = init_vmlinux();
+ else
+ ret = init_perf_uprobes();
+
if (ret < 0) {
free(pkgs);
return ret;
@@ -1672,23 +1889,15 @@ error:
return ret;
}
-static int del_trace_probe_event(int fd, const char *group,
- const char *event, struct strlist *namelist)
+static int del_trace_probe_event(int fd, const char *buf,
+ struct strlist *namelist)
{
- char buf[128];
struct str_node *ent, *n;
- int found = 0, ret = 0;
-
- ret = e_snprintf(buf, 128, "%s:%s", group, event);
- if (ret < 0) {
- pr_err("Failed to copy event.");
- return ret;
- }
+ int ret = -1;
if (strpbrk(buf, "*?")) { /* Glob-exp */
strlist__for_each_safe(ent, n, namelist)
if (strglobmatch(ent->s, buf)) {
- found++;
ret = __del_trace_probe_event(fd, ent);
if (ret < 0)
break;
@@ -1697,40 +1906,44 @@ static int del_trace_probe_event(int fd, const char *group,
} else {
ent = strlist__find(namelist, buf);
if (ent) {
- found++;
ret = __del_trace_probe_event(fd, ent);
if (ret >= 0)
strlist__remove(namelist, ent);
}
}
- if (found == 0 && ret >= 0)
- pr_info("Info: Event \"%s\" does not exist.\n", buf);
-
return ret;
}
-int del_perf_probe_events(struct strlist *dellist)
+int del_perf_probe_events(struct strlist *dellist, pid_t pid)
{
- int fd, ret = 0;
+ int ret = -1, ufd = -1, kfd = -1;
+ char buf[128];
const char *group, *event;
char *p, *str;
struct str_node *ent;
- struct strlist *namelist;
+ struct strlist *namelist = NULL, *unamelist = NULL;
- fd = open_kprobe_events(true);
- if (fd < 0)
- return fd;
/* Get current event names */
- namelist = get_probe_trace_event_names(fd, true);
- if (namelist == NULL)
- return -EINVAL;
+ if (!pid) {
+ kfd = open_kprobe_events(true);
+ if (kfd < 0)
+ return kfd;
+ namelist = get_probe_trace_event_names(kfd, true);
+ }
+
+ ufd = open_uprobe_events(true);
+ if (ufd >= 0)
+ unamelist = get_probe_trace_event_names(ufd, true);
+
+ if (namelist == NULL && unamelist == NULL)
+ goto error;
strlist__for_each(ent, dellist) {
str = strdup(ent->s);
if (str == NULL) {
ret = -ENOMEM;
- break;
+ goto error;
}
pr_debug("Parsing: %s\n", str);
p = strchr(str, ':');
@@ -1742,15 +1955,37 @@ int del_perf_probe_events(struct strlist *dellist)
group = "*";
event = str;
}
+
+ ret = e_snprintf(buf, 128, "%s:%s", group, event);
+ if (ret < 0) {
+ pr_err("Failed to copy event.");
+ free(str);
+ goto error;
+ }
+
pr_debug("Group: %s, Event: %s\n", group, event);
- ret = del_trace_probe_event(fd, group, event, namelist);
+ if (!pid && namelist)
+ ret = del_trace_probe_event(kfd, buf, namelist);
+ if (unamelist && ret != 0)
+ ret = del_trace_probe_event(ufd, buf, unamelist);
+
free(str);
- if (ret < 0)
- break;
+ if (ret != 0)
+ pr_info("Info: Event \"%s\" does not exist.\n", buf);
}
- strlist__delete(namelist);
- close(fd);
+error:
+ if (kfd >= 0) {
+ if (namelist)
+ strlist__delete(namelist);
+ close(kfd);
+ }
+
+ if (ufd >= 0) {
+ if (unamelist)
+ strlist__delete(unamelist);
+ close(ufd);
+ }
return ret;
}
diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
index fcd0f08..9cf1bcc 100644
--- a/tools/perf/util/probe-event.h
+++ b/tools/perf/util/probe-event.h
@@ -6,7 +6,7 @@
extern bool probe_event_dry_run;
-/* kprobe-tracer tracing point */
+/* kprobe-tracer and uprobe-tracer tracing point */
struct probe_trace_point {
char *symbol; /* Base symbol */
unsigned long offset; /* Offset from symbol */
@@ -19,7 +19,7 @@ struct probe_trace_arg_ref {
long offset; /* Offset value */
};
-/* kprobe-tracer tracing argument */
+/* kprobe-tracer and uprobe-tracer tracing argument */
struct probe_trace_arg {
char *name; /* Argument name */
char *value; /* Base value */
@@ -27,12 +27,13 @@ struct probe_trace_arg {
struct probe_trace_arg_ref *ref; /* Referencing offset */
};
-/* kprobe-tracer tracing event (point + arg) */
+/* kprobe-tracer and uprobe-tracer tracing event (point + arg) */
struct probe_trace_event {
char *event; /* Event name */
char *group; /* Group name */
struct probe_trace_point point; /* Trace point */
int nargs; /* Number of args */
+ pid_t upid; /* uprobes only */
struct probe_trace_arg *args; /* Arguments */
};
@@ -68,6 +69,7 @@ struct perf_probe_event {
char *group; /* Group name */
struct perf_probe_point point; /* Probe point */
int nargs; /* Number of arguments */
+ pid_t upid;
struct perf_probe_arg *args; /* Arguments */
};
@@ -112,7 +114,7 @@ extern int parse_line_range_desc(const char *cmd, struct line_range *lr);
extern int add_perf_probe_events(struct perf_probe_event *pevs, int npevs,
bool force_add, int max_probe_points);
-extern int del_perf_probe_events(struct strlist *dellist);
+extern int del_perf_probe_events(struct strlist *dellist, pid_t pid);
extern int show_perf_probe_events(void);
extern int show_line_range(struct line_range *lr);
extern int show_possible_probes(struct strlist *availlist);
Em Wed, Aug 25, 2010 at 07:13:29PM +0530, Srikar Dronamraju escreveu:
> Given a dso, list the symbols in ascending order. Needed for listing
> available symbols from perf-probe.
Applied after renaming it to 'dso__fprintf_symbols_by_name', as at first
I was scratching my head to figure out if we could reuse it in
dso__fprintf() to then notice that it is in ascending _name_ order, not
the default that is ordered by addr :-)
Please fixup the users, i.e. perf probe in your patchset.
- Arnaldo
* Arnaldo Carvalho de Melo <[email protected]> [2010-08-25 20:21:16]:
> Em Wed, Aug 25, 2010 at 07:13:29PM +0530, Srikar Dronamraju escreveu:
> > Given a dso, list the symbols in ascending order. Needed for listing
> > available symbols from perf-probe.
>
> Applied after renaming it to 'dso__fprintf_symbols_by_name', as at first
> I was scratching my head to figure out if we could reuse it in
> dso__fprintf() to then notice that it is in ascending _name_ order, not
> the default that is ordered by addr :-)
Okay, Thanks for pushing it up.
>
> Please fixup the users, i.e. perf probe in your patchset.
Yes, Shall send the refreshed patch now
--
Thanks and Regards
Srikar
(2010/08/25 22:43), Srikar Dronamraju wrote:
> Selecting CONFIG_PROBE_EVENTS enables both kprobe-based and
> uprobes-based dynamic events. However kprobe-tracer or uprobe-tracer
> can still be individually selected or disabled.
>
> Signed-off-by: Srikar Dronamraju <[email protected]>
> Suggested-by: Frederic Weisbecker <[email protected]>
> ---
> kernel/trace/Kconfig | 51 +++++++++++++++++++++++++++++---------------------
> 1 files changed, 30 insertions(+), 21 deletions(-)
>
> diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
> index 55ba474..205c12b 100644
> --- a/kernel/trace/Kconfig
> +++ b/kernel/trace/Kconfig
> @@ -76,7 +76,7 @@ config RING_BUFFER_ALLOW_SWAP
> # All tracer options should select GENERIC_TRACER. For those options that are
> # enabled by all tracers (context switch and event tracer) they select TRACING.
> # This allows those options to appear when no other tracer is selected. But the
> -# options do not appear when something else selects it. We need the two options
> +# options do not appear when something else selects it. We need the two option
Why are lots of end-of-line 's' character missing? :)
> # GENERIC_TRACER and TRACING to avoid circular dependencies to accomplish the
> # hiding of the automatic options.
>
> @@ -162,7 +162,7 @@ config IRQSOFF_TRACER
> This option measures the time spent in irqs-off critical
> sections, with microsecond accuracy.
>
> - The default measurement method is a maximum search, which is
> + The default measurement method is a maximum search, which i
> disabled by default and can be runtime (re-)started
> via:
>
> @@ -184,7 +184,7 @@ config PREEMPT_TRACER
> This option measures the time spent in preemption-off critical
> sections, with microsecond accuracy.
>
> - The default measurement method is a maximum search, which is
> + The default measurement method is a maximum search, which i
> disabled by default and can be runtime (re-)started
> via:
>
> @@ -228,7 +228,7 @@ choice
> prompt "Branch Profiling"
> default BRANCH_PROFILE_NONE
> help
> - The branch profiling is a software profiler. It will add hooks
> + The branch profiling is a software profiler. It will add hook
> into the C conditionals to test which path a branch takes.
>
> The likely/unlikely profiler only looks at the conditions that
> @@ -252,12 +252,12 @@ config PROFILE_ANNOTATED_BRANCHES
> bool "Trace likely/unlikely profiler"
> select TRACE_BRANCH_PROFILING
> help
> - This tracer profiles all the the likely and unlikely macros
> + This tracer profiles all the the likely and unlikely macro
> in the kernel. It will display the results in:
>
> /sys/kernel/debug/tracing/profile_annotated_branch
>
> - Note: this will add a significant overhead; only turn this
> + Note: this will add a significant overhead; only turn thi
> on if you need to profile the system's use of these macros.
>
> config PROFILE_ALL_BRANCHES
> @@ -333,7 +333,7 @@ config BLK_DEV_IO_TRACE
> select GENERIC_TRACER
> select STACKTRACE
> help
> - Say Y here if you want to be able to trace the block layer actions
> + Say Y here if you want to be able to trace the block layer action
> on a given queue. Tracing allows you to see any traffic happening
> on a block device queue. For more information (and the userspace
> support tools needed), fetch the blktrace tools from:
> @@ -351,9 +351,8 @@ config BLK_DEV_IO_TRACE
> config KPROBE_EVENT
> depends on KPROBES
> depends on HAVE_REGS_AND_STACK_ACCESS_API
> + depends on PROBE_EVENTS
> bool "Enable kprobes-based dynamic events"
> - select TRACING
> - select PROBE_EVENTS
> default y
> help
> This allows the user to add tracing events (similar to tracepoints)
> @@ -370,10 +369,9 @@ config UPROBE_EVENT
> bool "Enable uprobes-based dynamic events"
> depends on ARCH_SUPPORTS_UPROBES
> depends on MMU
> + depends on PROBE_EVENTS
> select UPROBES
> - select PROBE_EVENTS
> - select TRACING
> - default n
> + default y
> help
> This allows the user to add tracing events on top of userspace dynamic
> events (similar to tracepoints) on the fly via the traceevents interface.
> @@ -383,7 +381,18 @@ config UPROBE_EVENT
> tools on user space applications.
>
> config PROBE_EVENTS
> - def_bool n
> + bool "Enable kprobes and uprobe based dynamic events"
> + select TRACING
> + default n
Hmm, without this series, KPROBE_EVENT is set "y" by default.
(PROBE_EVENTS is introduced by 8/15)
I'd like to set this "y" by default, because it doesn't
affect other parts.
Thank you,
> + help
> + This allows a user to add dynamic tracing events in
> + kernel using kprobe-tracer and in userspace using
> + uprobe-tracer. However users can still selectively
> + disable one of these events.
> +
> + For more information on kprobe-tracer and uprobe-tracer
> + please refer help under KPROBE_EVENT and UPROBE_EVENT
> + respectively.
>
> config DYNAMIC_FTRACE
> bool "enable/disable ftrace tracepoints dynamically"
> @@ -393,14 +402,14 @@ config DYNAMIC_FTRACE
> help
> This option will modify all the calls to ftrace dynamically
> (will patch them out of the binary image and replace them
> - with a No-Op instruction) as they are called. A table is
> + with a No-Op instruction) as they are called. A table i
> created to dynamically enable them again.
>
> This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but
> otherwise has native performance as long as no tracing is active.
>
> The changes to the code are done by a kernel thread that
> - wakes up once a second and checks to see if any ftrace calls
> + wakes up once a second and checks to see if any ftrace call
> were made. If so, it runs stop_machine (stops all CPUS)
> and modifies the code to jump over the call to ftrace.
>
> @@ -432,7 +441,7 @@ config FTRACE_STARTUP_TEST
> select FTRACE_SELFTEST
> help
> This option performs a series of startup tests on ftrace. On bootup
> - a series of tests are made to verify that the tracer is
> + a series of tests are made to verify that the tracer i
> functioning properly. It will do tests on all the configured
> tracers of ftrace.
>
> @@ -441,12 +450,12 @@ config EVENT_TRACE_TEST_SYSCALLS
> depends on FTRACE_STARTUP_TEST
> help
> This option will also enable testing every syscall event.
> - It only enables the event and disables it and runs various loads
> + It only enables the event and disables it and runs various load
> with the event enabled. This adds a bit more time for kernel boot
> up since it runs this on every system call defined.
>
> TBD - enable a way to actually call the syscalls as we test their
> - events
> + event
>
> config MMIOTRACE
> bool "Memory mapped IO tracing"
> @@ -465,7 +474,7 @@ config MMIOTRACE_TEST
> tristate "Test module for mmiotrace"
> depends on MMIOTRACE && m
> help
> - This is a dumb module for testing mmiotrace. It is very dangerous
> + This is a dumb module for testing mmiotrace. It is very dangerou
> as it will write garbage to IO memory starting at a given address.
> However, it should be safe to use on e.g. unused portion of VRAM.
>
> @@ -477,9 +486,9 @@ config RING_BUFFER_BENCHMARK
> help
> This option creates a test to stress the ring buffer and benchmark it.
> It creates its own ring buffer such that it will not interfere with
> - any other users of the ring buffer (such as ftrace). It then creates
> + any other users of the ring buffer (such as ftrace). It then create
> a producer and consumer that will run for 10 seconds and sleep for
> - 10 seconds. Each interval it will print out the number of events
> + 10 seconds. Each interval it will print out the number of event
> it recorded and give a rough estimate of how long each iteration took.
>
> It does not disable interrupts or raise its priority, so it may be
>
> Why are lots of end-of-line 's' character missing? :)
>
Okay will correct them.
<snipped>
> >
> > config PROBE_EVENTS
> > - def_bool n
> > + bool "Enable kprobes and uprobe based dynamic events"
> > + select TRACING
> > + default n
>
> Hmm, without this series, KPROBE_EVENT is set "y" by default.
> (PROBE_EVENTS is introduced by 8/15)
> I'd like to set this "y" by default, because it doesn't
> affect other parts.
>
> Thank you,
>
This is based on what we discussed here
http://lkml.org/lkml/2010/8/2/86.
To recollect,
Frederic wanted that there should be one option to select both
UPROBE_EVENT and KPROBE_EVENT.
However if we make PROBE_EVENTS (which is the option to enable both
events) default "Y", then both UPROBE_EVENT and KPROBE_EVENT will be
selected.
Also if we look at http://lkml.org/lkml/2010/6/21/160, Steven
Rostedt didnt want UPROBE_EVENT to selected by default.
I agree that we should keep UPROBE_EVENT to be 'default n' till it gets
tested. Hence we have two choices. Either set the common knob to be
'default n' or dont have the common knob for now (i.e drop this
patch for now).
I think we should go with the first one, i.e have a common knob thats
by default unselected.
--
Thanks and Regards
Sriakr
(2010/08/27 18:31), Srikar Dronamraju wrote:
>>> config PROBE_EVENTS
>>> - def_bool n
>>> + bool "Enable kprobes and uprobe based dynamic events"
>>> + select TRACING
>>> + default n
>>
>> Hmm, without this series, KPROBE_EVENT is set "y" by default.
>> (PROBE_EVENTS is introduced by 8/15)
>> I'd like to set this "y" by default, because it doesn't
>> affect other parts.
>>
>> Thank you,
>>
>
> This is based on what we discussed here
> http://lkml.org/lkml/2010/8/2/86.
>
> To recollect,
> Frederic wanted that there should be one option to select both
> UPROBE_EVENT and KPROBE_EVENT.
>
> However if we make PROBE_EVENTS (which is the option to enable both
> events) default "Y", then both UPROBE_EVENT and KPROBE_EVENT will be
> selected.
>
> Also if we look at http://lkml.org/lkml/2010/6/21/160, Steven
> Rostedt didnt want UPROBE_EVENT to selected by default.
>
> I agree that we should keep UPROBE_EVENT to be 'default n' till it gets
> tested. Hence we have two choices. Either set the common knob to be
> 'default n' or dont have the common knob for now (i.e drop this
> patch for now).
>
> I think we should go with the first one, i.e have a common knob thats
> by default unselected.
Yeah, I'm OK to have a common knob, but I just don't like to set
KPROBE_EVENT unselected by default. I think there is no reason
to change default selecting (currently, KPROBE_EVENT=y by default.)
So, I think we should have below selecting list;
--- Tracers
...
[*] Enable dynamic events
[ ] Enable user-space dynamic events (EXPERIMENTAL)
...
What would you think about this ? :)
Thank you,
--
Masami HIRAMATSU
2nd Dept. Linux Technology Center
Hitachi, Ltd., Systems Development Laboratory
E-mail: [email protected]
> >
> > I think we should go with the first one, i.e have a common knob thats
> > by default unselected.
>
> Yeah, I'm OK to have a common knob, but I just don't like to set
> KPROBE_EVENT unselected by default. I think there is no reason
> to change default selecting (currently, KPROBE_EVENT=y by default.)
I understand your concern.
>
> So, I think we should have below selecting list;
> --- Tracers
> ...
> [*] Enable dynamic events
> [ ] Enable user-space dynamic events (EXPERIMENTAL)
> ...
>
> What would you think about this ? :)
>
> Thank you,
Wouldnt it negate the purpose of common knob?
Because people would still have go and select UPROBE_EVENTS,
I think when Frederic asked for a common knob, he was looking at
enabling both or disabling both and an option to selectively
select one of the tracers.
--
Thanks and Regards
Srikar
Selecting CONFIG_PROBE_EVENTS enables both kprobe-based and
uprobes-based dynamic events. However kprobe-tracer or uprobe-tracer
can still be individually selected or disabled.
Signed-off-by: Srikar Dronamraju <[email protected]>
Suggested-by: Frederic Weisbecker <[email protected]>
---
Changelog from V10: Fixed few erroneous changes: missing s at eol.
reported by Masami Hiramatsu.
kernel/trace/Kconfig | 21 +++++++++++++++------
1 files changed, 15 insertions(+), 6 deletions(-)
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 55ba474..77e04b0 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -351,9 +351,8 @@ config BLK_DEV_IO_TRACE
config KPROBE_EVENT
depends on KPROBES
depends on HAVE_REGS_AND_STACK_ACCESS_API
+ depends on PROBE_EVENTS
bool "Enable kprobes-based dynamic events"
- select TRACING
- select PROBE_EVENTS
default y
help
This allows the user to add tracing events (similar to tracepoints)
@@ -370,10 +369,9 @@ config UPROBE_EVENT
bool "Enable uprobes-based dynamic events"
depends on ARCH_SUPPORTS_UPROBES
depends on MMU
+ depends on PROBE_EVENTS
select UPROBES
- select PROBE_EVENTS
- select TRACING
- default n
+ default y
help
This allows the user to add tracing events on top of userspace dynamic
events (similar to tracepoints) on the fly via the traceevents interface.
@@ -383,7 +381,18 @@ config UPROBE_EVENT
tools on user space applications.
config PROBE_EVENTS
- def_bool n
+ bool "Enable kprobes and uprobe based dynamic events"
+ select TRACING
+ default n
+ help
+ This allows a user to add dynamic tracing events in
+ kernel using kprobe-tracer and in userspace using
+ uprobe-tracer. However users can still selectively
+ disable one of these events.
+
+ For more information on kprobe-tracer and uprobe-tracer
+ please refer help under KPROBE_EVENT and UPROBE_EVENT
+ respectively.
config DYNAMIC_FTRACE
bool "enable/disable ftrace tracepoints dynamically"
Introduces -S/--show_functions option for perf-probe.
This lists function names in a File. If no file is specified, then lists
functions in the current running kernel.
Signed-off-by: Srikar Dronamraju <[email protected]>
---
Changelog from V11: accomodate name change dso_fprintf_symbols_by_name.
Changelog from V10: As suggested by Arnaldo, filtering is now
based on sym.binding.
Changelog from V9: Filter labels, weak, and local binding functions
from listing as suggested by Christoph Hellwig.
Show last 10 functions in /bin/zsh.
# perf probe -S -D /bin/zsh | tail
zstrtol
ztrcmp
ztrdup
ztrduppfx
ztrftime
ztrlen
ztrncpy
ztrsub
zwarn
zwarnnam
Show first 10 functions in /lib/libc.so.6
# perf probe -S -D /lib/libc.so.6 | head
_IO_adjust_column
_IO_adjust_wcolumn
_IO_default_doallocate
_IO_default_finish
_IO_default_pbackfail
_IO_default_uflow
_IO_default_xsgetn
_IO_default_xsputn
_IO_do_write@@GLIBC_2.2.5
_IO_doallocbuf
Show last 10 functions in kernel.
# perf probe -S | tail
zlib_inflateInit2
zlib_inflateReset
zlib_inflate_blob
zlib_inflate_table
zlib_inflate_workspacesize
zone_pcp_update
zone_reclaim
zone_reclaimable_pages
zone_statistics
zone_watermark_ok
---
tools/perf/builtin-probe.c | 43 ++++++++++++++++++++++++
tools/perf/util/probe-event.c | 72 +++++++++++++++++++++++++++++++++++++++++
tools/perf/util/probe-event.h | 1 +
tools/perf/util/symbol.c | 8 +++++
tools/perf/util/symbol.h | 1 +
5 files changed, 124 insertions(+), 1 deletions(-)
diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
index 199d5e1..fa63245 100644
--- a/tools/perf/builtin-probe.c
+++ b/tools/perf/builtin-probe.c
@@ -50,9 +50,11 @@ static struct {
bool list_events;
bool force_add;
bool show_lines;
+ bool list_functions;
int nevents;
struct perf_probe_event events[MAX_PROBES];
struct strlist *dellist;
+ struct strlist *limitlist;
struct line_range line_range;
int max_probe_points;
} params;
@@ -132,6 +134,19 @@ static int opt_show_lines(const struct option *opt __used,
}
#endif
+static int opt_limit_dsos(const struct option *opt __used,
+ const char *str, int unset __used)
+{
+ if (str) {
+ if (!params.limitlist)
+ params.limitlist = strlist__new(true, NULL);
+ if (!params.limitlist)
+ return -1;
+ strlist__add(params.limitlist, str);
+ }
+ return 0;
+}
+
static const char * const probe_usage[] = {
"perf probe [<options>] 'PROBEDEF' ['PROBEDEF' ...]",
"perf probe [<options>] --add 'PROBEDEF' [--add 'PROBEDEF' ...]",
@@ -188,6 +203,10 @@ static const struct option options[] = {
OPT__DRY_RUN(&probe_event_dry_run),
OPT_INTEGER('\0', "max-probes", ¶ms.max_probe_points,
"Set how many probe points can be found for a probe."),
+ OPT_BOOLEAN('S', "show_functions", ¶ms.list_functions,
+ "Show potential probes."),
+ OPT_CALLBACK('D', "limit_dsos", NULL, "DSO",
+ "Limit Dsos.", opt_limit_dsos),
OPT_END()
};
@@ -213,7 +232,7 @@ int cmd_probe(int argc, const char **argv, const char *prefix __used)
params.max_probe_points = MAX_PROBES;
if ((!params.nevents && !params.dellist && !params.list_events &&
- !params.show_lines))
+ !params.show_lines && !params.list_functions))
usage_with_options(probe_usage, options);
if (params.list_events) {
@@ -225,12 +244,34 @@ int cmd_probe(int argc, const char **argv, const char *prefix __used)
pr_err(" Error: Don't use --list with --line.\n");
usage_with_options(probe_usage, options);
}
+ if (params.list_functions) {
+ pr_warning(" Error: Don't use --list with"
+ " --show_functions.\n");
+ usage_with_options(probe_usage, options);
+ }
ret = show_perf_probe_events();
if (ret < 0)
pr_err(" Error: Failed to show event list. (%d)\n",
ret);
return ret;
}
+ if (params.list_functions) {
+ if (params.nevents != 0 || params.dellist) {
+ pr_err(" Error: Don't use --show_functions with"
+ " --add/--del.\n");
+ usage_with_options(probe_usage, options);
+ }
+ if (params.show_lines) {
+ pr_err(" Error: Don't use --show_functions with"
+ " --line.\n");
+ usage_with_options(probe_usage, options);
+ }
+ ret = show_possible_probes(params.limitlist);
+ if (ret < 0)
+ pr_err(" Error: Failed to show possible"
+ " probes (%d).\n", ret);
+ return ret;
+ }
#ifdef DWARF_SUPPORT
if (params.show_lines) {
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index e72f05c..be90836 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -31,6 +31,7 @@
#include <string.h>
#include <stdarg.h>
#include <limits.h>
+#include <gelf.h>
#undef _GNU_SOURCE
#include "util.h"
@@ -46,6 +47,7 @@
#include "trace-event.h" /* For __unused */
#include "probe-event.h"
#include "probe-finder.h"
+#include "session.h"
#define MAX_CMDLEN 256
#define MAX_PROBE_ARGS 128
@@ -1752,3 +1754,73 @@ int del_perf_probe_events(struct strlist *dellist)
return ret;
}
+/*
+ * If a symbol corresponds to a function with global binding return 0.
+ * For all others return 1.
+ */
+static int filter_non_global_functions(struct map *map __unused,
+ struct symbol *sym)
+{
+ if (sym->binding != STB_GLOBAL)
+ return 1;
+
+ return 0;
+}
+
+static int print_list_available_symbols(struct map *map,
+ const char *name __unused)
+{
+ if (map__load(map, filter_non_global_functions) < 0)
+ return -EINVAL;
+ if (!dso__sorted_by_name(map->dso, map->type))
+ dso__sort_by_name(map->dso, map->type);
+
+ dso__fprintf_symbols_by_name(map->dso, map->type, stdout);
+ return 0;
+}
+
+int show_possible_probes(struct strlist *limitlist)
+{
+ struct str_node *ent;
+ struct map *map = NULL;
+ char *str;
+ int ret = -EINVAL;
+
+ if (!limitlist) { /* Show functions in kernel */
+ ret = init_vmlinux();
+ if (ret < 0)
+ return ret;
+ return print_list_available_symbols(
+ machine.vmlinux_maps[MAP__FUNCTION], NULL);
+ }
+
+ symbol_conf.try_vmlinux_path = false;
+ symbol_conf.sort_by_name = true;
+ ret = symbol__init();
+ if (ret < 0) {
+ pr_debug("Failed to init symbol map.\n");
+ return ret;
+ }
+
+ strlist__for_each(ent, limitlist) {
+ str = strdup(ent->s);
+ if (!str) {
+ ret = -ENOMEM;
+ goto out_delete;
+ }
+
+ map = dso__new_map(str);
+ ret = print_list_available_symbols(map, NULL);
+ if (ret)
+ pr_warning("No Symbols in dso %s.\n", str);
+
+ dso__delete(map->dso);
+ map__delete(map);
+ free(str);
+ }
+
+out_delete:
+ if (ret)
+ pr_warning("Failed to list available probes.\n");
+ return ret;
+}
diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
index 5af3924..fcd0f08 100644
--- a/tools/perf/util/probe-event.h
+++ b/tools/perf/util/probe-event.h
@@ -115,6 +115,7 @@ extern int add_perf_probe_events(struct perf_probe_event *pevs, int npevs,
extern int del_perf_probe_events(struct strlist *dellist);
extern int show_perf_probe_events(void);
extern int show_line_range(struct line_range *lr);
+extern int show_possible_probes(struct strlist *availlist);
/* Maximum index number of event-name postfix */
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index a08e1cb..1728d71 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -2464,3 +2464,11 @@ int machine__load_vmlinux_path(struct machine *self, enum map_type type,
return ret;
}
+
+struct map *dso__new_map(char *name)
+{
+ struct dso *dso = dso__new(name);
+ struct map *map = map__new2(0, dso, MAP__FUNCTION);
+
+ return map;
+}
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index 0a2c460..145953d 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -202,6 +202,7 @@ char dso__symtab_origin(const struct dso *self);
void dso__set_long_name(struct dso *self, char *name);
void dso__set_build_id(struct dso *self, void *build_id);
void dso__read_running_kernel_build_id(struct dso *self, struct machine *machine);
+struct map *dso__new_map(char *name);
struct symbol *dso__find_symbol(struct dso *self, enum map_type type, u64 addr);
struct symbol *dso__find_symbol_by_name(struct dso *self, enum map_type type,
const char *name);
(2010/08/27 21:17), Srikar Dronamraju wrote:
>>>
>>> I think we should go with the first one, i.e have a common knob thats
>>> by default unselected.
>>
>> Yeah, I'm OK to have a common knob, but I just don't like to set
>> KPROBE_EVENT unselected by default. I think there is no reason
>> to change default selecting (currently, KPROBE_EVENT=y by default.)
>
> I understand your concern.
>
>>
>> So, I think we should have below selecting list;
>> --- Tracers
>> ...
>> [*] Enable dynamic events
>> [ ] Enable user-space dynamic events (EXPERIMENTAL)
>> ...
>>
>> What would you think about this ? :)
>>
>> Thank you,
>
>
> Wouldnt it negate the purpose of common knob?
> Because people would still have go and select UPROBE_EVENTS,
Hmm, I think this just seems an enhancement of dynamic events,
and also you can enable it by default on some point.
I mean, eventually, there will be only "Enable dynamic events"
on the screen.
> I think when Frederic asked for a common knob, he was looking at
> enabling both or disabling both and an option to selectively
> select one of the tracers.
Yeah, but I'd like to ask Frederic that he expected disabling
KPROBE_EVENT by default too, even though it changes current
default config.
Thank you,
Commit-ID: 90f18e63fbd005133624bf18a5e8b75c92e90f4d
Gitweb: http://git.kernel.org/tip/90f18e63fbd005133624bf18a5e8b75c92e90f4d
Author: Srikar Dronamraju <[email protected]>
AuthorDate: Wed, 25 Aug 2010 19:13:29 +0530
Committer: Arnaldo Carvalho de Melo <[email protected]>
CommitDate: Wed, 25 Aug 2010 17:28:59 -0300
perf symbols: List symbols in a dso in ascending name order
Given a dso, list the symbols in ascending name order. Needed for
listing available symbols from perf probe.
Cc: Ananth N Mavinakayanahalli <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: "Frank Ch. Eigler" <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Jim Keniston <[email protected]>
Cc: Mark Wielaard <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: Naren A Devaiah <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: "Paul E. McKenney" <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Srikar Dronamraju <[email protected]>
Cc: Steven Rostedt <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Srikar Dronamraju <[email protected]>
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
---
tools/perf/util/symbol.c | 14 ++++++++++++++
tools/perf/util/symbol.h | 1 +
2 files changed, 15 insertions(+), 0 deletions(-)
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 1a36773..a08e1cb 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -388,6 +388,20 @@ size_t dso__fprintf_buildid(struct dso *self, FILE *fp)
return fprintf(fp, "%s", sbuild_id);
}
+size_t dso__fprintf_symbols_by_name(struct dso *self, enum map_type type, FILE *fp)
+{
+ size_t ret = 0;
+ struct rb_node *nd;
+ struct symbol_name_rb_node *pos;
+
+ for (nd = rb_first(&self->symbol_names[type]); nd; nd = rb_next(nd)) {
+ pos = rb_entry(nd, struct symbol_name_rb_node, rb_node);
+ fprintf(fp, "%s\n", pos->sym.name);
+ }
+
+ return ret;
+}
+
size_t dso__fprintf(struct dso *self, enum map_type type, FILE *fp)
{
struct rb_node *nd;
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index b7a8da4..0a2c460 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -181,6 +181,7 @@ size_t machines__fprintf_dsos(struct rb_root *self, FILE *fp);
size_t machines__fprintf_dsos_buildid(struct rb_root *self, FILE *fp, bool with_hits);
size_t dso__fprintf_buildid(struct dso *self, FILE *fp);
+size_t dso__fprintf_symbols_by_name(struct dso *self, enum map_type type, FILE *fp);
size_t dso__fprintf(struct dso *self, enum map_type type, FILE *fp);
enum dso_origin {
On Fri, Oct 29, 2010 at 04:18:58PM +0530, Srikar Dronamraju wrote:
> Current issues: Given a vma; finding all tasks that have this vma
> mapped. The current solution seems to walk thro all tasks in the system
> and check if each task's mm field. But this could be inefficient
> especially if the vma is part of all processes like libc etc.
It's pretty much guaranteed to be inefficient, yes.
> I dont think we can use mm->owner to walk thro all the tasks that map to
> this mm_struct.
I don't see a way around that if we have to find the task by the vma.
You'll have to start with vma->vm_mm->owner and then walk the list
of thread siblings inside the heavy weight process.
> Slot allocation delays: Using a per-thread slot instead of a per-probe
> slot leads to a 3.5X degradation in performance. If we need to use
> per-probe slots, we would have to have maintain metadata, i.e the slot
> to virtual address mapping per process. However Peter prefers that we
> reduce such metadata.
The performance numbers are pretty drastic. But I'll let Peter comment
on the desire in more detail. I'm really not in enough touch with this
code anymore to give too useful comments.
> >From a perf/ftrace perspective:
I really prefer the new interface. But as said before I'm just a user
here and I don't care how it's implemented underneath. I'll defer to
Peter and others knowing the code in more detail to make the trade offs
between the different low level implementations.