v1:
-- Split the RFC patch #2 into two patches
-- Use larch_insn_gen_break() to generate break insns
for kprobes and uprobes
-- Pass around instruction word instead of union for
insns_not_supported(), insns_need_simulation() and
arch_simulate_insn() to avoid type conversion for callers
-- Add a simple test case for uprobes in the commit message
Tiezhu Yang (4):
LoongArch: Move three functions from kprobes.c to inst.h
LoongArch: Add larch_insn_gen_break() to generate break insns
LoongArch: Use larch_insn_gen_break() for kprobes
LoongArch: Add uprobes support
arch/loongarch/Kconfig | 3 +
arch/loongarch/include/asm/inst.h | 63 ++++++++++++++++
arch/loongarch/include/asm/kprobes.h | 2 +-
arch/loongarch/include/asm/uprobes.h | 36 ++++++++++
arch/loongarch/kernel/Makefile | 1 +
arch/loongarch/kernel/inst.c | 9 +++
arch/loongarch/kernel/kprobes.c | 67 ++---------------
arch/loongarch/kernel/traps.c | 9 ++-
arch/loongarch/kernel/uprobes.c | 135 +++++++++++++++++++++++++++++++++++
9 files changed, 259 insertions(+), 66 deletions(-)
create mode 100644 arch/loongarch/include/asm/uprobes.h
create mode 100644 arch/loongarch/kernel/uprobes.c
--
2.1.0
The following three functions will be used for uprobes, move them
from kprobes.c to inst.h:
insns_not_supported()
insns_need_simulation()
arch_simulate_insn()
This is preparation for later patch, no functionality change.
Signed-off-by: Tiezhu Yang <[email protected]>
---
arch/loongarch/include/asm/inst.h | 39 +++++++++++++++++++++++++++++++++
arch/loongarch/kernel/kprobes.c | 46 ++-------------------------------------
2 files changed, 41 insertions(+), 44 deletions(-)
diff --git a/arch/loongarch/include/asm/inst.h b/arch/loongarch/include/asm/inst.h
index a04fe75..af494b5 100644
--- a/arch/loongarch/include/asm/inst.h
+++ b/arch/loongarch/include/asm/inst.h
@@ -409,6 +409,45 @@ static inline bool is_self_loop_ins(union loongarch_instruction *ip, struct pt_r
void simu_pc(struct pt_regs *regs, union loongarch_instruction insn);
void simu_branch(struct pt_regs *regs, union loongarch_instruction insn);
+static inline bool insns_not_supported(union loongarch_instruction insn)
+{
+ switch (insn.reg2i14_format.opcode) {
+ case llw_op:
+ case lld_op:
+ case scw_op:
+ case scd_op:
+ pr_notice("kprobe: ll and sc instructions are not supported\n");
+ return true;
+ }
+
+ switch (insn.reg1i21_format.opcode) {
+ case bceqz_op:
+ pr_notice("kprobe: bceqz and bcnez instructions are not supported\n");
+ return true;
+ }
+
+ return false;
+}
+
+static inline bool insns_need_simulation(union loongarch_instruction insn)
+{
+ if (is_pc_ins(&insn))
+ return true;
+
+ if (is_branch_ins(&insn))
+ return true;
+
+ return false;
+}
+
+static inline void arch_simulate_insn(union loongarch_instruction insn, struct pt_regs *regs)
+{
+ if (is_pc_ins(&insn))
+ simu_pc(regs, insn);
+ else if (is_branch_ins(&insn))
+ simu_branch(regs, insn);
+}
+
int larch_insn_read(void *addr, u32 *insnp);
int larch_insn_write(void *addr, u32 insn);
int larch_insn_patch_text(void *addr, u32 insn);
diff --git a/arch/loongarch/kernel/kprobes.c b/arch/loongarch/kernel/kprobes.c
index 56c8c4b..08c78d2 100644
--- a/arch/loongarch/kernel/kprobes.c
+++ b/arch/loongarch/kernel/kprobes.c
@@ -21,48 +21,6 @@ static const union loongarch_instruction singlestep_insn = {
DEFINE_PER_CPU(struct kprobe *, current_kprobe);
DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
-static bool insns_not_supported(union loongarch_instruction insn)
-{
- switch (insn.reg2i14_format.opcode) {
- case llw_op:
- case lld_op:
- case scw_op:
- case scd_op:
- pr_notice("kprobe: ll and sc instructions are not supported\n");
- return true;
- }
-
- switch (insn.reg1i21_format.opcode) {
- case bceqz_op:
- pr_notice("kprobe: bceqz and bcnez instructions are not supported\n");
- return true;
- }
-
- return false;
-}
-NOKPROBE_SYMBOL(insns_not_supported);
-
-static bool insns_need_simulation(struct kprobe *p)
-{
- if (is_pc_ins(&p->opcode))
- return true;
-
- if (is_branch_ins(&p->opcode))
- return true;
-
- return false;
-}
-NOKPROBE_SYMBOL(insns_need_simulation);
-
-static void arch_simulate_insn(struct kprobe *p, struct pt_regs *regs)
-{
- if (is_pc_ins(&p->opcode))
- simu_pc(regs, p->opcode);
- else if (is_branch_ins(&p->opcode))
- simu_branch(regs, p->opcode);
-}
-NOKPROBE_SYMBOL(arch_simulate_insn);
-
static void arch_prepare_ss_slot(struct kprobe *p)
{
p->ainsn.insn[0] = *p->addr;
@@ -89,7 +47,7 @@ int arch_prepare_kprobe(struct kprobe *p)
if (insns_not_supported(p->opcode))
return -EINVAL;
- if (insns_need_simulation(p)) {
+ if (insns_need_simulation(p->opcode)) {
p->ainsn.insn = NULL;
} else {
p->ainsn.insn = get_insn_slot();
@@ -220,7 +178,7 @@ static void setup_singlestep(struct kprobe *p, struct pt_regs *regs,
regs->csr_era = (unsigned long)p->ainsn.insn;
} else {
/* simulate single steping */
- arch_simulate_insn(p, regs);
+ arch_simulate_insn(p->opcode, regs);
/* now go for post processing */
post_kprobe_handler(p, kcb, regs);
}
--
2.1.0
Uprobes is the user-space counterpart to kprobes, this commit
adds uprobes support for LoongArch.
Here is a simple example with CONFIG_UPROBE_EVENTS=y:
# cat test.c
#include <stdio.h>
int add(int a, int b)
{
return a + b;
}
int main()
{
return add(2, 7);
}
# gcc test.c -o /tmp/test
# nm /tmp/test | grep add
0000000120004194 T add
# cd /sys/kernel/debug/tracing
# echo > uprobe_events
# echo "p:myuprobe /tmp/test:0x4194 %r4 %r5" > uprobe_events
# echo "r:myuretprobe /tmp/test:0x4194 %r4" >> uprobe_events
# echo 1 > events/uprobes/enable
# echo 1 > tracing_on
# /tmp/test
# cat trace
...
# TASK-PID CPU# ||||| TIMESTAMP FUNCTION
# | | | ||||| | |
test-1060 [001] DNZff 1015.770620: myuprobe: (0x120004194) arg1=0x2 arg2=0x7
test-1060 [001] DNZff 1015.770930: myuretprobe: (0x1200041f0 <- 0x120004194) arg1=0x9
Signed-off-by: Tiezhu Yang <[email protected]>
---
arch/loongarch/Kconfig | 3 +
arch/loongarch/include/asm/uprobes.h | 36 ++++++++++
arch/loongarch/kernel/Makefile | 1 +
arch/loongarch/kernel/traps.c | 9 ++-
arch/loongarch/kernel/uprobes.c | 135 +++++++++++++++++++++++++++++++++++
5 files changed, 179 insertions(+), 5 deletions(-)
create mode 100644 arch/loongarch/include/asm/uprobes.h
create mode 100644 arch/loongarch/kernel/uprobes.c
diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 7fd5125..ab66ad2 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -574,6 +574,9 @@ config ARCH_MMAP_RND_BITS_MIN
config ARCH_MMAP_RND_BITS_MAX
default 18
+config ARCH_SUPPORTS_UPROBES
+ def_bool y
+
menu "Power management options"
config ARCH_SUSPEND_POSSIBLE
diff --git a/arch/loongarch/include/asm/uprobes.h b/arch/loongarch/include/asm/uprobes.h
new file mode 100644
index 0000000..c6ffcb7
--- /dev/null
+++ b/arch/loongarch/include/asm/uprobes.h
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef __ASM_LOONGARCH_UPROBES_H
+#define __ASM_LOONGARCH_UPROBES_H
+
+#include <asm/inst.h>
+
+typedef u32 uprobe_opcode_t;
+
+#define MAX_UINSN_BYTES LOONGARCH_INSN_SIZE
+#define UPROBE_XOL_SLOT_BYTES MAX_UINSN_BYTES
+
+#define UPROBE_XOLBP_INSN larch_insn_gen_break(BRK_UPROBE_XOLBP)
+#define UPROBE_SWBP_INSN larch_insn_gen_break(BRK_UPROBE_BP)
+#define UPROBE_SWBP_INSN_SIZE LOONGARCH_INSN_SIZE
+
+struct arch_uprobe {
+ union {
+ u32 insn[MAX_UINSN_BYTES];
+ u32 ixol[MAX_UINSN_BYTES];
+ };
+ bool simulate;
+};
+
+struct arch_uprobe_task {
+ unsigned long saved_trap_nr;
+};
+
+#ifdef CONFIG_UPROBES
+bool uprobe_breakpoint_handler(struct pt_regs *regs);
+bool uprobe_singlestep_handler(struct pt_regs *regs);
+#else /* !CONFIG_UPROBES */
+static inline bool uprobe_breakpoint_handler(struct pt_regs *regs) { return false; }
+static inline bool uprobe_singlestep_handler(struct pt_regs *regs) { return false; }
+#endif /* CONFIG_UPROBES */
+
+#endif /* __ASM_LOONGARCH_UPROBES_H */
diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
index 78d4e33..67b9c26 100644
--- a/arch/loongarch/kernel/Makefile
+++ b/arch/loongarch/kernel/Makefile
@@ -53,5 +53,6 @@ obj-$(CONFIG_PERF_EVENTS) += perf_event.o perf_regs.o
obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
obj-$(CONFIG_KPROBES) += kprobes.o kprobes_trampoline.o
+obj-$(CONFIG_UPROBES) += uprobes.o
CPPFLAGS_vmlinux.lds := $(KBUILD_CFLAGS)
diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c
index de8ebe2..cfc2e0c 100644
--- a/arch/loongarch/kernel/traps.c
+++ b/arch/loongarch/kernel/traps.c
@@ -45,6 +45,7 @@
#include <asm/tlb.h>
#include <asm/types.h>
#include <asm/unwind.h>
+#include <asm/uprobes.h>
#include "access-helper.h"
@@ -440,7 +441,6 @@ asmlinkage void noinstr do_bp(struct pt_regs *regs)
if (regs->csr_prmd & CSR_PRMD_PIE)
local_irq_enable();
- current->thread.trap_nr = read_csr_excode();
if (__get_inst(&opcode, (u32 *)era, user))
goto out_sigsegv;
@@ -462,18 +462,17 @@ asmlinkage void noinstr do_bp(struct pt_regs *regs)
else
break;
case BRK_UPROBE_BP:
- if (notify_die(DIE_UPROBE, "Uprobe", regs, bcode,
- current->thread.trap_nr, SIGTRAP) == NOTIFY_STOP)
+ if (uprobe_breakpoint_handler(regs))
goto out;
else
break;
case BRK_UPROBE_XOLBP:
- if (notify_die(DIE_UPROBE_XOL, "Uprobe_XOL", regs, bcode,
- current->thread.trap_nr, SIGTRAP) == NOTIFY_STOP)
+ if (uprobe_singlestep_handler(regs))
goto out;
else
break;
default:
+ current->thread.trap_nr = read_csr_excode();
if (notify_die(DIE_TRAP, "Break", regs, bcode,
current->thread.trap_nr, SIGTRAP) == NOTIFY_STOP)
goto out;
diff --git a/arch/loongarch/kernel/uprobes.c b/arch/loongarch/kernel/uprobes.c
new file mode 100644
index 0000000..1b0e2de
--- /dev/null
+++ b/arch/loongarch/kernel/uprobes.c
@@ -0,0 +1,135 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/highmem.h>
+#include <linux/ptrace.h>
+#include <linux/uprobes.h>
+#include <linux/sched.h>
+#include <asm/cacheflush.h>
+
+#define UPROBE_TRAP_NR UINT_MAX
+
+int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe,
+ struct mm_struct *mm, unsigned long addr)
+{
+ if (addr & 0x3)
+ return -EILSEQ;
+
+ if (insns_not_supported(auprobe->insn[0]))
+ return -EINVAL;
+
+ if (insns_need_simulation(auprobe->insn[0])) {
+ auprobe->ixol[0] = larch_insn_gen_nop();
+ auprobe->simulate = true;
+ } else {
+ auprobe->ixol[0] = auprobe->insn[0];
+ auprobe->simulate = false;
+ }
+
+ auprobe->ixol[1] = UPROBE_XOLBP_INSN;
+
+ return 0;
+}
+
+int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ struct uprobe_task *utask = current->utask;
+
+ utask->autask.saved_trap_nr = current->thread.trap_nr;
+ current->thread.trap_nr = UPROBE_TRAP_NR;
+ instruction_pointer_set(regs, utask->xol_vaddr);
+
+ return 0;
+}
+
+int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ struct uprobe_task *utask = current->utask;
+
+ WARN_ON_ONCE(current->thread.trap_nr != UPROBE_TRAP_NR);
+ current->thread.trap_nr = utask->autask.saved_trap_nr;
+ instruction_pointer_set(regs, utask->vaddr + 4);
+
+ return 0;
+}
+
+void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ struct uprobe_task *utask = current->utask;
+
+ current->thread.trap_nr = utask->autask.saved_trap_nr;
+ instruction_pointer_set(regs, utask->vaddr);
+}
+
+bool arch_uprobe_xol_was_trapped(struct task_struct *t)
+{
+ if (t->thread.trap_nr != UPROBE_TRAP_NR)
+ return true;
+
+ return false;
+}
+
+bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ if (!auprobe->simulate)
+ return false;
+
+ arch_simulate_insn(auprobe->insn[0], regs);
+
+ return true;
+}
+
+unsigned long arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr,
+ struct pt_regs *regs)
+{
+ unsigned long ra = regs->regs[1];
+
+ regs->regs[1] = trampoline_vaddr;
+
+ return ra;
+}
+
+bool arch_uretprobe_is_alive(struct return_instance *ret,
+ enum rp_check ctx, struct pt_regs *regs)
+{
+ if (ctx == RP_CHECK_CHAIN_CALL)
+ return regs->regs[3] <= ret->stack;
+ else
+ return regs->regs[3] < ret->stack;
+}
+
+int arch_uprobe_exception_notify(struct notifier_block *self,
+ unsigned long val, void *data)
+{
+ return NOTIFY_DONE;
+}
+
+bool uprobe_breakpoint_handler(struct pt_regs *regs)
+{
+ if (uprobe_pre_sstep_notifier(regs))
+ return true;
+
+ return false;
+}
+
+bool uprobe_singlestep_handler(struct pt_regs *regs)
+{
+ if (uprobe_post_sstep_notifier(regs))
+ return true;
+
+ return false;
+}
+
+unsigned long uprobe_get_swbp_addr(struct pt_regs *regs)
+{
+ return instruction_pointer(regs);
+}
+
+void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
+ void *src, unsigned long len)
+{
+ void *kaddr = kmap_local_page(page);
+ void *dst = kaddr + (vaddr & ~PAGE_MASK);
+
+ memcpy(dst, src, len);
+ flush_icache_range((unsigned long)dst, (unsigned long)dst + len);
+ kunmap_local(kaddr);
+}
--
2.1.0
On Wed, 2023-04-12 at 18:04 +0800, Tiezhu Yang wrote:
> +static inline bool insns_not_supported(union loongarch_instruction insn)
This function seems long enough (to me) not to use "static inline".
Note that most part of this function belongs to a cold path, and IMO
it's bad to inline a cold path into every caller.
> +{
> + switch (insn.reg2i14_format.opcode) {
> + case llw_op:
> + case lld_op:
> + case scw_op:
> + case scd_op:
> + pr_notice("kprobe: ll and sc instructions are not supported\n");
> + return true;
> + }
> +
> + switch (insn.reg1i21_format.opcode) {
> + case bceqz_op:
> + pr_notice("kprobe: bceqz and bcnez instructions are not supported\n");
> + return true;
> + }
> +
> + return false;
> +}
> +
> +static inline bool insns_need_simulation(union loongarch_instruction insn)
> +{
> + if (is_pc_ins(&insn))
> + return true;
> +
> + if (is_branch_ins(&insn))
> + return true;
> +
> + return false;
I'd write "return is_pc_ins(&insn) || is_branch_ins(&insn);" here, but
there is no behavioral difference anyway.
> +}
--
Xi Ruoyao <[email protected]>
School of Aerospace Science and Technology, Xidian University
On 04/12/2023 06:39 PM, Xi Ruoyao wrote:
> On Wed, 2023-04-12 at 18:04 +0800, Tiezhu Yang wrote:
>> +static inline bool insns_not_supported(union loongarch_instruction insn)
>
> This function seems long enough (to me) not to use "static inline".
> Note that most part of this function belongs to a cold path, and IMO
> it's bad to inline a cold path into every caller.
OK, I will move the three functions from kprobes.c to inst.c.
>
>> +{
>> + switch (insn.reg2i14_format.opcode) {
>> + case llw_op:
>> + case lld_op:
>> + case scw_op:
>> + case scd_op:
>> + pr_notice("kprobe: ll and sc instructions are not supported\n");
>> + return true;
>> + }
>> +
>> + switch (insn.reg1i21_format.opcode) {
>> + case bceqz_op:
>> + pr_notice("kprobe: bceqz and bcnez instructions are not supported\n");
>> + return true;
>> + }
>> +
>> + return false;
>> +}
>> +
>> +static inline bool insns_need_simulation(union loongarch_instruction insn)
>> +{
>> + if (is_pc_ins(&insn))
>> + return true;
>> +
>> + if (is_branch_ins(&insn))
>> + return true;
>> +
>> + return false;
>
> I'd write "return is_pc_ins(&insn) || is_branch_ins(&insn);" here, but
> there is no behavioral difference anyway.
I prefer leave it as it is.
Thanks,
Tiezhu