Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754106Ab1FGNFf (ORCPT ); Tue, 7 Jun 2011 09:05:35 -0400 Received: from e23smtp09.au.ibm.com ([202.81.31.142]:37492 "EHLO e23smtp09.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753200Ab1FGNFb (ORCPT ); Tue, 7 Jun 2011 09:05:31 -0400 From: Srikar Dronamraju To: Peter Zijlstra , Ingo Molnar Cc: Steven Rostedt , Srikar Dronamraju , Linux-mm , Arnaldo Carvalho de Melo , Linus Torvalds , Masami Hiramatsu , Hugh Dickins , Christoph Hellwig , Andi Kleen , Thomas Gleixner , Jonathan Corbet , Oleg Nesterov , Andrew Morton , Jim Keniston , Roland McGrath , Ananth N Mavinakayanahalli , LKML Date: Tue, 07 Jun 2011 18:28:35 +0530 Message-Id: <20110607125835.28590.25476.sendpatchset@localhost6.localdomain6> In-Reply-To: <20110607125804.28590.92092.sendpatchset@localhost6.localdomain6> References: <20110607125804.28590.92092.sendpatchset@localhost6.localdomain6> Subject: [PATCH v4 3.0-rc2-tip 2/22] 2: uprobes: Breakground page replacement. Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 14133 Lines: 463 Provides Background page replacement by - cow the page that needs replacement. - modify a copy of the cowed page. - replace the cow page with the modified page - flush the page tables. Also provides additional routines to read an opcode from a given virtual address and for verifying if a instruction is a breakpoint instruction. Signed-off-by: Srikar Dronamraju Signed-off-by: Jim Keniston --- arch/Kconfig | 12 ++ include/linux/uprobes.h | 81 ++++++++++++ kernel/Makefile | 1 kernel/uprobes.c | 309 +++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 403 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 26b0e23..3d91687 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -61,6 +61,18 @@ config OPTPROBES depends on KPROBES && HAVE_OPTPROBES depends on !PREEMPT +config UPROBES + bool "User-space probes (EXPERIMENTAL)" + depends on ARCH_SUPPORTS_UPROBES + depends on MMU + select MM_OWNER + help + Uprobes enables kernel subsystems to establish probepoints + in user applications and execute handler functions when + the probepoints are hit. + + If in doubt, say "N". + config HAVE_EFFICIENT_UNALIGNED_ACCESS bool help diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h new file mode 100644 index 0000000..232ccea --- /dev/null +++ b/include/linux/uprobes.h @@ -0,0 +1,81 @@ +#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, 2008-2011 + * Authors: + * Srikar Dronamraju + * Jim Keniston + */ + +#ifdef CONFIG_ARCH_SUPPORTS_UPROBES +#include +#else +/* + * ARCH_SUPPORTS_UPROBES is not defined. + */ +typedef u8 uprobe_opcode_t; +#endif /* CONFIG_ARCH_SUPPORTS_UPROBES */ + +/* 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 + +/* Unexported functions & macros for use by arch-specific code */ +#define uprobe_opcode_sz (sizeof(uprobe_opcode_t)) + +/* + * Most architectures can use the default versions of @read_opcode(), + * @set_bkpt(), @set_orig_insn(), and @is_bkpt_insn(); + * + * @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). + * @pre_xol: + * 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. @pre_xol() should at least set the instruction pointer in + * @regs to @user_bkpt->xol_vaddr -- which is what the default, + * @pre_xol(), does. + * @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. + */ +#endif /* _LINUX_UPROBES_H */ diff --git a/kernel/Makefile b/kernel/Makefile index 2d64cfc..2ca229a 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -107,6 +107,7 @@ obj-$(CONFIG_PERF_EVENTS) += events/ obj-$(CONFIG_USER_RETURN_NOTIFIER) += user-return-notifier.o obj-$(CONFIG_PADATA) += padata.o obj-$(CONFIG_CRASH_DUMP) += crash_dump.o +obj-$(CONFIG_UPROBES) += uprobes.o ifneq ($(CONFIG_SCHED_OMIT_FRAME_POINTER),y) # According to Alan Modra , the -fno-omit-frame-pointer is diff --git a/kernel/uprobes.c b/kernel/uprobes.c new file mode 100644 index 0000000..7ef916e --- /dev/null +++ b/kernel/uprobes.c @@ -0,0 +1,309 @@ +/* + * 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, 2008-2011 + * Authors: + * Srikar Dronamraju + * Jim Keniston + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include /* needed for anon_vma_prepare */ +#include /* needed for set_pte_at_notify */ +#include /* needed for try_to_free_swap */ + +struct uprobe { + u8 insn[MAX_UINSN_BYTES]; + u16 fixups; +}; + +static bool valid_vma(struct vm_area_struct *vma) +{ + if (!vma->vm_file) + return false; + + if ((vma->vm_flags & (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)) == + (VM_READ|VM_EXEC)) + return true; + + return false; +} + +/** + * __replace_page - replace page in vma by new page. + * based on replace_page in mm/ksm.c + * + * @vma: vma that holds the pte pointing to page + * @page: the cowed page we are replacing by kpage + * @kpage: the modified page we replace page by + * + * Returns 0 on success, -EFAULT on failure. + */ +static int __replace_page(struct vm_area_struct *vma, struct page *page, + struct page *kpage) +{ + 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_trans_huge(*pmd) || (!pmd_present(*pmd))) + goto out; + + ptep = pte_offset_map_lock(mm, pmd, addr, &ptl); + if (!ptep) + goto out; + + get_page(kpage); + page_add_new_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); + if (!page_mapped(page)) + try_to_free_swap(page); + put_page(page); + pte_unmap_unlock(ptep, ptl); + err = 0; + +out: + return err; +} + +/* + * NOTE: + * Expect the breakpoint instruction to be the smallest size instruction for + * the architecture. If an arch has variable length instruction and the + * breakpoint instruction is not of the smallest length instruction + * supported by that architecture then we need to modify read_opcode / + * write_opcode accordingly. This would never be a problem for archs that + * have fixed length instructions. + */ + +/* + * write_opcode - write the opcode at a given virtual address. + * @tsk: the probed task. + * @uprobe: the breakpointing information. + * @vaddr: the virtual address to store the opcode. + * @opcode: opcode to be written at @vaddr. + * + * Called with tsk->mm->mmap_sem held (for read and with a reference to + * tsk->mm). + * + * For task @tsk, write the opcode at @vaddr. + * Return 0 (success) or a negative errno. + */ +static int write_opcode(struct task_struct *tsk, struct uprobe * uprobe, + unsigned long vaddr, uprobe_opcode_t opcode) +{ + struct page *old_page, *new_page; + void *vaddr_old, *vaddr_new; + struct vm_area_struct *vma; + unsigned long addr; + int ret; + + /* Read the page with vaddr into memory */ + ret = get_user_pages(tsk, tsk->mm, vaddr, 1, 1, 1, &old_page, &vma); + if (ret <= 0) + return ret; + ret = -EINVAL; + + /* + * We are interested in text pages only. Our pages of interest + * should be mapped for read and execute only. We desist from + * adding probes in write mapped pages since the breakpoints + * might end up in the file copy. + */ + if (!valid_vma(vma)) + 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); + /* 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 */ + addr = vaddr; + vaddr &= ~PAGE_MASK; + memcpy(vaddr_new + vaddr, &opcode, uprobe_opcode_sz); + + kunmap_atomic(vaddr_new); + kunmap_atomic(vaddr_old); + + ret = anon_vma_prepare(vma); + if (ret) + goto unlock_out; + + lock_page(new_page); + ret = __replace_page(vma, old_page, new_page); + unlock_page(new_page); + if (ret != 0) + page_cache_release(new_page); +unlock_out: + unlock_page(old_page); + +put_out: + put_page(old_page); /* we did a get_page in the beginning */ + return ret; +} + +/** + * read_opcode - read the opcode at a given virtual address. + * @tsk: the probed task. + * @vaddr: the virtual address to read the opcode. + * @opcode: location to store the read opcode. + * + * Called with tsk->mm->mmap_sem held (for read and with a reference to + * tsk->mm. + * + * 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, + uprobe_opcode_t *opcode) +{ + struct vm_area_struct *vma; + struct page *page; + void *vaddr_new; + int ret; + + ret = get_user_pages(tsk, tsk->mm, vaddr, 1, 0, 0, &page, &vma); + if (ret <= 0) + return ret; + ret = -EINVAL; + + /* + * We are interested in text pages only. Our pages of interest + * should be mapped for read and execute only. We desist from + * adding probes in write mapped pages since the breakpoints + * might end up in the file copy. + */ + if (!valid_vma(vma)) + goto put_out; + + lock_page(page); + vaddr_new = kmap_atomic(page, KM_USER0); + vaddr &= ~PAGE_MASK; + memcpy(opcode, vaddr_new + vaddr, uprobe_opcode_sz); + kunmap_atomic(vaddr_new); + unlock_page(page); + ret = 0; + +put_out: + put_page(page); /* we did a get_page in the beginning */ + return ret; +} + +/** + * set_bkpt - store breakpoint at a given address. + * @tsk: the probed task. + * @uprobe: the probepoint information. + * @vaddr: the virtual address to insert the opcode. + * + * For task @tsk, store the breakpoint instruction at @vaddr. + * Return 0 (success) or a negative errno. + */ +int __weak set_bkpt(struct task_struct *tsk, struct uprobe *uprobe, + unsigned long vaddr) +{ + return write_opcode(tsk, uprobe, vaddr, UPROBES_BKPT_INSN); +} + +/** + * set_orig_insn - Restore the original instruction. + * @tsk: the probed task. + * @uprobe: the probepoint information. + * @vaddr: the virtual address to insert the opcode. + * @verify: if true, verify existance of breakpoint instruction. + * + * For task @tsk, restore the original opcode (opcode) at @vaddr. + * Return 0 (success) or a negative errno. + */ +int __weak set_orig_insn(struct task_struct *tsk, struct uprobe *uprobe, + unsigned long vaddr, bool verify) +{ + if (verify) { + uprobe_opcode_t opcode; + int result = read_opcode(tsk, vaddr, &opcode); + if (result) + return result; + if (opcode != UPROBES_BKPT_INSN) + return -EINVAL; + } + return write_opcode(tsk, uprobe, vaddr, + *(uprobe_opcode_t *) uprobe->insn); +} + +static void print_insert_fail(struct task_struct *tsk, + unsigned long vaddr, const char *why) +{ + pr_warn_once("Can't place breakpoint at pid %d vaddr" " %#lx: %s\n", + tsk->pid, vaddr, why); +} + +/** + * is_bkpt_insn - check if instruction is breakpoint instruction. + * @insn: instruction to be checked. + * Default implementation of is_bkpt_insn + * Returns true if @insn is a breakpoint instruction. + */ +bool __weak is_bkpt_insn(u8 *insn) +{ + uprobe_opcode_t opcode; + + memcpy(&opcode, insn, UPROBES_BKPT_INSN_SIZE); + return (opcode == UPROBES_BKPT_INSN); +} -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/