From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754218Ab0LPKAf (ORCPT ); Thu, 16 Dec 2010 05:00:35 -0500 Received: from e23smtp01.au.ibm.com ([202.81.31.143]:39189 "EHLO e23smtp01.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752299Ab0LPKA3 (ORCPT ); Thu, 16 Dec 2010 05:00:29 -0500 From: Srikar Dronamraju To: Peter Zijlstra , Ingo Molnar Cc: Steven Rostedt , Srikar Dronamraju , Arnaldo Carvalho de Melo , Linus Torvalds , Andi Kleen , Christoph Hellwig , Ananth N Mavinakayanahalli , Masami Hiramatsu , Oleg Nesterov , Andrew Morton , Linux-mm , Jim Keniston , Frederic Weisbecker , SystemTap , LKML , "Paul E. McKenney" Date: Thu, 16 Dec 2010 15:27:49 +0530 Message-Id: <20101216095749.23751.39331.sendpatchset@localhost6.localdomain6> In-Reply-To: <20101216095714.23751.52601.sendpatchset@localhost6.localdomain6> References: <20101216095714.23751.52601.sendpatchset@localhost6.localdomain6> Subject: [RFC] [PATCH 2.6.37-rc5-tip 3/20] 3: uprobes: Breakground page replacement. Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Provides Background page replacement using replace_page() routine. Also provides routines to read/write few bytes to vm and for verifying if a instruction is a breakpoint instruction. Signed-off-by: Srikar Dronamraju Signed-off-by: Jim Keniston --- arch/Kconfig | 11 ++ arch/x86/include/asm/uprobes.h | 2 include/linux/uprobes.h | 76 ++++++++++++ kernel/Makefile | 1 kernel/uprobes.c | 252 ++++++++++++++++++++++++++++++++++++++++ 5 files changed, 341 insertions(+), 1 deletions(-) create mode 100644 include/linux/uprobes.h create mode 100644 kernel/uprobes.c diff --git a/arch/Kconfig b/arch/Kconfig index f78c2be..6e8f26e 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -61,6 +61,17 @@ 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 + 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 diff --git a/arch/x86/include/asm/uprobes.h b/arch/x86/include/asm/uprobes.h index 0e8ad5d..5026359 100644 --- a/arch/x86/include/asm/uprobes.h +++ b/arch/x86/include/asm/uprobes.h @@ -25,7 +25,7 @@ typedef u8 uprobe_opcode_t; #define MAX_UINSN_BYTES 16 -#define UPROBES_XOL_SLOT_BYTES (MAX_UINSN_BYTES) +#define UPROBES_XOL_SLOT_BYTES 128 /* to keep it cache aligned */ #define UPROBES_BKPT_INSN 0xcc #define UPROBES_BKPT_INSN_SIZE 1 diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h new file mode 100644 index 0000000..952e9d7 --- /dev/null +++ b/include/linux/uprobes.h @@ -0,0 +1,76 @@ +#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 +#else +/* + * ARCH_SUPPORTS_UPROBES has not be defined. + */ +typedef u8 uprobe_opcode_t; + +/* Post-execution fixups. Some architectures may define others. */ +#endif /* CONFIG_ARCH_SUPPORTS_UPROBES */ + +/* 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)) +extern unsigned long uprobes_read_vm(struct task_struct *tsk, + void __user *vaddr, void *kbuf, + unsigned long nbytes); +extern unsigned long uprobes_write_vm(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(); + * + * @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 + * @pre_xol: + * @post_xol: + * 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). + */ +#endif /* _LINUX_UPROBES_H */ diff --git a/kernel/Makefile b/kernel/Makefile index 0b5ff08..e53c0c4 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -106,6 +106,7 @@ 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 , the -fno-omit-frame-pointer is diff --git a/kernel/uprobes.c b/kernel/uprobes.c new file mode 100644 index 0000000..cb5884b --- /dev/null +++ b/kernel/uprobes.c @@ -0,0 +1,252 @@ +/* + * 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 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include /* needed for anon_vma_prepare */ + +struct uprobe { + uprobe_opcode_t opcode; + u16 fixups; +}; + +/** + * 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_vm - 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_vm(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, + uprobe_opcode_t opcode) +{ + struct page *old_page, *new_page; + void *vaddr_old, *vaddr_new; + struct vm_area_struct *vma; + struct mm_struct *mm; + pte_t orig_pte; + int ret = -EINVAL; + + mm = get_task_mm(tsk); + down_read(&mm->mmap_sem); + + /* Read the page with vaddr into memory */ + ret = get_user_pages(tsk, mm, vaddr, 1, 0, 0, &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); + /* 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, uprobe_opcode_sz); + + kunmap_atomic(vaddr_new, KM_USER1); + kunmap_atomic(vaddr_old, KM_USER0); + + /* 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; + + lock_page(new_page); + if (!anon_vma_prepare(vma)) + /* flip pages, do_wp_page() will fail pte_same() and bail */ + ret = replace_page(vma, old_page, new_page, orig_pte); + + 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 */ + +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, + uprobe_opcode_t *opcode) +{ + unsigned long bytes_read; + + bytes_read = uprobes_read_vm(tsk, (void __user *) vaddr, opcode, + uprobe_opcode_sz); + return (bytes_read == uprobe_opcode_sz ? 0 : -EFAULT); +} + +/** + * set_bkpt - store breakpoint at a given address. + * @tsk: the probed task + * @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, unsigned long vaddr) +{ + return write_opcode(tsk, vaddr, UPROBES_BKPT_INSN); +} + +/** + * set_orig_insn - Restore the original instruction. + * @tsk: the probed task + * @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, unsigned long vaddr, + bool verify, struct uprobe *uprobe) +{ + 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, vaddr, uprobe->opcode); +} + +static void print_insert_fail(struct task_struct *tsk, + unsigned long vaddr, const char *why) +{ + printk(KERN_ERR "Can't place breakpoint at pid %d vaddr %#lx: %s\n", + tsk->pid, vaddr, why); +} + +/* + * uprobes_resume_can_sleep - Check if fixup might result in sleep. + * @uprobes: the probepoint information. + * + * Returns true if fixup might result in sleep. + */ +static bool uprobes_resume_can_sleep(struct uprobe *uprobe) +{ + return uprobe->fixups & UPROBES_FIX_SLEEPY; +} + +/** + * is_bkpt_insn - check if instruction is breakpoint instruction. + * @uprobe: the probepoint information. + * Default implementation of is_bkpt_insn + * Returns true if @uprobe->opcode is @bkpt_insn. + */ +bool __weak is_bkpt_insn(struct uprobe *uprobe) +{ + return (uprobe->opcode == UPROBES_BKPT_INSN); +} +