From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754305Ab0LPKBS (ORCPT ); Thu, 16 Dec 2010 05:01:18 -0500 Received: from e28smtp07.in.ibm.com ([122.248.162.7]:52457 "EHLO e28smtp07.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754115Ab0LPKBO (ORCPT ); Thu, 16 Dec 2010 05:01:14 -0500 From: Srikar Dronamraju To: Peter Zijlstra , Ingo Molnar Cc: Steven Rostedt , Srikar Dronamraju , Arnaldo Carvalho de Melo , Linus Torvalds , Masami Hiramatsu , Christoph Hellwig , Andi Kleen , Oleg Nesterov , Andrew Morton , SystemTap , Linux-mm , Jim Keniston , Frederic Weisbecker , Ananth N Mavinakayanahalli , LKML , "Paul E. McKenney" Date: Thu, 16 Dec 2010 15:28:37 +0530 Message-Id: <20101216095837.23751.45271.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 7/20] 7: uprobes: store/restore original instruction. Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On the first probe insertion, copy the original instruction and opcode. If multiple vmas map the same text area corresponding to an inode, we only need to copy the instruction just once. The copied instruction is further copied to a designated slot on probe hit. Its also used at the time of probe removal to restore the original instruction. opcode is used to analyze the instruction and determine the fixups. Determining fixups at probe hit time would result in doing the same operation on every probe hit. Hence Instruction analysis using the opcode is done at probe insertion time. Signed-off-by: Srikar Dronamraju --- arch/Kconfig | 1 + kernel/uprobes.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++++++---- 2 files changed, 57 insertions(+), 5 deletions(-) diff --git a/arch/Kconfig b/arch/Kconfig index 6e8f26e..bba8108 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -65,6 +65,7 @@ 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 diff --git a/kernel/uprobes.c b/kernel/uprobes.c index 8a5da38..858ddb1 100644 --- a/kernel/uprobes.c +++ b/kernel/uprobes.c @@ -448,21 +448,72 @@ static int del_consumer(struct uprobe *uprobe, return ret; } +static int copy_insn(struct task_struct *tsk, unsigned long vaddr, + struct uprobe *uprobe) +{ + int len; + + len = uprobes_read_vm(tsk, (void __user *)vaddr, uprobe->insn, + MAX_UINSN_BYTES); + if (len < uprobe_opcode_sz) { + print_insert_fail(tsk, vaddr, + "error reading original instruction"); + return -EINVAL; + } + memcpy(&uprobe->opcode, uprobe->insn, uprobe_opcode_sz); + if (is_bkpt_insn(uprobe)) { + print_insert_fail(tsk, vaddr, + "breakpoint instruction already exists"); + return -EEXIST; + } + if (analyze_insn(tsk, uprobe)) { + print_insert_fail(tsk, vaddr, + "instruction type cannot be probed"); + return -EINVAL; + } + uprobe->copy = 1; + return 0; +} + static int install_uprobe(struct mm_struct *mm, struct uprobe *uprobe) { - int ret = 0; + struct task_struct *tsk; + int ret = -EINVAL; - /*TODO: install breakpoint */ - if (!ret) + get_task_struct(mm->owner); + tsk = mm->owner; + if (!tsk) + return ret; + + if (!uprobe->copy) { + ret = copy_insn(tsk, mm->uprobes_vaddr, uprobe); + if (ret) + goto put_return; + } + + ret = set_bkpt(tsk, mm->uprobes_vaddr); + if (ret < 0) + print_insert_fail(tsk, mm->uprobes_vaddr, + "failed to insert bkpt instruction"); + else atomic_inc(&mm->uprobes_count); + +put_return: + put_task_struct(tsk); return ret; } static int remove_uprobe(struct mm_struct *mm, struct uprobe *uprobe) { - int ret = 0; + struct task_struct *tsk; + int ret; + + get_task_struct(mm->owner); + tsk = mm->owner; + if (!tsk) + return -EINVAL; - /*TODO: remove breakpoint */ + ret = set_orig_insn(tsk, mm->uprobes_vaddr, true, uprobe); if (!ret) atomic_dec(&mm->uprobes_count);