Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932173AbZKYQ6z (ORCPT ); Wed, 25 Nov 2009 11:58:55 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758865AbZKYQ5x (ORCPT ); Wed, 25 Nov 2009 11:57:53 -0500 Received: from mx1.redhat.com ([209.132.183.28]:55020 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758861AbZKYQ5u (ORCPT ); Wed, 25 Nov 2009 11:57:50 -0500 From: Masami Hiramatsu Subject: [PATCH -tip v6 05/11] kprobes/x86: Boost probes when reentering To: Frederic Weisbecker , Ingo Molnar , Ananth N Mavinakayanahalli , lkml Cc: systemtap , DLE , Masami Hiramatsu , Ananth N Mavinakayanahalli , Ingo Molnar , Jim Keniston , Srikar Dronamraju , Christoph Hellwig , Steven Rostedt , Frederic Weisbecker , "H. Peter Anvin" , Anders Kaseorg , Tim Abbott , Andi Kleen , Jason Baron , Mathieu Desnoyers Date: Wed, 25 Nov 2009 11:55:49 -0500 Message-ID: <20091125165549.6073.2537.stgit@harusame> In-Reply-To: <20091125165510.6073.48721.stgit@harusame> References: <20091125165510.6073.48721.stgit@harusame> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4306 Lines: 132 Integrate prepare_singlestep() into setup_singlestep() to boost up reenter probes, if possible. Signed-off-by: Masami Hiramatsu Cc: Ananth N Mavinakayanahalli Cc: Ingo Molnar Cc: Jim Keniston Cc: Srikar Dronamraju Cc: Christoph Hellwig Cc: Steven Rostedt Cc: Frederic Weisbecker Cc: H. Peter Anvin Cc: Anders Kaseorg Cc: Tim Abbott Cc: Andi Kleen Cc: Jason Baron Cc: Mathieu Desnoyers --- arch/x86/kernel/kprobes.c | 48 ++++++++++++++++++++++++--------------------- 1 files changed, 26 insertions(+), 22 deletions(-) diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c index b6b75f1..85d88f6 100644 --- a/arch/x86/kernel/kprobes.c +++ b/arch/x86/kernel/kprobes.c @@ -403,18 +403,6 @@ static void __kprobes restore_btf(void) update_debugctlmsr(current->thread.debugctlmsr); } -static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs) -{ - clear_btf(); - regs->flags |= X86_EFLAGS_TF; - regs->flags &= ~X86_EFLAGS_IF; - /* single step inline if the instruction is an int3 */ - if (p->opcode == BREAKPOINT_INSTRUCTION) - regs->ip = (unsigned long)p->addr; - else - regs->ip = (unsigned long)p->ainsn.insn; -} - void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs) { @@ -427,19 +415,38 @@ void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, } static void __kprobes setup_singlestep(struct kprobe *p, struct pt_regs *regs, - struct kprobe_ctlblk *kcb) + struct kprobe_ctlblk *kcb, int reenter) { #if !defined(CONFIG_PREEMPT) || defined(CONFIG_FREEZER) if (p->ainsn.boostable == 1 && !p->post_handler) { /* Boost up -- we can execute copied instructions directly */ - reset_current_kprobe(); + if (!reenter) + reset_current_kprobe(); + /* + * Reentering boosted probe doesn't reset current_kprobe, + * nor set current_kprobe, because it doesn't use single + * stepping. + */ regs->ip = (unsigned long)p->ainsn.insn; preempt_enable_no_resched(); return; } #endif - prepare_singlestep(p, regs); - kcb->kprobe_status = KPROBE_HIT_SS; + if (reenter) { + save_previous_kprobe(kcb); + set_current_kprobe(p, regs, kcb); + kcb->kprobe_status = KPROBE_REENTER; + } else + kcb->kprobe_status = KPROBE_HIT_SS; + /* Prepare real single stepping */ + clear_btf(); + regs->flags |= X86_EFLAGS_TF; + regs->flags &= ~X86_EFLAGS_IF; + /* single step inline if the instruction is an int3 */ + if (p->opcode == BREAKPOINT_INSTRUCTION) + regs->ip = (unsigned long)p->addr; + else + regs->ip = (unsigned long)p->ainsn.insn; } /* @@ -453,11 +460,8 @@ static int __kprobes reenter_kprobe(struct kprobe *p, struct pt_regs *regs, switch (kcb->kprobe_status) { case KPROBE_HIT_SSDONE: case KPROBE_HIT_ACTIVE: - save_previous_kprobe(kcb); - set_current_kprobe(p, regs, kcb); kprobes_inc_nmissed_count(p); - prepare_singlestep(p, regs); - kcb->kprobe_status = KPROBE_REENTER; + setup_singlestep(p, regs, kcb, 1); break; case KPROBE_HIT_SS: /* A probe has been hit in the codepath leading up to, or just @@ -532,13 +536,13 @@ static int __kprobes kprobe_handler(struct pt_regs *regs) * more here. */ if (!p->pre_handler || !p->pre_handler(p, regs)) - setup_singlestep(p, regs, kcb); + setup_singlestep(p, regs, kcb, 0); return 1; } } else if (kprobe_running()) { p = __get_cpu_var(current_kprobe); if (p->break_handler && p->break_handler(p, regs)) { - setup_singlestep(p, regs, kcb); + setup_singlestep(p, regs, kcb, 0); return 1; } } /* else: not a kprobe fault; let the kernel handle it */ -- Masami Hiramatsu Software Engineer Hitachi Computer Products (America), Inc. Software Solutions Division e-mail: mhiramat@redhat.com -- 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/