Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756666AbYAATpT (ORCPT ); Tue, 1 Jan 2008 14:45:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754823AbYAATpG (ORCPT ); Tue, 1 Jan 2008 14:45:06 -0500 Received: from rv-out-0910.google.com ([209.85.198.188]:24749 "EHLO rv-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753864AbYAATpD (ORCPT ); Tue, 1 Jan 2008 14:45:03 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:cc:subject:references:in-reply-to:content-type:content-transfer-encoding; b=nUDRrI/7oVI6+UwMiyoqPc9iu9cHKJy7AB8FuJk5Tq2Ko/sgqmhydThm0M+XEgPaJoi8kz5KI/DMF7CIZwwkLJpw2FTBwFc+fF8+jsiNswk51ZbzNHKDbLfednMGJ/4ll/fRHeLeulH+490kgjDs/X8Y9RxMeTGg447k2WR5MKU= Message-ID: <477A971A.8030006@gmail.com> Date: Wed, 02 Jan 2008 01:10:10 +0530 From: Abhishek Sagar User-Agent: Thunderbird 2.0.0.9 (X11/20071031) MIME-Version: 1.0 To: Ingo Molnar CC: Harvey Harrison , Masami Hiramatsu , "H. Peter Anvin" , LKML , Thomas Gleixner , qbarnes@gmail.com, ananth@in.ibm.com, jkenisto@us.ibm.com Subject: Re: [PATCH] x86: kprobes change kprobe_handler flow References: <1198806265.6323.34.camel@brick> <4778E8B0.6010400@gmail.com> <20080101153558.GJ4434@elte.hu> In-Reply-To: <20080101153558.GJ4434@elte.hu> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7416 Lines: 250 Ingo Molnar wrote: > hm, this patch does not apply to x86.git#mm, due to the fixes, > unifications and cleanups done there. Could you send a patch against -mm > or against x86.git? (see the tree-fetching instructions below) Thanks, > > Ingo > > --------------{ x86.git instructions }----------> > > git-clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git linux-2.6.git > cd linux-2.6.git > git-branch x86 > git-checkout x86 > git-pull git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-x86.git mm > > (do subsequent pulls via "git-pull --force", as we frequently rebase the > git tree. NOTE: this might override your own local changes, so do this > only if you dont mind about losing thse changes in that tree.) > Thanks for pointing me to the right tree. I have made some code re-arrangements in this one. Signed-off-by: Abhishek Sagar Signed-off-by: Quentin Barnes --- diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c index a72e02b..45adc8e 100644 --- a/arch/x86/kernel/kprobes.c +++ b/arch/x86/kernel/kprobes.c @@ -441,6 +441,26 @@ void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, /* Replace the return addr with trampoline addr */ *sara = (unsigned long) &kretprobe_trampoline; } + +#if !defined(CONFIG_PREEMPT) || defined(CONFIG_PM) +static __always_inline int setup_boost(struct kprobe *p, struct pt_regs *regs) +{ + if (p->ainsn.boostable == 1 && !p->post_handler) { + /* Boost up -- we can execute copied instructions directly */ + reset_current_kprobe(); + regs->ip = (unsigned long)p->ainsn.insn; + preempt_enable_no_resched(); + return 0; + } + return 1; +} +#else +static __always_inline int setup_boost(struct kprobe *p, struct pt_regs *regs) +{ + return 1; +} +#endif + /* * We have reentered the kprobe_handler(), since another probe was hit while * within the handler. We save the original kprobes variables and just single @@ -449,29 +469,47 @@ void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, static int __kprobes reenter_kprobe(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb) { - if (kcb->kprobe_status == KPROBE_HIT_SS && - *p->ainsn.insn == BREAKPOINT_INSTRUCTION) { - regs->flags &= ~X86_EFLAGS_TF; - regs->flags |= kcb->kprobe_saved_flags; - return 0; + int ret = 0; + + switch (kcb->kprobe_status) { + case KPROBE_HIT_SSDONE: #ifdef CONFIG_X86_64 - } else if (kcb->kprobe_status == KPROBE_HIT_SSDONE) { - /* TODO: Provide re-entrancy from post_kprobes_handler() and - * avoid exception stack corruption while single-stepping on + /* TODO: Provide re-entrancy from + * post_kprobes_handler() and avoid exception + * stack corruption while single-stepping on * the instruction of the new probe. */ arch_disarm_kprobe(p); regs->ip = (unsigned long)p->addr; reset_current_kprobe(); - return 1; + preempt_enable_no_resched(); + ret = 1; + break; #endif + case KPROBE_HIT_ACTIVE: + /* a probe has been hit inside a + * user handler */ + save_previous_kprobe(kcb); + set_current_kprobe(p, regs, kcb); + kprobes_inc_nmissed_count(p); + prepare_singlestep(p, regs); + kcb->kprobe_status = KPROBE_REENTER; + ret = 1; + break; + case KPROBE_HIT_SS: + if (*p->ainsn.insn == BREAKPOINT_INSTRUCTION) { + regs->flags &= ~TF_MASK; + regs->flags |= kcb->kprobe_saved_flags; + } else { + /* BUG? */ + } + break; + default: + /* impossible cases */ + BUG(); } - save_previous_kprobe(kcb); - set_current_kprobe(p, regs, kcb); - kprobes_inc_nmissed_count(p); - prepare_singlestep(p, regs); - kcb->kprobe_status = KPROBE_REENTER; - return 1; + + return ret; } /* @@ -480,82 +518,67 @@ static int __kprobes reenter_kprobe(struct kprobe *p, struct pt_regs *regs, */ static int __kprobes kprobe_handler(struct pt_regs *regs) { - struct kprobe *p; int ret = 0; kprobe_opcode_t *addr; + struct kprobe *p, *cur; struct kprobe_ctlblk *kcb; addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t)); + if (*addr != BREAKPOINT_INSTRUCTION) { + /* + * The breakpoint instruction was removed right + * after we hit it. Another cpu has removed + * either a probepoint or a debugger breakpoint + * at this address. In either case, no further + * handling of this interrupt is appropriate. + * Back up over the (now missing) int3 and run + * the original instruction. + */ + regs->ip = (unsigned long)addr; + return 1; + } - /* - * We don't want to be preempted for the entire - * duration of kprobe processing - */ preempt_disable(); kcb = get_kprobe_ctlblk(); - + cur = kprobe_running(); p = get_kprobe(addr); + if (p) { - /* Check we're not actually recursing */ - if (kprobe_running()) { + if (cur) { ret = reenter_kprobe(p, regs, kcb); - if (kcb->kprobe_status == KPROBE_REENTER) - { - ret = 1; - goto out; - } - goto preempt_out; } else { set_current_kprobe(p, regs, kcb); kcb->kprobe_status = KPROBE_HIT_ACTIVE; - if (p->pre_handler && p->pre_handler(p, regs)) - { - /* handler set things up, skip ss setup */ - ret = 1; - goto out; - } - } - } else { - if (*addr != BREAKPOINT_INSTRUCTION) { + /* - * The breakpoint instruction was removed right - * after we hit it. Another cpu has removed - * either a probepoint or a debugger breakpoint - * at this address. In either case, no further - * handling of this interrupt is appropriate. - * Back up over the (now missing) int3 and run - * the original instruction. + * If we have no pre-handler or it returned 0, we + * continue with normal processing. If we have a + * pre-handler and it returned non-zero, it prepped + * for calling the break_handler below on re-entry + * for jprobe processing, so get out doing nothing + * more here. */ - regs->ip = (unsigned long)addr; + if (!p->pre_handler || !p->pre_handler(p, regs)) { + if (setup_boost(p, regs)) { + prepare_singlestep(p, regs); + kcb->kprobe_status = KPROBE_HIT_SS; + } + } ret = 1; - goto preempt_out; } - if (kprobe_running()) { - p = __get_cpu_var(current_kprobe); - if (p->break_handler && p->break_handler(p, regs)) - goto ss_probe; + } else if (cur) { + p = __get_cpu_var(current_kprobe); + if (p->break_handler && p->break_handler(p, regs)) { + if (setup_boost(p, regs)) { + prepare_singlestep(p, regs); + kcb->kprobe_status = KPROBE_HIT_SS; + } + ret = 1; } - /* Not one of ours: let kernel handle it */ - goto preempt_out; - } + } /* else: not a kprobe fault; let the kernel handle it */ -ss_probe: - ret = 1; -#if !defined(CONFIG_PREEMPT) || defined(CONFIG_PM) - if (p->ainsn.boostable == 1 && !p->post_handler) { - /* Boost up -- we can execute copied instructions directly */ - reset_current_kprobe(); - regs->ip = (unsigned long)p->ainsn.insn; - goto preempt_out; - } -#endif - prepare_singlestep(p, regs); - kcb->kprobe_status = KPROBE_HIT_SS; - goto out; - -preempt_out: - preempt_enable_no_resched(); -out: + if (!ret) + preempt_enable_no_resched(); return ret; } -- 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/