From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757036AbYCUOcy (ORCPT ); Fri, 21 Mar 2008 10:32:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754290AbYCUOcq (ORCPT ); Fri, 21 Mar 2008 10:32:46 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:37259 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753145AbYCUOcp (ORCPT ); Fri, 21 Mar 2008 10:32:45 -0400 Date: Fri, 21 Mar 2008 15:32:29 +0100 From: Ingo Molnar To: Ananth N Mavinakayanahalli Cc: Yakov Lerner , anil.s.keshavamurthy@intel.com, davem@davemloft.net, linux-kernel@vger.kernel.org, Masami Hiramatsu Subject: Re: [PATCH] Subject: kprobes-x86: correct post-eip value in post_hander() Message-ID: <20080321143229.GE31719@elte.hu> References: <20080321110804.GY20420@elte.hu> <20080321113134.GA7620@in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080321113134.GA7620@in.ibm.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Ananth N Mavinakayanahalli wrote: > > thanks, i've added your patch to the .26 bucket of x86.git, but it > > would be nice to get an Ack/Nack from a kprobes person as well. > > Ingo, > > I've tested Yakov's more comprehensive patch on powerpc too. This has > my ack. > > Acked-by: Ananth N Mavinakayanahalli thanks, i've queued up the x86-only patch below for .26 merging. (that is all that is needed for x86, and no .25 urgency, right?) Ingo ------------------> Subject: x86, kprobes: correct post-eip value in post_hander() From: "Yakov Lerner" Date: Sun, 16 Mar 2008 03:21:21 -0500 I was trying to get the address of instruction to be executed next after the kprobed instruction. But regs->eip in post_handler() contains value which is useless to the user. It's pre-corrected value. This value is difficult to use without access to resume_execution(), which is not exported anyway. I moved the invocation of post_handler() to *after* resume_execution(). Now regs->eip contains meaningful value in post_handler(). I do not think this change breaks any backward-compatibility. To make meaning of the old value, post_handler() would need access to resume_execution() which is not exported. I have difficulty to believe that previous, uncorrected, regs->eip can be meaningfully used in post_handler(). Signed-off-by: Yakov Lerner Acked-by: Ananth N Mavinakayanahalli Signed-off-by: Ingo Molnar --- arch/x86/kernel/kprobes.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) Index: linux-x86.q/arch/x86/kernel/kprobes.c =================================================================== --- linux-x86.q.orig/arch/x86/kernel/kprobes.c +++ linux-x86.q/arch/x86/kernel/kprobes.c @@ -858,15 +858,15 @@ static int __kprobes post_kprobe_handler if (!cur) return 0; + resume_execution(cur, regs, kcb); + regs->flags |= kcb->kprobe_saved_flags; + trace_hardirqs_fixup_flags(regs->flags); + if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { kcb->kprobe_status = KPROBE_HIT_SSDONE; cur->post_handler(cur, regs, 0); } - resume_execution(cur, regs, kcb); - regs->flags |= kcb->kprobe_saved_flags; - trace_hardirqs_fixup_flags(regs->flags); - /* Restore back the original saved kprobes variables and continue. */ if (kcb->kprobe_status == KPROBE_REENTER) { restore_previous_kprobe(kcb);