From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756094AbYCULba (ORCPT ); Fri, 21 Mar 2008 07:31:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754173AbYCULbW (ORCPT ); Fri, 21 Mar 2008 07:31:22 -0400 Received: from e31.co.us.ibm.com ([32.97.110.149]:49910 "EHLO e31.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753774AbYCULbV (ORCPT ); Fri, 21 Mar 2008 07:31:21 -0400 Date: Fri, 21 Mar 2008 17:01:34 +0530 From: Ananth N Mavinakayanahalli To: Ingo Molnar 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: <20080321113134.GA7620@in.ibm.com> Reply-To: ananth@in.ibm.com References: <20080321110804.GY20420@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080321110804.GY20420@elte.hu> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 21, 2008 at 12:08:04PM +0100, Ingo Molnar wrote: > > * Yakov Lerner wrote: > > > 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(). > > 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