From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753101AbYH1Hu5 (ORCPT ); Thu, 28 Aug 2008 03:50:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753003AbYH1Hus (ORCPT ); Thu, 28 Aug 2008 03:50:48 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:34826 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751123AbYH1Hus (ORCPT ); Thu, 28 Aug 2008 03:50:48 -0400 Date: Thu, 28 Aug 2008 09:50:26 +0200 From: Ingo Molnar To: Steven Rostedt Cc: LKML , Thomas Gleixner , Peter Zijlstra , Andrew Morton Subject: Re: [PATCH] ftrace: remove direct reference to mcount in trace code Message-ID: <20080828075023.GI21875@elte.hu> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) 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 * Steven Rostedt wrote: > The mcount record method of ftrace scans objdump for references to > mcount. Using mcount as the reference to test if the calls to mcount > being replaced are indeed calls to mcount, this use of mcount was also > caught as a location to change. Using a variable that points to the > mcount address moves this reference into the data section that is not > scanned, and we do not use a false location to try and modify. > > The warn on code was what was used to detect this bug. > > Signed-off-by: Steven Rostedt applied to tip/tracing/ftrace - thanks Steve! Ingo