Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754750AbZJUS1T (ORCPT ); Wed, 21 Oct 2009 14:27:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754724AbZJUS1Q (ORCPT ); Wed, 21 Oct 2009 14:27:16 -0400 Received: from hofr.at ([212.69.189.236]:49888 "EHLO mail.hofr.at" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754719AbZJUS1O (ORCPT ); Wed, 21 Oct 2009 14:27:14 -0400 X-Greylist: delayed 612 seconds by postgrey-1.27 at vger.kernel.org; Wed, 21 Oct 2009 14:27:14 EDT Date: Wed, 21 Oct 2009 20:17:05 +0200 From: Nicholas Mc Guire To: Steven Rostedt Cc: David Daney , Wu Zhangjin , linux-kernel@vger.kernel.org, linux-mips@linux-mips.org, Thomas Gleixner , Ralf Baechle Subject: Re: [PATCH -v4 9/9] tracing: add function graph tracer support for MIPS Message-ID: <20091021181705.GA5218@opentech.at> References: <53bdfdd95ec4fa00d4cc505bb5972cf21243a14d.1256135456.git.wuzhangjin@gmail.com> <1256141540.18347.3118.camel@gandalf.stny.rr.com> <4ADF38D5.9060100@caviumnetworks.com> <1256143568.18347.3169.camel@gandalf.stny.rr.com> <4ADF3FE0.5090104@caviumnetworks.com> <1256145813.18347.3210.camel@gandalf.stny.rr.com> <4ADF4982.9010306@caviumnetworks.com> <1256148562.18347.3264.camel@gandalf.stny.rr.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1256148562.18347.3264.camel@gandalf.stny.rr.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 862 Lines: 20 > > > We're not doing back traces. We need to modify the return of the > function being called. Note, the above functions that end with ";" are > leaf functions. Non leaf functions show "{" and end with "}". > > The trick here is to find a reliable way to modify the return address. > would it not more or less be the same thing if you used -finstrument-functions then and provide a stub __cyg_profile_func_enter/exit initialized to an empty function until you replace it during tracing. This does give you an overhead when you are not tracing - but it would make the tracer implementation quite generic. hofrat -- 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/