Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755881AbZJVQLy (ORCPT ); Thu, 22 Oct 2009 12:11:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753620AbZJVQLx (ORCPT ); Thu, 22 Oct 2009 12:11:53 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.123]:59170 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753287AbZJVQLx (ORCPT ); Thu, 22 Oct 2009 12:11:53 -0400 Subject: Re: [PATCH -v4 9/9] tracing: add function graph tracer support for MIPS From: Steven Rostedt Reply-To: rostedt@goodmis.org To: David Daney Cc: wuzhangjin@gmail.com, linux-kernel@vger.kernel.org, linux-mips@linux-mips.org, Thomas Gleixner , Ralf Baechle , Nicholas Mc Guire In-Reply-To: <4AE08173.7070500@caviumnetworks.com> References: <028867b99ec532b84963a35e7d552becc783cafc.1256135456.git.wuzhangjin@gmail.com> <2f73eae542c47ac5bbb9f7280e6c0271d193e90d.1256135456.git.wuzhangjin@gmail.com> <3f0d3515f74a58f4cfd11e61b62a129fdc21e3a7.1256135456.git.wuzhangjin@gmail.com> <96110ea5dd4d3d54eb97d0bb708a5bd81c7a50b5.1256135456.git.wuzhangjin@gmail.com> <5dda13e8e3a9c9dba4bb7179183941bda502604f.1256135456.git.wuzhangjin@gmail.com> <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> <1256211516.3852.47.camel@falcon> <4AE08173.7070500@caviumnetworks.com> Content-Type: text/plain Organization: Kihon Technologies Inc. Date: Thu, 22 Oct 2009 12:11:56 -0400 Message-Id: <1256227916.20866.784.camel@gandalf.stny.rr.com> Mime-Version: 1.0 X-Mailer: Evolution 2.26.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 950 Lines: 21 On Thu, 2009-10-22 at 08:59 -0700, David Daney wrote: > This is what I was talking about up-thread. Leaf functions may have no > function prolog. If you do code scanning you will fail. While scanning > backwards, there is no way to know when you have entered a new function. > Looking for function return sequences 'jr ra' doesn't work as there > may be functions with multiple return sites, functions that never > return, or arbitrary data before the function. I think you have to > force a frame pointer to be established if you want this to work. Functions that run off into another function?? I guess the compiler could do that, but with -pg enable, I would think is broken. -- Steve -- 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/