From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 8511 invoked by alias); 25 Nov 2009 20:13:15 -0000 Received: (qmail 8497 invoked by uid 22791); 25 Nov 2009 20:13:14 -0000 X-SWARE-Spam-Status: No, hits=-2.5 required=5.0 tests=AWL,BAYES_00 X-Spam-Check-By: sourceware.org Received: from terminus.zytor.com (HELO terminus.zytor.com) (198.137.202.10) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Wed, 25 Nov 2009 20:13:11 +0000 Received: from tazenda.hos.anvin.org (c-98-210-181-100.hsd1.ca.comcast.net [98.210.181.100]) (authenticated bits=0) by terminus.zytor.com (8.14.3/8.14.3) with ESMTP id nAPKCn8I024227 (version=TLSv1/SSLv3 cipher=DHE-RSA-CAMELLIA256-SHA bits=256 verify=NO); Wed, 25 Nov 2009 12:12:49 -0800 Message-ID: <4B0D8FC1.1010608@zytor.com> Date: Wed, 25 Nov 2009 20:13:00 -0000 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.4pre) Gecko/20091014 Fedora/3.0-2.8.b4.fc11 Thunderbird/3.0b4 MIME-Version: 1.0 To: Jakub Jelinek CC: Ingo Molnar , Thomas Gleixner , Andrew Haley , "H.J. Lu" , rostedt@goodmis.org, LKML , Andrew Morton , Heiko Carstens , feng.tang@intel.com, Peter Zijlstra , Frederic Weisbecker , David Daney , Richard Guenther , gcc , Linus Torvalds Subject: Re: [PATCH][GIT PULL][v2.6.32] tracing/x86: Add check to detect GCC messing with mcount prologue References: <1258736456.22249.1032.camel@gandalf.stny.rr.com> <4B06EF6F.2050507@redhat.com> <6dc9ffc80911220138y15bfa91agccf5c29f1c30e09a@mail.gmail.com> <4B0972C9.302@redhat.com> <6dc9ffc80911221530t38d83cf6je739743c8d756667@mail.gmail.com> <4B0BF119.4070704@redhat.com> <20091124150604.GJ22813@hs20-bc2-1.build.redhat.com> <20091125154452.GA9456@elte.hu> <20091125164434.GS22813@hs20-bc2-1.build.redhat.com> In-Reply-To: <20091125164434.GS22813@hs20-bc2-1.build.redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org X-SW-Source: 2009-11/txt/msg00706.txt.bz2 On 11/25/2009 08:44 AM, Jakub Jelinek wrote: > > If you compile kernels 90%+ people out there run with -p on i?86/x86_64, > then certainly coming up with a new gcc switch and new profiling ABI is > desirable. -p on i?86/x86_64 e.g. forces -fno-omit-frame-pointer, which > makes code on these register starved arches significantly worse. > Making GCC output profiling call before prologue instead of after prologue > is a 4 liner in generic code and a few lines in target specific code. > The important thing is that we shouldn't have 100 different profiling ABIs, > so it is desirable to agree on something that will be generally useful not > just for the kernel, but perhaps for other purposes. > There is really just one that makes sense, which is providing the ABI-defined entry state, which means intercepting at the point of entry. Anything else is/was a mistake. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.