Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934975AbZKYUQx (ORCPT ); Wed, 25 Nov 2009 15:16:53 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932338AbZKYUQw (ORCPT ); Wed, 25 Nov 2009 15:16:52 -0500 Received: from terminus.zytor.com ([198.137.202.10]:51046 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932331AbZKYUQw (ORCPT ); Wed, 25 Nov 2009 15:16:52 -0500 Message-ID: <4B0D8FC1.1010608@zytor.com> Date: Wed, 25 Nov 2009 12:12:49 -0800 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 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1234 Lines: 29 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. -- 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/