Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754695AbZKSVOW (ORCPT ); Thu, 19 Nov 2009 16:14:22 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753298AbZKSVOW (ORCPT ); Thu, 19 Nov 2009 16:14:22 -0500 Received: from mx1.redhat.com ([209.132.183.28]:16252 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752752AbZKSVOV (ORCPT ); Thu, 19 Nov 2009 16:14:21 -0500 Message-ID: <4B05B4B5.2000102@redhat.com> Date: Thu, 19 Nov 2009 14:12:21 -0700 From: Jeff Law User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.4pre) Gecko/20091014 Fedora/3.0-2.8.b4.fc11 Thunderbird/3.0b4 MIME-Version: 1.0 To: Linus Torvalds CC: "H. Peter Anvin" , rostedt@goodmis.org, David Daney , Andrew Haley , Richard Guenther , Thomas Gleixner , Ingo Molnar , LKML , Andrew Morton , Heiko Carstens , feng.tang@intel.com, Fr??d??ric Weisbecker , Peter Zijlstra , jakub@redhat.com, gcc@gcc.gnu.org Subject: Re: BUG: GCC-4.4.x changes the function frame on some functions References: <20091119072040.GA23579@elte.hu> <1258653562.22249.682.camel@gandalf.stny.rr.com> <84fc9c000911191003t244eb864o3d5b355ab5485f@mail.gmail.com> <4B058CCD.8050605@redhat.com> <4B05982B.6060200@caviumnetworks.com> <1258658886.22249.874.camel@gandalf.stny.rr.com> <4B05A16D.1050807@zytor.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1289 Lines: 32 On 11/19/09 13:06, Linus Torvalds wrote: > > On Thu, 19 Nov 2009, H. Peter Anvin wrote: > >> Calling the profiler immediately at the entry point is clearly the more >> sane option. It means the ABI is well-defined, stable, and independent >> of what the actual function contents are. It means that ABI isn't the >> normal C ABI (the __fentry__ function would have to preserve all >> registers), but that's fine... >> > As far as I know, that's true of _mcount already: it's not a normal ABI > and is rather a highly architecture-specific special case to begin with. > At least ARM has some (several?) special mcount calling conventions, > afaik. > Correct. _mcount's ABI typically has been defined by the implementation of the vendor's C library mcount. GCC has options to emit the profiling code prior to or after the prologue controllable through the usual variety of target macros & hooks. I can't imagine anyone would object to a clean, tested patch to change how x86-linux's profiling code was implemented. jeff -- 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/