Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757679AbYCEUsd (ORCPT ); Wed, 5 Mar 2008 15:48:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753123AbYCEUsZ (ORCPT ); Wed, 5 Mar 2008 15:48:25 -0500 Received: from terminus.zytor.com ([198.137.202.10]:57539 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752380AbYCEUsZ (ORCPT ); Wed, 5 Mar 2008 15:48:25 -0500 Message-ID: <47CF0627.2070200@zytor.com> Date: Wed, 05 Mar 2008 12:44:23 -0800 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.12 (X11/20080226) MIME-Version: 1.0 To: Michael Matz CC: Aurelien Jarno , Joe Buck , linux-kernel@vger.kernel.org, gcc@gcc.gnu.org Subject: Re: Linux doesn't follow x86/x86-64 ABI wrt direction flag References: <20080305153020.GA24631@volta.aurel32.net> <47CEC3AA.6080709@zytor.com> <20080305195834.GA17267@synopsys.com> <20080305202319.GA17053@volta.aurel32.net> 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: 1241 Lines: 31 Michael Matz wrote: > Hi, > > On Wed, 5 Mar 2008, Aurelien Jarno wrote: > >>> So I think gcc at least needs an *option* to revert to the old behavior, >>> and there's a good argument to make it the default for now, at least for >>> x86/x86-64 on Linux. >> And for other kernels. I tested OpenBSD 4.1, FreeBSD 6.3, NetBSD 4.0, >> they have the same behaviour as Linux, that is they don't clear DF >> before calling the signal handler. > > Sigh. We could perhaps insert a cld for all functions which can be > recognized as possible signal handlers and call other unknown or string > functions. But it's probably even faster to emit cld in front of the > inline copies of mem functions again :-( > Well, there is a (slight) difference: you know that a called function will not clobber your DF state; it's only the entry condition which is imprecise. The best would be if this could be controlled by a flag, which we can flip once kernel fixes has been around for long enough. -hpa -- 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/