Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932415AbZIDQE2 (ORCPT ); Fri, 4 Sep 2009 12:04:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755355AbZIDQE1 (ORCPT ); Fri, 4 Sep 2009 12:04:27 -0400 Received: from claw.goop.org ([74.207.240.146]:35517 "EHLO claw.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753226AbZIDQE1 (ORCPT ); Fri, 4 Sep 2009 12:04:27 -0400 Message-ID: <4AA13A8C.2080709@goop.org> Date: Fri, 04 Sep 2009 09:04:28 -0700 From: Jeremy Fitzhardinge User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.1) Gecko/20090814 Fedora/3.0-2.6.b3.fc11 Lightning/1.0pre Thunderbird/3.0b3 MIME-Version: 1.0 To: Tejun Heo CC: "H. Peter Anvin" , mingo@redhat.com, linux-kernel@vger.kernel.org, jeremy.fitzhardinge@citrix.com, stable@kernel.org, tglx@linutronix.de, mingo@elte.hu, linux-tip-commits@vger.kernel.org Subject: Re: [tip:x86/asm] x86/i386: Make sure stack-protector segment base is cache aligned References: <4AA01893.6000507@goop.org> <4AA02687.9080406@zytor.com> <4AA02B02.7080101@goop.org> <4AA031DE.2070109@zytor.com> <4AA080A0.7010804@kernel.org> <4AA08283.5020306@kernel.org> <4AA08B09.50503@zytor.com> <4AA08DD3.5010509@kernel.org> <4AA08ED0.4050206@zytor.com> <4AA0A05B.5010806@kernel.org> In-Reply-To: <4AA0A05B.5010806@kernel.org> X-Enigmail-Version: 0.97a 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: 1391 Lines: 29 On 09/03/09 22:06, Tejun Heo wrote: >>> Heh... here's a naive and hopeful plan. How about we beg gcc >>> developers to allow different segment register and offset in newer gcc >>> versions and then use the same one when building with the new gcc? >>> This should solve the i386 problem too. It would be the best as we >>> get to keep the separate segment register from the userland. Too >>> hopeful? >>> >> I think it's possible to set the register in more recent gcc. Doing the >> sane thing and having a symbol for an offset is probably worse. >> > I was thinking about altering the build process so that we can use sed > to substitute %gs:40 with %fs:40 while compiling. If it's already > possible to override the register in more recent gcc, no need to go > into that horror. > Ideally we'd like to get rid of the constant offset too. If we could change it to %[fg]s:__gcc_stack_canary_offset on both 32-bit and 64-bit, it would give us a lot more flexibility. __gcc_stack_canary_offset could be weakly defined to 20/40 for backwards compatibility, but we could override it to point to a normal percpu variable. J -- 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/