Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756454AbZICV0E (ORCPT ); Thu, 3 Sep 2009 17:26:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932321AbZICV0B (ORCPT ); Thu, 3 Sep 2009 17:26:01 -0400 Received: from terminus.zytor.com ([198.137.202.10]:50853 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932291AbZICV0A (ORCPT ); Thu, 3 Sep 2009 17:26:00 -0400 Message-ID: <4AA0334F.5020004@zytor.com> Date: Thu, 03 Sep 2009 14:21:19 -0700 From: "H. Peter Anvin" 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 Thunderbird/3.0b3 MIME-Version: 1.0 To: Ingo Molnar CC: Jeremy Fitzhardinge , mingo@redhat.com, linux-kernel@vger.kernel.org, jeremy.fitzhardinge@citrix.com, stable@kernel.org, tglx@linutronix.de, linux-tip-commits@vger.kernel.org, Tejun Heo , Arjan van de Ven 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> <20090903211805.GB12566@elte.hu> In-Reply-To: <20090903211805.GB12566@elte.hu> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1160 Lines: 31 On 09/03/2009 02:18 PM, Ingo Molnar wrote: > > * H. Peter Anvin wrote: > >> On 09/03/2009 01:45 PM, Jeremy Fitzhardinge wrote: >>> >>> Two problems: >>> >>> * gcc generates %gs: references for stack-protector, but we use %fs >>> for percpu data (because restoring %fs is faster if it's a null >>> selector; TLS uses %gs). I guess we could use %fs if >>> !CONFIG_CC_STACKPROTECTOR, or %gs if we are using it (though that >>> has some fiddly ramifications for things like ptrace). >> >> Well, by touching two segments we're getting the worst of both >> worlds, so at least assuming some significant number of real-world >> deployments use CC_STACKPROTECTOR, we really don't want to >> pessimize that case too much. > > Fedora has stackprotector enabled so it's used in a widespread way. > > Ingo I'm guessing most distros do, except perhaps embedded ones. -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/