From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756153AbZJFDa4 (ORCPT ); Mon, 5 Oct 2009 23:30:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756139AbZJFDa4 (ORCPT ); Mon, 5 Oct 2009 23:30:56 -0400 Received: from wavehammer.waldi.eu.org ([82.139.201.20]:43429 "EHLO wavehammer.waldi.eu.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756133AbZJFDaz (ORCPT ); Mon, 5 Oct 2009 23:30:55 -0400 Date: Tue, 6 Oct 2009 05:30:50 +0200 From: Bastian Blank To: Jeremy Fitzhardinge Cc: Ingo Molnar , the arch/x86 maintainers , Stable Kernel , Linux Kernel Mailing List , Xen-devel Subject: Re: [Xen-devel] Re: [PATCH] xen: Disable stack protector for irq helper Message-ID: <20091006033050.GA6332@wavehammer.waldi.eu.org> Mail-Followup-To: Bastian Blank , Jeremy Fitzhardinge , Ingo Molnar , the arch/x86 maintainers , Stable Kernel , Linux Kernel Mailing List , Xen-devel References: <20091004183013.GA26101@wavehammer.waldi.eu.org> <4AC92A65.40806@goop.org> <20091005013517.GA6081@wavehammer.waldi.eu.org> <4ACA2AFD.4080305@goop.org> <20091005224310.GA32144@wavehammer.waldi.eu.org> <4ACA90F2.1060909@goop.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <4ACA90F2.1060909@goop.org> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 05, 2009 at 05:36:02PM -0700, Jeremy Fitzhardinge wrote: > On 10/05/09 15:43, Bastian Blank wrote: > > On Mon, Oct 05, 2009 at 10:21:01AM -0700, Jeremy Fitzhardinge wrote: > >>> Save all caller-saved registers on x86_32 for the paravirt callee saved > >>> registers. > >> That looks better, but it is still overkill. We only need to save the > >> set of registers the ABI requires the callee to preserve. What > >> additional register(s) gets clobbered by stack-protector that need to be > >> saved? > > Well, exactly the two, ecx and edx. eax is still clobbered by the return > > value. Anyway, it works in praxis. > I'm confused. It already saves ecx, so what else needs saving? The original version saves ecx, but not edx. Both are official caller-saved registers. > Besides, most of the code in that file isn't used unless you're using a > very old version of Xen; it will generally prefer to use the ones in > xen-asm_X.S. Well, my call stack say something different. It crashs during early startup without a console. The modifications to the function pointers is done much later. Bastian -- Vulcans never bluff. -- Spock, "The Doomsday Machine", stardate 4202.1