Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758956AbYGBAYU (ORCPT ); Tue, 1 Jul 2008 20:24:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756102AbYGBAYE (ORCPT ); Tue, 1 Jul 2008 20:24:04 -0400 Received: from terminus.zytor.com ([198.137.202.10]:43148 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755851AbYGBAYD (ORCPT ); Tue, 1 Jul 2008 20:24:03 -0400 Message-ID: <486AC9D9.9030506@zytor.com> Date: Tue, 01 Jul 2008 17:20:41 -0700 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.14 (X11/20080501) MIME-Version: 1.0 To: Jeremy Fitzhardinge CC: "Eric W. Biederman" , Mike Travis , Christoph Lameter , Linux Kernel Mailing List Subject: Re: [crash, bisected] Re: [PATCH 3/4] x86_64: Fold pda into per cpu area References: <20080604003018.538497000@polaris-admin.engr.sgi.com> <485ACD92.8050109@sgi.com> <485AD138.4010404@goop.org> <485ADA12.5010505@sgi.com> <485ADC73.60009@goop.org> <485BDB04.4090709@sgi.com> <485BE80E.10209@goop.org> <485BF8F5.6010802@goop.org> <485BFFC5.6020404@sgi.com> <486912C4.8070705@sgi.com> <48691556.2080208@zytor.com> <48691E8B.4040605@sgi.com> <48694B3B.3010600@goop.org> <486A61A7.1000902@zytor.com> <486A68DD.80702@goop.org> <486A9D4F.8010508@goop.org> <486AA72B.6010401@goop.org> In-Reply-To: <486AA72B.6010401@goop.org> 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: 1013 Lines: 25 Jeremy Fitzhardinge wrote: > > Yes, and there's no reason we couldn't do the same on 64-bit, aside from > the stack-protector's use of %gs:40. There's no code-size cost in large > offsets, since they're always 32-bits anyway (there's no short absolute > addressing mode). > > If we manually generate %gs-relative references to percpu data, then > it's no different to what we do with 32-bit, whether it be a specific > symbol address or using the TLS relocations. > If we think the problem is the zero-basing triggering linker bugs, we should probably just use a small offset, like 64 (put a small dummy section before the .percpu.data section to occupy this section.) I'm going to play with this a bit and see if I come up with something sanish. -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/