From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933320AbXCFTnj (ORCPT ); Tue, 6 Mar 2007 14:43:39 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933299AbXCFTnj (ORCPT ); Tue, 6 Mar 2007 14:43:39 -0500 Received: from extu-mxob-2.symantec.com ([216.10.194.135]:10186 "EHLO extu-mxob-2.symantec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933315AbXCFTni (ORCPT ); Tue, 6 Mar 2007 14:43:38 -0500 X-AuditID: d80ac287-9ff9dbb000002978-0f-45edc4693e55 Date: Tue, 6 Mar 2007 19:43:41 +0000 (GMT) From: Hugh Dickins X-X-Sender: hugh@blonde.wat.veritas.com To: Chuck Ebbert cc: Bill Irwin , Andi Kleen , linux-kernel Subject: Re: Wanted: simple, safe x86 stack overflow detection In-Reply-To: <45EDBA1B.8050007@redhat.com> Message-ID: References: <45E5913D.3080505@redhat.com> <20070228204144.GA32316@one.firstfloor.org> <20070304015031.GA4224@holomorphy.com> <45EDBA1B.8050007@redhat.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-OriginalArrivalTime: 06 Mar 2007 19:43:37.0613 (UTC) FILETIME=[BBEBC3D0:01C76027] X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 6 Mar 2007, Chuck Ebbert wrote: > > In the 4k/4k stack i386 kernel, is there any fundamental reason it > can't be 4k/8k? We seem to be mostly hitting problems in overflowing > the IRQ stack... I think. Overhead would only be 4k per CPU for that. For all of history prior to 2.6.20, there's been the fundamental reason that even interrupt stacks need to access current_thread_info, and that involved the (THREAD_SIZE - 1) mask. But 2.6.20's read_pda using %gs gets away from that: my guess is that it's now possible for i386 to use different sized stacks. Hugh