Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752670AbZJZQhd (ORCPT ); Mon, 26 Oct 2009 12:37:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751553AbZJZQhc (ORCPT ); Mon, 26 Oct 2009 12:37:32 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:54062 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751499AbZJZQhc (ORCPT ); Mon, 26 Oct 2009 12:37:32 -0400 Date: Mon, 26 Oct 2009 09:37:06 -0700 From: Andrew Morton To: Chuck Ebbert Cc: Dave Jones , Linux Kernel , Ingo Molnar , Thomas Gleixner , esandeen@redhat.com Subject: Re: Unnecessary overhead with stack protector. Message-Id: <20091026093706.c6416715.akpm@linux-foundation.org> In-Reply-To: <20091026123004.297a0a25@katamari.usersys.redhat.com> References: <20091015183540.GA8098@redhat.com> <20091021182636.63edbf72.akpm@linux-foundation.org> <20091026123004.297a0a25@katamari.usersys.redhat.com> X-Mailer: Sylpheed 2.4.8 (GTK+ 2.12.5; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1960 Lines: 46 On Mon, 26 Oct 2009 12:30:04 -0400 Chuck Ebbert wrote: > On Wed, 21 Oct 2009 18:26:36 -0700 > Andrew Morton wrote: > > > On Thu, 15 Oct 2009 14:35:41 -0400 Dave Jones wrote: > > > > > 113c5413cf9051cc50b88befdc42e3402bb92115 introduced a change that > > > made CC_STACKPROTECTOR_ALL not-selectable if someone enables CC_STACKPROTECTOR. > > > > > > We've noticed in Fedora that this has introduced noticable overhead on > > > some functions, including those which don't even have any on-stack variables. > > > > > > According to the gcc manpage, -fstack-protector will protect functions with > > > as little as 8 bytes of stack usage. So we're introducing a huge amount > > > of overhead, to close a small amount of vulnerability (the >0 && <8 case). > > > > > > The overhead as it stands right now means this whole option is unusable for > > > a distro kernel without reverting the above commit. > > > > > > > This looks like a fairly serious problem to me, but I'm confused by the > > commit ID. February 2008 - is this correct? > > > > That date is pure fiction AFAICT. And the Mercurial kernel repo says May 2008... > Is there some way to get the date a change was merged into the official tree as > opposed to the date it was created in some other tree? oh, so someone _did_ read my email! git show --pretty=fuller 113c5413cf9051cc50b88befdc42e3402bb92115 commit 113c5413cf9051cc50b88befdc42e3402bb92115 Author: Ingo Molnar AuthorDate: Thu Feb 14 10:36:03 2008 +0100 Commit: Thomas Gleixner CommitDate: Mon May 26 16:15:32 2008 +0200 I think the CommitDate is when it hit mainline. -- 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/