From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751477AbXCGPFX (ORCPT ); Wed, 7 Mar 2007 10:05:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751048AbXCGPFX (ORCPT ); Wed, 7 Mar 2007 10:05:23 -0500 Received: from pentafluge.infradead.org ([213.146.154.40]:54529 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751090AbXCGPFW (ORCPT ); Wed, 7 Mar 2007 10:05:22 -0500 Subject: Re: Wanted: simple, safe x86 stack overflow detection From: Arjan van de Ven To: Bill Irwin Cc: Hugh Dickins , Chuck Ebbert , Andi Kleen , linux-kernel In-Reply-To: <20070307144816.GQ18774@holomorphy.com> References: <45E5913D.3080505@redhat.com> <20070228204144.GA32316@one.firstfloor.org> <20070304015031.GA4224@holomorphy.com> <45EDBA1B.8050007@redhat.com> <20070306203432.GD18774@holomorphy.com> <1173241715.3236.16.camel@laptopd505.fenrus.org> <20070307064423.GH18774@holomorphy.com> <1173270892.3176.4.camel@laptopd505.fenrus.org> <20070307144816.GQ18774@holomorphy.com> Content-Type: text/plain Organization: Intel International BV Date: Wed, 07 Mar 2007 07:04:23 -0800 Message-Id: <1173279863.3540.2.camel@laptopd505.fenrus.org> Mime-Version: 1.0 X-Mailer: Evolution 2.8.3 (2.8.3-1.fc6) Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > > just removing the if() and the explicit IRQ enabling already makes irqs no longer nest... > > I can see why that would raise eyebrows. I can see getting bashed > mercilessly with interrupt latency concerns as a result here. Can you > suggest any defenses? hardirq handlers are supposed to be fast. If they're slow the code should (and generally is) using bottom halves/tasklets/softirqs. Combine this with the fact that each new irq handler will start with a bunch of cache misses, the latency added isn't generally that significant. In addition, the cache miss thing makes the nesting suck a lot, it's faster to batch the irqs in sequence. -- if you want to mail me at work (you don't), use arjan (at) linux.intel.com Test the interaction between Linux and your BIOS via http://www.linuxfirmwarekit.org