From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758165AbYDURmw (ORCPT ); Mon, 21 Apr 2008 13:42:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753961AbYDURmo (ORCPT ); Mon, 21 Apr 2008 13:42:44 -0400 Received: from tomts20-srv.bellnexxia.net ([209.226.175.74]:48553 "EHLO tomts20-srv.bellnexxia.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753830AbYDURmn (ORCPT ); Mon, 21 Apr 2008 13:42:43 -0400 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AsAFAD9vDEhMROPA/2dsb2JhbACBUalE Date: Mon, 21 Apr 2008 13:42:39 -0400 From: Mathieu Desnoyers To: "H. Peter Anvin" Cc: Pavel Machek , mingo@elte.hu, akpm@osdl.org, Jeremy Fitzhardinge , Steven Rostedt , "Frank Ch. Eigler" , linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH] x86 NMI-safe INT3 and Page Fault (v5) Message-ID: <20080421174239.GA14718@Krystal> References: <20080417165839.GA25198@Krystal> <20080417165944.GB25198@Krystal> <20080417201410.GB31616@Krystal> <20080421140054.GB4685@ucw.cz> <480CA337.3090709@zytor.com> <20080421150825.GA4070@Krystal> <480CADD3.3010209@zytor.com> <20080421154756.GA2424@Krystal> <20080421172327.GA32278@elf.ucw.cz> <480CCEB0.8040401@zytor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: <480CCEB0.8040401@zytor.com> X-Editor: vi X-Info: http://krystal.dyndns.org:8080 X-Operating-System: Linux/2.6.21.3-grsec (i686) X-Uptime: 13:40:31 up 52 days, 13:51, 4 users, load average: 0.34, 0.48, 0.52 User-Agent: Mutt/1.5.16 (2007-06-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * H. Peter Anvin (hpa@zytor.com) wrote: > Pavel Machek wrote: >>> There is also the page fault case. I think putting this test in >>> ret_from_exception would be both safe (it is executed for any >>> exception return) and fast (exceptions are rare). >> Eh? I thought that page fault is one of the hottest paths in kernel >> (along with syscall and packet receive/send)... >> Pavel > On x86_64, we can pinpoint only the page faults returning to the kernel, which are rare and only caused by vmalloc accesses. Ideally we could do the same on x86_32. > Yeah, and the concept of handling page faults inside an NMI handler is pure > fantasy. > > -hpa > -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68