Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932146Ab1EaQnb (ORCPT ); Tue, 31 May 2011 12:43:31 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:34271 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752827Ab1EaQna (ORCPT ); Tue, 31 May 2011 12:43:30 -0400 Date: Tue, 31 May 2011 18:43:16 +0200 From: Ingo Molnar To: Andrew Lutomirski Cc: x86@kernel.org, Thomas Gleixner , linux-kernel@vger.kernel.org, Jesper Juhl , Borislav Petkov , Linus Torvalds , Andrew Morton , Arjan van de Ven , Jan Beulich , richard -rw- weinberger , Mikael Pettersson , Andi Kleen Subject: Re: [PATCH v4 09/10] x86-64: Randomize int 0xcc magic al values at boot Message-ID: <20110531164316.GB15651@elte.hu> References: <75a00aee647302e22c86a5c5fac0478b9776481a.1306851090.git.luto@mit.edu> <20110531154012.GB30353@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.3.1 -2.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1132 Lines: 30 * Andrew Lutomirski wrote: > On Tue, May 31, 2011 at 11:56 AM, Andrew Lutomirski wrote: > > We could scrap int 0xcc entirely and emulate on page fault, but that > > is slower and has other problems (like breaking anything that thinks > > it can look at a call target in a binary and dereference that > > address). > > > > Here's a possibly dumb/evil idea: > > > > Put real syscalls in the vsyscall page but mark the page NX. ?Then > > emulate the vsyscalls on the PF_INSTR fault when userspace jumps to > > the correct address but send SIGSEGV for the wrong address. > > > > Down side: it's even more complexity for the same silly case. > > Scratch that. It's incompatible with keeping time() fast for now. If we can find another fault than #PF then it will be similarly fast to an INT $0xCC so please at least investigate this route. Thanks, Ingo -- 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/