Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759302Ab1FBIKJ (ORCPT ); Thu, 2 Jun 2011 04:10:09 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:53167 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757458Ab1FBIKF (ORCPT ); Thu, 2 Jun 2011 04:10:05 -0400 Date: Thu, 2 Jun 2011 10:09:37 +0200 From: Ingo Molnar To: Valdis.Kletnieks@vt.edu Cc: Andrew Lutomirski , 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 v3 10/10] x86-64: Add CONFIG_UNSAFE_VSYSCALLS to feature-removal-schedule Message-ID: <20110602080937.GA5722@elte.hu> References: <7e604b2dd699a30204fda3d1011f3af5a2c56572.1306847455.git.luto@mit.edu> <10442.1306949732@turing-police.cc.vt.edu> <13093.1306952865@turing-police.cc.vt.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <13093.1306952865@turing-police.cc.vt.edu> 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: 1323 Lines: 33 * Valdis.Kletnieks@vt.edu wrote: > On Wed, 01 Jun 2011 13:41:56 EDT, Andrew Lutomirski said: > > >> + ? ? ? ? On a system with recent enough glibc (probably 2.14 or > >> + ? ? ? ? newer) and no static binaries, you can say N without a > >> + ? ? ? ? performance penalty to improve security > >> > >> So I checked my laptop (Fedora 16 Rawhide), and found a bunch of static binaries. The ones > >> that look like people may care: > > > The binaries will still work -- they'll just take a small performance > > hit (~220ns on Sandy Bridge) every time they call time(). > > Ah. I misparsed the Kconfig help - I read it as "If you have no > static binaries, setting this to N doesn't introduce a performance > hit" (with an implied "if you have static binaries, this will hose > you"). Adding "Static binaries will continue to work at a very > small performance penalty" would probably help. Yeah, would be nice to add that clarification. (or better yet, reformulate it in a way that makes it really obvious from the get go.) 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/