Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752254AbZGSHWQ (ORCPT ); Sun, 19 Jul 2009 03:22:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751555AbZGSHWO (ORCPT ); Sun, 19 Jul 2009 03:22:14 -0400 Received: from one.firstfloor.org ([213.235.205.2]:51168 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751514AbZGSHWO (ORCPT ); Sun, 19 Jul 2009 03:22:14 -0400 Date: Sun, 19 Jul 2009 09:22:10 +0200 From: Andi Kleen To: john stultz Cc: Andi Kleen , Ingo Molnar , Thomas Gleixner , lkml Subject: Re: Duplicate vsyscall/vdso gettimeofday implementations on x86_64 Message-ID: <20090719072210.GA3981@basil.fritz.box> References: <1247868130.8334.40.camel@localhost.localdomain> <87eisfvtzv.fsf@basil.nowhere.org> <1247871284.8334.42.camel@localhost.localdomain> <87ab32wmkv.fsf@basil.nowhere.org> <1247954594.14494.12.camel@work-vm> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1247954594.14494.12.camel@work-vm> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1225 Lines: 36 > Ok. Ulrich mailed me with the same points earlier and here's what I > said: Hopefully he can fix the terrible vsyscall code in glibc too. > 1) Keep the old vsyscall gtod implementation as is, despite it > duplicating things. Maybe avoid the code duplication via inlined > functions. > > 2) Set the old vsyscall gtod to directly call the syscall. There were some more like 3) Call from old vsyscall into new vDSO code. This needs to store the randomized mapping address somewhere though. Most options required a another page for each process. And a couple of other variants. > Neither of these help to avoid the non-randomized syscall instruction. They used to be patched away to nops when not needed, unfortunately that code was removed at some point. Perhaps that should be readded. Most systems actually don't need them (only those that need pmtimer) so you don't have a static syscall entry point on them. -Andi -- ak@linux.intel.com -- Speaking for myself only. -- 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/