From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sog-mx-2.v43.ch3.sourceforge.com ([172.29.43.192] helo=mx.sourceforge.net) by sfs-ml-3.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1QvM5f-0001EJ-Uo for user-mode-linux-devel@lists.sourceforge.net; Mon, 22 Aug 2011 04:26:23 +0000 Received: from zeniv.linux.org.uk ([195.92.253.2]) by sog-mx-2.v43.ch3.sourceforge.com with esmtps (TLSv1:AES256-SHA:256) (Exim 4.76) id 1QvM5e-0001Wl-Iu for user-mode-linux-devel@lists.sourceforge.net; Mon, 22 Aug 2011 04:26:23 +0000 Date: Mon, 22 Aug 2011 05:26:05 +0100 From: Al Viro Message-ID: <20110822042605.GR2203@ZenIV.linux.org.uk> References: <20110821063443.GH2203@ZenIV.linux.org.uk> <20110821084230.GI2203@ZenIV.linux.org.uk> <20110821144352.GJ2203@ZenIV.linux.org.uk> <20110821164124.GL2203@ZenIV.linux.org.uk> <20110822011645.GM2203@ZenIV.linux.org.uk> <20110822040759.GQ2203@ZenIV.linux.org.uk> <4E51D70A.1060001@zytor.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <4E51D70A.1060001@zytor.com> List-Id: The user-mode Linux development list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: user-mode-linux-devel-bounces@lists.sourceforge.net Subject: Re: [uml-devel] SYSCALL, ptrace and syscall restart breakages (Re: [RFC] weird crap with vdso on uml/i386) To: "H. Peter Anvin" Cc: Andrew Lutomirski , user-mode-linux-devel@lists.sourceforge.net, Richard Weinberger , linux-kernel@vger.kernel.org, mingo@redhat.com, Linus Torvalds On Sun, Aug 21, 2011 at 09:11:54PM -0700, H. Peter Anvin wrote: > > lack of point - the *only* CPU where it would matter would be K6-2, IIRC, > > and (again, IIRC) it had some differences in SYSCALL semantics compared to > > K7 (which supports SYSENTER as well). Bugger if I remember what those > > differences might've been... Some flag not cleared? > > The most likely reason for a binary to execute a stray SYSCALL is > because they read it out of the vdso. Totally daft, but we certainly > see a lot of stupid things as evidenced by the JIT thread earlier this > month. Um... What, blindly, no matter what surrounds it in there? What will happen to the same eager JIT when it steps on SYSENTER? ------------------------------------------------------------------------------ uberSVN's rich system and user administration capabilities and model configuration take the hassle out of deploying and managing Subversion and the tools developers use with it. Learn more about uberSVN and get a free download at: http://p.sf.net/sfu/wandisco-dev2dev _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751850Ab1HVE02 (ORCPT ); Mon, 22 Aug 2011 00:26:28 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:50671 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750837Ab1HVE0Y (ORCPT ); Mon, 22 Aug 2011 00:26:24 -0400 Date: Mon, 22 Aug 2011 05:26:05 +0100 From: Al Viro To: "H. Peter Anvin" Cc: Linus Torvalds , Andrew Lutomirski , mingo@redhat.com, Richard Weinberger , user-mode-linux-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: SYSCALL, ptrace and syscall restart breakages (Re: [RFC] weird crap with vdso on uml/i386) Message-ID: <20110822042605.GR2203@ZenIV.linux.org.uk> References: <20110821063443.GH2203@ZenIV.linux.org.uk> <20110821084230.GI2203@ZenIV.linux.org.uk> <20110821144352.GJ2203@ZenIV.linux.org.uk> <20110821164124.GL2203@ZenIV.linux.org.uk> <20110822011645.GM2203@ZenIV.linux.org.uk> <20110822040759.GQ2203@ZenIV.linux.org.uk> <4E51D70A.1060001@zytor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4E51D70A.1060001@zytor.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Aug 21, 2011 at 09:11:54PM -0700, H. Peter Anvin wrote: > > lack of point - the *only* CPU where it would matter would be K6-2, IIRC, > > and (again, IIRC) it had some differences in SYSCALL semantics compared to > > K7 (which supports SYSENTER as well). Bugger if I remember what those > > differences might've been... Some flag not cleared? > > The most likely reason for a binary to execute a stray SYSCALL is > because they read it out of the vdso. Totally daft, but we certainly > see a lot of stupid things as evidenced by the JIT thread earlier this > month. Um... What, blindly, no matter what surrounds it in there? What will happen to the same eager JIT when it steps on SYSENTER?