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 1Qv9NP-0003jJ-Nv for user-mode-linux-devel@lists.sourceforge.net; Sun, 21 Aug 2011 14:51:51 +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 1Qv9NO-00056X-FS for user-mode-linux-devel@lists.sourceforge.net; Sun, 21 Aug 2011 14:51:51 +0000 Date: Sun, 21 Aug 2011 15:51:26 +0100 From: Al Viro Message-ID: <20110821145126.GK2203@ZenIV.linux.org.uk> References: <20110820011845.GC2203@ZenIV.linux.org.uk> <4E4FD12F.70508@nod.at> <20110820201406.GF2203@ZenIV.linux.org.uk> <4E501F51.9060905@nod.at> <20110821063443.GH2203@ZenIV.linux.org.uk> <20110821084230.GI2203@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: 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: Andrew Lutomirski Cc: user-mode-linux-devel@lists.sourceforge.net, Richard Weinberger , linux-kernel@vger.kernel.org, mingo@redhat.com, "H. Peter Anvin" , Linus Torvalds On Sun, Aug 21, 2011 at 09:37:18AM -0400, Andrew Lutomirski wrote: > Gack. Is this a holdover from the 32-bit code that shares the > argument save area with the parameters passed on the C stack? If so, > we could just set up the argument save area honestly and pass the real > parameters in registers like 64-bit C code expects. > > If the tracing and restart cases use iret to return to userspace, this > should all just work. ptrace users shouldn't notice the overhead, and > syscall restart is presumably slow enough anyway that it wouldn't > matter. The userspace entry code would be as simple as: > > sysenter > ret > > or > > sysexit > ret You are making no sense at all... ------------------------------------------------------------------------------ Get a FREE DOWNLOAD! and learn more about uberSVN rich system, user administration capabilities and model configuration. Take the hassle out of deploying and managing Subversion and the tools developers use with it. http://p.sf.net/sfu/wandisco-d2d-2 _______________________________________________ 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 S1755524Ab1HUOvx (ORCPT ); Sun, 21 Aug 2011 10:51:53 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:34778 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754867Ab1HUOvw (ORCPT ); Sun, 21 Aug 2011 10:51:52 -0400 Date: Sun, 21 Aug 2011 15:51:26 +0100 From: Al Viro To: Andrew Lutomirski Cc: Linus Torvalds , "H. Peter Anvin" , 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: <20110821145126.GK2203@ZenIV.linux.org.uk> References: <20110820011845.GC2203@ZenIV.linux.org.uk> <4E4FD12F.70508@nod.at> <20110820201406.GF2203@ZenIV.linux.org.uk> <4E501F51.9060905@nod.at> <20110821063443.GH2203@ZenIV.linux.org.uk> <20110821084230.GI2203@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 09:37:18AM -0400, Andrew Lutomirski wrote: > Gack. Is this a holdover from the 32-bit code that shares the > argument save area with the parameters passed on the C stack? If so, > we could just set up the argument save area honestly and pass the real > parameters in registers like 64-bit C code expects. > > If the tracing and restart cases use iret to return to userspace, this > should all just work. ptrace users shouldn't notice the overhead, and > syscall restart is presumably slow enough anyway that it wouldn't > matter. The userspace entry code would be as simple as: > > sysenter > ret > > or > > sysexit > ret You are making no sense at all...