From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932110AbWGaJBK (ORCPT ); Mon, 31 Jul 2006 05:01:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932129AbWGaJBJ (ORCPT ); Mon, 31 Jul 2006 05:01:09 -0400 Received: from ns.suse.de ([195.135.220.2]:26325 "EHLO mx1.suse.de") by vger.kernel.org with ESMTP id S932110AbWGaJBI (ORCPT ); Mon, 31 Jul 2006 05:01:08 -0400 From: Andi Kleen To: Chuck Ebbert <76306.1226@compuserve.com> Subject: Re: [patch] x86_64: fix is_at_popf() for compat tasks Date: Mon, 31 Jul 2006 10:54:38 +0200 User-Agent: KMail/1.9.3 Cc: Albert Cahalan , linux-kernel References: <200607310325_MC3-1-C691-D76B@compuserve.com> In-Reply-To: <200607310325_MC3-1-C691-D76B@compuserve.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200607311054.38585.ak@suse.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Monday 31 July 2006 09:22, Chuck Ebbert wrote: > When testing for the REX instruction prefix, first check > for a 32-bit task because in compat mode the REX prefix is an > increment instruction. is_compat_task doesn't actually say that a task is in compat mode (it refers to the Linux compat layer, not x86-64 compat mode) A better test would be regs->cs == __USER32_CS, but in theory there could be other code segments in LDT. I guess that can be ignored though. -Andi