From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 118028 invoked by alias); 11 May 2018 17:14:24 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 118008 invoked by uid 89); 11 May 2018 17:14:24 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.0 required=5.0 tests=AWL,BAYES_00,KAM_LAZY_DOMAIN_SECURITY,SPF_HELO_PASS autolearn=no version=3.3.2 spammy= X-HELO: mx1.redhat.com Received: from mx3-rdu2.redhat.com (HELO mx1.redhat.com) (66.187.233.73) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Fri, 11 May 2018 17:14:23 +0000 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E11FCEC016; Fri, 11 May 2018 17:14:21 +0000 (UTC) Received: from [127.0.0.1] (ovpn04.gateway.prod.ext.ams2.redhat.com [10.39.146.4]) by smtp.corp.redhat.com (Postfix) with ESMTP id 385BC2026DEF; Fri, 11 May 2018 17:14:21 +0000 (UTC) Subject: Re: [PATCH] gdb/x86: Fix write out of mxcsr register for xsave targets To: Andrew Burgess , gdb-patches@sourceware.org References: <20180511115228.22098-1-andrew.burgess@embecosm.com> From: Pedro Alves Message-ID: Date: Fri, 11 May 2018 18:26:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <20180511115228.22098-1-andrew.burgess@embecosm.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-SW-Source: 2018-05/txt/msg00307.txt.bz2 On 05/11/2018 12:52 PM, Andrew Burgess wrote: > In commit: > > commit 8ee22052f690c007556b97eed59f49350ece5ca9 > Author: Andrew Burgess > Date: Thu May 3 17:46:14 2018 +0100 > > gdb/x86: Handle kernels using compact xsave format > > in two places FXSAVE_ADDR was used instead of FXSAVE_MXCSR_ADDR to get > the address of the mxcsr register within the xsave buffer. This will > mean we are potentially accessing the wrong location within the xsave > buffer. > > There are no tests included with this patch. The first mistake would > only trigger an issue if/when the user tries to manually set the mxcsr > register to a value that matches the random (value off stack) value > that is in the xsave buffer, in this case the change by the user will > go unnoticed by GDB, and the default value of mxcsr will be preserved. > > The second mistake only happens on the code path where all x87 > registers are being written out of the register cache. I'm not sure > how to trigger that code path. > OK as is. How did you notice this? Valgrind? Thanks, Pedro Alves