From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B3A6FC433DB for ; Fri, 29 Jan 2021 17:02:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 802D160234 for ; Fri, 29 Jan 2021 17:02:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231849AbhA2RCw (ORCPT ); Fri, 29 Jan 2021 12:02:52 -0500 Received: from mx2.suse.de ([195.135.220.15]:47082 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231915AbhA2RAg (ORCPT ); Fri, 29 Jan 2021 12:00:36 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 7A127ACB7; Fri, 29 Jan 2021 16:59:55 +0000 (UTC) Subject: Re: [PATCH v2] x86/debug: Fix DR6 handling To: Borislav Petkov , Peter Zijlstra Cc: x86@kernel.org, linux-kernel@vger.kernel.org, andrew.cooper3@citrix.com, Frederic Weisbecker References: <20210128211627.GB4348@worktop.programming.kicks-ass.net> <20210129144816.GB27841@zn.tnic> From: Tom de Vries Message-ID: <50670b90-6d53-8c65-b3c8-e76fc9e2a1d3@suse.de> Date: Fri, 29 Jan 2021 17:59:54 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: <20210129144816.GB27841@zn.tnic> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/29/21 3:48 PM, Borislav Petkov wrote: > On Thu, Jan 28, 2021 at 10:16:27PM +0100, Peter Zijlstra wrote: >> >> Tom reported that one of the GDB test-cases failed, and Boris bisected >> it to commit: >> >> d53d9bc0cf78 ("x86/debug: Change thread.debugreg6 to thread.virtual_dr6") >> >> The debugging session led us to commit: >> >> 6c0aca288e72 ("x86: Ignore trap bits on single step exceptions") >> >> It turns out that TF and data breakpoints are both traps and will be >> merged, while instruction breakpoints are faults and will not be >> merged. This means 6c0aca288e72 is wrong, we only need to exclude TF >> and instruction breakpoints while we can merge TF and data >> breakpoints. >> >> Fixes: d53d9bc0cf78 ("x86/debug: Change thread.debugreg6 to thread.virtual_dr6") >> Fixes: 6c0aca288e72 ("x86: Ignore trap bits on single step exceptions") >> Reported-by: Tom de Vries >> Bisected-by: Borislav Petkov >> Signed-off-by: Peter Zijlstra (Intel) > > I guess > > Cc: > > Also, > > Reviewed-by: Borislav Petkov > > And gdb testsuite is a bit happier: > > --- before > +++ after > === gdb Summary === > > -# of expected passes 70822 > -# of unexpected failures 899 > +# of expected passes 70852 > +# of unexpected failures 869 > # of expected failures 74 > # of known failures 99 > # of untested testcases 114 > > You just fixed 30(!) testcases. > > :-) > Hi Boris, thanks for testing this, and just to confirm: the total number of regressions I see in the gdb testsuite related to watchpoints is indeed 30. Thanks, - Tom