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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 BF65FC47085 for ; Tue, 25 May 2021 18:00:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9B168613CC for ; Tue, 25 May 2021 18:00:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233644AbhEYSBt (ORCPT ); Tue, 25 May 2021 14:01:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38982 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234235AbhEYSBo (ORCPT ); Tue, 25 May 2021 14:01:44 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DB4CAC061574; Tue, 25 May 2021 11:00:14 -0700 (PDT) From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1621965612; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=wKSV89E/6EiSVlVjhoAd4jt3GiLGZVtIU+F/LgVrtdw=; b=vVkGgQH93Lgt5QEtsQIHjDUQ1vPUsDVdoNFy39FEgMj33Q4sFUBoqe97mj99aNdhtTGkrc 6tH4hij+q/wLno+L4QRxYk4LmY80pEmSpDcQXlnLEvlyB5Om6QJHQOhfEdAehXlvBPgVFi y17B6cX9U/Qf2EmRPwWpy9/zwNMEZHN9kbL9nfoF24+6FQLp1rncyyddO4ZREVoqgtk72Z R6eH+a1mZQ1J/kmvbrMJhiTvDtVLFpDY2BSTkV8pXfcqqh/arcXG6CiZgx2/vw3WyDlpph bXPjiAHk2MzKaNGftDa5CCXUpadsYtbrFeAjhHnB8h5ZOcrNAIj7cREHagmCnA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1621965612; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=wKSV89E/6EiSVlVjhoAd4jt3GiLGZVtIU+F/LgVrtdw=; b=P1g/A7Xb52/fy6IIW7+cCIlHncl/zsJqew/anHCMWH4DwSzRtdBTwsDY442pE0M161GOeS hVww1RpWfD3W49BQ== To: "Yu\, Yu-cheng" , Andy Lutomirski , LKML Cc: linux-tip-commits@vger.kernel.org, Fenghua Yu , Borislav Petkov , Dave Hansen , Tony Luck , x86 , "Shankar\, Ravi V" Subject: Re: [tip: x86/fpu] x86/fpu/xstate: Define new functions for clearing fpregs and xstates In-Reply-To: <10a553a5-699f-6921-705e-9afa1a8e42de@intel.com> References: <20200512145444.15483-6-yu-cheng.yu@intel.com> <158964181793.17951.15480349640697746223.tip-bot2@tip-bot2> <10a553a5-699f-6921-705e-9afa1a8e42de@intel.com> Date: Tue, 25 May 2021 20:00:12 +0200 Message-ID: <87y2c28zir.ffs@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 25 2021 at 10:44, Yu-cheng Yu wrote: > On 5/24/2021 9:34 AM, Andy Lutomirski wrote: >> So I'm guessing that syzbot may have misattributed the problem. But >> we definitely need to clean up the XRSTOR #GP handling before CET >> lands. >> > From the crash dump, the system is doing syscall_exit_to_user_mode() > for __x64_sys_futex(). The futex syscall does not seem to modify > xstates, Of course does the futex syscall not modify anything, but the task can schedule out before returning from the syscall so it has to restore the FPU state. > but upon returning to user mode, XRSTORS gets a GP. Can this > be some memory corruption? fpu__clear() is merely helping to clear the > mess and seems to be innocent. What kind of analysis is that? Thanks, tglx