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=-11.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 D544FC433E0 for ; Tue, 19 May 2020 19:59:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A95A820872 for ; Tue, 19 May 2020 19:59:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728542AbgEST7l (ORCPT ); Tue, 19 May 2020 15:59:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52140 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728384AbgEST7K (ORCPT ); Tue, 19 May 2020 15:59:10 -0400 Received: from Galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 68AFFC08C5C2; Tue, 19 May 2020 12:59:10 -0700 (PDT) Received: from [5.158.153.53] (helo=tip-bot2.lab.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1jb8OH-0000HV-5t; Tue, 19 May 2020 21:59:05 +0200 Received: from [127.0.1.1] (localhost [IPv6:::1]) by tip-bot2.lab.linutronix.de (Postfix) with ESMTP id 3D9E81C047E; Tue, 19 May 2020 21:58:50 +0200 (CEST) Date: Tue, 19 May 2020 19:58:50 -0000 From: "tip-bot2 for Peter Zijlstra" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/entry] x86/doublefault: Remove memmove() call Cc: Borislav Petkov , "Peter Zijlstra (Intel)" , Thomas Gleixner , Alexandre Chartre , Andy Lutomirski , x86 , LKML In-Reply-To: <20200505134058.863038566@linutronix.de> References: <20200505134058.863038566@linutronix.de> MIME-Version: 1.0 Message-ID: <158991833013.17951.13456353153440993898.tip-bot2@tip-bot2> X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the x86/entry branch of tip: Commit-ID: f44e70325748c7998cf089d2ae67b4b5bc8d8ad9 Gitweb: https://git.kernel.org/tip/f44e70325748c7998cf089d2ae67b4b5bc8d8ad9 Author: Peter Zijlstra AuthorDate: Thu, 20 Feb 2020 13:17:27 +01:00 Committer: Thomas Gleixner CommitterDate: Fri, 15 May 2020 20:03:04 +02:00 x86/doublefault: Remove memmove() call Use of memmove() in #DF is problematic considered tracing and other instrumentation. Remove the memmove() call and simply write out what needs doing; this even clarifies the code, win-win! The code copies from the espfix64 stack to the normal task stack, there is no possible way for that to overlap. Survives selftests/x86, specifically sigreturn_64. Suggested-by: Borislav Petkov Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Thomas Gleixner Reviewed-by: Alexandre Chartre Acked-by: Andy Lutomirski Link: https://lkml.kernel.org/r/20200505134058.863038566@linutronix.de --- arch/x86/kernel/traps.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index e85561f..75fa765 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -369,6 +369,7 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code, unsign regs->ip == (unsigned long)native_irq_return_iret) { struct pt_regs *gpregs = (struct pt_regs *)this_cpu_read(cpu_tss_rw.x86_tss.sp0) - 1; + unsigned long *p = (unsigned long *)regs->sp; /* * regs->sp points to the failing IRET frame on the @@ -376,7 +377,11 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code, unsign * in gpregs->ss through gpregs->ip. * */ - memmove(&gpregs->ip, (void *)regs->sp, 5*8); + gpregs->ip = p[0]; + gpregs->cs = p[1]; + gpregs->flags = p[2]; + gpregs->sp = p[3]; + gpregs->ss = p[4]; gpregs->orig_ax = 0; /* Missing (lost) #GP error code */ /*