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=-3.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 101DFC35646 for ; Fri, 21 Feb 2020 13:51:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D73DE24676 for ; Fri, 21 Feb 2020 13:51:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="FcHHQ2Za" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728852AbgBUNuk (ORCPT ); Fri, 21 Feb 2020 08:50:40 -0500 Received: from merlin.infradead.org ([205.233.59.134]:45512 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728829AbgBUNui (ORCPT ); Fri, 21 Feb 2020 08:50:38 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-Id:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To; bh=4ftWpOmadAOI/R1k36uM0sOzlPG8YKuw4enMq9FixWQ=; b=FcHHQ2Za0ZHjLasjlAB4tJcaOc B1KapfQ55WVx7k9On26pIvP2VetAPCfgz8RApbRSm2MujQM7r6J+GABxkqPvNP+1844FOXJrDgJcZ MOzCiVFkqw/jA1aZOZMI/KIhIMYnsWsCUpDPVT5eNYq2PN6nbOrdPBTZ3fEnjV6gYxoP3OGJaLyBv 1CLQ27N5vEsWM9VY/rjB3RZew+Oz9PNtXHZfQ+bJVa/9N6ceCno3m44vfbwLM90sCj7m7mUZh9Ga4 pGiHn6eXlgk/kmybof1YjZYwK65Ze0lrlq+ERQim937Jx1XXgr9vpJ4zJNwrQfI/f27RAqTV0GxF2 xogcI4sg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1j58gv-0006V0-4T; Fri, 21 Feb 2020 13:50:05 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 468E53070F9; Fri, 21 Feb 2020 14:48:08 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 0) id BC15A29B59040; Fri, 21 Feb 2020 14:50:00 +0100 (CET) Message-Id: <20200221134215.385886177@infradead.org> User-Agent: quilt/0.65 Date: Fri, 21 Feb 2020 14:34:22 +0100 From: Peter Zijlstra To: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, rostedt@goodmis.org Cc: peterz@infradead.org, mingo@kernel.org, joel@joelfernandes.org, gregkh@linuxfoundation.org, gustavo@embeddedor.com, tglx@linutronix.de, paulmck@kernel.org, josh@joshtriplett.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, luto@kernel.org, tony.luck@intel.com, frederic@kernel.org, dan.carpenter@oracle.com, mhiramat@kernel.org Subject: [PATCH v4 06/27] x86/doublefault: Remove memmove() call References: <20200221133416.777099322@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Use of memmove() in #DF is problematic when you consider tracing and other instrumentation. Remove the memmove() call and simply write out what need doing; Boris argues the ranges should not overlap. Survives selftests/x86, specifically sigreturn_64. (Andy ?!) Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200220121727.GB507@zn.tnic --- arch/x86/kernel/traps.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -278,6 +278,7 @@ dotraplinkage void do_double_fault(struc 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 @@ -285,7 +286,11 @@ dotraplinkage void do_double_fault(struc * 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 */ /*