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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 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 88CE7C34047 for ; Wed, 19 Feb 2020 16:12:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5DF5D24656 for ; Wed, 19 Feb 2020 16:12:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726783AbgBSQMc (ORCPT ); Wed, 19 Feb 2020 11:12:32 -0500 Received: from mail.kernel.org ([198.145.29.99]:50330 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726731AbgBSQMb (ORCPT ); Wed, 19 Feb 2020 11:12:31 -0500 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8BCEF24654; Wed, 19 Feb 2020 16:12:29 +0000 (UTC) Date: Wed, 19 Feb 2020 11:12:28 -0500 From: Steven Rostedt To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.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: Re: [PATCH v3 04/22] x86/doublefault: Make memmove() notrace/NOKPROBE Message-ID: <20200219111228.44c2999b@gandalf.local.home> In-Reply-To: <20200219160442.GE14946@hirez.programming.kicks-ass.net> References: <20200219144724.800607165@infradead.org> <20200219150744.604459293@infradead.org> <20200219103614.2299ff61@gandalf.local.home> <20200219154031.GE18400@hirez.programming.kicks-ass.net> <20200219155715.GD14946@hirez.programming.kicks-ass.net> <20200219160442.GE14946@hirez.programming.kicks-ass.net> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 19 Feb 2020 17:04:42 +0100 Peter Zijlstra wrote: > > - memmove(&gpregs->ip, (void *)regs->sp, 5*8); > > + for (i = 0; i < count; i++) { > > + int idx = (dst <= src) ? i : count - i; > > That's an off-by-one for going backward; 'count - 1 - i' should work > better, or I should just stop typing for today ;-) Or, we could just cut and paste the current memmove and make a notrace version too. Then we don't need to worry bout bugs like this. -- Steve