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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 25A61C43381 for ; Sun, 10 Mar 2019 13:13:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E0505207E0 for ; Sun, 10 Mar 2019 13:13:46 +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="e150KcCv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726581AbfCJNNp (ORCPT ); Sun, 10 Mar 2019 09:13:45 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:53288 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726449AbfCJNNo (ORCPT ); Sun, 10 Mar 2019 09:13:44 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=LEIef661FM8j5UkrBAqQSbJez2EkNY7teSflteSNOe8=; b=e150KcCvL1kPviLTyIjJkaAjd 27neT/ID10yeixqRKg9Ydq7cOiofdCM+5kqvlUSGAWr72ORDF3hoAe0NR/5YmnQsLMJ4scSIdkxI/ xzf2us0+vzgvsGEEOZBK6yLsvp6+7m2ICCUIrYJreLeuRp1aVAnCo/DpZBjdQGbjSNVZUklQNAa2F URVxwcpcee576r+wH1u45cxsHm0Z1/tVBLXhCqMfTQJI3B8vsOWMhCob7RhiS50RuDrkrYo8SDoSq zjkoaYWMoF+Uo78eqeJFVi9Mw3omRN04R6neJWRPg30wAWwMhPYvqi9yvf96gzZZuNZXXY0T7d6mf /Q+RnC1hQ==; Received: from [188.207.104.17] (helo=worktop.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1h2yGk-0006r0-4o; Sun, 10 Mar 2019 13:13:34 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id 08B05981BBE; Sun, 10 Mar 2019 14:13:32 +0100 (CET) Date: Sun, 10 Mar 2019 14:13:31 +0100 From: Peter Zijlstra To: Josh Poimboeuf Cc: torvalds@linux-foundation.org, tglx@linutronix.de, hpa@zytor.com, julien.thierry@arm.com, will.deacon@arm.com, luto@amacapital.net, mingo@kernel.org, catalin.marinas@arm.com, james.morse@arm.com, valentin.schneider@arm.com, brgerst@gmail.com, luto@kernel.org, bp@alien8.de, dvlasenk@redhat.com, linux-kernel@vger.kernel.org, dvyukov@google.com, rostedt@goodmis.org Subject: Re: [PATCH 20/20] objtool: Add Direction Flag validation Message-ID: <20190310131331.GK2482@worktop.programming.kicks-ass.net> References: <20190307114511.870090179@infradead.org> <20190307115200.878625203@infradead.org> <20190308211603.fpjbd5avcuoox6xf@treble> <20190308213343.GE2482@worktop.programming.kicks-ass.net> <20190308215602.txm4bv2eg2tyubuj@treble> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190308215602.txm4bv2eg2tyubuj@treble> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 08, 2019 at 03:56:02PM -0600, Josh Poimboeuf wrote: > On Fri, Mar 08, 2019 at 10:33:43PM +0100, Peter Zijlstra wrote: > > On Fri, Mar 08, 2019 at 03:16:03PM -0600, Josh Poimboeuf wrote: > > > Can you elaborate on why (in the patch description)? Did this actually > > > find any occurrences? > > > > Nope, didn't find anything. Also, all DF users are in asm so I didn't > > really expect any. Having it escape would probably result in fairly > > instant wreckage though. > > > > DF=1 results in things like rep mov going _backwards_. > > Ok, I wonder if we really need to add this then. Well, Linus asked for it, and it was a fairly trivial add-on :-)