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=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_NEOMUTT 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 5EC70C43381 for ; Mon, 11 Mar 2019 18:00:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 419A32075C for ; Mon, 11 Mar 2019 18:00:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727940AbfCKSAQ (ORCPT ); Mon, 11 Mar 2019 14:00:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52196 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726864AbfCKSAQ (ORCPT ); Mon, 11 Mar 2019 14:00:16 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 2C6AB88304; Mon, 11 Mar 2019 18:00:16 +0000 (UTC) Received: from treble (ovpn-123-151.rdu2.redhat.com [10.10.123.151]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 95830608E2; Mon, 11 Mar 2019 18:00:11 +0000 (UTC) Date: Mon, 11 Mar 2019 13:00:09 -0500 From: Josh Poimboeuf To: Peter Zijlstra 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: <20190311180009.7dpvwevuufz7jdxm@treble> References: <20190307114511.870090179@infradead.org> <20190307115200.878625203@infradead.org> <20190308211603.fpjbd5avcuoox6xf@treble> <20190308213343.GE2482@worktop.programming.kicks-ass.net> <20190308215602.txm4bv2eg2tyubuj@treble> <20190310131331.GK2482@worktop.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190310131331.GK2482@worktop.programming.kicks-ass.net> User-Agent: NeoMutt/20180716 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Mon, 11 Mar 2019 18:00:16 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Mar 10, 2019 at 02:13:31PM +0100, Peter Zijlstra wrote: > 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 :-) If it doesn't matter much either way, I'd rather err on the side of less code. Your call though. -- Josh