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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 CEF83C433E1 for ; Sat, 22 Aug 2020 00:43:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AA1FC2072D for ; Sat, 22 Aug 2020 00:43:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="fGNzcexa"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="SaUrR/w4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726870AbgHVAnM (ORCPT ); Fri, 21 Aug 2020 20:43:12 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:59666 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726688AbgHVAnK (ORCPT ); Fri, 21 Aug 2020 20:43:10 -0400 From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1598056988; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=9j5b+CtfA3mIyxZyTYcFL91niFPfgh0kPXDP8Y6fJV0=; b=fGNzcexaB0EfXZu78Cu1jtyLOEaKC9MQijZNjrtkdIlzqTqFdB/JPyJCgK5EIYlWAOaK/K ++gL6+7M5HBZYzfWi5qKwdUClKZs4iz3mCj7toiHgIDdaQvJFkkqlBLOAzeX8r3WkNC77n xx2RKtSMIpFKsHDG2z93gHkJt5HduxJdy5MDxWfdeVBglUxW8aj4itx8CDAIKbujmAChSF vpWh0DTCX/QR5Gc46ux4/pOvMs7BTm/9UALzLDD8qceJRLvqohcQUkkhZIdLr3vuprJYJL JOJm3Okr1GlzTQ89UKw1+oCqhsaOL+WBKBmuMnjdS8mVVTip8kCTnbyvEolKkQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1598056988; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=9j5b+CtfA3mIyxZyTYcFL91niFPfgh0kPXDP8Y6fJV0=; b=SaUrR/w46g7GN5iqAqa8LUfdWEQVi2MhqeKJbM7aAf1rOy2RvDPGhLDpDnq310TI2ewDfJ xkV+f++c/tSQofDA== To: Nick Desaulniers , Arvind Sankar Cc: "Paul E. McKenney" , Ingo Molnar , Arnd Bergmann , Borislav Petkov , "maintainer\:X86 ARCHITECTURE \(32-BIT AND 64-BIT\)" , "H. Peter Anvin" , "Kirill A. Shutemov" , Zhenzhong Duan , Kees Cook , Peter Zijlstra , Juergen Gross , Andy Lutomirski , Andrew Cooper , LKML , clang-built-linux , Will Deacon , Linus Torvalds Subject: Re: [PATCH] x86: work around clang IAS bug referencing __force_order In-Reply-To: References: <20200527135329.1172644-1-arnd@arndb.de> <878serh1b9.fsf@nanos.tec.linutronix.de> <87h7t6tpye.fsf@nanos.tec.linutronix.de> <20200813173701.GC4295@paulmck-ThinkPad-P72> <20200813180933.GA532283@rani.riverdale.lan> <875z9dioll.fsf@nanos.tec.linutronix.de> <20200820130641.GA536306@rani.riverdale.lan> <87zh6ohm03.fsf@nanos.tec.linutronix.de> <20200821230435.GA56974@rani.riverdale.lan> Date: Sat, 22 Aug 2020 02:43:08 +0200 Message-ID: <87eenzqzmr.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 21 2020 at 16:16, Nick Desaulniers wrote: > On Fri, Aug 21, 2020 at 4:04 PM Arvind Sankar wrote: >> On Fri, Aug 21, 2020 at 02:37:48AM +0200, Thomas Gleixner wrote: >> The gcc bug I linked to earlier is only fixed in gcc-6 onwards. Is that > > (based on https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82602#c14) > >> good enough to remove force_order? I can test gcc-4.9 and gcc-5 to check >> if it would currently have any impact. And that test tells you what exactly? That your particular build of those compilers does not have the problem. A truly scientific approach. > I think checking the disassemblies with a pre-gcc-6 would be good > enough then; that bug isn't specific to this particular case. What? I clearly want a statement from the GCC people that this won't happen on pre gcc6 compilers and not just some 'works for me' statement based on a randomly picked compiler build. Thanks, tglx