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=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,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 D8766C2BA15 for ; Sat, 4 Apr 2020 14:22:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 88469206C3 for ; Sat, 4 Apr 2020 14:22:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="fqaFysNp" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726327AbgDDOWk (ORCPT ); Sat, 4 Apr 2020 10:22:40 -0400 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:58058 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725730AbgDDOWk (ORCPT ); Sat, 4 Apr 2020 10:22:40 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1586010158; 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=ZBXXFQq1y2qUkhtU8bFmrD9Xf22O0XSHFLk6Da/v1Ng=; b=fqaFysNpRD7ViHHR2RRO8/AekGdLA2OsSeC9AkpgF0sUmaDOpQ3dHHhyKo8VpN64KeTzCn LGzzsHOx37Denawkz9MjmIpvS96W0ZrL0sBaRR3HW08x/7Q90N4H+HW57g/SMfuMdhPISC T5Pp1ZZ5Ha9M3du54klAdn3Big1+MYg= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-184-AapuGhmOOn2xw4RaB3Ma6g-1; Sat, 04 Apr 2020 10:22:36 -0400 X-MC-Unique: AapuGhmOOn2xw4RaB3Ma6g-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 78D328018A2; Sat, 4 Apr 2020 14:22:35 +0000 (UTC) Received: from treble (ovpn-118-100.rdu2.redhat.com [10.10.118.100]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 479415C1B0; Sat, 4 Apr 2020 14:22:34 +0000 (UTC) Date: Sat, 4 Apr 2020 09:22:32 -0500 From: Josh Poimboeuf To: Peter Zijlstra Cc: Julien Thierry , Alexandre Chartre , x86@kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de Subject: Re: [PATCH 4/7] objtool: Add support for return trampoline call Message-ID: <20200404142232.wpn7estahnabfy3z@treble> References: <20200402082220.808-1-alexandre.chartre@oracle.com> <20200402082220.808-5-alexandre.chartre@oracle.com> <20200402154022.GG20730@hirez.programming.kicks-ass.net> <20200403151757.lhhia7pzqptvlqz5@treble> <20200403154620.GS20730@hirez.programming.kicks-ass.net> <20200404133218.GL20760@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200404133218.GL20760@hirez.programming.kicks-ass.net> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Apr 04, 2020 at 03:32:18PM +0200, Peter Zijlstra wrote: > On Fri, Apr 03, 2020 at 05:46:20PM +0200, Peter Zijlstra wrote: > > On Fri, Apr 03, 2020 at 10:17:57AM -0500, Josh Poimboeuf wrote: > > > Peter, I think my previous idea for UNWIND_HINT_ADJUST stack_add=8 would > > > work here? > > > > Yes, it would. > > Sorry, I have reconsidered. While it will shut up objtool, it will not > 'work'. That is, the ORC data generated will not correctly unwind. > > I'll try and write a longer email tonight. Right, that's what I've been trying to say. The ORC data will be non-deterministic unless we unroll the loop. Or did you mean something else? -- Josh