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=-6.1 required=3.0 tests=BAYES_00,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 70412C433B4 for ; Tue, 18 May 2021 12:48:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4DD3A6124C for ; Tue, 18 May 2021 12:48:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244400AbhERMtn (ORCPT ); Tue, 18 May 2021 08:49:43 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:45604 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243710AbhERMtn (ORCPT ); Tue, 18 May 2021 08:49:43 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1621342104; 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=Xys4RHY26UfieMaalsu2Qz1GHffwuNktYKADu7evr5g=; b=fNz60PcI92BNWeaPqw6MH5O47FOjB0UBp7xji7z/5UQJIW2cQAmRGUuKMky9250X+aHwtT N/QIQ0yLzRpCyi3PkPXNxsrP6BabdHA7uWIy0RQIHv+b9GPXbBJS3adb3/a+Qr+0eZtOCk iEjvJP3E0MZ4qWRoSFVxWKX9gu4PLjE= 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-569-QHxWfWhWNuWFajznfHuGmA-1; Tue, 18 May 2021 08:48:23 -0400 X-MC-Unique: QHxWfWhWNuWFajznfHuGmA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3C463803622; Tue, 18 May 2021 12:48:21 +0000 (UTC) Received: from treble (ovpn-119-197.rdu2.redhat.com [10.10.119.197]) by smtp.corp.redhat.com (Postfix) with SMTP id 1F465BA6D; Tue, 18 May 2021 12:48:20 +0000 (UTC) Date: Tue, 18 May 2021 07:48:19 -0500 From: Josh Poimboeuf To: Will Deacon Cc: Nick Desaulniers , "Jose E. Marchesi" , "Paul E. McKenney" , peterz@infradead.org, ardb@kernel.org, catalin.marinas@arm.com, mark.rutland@arm.com, linux-toolchains@vger.kernel.org Subject: Re: Linux Plumbers Conf 2021 Message-ID: <20210518124819.lkzzgjcrh4cc5a6i@treble> References: <20210518121447.GB7914@willie-the-truck> <20210518124311.r4fwv6lfz3erkqnb@treble> MIME-Version: 1.0 In-Reply-To: <20210518124311.r4fwv6lfz3erkqnb@treble> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=jpoimboe@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Precedence: bulk List-ID: X-Mailing-List: linux-toolchains@vger.kernel.org Fixing linux-toolchains list address. On Tue, May 18, 2021 at 07:43:13AM -0500, Josh Poimboeuf wrote: > On Tue, May 18, 2021 at 01:14:48PM +0100, Will Deacon wrote: > > If it's not too late, I'd definitely be interested in a discussion around > > objtool support for arm64. Specifically, I would very much like us _not_ > > to have a hard dependency on objtool and instead treat it as a binary > > linter of sorts. However, this likely requires help from the toolchain > > where some of the jobs which are performed by objtool on x86 today now > > need to be done by the compiler/linker for arm64. > > > > I don't have a good handle on exactly what is needed and whether there's > > any appetite from the toolchain developers to implement this, so it would > > be very helpful to kick that discussion off. > > Objtool stack validation already is pretty much a "binary linter". If > all the warnings are fixed then we can trust the unwind metadata (e.g. > frame pointers) for reliable unwinding / live patching. > > All warnings are expected to be fixed by humans, so objtool doesn't have > to edit the binary (assuming no ORC, which is optional). Objtool is > only considered a hard dependency for live patching because unfixed > warnings could mean a livepatch fail. > > So I wonder what specifically you have in mind? > > -- > Josh -- Josh