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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 77A84C433F5 for ; Wed, 24 Nov 2021 18:18:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350420AbhKXSVm (ORCPT ); Wed, 24 Nov 2021 13:21:42 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:53885 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242520AbhKXSVa (ORCPT ); Wed, 24 Nov 2021 13:21:30 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1637777899; 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=aImuXRsg8yxI6g3AKa1ZMJeiF400ljnzLc9mnInKQqk=; b=UneTVI16XDCBvzZbylUqtwzDYMe4t09w3sNSsx7pjidRmxYXgpyS0xiDSH5Poo+knos9qR hnItwPBSLBn+sd72aLPta2HIbTdJoRAUbbebOqEenhgde8LofX8evO9BweH/1IiO6Id04u iXOxT4mr/3nbYEfCEDlQM8Ht9lDA9gc= Received: from mail-ot1-f72.google.com (mail-ot1-f72.google.com [209.85.210.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-506-7D3gM_edP6SGhWgScnEjew-1; Wed, 24 Nov 2021 13:18:18 -0500 X-MC-Unique: 7D3gM_edP6SGhWgScnEjew-1 Received: by mail-ot1-f72.google.com with SMTP id a9-20020a056830008900b0056561b8c755so2043849oto.22 for ; Wed, 24 Nov 2021 10:18:18 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=aImuXRsg8yxI6g3AKa1ZMJeiF400ljnzLc9mnInKQqk=; b=gxUGkkwP0lYhx9Mw6vIonbSlcYwpWQJ6QRWe2hux94D+yFlaoW91rFf7Mh4WKRaB22 WUa5Q/F5SH7t9UraKNg2mwkSoP2arWSMQgHVtgznsF0cUxtcMGKHieQ0R/WWvweV/6fZ nWUr/iv1ZNVCarIVZurPMjmPqraM56zm2kZ5sR3GNvk20I0JGs2SGOWGaS3IrUS/DKWz 8MLF4KbUtdwLDnJVK4V+DsVuTP5TqIDC5ywISwc5WR1dNL5LxJuEja96aaunUB0Znffl W1dVD8ilTiQsfbG4kuN9ALu1Pl9SJuX3roXflIhGTx2j7EBxphI0aFhGzoTnh69Pc129 HtoA== X-Gm-Message-State: AOAM531NYSVJiSAHHF9a8wCyrxIhzNDzp584Hr869s77HRgXgwMw0XFk h3I3DF/jGnbtGqEjT5PMiyeWVD5HGfizs2va4vnyioMgllOD/c9nSKXeeSWUyxViY3/xo2q4nzR rE9q36zcmGga9g0fOm+++4ae/ X-Received: by 2002:a05:6808:230d:: with SMTP id bn13mr8587363oib.102.1637777897692; Wed, 24 Nov 2021 10:18:17 -0800 (PST) X-Google-Smtp-Source: ABdhPJzv7e8nF+f1PWTCzu4bP/3XrRnuLWwR+3nOYDyykdCd/W64HSkTJm6pIPem5/EDCm6JYQ3Mlg== X-Received: by 2002:a05:6808:230d:: with SMTP id bn13mr8587323oib.102.1637777897463; Wed, 24 Nov 2021 10:18:17 -0800 (PST) Received: from treble ([2600:1700:6e32:6c00::15]) by smtp.gmail.com with ESMTPSA id bh12sm133130oib.25.2021.11.24.10.18.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Nov 2021 10:18:16 -0800 (PST) Date: Wed, 24 Nov 2021 10:18:14 -0800 From: Josh Poimboeuf To: Peter Zijlstra Cc: Mark Rutland , x86@kernel.org, joao@overdrivepizza.com, hjl.tools@gmail.com, andrew.cooper3@citrix.com, linux-kernel@vger.kernel.org, ndesaulniers@google.com, keescook@chromium.org, samitolvanen@google.com Subject: Re: [RFC][PATCH 1/6] x86: Annotate _THIS_IP_ Message-ID: <20211124181814.2ahj7ppt6kewcjmb@treble> References: <20211122170301.764232470@infradead.org> <20211122170805.025419814@infradead.org> <20211123135348.GE37253@lakrids.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 23, 2021 at 03:14:45PM +0100, Peter Zijlstra wrote: > On Tue, Nov 23, 2021 at 01:53:49PM +0000, Mark Rutland wrote: > > On Mon, Nov 22, 2021 at 06:03:02PM +0100, Peter Zijlstra wrote: > > > In order to find _THIS_IP_ code references in objtool, annotate them. > > > > Just to check my understanding, IIUC this is because in later patches > > you'll look at text relocations to spot missing ENDBRs, and when doing > > so you need to filter out _THIS_IP_ instances, since those don't need an > > ENDBR. Is that right? > > > > Just checking I haven't missed some other concern that might apply to > > arm64's BTI (Branch Target Identifier), which are analagous to ENDBR. > > Correct; since _THIS_IP_ is never used for control flow (afaik, let's > hope to $deity etc..) we can ignore any relocation resulting from it > (lots!). This would all be good context to add to the commit message. -- Josh