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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 AC130C2D0DB for ; Thu, 30 Jan 2020 17:39:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8000F20661 for ; Thu, 30 Jan 2020 17:39:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727460AbgA3RjO (ORCPT ); Thu, 30 Jan 2020 12:39:14 -0500 Received: from mx2.suse.de ([195.135.220.15]:38162 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727247AbgA3RjO (ORCPT ); Thu, 30 Jan 2020 12:39:14 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 9ADC5AF6D; Thu, 30 Jan 2020 17:39:12 +0000 (UTC) Date: Thu, 30 Jan 2020 18:39:10 +0100 From: Borislav Petkov To: Linus Torvalds Cc: "Luck, Tony" , Ingo Molnar , Linux Kernel Mailing List , Thomas Gleixner , Borislav Petkov , Peter Zijlstra , Andrew Morton Subject: Re: [GIT PULL] x86/asm changes for v5.6 Message-ID: <20200130173910.GK6684@zn.tnic> References: <20200128165906.GA67781@gmail.com> <20200129132618.GA30979@zn.tnic> <20200129170725.GA21265@agluck-desk2.amr.corp.intel.com> <20200129183404.GB30979@zn.tnic> <20200130085134.GB6684@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 30, 2020 at 07:27:28AM -0800, Linus Torvalds wrote: > Fair enough. Let's not complicate things just to avoid a few nops. Yeah, judging by the frequency this keeps popping up, we might end up doing proper insn parsing for the alternatives soon. :) > That does make me wonder about RIP-relative addressing in alternatives > too. Particularly anything where we let gcc pick addressing modes. I > guess we don't have any, but maybe this branch issue and possible RIP > addressing is something that objtool could be taught to warn about? Yeah, makes sense. It would help if one slaps a relative JMP as *not* the first insn in an alternatives replacement and the build to warn that it can't work. Lemme go stare at objtool. -- Regards/Gruss, Boris. SUSE Software Solutions Germany GmbH, GF: Felix Imendörffer, HRB 36809, AG Nürnberg