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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 7A01EC433E6 for ; Thu, 11 Mar 2021 15:45:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 20E0164FF6 for ; Thu, 11 Mar 2021 15:45:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234169AbhCKPpH (ORCPT ); Thu, 11 Mar 2021 10:45:07 -0500 Received: from mga04.intel.com ([192.55.52.120]:61146 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234096AbhCKPok (ORCPT ); Thu, 11 Mar 2021 10:44:40 -0500 IronPort-SDR: qWK9aRE2TTZXTnoGQ6XadpIdaUrWHZIrBladi08rhh9Bhd46bi94+w+pNYdIORre8+gcMBXe4+ 4SNLXEpDnd0w== X-IronPort-AV: E=McAfee;i="6000,8403,9920"; a="186305781" X-IronPort-AV: E=Sophos;i="5.81,241,1610438400"; d="scan'208";a="186305781" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Mar 2021 07:44:40 -0800 IronPort-SDR: lVQmY3uuvk0SUoyAiiYU6+ijNeIsC7r6XEJxTl3KcWvFb7zk/HRdoWsUdZ7GfcLk9Ooudiw5o4 51RFWl0wayEQ== X-IronPort-AV: E=Sophos;i="5.81,241,1610438400"; d="scan'208";a="404106966" Received: from yyu32-mobl1.amr.corp.intel.com (HELO [10.212.103.95]) ([10.212.103.95]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Mar 2021 07:44:39 -0800 Subject: Re: [PATCH v22 8/8] x86/vdso: Add ENDBR64 to __vdso_sgx_enter_enclave To: Peter Zijlstra , Jarkko Sakkinen Cc: x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Dave Martin , Weijiang Yang , Pengfei Xu , Haitao Huang References: <20210310220519.16811-1-yu-cheng.yu@intel.com> <20210310220519.16811-9-yu-cheng.yu@intel.com> <8b8efe44-b79f-ce29-ee28-066f88c93840@intel.com> From: "Yu, Yu-cheng" Message-ID: Date: Thu, 11 Mar 2021 07:44:39 -0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/11/2021 12:42 AM, Peter Zijlstra wrote: > On Thu, Mar 11, 2021 at 05:36:06AM +0200, Jarkko Sakkinen wrote: >> Does it do any harm to put it there unconditionally? > > Blows up your text footprint and I$ pressure. These instructions are 4 > bytes each. > > Aside from that, they're a NOP, so only consume front-end resources > (hopefully) on older CPUs and when IBT is disabled. > Thanks Peter. I think probably we'll do the macro Boris suggested. That takes care of the visual clutter, and eliminates the need of using .byte when the assembler is outdated. -- Yu-cheng