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 20102C433DB for ; Tue, 16 Mar 2021 20:27:00 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id B98F964E38 for ; Tue, 16 Mar 2021 20:26:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B98F964E38 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 3417B6B0036; Tue, 16 Mar 2021 16:26:59 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2F1286B006C; Tue, 16 Mar 2021 16:26:59 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 16BBE6B006E; Tue, 16 Mar 2021 16:26:59 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0081.hostedemail.com [216.40.44.81]) by kanga.kvack.org (Postfix) with ESMTP id EDAC26B0036 for ; Tue, 16 Mar 2021 16:26:58 -0400 (EDT) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id A4375181AEF32 for ; Tue, 16 Mar 2021 20:26:58 +0000 (UTC) X-FDA: 77926871316.10.C9292FA Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) by imf25.hostedemail.com (Postfix) with ESMTP id 661496000101 for ; Tue, 16 Mar 2021 20:26:57 +0000 (UTC) IronPort-SDR: gbXqSa1m36c7Jh8d82OANZivM2DVdKHHdwOaLP0AqOryPz9GisUC1KC/6bQ2HpKY8ytxJEdePl D6KqldJa2fMg== X-IronPort-AV: E=McAfee;i="6000,8403,9925"; a="169244938" X-IronPort-AV: E=Sophos;i="5.81,254,1610438400"; d="scan'208";a="169244938" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Mar 2021 13:26:54 -0700 IronPort-SDR: pD5ul5yOwtpfwHTN4BvRRRjbGIMkDXv5lWdENanTMsC4a8NqdJjtNTqy/C6okQOOanN2r8sIaK PlyFizGSP54A== X-IronPort-AV: E=Sophos;i="5.81,254,1610438400"; d="scan'208";a="449839286" Received: from yyu32-mobl1.amr.corp.intel.com (HELO [10.212.191.248]) ([10.212.191.248]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Mar 2021 13:26:52 -0700 Subject: Re: [PATCH v23 6/9] x86/entry: Introduce ENDBR macro To: Peter Zijlstra Cc: Dave Hansen , 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 , Jarkko Sakkinen References: <20210316151320.6123-1-yu-cheng.yu@intel.com> <20210316151320.6123-7-yu-cheng.yu@intel.com> <15966857-9be7-3029-7e93-e40596b4649a@intel.com> <65845773-6cf0-1bdc-1ecf-168de74cc283@intel.com> From: "Yu, Yu-cheng" Message-ID: Date: Tue, 16 Mar 2021 13:26:52 -0700 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 X-Stat-Signature: iqmzys8tzns9o3t3fo555sn5ixzzar4m X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 661496000101 Received-SPF: none (intel.com>: No applicable sender policy available) receiver=imf25; identity=mailfrom; envelope-from=""; helo=mga17.intel.com; client-ip=192.55.52.151 X-HE-DKIM-Result: none/none X-HE-Tag: 1615926417-84780 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 3/16/2021 1:15 PM, Peter Zijlstra wrote: > On Tue, Mar 16, 2021 at 01:05:30PM -0700, Yu, Yu-cheng wrote: >> On 3/16/2021 12:57 PM, Peter Zijlstra wrote: >>> On Tue, Mar 16, 2021 at 10:12:39AM -0700, Yu, Yu-cheng wrote: >>>> Alternatively, there is another compiler-defined macro _CET_ENDBR that can >>>> be used. We can put the following in calling.h: >>>> >>>> #ifdef __CET__ >>>> #include >>>> #else >>>> #define _CET_ENDBR >>>> #endif >>>> >>>> and then use _CET_ENDBR in other files. How is that? >>>> >>>> In the future, in case we have kernel-mode IBT, ENDBR macros are also needed >>>> for other assembly files. >>> >>> Can we please call it IBT_ENDBR or just ENDBR. CET is a horrible name, >>> seeing how it is not specific. >>> >> >> _CET_ENDBR is from the compiler and we cannot change it. We can do: >> >> #define ENDBR _CET_ENDBR >> >> How is that? > > Do we really want to include compiler headers? AFAICT it's not a > built-in. Also what about clang? > > This thing seems trivial enough to build our own, it's a single damn > instruction. That also means we don't have to worry about changes to > header files we don't control. > Then, what about moving what I had earlier to vdso.h? If we don't want __i386__ either, then make it two macros. +.macro ENDBR +#ifdef CONFIG_X86_CET +#ifdef __i386__ + endbr32 +#else + endbr64 +#endif +#endif +.endm