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=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 00AB5C4332E for ; Tue, 16 Mar 2021 20:15:57 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 6416864F6D for ; Tue, 16 Mar 2021 20:15:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6416864F6D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id E70D56B0036; Tue, 16 Mar 2021 16:15:55 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E21A36B006C; Tue, 16 Mar 2021 16:15:55 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C4D8D6B006E; Tue, 16 Mar 2021 16:15:55 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0167.hostedemail.com [216.40.44.167]) by kanga.kvack.org (Postfix) with ESMTP id A59446B0036 for ; Tue, 16 Mar 2021 16:15:55 -0400 (EDT) Received: from smtpin28.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 6A573249D for ; Tue, 16 Mar 2021 20:15:55 +0000 (UTC) X-FDA: 77926843470.28.9136E55 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) by imf23.hostedemail.com (Postfix) with ESMTP id C5516A0009E0 for ; Tue, 16 Mar 2021 20:15:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=25Try9Vsj8b5XGaRHjhes0qHsMMyPZK0kTaQIOavQ6A=; b=AnHus7XJzGVxIFuzMangQl62Hu v1y8qc5CSlkUQDXqbfOA9DNG4wicfwaNcF84seZZoQ093qg+6T2sWpFwW7GLKvaunoRSedXJg4Q7T IohHNum/GOeZdWKAOk3Wi0OagYHQ3Gi7Q8VP5mUzOz3bcLoZjR6ECx5/23Nda1Yoxn0EVTrNQWIlx jwNMZLzBQ6KQpIz+LHBOAFjJQcsnQWUZ6Eh5ciVqYQqH79Z6C84B4B2no38hwu+QKvvqvYzDQpdNN 5HhksWs8e0S/syyl5EvPS2A2CWec9m0KNNhw0zf+6SRhM/PrZbOn7i8/awQsztL82mAIqaTsHH39p 6aIHG54Q==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1lMG6S-001mTt-7H; Tue, 16 Mar 2021 20:15:44 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 3A3E5304D58; Tue, 16 Mar 2021 21:15:43 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 2307423CC228C; Tue, 16 Mar 2021 21:15:43 +0100 (CET) Date: Tue, 16 Mar 2021 21:15:43 +0100 From: Peter Zijlstra To: "Yu, Yu-cheng" 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 Subject: Re: [PATCH v23 6/9] x86/entry: Introduce ENDBR macro Message-ID: 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <65845773-6cf0-1bdc-1ecf-168de74cc283@intel.com> X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: C5516A0009E0 X-Stat-Signature: zzh9oika7gax6p35az3cn186sn5e3rzs Received-SPF: none (infradead.org>: No applicable sender policy available) receiver=imf23; identity=mailfrom; envelope-from=""; helo=desiato.infradead.org; client-ip=90.155.92.199 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1615925754-956772 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 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.