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=-6.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 EC286C4332B for ; Fri, 12 Mar 2021 16:57:12 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 563F465033 for ; Fri, 12 Mar 2021 16:57:12 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 563F465033 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id BDB7F6B009A; Fri, 12 Mar 2021 11:57:11 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id BB2836B009C; Fri, 12 Mar 2021 11:57:11 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A797F6B009D; Fri, 12 Mar 2021 11:57:11 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0109.hostedemail.com [216.40.44.109]) by kanga.kvack.org (Postfix) with ESMTP id 8AF0E6B009A for ; Fri, 12 Mar 2021 11:57:11 -0500 (EST) Received: from smtpin03.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 491B18248047 for ; Fri, 12 Mar 2021 16:57:11 +0000 (UTC) X-FDA: 77911827462.03.52392E7 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf15.hostedemail.com (Postfix) with ESMTP id 01D14A0009E7 for ; Fri, 12 Mar 2021 16:57:09 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 625456500F; Fri, 12 Mar 2021 16:57:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1615568229; bh=SJfafrtQ5B5A3SwT7vSgIDHHYLMqHVBXm88U6i/lrz8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ZBHd/DIGMGGyAQ1Fyh1z65o26PZRWPBaC7HmqL2I2BJz0xpc2D2+UYR+uWE4tsBfF zKsPdydcsHyw1HKBdrcdU09WvmHKT1lPsLFxQq0x37koIVDPApwPcgVE2kveptR7H0 Gu8Krielpjd6FDaZcfu0WRktySs+gqtoAic+1xoP/7qJWXYv9txQA72CN1rXi2U3lV 7StlQT3Yp/t/TOcJlVtySp/DZuikkwGIKJ4LjTgPwu4CX9j6jYIjJow80BFYaSDYED eUITaKLoDEK1lW+fqO8UYxW/ayjQ+Xni3OFKmdPBIvg+g18BK0aEN390EwRVKxLmcC Pux89hDB5Ihfg== Date: Fri, 12 Mar 2021 18:56:45 +0200 From: Jarkko Sakkinen To: Peter Zijlstra Cc: "Yu, Yu-cheng" , 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 Subject: Re: [PATCH v22 8/8] x86/vdso: Add ENDBR64 to __vdso_sgx_enter_enclave Message-ID: References: <20210310220519.16811-1-yu-cheng.yu@intel.com> <20210310220519.16811-9-yu-cheng.yu@intel.com> <8b8efe44-b79f-ce29-ee28-066f88c93840@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: 4bogdc7dd7wpzwq5fa354cnw56s1kciw X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 01D14A0009E7 Received-SPF: none (kernel.org>: No applicable sender policy available) receiver=imf15; identity=mailfrom; envelope-from=""; helo=mail.kernel.org; client-ip=198.145.29.99 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1615568229-891269 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 Thu, Mar 11, 2021 at 09:42:05AM +0100, 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. OK, understood, thanks for the explanation. /Jarkko