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 D3BD4C43457 for ; Mon, 12 Oct 2020 20:30:04 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 3A6912087E for ; Mon, 12 Oct 2020 20:30:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3A6912087E 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 46635900002; Mon, 12 Oct 2020 16:30:03 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 414FF940007; Mon, 12 Oct 2020 16:30:03 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2DC1F900003; Mon, 12 Oct 2020 16:30:03 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0107.hostedemail.com [216.40.44.107]) by kanga.kvack.org (Postfix) with ESMTP id F053F900002 for ; Mon, 12 Oct 2020 16:30:02 -0400 (EDT) Received: from smtpin13.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 8DA753625 for ; Mon, 12 Oct 2020 20:30:02 +0000 (UTC) X-FDA: 77364415044.13.skirt03_1c0bc9d271fd Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin13.hostedemail.com (Postfix) with ESMTP id 6AF0E18140B67 for ; Mon, 12 Oct 2020 20:30:02 +0000 (UTC) X-HE-Tag: skirt03_1c0bc9d271fd X-Filterd-Recvd-Size: 3929 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by imf28.hostedemail.com (Postfix) with ESMTP for ; Mon, 12 Oct 2020 20:30:01 +0000 (UTC) IronPort-SDR: WJBfvnhsYJdIo5qBlaa8H/gnevhHeHgoAZL0RAM+6Ax9p068JS9QDFFjVFgD/SNaUI3hmj3o3p d5UdyLWcobUw== X-IronPort-AV: E=McAfee;i="6000,8403,9772"; a="165911769" X-IronPort-AV: E=Sophos;i="5.77,367,1596524400"; d="scan'208";a="165911769" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Oct 2020 13:29:59 -0700 IronPort-SDR: Q3TMmJJfFdzOben8LhYKlvy2Lf9ifmccyfK46qxXdTv68g+iC/y3Dbe8lzuVbqqJFOCGX9WdEK BE8Pg6hROcLw== X-IronPort-AV: E=Sophos;i="5.77,367,1596524400"; d="scan'208";a="356739364" Received: from yyu32-mobl1.amr.corp.intel.com (HELO [10.209.167.7]) ([10.209.167.7]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Oct 2020 13:29:58 -0700 Subject: Re: [PATCH v14 1/7] x86/cet/ibt: Add Kconfig option for user-mode Indirect Branch Tracking To: Cyrill Gorcunov 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 , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue , Dave Martin , Weijiang Yang , Pengfei Xu References: <20201012154530.28382-1-yu-cheng.yu@intel.com> <20201012154530.28382-2-yu-cheng.yu@intel.com> <20201012191511.GC14048@grain> From: "Yu, Yu-cheng" Message-ID: Date: Mon, 12 Oct 2020 13:29:57 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.12.1 MIME-Version: 1.0 In-Reply-To: <20201012191511.GC14048@grain> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit 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 10/12/2020 12:15 PM, Cyrill Gorcunov wrote: > On Mon, Oct 12, 2020 at 08:45:24AM -0700, Yu-cheng Yu wrote: > ... >> + the application support it. When this feature is enabled, >> + legacy non-IBT applications continue to work, but without >> + IBT protection. >> + Support for this feature is only known to be present on >> + processors released in 2020 or later. CET features are also >> + known to increase kernel text size by 3.7 KB. > > It seems the last sentence is redundant - new features always bloat > the kernel code and precise size may differ depending on compiler > and options. Surely this can be patched on top. > This was added after some discussion in v12 about kernel text size [1]. I think these few extra words can help people who have older machines and want to save some space. Yes, like you said, if later we don't want this sentence, I will be happy to add a patch to remove it. Thanks for the feedback. Yu-cheng [1] https://lore.kernel.org/linux-api/5e0a4005-45e3-3e88-e6e0-4ec31aad7eb9@intel.com/