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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 AA87BC46466 for ; Tue, 20 Nov 2018 20:41:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 63F712241B for ; Tue, 20 Nov 2018 20:41:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 63F712241B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727133AbeKUHM6 (ORCPT ); Wed, 21 Nov 2018 02:12:58 -0500 Received: from mga02.intel.com ([134.134.136.20]:50020 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725968AbeKUHM6 (ORCPT ); Wed, 21 Nov 2018 02:12:58 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 20 Nov 2018 12:41:57 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,258,1539673200"; d="scan'208";a="87439706" Received: from yyu32-desk1.sc.intel.com ([143.183.136.147]) by fmsmga007.fm.intel.com with ESMTP; 20 Nov 2018 12:41:56 -0800 Message-ID: <16a0261fbe4b31e2f42b552d6a991a1116d398c2.camel@intel.com> Subject: Re: [RFC PATCH v6 01/26] Documentation/x86: Add CET description From: Yu-cheng Yu To: Ingo Molnar 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 , 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 , Peter Zijlstra , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue Date: Tue, 20 Nov 2018 12:36:38 -0800 In-Reply-To: <20181120095253.GA119911@gmail.com> References: <20181119214809.6086-1-yu-cheng.yu@intel.com> <20181119214809.6086-2-yu-cheng.yu@intel.com> <20181120095253.GA119911@gmail.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.1-2 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2018-11-20 at 10:52 +0100, Ingo Molnar wrote: > * Yu-cheng Yu wrote: > > > +X86 Documentation > > [...] > > + > > +At run time, /proc/cpuinfo shows the availability of SHSTK and IBT. > > What is the rough expected performance impact of CET on average function > call frequency user applications and the kernel itself? I don't have any conclusive numbers yet; but since currently only user-mode protection is implemented, I suspect any impact would be most likely to the application. The kernel would spend some small amount of time on the setup of CET. Yu-cheng