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[46.139.12.213]) by smtp.gmail.com with ESMTPSA id t5sm70496wmg.43.2018.11.20.23.24.35 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 20 Nov 2018 23:24:36 -0800 (PST) Date: Wed, 21 Nov 2018 08:24:33 +0100 From: Ingo Molnar To: Yu-cheng Yu 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 Subject: Re: [RFC PATCH v6 01/26] Documentation/x86: Add CET description Message-ID: <20181121072433.GA56599@gmail.com> References: <20181119214809.6086-1-yu-cheng.yu@intel.com> <20181119214809.6086-2-yu-cheng.yu@intel.com> <20181120095253.GA119911@gmail.com> <16a0261fbe4b31e2f42b552d6a991a1116d398c2.camel@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <16a0261fbe4b31e2f42b552d6a991a1116d398c2.camel@intel.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Yu-cheng Yu wrote: > 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. This is horribly vague. Thanks, Ingo