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=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 A695AC43463 for ; Fri, 18 Sep 2020 21:24:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 68F8923119 for ; Fri, 18 Sep 2020 21:24:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726344AbgIRVYG (ORCPT ); Fri, 18 Sep 2020 17:24:06 -0400 Received: from jabberwock.ucw.cz ([46.255.230.98]:35150 "EHLO jabberwock.ucw.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726307AbgIRVYG (ORCPT ); Fri, 18 Sep 2020 17:24:06 -0400 Received: by jabberwock.ucw.cz (Postfix, from userid 1017) id CE3731C0B78; Fri, 18 Sep 2020 23:24:03 +0200 (CEST) Date: Fri, 18 Sep 2020 23:24:03 +0200 From: Pavel Machek To: "H.J. Lu" Cc: Randy Dunlap , Yu-cheng Yu , the arch/x86 maintainers , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , LKML , "open list:DOCUMENTATION" , Linux-MM , linux-arch , Linux API , Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Peter Zijlstra , "Ravi V. Shankar" , Vedvyas Shanbhogue , Dave Martin , Weijiang Yang Subject: Re: [PATCH v12 1/8] x86/cet/ibt: Add Kconfig option for user-mode Indirect Branch Tracking Message-ID: <20200918212403.GE4304@duo.ucw.cz> References: <20200918192312.25978-1-yu-cheng.yu@intel.com> <20200918192312.25978-2-yu-cheng.yu@intel.com> <20200918205933.GB4304@duo.ucw.cz> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="cPi+lWm09sJ+d57q" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org --cPi+lWm09sJ+d57q Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi! > > > > + help > > > > + Indirect Branch Tracking (IBT) provides protection against > > > > + CALL-/JMP-oriented programming attacks. It is active when > > > > + the kernel has this feature enabled, and the processor and > > > > + the application support it. When this feature is enabled, > > > > + legacy non-IBT applications continue to work, but without > > > > + IBT protection. > > > > + > > > > + If unsure, say y > > > > > > If unsure, say y. > > > > Actually, it would be "If unsure, say Y.", to be consistent with the > > rest of the Kconfig. > > > > But I wonder if Yes by default is good idea. Only very new CPUs will > > support this, right? Are they even available at the market? Should the > > help text say "if your CPU is Whatever Lake or newer, ...." :-) ? > > >=20 > CET enabled kernel runs on all x86-64 processors. All my machines > are running the same CET enabled kernel binary. I believe that. But enabling CET in kernel is useless on Core 2 Duo machine, right? Pavel --=20 (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo= g.html --cPi+lWm09sJ+d57q Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iF0EABECAB0WIQRPfPO7r0eAhk010v0w5/Bqldv68gUCX2UlcwAKCRAw5/Bqldv6 8r0mAJ9JcTHq3hoeh6afJxFoVECsAnMbOACfVq6tEmAU2T5ovnJ0hthFdEAfoN4= =kXk6 -----END PGP SIGNATURE----- --cPi+lWm09sJ+d57q--