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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 A1490C433F5 for ; Wed, 5 Sep 2018 18:26:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 677AB20857 for ; Wed, 5 Sep 2018 18:26:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 677AB20857 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linutronix.de 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 S1727740AbeIEW6P (ORCPT ); Wed, 5 Sep 2018 18:58:15 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:60301 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727195AbeIEW6P (ORCPT ); Wed, 5 Sep 2018 18:58:15 -0400 Received: from p4fea45ac.dip0.t-ipconnect.de ([79.234.69.172] helo=nanos) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1fxcVj-0002Gp-QV; Wed, 05 Sep 2018 20:26:39 +0200 Date: Wed, 5 Sep 2018 20:26:38 +0200 (CEST) From: Thomas Gleixner To: Andi Kleen cc: Jiri Kosina , Tim Chen , "Schaufler, Casey" , Ingo Molnar , Peter Zijlstra , Josh Poimboeuf , Andrea Arcangeli , "Woodhouse, David" , Oleg Nesterov , "linux-kernel@vger.kernel.org" , "x86@kernel.org" Subject: Re: [PATCH v3 1/3] ptrace: Provide ___ptrace_may_access() that can be applied on arbitrary tasks In-Reply-To: <20180905155823.GL27886@tassilo.jf.intel.com> Message-ID: References: <31436186-88da-324e-88a0-8fdca7bf60ac@linux.intel.com> <99FC4B6EFCEFD44486C35F4C281DC67321447094@ORSMSX107.amr.corp.intel.com> <3f24e8c8-eab8-66c2-9a8d-957e30cac809@linux.intel.com> <20180905155823.GL27886@tassilo.jf.intel.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 5 Sep 2018, Andi Kleen wrote: > > So, after giving it a bit more thought, I still believe "I want spectre V2 > > protection" vs. "I do not care about spectre V2 on my system > > (=nospectre_v2)" are the sane options we should provide; so I'll respin v4 > > of my patchset, including the ptrace check in switch_mm() (statically > > patched out on !IBPB-capable systems), and we can then later see whether > > the LSM implementation, once it exists, should be used instead. > > Please if you repost include plenty of performance numbers for multi threaded > workloads. It's ridiculous to even discuss this without them. Either we care about that problem and provide a proper mechanism to protect systems or we do not. That's not a performance number problem at all. Thanks, tglx