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 D0BDFC04EBB for ; Thu, 22 Nov 2018 23:06:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A11E720820 for ; Thu, 22 Nov 2018 23:06:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A11E720820 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 S2407860AbeKWJqD (ORCPT ); Fri, 23 Nov 2018 04:46:03 -0500 Received: from Galois.linutronix.de ([146.0.238.70]:49182 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2392559AbeKWJqD (ORCPT ); Fri, 23 Nov 2018 04:46:03 -0500 Received: from p4fea46ac.dip0.t-ipconnect.de ([79.234.70.172] helo=nanos) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1gPy1G-0005vV-Nt; Fri, 23 Nov 2018 00:04:22 +0100 Date: Fri, 23 Nov 2018 00:04:22 +0100 (CET) From: Thomas Gleixner To: Ingo Molnar cc: LKML , x86@kernel.org, Peter Zijlstra , Andy Lutomirski , Linus Torvalds , Jiri Kosina , Tom Lendacky , Josh Poimboeuf , Andrea Arcangeli , David Woodhouse , Andi Kleen , Dave Hansen , Casey Schaufler , Asit Mallick , Arjan van de Ven , Jon Masters , Waiman Long , Greg KH , Dave Stewart , Kees Cook Subject: Re: [patch 20/24] x86/speculation: Split out TIF update In-Reply-To: <20181122074322.GE41788@gmail.com> Message-ID: References: <20181121201430.559770965@linutronix.de> <20181121201724.227260385@linutronix.de> <20181122074322.GE41788@gmail.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 Thu, 22 Nov 2018, Ingo Molnar wrote: > * Thomas Gleixner wrote: > > Had to read this twice, because the comment and the code are both correct > but deal with the inverse case. This might have helped: > > /* > * Immediately update the speculation MSRs on the current task, > * but for non-current tasks delay setting the CPU mitigation > * until it is scheduled next. > */ > if (tsk == current && update) > speculation_ctrl_update_current(); > > But can the target task ever be non-current here? I don't think so: the > two callers are prctl and seccomp, and both are passing in the current > task pointer. See te other mail. Yes, seccomp passes non current task pointers. Will update the comment. Thanks, tglx