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 7AE44C43142 for ; Mon, 25 Jun 2018 09:18:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 28DB6224E1 for ; Mon, 25 Jun 2018 09:18:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 28DB6224E1 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 S1754923AbeFYJSh (ORCPT ); Mon, 25 Jun 2018 05:18:37 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:45955 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754701AbeFYJSg (ORCPT ); Mon, 25 Jun 2018 05:18:36 -0400 Received: from p4fea482e.dip0.t-ipconnect.de ([79.234.72.46] helo=nanos) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1fXNdL-0005Jd-Ho; Mon, 25 Jun 2018 11:18:03 +0200 Date: Mon, 25 Jun 2018 11:18:02 +0200 (CEST) From: Thomas Gleixner To: Peter Zijlstra cc: Pavel Tatashin , steven.sistare@oracle.com, daniel.m.jordan@oracle.com, linux@armlinux.org.uk, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, john.stultz@linaro.org, sboyd@codeaurora.org, x86@kernel.org, linux-kernel@vger.kernel.org, mingo@redhat.com, hpa@zytor.com, douly.fnst@cn.fujitsu.com, prarit@redhat.com, feng.tang@intel.com, pmladek@suse.com, gnomes@lxorguk.ukuu.org.uk, linux-s390@vger.kernel.org, Steven Rostedt Subject: Re: [PATCH v12 01/11] x86: text_poke() may access uninitialized struct pages In-Reply-To: <20180625090915.GV2494@hirez.programming.kicks-ass.net> Message-ID: References: <20180621212518.19914-1-pasha.tatashin@oracle.com> <20180621212518.19914-2-pasha.tatashin@oracle.com> <20180625081429.GS2494@hirez.programming.kicks-ass.net> <20180625090915.GV2494@hirez.programming.kicks-ass.net> 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 Mon, 25 Jun 2018, Peter Zijlstra wrote: > On Mon, Jun 25, 2018 at 10:39:24AM +0200, Thomas Gleixner wrote: > > On Mon, 25 Jun 2018, Peter Zijlstra wrote: > > > I'm not entirely sure this is right.. Because not only do we need the > > > whole fixmap stuff working, we also need #DB and the IPI handlers set-up > > > and working. > > > > IPI? That's early UP boot why would you need an IPI? > > Because the way this is called is from __jump_label_transform() -> > text_poke_bp() -> text_poke() -> text_poke_early(). > > And if you look at text_poke_bp(), you'll note it relies on #DB and > on_each_cpu() IPIs. on_each_cpu() resolves to a direct call on the current CPU and as there is no other CPU it does not matter. #DB might be a different story, haven't looked yet. > Which is of course exactly the reason I avoided text_poke_bp() entirely > in the first place. Fair enough. Thanks, tglx