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=-11.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,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 571AAC3A59F for ; Thu, 29 Aug 2019 19:03:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3393422CEA for ; Thu, 29 Aug 2019 19:03:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729267AbfH2TC7 (ORCPT ); Thu, 29 Aug 2019 15:02:59 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:51585 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729229AbfH2TCz (ORCPT ); Thu, 29 Aug 2019 15:02:55 -0400 Received: from [5.158.153.53] (helo=tip-bot2.lab.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1i3Ph0-0005PD-6a; Thu, 29 Aug 2019 21:02:46 +0200 Received: from [127.0.1.1] (localhost [IPv6:::1]) by tip-bot2.lab.linutronix.de (Postfix) with ESMTP id BAAD41C0DE6; Thu, 29 Aug 2019 21:02:45 +0200 (CEST) Date: Thu, 29 Aug 2019 19:02:45 -0000 From: "tip-bot2 for Thomas Gleixner" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/pti] x86/mm/pti: Do not invoke PTI functions when PTI is disabled Cc: Thomas Gleixner , Dave Hansen , Ingo Molnar , Song Liu , "Peter Zijlstra (Intel)" , Borislav Petkov , linux-kernel@vger.kernel.org In-Reply-To: <20190828143124.063353972@linutronix.de> References: <20190828143124.063353972@linutronix.de> MIME-Version: 1.0 Message-ID: <156710536567.11135.4843469499808900617.tip-bot2@tip-bot2> X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit 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 The following commit has been merged into the x86/pti branch of tip: Commit-ID: 990784b57731192b7d90c8d4049e6318d81e887d Gitweb: https://git.kernel.org/tip/990784b57731192b7d90c8d4049e6318d81e887d Author: Thomas Gleixner AuthorDate: Wed, 28 Aug 2019 16:24:47 +02:00 Committer: Thomas Gleixner CommitterDate: Thu, 29 Aug 2019 20:52:53 +02:00 x86/mm/pti: Do not invoke PTI functions when PTI is disabled When PTI is disabled at boot time either because the CPU is not affected or PTI has been disabled on the command line, the boot code still calls into pti_finalize() which then unconditionally invokes: pti_clone_entry_text() pti_clone_kernel_text() pti_clone_kernel_text() was called unconditionally before the 32bit support was added and 32bit added the call to pti_clone_entry_text(). The call has no side effects as cloning the page tables into the available second one, which was allocated for PTI does not create damage. But it does not make sense either and in case that this functionality would be extended later this might actually lead to hard to diagnose issues. Neither function should be called when PTI is runtime disabled. Make the invocation conditional. Signed-off-by: Thomas Gleixner Reviewed-by: Dave Hansen Acked-by: Ingo Molnar Acked-by: Song Liu Acked-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20190828143124.063353972@linutronix.de --- arch/x86/mm/pti.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c index a24487b..7f21404 100644 --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -668,6 +668,8 @@ void __init pti_init(void) */ void pti_finalize(void) { + if (!boot_cpu_has(X86_FEATURE_PTI)) + return; /* * We need to clone everything (again) that maps parts of the * kernel image.