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=-7.7 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 4DD7EC04EB8 for ; Tue, 4 Dec 2018 10:57:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 14AEA214DA for ; Tue, 4 Dec 2018 10:57:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="G3IJsRgh" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 14AEA214DA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org 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 S1726704AbeLDK5S (ORCPT ); Tue, 4 Dec 2018 05:57:18 -0500 Received: from mail.kernel.org ([198.145.29.99]:41030 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726681AbeLDK5P (ORCPT ); Tue, 4 Dec 2018 05:57:15 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id F1D82214DB; Tue, 4 Dec 2018 10:57:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1543921034; bh=geR1AF6GiEwi8hVn0yZTcuDcHhlQJEi0LT6ZmNYDxKw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=G3IJsRghcqPDmcnRDKUu0oUrxPksBMD4SFQ7jUjYqcH1oo80TYmcp2czftUCoZZ+C GO2ZoPePu3+amVo5GTyzs6xta9OKuUk65scO9Pig7+ht4gZQJ5Xh1BxuCOBHziW7FH zQ2efqaBonnsn3A22V4Pu7Obn/eMdHNLJQW7p1Xg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Peter Zijlstra , Andy Lutomirski , Linus Torvalds , Jiri Kosina , Tom Lendacky , Josh Poimboeuf , Andrea Arcangeli , David Woodhouse , Tim Chen , Andi Kleen , Dave Hansen , Casey Schaufler , Asit Mallick , Arjan van de Ven , Jon Masters , Waiman Long , Dave Stewart , Kees Cook Subject: [PATCH 4.19 055/139] x86/speculation: Split out TIF update Date: Tue, 4 Dec 2018 11:48:56 +0100 Message-Id: <20181204103652.238238402@linuxfoundation.org> X-Mailer: git-send-email 2.19.2 In-Reply-To: <20181204103649.950154335@linuxfoundation.org> References: <20181204103649.950154335@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Thomas Gleixner tglx@linutronix.de commit e6da8bb6f9abb2628381904b24163c770e630bac upstream The update of the TIF_SSBD flag and the conditional speculation control MSR update is done in the ssb_prctl_set() function directly. The upcoming prctl support for controlling indirect branch speculation via STIBP needs the same mechanism. Split the code out and make it reusable. Reword the comment about updates for other tasks. Signed-off-by: Thomas Gleixner Reviewed-by: Ingo Molnar Cc: Peter Zijlstra Cc: Andy Lutomirski Cc: Linus Torvalds Cc: Jiri Kosina Cc: Tom Lendacky Cc: Josh Poimboeuf Cc: Andrea Arcangeli Cc: David Woodhouse Cc: Tim Chen Cc: Andi Kleen Cc: Dave Hansen Cc: Casey Schaufler Cc: Asit Mallick Cc: Arjan van de Ven Cc: Jon Masters Cc: Waiman Long Cc: Greg KH Cc: Dave Stewart Cc: Kees Cook Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20181125185005.652305076@linutronix.de Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/cpu/bugs.c | 35 +++++++++++++++++++++++------------ 1 file changed, 23 insertions(+), 12 deletions(-) --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -700,10 +700,29 @@ static void ssb_select_mitigation(void) #undef pr_fmt #define pr_fmt(fmt) "Speculation prctl: " fmt -static int ssb_prctl_set(struct task_struct *task, unsigned long ctrl) +static void task_update_spec_tif(struct task_struct *tsk, int tifbit, bool on) { bool update; + if (on) + update = !test_and_set_tsk_thread_flag(tsk, tifbit); + else + update = test_and_clear_tsk_thread_flag(tsk, tifbit); + + /* + * Immediately update the speculation control MSRs for the current + * task, but for a non-current task delay setting the CPU + * mitigation until it is scheduled next. + * + * This can only happen for SECCOMP mitigation. For PRCTL it's + * always the current task. + */ + if (tsk == current && update) + speculation_ctrl_update_current(); +} + +static int ssb_prctl_set(struct task_struct *task, unsigned long ctrl) +{ if (ssb_mode != SPEC_STORE_BYPASS_PRCTL && ssb_mode != SPEC_STORE_BYPASS_SECCOMP) return -ENXIO; @@ -714,28 +733,20 @@ static int ssb_prctl_set(struct task_str if (task_spec_ssb_force_disable(task)) return -EPERM; task_clear_spec_ssb_disable(task); - update = test_and_clear_tsk_thread_flag(task, TIF_SSBD); + task_update_spec_tif(task, TIF_SSBD, false); break; case PR_SPEC_DISABLE: task_set_spec_ssb_disable(task); - update = !test_and_set_tsk_thread_flag(task, TIF_SSBD); + task_update_spec_tif(task, TIF_SSBD, true); break; case PR_SPEC_FORCE_DISABLE: task_set_spec_ssb_disable(task); task_set_spec_ssb_force_disable(task); - update = !test_and_set_tsk_thread_flag(task, TIF_SSBD); + task_update_spec_tif(task, TIF_SSBD, true); break; default: return -ERANGE; } - - /* - * If being set on non-current task, delay setting the CPU - * mitigation until it is next scheduled. - */ - if (task == current && update) - speculation_ctrl_update_current(); - return 0; }