From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756129AbdCTRxu (ORCPT ); Mon, 20 Mar 2017 13:53:50 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:37946 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756004AbdCTRus (ORCPT ); Mon, 20 Mar 2017 13:50:48 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andy Lutomirski , Alexander Shishkin , Arnaldo Carvalho de Melo , Borislav Petkov , "H. Peter Anvin" , Jiri Olsa , Linus Torvalds , Peter Zijlstra , Stephane Eranian , Thomas Gleixner , Ingo Molnar Subject: [PATCH 4.4 26/28] x86/perf: Fix CR4.PCE propagation to use active_mm instead of mm Date: Mon, 20 Mar 2017 18:49:21 +0100 Message-Id: <20170320174720.237039139@linuxfoundation.org> X-Mailer: git-send-email 2.12.0 In-Reply-To: <20170320174718.794407270@linuxfoundation.org> References: <20170320174718.794407270@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Andy Lutomirski commit 5dc855d44c2ad960a86f593c60461f1ae1566b6d upstream. If one thread mmaps a perf event while another thread in the same mm is in some context where active_mm != mm (which can happen in the scheduler, for example), refresh_pce() would write the wrong value to CR4.PCE. This broke some PAPI tests. Reported-and-tested-by: Vince Weaver Signed-off-by: Andy Lutomirski Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Borislav Petkov Cc: H. Peter Anvin Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: stable@vger.kernel.org Fixes: 7911d3f7af14 ("perf/x86: Only allow rdpmc if a perf_event is mapped") Link: http://lkml.kernel.org/r/0c5b38a76ea50e405f9abe07a13dfaef87c173a1.1489694270.git.luto@kernel.org Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/cpu/perf_event.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -1996,8 +1996,8 @@ static int x86_pmu_event_init(struct per static void refresh_pce(void *ignored) { - if (current->mm) - load_mm_cr4(current->mm); + if (current->active_mm) + load_mm_cr4(current->active_mm); } static void x86_pmu_event_mapped(struct perf_event *event)