From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756162Ab3CYBms (ORCPT ); Sun, 24 Mar 2013 21:42:48 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:33757 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755112Ab3CYBO5 (ORCPT ); Sun, 24 Mar 2013 21:14:57 -0400 Message-Id: <20130325010524.509840202@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Mon, 25 Mar 2013 01:05:26 +0000 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: akpm@linux-foundation.org, Stephane Eranian , Linus Torvalds Subject: [ 002/104] perf,x86: fix kernel crash with PEBS/BTS after suspend/resume Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In-Reply-To: <20130325010524.240972766@decadent.org.uk> X-SA-Exim-Connect-IP: 2001:470:1f08:1539:f137:78a:b654:affb X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Stephane Eranian commit 1d9d8639c063caf6efc2447f5f26aa637f844ff6 upstream. This patch fixes a kernel crash when using precise sampling (PEBS) after a suspend/resume. Turns out the CPU notifier code is not invoked on CPU0 (BP). Therefore, the DS_AREA (used by PEBS) is not restored properly by the kernel and keeps it power-on/resume value of 0 causing any PEBS measurement to crash when running on CPU0. The workaround is to add a hook in the actual resume code to restore the DS Area MSR value. It is invoked for all CPUS. So for all but CPU0, the DS_AREA will be restored twice but this is harmless. Reported-by: Linus Torvalds Signed-off-by: Stephane Eranian Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings --- arch/x86/kernel/cpu/perf_event_intel_ds.c | 8 ++++++++ arch/x86/power/cpu.c | 2 ++ include/linux/perf_event.h | 2 ++ 3 files changed, 12 insertions(+) --- a/arch/x86/kernel/cpu/perf_event_intel_ds.c +++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c @@ -736,3 +736,11 @@ void intel_ds_init(void) } } } + +void perf_restore_debug_store(void) +{ + if (!x86_pmu.bts && !x86_pmu.pebs) + return; + + init_debug_store_on_cpu(smp_processor_id()); +} --- a/arch/x86/power/cpu.c +++ b/arch/x86/power/cpu.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include @@ -225,6 +226,7 @@ static void __restore_processor_state(st do_fpu_end(); mtrr_bp_restore(); + perf_restore_debug_store(); } /* Needed by apm.c */ --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1146,6 +1146,7 @@ extern void perf_swevent_put_recursion_c extern void perf_event_enable(struct perf_event *event); extern void perf_event_disable(struct perf_event *event); extern void perf_event_task_tick(void); +extern void perf_restore_debug_store(void); #else static inline void perf_event_task_sched_in(struct task_struct *prev, @@ -1184,6 +1185,7 @@ static inline void perf_swevent_put_recu static inline void perf_event_enable(struct perf_event *event) { } static inline void perf_event_disable(struct perf_event *event) { } static inline void perf_event_task_tick(void) { } +static inline void perf_restore_debug_store(void) { } #endif #define perf_output_put(handle, x) perf_output_copy((handle), &(x), sizeof(x))