[3.5.y.z,extended,stable] Patch "perf, x86: fix kernel crash with PEBS/BTS after suspend/resume" has been added to staging queue

Message ID 1363776235-5148-1-git-send-email-luis.henriques@canonical.com
State New
Headers show

Commit Message

Luis Henriques March 20, 2013, 10:43 a.m.
This is a note to let you know that I have just added a patch titled

    perf,x86: fix kernel crash with PEBS/BTS after suspend/resume

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:


If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see



From a27090150fb7e7389840d4666f227db5e19e0ac2 Mon Sep 17 00:00:00 2001
From: Stephane Eranian <eranian@google.com>
Date: Fri, 15 Mar 2013 14:26:07 +0100
Subject: [PATCH] perf,x86: fix kernel crash with PEBS/BTS after suspend/resume

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 <torvalds@linux-foundation.org>
Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
 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(+)



diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c
index 35e2192..9a9be1e 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_ds.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c
@@ -714,3 +714,11 @@  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());
diff --git a/arch/x86/power/cpu.c b/arch/x86/power/cpu.c
index 218cdb1..fcbaac60 100644
--- a/arch/x86/power/cpu.c
+++ b/arch/x86/power/cpu.c
@@ -11,6 +11,7 @@ 
 #include <linux/suspend.h>
 #include <linux/export.h>
 #include <linux/smp.h>
+#include <linux/perf_event.h>

 #include <asm/pgtable.h>
 #include <asm/proto.h>
@@ -227,6 +228,7 @@  static void __restore_processor_state(struct saved_context *ctxt)
+	perf_restore_debug_store();

 /* Needed by apm.c */
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index c3c98a6..1d56bf6 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1295,6 +1295,7 @@  extern void perf_swevent_put_recursion_context(int rctx);
 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);
 static inline void
 perf_event_task_sched_in(struct task_struct *prev,
@@ -1333,6 +1334,7 @@  static inline void perf_swevent_put_recursion_context(int rctx)		{ }
 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)			{ }

 #define perf_output_put(handle, x) perf_output_copy((handle), &(x), sizeof(x))