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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index f18d537..3e52a77 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1290,6 +1290,7 @@
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,
@@ -1328,6 +1329,7 @@
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))