From 87a42f27adef5e88b8907edbc168de1380e7129e Mon Sep 17 00:00:00 2001
From: Stephane Eranian <eranian@google.com>
Date: Fri, 15 Mar 2013 14:26:07 +0100
Subject: 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: Shuah Khan <shuah.khan@hp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/kernel/cpu/perf_event_intel_ds.c | 8 ++++++++
arch/x86/power/cpu.c | 2 ++
2 files changed, 10 insertions(+)
(limited to 'arch/x86')
diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c
index d812fe2d02be..cf82ee55ef4b 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_ds.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c
@@ -754,6 +754,14 @@ static 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());
+}
+
#else /* CONFIG_CPU_SUP_INTEL */
static void reserve_ds_buffers(void)
diff --git a/arch/x86/power/cpu.c b/arch/x86/power/cpu.c
index 87bb35e34ef1..0ea8bd233def 100644
--- a/arch/x86/power/cpu.c
+++ b/arch/x86/power/cpu.c
@@ -10,6 +10,7 @@
#include <linux/suspend.h>
#include <linux/smp.h>
+#include <linux/perf_event.h>
#include <asm/pgtable.h>
#include <asm/proto.h>
@@ -224,6 +225,7 @@ static void __restore_processor_state(struct saved_context *ctxt)
do_fpu_end();
mtrr_bp_restore();
+ perf_restore_debug_store();
}
/* Needed by apm.c */
--
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