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authorLinus Torvalds <torvalds@linux-foundation.org>2013-03-17 15:44:43 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-03-17 15:44:43 -0700
commit2a6e06b2aed6995af401dcd4feb5e79a0c7ea554 (patch)
treee8bfb4d2895a8857ab28a833b11c39bc961a1d65
parent08637024ab77f7defff1627cc8aedc2c6679ad8a (diff)
perf,x86: fix wrmsr_on_cpu() warning on suspend/resume
Commit 1d9d8639c063 ("perf,x86: fix kernel crash with PEBS/BTS after suspend/resume") fixed a crash when doing PEBS performance profiling after resuming, but in using init_debug_store_on_cpu() to restore the DS_AREA mtrr it also resulted in a new WARN_ON() triggering. init_debug_store_on_cpu() uses "wrmsr_on_cpu()", which in turn uses CPU cross-calls to do the MSR update. Which is not really valid at the early resume stage, and the warning is quite reasonable. Now, it all happens to _work_, for the simple reason that smp_call_function_single() ends up just doing the call directly on the CPU when the CPU number matches, but we really should just do the wrmsr() directly instead. This duplicates the wrmsr() logic, but hopefully we can just remove the wrmsr_on_cpu() version eventually. Reported-and-tested-by: Parag Warudkar <parag.lkml@gmail.com> Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--arch/x86/kernel/cpu/perf_event_intel_ds.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c
index 0e9bdd3cb01e..b05a575d56f4 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_ds.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c
@@ -732,8 +732,10 @@ void intel_ds_init(void)
void perf_restore_debug_store(void)
{
+ struct debug_store *ds = __this_cpu_read(cpu_hw_events.ds);
+
if (!x86_pmu.bts && !x86_pmu.pebs)
return;
- init_debug_store_on_cpu(smp_processor_id());
+ wrmsrl(MSR_IA32_DS_AREA, (unsigned long)ds);
}

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