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author | Ingo Molnar <mingo@elte.hu> | 2009-05-26 08:10:00 +0200 |
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committer | Ingo Molnar <mingo@elte.hu> | 2009-05-26 09:52:03 +0200 |
commit | aaba98018b8295dfa2119345d17f833d74448cd0 (patch) | |
tree | 680995e29b5fde045340dbddf3a22f23e72f63c9 /arch/x86/kernel/cpu | |
parent | 79202ba9ff8cf570a75596f42e011167734d1c4b (diff) | |
download | op-kernel-dev-aaba98018b8295dfa2119345d17f833d74448cd0.zip op-kernel-dev-aaba98018b8295dfa2119345d17f833d74448cd0.tar.gz |
perf_counter, x86: Make NMI lockups more robust
We have a debug check that detects stuck NMIs and returns with
the PMU disabled in the global ctrl MSR - but i managed to trigger
a situation where this was not enough to deassert the NMI.
So clear/reset the full PMU and keep the disable count balanced when
exiting from here. This way the box produces a debug warning but
stays up and is more debuggable.
[ Impact: in case of PMU related bugs, recover more gracefully ]
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel/cpu')
-rw-r--r-- | arch/x86/kernel/cpu/perf_counter.c | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c index ece3813..2eeaa99 100644 --- a/arch/x86/kernel/cpu/perf_counter.c +++ b/arch/x86/kernel/cpu/perf_counter.c @@ -724,6 +724,30 @@ static void intel_pmu_save_and_restart(struct perf_counter *counter) intel_pmu_enable_counter(hwc, idx); } +static void intel_pmu_reset(void) +{ + unsigned long flags; + int idx; + + if (!x86_pmu.num_counters) + return; + + local_irq_save(flags); + + printk("clearing PMU state on CPU#%d\n", smp_processor_id()); + + for (idx = 0; idx < x86_pmu.num_counters; idx++) { + checking_wrmsrl(x86_pmu.eventsel + idx, 0ull); + checking_wrmsrl(x86_pmu.perfctr + idx, 0ull); + } + for (idx = 0; idx < x86_pmu.num_counters_fixed; idx++) { + checking_wrmsrl(MSR_ARCH_PERFMON_FIXED_CTR0 + idx, 0ull); + } + + local_irq_restore(flags); +} + + /* * This handler is triggered by the local APIC, so the APIC IRQ handling * rules apply: @@ -750,6 +774,8 @@ again: if (++loops > 100) { WARN_ONCE(1, "perfcounters: irq loop stuck!\n"); perf_counter_print_debug(); + intel_pmu_reset(); + perf_enable(); return 1; } |