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authorZhang, Yanmin <yanmin_zhang@linux.intel.com>2010-08-06 13:39:08 +0800
committerGreg Kroah-Hartman <gregkh@suse.de>2010-08-26 16:45:50 -0700
commit05a939449fc6998700eb5264feee9206a6d6e6f6 (patch)
treed8a20b5a819f820a7c45df010ca345980e6810fe /arch
parent6105020a90881ab1916a632532948255c9d28a8f (diff)
downloadlinux-linaro-05a939449fc6998700eb5264feee9206a6d6e6f6.tar.gz
perf, x86: Fix Intel-nhm PMU programming errata workaround
commit 351af0725e5222e35741011d1ea62215c1ed06db upstream. Fix the Errata AAK100/AAP53/BD53 workaround, the officialy documented workaround we implemented in: 11164cd: perf, x86: Add Nehelem PMU programming errata workaround doesn't actually work fully and causes a stuck PMU state under load and non-functioning perf profiling. A functional workaround was found by trial & error. Affects all Nehalem-class Intel PMUs. Signed-off-by: Zhang Yanmin <yanmin_zhang@linux.intel.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1281073148.2125.63.camel@ymzhang.sh.intel.com> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/cpu/perf_event_intel.c81
1 files changed, 63 insertions, 18 deletions
diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
index 214ac860ebe..d8d86d01400 100644
--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -491,33 +491,78 @@ static void intel_pmu_enable_all(int added)
* Intel Errata AAP53 (model 30)
* Intel Errata BD53 (model 44)
*
- * These chips need to be 'reset' when adding counters by programming
- * the magic three (non counting) events 0x4300D2, 0x4300B1 and 0x4300B5
- * either in sequence on the same PMC or on different PMCs.
+ * The official story:
+ * These chips need to be 'reset' when adding counters by programming the
+ * magic three (non-counting) events 0x4300B5, 0x4300D2, and 0x4300B1 either
+ * in sequence on the same PMC or on different PMCs.
+ *
+ * In practise it appears some of these events do in fact count, and
+ * we need to programm all 4 events.
*/
-static void intel_pmu_nhm_enable_all(int added)
+static void intel_pmu_nhm_workaround(void)
{
- if (added) {
- struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
- int i;
+ struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+ static const unsigned long nhm_magic[4] = {
+ 0x4300B5,
+ 0x4300D2,
+ 0x4300B1,
+ 0x4300B1
+ };
+ struct perf_event *event;
+ int i;
+
+ /*
+ * The Errata requires below steps:
+ * 1) Clear MSR_IA32_PEBS_ENABLE and MSR_CORE_PERF_GLOBAL_CTRL;
+ * 2) Configure 4 PERFEVTSELx with the magic events and clear
+ * the corresponding PMCx;
+ * 3) set bit0~bit3 of MSR_CORE_PERF_GLOBAL_CTRL;
+ * 4) Clear MSR_CORE_PERF_GLOBAL_CTRL;
+ * 5) Clear 4 pairs of ERFEVTSELx and PMCx;
+ */
+
+ /*
+ * The real steps we choose are a little different from above.
+ * A) To reduce MSR operations, we don't run step 1) as they
+ * are already cleared before this function is called;
+ * B) Call x86_perf_event_update to save PMCx before configuring
+ * PERFEVTSELx with magic number;
+ * C) With step 5), we do clear only when the PERFEVTSELx is
+ * not used currently.
+ * D) Call x86_perf_event_set_period to restore PMCx;
+ */
- wrmsrl(MSR_ARCH_PERFMON_EVENTSEL0 + 0, 0x4300D2);
- wrmsrl(MSR_ARCH_PERFMON_EVENTSEL0 + 1, 0x4300B1);
- wrmsrl(MSR_ARCH_PERFMON_EVENTSEL0 + 2, 0x4300B5);
+ /* We always operate 4 pairs of PERF Counters */
+ for (i = 0; i < 4; i++) {
+ event = cpuc->events[i];
+ if (event)
+ x86_perf_event_update(event);
+ }
- wrmsrl(MSR_CORE_PERF_GLOBAL_CTRL, 0x3);
- wrmsrl(MSR_CORE_PERF_GLOBAL_CTRL, 0x0);
+ for (i = 0; i < 4; i++) {
+ wrmsrl(MSR_ARCH_PERFMON_EVENTSEL0 + i, nhm_magic[i]);
+ wrmsrl(MSR_ARCH_PERFMON_PERFCTR0 + i, 0x0);
+ }
- for (i = 0; i < 3; i++) {
- struct perf_event *event = cpuc->events[i];
+ wrmsrl(MSR_CORE_PERF_GLOBAL_CTRL, 0xf);
+ wrmsrl(MSR_CORE_PERF_GLOBAL_CTRL, 0x0);
- if (!event)
- continue;
+ for (i = 0; i < 4; i++) {
+ event = cpuc->events[i];
+ if (event) {
+ x86_perf_event_set_period(event);
__x86_pmu_enable_event(&event->hw,
- ARCH_PERFMON_EVENTSEL_ENABLE);
- }
+ ARCH_PERFMON_EVENTSEL_ENABLE);
+ } else
+ wrmsrl(MSR_ARCH_PERFMON_EVENTSEL0 + i, 0x0);
}
+}
+
+static void intel_pmu_nhm_enable_all(int added)
+{
+ if (added)
+ intel_pmu_nhm_workaround();
intel_pmu_enable_all(added);
}