diff options
author | Zhang, Yanmin <yanmin_zhang@linux.intel.com> | 2010-08-06 09:39:08 +0400 |
---|---|---|
committer | Ingo Molnar <mingo@elte.hu> | 2010-08-18 13:17:39 +0400 |
commit | 351af0725e5222e35741011d1ea62215c1ed06db (patch) | |
tree | 1b58323fb9bc7a86c814c3883cd09c3e859b32c3 /arch | |
parent | 9d5f3714e4705a66b6be693f7202192f756f498e (diff) | |
download | linux-351af0725e5222e35741011d1ea62215c1ed06db.tar.xz |
perf, x86: Fix Intel-nhm PMU programming errata workaround
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>
Cc: <stable@kernel.org> # .35.x
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch')
-rw-r--r-- | arch/x86/kernel/cpu/perf_event_intel.c | 81 |
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 214ac860ebe0..d8d86d014008 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); } |