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| author | Yan, Zheng <zheng.z.yan@intel.com> | 2014-11-04 21:56:10 -0500 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-02-18 17:16:13 +0100 |
| commit | 2c70d0086e4e9e2440f0f78098090f32bde14277 (patch) | |
| tree | adca22321fb3816e114b3ecb9af8ac72127f5ad2 /arch/x86 | |
| parent | 4b854900995194601d767fcd112307b21ed278b2 (diff) | |
| download | op-kernel-dev-2c70d0086e4e9e2440f0f78098090f32bde14277.zip op-kernel-dev-2c70d0086e4e9e2440f0f78098090f32bde14277.tar.gz | |
perf/x86/intel: Disable FREEZE_LBRS_ON_PMI when LBR operates in callstack mode
LBR callstack is designed for PEBS, It does not work well with
FREEZE_LBRS_ON_PMI for non PEBS event. If FREEZE_LBRS_ON_PMI is set for
non PEBS event, PMIs near call/return instructions may cause superfluous
increase/decrease of LBR_TOS.
This patch modifies __intel_pmu_lbr_enable() to not enable
FREEZE_LBRS_ON_PMI when LBR operates in callstack mode. We currently
don't use LBR callstack to capture kernel space callchain, so disabling
FREEZE_LBRS_ON_PMI should not be a problem.
Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Signed-off-by: Kan Liang <kan.liang@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: eranian@google.com
Cc: jolsa@redhat.com
Link: http://lkml.kernel.org/r/1415156173-10035-15-git-send-email-kan.liang@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kernel/cpu/perf_event_intel_lbr.c | 17 |
1 files changed, 13 insertions, 4 deletions
diff --git a/arch/x86/kernel/cpu/perf_event_intel_lbr.c b/arch/x86/kernel/cpu/perf_event_intel_lbr.c index a8b3f23..92a44fd 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c +++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c @@ -131,14 +131,23 @@ static void intel_pmu_lbr_filter(struct cpu_hw_events *cpuc); static void __intel_pmu_lbr_enable(void) { - u64 debugctl; struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); + u64 debugctl, lbr_select = 0; - if (cpuc->lbr_sel) - wrmsrl(MSR_LBR_SELECT, cpuc->lbr_sel->config); + if (cpuc->lbr_sel) { + lbr_select = cpuc->lbr_sel->config; + wrmsrl(MSR_LBR_SELECT, lbr_select); + } rdmsrl(MSR_IA32_DEBUGCTLMSR, debugctl); - debugctl |= (DEBUGCTLMSR_LBR | DEBUGCTLMSR_FREEZE_LBRS_ON_PMI); + debugctl |= DEBUGCTLMSR_LBR; + /* + * LBR callstack does not work well with FREEZE_LBRS_ON_PMI. + * If FREEZE_LBRS_ON_PMI is set, PMI near call/return instructions + * may cause superfluous increase/decrease of LBR_TOS. + */ + if (!(lbr_select & LBR_CALL_STACK)) + debugctl |= DEBUGCTLMSR_FREEZE_LBRS_ON_PMI; wrmsrl(MSR_IA32_DEBUGCTLMSR, debugctl); } |
