powerpc, perf: Clear out branch entries to avoid any previous stale values

Submitted by Anshuman Khandual on May 6, 2013, 6:59 a.m.

Details

Message ID 1367823588-28871-1-git-send-email-khandual@linux.vnet.ibm.com
State Superseded
Headers show

Commit Message

Anshuman Khandual May 6, 2013, 6:59 a.m.
The 'to' field inside branch entries might contain stale values from previous
PMU interrupt instances which had indirect branches. So clear all the values
before reading a fresh set of BHRB entries after a PMU interrupt.

Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
---
 arch/powerpc/perf/core-book3s.c | 2 ++
 1 file changed, 2 insertions(+)

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diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index c627843..09db68d 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -1590,6 +1590,8 @@  static void record_and_restart(struct perf_event *event, unsigned long val,
 		if (event->attr.sample_type & PERF_SAMPLE_BRANCH_STACK) {
 			struct cpu_hw_events *cpuhw;
 			cpuhw = &__get_cpu_var(cpu_hw_events);
+			memset(cpuhw->bhrb_entries, 0,
+				sizeof(struct perf_branch_entry) * BHRB_MAX_ENTRIES);
 			power_pmu_bhrb_read(cpuhw);
 			data.br_stack = &cpuhw->bhrb_stack;
 		}