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From: Anshuman Khandual <khandual@linux.vnet.ibm.com>
To: linuxppc-dev@ozlabs.org
Cc: mikey@neuling.org
Subject: [PATCH] powerpc, perf: Clear out branch entries to avoid any previous stale values
Date: Mon,  6 May 2013 12:29:48 +0530	[thread overview]
Message-ID: <1367823588-28871-1-git-send-email-khandual@linux.vnet.ibm.com> (raw)

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(+)

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;
 		}
-- 
1.7.11.7

             reply	other threads:[~2013-05-06  9:51 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-05-06  6:59 Anshuman Khandual [this message]
2013-05-06  8:04 [PATCH] powerpc, perf: Clear out branch entries to avoid any previous stale values Anshuman Khandual
2013-05-06  8:04 ` Anshuman Khandual
2013-05-06 12:53 ` Michael Ellerman
2013-05-06 12:53   ` Michael Ellerman

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