[v5,05/12] arm: perf: conditionally use PERF_PMU_CAP_NO_EXCLUDE

Commit Message

Andrew Murray Jan. 10, 2019, 1:53 p.m. UTC

The ARM PMU driver can be used to represent a variety of ARM based
PMUs. Some of these PMUs do not provide support for context
exclusion, where this is the case we advertise the
PERF_PMU_CAP_NO_EXCLUDE capability to ensure that perf prevents us
from handling events where any exclusion flags are set.

Where an ARM PMU driver has the set_event_filter function implemented,
we rely on it to perform exclusion checks. At present some of these
functions do not test for all of the available exclude flags.

Signed-off-by: Andrew Murray <[e-mail]>
Acked-by: Will Deacon <[e-mail]>
---
 drivers/perf/arm_pmu.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

Patch

diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index d0b7dd8..eec75b9 100644
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -357,13 +357,6 @@  static irqreturn_t armpmu_dispatch_irq(int irq, void *dev)
 }
 
 static int
-event_requires_mode_exclusion(struct perf_event_attr *attr)
-{
-	return attr->exclude_idle || attr->exclude_user ||
-	       attr->exclude_kernel || attr->exclude_hv;
-}
-
-static int
 __hw_perf_event_init(struct perf_event *event)
 {
 	struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
@@ -393,9 +386,8 @@  __hw_perf_event_init(struct perf_event *event)
 	/*
 	 * Check whether we need to exclude the counter from certain modes.
 	 */
-	if ((!armpmu->set_event_filter ||
-	     armpmu->set_event_filter(hwc, &event->attr)) &&
-	     event_requires_mode_exclusion(&event->attr)) {
+	if (armpmu->set_event_filter &&
+	    armpmu->set_event_filter(hwc, &event->attr)) {
 		pr_debug("ARM performance counters do not support "
 			 "mode exclusion\n");
 		return -EOPNOTSUPP;
@@ -867,6 +859,9 @@  int armpmu_register(struct arm_pmu *pmu)
 	if (ret)
 		return ret;
 
+	if (!pmu->set_event_filter)
+		pmu->pmu.capabilities |= PERF_PMU_CAP_NO_EXCLUDE;
+
 	ret = perf_pmu_register(&pmu->pmu, pmu->name, -1);
 	if (ret)
 		goto out_destroy;