arm_pmu: Validate single/group leader events

commit e5c23779f93d45e39a52758ca593bd7e62e9b4be upstream.

In the case where there is only a cycle counter available (i.e.
PMCR_EL0.N is 0) and an event other than CPU cycles is opened, the open
should fail as the event can never possibly be scheduled. However, the
event validation when an event is opened is skipped when the group
leader is opened. Fix this by always validating the group leader events.

Reported-by: Al Grant <al.grant@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20220408203330.4014015-1-robh@kernel.org
Cc: <stable@vger.kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index cb2f55f450e4adf05a7b3d81e8b9a01230665584..7fd11ef5cb8a2c285c9a6a0d2c8396513deeadcf 100644 (file)
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -398,6 +398,9 @@ validate_group(struct perf_event *event)
        if (!validate_event(event->pmu, &fake_pmu, leader))
                return -EINVAL;
 
+       if (event == leader)
+               return 0;
+
        for_each_sibling_event(sibling, leader) {
                if (!validate_event(event->pmu, &fake_pmu, sibling))
                        return -EINVAL;
@@ -487,12 +490,7 @@ __hw_perf_event_init(struct perf_event *event)
                local64_set(&hwc->period_left, hwc->sample_period);
        }
 
-       if (event->group_leader != event) {
-               if (validate_group(event) != 0)
-                       return -EINVAL;
-       }
-
-       return 0;
+       return validate_group(event);
 }
 
 static int armpmu_event_init(struct perf_event *event)