arm_pmu: Validate single/group leader events

BugLink: https://bugs.launchpad.net/bugs/1972905
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>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index 295cc7952d0edf9d622727357d1c3d607ac4aa0b..57d20cf3da7a39ae3d7b848c5413c09a28b3b6ca 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)