From e5c23779f93d45e39a52758ca593bd7e62e9b4be Mon Sep 17 00:00:00 2001
From: Rob Herring <robh@kernel.org>
Date: Fri, 8 Apr 2022 15:33:30 -0500
Subject: [PATCH] arm_pmu: Validate single/group leader events
Git-commit: e5c23779f93d45e39a52758ca593bd7e62e9b4be
Patch-mainline: v5.18-rc4
References: git-fixes

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>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/perf/arm_pmu.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index 9694370651fa..59d3980b8ca2 100644
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -400,6 +400,9 @@ 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;
@@ -489,12 +492,7 @@ __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)
-- 
2.35.3