linux-kernel - [PATCH] perf: arm_pmuv3: Fix chained event check for cycle counter

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Message-ID: <20240710182357.3701635-1-robh@kernel.org>
Date: Wed, 10 Jul 2024 12:23:56 -0600
From: "Rob Herring (Arm)" <robh@...nel.org>
To: Will Deacon <will@...nel.org>,
	Mark Rutland <mark.rutland@....com>
Cc: linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] perf: arm_pmuv3: Fix chained event check for cycle counter

Since commit b7e89b0f5bd7 ("perf: arm_pmu: Remove event index to
counter remapping"), armv8pmu_event_is_chained() is incorrectly
returning that the cycle counter is chained, but the cycle counter has
always been 64-bit. The result is trying to configure counter #30 which
typically doesn't exist.

As ARMV8_PMU_MAX_GENERAL_COUNTERS is the number of counters (31), the
comparison to the counter index needs to be '<' rather than '<='.

Fixes: b7e89b0f5bd7 ("perf: arm_pmu: Remove event index to counter remapping")
Signed-off-by: Rob Herring (Arm) <robh@...nel.org>
---
 drivers/perf/arm_pmuv3.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/perf/arm_pmuv3.c b/drivers/perf/arm_pmuv3.c
index 3b3a3334cc3f..0e22c68fb804 100644
--- a/drivers/perf/arm_pmuv3.c
+++ b/drivers/perf/arm_pmuv3.c
@@ -482,7 +482,7 @@ static bool armv8pmu_event_is_chained(struct perf_event *event)
 	return !armv8pmu_event_has_user_read(event) &&
 	       armv8pmu_event_is_64bit(event) &&
 	       !armv8pmu_has_long_event(cpu_pmu) &&
-	       (idx <= ARMV8_PMU_MAX_GENERAL_COUNTERS);
+	       (idx < ARMV8_PMU_MAX_GENERAL_COUNTERS);
 }
 
 /*
-- 
2.43.0