[PATCH v8 4/6] arm64: perf: extract chain helper into header

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The ARMv8 Performance Monitors Extension includes an architectural
event type named CHAIN which allows for chaining counters together.

Let's extract the test for this event into a header file such that
other users, such as KVM (for PMU emulation) can make use of.

Signed-off-by: Andrew Murray <andrew.murray@xxxxxxx>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
---
 arch/arm64/include/asm/perf_event.h | 5 +++++
 arch/arm64/kernel/perf_event.c      | 2 +-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/perf_event.h b/arch/arm64/include/asm/perf_event.h
index c593761ba61c..cd13f3fd1055 100644
--- a/arch/arm64/include/asm/perf_event.h
+++ b/arch/arm64/include/asm/perf_event.h
@@ -219,6 +219,11 @@
 #define ARMV8_PMU_USERENR_CR	(1 << 2) /* Cycle counter can be read at EL0 */
 #define ARMV8_PMU_USERENR_ER	(1 << 3) /* Event counter can be read at EL0 */
 
+static inline bool armv8pmu_evtype_is_chain(u64 evtype)
+{
+	return (evtype == ARMV8_PMUV3_PERFCTR_CHAIN);
+}
+
 #ifdef CONFIG_PERF_EVENTS
 struct pt_regs;
 extern unsigned long perf_instruction_pointer(struct pt_regs *regs);
diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
index 314b1adedf06..265bd835a724 100644
--- a/arch/arm64/kernel/perf_event.c
+++ b/arch/arm64/kernel/perf_event.c
@@ -879,7 +879,7 @@ static int armv8pmu_set_event_filter(struct hw_perf_event *event,
 static int armv8pmu_filter_match(struct perf_event *event)
 {
 	unsigned long evtype = event->hw.config_base & ARMV8_PMU_EVTYPE_EVENT;
-	return evtype != ARMV8_PMUV3_PERFCTR_CHAIN;
+	return !armv8pmu_evtype_is_chain(evtype);
 }
 
 static void armv8pmu_reset(void *info)
-- 
2.21.0

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