linux-kernel - [PATCH 2/3] arm64: perf: Support NMI context for perf event ISR

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Date:   Sat, 16 May 2020 20:48:56 +0800
From:   Lecopzer Chen <lecopzer@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     lecopzer.chen@...iatek.com, linux-arm-kernel@...ts.infradead.org,
        matthias.bgg@...il.com, catalin.marinas@....com, will@...nel.org,
        mark.rutland@....com, mingo@...hat.com, acme@...nel.org,
        jolsa@...hat.com, namhyung@...nel.org,
        linux-mediatek@...ts.infradead.org,
        alexander.shishkin@...ux.intel.com, peterz@...radead.org,
        yj.chiang@...iatek.com, Lecopzer Chen <lecopzer@...il.com>
Subject: [PATCH 2/3] arm64: perf: Support NMI context for perf event ISR

Perf ISR doesn't support for NMI context, thus add some necessary
condition-if to handle NMI context:

- We should not hold pmu_lock since it may have already been acquired
before NMI triggered.
- irq_work should not run at NMI context.

Signed-off-by: Lecopzer Chen <lecopzer.chen@...iatek.com>
---
 arch/arm64/kernel/perf_event.c | 36 +++++++++++++++++++++++++---------
 1 file changed, 27 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
index 4d7879484cec..94b404509f02 100644
--- a/arch/arm64/kernel/perf_event.c
+++ b/arch/arm64/kernel/perf_event.c
@@ -313,6 +313,23 @@ static inline bool armv8pmu_event_is_chained(struct perf_event *event)
 	       (idx != ARMV8_IDX_CYCLE_COUNTER);
 }
 
+/*
+ * NMI Perf interrupts may be triggered during kernel holding
+ * same lock.
+ * Avoid acquiring lock again in NMI context.
+ */
+#define armv8pmu_lock(lock, flags)				\
+	do {							\
+		if (!in_nmi())					\
+			raw_spin_lock_irqsave(lock, flags);	\
+	} while (0)
+
+#define armv8pmu_unlock(lock, flags)				\
+	do {							\
+		if (!in_nmi())					\
+			raw_spin_unlock_irqrestore(lock, flags);\
+	} while (0)
+
 /*
  * ARMv8 low level PMU access
  */
@@ -589,7 +606,7 @@ static void armv8pmu_enable_event(struct perf_event *event)
 	 * Enable counter and interrupt, and set the counter to count
 	 * the event that we're interested in.
 	 */
-	raw_spin_lock_irqsave(&events->pmu_lock, flags);
+	armv8pmu_lock(&events->pmu_lock, flags);
 
 	/*
 	 * Disable counter
@@ -611,7 +628,7 @@ static void armv8pmu_enable_event(struct perf_event *event)
 	 */
 	armv8pmu_enable_event_counter(event);
 
-	raw_spin_unlock_irqrestore(&events->pmu_lock, flags);
+	armv8pmu_unlock(&events->pmu_lock, flags);
 }
 
 static void armv8pmu_disable_event(struct perf_event *event)
@@ -623,7 +640,7 @@ static void armv8pmu_disable_event(struct perf_event *event)
 	/*
 	 * Disable counter and interrupt
 	 */
-	raw_spin_lock_irqsave(&events->pmu_lock, flags);
+	armv8pmu_lock(&events->pmu_lock, flags);
 
 	/*
 	 * Disable counter
@@ -635,7 +652,7 @@ static void armv8pmu_disable_event(struct perf_event *event)
 	 */
 	armv8pmu_disable_event_irq(event);
 
-	raw_spin_unlock_irqrestore(&events->pmu_lock, flags);
+	armv8pmu_unlock(&events->pmu_lock, flags);
 }
 
 static void armv8pmu_start(struct arm_pmu *cpu_pmu)
@@ -643,10 +660,10 @@ static void armv8pmu_start(struct arm_pmu *cpu_pmu)
 	unsigned long flags;
 	struct pmu_hw_events *events = this_cpu_ptr(cpu_pmu->hw_events);
 
-	raw_spin_lock_irqsave(&events->pmu_lock, flags);
+	armv8pmu_lock(&events->pmu_lock, flags);
 	/* Enable all counters */
 	armv8pmu_pmcr_write(armv8pmu_pmcr_read() | ARMV8_PMU_PMCR_E);
-	raw_spin_unlock_irqrestore(&events->pmu_lock, flags);
+	armv8pmu_unlock(&events->pmu_lock, flags);
 }
 
 static void armv8pmu_stop(struct arm_pmu *cpu_pmu)
@@ -654,10 +671,10 @@ static void armv8pmu_stop(struct arm_pmu *cpu_pmu)
 	unsigned long flags;
 	struct pmu_hw_events *events = this_cpu_ptr(cpu_pmu->hw_events);
 
-	raw_spin_lock_irqsave(&events->pmu_lock, flags);
+	armv8pmu_lock(&events->pmu_lock, flags);
 	/* Disable all counters */
 	armv8pmu_pmcr_write(armv8pmu_pmcr_read() & ~ARMV8_PMU_PMCR_E);
-	raw_spin_unlock_irqrestore(&events->pmu_lock, flags);
+	armv8pmu_unlock(&events->pmu_lock, flags);
 }
 
 static irqreturn_t armv8pmu_handle_irq(struct arm_pmu *cpu_pmu)
@@ -722,7 +739,8 @@ static irqreturn_t armv8pmu_handle_irq(struct arm_pmu *cpu_pmu)
 	 * platforms that can have the PMU interrupts raised as an NMI, this
 	 * will not work.
 	 */
-	irq_work_run();
+	if (!armpmu_support_nmi())
+		irq_work_run();
 
 	return IRQ_HANDLED;
 }
-- 
2.25.1