perf/arm_cspmu: Generalise event filtering

The notion of a single u32 filter value for any event doesn't scale well
when the potential architectural scope is already two 64-bit values, and
implementations may add custom stuff on the side too. Rather than try to
thread arbitrary filter data through the common path, let's just make
the set_ev_filter op self-contained in terms of parsing and configuring
any and all filtering for the given event - splitting out a distinct op
for cycles events which inherently differ - and let implementations
override the whole thing if they want to do something different. This
already allows the Ampere code to stop looking a bit hacky.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: James Clark <james.clark@linaro.org>
Reviewed-by: Ilkka Koskinen <ilkka@os.amperecomputing.com>
Link: https://lore.kernel.org/r/c0cd4d4c12566dbf1b062ccd60241b3e0639f4cc.1741190362.git.robin.murphy@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

drivers/perf/arm_cspmu/ampere_cspmu.c

@@ -132,32 +132,20 @@ ampere_cspmu_get_name(const struct arm_cspmu *cspmu)
 	return ctx->name;
 }
 
-static u32 ampere_cspmu_event_filter(const struct perf_event *event)
+static void ampere_cspmu_set_cc_filter(struct arm_cspmu *cspmu,
+				       const struct perf_event *event)
 {
 	/*
-	 * PMEVFILTR or PMCCFILTR aren't used in Ampere SoC PMU but are marked
-	 * as RES0. Make sure, PMCCFILTR is written zero.
+	 * PMCCFILTR is RES0, so this is just a dummy callback to override
+	 * the default implementation and avoid writing to it.
 	 */
-	return 0;
 }
 
 static void ampere_cspmu_set_ev_filter(struct arm_cspmu *cspmu,
-				       struct hw_perf_event *hwc,
-				       u32 filter)
+				       const struct perf_event *event)
 {
-	struct perf_event *event;
-	unsigned int idx;
 	u32 threshold, rank, bank;
 
-	/*
-	 * At this point, all the events have the same filter settings.
-	 * Therefore, take the first event and use its configuration.
-	 */
-	idx = find_first_bit(cspmu->hw_events.used_ctrs,
-			     cspmu->cycle_counter_logical_idx);
-
-	event = cspmu->hw_events.events[idx];
-
 	threshold	= get_threshold(event);
 	rank		= get_rank(event);
 	bank		= get_bank(event);
@@ -233,7 +221,7 @@ static int ampere_cspmu_init_ops(struct arm_cspmu *cspmu)
 
 	cspmu->impl.ctx = ctx;
 
-	impl_ops->event_filter		= ampere_cspmu_event_filter;
+	impl_ops->set_cc_filter		= ampere_cspmu_set_cc_filter;
 	impl_ops->set_ev_filter		= ampere_cspmu_set_ev_filter;
 	impl_ops->validate_event	= ampere_cspmu_validate_event;
 	impl_ops->get_name		= ampere_cspmu_get_name;

drivers/perf/arm_cspmu/arm_cspmu.c

@@ -66,7 +66,9 @@ static unsigned long arm_cspmu_cpuhp_state;
 static DEFINE_MUTEX(arm_cspmu_lock);
 
 static void arm_cspmu_set_ev_filter(struct arm_cspmu *cspmu,
-				    struct hw_perf_event *hwc, u32 filter);
+				    const struct perf_event *event);
+static void arm_cspmu_set_cc_filter(struct arm_cspmu *cspmu,
+				    const struct perf_event *event);
 
 static struct acpi_apmt_node *arm_cspmu_apmt_node(struct device *dev)
 {
@@ -205,11 +207,6 @@ static bool arm_cspmu_is_cycle_counter_event(const struct perf_event *event)
 	return (event->attr.config == ARM_CSPMU_EVT_CYCLES_DEFAULT);
 }
 
-static u32 arm_cspmu_event_filter(const struct perf_event *event)
-{
-	return event->attr.config1 & ARM_CSPMU_FILTER_MASK;
-}
-
 static ssize_t arm_cspmu_identifier_show(struct device *dev,
 					 struct device_attribute *attr,
 					 char *page)
@@ -371,7 +368,7 @@ static int arm_cspmu_init_impl_ops(struct arm_cspmu *cspmu)
 		DEFAULT_IMPL_OP(get_name),
 		DEFAULT_IMPL_OP(is_cycle_counter_event),
 		DEFAULT_IMPL_OP(event_type),
-		DEFAULT_IMPL_OP(event_filter),
+		DEFAULT_IMPL_OP(set_cc_filter),
 		DEFAULT_IMPL_OP(set_ev_filter),
 		DEFAULT_IMPL_OP(event_attr_is_visible),
 	};
@@ -767,26 +764,26 @@ static inline void arm_cspmu_set_event(struct arm_cspmu *cspmu,
 }
 
 static void arm_cspmu_set_ev_filter(struct arm_cspmu *cspmu,
-					struct hw_perf_event *hwc,
-					u32 filter)
+				    const struct perf_event *event)
 {
+	u32 filter = event->attr.config1 & ARM_CSPMU_FILTER_MASK;
 	u32 offset = PMEVFILTR + (4 * hwc->idx);
 
 	writel(filter, cspmu->base0 + offset);
 }
 
-static inline void arm_cspmu_set_cc_filter(struct arm_cspmu *cspmu, u32 filter)
+static void arm_cspmu_set_cc_filter(struct arm_cspmu *cspmu,
+				    const struct perf_event *event)
 {
-	u32 offset = PMCCFILTR;
+	u32 filter = event->attr.config1 & ARM_CSPMU_FILTER_MASK;
 
-	writel(filter, cspmu->base0 + offset);
+	writel(filter, cspmu->base0 + PMCCFILTR);
 }
 
 static void arm_cspmu_start(struct perf_event *event, int pmu_flags)
 {
 	struct arm_cspmu *cspmu = to_arm_cspmu(event->pmu);
 	struct hw_perf_event *hwc = &event->hw;
-	u32 filter;
 
 	/* We always reprogram the counter */
 	if (pmu_flags & PERF_EF_RELOAD)
@@ -794,13 +791,11 @@ static void arm_cspmu_start(struct perf_event *event, int pmu_flags)
 
 	arm_cspmu_set_event_period(event);
 
-	filter = cspmu->impl.ops.event_filter(event);
-
 	if (event->hw.extra_reg.idx == cspmu->cycle_counter_logical_idx) {
-		arm_cspmu_set_cc_filter(cspmu, filter);
+		cspmu->impl.ops.set_cc_filter(cspmu, event);
 	} else {
 		arm_cspmu_set_event(cspmu, hwc);
-		cspmu->impl.ops.set_ev_filter(cspmu, hwc, filter);
+		cspmu->impl.ops.set_ev_filter(cspmu, event);
 	}
 
 	hwc->state = 0;

drivers/perf/arm_cspmu/arm_cspmu.h

@@ -149,11 +149,11 @@ struct arm_cspmu_impl_ops {
 	bool (*is_cycle_counter_event)(const struct perf_event *event);
 	/* Decode event type/id from configs */
 	u32 (*event_type)(const struct perf_event *event);
-	/* Decode filter value from configs */
-	u32 (*event_filter)(const struct perf_event *event);
-	/* Set event filter */
+	/* Set event filters */
+	void (*set_cc_filter)(struct arm_cspmu *cspmu,
+			      const struct perf_event *event);
 	void (*set_ev_filter)(struct arm_cspmu *cspmu,
-			      struct hw_perf_event *hwc, u32 filter);
+			      const struct perf_event *event);
 	/* Implementation specific event validation */
 	int (*validate_event)(struct arm_cspmu *cspmu,
 			      struct perf_event *event);

drivers/perf/arm_cspmu/nvidia_cspmu.c

@@ -183,6 +183,24 @@ static u32 nv_cspmu_event_filter(const struct perf_event *event)
 	return filter_val;
 }
 
+static void nv_cspmu_set_ev_filter(struct arm_cspmu *cspmu,
+				   const struct perf_event *event)
+{
+	u32 filter = nv_cspmu_event_filter(event);
+	u32 offset = PMEVFILTR + (4 * event->hw.idx);
+
+	writel(filter, cspmu->base0 + offset);
+}
+
+static void nv_cspmu_set_cc_filter(struct arm_cspmu *cspmu,
+				   const struct perf_event *event)
+{
+	u32 filter = nv_cspmu_event_filter(event);
+
+	writel(filter, cspmu->base0 + PMCCFILTR);
+}
+
+
 enum nv_cspmu_name_fmt {
 	NAME_FMT_GENERIC,
 	NAME_FMT_SOCKET
@@ -322,7 +340,8 @@ static int nv_cspmu_init_ops(struct arm_cspmu *cspmu)
 	cspmu->impl.ctx = ctx;
 
 	/* NVIDIA specific callbacks. */
-	impl_ops->event_filter			= nv_cspmu_event_filter;
+	impl_ops->set_cc_filter			= nv_cspmu_set_cc_filter;
+	impl_ops->set_ev_filter			= nv_cspmu_set_ev_filter;
 	impl_ops->get_event_attrs		= nv_cspmu_get_event_attrs;
 	impl_ops->get_format_attrs		= nv_cspmu_get_format_attrs;
 	impl_ops->get_name			= nv_cspmu_get_name;