bpf: perf event change needed for subsequent bpf helpers

This patch does not impact existing functionalities.
It contains the changes in perf event area needed for
subsequent bpf_perf_event_read_value and
bpf_perf_prog_read_value helpers.
Signed-off-by: NYonghong Song <yhs@fb.com>
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/perf_event.h

@@ -806,6 +806,7 @@ struct perf_output_handle {
 struct bpf_perf_event_data_kern {
 	struct pt_regs *regs;
 	struct perf_sample_data *data;
+	struct perf_event *event;
 };
 
 #ifdef CONFIG_CGROUP_PERF
@@ -884,7 +885,8 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr,
 				void *context);
 extern void perf_pmu_migrate_context(struct pmu *pmu,
 				int src_cpu, int dst_cpu);
-int perf_event_read_local(struct perf_event *event, u64 *value);
+int perf_event_read_local(struct perf_event *event, u64 *value,
+			  u64 *enabled, u64 *running);
 extern u64 perf_event_read_value(struct perf_event *event,
 				 u64 *enabled, u64 *running);
 
@@ -1286,7 +1288,8 @@ static inline const struct perf_event_attr *perf_event_attrs(struct perf_event *
 {
 	return ERR_PTR(-EINVAL);
 }
-static inline int perf_event_read_local(struct perf_event *event, u64 *value)
+static inline int perf_event_read_local(struct perf_event *event, u64 *value,
+					u64 *enabled, u64 *running)
 {
 	return -EINVAL;
 }

kernel/bpf/arraymap.c

@@ -492,7 +492,7 @@ static void *perf_event_fd_array_get_ptr(struct bpf_map *map,
 
 	ee = ERR_PTR(-EOPNOTSUPP);
 	event = perf_file->private_data;
-	if (perf_event_read_local(event, &value) == -EOPNOTSUPP)
+	if (perf_event_read_local(event, &value, NULL, NULL) == -EOPNOTSUPP)
 		goto err_out;
 
 	ee = bpf_event_entry_gen(perf_file, map_file);

kernel/events/core.c

@@ -3684,10 +3684,12 @@ static inline u64 perf_event_count(struct perf_event *event)
  *     will not be local and we cannot read them atomically
  *   - must not have a pmu::count method
  */
-int perf_event_read_local(struct perf_event *event, u64 *value)
+int perf_event_read_local(struct perf_event *event, u64 *value,
+			  u64 *enabled, u64 *running)
 {
 	unsigned long flags;
 	int ret = 0;
+	u64 now;
 
 	/*
 	 * Disabling interrupts avoids all counter scheduling (context
@@ -3718,13 +3720,21 @@ int perf_event_read_local(struct perf_event *event, u64 *value)
 		goto out;
 	}
 
+	now = event->shadow_ctx_time + perf_clock();
+	if (enabled)
+		*enabled = now - event->tstamp_enabled;
 	/*
 	 * If the event is currently on this CPU, its either a per-task event,
 	 * or local to this CPU. Furthermore it means its ACTIVE (otherwise
 	 * oncpu == -1).
 	 */
-	if (event->oncpu == smp_processor_id())
+	if (event->oncpu == smp_processor_id()) {
 		event->pmu->read(event);
+		if (running)
+			*running = now - event->tstamp_running;
+	} else if (running) {
+		*running = event->total_time_running;
+	}
 
 	*value = local64_read(&event->count);
 out:
@@ -8072,6 +8082,7 @@ static void bpf_overflow_handler(struct perf_event *event,
 	struct bpf_perf_event_data_kern ctx = {
 		.data = data,
 		.regs = regs,
+		.event = event,
 	};
 	int ret = 0;
 

kernel/trace/bpf_trace.c

@@ -275,7 +275,7 @@ BPF_CALL_2(bpf_perf_event_read, struct bpf_map *, map, u64, flags)
 	if (!ee)
 		return -ENOENT;
 
-	err = perf_event_read_local(ee->event, &value);
+	err = perf_event_read_local(ee->event, &value, NULL, NULL);
 	/*
 	 * this api is ugly since we miss [-22..-2] range of valid
 	 * counter values, but that's uapi