+/*
+ * Lost/dropped samples logging
+ */
+void perf_log_lost_samples(struct perf_event *event, u64 lost)
+{
+ struct perf_output_handle handle;
+ struct perf_sample_data sample;
+ int ret;
+
+ struct {
+ struct perf_event_header header;
+ u64 lost;
+ } lost_samples_event = {
+ .header = {
+ .type = PERF_RECORD_LOST_SAMPLES,
+ .misc = 0,
+ .size = sizeof(lost_samples_event),
+ },
+ .lost = lost,
+ };
+
+ perf_event_header__init_id(&lost_samples_event.header, &sample, event);
+
+ ret = perf_output_begin(&handle, event,
+ lost_samples_event.header.size);
+ if (ret)
+ return;
+
+ perf_output_put(&handle, lost_samples_event);
+ perf_event__output_id_sample(event, &handle, &sample);
+ perf_output_end(&handle);
+}
+
+/*
+ * context_switch tracking
+ */
+
+struct perf_switch_event {
+ struct task_struct *task;
+ struct task_struct *next_prev;
+
+ struct {
+ struct perf_event_header header;
+ u32 next_prev_pid;
+ u32 next_prev_tid;
+ } event_id;
+};
+
+static int perf_event_switch_match(struct perf_event *event)
+{
+ return event->attr.context_switch;
+}
+
+static void perf_event_switch_output(struct perf_event *event, void *data)
+{
+ struct perf_switch_event *se = data;
+ struct perf_output_handle handle;
+ struct perf_sample_data sample;
+ int ret;
+
+ if (!perf_event_switch_match(event))
+ return;
+
+ /* Only CPU-wide events are allowed to see next/prev pid/tid */
+ if (event->ctx->task) {
+ se->event_id.header.type = PERF_RECORD_SWITCH;
+ se->event_id.header.size = sizeof(se->event_id.header);
+ } else {
+ se->event_id.header.type = PERF_RECORD_SWITCH_CPU_WIDE;
+ se->event_id.header.size = sizeof(se->event_id);
+ se->event_id.next_prev_pid =
+ perf_event_pid(event, se->next_prev);
+ se->event_id.next_prev_tid =
+ perf_event_tid(event, se->next_prev);
+ }
+
+ perf_event_header__init_id(&se->event_id.header, &sample, event);
+
+ ret = perf_output_begin(&handle, event, se->event_id.header.size);
+ if (ret)
+ return;
+
+ if (event->ctx->task)
+ perf_output_put(&handle, se->event_id.header);
+ else
+ perf_output_put(&handle, se->event_id);
+
+ perf_event__output_id_sample(event, &handle, &sample);
+
+ perf_output_end(&handle);
+}
+
+static void perf_event_switch(struct task_struct *task,
+ struct task_struct *next_prev, bool sched_in)
+{
+ struct perf_switch_event switch_event;
+
+ /* N.B. caller checks nr_switch_events != 0 */
+
+ switch_event = (struct perf_switch_event){
+ .task = task,
+ .next_prev = next_prev,
+ .event_id = {
+ .header = {
+ /* .type */
+ .misc = sched_in ? 0 : PERF_RECORD_MISC_SWITCH_OUT,
+ /* .size */
+ },
+ /* .next_prev_pid */
+ /* .next_prev_tid */
+ },
+ };
+
+ perf_event_aux(perf_event_switch_output,
+ &switch_event,
+ NULL);
+}
+