#define PERF_PMU_CAP_ITRACE 0x20
#define PERF_PMU_CAP_HETEROGENEOUS_CPUS 0x40
#define PERF_PMU_CAP_NO_EXCLUDE 0x80
+#define PERF_PMU_CAP_AUX_OUTPUT 0x100
/**
* struct pmu - generic performance monitoring unit
void (*addr_filters_sync) (struct perf_event *event);
/* optional */
+ /*
+ * Check if event can be used for aux_output purposes for
+ * events of this PMU.
+ *
+ * Runs from perf_event_open(). Should return 0 for "no match"
+ * or non-zero for "match".
+ */
+ int (*aux_output_match) (struct perf_event *event);
+ /* optional */
+
/*
* Filter events for PMU-specific reasons.
*/
struct perf_addr_filter_range *addr_filter_ranges;
unsigned long addr_filters_gen;
+ /* for aux_output events */
+ struct perf_event *aux_event;
+
void (*destroy)(struct perf_event *);
struct rcu_head rcu_head;
ctx->generation++;
}
+static int
+perf_aux_output_match(struct perf_event *event, struct perf_event *aux_event)
+{
+ if (!has_aux(aux_event))
+ return 0;
+
+ if (!event->pmu->aux_output_match)
+ return 0;
+
+ return event->pmu->aux_output_match(aux_event);
+}
+
+static void put_event(struct perf_event *event);
+static void event_sched_out(struct perf_event *event,
+ struct perf_cpu_context *cpuctx,
+ struct perf_event_context *ctx);
+
+static void perf_put_aux_event(struct perf_event *event)
+{
+ struct perf_event_context *ctx = event->ctx;
+ struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+ struct perf_event *iter;
+
+ /*
+ * If event uses aux_event tear down the link
+ */
+ if (event->aux_event) {
+ iter = event->aux_event;
+ event->aux_event = NULL;
+ put_event(iter);
+ return;
+ }
+
+ /*
+ * If the event is an aux_event, tear down all links to
+ * it from other events.
+ */
+ for_each_sibling_event(iter, event->group_leader) {
+ if (iter->aux_event != event)
+ continue;
+
+ iter->aux_event = NULL;
+ put_event(event);
+
+ /*
+ * If it's ACTIVE, schedule it out and put it into ERROR
+ * state so that we don't try to schedule it again. Note
+ * that perf_event_enable() will clear the ERROR status.
+ */
+ event_sched_out(iter, cpuctx, ctx);
+ perf_event_set_state(event, PERF_EVENT_STATE_ERROR);
+ }
+}
+
+static int perf_get_aux_event(struct perf_event *event,
+ struct perf_event *group_leader)
+{
+ /*
+ * Our group leader must be an aux event if we want to be
+ * an aux_output. This way, the aux event will precede its
+ * aux_output events in the group, and therefore will always
+ * schedule first.
+ */
+ if (!group_leader)
+ return 0;
+
+ if (!perf_aux_output_match(event, group_leader))
+ return 0;
+
+ if (!atomic_long_inc_not_zero(&group_leader->refcount))
+ return 0;
+
+ /*
+ * Link aux_outputs to their aux event; this is undone in
+ * perf_group_detach() by perf_put_aux_event(). When the
+ * group in torn down, the aux_output events loose their
+ * link to the aux_event and can't schedule any more.
+ */
+ event->aux_event = group_leader;
+
+ return 1;
+}
+
static void perf_group_detach(struct perf_event *event)
{
struct perf_event *sibling, *tmp;
event->attach_state &= ~PERF_ATTACH_GROUP;
+ perf_put_aux_event(event);
+
/*
* If this is a sibling, remove it from its group.
*/
goto err_ns;
}
+ if (event->attr.aux_output &&
+ !(pmu->capabilities & PERF_PMU_CAP_AUX_OUTPUT)) {
+ err = -EOPNOTSUPP;
+ goto err_pmu;
+ }
+
err = exclusive_event_init(event);
if (err)
goto err_pmu;
}
}
+ if (event->attr.aux_output && !perf_get_aux_event(event, group_leader))
+ goto err_locked;
/*
* Must be under the same ctx::mutex as perf_install_in_context(),