#include "util/types.h"
#include <stdbool.h>
+struct perf_mmap {
+ void *base;
+ int mask;
+ unsigned int prev;
+};
+
+static inline unsigned int perf_mmap__read_head(struct perf_mmap *mm)
+{
+ struct perf_event_mmap_page *pc = mm->base;
+ int head = pc->data_head;
+ rmb();
+ return head;
+}
+
+static inline void perf_mmap__write_tail(struct perf_mmap *md,
+ unsigned long tail)
+{
+ struct perf_event_mmap_page *pc = md->base;
+
+ /*
+ * ensure all reads are done before we write the tail out.
+ */
+ /* mb(); */
+ pc->data_tail = tail;
+}
+
/*
* prctl(PR_TASK_PERF_EVENTS_DISABLE) will (cheaply) disable all
* counters in the current task.