--- /dev/null
+#ifndef _LINUX_TRACE_CLOCK_H
+#define _LINUX_TRACE_CLOCK_H
+
+/*
+ * 3 trace clock variants, with differing scalability/precision
+ * tradeoffs:
+ *
+ * - local: CPU-local trace clock
+ * - medium: scalable global clock with some jitter
+ * - global: globally monotonic, serialized clock
+ */
+#include <linux/compiler.h>
+#include <linux/types.h>
+
+extern u64 notrace trace_clock_local(void);
+extern u64 notrace trace_clock(void);
+extern u64 notrace trace_clock_global(void);
+
+#endif /* _LINUX_TRACE_CLOCK_H */