v4.19.13 snapshot.
diff --git a/include/linux/sched_clock.h b/include/linux/sched_clock.h
new file mode 100644
index 0000000..abe28d5
--- /dev/null
+++ b/include/linux/sched_clock.h
@@ -0,0 +1,25 @@
+/*
+ * sched_clock.h: support for extending counters to full 64-bit ns counter
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#ifndef LINUX_SCHED_CLOCK
+#define LINUX_SCHED_CLOCK
+
+#ifdef CONFIG_GENERIC_SCHED_CLOCK
+extern void generic_sched_clock_init(void);
+
+extern void sched_clock_register(u64 (*read)(void), int bits,
+ unsigned long rate);
+#else
+static inline void generic_sched_clock_init(void) { }
+
+static inline void sched_clock_register(u64 (*read)(void), int bits,
+ unsigned long rate)
+{
+}
+#endif
+
+#endif