+#include <linux/percpu.h>
+#include <linux/version.h>
+#include <asm/local.h>
+#include "../lttng-kernel-version.h"
+#include "percpu-defs.h"
+#include "random.h"
+
+#if LTTNG_KERNEL_RANGE(3,10,0, 3,10,14) || LTTNG_KERNEL_RANGE(3,11,0, 3,11,3)
+#error "Linux kernels 3.10 and 3.11 introduce a deadlock in the timekeeping subsystem. Fixed by commit 7bd36014460f793c19e7d6c94dab67b0afcfcb7f \"timekeeping: Fix HRTICK related deadlock from ntp lock changes\" in Linux."
+#endif
+
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0))
+
+DECLARE_PER_CPU(local_t, lttng_last_tsc);
+
+#if (BITS_PER_LONG == 32)
+/*
+ * Fixup "src_now" using the 32 LSB from "last". We need to handle overflow and
+ * underflow of the 32nd bit. "last" can be above, below or equal to the 32 LSB
+ * of "src_now".
+ */
+static inline u64 trace_clock_fixup(u64 src_now, u32 last)
+{
+ u64 now;
+
+ now = src_now & 0xFFFFFFFF00000000ULL;
+ now |= (u64) last;
+ /* Detect overflow or underflow between now and last. */
+ if ((src_now & 0x80000000U) && !(last & 0x80000000U)) {
+ /*
+ * If 32nd bit transitions from 1 to 0, and we move forward in
+ * time from "now" to "last", then we have an overflow.
+ */
+ if (((s32) now - (s32) last) < 0)
+ now += 0x0000000100000000ULL;
+ } else if (!(src_now & 0x80000000U) && (last & 0x80000000U)) {
+ /*
+ * If 32nd bit transitions from 0 to 1, and we move backward in
+ * time from "now" to "last", then we have an underflow.
+ */
+ if (((s32) now - (s32) last) > 0)
+ now -= 0x0000000100000000ULL;
+ }
+ return now;
+}
+#else /* #if (BITS_PER_LONG == 32) */
+/*
+ * The fixup is pretty easy on 64-bit architectures: "last" is a 64-bit
+ * value, so we can use last directly as current time.
+ */
+static inline u64 trace_clock_fixup(u64 src_now, u64 last)
+{
+ return last;
+}
+#endif /* #else #if (BITS_PER_LONG == 32) */