+#include <linux/percpu.h>
+#include <linux/version.h>
+#include <asm/local.h>
+#include <lttng-kernel-version.h>
+#include <lttng-clock.h>
+#include <wrapper/percpu-defs.h>
+#include <wrapper/random.h>
+
+#if ((LTTNG_KERNEL_RANGE(3,10,0, 3,10,14) && !LTTNG_RHEL_KERNEL_RANGE(3,10,0,123,0,0, 3,10,14,0,0,0)) \
+ || 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
+
+extern struct lttng_trace_clock *lttng_trace_clock;
+
+/*
+ * Upstream Linux commit 27727df240c7 ("Avoid taking lock in NMI path with
+ * CONFIG_DEBUG_TIMEKEEPING") introduces a buggy ktime_get_mono_fast_ns().
+ * This is fixed by patch "timekeeping: Fix __ktime_get_fast_ns() regression".
+ */
+#if (LTTNG_KERNEL_RANGE(4,8,0, 4,8,2) \
+ || LTTNG_KERNEL_RANGE(4,7,4, 4,7,8) \
+ || LTTNG_KERNEL_RANGE(4,4,20, 4,4,25) \
+ || LTTNG_KERNEL_RANGE(4,1,32, 4,1,35))
+#define LTTNG_CLOCK_NMI_SAFE_BROKEN
+#endif
+
+/*
+ * We need clock values to be monotonically increasing per-cpu, which is
+ * not strictly guaranteed by ktime_get_mono_fast_ns(). It is
+ * straightforward to do on architectures with a 64-bit cmpxchg(), but
+ * not so on architectures without 64-bit cmpxchg. For now, only enable
+ * this feature on 64-bit architectures.
+ */
+
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,17,0) \
+ && BITS_PER_LONG == 64 \
+ && !defined(LTTNG_CLOCK_NMI_SAFE_BROKEN))
+#define LTTNG_USE_NMI_SAFE_CLOCK
+#endif