1 files changed, 14 insertions, 0 deletions

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 116b040a73a8..f8bddb5b0600 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -32,6 +32,7 @@
 #include <asm/compat.h>
 #include <asm/smp.h>
 #include <asm/alternative.h>
+#include <asm/timer.h>
 
 #include "perf_event.h"
 
@@ -1627,6 +1628,19 @@ static struct pmu pmu = {
         .event_idx      = x86_pmu_event_idx,
 };
 
+void perf_update_user_clock(struct perf_event_mmap_page *userpg, u64 now)
+{
+        if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC))
+                return;
+
+        if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
+                return;
+
+        userpg->time_mult = this_cpu_read(cyc2ns);
+        userpg->time_shift = CYC2NS_SCALE_FACTOR;
+        userpg->time_offset = this_cpu_read(cyc2ns_offset) - now;
+}
+
 /*
  * callchain support
  */