1 files changed, 17 insertions, 3 deletions

diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 4be1a8d872b4..b7a027a2ef02 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -928,18 +928,32 @@ static const struct file_operations perf_fops = {
 
 static int cpu_clock_perf_counter_enable(struct perf_counter *counter)
 {
+        int cpu = raw_smp_processor_id();
+
+        atomic64_set(&counter->hw.prev_count, cpu_clock(cpu));
         return 0;
 }
 
+static void cpu_clock_perf_counter_update(struct perf_counter *counter)
+{
+        int cpu = raw_smp_processor_id();
+        s64 prev;
+        u64 now;
+
+        now = cpu_clock(cpu);
+        prev = atomic64_read(&counter->hw.prev_count);
+        atomic64_set(&counter->hw.prev_count, now);
+        atomic64_add(now - prev, &counter->count);
+}
+
 static void cpu_clock_perf_counter_disable(struct perf_counter *counter)
 {
+        cpu_clock_perf_counter_update(counter);
 }
 
 static void cpu_clock_perf_counter_read(struct perf_counter *counter)
 {
-        int cpu = raw_smp_processor_id();
-
-        atomic64_set(&counter->count, cpu_clock(cpu));
+        cpu_clock_perf_counter_update(counter);
 }
 
 static const struct hw_perf_counter_ops perf_ops_cpu_clock = {