1 files changed, 19 insertions, 19 deletions

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 7437b41f6a47..c8d52cb4cb6e 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -38,7 +38,7 @@ static int __read_mostly tsc_unstable;
    erroneous rdtsc usage on !cpu_has_tsc processors */
 static int __read_mostly tsc_disabled = -1;
 
-static struct static_key __use_tsc = STATIC_KEY_INIT;
+static DEFINE_STATIC_KEY_FALSE(__use_tsc);
 
 int tsc_clocksource_reliable;
 
@@ -248,7 +248,7 @@ static void set_cyc2ns_scale(unsigned long cpu_khz, int cpu)
 
 	data = cyc2ns_write_begin(cpu);
 
-	rdtscll(tsc_now);
+	tsc_now = rdtsc();
 	ns_now = cycles_2_ns(tsc_now);
 
 	/*
@@ -274,7 +274,12 @@ done:
  */
 u64 native_sched_clock(void)
 {
-	u64 tsc_now;
+	if (static_branch_likely(&__use_tsc)) {
+		u64 tsc_now = rdtsc();
+
+		/* return the value in ns */
+		return cycles_2_ns(tsc_now);
+	}
 
 	/*
 	 * Fall back to jiffies if there's no TSC available:
@@ -284,16 +289,17 @@ u64 native_sched_clock(void)
 	 *   very important for it to be as fast as the platform
 	 *   can achieve it. )
 	 */
-	if (!static_key_false(&__use_tsc)) {
-		/* No locking but a rare wrong value is not a big deal: */
-		return (jiffies_64 - INITIAL_JIFFIES) * (1000000000 / HZ);
-	}
 
-	/* read the Time Stamp Counter: */
-	rdtscll(tsc_now);
+	/* No locking but a rare wrong value is not a big deal: */
+	return (jiffies_64 - INITIAL_JIFFIES) * (1000000000 / HZ);
+}
 
-	/* return the value in ns */
-	return cycles_2_ns(tsc_now);
+/*
+ * Generate a sched_clock if you already have a TSC value.
+ */
+u64 native_sched_clock_from_tsc(u64 tsc)
+{
+	return cycles_2_ns(tsc);
 }
 
 /* We need to define a real function for sched_clock, to override the
@@ -308,12 +314,6 @@ unsigned long long
 sched_clock(void) __attribute__((alias("native_sched_clock")));
 #endif
 
-unsigned long long native_read_tsc(void)
-{
-	return __native_read_tsc();
-}
-EXPORT_SYMBOL(native_read_tsc);
-
 int check_tsc_unstable(void)
 {
 	return tsc_unstable;
@@ -976,7 +976,7 @@ static struct clocksource clocksource_tsc;
  */
 static cycle_t read_tsc(struct clocksource *cs)
 {
-	return (cycle_t)get_cycles();
+	return (cycle_t)rdtsc_ordered();
 }
 
 /*
@@ -1210,7 +1210,7 @@ void __init tsc_init(void)
 	/* now allow native_sched_clock() to use rdtsc */
 
 	tsc_disabled = 0;
-	static_key_slow_inc(&__use_tsc);
+	static_branch_enable(&__use_tsc);
 
 	if (!no_sched_irq_time)
 		enable_sched_clock_irqtime();