1 files changed, 24 insertions, 10 deletions

diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c
index 68d6c1190ac7..fcca4e72f1ef 100644
--- a/kernel/time/sched_clock.c
+++ b/kernel/time/sched_clock.c
@@ -71,16 +71,16 @@ static __always_inline u64 cyc_to_ns(u64 cyc, u32 mult, u32 shift)
 
 notrace struct clock_read_data *sched_clock_read_begin(unsigned int *seq)
 {
-	*seq = raw_read_seqcount_latch(&cd.seq);
+	*seq = read_seqcount_latch(&cd.seq);
 	return cd.read_data + (*seq & 1);
 }
 
 notrace int sched_clock_read_retry(unsigned int seq)
 {
-	return raw_read_seqcount_latch_retry(&cd.seq, seq);
+	return read_seqcount_latch_retry(&cd.seq, seq);
 }
 
-unsigned long long noinstr sched_clock_noinstr(void)
+static __always_inline unsigned long long __sched_clock(void)
 {
 	struct clock_read_data *rd;
 	unsigned int seq;
@@ -98,11 +98,23 @@ unsigned long long noinstr sched_clock_noinstr(void)
 	return res;
 }
 
+unsigned long long noinstr sched_clock_noinstr(void)
+{
+	return __sched_clock();
+}
+
 unsigned long long notrace sched_clock(void)
 {
 	unsigned long long ns;
 	preempt_disable_notrace();
-	ns = sched_clock_noinstr();
+	/*
+	 * All of __sched_clock() is a seqcount_latch reader critical section,
+	 * but relies on the raw helpers which are uninstrumented. For KCSAN,
+	 * mark all accesses in __sched_clock() as atomic.
+	 */
+	kcsan_nestable_atomic_begin();
+	ns = __sched_clock();
+	kcsan_nestable_atomic_end();
 	preempt_enable_notrace();
 	return ns;
 }
@@ -119,17 +131,19 @@ unsigned long long notrace sched_clock(void)
  */
 static void update_clock_read_data(struct clock_read_data *rd)
 {
-	/* update the backup (odd) copy with the new data */
-	cd.read_data[1] = *rd;
-
 	/* steer readers towards the odd copy */
-	raw_write_seqcount_latch(&cd.seq);
+	write_seqcount_latch_begin(&cd.seq);
 
 	/* now its safe for us to update the normal (even) copy */
 	cd.read_data[0] = *rd;
 
 	/* switch readers back to the even copy */
-	raw_write_seqcount_latch(&cd.seq);
+	write_seqcount_latch(&cd.seq);
+
+	/* update the backup (odd) copy with the new data */
+	cd.read_data[1] = *rd;
+
+	write_seqcount_latch_end(&cd.seq);
 }
 
 /*
@@ -267,7 +281,7 @@ void __init generic_sched_clock_init(void)
  */
 static u64 notrace suspended_sched_clock_read(void)
 {
-	unsigned int seq = raw_read_seqcount_latch(&cd.seq);
+	unsigned int seq = read_seqcount_latch(&cd.seq);
 
 	return cd.read_data[seq & 1].epoch_cyc;
 }