ntp: Fix RTC synchronization on 32-bit platforms

Due to an integer overflow, RTC synchronization now happens every 2s
instead of the intended 11 minutes.  Fix this by forcing 64-bit
arithmetic for the sync period calculation.

Annotate the other place which multiplies seconds for consistency as well.

Fixes: c9e6189 ("ntp: Make the RTC synchronization more reliable")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210111103956.290378-1-geert+renesas@glider.be

kernel/time/ntp.c

@@ -498,7 +498,7 @@ int second_overflow(time64_t secs)
 static void sync_hw_clock(struct work_struct *work);
 static DECLARE_WORK(sync_work, sync_hw_clock);
 static struct hrtimer sync_hrtimer;
-#define SYNC_PERIOD_NS (11UL * 60 * NSEC_PER_SEC)
+#define SYNC_PERIOD_NS (11ULL * 60 * NSEC_PER_SEC)
 
 static enum hrtimer_restart sync_timer_callback(struct hrtimer *timer)
 {
@@ -512,7 +512,7 @@ static void sched_sync_hw_clock(unsigned long offset_nsec, bool retry)
 	ktime_t exp = ktime_set(ktime_get_real_seconds(), 0);
 
 	if (retry)
-		exp = ktime_add_ns(exp, 2 * NSEC_PER_SEC - offset_nsec);
+		exp = ktime_add_ns(exp, 2ULL * NSEC_PER_SEC - offset_nsec);
 	else
 		exp = ktime_add_ns(exp, SYNC_PERIOD_NS - offset_nsec);