tile: Convert VDSO timekeeping to the precise mechanism

The code was only halfarsed converted to the new VSDO update mechanism
and still uses the inaccurate base value which lacks the fractional
part of xtime_nsec. Fix it up.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>

arch/tile/kernel/time.c

@@ -260,7 +260,6 @@ void update_vsyscall_tz(void)
 
 void update_vsyscall(struct timekeeper *tk)
 {
-	struct timespec wall_time = tk_xtime(tk);
 	struct timespec *wtm = &tk->wall_to_monotonic;
 	struct clocksource *clock = tk->clock;
 
@@ -271,12 +270,12 @@ void update_vsyscall(struct timekeeper *tk)
 	++vdso_data->tb_update_count;
 	smp_wmb();
 	vdso_data->xtime_tod_stamp = clock->cycle_last;
-	vdso_data->xtime_clock_sec = wall_time.tv_sec;
-	vdso_data->xtime_clock_nsec = wall_time.tv_nsec;
+	vdso_data->xtime_clock_sec = tk->xtime_sec;
+	vdso_data->xtime_clock_nsec = tk->xtime_nsec;
 	vdso_data->wtom_clock_sec = wtm->tv_sec;
 	vdso_data->wtom_clock_nsec = wtm->tv_nsec;
-	vdso_data->mult = clock->mult;
-	vdso_data->shift = clock->shift;
+	vdso_data->mult = tk->mult;
+	vdso_data->shift = tk->shift;
 	smp_wmb();
 	++vdso_data->tb_update_count;
 }

arch/tile/kernel/vdso/vgettimeofday.c

@@ -83,10 +83,11 @@ int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
 		if (count & 1)
 			continue;
 
-		cycles = (get_cycles() - vdso_data->xtime_tod_stamp);
-		ns = (cycles * vdso_data->mult) >> vdso_data->shift;
 		sec = vdso_data->xtime_clock_sec;
-		ns += vdso_data->xtime_clock_nsec;
+		cycles = get_cycles() - vdso_data->xtime_tod_stamp;
+		ns = (cycles * vdso_data->mult) + vdso_data->xtime_clock_nsec;
+		ns >>= vdso_data->shift;
+
 		if (ns >= NSEC_PER_SEC) {
 			ns -= NSEC_PER_SEC;
 			sec += 1;