[4/8] time: Condense timekeeper.xtime into xtime_sec

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 4fd83df..80d0c78 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -38,8 +38,11 @@  struct timekeeper {
 	/* Raw nano seconds accumulated per NTP interval. */
 	u32			raw_interval;
 
-	/* Clock shifted nano seconds remainder not stored in xtime.tv_nsec. */
+	/* Current CLOCK_REALTIME time in seconds */
+	u64			xtime_sec;
+	/* Clock shifted nano seconds */
 	u64			xtime_nsec;
+
 	/* Difference between accumulated time and NTP time in ntp
 	 * shifted nano seconds. */
 	s64			ntp_error;
@@ -47,8 +50,6 @@  struct timekeeper {
 	 * ntp shifted nano seconds. */
 	u32			ntp_error_shift;
 
-	/* The current time */
-	struct timespec 	xtime;
 	/*
 	 * wall_to_monotonic is what we need to add to xtime (or xtime corrected
 	 * for sub jiffie times) to get to monotonic time.  Monotonic is pegged
@@ -89,6 +90,36 @@  __cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock);
 int __read_mostly timekeeping_suspended;
 
 
+static inline void tk_normalize_xtime(struct timekeeper *tk)
+{
+	while (tk->xtime_nsec >= ((u64)NSEC_PER_SEC << tk->shift)) {
+		tk->xtime_nsec -= (u64)NSEC_PER_SEC << tk->shift;
+		tk->xtime_sec++;
+	}
+}
+
+static struct timespec tk_xtime(struct timekeeper *tk)
+{
+	struct timespec ts;
+
+	ts.tv_sec = tk->xtime_sec;
+	ts.tv_nsec = (long)(tk->xtime_nsec >> tk->shift);
+	return ts;
+}
+
+static void tk_set_xtime(struct timekeeper *tk, const struct timespec *ts)
+{
+	tk->xtime_sec = ts->tv_sec;
+	tk->xtime_nsec = ts->tv_nsec << tk->shift;
+}
+
+
+static void tk_xtime_add(struct timekeeper *tk, const struct timespec *ts)
+{
+	tk->xtime_sec += ts->tv_sec;
+	tk->xtime_nsec += ts->tv_nsec << tk->shift;
+}
+
 
 /**
  * timekeeper_setup_internals - Set up internals to use clocksource clock.
@@ -104,7 +135,9 @@  static void timekeeper_setup_internals(struct clocksource *clock)
 {
 	cycle_t interval;
 	u64 tmp, ntpinterval;
+	struct clocksource *old_clock;
 
+	old_clock = timekeeper.clock;
 	timekeeper.clock = clock;
 	clock->cycle_last = clock->read(clock);
 
@@ -126,7 +159,14 @@  static void timekeeper_setup_internals(struct clocksource *clock)
 	timekeeper.raw_interval =
 		((u64) interval * clock->mult) >> clock->shift;
 
-	timekeeper.xtime_nsec = 0;
+	 /* if changing clocks, convert xtime_nsec shift units */
+	if (old_clock) {
+		int shift_change = clock->shift - old_clock->shift;
+		if (shift_change < 0)
+			timekeeper.xtime_nsec >>= -shift_change;
+		else
+			timekeeper.xtime_nsec <<= shift_change;
+	}
 	timekeeper.shift = clock->shift;
 
 	timekeeper.ntp_error = 0;
@@ -145,6 +185,7 @@  static inline s64 timekeeping_get_ns(void)
 {
 	cycle_t cycle_now, cycle_delta;
 	struct clocksource *clock;
+	s64 nsec;
 
 	/* read clocksource: */
 	clock = timekeeper.clock;
@@ -153,9 +194,8 @@  static inline s64 timekeeping_get_ns(void)
 	/* calculate the delta since the last update_wall_time: */
 	cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
 
-	/* return delta convert to nanoseconds using ntp adjusted mult. */
-	return clocksource_cyc2ns(cycle_delta, timekeeper.mult,
-				  timekeeper.shift);
+	nsec = cycle_delta * timekeeper.mult + timekeeper.xtime_nsec;
+	return nsec >> timekeeper.shift;
 }
 
 static inline s64 timekeeping_get_ns_raw(void)
@@ -185,12 +225,15 @@  static void update_rt_offset(void)
 /* must hold write on timekeeper.lock */
 static void timekeeping_update(bool clearntp)
 {
+	struct timespec xt;
+
 	if (clearntp) {
 		timekeeper.ntp_error = 0;
 		ntp_clear();
 	}
 	update_rt_offset();
-	update_vsyscall(&timekeeper.xtime, &timekeeper.wall_to_monotonic,
+	xt = tk_xtime(&timekeeper);
+	update_vsyscall(&xt, &timekeeper.wall_to_monotonic,
 			 timekeeper.clock, timekeeper.mult);
 }
 
@@ -213,13 +256,12 @@  static void timekeeping_forward_now(void)
 	cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
 	clock->cycle_last = cycle_now;
 
-	nsec = clocksource_cyc2ns(cycle_delta, timekeeper.mult,
-				  timekeeper.shift);
+	timekeeper.xtime_nsec += cycle_delta * timekeeper.mult;
 
 	/* If arch requires, add in gettimeoffset() */
-	nsec += arch_gettimeoffset();
+	timekeeper.xtime_nsec += arch_gettimeoffset() << timekeeper.shift;
 
-	timespec_add_ns(&timekeeper.xtime, nsec);
+	tk_normalize_xtime(&timekeeper);
 
 	nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
 	timespec_add_ns(&timekeeper.raw_time, nsec);
@@ -234,15 +276,15 @@  static void timekeeping_forward_now(void)
 void getnstimeofday(struct timespec *ts)
 {
 	unsigned long seq;
-	s64 nsecs;
+	s64 nsecs = 0;
 
 	WARN_ON(timekeeping_suspended);
 
 	do {
 		seq = read_seqbegin(&timekeeper.lock);
 
-		*ts = timekeeper.xtime;
-		nsecs = timekeeping_get_ns();
+		ts->tv_sec = timekeeper.xtime_sec;
+		ts->tv_nsec = timekeeping_get_ns();
 
 		/* If arch requires, add in gettimeoffset() */
 		nsecs += arch_gettimeoffset();
@@ -262,11 +304,10 @@  ktime_t ktime_get(void)
 
 	do {
 		seq = read_seqbegin(&timekeeper.lock);
-		secs = timekeeper.xtime.tv_sec +
+		secs = timekeeper.xtime_sec +
 				timekeeper.wall_to_monotonic.tv_sec;
-		nsecs = timekeeper.xtime.tv_nsec +
+		nsecs = timekeeping_get_ns() +
 				timekeeper.wall_to_monotonic.tv_nsec;
-		nsecs += timekeeping_get_ns();
 		/* If arch requires, add in gettimeoffset() */
 		nsecs += arch_gettimeoffset();
 
@@ -291,22 +332,21 @@  void ktime_get_ts(struct timespec *ts)
 {
 	struct timespec tomono;
 	unsigned int seq;
-	s64 nsecs;
 
 	WARN_ON(timekeeping_suspended);
 
 	do {
 		seq = read_seqbegin(&timekeeper.lock);
-		*ts = timekeeper.xtime;
+		ts->tv_sec = timekeeper.xtime_sec;
+		ts->tv_nsec = timekeeping_get_ns();
 		tomono = timekeeper.wall_to_monotonic;
-		nsecs = timekeeping_get_ns();
 		/* If arch requires, add in gettimeoffset() */
-		nsecs += arch_gettimeoffset();
+		ts->tv_nsec += arch_gettimeoffset();
 
 	} while (read_seqretry(&timekeeper.lock, seq));
 
 	set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec,
-				ts->tv_nsec + tomono.tv_nsec + nsecs);
+				ts->tv_nsec + tomono.tv_nsec);
 }
 EXPORT_SYMBOL_GPL(ktime_get_ts);
 
@@ -334,7 +374,8 @@  void getnstime_raw_and_real(struct timespec *ts_raw, struct timespec *ts_real)
 		seq = read_seqbegin(&timekeeper.lock);
 
 		*ts_raw = timekeeper.raw_time;
-		*ts_real = timekeeper.xtime;
+		ts_real->tv_sec = timekeeper.xtime_sec;
+		ts_real->tv_nsec = 0;
 
 		nsecs_raw = timekeeping_get_ns_raw();
 		nsecs_real = timekeeping_get_ns();
@@ -377,7 +418,7 @@  EXPORT_SYMBOL(do_gettimeofday);
  */
 int do_settimeofday(const struct timespec *tv)
 {
-	struct timespec ts_delta;
+	struct timespec ts_delta, xt;
 	unsigned long flags;
 
 	if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
@@ -387,12 +428,15 @@  int do_settimeofday(const struct timespec *tv)
 
 	timekeeping_forward_now();
 
-	ts_delta.tv_sec = tv->tv_sec - timekeeper.xtime.tv_sec;
-	ts_delta.tv_nsec = tv->tv_nsec - timekeeper.xtime.tv_nsec;
+	xt = tk_xtime(&timekeeper);
+	ts_delta.tv_sec = tv->tv_sec - xt.tv_sec;
+	ts_delta.tv_nsec = tv->tv_nsec - xt.tv_nsec;
+
 	timekeeper.wall_to_monotonic =
 			timespec_sub(timekeeper.wall_to_monotonic, ts_delta);
 
-	timekeeper.xtime = *tv;
+	tk_set_xtime(&timekeeper, tv);
+
 	timekeeping_update(true);
 
 	write_sequnlock_irqrestore(&timekeeper.lock, flags);
@@ -422,7 +466,8 @@  int timekeeping_inject_offset(struct timespec *ts)
 
 	timekeeping_forward_now();
 
-	timekeeper.xtime = timespec_add(timekeeper.xtime, *ts);
+
+	tk_xtime_add(&timekeeper, ts);
 	timekeeper.wall_to_monotonic =
 				timespec_sub(timekeeper.wall_to_monotonic, *ts);
 
@@ -606,14 +651,12 @@  void __init timekeeping_init(void)
 		clock->enable(clock);
 	timekeeper_setup_internals(clock);
 
-	timekeeper.xtime.tv_sec = now.tv_sec;
-	timekeeper.xtime.tv_nsec = now.tv_nsec;
+	tk_set_xtime(&timekeeper, &now);
 	timekeeper.raw_time.tv_sec = 0;
 	timekeeper.raw_time.tv_nsec = 0;
-	if (boot.tv_sec == 0 && boot.tv_nsec == 0) {
-		boot.tv_sec = timekeeper.xtime.tv_sec;
-		boot.tv_nsec = timekeeper.xtime.tv_nsec;
-	}
+	if (boot.tv_sec == 0 && boot.tv_nsec == 0)
+		boot = tk_xtime(&timekeeper);
+
 	set_normalized_timespec(&timekeeper.wall_to_monotonic,
 				-boot.tv_sec, -boot.tv_nsec);
 	update_rt_offset();
@@ -646,7 +689,7 @@  static void __timekeeping_inject_sleeptime(struct timespec *delta)
 		return;
 	}
 
-	timekeeper.xtime = timespec_add(timekeeper.xtime, *delta);
+	tk_xtime_add(&timekeeper, delta);
 	timekeeper.wall_to_monotonic =
 			timespec_sub(timekeeper.wall_to_monotonic, *delta);
 	update_sleep_time(timespec_add(timekeeper.total_sleep_time, *delta));
@@ -742,7 +785,7 @@  static int timekeeping_suspend(void)
 	 * try to compensate so the difference in system time
 	 * and persistent_clock time stays close to constant.
 	 */
-	delta = timespec_sub(timekeeper.xtime, timekeeping_suspend_time);
+	delta = timespec_sub(tk_xtime(&timekeeper), timekeeping_suspend_time);
 	delta_delta = timespec_sub(delta, old_delta);
 	if (abs(delta_delta.tv_sec)  >= 2) {
 		/*
@@ -977,9 +1020,9 @@  static cycle_t logarithmic_accumulation(cycle_t offset, u32 shift)
 	while (timekeeper.xtime_nsec >= nsecps) {
 		int leap;
 		timekeeper.xtime_nsec -= nsecps;
-		timekeeper.xtime.tv_sec++;
-		leap = second_overflow(timekeeper.xtime.tv_sec);
-		timekeeper.xtime.tv_sec += leap;
+		timekeeper.xtime_sec++;
+		leap = second_overflow(timekeeper.xtime_sec);
+		timekeeper.xtime_sec += leap;
 		timekeeper.wall_to_monotonic.tv_sec -= leap;
 		if (leap)
 			clock_was_set_delayed();
@@ -1015,6 +1058,7 @@  static void update_wall_time(void)
 	cycle_t offset;
 	int shift = 0, maxshift;
 	unsigned long flags;
+	s64 remainder;
 
 	write_seqlock_irqsave(&timekeeper.lock, flags);
 
@@ -1029,8 +1073,6 @@  static void update_wall_time(void)
 #else
 	offset = (clock->read(clock) - clock->cycle_last) & clock->mask;
 #endif
-	timekeeper.xtime_nsec = (s64)timekeeper.xtime.tv_nsec <<
-						timekeeper.shift;
 
 	/*
 	 * With NO_HZ we may have to accumulate many cycle_intervals
@@ -1076,28 +1118,31 @@  static void update_wall_time(void)
 		timekeeper.ntp_error += neg << timekeeper.ntp_error_shift;
 	}
 
-
 	/*
-	 * Store full nanoseconds into xtime after rounding it up and
-	 * add the remainder to the error difference.
-	 */
-	timekeeper.xtime.tv_nsec = ((s64)timekeeper.xtime_nsec >>
-						timekeeper.shift) + 1;
-	timekeeper.xtime_nsec -= (s64)timekeeper.xtime.tv_nsec <<
-						timekeeper.shift;
-	timekeeper.ntp_error +=	timekeeper.xtime_nsec <<
-				timekeeper.ntp_error_shift;
+	* Store only full nanoseconds into xtime_nsec after rounding
+	* it up and add the remainder to the error difference.
+	* XXX - This is necessary to avoid small 1ns inconsistnecies caused
+	* by truncating the remainder in vsyscalls. However, it causes
+	* additional work to be done in timekeeping_adjust(). Once
+	* the vsyscall implementations are converted to use xtime_nsec
+	* (shifted nanoseconds), this can be killed.
+	*/
+	remainder = timekeeper.xtime_nsec & ((1 << timekeeper.shift) - 1);
+	timekeeper.xtime_nsec -= remainder;
+	timekeeper.xtime_nsec += 1 << timekeeper.shift;
+	timekeeper.ntp_error += remainder << timekeeper.ntp_error_shift;
 
 	/*
 	 * Finally, make sure that after the rounding
-	 * xtime.tv_nsec isn't larger than NSEC_PER_SEC
+	 * xtime_nsec isn't larger than NSEC_PER_SEC
 	 */
-	if (unlikely(timekeeper.xtime.tv_nsec >= NSEC_PER_SEC)) {
+	if (unlikely(timekeeper.xtime_nsec >=
+			((u64)NSEC_PER_SEC << timekeeper.shift))) {
 		int leap;
-		timekeeper.xtime.tv_nsec -= NSEC_PER_SEC;
-		timekeeper.xtime.tv_sec++;
-		leap = second_overflow(timekeeper.xtime.tv_sec);
-		timekeeper.xtime.tv_sec += leap;
+		timekeeper.xtime_nsec -= (u64)NSEC_PER_SEC << timekeeper.shift;
+		timekeeper.xtime_sec++;
+		leap = second_overflow(timekeeper.xtime_sec);
+		timekeeper.xtime_sec += leap;
 		timekeeper.wall_to_monotonic.tv_sec -= leap;
 		if (leap)
 			clock_was_set_delayed();
@@ -1148,21 +1193,20 @@  void get_monotonic_boottime(struct timespec *ts)
 {
 	struct timespec tomono, sleep;
 	unsigned int seq;
-	s64 nsecs;
 
 	WARN_ON(timekeeping_suspended);
 
 	do {
 		seq = read_seqbegin(&timekeeper.lock);
-		*ts = timekeeper.xtime;
+		ts->tv_sec = timekeeper.xtime_sec;
+		ts->tv_nsec = timekeeping_get_ns();
 		tomono = timekeeper.wall_to_monotonic;
 		sleep = timekeeper.total_sleep_time;
-		nsecs = timekeeping_get_ns();
 
 	} while (read_seqretry(&timekeeper.lock, seq));
 
 	set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec + sleep.tv_sec,
-			ts->tv_nsec + tomono.tv_nsec + sleep.tv_nsec + nsecs);
+			ts->tv_nsec + tomono.tv_nsec + sleep.tv_nsec);
 }
 EXPORT_SYMBOL_GPL(get_monotonic_boottime);
 
@@ -1195,13 +1239,13 @@  EXPORT_SYMBOL_GPL(monotonic_to_bootbased);
 
 unsigned long get_seconds(void)
 {
-	return timekeeper.xtime.tv_sec;
+	return timekeeper.xtime_sec;
 }
 EXPORT_SYMBOL(get_seconds);
 
 struct timespec __current_kernel_time(void)
 {
-	return timekeeper.xtime;
+	return tk_xtime(&timekeeper);
 }
 
 struct timespec current_kernel_time(void)
@@ -1212,7 +1256,7 @@  struct timespec current_kernel_time(void)
 	do {
 		seq = read_seqbegin(&timekeeper.lock);
 
-		now = timekeeper.xtime;
+		now = tk_xtime(&timekeeper);
 	} while (read_seqretry(&timekeeper.lock, seq));
 
 	return now;
@@ -1227,7 +1271,7 @@  struct timespec get_monotonic_coarse(void)
 	do {
 		seq = read_seqbegin(&timekeeper.lock);
 
-		now = timekeeper.xtime;
+		now = tk_xtime(&timekeeper);
 		mono = timekeeper.wall_to_monotonic;
 	} while (read_seqretry(&timekeeper.lock, seq));
 
@@ -1262,7 +1306,7 @@  void get_xtime_and_monotonic_and_sleep_offset(struct timespec *xtim,
 
 	do {
 		seq = read_seqbegin(&timekeeper.lock);
-		*xtim = timekeeper.xtime;
+		*xtim = tk_xtime(&timekeeper);
 		*wtom = timekeeper.wall_to_monotonic;
 		*sleep = timekeeper.total_sleep_time;
 	} while (read_seqretry(&timekeeper.lock, seq));
@@ -1286,9 +1330,8 @@  ktime_t ktime_get_update_offsets(ktime_t *offs_real, ktime_t *offs_boot)
 	do {
 		seq = read_seqbegin(&timekeeper.lock);
 
-		secs = timekeeper.xtime.tv_sec;
-		nsecs = timekeeper.xtime.tv_nsec;
-		nsecs += timekeeping_get_ns();
+		secs = timekeeper.xtime_sec;
+		nsecs = timekeeping_get_ns();
 		/* If arch requires, add in gettimeoffset() */
 		nsecs += arch_gettimeoffset();