time: Introduce new GENERIC_TIME_VSYSCALL

Now that we moved everyone over to GENERIC_TIME_VSYSCALL_OLD,
introduce the new declaration and config option for the new
update_vsyscall method.

Cc: Tony Luck <tony.luck@intel.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>

include/linux/timekeeper_internal.h

@@ -66,16 +66,38 @@ struct timekeeper {
 	seqlock_t		lock;
 };
 
+static inline struct timespec tk_xtime(struct timekeeper *tk)
+{
+	struct timespec ts;
 
-#ifdef CONFIG_GENERIC_TIME_VSYSCALL_OLD
-extern void
-update_vsyscall_old(struct timespec *ts, struct timespec *wtm,
-			struct clocksource *c, u32 mult);
+	ts.tv_sec = tk->xtime_sec;
+	ts.tv_nsec = (long)(tk->xtime_nsec >> tk->shift);
+	return ts;
+}
+
+
+#ifdef CONFIG_GENERIC_TIME_VSYSCALL
+
+extern void update_vsyscall(struct timekeeper *tk);
 extern void update_vsyscall_tz(void);
+
+#elif defined(CONFIG_GENERIC_TIME_VSYSCALL_OLD)
+
+extern void update_vsyscall_old(struct timespec *ts, struct timespec *wtm,
+				struct clocksource *c, u32 mult);
+extern void update_vsyscall_tz(void);
+
+static inline void update_vsyscall(struct timekeeper *tk)
+{
+	struct timespec xt;
+
+	xt = tk_xtime(tk);
+	update_vsyscall_old(&xt, &tk->wall_to_monotonic, tk->clock, tk->mult);
+}
+
 #else
-static inline void
-update_vsyscall_old(struct timespec *ts, struct timespec *wtm,
-					struct clocksource *c, u32 mult)
+
+static inline void update_vsyscall(struct timekeeper *tk)
 {
 }
 static inline void update_vsyscall_tz(void)

kernel/time/Kconfig

@@ -12,6 +12,10 @@ config CLOCKSOURCE_WATCHDOG
 config ARCH_CLOCKSOURCE_DATA
 	bool
 
+# Timekeeping vsyscall support
+config GENERIC_TIME_VSYSCALL
+	bool
+
 # Timekeeping vsyscall support
 config GENERIC_TIME_VSYSCALL_OLD
 	bool

kernel/time/timekeeping.c

@@ -42,15 +42,6 @@ static inline void tk_normalize_xtime(struct timekeeper *tk)
 	}
 }
 
-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;
@@ -192,14 +183,11 @@ static inline s64 timekeeping_get_ns_raw(struct timekeeper *tk)
 /* must hold write on timekeeper.lock */
 static void timekeeping_update(struct timekeeper *tk, bool clearntp)
 {
-	struct timespec xt;
-
 	if (clearntp) {
 		tk->ntp_error = 0;
 		ntp_clear();
 	}
-	xt = tk_xtime(tk);
-	update_vsyscall_old(&xt, &tk->wall_to_monotonic, tk->clock, tk->mult);
+	update_vsyscall(tk);
 }
 
 /**