timekeeping: Remove CONFIG_GENERIC_TIME_VSYSCALL_OLD

As of d4d1fc61eb38f (ia64: Update fsyscall gettime to use modern
vsyscall_update)the last user of CONFIG_GENERIC_TIME_VSYSCALL_OLD
have been updated, the legacy support for old-style vsyscall
implementations can be removed from the timekeeping code.

(Thanks again to Tony Luck for helping remove the last user!)

[jstultz: Commit message rework]

Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <stephen.boyd@linaro.org>
Link: https://lkml.kernel.org/r/1510613491-16695-1-git-send-email-john.stultz@linaro.org

include/linux/timekeeper_internal.h

@@ -136,13 +136,6 @@ struct timekeeper {
 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,
-				u64 cycle_last);
-extern void update_vsyscall_tz(void);
-
 #else
 
 static inline void update_vsyscall(struct timekeeper *tk)

kernel/time/Kconfig

@@ -21,10 +21,6 @@ config CLOCKSOURCE_VALIDATE_LAST_CYCLE
 config GENERIC_TIME_VSYSCALL
 	bool
 
-# Timekeeping vsyscall support
-config GENERIC_TIME_VSYSCALL_OLD
-	bool
-
 # Old style timekeeping
 config ARCH_USES_GETTIMEOFFSET
 	bool

kernel/time/timekeeping.c

@@ -557,45 +557,6 @@ static void halt_fast_timekeeper(struct timekeeper *tk)
 	update_fast_timekeeper(&tkr_dummy, &tk_fast_raw);
 }
 
-#ifdef CONFIG_GENERIC_TIME_VSYSCALL_OLD
-#warning Please contact your maintainers, as GENERIC_TIME_VSYSCALL_OLD compatibity will disappear soon.
-
-static inline void update_vsyscall(struct timekeeper *tk)
-{
-	struct timespec xt, wm;
-
-	xt = timespec64_to_timespec(tk_xtime(tk));
-	wm = timespec64_to_timespec(tk->wall_to_monotonic);
-	update_vsyscall_old(&xt, &wm, tk->tkr_mono.clock, tk->tkr_mono.mult,
-			    tk->tkr_mono.cycle_last);
-}
-
-static inline void old_vsyscall_fixup(struct timekeeper *tk)
-{
-	s64 remainder;
-
-	/*
-	* 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), and CONFIG_GENERIC_TIME_VSYSCALL_OLD
-	* users are removed, this can be killed.
-	*/
-	remainder = tk->tkr_mono.xtime_nsec & ((1ULL << tk->tkr_mono.shift) - 1);
-	if (remainder != 0) {
-		tk->tkr_mono.xtime_nsec -= remainder;
-		tk->tkr_mono.xtime_nsec += 1ULL << tk->tkr_mono.shift;
-		tk->ntp_error += remainder << tk->ntp_error_shift;
-		tk->ntp_error -= (1ULL << tk->tkr_mono.shift) << tk->ntp_error_shift;
-	}
-}
-#else
-#define old_vsyscall_fixup(tk)
-#endif
-
 static RAW_NOTIFIER_HEAD(pvclock_gtod_chain);
 
 static void update_pvclock_gtod(struct timekeeper *tk, bool was_set)
@@ -2163,12 +2124,6 @@ void update_wall_time(void)
 	/* correct the clock when NTP error is too big */
 	timekeeping_adjust(tk, offset);
 
-	/*
-	 * XXX This can be killed once everyone converts
-	 * to the new update_vsyscall.
-	 */
-	old_vsyscall_fixup(tk);
-
 	/*
 	 * Finally, make sure that after the rounding
 	 * xtime_nsec isn't larger than NSEC_PER_SEC