time: Convert x86_64 to using new update_vsyscall

Switch x86_64 to using sub-ns precise vsyscall

Cc: Tony Luck <[e-mail]>
Cc: Paul Mackerras <[e-mail]>
Cc: Benjamin Herrenschmidt <[e-mail]>
Cc: Andy Lutomirski <[e-mail]>
Cc: Martin Schwidefsky <[e-mail]>
Cc: Paul Turner <[e-mail]>
Cc: Steven Rostedt <[e-mail]>
Cc: Richard Cochran <[e-mail]>
Cc: Prarit Bhargava <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Signed-off-by: John Stultz <[e-mail]>

arch/x86/Kconfig

···
 	select GENERIC_CLOCKEVENTS
 	select ARCH_CLOCKSOURCE_DATA if X86_64
 	select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
-	select GENERIC_TIME_VSYSCALL_OLD if X86_64
+	select GENERIC_TIME_VSYSCALL if X86_64
 	select KTIME_SCALAR if X86_32
 	select GENERIC_STRNCPY_FROM_USER
 	select GENERIC_STRNLEN_USER

arch/x86/include/asm/vgtod.h

···
 
 	/* open coded 'struct timespec' */
 	time_t		wall_time_sec;
-	u32		wall_time_nsec;
-	u32		monotonic_time_nsec;
+	u64		wall_time_snsec;
+	u64		monotonic_time_snsec;
 	time_t		monotonic_time_sec;
 
 	struct timezone sys_tz;

arch/x86/kernel/vsyscall_64.c

···
 	vsyscall_gtod_data.sys_tz = sys_tz;
 }
 
-void update_vsyscall_old(struct timespec *wall_time, struct timespec *wtm,
-			struct clocksource *clock, u32 mult)
+void update_vsyscall(struct timekeeper *tk)
 {
-	struct timespec monotonic;
+	struct vsyscall_gtod_data *vdata = &vsyscall_gtod_data;
 
-	write_seqcount_begin(&vsyscall_gtod_data.seq);
+	write_seqcount_begin(&vdata->seq);
 
 	/* copy vsyscall data */
-	vsyscall_gtod_data.clock.vclock_mode	= clock->archdata.vclock_mode;
-	vsyscall_gtod_data.clock.cycle_last	= clock->cycle_last;
-	vsyscall_gtod_data.clock.mask		= clock->mask;
-	vsyscall_gtod_data.clock.mult		= mult;
-	vsyscall_gtod_data.clock.shift		= clock->shift;
+	vdata->clock.vclock_mode	= tk->clock->archdata.vclock_mode;
+	vdata->clock.cycle_last		= tk->clock->cycle_last;
+	vdata->clock.mask		= tk->clock->mask;
+	vdata->clock.mult		= tk->mult;
+	vdata->clock.shift		= tk->shift;
 
-	vsyscall_gtod_data.wall_time_sec	= wall_time->tv_sec;
-	vsyscall_gtod_data.wall_time_nsec	= wall_time->tv_nsec;
+	vdata->wall_time_sec		= tk->xtime_sec;
+	vdata->wall_time_snsec		= tk->xtime_nsec;
 
-	monotonic = timespec_add(*wall_time, *wtm);
-	vsyscall_gtod_data.monotonic_time_sec	= monotonic.tv_sec;
-	vsyscall_gtod_data.monotonic_time_nsec	= monotonic.tv_nsec;
+	vdata->monotonic_time_sec	= tk->xtime_sec
+					+ tk->wall_to_monotonic.tv_sec;
+	vdata->monotonic_time_snsec	= tk->xtime_nsec
+					+ (tk->wall_to_monotonic.tv_nsec
+						<< tk->shift);
+	while (vdata->monotonic_time_snsec >=
+					(((u64)NSEC_PER_SEC) << tk->shift)) {
+		vdata->monotonic_time_snsec -=
+					((u64)NSEC_PER_SEC) << tk->shift;
+		vdata->monotonic_time_sec++;
+	}
 
-	vsyscall_gtod_data.wall_time_coarse	= __current_kernel_time();
-	vsyscall_gtod_data.monotonic_time_coarse =
-		timespec_add(vsyscall_gtod_data.wall_time_coarse, *wtm);
+	vdata->wall_time_coarse.tv_sec	= tk->xtime_sec;
+	vdata->wall_time_coarse.tv_nsec	= (long)(tk->xtime_nsec >> tk->shift);
 
-	write_seqcount_end(&vsyscall_gtod_data.seq);
+	vdata->monotonic_time_coarse	= timespec_add(vdata->wall_time_coarse,
+							tk->wall_to_monotonic);
+
+	write_seqcount_end(&vdata->seq);
 }
 
 static void warn_bad_vsyscall(const char *level, struct pt_regs *regs,

arch/x86/vdso/vclock_gettime.c

···
 }
 
 
-notrace static inline long vgetns(void)
+notrace static inline u64 vgetsns(void)
 {
 	long v;
 	cycles_t cycles;
···
 	else
 		return 0;
 	v = (cycles - gtod->clock.cycle_last) & gtod->clock.mask;
-	return (v * gtod->clock.mult) >> gtod->clock.shift;
+	return v * gtod->clock.mult;
 }
 
 /* Code size doesn't matter (vdso is 4k anyway) and this is faster. */
 notrace static int __always_inline do_realtime(struct timespec *ts)
 {
-	unsigned long seq, ns;
+	unsigned long seq;
+	u64 ns;
 	int mode;
 
+	ts->tv_nsec = 0;
 	do {
 		seq = read_seqcount_begin(&gtod->seq);
 		mode = gtod->clock.vclock_mode;
 		ts->tv_sec = gtod->wall_time_sec;
-		ts->tv_nsec = gtod->wall_time_nsec;
-		ns = vgetns();
+		ns = gtod->wall_time_snsec;
+		ns += vgetsns();
+		ns >>= gtod->clock.shift;
 	} while (unlikely(read_seqcount_retry(&gtod->seq, seq)));
 
 	timespec_add_ns(ts, ns);
···
 
 notrace static int do_monotonic(struct timespec *ts)
 {
-	unsigned long seq, ns;
+	unsigned long seq;
+	u64 ns;
 	int mode;
 
+	ts->tv_nsec = 0;
 	do {
 		seq = read_seqcount_begin(&gtod->seq);
 		mode = gtod->clock.vclock_mode;
 		ts->tv_sec = gtod->monotonic_time_sec;
-		ts->tv_nsec = gtod->monotonic_time_nsec;
-		ns = vgetns();
+		ns = gtod->monotonic_time_snsec;
+		ns += vgetsns();
+		ns >>= gtod->clock.shift;
 	} while (unlikely(read_seqcount_retry(&gtod->seq, seq)));
 	timespec_add_ns(ts, ns);