[PATCH 6/6][RFC] time: Convert x86_64 to using new update_vsyscall
From: John Stultz
Date: Mon Sep 17 2012 - 18:05:30 EST
Switch x86_64 to using sub-ns precise vsyscall
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Paul Turner <pjt@xxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Richard Cochran <richardcochran@xxxxxxxxx>
Cc: Prarit Bhargava <prarit@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
---
arch/x86/Kconfig | 2 +-
arch/x86/include/asm/vgtod.h | 4 ++--
arch/x86/kernel/vsyscall_64.c | 47 ++++++++++++++++++++++++----------------
arch/x86/vdso/vclock_gettime.c | 22 ++++++++++++-------
4 files changed, 45 insertions(+), 30 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index e3f3c1a..8ec3a1a 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -93,7 +93,7 @@ config X86
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
diff --git a/arch/x86/include/asm/vgtod.h b/arch/x86/include/asm/vgtod.h
index 8b38be2..46e24d3 100644
--- a/arch/x86/include/asm/vgtod.h
+++ b/arch/x86/include/asm/vgtod.h
@@ -17,8 +17,8 @@ struct vsyscall_gtod_data {
/* 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;
diff --git a/arch/x86/kernel/vsyscall_64.c b/arch/x86/kernel/vsyscall_64.c
index 77dde29..3a3e8c9 100644
--- a/arch/x86/kernel/vsyscall_64.c
+++ b/arch/x86/kernel/vsyscall_64.c
@@ -82,32 +82,41 @@ void update_vsyscall_tz(void)
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;
-
- vsyscall_gtod_data.wall_time_sec = wall_time->tv_sec;
- vsyscall_gtod_data.wall_time_nsec = wall_time->tv_nsec;
+ 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;
+
+ vdata->wall_time_sec = tk->xtime_sec;
+ vdata->wall_time_snsec = tk->xtime_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++;
+ }
- 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->wall_time_coarse.tv_sec = tk->xtime_sec;
+ vdata->wall_time_coarse.tv_nsec = (long)(tk->xtime_nsec >> tk->shift);
- 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->monotonic_time_coarse = timespec_add(vdata->wall_time_coarse,
+ tk->wall_to_monotonic);
- write_seqcount_end(&vsyscall_gtod_data.seq);
+ write_seqcount_end(&vdata->seq);
}
static void warn_bad_vsyscall(const char *level, struct pt_regs *regs,
diff --git a/arch/x86/vdso/vclock_gettime.c b/arch/x86/vdso/vclock_gettime.c
index 885eff4..4df6c37 100644
--- a/arch/x86/vdso/vclock_gettime.c
+++ b/arch/x86/vdso/vclock_gettime.c
@@ -80,7 +80,7 @@ notrace static long vdso_fallback_gtod(struct timeval *tv, struct timezone *tz)
}
-notrace static inline long vgetns(void)
+notrace static inline u64 vgetsns(void)
{
long v;
cycles_t cycles;
@@ -91,21 +91,24 @@ notrace static inline long vgetns(void)
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(>od->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(>od->seq, seq)));
timespec_add_ns(ts, ns);
@@ -114,15 +117,18 @@ notrace static int __always_inline do_realtime(struct timespec *ts)
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(>od->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(>od->seq, seq)));
timespec_add_ns(ts, ns);
--
1.7.9.5
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/