diff options
Diffstat (limited to 'kernel/time/timekeeping.c')
| -rw-r--r-- | kernel/time/timekeeping.c | 60 |
1 files changed, 44 insertions, 16 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 6a931852082f..91db94136c10 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -230,9 +230,7 @@ static inline s64 timekeeping_get_ns_raw(struct timekeeper *tk) /** * update_fast_timekeeper - Update the fast and NMI safe monotonic timekeeper. - * @tk: The timekeeper from which we take the update - * @tkf: The fast timekeeper to update - * @tbase: The time base for the fast timekeeper (mono/raw) + * @tkr: Timekeeping readout base from which we take the update * * We want to use this from any context including NMI and tracing / * instrumenting the timekeeping code itself. @@ -244,11 +242,11 @@ static inline s64 timekeeping_get_ns_raw(struct timekeeper *tk) * smp_wmb(); <- Ensure that the last base[1] update is visible * tkf->seq++; * smp_wmb(); <- Ensure that the seqcount update is visible - * update(tkf->base[0], tk); + * update(tkf->base[0], tkr); * smp_wmb(); <- Ensure that the base[0] update is visible * tkf->seq++; * smp_wmb(); <- Ensure that the seqcount update is visible - * update(tkf->base[1], tk); + * update(tkf->base[1], tkr); * * The reader side does: * @@ -269,7 +267,7 @@ static inline s64 timekeeping_get_ns_raw(struct timekeeper *tk) * slightly wrong timestamp (a few nanoseconds). See * @ktime_get_mono_fast_ns. */ -static void update_fast_timekeeper(struct timekeeper *tk) +static void update_fast_timekeeper(struct tk_read_base *tkr) { struct tk_read_base *base = tk_fast_mono.base; @@ -277,7 +275,7 @@ static void update_fast_timekeeper(struct timekeeper *tk) raw_write_seqcount_latch(&tk_fast_mono.seq); /* Update base[0] */ - memcpy(base, &tk->tkr, sizeof(*base)); + memcpy(base, tkr, sizeof(*base)); /* Force readers back to base[0] */ raw_write_seqcount_latch(&tk_fast_mono.seq); @@ -334,6 +332,35 @@ u64 notrace ktime_get_mono_fast_ns(void) } EXPORT_SYMBOL_GPL(ktime_get_mono_fast_ns); +/* Suspend-time cycles value for halted fast timekeeper. */ +static cycle_t cycles_at_suspend; + +static cycle_t dummy_clock_read(struct clocksource *cs) +{ + return cycles_at_suspend; +} + +/** + * halt_fast_timekeeper - Prevent fast timekeeper from accessing clocksource. + * @tk: Timekeeper to snapshot. + * + * It generally is unsafe to access the clocksource after timekeeping has been + * suspended, so take a snapshot of the readout base of @tk and use it as the + * fast timekeeper's readout base while suspended. It will return the same + * number of cycles every time until timekeeping is resumed at which time the + * proper readout base for the fast timekeeper will be restored automatically. + */ +static void halt_fast_timekeeper(struct timekeeper *tk) +{ + static struct tk_read_base tkr_dummy; + struct tk_read_base *tkr = &tk->tkr; + + memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy)); + cycles_at_suspend = tkr->read(tkr->clock); + tkr_dummy.read = dummy_clock_read; + update_fast_timekeeper(&tkr_dummy); +} + #ifdef CONFIG_GENERIC_TIME_VSYSCALL_OLD static inline void update_vsyscall(struct timekeeper *tk) @@ -462,7 +489,7 @@ static void timekeeping_update(struct timekeeper *tk, unsigned int action) memcpy(&shadow_timekeeper, &tk_core.timekeeper, sizeof(tk_core.timekeeper)); - update_fast_timekeeper(tk); + update_fast_timekeeper(&tk->tkr); } /** @@ -1170,7 +1197,7 @@ void timekeeping_inject_sleeptime64(struct timespec64 *delta) * xtime/wall_to_monotonic/jiffies/etc are * still managed by arch specific suspend/resume code. */ -static void timekeeping_resume(void) +void timekeeping_resume(void) { struct timekeeper *tk = &tk_core.timekeeper; struct clocksource *clock = tk->tkr.clock; @@ -1251,7 +1278,7 @@ static void timekeeping_resume(void) hrtimers_resume(); } -static int timekeeping_suspend(void) +int timekeeping_suspend(void) { struct timekeeper *tk = &tk_core.timekeeper; unsigned long flags; @@ -1296,6 +1323,7 @@ static int timekeeping_suspend(void) } timekeeping_update(tk, TK_MIRROR); + halt_fast_timekeeper(tk); write_seqcount_end(&tk_core.seq); raw_spin_unlock_irqrestore(&timekeeper_lock, flags); @@ -1659,24 +1687,24 @@ out: } /** - * getboottime - Return the real time of system boot. - * @ts: pointer to the timespec to be set + * getboottime64 - Return the real time of system boot. + * @ts: pointer to the timespec64 to be set * - * Returns the wall-time of boot in a timespec. + * Returns the wall-time of boot in a timespec64. * * This is based on the wall_to_monotonic offset and the total suspend * time. Calls to settimeofday will affect the value returned (which * basically means that however wrong your real time clock is at boot time, * you get the right time here). */ -void getboottime(struct timespec *ts) +void getboottime64(struct timespec64 *ts) { struct timekeeper *tk = &tk_core.timekeeper; ktime_t t = ktime_sub(tk->offs_real, tk->offs_boot); - *ts = ktime_to_timespec(t); + *ts = ktime_to_timespec64(t); } -EXPORT_SYMBOL_GPL(getboottime); +EXPORT_SYMBOL_GPL(getboottime64); unsigned long get_seconds(void) { |