diff options
Diffstat (limited to 'kernel/time/timekeeping.c')
| -rw-r--r-- | kernel/time/timekeeping.c | 85 |
1 files changed, 49 insertions, 36 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index daa0ff017819..a45cedda93a7 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -399,6 +399,7 @@ static inline u64 timekeeping_cycles_to_ns(const struct tk_read_base *tkr, u64 c /** * update_fast_timekeeper - Update the fast and NMI safe monotonic timekeeper. * @tkr: Timekeeping readout base from which we take the update + * @tkf: Pointer to NMI safe timekeeper * * We want to use this from any context including NMI and tracing / * instrumenting the timekeeping code itself. @@ -428,6 +429,27 @@ static void update_fast_timekeeper(const struct tk_read_base *tkr, memcpy(base + 1, base, sizeof(*base)); } +static __always_inline u64 __ktime_get_fast_ns(struct tk_fast *tkf) +{ + struct tk_read_base *tkr; + unsigned int seq; + u64 now; + + do { + seq = raw_read_seqcount_latch(&tkf->seq); + tkr = tkf->base + (seq & 0x01); + now = ktime_to_ns(tkr->base); + + now += timekeeping_delta_to_ns(tkr, + clocksource_delta( + tk_clock_read(tkr), + tkr->cycle_last, + tkr->mask)); + } while (read_seqcount_latch_retry(&tkf->seq, seq)); + + return now; +} + /** * ktime_get_mono_fast_ns - Fast NMI safe access to clock monotonic * @@ -454,39 +476,24 @@ static void update_fast_timekeeper(const struct tk_read_base *tkr, * * So reader 6 will observe time going backwards versus reader 5. * - * While other CPUs are likely to be able observe that, the only way + * While other CPUs are likely to be able to observe that, the only way * for a CPU local observation is when an NMI hits in the middle of * the update. Timestamps taken from that NMI context might be ahead * of the following timestamps. Callers need to be aware of that and * deal with it. */ -static __always_inline u64 __ktime_get_fast_ns(struct tk_fast *tkf) -{ - struct tk_read_base *tkr; - unsigned int seq; - u64 now; - - do { - seq = raw_read_seqcount_latch(&tkf->seq); - tkr = tkf->base + (seq & 0x01); - now = ktime_to_ns(tkr->base); - - now += timekeeping_delta_to_ns(tkr, - clocksource_delta( - tk_clock_read(tkr), - tkr->cycle_last, - tkr->mask)); - } while (read_seqcount_latch_retry(&tkf->seq, seq)); - - return now; -} - u64 ktime_get_mono_fast_ns(void) { return __ktime_get_fast_ns(&tk_fast_mono); } EXPORT_SYMBOL_GPL(ktime_get_mono_fast_ns); +/** + * ktime_get_raw_fast_ns - Fast NMI safe access to clock monotonic raw + * + * Contrary to ktime_get_mono_fast_ns() this is always correct because the + * conversion factor is not affected by NTP/PTP correction. + */ u64 ktime_get_raw_fast_ns(void) { return __ktime_get_fast_ns(&tk_fast_raw); @@ -513,6 +520,9 @@ EXPORT_SYMBOL_GPL(ktime_get_raw_fast_ns); * (2) On 32-bit systems, the 64-bit boot offset (tk->offs_boot) may be * partially updated. Since the tk->offs_boot update is a rare event, this * should be a rare occurrence which postprocessing should be able to handle. + * + * The caveats vs. timestamp ordering as documented for ktime_get_fast_ns() + * apply as well. */ u64 notrace ktime_get_boot_fast_ns(void) { @@ -522,9 +532,6 @@ u64 notrace ktime_get_boot_fast_ns(void) } EXPORT_SYMBOL_GPL(ktime_get_boot_fast_ns); -/* - * See comment for __ktime_get_fast_ns() vs. timestamp ordering - */ static __always_inline u64 __ktime_get_real_fast(struct tk_fast *tkf, u64 *mono) { struct tk_read_base *tkr; @@ -549,6 +556,8 @@ static __always_inline u64 __ktime_get_real_fast(struct tk_fast *tkf, u64 *mono) /** * ktime_get_real_fast_ns: - NMI safe and fast access to clock realtime. + * + * See ktime_get_fast_ns() for documentation of the time stamp ordering. */ u64 ktime_get_real_fast_ns(void) { @@ -646,6 +655,7 @@ static void update_pvclock_gtod(struct timekeeper *tk, bool was_set) /** * pvclock_gtod_register_notifier - register a pvclock timedata update listener + * @nb: Pointer to the notifier block to register */ int pvclock_gtod_register_notifier(struct notifier_block *nb) { @@ -665,6 +675,7 @@ EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier); /** * pvclock_gtod_unregister_notifier - unregister a pvclock * timedata update listener + * @nb: Pointer to the notifier block to unregister */ int pvclock_gtod_unregister_notifier(struct notifier_block *nb) { @@ -755,6 +766,7 @@ static void timekeeping_update(struct timekeeper *tk, unsigned int action) /** * timekeeping_forward_now - update clock to the current time + * @tk: Pointer to the timekeeper to update * * Forward the current clock to update its state since the last call to * update_wall_time(). This is useful before significant clock changes, @@ -1323,7 +1335,7 @@ EXPORT_SYMBOL(do_settimeofday64); /** * timekeeping_inject_offset - Adds or subtracts from the current time. - * @tv: pointer to the timespec variable containing the offset + * @ts: Pointer to the timespec variable containing the offset * * Adds or subtracts an offset value from the current time. */ @@ -1399,9 +1411,8 @@ void timekeeping_warp_clock(void) } } -/** +/* * __timekeeping_set_tai_offset - Sets the TAI offset from UTC and monotonic - * */ static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset) { @@ -1409,7 +1420,7 @@ static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset) tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tai_offset, 0)); } -/** +/* * change_clocksource - Swaps clocksources if a new one is available * * Accumulates current time interval and initializes new clocksource @@ -1532,6 +1543,7 @@ u64 timekeeping_max_deferment(void) /** * read_persistent_clock64 - Return time from the persistent clock. + * @ts: Pointer to the storage for the readout value * * Weak dummy function for arches that do not yet support it. * Reads the time from the battery backed persistent clock. @@ -1550,8 +1562,9 @@ void __weak read_persistent_clock64(struct timespec64 *ts) * from the boot. * * Weak dummy function for arches that do not yet support it. - * wall_time - current time as returned by persistent clock - * boot_offset - offset that is defined as wall_time - boot_time + * @wall_time: - current time as returned by persistent clock + * @boot_offset: - offset that is defined as wall_time - boot_time + * * The default function calculates offset based on the current value of * local_clock(). This way architectures that support sched_clock() but don't * support dedicated boot time clock will provide the best estimate of the @@ -1636,7 +1649,8 @@ static struct timespec64 timekeeping_suspend_time; /** * __timekeeping_inject_sleeptime - Internal function to add sleep interval - * @delta: pointer to a timespec delta value + * @tk: Pointer to the timekeeper to be updated + * @delta: Pointer to the delta value in timespec64 format * * Takes a timespec offset measuring a suspend interval and properly * adds the sleep offset to the timekeeping variables. @@ -2007,13 +2021,12 @@ static void timekeeping_adjust(struct timekeeper *tk, s64 offset) } } -/** +/* * accumulate_nsecs_to_secs - Accumulates nsecs into secs * * Helper function that accumulates the nsecs greater than a second * from the xtime_nsec field to the xtime_secs field. * It also calls into the NTP code to handle leapsecond processing. - * */ static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper *tk) { @@ -2055,7 +2068,7 @@ static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper *tk) return clock_set; } -/** +/* * logarithmic_accumulation - shifted accumulation of cycles * * This functions accumulates a shifted interval of cycles into @@ -2291,7 +2304,7 @@ ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq, ktime_t *offs_real, return base; } -/** +/* * timekeeping_validate_timex - Ensures the timex is ok for use in do_adjtimex */ static int timekeeping_validate_timex(const struct __kernel_timex *txc) |