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Diffstat (limited to 'kernel/time/timekeeping.c')
| -rw-r--r-- | kernel/time/timekeeping.c | 2072 |
1 files changed, 2072 insertions, 0 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c new file mode 100644 index 000000000..946acb721 --- /dev/null +++ b/kernel/time/timekeeping.c @@ -0,0 +1,2072 @@ +/* + * linux/kernel/time/timekeeping.c + * + * Kernel timekeeping code and accessor functions + * + * This code was moved from linux/kernel/timer.c. + * Please see that file for copyright and history logs. + * + */ + +#include <linux/timekeeper_internal.h> +#include <linux/module.h> +#include <linux/interrupt.h> +#include <linux/percpu.h> +#include <linux/init.h> +#include <linux/mm.h> +#include <linux/sched.h> +#include <linux/syscore_ops.h> +#include <linux/clocksource.h> +#include <linux/jiffies.h> +#include <linux/time.h> +#include <linux/tick.h> +#include <linux/stop_machine.h> +#include <linux/pvclock_gtod.h> +#include <linux/compiler.h> + +#include "tick-internal.h" +#include "ntp_internal.h" +#include "timekeeping_internal.h" + +#define TK_CLEAR_NTP (1 << 0) +#define TK_MIRROR (1 << 1) +#define TK_CLOCK_WAS_SET (1 << 2) + +/* + * The most important data for readout fits into a single 64 byte + * cache line. + */ +static struct { + seqcount_t seq; + struct timekeeper timekeeper; +} tk_core ____cacheline_aligned; + +static DEFINE_RAW_SPINLOCK(timekeeper_lock); +static struct timekeeper shadow_timekeeper; + +/** + * struct tk_fast - NMI safe timekeeper + * @seq: Sequence counter for protecting updates. The lowest bit + * is the index for the tk_read_base array + * @base: tk_read_base array. Access is indexed by the lowest bit of + * @seq. + * + * See @update_fast_timekeeper() below. + */ +struct tk_fast { + seqcount_t seq; + struct tk_read_base base[2]; +}; + +static struct tk_fast tk_fast_mono ____cacheline_aligned; +static struct tk_fast tk_fast_raw ____cacheline_aligned; + +/* flag for if timekeeping is suspended */ +int __read_mostly timekeeping_suspended; + +static inline void tk_normalize_xtime(struct timekeeper *tk) +{ + while (tk->tkr_mono.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_mono.shift)) { + tk->tkr_mono.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_mono.shift; + tk->xtime_sec++; + } +} + +static inline struct timespec64 tk_xtime(struct timekeeper *tk) +{ + struct timespec64 ts; + + ts.tv_sec = tk->xtime_sec; + ts.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift); + return ts; +} + +static void tk_set_xtime(struct timekeeper *tk, const struct timespec64 *ts) +{ + tk->xtime_sec = ts->tv_sec; + tk->tkr_mono.xtime_nsec = (u64)ts->tv_nsec << tk->tkr_mono.shift; +} + +static void tk_xtime_add(struct timekeeper *tk, const struct timespec64 *ts) +{ + tk->xtime_sec += ts->tv_sec; + tk->tkr_mono.xtime_nsec += (u64)ts->tv_nsec << tk->tkr_mono.shift; + tk_normalize_xtime(tk); +} + +static void tk_set_wall_to_mono(struct timekeeper *tk, struct timespec64 wtm) +{ + struct timespec64 tmp; + + /* + * Verify consistency of: offset_real = -wall_to_monotonic + * before modifying anything + */ + set_normalized_timespec64(&tmp, -tk->wall_to_monotonic.tv_sec, + -tk->wall_to_monotonic.tv_nsec); + WARN_ON_ONCE(tk->offs_real.tv64 != timespec64_to_ktime(tmp).tv64); + tk->wall_to_monotonic = wtm; + set_normalized_timespec64(&tmp, -wtm.tv_sec, -wtm.tv_nsec); + tk->offs_real = timespec64_to_ktime(tmp); + tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tk->tai_offset, 0)); +} + +static inline void tk_update_sleep_time(struct timekeeper *tk, ktime_t delta) +{ + tk->offs_boot = ktime_add(tk->offs_boot, delta); +} + +#ifdef CONFIG_DEBUG_TIMEKEEPING +#define WARNING_FREQ (HZ*300) /* 5 minute rate-limiting */ +/* + * These simple flag variables are managed + * without locks, which is racy, but ok since + * we don't really care about being super + * precise about how many events were seen, + * just that a problem was observed. + */ +static int timekeeping_underflow_seen; +static int timekeeping_overflow_seen; + +/* last_warning is only modified under the timekeeping lock */ +static long timekeeping_last_warning; + +static void timekeeping_check_update(struct timekeeper *tk, cycle_t offset) +{ + + cycle_t max_cycles = tk->tkr_mono.clock->max_cycles; + const char *name = tk->tkr_mono.clock->name; + + if (offset > max_cycles) { + printk_deferred("WARNING: timekeeping: Cycle offset (%lld) is larger than allowed by the '%s' clock's max_cycles value (%lld): time overflow danger\n", + offset, name, max_cycles); + printk_deferred(" timekeeping: Your kernel is sick, but tries to cope by capping time updates\n"); + } else { + if (offset > (max_cycles >> 1)) { + printk_deferred("INFO: timekeeping: Cycle offset (%lld) is larger than the the '%s' clock's 50%% safety margin (%lld)\n", + offset, name, max_cycles >> 1); + printk_deferred(" timekeeping: Your kernel is still fine, but is feeling a bit nervous\n"); + } + } + + if (timekeeping_underflow_seen) { + if (jiffies - timekeeping_last_warning > WARNING_FREQ) { + printk_deferred("WARNING: Underflow in clocksource '%s' observed, time update ignored.\n", name); + printk_deferred(" Please report this, consider using a different clocksource, if possible.\n"); + printk_deferred(" Your kernel is probably still fine.\n"); + timekeeping_last_warning = jiffies; + } + timekeeping_underflow_seen = 0; + } + + if (timekeeping_overflow_seen) { + if (jiffies - timekeeping_last_warning > WARNING_FREQ) { + printk_deferred("WARNING: Overflow in clocksource '%s' observed, time update capped.\n", name); + printk_deferred(" Please report this, consider using a different clocksource, if possible.\n"); + printk_deferred(" Your kernel is probably still fine.\n"); + timekeeping_last_warning = jiffies; + } + timekeeping_overflow_seen = 0; + } +} + +static inline cycle_t timekeeping_get_delta(struct tk_read_base *tkr) +{ + cycle_t now, last, mask, max, delta; + unsigned int seq; + + /* + * Since we're called holding a seqlock, the data may shift + * under us while we're doing the calculation. This can cause + * false positives, since we'd note a problem but throw the + * results away. So nest another seqlock here to atomically + * grab the points we are checking with. + */ + do { + seq = read_seqcount_begin(&tk_core.seq); + now = tkr->read(tkr->clock); + last = tkr->cycle_last; + mask = tkr->mask; + max = tkr->clock->max_cycles; + } while (read_seqcount_retry(&tk_core.seq, seq)); + + delta = clocksource_delta(now, last, mask); + + /* + * Try to catch underflows by checking if we are seeing small + * mask-relative negative values. + */ + if (unlikely((~delta & mask) < (mask >> 3))) { + timekeeping_underflow_seen = 1; + delta = 0; + } + + /* Cap delta value to the max_cycles values to avoid mult overflows */ + if (unlikely(delta > max)) { + timekeeping_overflow_seen = 1; + delta = tkr->clock->max_cycles; + } + + return delta; +} +#else +static inline void timekeeping_check_update(struct timekeeper *tk, cycle_t offset) +{ +} +static inline cycle_t timekeeping_get_delta(struct tk_read_base *tkr) +{ + cycle_t cycle_now, delta; + + /* read clocksource */ + cycle_now = tkr->read(tkr->clock); + + /* calculate the delta since the last update_wall_time */ + delta = clocksource_delta(cycle_now, tkr->cycle_last, tkr->mask); + + return delta; +} +#endif + +/** + * tk_setup_internals - Set up internals to use clocksource clock. + * + * @tk: The target timekeeper to setup. + * @clock: Pointer to clocksource. + * + * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment + * pair and interval request. + * + * Unless you're the timekeeping code, you should not be using this! + */ +static void tk_setup_internals(struct timekeeper *tk, struct clocksource *clock) +{ + cycle_t interval; + u64 tmp, ntpinterval; + struct clocksource *old_clock; + + old_clock = tk->tkr_mono.clock; + tk->tkr_mono.clock = clock; + tk->tkr_mono.read = clock->read; + tk->tkr_mono.mask = clock->mask; + tk->tkr_mono.cycle_last = tk->tkr_mono.read(clock); + + tk->tkr_raw.clock = clock; + tk->tkr_raw.read = clock->read; + tk->tkr_raw.mask = clock->mask; + tk->tkr_raw.cycle_last = tk->tkr_mono.cycle_last; + + /* Do the ns -> cycle conversion first, using original mult */ + tmp = NTP_INTERVAL_LENGTH; + tmp <<= clock->shift; + ntpinterval = tmp; + tmp += clock->mult/2; + do_div(tmp, clock->mult); + if (tmp == 0) + tmp = 1; + + interval = (cycle_t) tmp; + tk->cycle_interval = interval; + + /* Go back from cycles -> shifted ns */ + tk->xtime_interval = (u64) interval * clock->mult; + tk->xtime_remainder = ntpinterval - tk->xtime_interval; + tk->raw_interval = + ((u64) interval * clock->mult) >> clock->shift; + + /* if changing clocks, convert xtime_nsec shift units */ + if (old_clock) { + int shift_change = clock->shift - old_clock->shift; + if (shift_change < 0) + tk->tkr_mono.xtime_nsec >>= -shift_change; + else + tk->tkr_mono.xtime_nsec <<= shift_change; + } + tk->tkr_raw.xtime_nsec = 0; + + tk->tkr_mono.shift = clock->shift; + tk->tkr_raw.shift = clock->shift; + + tk->ntp_error = 0; + tk->ntp_error_shift = NTP_SCALE_SHIFT - clock->shift; + tk->ntp_tick = ntpinterval << tk->ntp_error_shift; + + /* + * The timekeeper keeps its own mult values for the currently + * active clocksource. These value will be adjusted via NTP + * to counteract clock drifting. + */ + tk->tkr_mono.mult = clock->mult; + tk->tkr_raw.mult = clock->mult; + tk->ntp_err_mult = 0; +} + +/* Timekeeper helper functions. */ + +#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET +static u32 default_arch_gettimeoffset(void) { return 0; } +u32 (*arch_gettimeoffset)(void) = default_arch_gettimeoffset; +#else +static inline u32 arch_gettimeoffset(void) { return 0; } +#endif + +static inline s64 timekeeping_get_ns(struct tk_read_base *tkr) +{ + cycle_t delta; + s64 nsec; + + delta = timekeeping_get_delta(tkr); + + nsec = delta * tkr->mult + tkr->xtime_nsec; + nsec >>= tkr->shift; + + /* If arch requires, add in get_arch_timeoffset() */ + return nsec + arch_gettimeoffset(); +} + +/** + * update_fast_timekeeper - Update the fast and NMI safe monotonic timekeeper. + * @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. + * + * So we handle this differently than the other timekeeping accessor + * functions which retry when the sequence count has changed. The + * update side does: + * + * 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], 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], tkr); + * + * The reader side does: + * + * do { + * seq = tkf->seq; + * smp_rmb(); + * idx = seq & 0x01; + * now = now(tkf->base[idx]); + * smp_rmb(); + * } while (seq != tkf->seq) + * + * As long as we update base[0] readers are forced off to + * base[1]. Once base[0] is updated readers are redirected to base[0] + * and the base[1] update takes place. + * + * So if a NMI hits the update of base[0] then it will use base[1] + * which is still consistent. In the worst case this can result is a + * slightly wrong timestamp (a few nanoseconds). See + * @ktime_get_mono_fast_ns. + */ +static void update_fast_timekeeper(struct tk_read_base *tkr, struct tk_fast *tkf) +{ + struct tk_read_base *base = tkf->base; + + /* Force readers off to base[1] */ + raw_write_seqcount_latch(&tkf->seq); + + /* Update base[0] */ + memcpy(base, tkr, sizeof(*base)); + + /* Force readers back to base[0] */ + raw_write_seqcount_latch(&tkf->seq); + + /* Update base[1] */ + memcpy(base + 1, base, sizeof(*base)); +} + +/** + * ktime_get_mono_fast_ns - Fast NMI safe access to clock monotonic + * + * This timestamp is not guaranteed to be monotonic across an update. + * The timestamp is calculated by: + * + * now = base_mono + clock_delta * slope + * + * So if the update lowers the slope, readers who are forced to the + * not yet updated second array are still using the old steeper slope. + * + * tmono + * ^ + * | o n + * | o n + * | u + * | o + * |o + * |12345678---> reader order + * + * o = old slope + * u = update + * n = new slope + * + * So reader 6 will observe time going backwards versus reader 5. + * + * While other CPUs are likely to be able 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(&tkf->seq); + tkr = tkf->base + (seq & 0x01); + now = ktime_to_ns(tkr->base) + timekeeping_get_ns(tkr); + } while (read_seqcount_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); + +u64 ktime_get_raw_fast_ns(void) +{ + return __ktime_get_fast_ns(&tk_fast_raw); +} +EXPORT_SYMBOL_GPL(ktime_get_raw_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_mono; + + 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, &tk_fast_mono); + + tkr = &tk->tkr_raw; + memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy)); + tkr_dummy.read = dummy_clock_read; + update_fast_timekeeper(&tkr_dummy, &tk_fast_raw); +} + +#ifdef CONFIG_GENERIC_TIME_VSYSCALL_OLD + +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); + 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) +{ + raw_notifier_call_chain(&pvclock_gtod_chain, was_set, tk); +} + +/** + * pvclock_gtod_register_notifier - register a pvclock timedata update listener + */ +int pvclock_gtod_register_notifier(struct notifier_block *nb) +{ + struct timekeeper *tk = &tk_core.timekeeper; + unsigned long flags; + int ret; + + raw_spin_lock_irqsave(&timekeeper_lock, flags); + ret = raw_notifier_chain_register(&pvclock_gtod_chain, nb); + update_pvclock_gtod(tk, true); + raw_spin_unlock_irqrestore(&timekeeper_lock, flags); + + return ret; +} +EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier); + +/** + * pvclock_gtod_unregister_notifier - unregister a pvclock + * timedata update listener + */ +int pvclock_gtod_unregister_notifier(struct notifier_block *nb) +{ + unsigned long flags; + int ret; + + raw_spin_lock_irqsave(&timekeeper_lock, flags); + ret = raw_notifier_chain_unregister(&pvclock_gtod_chain, nb); + raw_spin_unlock_irqrestore(&timekeeper_lock, flags); + + return ret; +} +EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier); + +/* + * Update the ktime_t based scalar nsec members of the timekeeper + */ +static inline void tk_update_ktime_data(struct timekeeper *tk) +{ + u64 seconds; + u32 nsec; + + /* + * The xtime based monotonic readout is: + * nsec = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec + now(); + * The ktime based monotonic readout is: + * nsec = base_mono + now(); + * ==> base_mono = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec + */ + seconds = (u64)(tk->xtime_sec + tk->wall_to_monotonic.tv_sec); + nsec = (u32) tk->wall_to_monotonic.tv_nsec; + tk->tkr_mono.base = ns_to_ktime(seconds * NSEC_PER_SEC + nsec); + + /* Update the monotonic raw base */ + tk->tkr_raw.base = timespec64_to_ktime(tk->raw_time); + + /* + * The sum of the nanoseconds portions of xtime and + * wall_to_monotonic can be greater/equal one second. Take + * this into account before updating tk->ktime_sec. + */ + nsec += (u32)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift); + if (nsec >= NSEC_PER_SEC) + seconds++; + tk->ktime_sec = seconds; +} + +/* must hold timekeeper_lock */ +static void timekeeping_update(struct timekeeper *tk, unsigned int action) +{ + if (action & TK_CLEAR_NTP) { + tk->ntp_error = 0; + ntp_clear(); + } + + tk_update_ktime_data(tk); + + update_vsyscall(tk); + update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET); + + if (action & TK_MIRROR) + memcpy(&shadow_timekeeper, &tk_core.timekeeper, + sizeof(tk_core.timekeeper)); + + update_fast_timekeeper(&tk->tkr_mono, &tk_fast_mono); + update_fast_timekeeper(&tk->tkr_raw, &tk_fast_raw); +} + +/** + * timekeeping_forward_now - update clock to the current time + * + * Forward the current clock to update its state since the last call to + * update_wall_time(). This is useful before significant clock changes, + * as it avoids having to deal with this time offset explicitly. + */ +static void timekeeping_forward_now(struct timekeeper *tk) +{ + struct clocksource *clock = tk->tkr_mono.clock; + cycle_t cycle_now, delta; + s64 nsec; + + cycle_now = tk->tkr_mono.read(clock); + delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last, tk->tkr_mono.mask); + tk->tkr_mono.cycle_last = cycle_now; + tk->tkr_raw.cycle_last = cycle_now; + + tk->tkr_mono.xtime_nsec += delta * tk->tkr_mono.mult; + + /* If arch requires, add in get_arch_timeoffset() */ + tk->tkr_mono.xtime_nsec += (u64)arch_gettimeoffset() << tk->tkr_mono.shift; + + tk_normalize_xtime(tk); + + nsec = clocksource_cyc2ns(delta, tk->tkr_raw.mult, tk->tkr_raw.shift); + timespec64_add_ns(&tk->raw_time, nsec); +} + +/** + * __getnstimeofday64 - Returns the time of day in a timespec64. + * @ts: pointer to the timespec to be set + * + * Updates the time of day in the timespec. + * Returns 0 on success, or -ve when suspended (timespec will be undefined). + */ +int __getnstimeofday64(struct timespec64 *ts) +{ + struct timekeeper *tk = &tk_core.timekeeper; + unsigned long seq; + s64 nsecs = 0; + + do { + seq = read_seqcount_begin(&tk_core.seq); + + ts->tv_sec = tk->xtime_sec; + nsecs = timekeeping_get_ns(&tk->tkr_mono); + + } while (read_seqcount_retry(&tk_core.seq, seq)); + + ts->tv_nsec = 0; + timespec64_add_ns(ts, nsecs); + + /* + * Do not bail out early, in case there were callers still using + * the value, even in the face of the WARN_ON. + */ + if (unlikely(timekeeping_suspended)) + return -EAGAIN; + return 0; +} +EXPORT_SYMBOL(__getnstimeofday64); + +/** + * getnstimeofday64 - Returns the time of day in a timespec64. + * @ts: pointer to the timespec64 to be set + * + * Returns the time of day in a timespec64 (WARN if suspended). + */ +void getnstimeofday64(struct timespec64 *ts) +{ + WARN_ON(__getnstimeofday64(ts)); +} +EXPORT_SYMBOL(getnstimeofday64); + +ktime_t ktime_get(void) +{ + struct timekeeper *tk = &tk_core.timekeeper; + unsigned int seq; + ktime_t base; + s64 nsecs; + + WARN_ON(timekeeping_suspended); + + do { + seq = read_seqcount_begin(&tk_core.seq); + base = tk->tkr_mono.base; + nsecs = timekeeping_get_ns(&tk->tkr_mono); + + } while (read_seqcount_retry(&tk_core.seq, seq)); + + return ktime_add_ns(base, nsecs); +} +EXPORT_SYMBOL_GPL(ktime_get); + +static ktime_t *offsets[TK_OFFS_MAX] = { + [TK_OFFS_REAL] = &tk_core.timekeeper.offs_real, + [TK_OFFS_BOOT] = &tk_core.timekeeper.offs_boot, + [TK_OFFS_TAI] = &tk_core.timekeeper.offs_tai, +}; + +ktime_t ktime_get_with_offset(enum tk_offsets offs) +{ + struct timekeeper *tk = &tk_core.timekeeper; + unsigned int seq; + ktime_t base, *offset = offsets[offs]; + s64 nsecs; + + WARN_ON(timekeeping_suspended); + + do { + seq = read_seqcount_begin(&tk_core.seq); + base = ktime_add(tk->tkr_mono.base, *offset); + nsecs = timekeeping_get_ns(&tk->tkr_mono); + + } while (read_seqcount_retry(&tk_core.seq, seq)); + + return ktime_add_ns(base, nsecs); + +} +EXPORT_SYMBOL_GPL(ktime_get_with_offset); + +/** + * ktime_mono_to_any() - convert mononotic time to any other time + * @tmono: time to convert. + * @offs: which offset to use + */ +ktime_t ktime_mono_to_any(ktime_t tmono, enum tk_offsets offs) +{ + ktime_t *offset = offsets[offs]; + unsigned long seq; + ktime_t tconv; + + do { + seq = read_seqcount_begin(&tk_core.seq); + tconv = ktime_add(tmono, *offset); + } while (read_seqcount_retry(&tk_core.seq, seq)); + + return tconv; +} +EXPORT_SYMBOL_GPL(ktime_mono_to_any); + +/** + * ktime_get_raw - Returns the raw monotonic time in ktime_t format + */ +ktime_t ktime_get_raw(void) +{ + struct timekeeper *tk = &tk_core.timekeeper; + unsigned int seq; + ktime_t base; + s64 nsecs; + + do { + seq = read_seqcount_begin(&tk_core.seq); + base = tk->tkr_raw.base; + nsecs = timekeeping_get_ns(&tk->tkr_raw); + + } while (read_seqcount_retry(&tk_core.seq, seq)); + + return ktime_add_ns(base, nsecs); +} +EXPORT_SYMBOL_GPL(ktime_get_raw); + +/** + * ktime_get_ts64 - get the monotonic clock in timespec64 format + * @ts: pointer to timespec variable + * + * The function calculates the monotonic clock from the realtime + * clock and the wall_to_monotonic offset and stores the result + * in normalized timespec64 format in the variable pointed to by @ts. + */ +void ktime_get_ts64(struct timespec64 *ts) +{ + struct timekeeper *tk = &tk_core.timekeeper; + struct timespec64 tomono; + s64 nsec; + unsigned int seq; + + WARN_ON(timekeeping_suspended); + + do { + seq = read_seqcount_begin(&tk_core.seq); + ts->tv_sec = tk->xtime_sec; + nsec = timekeeping_get_ns(&tk->tkr_mono); + tomono = tk->wall_to_monotonic; + + } while (read_seqcount_retry(&tk_core.seq, seq)); + + ts->tv_sec += tomono.tv_sec; + ts->tv_nsec = 0; + timespec64_add_ns(ts, nsec + tomono.tv_nsec); +} +EXPORT_SYMBOL_GPL(ktime_get_ts64); + +/** + * ktime_get_seconds - Get the seconds portion of CLOCK_MONOTONIC + * + * Returns the seconds portion of CLOCK_MONOTONIC with a single non + * serialized read. tk->ktime_sec is of type 'unsigned long' so this + * works on both 32 and 64 bit systems. On 32 bit systems the readout + * covers ~136 years of uptime which should be enough to prevent + * premature wrap arounds. + */ +time64_t ktime_get_seconds(void) +{ + struct timekeeper *tk = &tk_core.timekeeper; + + WARN_ON(timekeeping_suspended); + return tk->ktime_sec; +} +EXPORT_SYMBOL_GPL(ktime_get_seconds); + +/** + * ktime_get_real_seconds - Get the seconds portion of CLOCK_REALTIME + * + * Returns the wall clock seconds since 1970. This replaces the + * get_seconds() interface which is not y2038 safe on 32bit systems. + * + * For 64bit systems the fast access to tk->xtime_sec is preserved. On + * 32bit systems the access must be protected with the sequence + * counter to provide "atomic" access to the 64bit tk->xtime_sec + * value. + */ +time64_t ktime_get_real_seconds(void) +{ + struct timekeeper *tk = &tk_core.timekeeper; + time64_t seconds; + unsigned int seq; + + if (IS_ENABLED(CONFIG_64BIT)) + return tk->xtime_sec; + + do { + seq = read_seqcount_begin(&tk_core.seq); + seconds = tk->xtime_sec; + + } while (read_seqcount_retry(&tk_core.seq, seq)); + + return seconds; +} +EXPORT_SYMBOL_GPL(ktime_get_real_seconds); + +#ifdef CONFIG_NTP_PPS + +/** + * getnstime_raw_and_real - get day and raw monotonic time in timespec format + * @ts_raw: pointer to the timespec to be set to raw monotonic time + * @ts_real: pointer to the timespec to be set to the time of day + * + * This function reads both the time of day and raw monotonic time at the + * same time atomically and stores the resulting timestamps in timespec + * format. + */ +void getnstime_raw_and_real(struct timespec *ts_raw, struct timespec *ts_real) +{ + struct timekeeper *tk = &tk_core.timekeeper; + unsigned long seq; + s64 nsecs_raw, nsecs_real; + + WARN_ON_ONCE(timekeeping_suspended); + + do { + seq = read_seqcount_begin(&tk_core.seq); + + *ts_raw = timespec64_to_timespec(tk->raw_time); + ts_real->tv_sec = tk->xtime_sec; + ts_real->tv_nsec = 0; + + nsecs_raw = timekeeping_get_ns(&tk->tkr_raw); + nsecs_real = timekeeping_get_ns(&tk->tkr_mono); + + } while (read_seqcount_retry(&tk_core.seq, seq)); + + timespec_add_ns(ts_raw, nsecs_raw); + timespec_add_ns(ts_real, nsecs_real); +} +EXPORT_SYMBOL(getnstime_raw_and_real); + +#endif /* CONFIG_NTP_PPS */ + +/** + * do_gettimeofday - Returns the time of day in a timeval + * @tv: pointer to the timeval to be set + * + * NOTE: Users should be converted to using getnstimeofday() + */ +void do_gettimeofday(struct timeval *tv) +{ + struct timespec64 now; + + getnstimeofday64(&now); + tv->tv_sec = now.tv_sec; + tv->tv_usec = now.tv_nsec/1000; +} +EXPORT_SYMBOL(do_gettimeofday); + +/** + * do_settimeofday64 - Sets the time of day. + * @ts: pointer to the timespec64 variable containing the new time + * + * Sets the time of day to the new time and update NTP and notify hrtimers + */ +int do_settimeofday64(const struct timespec64 *ts) +{ + struct timekeeper *tk = &tk_core.timekeeper; + struct timespec64 ts_delta, xt; + unsigned long flags; + + if (!timespec64_valid_strict(ts)) + return -EINVAL; + + raw_spin_lock_irqsave(&timekeeper_lock, flags); + write_seqcount_begin(&tk_core.seq); + + timekeeping_forward_now(tk); + + xt = tk_xtime(tk); + ts_delta.tv_sec = ts->tv_sec - xt.tv_sec; + ts_delta.tv_nsec = ts->tv_nsec - xt.tv_nsec; + + tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts_delta)); + + tk_set_xtime(tk, ts); + + timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET); + + write_seqcount_end(&tk_core.seq); + raw_spin_unlock_irqrestore(&timekeeper_lock, flags); + + /* signal hrtimers about time change */ + clock_was_set(); + + return 0; +} +EXPORT_SYMBOL(do_settimeofday64); + +/** + * timekeeping_inject_offset - Adds or subtracts from the current time. + * @tv: pointer to the timespec variable containing the offset + * + * Adds or subtracts an offset value from the current time. + */ +int timekeeping_inject_offset(struct timespec *ts) +{ + struct timekeeper *tk = &tk_core.timekeeper; + unsigned long flags; + struct timespec64 ts64, tmp; + int ret = 0; + + if ((unsigned long)ts->tv_nsec >= NSEC_PER_SEC) + return -EINVAL; + + ts64 = timespec_to_timespec64(*ts); + + raw_spin_lock_irqsave(&timekeeper_lock, flags); + write_seqcount_begin(&tk_core.seq); + + timekeeping_forward_now(tk); + + /* Make sure the proposed value is valid */ + tmp = timespec64_add(tk_xtime(tk), ts64); + if (!timespec64_valid_strict(&tmp)) { + ret = -EINVAL; + goto error; + } + + tk_xtime_add(tk, &ts64); + tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts64)); + +error: /* even if we error out, we forwarded the time, so call update */ + timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET); + + write_seqcount_end(&tk_core.seq); + raw_spin_unlock_irqrestore(&timekeeper_lock, flags); + + /* signal hrtimers about time change */ + clock_was_set(); + + return ret; +} +EXPORT_SYMBOL(timekeeping_inject_offset); + + +/** + * timekeeping_get_tai_offset - Returns current TAI offset from UTC + * + */ +s32 timekeeping_get_tai_offset(void) +{ + struct timekeeper *tk = &tk_core.timekeeper; + unsigned int seq; + s32 ret; + + do { + seq = read_seqcount_begin(&tk_core.seq); + ret = tk->tai_offset; + } while (read_seqcount_retry(&tk_core.seq, seq)); + + return ret; +} + +/** + * __timekeeping_set_tai_offset - Lock free worker function + * + */ +static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset) +{ + tk->tai_offset = tai_offset; + tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tai_offset, 0)); +} + +/** + * timekeeping_set_tai_offset - Sets the current TAI offset from UTC + * + */ +void timekeeping_set_tai_offset(s32 tai_offset) +{ + struct timekeeper *tk = &tk_core.timekeeper; + unsigned long flags; + + raw_spin_lock_irqsave(&timekeeper_lock, flags); + write_seqcount_begin(&tk_core.seq); + __timekeeping_set_tai_offset(tk, tai_offset); + timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET); + write_seqcount_end(&tk_core.seq); + raw_spin_unlock_irqrestore(&timekeeper_lock, flags); + clock_was_set(); +} + +/** + * change_clocksource - Swaps clocksources if a new one is available + * + * Accumulates current time interval and initializes new clocksource + */ +static int change_clocksource(void *data) +{ + struct timekeeper *tk = &tk_core.timekeeper; + struct clocksource *new, *old; + unsigned long flags; + + new = (struct clocksource *) data; + + raw_spin_lock_irqsave(&timekeeper_lock, flags); + write_seqcount_begin(&tk_core.seq); + + timekeeping_forward_now(tk); + /* + * If the cs is in module, get a module reference. Succeeds + * for built-in code (owner == NULL) as well. + */ + if (try_module_get(new->owner)) { + if (!new->enable || new->enable(new) == 0) { + old = tk->tkr_mono.clock; + tk_setup_internals(tk, new); + if (old->disable) + old->disable(old); + module_put(old->owner); + } else { + module_put(new->owner); + } + } + timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET); + + write_seqcount_end(&tk_core.seq); + raw_spin_unlock_irqrestore(&timekeeper_lock, flags); + + return 0; +} + +/** + * timekeeping_notify - Install a new clock source + * @clock: pointer to the clock source + * + * This function is called from clocksource.c after a new, better clock + * source has been registered. The caller holds the clocksource_mutex. + */ +int timekeeping_notify(struct clocksource *clock) +{ + struct timekeeper *tk = &tk_core.timekeeper; + + if (tk->tkr_mono.clock == clock) + return 0; + stop_machine(change_clocksource, clock, NULL); + tick_clock_notify(); + return tk->tkr_mono.clock == clock ? 0 : -1; +} + +/** + * getrawmonotonic64 - Returns the raw monotonic time in a timespec + * @ts: pointer to the timespec64 to be set + * + * Returns the raw monotonic time (completely un-modified by ntp) + */ +void getrawmonotonic64(struct timespec64 *ts) +{ + struct timekeeper *tk = &tk_core.timekeeper; + struct timespec64 ts64; + unsigned long seq; + s64 nsecs; + + do { + seq = read_seqcount_begin(&tk_core.seq); + nsecs = timekeeping_get_ns(&tk->tkr_raw); + ts64 = tk->raw_time; + + } while (read_seqcount_retry(&tk_core.seq, seq)); + + timespec64_add_ns(&ts64, nsecs); + *ts = ts64; +} +EXPORT_SYMBOL(getrawmonotonic64); + + +/** + * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres + */ +int timekeeping_valid_for_hres(void) +{ + struct timekeeper *tk = &tk_core.timekeeper; + unsigned long seq; + int ret; + + do { + seq = read_seqcount_begin(&tk_core.seq); + + ret = tk->tkr_mono.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES; + + } while (read_seqcount_retry(&tk_core.seq, seq)); + + return ret; +} + +/** + * timekeeping_max_deferment - Returns max time the clocksource can be deferred + */ +u64 timekeeping_max_deferment(void) +{ + struct timekeeper *tk = &tk_core.timekeeper; + unsigned long seq; + u64 ret; + + do { + seq = read_seqcount_begin(&tk_core.seq); + + ret = tk->tkr_mono.clock->max_idle_ns; + + } while (read_seqcount_retry(&tk_core.seq, seq)); + + return ret; +} + +/** + * read_persistent_clock - Return time from the persistent clock. + * + * Weak dummy function for arches that do not yet support it. + * Reads the time from the battery backed persistent clock. + * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported. + * + * XXX - Do be sure to remove it once all arches implement it. + */ +void __weak read_persistent_clock(struct timespec *ts) +{ + ts->tv_sec = 0; + ts->tv_nsec = 0; +} + +void __weak read_persistent_clock64(struct timespec64 *ts64) +{ + struct timespec ts; + + read_persistent_clock(&ts); + *ts64 = timespec_to_timespec64(ts); +} + +/** + * read_boot_clock - Return time of the system start. + * + * Weak dummy function for arches that do not yet support it. + * Function to read the exact time the system has been started. + * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported. + * + * XXX - Do be sure to remove it once all arches implement it. + */ +void __weak read_boot_clock(struct timespec *ts) +{ + ts->tv_sec = 0; + ts->tv_nsec = 0; +} + +void __weak read_boot_clock64(struct timespec64 *ts64) +{ + struct timespec ts; + + read_boot_clock(&ts); + *ts64 = timespec_to_timespec64(ts); +} + +/* Flag for if timekeeping_resume() has injected sleeptime */ +static bool sleeptime_injected; + +/* Flag for if there is a persistent clock on this platform */ +static bool persistent_clock_exists; + +/* + * timekeeping_init - Initializes the clocksource and common timekeeping values + */ +void __init timekeeping_init(void) +{ + struct timekeeper *tk = &tk_core.timekeeper; + struct clocksource *clock; + unsigned long flags; + struct timespec64 now, boot, tmp; + + read_persistent_clock64(&now); + if (!timespec64_valid_strict(&now)) { + pr_warn("WARNING: Persistent clock returned invalid value!\n" + " Check your CMOS/BIOS settings.\n"); + now.tv_sec = 0; + now.tv_nsec = 0; + } else if (now.tv_sec || now.tv_nsec) + persistent_clock_exists = true; + + read_boot_clock64(&boot); + if (!timespec64_valid_strict(&boot)) { + pr_warn("WARNING: Boot clock returned invalid value!\n" + " Check your CMOS/BIOS settings.\n"); + boot.tv_sec = 0; + boot.tv_nsec = 0; + } + + raw_spin_lock_irqsave(&timekeeper_lock, flags); + write_seqcount_begin(&tk_core.seq); + ntp_init(); + + clock = clocksource_default_clock(); + if (clock->enable) + clock->enable(clock); + tk_setup_internals(tk, clock); + + tk_set_xtime(tk, &now); + tk->raw_time.tv_sec = 0; + tk->raw_time.tv_nsec = 0; + if (boot.tv_sec == 0 && boot.tv_nsec == 0) + boot = tk_xtime(tk); + + set_normalized_timespec64(&tmp, -boot.tv_sec, -boot.tv_nsec); + tk_set_wall_to_mono(tk, tmp); + + timekeeping_update(tk, TK_MIRROR); + + write_seqcount_end(&tk_core.seq); + raw_spin_unlock_irqrestore(&timekeeper_lock, flags); +} + +/* time in seconds when suspend began for persistent clock */ +static struct timespec64 timekeeping_suspend_time; + +/** + * __timekeeping_inject_sleeptime - Internal function to add sleep interval + * @delta: pointer to a timespec delta value + * + * Takes a timespec offset measuring a suspend interval and properly + * adds the sleep offset to the timekeeping variables. + */ +static void __timekeeping_inject_sleeptime(struct timekeeper *tk, + struct timespec64 *delta) +{ + if (!timespec64_valid_strict(delta)) { + printk_deferred(KERN_WARNING + "__timekeeping_inject_sleeptime: Invalid " + "sleep delta value!\n"); + return; + } + tk_xtime_add(tk, delta); + tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *delta)); + tk_update_sleep_time(tk, timespec64_to_ktime(*delta)); + tk_debug_account_sleep_time(delta); +} + +#if defined(CONFIG_PM_SLEEP) && defined(CONFIG_RTC_HCTOSYS_DEVICE) +/** + * We have three kinds of time sources to use for sleep time + * injection, the preference order is: + * 1) non-stop clocksource + * 2) persistent clock (ie: RTC accessible when irqs are off) + * 3) RTC + * + * 1) and 2) are used by timekeeping, 3) by RTC subsystem. + * If system has neither 1) nor 2), 3) will be used finally. + * + * + * If timekeeping has injected sleeptime via either 1) or 2), + * 3) becomes needless, so in this case we don't need to call + * rtc_resume(), and this is what timekeeping_rtc_skipresume() + * means. + */ +bool timekeeping_rtc_skipresume(void) +{ + return sleeptime_injected; +} + +/** + * 1) can be determined whether to use or not only when doing + * timekeeping_resume() which is invoked after rtc_suspend(), + * so we can't skip rtc_suspend() surely if system has 1). + * + * But if system has 2), 2) will definitely be used, so in this + * case we don't need to call rtc_suspend(), and this is what + * timekeeping_rtc_skipsuspend() means. + */ +bool timekeeping_rtc_skipsuspend(void) +{ + return persistent_clock_exists; +} + +/** + * timekeeping_inject_sleeptime64 - Adds suspend interval to timeekeeping values + * @delta: pointer to a timespec64 delta value + * + * This hook is for architectures that cannot support read_persistent_clock64 + * because their RTC/persistent clock is only accessible when irqs are enabled. + * and also don't have an effective nonstop clocksource. + * + * This function should only be called by rtc_resume(), and allows + * a suspend offset to be injected into the timekeeping values. + */ +void timekeeping_inject_sleeptime64(struct timespec64 *delta) +{ + struct timekeeper *tk = &tk_core.timekeeper; + unsigned long flags; + + raw_spin_lock_irqsave(&timekeeper_lock, flags); + write_seqcount_begin(&tk_core.seq); + + timekeeping_forward_now(tk); + + __timekeeping_inject_sleeptime(tk, delta); + + timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET); + + write_seqcount_end(&tk_core.seq); + raw_spin_unlock_irqrestore(&timekeeper_lock, flags); + + /* signal hrtimers about time change */ + clock_was_set(); +} +#endif + +/** + * timekeeping_resume - Resumes the generic timekeeping subsystem. + */ +void timekeeping_resume(void) +{ + struct timekeeper *tk = &tk_core.timekeeper; + struct clocksource *clock = tk->tkr_mono.clock; + unsigned long flags; + struct timespec64 ts_new, ts_delta; + cycle_t cycle_now, cycle_delta; + + sleeptime_injected = false; + read_persistent_clock64(&ts_new); + + clockevents_resume(); + clocksource_resume(); + + raw_spin_lock_irqsave(&timekeeper_lock, flags); + write_seqcount_begin(&tk_core.seq); + + /* + * After system resumes, we need to calculate the suspended time and + * compensate it for the OS time. There are 3 sources that could be + * used: Nonstop clocksource during suspend, persistent clock and rtc + * device. + * + * One specific platform may have 1 or 2 or all of them, and the + * preference will be: + * suspend-nonstop clocksource -> persistent clock -> rtc + * The less preferred source will only be tried if there is no better + * usable source. The rtc part is handled separately in rtc core code. + */ + cycle_now = tk->tkr_mono.read(clock); + if ((clock->flags & CLOCK_SOURCE_SUSPEND_NONSTOP) && + cycle_now > tk->tkr_mono.cycle_last) { + u64 num, max = ULLONG_MAX; + u32 mult = clock->mult; + u32 shift = clock->shift; + s64 nsec = 0; + + cycle_delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last, + tk->tkr_mono.mask); + + /* + * "cycle_delta * mutl" may cause 64 bits overflow, if the + * suspended time is too long. In that case we need do the + * 64 bits math carefully + */ + do_div(max, mult); + if (cycle_delta > max) { + num = div64_u64(cycle_delta, max); + nsec = (((u64) max * mult) >> shift) * num; + cycle_delta -= num * max; + } + nsec += ((u64) cycle_delta * mult) >> shift; + + ts_delta = ns_to_timespec64(nsec); + sleeptime_injected = true; + } else if (timespec64_compare(&ts_new, &timekeeping_suspend_time) > 0) { + ts_delta = timespec64_sub(ts_new, timekeeping_suspend_time); + sleeptime_injected = true; + } + + if (sleeptime_injected) + __timekeeping_inject_sleeptime(tk, &ts_delta); + + /* Re-base the last cycle value */ + tk->tkr_mono.cycle_last = cycle_now; + tk->tkr_raw.cycle_last = cycle_now; + + tk->ntp_error = 0; + timekeeping_suspended = 0; + timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET); + write_seqcount_end(&tk_core.seq); + raw_spin_unlock_irqrestore(&timekeeper_lock, flags); + + touch_softlockup_watchdog(); + + tick_resume(); + hrtimers_resume(); +} + +int timekeeping_suspend(void) +{ + struct timekeeper *tk = &tk_core.timekeeper; + unsigned long flags; + struct timespec64 delta, delta_delta; + static struct timespec64 old_delta; + + read_persistent_clock64(&timekeeping_suspend_time); + + /* + * On some systems the persistent_clock can not be detected at + * timekeeping_init by its return value, so if we see a valid + * value returned, update the persistent_clock_exists flag. + */ + if (timekeeping_suspend_time.tv_sec || timekeeping_suspend_time.tv_nsec) + persistent_clock_exists = true; + + raw_spin_lock_irqsave(&timekeeper_lock, flags); + write_seqcount_begin(&tk_core.seq); + timekeeping_forward_now(tk); + timekeeping_suspended = 1; + + if (persistent_clock_exists) { + /* + * To avoid drift caused by repeated suspend/resumes, + * which each can add ~1 second drift error, + * try to compensate so the difference in system time + * and persistent_clock time stays close to constant. + */ + delta = timespec64_sub(tk_xtime(tk), timekeeping_suspend_time); + delta_delta = timespec64_sub(delta, old_delta); + if (abs(delta_delta.tv_sec) >= 2) { + /* + * if delta_delta is too large, assume time correction + * has occurred and set old_delta to the current delta. + */ + old_delta = delta; + } else { + /* Otherwise try to adjust old_system to compensate */ + timekeeping_suspend_time = + timespec64_add(timekeeping_suspend_time, delta_delta); + } + } + + timekeeping_update(tk, TK_MIRROR); + halt_fast_timekeeper(tk); + write_seqcount_end(&tk_core.seq); + raw_spin_unlock_irqrestore(&timekeeper_lock, flags); + + tick_suspend(); + clocksource_suspend(); + clockevents_suspend(); + + return 0; +} + +/* sysfs resume/suspend bits for timekeeping */ +static struct syscore_ops timekeeping_syscore_ops = { + .resume = timekeeping_resume, + .suspend = timekeeping_suspend, +}; + +static int __init timekeeping_init_ops(void) +{ + register_syscore_ops(&timekeeping_syscore_ops); + return 0; +} +device_initcall(timekeeping_init_ops); + +/* + * Apply a multiplier adjustment to the timekeeper + */ +static __always_inline void timekeeping_apply_adjustment(struct timekeeper *tk, + s64 offset, + bool negative, + int adj_scale) +{ + s64 interval = tk->cycle_interval; + s32 mult_adj = 1; + + if (negative) { + mult_adj = -mult_adj; + interval = -interval; + offset = -offset; + } + mult_adj <<= adj_scale; + interval <<= adj_scale; + offset <<= adj_scale; + + /* + * So the following can be confusing. + * + * To keep things simple, lets assume mult_adj == 1 for now. + * + * When mult_adj != 1, remember that the interval and offset values + * have been appropriately scaled so the math is the same. + * + * The basic idea here is that we're increasing the multiplier + * by one, this causes the xtime_interval to be incremented by + * one cycle_interval. This is because: + * xtime_interval = cycle_interval * mult + * So if mult is being incremented by one: + * xtime_interval = cycle_interval * (mult + 1) + * Its the same as: + * xtime_interval = (cycle_interval * mult) + cycle_interval + * Which can be shortened to: + * xtime_interval += cycle_interval + * + * So offset stores the non-accumulated cycles. Thus the current + * time (in shifted nanoseconds) is: + * now = (offset * adj) + xtime_nsec + * Now, even though we're adjusting the clock frequency, we have + * to keep time consistent. In other words, we can't jump back + * in time, and we also want to avoid jumping forward in time. + * + * So given the same offset value, we need the time to be the same + * both before and after the freq adjustment. + * now = (offset * adj_1) + xtime_nsec_1 + * now = (offset * adj_2) + xtime_nsec_2 + * So: + * (offset * adj_1) + xtime_nsec_1 = + * (offset * adj_2) + xtime_nsec_2 + * And we know: + * adj_2 = adj_1 + 1 + * So: + * (offset * adj_1) + xtime_nsec_1 = + * (offset * (adj_1+1)) + xtime_nsec_2 + * (offset * adj_1) + xtime_nsec_1 = + * (offset * adj_1) + offset + xtime_nsec_2 + * Canceling the sides: + * xtime_nsec_1 = offset + xtime_nsec_2 + * Which gives us: + * xtime_nsec_2 = xtime_nsec_1 - offset + * Which simplfies to: + * xtime_nsec -= offset + * + * XXX - TODO: Doc ntp_error calculation. + */ + if ((mult_adj > 0) && (tk->tkr_mono.mult + mult_adj < mult_adj)) { + /* NTP adjustment caused clocksource mult overflow */ + WARN_ON_ONCE(1); + return; + } + + tk->tkr_mono.mult += mult_adj; + tk->xtime_interval += interval; + tk->tkr_mono.xtime_nsec -= offset; + tk->ntp_error -= (interval - offset) << tk->ntp_error_shift; +} + +/* + * Calculate the multiplier adjustment needed to match the frequency + * specified by NTP + */ +static __always_inline void timekeeping_freqadjust(struct timekeeper *tk, + s64 offset) +{ + s64 interval = tk->cycle_interval; + s64 xinterval = tk->xtime_interval; + s64 tick_error; + bool negative; + u32 adj; + + /* Remove any current error adj from freq calculation */ + if (tk->ntp_err_mult) + xinterval -= tk->cycle_interval; + + tk->ntp_tick = ntp_tick_length(); + + /* Calculate current error per tick */ + tick_error = ntp_tick_length() >> tk->ntp_error_shift; + tick_error -= (xinterval + tk->xtime_remainder); + + /* Don't worry about correcting it if its small */ + if (likely((tick_error >= 0) && (tick_error <= interval))) + return; + + /* preserve the direction of correction */ + negative = (tick_error < 0); + + /* Sort out the magnitude of the correction */ + tick_error = abs(tick_error); + for (adj = 0; tick_error > interval; adj++) + tick_error >>= 1; + + /* scale the corrections */ + timekeeping_apply_adjustment(tk, offset, negative, adj); +} + +/* + * Adjust the timekeeper's multiplier to the correct frequency + * and also to reduce the accumulated error value. + */ +static void timekeeping_adjust(struct timekeeper *tk, s64 offset) +{ + /* Correct for the current frequency error */ + timekeeping_freqadjust(tk, offset); + + /* Next make a small adjustment to fix any cumulative error */ + if (!tk->ntp_err_mult && (tk->ntp_error > 0)) { + tk->ntp_err_mult = 1; + timekeeping_apply_adjustment(tk, offset, 0, 0); + } else if (tk->ntp_err_mult && (tk->ntp_error <= 0)) { + /* Undo any existing error adjustment */ + timekeeping_apply_adjustment(tk, offset, 1, 0); + tk->ntp_err_mult = 0; + } + + if (unlikely(tk->tkr_mono.clock->maxadj && + (abs(tk->tkr_mono.mult - tk->tkr_mono.clock->mult) + > tk->tkr_mono.clock->maxadj))) { + printk_once(KERN_WARNING + "Adjusting %s more than 11%% (%ld vs %ld)\n", + tk->tkr_mono.clock->name, (long)tk->tkr_mono.mult, + (long)tk->tkr_mono.clock->mult + tk->tkr_mono.clock->maxadj); + } + + /* + * It may be possible that when we entered this function, xtime_nsec + * was very small. Further, if we're slightly speeding the clocksource + * in the code above, its possible the required corrective factor to + * xtime_nsec could cause it to underflow. + * + * Now, since we already accumulated the second, cannot simply roll + * the accumulated second back, since the NTP subsystem has been + * notified via second_overflow. So instead we push xtime_nsec forward + * by the amount we underflowed, and add that amount into the error. + * + * We'll correct this error next time through this function, when + * xtime_nsec is not as small. + */ + if (unlikely((s64)tk->tkr_mono.xtime_nsec < 0)) { + s64 neg = -(s64)tk->tkr_mono.xtime_nsec; + tk->tkr_mono.xtime_nsec = 0; + tk->ntp_error += neg << tk->ntp_error_shift; + } +} + +/** + * accumulate_nsecs_to_secs - Accumulates nsecs into secs + * + * Helper function that accumulates a the nsecs greater then 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) +{ + u64 nsecps = (u64)NSEC_PER_SEC << tk->tkr_mono.shift; + unsigned int clock_set = 0; + + while (tk->tkr_mono.xtime_nsec >= nsecps) { + int leap; + + tk->tkr_mono.xtime_nsec -= nsecps; + tk->xtime_sec++; + + /* Figure out if its a leap sec and apply if needed */ + leap = second_overflow(tk->xtime_sec); + if (unlikely(leap)) { + struct timespec64 ts; + + tk->xtime_sec += leap; + + ts.tv_sec = leap; + ts.tv_nsec = 0; + tk_set_wall_to_mono(tk, + timespec64_sub(tk->wall_to_monotonic, ts)); + + __timekeeping_set_tai_offset(tk, tk->tai_offset - leap); + + clock_set = TK_CLOCK_WAS_SET; + } + } + return clock_set; +} + +/** + * logarithmic_accumulation - shifted accumulation of cycles + * + * This functions accumulates a shifted interval of cycles into + * into a shifted interval nanoseconds. Allows for O(log) accumulation + * loop. + * + * Returns the unconsumed cycles. + */ +static cycle_t logarithmic_accumulation(struct timekeeper *tk, cycle_t offset, + u32 shift, + unsigned int *clock_set) +{ + cycle_t interval = tk->cycle_interval << shift; + u64 raw_nsecs; + + /* If the offset is smaller then a shifted interval, do nothing */ + if (offset < interval) + return offset; + + /* Accumulate one shifted interval */ + offset -= interval; + tk->tkr_mono.cycle_last += interval; + tk->tkr_raw.cycle_last += interval; + + tk->tkr_mono.xtime_nsec += tk->xtime_interval << shift; + *clock_set |= accumulate_nsecs_to_secs(tk); + + /* Accumulate raw time */ + raw_nsecs = (u64)tk->raw_interval << shift; + raw_nsecs += tk->raw_time.tv_nsec; + if (raw_nsecs >= NSEC_PER_SEC) { + u64 raw_secs = raw_nsecs; + raw_nsecs = do_div(raw_secs, NSEC_PER_SEC); + tk->raw_time.tv_sec += raw_secs; + } + tk->raw_time.tv_nsec = raw_nsecs; + + /* Accumulate error between NTP and clock interval */ + tk->ntp_error += tk->ntp_tick << shift; + tk->ntp_error -= (tk->xtime_interval + tk->xtime_remainder) << + (tk->ntp_error_shift + shift); + + return offset; +} + +/** + * update_wall_time - Uses the current clocksource to increment the wall time + * + */ +void update_wall_time(void) +{ + struct timekeeper *real_tk = &tk_core.timekeeper; + struct timekeeper *tk = &shadow_timekeeper; + cycle_t offset; + int shift = 0, maxshift; + unsigned int clock_set = 0; + unsigned long flags; + + raw_spin_lock_irqsave(&timekeeper_lock, flags); + + /* Make sure we're fully resumed: */ + if (unlikely(timekeeping_suspended)) + goto out; + +#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET + offset = real_tk->cycle_interval; +#else + offset = clocksource_delta(tk->tkr_mono.read(tk->tkr_mono.clock), + tk->tkr_mono.cycle_last, tk->tkr_mono.mask); +#endif + + /* Check if there's really nothing to do */ + if (offset < real_tk->cycle_interval) + goto out; + + /* Do some additional sanity checking */ + timekeeping_check_update(real_tk, offset); + + /* + * With NO_HZ we may have to accumulate many cycle_intervals + * (think "ticks") worth of time at once. To do this efficiently, + * we calculate the largest doubling multiple of cycle_intervals + * that is smaller than the offset. We then accumulate that + * chunk in one go, and then try to consume the next smaller + * doubled multiple. + */ + shift = ilog2(offset) - ilog2(tk->cycle_interval); + shift = max(0, shift); + /* Bound shift to one less than what overflows tick_length */ + maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1; + shift = min(shift, maxshift); + while (offset >= tk->cycle_interval) { + offset = logarithmic_accumulation(tk, offset, shift, + &clock_set); + if (offset < tk->cycle_interval<<shift) + shift--; + } + + /* 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 + */ + clock_set |= accumulate_nsecs_to_secs(tk); + + write_seqcount_begin(&tk_core.seq); + /* + * Update the real timekeeper. + * + * We could avoid this memcpy by switching pointers, but that + * requires changes to all other timekeeper usage sites as + * well, i.e. move the timekeeper pointer getter into the + * spinlocked/seqcount protected sections. And we trade this + * memcpy under the tk_core.seq against one before we start + * updating. + */ + memcpy(real_tk, tk, sizeof(*tk)); + timekeeping_update(real_tk, clock_set); + write_seqcount_end(&tk_core.seq); +out: + raw_spin_unlock_irqrestore(&timekeeper_lock, flags); + if (clock_set) + /* Have to call _delayed version, since in irq context*/ + clock_was_set_delayed(); +} + +/** + * getboottime64 - Return the real time of system boot. + * @ts: pointer to the timespec64 to be set + * + * 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 getboottime64(struct timespec64 *ts) +{ + struct timekeeper *tk = &tk_core.timekeeper; + ktime_t t = ktime_sub(tk->offs_real, tk->offs_boot); + + *ts = ktime_to_timespec64(t); +} +EXPORT_SYMBOL_GPL(getboottime64); + +unsigned long get_seconds(void) +{ + struct timekeeper *tk = &tk_core.timekeeper; + + return tk->xtime_sec; +} +EXPORT_SYMBOL(get_seconds); + +struct timespec __current_kernel_time(void) +{ + struct timekeeper *tk = &tk_core.timekeeper; + + return timespec64_to_timespec(tk_xtime(tk)); +} + +struct timespec current_kernel_time(void) +{ + struct timekeeper *tk = &tk_core.timekeeper; + struct timespec64 now; + unsigned long seq; + + do { + seq = read_seqcount_begin(&tk_core.seq); + + now = tk_xtime(tk); + } while (read_seqcount_retry(&tk_core.seq, seq)); + + return timespec64_to_timespec(now); +} +EXPORT_SYMBOL(current_kernel_time); + +struct timespec64 get_monotonic_coarse64(void) +{ + struct timekeeper *tk = &tk_core.timekeeper; + struct timespec64 now, mono; + unsigned long seq; + + do { + seq = read_seqcount_begin(&tk_core.seq); + + now = tk_xtime(tk); + mono = tk->wall_to_monotonic; + } while (read_seqcount_retry(&tk_core.seq, seq)); + + set_normalized_timespec64(&now, now.tv_sec + mono.tv_sec, + now.tv_nsec + mono.tv_nsec); + + return now; +} + +/* + * Must hold jiffies_lock + */ +void do_timer(unsigned long ticks) +{ + jiffies_64 += ticks; + calc_global_load(ticks); +} + +/** + * ktime_get_update_offsets_tick - hrtimer helper + * @offs_real: pointer to storage for monotonic -> realtime offset + * @offs_boot: pointer to storage for monotonic -> boottime offset + * @offs_tai: pointer to storage for monotonic -> clock tai offset + * + * Returns monotonic time at last tick and various offsets + */ +ktime_t ktime_get_update_offsets_tick(ktime_t *offs_real, ktime_t *offs_boot, + ktime_t *offs_tai) +{ + struct timekeeper *tk = &tk_core.timekeeper; + unsigned int seq; + ktime_t base; + u64 nsecs; + + do { + seq = read_seqcount_begin(&tk_core.seq); + + base = tk->tkr_mono.base; + nsecs = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift; + + *offs_real = tk->offs_real; + *offs_boot = tk->offs_boot; + *offs_tai = tk->offs_tai; + } while (read_seqcount_retry(&tk_core.seq, seq)); + + return ktime_add_ns(base, nsecs); +} + +#ifdef CONFIG_HIGH_RES_TIMERS +/** + * ktime_get_update_offsets_now - hrtimer helper + * @offs_real: pointer to storage for monotonic -> realtime offset + * @offs_boot: pointer to storage for monotonic -> boottime offset + * @offs_tai: pointer to storage for monotonic -> clock tai offset + * + * Returns current monotonic time and updates the offsets + * Called from hrtimer_interrupt() or retrigger_next_event() + */ +ktime_t ktime_get_update_offsets_now(ktime_t *offs_real, ktime_t *offs_boot, + ktime_t *offs_tai) +{ + struct timekeeper *tk = &tk_core.timekeeper; + unsigned int seq; + ktime_t base; + u64 nsecs; + + do { + seq = read_seqcount_begin(&tk_core.seq); + + base = tk->tkr_mono.base; + nsecs = timekeeping_get_ns(&tk->tkr_mono); + + *offs_real = tk->offs_real; + *offs_boot = tk->offs_boot; + *offs_tai = tk->offs_tai; + } while (read_seqcount_retry(&tk_core.seq, seq)); + + return ktime_add_ns(base, nsecs); +} +#endif + +/** + * do_adjtimex() - Accessor function to NTP __do_adjtimex function + */ +int do_adjtimex(struct timex *txc) +{ + struct timekeeper *tk = &tk_core.timekeeper; + unsigned long flags; + struct timespec64 ts; + s32 orig_tai, tai; + int ret; + + /* Validate the data before disabling interrupts */ + ret = ntp_validate_timex(txc); + if (ret) + return ret; + + if (txc->modes & ADJ_SETOFFSET) { + struct timespec delta; + delta.tv_sec = txc->time.tv_sec; + delta.tv_nsec = txc->time.tv_usec; + if (!(txc->modes & ADJ_NANO)) + delta.tv_nsec *= 1000; + ret = timekeeping_inject_offset(&delta); + if (ret) + return ret; + } + + getnstimeofday64(&ts); + + raw_spin_lock_irqsave(&timekeeper_lock, flags); + write_seqcount_begin(&tk_core.seq); + + orig_tai = tai = tk->tai_offset; + ret = __do_adjtimex(txc, &ts, &tai); + + if (tai != orig_tai) { + __timekeeping_set_tai_offset(tk, tai); + timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET); + } + write_seqcount_end(&tk_core.seq); + raw_spin_unlock_irqrestore(&timekeeper_lock, flags); + + if (tai != orig_tai) + clock_was_set(); + + ntp_notify_cmos_timer(); + + return ret; +} + +#ifdef CONFIG_NTP_PPS +/** + * hardpps() - Accessor function to NTP __hardpps function + */ +void hardpps(const struct timespec *phase_ts, const struct timespec *raw_ts) +{ + unsigned long flags; + + raw_spin_lock_irqsave(&timekeeper_lock, flags); + write_seqcount_begin(&tk_core.seq); + + __hardpps(phase_ts, raw_ts); + + write_seqcount_end(&tk_core.seq); + raw_spin_unlock_irqrestore(&timekeeper_lock, flags); +} +EXPORT_SYMBOL(hardpps); +#endif + +/** + * xtime_update() - advances the timekeeping infrastructure + * @ticks: number of ticks, that have elapsed since the last call. + * + * Must be called with interrupts disabled. + */ +void xtime_update(unsigned long ticks) +{ + write_seqlock(&jiffies_lock); + do_timer(ticks); + write_sequnlock(&jiffies_lock); + update_wall_time(); +} |