diff options
Diffstat (limited to 'kernel/time/timekeeping.c')
| -rw-r--r-- | kernel/time/timekeeping.c | 2414 |
1 files changed, 2414 insertions, 0 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c new file mode 100644 index 000000000..087f71183 --- /dev/null +++ b/kernel/time/timekeeping.c @@ -0,0 +1,2414 @@ +/* + * 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/nmi.h> +#include <linux/sched.h> +#include <linux/sched/loadavg.h> +#include <linux/sched/clock.h> +#include <linux/syscore_ops.h> +#include <linux/clocksource.h> +#include <linux/jiffies.h> +#include <linux/time.h> +#include <linux/timex.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) + +enum timekeeping_adv_mode { + /* Update timekeeper when a tick has passed */ + TK_ADV_TICK, + + /* Update timekeeper on a direct frequency change */ + TK_ADV_FREQ +}; + +/* + * 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 = { + .seq = SEQCNT_ZERO(tk_core.seq), +}; + +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]; +}; + +/* Suspend-time cycles value for halted fast timekeeper. */ +static u64 cycles_at_suspend; + +static u64 dummy_clock_read(struct clocksource *cs) +{ + return cycles_at_suspend; +} + +static struct clocksource dummy_clock = { + .read = dummy_clock_read, +}; + +static struct tk_fast tk_fast_mono ____cacheline_aligned = { + .base[0] = { .clock = &dummy_clock, }, + .base[1] = { .clock = &dummy_clock, }, +}; + +static struct tk_fast tk_fast_raw ____cacheline_aligned = { + .base[0] = { .clock = &dummy_clock, }, + .base[1] = { .clock = &dummy_clock, }, +}; + +/* 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++; + } + while (tk->tkr_raw.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_raw.shift)) { + tk->tkr_raw.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_raw.shift; + tk->raw_sec++; + } +} + +static inline struct timespec64 tk_xtime(const 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 != timespec64_to_ktime(tmp)); + 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); +} + +/* + * tk_clock_read - atomic clocksource read() helper + * + * This helper is necessary to use in the read paths because, while the + * seqlock ensures we don't return a bad value while structures are updated, + * it doesn't protect from potential crashes. There is the possibility that + * the tkr's clocksource may change between the read reference, and the + * clock reference passed to the read function. This can cause crashes if + * the wrong clocksource is passed to the wrong read function. + * This isn't necessary to use when holding the timekeeper_lock or doing + * a read of the fast-timekeeper tkrs (which is protected by its own locking + * and update logic). + */ +static inline u64 tk_clock_read(const struct tk_read_base *tkr) +{ + struct clocksource *clock = READ_ONCE(tkr->clock); + + return clock->read(clock); +} + +#ifdef CONFIG_DEBUG_TIMEKEEPING +#define WARNING_FREQ (HZ*300) /* 5 minute rate-limiting */ + +static void timekeeping_check_update(struct timekeeper *tk, u64 offset) +{ + + u64 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 '%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 (tk->underflow_seen) { + if (jiffies - tk->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"); + tk->last_warning = jiffies; + } + tk->underflow_seen = 0; + } + + if (tk->overflow_seen) { + if (jiffies - tk->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"); + tk->last_warning = jiffies; + } + tk->overflow_seen = 0; + } +} + +static inline u64 timekeeping_get_delta(const struct tk_read_base *tkr) +{ + struct timekeeper *tk = &tk_core.timekeeper; + u64 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 = tk_clock_read(tkr); + 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))) { + tk->underflow_seen = 1; + delta = 0; + } + + /* Cap delta value to the max_cycles values to avoid mult overflows */ + if (unlikely(delta > max)) { + tk->overflow_seen = 1; + delta = tkr->clock->max_cycles; + } + + return delta; +} +#else +static inline void timekeeping_check_update(struct timekeeper *tk, u64 offset) +{ +} +static inline u64 timekeeping_get_delta(const struct tk_read_base *tkr) +{ + u64 cycle_now, delta; + + /* read clocksource */ + cycle_now = tk_clock_read(tkr); + + /* 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) +{ + u64 interval; + u64 tmp, ntpinterval; + struct clocksource *old_clock; + + ++tk->cs_was_changed_seq; + old_clock = tk->tkr_mono.clock; + tk->tkr_mono.clock = clock; + tk->tkr_mono.mask = clock->mask; + tk->tkr_mono.cycle_last = tk_clock_read(&tk->tkr_mono); + + tk->tkr_raw.clock = clock; + 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 = (u64) tmp; + tk->cycle_interval = interval; + + /* Go back from cycles -> shifted ns */ + tk->xtime_interval = interval * clock->mult; + tk->xtime_remainder = ntpinterval - tk->xtime_interval; + tk->raw_interval = interval * clock->mult; + + /* 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; + tk->tkr_raw.xtime_nsec >>= -shift_change; + } else { + tk->tkr_mono.xtime_nsec <<= shift_change; + tk->tkr_raw.xtime_nsec <<= shift_change; + } + } + + 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; + tk->skip_second_overflow = 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 u64 timekeeping_delta_to_ns(const struct tk_read_base *tkr, u64 delta) +{ + u64 nsec; + + nsec = delta * tkr->mult + tkr->xtime_nsec; + nsec >>= tkr->shift; + + /* If arch requires, add in get_arch_timeoffset() */ + return nsec + arch_gettimeoffset(); +} + +static inline u64 timekeeping_get_ns(const struct tk_read_base *tkr) +{ + u64 delta; + + delta = timekeeping_get_delta(tkr); + return timekeeping_delta_to_ns(tkr, delta); +} + +static inline u64 timekeeping_cycles_to_ns(const struct tk_read_base *tkr, u64 cycles) +{ + u64 delta; + + /* calculate the delta since the last update_wall_time */ + delta = clocksource_delta(cycles, tkr->cycle_last, tkr->mask); + return timekeeping_delta_to_ns(tkr, delta); +} + +/** + * 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. + * + * Employ the latch technique; see @raw_write_seqcount_latch. + * + * 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(const 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_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_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); + +/** + * ktime_get_boot_fast_ns - NMI safe and fast access to boot clock. + * + * To keep it NMI safe since we're accessing from tracing, we're not using a + * separate timekeeper with updates to monotonic clock and boot offset + * protected with seqlocks. This has the following minor side effects: + * + * (1) Its possible that a timestamp be taken after the boot offset is updated + * but before the timekeeper is updated. If this happens, the new boot offset + * is added to the old timekeeping making the clock appear to update slightly + * earlier: + * CPU 0 CPU 1 + * timekeeping_inject_sleeptime64() + * __timekeeping_inject_sleeptime(tk, delta); + * timestamp(); + * timekeeping_update(tk, TK_CLEAR_NTP...); + * + * (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. + */ +u64 notrace ktime_get_boot_fast_ns(void) +{ + struct timekeeper *tk = &tk_core.timekeeper; + + return (ktime_get_mono_fast_ns() + ktime_to_ns(tk->offs_boot)); +} +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_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_real); + + now += timekeeping_delta_to_ns(tkr, + clocksource_delta( + tk_clock_read(tkr), + tkr->cycle_last, + tkr->mask)); + } while (read_seqcount_retry(&tkf->seq, seq)); + + return now; +} + +/** + * ktime_get_real_fast_ns: - NMI safe and fast access to clock realtime. + */ +u64 ktime_get_real_fast_ns(void) +{ + return __ktime_get_real_fast_ns(&tk_fast_mono); +} +EXPORT_SYMBOL_GPL(ktime_get_real_fast_ns); + +/** + * 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(const struct timekeeper *tk) +{ + static struct tk_read_base tkr_dummy; + const struct tk_read_base *tkr = &tk->tkr_mono; + + memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy)); + cycles_at_suspend = tk_clock_read(tkr); + tkr_dummy.clock = &dummy_clock; + tkr_dummy.base_real = tkr->base + tk->offs_real; + update_fast_timekeeper(&tkr_dummy, &tk_fast_mono); + + tkr = &tk->tkr_raw; + memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy)); + tkr_dummy.clock = &dummy_clock; + update_fast_timekeeper(&tkr_dummy, &tk_fast_raw); +} + +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); + +/* + * tk_update_leap_state - helper to update the next_leap_ktime + */ +static inline void tk_update_leap_state(struct timekeeper *tk) +{ + tk->next_leap_ktime = ntp_get_next_leap(); + if (tk->next_leap_ktime != KTIME_MAX) + /* Convert to monotonic time */ + tk->next_leap_ktime = ktime_sub(tk->next_leap_ktime, tk->offs_real); +} + +/* + * 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); + + /* + * 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; + + /* Update the monotonic raw base */ + tk->tkr_raw.base = ns_to_ktime(tk->raw_sec * NSEC_PER_SEC); +} + +/* 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_leap_state(tk); + tk_update_ktime_data(tk); + + update_vsyscall(tk); + update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET); + + tk->tkr_mono.base_real = tk->tkr_mono.base + tk->offs_real; + update_fast_timekeeper(&tk->tkr_mono, &tk_fast_mono); + update_fast_timekeeper(&tk->tkr_raw, &tk_fast_raw); + + if (action & TK_CLOCK_WAS_SET) + tk->clock_was_set_seq++; + /* + * The mirroring of the data to the shadow-timekeeper needs + * to happen last here to ensure we don't over-write the + * timekeeper structure on the next update with stale data + */ + if (action & TK_MIRROR) + memcpy(&shadow_timekeeper, &tk_core.timekeeper, + sizeof(tk_core.timekeeper)); +} + +/** + * 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) +{ + u64 cycle_now, delta; + + cycle_now = tk_clock_read(&tk->tkr_mono); + 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->tkr_raw.xtime_nsec += delta * tk->tkr_raw.mult; + + /* If arch requires, add in get_arch_timeoffset() */ + tk->tkr_raw.xtime_nsec += (u64)arch_gettimeoffset() << tk->tkr_raw.shift; + + tk_normalize_xtime(tk); +} + +/** + * ktime_get_real_ts64 - Returns the time of day in a timespec64. + * @ts: pointer to the timespec to be set + * + * Returns the time of day in a timespec64 (WARN if suspended). + */ +void ktime_get_real_ts64(struct timespec64 *ts) +{ + struct timekeeper *tk = &tk_core.timekeeper; + unsigned long seq; + u64 nsecs; + + WARN_ON(timekeeping_suspended); + + 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); +} +EXPORT_SYMBOL(ktime_get_real_ts64); + +ktime_t ktime_get(void) +{ + struct timekeeper *tk = &tk_core.timekeeper; + unsigned int seq; + ktime_t base; + u64 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); + +u32 ktime_get_resolution_ns(void) +{ + struct timekeeper *tk = &tk_core.timekeeper; + unsigned int seq; + u32 nsecs; + + WARN_ON(timekeeping_suspended); + + do { + seq = read_seqcount_begin(&tk_core.seq); + nsecs = tk->tkr_mono.mult >> tk->tkr_mono.shift; + } while (read_seqcount_retry(&tk_core.seq, seq)); + + return nsecs; +} +EXPORT_SYMBOL_GPL(ktime_get_resolution_ns); + +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]; + u64 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_t ktime_get_coarse_with_offset(enum tk_offsets offs) +{ + struct timekeeper *tk = &tk_core.timekeeper; + unsigned int seq; + ktime_t base, *offset = offsets[offs]; + u64 nsecs; + + WARN_ON(timekeeping_suspended); + + do { + seq = read_seqcount_begin(&tk_core.seq); + base = ktime_add(tk->tkr_mono.base, *offset); + nsecs = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift; + + } while (read_seqcount_retry(&tk_core.seq, seq)); + + return ktime_add_ns(base, nsecs); +} +EXPORT_SYMBOL_GPL(ktime_get_coarse_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; + u64 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; + unsigned int seq; + u64 nsec; + + 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); + +/** + * __ktime_get_real_seconds - The same as ktime_get_real_seconds + * but without the sequence counter protect. This internal function + * is called just when timekeeping lock is already held. + */ +time64_t __ktime_get_real_seconds(void) +{ + struct timekeeper *tk = &tk_core.timekeeper; + + return tk->xtime_sec; +} + +/** + * ktime_get_snapshot - snapshots the realtime/monotonic raw clocks with counter + * @systime_snapshot: pointer to struct receiving the system time snapshot + */ +void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot) +{ + struct timekeeper *tk = &tk_core.timekeeper; + unsigned long seq; + ktime_t base_raw; + ktime_t base_real; + u64 nsec_raw; + u64 nsec_real; + u64 now; + + WARN_ON_ONCE(timekeeping_suspended); + + do { + seq = read_seqcount_begin(&tk_core.seq); + now = tk_clock_read(&tk->tkr_mono); + systime_snapshot->cs_was_changed_seq = tk->cs_was_changed_seq; + systime_snapshot->clock_was_set_seq = tk->clock_was_set_seq; + base_real = ktime_add(tk->tkr_mono.base, + tk_core.timekeeper.offs_real); + base_raw = tk->tkr_raw.base; + nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono, now); + nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw, now); + } while (read_seqcount_retry(&tk_core.seq, seq)); + + systime_snapshot->cycles = now; + systime_snapshot->real = ktime_add_ns(base_real, nsec_real); + systime_snapshot->raw = ktime_add_ns(base_raw, nsec_raw); +} +EXPORT_SYMBOL_GPL(ktime_get_snapshot); + +/* Scale base by mult/div checking for overflow */ +static int scale64_check_overflow(u64 mult, u64 div, u64 *base) +{ + u64 tmp, rem; + + tmp = div64_u64_rem(*base, div, &rem); + + if (((int)sizeof(u64)*8 - fls64(mult) < fls64(tmp)) || + ((int)sizeof(u64)*8 - fls64(mult) < fls64(rem))) + return -EOVERFLOW; + tmp *= mult; + + rem = div64_u64(rem * mult, div); + *base = tmp + rem; + return 0; +} + +/** + * adjust_historical_crosststamp - adjust crosstimestamp previous to current interval + * @history: Snapshot representing start of history + * @partial_history_cycles: Cycle offset into history (fractional part) + * @total_history_cycles: Total history length in cycles + * @discontinuity: True indicates clock was set on history period + * @ts: Cross timestamp that should be adjusted using + * partial/total ratio + * + * Helper function used by get_device_system_crosststamp() to correct the + * crosstimestamp corresponding to the start of the current interval to the + * system counter value (timestamp point) provided by the driver. The + * total_history_* quantities are the total history starting at the provided + * reference point and ending at the start of the current interval. The cycle + * count between the driver timestamp point and the start of the current + * interval is partial_history_cycles. + */ +static int adjust_historical_crosststamp(struct system_time_snapshot *history, + u64 partial_history_cycles, + u64 total_history_cycles, + bool discontinuity, + struct system_device_crosststamp *ts) +{ + struct timekeeper *tk = &tk_core.timekeeper; + u64 corr_raw, corr_real; + bool interp_forward; + int ret; + + if (total_history_cycles == 0 || partial_history_cycles == 0) + return 0; + + /* Interpolate shortest distance from beginning or end of history */ + interp_forward = partial_history_cycles > total_history_cycles / 2; + partial_history_cycles = interp_forward ? + total_history_cycles - partial_history_cycles : + partial_history_cycles; + + /* + * Scale the monotonic raw time delta by: + * partial_history_cycles / total_history_cycles + */ + corr_raw = (u64)ktime_to_ns( + ktime_sub(ts->sys_monoraw, history->raw)); + ret = scale64_check_overflow(partial_history_cycles, + total_history_cycles, &corr_raw); + if (ret) + return ret; + + /* + * If there is a discontinuity in the history, scale monotonic raw + * correction by: + * mult(real)/mult(raw) yielding the realtime correction + * Otherwise, calculate the realtime correction similar to monotonic + * raw calculation + */ + if (discontinuity) { + corr_real = mul_u64_u32_div + (corr_raw, tk->tkr_mono.mult, tk->tkr_raw.mult); + } else { + corr_real = (u64)ktime_to_ns( + ktime_sub(ts->sys_realtime, history->real)); + ret = scale64_check_overflow(partial_history_cycles, + total_history_cycles, &corr_real); + if (ret) + return ret; + } + + /* Fixup monotonic raw and real time time values */ + if (interp_forward) { + ts->sys_monoraw = ktime_add_ns(history->raw, corr_raw); + ts->sys_realtime = ktime_add_ns(history->real, corr_real); + } else { + ts->sys_monoraw = ktime_sub_ns(ts->sys_monoraw, corr_raw); + ts->sys_realtime = ktime_sub_ns(ts->sys_realtime, corr_real); + } + + return 0; +} + +/* + * cycle_between - true if test occurs chronologically between before and after + */ +static bool cycle_between(u64 before, u64 test, u64 after) +{ + if (test > before && test < after) + return true; + if (test < before && before > after) + return true; + return false; +} + +/** + * get_device_system_crosststamp - Synchronously capture system/device timestamp + * @get_time_fn: Callback to get simultaneous device time and + * system counter from the device driver + * @ctx: Context passed to get_time_fn() + * @history_begin: Historical reference point used to interpolate system + * time when counter provided by the driver is before the current interval + * @xtstamp: Receives simultaneously captured system and device time + * + * Reads a timestamp from a device and correlates it to system time + */ +int get_device_system_crosststamp(int (*get_time_fn) + (ktime_t *device_time, + struct system_counterval_t *sys_counterval, + void *ctx), + void *ctx, + struct system_time_snapshot *history_begin, + struct system_device_crosststamp *xtstamp) +{ + struct system_counterval_t system_counterval; + struct timekeeper *tk = &tk_core.timekeeper; + u64 cycles, now, interval_start; + unsigned int clock_was_set_seq = 0; + ktime_t base_real, base_raw; + u64 nsec_real, nsec_raw; + u8 cs_was_changed_seq; + unsigned long seq; + bool do_interp; + int ret; + + do { + seq = read_seqcount_begin(&tk_core.seq); + /* + * Try to synchronously capture device time and a system + * counter value calling back into the device driver + */ + ret = get_time_fn(&xtstamp->device, &system_counterval, ctx); + if (ret) + return ret; + + /* + * Verify that the clocksource associated with the captured + * system counter value is the same as the currently installed + * timekeeper clocksource + */ + if (tk->tkr_mono.clock != system_counterval.cs) + return -ENODEV; + cycles = system_counterval.cycles; + + /* + * Check whether the system counter value provided by the + * device driver is on the current timekeeping interval. + */ + now = tk_clock_read(&tk->tkr_mono); + interval_start = tk->tkr_mono.cycle_last; + if (!cycle_between(interval_start, cycles, now)) { + clock_was_set_seq = tk->clock_was_set_seq; + cs_was_changed_seq = tk->cs_was_changed_seq; + cycles = interval_start; + do_interp = true; + } else { + do_interp = false; + } + + base_real = ktime_add(tk->tkr_mono.base, + tk_core.timekeeper.offs_real); + base_raw = tk->tkr_raw.base; + + nsec_real = timekeeping_cycles_to_ns(&tk->tkr_mono, + system_counterval.cycles); + nsec_raw = timekeeping_cycles_to_ns(&tk->tkr_raw, + system_counterval.cycles); + } while (read_seqcount_retry(&tk_core.seq, seq)); + + xtstamp->sys_realtime = ktime_add_ns(base_real, nsec_real); + xtstamp->sys_monoraw = ktime_add_ns(base_raw, nsec_raw); + + /* + * Interpolate if necessary, adjusting back from the start of the + * current interval + */ + if (do_interp) { + u64 partial_history_cycles, total_history_cycles; + bool discontinuity; + + /* + * Check that the counter value occurs after the provided + * history reference and that the history doesn't cross a + * clocksource change + */ + if (!history_begin || + !cycle_between(history_begin->cycles, + system_counterval.cycles, cycles) || + history_begin->cs_was_changed_seq != cs_was_changed_seq) + return -EINVAL; + partial_history_cycles = cycles - system_counterval.cycles; + total_history_cycles = cycles - history_begin->cycles; + discontinuity = + history_begin->clock_was_set_seq != clock_was_set_seq; + + ret = adjust_historical_crosststamp(history_begin, + partial_history_cycles, + total_history_cycles, + discontinuity, xtstamp); + if (ret) + return ret; + } + + return 0; +} +EXPORT_SYMBOL_GPL(get_device_system_crosststamp); + +/** + * 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; + int ret = 0; + + if (!timespec64_valid_settod(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 = timespec64_sub(*ts, xt); + + if (timespec64_compare(&tk->wall_to_monotonic, &ts_delta) > 0) { + ret = -EINVAL; + goto out; + } + + tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts_delta)); + + tk_set_xtime(tk, ts); +out: + 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(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. + */ +static int timekeeping_inject_offset(const struct timespec64 *ts) +{ + struct timekeeper *tk = &tk_core.timekeeper; + unsigned long flags; + struct timespec64 tmp; + int ret = 0; + + if (ts->tv_nsec < 0 || ts->tv_nsec >= NSEC_PER_SEC) + return -EINVAL; + + 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), *ts); + if (timespec64_compare(&tk->wall_to_monotonic, ts) > 0 || + !timespec64_valid_settod(&tmp)) { + ret = -EINVAL; + goto error; + } + + tk_xtime_add(tk, ts); + tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, *ts)); + +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; +} + +/* + * Indicates if there is an offset between the system clock and the hardware + * clock/persistent clock/rtc. + */ +int persistent_clock_is_local; + +/* + * Adjust the time obtained from the CMOS to be UTC time instead of + * local time. + * + * This is ugly, but preferable to the alternatives. Otherwise we + * would either need to write a program to do it in /etc/rc (and risk + * confusion if the program gets run more than once; it would also be + * hard to make the program warp the clock precisely n hours) or + * compile in the timezone information into the kernel. Bad, bad.... + * + * - TYT, 1992-01-01 + * + * The best thing to do is to keep the CMOS clock in universal time (UTC) + * as real UNIX machines always do it. This avoids all headaches about + * daylight saving times and warping kernel clocks. + */ +void timekeeping_warp_clock(void) +{ + if (sys_tz.tz_minuteswest != 0) { + struct timespec64 adjust; + + persistent_clock_is_local = 1; + adjust.tv_sec = sys_tz.tz_minuteswest * 60; + adjust.tv_nsec = 0; + timekeeping_inject_offset(&adjust); + } +} + +/** + * __timekeeping_set_tai_offset - Sets the TAI offset from UTC and monotonic + * + */ +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)); +} + +/** + * 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; +} + +/** + * ktime_get_raw_ts64 - 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 ktime_get_raw_ts64(struct timespec64 *ts) +{ + struct timekeeper *tk = &tk_core.timekeeper; + unsigned long seq; + u64 nsecs; + + do { + seq = read_seqcount_begin(&tk_core.seq); + ts->tv_sec = tk->raw_sec; + nsecs = timekeeping_get_ns(&tk->tkr_raw); + + } while (read_seqcount_retry(&tk_core.seq, seq)); + + ts->tv_nsec = 0; + timespec64_add_ns(ts, nsecs); +} +EXPORT_SYMBOL(ktime_get_raw_ts64); + + +/** + * 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_persistent_wall_and_boot_offset - Read persistent clock, and also offset + * 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 + * 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 + * boot time. + */ +void __weak __init +read_persistent_wall_and_boot_offset(struct timespec64 *wall_time, + struct timespec64 *boot_offset) +{ + read_persistent_clock64(wall_time); + *boot_offset = ns_to_timespec64(local_clock()); +} + +/* + * Flag reflecting whether timekeeping_resume() has injected sleeptime. + * + * The flag starts of false and is only set when a suspend reaches + * timekeeping_suspend(), timekeeping_resume() sets it to false when the + * timekeeper clocksource is not stopping across suspend and has been + * used to update sleep time. If the timekeeper clocksource has stopped + * then the flag stays true and is used by the RTC resume code to decide + * whether sleeptime must be injected and if so the flag gets false then. + * + * If a suspend fails before reaching timekeeping_resume() then the flag + * stays false and prevents erroneous sleeptime injection. + */ +static bool suspend_timing_needed; + +/* 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 timespec64 wall_time, boot_offset, wall_to_mono; + struct timekeeper *tk = &tk_core.timekeeper; + struct clocksource *clock; + unsigned long flags; + + read_persistent_wall_and_boot_offset(&wall_time, &boot_offset); + if (timespec64_valid_settod(&wall_time) && + timespec64_to_ns(&wall_time) > 0) { + persistent_clock_exists = true; + } else if (timespec64_to_ns(&wall_time) != 0) { + pr_warn("Persistent clock returned invalid value"); + wall_time = (struct timespec64){0}; + } + + if (timespec64_compare(&wall_time, &boot_offset) < 0) + boot_offset = (struct timespec64){0}; + + /* + * We want set wall_to_mono, so the following is true: + * wall time + wall_to_mono = boot time + */ + wall_to_mono = timespec64_sub(boot_offset, wall_time); + + 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, &wall_time); + tk->raw_sec = 0; + + tk_set_wall_to_mono(tk, wall_to_mono); + + timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET); + + 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, + const 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 !suspend_timing_needed; +} + +/** + * 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(const 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); + + suspend_timing_needed = false; + + 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; + u64 cycle_now, nsec; + bool inject_sleeptime = 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_clock_read(&tk->tkr_mono); + nsec = clocksource_stop_suspend_timing(clock, cycle_now); + if (nsec > 0) { + ts_delta = ns_to_timespec64(nsec); + inject_sleeptime = true; + } else if (timespec64_compare(&ts_new, &timekeeping_suspend_time) > 0) { + ts_delta = timespec64_sub(ts_new, timekeeping_suspend_time); + inject_sleeptime = true; + } + + if (inject_sleeptime) { + suspend_timing_needed = false; + __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; + struct clocksource *curr_clock; + u64 cycle_now; + + 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; + + suspend_timing_needed = true; + + raw_spin_lock_irqsave(&timekeeper_lock, flags); + write_seqcount_begin(&tk_core.seq); + timekeeping_forward_now(tk); + timekeeping_suspended = 1; + + /* + * Since we've called forward_now, cycle_last stores the value + * just read from the current clocksource. Save this to potentially + * use in suspend timing. + */ + curr_clock = tk->tkr_mono.clock; + cycle_now = tk->tkr_mono.cycle_last; + clocksource_start_suspend_timing(curr_clock, cycle_now); + + 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, + s32 mult_adj) +{ + s64 interval = tk->cycle_interval; + + if (mult_adj == 0) { + return; + } else if (mult_adj == -1) { + interval = -interval; + offset = -offset; + } else if (mult_adj != 1) { + interval *= mult_adj; + offset *= mult_adj; + } + + /* + * 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 + */ + 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; +} + +/* + * 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) +{ + u32 mult; + + /* + * Determine the multiplier from the current NTP tick length. + * Avoid expensive division when the tick length doesn't change. + */ + if (likely(tk->ntp_tick == ntp_tick_length())) { + mult = tk->tkr_mono.mult - tk->ntp_err_mult; + } else { + tk->ntp_tick = ntp_tick_length(); + mult = div64_u64((tk->ntp_tick >> tk->ntp_error_shift) - + tk->xtime_remainder, tk->cycle_interval); + } + + /* + * If the clock is behind the NTP time, increase the multiplier by 1 + * to catch up with it. If it's ahead and there was a remainder in the + * tick division, the clock will slow down. Otherwise it will stay + * ahead until the tick length changes to a non-divisible value. + */ + tk->ntp_err_mult = tk->ntp_error > 0 ? 1 : 0; + mult += tk->ntp_err_mult; + + timekeeping_apply_adjustment(tk, offset, mult - tk->tkr_mono.mult); + + 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 have already accumulated the second and the NTP + * subsystem has been notified via second_overflow(), we need to skip + * the next update. + */ + if (unlikely((s64)tk->tkr_mono.xtime_nsec < 0)) { + tk->tkr_mono.xtime_nsec += (u64)NSEC_PER_SEC << + tk->tkr_mono.shift; + tk->xtime_sec--; + tk->skip_second_overflow = 1; + } +} + +/** + * 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) +{ + 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++; + + /* + * Skip NTP update if this second was accumulated before, + * i.e. xtime_nsec underflowed in timekeeping_adjust() + */ + if (unlikely(tk->skip_second_overflow)) { + tk->skip_second_overflow = 0; + continue; + } + + /* 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 u64 logarithmic_accumulation(struct timekeeper *tk, u64 offset, + u32 shift, unsigned int *clock_set) +{ + u64 interval = tk->cycle_interval << shift; + u64 snsec_per_sec; + + /* If the offset is smaller than 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 */ + tk->tkr_raw.xtime_nsec += tk->raw_interval << shift; + snsec_per_sec = (u64)NSEC_PER_SEC << tk->tkr_raw.shift; + while (tk->tkr_raw.xtime_nsec >= snsec_per_sec) { + tk->tkr_raw.xtime_nsec -= snsec_per_sec; + tk->raw_sec++; + } + + /* 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; +} + +/* + * timekeeping_advance - Updates the timekeeper to the current time and + * current NTP tick length + */ +static void timekeeping_advance(enum timekeeping_adv_mode mode) +{ + struct timekeeper *real_tk = &tk_core.timekeeper; + struct timekeeper *tk = &shadow_timekeeper; + u64 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; + + if (mode != TK_ADV_TICK) + goto out; +#else + offset = clocksource_delta(tk_clock_read(&tk->tkr_mono), + tk->tkr_mono.cycle_last, tk->tkr_mono.mask); + + /* Check if there's really nothing to do */ + if (offset < real_tk->cycle_interval && mode == TK_ADV_TICK) + goto out; +#endif + + /* Do some additional sanity checking */ + timekeeping_check_update(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--; + } + + /* Adjust the multiplier to correct NTP error */ + timekeeping_adjust(tk, offset); + + /* + * 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. + */ + timekeeping_update(tk, clock_set); + memcpy(real_tk, tk, sizeof(*tk)); + /* The memcpy must come last. Do not put anything here! */ + 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(); +} + +/** + * update_wall_time - Uses the current clocksource to increment the wall time + * + */ +void update_wall_time(void) +{ + timekeeping_advance(TK_ADV_TICK); +} + +/** + * 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); + +void ktime_get_coarse_real_ts64(struct timespec64 *ts) +{ + struct timekeeper *tk = &tk_core.timekeeper; + unsigned long seq; + + do { + seq = read_seqcount_begin(&tk_core.seq); + + *ts = tk_xtime(tk); + } while (read_seqcount_retry(&tk_core.seq, seq)); +} +EXPORT_SYMBOL(ktime_get_coarse_real_ts64); + +void ktime_get_coarse_ts64(struct timespec64 *ts) +{ + 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(ts, now.tv_sec + mono.tv_sec, + now.tv_nsec + mono.tv_nsec); +} +EXPORT_SYMBOL(ktime_get_coarse_ts64); + +/* + * Must hold jiffies_lock + */ +void do_timer(unsigned long ticks) +{ + jiffies_64 += ticks; + calc_global_load(ticks); +} + +/** + * ktime_get_update_offsets_now - hrtimer helper + * @cwsseq: pointer to check and store the clock was set sequence number + * @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 if the + * sequence number in @cwsseq and timekeeper.clock_was_set_seq are + * different. + * + * Called from hrtimer_interrupt() or retrigger_next_event() + */ +ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq, 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); + base = ktime_add_ns(base, nsecs); + + if (*cwsseq != tk->clock_was_set_seq) { + *cwsseq = tk->clock_was_set_seq; + *offs_real = tk->offs_real; + *offs_boot = tk->offs_boot; + *offs_tai = tk->offs_tai; + } + + /* Handle leapsecond insertion adjustments */ + if (unlikely(base >= tk->next_leap_ktime)) + *offs_real = ktime_sub(tk->offs_real, ktime_set(1, 0)); + + } while (read_seqcount_retry(&tk_core.seq, seq)); + + return base; +} + +/** + * timekeeping_validate_timex - Ensures the timex is ok for use in do_adjtimex + */ +static int timekeeping_validate_timex(const struct timex *txc) +{ + if (txc->modes & ADJ_ADJTIME) { + /* singleshot must not be used with any other mode bits */ + if (!(txc->modes & ADJ_OFFSET_SINGLESHOT)) + return -EINVAL; + if (!(txc->modes & ADJ_OFFSET_READONLY) && + !capable(CAP_SYS_TIME)) + return -EPERM; + } else { + /* In order to modify anything, you gotta be super-user! */ + if (txc->modes && !capable(CAP_SYS_TIME)) + return -EPERM; + /* + * if the quartz is off by more than 10% then + * something is VERY wrong! + */ + if (txc->modes & ADJ_TICK && + (txc->tick < 900000/USER_HZ || + txc->tick > 1100000/USER_HZ)) + return -EINVAL; + } + + if (txc->modes & ADJ_SETOFFSET) { + /* In order to inject time, you gotta be super-user! */ + if (!capable(CAP_SYS_TIME)) + return -EPERM; + + /* + * Validate if a timespec/timeval used to inject a time + * offset is valid. Offsets can be postive or negative, so + * we don't check tv_sec. The value of the timeval/timespec + * is the sum of its fields,but *NOTE*: + * The field tv_usec/tv_nsec must always be non-negative and + * we can't have more nanoseconds/microseconds than a second. + */ + if (txc->time.tv_usec < 0) + return -EINVAL; + + if (txc->modes & ADJ_NANO) { + if (txc->time.tv_usec >= NSEC_PER_SEC) + return -EINVAL; + } else { + if (txc->time.tv_usec >= USEC_PER_SEC) + return -EINVAL; + } + } + + /* + * Check for potential multiplication overflows that can + * only happen on 64-bit systems: + */ + if ((txc->modes & ADJ_FREQUENCY) && (BITS_PER_LONG == 64)) { + if (LLONG_MIN / PPM_SCALE > txc->freq) + return -EINVAL; + if (LLONG_MAX / PPM_SCALE < txc->freq) + return -EINVAL; + } + + return 0; +} + +/** + * random_get_entropy_fallback - Returns the raw clock source value, + * used by random.c for platforms with no valid random_get_entropy(). + */ +unsigned long random_get_entropy_fallback(void) +{ + struct tk_read_base *tkr = &tk_core.timekeeper.tkr_mono; + struct clocksource *clock = READ_ONCE(tkr->clock); + + if (unlikely(timekeeping_suspended || !clock)) + return 0; + return clock->read(clock); +} +EXPORT_SYMBOL_GPL(random_get_entropy_fallback); + +/** + * 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 = timekeeping_validate_timex(txc); + if (ret) + return ret; + + if (txc->modes & ADJ_SETOFFSET) { + struct timespec64 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; + } + + ktime_get_real_ts64(&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); + } + tk_update_leap_state(tk); + + write_seqcount_end(&tk_core.seq); + raw_spin_unlock_irqrestore(&timekeeper_lock, flags); + + /* Update the multiplier immediately if frequency was set directly */ + if (txc->modes & (ADJ_FREQUENCY | ADJ_TICK)) + timekeeping_advance(TK_ADV_FREQ); + + 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 timespec64 *phase_ts, const struct timespec64 *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 /* CONFIG_NTP_PPS */ + +/** + * 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(); +} |