| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * Kernel timekeeping code and accessor functions. Based on code from |
| * timer.c, moved in commit 8524070b7982. |
| */ |
| #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 <linux/audit.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 |
| }; |
| |
| DEFINE_RAW_SPINLOCK(timekeeper_lock); |
| |
| /* |
| * The most important data for readout fits into a single 64 byte |
| * cache line. |
| */ |
| static struct { |
| seqcount_raw_spinlock_t seq; |
| struct timekeeper timekeeper; |
| } tk_core ____cacheline_aligned = { |
| .seq = SEQCNT_RAW_SPINLOCK_ZERO(tk_core.seq, &timekeeper_lock), |
| }; |
| |
| static struct timekeeper shadow_timekeeper; |
| |
| /* flag for if timekeeping is suspended */ |
| int __read_mostly timekeeping_suspended; |
| |
| /** |
| * 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_latch_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) |
| { |
| if (timekeeping_suspended) |
| return cycles_at_suspend; |
| return local_clock(); |
| } |
| |
| static struct clocksource dummy_clock = { |
| .read = dummy_clock_read, |
| }; |
| |
| /* |
| * Boot time initialization which allows local_clock() to be utilized |
| * during early boot when clocksources are not available. local_clock() |
| * returns nanoseconds already so no conversion is required, hence mult=1 |
| * and shift=0. When the first proper clocksource is installed then |
| * the fast time keepers are updated with the correct values. |
| */ |
| #define FAST_TK_INIT \ |
| { \ |
| .clock = &dummy_clock, \ |
| .mask = CLOCKSOURCE_MASK(64), \ |
| .mult = 1, \ |
| .shift = 0, \ |
| } |
| |
| static struct tk_fast tk_fast_mono ____cacheline_aligned = { |
| .seq = SEQCNT_LATCH_ZERO(tk_fast_mono.seq), |
| .base[0] = FAST_TK_INIT, |
| .base[1] = FAST_TK_INIT, |
| }; |
| |
| static struct tk_fast tk_fast_raw ____cacheline_aligned = { |
| .seq = SEQCNT_LATCH_ZERO(tk_fast_raw.seq), |
| .base[0] = FAST_TK_INIT, |
| .base[1] = FAST_TK_INIT, |
| }; |
| |
| 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); |
| /* |
| * Timespec representation for VDSO update to avoid 64bit division |
| * on every update. |
| */ |
| tk->monotonic_to_boot = ktime_to_timespec64(tk->offs_boot); |
| } |
| |
| /* |
| * tk_clock_read - atomic clocksource read() helper |
| * |
| * This helper is necessary to use in the read paths because, while the |
| * seqcount 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 seqcount, 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 seqcount 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. */ |
| |
| 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; |
| |
| return nsec; |
| } |
| |
| 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 |
| * @tkf: Pointer to NMI safe timekeeper |
| * |
| * 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)); |
| } |
| |
| static __always_inline u64 fast_tk_get_delta_ns(struct tk_read_base *tkr) |
| { |
| u64 delta, cycles = tk_clock_read(tkr); |
| |
| delta = clocksource_delta(cycles, tkr->cycle_last, tkr->mask); |
| return timekeeping_delta_to_ns(tkr, delta); |
| } |
| |
| 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 += fast_tk_get_delta_ns(tkr); |
| } while (read_seqcount_latch_retry(&tkf->seq, seq)); |
| |
| return now; |
| } |
| |
| /** |
| * 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 to observe that, the only way |
| * for a CPU local observation is when an NMI hits in the middle of |
| * the update. Timestamps taken from that NMI context might be ahead |
| * of the following timestamps. Callers need to be aware of that and |
| * deal with it. |
| */ |
| u64 notrace ktime_get_mono_fast_ns(void) |
| { |
| return __ktime_get_fast_ns(&tk_fast_mono); |
| } |
| EXPORT_SYMBOL_GPL(ktime_get_mono_fast_ns); |
| |
| /** |
| * ktime_get_raw_fast_ns - Fast NMI safe access to clock monotonic raw |
| * |
| * Contrary to ktime_get_mono_fast_ns() this is always correct because the |
| * conversion factor is not affected by NTP/PTP correction. |
| */ |
| u64 notrace 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 seqcounts. 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. |
| * |
| * The caveats vs. timestamp ordering as documented for ktime_get_fast_ns() |
| * apply as well. |
| */ |
| u64 notrace ktime_get_boot_fast_ns(void) |
| { |
| struct timekeeper *tk = &tk_core.timekeeper; |
| |
| return (ktime_get_mono_fast_ns() + ktime_to_ns(data_race(tk->offs_boot))); |
| } |
| EXPORT_SYMBOL_GPL(ktime_get_boot_fast_ns); |
| |
| /** |
| * ktime_get_tai_fast_ns - NMI safe and fast access to tai clock. |
| * |
| * The same limitations as described for ktime_get_boot_fast_ns() apply. The |
| * mono time and the TAI offset are not read atomically which may yield wrong |
| * readouts. However, an update of the TAI offset is an rare event e.g., caused |
| * by settime or adjtimex with an offset. The user of this function has to deal |
| * with the possibility of wrong timestamps in post processing. |
| */ |
| u64 notrace ktime_get_tai_fast_ns(void) |
| { |
| struct timekeeper *tk = &tk_core.timekeeper; |
| |
| return (ktime_get_mono_fast_ns() + ktime_to_ns(data_race(tk->offs_tai))); |
| } |
| EXPORT_SYMBOL_GPL(ktime_get_tai_fast_ns); |
| |
| static __always_inline u64 __ktime_get_real_fast(struct tk_fast *tkf, u64 *mono) |
| { |
| struct tk_read_base *tkr; |
| u64 basem, baser, delta; |
| unsigned int seq; |
| |
| do { |
| seq = raw_read_seqcount_latch(&tkf->seq); |
| tkr = tkf->base + (seq & 0x01); |
| basem = ktime_to_ns(tkr->base); |
| baser = ktime_to_ns(tkr->base_real); |
| delta = fast_tk_get_delta_ns(tkr); |
| } while (read_seqcount_latch_retry(&tkf->seq, seq)); |
| |
| if (mono) |
| *mono = basem + delta; |
| return baser + delta; |
| } |
| |
| /** |
| * ktime_get_real_fast_ns: - NMI safe and fast access to clock realtime. |
| * |
| * See ktime_get_fast_ns() for documentation of the time stamp ordering. |
| */ |
| u64 ktime_get_real_fast_ns(void) |
| { |
| return __ktime_get_real_fast(&tk_fast_mono, NULL); |
| } |
| EXPORT_SYMBOL_GPL(ktime_get_real_fast_ns); |
| |
| /** |
| * ktime_get_fast_timestamps: - NMI safe timestamps |
| * @snapshot: Pointer to timestamp storage |
| * |
| * Stores clock monotonic, boottime and realtime timestamps. |
| * |
| * Boot time is a racy access on 32bit systems if the sleep time injection |
| * happens late during resume and not in timekeeping_resume(). That could |
| * be avoided by expanding struct tk_read_base with boot offset for 32bit |
| * and adding more overhead to the update. As this is a hard to observe |
| * once per resume event which can be filtered with reasonable effort using |
| * the accurate mono/real timestamps, it's probably not worth the trouble. |
| * |
| * Aside of that it might be possible on 32 and 64 bit to observe the |
| * following when the sleep time injection happens late: |
| * |
| * CPU 0 CPU 1 |
| * timekeeping_resume() |
| * ktime_get_fast_timestamps() |
| * mono, real = __ktime_get_real_fast() |
| * inject_sleep_time() |
| * update boot offset |
| * boot = mono + bootoffset; |
| * |
| * That means that boot time already has the sleep time adjustment, but |
| * real time does not. On the next readout both are in sync again. |
| * |
| * Preventing this for 64bit is not really feasible without destroying the |
| * careful cache layout of the timekeeper because the sequence count and |
| * struct tk_read_base would then need two cache lines instead of one. |
| * |
| * Access to the time keeper clock source is disabled across the innermost |
| * steps of suspend/resume. The accessors still work, but the timestamps |
| * are frozen until time keeping is resumed which happens very early. |
| * |
| * For regular suspend/resume there is no observable difference vs. sched |
| * clock, but it might affect some of the nasty low level debug printks. |
| * |
| * OTOH, access to sched clock is not guaranteed across suspend/resume on |
| * all systems either so it depends on the hardware in use. |
| * |
| * If that turns out to be a real problem then this could be mitigated by |
| * using sched clock in a similar way as during early boot. But it's not as |
| * trivial as on early boot because it needs some careful protection |
| * against the clock monotonic timestamp jumping backwards on resume. |
| */ |
| void ktime_get_fast_timestamps(struct ktime_timestamps *snapshot) |
| { |
| struct timekeeper *tk = &tk_core.timekeeper; |
| |
| snapshot->real = __ktime_get_real_fast(&tk_fast_mono, &snapshot->mono); |
| snapshot->boot = snapshot->mono + ktime_to_ns(data_race(tk->offs_boot)); |
| } |
| |
| /** |
| * 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 |
| * @nb: Pointer to the notifier block to register |
| */ |
| 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 |
| * @nb: Pointer to the notifier block to unregister |
| */ |
| 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 |
| * @tk: Pointer to the timekeeper to update |
| * |
| * Forward the current clock to update its state since the last call to |
| * update_wall_time(). This is useful before significant clock changes, |
| * 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; |
| tk->tkr_raw.xtime_nsec += delta * tk->tkr_raw.mult; |
| |
| 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 int 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 monotonic 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 int 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. |
| * |
| * 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. |
| */ |
| noinstr 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 int 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_id = tk->tkr_mono.clock->id; |
| 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 int 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(CLOCK_SET_WALL); |
| |
| if (!ret) |
| audit_tk_injoffset(ts_delta); |
| |
| return ret; |
| } |
| EXPORT_SYMBOL(do_settimeofday64); |
| |
| /** |
| * timekeeping_inject_offset - Adds or subtracts from the current time. |
| * @ts: 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(CLOCK_SET_WALL); |
| |
| 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 = NULL; |
| unsigned long flags; |
| bool change = false; |
| |
| new = (struct clocksource *) data; |
| |
| /* |
| * 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) |
| change = true; |
| else |
| module_put(new->owner); |
| } |
| |
| raw_spin_lock_irqsave(&timekeeper_lock, flags); |
| write_seqcount_begin(&tk_core.seq); |
| |
| timekeeping_forward_now(tk); |
| |
| if (change) { |
| old = tk->tkr_mono.clock; |
| tk_setup_internals(tk, new); |
| } |
| |
| 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); |
| |
| if (old) { |
| if (old->disable) |
| old->disable(old); |
| |
| module_put(old->owner); |
| } |
| |
| 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 int 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 int 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 int 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_clock64 - Return time from the persistent clock. |
| * @ts: Pointer to the storage for the readout value |
| * |
| * Weak dummy function for arches that do not yet support it. |
| * Reads the time from the battery backed persistent clock. |
| * 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_clock64(struct timespec64 *ts) |
| { |
| ts->tv_sec = 0; |
| ts->tv_nsec = 0; |
| } |
| |
| /** |
| * 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 |
| * @tk: Pointer to the timekeeper to be updated |
| * @delta: Pointer to the delta value in timespec64 format |
| * |
| * Takes a timespec offset measuring a suspend interval and properly |
| * adds the sleep offset to the timekeeping variables. |
| */ |
| 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(CLOCK_SET_WALL | CLOCK_SET_BOOT); |
| } |
| #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(); |
| |
| /* Resume the clockevent device(s) and hrtimers */ |
| tick_resume(); |
| /* Notify timerfd as resume is equivalent to clock_was_set() */ |
| timerfd_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 simplifies 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 |
| * 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 bool 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; |
| |
| 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; |
| |
| /* 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); |
| |
| return !!clock_set; |
| } |
| |
| /** |
| * update_wall_time - Uses the current clocksource to increment the wall time |
| * |
| */ |
| void update_wall_time(void) |
| { |
| if (timekeeping_advance(TK_ADV_TICK)) |
| 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); |
| |
| void ktime_get_coarse_real_ts64(struct timespec64 *ts) |
| { |
| struct timekeeper *tk = &tk_core.timekeeper; |
| unsigned int 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 int 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(); |
| } |
| |
| /** |
| * 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 __kernel_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 positive 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 __kernel_timex *txc) |
| { |
| struct timekeeper *tk = &tk_core.timekeeper; |
| struct audit_ntp_data ad; |
| bool clock_set = false; |
| struct timespec64 ts; |
| unsigned long flags; |
| 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; |
| |
| audit_tk_injoffset(delta); |
| } |
| |
| audit_ntp_init(&ad); |
| |
| 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, &ad); |
| |
| if (tai != orig_tai) { |
| __timekeeping_set_tai_offset(tk, tai); |
| timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET); |
| clock_set = true; |
| } |
| tk_update_leap_state(tk); |
| |
| write_seqcount_end(&tk_core.seq); |
| raw_spin_unlock_irqrestore(&timekeeper_lock, flags); |
| |
| audit_ntp_log(&ad); |
| |
| /* Update the multiplier immediately if frequency was set directly */ |
| if (txc->modes & (ADJ_FREQUENCY | ADJ_TICK)) |
| clock_set |= timekeeping_advance(TK_ADV_FREQ); |
| |
| if (clock_set) |
| clock_was_set(CLOCK_REALTIME); |
| |
| 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 */ |