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2467 lines
70 KiB
2467 lines
70 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Kernel timekeeping code and accessor functions. Based on code from |
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* timer.c, moved in commit 8524070b7982. |
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*/ |
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#include <linux/timekeeper_internal.h> |
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#include <linux/module.h> |
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#include <linux/interrupt.h> |
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#include <linux/percpu.h> |
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#include <linux/init.h> |
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#include <linux/mm.h> |
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#include <linux/nmi.h> |
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#include <linux/sched.h> |
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#include <linux/sched/loadavg.h> |
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#include <linux/sched/clock.h> |
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#include <linux/syscore_ops.h> |
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#include <linux/clocksource.h> |
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#include <linux/jiffies.h> |
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#include <linux/time.h> |
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#include <linux/tick.h> |
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#include <linux/stop_machine.h> |
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#include <linux/pvclock_gtod.h> |
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#include <linux/compiler.h> |
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#include <linux/audit.h> |
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|
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#include "tick-internal.h" |
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#include "ntp_internal.h" |
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#include "timekeeping_internal.h" |
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|
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#define TK_CLEAR_NTP (1 << 0) |
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#define TK_MIRROR (1 << 1) |
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#define TK_CLOCK_WAS_SET (1 << 2) |
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enum timekeeping_adv_mode { |
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/* Update timekeeper when a tick has passed */ |
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TK_ADV_TICK, |
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|
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/* Update timekeeper on a direct frequency change */ |
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TK_ADV_FREQ |
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}; |
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|
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DEFINE_RAW_SPINLOCK(timekeeper_lock); |
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|
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/* |
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* The most important data for readout fits into a single 64 byte |
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* cache line. |
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*/ |
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static struct { |
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seqcount_raw_spinlock_t seq; |
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struct timekeeper timekeeper; |
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} tk_core ____cacheline_aligned = { |
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.seq = SEQCNT_RAW_SPINLOCK_ZERO(tk_core.seq, &timekeeper_lock), |
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}; |
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|
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static struct timekeeper shadow_timekeeper; |
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|
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/* flag for if timekeeping is suspended */ |
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int __read_mostly timekeeping_suspended; |
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|
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/** |
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* struct tk_fast - NMI safe timekeeper |
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* @seq: Sequence counter for protecting updates. The lowest bit |
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* is the index for the tk_read_base array |
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* @base: tk_read_base array. Access is indexed by the lowest bit of |
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* @seq. |
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* |
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* See @update_fast_timekeeper() below. |
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*/ |
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struct tk_fast { |
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seqcount_latch_t seq; |
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struct tk_read_base base[2]; |
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}; |
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|
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/* Suspend-time cycles value for halted fast timekeeper. */ |
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static u64 cycles_at_suspend; |
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|
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static u64 dummy_clock_read(struct clocksource *cs) |
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{ |
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if (timekeeping_suspended) |
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return cycles_at_suspend; |
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return local_clock(); |
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} |
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|
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static struct clocksource dummy_clock = { |
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.read = dummy_clock_read, |
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}; |
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|
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/* |
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* Boot time initialization which allows local_clock() to be utilized |
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* during early boot when clocksources are not available. local_clock() |
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* returns nanoseconds already so no conversion is required, hence mult=1 |
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* and shift=0. When the first proper clocksource is installed then |
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* the fast time keepers are updated with the correct values. |
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*/ |
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#define FAST_TK_INIT \ |
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{ \ |
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.clock = &dummy_clock, \ |
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.mask = CLOCKSOURCE_MASK(64), \ |
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.mult = 1, \ |
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.shift = 0, \ |
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} |
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static struct tk_fast tk_fast_mono ____cacheline_aligned = { |
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.seq = SEQCNT_LATCH_ZERO(tk_fast_mono.seq), |
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.base[0] = FAST_TK_INIT, |
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.base[1] = FAST_TK_INIT, |
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}; |
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static struct tk_fast tk_fast_raw ____cacheline_aligned = { |
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.seq = SEQCNT_LATCH_ZERO(tk_fast_raw.seq), |
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.base[0] = FAST_TK_INIT, |
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.base[1] = FAST_TK_INIT, |
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}; |
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|
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static inline void tk_normalize_xtime(struct timekeeper *tk) |
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{ |
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while (tk->tkr_mono.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_mono.shift)) { |
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tk->tkr_mono.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_mono.shift; |
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tk->xtime_sec++; |
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} |
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while (tk->tkr_raw.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_raw.shift)) { |
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tk->tkr_raw.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_raw.shift; |
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tk->raw_sec++; |
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} |
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} |
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static inline struct timespec64 tk_xtime(const struct timekeeper *tk) |
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{ |
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struct timespec64 ts; |
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|
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ts.tv_sec = tk->xtime_sec; |
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ts.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift); |
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return ts; |
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} |
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static void tk_set_xtime(struct timekeeper *tk, const struct timespec64 *ts) |
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{ |
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tk->xtime_sec = ts->tv_sec; |
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tk->tkr_mono.xtime_nsec = (u64)ts->tv_nsec << tk->tkr_mono.shift; |
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} |
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static void tk_xtime_add(struct timekeeper *tk, const struct timespec64 *ts) |
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{ |
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tk->xtime_sec += ts->tv_sec; |
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tk->tkr_mono.xtime_nsec += (u64)ts->tv_nsec << tk->tkr_mono.shift; |
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tk_normalize_xtime(tk); |
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} |
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static void tk_set_wall_to_mono(struct timekeeper *tk, struct timespec64 wtm) |
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{ |
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struct timespec64 tmp; |
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|
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/* |
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* Verify consistency of: offset_real = -wall_to_monotonic |
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* before modifying anything |
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*/ |
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set_normalized_timespec64(&tmp, -tk->wall_to_monotonic.tv_sec, |
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-tk->wall_to_monotonic.tv_nsec); |
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WARN_ON_ONCE(tk->offs_real != timespec64_to_ktime(tmp)); |
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tk->wall_to_monotonic = wtm; |
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set_normalized_timespec64(&tmp, -wtm.tv_sec, -wtm.tv_nsec); |
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tk->offs_real = timespec64_to_ktime(tmp); |
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tk->offs_tai = ktime_add(tk->offs_real, ktime_set(tk->tai_offset, 0)); |
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} |
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static inline void tk_update_sleep_time(struct timekeeper *tk, ktime_t delta) |
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{ |
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tk->offs_boot = ktime_add(tk->offs_boot, delta); |
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/* |
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* Timespec representation for VDSO update to avoid 64bit division |
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* on every update. |
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*/ |
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tk->monotonic_to_boot = ktime_to_timespec64(tk->offs_boot); |
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} |
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/* |
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* tk_clock_read - atomic clocksource read() helper |
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* |
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* This helper is necessary to use in the read paths because, while the |
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* seqcount ensures we don't return a bad value while structures are updated, |
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* it doesn't protect from potential crashes. There is the possibility that |
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* the tkr's clocksource may change between the read reference, and the |
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* clock reference passed to the read function. This can cause crashes if |
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* the wrong clocksource is passed to the wrong read function. |
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* This isn't necessary to use when holding the timekeeper_lock or doing |
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* a read of the fast-timekeeper tkrs (which is protected by its own locking |
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* and update logic). |
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*/ |
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static inline u64 tk_clock_read(const struct tk_read_base *tkr) |
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{ |
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struct clocksource *clock = READ_ONCE(tkr->clock); |
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return clock->read(clock); |
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} |
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#ifdef CONFIG_DEBUG_TIMEKEEPING |
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#define WARNING_FREQ (HZ*300) /* 5 minute rate-limiting */ |
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static void timekeeping_check_update(struct timekeeper *tk, u64 offset) |
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{ |
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u64 max_cycles = tk->tkr_mono.clock->max_cycles; |
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const char *name = tk->tkr_mono.clock->name; |
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if (offset > max_cycles) { |
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printk_deferred("WARNING: timekeeping: Cycle offset (%lld) is larger than allowed by the '%s' clock's max_cycles value (%lld): time overflow danger\n", |
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offset, name, max_cycles); |
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printk_deferred(" timekeeping: Your kernel is sick, but tries to cope by capping time updates\n"); |
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} else { |
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if (offset > (max_cycles >> 1)) { |
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printk_deferred("INFO: timekeeping: Cycle offset (%lld) is larger than the '%s' clock's 50%% safety margin (%lld)\n", |
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offset, name, max_cycles >> 1); |
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printk_deferred(" timekeeping: Your kernel is still fine, but is feeling a bit nervous\n"); |
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} |
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} |
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if (tk->underflow_seen) { |
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if (jiffies - tk->last_warning > WARNING_FREQ) { |
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printk_deferred("WARNING: Underflow in clocksource '%s' observed, time update ignored.\n", name); |
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printk_deferred(" Please report this, consider using a different clocksource, if possible.\n"); |
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printk_deferred(" Your kernel is probably still fine.\n"); |
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tk->last_warning = jiffies; |
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} |
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tk->underflow_seen = 0; |
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} |
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if (tk->overflow_seen) { |
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if (jiffies - tk->last_warning > WARNING_FREQ) { |
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printk_deferred("WARNING: Overflow in clocksource '%s' observed, time update capped.\n", name); |
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printk_deferred(" Please report this, consider using a different clocksource, if possible.\n"); |
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printk_deferred(" Your kernel is probably still fine.\n"); |
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tk->last_warning = jiffies; |
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} |
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tk->overflow_seen = 0; |
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} |
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} |
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static inline u64 timekeeping_get_delta(const struct tk_read_base *tkr) |
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{ |
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struct timekeeper *tk = &tk_core.timekeeper; |
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u64 now, last, mask, max, delta; |
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unsigned int seq; |
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/* |
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* Since we're called holding a seqcount, the data may shift |
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* under us while we're doing the calculation. This can cause |
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* false positives, since we'd note a problem but throw the |
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* results away. So nest another seqcount here to atomically |
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* grab the points we are checking with. |
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*/ |
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do { |
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seq = read_seqcount_begin(&tk_core.seq); |
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now = tk_clock_read(tkr); |
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last = tkr->cycle_last; |
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mask = tkr->mask; |
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max = tkr->clock->max_cycles; |
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} while (read_seqcount_retry(&tk_core.seq, seq)); |
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delta = clocksource_delta(now, last, mask); |
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/* |
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* Try to catch underflows by checking if we are seeing small |
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* mask-relative negative values. |
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*/ |
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if (unlikely((~delta & mask) < (mask >> 3))) { |
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tk->underflow_seen = 1; |
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delta = 0; |
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} |
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/* Cap delta value to the max_cycles values to avoid mult overflows */ |
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if (unlikely(delta > max)) { |
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tk->overflow_seen = 1; |
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delta = tkr->clock->max_cycles; |
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} |
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return delta; |
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} |
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#else |
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static inline void timekeeping_check_update(struct timekeeper *tk, u64 offset) |
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{ |
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} |
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static inline u64 timekeeping_get_delta(const struct tk_read_base *tkr) |
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{ |
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u64 cycle_now, delta; |
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/* read clocksource */ |
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cycle_now = tk_clock_read(tkr); |
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|
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/* calculate the delta since the last update_wall_time */ |
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delta = clocksource_delta(cycle_now, tkr->cycle_last, tkr->mask); |
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return delta; |
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} |
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#endif |
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/** |
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* tk_setup_internals - Set up internals to use clocksource clock. |
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* |
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* @tk: The target timekeeper to setup. |
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* @clock: Pointer to clocksource. |
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* |
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* Calculates a fixed cycle/nsec interval for a given clocksource/adjustment |
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* pair and interval request. |
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* |
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* Unless you're the timekeeping code, you should not be using this! |
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*/ |
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static void tk_setup_internals(struct timekeeper *tk, struct clocksource *clock) |
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{ |
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u64 interval; |
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u64 tmp, ntpinterval; |
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struct clocksource *old_clock; |
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++tk->cs_was_changed_seq; |
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old_clock = tk->tkr_mono.clock; |
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tk->tkr_mono.clock = clock; |
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tk->tkr_mono.mask = clock->mask; |
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tk->tkr_mono.cycle_last = tk_clock_read(&tk->tkr_mono); |
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tk->tkr_raw.clock = clock; |
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tk->tkr_raw.mask = clock->mask; |
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tk->tkr_raw.cycle_last = tk->tkr_mono.cycle_last; |
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/* Do the ns -> cycle conversion first, using original mult */ |
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tmp = NTP_INTERVAL_LENGTH; |
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tmp <<= clock->shift; |
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ntpinterval = tmp; |
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tmp += clock->mult/2; |
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do_div(tmp, clock->mult); |
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if (tmp == 0) |
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tmp = 1; |
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interval = (u64) tmp; |
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tk->cycle_interval = interval; |
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|
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/* Go back from cycles -> shifted ns */ |
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tk->xtime_interval = interval * clock->mult; |
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tk->xtime_remainder = ntpinterval - tk->xtime_interval; |
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tk->raw_interval = interval * clock->mult; |
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|
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/* if changing clocks, convert xtime_nsec shift units */ |
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if (old_clock) { |
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int shift_change = clock->shift - old_clock->shift; |
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if (shift_change < 0) { |
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tk->tkr_mono.xtime_nsec >>= -shift_change; |
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tk->tkr_raw.xtime_nsec >>= -shift_change; |
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} else { |
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tk->tkr_mono.xtime_nsec <<= shift_change; |
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tk->tkr_raw.xtime_nsec <<= shift_change; |
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} |
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} |
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tk->tkr_mono.shift = clock->shift; |
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tk->tkr_raw.shift = clock->shift; |
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tk->ntp_error = 0; |
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tk->ntp_error_shift = NTP_SCALE_SHIFT - clock->shift; |
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tk->ntp_tick = ntpinterval << tk->ntp_error_shift; |
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/* |
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* The timekeeper keeps its own mult values for the currently |
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* active clocksource. These value will be adjusted via NTP |
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* to counteract clock drifting. |
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*/ |
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tk->tkr_mono.mult = clock->mult; |
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tk->tkr_raw.mult = clock->mult; |
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tk->ntp_err_mult = 0; |
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tk->skip_second_overflow = 0; |
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} |
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/* Timekeeper helper functions. */ |
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static inline u64 timekeeping_delta_to_ns(const struct tk_read_base *tkr, u64 delta) |
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{ |
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u64 nsec; |
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nsec = delta * tkr->mult + tkr->xtime_nsec; |
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nsec >>= tkr->shift; |
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return nsec; |
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} |
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static inline u64 timekeeping_get_ns(const struct tk_read_base *tkr) |
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{ |
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u64 delta; |
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delta = timekeeping_get_delta(tkr); |
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return timekeeping_delta_to_ns(tkr, delta); |
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} |
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static inline u64 timekeeping_cycles_to_ns(const struct tk_read_base *tkr, u64 cycles) |
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{ |
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u64 delta; |
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|
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/* calculate the delta since the last update_wall_time */ |
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delta = clocksource_delta(cycles, tkr->cycle_last, tkr->mask); |
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return timekeeping_delta_to_ns(tkr, delta); |
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} |
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/** |
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* update_fast_timekeeper - Update the fast and NMI safe monotonic timekeeper. |
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* @tkr: Timekeeping readout base from which we take the update |
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* @tkf: Pointer to NMI safe timekeeper |
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* |
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* We want to use this from any context including NMI and tracing / |
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* instrumenting the timekeeping code itself. |
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* |
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* Employ the latch technique; see @raw_write_seqcount_latch. |
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* |
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* So if a NMI hits the update of base[0] then it will use base[1] |
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* which is still consistent. In the worst case this can result is a |
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* slightly wrong timestamp (a few nanoseconds). See |
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* @ktime_get_mono_fast_ns. |
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*/ |
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static void update_fast_timekeeper(const struct tk_read_base *tkr, |
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struct tk_fast *tkf) |
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{ |
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struct tk_read_base *base = tkf->base; |
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|
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/* Force readers off to base[1] */ |
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raw_write_seqcount_latch(&tkf->seq); |
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|
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/* Update base[0] */ |
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memcpy(base, tkr, sizeof(*base)); |
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|
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/* Force readers back to base[0] */ |
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raw_write_seqcount_latch(&tkf->seq); |
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|
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/* Update base[1] */ |
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memcpy(base + 1, base, sizeof(*base)); |
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} |
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|
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static __always_inline u64 __ktime_get_fast_ns(struct tk_fast *tkf) |
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{ |
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struct tk_read_base *tkr; |
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unsigned int seq; |
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u64 now; |
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|
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do { |
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seq = raw_read_seqcount_latch(&tkf->seq); |
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tkr = tkf->base + (seq & 0x01); |
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now = ktime_to_ns(tkr->base); |
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|
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now += timekeeping_delta_to_ns(tkr, |
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clocksource_delta( |
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tk_clock_read(tkr), |
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tkr->cycle_last, |
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tkr->mask)); |
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} while (read_seqcount_latch_retry(&tkf->seq, seq)); |
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|
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return now; |
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} |
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|
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/** |
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* ktime_get_mono_fast_ns - Fast NMI safe access to clock monotonic |
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* |
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* This timestamp is not guaranteed to be monotonic across an update. |
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* The timestamp is calculated by: |
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* |
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* now = base_mono + clock_delta * slope |
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* |
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* So if the update lowers the slope, readers who are forced to the |
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* not yet updated second array are still using the old steeper slope. |
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* |
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* tmono |
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* ^ |
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* | o n |
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* | o n |
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* | u |
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* | o |
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* |o |
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* |12345678---> reader order |
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* |
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* o = old slope |
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* u = update |
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* n = new slope |
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* |
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* So reader 6 will observe time going backwards versus reader 5. |
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* |
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* While other CPUs are likely to be able to observe that, the only way |
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* for a CPU local observation is when an NMI hits in the middle of |
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* the update. Timestamps taken from that NMI context might be ahead |
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* of the following timestamps. Callers need to be aware of that and |
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* deal with it. |
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*/ |
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u64 ktime_get_mono_fast_ns(void) |
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{ |
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return __ktime_get_fast_ns(&tk_fast_mono); |
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} |
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EXPORT_SYMBOL_GPL(ktime_get_mono_fast_ns); |
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|
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/** |
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* ktime_get_raw_fast_ns - Fast NMI safe access to clock monotonic raw |
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* |
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* Contrary to ktime_get_mono_fast_ns() this is always correct because the |
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* conversion factor is not affected by NTP/PTP correction. |
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*/ |
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u64 ktime_get_raw_fast_ns(void) |
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{ |
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return __ktime_get_fast_ns(&tk_fast_raw); |
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} |
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EXPORT_SYMBOL_GPL(ktime_get_raw_fast_ns); |
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|
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/** |
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* ktime_get_boot_fast_ns - NMI safe and fast access to boot clock. |
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* |
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* To keep it NMI safe since we're accessing from tracing, we're not using a |
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* separate timekeeper with updates to monotonic clock and boot offset |
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* protected with seqcounts. This has the following minor side effects: |
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* |
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* (1) Its possible that a timestamp be taken after the boot offset is updated |
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* but before the timekeeper is updated. If this happens, the new boot offset |
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* is added to the old timekeeping making the clock appear to update slightly |
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* earlier: |
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* CPU 0 CPU 1 |
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* timekeeping_inject_sleeptime64() |
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* __timekeeping_inject_sleeptime(tk, delta); |
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* timestamp(); |
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* timekeeping_update(tk, TK_CLEAR_NTP...); |
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* |
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* (2) On 32-bit systems, the 64-bit boot offset (tk->offs_boot) may be |
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* partially updated. Since the tk->offs_boot update is a rare event, this |
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* should be a rare occurrence which postprocessing should be able to handle. |
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* |
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* The caveats vs. timestamp ordering as documented for ktime_get_fast_ns() |
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* apply as well. |
|
*/ |
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u64 notrace ktime_get_boot_fast_ns(void) |
|
{ |
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struct timekeeper *tk = &tk_core.timekeeper; |
|
|
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return (ktime_get_mono_fast_ns() + ktime_to_ns(tk->offs_boot)); |
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} |
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EXPORT_SYMBOL_GPL(ktime_get_boot_fast_ns); |
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|
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static __always_inline u64 __ktime_get_real_fast(struct tk_fast *tkf, u64 *mono) |
|
{ |
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struct tk_read_base *tkr; |
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u64 basem, baser, delta; |
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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 = timekeeping_delta_to_ns(tkr, |
|
clocksource_delta(tk_clock_read(tkr), |
|
tkr->cycle_last, tkr->mask)); |
|
} 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.tv_sec = ts->tv_sec - xt.tv_sec; |
|
ts_delta.tv_nsec = ts->tv_nsec - xt.tv_nsec; |
|
|
|
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; |
|
} |
|
|
|
|
|
/** |
|
* 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 */
|
|
|