11 files changed, 275 insertions, 171 deletions

diff --git a/kernel/time/Makefile b/kernel/time/Makefile
index f622cf28628a..c09c07817d7a 100644
--- a/kernel/time/Makefile
+++ b/kernel/time/Makefile
@@ -1,6 +1,6 @@
 obj-y += time.o timer.o hrtimer.o itimer.o posix-timers.o posix-cpu-timers.o
 obj-y += timekeeping.o ntp.o clocksource.o jiffies.o timer_list.o
-obj-y += timeconv.o posix-clock.o alarmtimer.o
+obj-y += timeconv.o timecounter.o posix-clock.o alarmtimer.o
 
 obj-$(CONFIG_GENERIC_CLOCKEVENTS_BUILD)         += clockevents.o
 obj-$(CONFIG_GENERIC_CLOCKEVENTS)               += tick-common.o
diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index a7077d3ae52f..1b001ed1edb9 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -788,7 +788,7 @@ static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
                         goto out;
         }
 
-        restart = &current_thread_info()->restart_block;
+        restart = &current->restart_block;
         restart->fn = alarm_timer_nsleep_restart;
         restart->nanosleep.clockid = type;
         restart->nanosleep.expires = exp.tv64;
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index b79f39bda7e1..4892352f0e49 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -34,82 +34,6 @@
 #include "tick-internal.h"
 #include "timekeeping_internal.h"
 
-void timecounter_init(struct timecounter *tc,
-                      const struct cyclecounter *cc,
-                      u64 start_tstamp)
-{
-        tc->cc = cc;
-        tc->cycle_last = cc->read(cc);
-        tc->nsec = start_tstamp;
-}
-EXPORT_SYMBOL_GPL(timecounter_init);
-
-/**
- * timecounter_read_delta - get nanoseconds since last call of this function
- * @tc:         Pointer to time counter
- *
- * When the underlying cycle counter runs over, this will be handled
- * correctly as long as it does not run over more than once between
- * calls.
- *
- * The first call to this function for a new time counter initializes
- * the time tracking and returns an undefined result.
- */
-static u64 timecounter_read_delta(struct timecounter *tc)
-{
-        cycle_t cycle_now, cycle_delta;
-        u64 ns_offset;
-
-        /* read cycle counter: */
-        cycle_now = tc->cc->read(tc->cc);
-
-        /* calculate the delta since the last timecounter_read_delta(): */
-        cycle_delta = (cycle_now - tc->cycle_last) & tc->cc->mask;
-
-        /* convert to nanoseconds: */
-        ns_offset = cyclecounter_cyc2ns(tc->cc, cycle_delta);
-
-        /* update time stamp of timecounter_read_delta() call: */
-        tc->cycle_last = cycle_now;
-
-        return ns_offset;
-}
-
-u64 timecounter_read(struct timecounter *tc)
-{
-        u64 nsec;
-
-        /* increment time by nanoseconds since last call */
-        nsec = timecounter_read_delta(tc);
-        nsec += tc->nsec;
-        tc->nsec = nsec;
-
-        return nsec;
-}
-EXPORT_SYMBOL_GPL(timecounter_read);
-
-u64 timecounter_cyc2time(struct timecounter *tc,
-                         cycle_t cycle_tstamp)
-{
-        u64 cycle_delta = (cycle_tstamp - tc->cycle_last) & tc->cc->mask;
-        u64 nsec;
-
-        /*
-         * Instead of always treating cycle_tstamp as more recent
-         * than tc->cycle_last, detect when it is too far in the
-         * future and treat it as old time stamp instead.
-         */
-        if (cycle_delta > tc->cc->mask / 2) {
-                cycle_delta = (tc->cycle_last - cycle_tstamp) & tc->cc->mask;
-                nsec = tc->nsec - cyclecounter_cyc2ns(tc->cc, cycle_delta);
-        } else {
-                nsec = cyclecounter_cyc2ns(tc->cc, cycle_delta) + tc->nsec;
-        }
-
-        return nsec;
-}
-EXPORT_SYMBOL_GPL(timecounter_cyc2time);
-
 /**
  * clocks_calc_mult_shift - calculate mult/shift factors for scaled math of clocks
  * @mult:       pointer to mult variable
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index d8c724cda37b..bee0c1f78091 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -266,7 +266,7 @@ lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
 /*
  * Divide a ktime value by a nanosecond value
  */
-u64 ktime_divns(const ktime_t kt, s64 div)
+u64 __ktime_divns(const ktime_t kt, s64 div)
 {
         u64 dclc;
         int sft = 0;
@@ -282,7 +282,7 @@ u64 ktime_divns(const ktime_t kt, s64 div)
 
         return dclc;
 }
-EXPORT_SYMBOL_GPL(ktime_divns);
+EXPORT_SYMBOL_GPL(__ktime_divns);
 #endif /* BITS_PER_LONG >= 64 */
 
 /*
@@ -440,6 +440,37 @@ static inline void debug_deactivate(struct hrtimer *timer)
         trace_hrtimer_cancel(timer);
 }
 
+#if defined(CONFIG_NO_HZ_COMMON) || defined(CONFIG_HIGH_RES_TIMERS)
+static ktime_t __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base)
+{
+        struct hrtimer_clock_base *base = cpu_base->clock_base;
+        ktime_t expires, expires_next = { .tv64 = KTIME_MAX };
+        int i;
+
+        for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) {
+                struct timerqueue_node *next;
+                struct hrtimer *timer;
+
+                next = timerqueue_getnext(&base->active);
+                if (!next)
+                        continue;
+
+                timer = container_of(next, struct hrtimer, node);
+                expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
+                if (expires.tv64 < expires_next.tv64)
+                        expires_next = expires;
+        }
+        /*
+         * clock_was_set() might have changed base->offset of any of
+         * the clock bases so the result might be negative. Fix it up
+         * to prevent a false positive in clockevents_program_event().
+         */
+        if (expires_next.tv64 < 0)
+                expires_next.tv64 = 0;
+        return expires_next;
+}
+#endif
+
 /* High resolution timer related functions */
 #ifdef CONFIG_HIGH_RES_TIMERS
 
@@ -488,32 +519,7 @@ static inline int hrtimer_hres_active(void)
 static void
 hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base, int skip_equal)
 {
-        int i;
-        struct hrtimer_clock_base *base = cpu_base->clock_base;
-        ktime_t expires, expires_next;
-
-        expires_next.tv64 = KTIME_MAX;
-
-        for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) {
-                struct hrtimer *timer;
-                struct timerqueue_node *next;
-
-                next = timerqueue_getnext(&base->active);
-                if (!next)
-                        continue;
-                timer = container_of(next, struct hrtimer, node);
-
-                expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
-                /*
-                 * clock_was_set() has changed base->offset so the
-                 * result might be negative. Fix it up to prevent a
-                 * false positive in clockevents_program_event()
-                 */
-                if (expires.tv64 < 0)
-                        expires.tv64 = 0;
-                if (expires.tv64 < expires_next.tv64)
-                        expires_next = expires;
-        }
+        ktime_t expires_next = __hrtimer_get_next_event(cpu_base);
 
         if (skip_equal && expires_next.tv64 == cpu_base->expires_next.tv64)
                 return;
@@ -587,6 +593,15 @@ static int hrtimer_reprogram(struct hrtimer *timer,
                 return 0;
 
         /*
+         * When the target cpu of the timer is currently executing
+         * hrtimer_interrupt(), then we do not touch the clock event
+         * device. hrtimer_interrupt() will reevaluate all clock bases
+         * before reprogramming the device.
+         */
+        if (cpu_base->in_hrtirq)
+                return 0;
+
+        /*
          * If a hang was detected in the last timer interrupt then we
          * do not schedule a timer which is earlier than the expiry
          * which we enforced in the hang detection. We want the system
@@ -1104,29 +1119,14 @@ EXPORT_SYMBOL_GPL(hrtimer_get_remaining);
 ktime_t hrtimer_get_next_event(void)
 {
         struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
-        struct hrtimer_clock_base *base = cpu_base->clock_base;
-        ktime_t delta, mindelta = { .tv64 = KTIME_MAX };
+        ktime_t mindelta = { .tv64 = KTIME_MAX };
         unsigned long flags;
-        int i;
 
         raw_spin_lock_irqsave(&cpu_base->lock, flags);
 
-        if (!hrtimer_hres_active()) {
-                for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) {
-                        struct hrtimer *timer;
-                        struct timerqueue_node *next;
-
-                        next = timerqueue_getnext(&base->active);
-                        if (!next)
-                                continue;
-
-                        timer = container_of(next, struct hrtimer, node);
-                        delta.tv64 = hrtimer_get_expires_tv64(timer);
-                        delta = ktime_sub(delta, base->get_time());
-                        if (delta.tv64 < mindelta.tv64)
-                                mindelta.tv64 = delta.tv64;
-                }
-        }
+        if (!hrtimer_hres_active())
+                mindelta = ktime_sub(__hrtimer_get_next_event(cpu_base),
+                                     ktime_get());
 
         raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
 
@@ -1253,7 +1253,7 @@ void hrtimer_interrupt(struct clock_event_device *dev)
         raw_spin_lock(&cpu_base->lock);
         entry_time = now = hrtimer_update_base(cpu_base);
 retry:
-        expires_next.tv64 = KTIME_MAX;
+        cpu_base->in_hrtirq = 1;
         /*
          * We set expires_next to KTIME_MAX here with cpu_base->lock
          * held to prevent that a timer is enqueued in our queue via
@@ -1291,28 +1291,20 @@ retry:
                          * are right-of a not yet expired timer, because that
                          * timer will have to trigger a wakeup anyway.
                          */
-
-                        if (basenow.tv64 < hrtimer_get_softexpires_tv64(timer)) {
-                                ktime_t expires;
-
-                                expires = ktime_sub(hrtimer_get_expires(timer),
-                                                    base->offset);
-                                if (expires.tv64 < 0)
-                                        expires.tv64 = KTIME_MAX;
-                                if (expires.tv64 < expires_next.tv64)
-                                        expires_next = expires;
+                        if (basenow.tv64 < hrtimer_get_softexpires_tv64(timer))
                                 break;
-                        }
 
                         __run_hrtimer(timer, &basenow);
                 }
         }
-
+        /* Reevaluate the clock bases for the next expiry */
+        expires_next = __hrtimer_get_next_event(cpu_base);
         /*
          * Store the new expiry value so the migration code can verify
          * against it.
          */
         cpu_base->expires_next = expires_next;
+        cpu_base->in_hrtirq = 0;
         raw_spin_unlock(&cpu_base->lock);
 
         /* Reprogramming necessary ? */
@@ -1591,7 +1583,7 @@ long hrtimer_nanosleep(struct timespec *rqtp, struct timespec __user *rmtp,
                         goto out;
         }
 
-        restart = &current_thread_info()->restart_block;
+        restart = &current->restart_block;
         restart->fn = hrtimer_nanosleep_restart;
         restart->nanosleep.clockid = t.timer.base->clockid;
         restart->nanosleep.rmtp = rmtp;
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 28bf91c60a0b..0f60b08a4f07 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -488,13 +488,13 @@ static void sync_cmos_clock(struct work_struct *work)
 
         getnstimeofday64(&now);
         if (abs(now.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec * 5) {
-                struct timespec adjust = timespec64_to_timespec(now);
+                struct timespec64 adjust = now;
 
                 fail = -ENODEV;
                 if (persistent_clock_is_local)
                         adjust.tv_sec -= (sys_tz.tz_minuteswest * 60);
 #ifdef CONFIG_GENERIC_CMOS_UPDATE
-                fail = update_persistent_clock(adjust);
+                fail = update_persistent_clock(timespec64_to_timespec(adjust));
 #endif
 #ifdef CONFIG_RTC_SYSTOHC
                 if (fail == -ENODEV)
@@ -633,10 +633,14 @@ int ntp_validate_timex(struct timex *txc)
         if ((txc->modes & ADJ_SETOFFSET) && (!capable(CAP_SYS_TIME)))
                 return -EPERM;
 
-        if (txc->modes & ADJ_FREQUENCY) {
-                if (LONG_MIN / PPM_SCALE > txc->freq)
+        /*
+         * 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 (LONG_MAX / PPM_SCALE < txc->freq)
+                if (LLONG_MAX / PPM_SCALE < txc->freq)
                         return -EINVAL;
         }
 
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index a16b67859e2a..0075da74abf0 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -1334,8 +1334,7 @@ static long posix_cpu_nsleep_restart(struct restart_block *restart_block);
 static int posix_cpu_nsleep(const clockid_t which_clock, int flags,
                             struct timespec *rqtp, struct timespec __user *rmtp)
 {
-        struct restart_block *restart_block =
-                &current_thread_info()->restart_block;
+        struct restart_block *restart_block = &current->restart_block;
         struct itimerspec it;
         int error;
 
diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index 7efeedf53ebd..f7c515595b42 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -394,6 +394,56 @@ void tick_resume(void)
         }
 }
 
+static DEFINE_RAW_SPINLOCK(tick_freeze_lock);
+static unsigned int tick_freeze_depth;
+
+/**
+ * tick_freeze - Suspend the local tick and (possibly) timekeeping.
+ *
+ * Check if this is the last online CPU executing the function and if so,
+ * suspend timekeeping.  Otherwise suspend the local tick.
+ *
+ * Call with interrupts disabled.  Must be balanced with %tick_unfreeze().
+ * Interrupts must not be enabled before the subsequent %tick_unfreeze().
+ */
+void tick_freeze(void)
+{
+        raw_spin_lock(&tick_freeze_lock);
+
+        tick_freeze_depth++;
+        if (tick_freeze_depth == num_online_cpus()) {
+                timekeeping_suspend();
+        } else {
+                tick_suspend();
+                tick_suspend_broadcast();
+        }
+
+        raw_spin_unlock(&tick_freeze_lock);
+}
+
+/**
+ * tick_unfreeze - Resume the local tick and (possibly) timekeeping.
+ *
+ * Check if this is the first CPU executing the function and if so, resume
+ * timekeeping.  Otherwise resume the local tick.
+ *
+ * Call with interrupts disabled.  Must be balanced with %tick_freeze().
+ * Interrupts must not be enabled after the preceding %tick_freeze().
+ */
+void tick_unfreeze(void)
+{
+        raw_spin_lock(&tick_freeze_lock);
+
+        if (tick_freeze_depth == num_online_cpus())
+                timekeeping_resume();
+        else
+                tick_resume();
+
+        tick_freeze_depth--;
+
+        raw_spin_unlock(&tick_freeze_lock);
+}
+
 /**
  * tick_init - initialize the tick control
  */
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 1363d58f07e9..a4c4edac4528 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -326,13 +326,6 @@ static int tick_nohz_cpu_down_callback(struct notifier_block *nfb,
         return NOTIFY_OK;
 }
 
-/*
- * Worst case string length in chunks of CPU range seems 2 steps
- * separations: 0,2,4,6,...
- * This is NR_CPUS + sizeof('\0')
- */
-static char __initdata nohz_full_buf[NR_CPUS + 1];
-
 static int tick_nohz_init_all(void)
 {
         int err = -1;
@@ -393,8 +386,8 @@ void __init tick_nohz_init(void)
                 context_tracking_cpu_set(cpu);
 
         cpu_notifier(tick_nohz_cpu_down_callback, 0);
-        cpulist_scnprintf(nohz_full_buf, sizeof(nohz_full_buf), tick_nohz_full_mask);
-        pr_info("NO_HZ: Full dynticks CPUs: %s.\n", nohz_full_buf);
+        pr_info("NO_HZ: Full dynticks CPUs: %*pbl.\n",
+                cpumask_pr_args(tick_nohz_full_mask));
 }
 #endif
 
diff --git a/kernel/time/timecounter.c b/kernel/time/timecounter.c
new file mode 100644
index 000000000000..4687b3104bae
--- /dev/null
+++ b/kernel/time/timecounter.c
@@ -0,0 +1,112 @@
+/*
+ * linux/kernel/time/timecounter.c
+ *
+ * based on code that migrated away from
+ * linux/kernel/time/clocksource.c
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/export.h>
+#include <linux/timecounter.h>
+
+void timecounter_init(struct timecounter *tc,
+                      const struct cyclecounter *cc,
+                      u64 start_tstamp)
+{
+        tc->cc = cc;
+        tc->cycle_last = cc->read(cc);
+        tc->nsec = start_tstamp;
+        tc->mask = (1ULL << cc->shift) - 1;
+        tc->frac = 0;
+}
+EXPORT_SYMBOL_GPL(timecounter_init);
+
+/**
+ * timecounter_read_delta - get nanoseconds since last call of this function
+ * @tc:         Pointer to time counter
+ *
+ * When the underlying cycle counter runs over, this will be handled
+ * correctly as long as it does not run over more than once between
+ * calls.
+ *
+ * The first call to this function for a new time counter initializes
+ * the time tracking and returns an undefined result.
+ */
+static u64 timecounter_read_delta(struct timecounter *tc)
+{
+        cycle_t cycle_now, cycle_delta;
+        u64 ns_offset;
+
+        /* read cycle counter: */
+        cycle_now = tc->cc->read(tc->cc);
+
+        /* calculate the delta since the last timecounter_read_delta(): */
+        cycle_delta = (cycle_now - tc->cycle_last) & tc->cc->mask;
+
+        /* convert to nanoseconds: */
+        ns_offset = cyclecounter_cyc2ns(tc->cc, cycle_delta,
+                                        tc->mask, &tc->frac);
+
+        /* update time stamp of timecounter_read_delta() call: */
+        tc->cycle_last = cycle_now;
+
+        return ns_offset;
+}
+
+u64 timecounter_read(struct timecounter *tc)
+{
+        u64 nsec;
+
+        /* increment time by nanoseconds since last call */
+        nsec = timecounter_read_delta(tc);
+        nsec += tc->nsec;
+        tc->nsec = nsec;
+
+        return nsec;
+}
+EXPORT_SYMBOL_GPL(timecounter_read);
+
+/*
+ * This is like cyclecounter_cyc2ns(), but it is used for computing a
+ * time previous to the time stored in the cycle counter.
+ */
+static u64 cc_cyc2ns_backwards(const struct cyclecounter *cc,
+                               cycle_t cycles, u64 mask, u64 frac)
+{
+        u64 ns = (u64) cycles;
+
+        ns = ((ns * cc->mult) - frac) >> cc->shift;
+
+        return ns;
+}
+
+u64 timecounter_cyc2time(struct timecounter *tc,
+                         cycle_t cycle_tstamp)
+{
+        u64 delta = (cycle_tstamp - tc->cycle_last) & tc->cc->mask;
+        u64 nsec = tc->nsec, frac = tc->frac;
+
+        /*
+         * Instead of always treating cycle_tstamp as more recent
+         * than tc->cycle_last, detect when it is too far in the
+         * future and treat it as old time stamp instead.
+         */
+        if (delta > tc->cc->mask / 2) {
+                delta = (tc->cycle_last - cycle_tstamp) & tc->cc->mask;
+                nsec -= cc_cyc2ns_backwards(tc->cc, delta, tc->mask, frac);
+        } else {
+                nsec += cyclecounter_cyc2ns(tc->cc, delta, tc->mask, &frac);
+        }
+
+        return nsec;
+}
+EXPORT_SYMBOL_GPL(timecounter_cyc2time);
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 6a931852082f..91db94136c10 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -230,9 +230,7 @@ static inline s64 timekeeping_get_ns_raw(struct timekeeper *tk)
 
 /**
  * update_fast_timekeeper - Update the fast and NMI safe monotonic timekeeper.
- * @tk:         The timekeeper from which we take the update
- * @tkf:        The fast timekeeper to update
- * @tbase:      The time base for the fast timekeeper (mono/raw)
+ * @tkr: Timekeeping readout base from which we take the update
  *
  * We want to use this from any context including NMI and tracing /
  * instrumenting the timekeeping code itself.
@@ -244,11 +242,11 @@ static inline s64 timekeeping_get_ns_raw(struct timekeeper *tk)
  * smp_wmb();   <- Ensure that the last base[1] update is visible
  * tkf->seq++;
  * smp_wmb();   <- Ensure that the seqcount update is visible
- * update(tkf->base[0], tk);
+ * update(tkf->base[0], tkr);
  * smp_wmb();   <- Ensure that the base[0] update is visible
  * tkf->seq++;
  * smp_wmb();   <- Ensure that the seqcount update is visible
- * update(tkf->base[1], tk);
+ * update(tkf->base[1], tkr);
  *
  * The reader side does:
  *
@@ -269,7 +267,7 @@ static inline s64 timekeeping_get_ns_raw(struct timekeeper *tk)
  * slightly wrong timestamp (a few nanoseconds). See
  * @ktime_get_mono_fast_ns.
  */
-static void update_fast_timekeeper(struct timekeeper *tk)
+static void update_fast_timekeeper(struct tk_read_base *tkr)
 {
         struct tk_read_base *base = tk_fast_mono.base;
 
@@ -277,7 +275,7 @@ static void update_fast_timekeeper(struct timekeeper *tk)
         raw_write_seqcount_latch(&tk_fast_mono.seq);
 
         /* Update base[0] */
-        memcpy(base, &tk->tkr, sizeof(*base));
+        memcpy(base, tkr, sizeof(*base));
 
         /* Force readers back to base[0] */
         raw_write_seqcount_latch(&tk_fast_mono.seq);
@@ -334,6 +332,35 @@ u64 notrace ktime_get_mono_fast_ns(void)
 }
 EXPORT_SYMBOL_GPL(ktime_get_mono_fast_ns);
 
+/* Suspend-time cycles value for halted fast timekeeper. */
+static cycle_t cycles_at_suspend;
+
+static cycle_t dummy_clock_read(struct clocksource *cs)
+{
+        return cycles_at_suspend;
+}
+
+/**
+ * halt_fast_timekeeper - Prevent fast timekeeper from accessing clocksource.
+ * @tk: Timekeeper to snapshot.
+ *
+ * It generally is unsafe to access the clocksource after timekeeping has been
+ * suspended, so take a snapshot of the readout base of @tk and use it as the
+ * fast timekeeper's readout base while suspended.  It will return the same
+ * number of cycles every time until timekeeping is resumed at which time the
+ * proper readout base for the fast timekeeper will be restored automatically.
+ */
+static void halt_fast_timekeeper(struct timekeeper *tk)
+{
+        static struct tk_read_base tkr_dummy;
+        struct tk_read_base *tkr = &tk->tkr;
+
+        memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
+        cycles_at_suspend = tkr->read(tkr->clock);
+        tkr_dummy.read = dummy_clock_read;
+        update_fast_timekeeper(&tkr_dummy);
+}
+
 #ifdef CONFIG_GENERIC_TIME_VSYSCALL_OLD
 
 static inline void update_vsyscall(struct timekeeper *tk)
@@ -462,7 +489,7 @@ static void timekeeping_update(struct timekeeper *tk, unsigned int action)
                 memcpy(&shadow_timekeeper, &tk_core.timekeeper,
                        sizeof(tk_core.timekeeper));
 
-        update_fast_timekeeper(tk);
+        update_fast_timekeeper(&tk->tkr);
 }
 
 /**
@@ -1170,7 +1197,7 @@ void timekeeping_inject_sleeptime64(struct timespec64 *delta)
  * xtime/wall_to_monotonic/jiffies/etc are
  * still managed by arch specific suspend/resume code.
  */
-static void timekeeping_resume(void)
+void timekeeping_resume(void)
 {
         struct timekeeper *tk = &tk_core.timekeeper;
         struct clocksource *clock = tk->tkr.clock;
@@ -1251,7 +1278,7 @@ static void timekeeping_resume(void)
         hrtimers_resume();
 }
 
-static int timekeeping_suspend(void)
+int timekeeping_suspend(void)
 {
         struct timekeeper *tk = &tk_core.timekeeper;
         unsigned long flags;
@@ -1296,6 +1323,7 @@ static int timekeeping_suspend(void)
         }
 
         timekeeping_update(tk, TK_MIRROR);
+        halt_fast_timekeeper(tk);
         write_seqcount_end(&tk_core.seq);
         raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
 
@@ -1659,24 +1687,24 @@ out:
 }
 
 /**
- * getboottime - Return the real time of system boot.
- * @ts:         pointer to the timespec to be set
+ * getboottime64 - Return the real time of system boot.
+ * @ts:         pointer to the timespec64 to be set
  *
- * Returns the wall-time of boot in a timespec.
+ * 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 getboottime(struct timespec *ts)
+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_timespec(t);
+        *ts = ktime_to_timespec64(t);
 }
-EXPORT_SYMBOL_GPL(getboottime);
+EXPORT_SYMBOL_GPL(getboottime64);
 
 unsigned long get_seconds(void)
 {
diff --git a/kernel/time/timekeeping.h b/kernel/time/timekeeping.h
index adc1fc98bde3..1d91416055d5 100644
--- a/kernel/time/timekeeping.h
+++ b/kernel/time/timekeeping.h
@@ -16,5 +16,7 @@ extern int timekeeping_inject_offset(struct timespec *ts);
 extern s32 timekeeping_get_tai_offset(void);
 extern void timekeeping_set_tai_offset(s32 tai_offset);
 extern void timekeeping_clocktai(struct timespec *ts);
+extern int timekeeping_suspend(void);
+extern void timekeeping_resume(void);
 
 #endif