1 files changed, 44 insertions, 16 deletions

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)
 {