1 files changed, 35 insertions, 0 deletions

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 6a92794427c9..8af77006e937 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -496,6 +496,39 @@ u64 notrace ktime_get_boot_fast_ns(void)
 }
 EXPORT_SYMBOL_GPL(ktime_get_boot_fast_ns);
 
+
+/*
+ * See comment for __ktime_get_fast_ns() vs. timestamp ordering
+ */
+static __always_inline u64 __ktime_get_real_fast_ns(struct tk_fast *tkf)
+{
+        struct tk_read_base *tkr;
+        unsigned int seq;
+        u64 now;
+
+        do {
+                seq = raw_read_seqcount_latch(&tkf->seq);
+                tkr = tkf->base + (seq & 0x01);
+                now = ktime_to_ns(tkr->base_real);
+
+                now += timekeeping_delta_to_ns(tkr,
+                                clocksource_delta(
+                                        tk_clock_read(tkr),
+                                        tkr->cycle_last,
+                                        tkr->mask));
+        } while (read_seqcount_retry(&tkf->seq, seq));
+
+        return now;
+}
+
+/**
+ * ktime_get_real_fast_ns: - NMI safe and fast access to clock realtime.
+ */
+u64 ktime_get_real_fast_ns(void)
+{
+        return __ktime_get_real_fast_ns(&tk_fast_mono);
+}
+
 /**
  * halt_fast_timekeeper - Prevent fast timekeeper from accessing clocksource.
  * @tk: Timekeeper to snapshot.
@@ -514,6 +547,7 @@ static void halt_fast_timekeeper(struct timekeeper *tk)
         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;
@@ -661,6 +695,7 @@ static void timekeeping_update(struct timekeeper *tk, unsigned int action)
         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);