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-rw-r--r--kernel/time/timekeeping.c54
1 files changed, 43 insertions, 11 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 3b1398fbddaf..8e4b3c32fcf9 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -17,6 +17,7 @@
#include <linux/clocksource.h>
#include <linux/jiffies.h>
#include <linux/time.h>
+#include <linux/timex.h>
#include <linux/tick.h>
#include <linux/stop_machine.h>
#include <linux/pvclock_gtod.h>
@@ -429,6 +430,14 @@ static void update_fast_timekeeper(const struct tk_read_base *tkr,
memcpy(base + 1, base, sizeof(*base));
}
+static __always_inline u64 fast_tk_get_delta_ns(struct tk_read_base *tkr)
+{
+ u64 delta, cycles = tk_clock_read(tkr);
+
+ delta = clocksource_delta(cycles, tkr->cycle_last, tkr->mask);
+ return timekeeping_delta_to_ns(tkr, delta);
+}
+
static __always_inline u64 __ktime_get_fast_ns(struct tk_fast *tkf)
{
struct tk_read_base *tkr;
@@ -439,12 +448,7 @@ static __always_inline u64 __ktime_get_fast_ns(struct tk_fast *tkf)
seq = raw_read_seqcount_latch(&tkf->seq);
tkr = tkf->base + (seq & 0x01);
now = ktime_to_ns(tkr->base);
-
- now += timekeeping_delta_to_ns(tkr,
- clocksource_delta(
- tk_clock_read(tkr),
- tkr->cycle_last,
- tkr->mask));
+ now += fast_tk_get_delta_ns(tkr);
} while (read_seqcount_latch_retry(&tkf->seq, seq));
return now;
@@ -528,10 +532,27 @@ u64 notrace ktime_get_boot_fast_ns(void)
{
struct timekeeper *tk = &tk_core.timekeeper;
- return (ktime_get_mono_fast_ns() + ktime_to_ns(tk->offs_boot));
+ return (ktime_get_mono_fast_ns() + ktime_to_ns(data_race(tk->offs_boot)));
}
EXPORT_SYMBOL_GPL(ktime_get_boot_fast_ns);
+/**
+ * ktime_get_tai_fast_ns - NMI safe and fast access to tai clock.
+ *
+ * The same limitations as described for ktime_get_boot_fast_ns() apply. The
+ * mono time and the TAI offset are not read atomically which may yield wrong
+ * readouts. However, an update of the TAI offset is an rare event e.g., caused
+ * by settime or adjtimex with an offset. The user of this function has to deal
+ * with the possibility of wrong timestamps in post processing.
+ */
+u64 notrace ktime_get_tai_fast_ns(void)
+{
+ struct timekeeper *tk = &tk_core.timekeeper;
+
+ return (ktime_get_mono_fast_ns() + ktime_to_ns(data_race(tk->offs_tai)));
+}
+EXPORT_SYMBOL_GPL(ktime_get_tai_fast_ns);
+
static __always_inline u64 __ktime_get_real_fast(struct tk_fast *tkf, u64 *mono)
{
struct tk_read_base *tkr;
@@ -543,10 +564,7 @@ static __always_inline u64 __ktime_get_real_fast(struct tk_fast *tkf, u64 *mono)
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));
+ delta = fast_tk_get_delta_ns(tkr);
} while (read_seqcount_latch_retry(&tkf->seq, seq));
if (mono)
@@ -2380,6 +2398,20 @@ static int timekeeping_validate_timex(const struct __kernel_timex *txc)
return 0;
}
+/**
+ * random_get_entropy_fallback - Returns the raw clock source value,
+ * used by random.c for platforms with no valid random_get_entropy().
+ */
+unsigned long random_get_entropy_fallback(void)
+{
+ struct tk_read_base *tkr = &tk_core.timekeeper.tkr_mono;
+ struct clocksource *clock = READ_ONCE(tkr->clock);
+
+ if (unlikely(timekeeping_suspended || !clock))
+ return 0;
+ return clock->read(clock);
+}
+EXPORT_SYMBOL_GPL(random_get_entropy_fallback);
/**
* do_adjtimex() - Accessor function to NTP __do_adjtimex function