diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/time/timekeeping.c | 68 |
1 files changed, 63 insertions, 5 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 2dc0646258ae..6a931852082f 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -417,7 +417,8 @@ EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier); */ static inline void tk_update_ktime_data(struct timekeeper *tk) { - s64 nsec; + u64 seconds; + u32 nsec; /* * The xtime based monotonic readout is: @@ -426,13 +427,22 @@ static inline void tk_update_ktime_data(struct timekeeper *tk) * nsec = base_mono + now(); * ==> base_mono = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec */ - nsec = (s64)(tk->xtime_sec + tk->wall_to_monotonic.tv_sec); - nsec *= NSEC_PER_SEC; - nsec += tk->wall_to_monotonic.tv_nsec; - tk->tkr.base_mono = ns_to_ktime(nsec); + seconds = (u64)(tk->xtime_sec + tk->wall_to_monotonic.tv_sec); + nsec = (u32) tk->wall_to_monotonic.tv_nsec; + tk->tkr.base_mono = ns_to_ktime(seconds * NSEC_PER_SEC + nsec); /* Update the monotonic raw base */ tk->base_raw = timespec64_to_ktime(tk->raw_time); + + /* + * 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.xtime_nsec >> tk->tkr.shift); + if (nsec >= NSEC_PER_SEC) + seconds++; + tk->ktime_sec = seconds; } /* must hold timekeeper_lock */ @@ -648,6 +658,54 @@ void ktime_get_ts64(struct timespec64 *ts) } 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. This replaces the + * get_seconds() interface which is not y2038 safe on 32bit systems. + * + * 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); + #ifdef CONFIG_NTP_PPS /** |