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-rw-r--r--kernel/time/timekeeping.c109
1 files changed, 68 insertions, 41 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 9652bc57fd09..cedafa008de5 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -72,6 +72,10 @@ static inline void tk_normalize_xtime(struct timekeeper *tk)
tk->tkr_mono.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_mono.shift;
tk->xtime_sec++;
}
+ while (tk->tkr_raw.xtime_nsec >= ((u64)NSEC_PER_SEC << tk->tkr_raw.shift)) {
+ tk->tkr_raw.xtime_nsec -= (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
+ tk->raw_sec++;
+ }
}
static inline struct timespec64 tk_xtime(struct timekeeper *tk)
@@ -118,6 +122,26 @@ static inline void tk_update_sleep_time(struct timekeeper *tk, ktime_t delta)
tk->offs_boot = ktime_add(tk->offs_boot, delta);
}
+/*
+ * tk_clock_read - atomic clocksource read() helper
+ *
+ * This helper is necessary to use in the read paths because, while the
+ * seqlock ensures we don't return a bad value while structures are updated,
+ * it doesn't protect from potential crashes. There is the possibility that
+ * the tkr's clocksource may change between the read reference, and the
+ * clock reference passed to the read function. This can cause crashes if
+ * the wrong clocksource is passed to the wrong read function.
+ * This isn't necessary to use when holding the timekeeper_lock or doing
+ * a read of the fast-timekeeper tkrs (which is protected by its own locking
+ * and update logic).
+ */
+static inline u64 tk_clock_read(struct tk_read_base *tkr)
+{
+ struct clocksource *clock = READ_ONCE(tkr->clock);
+
+ return clock->read(clock);
+}
+
#ifdef CONFIG_DEBUG_TIMEKEEPING
#define WARNING_FREQ (HZ*300) /* 5 minute rate-limiting */
@@ -175,7 +199,7 @@ static inline u64 timekeeping_get_delta(struct tk_read_base *tkr)
*/
do {
seq = read_seqcount_begin(&tk_core.seq);
- now = tkr->read(tkr->clock);
+ now = tk_clock_read(tkr);
last = tkr->cycle_last;
mask = tkr->mask;
max = tkr->clock->max_cycles;
@@ -209,7 +233,7 @@ static inline u64 timekeeping_get_delta(struct tk_read_base *tkr)
u64 cycle_now, delta;
/* read clocksource */
- cycle_now = tkr->read(tkr->clock);
+ cycle_now = tk_clock_read(tkr);
/* calculate the delta since the last update_wall_time */
delta = clocksource_delta(cycle_now, tkr->cycle_last, tkr->mask);
@@ -238,12 +262,10 @@ static void tk_setup_internals(struct timekeeper *tk, struct clocksource *clock)
++tk->cs_was_changed_seq;
old_clock = tk->tkr_mono.clock;
tk->tkr_mono.clock = clock;
- tk->tkr_mono.read = clock->read;
tk->tkr_mono.mask = clock->mask;
- tk->tkr_mono.cycle_last = tk->tkr_mono.read(clock);
+ tk->tkr_mono.cycle_last = tk_clock_read(&tk->tkr_mono);
tk->tkr_raw.clock = clock;
- tk->tkr_raw.read = clock->read;
tk->tkr_raw.mask = clock->mask;
tk->tkr_raw.cycle_last = tk->tkr_mono.cycle_last;
@@ -262,17 +284,19 @@ static void tk_setup_internals(struct timekeeper *tk, struct clocksource *clock)
/* Go back from cycles -> shifted ns */
tk->xtime_interval = interval * clock->mult;
tk->xtime_remainder = ntpinterval - tk->xtime_interval;
- tk->raw_interval = (interval * clock->mult) >> clock->shift;
+ tk->raw_interval = interval * clock->mult;
/* if changing clocks, convert xtime_nsec shift units */
if (old_clock) {
int shift_change = clock->shift - old_clock->shift;
- if (shift_change < 0)
+ if (shift_change < 0) {
tk->tkr_mono.xtime_nsec >>= -shift_change;
- else
+ tk->tkr_raw.xtime_nsec >>= -shift_change;
+ } else {
tk->tkr_mono.xtime_nsec <<= shift_change;
+ tk->tkr_raw.xtime_nsec <<= shift_change;
+ }
}
- tk->tkr_raw.xtime_nsec = 0;
tk->tkr_mono.shift = clock->shift;
tk->tkr_raw.shift = clock->shift;
@@ -404,7 +428,7 @@ static __always_inline u64 __ktime_get_fast_ns(struct tk_fast *tkf)
now += timekeeping_delta_to_ns(tkr,
clocksource_delta(
- tkr->read(tkr->clock),
+ tk_clock_read(tkr),
tkr->cycle_last,
tkr->mask));
} while (read_seqcount_retry(&tkf->seq, seq));
@@ -461,6 +485,10 @@ static u64 dummy_clock_read(struct clocksource *cs)
return cycles_at_suspend;
}
+static struct clocksource dummy_clock = {
+ .read = dummy_clock_read,
+};
+
/**
* halt_fast_timekeeper - Prevent fast timekeeper from accessing clocksource.
* @tk: Timekeeper to snapshot.
@@ -477,17 +505,18 @@ static void halt_fast_timekeeper(struct timekeeper *tk)
struct tk_read_base *tkr = &tk->tkr_mono;
memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
- cycles_at_suspend = tkr->read(tkr->clock);
- tkr_dummy.read = dummy_clock_read;
+ cycles_at_suspend = tk_clock_read(tkr);
+ tkr_dummy.clock = &dummy_clock;
update_fast_timekeeper(&tkr_dummy, &tk_fast_mono);
tkr = &tk->tkr_raw;
memcpy(&tkr_dummy, tkr, sizeof(tkr_dummy));
- tkr_dummy.read = dummy_clock_read;
+ tkr_dummy.clock = &dummy_clock;
update_fast_timekeeper(&tkr_dummy, &tk_fast_raw);
}
#ifdef CONFIG_GENERIC_TIME_VSYSCALL_OLD
+#warning Please contact your maintainers, as GENERIC_TIME_VSYSCALL_OLD compatibity will disappear soon.
static inline void update_vsyscall(struct timekeeper *tk)
{
@@ -597,9 +626,6 @@ static inline void tk_update_ktime_data(struct timekeeper *tk)
nsec = (u32) tk->wall_to_monotonic.tv_nsec;
tk->tkr_mono.base = ns_to_ktime(seconds * NSEC_PER_SEC + nsec);
- /* Update the monotonic raw base */
- tk->tkr_raw.base = 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
@@ -609,6 +635,11 @@ static inline void tk_update_ktime_data(struct timekeeper *tk)
if (nsec >= NSEC_PER_SEC)
seconds++;
tk->ktime_sec = seconds;
+
+ /* Update the monotonic raw base */
+ seconds = tk->raw_sec;
+ nsec = (u32)(tk->tkr_raw.xtime_nsec >> tk->tkr_raw.shift);
+ tk->tkr_raw.base = ns_to_ktime(seconds * NSEC_PER_SEC + nsec);
}
/* must hold timekeeper_lock */
@@ -649,11 +680,9 @@ static void timekeeping_update(struct timekeeper *tk, unsigned int action)
*/
static void timekeeping_forward_now(struct timekeeper *tk)
{
- struct clocksource *clock = tk->tkr_mono.clock;
u64 cycle_now, delta;
- u64 nsec;
- cycle_now = tk->tkr_mono.read(clock);
+ cycle_now = tk_clock_read(&tk->tkr_mono);
delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
tk->tkr_mono.cycle_last = cycle_now;
tk->tkr_raw.cycle_last = cycle_now;
@@ -663,10 +692,13 @@ static void timekeeping_forward_now(struct timekeeper *tk)
/* If arch requires, add in get_arch_timeoffset() */
tk->tkr_mono.xtime_nsec += (u64)arch_gettimeoffset() << tk->tkr_mono.shift;
- tk_normalize_xtime(tk);
- nsec = clocksource_cyc2ns(delta, tk->tkr_raw.mult, tk->tkr_raw.shift);
- timespec64_add_ns(&tk->raw_time, nsec);
+ tk->tkr_raw.xtime_nsec += delta * tk->tkr_raw.mult;
+
+ /* If arch requires, add in get_arch_timeoffset() */
+ tk->tkr_raw.xtime_nsec += (u64)arch_gettimeoffset() << tk->tkr_raw.shift;
+
+ tk_normalize_xtime(tk);
}
/**
@@ -929,8 +961,7 @@ void ktime_get_snapshot(struct system_time_snapshot *systime_snapshot)
do {
seq = read_seqcount_begin(&tk_core.seq);
-
- now = tk->tkr_mono.read(tk->tkr_mono.clock);
+ now = tk_clock_read(&tk->tkr_mono);
systime_snapshot->cs_was_changed_seq = tk->cs_was_changed_seq;
systime_snapshot->clock_was_set_seq = tk->clock_was_set_seq;
base_real = ktime_add(tk->tkr_mono.base,
@@ -1108,7 +1139,7 @@ int get_device_system_crosststamp(int (*get_time_fn)
* Check whether the system counter value provided by the
* device driver is on the current timekeeping interval.
*/
- now = tk->tkr_mono.read(tk->tkr_mono.clock);
+ now = tk_clock_read(&tk->tkr_mono);
interval_start = tk->tkr_mono.cycle_last;
if (!cycle_between(interval_start, cycles, now)) {
clock_was_set_seq = tk->clock_was_set_seq;
@@ -1353,19 +1384,18 @@ int timekeeping_notify(struct clocksource *clock)
void getrawmonotonic64(struct timespec64 *ts)
{
struct timekeeper *tk = &tk_core.timekeeper;
- struct timespec64 ts64;
unsigned long seq;
u64 nsecs;
do {
seq = read_seqcount_begin(&tk_core.seq);
+ ts->tv_sec = tk->raw_sec;
nsecs = timekeeping_get_ns(&tk->tkr_raw);
- ts64 = tk->raw_time;
} while (read_seqcount_retry(&tk_core.seq, seq));
- timespec64_add_ns(&ts64, nsecs);
- *ts = ts64;
+ ts->tv_nsec = 0;
+ timespec64_add_ns(ts, nsecs);
}
EXPORT_SYMBOL(getrawmonotonic64);
@@ -1489,8 +1519,7 @@ void __init timekeeping_init(void)
tk_setup_internals(tk, clock);
tk_set_xtime(tk, &now);
- tk->raw_time.tv_sec = 0;
- tk->raw_time.tv_nsec = 0;
+ tk->raw_sec = 0;
if (boot.tv_sec == 0 && boot.tv_nsec == 0)
boot = tk_xtime(tk);
@@ -1629,7 +1658,7 @@ void timekeeping_resume(void)
* The less preferred source will only be tried if there is no better
* usable source. The rtc part is handled separately in rtc core code.
*/
- cycle_now = tk->tkr_mono.read(clock);
+ cycle_now = tk_clock_read(&tk->tkr_mono);
if ((clock->flags & CLOCK_SOURCE_SUSPEND_NONSTOP) &&
cycle_now > tk->tkr_mono.cycle_last) {
u64 nsec, cyc_delta;
@@ -1976,7 +2005,7 @@ static u64 logarithmic_accumulation(struct timekeeper *tk, u64 offset,
u32 shift, unsigned int *clock_set)
{
u64 interval = tk->cycle_interval << shift;
- u64 raw_nsecs;
+ u64 snsec_per_sec;
/* If the offset is smaller than a shifted interval, do nothing */
if (offset < interval)
@@ -1991,14 +2020,12 @@ static u64 logarithmic_accumulation(struct timekeeper *tk, u64 offset,
*clock_set |= accumulate_nsecs_to_secs(tk);
/* Accumulate raw time */
- raw_nsecs = (u64)tk->raw_interval << shift;
- raw_nsecs += tk->raw_time.tv_nsec;
- if (raw_nsecs >= NSEC_PER_SEC) {
- u64 raw_secs = raw_nsecs;
- raw_nsecs = do_div(raw_secs, NSEC_PER_SEC);
- tk->raw_time.tv_sec += raw_secs;
+ tk->tkr_raw.xtime_nsec += tk->raw_interval << shift;
+ snsec_per_sec = (u64)NSEC_PER_SEC << tk->tkr_raw.shift;
+ while (tk->tkr_raw.xtime_nsec >= snsec_per_sec) {
+ tk->tkr_raw.xtime_nsec -= snsec_per_sec;
+ tk->raw_sec++;
}
- tk->raw_time.tv_nsec = raw_nsecs;
/* Accumulate error between NTP and clock interval */
tk->ntp_error += tk->ntp_tick << shift;
@@ -2030,7 +2057,7 @@ void update_wall_time(void)
#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
offset = real_tk->cycle_interval;
#else
- offset = clocksource_delta(tk->tkr_mono.read(tk->tkr_mono.clock),
+ offset = clocksource_delta(tk_clock_read(&tk->tkr_mono),
tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
#endif