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authorLinus Torvalds <torvalds@linux-foundation.org>2017-06-25 11:59:19 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-06-25 11:59:19 -0700
commit5f4b37d8784da4217ede8f8bcd301686853dcf8c (patch)
tree0ce7799c0133a4707628b128473f22db89ff7502
parent35d8d5d47c0ef066197f629f71cdd6039693b86d (diff)
parent8e6cec1c7c5afa489687c90be15d6ed82c742975 (diff)
downloadlinux-stericsson-5f4b37d8784da4217ede8f8bcd301686853dcf8c.tar.gz
Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer fixes from Thomas Gleixner: "A few fixes for timekeeping and timers: - Plug a subtle race due to a missing READ_ONCE() in the timekeeping code where reloading of a pointer results in an inconsistent callback argument being supplied to the clocksource->read function. - Correct the CLOCK_MONOTONIC_RAW sub-nanosecond accounting in the time keeping core code, to prevent a possible discontuity. - Apply a similar fix to the arm64 vdso clock_gettime() implementation - Add missing includes to clocksource drivers, which relied on indirect includes which fails in certain configs. - Use the proper iomem pointer for read/iounmap in a probe function" * 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: arm64/vdso: Fix nsec handling for CLOCK_MONOTONIC_RAW time: Fix CLOCK_MONOTONIC_RAW sub-nanosecond accounting time: Fix clock->read(clock) race around clocksource changes clocksource: Explicitly include linux/clocksource.h when needed clocksource/drivers/arm_arch_timer: Fix read and iounmap of incorrect variable
-rw-r--r--arch/arm64/kernel/vdso.c5
-rw-r--r--arch/arm64/kernel/vdso/gettimeofday.S1
-rw-r--r--drivers/clocksource/arm_arch_timer.c4
-rw-r--r--drivers/clocksource/cadence_ttc_timer.c1
-rw-r--r--drivers/clocksource/timer-sun5i.c1
-rw-r--r--include/linux/timekeeper_internal.h5
-rw-r--r--kernel/time/timekeeping.c71
7 files changed, 55 insertions, 33 deletions
diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index 41b6e31f8f55..d0cb007fa482 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -221,10 +221,11 @@ void update_vsyscall(struct timekeeper *tk)
/* tkr_mono.cycle_last == tkr_raw.cycle_last */
vdso_data->cs_cycle_last = tk->tkr_mono.cycle_last;
vdso_data->raw_time_sec = tk->raw_time.tv_sec;
- vdso_data->raw_time_nsec = tk->raw_time.tv_nsec;
+ vdso_data->raw_time_nsec = (tk->raw_time.tv_nsec <<
+ tk->tkr_raw.shift) +
+ tk->tkr_raw.xtime_nsec;
vdso_data->xtime_clock_sec = tk->xtime_sec;
vdso_data->xtime_clock_nsec = tk->tkr_mono.xtime_nsec;
- /* tkr_raw.xtime_nsec == 0 */
vdso_data->cs_mono_mult = tk->tkr_mono.mult;
vdso_data->cs_raw_mult = tk->tkr_raw.mult;
/* tkr_mono.shift == tkr_raw.shift */
diff --git a/arch/arm64/kernel/vdso/gettimeofday.S b/arch/arm64/kernel/vdso/gettimeofday.S
index e00b4671bd7c..76320e920965 100644
--- a/arch/arm64/kernel/vdso/gettimeofday.S
+++ b/arch/arm64/kernel/vdso/gettimeofday.S
@@ -256,7 +256,6 @@ monotonic_raw:
seqcnt_check fail=monotonic_raw
/* All computations are done with left-shifted nsecs. */
- lsl x14, x14, x12
get_nsec_per_sec res=x9
lsl x9, x9, x12
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 4bed671e490e..8b5c30062d99 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -1209,9 +1209,9 @@ arch_timer_mem_frame_get_cntfrq(struct arch_timer_mem_frame *frame)
return 0;
}
- rate = readl_relaxed(frame + CNTFRQ);
+ rate = readl_relaxed(base + CNTFRQ);
- iounmap(frame);
+ iounmap(base);
return rate;
}
diff --git a/drivers/clocksource/cadence_ttc_timer.c b/drivers/clocksource/cadence_ttc_timer.c
index 44e5e951583b..8e64b8460f11 100644
--- a/drivers/clocksource/cadence_ttc_timer.c
+++ b/drivers/clocksource/cadence_ttc_timer.c
@@ -18,6 +18,7 @@
#include <linux/clk.h>
#include <linux/interrupt.h>
#include <linux/clockchips.h>
+#include <linux/clocksource.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/slab.h>
diff --git a/drivers/clocksource/timer-sun5i.c b/drivers/clocksource/timer-sun5i.c
index 2e9c830ae1cd..c4656c4d44a6 100644
--- a/drivers/clocksource/timer-sun5i.c
+++ b/drivers/clocksource/timer-sun5i.c
@@ -12,6 +12,7 @@
#include <linux/clk.h>
#include <linux/clockchips.h>
+#include <linux/clocksource.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
diff --git a/include/linux/timekeeper_internal.h b/include/linux/timekeeper_internal.h
index 110f4532188c..f7043ccca81c 100644
--- a/include/linux/timekeeper_internal.h
+++ b/include/linux/timekeeper_internal.h
@@ -29,7 +29,6 @@
*/
struct tk_read_base {
struct clocksource *clock;
- u64 (*read)(struct clocksource *cs);
u64 mask;
u64 cycle_last;
u32 mult;
@@ -58,7 +57,7 @@ struct tk_read_base {
* interval.
* @xtime_remainder: Shifted nano seconds left over when rounding
* @cycle_interval
- * @raw_interval: Raw nano seconds accumulated per NTP interval.
+ * @raw_interval: Shifted raw nano seconds accumulated per NTP interval.
* @ntp_error: Difference between accumulated time and NTP time in ntp
* shifted nano seconds.
* @ntp_error_shift: Shift conversion between clock shifted nano seconds and
@@ -100,7 +99,7 @@ struct timekeeper {
u64 cycle_interval;
u64 xtime_interval;
s64 xtime_remainder;
- u32 raw_interval;
+ u64 raw_interval;
/* The ntp_tick_length() value currently being used.
* This cached copy ensures we consistently apply the tick
* length for an entire tick, as ntp_tick_length may change
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 9652bc57fd09..b602c48cb841 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -118,6 +118,26 @@ 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 +195,7 @@ 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 +229,7 @@ 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 +258,10 @@ 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;
@@ -262,7 +280,7 @@ 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) {
@@ -404,7 +422,7 @@ 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 +479,10 @@ 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.
@@ -477,13 +499,13 @@ 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);
}
@@ -649,11 +671,10 @@ 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;
@@ -929,8 +950,7 @@ 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 +1128,7 @@ 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;
@@ -1629,7 +1649,7 @@ 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 +1996,7 @@ 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 +2011,15 @@ 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 += (u64)tk->raw_time.tv_nsec << tk->tkr_raw.shift;
+ 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_time.tv_sec++;
}
- tk->raw_time.tv_nsec = raw_nsecs;
+ tk->raw_time.tv_nsec = tk->tkr_raw.xtime_nsec >> tk->tkr_raw.shift;
+ tk->tkr_raw.xtime_nsec -= (u64)tk->raw_time.tv_nsec << tk->tkr_raw.shift;
/* Accumulate error between NTP and clock interval */
tk->ntp_error += tk->ntp_tick << shift;
@@ -2030,7 +2051,7 @@ 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