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-rw-r--r--arch/arm/plat-omap/counter_32k.c2
-rw-r--r--arch/s390/kernel/time.c2
-rw-r--r--arch/sparc/kernel/time_32.c6
-rw-r--r--drivers/clocksource/em_sti.c2
-rw-r--r--drivers/clocksource/sh_cmt.c2
-rw-r--r--drivers/clocksource/sh_tmu.c2
-rw-r--r--include/linux/clockchips.h21
-rw-r--r--include/linux/clocksource.h25
-rw-r--r--kernel/time/clockevents.c88
-rw-r--r--kernel/time/clocksource.c170
-rw-r--r--kernel/time/jiffies.c5
-rw-r--r--kernel/time/sched_clock.c6
-rw-r--r--kernel/time/timekeeping.c130
-rw-r--r--kernel/time/timer_list.c32
-rw-r--r--lib/Kconfig.debug13
15 files changed, 371 insertions, 135 deletions
diff --git a/arch/arm/plat-omap/counter_32k.c b/arch/arm/plat-omap/counter_32k.c
index 61b4d705c267..43cf74561cfd 100644
--- a/arch/arm/plat-omap/counter_32k.c
+++ b/arch/arm/plat-omap/counter_32k.c
@@ -103,7 +103,7 @@ int __init omap_init_clocksource_32k(void __iomem *vbase)
/*
* 120000 rough estimate from the calculations in
- * __clocksource_updatefreq_scale.
+ * __clocksource_update_freq_scale.
*/
clocks_calc_mult_shift(&persistent_mult, &persistent_shift,
32768, NSEC_PER_SEC, 120000);
diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index 20660dddb2d6..6c273cd815bb 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -283,7 +283,7 @@ void __init time_init(void)
if (register_external_irq(EXT_IRQ_TIMING_ALERT, timing_alert_interrupt))
panic("Couldn't request external interrupt 0x1406");
- if (clocksource_register(&clocksource_tod) != 0)
+ if (__clocksource_register(&clocksource_tod) != 0)
panic("Could not register TOD clock source");
/* Enable TOD clock interrupts on the boot cpu. */
diff --git a/arch/sparc/kernel/time_32.c b/arch/sparc/kernel/time_32.c
index 2f80d23a0a44..18147a5523d9 100644
--- a/arch/sparc/kernel/time_32.c
+++ b/arch/sparc/kernel/time_32.c
@@ -181,17 +181,13 @@ static struct clocksource timer_cs = {
.rating = 100,
.read = timer_cs_read,
.mask = CLOCKSOURCE_MASK(64),
- .shift = 2,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
static __init int setup_timer_cs(void)
{
timer_cs_enabled = 1;
- timer_cs.mult = clocksource_hz2mult(sparc_config.clock_rate,
- timer_cs.shift);
-
- return clocksource_register(&timer_cs);
+ return clocksource_register_hz(&timer_cs, sparc_config.clock_rate);
}
#ifdef CONFIG_SMP
diff --git a/drivers/clocksource/em_sti.c b/drivers/clocksource/em_sti.c
index d0a7bd66b8b9..dc3c6ee04aaa 100644
--- a/drivers/clocksource/em_sti.c
+++ b/drivers/clocksource/em_sti.c
@@ -210,7 +210,7 @@ static int em_sti_clocksource_enable(struct clocksource *cs)
ret = em_sti_start(p, USER_CLOCKSOURCE);
if (!ret)
- __clocksource_updatefreq_hz(cs, p->rate);
+ __clocksource_update_freq_hz(cs, p->rate);
return ret;
}
diff --git a/drivers/clocksource/sh_cmt.c b/drivers/clocksource/sh_cmt.c
index 2bd13b53b727..b8ff3c64cc45 100644
--- a/drivers/clocksource/sh_cmt.c
+++ b/drivers/clocksource/sh_cmt.c
@@ -641,7 +641,7 @@ static int sh_cmt_clocksource_enable(struct clocksource *cs)
ret = sh_cmt_start(ch, FLAG_CLOCKSOURCE);
if (!ret) {
- __clocksource_updatefreq_hz(cs, ch->rate);
+ __clocksource_update_freq_hz(cs, ch->rate);
ch->cs_enabled = true;
}
return ret;
diff --git a/drivers/clocksource/sh_tmu.c b/drivers/clocksource/sh_tmu.c
index f150ca82bfaf..b6b8fa3cd211 100644
--- a/drivers/clocksource/sh_tmu.c
+++ b/drivers/clocksource/sh_tmu.c
@@ -272,7 +272,7 @@ static int sh_tmu_clocksource_enable(struct clocksource *cs)
ret = sh_tmu_enable(ch);
if (!ret) {
- __clocksource_updatefreq_hz(cs, ch->rate);
+ __clocksource_update_freq_hz(cs, ch->rate);
ch->cs_enabled = true;
}
diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h
index 2e4cb67f6e56..59af26b54d15 100644
--- a/include/linux/clockchips.h
+++ b/include/linux/clockchips.h
@@ -39,6 +39,8 @@ enum clock_event_mode {
CLOCK_EVT_MODE_PERIODIC,
CLOCK_EVT_MODE_ONESHOT,
CLOCK_EVT_MODE_RESUME,
+
+ /* Legacy ->set_mode() callback doesn't support below modes */
};
/*
@@ -81,7 +83,11 @@ enum clock_event_mode {
* @mode: operating mode assigned by the management code
* @features: features
* @retries: number of forced programming retries
- * @set_mode: set mode function
+ * @set_mode: legacy set mode function, only for modes <= CLOCK_EVT_MODE_RESUME.
+ * @set_mode_periodic: switch mode to periodic, if !set_mode
+ * @set_mode_oneshot: switch mode to oneshot, if !set_mode
+ * @set_mode_shutdown: switch mode to shutdown, if !set_mode
+ * @set_mode_resume: resume clkevt device, if !set_mode
* @broadcast: function to broadcast events
* @min_delta_ticks: minimum delta value in ticks stored for reconfiguration
* @max_delta_ticks: maximum delta value in ticks stored for reconfiguration
@@ -108,9 +114,20 @@ struct clock_event_device {
unsigned int features;
unsigned long retries;
- void (*broadcast)(const struct cpumask *mask);
+ /*
+ * Mode transition callback(s): Only one of the two groups should be
+ * defined:
+ * - set_mode(), only for modes <= CLOCK_EVT_MODE_RESUME.
+ * - set_mode_{shutdown|periodic|oneshot|resume}().
+ */
void (*set_mode)(enum clock_event_mode mode,
struct clock_event_device *);
+ int (*set_mode_periodic)(struct clock_event_device *);
+ int (*set_mode_oneshot)(struct clock_event_device *);
+ int (*set_mode_shutdown)(struct clock_event_device *);
+ int (*set_mode_resume)(struct clock_event_device *);
+
+ void (*broadcast)(const struct cpumask *mask);
void (*suspend)(struct clock_event_device *);
void (*resume)(struct clock_event_device *);
unsigned long min_delta_ticks;
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index 9c78d15d33e4..135509821c39 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -56,6 +56,7 @@ struct module;
* @shift: cycle to nanosecond divisor (power of two)
* @max_idle_ns: max idle time permitted by the clocksource (nsecs)
* @maxadj: maximum adjustment value to mult (~11%)
+ * @max_cycles: maximum safe cycle value which won't overflow on multiplication
* @flags: flags describing special properties
* @archdata: arch-specific data
* @suspend: suspend function for the clocksource, if necessary
@@ -76,7 +77,7 @@ struct clocksource {
#ifdef CONFIG_ARCH_CLOCKSOURCE_DATA
struct arch_clocksource_data archdata;
#endif
-
+ u64 max_cycles;
const char *name;
struct list_head list;
int rating;
@@ -178,7 +179,6 @@ static inline s64 clocksource_cyc2ns(cycle_t cycles, u32 mult, u32 shift)
}
-extern int clocksource_register(struct clocksource*);
extern int clocksource_unregister(struct clocksource*);
extern void clocksource_touch_watchdog(void);
extern struct clocksource* clocksource_get_next(void);
@@ -189,7 +189,7 @@ extern struct clocksource * __init clocksource_default_clock(void);
extern void clocksource_mark_unstable(struct clocksource *cs);
extern u64
-clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask);
+clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cycles);
extern void
clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec);
@@ -200,7 +200,16 @@ clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec);
extern int
__clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq);
extern void
-__clocksource_updatefreq_scale(struct clocksource *cs, u32 scale, u32 freq);
+__clocksource_update_freq_scale(struct clocksource *cs, u32 scale, u32 freq);
+
+/*
+ * Don't call this unless you are a default clocksource
+ * (AKA: jiffies) and absolutely have to.
+ */
+static inline int __clocksource_register(struct clocksource *cs)
+{
+ return __clocksource_register_scale(cs, 1, 0);
+}
static inline int clocksource_register_hz(struct clocksource *cs, u32 hz)
{
@@ -212,14 +221,14 @@ static inline int clocksource_register_khz(struct clocksource *cs, u32 khz)
return __clocksource_register_scale(cs, 1000, khz);
}
-static inline void __clocksource_updatefreq_hz(struct clocksource *cs, u32 hz)
+static inline void __clocksource_update_freq_hz(struct clocksource *cs, u32 hz)
{
- __clocksource_updatefreq_scale(cs, 1, hz);
+ __clocksource_update_freq_scale(cs, 1, hz);
}
-static inline void __clocksource_updatefreq_khz(struct clocksource *cs, u32 khz)
+static inline void __clocksource_update_freq_khz(struct clocksource *cs, u32 khz)
{
- __clocksource_updatefreq_scale(cs, 1000, khz);
+ __clocksource_update_freq_scale(cs, 1000, khz);
}
diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index 55449909f114..489642b08d64 100644
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -94,6 +94,57 @@ u64 clockevent_delta2ns(unsigned long latch, struct clock_event_device *evt)
}
EXPORT_SYMBOL_GPL(clockevent_delta2ns);
+static int __clockevents_set_mode(struct clock_event_device *dev,
+ enum clock_event_mode mode)
+{
+ /* Transition with legacy set_mode() callback */
+ if (dev->set_mode) {
+ /* Legacy callback doesn't support new modes */
+ if (mode > CLOCK_EVT_MODE_RESUME)
+ return -ENOSYS;
+ dev->set_mode(mode, dev);
+ return 0;
+ }
+
+ if (dev->features & CLOCK_EVT_FEAT_DUMMY)
+ return 0;
+
+ /* Transition with new mode-specific callbacks */
+ switch (mode) {
+ case CLOCK_EVT_MODE_UNUSED:
+ /*
+ * This is an internal state, which is guaranteed to go from
+ * SHUTDOWN to UNUSED. No driver interaction required.
+ */
+ return 0;
+
+ case CLOCK_EVT_MODE_SHUTDOWN:
+ return dev->set_mode_shutdown(dev);
+
+ case CLOCK_EVT_MODE_PERIODIC:
+ /* Core internal bug */
+ if (!(dev->features & CLOCK_EVT_FEAT_PERIODIC))
+ return -ENOSYS;
+ return dev->set_mode_periodic(dev);
+
+ case CLOCK_EVT_MODE_ONESHOT:
+ /* Core internal bug */
+ if (!(dev->features & CLOCK_EVT_FEAT_ONESHOT))
+ return -ENOSYS;
+ return dev->set_mode_oneshot(dev);
+
+ case CLOCK_EVT_MODE_RESUME:
+ /* Optional callback */
+ if (dev->set_mode_resume)
+ return dev->set_mode_resume(dev);
+ else
+ return 0;
+
+ default:
+ return -ENOSYS;
+ }
+}
+
/**
* clockevents_set_mode - set the operating mode of a clock event device
* @dev: device to modify
@@ -105,7 +156,9 @@ void clockevents_set_mode(struct clock_event_device *dev,
enum clock_event_mode mode)
{
if (dev->mode != mode) {
- dev->set_mode(mode, dev);
+ if (__clockevents_set_mode(dev, mode))
+ return;
+
dev->mode = mode;
/*
@@ -373,6 +426,35 @@ int clockevents_unbind_device(struct clock_event_device *ced, int cpu)
}
EXPORT_SYMBOL_GPL(clockevents_unbind);
+/* Sanity check of mode transition callbacks */
+static int clockevents_sanity_check(struct clock_event_device *dev)
+{
+ /* Legacy set_mode() callback */
+ if (dev->set_mode) {
+ /* We shouldn't be supporting new modes now */
+ WARN_ON(dev->set_mode_periodic || dev->set_mode_oneshot ||
+ dev->set_mode_shutdown || dev->set_mode_resume);
+ return 0;
+ }
+
+ if (dev->features & CLOCK_EVT_FEAT_DUMMY)
+ return 0;
+
+ /* New mode-specific callbacks */
+ if (!dev->set_mode_shutdown)
+ return -EINVAL;
+
+ if ((dev->features & CLOCK_EVT_FEAT_PERIODIC) &&
+ !dev->set_mode_periodic)
+ return -EINVAL;
+
+ if ((dev->features & CLOCK_EVT_FEAT_ONESHOT) &&
+ !dev->set_mode_oneshot)
+ return -EINVAL;
+
+ return 0;
+}
+
/**
* clockevents_register_device - register a clock event device
* @dev: device to register
@@ -382,6 +464,8 @@ void clockevents_register_device(struct clock_event_device *dev)
unsigned long flags;
BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED);
+ BUG_ON(clockevents_sanity_check(dev));
+
if (!dev->cpumask) {
WARN_ON(num_possible_cpus() > 1);
dev->cpumask = cpumask_of(smp_processor_id());
@@ -449,7 +533,7 @@ int __clockevents_update_freq(struct clock_event_device *dev, u32 freq)
return clockevents_program_event(dev, dev->next_event, false);
if (dev->mode == CLOCK_EVT_MODE_PERIODIC)
- dev->set_mode(CLOCK_EVT_MODE_PERIODIC, dev);
+ return __clockevents_set_mode(dev, CLOCK_EVT_MODE_PERIODIC);
return 0;
}
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 4892352f0e49..c3be3c71bbad 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -142,13 +142,6 @@ static void __clocksource_unstable(struct clocksource *cs)
schedule_work(&watchdog_work);
}
-static void clocksource_unstable(struct clocksource *cs, int64_t delta)
-{
- printk(KERN_WARNING "Clocksource %s unstable (delta = %Ld ns)\n",
- cs->name, delta);
- __clocksource_unstable(cs);
-}
-
/**
* clocksource_mark_unstable - mark clocksource unstable via watchdog
* @cs: clocksource to be marked unstable
@@ -174,7 +167,7 @@ void clocksource_mark_unstable(struct clocksource *cs)
static void clocksource_watchdog(unsigned long data)
{
struct clocksource *cs;
- cycle_t csnow, wdnow, delta;
+ cycle_t csnow, wdnow, cslast, wdlast, delta;
int64_t wd_nsec, cs_nsec;
int next_cpu, reset_pending;
@@ -213,6 +206,8 @@ static void clocksource_watchdog(unsigned long data)
delta = clocksource_delta(csnow, cs->cs_last, cs->mask);
cs_nsec = clocksource_cyc2ns(delta, cs->mult, cs->shift);
+ wdlast = cs->wd_last; /* save these in case we print them */
+ cslast = cs->cs_last;
cs->cs_last = csnow;
cs->wd_last = wdnow;
@@ -221,7 +216,12 @@ static void clocksource_watchdog(unsigned long data)
/* Check the deviation from the watchdog clocksource. */
if ((abs(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD)) {
- clocksource_unstable(cs, cs_nsec - wd_nsec);
+ pr_warn("timekeeping watchdog: Marking clocksource '%s' as unstable, because the skew is too large:\n", cs->name);
+ pr_warn(" '%s' wd_now: %llx wd_last: %llx mask: %llx\n",
+ watchdog->name, wdnow, wdlast, watchdog->mask);
+ pr_warn(" '%s' cs_now: %llx cs_last: %llx mask: %llx\n",
+ cs->name, csnow, cslast, cs->mask);
+ __clocksource_unstable(cs);
continue;
}
@@ -469,26 +469,22 @@ static u32 clocksource_max_adjustment(struct clocksource *cs)
* @shift: cycle to nanosecond divisor (power of two)
* @maxadj: maximum adjustment value to mult (~11%)
* @mask: bitmask for two's complement subtraction of non 64 bit counters
+ * @max_cyc: maximum cycle value before potential overflow (does not include
+ * any safety margin)
+ *
+ * NOTE: This function includes a safety margin of 50%, so that bad clock values
+ * can be detected.
*/
-u64 clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask)
+u64 clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cyc)
{
u64 max_nsecs, max_cycles;
/*
* Calculate the maximum number of cycles that we can pass to the
- * cyc2ns function without overflowing a 64-bit signed result. The
- * maximum number of cycles is equal to ULLONG_MAX/(mult+maxadj)
- * which is equivalent to the below.
- * max_cycles < (2^63)/(mult + maxadj)
- * max_cycles < 2^(log2((2^63)/(mult + maxadj)))
- * max_cycles < 2^(log2(2^63) - log2(mult + maxadj))
- * max_cycles < 2^(63 - log2(mult + maxadj))
- * max_cycles < 1 << (63 - log2(mult + maxadj))
- * Please note that we add 1 to the result of the log2 to account for
- * any rounding errors, ensure the above inequality is satisfied and
- * no overflow will occur.
+ * cyc2ns() function without overflowing a 64-bit result.
*/
- max_cycles = 1ULL << (63 - (ilog2(mult + maxadj) + 1));
+ max_cycles = ULLONG_MAX;
+ do_div(max_cycles, mult+maxadj);
/*
* The actual maximum number of cycles we can defer the clocksource is
@@ -499,27 +495,26 @@ u64 clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask)
max_cycles = min(max_cycles, mask);
max_nsecs = clocksource_cyc2ns(max_cycles, mult - maxadj, shift);
+ /* return the max_cycles value as well if requested */
+ if (max_cyc)
+ *max_cyc = max_cycles;
+
+ /* Return 50% of the actual maximum, so we can detect bad values */
+ max_nsecs >>= 1;
+
return max_nsecs;
}
/**
- * clocksource_max_deferment - Returns max time the clocksource can be deferred
- * @cs: Pointer to clocksource
+ * clocksource_update_max_deferment - Updates the clocksource max_idle_ns & max_cycles
+ * @cs: Pointer to clocksource to be updated
*
*/
-static u64 clocksource_max_deferment(struct clocksource *cs)
+static inline void clocksource_update_max_deferment(struct clocksource *cs)
{
- u64 max_nsecs;
-
- max_nsecs = clocks_calc_max_nsecs(cs->mult, cs->shift, cs->maxadj,
- cs->mask);
- /*
- * To ensure that the clocksource does not wrap whilst we are idle,
- * limit the time the clocksource can be deferred by 12.5%. Please
- * note a margin of 12.5% is used because this can be computed with
- * a shift, versus say 10% which would require division.
- */
- return max_nsecs - (max_nsecs >> 3);
+ cs->max_idle_ns = clocks_calc_max_nsecs(cs->mult, cs->shift,
+ cs->maxadj, cs->mask,
+ &cs->max_cycles);
}
#ifndef CONFIG_ARCH_USES_GETTIMEOFFSET
@@ -648,7 +643,7 @@ static void clocksource_enqueue(struct clocksource *cs)
}
/**
- * __clocksource_updatefreq_scale - Used update clocksource with new freq
+ * __clocksource_update_freq_scale - Used update clocksource with new freq
* @cs: clocksource to be registered
* @scale: Scale factor multiplied against freq to get clocksource hz
* @freq: clocksource frequency (cycles per second) divided by scale
@@ -656,48 +651,64 @@ static void clocksource_enqueue(struct clocksource *cs)
* This should only be called from the clocksource->enable() method.
*
* This *SHOULD NOT* be called directly! Please use the
- * clocksource_updatefreq_hz() or clocksource_updatefreq_khz helper functions.
+ * __clocksource_update_freq_hz() or __clocksource_update_freq_khz() helper
+ * functions.
*/
-void __clocksource_updatefreq_scale(struct clocksource *cs, u32 scale, u32 freq)
+void __clocksource_update_freq_scale(struct clocksource *cs, u32 scale, u32 freq)
{
u64 sec;
+
/*
- * Calc the maximum number of seconds which we can run before
- * wrapping around. For clocksources which have a mask > 32bit
- * we need to limit the max sleep time to have a good
- * conversion precision. 10 minutes is still a reasonable
- * amount. That results in a shift value of 24 for a
- * clocksource with mask >= 40bit and f >= 4GHz. That maps to
- * ~ 0.06ppm granularity for NTP. We apply the same 12.5%
- * margin as we do in clocksource_max_deferment()
+ * Default clocksources are *special* and self-define their mult/shift.
+ * But, you're not special, so you should specify a freq value.
*/
- sec = (cs->mask - (cs->mask >> 3));
- do_div(sec, freq);
- do_div(sec, scale);
- if (!sec)
- sec = 1;
- else if (sec > 600 && cs->mask > UINT_MAX)
- sec = 600;
-
- clocks_calc_mult_shift(&cs->mult, &cs->shift, freq,
- NSEC_PER_SEC / scale, sec * scale);
-
+ if (freq) {
+ /*
+ * Calc the maximum number of seconds which we can run before
+ * wrapping around. For clocksources which have a mask > 32-bit
+ * we need to limit the max sleep time to have a good
+ * conversion precision. 10 minutes is still a reasonable
+ * amount. That results in a shift value of 24 for a
+ * clocksource with mask >= 40-bit and f >= 4GHz. That maps to
+ * ~ 0.06ppm granularity for NTP.
+ */
+ sec = cs->mask;
+ do_div(sec, freq);
+ do_div(sec, scale);
+ if (!sec)
+ sec = 1;
+ else if (sec > 600 && cs->mask > UINT_MAX)
+ sec = 600;
+
+ clocks_calc_mult_shift(&cs->mult, &cs->shift, freq,
+ NSEC_PER_SEC / scale, sec * scale);
+ }
/*
- * for clocksources that have large mults, to avoid overflow.
- * Since mult may be adjusted by ntp, add an safety extra margin
- *
+ * Ensure clocksources that have large 'mult' values don't overflow
+ * when adjusted.
*/
cs->maxadj = clocksource_max_adjustment(cs);
- while ((cs->mult + cs->maxadj < cs->mult)
- || (cs->mult - cs->maxadj > cs->mult)) {
+ while (freq && ((cs->mult + cs->maxadj < cs->mult)
+ || (cs->mult - cs->maxadj > cs->mult))) {
cs->mult >>= 1;
cs->shift--;
cs->maxadj = clocksource_max_adjustment(cs);
}
- cs->max_idle_ns = clocksource_max_deferment(cs);
+ /*
+ * Only warn for *special* clocksources that self-define
+ * their mult/shift values and don't specify a freq.
+ */
+ WARN_ONCE(cs->mult + cs->maxadj < cs->mult,
+ "timekeeping: Clocksource %s might overflow on 11%% adjustment\n",
+ cs->name);
+
+ clocksource_update_max_deferment(cs);
+
+ pr_info("clocksource %s: mask: 0x%llx max_cycles: 0x%llx, max_idle_ns: %lld ns\n",
+ cs->name, cs->mask, cs->max_cycles, cs->max_idle_ns);
}
-EXPORT_SYMBOL_GPL(__clocksource_updatefreq_scale);
+EXPORT_SYMBOL_GPL(__clocksource_update_freq_scale);
/**
* __clocksource_register_scale - Used to install new clocksources
@@ -714,7 +725,7 @@ int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq)
{
/* Initialize mult/shift and max_idle_ns */
- __clocksource_updatefreq_scale(cs, scale, freq);
+ __clocksource_update_freq_scale(cs, scale, freq);
/* Add clocksource to the clocksource list */
mutex_lock(&clocksource_mutex);
@@ -726,33 +737,6 @@ int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq)
}
EXPORT_SYMBOL_GPL(__clocksource_register_scale);
-
-/**
- * clocksource_register - Used to install new clocksources
- * @cs: clocksource to be registered
- *
- * Returns -EBUSY if registration fails, zero otherwise.
- */
-int clocksource_register(struct clocksource *cs)
-{
- /* calculate max adjustment for given mult/shift */
- cs->maxadj = clocksource_max_adjustment(cs);
- WARN_ONCE(cs->mult + cs->maxadj < cs->mult,
- "Clocksource %s might overflow on 11%% adjustment\n",
- cs->name);
-
- /* calculate max idle time permitted for this clocksource */
- cs->max_idle_ns = clocksource_max_deferment(cs);
-
- mutex_lock(&clocksource_mutex);
- clocksource_enqueue(cs);
- clocksource_enqueue_watchdog(cs);
- clocksource_select();
- mutex_unlock(&clocksource_mutex);
- return 0;
-}
-EXPORT_SYMBOL(clocksource_register);
-
static void __clocksource_change_rating(struct clocksource *cs, int rating)
{
list_del(&cs->list);
diff --git a/kernel/time/jiffies.c b/kernel/time/jiffies.c
index a6a5bf53e86d..c4bb518725b5 100644
--- a/kernel/time/jiffies.c
+++ b/kernel/time/jiffies.c
@@ -71,6 +71,7 @@ static struct clocksource clocksource_jiffies = {
.mask = 0xffffffff, /*32bits*/
.mult = NSEC_PER_JIFFY << JIFFIES_SHIFT, /* details above */
.shift = JIFFIES_SHIFT,
+ .max_cycles = 10,
};
__cacheline_aligned_in_smp DEFINE_SEQLOCK(jiffies_lock);
@@ -94,7 +95,7 @@ EXPORT_SYMBOL(jiffies);
static int __init init_jiffies_clocksource(void)
{
- return clocksource_register(&clocksource_jiffies);
+ return __clocksource_register(&clocksource_jiffies);
}
core_initcall(init_jiffies_clocksource);
@@ -130,6 +131,6 @@ int register_refined_jiffies(long cycles_per_second)
refined_jiffies.mult = ((u32)nsec_per_tick) << JIFFIES_SHIFT;
- clocksource_register(&refined_jiffies);
+ __clocksource_register(&refined_jiffies);
return 0;
}
diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c
index 01d2d15aa662..ca3bc5c7027c 100644
--- a/kernel/time/sched_clock.c
+++ b/kernel/time/sched_clock.c
@@ -125,9 +125,9 @@ void __init sched_clock_register(u64 (*read)(void), int bits,
new_mask = CLOCKSOURCE_MASK(bits);
- /* calculate how many ns until we wrap */
- wrap = clocks_calc_max_nsecs(new_mult, new_shift, 0, new_mask);
- new_wrap_kt = ns_to_ktime(wrap - (wrap >> 3));
+ /* calculate how many nanosecs until we risk wrapping */
+ wrap = clocks_calc_max_nsecs(new_mult, new_shift, 0, new_mask, NULL);
+ new_wrap_kt = ns_to_ktime(wrap);
/* update epoch for new counter and update epoch_ns from old counter*/
new_epoch = read();
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 91db94136c10..892f6cbf1e67 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -118,6 +118,117 @@ static inline void tk_update_sleep_time(struct timekeeper *tk, ktime_t delta)
tk->offs_boot = ktime_add(tk->offs_boot, delta);
}
+#ifdef CONFIG_DEBUG_TIMEKEEPING
+#define WARNING_FREQ (HZ*300) /* 5 minute rate-limiting */
+/*
+ * These simple flag variables are managed
+ * without locks, which is racy, but ok since
+ * we don't really care about being super
+ * precise about how many events were seen,
+ * just that a problem was observed.
+ */
+static int timekeeping_underflow_seen;
+static int timekeeping_overflow_seen;
+
+/* last_warning is only modified under the timekeeping lock */
+static long timekeeping_last_warning;
+
+static void timekeeping_check_update(struct timekeeper *tk, cycle_t offset)
+{
+
+ cycle_t max_cycles = tk->tkr.clock->max_cycles;
+ const char *name = tk->tkr.clock->name;
+
+ if (offset > max_cycles) {
+ printk_deferred("WARNING: timekeeping: Cycle offset (%lld) is larger than allowed by the '%s' clock's max_cycles value (%lld): time overflow danger\n",
+ offset, name, max_cycles);
+ printk_deferred(" timekeeping: Your kernel is sick, but tries to cope by capping time updates\n");
+ } else {
+ if (offset > (max_cycles >> 1)) {
+ printk_deferred("INFO: timekeeping: Cycle offset (%lld) is larger than the the '%s' clock's 50%% safety margin (%lld)\n",
+ offset, name, max_cycles >> 1);
+ printk_deferred(" timekeeping: Your kernel is still fine, but is feeling a bit nervous\n");
+ }
+ }
+
+ if (timekeeping_underflow_seen) {
+ if (jiffies - timekeeping_last_warning > WARNING_FREQ) {
+ printk_deferred("WARNING: Underflow in clocksource '%s' observed, time update ignored.\n", name);
+ printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
+ printk_deferred(" Your kernel is probably still fine.\n");
+ timekeeping_last_warning = jiffies;
+ }
+ timekeeping_underflow_seen = 0;
+ }
+
+ if (timekeeping_overflow_seen) {
+ if (jiffies - timekeeping_last_warning > WARNING_FREQ) {
+ printk_deferred("WARNING: Overflow in clocksource '%s' observed, time update capped.\n", name);
+ printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
+ printk_deferred(" Your kernel is probably still fine.\n");
+ timekeeping_last_warning = jiffies;
+ }
+ timekeeping_overflow_seen = 0;
+ }
+}
+
+static inline cycle_t timekeeping_get_delta(struct tk_read_base *tkr)
+{
+ cycle_t now, last, mask, max, delta;
+ unsigned int seq;
+
+ /*
+ * Since we're called holding a seqlock, the data may shift
+ * under us while we're doing the calculation. This can cause
+ * false positives, since we'd note a problem but throw the
+ * results away. So nest another seqlock here to atomically
+ * grab the points we are checking with.
+ */
+ do {
+ seq = read_seqcount_begin(&tk_core.seq);
+ now = tkr->read(tkr->clock);
+ last = tkr->cycle_last;
+ mask = tkr->mask;
+ max = tkr->clock->max_cycles;
+ } while (read_seqcount_retry(&tk_core.seq, seq));
+
+ delta = clocksource_delta(now, last, mask);
+
+ /*
+ * Try to catch underflows by checking if we are seeing small
+ * mask-relative negative values.
+ */
+ if (unlikely((~delta & mask) < (mask >> 3))) {
+ timekeeping_underflow_seen = 1;
+ delta = 0;
+ }
+
+ /* Cap delta value to the max_cycles values to avoid mult overflows */
+ if (unlikely(delta > max)) {
+ timekeeping_overflow_seen = 1;
+ delta = tkr->clock->max_cycles;
+ }
+
+ return delta;
+}
+#else
+static inline void timekeeping_check_update(struct timekeeper *tk, cycle_t offset)
+{
+}
+static inline cycle_t timekeeping_get_delta(struct tk_read_base *tkr)
+{
+ cycle_t cycle_now, delta;
+
+ /* read clocksource */
+ cycle_now = tkr->read(tkr->clock);
+
+ /* calculate the delta since the last update_wall_time */
+ delta = clocksource_delta(cycle_now, tkr->cycle_last, tkr->mask);
+
+ return delta;
+}
+#endif
+
/**
* tk_setup_internals - Set up internals to use clocksource clock.
*
@@ -193,14 +304,10 @@ static inline u32 arch_gettimeoffset(void) { return 0; }
static inline s64 timekeeping_get_ns(struct tk_read_base *tkr)
{
- cycle_t cycle_now, delta;
+ cycle_t delta;
s64 nsec;
- /* read clocksource: */
- cycle_now = tkr->read(tkr->clock);
-
- /* calculate the delta since the last update_wall_time: */
- delta = clocksource_delta(cycle_now, tkr->cycle_last, tkr->mask);
+ delta = timekeeping_get_delta(tkr);
nsec = delta * tkr->mult + tkr->xtime_nsec;
nsec >>= tkr->shift;
@@ -212,14 +319,10 @@ static inline s64 timekeeping_get_ns(struct tk_read_base *tkr)
static inline s64 timekeeping_get_ns_raw(struct timekeeper *tk)
{
struct clocksource *clock = tk->tkr.clock;
- cycle_t cycle_now, delta;
+ cycle_t delta;
s64 nsec;
- /* read clocksource: */
- cycle_now = tk->tkr.read(clock);
-
- /* calculate the delta since the last update_wall_time: */
- delta = clocksource_delta(cycle_now, tk->tkr.cycle_last, tk->tkr.mask);
+ delta = timekeeping_get_delta(&tk->tkr);
/* convert delta to nanoseconds. */
nsec = clocksource_cyc2ns(delta, clock->mult, clock->shift);
@@ -1630,6 +1733,9 @@ void update_wall_time(void)
if (offset < real_tk->cycle_interval)
goto out;
+ /* Do some additional sanity checking */
+ timekeeping_check_update(real_tk, offset);
+
/*
* With NO_HZ we may have to accumulate many cycle_intervals
* (think "ticks") worth of time at once. To do this efficiently,
diff --git a/kernel/time/timer_list.c b/kernel/time/timer_list.c
index 61ed862cdd37..2cfd19485824 100644
--- a/kernel/time/timer_list.c
+++ b/kernel/time/timer_list.c
@@ -228,9 +228,35 @@ print_tickdevice(struct seq_file *m, struct tick_device *td, int cpu)
print_name_offset(m, dev->set_next_event);
SEQ_printf(m, "\n");
- SEQ_printf(m, " set_mode: ");
- print_name_offset(m, dev->set_mode);
- SEQ_printf(m, "\n");
+ if (dev->set_mode) {
+ SEQ_printf(m, " set_mode: ");
+ print_name_offset(m, dev->set_mode);
+ SEQ_printf(m, "\n");
+ } else {
+ if (dev->set_mode_shutdown) {
+ SEQ_printf(m, " shutdown: ");
+ print_name_offset(m, dev->set_mode_shutdown);
+ SEQ_printf(m, "\n");
+ }
+
+ if (dev->set_mode_periodic) {
+ SEQ_printf(m, " periodic: ");
+ print_name_offset(m, dev->set_mode_periodic);
+ SEQ_printf(m, "\n");
+ }
+
+ if (dev->set_mode_oneshot) {
+ SEQ_printf(m, " oneshot: ");
+ print_name_offset(m, dev->set_mode_oneshot);
+ SEQ_printf(m, "\n");
+ }
+
+ if (dev->set_mode_resume) {
+ SEQ_printf(m, " resume: ");
+ print_name_offset(m, dev->set_mode_resume);
+ SEQ_printf(m, "\n");
+ }
+ }
SEQ_printf(m, " event_handler: ");
print_name_offset(m, dev->event_handler);
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index c5cefb3c009c..36b6fa88ce5b 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -865,6 +865,19 @@ config SCHED_STACK_END_CHECK
data corruption or a sporadic crash at a later stage once the region
is examined. The runtime overhead introduced is minimal.
+config DEBUG_TIMEKEEPING
+ bool "Enable extra timekeeping sanity checking"
+ help
+ This option will enable additional timekeeping sanity checks
+ which may be helpful when diagnosing issues where timekeeping
+ problems are suspected.
+
+ This may include checks in the timekeeping hotpaths, so this
+ option may have a (very small) performance impact to some
+ workloads.
+
+ If unsure, say N.
+
config TIMER_STATS
bool "Collect kernel timers statistics"
depends on DEBUG_KERNEL && PROC_FS
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