linux/kernel/time/clockevents.c

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/*
* linux/kernel/time/clockevents.c
*
* This file contains functions which manage clock event devices.
*
* Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
* Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
* Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
*
* This code is licenced under the GPL version 2. For details see
* kernel-base/COPYING.
*/
#include <linux/clockchips.h>
#include <linux/hrtimer.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/smp.h>
#include <linux/device.h>
#include "tick-internal.h"
/* The registered clock event devices */
static LIST_HEAD(clockevent_devices);
static LIST_HEAD(clockevents_released);
/* Protection for the above */
static DEFINE_RAW_SPINLOCK(clockevents_lock);
/* Protection for unbind operations */
static DEFINE_MUTEX(clockevents_mutex);
struct ce_unbind {
struct clock_event_device *ce;
int res;
};
clockevents: Sanitize ticks to nsec conversion Marc Kleine-Budde pointed out, that commit 77cc982 "clocksource: use clockevents_config_and_register() where possible" caused a regression for some of the converted subarchs. The reason is, that the clockevents core code converts the minimal hardware tick delta to a nanosecond value for core internal usage. This conversion is affected by integer math rounding loss, so the backwards conversion to hardware ticks will likely result in a value which is less than the configured hardware limitation. The affected subarchs used their own workaround (SIGH!) which got lost in the conversion. The solution for the issue at hand is simple: adding evt->mult - 1 to the shifted value before the integer divison in the core conversion function takes care of it. But this only works for the case where for the scaled math mult/shift pair "mult <= 1 << shift" is true. For the case where "mult > 1 << shift" we can apply the rounding add only for the minimum delta value to make sure that the backward conversion is not less than the given hardware limit. For the upper bound we need to omit the rounding add, because the backwards conversion is always larger than the original latch value. That would violate the upper bound of the hardware device. Though looking closer at the details of that function reveals another bogosity: The upper bounds check is broken as well. Checking for a resulting "clc" value greater than KTIME_MAX after the conversion is pointless. The conversion does: u64 clc = (latch << evt->shift) / evt->mult; So there is no sanity check for (latch << evt->shift) exceeding the 64bit boundary. The latch argument is "unsigned long", so on a 64bit arch the handed in argument could easily lead to an unnoticed shift overflow. With the above rounding fix applied the calculation before the divison is: u64 clc = (latch << evt->shift) + evt->mult - 1; So we need to make sure, that neither the shift nor the rounding add is overflowing the u64 boundary. [ukl: move assignment to rnd after eventually changing mult, fix build issue and correct comment with the right math] Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Russell King - ARM Linux <linux@arm.linux.org.uk> Cc: Marc Kleine-Budde <mkl@pengutronix.de> Cc: nicolas.ferre@atmel.com Cc: Marc Pignat <marc.pignat@hevs.ch> Cc: john.stultz@linaro.org Cc: kernel@pengutronix.de Cc: Ronald Wahl <ronald.wahl@raritan.com> Cc: LAK <linux-arm-kernel@lists.infradead.org> Cc: Ludovic Desroches <ludovic.desroches@atmel.com> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1380052223-24139-1-git-send-email-u.kleine-koenig@pengutronix.de Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
2013-09-24 23:50:23 +04:00
static u64 cev_delta2ns(unsigned long latch, struct clock_event_device *evt,
bool ismax)
{
nohz: Allow 32-bit machines to sleep for more than 2.15 seconds In the dynamic tick code, "max_delta_ns" (member of the "clock_event_device" structure) represents the maximum sleep time that can occur between timer events in nanoseconds. The variable, "max_delta_ns", is defined as an unsigned long which is a 32-bit integer for 32-bit machines and a 64-bit integer for 64-bit machines (if -m64 option is used for gcc). The value of max_delta_ns is set by calling the function "clockevent_delta2ns()" which returns a maximum value of LONG_MAX. For a 32-bit machine LONG_MAX is equal to 0x7fffffff and in nanoseconds this equates to ~2.15 seconds. Hence, the maximum sleep time for a 32-bit machine is ~2.15 seconds, where as for a 64-bit machine it will be many years. This patch changes the type of max_delta_ns to be "u64" instead of "unsigned long" so that this variable is a 64-bit type for both 32-bit and 64-bit machines. It also changes the maximum value returned by clockevent_delta2ns() to KTIME_MAX. Hence this allows a 32-bit machine to sleep for longer than ~2.15 seconds. Please note that this patch also changes "min_delta_ns" to be "u64" too and although this is unnecessary, it makes the patch simpler as it avoids to fixup all callers of clockevent_delta2ns(). [ tglx: changed "unsigned long long" to u64 as we use this data type through out the time code ] Signed-off-by: Jon Hunter <jon-hunter@ti.com> Cc: John Stultz <johnstul@us.ibm.com> LKML-Reference: <1250617512-23567-3-git-send-email-jon-hunter@ti.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2009-08-18 21:45:11 +04:00
u64 clc = (u64) latch << evt->shift;
clockevents: Sanitize ticks to nsec conversion Marc Kleine-Budde pointed out, that commit 77cc982 "clocksource: use clockevents_config_and_register() where possible" caused a regression for some of the converted subarchs. The reason is, that the clockevents core code converts the minimal hardware tick delta to a nanosecond value for core internal usage. This conversion is affected by integer math rounding loss, so the backwards conversion to hardware ticks will likely result in a value which is less than the configured hardware limitation. The affected subarchs used their own workaround (SIGH!) which got lost in the conversion. The solution for the issue at hand is simple: adding evt->mult - 1 to the shifted value before the integer divison in the core conversion function takes care of it. But this only works for the case where for the scaled math mult/shift pair "mult <= 1 << shift" is true. For the case where "mult > 1 << shift" we can apply the rounding add only for the minimum delta value to make sure that the backward conversion is not less than the given hardware limit. For the upper bound we need to omit the rounding add, because the backwards conversion is always larger than the original latch value. That would violate the upper bound of the hardware device. Though looking closer at the details of that function reveals another bogosity: The upper bounds check is broken as well. Checking for a resulting "clc" value greater than KTIME_MAX after the conversion is pointless. The conversion does: u64 clc = (latch << evt->shift) / evt->mult; So there is no sanity check for (latch << evt->shift) exceeding the 64bit boundary. The latch argument is "unsigned long", so on a 64bit arch the handed in argument could easily lead to an unnoticed shift overflow. With the above rounding fix applied the calculation before the divison is: u64 clc = (latch << evt->shift) + evt->mult - 1; So we need to make sure, that neither the shift nor the rounding add is overflowing the u64 boundary. [ukl: move assignment to rnd after eventually changing mult, fix build issue and correct comment with the right math] Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Russell King - ARM Linux <linux@arm.linux.org.uk> Cc: Marc Kleine-Budde <mkl@pengutronix.de> Cc: nicolas.ferre@atmel.com Cc: Marc Pignat <marc.pignat@hevs.ch> Cc: john.stultz@linaro.org Cc: kernel@pengutronix.de Cc: Ronald Wahl <ronald.wahl@raritan.com> Cc: LAK <linux-arm-kernel@lists.infradead.org> Cc: Ludovic Desroches <ludovic.desroches@atmel.com> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1380052223-24139-1-git-send-email-u.kleine-koenig@pengutronix.de Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
2013-09-24 23:50:23 +04:00
u64 rnd;
if (unlikely(!evt->mult)) {
evt->mult = 1;
WARN_ON(1);
}
clockevents: Sanitize ticks to nsec conversion Marc Kleine-Budde pointed out, that commit 77cc982 "clocksource: use clockevents_config_and_register() where possible" caused a regression for some of the converted subarchs. The reason is, that the clockevents core code converts the minimal hardware tick delta to a nanosecond value for core internal usage. This conversion is affected by integer math rounding loss, so the backwards conversion to hardware ticks will likely result in a value which is less than the configured hardware limitation. The affected subarchs used their own workaround (SIGH!) which got lost in the conversion. The solution for the issue at hand is simple: adding evt->mult - 1 to the shifted value before the integer divison in the core conversion function takes care of it. But this only works for the case where for the scaled math mult/shift pair "mult <= 1 << shift" is true. For the case where "mult > 1 << shift" we can apply the rounding add only for the minimum delta value to make sure that the backward conversion is not less than the given hardware limit. For the upper bound we need to omit the rounding add, because the backwards conversion is always larger than the original latch value. That would violate the upper bound of the hardware device. Though looking closer at the details of that function reveals another bogosity: The upper bounds check is broken as well. Checking for a resulting "clc" value greater than KTIME_MAX after the conversion is pointless. The conversion does: u64 clc = (latch << evt->shift) / evt->mult; So there is no sanity check for (latch << evt->shift) exceeding the 64bit boundary. The latch argument is "unsigned long", so on a 64bit arch the handed in argument could easily lead to an unnoticed shift overflow. With the above rounding fix applied the calculation before the divison is: u64 clc = (latch << evt->shift) + evt->mult - 1; So we need to make sure, that neither the shift nor the rounding add is overflowing the u64 boundary. [ukl: move assignment to rnd after eventually changing mult, fix build issue and correct comment with the right math] Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Russell King - ARM Linux <linux@arm.linux.org.uk> Cc: Marc Kleine-Budde <mkl@pengutronix.de> Cc: nicolas.ferre@atmel.com Cc: Marc Pignat <marc.pignat@hevs.ch> Cc: john.stultz@linaro.org Cc: kernel@pengutronix.de Cc: Ronald Wahl <ronald.wahl@raritan.com> Cc: LAK <linux-arm-kernel@lists.infradead.org> Cc: Ludovic Desroches <ludovic.desroches@atmel.com> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1380052223-24139-1-git-send-email-u.kleine-koenig@pengutronix.de Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
2013-09-24 23:50:23 +04:00
rnd = (u64) evt->mult - 1;
/*
* Upper bound sanity check. If the backwards conversion is
* not equal latch, we know that the above shift overflowed.
*/
if ((clc >> evt->shift) != (u64)latch)
clc = ~0ULL;
/*
* Scaled math oddities:
*
* For mult <= (1 << shift) we can safely add mult - 1 to
* prevent integer rounding loss. So the backwards conversion
* from nsec to device ticks will be correct.
*
* For mult > (1 << shift), i.e. device frequency is > 1GHz we
* need to be careful. Adding mult - 1 will result in a value
* which when converted back to device ticks can be larger
* than latch by up to (mult - 1) >> shift. For the min_delta
* calculation we still want to apply this in order to stay
* above the minimum device ticks limit. For the upper limit
* we would end up with a latch value larger than the upper
* limit of the device, so we omit the add to stay below the
* device upper boundary.
*
* Also omit the add if it would overflow the u64 boundary.
*/
if ((~0ULL - clc > rnd) &&
(!ismax || evt->mult <= (1U << evt->shift)))
clc += rnd;
do_div(clc, evt->mult);
clockevents: Sanitize ticks to nsec conversion Marc Kleine-Budde pointed out, that commit 77cc982 "clocksource: use clockevents_config_and_register() where possible" caused a regression for some of the converted subarchs. The reason is, that the clockevents core code converts the minimal hardware tick delta to a nanosecond value for core internal usage. This conversion is affected by integer math rounding loss, so the backwards conversion to hardware ticks will likely result in a value which is less than the configured hardware limitation. The affected subarchs used their own workaround (SIGH!) which got lost in the conversion. The solution for the issue at hand is simple: adding evt->mult - 1 to the shifted value before the integer divison in the core conversion function takes care of it. But this only works for the case where for the scaled math mult/shift pair "mult <= 1 << shift" is true. For the case where "mult > 1 << shift" we can apply the rounding add only for the minimum delta value to make sure that the backward conversion is not less than the given hardware limit. For the upper bound we need to omit the rounding add, because the backwards conversion is always larger than the original latch value. That would violate the upper bound of the hardware device. Though looking closer at the details of that function reveals another bogosity: The upper bounds check is broken as well. Checking for a resulting "clc" value greater than KTIME_MAX after the conversion is pointless. The conversion does: u64 clc = (latch << evt->shift) / evt->mult; So there is no sanity check for (latch << evt->shift) exceeding the 64bit boundary. The latch argument is "unsigned long", so on a 64bit arch the handed in argument could easily lead to an unnoticed shift overflow. With the above rounding fix applied the calculation before the divison is: u64 clc = (latch << evt->shift) + evt->mult - 1; So we need to make sure, that neither the shift nor the rounding add is overflowing the u64 boundary. [ukl: move assignment to rnd after eventually changing mult, fix build issue and correct comment with the right math] Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Russell King - ARM Linux <linux@arm.linux.org.uk> Cc: Marc Kleine-Budde <mkl@pengutronix.de> Cc: nicolas.ferre@atmel.com Cc: Marc Pignat <marc.pignat@hevs.ch> Cc: john.stultz@linaro.org Cc: kernel@pengutronix.de Cc: Ronald Wahl <ronald.wahl@raritan.com> Cc: LAK <linux-arm-kernel@lists.infradead.org> Cc: Ludovic Desroches <ludovic.desroches@atmel.com> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1380052223-24139-1-git-send-email-u.kleine-koenig@pengutronix.de Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
2013-09-24 23:50:23 +04:00
/* Deltas less than 1usec are pointless noise */
return clc > 1000 ? clc : 1000;
}
/**
* clockevents_delta2ns - Convert a latch value (device ticks) to nanoseconds
* @latch: value to convert
* @evt: pointer to clock event device descriptor
*
* Math helper, returns latch value converted to nanoseconds (bound checked)
*/
u64 clockevent_delta2ns(unsigned long latch, struct clock_event_device *evt)
{
return cev_delta2ns(latch, evt, false);
}
EXPORT_SYMBOL_GPL(clockevent_delta2ns);
/**
* clockevents_set_mode - set the operating mode of a clock event device
* @dev: device to modify
* @mode: new mode
*
* Must be called with interrupts disabled !
*/
void clockevents_set_mode(struct clock_event_device *dev,
enum clock_event_mode mode)
{
if (dev->mode != mode) {
dev->set_mode(mode, dev);
dev->mode = mode;
/*
* A nsec2cyc multiplicator of 0 is invalid and we'd crash
* on it, so fix it up and emit a warning:
*/
if (mode == CLOCK_EVT_MODE_ONESHOT) {
if (unlikely(!dev->mult)) {
dev->mult = 1;
WARN_ON(1);
}
}
}
}
/**
* clockevents_shutdown - shutdown the device and clear next_event
* @dev: device to shutdown
*/
void clockevents_shutdown(struct clock_event_device *dev)
{
clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
dev->next_event.tv64 = KTIME_MAX;
}
#ifdef CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST
/* Limit min_delta to a jiffie */
#define MIN_DELTA_LIMIT (NSEC_PER_SEC / HZ)
/**
* clockevents_increase_min_delta - raise minimum delta of a clock event device
* @dev: device to increase the minimum delta
*
* Returns 0 on success, -ETIME when the minimum delta reached the limit.
*/
static int clockevents_increase_min_delta(struct clock_event_device *dev)
{
/* Nothing to do if we already reached the limit */
if (dev->min_delta_ns >= MIN_DELTA_LIMIT) {
printk(KERN_WARNING "CE: Reprogramming failure. Giving up\n");
dev->next_event.tv64 = KTIME_MAX;
return -ETIME;
}
if (dev->min_delta_ns < 5000)
dev->min_delta_ns = 5000;
else
dev->min_delta_ns += dev->min_delta_ns >> 1;
if (dev->min_delta_ns > MIN_DELTA_LIMIT)
dev->min_delta_ns = MIN_DELTA_LIMIT;
printk(KERN_WARNING "CE: %s increased min_delta_ns to %llu nsec\n",
dev->name ? dev->name : "?",
(unsigned long long) dev->min_delta_ns);
return 0;
}
/**
* clockevents_program_min_delta - Set clock event device to the minimum delay.
* @dev: device to program
*
* Returns 0 on success, -ETIME when the retry loop failed.
*/
static int clockevents_program_min_delta(struct clock_event_device *dev)
{
unsigned long long clc;
int64_t delta;
int i;
for (i = 0;;) {
delta = dev->min_delta_ns;
dev->next_event = ktime_add_ns(ktime_get(), delta);
if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN)
return 0;
dev->retries++;
clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
if (dev->set_next_event((unsigned long) clc, dev) == 0)
return 0;
if (++i > 2) {
/*
* We tried 3 times to program the device with the
* given min_delta_ns. Try to increase the minimum
* delta, if that fails as well get out of here.
*/
if (clockevents_increase_min_delta(dev))
return -ETIME;
i = 0;
}
}
}
#else /* CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST */
/**
* clockevents_program_min_delta - Set clock event device to the minimum delay.
* @dev: device to program
*
* Returns 0 on success, -ETIME when the retry loop failed.
*/
static int clockevents_program_min_delta(struct clock_event_device *dev)
{
unsigned long long clc;
int64_t delta;
delta = dev->min_delta_ns;
dev->next_event = ktime_add_ns(ktime_get(), delta);
if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN)
return 0;
dev->retries++;
clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
return dev->set_next_event((unsigned long) clc, dev);
}
#endif /* CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST */
/**
* clockevents_program_event - Reprogram the clock event device.
* @dev: device to program
* @expires: absolute expiry time (monotonic clock)
* @force: program minimum delay if expires can not be set
*
* Returns 0 on success, -ETIME when the event is in the past.
*/
int clockevents_program_event(struct clock_event_device *dev, ktime_t expires,
bool force)
{
unsigned long long clc;
int64_t delta;
int rc;
if (unlikely(expires.tv64 < 0)) {
WARN_ON_ONCE(1);
return -ETIME;
}
dev->next_event = expires;
if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN)
return 0;
/* Shortcut for clockevent devices that can deal with ktime. */
if (dev->features & CLOCK_EVT_FEAT_KTIME)
return dev->set_next_ktime(expires, dev);
delta = ktime_to_ns(ktime_sub(expires, ktime_get()));
if (delta <= 0)
return force ? clockevents_program_min_delta(dev) : -ETIME;
delta = min(delta, (int64_t) dev->max_delta_ns);
delta = max(delta, (int64_t) dev->min_delta_ns);
clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
rc = dev->set_next_event((unsigned long) clc, dev);
return (rc && force) ? clockevents_program_min_delta(dev) : rc;
}
/*
* Called after a notify add to make devices available which were
* released from the notifier call.
*/
static void clockevents_notify_released(void)
{
struct clock_event_device *dev;
while (!list_empty(&clockevents_released)) {
dev = list_entry(clockevents_released.next,
struct clock_event_device, list);
list_del(&dev->list);
list_add(&dev->list, &clockevent_devices);
tick_check_new_device(dev);
}
}
/*
* Try to install a replacement clock event device
*/
static int clockevents_replace(struct clock_event_device *ced)
{
struct clock_event_device *dev, *newdev = NULL;
list_for_each_entry(dev, &clockevent_devices, list) {
if (dev == ced || dev->mode != CLOCK_EVT_MODE_UNUSED)
continue;
if (!tick_check_replacement(newdev, dev))
continue;
if (!try_module_get(dev->owner))
continue;
if (newdev)
module_put(newdev->owner);
newdev = dev;
}
if (newdev) {
tick_install_replacement(newdev);
list_del_init(&ced->list);
}
return newdev ? 0 : -EBUSY;
}
/*
* Called with clockevents_mutex and clockevents_lock held
*/
static int __clockevents_try_unbind(struct clock_event_device *ced, int cpu)
{
/* Fast track. Device is unused */
if (ced->mode == CLOCK_EVT_MODE_UNUSED) {
list_del_init(&ced->list);
return 0;
}
return ced == per_cpu(tick_cpu_device, cpu).evtdev ? -EAGAIN : -EBUSY;
}
/*
* SMP function call to unbind a device
*/
static void __clockevents_unbind(void *arg)
{
struct ce_unbind *cu = arg;
int res;
raw_spin_lock(&clockevents_lock);
res = __clockevents_try_unbind(cu->ce, smp_processor_id());
if (res == -EAGAIN)
res = clockevents_replace(cu->ce);
cu->res = res;
raw_spin_unlock(&clockevents_lock);
}
/*
* Issues smp function call to unbind a per cpu device. Called with
* clockevents_mutex held.
*/
static int clockevents_unbind(struct clock_event_device *ced, int cpu)
{
struct ce_unbind cu = { .ce = ced, .res = -ENODEV };
smp_call_function_single(cpu, __clockevents_unbind, &cu, 1);
return cu.res;
}
/*
* Unbind a clockevents device.
*/
int clockevents_unbind_device(struct clock_event_device *ced, int cpu)
{
int ret;
mutex_lock(&clockevents_mutex);
ret = clockevents_unbind(ced, cpu);
mutex_unlock(&clockevents_mutex);
return ret;
}
EXPORT_SYMBOL_GPL(clockevents_unbind);
/**
* clockevents_register_device - register a clock event device
* @dev: device to register
*/
void clockevents_register_device(struct clock_event_device *dev)
{
2009-08-18 01:34:59 +04:00
unsigned long flags;
BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED);
if (!dev->cpumask) {
WARN_ON(num_possible_cpus() > 1);
dev->cpumask = cpumask_of(smp_processor_id());
}
raw_spin_lock_irqsave(&clockevents_lock, flags);
list_add(&dev->list, &clockevent_devices);
tick_check_new_device(dev);
clockevents_notify_released();
raw_spin_unlock_irqrestore(&clockevents_lock, flags);
}
EXPORT_SYMBOL_GPL(clockevents_register_device);
void clockevents_config(struct clock_event_device *dev, u32 freq)
{
u64 sec;
if (!(dev->features & CLOCK_EVT_FEAT_ONESHOT))
return;
/*
* Calculate the maximum number of seconds we can sleep. Limit
* to 10 minutes for hardware which can program more than
* 32bit ticks so we still get reasonable conversion values.
*/
sec = dev->max_delta_ticks;
do_div(sec, freq);
if (!sec)
sec = 1;
else if (sec > 600 && dev->max_delta_ticks > UINT_MAX)
sec = 600;
clockevents_calc_mult_shift(dev, freq, sec);
clockevents: Sanitize ticks to nsec conversion Marc Kleine-Budde pointed out, that commit 77cc982 "clocksource: use clockevents_config_and_register() where possible" caused a regression for some of the converted subarchs. The reason is, that the clockevents core code converts the minimal hardware tick delta to a nanosecond value for core internal usage. This conversion is affected by integer math rounding loss, so the backwards conversion to hardware ticks will likely result in a value which is less than the configured hardware limitation. The affected subarchs used their own workaround (SIGH!) which got lost in the conversion. The solution for the issue at hand is simple: adding evt->mult - 1 to the shifted value before the integer divison in the core conversion function takes care of it. But this only works for the case where for the scaled math mult/shift pair "mult <= 1 << shift" is true. For the case where "mult > 1 << shift" we can apply the rounding add only for the minimum delta value to make sure that the backward conversion is not less than the given hardware limit. For the upper bound we need to omit the rounding add, because the backwards conversion is always larger than the original latch value. That would violate the upper bound of the hardware device. Though looking closer at the details of that function reveals another bogosity: The upper bounds check is broken as well. Checking for a resulting "clc" value greater than KTIME_MAX after the conversion is pointless. The conversion does: u64 clc = (latch << evt->shift) / evt->mult; So there is no sanity check for (latch << evt->shift) exceeding the 64bit boundary. The latch argument is "unsigned long", so on a 64bit arch the handed in argument could easily lead to an unnoticed shift overflow. With the above rounding fix applied the calculation before the divison is: u64 clc = (latch << evt->shift) + evt->mult - 1; So we need to make sure, that neither the shift nor the rounding add is overflowing the u64 boundary. [ukl: move assignment to rnd after eventually changing mult, fix build issue and correct comment with the right math] Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Russell King - ARM Linux <linux@arm.linux.org.uk> Cc: Marc Kleine-Budde <mkl@pengutronix.de> Cc: nicolas.ferre@atmel.com Cc: Marc Pignat <marc.pignat@hevs.ch> Cc: john.stultz@linaro.org Cc: kernel@pengutronix.de Cc: Ronald Wahl <ronald.wahl@raritan.com> Cc: LAK <linux-arm-kernel@lists.infradead.org> Cc: Ludovic Desroches <ludovic.desroches@atmel.com> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1380052223-24139-1-git-send-email-u.kleine-koenig@pengutronix.de Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
2013-09-24 23:50:23 +04:00
dev->min_delta_ns = cev_delta2ns(dev->min_delta_ticks, dev, false);
dev->max_delta_ns = cev_delta2ns(dev->max_delta_ticks, dev, true);
}
/**
* clockevents_config_and_register - Configure and register a clock event device
* @dev: device to register
* @freq: The clock frequency
* @min_delta: The minimum clock ticks to program in oneshot mode
* @max_delta: The maximum clock ticks to program in oneshot mode
*
* min/max_delta can be 0 for devices which do not support oneshot mode.
*/
void clockevents_config_and_register(struct clock_event_device *dev,
u32 freq, unsigned long min_delta,
unsigned long max_delta)
{
dev->min_delta_ticks = min_delta;
dev->max_delta_ticks = max_delta;
clockevents_config(dev, freq);
clockevents_register_device(dev);
}
EXPORT_SYMBOL_GPL(clockevents_config_and_register);
/**
* clockevents_update_freq - Update frequency and reprogram a clock event device.
* @dev: device to modify
* @freq: new device frequency
*
* Reconfigure and reprogram a clock event device in oneshot
* mode. Must be called on the cpu for which the device delivers per
* cpu timer events with interrupts disabled! Returns 0 on success,
* -ETIME when the event is in the past.
*/
int clockevents_update_freq(struct clock_event_device *dev, u32 freq)
{
clockevents_config(dev, freq);
if (dev->mode != CLOCK_EVT_MODE_ONESHOT)
return 0;
return clockevents_program_event(dev, dev->next_event, false);
}
/*
* Noop handler when we shut down an event device
*/
void clockevents_handle_noop(struct clock_event_device *dev)
{
}
/**
* clockevents_exchange_device - release and request clock devices
* @old: device to release (can be NULL)
* @new: device to request (can be NULL)
*
* Called from the notifier chain. clockevents_lock is held already
*/
void clockevents_exchange_device(struct clock_event_device *old,
struct clock_event_device *new)
{
unsigned long flags;
local_irq_save(flags);
/*
* Caller releases a clock event device. We queue it into the
* released list and do a notify add later.
*/
if (old) {
module_put(old->owner);
clockevents_set_mode(old, CLOCK_EVT_MODE_UNUSED);
list_del(&old->list);
list_add(&old->list, &clockevents_released);
}
if (new) {
BUG_ON(new->mode != CLOCK_EVT_MODE_UNUSED);
clockevents_shutdown(new);
}
local_irq_restore(flags);
}
/**
* clockevents_suspend - suspend clock devices
*/
void clockevents_suspend(void)
{
struct clock_event_device *dev;
list_for_each_entry_reverse(dev, &clockevent_devices, list)
if (dev->suspend)
dev->suspend(dev);
}
/**
* clockevents_resume - resume clock devices
*/
void clockevents_resume(void)
{
struct clock_event_device *dev;
list_for_each_entry(dev, &clockevent_devices, list)
if (dev->resume)
dev->resume(dev);
}
#ifdef CONFIG_GENERIC_CLOCKEVENTS
/**
* clockevents_notify - notification about relevant events
*/
void clockevents_notify(unsigned long reason, void *arg)
{
struct clock_event_device *dev, *tmp;
2009-08-18 01:34:59 +04:00
unsigned long flags;
int cpu;
raw_spin_lock_irqsave(&clockevents_lock, flags);
switch (reason) {
case CLOCK_EVT_NOTIFY_BROADCAST_ON:
case CLOCK_EVT_NOTIFY_BROADCAST_OFF:
case CLOCK_EVT_NOTIFY_BROADCAST_FORCE:
tick_broadcast_on_off(reason, arg);
break;
case CLOCK_EVT_NOTIFY_BROADCAST_ENTER:
case CLOCK_EVT_NOTIFY_BROADCAST_EXIT:
tick_broadcast_oneshot_control(reason);
break;
case CLOCK_EVT_NOTIFY_CPU_DYING:
tick_handover_do_timer(arg);
break;
case CLOCK_EVT_NOTIFY_SUSPEND:
tick_suspend();
tick_suspend_broadcast();
break;
case CLOCK_EVT_NOTIFY_RESUME:
tick_resume();
break;
case CLOCK_EVT_NOTIFY_CPU_DEAD:
tick_shutdown_broadcast_oneshot(arg);
tick_shutdown_broadcast(arg);
tick_shutdown(arg);
/*
* Unregister the clock event devices which were
* released from the users in the notify chain.
*/
list_for_each_entry_safe(dev, tmp, &clockevents_released, list)
list_del(&dev->list);
/*
* Now check whether the CPU has left unused per cpu devices
*/
cpu = *((int *)arg);
list_for_each_entry_safe(dev, tmp, &clockevent_devices, list) {
if (cpumask_test_cpu(cpu, dev->cpumask) &&
cpumask_weight(dev->cpumask) == 1 &&
!tick_is_broadcast_device(dev)) {
BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED);
list_del(&dev->list);
}
}
break;
default:
break;
}
raw_spin_unlock_irqrestore(&clockevents_lock, flags);
}
EXPORT_SYMBOL_GPL(clockevents_notify);
#ifdef CONFIG_SYSFS
struct bus_type clockevents_subsys = {
.name = "clockevents",
.dev_name = "clockevent",
};
static DEFINE_PER_CPU(struct device, tick_percpu_dev);
static struct tick_device *tick_get_tick_dev(struct device *dev);
static ssize_t sysfs_show_current_tick_dev(struct device *dev,
struct device_attribute *attr,
char *buf)
{
struct tick_device *td;
ssize_t count = 0;
raw_spin_lock_irq(&clockevents_lock);
td = tick_get_tick_dev(dev);
if (td && td->evtdev)
count = snprintf(buf, PAGE_SIZE, "%s\n", td->evtdev->name);
raw_spin_unlock_irq(&clockevents_lock);
return count;
}
static DEVICE_ATTR(current_device, 0444, sysfs_show_current_tick_dev, NULL);
/* We don't support the abomination of removable broadcast devices */
static ssize_t sysfs_unbind_tick_dev(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
char name[CS_NAME_LEN];
size_t ret = sysfs_get_uname(buf, name, count);
struct clock_event_device *ce;
if (ret < 0)
return ret;
ret = -ENODEV;
mutex_lock(&clockevents_mutex);
raw_spin_lock_irq(&clockevents_lock);
list_for_each_entry(ce, &clockevent_devices, list) {
if (!strcmp(ce->name, name)) {
ret = __clockevents_try_unbind(ce, dev->id);
break;
}
}
raw_spin_unlock_irq(&clockevents_lock);
/*
* We hold clockevents_mutex, so ce can't go away
*/
if (ret == -EAGAIN)
ret = clockevents_unbind(ce, dev->id);
mutex_unlock(&clockevents_mutex);
return ret ? ret : count;
}
static DEVICE_ATTR(unbind_device, 0200, NULL, sysfs_unbind_tick_dev);
#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
static struct device tick_bc_dev = {
.init_name = "broadcast",
.id = 0,
.bus = &clockevents_subsys,
};
static struct tick_device *tick_get_tick_dev(struct device *dev)
{
return dev == &tick_bc_dev ? tick_get_broadcast_device() :
&per_cpu(tick_cpu_device, dev->id);
}
static __init int tick_broadcast_init_sysfs(void)
{
int err = device_register(&tick_bc_dev);
if (!err)
err = device_create_file(&tick_bc_dev, &dev_attr_current_device);
return err;
}
#else
static struct tick_device *tick_get_tick_dev(struct device *dev)
{
return &per_cpu(tick_cpu_device, dev->id);
}
static inline int tick_broadcast_init_sysfs(void) { return 0; }
#endif
static int __init tick_init_sysfs(void)
{
int cpu;
for_each_possible_cpu(cpu) {
struct device *dev = &per_cpu(tick_percpu_dev, cpu);
int err;
dev->id = cpu;
dev->bus = &clockevents_subsys;
err = device_register(dev);
if (!err)
err = device_create_file(dev, &dev_attr_current_device);
if (!err)
err = device_create_file(dev, &dev_attr_unbind_device);
if (err)
return err;
}
return tick_broadcast_init_sysfs();
}
static int __init clockevents_init_sysfs(void)
{
int err = subsys_system_register(&clockevents_subsys, NULL);
if (!err)
err = tick_init_sysfs();
return err;
}
device_initcall(clockevents_init_sysfs);
#endif /* SYSFS */
#endif /* GENERIC_CLOCK_EVENTS */