linux/drivers/cpuidle/driver.c
Chris Metcalf 6727ad9e20 nmi_backtrace: generate one-line reports for idle cpus
When doing an nmi backtrace of many cores, most of which are idle, the
output is a little overwhelming and very uninformative.  Suppress
messages for cpus that are idling when they are interrupted and just
emit one line, "NMI backtrace for N skipped: idling at pc 0xNNN".

We do this by grouping all the cpuidle code together into a new
.cpuidle.text section, and then checking the address of the interrupted
PC to see if it lies within that section.

This commit suitably tags x86 and tile idle routines, and only adds in
the minimal framework for other architectures.

Link: http://lkml.kernel.org/r/1472487169-14923-5-git-send-email-cmetcalf@mellanox.com
Signed-off-by: Chris Metcalf <cmetcalf@mellanox.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Daniel Thompson <daniel.thompson@linaro.org> [arm]
Tested-by: Petr Mladek <pmladek@suse.com>
Cc: Aaron Tomlin <atomlin@redhat.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-07 18:46:30 -07:00

388 lines
9.4 KiB
C

/*
* driver.c - driver support
*
* (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
* Shaohua Li <shaohua.li@intel.com>
* Adam Belay <abelay@novell.com>
*
* This code is licenced under the GPL.
*/
#include <linux/mutex.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/cpuidle.h>
#include <linux/cpumask.h>
#include <linux/tick.h>
#include <linux/cpu.h>
#include "cpuidle.h"
DEFINE_SPINLOCK(cpuidle_driver_lock);
#ifdef CONFIG_CPU_IDLE_MULTIPLE_DRIVERS
static DEFINE_PER_CPU(struct cpuidle_driver *, cpuidle_drivers);
/**
* __cpuidle_get_cpu_driver - return the cpuidle driver tied to a CPU.
* @cpu: the CPU handled by the driver
*
* Returns a pointer to struct cpuidle_driver or NULL if no driver has been
* registered for @cpu.
*/
static struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
{
return per_cpu(cpuidle_drivers, cpu);
}
/**
* __cpuidle_unset_driver - unset per CPU driver variables.
* @drv: a valid pointer to a struct cpuidle_driver
*
* For each CPU in the driver's CPU mask, unset the registered driver per CPU
* variable. If @drv is different from the registered driver, the corresponding
* variable is not cleared.
*/
static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv)
{
int cpu;
for_each_cpu(cpu, drv->cpumask) {
if (drv != __cpuidle_get_cpu_driver(cpu))
continue;
per_cpu(cpuidle_drivers, cpu) = NULL;
}
}
/**
* __cpuidle_set_driver - set per CPU driver variables for the given driver.
* @drv: a valid pointer to a struct cpuidle_driver
*
* For each CPU in the driver's cpumask, unset the registered driver per CPU
* to @drv.
*
* Returns 0 on success, -EBUSY if the CPUs have driver(s) already.
*/
static inline int __cpuidle_set_driver(struct cpuidle_driver *drv)
{
int cpu;
for_each_cpu(cpu, drv->cpumask) {
if (__cpuidle_get_cpu_driver(cpu)) {
__cpuidle_unset_driver(drv);
return -EBUSY;
}
per_cpu(cpuidle_drivers, cpu) = drv;
}
return 0;
}
#else
static struct cpuidle_driver *cpuidle_curr_driver;
/**
* __cpuidle_get_cpu_driver - return the global cpuidle driver pointer.
* @cpu: ignored without the multiple driver support
*
* Return a pointer to a struct cpuidle_driver object or NULL if no driver was
* previously registered.
*/
static inline struct cpuidle_driver *__cpuidle_get_cpu_driver(int cpu)
{
return cpuidle_curr_driver;
}
/**
* __cpuidle_set_driver - assign the global cpuidle driver variable.
* @drv: pointer to a struct cpuidle_driver object
*
* Returns 0 on success, -EBUSY if the driver is already registered.
*/
static inline int __cpuidle_set_driver(struct cpuidle_driver *drv)
{
if (cpuidle_curr_driver)
return -EBUSY;
cpuidle_curr_driver = drv;
return 0;
}
/**
* __cpuidle_unset_driver - unset the global cpuidle driver variable.
* @drv: a pointer to a struct cpuidle_driver
*
* Reset the global cpuidle variable to NULL. If @drv does not match the
* registered driver, do nothing.
*/
static inline void __cpuidle_unset_driver(struct cpuidle_driver *drv)
{
if (drv == cpuidle_curr_driver)
cpuidle_curr_driver = NULL;
}
#endif
/**
* cpuidle_setup_broadcast_timer - enable/disable the broadcast timer on a cpu
* @arg: a void pointer used to match the SMP cross call API
*
* If @arg is NULL broadcast is disabled otherwise enabled
*
* This function is executed per CPU by an SMP cross call. It's not
* supposed to be called directly.
*/
static void cpuidle_setup_broadcast_timer(void *arg)
{
if (arg)
tick_broadcast_enable();
else
tick_broadcast_disable();
}
/**
* __cpuidle_driver_init - initialize the driver's internal data
* @drv: a valid pointer to a struct cpuidle_driver
*/
static void __cpuidle_driver_init(struct cpuidle_driver *drv)
{
int i;
drv->refcnt = 0;
/*
* Use all possible CPUs as the default, because if the kernel boots
* with some CPUs offline and then we online one of them, the CPU
* notifier has to know which driver to assign.
*/
if (!drv->cpumask)
drv->cpumask = (struct cpumask *)cpu_possible_mask;
/*
* Look for the timer stop flag in the different states, so that we know
* if the broadcast timer has to be set up. The loop is in the reverse
* order, because usually one of the deeper states have this flag set.
*/
for (i = drv->state_count - 1; i >= 0 ; i--) {
if (drv->states[i].flags & CPUIDLE_FLAG_TIMER_STOP) {
drv->bctimer = 1;
break;
}
}
}
#ifdef CONFIG_ARCH_HAS_CPU_RELAX
static int __cpuidle poll_idle(struct cpuidle_device *dev,
struct cpuidle_driver *drv, int index)
{
local_irq_enable();
if (!current_set_polling_and_test()) {
while (!need_resched())
cpu_relax();
}
current_clr_polling();
return index;
}
static void poll_idle_init(struct cpuidle_driver *drv)
{
struct cpuidle_state *state = &drv->states[0];
snprintf(state->name, CPUIDLE_NAME_LEN, "POLL");
snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
state->exit_latency = 0;
state->target_residency = 0;
state->power_usage = -1;
state->enter = poll_idle;
state->disabled = false;
}
#else
static void poll_idle_init(struct cpuidle_driver *drv) {}
#endif /* !CONFIG_ARCH_HAS_CPU_RELAX */
/**
* __cpuidle_register_driver: register the driver
* @drv: a valid pointer to a struct cpuidle_driver
*
* Do some sanity checks, initialize the driver, assign the driver to the
* global cpuidle driver variable(s) and set up the broadcast timer if the
* cpuidle driver has some states that shut down the local timer.
*
* Returns 0 on success, a negative error code otherwise:
* * -EINVAL if the driver pointer is NULL or no idle states are available
* * -ENODEV if the cpuidle framework is disabled
* * -EBUSY if the driver is already assigned to the global variable(s)
*/
static int __cpuidle_register_driver(struct cpuidle_driver *drv)
{
int ret;
if (!drv || !drv->state_count)
return -EINVAL;
ret = cpuidle_coupled_state_verify(drv);
if (ret)
return ret;
if (cpuidle_disabled())
return -ENODEV;
__cpuidle_driver_init(drv);
ret = __cpuidle_set_driver(drv);
if (ret)
return ret;
if (drv->bctimer)
on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer,
(void *)1, 1);
poll_idle_init(drv);
return 0;
}
/**
* __cpuidle_unregister_driver - unregister the driver
* @drv: a valid pointer to a struct cpuidle_driver
*
* Check if the driver is no longer in use, reset the global cpuidle driver
* variable(s) and disable the timer broadcast notification mechanism if it was
* in use.
*
*/
static void __cpuidle_unregister_driver(struct cpuidle_driver *drv)
{
if (WARN_ON(drv->refcnt > 0))
return;
if (drv->bctimer) {
drv->bctimer = 0;
on_each_cpu_mask(drv->cpumask, cpuidle_setup_broadcast_timer,
NULL, 1);
}
__cpuidle_unset_driver(drv);
}
/**
* cpuidle_register_driver - registers a driver
* @drv: a pointer to a valid struct cpuidle_driver
*
* Register the driver under a lock to prevent concurrent attempts to
* [un]register the driver from occuring at the same time.
*
* Returns 0 on success, a negative error code (returned by
* __cpuidle_register_driver()) otherwise.
*/
int cpuidle_register_driver(struct cpuidle_driver *drv)
{
int ret;
spin_lock(&cpuidle_driver_lock);
ret = __cpuidle_register_driver(drv);
spin_unlock(&cpuidle_driver_lock);
return ret;
}
EXPORT_SYMBOL_GPL(cpuidle_register_driver);
/**
* cpuidle_unregister_driver - unregisters a driver
* @drv: a pointer to a valid struct cpuidle_driver
*
* Unregisters the cpuidle driver under a lock to prevent concurrent attempts
* to [un]register the driver from occuring at the same time. @drv has to
* match the currently registered driver.
*/
void cpuidle_unregister_driver(struct cpuidle_driver *drv)
{
spin_lock(&cpuidle_driver_lock);
__cpuidle_unregister_driver(drv);
spin_unlock(&cpuidle_driver_lock);
}
EXPORT_SYMBOL_GPL(cpuidle_unregister_driver);
/**
* cpuidle_get_driver - return the driver tied to the current CPU.
*
* Returns a struct cpuidle_driver pointer, or NULL if no driver is registered.
*/
struct cpuidle_driver *cpuidle_get_driver(void)
{
struct cpuidle_driver *drv;
int cpu;
cpu = get_cpu();
drv = __cpuidle_get_cpu_driver(cpu);
put_cpu();
return drv;
}
EXPORT_SYMBOL_GPL(cpuidle_get_driver);
/**
* cpuidle_get_cpu_driver - return the driver registered for a CPU.
* @dev: a valid pointer to a struct cpuidle_device
*
* Returns a struct cpuidle_driver pointer, or NULL if no driver is registered
* for the CPU associated with @dev.
*/
struct cpuidle_driver *cpuidle_get_cpu_driver(struct cpuidle_device *dev)
{
if (!dev)
return NULL;
return __cpuidle_get_cpu_driver(dev->cpu);
}
EXPORT_SYMBOL_GPL(cpuidle_get_cpu_driver);
/**
* cpuidle_driver_ref - get a reference to the driver.
*
* Increment the reference counter of the cpuidle driver associated with
* the current CPU.
*
* Returns a pointer to the driver, or NULL if the current CPU has no driver.
*/
struct cpuidle_driver *cpuidle_driver_ref(void)
{
struct cpuidle_driver *drv;
spin_lock(&cpuidle_driver_lock);
drv = cpuidle_get_driver();
if (drv)
drv->refcnt++;
spin_unlock(&cpuidle_driver_lock);
return drv;
}
/**
* cpuidle_driver_unref - puts down the refcount for the driver
*
* Decrement the reference counter of the cpuidle driver associated with
* the current CPU.
*/
void cpuidle_driver_unref(void)
{
struct cpuidle_driver *drv;
spin_lock(&cpuidle_driver_lock);
drv = cpuidle_get_driver();
if (drv && !WARN_ON(drv->refcnt <= 0))
drv->refcnt--;
spin_unlock(&cpuidle_driver_lock);
}