/*
* Generic idle loop implementation
*
* Called with polling cleared.
*/
static void do_idle(void)
{
/*
* If the arch has a polling bit, we maintain an invariant:
*
* Our polling bit is clear if we're not scheduled (i.e. if rq->curr !=
* rq->idle). This means that, if rq->idle has the polling bit set,
* then setting need_resched is guaranteed to cause the CPU to
* reschedule.
*/
__current_set_polling();
tick_nohz_idle_enter();
while (!need_resched()) {
check_pgt_cache();
rmb();
if (cpu_is_offline(smp_processor_id())) {
cpuhp_report_idle_dead();
arch_cpu_idle_dead();
}
local_irq_disable();
arch_cpu_idle_enter();
/*
* In poll mode we reenable interrupts and spin. Also if we
* detected in the wakeup from idle path that the tick
* broadcast device expired for us, we don't want to go deep
* idle as we know that the IPI is going to arrive right away.
*/
if (cpu_idle_force_poll || tick_check_broadcast_expired())
cpu_idle_poll();
else
cpuidle_idle_call();
arch_cpu_idle_exit();
}
/*
* Since we fell out of the loop above, we know TIF_NEED_RESCHED must
* be set, propagate it into PREEMPT_NEED_RESCHED.
*
* This is required because for polling idle loops we will not have had
* an IPI to fold the state for us.
*/
preempt_set_need_resched();
tick_nohz_idle_exit();
__current_clr_polling();
/*
* We promise to call sched_ttwu_pending() and reschedule if
* need_resched() is set while polling is set. That means that clearing
* polling needs to be visible before doing these things.
*/
smp_mb__after_atomic();
sched_ttwu_pending();
schedule_preempt_disabled();
}
/*
* Generic idle loop implementation
*
* Called with polling cleared.
*/
static void cpu_idle_loop(void)
{
while (1) {
/*
* If the arch has a polling bit, we maintain an invariant:
*
* Our polling bit is clear if we're not scheduled (i.e. if
* rq->curr != rq->idle). This means that, if rq->idle has
* the polling bit set, then setting need_resched is
* guaranteed to cause the cpu to reschedule.
*/
__current_set_polling();
tick_nohz_idle_enter();
while (!need_resched()) {
check_pgt_cache();
rmb();
local_irq_disable();
arch_cpu_idle_enter();
/*
* In poll mode we reenable interrupts and spin.
*
* Also if we detected in the wakeup from idle
* path that the tick broadcast device expired
* for us, we don't want to go deep idle as we
* know that the IPI is going to arrive right
* away
*/
if (cpu_idle_force_poll ||
tick_check_broadcast_expired() ||
__get_cpu_var(idle_force_poll))
cpu_idle_poll();
else
cpuidle_idle_call();
arch_cpu_idle_exit();
}
tick_nohz_idle_exit();
__current_clr_polling();
/*
* We promise to reschedule if need_resched is set while
* polling is set. That means that clearing polling
* needs to be visible before rescheduling.
*/
smp_mb__after_atomic();
schedule_preempt_disabled();
if (cpu_is_offline(smp_processor_id()))
arch_cpu_idle_dead();
}
}
/*
* Generic idle loop implementation
*/
static void cpu_idle_loop(void)
{
while (1) {
tick_nohz_idle_enter();
while (!need_resched()) {
check_pgt_cache();
rmb();
if (cpu_is_offline(smp_processor_id()))
arch_cpu_idle_dead();
local_irq_disable();
arch_cpu_idle_enter();
/*
* In poll mode we reenable interrupts and spin.
*
* Also if we detected in the wakeup from idle
* path that the tick broadcast device expired
* for us, we don't want to go deep idle as we
* know that the IPI is going to arrive right
* away
*/
if (cpu_idle_force_poll || tick_check_broadcast_expired())
cpu_idle_poll();
else
cpuidle_idle_call();
arch_cpu_idle_exit();
}
/*
* Since we fell out of the loop above, we know
* TIF_NEED_RESCHED must be set, propagate it into
* PREEMPT_NEED_RESCHED.
*
* This is required because for polling idle loops we will
* not have had an IPI to fold the state for us.
*/
preempt_set_need_resched();
tick_nohz_idle_exit();
schedule_preempt_disabled();
}
}
/*
* The idle thread, has rather strange semantics for calling pm_idle,
* but this is what x86 does and we need to do the same, so that
* things like cpuidle get called in the same way. The only difference
* is that we always respect 'hlt_counter' to prevent low power idle.
*/
void cpu_idle(void)
{
local_fiq_enable();
/* endless idle loop with no priority at all */
while (1) {
idle_notifier_call_chain(IDLE_START);
tick_nohz_idle_enter();
rcu_idle_enter();
while (!need_resched()) {
/*
* We need to disable interrupts here
* to ensure we don't miss a wakeup call.
*/
local_irq_disable();
#ifdef CONFIG_PL310_ERRATA_769419
wmb();
#endif
if (hlt_counter) {
local_irq_enable();
cpu_relax();
} else if (!need_resched()) {
stop_critical_timings();
if (cpuidle_idle_call())
pm_idle();
start_critical_timings();
/*
* pm_idle functions must always
* return with IRQs enabled.
*/
WARN_ON(irqs_disabled());
} else
local_irq_enable();
}
rcu_idle_exit();
tick_nohz_idle_exit();
idle_notifier_call_chain(IDLE_END);
schedule_preempt_disabled();
#ifdef CONFIG_HOTPLUG_CPU
if (cpu_is_offline(smp_processor_id()))
cpu_die();
#endif
}
}
/*
* The idle thread. There's no useful work to be
* done, so just try to conserve power and have a
* low exit latency (ie sit in a loop waiting for
* somebody to say that they'd like to reschedule)
*/
void cpu_idle(void)
{
int cpu = smp_processor_id();
/*
* If we're the non-boot CPU, nothing set the stack canary up
* for us. CPU0 already has it initialized but no harm in
* doing it again. This is a good place for updating it, as
* we wont ever return from this function (so the invalid
* canaries already on the stack wont ever trigger).
*/
boot_init_stack_canary();
current_thread_info()->status |= TS_POLLING;
/* endless idle loop with no priority at all */
while (1) {
tick_nohz_idle_enter();
rcu_idle_enter();
while (!need_resched()) {
check_pgt_cache();
rmb();
if (cpu_is_offline(cpu))
play_dead();
local_touch_nmi();
local_irq_disable();
/* Don't trace irqs off for idle */
stop_critical_timings();
if (cpuidle_idle_call())
pm_idle();
start_critical_timings();
}
rcu_idle_exit();
tick_nohz_idle_exit();
preempt_enable_no_resched();
schedule();
preempt_disable();
}
}
/*
* The idle thread. There's no useful work to be done, so just try to conserve
* power and have a low exit latency (ie sit in a loop waiting for somebody to
* say that they'd like to reschedule)
*/
void cpu_idle(void)
{
unsigned int cpu = smp_processor_id();
set_thread_flag(TIF_POLLING_NRFLAG);
/* endless idle loop with no priority at all */
while (1) {
tick_nohz_idle_enter();
rcu_idle_enter();
while (!need_resched()) {
check_pgt_cache();
rmb();
if (cpu_is_offline(cpu))
play_dead();
local_irq_disable();
/* Don't trace irqs off for idle */
stop_critical_timings();
if (cpuidle_idle_call())
sh_idle();
/*
* Sanity check to ensure that sh_idle() returns
* with IRQs enabled
*/
WARN_ON(irqs_disabled());
start_critical_timings();
}
rcu_idle_exit();
tick_nohz_idle_exit();
schedule_preempt_disabled();
}
}
/*
* Generic idle loop implementation
*
* Called with polling cleared.
*/
static void cpu_idle_loop(void)
{
while (1) {
/*
* If the arch has a polling bit, we maintain an invariant:
*
* Our polling bit is clear if we're not scheduled (i.e. if
* rq->curr != rq->idle). This means that, if rq->idle has
* the polling bit set, then setting need_resched is
* guaranteed to cause the cpu to reschedule.
*/
__current_set_polling();
quiet_vmstat();
tick_nohz_idle_enter();
while (!need_resched()) {
check_pgt_cache();
rmb();
if (cpu_is_offline(smp_processor_id())) {
rcu_cpu_notify(NULL, CPU_DYING_IDLE,
(void *)(long)smp_processor_id());
smp_mb(); /* all activity before dead. */
this_cpu_write(cpu_dead_idle, true);
arch_cpu_idle_dead();
}
local_irq_disable();
arch_cpu_idle_enter();
/*
* In poll mode we reenable interrupts and spin.
*
* Also if we detected in the wakeup from idle
* path that the tick broadcast device expired
* for us, we don't want to go deep idle as we
* know that the IPI is going to arrive right
* away
*/
if (cpu_idle_force_poll || tick_check_broadcast_expired())
cpu_idle_poll();
else
cpuidle_idle_call();
arch_cpu_idle_exit();
}
/*
* Since we fell out of the loop above, we know
* TIF_NEED_RESCHED must be set, propagate it into
* PREEMPT_NEED_RESCHED.
*
* This is required because for polling idle loops we will
* not have had an IPI to fold the state for us.
*/
preempt_set_need_resched();
tick_nohz_idle_exit();
__current_clr_polling();
/*
* We promise to call sched_ttwu_pending and reschedule
* if need_resched is set while polling is set. That
* means that clearing polling needs to be visible
* before doing these things.
*/
smp_mb__after_atomic();
sched_ttwu_pending();
schedule_preempt_disabled();
}
}
/*
* Generic idle loop implementation
*
* Called with polling cleared.
*/
static void cpu_idle_loop(void)
{
while (1) {
/*
* If the arch has a polling bit, we maintain an invariant:
*
* Our polling bit is clear if we're not scheduled (i.e. if
* rq->curr != rq->idle). This means that, if rq->idle has
* the polling bit set, then setting need_resched is
* guaranteed to cause the cpu to reschedule.
*/
__current_set_polling();
tick_nohz_idle_enter();
while (!need_resched()) {
check_pgt_cache();
rmb();
if (cpu_is_offline(smp_processor_id()))
arch_cpu_idle_dead();
local_irq_disable();
arch_cpu_idle_enter();
/*
* In poll mode we reenable interrupts and spin.
*
* Also if we detected in the wakeup from idle
* path that the tick broadcast device expired
* for us, we don't want to go deep idle as we
* know that the IPI is going to arrive right
* away
*/
if (cpu_idle_force_poll || tick_check_broadcast_expired())
cpu_idle_poll();
else
cpuidle_idle_call();
arch_cpu_idle_exit();
/*
* We need to test and propagate the TIF_NEED_RESCHED
* bit here because we might not have send the
* reschedule IPI to idle tasks.
*/
if (tif_need_resched())
set_preempt_need_resched();
}
tick_nohz_idle_exit();
__current_clr_polling();
/*
* We promise to call sched_ttwu_pending and reschedule
* if need_resched is set while polling is set. That
* means that clearing polling needs to be visible
* before doing these things.
*/
smp_mb();
sched_ttwu_pending();
schedule_preempt_disabled();
}
}