v4.19.13 snapshot.
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
new file mode 100644
index 0000000..16f8414
--- /dev/null
+++ b/kernel/sched/idle.c
@@ -0,0 +1,482 @@
+/*
+ * Generic entry points for the idle threads and
+ * implementation of the idle task scheduling class.
+ *
+ * (NOTE: these are not related to SCHED_IDLE batch scheduled
+ * tasks which are handled in sched/fair.c )
+ */
+#include "sched.h"
+
+#include <trace/events/power.h>
+
+/* Linker adds these: start and end of __cpuidle functions */
+extern char __cpuidle_text_start[], __cpuidle_text_end[];
+
+/**
+ * sched_idle_set_state - Record idle state for the current CPU.
+ * @idle_state: State to record.
+ */
+void sched_idle_set_state(struct cpuidle_state *idle_state)
+{
+ idle_set_state(this_rq(), idle_state);
+}
+
+static int __read_mostly cpu_idle_force_poll;
+
+void cpu_idle_poll_ctrl(bool enable)
+{
+ if (enable) {
+ cpu_idle_force_poll++;
+ } else {
+ cpu_idle_force_poll--;
+ WARN_ON_ONCE(cpu_idle_force_poll < 0);
+ }
+}
+
+#ifdef CONFIG_GENERIC_IDLE_POLL_SETUP
+static int __init cpu_idle_poll_setup(char *__unused)
+{
+ cpu_idle_force_poll = 1;
+
+ return 1;
+}
+__setup("nohlt", cpu_idle_poll_setup);
+
+static int __init cpu_idle_nopoll_setup(char *__unused)
+{
+ cpu_idle_force_poll = 0;
+
+ return 1;
+}
+__setup("hlt", cpu_idle_nopoll_setup);
+#endif
+
+static noinline int __cpuidle cpu_idle_poll(void)
+{
+ rcu_idle_enter();
+ trace_cpu_idle_rcuidle(0, smp_processor_id());
+ local_irq_enable();
+ stop_critical_timings();
+
+ while (!tif_need_resched() &&
+ (cpu_idle_force_poll || tick_check_broadcast_expired()))
+ cpu_relax();
+ start_critical_timings();
+ trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
+ rcu_idle_exit();
+
+ return 1;
+}
+
+/* Weak implementations for optional arch specific functions */
+void __weak arch_cpu_idle_prepare(void) { }
+void __weak arch_cpu_idle_enter(void) { }
+void __weak arch_cpu_idle_exit(void) { }
+void __weak arch_cpu_idle_dead(void) { }
+void __weak arch_cpu_idle(void)
+{
+ cpu_idle_force_poll = 1;
+ local_irq_enable();
+}
+
+/**
+ * default_idle_call - Default CPU idle routine.
+ *
+ * To use when the cpuidle framework cannot be used.
+ */
+void __cpuidle default_idle_call(void)
+{
+ if (current_clr_polling_and_test()) {
+ local_irq_enable();
+ } else {
+ stop_critical_timings();
+ arch_cpu_idle();
+ start_critical_timings();
+ }
+}
+
+static int call_cpuidle(struct cpuidle_driver *drv, struct cpuidle_device *dev,
+ int next_state)
+{
+ /*
+ * The idle task must be scheduled, it is pointless to go to idle, just
+ * update no idle residency and return.
+ */
+ if (current_clr_polling_and_test()) {
+ dev->last_residency = 0;
+ local_irq_enable();
+ return -EBUSY;
+ }
+
+ /*
+ * Enter the idle state previously returned by the governor decision.
+ * This function will block until an interrupt occurs and will take
+ * care of re-enabling the local interrupts
+ */
+ return cpuidle_enter(drv, dev, next_state);
+}
+
+/**
+ * cpuidle_idle_call - the main idle function
+ *
+ * NOTE: no locks or semaphores should be used here
+ *
+ * On archs that support TIF_POLLING_NRFLAG, is called with polling
+ * set, and it returns with polling set. If it ever stops polling, it
+ * must clear the polling bit.
+ */
+static void cpuidle_idle_call(void)
+{
+ struct cpuidle_device *dev = cpuidle_get_device();
+ struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
+ int next_state, entered_state;
+
+ /*
+ * Check if the idle task must be rescheduled. If it is the
+ * case, exit the function after re-enabling the local irq.
+ */
+ if (need_resched()) {
+ local_irq_enable();
+ return;
+ }
+
+ /*
+ * The RCU framework needs to be told that we are entering an idle
+ * section, so no more rcu read side critical sections and one more
+ * step to the grace period
+ */
+
+ if (cpuidle_not_available(drv, dev)) {
+ tick_nohz_idle_stop_tick();
+ rcu_idle_enter();
+
+ default_idle_call();
+ goto exit_idle;
+ }
+
+ /*
+ * Suspend-to-idle ("s2idle") is a system state in which all user space
+ * has been frozen, all I/O devices have been suspended and the only
+ * activity happens here and in iterrupts (if any). In that case bypass
+ * the cpuidle governor and go stratight for the deepest idle state
+ * available. Possibly also suspend the local tick and the entire
+ * timekeeping to prevent timer interrupts from kicking us out of idle
+ * until a proper wakeup interrupt happens.
+ */
+
+ if (idle_should_enter_s2idle() || dev->use_deepest_state) {
+ if (idle_should_enter_s2idle()) {
+ rcu_idle_enter();
+
+ entered_state = cpuidle_enter_s2idle(drv, dev);
+ if (entered_state > 0) {
+ local_irq_enable();
+ goto exit_idle;
+ }
+
+ rcu_idle_exit();
+ }
+
+ tick_nohz_idle_stop_tick();
+ rcu_idle_enter();
+
+ next_state = cpuidle_find_deepest_state(drv, dev);
+ call_cpuidle(drv, dev, next_state);
+ } else {
+ bool stop_tick = true;
+
+ /*
+ * Ask the cpuidle framework to choose a convenient idle state.
+ */
+ next_state = cpuidle_select(drv, dev, &stop_tick);
+
+ if (stop_tick || tick_nohz_tick_stopped())
+ tick_nohz_idle_stop_tick();
+ else
+ tick_nohz_idle_retain_tick();
+
+ rcu_idle_enter();
+
+ entered_state = call_cpuidle(drv, dev, next_state);
+ /*
+ * Give the governor an opportunity to reflect on the outcome
+ */
+ cpuidle_reflect(dev, entered_state);
+ }
+
+exit_idle:
+ __current_set_polling();
+
+ /*
+ * It is up to the idle functions to reenable local interrupts
+ */
+ if (WARN_ON_ONCE(irqs_disabled()))
+ local_irq_enable();
+
+ rcu_idle_exit();
+}
+
+/*
+ * Generic idle loop implementation
+ *
+ * Called with polling cleared.
+ */
+static void do_idle(void)
+{
+ int cpu = smp_processor_id();
+ /*
+ * 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(cpu)) {
+ tick_nohz_idle_stop_tick_protected();
+ 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()) {
+ tick_nohz_idle_restart_tick();
+ 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_idle();
+
+ if (unlikely(klp_patch_pending(current)))
+ klp_update_patch_state(current);
+}
+
+bool cpu_in_idle(unsigned long pc)
+{
+ return pc >= (unsigned long)__cpuidle_text_start &&
+ pc < (unsigned long)__cpuidle_text_end;
+}
+
+struct idle_timer {
+ struct hrtimer timer;
+ int done;
+};
+
+static enum hrtimer_restart idle_inject_timer_fn(struct hrtimer *timer)
+{
+ struct idle_timer *it = container_of(timer, struct idle_timer, timer);
+
+ WRITE_ONCE(it->done, 1);
+ set_tsk_need_resched(current);
+
+ return HRTIMER_NORESTART;
+}
+
+void play_idle(unsigned long duration_ms)
+{
+ struct idle_timer it;
+
+ /*
+ * Only FIFO tasks can disable the tick since they don't need the forced
+ * preemption.
+ */
+ WARN_ON_ONCE(current->policy != SCHED_FIFO);
+ WARN_ON_ONCE(current->nr_cpus_allowed != 1);
+ WARN_ON_ONCE(!(current->flags & PF_KTHREAD));
+ WARN_ON_ONCE(!(current->flags & PF_NO_SETAFFINITY));
+ WARN_ON_ONCE(!duration_ms);
+
+ rcu_sleep_check();
+ preempt_disable();
+ current->flags |= PF_IDLE;
+ cpuidle_use_deepest_state(true);
+
+ it.done = 0;
+ hrtimer_init_on_stack(&it.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+ it.timer.function = idle_inject_timer_fn;
+ hrtimer_start(&it.timer, ms_to_ktime(duration_ms), HRTIMER_MODE_REL_PINNED);
+
+ while (!READ_ONCE(it.done))
+ do_idle();
+
+ cpuidle_use_deepest_state(false);
+ current->flags &= ~PF_IDLE;
+
+ preempt_fold_need_resched();
+ preempt_enable();
+}
+EXPORT_SYMBOL_GPL(play_idle);
+
+void cpu_startup_entry(enum cpuhp_state state)
+{
+ /*
+ * This #ifdef needs to die, but it's too late in the cycle to
+ * make this generic (ARM and SH have never invoked the canary
+ * init for the non boot CPUs!). Will be fixed in 3.11
+ */
+#ifdef CONFIG_X86
+ /*
+ * If we're the non-boot CPU, nothing set the stack canary up
+ * for us. The boot CPU 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();
+#endif
+ arch_cpu_idle_prepare();
+ cpuhp_online_idle(state);
+ while (1)
+ do_idle();
+}
+
+/*
+ * idle-task scheduling class.
+ */
+
+#ifdef CONFIG_SMP
+static int
+select_task_rq_idle(struct task_struct *p, int cpu, int sd_flag, int flags)
+{
+ return task_cpu(p); /* IDLE tasks as never migrated */
+}
+#endif
+
+/*
+ * Idle tasks are unconditionally rescheduled:
+ */
+static void check_preempt_curr_idle(struct rq *rq, struct task_struct *p, int flags)
+{
+ resched_curr(rq);
+}
+
+static struct task_struct *
+pick_next_task_idle(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
+{
+ put_prev_task(rq, prev);
+ update_idle_core(rq);
+ schedstat_inc(rq->sched_goidle);
+
+ return rq->idle;
+}
+
+/*
+ * It is not legal to sleep in the idle task - print a warning
+ * message if some code attempts to do it:
+ */
+static void
+dequeue_task_idle(struct rq *rq, struct task_struct *p, int flags)
+{
+ raw_spin_unlock_irq(&rq->lock);
+ printk(KERN_ERR "bad: scheduling from the idle thread!\n");
+ dump_stack();
+ raw_spin_lock_irq(&rq->lock);
+}
+
+static void put_prev_task_idle(struct rq *rq, struct task_struct *prev)
+{
+}
+
+/*
+ * scheduler tick hitting a task of our scheduling class.
+ *
+ * NOTE: This function can be called remotely by the tick offload that
+ * goes along full dynticks. Therefore no local assumption can be made
+ * and everything must be accessed through the @rq and @curr passed in
+ * parameters.
+ */
+static void task_tick_idle(struct rq *rq, struct task_struct *curr, int queued)
+{
+}
+
+static void set_curr_task_idle(struct rq *rq)
+{
+}
+
+static void switched_to_idle(struct rq *rq, struct task_struct *p)
+{
+ BUG();
+}
+
+static void
+prio_changed_idle(struct rq *rq, struct task_struct *p, int oldprio)
+{
+ BUG();
+}
+
+static unsigned int get_rr_interval_idle(struct rq *rq, struct task_struct *task)
+{
+ return 0;
+}
+
+static void update_curr_idle(struct rq *rq)
+{
+}
+
+/*
+ * Simple, special scheduling class for the per-CPU idle tasks:
+ */
+const struct sched_class idle_sched_class = {
+ /* .next is NULL */
+ /* no enqueue/yield_task for idle tasks */
+
+ /* dequeue is not valid, we print a debug message there: */
+ .dequeue_task = dequeue_task_idle,
+
+ .check_preempt_curr = check_preempt_curr_idle,
+
+ .pick_next_task = pick_next_task_idle,
+ .put_prev_task = put_prev_task_idle,
+
+#ifdef CONFIG_SMP
+ .select_task_rq = select_task_rq_idle,
+ .set_cpus_allowed = set_cpus_allowed_common,
+#endif
+
+ .set_curr_task = set_curr_task_idle,
+ .task_tick = task_tick_idle,
+
+ .get_rr_interval = get_rr_interval_idle,
+
+ .prio_changed = prio_changed_idle,
+ .switched_to = switched_to_idle,
+ .update_curr = update_curr_idle,
+};