From 2c3c1048746a4622d8c89a29670120dc8fab93c4 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 20:49:45 +0200 Subject: Adding upstream version 6.1.76. Signed-off-by: Daniel Baumann --- kernel/sched/idle.c | 524 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 524 insertions(+) create mode 100644 kernel/sched/idle.c (limited to 'kernel/sched/idle.c') diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c new file mode 100644 index 000000000..200a0fac0 --- /dev/null +++ b/kernel/sched/idle.c @@ -0,0 +1,524 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * 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 ) + */ + +/* 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) +{ + trace_cpu_idle(0, smp_processor_id()); + stop_critical_timings(); + ct_idle_enter(); + local_irq_enable(); + + while (!tif_need_resched() && + (cpu_idle_force_poll || tick_check_broadcast_expired())) + cpu_relax(); + + ct_idle_exit(); + start_critical_timings(); + trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id()); + + 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; + raw_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 { + + trace_cpu_idle(1, smp_processor_id()); + stop_critical_timings(); + + /* + * arch_cpu_idle() is supposed to enable IRQs, however + * we can't do that because of RCU and tracing. + * + * Trace IRQs enable here, then switch off RCU, and have + * arch_cpu_idle() use raw_local_irq_enable(). Note that + * ct_idle_enter() relies on lockdep IRQ state, so switch that + * last -- this is very similar to the entry code. + */ + trace_hardirqs_on_prepare(); + lockdep_hardirqs_on_prepare(); + ct_idle_enter(); + lockdep_hardirqs_on(_THIS_IP_); + + arch_cpu_idle(); + + /* + * OK, so IRQs are enabled here, but RCU needs them disabled to + * turn itself back on.. funny thing is that disabling IRQs + * will cause tracing, which needs RCU. Jump through hoops to + * make it 'work'. + */ + raw_local_irq_disable(); + lockdep_hardirqs_off(_THIS_IP_); + ct_idle_exit(); + lockdep_hardirqs_on(_THIS_IP_); + raw_local_irq_enable(); + + start_critical_timings(); + trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id()); + } +} + +static int call_cpuidle_s2idle(struct cpuidle_driver *drv, + struct cpuidle_device *dev) +{ + if (current_clr_polling_and_test()) + return -EBUSY; + + return cpuidle_enter_s2idle(drv, dev); +} + +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_ns = 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 architectures 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(); + + 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 interrupts (if any). In that case bypass + * the cpuidle governor and go straight 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->forced_idle_latency_limit_ns) { + u64 max_latency_ns; + + if (idle_should_enter_s2idle()) { + + entered_state = call_cpuidle_s2idle(drv, dev); + if (entered_state > 0) + goto exit_idle; + + max_latency_ns = U64_MAX; + } else { + max_latency_ns = dev->forced_idle_latency_limit_ns; + } + + tick_nohz_idle_stop_tick(); + + next_state = cpuidle_find_deepest_state(drv, dev, max_latency_ns); + 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(); + + 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(); +} + +/* + * Generic idle loop implementation + * + * Called with polling cleared. + */ +static void do_idle(void) +{ + int cpu = smp_processor_id(); + + /* + * Check if we need to update blocked load + */ + nohz_run_idle_balance(cpu); + + /* + * 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()) { + rmb(); + + local_irq_disable(); + + if (cpu_is_offline(cpu)) { + tick_nohz_idle_stop_tick(); + cpuhp_report_idle_dead(); + arch_cpu_idle_dead(); + } + + arch_cpu_idle_enter(); + rcu_nocb_flush_deferred_wakeup(); + + /* + * 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(); + + /* + * RCU relies on this call to be done outside of an RCU read-side + * critical section. + */ + flush_smp_call_function_queue(); + 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_precise(u64 duration_ns, u64 latency_ns) +{ + 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_ns); + WARN_ON_ONCE(current->mm); + + rcu_sleep_check(); + preempt_disable(); + current->flags |= PF_IDLE; + cpuidle_use_deepest_state(latency_ns); + + it.done = 0; + hrtimer_init_on_stack(&it.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD); + it.timer.function = idle_inject_timer_fn; + hrtimer_start(&it.timer, ns_to_ktime(duration_ns), + HRTIMER_MODE_REL_PINNED_HARD); + + while (!READ_ONCE(it.done)) + do_idle(); + + cpuidle_use_deepest_state(0); + current->flags &= ~PF_IDLE; + + preempt_fold_need_resched(); + preempt_enable(); +} +EXPORT_SYMBOL_GPL(play_idle_precise); + +void cpu_startup_entry(enum cpuhp_state state) +{ + current->flags |= PF_IDLE; + 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 flags) +{ + return task_cpu(p); /* IDLE tasks as never migrated */ +} + +static int +balance_idle(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) +{ + return WARN_ON_ONCE(1); +} +#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 void put_prev_task_idle(struct rq *rq, struct task_struct *prev) +{ +} + +static void set_next_task_idle(struct rq *rq, struct task_struct *next, bool first) +{ + update_idle_core(rq); + schedstat_inc(rq->sched_goidle); +} + +#ifdef CONFIG_SMP +static struct task_struct *pick_task_idle(struct rq *rq) +{ + return rq->idle; +} +#endif + +struct task_struct *pick_next_task_idle(struct rq *rq) +{ + struct task_struct *next = rq->idle; + + set_next_task_idle(rq, next, true); + + return next; +} + +/* + * 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_rq_unlock_irq(rq); + printk(KERN_ERR "bad: scheduling from the idle thread!\n"); + dump_stack(); + raw_spin_rq_lock_irq(rq); +} + +/* + * 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 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 void update_curr_idle(struct rq *rq) +{ +} + +/* + * Simple, special scheduling class for the per-CPU idle tasks: + */ +DEFINE_SCHED_CLASS(idle) = { + + /* 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, + .set_next_task = set_next_task_idle, + +#ifdef CONFIG_SMP + .balance = balance_idle, + .pick_task = pick_task_idle, + .select_task_rq = select_task_rq_idle, + .set_cpus_allowed = set_cpus_allowed_common, +#endif + + .task_tick = task_tick_idle, + + .prio_changed = prio_changed_idle, + .switched_to = switched_to_idle, + .update_curr = update_curr_idle, +}; -- cgit v1.2.3