/* * Generic entry point for the idle threads */ #include <linux/sched.h> #include <linux/cpu.h> #include <linux/tick.h> #include <linux/mm.h> #include <asm/tlb.h> #include <trace/events/power.h> 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 inline int cpu_idle_poll(void) { trace_cpu_idle_rcuidle(0, smp_processor_id()); local_irq_enable(); while (!need_resched()) cpu_relax(); trace_cpu_idle_rcuidle(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; } /* * 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 { current_clr_polling(); if (!need_resched()) { stop_critical_timings(); rcu_idle_enter(); arch_cpu_idle(); WARN_ON_ONCE(irqs_disabled()); rcu_idle_exit(); start_critical_timings(); } else { local_irq_enable(); } current_set_polling(); } arch_cpu_idle_exit(); } tick_nohz_idle_exit(); schedule_preempt_disabled(); } } void cpu_startup_entry(enum cpuhp_state state) { current_set_polling(); arch_cpu_idle_prepare(); cpu_idle_loop(); }