Thomas Gleixner | a1a04ec | 2013-03-21 22:49:34 +0100 | [diff] [blame] | 1 | /* |
| 2 | * Generic entry point for the idle threads |
| 3 | */ |
| 4 | #include <linux/sched.h> |
| 5 | #include <linux/cpu.h> |
Thomas Gleixner | d166991 | 2013-03-21 22:49:35 +0100 | [diff] [blame] | 6 | #include <linux/tick.h> |
| 7 | #include <linux/mm.h> |
Thomas Gleixner | d788081 | 2013-06-10 16:52:03 +0200 | [diff] [blame] | 8 | #include <linux/stackprotector.h> |
Thomas Gleixner | a1a04ec | 2013-03-21 22:49:34 +0100 | [diff] [blame] | 9 | |
Thomas Gleixner | d166991 | 2013-03-21 22:49:35 +0100 | [diff] [blame] | 10 | #include <asm/tlb.h> |
| 11 | |
| 12 | #include <trace/events/power.h> |
| 13 | |
Thomas Gleixner | d166991 | 2013-03-21 22:49:35 +0100 | [diff] [blame] | 14 | static int __read_mostly cpu_idle_force_poll; |
| 15 | |
| 16 | void cpu_idle_poll_ctrl(bool enable) |
| 17 | { |
| 18 | if (enable) { |
| 19 | cpu_idle_force_poll++; |
| 20 | } else { |
| 21 | cpu_idle_force_poll--; |
| 22 | WARN_ON_ONCE(cpu_idle_force_poll < 0); |
| 23 | } |
| 24 | } |
| 25 | |
| 26 | #ifdef CONFIG_GENERIC_IDLE_POLL_SETUP |
| 27 | static int __init cpu_idle_poll_setup(char *__unused) |
| 28 | { |
| 29 | cpu_idle_force_poll = 1; |
| 30 | return 1; |
| 31 | } |
| 32 | __setup("nohlt", cpu_idle_poll_setup); |
| 33 | |
| 34 | static int __init cpu_idle_nopoll_setup(char *__unused) |
| 35 | { |
| 36 | cpu_idle_force_poll = 0; |
| 37 | return 1; |
| 38 | } |
| 39 | __setup("hlt", cpu_idle_nopoll_setup); |
| 40 | #endif |
| 41 | |
| 42 | static inline int cpu_idle_poll(void) |
| 43 | { |
Srivatsa S. Bhat | b47430d | 2013-05-14 04:01:27 +0530 | [diff] [blame] | 44 | rcu_idle_enter(); |
Thomas Gleixner | d166991 | 2013-03-21 22:49:35 +0100 | [diff] [blame] | 45 | trace_cpu_idle_rcuidle(0, smp_processor_id()); |
| 46 | local_irq_enable(); |
Peter Zijlstra | ea81174 | 2013-09-11 12:43:13 +0200 | [diff] [blame] | 47 | while (!tif_need_resched()) |
Thomas Gleixner | d166991 | 2013-03-21 22:49:35 +0100 | [diff] [blame] | 48 | cpu_relax(); |
| 49 | trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id()); |
Srivatsa S. Bhat | b47430d | 2013-05-14 04:01:27 +0530 | [diff] [blame] | 50 | rcu_idle_exit(); |
Thomas Gleixner | d166991 | 2013-03-21 22:49:35 +0100 | [diff] [blame] | 51 | return 1; |
| 52 | } |
| 53 | |
| 54 | /* Weak implementations for optional arch specific functions */ |
| 55 | void __weak arch_cpu_idle_prepare(void) { } |
| 56 | void __weak arch_cpu_idle_enter(void) { } |
| 57 | void __weak arch_cpu_idle_exit(void) { } |
| 58 | void __weak arch_cpu_idle_dead(void) { } |
| 59 | void __weak arch_cpu_idle(void) |
| 60 | { |
| 61 | cpu_idle_force_poll = 1; |
James Bottomley | 29ce378 | 2013-05-08 14:05:34 -0700 | [diff] [blame] | 62 | local_irq_enable(); |
Thomas Gleixner | d166991 | 2013-03-21 22:49:35 +0100 | [diff] [blame] | 63 | } |
| 64 | |
| 65 | /* |
| 66 | * Generic idle loop implementation |
| 67 | */ |
| 68 | static void cpu_idle_loop(void) |
| 69 | { |
| 70 | while (1) { |
| 71 | tick_nohz_idle_enter(); |
| 72 | |
| 73 | while (!need_resched()) { |
| 74 | check_pgt_cache(); |
| 75 | rmb(); |
| 76 | |
| 77 | if (cpu_is_offline(smp_processor_id())) |
| 78 | arch_cpu_idle_dead(); |
| 79 | |
| 80 | local_irq_disable(); |
| 81 | arch_cpu_idle_enter(); |
| 82 | |
Linus Torvalds | ab86e97 | 2013-04-30 08:15:40 -0700 | [diff] [blame] | 83 | /* |
| 84 | * In poll mode we reenable interrupts and spin. |
| 85 | * |
| 86 | * Also if we detected in the wakeup from idle |
| 87 | * path that the tick broadcast device expired |
| 88 | * for us, we don't want to go deep idle as we |
| 89 | * know that the IPI is going to arrive right |
| 90 | * away |
| 91 | */ |
| 92 | if (cpu_idle_force_poll || tick_check_broadcast_expired()) { |
Thomas Gleixner | d166991 | 2013-03-21 22:49:35 +0100 | [diff] [blame] | 93 | cpu_idle_poll(); |
| 94 | } else { |
Peter Zijlstra | ea81174 | 2013-09-11 12:43:13 +0200 | [diff] [blame] | 95 | if (!current_clr_polling_and_test()) { |
Thomas Gleixner | d166991 | 2013-03-21 22:49:35 +0100 | [diff] [blame] | 96 | stop_critical_timings(); |
| 97 | rcu_idle_enter(); |
| 98 | arch_cpu_idle(); |
| 99 | WARN_ON_ONCE(irqs_disabled()); |
| 100 | rcu_idle_exit(); |
| 101 | start_critical_timings(); |
| 102 | } else { |
| 103 | local_irq_enable(); |
| 104 | } |
Peter Zijlstra | ea81174 | 2013-09-11 12:43:13 +0200 | [diff] [blame] | 105 | __current_set_polling(); |
Thomas Gleixner | d166991 | 2013-03-21 22:49:35 +0100 | [diff] [blame] | 106 | } |
| 107 | arch_cpu_idle_exit(); |
| 108 | } |
Peter Zijlstra | 8cb75e0 | 2013-11-20 12:22:37 +0100 | [diff] [blame] | 109 | |
| 110 | /* |
| 111 | * Since we fell out of the loop above, we know |
| 112 | * TIF_NEED_RESCHED must be set, propagate it into |
| 113 | * PREEMPT_NEED_RESCHED. |
| 114 | * |
| 115 | * This is required because for polling idle loops we will |
| 116 | * not have had an IPI to fold the state for us. |
| 117 | */ |
| 118 | preempt_set_need_resched(); |
Thomas Gleixner | d166991 | 2013-03-21 22:49:35 +0100 | [diff] [blame] | 119 | tick_nohz_idle_exit(); |
| 120 | schedule_preempt_disabled(); |
| 121 | } |
| 122 | } |
| 123 | |
| 124 | void cpu_startup_entry(enum cpuhp_state state) |
| 125 | { |
Thomas Gleixner | d788081 | 2013-06-10 16:52:03 +0200 | [diff] [blame] | 126 | /* |
| 127 | * This #ifdef needs to die, but it's too late in the cycle to |
| 128 | * make this generic (arm and sh have never invoked the canary |
| 129 | * init for the non boot cpus!). Will be fixed in 3.11 |
| 130 | */ |
| 131 | #ifdef CONFIG_X86 |
| 132 | /* |
| 133 | * If we're the non-boot CPU, nothing set the stack canary up |
| 134 | * for us. The boot CPU already has it initialized but no harm |
| 135 | * in doing it again. This is a good place for updating it, as |
| 136 | * we wont ever return from this function (so the invalid |
| 137 | * canaries already on the stack wont ever trigger). |
| 138 | */ |
| 139 | boot_init_stack_canary(); |
| 140 | #endif |
Peter Zijlstra | ea81174 | 2013-09-11 12:43:13 +0200 | [diff] [blame] | 141 | __current_set_polling(); |
Thomas Gleixner | d166991 | 2013-03-21 22:49:35 +0100 | [diff] [blame] | 142 | arch_cpu_idle_prepare(); |
| 143 | cpu_idle_loop(); |
| 144 | } |