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Commit | Line | Data |
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a1a04ec3 TG |
1 | /* |
2 | * Generic entry point for the idle threads | |
3 | */ | |
4 | #include <linux/sched.h> | |
5 | #include <linux/cpu.h> | |
d1669912 TG |
6 | #include <linux/tick.h> |
7 | #include <linux/mm.h> | |
d7880812 | 8 | #include <linux/stackprotector.h> |
a1a04ec3 | 9 | |
d1669912 TG |
10 | #include <asm/tlb.h> |
11 | ||
12 | #include <trace/events/power.h> | |
13 | ||
d1669912 TG |
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 | { | |
b47430d3 | 44 | rcu_idle_enter(); |
d1669912 TG |
45 | trace_cpu_idle_rcuidle(0, smp_processor_id()); |
46 | local_irq_enable(); | |
47 | while (!need_resched()) | |
48 | cpu_relax(); | |
49 | trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id()); | |
b47430d3 | 50 | rcu_idle_exit(); |
d1669912 TG |
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; | |
29ce3785 | 62 | local_irq_enable(); |
d1669912 TG |
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 | ||
ab86e974 LT |
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()) { | |
d1669912 TG |
93 | cpu_idle_poll(); |
94 | } else { | |
95 | current_clr_polling(); | |
96 | if (!need_resched()) { | |
97 | stop_critical_timings(); | |
98 | rcu_idle_enter(); | |
99 | arch_cpu_idle(); | |
100 | WARN_ON_ONCE(irqs_disabled()); | |
101 | rcu_idle_exit(); | |
102 | start_critical_timings(); | |
103 | } else { | |
104 | local_irq_enable(); | |
105 | } | |
106 | current_set_polling(); | |
107 | } | |
108 | arch_cpu_idle_exit(); | |
109 | } | |
110 | tick_nohz_idle_exit(); | |
111 | schedule_preempt_disabled(); | |
112 | } | |
113 | } | |
114 | ||
115 | void cpu_startup_entry(enum cpuhp_state state) | |
116 | { | |
d7880812 TG |
117 | /* |
118 | * This #ifdef needs to die, but it's too late in the cycle to | |
119 | * make this generic (arm and sh have never invoked the canary | |
120 | * init for the non boot cpus!). Will be fixed in 3.11 | |
121 | */ | |
122 | #ifdef CONFIG_X86 | |
123 | /* | |
124 | * If we're the non-boot CPU, nothing set the stack canary up | |
125 | * for us. The boot CPU already has it initialized but no harm | |
126 | * in doing it again. This is a good place for updating it, as | |
127 | * we wont ever return from this function (so the invalid | |
128 | * canaries already on the stack wont ever trigger). | |
129 | */ | |
130 | boot_init_stack_canary(); | |
131 | #endif | |
d1669912 TG |
132 | current_set_polling(); |
133 | arch_cpu_idle_prepare(); | |
134 | cpu_idle_loop(); | |
135 | } |