blob: 277f494c2a9ae695c9a61dd44e5a2bfe68d75b2c [file] [log] [blame]
Thomas Gleixnera1a04ec2013-03-21 22:49:34 +01001/*
2 * Generic entry point for the idle threads
3 */
4#include <linux/sched.h>
5#include <linux/cpu.h>
Thomas Gleixnerd1669912013-03-21 22:49:35 +01006#include <linux/tick.h>
7#include <linux/mm.h>
Thomas Gleixnerd7880812013-06-10 16:52:03 +02008#include <linux/stackprotector.h>
Thomas Gleixnera1a04ec2013-03-21 22:49:34 +01009
Thomas Gleixnerd1669912013-03-21 22:49:35 +010010#include <asm/tlb.h>
11
12#include <trace/events/power.h>
13
Thomas Gleixnerd1669912013-03-21 22:49:35 +010014static int __read_mostly cpu_idle_force_poll;
15
16void 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
27static 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
34static 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
42static inline int cpu_idle_poll(void)
43{
Srivatsa S. Bhatb47430d2013-05-14 04:01:27 +053044 rcu_idle_enter();
Thomas Gleixnerd1669912013-03-21 22:49:35 +010045 trace_cpu_idle_rcuidle(0, smp_processor_id());
46 local_irq_enable();
Peter Zijlstraea811742013-09-11 12:43:13 +020047 while (!tif_need_resched())
Thomas Gleixnerd1669912013-03-21 22:49:35 +010048 cpu_relax();
49 trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
Srivatsa S. Bhatb47430d2013-05-14 04:01:27 +053050 rcu_idle_exit();
Thomas Gleixnerd1669912013-03-21 22:49:35 +010051 return 1;
52}
53
54/* Weak implementations for optional arch specific functions */
55void __weak arch_cpu_idle_prepare(void) { }
56void __weak arch_cpu_idle_enter(void) { }
57void __weak arch_cpu_idle_exit(void) { }
58void __weak arch_cpu_idle_dead(void) { }
59void __weak arch_cpu_idle(void)
60{
61 cpu_idle_force_poll = 1;
James Bottomley29ce3782013-05-08 14:05:34 -070062 local_irq_enable();
Thomas Gleixnerd1669912013-03-21 22:49:35 +010063}
64
65/*
66 * Generic idle loop implementation
67 */
68static 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 Torvaldsab86e972013-04-30 08:15:40 -070083 /*
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 Gleixnerd1669912013-03-21 22:49:35 +010093 cpu_idle_poll();
94 } else {
Peter Zijlstraea811742013-09-11 12:43:13 +020095 if (!current_clr_polling_and_test()) {
Thomas Gleixnerd1669912013-03-21 22:49:35 +010096 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 Zijlstraea811742013-09-11 12:43:13 +0200105 __current_set_polling();
Thomas Gleixnerd1669912013-03-21 22:49:35 +0100106 }
107 arch_cpu_idle_exit();
108 }
Peter Zijlstra8cb75e02013-11-20 12:22:37 +0100109
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 Gleixnerd1669912013-03-21 22:49:35 +0100119 tick_nohz_idle_exit();
120 schedule_preempt_disabled();
121 }
122}
123
124void cpu_startup_entry(enum cpuhp_state state)
125{
Thomas Gleixnerd7880812013-06-10 16:52:03 +0200126 /*
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 Zijlstraea811742013-09-11 12:43:13 +0200141 __current_set_polling();
Thomas Gleixnerd1669912013-03-21 22:49:35 +0100142 arch_cpu_idle_prepare();
143 cpu_idle_loop();
144}