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Commit | Line | Data |
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cf37b6b4 NP |
1 | /* |
2 | * Generic entry point for the idle threads | |
3 | */ | |
4 | #include <linux/sched.h> | |
4c822698 | 5 | #include <linux/sched/idle.h> |
cf37b6b4 NP |
6 | #include <linux/cpu.h> |
7 | #include <linux/cpuidle.h> | |
8df3e07e | 8 | #include <linux/cpuhotplug.h> |
cf37b6b4 NP |
9 | #include <linux/tick.h> |
10 | #include <linux/mm.h> | |
11 | #include <linux/stackprotector.h> | |
38106313 | 12 | #include <linux/suspend.h> |
cf37b6b4 NP |
13 | |
14 | #include <asm/tlb.h> | |
15 | ||
16 | #include <trace/events/power.h> | |
17 | ||
e3baac47 PZ |
18 | #include "sched.h" |
19 | ||
6727ad9e CM |
20 | /* Linker adds these: start and end of __cpuidle functions */ |
21 | extern char __cpuidle_text_start[], __cpuidle_text_end[]; | |
22 | ||
faad3849 RW |
23 | /** |
24 | * sched_idle_set_state - Record idle state for the current CPU. | |
25 | * @idle_state: State to record. | |
26 | */ | |
27 | void sched_idle_set_state(struct cpuidle_state *idle_state) | |
28 | { | |
29 | idle_set_state(this_rq(), idle_state); | |
30 | } | |
31 | ||
cf37b6b4 NP |
32 | static int __read_mostly cpu_idle_force_poll; |
33 | ||
34 | void cpu_idle_poll_ctrl(bool enable) | |
35 | { | |
36 | if (enable) { | |
37 | cpu_idle_force_poll++; | |
38 | } else { | |
39 | cpu_idle_force_poll--; | |
40 | WARN_ON_ONCE(cpu_idle_force_poll < 0); | |
41 | } | |
42 | } | |
43 | ||
44 | #ifdef CONFIG_GENERIC_IDLE_POLL_SETUP | |
45 | static int __init cpu_idle_poll_setup(char *__unused) | |
46 | { | |
47 | cpu_idle_force_poll = 1; | |
48 | return 1; | |
49 | } | |
50 | __setup("nohlt", cpu_idle_poll_setup); | |
51 | ||
52 | static int __init cpu_idle_nopoll_setup(char *__unused) | |
53 | { | |
54 | cpu_idle_force_poll = 0; | |
55 | return 1; | |
56 | } | |
57 | __setup("hlt", cpu_idle_nopoll_setup); | |
58 | #endif | |
59 | ||
6727ad9e | 60 | static noinline int __cpuidle cpu_idle_poll(void) |
cf37b6b4 NP |
61 | { |
62 | rcu_idle_enter(); | |
63 | trace_cpu_idle_rcuidle(0, smp_processor_id()); | |
64 | local_irq_enable(); | |
9babcd79 | 65 | stop_critical_timings(); |
ff6f2d29 PM |
66 | while (!tif_need_resched() && |
67 | (cpu_idle_force_poll || tick_check_broadcast_expired())) | |
cf37b6b4 | 68 | cpu_relax(); |
9babcd79 | 69 | start_critical_timings(); |
cf37b6b4 NP |
70 | trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id()); |
71 | rcu_idle_exit(); | |
72 | return 1; | |
73 | } | |
74 | ||
75 | /* Weak implementations for optional arch specific functions */ | |
76 | void __weak arch_cpu_idle_prepare(void) { } | |
77 | void __weak arch_cpu_idle_enter(void) { } | |
78 | void __weak arch_cpu_idle_exit(void) { } | |
79 | void __weak arch_cpu_idle_dead(void) { } | |
80 | void __weak arch_cpu_idle(void) | |
81 | { | |
82 | cpu_idle_force_poll = 1; | |
83 | local_irq_enable(); | |
84 | } | |
85 | ||
827a5aef RW |
86 | /** |
87 | * default_idle_call - Default CPU idle routine. | |
88 | * | |
89 | * To use when the cpuidle framework cannot be used. | |
90 | */ | |
6727ad9e | 91 | void __cpuidle default_idle_call(void) |
82f66327 | 92 | { |
63caae84 | 93 | if (current_clr_polling_and_test()) { |
82f66327 | 94 | local_irq_enable(); |
63caae84 LS |
95 | } else { |
96 | stop_critical_timings(); | |
82f66327 | 97 | arch_cpu_idle(); |
63caae84 LS |
98 | start_critical_timings(); |
99 | } | |
82f66327 RW |
100 | } |
101 | ||
bcf6ad8a RW |
102 | static int call_cpuidle(struct cpuidle_driver *drv, struct cpuidle_device *dev, |
103 | int next_state) | |
104 | { | |
bcf6ad8a RW |
105 | /* |
106 | * The idle task must be scheduled, it is pointless to go to idle, just | |
107 | * update no idle residency and return. | |
108 | */ | |
109 | if (current_clr_polling_and_test()) { | |
110 | dev->last_residency = 0; | |
111 | local_irq_enable(); | |
112 | return -EBUSY; | |
113 | } | |
114 | ||
bcf6ad8a RW |
115 | /* |
116 | * Enter the idle state previously returned by the governor decision. | |
117 | * This function will block until an interrupt occurs and will take | |
118 | * care of re-enabling the local interrupts | |
119 | */ | |
827a5aef | 120 | return cpuidle_enter(drv, dev, next_state); |
bcf6ad8a RW |
121 | } |
122 | ||
30cdd69e DL |
123 | /** |
124 | * cpuidle_idle_call - the main idle function | |
125 | * | |
126 | * NOTE: no locks or semaphores should be used here | |
82c65d60 AL |
127 | * |
128 | * On archs that support TIF_POLLING_NRFLAG, is called with polling | |
129 | * set, and it returns with polling set. If it ever stops polling, it | |
130 | * must clear the polling bit. | |
30cdd69e | 131 | */ |
08c373e5 | 132 | static void cpuidle_idle_call(void) |
30cdd69e | 133 | { |
9bd616e3 | 134 | struct cpuidle_device *dev = cpuidle_get_device(); |
30cdd69e | 135 | struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); |
37352273 | 136 | int next_state, entered_state; |
30cdd69e | 137 | |
a1d028bd DL |
138 | /* |
139 | * Check if the idle task must be rescheduled. If it is the | |
c444117f | 140 | * case, exit the function after re-enabling the local irq. |
a1d028bd | 141 | */ |
c444117f | 142 | if (need_resched()) { |
8ca3c642 | 143 | local_irq_enable(); |
08c373e5 | 144 | return; |
8ca3c642 DL |
145 | } |
146 | ||
a1d028bd DL |
147 | /* |
148 | * Tell the RCU framework we are entering an idle section, | |
149 | * so no more rcu read side critical sections and one more | |
150 | * step to the grace period | |
151 | */ | |
c8cc7d4d DL |
152 | rcu_idle_enter(); |
153 | ||
82f66327 RW |
154 | if (cpuidle_not_available(drv, dev)) { |
155 | default_idle_call(); | |
156 | goto exit_idle; | |
157 | } | |
ef2b22ac | 158 | |
38106313 RW |
159 | /* |
160 | * Suspend-to-idle ("freeze") is a system state in which all user space | |
161 | * has been frozen, all I/O devices have been suspended and the only | |
162 | * activity happens here and in iterrupts (if any). In that case bypass | |
163 | * the cpuidle governor and go stratight for the deepest idle state | |
164 | * available. Possibly also suspend the local tick and the entire | |
165 | * timekeeping to prevent timer interrupts from kicking us out of idle | |
166 | * until a proper wakeup interrupt happens. | |
167 | */ | |
bb8313b6 JP |
168 | |
169 | if (idle_should_freeze() || dev->use_deepest_state) { | |
170 | if (idle_should_freeze()) { | |
171 | entered_state = cpuidle_enter_freeze(drv, dev); | |
172 | if (entered_state > 0) { | |
173 | local_irq_enable(); | |
174 | goto exit_idle; | |
175 | } | |
ef2b22ac RW |
176 | } |
177 | ||
ef2b22ac | 178 | next_state = cpuidle_find_deepest_state(drv, dev); |
bcf6ad8a | 179 | call_cpuidle(drv, dev, next_state); |
ef2b22ac | 180 | } else { |
ef2b22ac RW |
181 | /* |
182 | * Ask the cpuidle framework to choose a convenient idle state. | |
183 | */ | |
184 | next_state = cpuidle_select(drv, dev); | |
bcf6ad8a RW |
185 | entered_state = call_cpuidle(drv, dev, next_state); |
186 | /* | |
187 | * Give the governor an opportunity to reflect on the outcome | |
188 | */ | |
ef2b22ac | 189 | cpuidle_reflect(dev, entered_state); |
bcf6ad8a | 190 | } |
37352273 PZ |
191 | |
192 | exit_idle: | |
8ca3c642 | 193 | __current_set_polling(); |
30cdd69e | 194 | |
a1d028bd | 195 | /* |
37352273 | 196 | * It is up to the idle functions to reenable local interrupts |
a1d028bd | 197 | */ |
c8cc7d4d DL |
198 | if (WARN_ON_ONCE(irqs_disabled())) |
199 | local_irq_enable(); | |
200 | ||
201 | rcu_idle_exit(); | |
30cdd69e | 202 | } |
30cdd69e | 203 | |
cf37b6b4 NP |
204 | /* |
205 | * Generic idle loop implementation | |
82c65d60 AL |
206 | * |
207 | * Called with polling cleared. | |
cf37b6b4 | 208 | */ |
c1de45ca | 209 | static void do_idle(void) |
cf37b6b4 | 210 | { |
c1de45ca PZ |
211 | /* |
212 | * If the arch has a polling bit, we maintain an invariant: | |
213 | * | |
214 | * Our polling bit is clear if we're not scheduled (i.e. if rq->curr != | |
215 | * rq->idle). This means that, if rq->idle has the polling bit set, | |
216 | * then setting need_resched is guaranteed to cause the CPU to | |
217 | * reschedule. | |
218 | */ | |
cf37b6b4 | 219 | |
c1de45ca PZ |
220 | __current_set_polling(); |
221 | tick_nohz_idle_enter(); | |
cf37b6b4 | 222 | |
c1de45ca PZ |
223 | while (!need_resched()) { |
224 | check_pgt_cache(); | |
225 | rmb(); | |
cf37b6b4 | 226 | |
c1de45ca PZ |
227 | if (cpu_is_offline(smp_processor_id())) { |
228 | cpuhp_report_idle_dead(); | |
229 | arch_cpu_idle_dead(); | |
cf37b6b4 | 230 | } |
06d50c65 | 231 | |
c1de45ca PZ |
232 | local_irq_disable(); |
233 | arch_cpu_idle_enter(); | |
82c65d60 AL |
234 | |
235 | /* | |
c1de45ca PZ |
236 | * In poll mode we reenable interrupts and spin. Also if we |
237 | * detected in the wakeup from idle path that the tick | |
238 | * broadcast device expired for us, we don't want to go deep | |
239 | * idle as we know that the IPI is going to arrive right away. | |
82c65d60 | 240 | */ |
c1de45ca PZ |
241 | if (cpu_idle_force_poll || tick_check_broadcast_expired()) |
242 | cpu_idle_poll(); | |
243 | else | |
244 | cpuidle_idle_call(); | |
245 | arch_cpu_idle_exit(); | |
cf37b6b4 | 246 | } |
c1de45ca PZ |
247 | |
248 | /* | |
249 | * Since we fell out of the loop above, we know TIF_NEED_RESCHED must | |
250 | * be set, propagate it into PREEMPT_NEED_RESCHED. | |
251 | * | |
252 | * This is required because for polling idle loops we will not have had | |
253 | * an IPI to fold the state for us. | |
254 | */ | |
255 | preempt_set_need_resched(); | |
256 | tick_nohz_idle_exit(); | |
257 | __current_clr_polling(); | |
258 | ||
259 | /* | |
260 | * We promise to call sched_ttwu_pending() and reschedule if | |
261 | * need_resched() is set while polling is set. That means that clearing | |
262 | * polling needs to be visible before doing these things. | |
263 | */ | |
264 | smp_mb__after_atomic(); | |
265 | ||
266 | sched_ttwu_pending(); | |
267 | schedule_preempt_disabled(); | |
cf37b6b4 NP |
268 | } |
269 | ||
6727ad9e CM |
270 | bool cpu_in_idle(unsigned long pc) |
271 | { | |
272 | return pc >= (unsigned long)__cpuidle_text_start && | |
273 | pc < (unsigned long)__cpuidle_text_end; | |
274 | } | |
275 | ||
c1de45ca PZ |
276 | struct idle_timer { |
277 | struct hrtimer timer; | |
278 | int done; | |
279 | }; | |
280 | ||
281 | static enum hrtimer_restart idle_inject_timer_fn(struct hrtimer *timer) | |
282 | { | |
283 | struct idle_timer *it = container_of(timer, struct idle_timer, timer); | |
284 | ||
285 | WRITE_ONCE(it->done, 1); | |
286 | set_tsk_need_resched(current); | |
287 | ||
288 | return HRTIMER_NORESTART; | |
289 | } | |
290 | ||
291 | void play_idle(unsigned long duration_ms) | |
292 | { | |
293 | struct idle_timer it; | |
294 | ||
295 | /* | |
296 | * Only FIFO tasks can disable the tick since they don't need the forced | |
297 | * preemption. | |
298 | */ | |
299 | WARN_ON_ONCE(current->policy != SCHED_FIFO); | |
300 | WARN_ON_ONCE(current->nr_cpus_allowed != 1); | |
301 | WARN_ON_ONCE(!(current->flags & PF_KTHREAD)); | |
302 | WARN_ON_ONCE(!(current->flags & PF_NO_SETAFFINITY)); | |
303 | WARN_ON_ONCE(!duration_ms); | |
304 | ||
305 | rcu_sleep_check(); | |
306 | preempt_disable(); | |
307 | current->flags |= PF_IDLE; | |
308 | cpuidle_use_deepest_state(true); | |
309 | ||
310 | it.done = 0; | |
311 | hrtimer_init_on_stack(&it.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); | |
312 | it.timer.function = idle_inject_timer_fn; | |
313 | hrtimer_start(&it.timer, ms_to_ktime(duration_ms), HRTIMER_MODE_REL_PINNED); | |
314 | ||
315 | while (!READ_ONCE(it.done)) | |
316 | do_idle(); | |
317 | ||
318 | cpuidle_use_deepest_state(false); | |
319 | current->flags &= ~PF_IDLE; | |
320 | ||
321 | preempt_fold_need_resched(); | |
322 | preempt_enable(); | |
323 | } | |
324 | EXPORT_SYMBOL_GPL(play_idle); | |
325 | ||
cf37b6b4 NP |
326 | void cpu_startup_entry(enum cpuhp_state state) |
327 | { | |
328 | /* | |
329 | * This #ifdef needs to die, but it's too late in the cycle to | |
330 | * make this generic (arm and sh have never invoked the canary | |
331 | * init for the non boot cpus!). Will be fixed in 3.11 | |
332 | */ | |
333 | #ifdef CONFIG_X86 | |
334 | /* | |
335 | * If we're the non-boot CPU, nothing set the stack canary up | |
336 | * for us. The boot CPU already has it initialized but no harm | |
337 | * in doing it again. This is a good place for updating it, as | |
338 | * we wont ever return from this function (so the invalid | |
339 | * canaries already on the stack wont ever trigger). | |
340 | */ | |
341 | boot_init_stack_canary(); | |
342 | #endif | |
cf37b6b4 | 343 | arch_cpu_idle_prepare(); |
8df3e07e | 344 | cpuhp_online_idle(state); |
c1de45ca PZ |
345 | while (1) |
346 | do_idle(); | |
cf37b6b4 | 347 | } |