Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0
2 : /*
3 : * This file contains functions which emulate a local clock-event
4 : * device via a broadcast event source.
5 : *
6 : * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
7 : * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
8 : * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
9 : */
10 : #include <linux/cpu.h>
11 : #include <linux/err.h>
12 : #include <linux/hrtimer.h>
13 : #include <linux/interrupt.h>
14 : #include <linux/percpu.h>
15 : #include <linux/profile.h>
16 : #include <linux/sched.h>
17 : #include <linux/smp.h>
18 : #include <linux/module.h>
19 :
20 : #include "tick-internal.h"
21 :
22 : /*
23 : * Broadcast support for broken x86 hardware, where the local apic
24 : * timer stops in C3 state.
25 : */
26 :
27 : static struct tick_device tick_broadcast_device;
28 : static cpumask_var_t tick_broadcast_mask __cpumask_var_read_mostly;
29 : static cpumask_var_t tick_broadcast_on __cpumask_var_read_mostly;
30 : static cpumask_var_t tmpmask __cpumask_var_read_mostly;
31 : static int tick_broadcast_forced;
32 :
33 : static __cacheline_aligned_in_smp DEFINE_RAW_SPINLOCK(tick_broadcast_lock);
34 :
35 : #ifdef CONFIG_TICK_ONESHOT
36 : static void tick_broadcast_setup_oneshot(struct clock_event_device *bc);
37 : static void tick_broadcast_clear_oneshot(int cpu);
38 : static void tick_resume_broadcast_oneshot(struct clock_event_device *bc);
39 : # ifdef CONFIG_HOTPLUG_CPU
40 : static void tick_broadcast_oneshot_offline(unsigned int cpu);
41 : # endif
42 : #else
43 : static inline void tick_broadcast_setup_oneshot(struct clock_event_device *bc) { BUG(); }
44 : static inline void tick_broadcast_clear_oneshot(int cpu) { }
45 : static inline void tick_resume_broadcast_oneshot(struct clock_event_device *bc) { }
46 : # ifdef CONFIG_HOTPLUG_CPU
47 : static inline void tick_broadcast_oneshot_offline(unsigned int cpu) { }
48 : # endif
49 : #endif
50 :
51 : /*
52 : * Debugging: see timer_list.c
53 : */
54 0 : struct tick_device *tick_get_broadcast_device(void)
55 : {
56 0 : return &tick_broadcast_device;
57 : }
58 :
59 0 : struct cpumask *tick_get_broadcast_mask(void)
60 : {
61 0 : return tick_broadcast_mask;
62 : }
63 :
64 : /*
65 : * Start the device in periodic mode
66 : */
67 0 : static void tick_broadcast_start_periodic(struct clock_event_device *bc)
68 : {
69 0 : if (bc)
70 0 : tick_setup_periodic(bc, 1);
71 0 : }
72 :
73 : /*
74 : * Check, if the device can be utilized as broadcast device:
75 : */
76 0 : static bool tick_check_broadcast_device(struct clock_event_device *curdev,
77 : struct clock_event_device *newdev)
78 : {
79 0 : if ((newdev->features & CLOCK_EVT_FEAT_DUMMY) ||
80 0 : (newdev->features & CLOCK_EVT_FEAT_PERCPU) ||
81 : (newdev->features & CLOCK_EVT_FEAT_C3STOP))
82 : return false;
83 :
84 0 : if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT &&
85 0 : !(newdev->features & CLOCK_EVT_FEAT_ONESHOT))
86 : return false;
87 :
88 0 : return !curdev || newdev->rating > curdev->rating;
89 : }
90 :
91 : /*
92 : * Conditionally install/replace broadcast device
93 : */
94 0 : void tick_install_broadcast_device(struct clock_event_device *dev)
95 : {
96 0 : struct clock_event_device *cur = tick_broadcast_device.evtdev;
97 :
98 0 : if (!tick_check_broadcast_device(cur, dev))
99 : return;
100 :
101 0 : if (!try_module_get(dev->owner))
102 : return;
103 :
104 0 : clockevents_exchange_device(cur, dev);
105 0 : if (cur)
106 0 : cur->event_handler = clockevents_handle_noop;
107 0 : tick_broadcast_device.evtdev = dev;
108 0 : if (!cpumask_empty(tick_broadcast_mask))
109 0 : tick_broadcast_start_periodic(dev);
110 : /*
111 : * Inform all cpus about this. We might be in a situation
112 : * where we did not switch to oneshot mode because the per cpu
113 : * devices are affected by CLOCK_EVT_FEAT_C3STOP and the lack
114 : * of a oneshot capable broadcast device. Without that
115 : * notification the systems stays stuck in periodic mode
116 : * forever.
117 : */
118 0 : if (dev->features & CLOCK_EVT_FEAT_ONESHOT)
119 0 : tick_clock_notify();
120 : }
121 :
122 : /*
123 : * Check, if the device is the broadcast device
124 : */
125 4 : int tick_is_broadcast_device(struct clock_event_device *dev)
126 : {
127 4 : return (dev && tick_broadcast_device.evtdev == dev);
128 : }
129 :
130 0 : int tick_broadcast_update_freq(struct clock_event_device *dev, u32 freq)
131 : {
132 0 : int ret = -ENODEV;
133 :
134 0 : if (tick_is_broadcast_device(dev)) {
135 0 : raw_spin_lock(&tick_broadcast_lock);
136 0 : ret = __clockevents_update_freq(dev, freq);
137 0 : raw_spin_unlock(&tick_broadcast_lock);
138 : }
139 0 : return ret;
140 : }
141 :
142 :
143 0 : static void err_broadcast(const struct cpumask *mask)
144 : {
145 0 : pr_crit_once("Failed to broadcast timer tick. Some CPUs may be unresponsive.\n");
146 0 : }
147 :
148 0 : static void tick_device_setup_broadcast_func(struct clock_event_device *dev)
149 : {
150 0 : if (!dev->broadcast)
151 0 : dev->broadcast = tick_broadcast;
152 0 : if (!dev->broadcast) {
153 0 : pr_warn_once("%s depends on broadcast, but no broadcast function available\n",
154 : dev->name);
155 0 : dev->broadcast = err_broadcast;
156 : }
157 0 : }
158 :
159 : /*
160 : * Check, if the device is disfunctional and a place holder, which
161 : * needs to be handled by the broadcast device.
162 : */
163 4 : int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
164 : {
165 4 : struct clock_event_device *bc = tick_broadcast_device.evtdev;
166 4 : unsigned long flags;
167 4 : int ret = 0;
168 :
169 4 : raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
170 :
171 : /*
172 : * Devices might be registered with both periodic and oneshot
173 : * mode disabled. This signals, that the device needs to be
174 : * operated from the broadcast device and is a placeholder for
175 : * the cpu local device.
176 : */
177 4 : if (!tick_device_is_functional(dev)) {
178 0 : dev->event_handler = tick_handle_periodic;
179 0 : tick_device_setup_broadcast_func(dev);
180 0 : cpumask_set_cpu(cpu, tick_broadcast_mask);
181 0 : if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
182 0 : tick_broadcast_start_periodic(bc);
183 : else
184 0 : tick_broadcast_setup_oneshot(bc);
185 : ret = 1;
186 : } else {
187 : /*
188 : * Clear the broadcast bit for this cpu if the
189 : * device is not power state affected.
190 : */
191 4 : if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
192 4 : cpumask_clear_cpu(cpu, tick_broadcast_mask);
193 : else
194 0 : tick_device_setup_broadcast_func(dev);
195 :
196 : /*
197 : * Clear the broadcast bit if the CPU is not in
198 : * periodic broadcast on state.
199 : */
200 4 : if (!cpumask_test_cpu(cpu, tick_broadcast_on))
201 4 : cpumask_clear_cpu(cpu, tick_broadcast_mask);
202 :
203 4 : switch (tick_broadcast_device.mode) {
204 0 : case TICKDEV_MODE_ONESHOT:
205 : /*
206 : * If the system is in oneshot mode we can
207 : * unconditionally clear the oneshot mask bit,
208 : * because the CPU is running and therefore
209 : * not in an idle state which causes the power
210 : * state affected device to stop. Let the
211 : * caller initialize the device.
212 : */
213 0 : tick_broadcast_clear_oneshot(cpu);
214 0 : ret = 0;
215 0 : break;
216 :
217 : case TICKDEV_MODE_PERIODIC:
218 : /*
219 : * If the system is in periodic mode, check
220 : * whether the broadcast device can be
221 : * switched off now.
222 : */
223 4 : if (cpumask_empty(tick_broadcast_mask) && bc)
224 0 : clockevents_shutdown(bc);
225 : /*
226 : * If we kept the cpu in the broadcast mask,
227 : * tell the caller to leave the per cpu device
228 : * in shutdown state. The periodic interrupt
229 : * is delivered by the broadcast device, if
230 : * the broadcast device exists and is not
231 : * hrtimer based.
232 : */
233 4 : if (bc && !(bc->features & CLOCK_EVT_FEAT_HRTIMER))
234 0 : ret = cpumask_test_cpu(cpu, tick_broadcast_mask);
235 : break;
236 : default:
237 : break;
238 : }
239 : }
240 4 : raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
241 4 : return ret;
242 : }
243 :
244 : #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
245 0 : int tick_receive_broadcast(void)
246 : {
247 0 : struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
248 0 : struct clock_event_device *evt = td->evtdev;
249 :
250 0 : if (!evt)
251 : return -ENODEV;
252 :
253 0 : if (!evt->event_handler)
254 : return -EINVAL;
255 :
256 0 : evt->event_handler(evt);
257 0 : return 0;
258 : }
259 : #endif
260 :
261 : /*
262 : * Broadcast the event to the cpus, which are set in the mask (mangled).
263 : */
264 0 : static bool tick_do_broadcast(struct cpumask *mask)
265 : {
266 0 : int cpu = smp_processor_id();
267 0 : struct tick_device *td;
268 0 : bool local = false;
269 :
270 : /*
271 : * Check, if the current cpu is in the mask
272 : */
273 0 : if (cpumask_test_cpu(cpu, mask)) {
274 0 : struct clock_event_device *bc = tick_broadcast_device.evtdev;
275 :
276 0 : cpumask_clear_cpu(cpu, mask);
277 : /*
278 : * We only run the local handler, if the broadcast
279 : * device is not hrtimer based. Otherwise we run into
280 : * a hrtimer recursion.
281 : *
282 : * local timer_interrupt()
283 : * local_handler()
284 : * expire_hrtimers()
285 : * bc_handler()
286 : * local_handler()
287 : * expire_hrtimers()
288 : */
289 0 : local = !(bc->features & CLOCK_EVT_FEAT_HRTIMER);
290 : }
291 :
292 0 : if (!cpumask_empty(mask)) {
293 : /*
294 : * It might be necessary to actually check whether the devices
295 : * have different broadcast functions. For now, just use the
296 : * one of the first device. This works as long as we have this
297 : * misfeature only on x86 (lapic)
298 : */
299 0 : td = &per_cpu(tick_cpu_device, cpumask_first(mask));
300 0 : td->evtdev->broadcast(mask);
301 : }
302 0 : return local;
303 : }
304 :
305 : /*
306 : * Periodic broadcast:
307 : * - invoke the broadcast handlers
308 : */
309 0 : static bool tick_do_periodic_broadcast(void)
310 : {
311 0 : cpumask_and(tmpmask, cpu_online_mask, tick_broadcast_mask);
312 0 : return tick_do_broadcast(tmpmask);
313 : }
314 :
315 : /*
316 : * Event handler for periodic broadcast ticks
317 : */
318 0 : static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
319 : {
320 0 : struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
321 0 : bool bc_local;
322 :
323 0 : raw_spin_lock(&tick_broadcast_lock);
324 :
325 : /* Handle spurious interrupts gracefully */
326 0 : if (clockevent_state_shutdown(tick_broadcast_device.evtdev)) {
327 0 : raw_spin_unlock(&tick_broadcast_lock);
328 0 : return;
329 : }
330 :
331 0 : bc_local = tick_do_periodic_broadcast();
332 :
333 0 : if (clockevent_state_oneshot(dev)) {
334 0 : ktime_t next = ktime_add_ns(dev->next_event, TICK_NSEC);
335 :
336 0 : clockevents_program_event(dev, next, true);
337 : }
338 0 : raw_spin_unlock(&tick_broadcast_lock);
339 :
340 : /*
341 : * We run the handler of the local cpu after dropping
342 : * tick_broadcast_lock because the handler might deadlock when
343 : * trying to switch to oneshot mode.
344 : */
345 0 : if (bc_local)
346 0 : td->evtdev->event_handler(td->evtdev);
347 : }
348 :
349 : /**
350 : * tick_broadcast_control - Enable/disable or force broadcast mode
351 : * @mode: The selected broadcast mode
352 : *
353 : * Called when the system enters a state where affected tick devices
354 : * might stop. Note: TICK_BROADCAST_FORCE cannot be undone.
355 : */
356 0 : void tick_broadcast_control(enum tick_broadcast_mode mode)
357 : {
358 0 : struct clock_event_device *bc, *dev;
359 0 : struct tick_device *td;
360 0 : int cpu, bc_stopped;
361 0 : unsigned long flags;
362 :
363 : /* Protects also the local clockevent device. */
364 0 : raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
365 0 : td = this_cpu_ptr(&tick_cpu_device);
366 0 : dev = td->evtdev;
367 :
368 : /*
369 : * Is the device not affected by the powerstate ?
370 : */
371 0 : if (!dev || !(dev->features & CLOCK_EVT_FEAT_C3STOP))
372 0 : goto out;
373 :
374 0 : if (!tick_device_is_functional(dev))
375 0 : goto out;
376 :
377 0 : cpu = smp_processor_id();
378 0 : bc = tick_broadcast_device.evtdev;
379 0 : bc_stopped = cpumask_empty(tick_broadcast_mask);
380 :
381 0 : switch (mode) {
382 0 : case TICK_BROADCAST_FORCE:
383 0 : tick_broadcast_forced = 1;
384 0 : fallthrough;
385 0 : case TICK_BROADCAST_ON:
386 0 : cpumask_set_cpu(cpu, tick_broadcast_on);
387 0 : if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_mask)) {
388 : /*
389 : * Only shutdown the cpu local device, if:
390 : *
391 : * - the broadcast device exists
392 : * - the broadcast device is not a hrtimer based one
393 : * - the broadcast device is in periodic mode to
394 : * avoid a hickup during switch to oneshot mode
395 : */
396 0 : if (bc && !(bc->features & CLOCK_EVT_FEAT_HRTIMER) &&
397 0 : tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
398 0 : clockevents_shutdown(dev);
399 : }
400 : break;
401 :
402 0 : case TICK_BROADCAST_OFF:
403 0 : if (tick_broadcast_forced)
404 : break;
405 0 : cpumask_clear_cpu(cpu, tick_broadcast_on);
406 0 : if (cpumask_test_and_clear_cpu(cpu, tick_broadcast_mask)) {
407 0 : if (tick_broadcast_device.mode ==
408 : TICKDEV_MODE_PERIODIC)
409 0 : tick_setup_periodic(dev, 0);
410 : }
411 : break;
412 : }
413 :
414 0 : if (bc) {
415 0 : if (cpumask_empty(tick_broadcast_mask)) {
416 0 : if (!bc_stopped)
417 0 : clockevents_shutdown(bc);
418 0 : } else if (bc_stopped) {
419 0 : if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
420 0 : tick_broadcast_start_periodic(bc);
421 : else
422 0 : tick_broadcast_setup_oneshot(bc);
423 : }
424 : }
425 0 : out:
426 0 : raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
427 0 : }
428 : EXPORT_SYMBOL_GPL(tick_broadcast_control);
429 :
430 : /*
431 : * Set the periodic handler depending on broadcast on/off
432 : */
433 4 : void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
434 : {
435 4 : if (!broadcast)
436 4 : dev->event_handler = tick_handle_periodic;
437 : else
438 0 : dev->event_handler = tick_handle_periodic_broadcast;
439 4 : }
440 :
441 : #ifdef CONFIG_HOTPLUG_CPU
442 0 : static void tick_shutdown_broadcast(void)
443 : {
444 0 : struct clock_event_device *bc = tick_broadcast_device.evtdev;
445 :
446 0 : if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
447 0 : if (bc && cpumask_empty(tick_broadcast_mask))
448 0 : clockevents_shutdown(bc);
449 : }
450 0 : }
451 :
452 : /*
453 : * Remove a CPU from broadcasting
454 : */
455 0 : void tick_broadcast_offline(unsigned int cpu)
456 : {
457 0 : raw_spin_lock(&tick_broadcast_lock);
458 0 : cpumask_clear_cpu(cpu, tick_broadcast_mask);
459 0 : cpumask_clear_cpu(cpu, tick_broadcast_on);
460 0 : tick_broadcast_oneshot_offline(cpu);
461 0 : tick_shutdown_broadcast();
462 0 : raw_spin_unlock(&tick_broadcast_lock);
463 0 : }
464 :
465 : #endif
466 :
467 0 : void tick_suspend_broadcast(void)
468 : {
469 0 : struct clock_event_device *bc;
470 0 : unsigned long flags;
471 :
472 0 : raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
473 :
474 0 : bc = tick_broadcast_device.evtdev;
475 0 : if (bc)
476 0 : clockevents_shutdown(bc);
477 :
478 0 : raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
479 0 : }
480 :
481 : /*
482 : * This is called from tick_resume_local() on a resuming CPU. That's
483 : * called from the core resume function, tick_unfreeze() and the magic XEN
484 : * resume hackery.
485 : *
486 : * In none of these cases the broadcast device mode can change and the
487 : * bit of the resuming CPU in the broadcast mask is safe as well.
488 : */
489 0 : bool tick_resume_check_broadcast(void)
490 : {
491 0 : if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT)
492 : return false;
493 : else
494 0 : return cpumask_test_cpu(smp_processor_id(), tick_broadcast_mask);
495 : }
496 :
497 0 : void tick_resume_broadcast(void)
498 : {
499 0 : struct clock_event_device *bc;
500 0 : unsigned long flags;
501 :
502 0 : raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
503 :
504 0 : bc = tick_broadcast_device.evtdev;
505 :
506 0 : if (bc) {
507 0 : clockevents_tick_resume(bc);
508 :
509 0 : switch (tick_broadcast_device.mode) {
510 : case TICKDEV_MODE_PERIODIC:
511 0 : if (!cpumask_empty(tick_broadcast_mask))
512 0 : tick_broadcast_start_periodic(bc);
513 : break;
514 : case TICKDEV_MODE_ONESHOT:
515 0 : if (!cpumask_empty(tick_broadcast_mask))
516 0 : tick_resume_broadcast_oneshot(bc);
517 : break;
518 : }
519 0 : }
520 0 : raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
521 0 : }
522 :
523 : #ifdef CONFIG_TICK_ONESHOT
524 :
525 : static cpumask_var_t tick_broadcast_oneshot_mask __cpumask_var_read_mostly;
526 : static cpumask_var_t tick_broadcast_pending_mask __cpumask_var_read_mostly;
527 : static cpumask_var_t tick_broadcast_force_mask __cpumask_var_read_mostly;
528 :
529 : /*
530 : * Exposed for debugging: see timer_list.c
531 : */
532 0 : struct cpumask *tick_get_broadcast_oneshot_mask(void)
533 : {
534 0 : return tick_broadcast_oneshot_mask;
535 : }
536 :
537 : /*
538 : * Called before going idle with interrupts disabled. Checks whether a
539 : * broadcast event from the other core is about to happen. We detected
540 : * that in tick_broadcast_oneshot_control(). The callsite can use this
541 : * to avoid a deep idle transition as we are about to get the
542 : * broadcast IPI right away.
543 : */
544 18528 : int tick_check_broadcast_expired(void)
545 : {
546 18528 : return cpumask_test_cpu(smp_processor_id(), tick_broadcast_force_mask);
547 : }
548 :
549 : /*
550 : * Set broadcast interrupt affinity
551 : */
552 0 : static void tick_broadcast_set_affinity(struct clock_event_device *bc,
553 : const struct cpumask *cpumask)
554 : {
555 0 : if (!(bc->features & CLOCK_EVT_FEAT_DYNIRQ))
556 : return;
557 :
558 0 : if (cpumask_equal(bc->cpumask, cpumask))
559 : return;
560 :
561 0 : bc->cpumask = cpumask;
562 0 : irq_set_affinity(bc->irq, bc->cpumask);
563 : }
564 :
565 0 : static void tick_broadcast_set_event(struct clock_event_device *bc, int cpu,
566 : ktime_t expires)
567 : {
568 0 : if (!clockevent_state_oneshot(bc))
569 0 : clockevents_switch_state(bc, CLOCK_EVT_STATE_ONESHOT);
570 :
571 0 : clockevents_program_event(bc, expires, 1);
572 0 : tick_broadcast_set_affinity(bc, cpumask_of(cpu));
573 0 : }
574 :
575 0 : static void tick_resume_broadcast_oneshot(struct clock_event_device *bc)
576 : {
577 0 : clockevents_switch_state(bc, CLOCK_EVT_STATE_ONESHOT);
578 0 : }
579 :
580 : /*
581 : * Called from irq_enter() when idle was interrupted to reenable the
582 : * per cpu device.
583 : */
584 16994 : void tick_check_oneshot_broadcast_this_cpu(void)
585 : {
586 16994 : if (cpumask_test_cpu(smp_processor_id(), tick_broadcast_oneshot_mask)) {
587 0 : struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
588 :
589 : /*
590 : * We might be in the middle of switching over from
591 : * periodic to oneshot. If the CPU has not yet
592 : * switched over, leave the device alone.
593 : */
594 0 : if (td->mode == TICKDEV_MODE_ONESHOT) {
595 0 : clockevents_switch_state(td->evtdev,
596 : CLOCK_EVT_STATE_ONESHOT);
597 : }
598 : }
599 17099 : }
600 :
601 : /*
602 : * Handle oneshot mode broadcasting
603 : */
604 0 : static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
605 : {
606 0 : struct tick_device *td;
607 0 : ktime_t now, next_event;
608 0 : int cpu, next_cpu = 0;
609 0 : bool bc_local;
610 :
611 0 : raw_spin_lock(&tick_broadcast_lock);
612 0 : dev->next_event = KTIME_MAX;
613 0 : next_event = KTIME_MAX;
614 0 : cpumask_clear(tmpmask);
615 0 : now = ktime_get();
616 : /* Find all expired events */
617 0 : for_each_cpu(cpu, tick_broadcast_oneshot_mask) {
618 : /*
619 : * Required for !SMP because for_each_cpu() reports
620 : * unconditionally CPU0 as set on UP kernels.
621 : */
622 0 : if (!IS_ENABLED(CONFIG_SMP) &&
623 : cpumask_empty(tick_broadcast_oneshot_mask))
624 : break;
625 :
626 0 : td = &per_cpu(tick_cpu_device, cpu);
627 0 : if (td->evtdev->next_event <= now) {
628 0 : cpumask_set_cpu(cpu, tmpmask);
629 : /*
630 : * Mark the remote cpu in the pending mask, so
631 : * it can avoid reprogramming the cpu local
632 : * timer in tick_broadcast_oneshot_control().
633 : */
634 0 : cpumask_set_cpu(cpu, tick_broadcast_pending_mask);
635 0 : } else if (td->evtdev->next_event < next_event) {
636 0 : next_event = td->evtdev->next_event;
637 0 : next_cpu = cpu;
638 : }
639 : }
640 :
641 : /*
642 : * Remove the current cpu from the pending mask. The event is
643 : * delivered immediately in tick_do_broadcast() !
644 : */
645 0 : cpumask_clear_cpu(smp_processor_id(), tick_broadcast_pending_mask);
646 :
647 : /* Take care of enforced broadcast requests */
648 0 : cpumask_or(tmpmask, tmpmask, tick_broadcast_force_mask);
649 0 : cpumask_clear(tick_broadcast_force_mask);
650 :
651 : /*
652 : * Sanity check. Catch the case where we try to broadcast to
653 : * offline cpus.
654 : */
655 0 : if (WARN_ON_ONCE(!cpumask_subset(tmpmask, cpu_online_mask)))
656 0 : cpumask_and(tmpmask, tmpmask, cpu_online_mask);
657 :
658 : /*
659 : * Wakeup the cpus which have an expired event.
660 : */
661 0 : bc_local = tick_do_broadcast(tmpmask);
662 :
663 : /*
664 : * Two reasons for reprogram:
665 : *
666 : * - The global event did not expire any CPU local
667 : * events. This happens in dyntick mode, as the maximum PIT
668 : * delta is quite small.
669 : *
670 : * - There are pending events on sleeping CPUs which were not
671 : * in the event mask
672 : */
673 0 : if (next_event != KTIME_MAX)
674 0 : tick_broadcast_set_event(dev, next_cpu, next_event);
675 :
676 0 : raw_spin_unlock(&tick_broadcast_lock);
677 :
678 0 : if (bc_local) {
679 0 : td = this_cpu_ptr(&tick_cpu_device);
680 0 : td->evtdev->event_handler(td->evtdev);
681 : }
682 0 : }
683 :
684 0 : static int broadcast_needs_cpu(struct clock_event_device *bc, int cpu)
685 : {
686 0 : if (!(bc->features & CLOCK_EVT_FEAT_HRTIMER))
687 : return 0;
688 0 : if (bc->next_event == KTIME_MAX)
689 : return 0;
690 0 : return bc->bound_on == cpu ? -EBUSY : 0;
691 : }
692 :
693 0 : static void broadcast_shutdown_local(struct clock_event_device *bc,
694 : struct clock_event_device *dev)
695 : {
696 : /*
697 : * For hrtimer based broadcasting we cannot shutdown the cpu
698 : * local device if our own event is the first one to expire or
699 : * if we own the broadcast timer.
700 : */
701 0 : if (bc->features & CLOCK_EVT_FEAT_HRTIMER) {
702 0 : if (broadcast_needs_cpu(bc, smp_processor_id()))
703 : return;
704 0 : if (dev->next_event < bc->next_event)
705 : return;
706 : }
707 0 : clockevents_switch_state(dev, CLOCK_EVT_STATE_SHUTDOWN);
708 : }
709 :
710 0 : int __tick_broadcast_oneshot_control(enum tick_broadcast_state state)
711 : {
712 0 : struct clock_event_device *bc, *dev;
713 0 : int cpu, ret = 0;
714 0 : ktime_t now;
715 :
716 : /*
717 : * If there is no broadcast device, tell the caller not to go
718 : * into deep idle.
719 : */
720 0 : if (!tick_broadcast_device.evtdev)
721 : return -EBUSY;
722 :
723 0 : dev = this_cpu_ptr(&tick_cpu_device)->evtdev;
724 :
725 0 : raw_spin_lock(&tick_broadcast_lock);
726 0 : bc = tick_broadcast_device.evtdev;
727 0 : cpu = smp_processor_id();
728 :
729 0 : if (state == TICK_BROADCAST_ENTER) {
730 : /*
731 : * If the current CPU owns the hrtimer broadcast
732 : * mechanism, it cannot go deep idle and we do not add
733 : * the CPU to the broadcast mask. We don't have to go
734 : * through the EXIT path as the local timer is not
735 : * shutdown.
736 : */
737 0 : ret = broadcast_needs_cpu(bc, cpu);
738 0 : if (ret)
739 0 : goto out;
740 :
741 : /*
742 : * If the broadcast device is in periodic mode, we
743 : * return.
744 : */
745 0 : if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
746 : /* If it is a hrtimer based broadcast, return busy */
747 0 : if (bc->features & CLOCK_EVT_FEAT_HRTIMER)
748 0 : ret = -EBUSY;
749 0 : goto out;
750 : }
751 :
752 0 : if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_oneshot_mask)) {
753 0 : WARN_ON_ONCE(cpumask_test_cpu(cpu, tick_broadcast_pending_mask));
754 :
755 : /* Conditionally shut down the local timer. */
756 0 : broadcast_shutdown_local(bc, dev);
757 :
758 : /*
759 : * We only reprogram the broadcast timer if we
760 : * did not mark ourself in the force mask and
761 : * if the cpu local event is earlier than the
762 : * broadcast event. If the current CPU is in
763 : * the force mask, then we are going to be
764 : * woken by the IPI right away; we return
765 : * busy, so the CPU does not try to go deep
766 : * idle.
767 : */
768 0 : if (cpumask_test_cpu(cpu, tick_broadcast_force_mask)) {
769 : ret = -EBUSY;
770 0 : } else if (dev->next_event < bc->next_event) {
771 0 : tick_broadcast_set_event(bc, cpu, dev->next_event);
772 : /*
773 : * In case of hrtimer broadcasts the
774 : * programming might have moved the
775 : * timer to this cpu. If yes, remove
776 : * us from the broadcast mask and
777 : * return busy.
778 : */
779 0 : ret = broadcast_needs_cpu(bc, cpu);
780 0 : if (ret) {
781 0 : cpumask_clear_cpu(cpu,
782 : tick_broadcast_oneshot_mask);
783 : }
784 : }
785 : }
786 : } else {
787 0 : if (cpumask_test_and_clear_cpu(cpu, tick_broadcast_oneshot_mask)) {
788 0 : clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT);
789 : /*
790 : * The cpu which was handling the broadcast
791 : * timer marked this cpu in the broadcast
792 : * pending mask and fired the broadcast
793 : * IPI. So we are going to handle the expired
794 : * event anyway via the broadcast IPI
795 : * handler. No need to reprogram the timer
796 : * with an already expired event.
797 : */
798 0 : if (cpumask_test_and_clear_cpu(cpu,
799 : tick_broadcast_pending_mask))
800 0 : goto out;
801 :
802 : /*
803 : * Bail out if there is no next event.
804 : */
805 0 : if (dev->next_event == KTIME_MAX)
806 0 : goto out;
807 : /*
808 : * If the pending bit is not set, then we are
809 : * either the CPU handling the broadcast
810 : * interrupt or we got woken by something else.
811 : *
812 : * We are no longer in the broadcast mask, so
813 : * if the cpu local expiry time is already
814 : * reached, we would reprogram the cpu local
815 : * timer with an already expired event.
816 : *
817 : * This can lead to a ping-pong when we return
818 : * to idle and therefore rearm the broadcast
819 : * timer before the cpu local timer was able
820 : * to fire. This happens because the forced
821 : * reprogramming makes sure that the event
822 : * will happen in the future and depending on
823 : * the min_delta setting this might be far
824 : * enough out that the ping-pong starts.
825 : *
826 : * If the cpu local next_event has expired
827 : * then we know that the broadcast timer
828 : * next_event has expired as well and
829 : * broadcast is about to be handled. So we
830 : * avoid reprogramming and enforce that the
831 : * broadcast handler, which did not run yet,
832 : * will invoke the cpu local handler.
833 : *
834 : * We cannot call the handler directly from
835 : * here, because we might be in a NOHZ phase
836 : * and we did not go through the irq_enter()
837 : * nohz fixups.
838 : */
839 0 : now = ktime_get();
840 0 : if (dev->next_event <= now) {
841 0 : cpumask_set_cpu(cpu, tick_broadcast_force_mask);
842 0 : goto out;
843 : }
844 : /*
845 : * We got woken by something else. Reprogram
846 : * the cpu local timer device.
847 : */
848 0 : tick_program_event(dev->next_event, 1);
849 : }
850 : }
851 0 : out:
852 0 : raw_spin_unlock(&tick_broadcast_lock);
853 0 : return ret;
854 : }
855 :
856 : /*
857 : * Reset the one shot broadcast for a cpu
858 : *
859 : * Called with tick_broadcast_lock held
860 : */
861 0 : static void tick_broadcast_clear_oneshot(int cpu)
862 : {
863 0 : cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask);
864 0 : cpumask_clear_cpu(cpu, tick_broadcast_pending_mask);
865 0 : }
866 :
867 0 : static void tick_broadcast_init_next_event(struct cpumask *mask,
868 : ktime_t expires)
869 : {
870 0 : struct tick_device *td;
871 0 : int cpu;
872 :
873 0 : for_each_cpu(cpu, mask) {
874 0 : td = &per_cpu(tick_cpu_device, cpu);
875 0 : if (td->evtdev)
876 0 : td->evtdev->next_event = expires;
877 : }
878 0 : }
879 :
880 0 : static inline ktime_t tick_get_next_period(void)
881 : {
882 0 : ktime_t next;
883 :
884 : /*
885 : * Protect against concurrent updates (store /load tearing on
886 : * 32bit). It does not matter if the time is already in the
887 : * past. The broadcast device which is about to be programmed will
888 : * fire in any case.
889 : */
890 0 : raw_spin_lock(&jiffies_lock);
891 0 : next = tick_next_period;
892 0 : raw_spin_unlock(&jiffies_lock);
893 0 : return next;
894 : }
895 :
896 : /**
897 : * tick_broadcast_setup_oneshot - setup the broadcast device
898 : */
899 0 : static void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
900 : {
901 0 : int cpu = smp_processor_id();
902 :
903 0 : if (!bc)
904 : return;
905 :
906 : /* Set it up only once ! */
907 0 : if (bc->event_handler != tick_handle_oneshot_broadcast) {
908 0 : int was_periodic = clockevent_state_periodic(bc);
909 :
910 0 : bc->event_handler = tick_handle_oneshot_broadcast;
911 :
912 : /*
913 : * We must be careful here. There might be other CPUs
914 : * waiting for periodic broadcast. We need to set the
915 : * oneshot_mask bits for those and program the
916 : * broadcast device to fire.
917 : */
918 0 : cpumask_copy(tmpmask, tick_broadcast_mask);
919 0 : cpumask_clear_cpu(cpu, tmpmask);
920 0 : cpumask_or(tick_broadcast_oneshot_mask,
921 : tick_broadcast_oneshot_mask, tmpmask);
922 :
923 0 : if (was_periodic && !cpumask_empty(tmpmask)) {
924 0 : ktime_t nextevt = tick_get_next_period();
925 :
926 0 : clockevents_switch_state(bc, CLOCK_EVT_STATE_ONESHOT);
927 0 : tick_broadcast_init_next_event(tmpmask, nextevt);
928 0 : tick_broadcast_set_event(bc, cpu, nextevt);
929 : } else
930 0 : bc->next_event = KTIME_MAX;
931 : } else {
932 : /*
933 : * The first cpu which switches to oneshot mode sets
934 : * the bit for all other cpus which are in the general
935 : * (periodic) broadcast mask. So the bit is set and
936 : * would prevent the first broadcast enter after this
937 : * to program the bc device.
938 : */
939 0 : tick_broadcast_clear_oneshot(cpu);
940 : }
941 : }
942 :
943 : /*
944 : * Select oneshot operating mode for the broadcast device
945 : */
946 4 : void tick_broadcast_switch_to_oneshot(void)
947 : {
948 4 : struct clock_event_device *bc;
949 4 : unsigned long flags;
950 :
951 4 : raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
952 :
953 4 : tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
954 4 : bc = tick_broadcast_device.evtdev;
955 4 : if (bc)
956 0 : tick_broadcast_setup_oneshot(bc);
957 :
958 4 : raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
959 4 : }
960 :
961 : #ifdef CONFIG_HOTPLUG_CPU
962 0 : void hotplug_cpu__broadcast_tick_pull(int deadcpu)
963 : {
964 0 : struct clock_event_device *bc;
965 0 : unsigned long flags;
966 :
967 0 : raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
968 0 : bc = tick_broadcast_device.evtdev;
969 :
970 0 : if (bc && broadcast_needs_cpu(bc, deadcpu)) {
971 : /* This moves the broadcast assignment to this CPU: */
972 0 : clockevents_program_event(bc, bc->next_event, 1);
973 : }
974 0 : raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
975 0 : }
976 :
977 : /*
978 : * Remove a dying CPU from broadcasting
979 : */
980 0 : static void tick_broadcast_oneshot_offline(unsigned int cpu)
981 : {
982 : /*
983 : * Clear the broadcast masks for the dead cpu, but do not stop
984 : * the broadcast device!
985 : */
986 0 : cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask);
987 0 : cpumask_clear_cpu(cpu, tick_broadcast_pending_mask);
988 0 : cpumask_clear_cpu(cpu, tick_broadcast_force_mask);
989 0 : }
990 : #endif
991 :
992 : /*
993 : * Check, whether the broadcast device is in one shot mode
994 : */
995 0 : int tick_broadcast_oneshot_active(void)
996 : {
997 0 : return tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT;
998 : }
999 :
1000 : /*
1001 : * Check whether the broadcast device supports oneshot.
1002 : */
1003 0 : bool tick_broadcast_oneshot_available(void)
1004 : {
1005 0 : struct clock_event_device *bc = tick_broadcast_device.evtdev;
1006 :
1007 0 : return bc ? bc->features & CLOCK_EVT_FEAT_ONESHOT : false;
1008 : }
1009 :
1010 : #else
1011 : int __tick_broadcast_oneshot_control(enum tick_broadcast_state state)
1012 : {
1013 : struct clock_event_device *bc = tick_broadcast_device.evtdev;
1014 :
1015 : if (!bc || (bc->features & CLOCK_EVT_FEAT_HRTIMER))
1016 : return -EBUSY;
1017 :
1018 : return 0;
1019 : }
1020 : #endif
1021 :
1022 1 : void __init tick_broadcast_init(void)
1023 : {
1024 1 : zalloc_cpumask_var(&tick_broadcast_mask, GFP_NOWAIT);
1025 1 : zalloc_cpumask_var(&tick_broadcast_on, GFP_NOWAIT);
1026 1 : zalloc_cpumask_var(&tmpmask, GFP_NOWAIT);
1027 : #ifdef CONFIG_TICK_ONESHOT
1028 1 : zalloc_cpumask_var(&tick_broadcast_oneshot_mask, GFP_NOWAIT);
1029 1 : zalloc_cpumask_var(&tick_broadcast_pending_mask, GFP_NOWAIT);
1030 1 : zalloc_cpumask_var(&tick_broadcast_force_mask, GFP_NOWAIT);
1031 : #endif
1032 1 : }
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