Branch data 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 : 11 : static bool tick_check_broadcast_device(struct clock_event_device *curdev,
77 : : struct clock_event_device *newdev)
78 : : {
79 : 11 : if ((newdev->features & CLOCK_EVT_FEAT_DUMMY) ||
80 : 11 : (newdev->features & CLOCK_EVT_FEAT_PERCPU) ||
81 : : (newdev->features & CLOCK_EVT_FEAT_C3STOP))
82 : : return false;
83 : :
84 [ - + ]: 11 : if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT &&
85 [ # # ]: 0 : !(newdev->features & CLOCK_EVT_FEAT_ONESHOT))
86 : : return false;
87 : :
88 [ - + - - ]: 11 : return !curdev || newdev->rating > curdev->rating;
89 : : }
90 : :
91 : : /*
92 : : * Conditionally install/replace broadcast device
93 : : */
94 : 11 : void tick_install_broadcast_device(struct clock_event_device *dev)
95 : : {
96 : 11 : struct clock_event_device *cur = tick_broadcast_device.evtdev;
97 : :
98 [ + - + - ]: 22 : if (!tick_check_broadcast_device(cur, dev))
99 : : return;
100 : :
101 [ + - ]: 11 : if (!try_module_get(dev->owner))
102 : : return;
103 : :
104 : 11 : clockevents_exchange_device(cur, dev);
105 [ - + ]: 11 : if (cur)
106 : 0 : cur->event_handler = clockevents_handle_noop;
107 : 11 : tick_broadcast_device.evtdev = dev;
108 [ - + ]: 11 : 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 [ + - ]: 11 : if (dev->features & CLOCK_EVT_FEAT_ONESHOT)
119 : 11 : tick_clock_notify();
120 : : }
121 : :
122 : : /*
123 : : * Check, if the device is the broadcast device
124 : : */
125 : 22 : int tick_is_broadcast_device(struct clock_event_device *dev)
126 : : {
127 [ - - + + : 22 : 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 : : static void tick_device_setup_broadcast_func(struct clock_event_device *dev)
149 : : {
150 : : if (!dev->broadcast)
151 : : dev->broadcast = tick_broadcast;
152 : : if (!dev->broadcast) {
153 : : pr_warn_once("%s depends on broadcast, but no broadcast function available\n",
154 : : dev->name);
155 : : dev->broadcast = err_broadcast;
156 : : }
157 : : }
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 : 22 : int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
164 : : {
165 : 22 : struct clock_event_device *bc = tick_broadcast_device.evtdev;
166 : 22 : unsigned long flags;
167 : 22 : int ret = 0;
168 : :
169 : 22 : 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 [ - + ]: 22 : 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 [ + + ]: 22 : if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
192 : 11 : cpumask_clear_cpu(cpu, tick_broadcast_mask);
193 : : else
194 : 11 : 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 [ + - ]: 22 : if (!cpumask_test_cpu(cpu, tick_broadcast_on))
201 : 22 : cpumask_clear_cpu(cpu, tick_broadcast_mask);
202 : :
203 [ - + - ]: 22 : switch (tick_broadcast_device.mode) {
204 : : 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 [ + - - + ]: 22 : 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 [ - + - - ]: 22 : 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 : 22 : raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
241 : 22 : 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(dev->next_event, tick_period);
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 : : /* fall through */
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 : 22 : void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
434 : : {
435 [ + - ]: 22 : if (!broadcast)
436 : 22 : dev->event_handler = tick_handle_periodic;
437 : : else
438 : 0 : dev->event_handler = tick_handle_periodic_broadcast;
439 : 22 : }
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 : 3938 : int tick_check_broadcast_expired(void)
545 : : {
546 : 3938 : 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 : 4158 : void tick_check_oneshot_broadcast_this_cpu(void)
585 : : {
586 [ - + ]: 4158 : 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 : 4158 : }
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 : : /**
881 : : * tick_broadcast_setup_oneshot - setup the broadcast device
882 : : */
883 : 11 : static void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
884 : : {
885 [ + - ]: 11 : int cpu = smp_processor_id();
886 : :
887 [ + - ]: 11 : if (!bc)
888 : : return;
889 : :
890 : : /* Set it up only once ! */
891 [ + - ]: 11 : if (bc->event_handler != tick_handle_oneshot_broadcast) {
892 : 11 : int was_periodic = clockevent_state_periodic(bc);
893 : :
894 : 11 : bc->event_handler = tick_handle_oneshot_broadcast;
895 : :
896 : : /*
897 : : * We must be careful here. There might be other CPUs
898 : : * waiting for periodic broadcast. We need to set the
899 : : * oneshot_mask bits for those and program the
900 : : * broadcast device to fire.
901 : : */
902 : 11 : cpumask_copy(tmpmask, tick_broadcast_mask);
903 : 11 : cpumask_clear_cpu(cpu, tmpmask);
904 [ - + ]: 11 : cpumask_or(tick_broadcast_oneshot_mask,
905 : : tick_broadcast_oneshot_mask, tmpmask);
906 : :
907 [ - + - - ]: 11 : if (was_periodic && !cpumask_empty(tmpmask)) {
908 : 0 : clockevents_switch_state(bc, CLOCK_EVT_STATE_ONESHOT);
909 : 0 : tick_broadcast_init_next_event(tmpmask,
910 : : tick_next_period);
911 : 0 : tick_broadcast_set_event(bc, cpu, tick_next_period);
912 : : } else
913 : 11 : bc->next_event = KTIME_MAX;
914 : : } else {
915 : : /*
916 : : * The first cpu which switches to oneshot mode sets
917 : : * the bit for all other cpus which are in the general
918 : : * (periodic) broadcast mask. So the bit is set and
919 : : * would prevent the first broadcast enter after this
920 : : * to program the bc device.
921 : : */
922 : 0 : tick_broadcast_clear_oneshot(cpu);
923 : : }
924 : : }
925 : :
926 : : /*
927 : : * Select oneshot operating mode for the broadcast device
928 : : */
929 : 11 : void tick_broadcast_switch_to_oneshot(void)
930 : : {
931 : 11 : struct clock_event_device *bc;
932 : 11 : unsigned long flags;
933 : :
934 : 11 : raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
935 : :
936 : 11 : tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
937 : 11 : bc = tick_broadcast_device.evtdev;
938 [ + - ]: 11 : if (bc)
939 : 11 : tick_broadcast_setup_oneshot(bc);
940 : :
941 : 11 : raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
942 : 11 : }
943 : :
944 : : #ifdef CONFIG_HOTPLUG_CPU
945 : 0 : void hotplug_cpu__broadcast_tick_pull(int deadcpu)
946 : : {
947 : 0 : struct clock_event_device *bc;
948 : 0 : unsigned long flags;
949 : :
950 : 0 : raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
951 : 0 : bc = tick_broadcast_device.evtdev;
952 : :
953 [ # # ]: 0 : if (bc && broadcast_needs_cpu(bc, deadcpu)) {
954 : : /* This moves the broadcast assignment to this CPU: */
955 : 0 : clockevents_program_event(bc, bc->next_event, 1);
956 : : }
957 : 0 : raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
958 : 0 : }
959 : :
960 : : /*
961 : : * Remove a dying CPU from broadcasting
962 : : */
963 : 0 : static void tick_broadcast_oneshot_offline(unsigned int cpu)
964 : : {
965 : : /*
966 : : * Clear the broadcast masks for the dead cpu, but do not stop
967 : : * the broadcast device!
968 : : */
969 : 0 : cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask);
970 : 0 : cpumask_clear_cpu(cpu, tick_broadcast_pending_mask);
971 : 0 : cpumask_clear_cpu(cpu, tick_broadcast_force_mask);
972 : 0 : }
973 : : #endif
974 : :
975 : : /*
976 : : * Check, whether the broadcast device is in one shot mode
977 : : */
978 : 22 : int tick_broadcast_oneshot_active(void)
979 : : {
980 : 22 : return tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT;
981 : : }
982 : :
983 : : /*
984 : : * Check whether the broadcast device supports oneshot.
985 : : */
986 : 11 : bool tick_broadcast_oneshot_available(void)
987 : : {
988 : 11 : struct clock_event_device *bc = tick_broadcast_device.evtdev;
989 : :
990 [ + - - + ]: 11 : return bc ? bc->features & CLOCK_EVT_FEAT_ONESHOT : false;
991 : : }
992 : :
993 : : #else
994 : : int __tick_broadcast_oneshot_control(enum tick_broadcast_state state)
995 : : {
996 : : struct clock_event_device *bc = tick_broadcast_device.evtdev;
997 : :
998 : : if (!bc || (bc->features & CLOCK_EVT_FEAT_HRTIMER))
999 : : return -EBUSY;
1000 : :
1001 : : return 0;
1002 : : }
1003 : : #endif
1004 : :
1005 : 11 : void __init tick_broadcast_init(void)
1006 : : {
1007 : 11 : zalloc_cpumask_var(&tick_broadcast_mask, GFP_NOWAIT);
1008 : 11 : zalloc_cpumask_var(&tick_broadcast_on, GFP_NOWAIT);
1009 : 11 : zalloc_cpumask_var(&tmpmask, GFP_NOWAIT);
1010 : : #ifdef CONFIG_TICK_ONESHOT
1011 : 11 : zalloc_cpumask_var(&tick_broadcast_oneshot_mask, GFP_NOWAIT);
1012 : 11 : zalloc_cpumask_var(&tick_broadcast_pending_mask, GFP_NOWAIT);
1013 : 11 : zalloc_cpumask_var(&tick_broadcast_force_mask, GFP_NOWAIT);
1014 : : #endif
1015 : 11 : }
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