aboutsummaryrefslogtreecommitdiffstats
path: root/arch/s390/kernel/vtime.c
blob: c5f05b3fb2c30f1548a062280be08fc12411340d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
/*
 *  arch/s390/kernel/vtime.c
 *    Virtual cpu timer based timer functions.
 *
 *  S390 version
 *    Copyright (C) 2004 IBM Deutschland Entwicklung GmbH, IBM Corporation
 *    Author(s): Jan Glauber <jan.glauber@de.ibm.com>
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/time.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/types.h>
#include <linux/timex.h>
#include <linux/notifier.h>
#include <linux/kernel_stat.h>
#include <linux/rcupdate.h>
#include <linux/posix-timers.h>

#include <asm/s390_ext.h>
#include <asm/timer.h>
#include <asm/irq_regs.h>

static ext_int_info_t ext_int_info_timer;
static DEFINE_PER_CPU(struct vtimer_queue, virt_cpu_timer);

#ifdef CONFIG_VIRT_CPU_ACCOUNTING
/*
 * Update process times based on virtual cpu times stored by entry.S
 * to the lowcore fields user_timer, system_timer & steal_clock.
 */
void account_process_tick(struct task_struct *tsk, int user_tick)
{
	cputime_t cputime;
	__u64 timer, clock;
	int rcu_user_flag;

	timer = S390_lowcore.last_update_timer;
	clock = S390_lowcore.last_update_clock;
	asm volatile ("  STPT %0\n"    /* Store current cpu timer value */
		      "  STCK %1"      /* Store current tod clock value */
		      : "=m" (S390_lowcore.last_update_timer),
		        "=m" (S390_lowcore.last_update_clock) );
	S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
	S390_lowcore.steal_clock += S390_lowcore.last_update_clock - clock;

	cputime = S390_lowcore.user_timer >> 12;
	rcu_user_flag = cputime != 0;
	S390_lowcore.user_timer -= cputime << 12;
	S390_lowcore.steal_clock -= cputime << 12;
	account_user_time(tsk, cputime);

	cputime =  S390_lowcore.system_timer >> 12;
	S390_lowcore.system_timer -= cputime << 12;
	S390_lowcore.steal_clock -= cputime << 12;
	account_system_time(tsk, HARDIRQ_OFFSET, cputime);

	cputime = S390_lowcore.steal_clock;
	if ((__s64) cputime > 0) {
		cputime >>= 12;
		S390_lowcore.steal_clock -= cputime << 12;
		account_steal_time(tsk, cputime);
	}
}

/*
 * Update process times based on virtual cpu times stored by entry.S
 * to the lowcore fields user_timer, system_timer & steal_clock.
 */
void account_vtime(struct task_struct *tsk)
{
	cputime_t cputime;
	__u64 timer;

	timer = S390_lowcore.last_update_timer;
	asm volatile ("  STPT %0"    /* Store current cpu timer value */
		      : "=m" (S390_lowcore.last_update_timer) );
	S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;

	cputime = S390_lowcore.user_timer >> 12;
	S390_lowcore.user_timer -= cputime << 12;
	S390_lowcore.steal_clock -= cputime << 12;
	account_user_time(tsk, cputime);

	cputime =  S390_lowcore.system_timer >> 12;
	S390_lowcore.system_timer -= cputime << 12;
	S390_lowcore.steal_clock -= cputime << 12;
	account_system_time(tsk, 0, cputime);
}

/*
 * Update process times based on virtual cpu times stored by entry.S
 * to the lowcore fields user_timer, system_timer & steal_clock.
 */
void account_system_vtime(struct task_struct *tsk)
{
	cputime_t cputime;
	__u64 timer;

	timer = S390_lowcore.last_update_timer;
	asm volatile ("  STPT %0"    /* Store current cpu timer value */
		      : "=m" (S390_lowcore.last_update_timer) );
	S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;

	cputime =  S390_lowcore.system_timer >> 12;
	S390_lowcore.system_timer -= cputime << 12;
	S390_lowcore.steal_clock -= cputime << 12;
	account_system_time(tsk, 0, cputime);
}

static inline void set_vtimer(__u64 expires)
{
	__u64 timer;

	asm volatile ("  STPT %0\n"  /* Store current cpu timer value */
		      "  SPT %1"     /* Set new value immediatly afterwards */
		      : "=m" (timer) : "m" (expires) );
	S390_lowcore.system_timer += S390_lowcore.last_update_timer - timer;
	S390_lowcore.last_update_timer = expires;

	/* store expire time for this CPU timer */
	__get_cpu_var(virt_cpu_timer).to_expire = expires;
}
#else
static inline void set_vtimer(__u64 expires)
{
	S390_lowcore.last_update_timer = expires;
	asm volatile ("SPT %0" : : "m" (S390_lowcore.last_update_timer));

	/* store expire time for this CPU timer */
	__get_cpu_var(virt_cpu_timer).to_expire = expires;
}
#endif

static void start_cpu_timer(void)
{
	struct vtimer_queue *vt_list;

	vt_list = &__get_cpu_var(virt_cpu_timer);

	/* CPU timer interrupt is pending, don't reprogramm it */
	if (vt_list->idle & 1LL<<63)
		return;

	if (!list_empty(&vt_list->list))
		set_vtimer(vt_list->idle);
}

static void stop_cpu_timer(void)
{
	struct vtimer_queue *vt_list;

	vt_list = &__get_cpu_var(virt_cpu_timer);

	/* nothing to do */
	if (list_empty(&vt_list->list)) {
		vt_list->idle = VTIMER_MAX_SLICE;
		goto fire;
	}

	/* store the actual expire value */
	asm volatile ("STPT %0" : "=m" (vt_list->idle));

	/*
	 * If the CPU timer is negative we don't reprogramm
	 * it because we will get instantly an interrupt.
	 */
	if (vt_list->idle & 1LL<<63)
		return;

	vt_list->offset += vt_list->to_expire - vt_list->idle;

	/*
	 * We cannot halt the CPU timer, we just write a value that
	 * nearly never expires (only after 71 years) and re-write
	 * the stored expire value if we continue the timer
	 */
 fire:
	set_vtimer(VTIMER_MAX_SLICE);
}

/*
 * Sorted add to a list. List is linear searched until first bigger
 * element is found.
 */
static void list_add_sorted(struct vtimer_list *timer, struct list_head *head)
{
	struct vtimer_list *event;

	list_for_each_entry(event, head, entry) {
		if (event->expires > timer->expires) {
			list_add_tail(&timer->entry, &event->entry);
			return;
		}
	}
	list_add_tail(&timer->entry, head);
}

/*
 * Do the callback functions of expired vtimer events.
 * Called from within the interrupt handler.
 */
static void do_callbacks(struct list_head *cb_list)
{
	struct vtimer_queue *vt_list;
	struct vtimer_list *event, *tmp;
	void (*fn)(unsigned long);
	unsigned long data;

	if (list_empty(cb_list))
		return;

	vt_list = &__get_cpu_var(virt_cpu_timer);

	list_for_each_entry_safe(event, tmp, cb_list, entry) {
		fn = event->function;
		data = event->data;
		fn(data);

		if (!event->interval)
			/* delete one shot timer */
			list_del_init(&event->entry);
		else {
			/* move interval timer back to list */
			spin_lock(&vt_list->lock);
			list_del_init(&event->entry);
			list_add_sorted(event, &vt_list->list);
			spin_unlock(&vt_list->lock);
		}
	}
}

/*
 * Handler for the virtual CPU timer.
 */
static void do_cpu_timer_interrupt(__u16 error_code)
{
	__u64 next, delta;
	struct vtimer_queue *vt_list;
	struct vtimer_list *event, *tmp;
	struct list_head *ptr;
	/* the callback queue */
	struct list_head cb_list;

	INIT_LIST_HEAD(&cb_list);
	vt_list = &__get_cpu_var(virt_cpu_timer);

	/* walk timer list, fire all expired events */
	spin_lock(&vt_list->lock);

	if (vt_list->to_expire < VTIMER_MAX_SLICE)
		vt_list->offset += vt_list->to_expire;

	list_for_each_entry_safe(event, tmp, &vt_list->list, entry) {
		if (event->expires > vt_list->offset)
			/* found first unexpired event, leave */
			break;

		/* re-charge interval timer, we have to add the offset */
		if (event->interval)
			event->expires = event->interval + vt_list->offset;

		/* move expired timer to the callback queue */
		list_move_tail(&event->entry, &cb_list);
	}
	spin_unlock(&vt_list->lock);
	do_callbacks(&cb_list);

	/* next event is first in list */
	spin_lock(&vt_list->lock);
	if (!list_empty(&vt_list->list)) {
		ptr = vt_list->list.next;
		event = list_entry(ptr, struct vtimer_list, entry);
		next = event->expires - vt_list->offset;

		/* add the expired time from this interrupt handler
		 * and the callback functions
		 */
		asm volatile ("STPT %0" : "=m" (delta));
		delta = 0xffffffffffffffffLL - delta + 1;
		vt_list->offset += delta;
		next -= delta;
	} else {
		vt_list->offset = 0;
		next = VTIMER_MAX_SLICE;
	}
	spin_unlock(&vt_list->lock);
	set_vtimer(next);
}

void init_virt_timer(struct vtimer_list *timer)
{
	timer->function = NULL;
	INIT_LIST_HEAD(&timer->entry);
	spin_lock_init(&timer->lock);
}
EXPORT_SYMBOL(init_virt_timer);

static inline int vtimer_pending(struct vtimer_list *timer)
{
	return (!list_empty(&timer->entry));
}

/*
 * this function should only run on the specified CPU
 */
static void internal_add_vtimer(struct vtimer_list *timer)
{
	unsigned long flags;
	__u64 done;
	struct vtimer_list *event;
	struct vtimer_queue *vt_list;

	vt_list = &per_cpu(virt_cpu_timer, timer->cpu);
	spin_lock_irqsave(&vt_list->lock, flags);

	if (timer->cpu != smp_processor_id())
		printk("internal_add_vtimer: BUG, running on wrong CPU");

	/* if list is empty we only have to set the timer */
	if (list_empty(&vt_list->list)) {
		/* reset the offset, this may happen if the last timer was
		 * just deleted by mod_virt_timer and the interrupt
		 * didn't happen until here
		 */
		vt_list->offset = 0;
		goto fire;
	}

	/* save progress */
	asm volatile ("STPT %0" : "=m" (done));

	/* calculate completed work */
	done = vt_list->to_expire - done + vt_list->offset;
	vt_list->offset = 0;

	list_for_each_entry(event, &vt_list->list, entry)
		event->expires -= done;

 fire:
	list_add_sorted(timer, &vt_list->list);

	/* get first element, which is the next vtimer slice */
	event = list_entry(vt_list->list.next, struct vtimer_list, entry);

	set_vtimer(event->expires);
	spin_unlock_irqrestore(&vt_list->lock, flags);
	/* release CPU acquired in prepare_vtimer or mod_virt_timer() */
	put_cpu();
}

static inline int prepare_vtimer(struct vtimer_list *timer)
{
	if (!timer->function) {
		printk("add_virt_timer: uninitialized timer\n");
		return -EINVAL;
	}

	if (!timer->expires || timer->expires > VTIMER_MAX_SLICE) {
		printk("add_virt_timer: invalid timer expire value!\n");
		return -EINVAL;
	}

	if (vtimer_pending(timer)) {
		printk("add_virt_timer: timer pending\n");
		return -EBUSY;
	}

	timer->cpu = get_cpu();
	return 0;
}

/*
 * add_virt_timer - add an oneshot virtual CPU timer
 */
void add_virt_timer(void *new)
{
	struct vtimer_list *timer;

	timer = (struct vtimer_list *)new;

	if (prepare_vtimer(timer) < 0)
		return;

	timer->interval = 0;
	internal_add_vtimer(timer);
}
EXPORT_SYMBOL(add_virt_timer);

/*
 * add_virt_timer_int - add an interval virtual CPU timer
 */
void add_virt_timer_periodic(void *new)
{
	struct vtimer_list *timer;

	timer = (struct vtimer_list *)new;

	if (prepare_vtimer(timer) < 0)
		return;

	timer->interval = timer->expires;
	internal_add_vtimer(timer);
}
EXPORT_SYMBOL(add_virt_timer_periodic);

/*
 * If we change a pending timer the function must be called on the CPU
 * where the timer is running on, e.g. by smp_call_function_single()
 *
 * The original mod_timer adds the timer if it is not pending. For compatibility
 * we do the same. The timer will be added on the current CPU as a oneshot timer.
 *
 * returns whether it has modified a pending timer (1) or not (0)
 */
int mod_virt_timer(struct vtimer_list *timer, __u64 expires)
{
	struct vtimer_queue *vt_list;
	unsigned long flags;
	int cpu;

	if (!timer->function) {
		printk("mod_virt_timer: uninitialized timer\n");
		return	-EINVAL;
	}

	if (!expires || expires > VTIMER_MAX_SLICE) {
		printk("mod_virt_timer: invalid expire range\n");
		return -EINVAL;
	}

	/*
	 * This is a common optimization triggered by the
	 * networking code - if the timer is re-modified
	 * to be the same thing then just return:
	 */
	if (timer->expires == expires && vtimer_pending(timer))
		return 1;

	cpu = get_cpu();
	vt_list = &per_cpu(virt_cpu_timer, cpu);

	/* disable interrupts before test if timer is pending */
	spin_lock_irqsave(&vt_list->lock, flags);

	/* if timer isn't pending add it on the current CPU */
	if (!vtimer_pending(timer)) {
		spin_unlock_irqrestore(&vt_list->lock, flags);
		/* we do not activate an interval timer with mod_virt_timer */
		timer->interval = 0;
		timer->expires = expires;
		timer->cpu = cpu;
		internal_add_vtimer(timer);
		return 0;
	}

	/* check if we run on the right CPU */
	if (timer->cpu != cpu) {
		printk("mod_virt_timer: running on wrong CPU, check your code\n");
		spin_unlock_irqrestore(&vt_list->lock, flags);
		put_cpu();
		return -EINVAL;
	}

	list_del_init(&timer->entry);
	timer->expires = expires;

	/* also change the interval if we have an interval timer */
	if (timer->interval)
		timer->interval = expires;

	/* the timer can't expire anymore so we can release the lock */
	spin_unlock_irqrestore(&vt_list->lock, flags);
	internal_add_vtimer(timer);
	return 1;
}
EXPORT_SYMBOL(mod_virt_timer);

/*
 * delete a virtual timer
 *
 * returns whether the deleted timer was pending (1) or not (0)
 */
int del_virt_timer(struct vtimer_list *timer)
{
	unsigned long flags;
	struct vtimer_queue *vt_list;

	/* check if timer is pending */
	if (!vtimer_pending(timer))
		return 0;

	vt_list = &per_cpu(virt_cpu_timer, timer->cpu);
	spin_lock_irqsave(&vt_list->lock, flags);

	/* we don't interrupt a running timer, just let it expire! */
	list_del_init(&timer->entry);

	/* last timer removed */
	if (list_empty(&vt_list->list)) {
		vt_list->to_expire = 0;
		vt_list->offset = 0;
	}

	spin_unlock_irqrestore(&vt_list->lock, flags);
	return 1;
}
EXPORT_SYMBOL(del_virt_timer);

/*
 * Start the virtual CPU timer on the current CPU.
 */
void init_cpu_vtimer(void)
{
	struct vtimer_queue *vt_list;

	/* kick the virtual timer */
	S390_lowcore.exit_timer = VTIMER_MAX_SLICE;
	S390_lowcore.last_update_timer = VTIMER_MAX_SLICE;
	asm volatile ("SPT %0" : : "m" (S390_lowcore.last_update_timer));
	asm volatile ("STCK %0" : "=m" (S390_lowcore.last_update_clock));

	/* enable cpu timer interrupts */
	__ctl_set_bit(0,10);

	vt_list = &__get_cpu_var(virt_cpu_timer);
	INIT_LIST_HEAD(&vt_list->list);
	spin_lock_init(&vt_list->lock);
	vt_list->to_expire = 0;
	vt_list->offset = 0;
	vt_list->idle = 0;

}

static int vtimer_idle_notify(struct notifier_block *self,
			      unsigned long action, void *hcpu)
{
	switch (action) {
	case S390_CPU_IDLE:
		stop_cpu_timer();
		break;
	case S390_CPU_NOT_IDLE:
		start_cpu_timer();
		break;
	}
	return NOTIFY_OK;
}

static struct notifier_block vtimer_idle_nb = {
	.notifier_call = vtimer_idle_notify,
};

void __init vtime_init(void)
{
	/* request the cpu timer external interrupt */
	if (register_early_external_interrupt(0x1005, do_cpu_timer_interrupt,
					      &ext_int_info_timer) != 0)
		panic("Couldn't request external interrupt 0x1005");

	if (register_idle_notifier(&vtimer_idle_nb))
		panic("Couldn't register idle notifier");

	/* Enable cpu timer interrupts on the boot cpu. */
	init_cpu_vtimer();
}