aboutsummaryrefslogtreecommitdiffstats
path: root/arch/s390/kernel/vtime.c
blob: b59a812a010e2b1bd0861e30ae3d662c45d3e04a (plain) (blame)
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
570
571
572
573
574
/*
 *  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>
#include <asm/cputime.h>

static DEFINE_PER_CPU(struct vtimer_queue, virt_cpu_timer);

DEFINE_PER_CPU(struct s390_idle_data, s390_idle);

static inline __u64 get_vtimer(void)
{
	__u64 timer;

	asm volatile("STPT %0" : "=m" (timer));
	return timer;
}

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;
}

/*
 * Update process times based on virtual cpu times stored by entry.S
 * to the lowcore fields user_timer, system_timer & steal_clock.
 */
static void do_account_vtime(struct task_struct *tsk, int hardirq_offset)
{
	struct thread_info *ti = task_thread_info(tsk);
	__u64 timer, clock, user, system, steal;

	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_timer += S390_lowcore.last_update_clock - clock;

	user = S390_lowcore.user_timer - ti->user_timer;
	S390_lowcore.steal_timer -= user;
	ti->user_timer = S390_lowcore.user_timer;
	account_user_time(tsk, user, user);

	system = S390_lowcore.system_timer - ti->system_timer;
	S390_lowcore.steal_timer -= system;
	ti->system_timer = S390_lowcore.system_timer;
	account_system_time(tsk, hardirq_offset, system, system);

	steal = S390_lowcore.steal_timer;
	if ((s64) steal > 0) {
		S390_lowcore.steal_timer = 0;
		account_steal_time(steal);
	}
}

void account_vtime(struct task_struct *prev, struct task_struct *next)
{
	struct thread_info *ti;

	do_account_vtime(prev, 0);
	ti = task_thread_info(prev);
	ti->user_timer = S390_lowcore.user_timer;
	ti->system_timer = S390_lowcore.system_timer;
	ti = task_thread_info(next);
	S390_lowcore.user_timer = ti->user_timer;
	S390_lowcore.system_timer = ti->system_timer;
}

void account_process_tick(struct task_struct *tsk, int user_tick)
{
	do_account_vtime(tsk, HARDIRQ_OFFSET);
}

/*
 * 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)
{
	struct thread_info *ti = task_thread_info(tsk);
	__u64 timer, system;

	timer = S390_lowcore.last_update_timer;
	S390_lowcore.last_update_timer = get_vtimer();
	S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;

	system = S390_lowcore.system_timer - ti->system_timer;
	S390_lowcore.steal_timer -= system;
	ti->system_timer = S390_lowcore.system_timer;
	account_system_time(tsk, 0, system, system);
}
EXPORT_SYMBOL_GPL(account_system_vtime);

void vtime_start_cpu(void)
{
	struct s390_idle_data *idle = &__get_cpu_var(s390_idle);
	struct vtimer_queue *vq = &__get_cpu_var(virt_cpu_timer);
	__u64 idle_time, expires;

	/* Account time spent with enabled wait psw loaded as idle time. */
	idle_time = S390_lowcore.int_clock - idle->idle_enter;
	account_idle_time(idle_time);
	S390_lowcore.steal_timer +=
		idle->idle_enter - S390_lowcore.last_update_clock;
	S390_lowcore.last_update_clock = S390_lowcore.int_clock;

	/* Account system time spent going idle. */
	S390_lowcore.system_timer += S390_lowcore.last_update_timer - vq->idle;
	S390_lowcore.last_update_timer = S390_lowcore.async_enter_timer;

	/* Restart vtime CPU timer */
	if (vq->do_spt) {
		/* Program old expire value but first save progress. */
		expires = vq->idle - S390_lowcore.async_enter_timer;
		expires += get_vtimer();
		set_vtimer(expires);
	} else {
		/* Don't account the CPU timer delta while the cpu was idle. */
		vq->elapsed -= vq->idle - S390_lowcore.async_enter_timer;
	}

	idle->sequence++;
	smp_wmb();
	idle->idle_time += idle_time;
	idle->idle_enter = 0ULL;
	idle->idle_count++;
	smp_wmb();
	idle->sequence++;
}

void vtime_stop_cpu(void)
{
	struct s390_idle_data *idle = &__get_cpu_var(s390_idle);
	struct vtimer_queue *vq = &__get_cpu_var(virt_cpu_timer);
	psw_t psw;

	/* Wait for external, I/O or machine check interrupt. */
	psw.mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_IO | PSW_MASK_EXT;

	idle->nohz_delay = 0;

	/* Check if the CPU timer needs to be reprogrammed. */
	if (vq->do_spt) {
		__u64 vmax = VTIMER_MAX_SLICE;
		/*
		 * The inline assembly is equivalent to
		 *	vq->idle = get_cpu_timer();
		 *	set_cpu_timer(VTIMER_MAX_SLICE);
		 *	idle->idle_enter = get_clock();
		 *	__load_psw_mask(psw_kernel_bits | PSW_MASK_WAIT |
		 *			   PSW_MASK_IO | PSW_MASK_EXT);
		 * The difference is that the inline assembly makes sure that
		 * the last three instruction are stpt, stck and lpsw in that
		 * order. This is done to increase the precision.
		 */
		asm volatile(
#ifndef CONFIG_64BIT
			"	basr	1,0\n"
			"0:	ahi	1,1f-0b\n"
			"	st	1,4(%2)\n"
#else /* CONFIG_64BIT */
			"	larl	1,1f\n"
			"	stg	1,8(%2)\n"
#endif /* CONFIG_64BIT */
			"	stpt	0(%4)\n"
			"	spt	0(%5)\n"
			"	stck	0(%3)\n"
#ifndef CONFIG_64BIT
			"	lpsw	0(%2)\n"
#else /* CONFIG_64BIT */
			"	lpswe	0(%2)\n"
#endif /* CONFIG_64BIT */
			"1:"
			: "=m" (idle->idle_enter), "=m" (vq->idle)
			: "a" (&psw), "a" (&idle->idle_enter),
			  "a" (&vq->idle), "a" (&vmax), "m" (vmax), "m" (psw)
			: "memory", "cc", "1");
	} else {
		/*
		 * The inline assembly is equivalent to
		 *	vq->idle = get_cpu_timer();
		 *	idle->idle_enter = get_clock();
		 *	__load_psw_mask(psw_kernel_bits | PSW_MASK_WAIT |
		 *			   PSW_MASK_IO | PSW_MASK_EXT);
		 * The difference is that the inline assembly makes sure that
		 * the last three instruction are stpt, stck and lpsw in that
		 * order. This is done to increase the precision.
		 */
		asm volatile(
#ifndef CONFIG_64BIT
			"	basr	1,0\n"
			"0:	ahi	1,1f-0b\n"
			"	st	1,4(%2)\n"
#else /* CONFIG_64BIT */
			"	larl	1,1f\n"
			"	stg	1,8(%2)\n"
#endif /* CONFIG_64BIT */
			"	stpt	0(%4)\n"
			"	stck	0(%3)\n"
#ifndef CONFIG_64BIT
			"	lpsw	0(%2)\n"
#else /* CONFIG_64BIT */
			"	lpswe	0(%2)\n"
#endif /* CONFIG_64BIT */
			"1:"
			: "=m" (idle->idle_enter), "=m" (vq->idle)
			: "a" (&psw), "a" (&idle->idle_enter),
			  "a" (&vq->idle), "m" (psw)
			: "memory", "cc", "1");
	}
}

cputime64_t s390_get_idle_time(int cpu)
{
	struct s390_idle_data *idle;
	unsigned long long now, idle_time, idle_enter;
	unsigned int sequence;

	idle = &per_cpu(s390_idle, cpu);

	now = get_clock();
repeat:
	sequence = idle->sequence;
	smp_rmb();
	if (sequence & 1)
		goto repeat;
	idle_time = 0;
	idle_enter = idle->idle_enter;
	if (idle_enter != 0ULL && idle_enter < now)
		idle_time = now - idle_enter;
	smp_rmb();
	if (idle->sequence != sequence)
		goto repeat;
	return idle_time;
}

/*
 * 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 *vq;
	struct vtimer_list *event, *tmp;

	if (list_empty(cb_list))
		return;

	vq = &__get_cpu_var(virt_cpu_timer);

	list_for_each_entry_safe(event, tmp, cb_list, entry) {
		list_del_init(&event->entry);
		(event->function)(event->data);
		if (event->interval) {
			/* Recharge interval timer */
			event->expires = event->interval + vq->elapsed;
			spin_lock(&vq->lock);
			list_add_sorted(event, &vq->list);
			spin_unlock(&vq->lock);
		}
	}
}

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

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

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

	elapsed = vq->elapsed + (vq->timer - S390_lowcore.async_enter_timer);
	BUG_ON((s64) elapsed < 0);
	vq->elapsed = 0;
	list_for_each_entry_safe(event, tmp, &vq->list, entry) {
		if (event->expires < elapsed)
			/* move expired timer to the callback queue */
			list_move_tail(&event->entry, &cb_list);
		else
			event->expires -= elapsed;
	}
	spin_unlock(&vq->lock);

	vq->do_spt = list_empty(&cb_list);
	do_callbacks(&cb_list);

	/* next event is first in list */
	next = VTIMER_MAX_SLICE;
	spin_lock(&vq->lock);
	if (!list_empty(&vq->list)) {
		event = list_first_entry(&vq->list, struct vtimer_list, entry);
		next = event->expires;
	} else
		vq->do_spt = 0;
	spin_unlock(&vq->lock);
	/*
	 * To improve precision add the time spent by the
	 * interrupt handler to the elapsed time.
	 * Note: CPU timer counts down and we got an interrupt,
	 *	 the current content is negative
	 */
	elapsed = S390_lowcore.async_enter_timer - get_vtimer();
	set_vtimer(next - elapsed);
	vq->timer = next - elapsed;
	vq->elapsed = elapsed;
}

void init_virt_timer(struct vtimer_list *timer)
{
	timer->function = NULL;
	INIT_LIST_HEAD(&timer->entry);
}
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)
{
	struct vtimer_queue *vq;
	unsigned long flags;
	__u64 left, expires;

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

	BUG_ON(timer->cpu != smp_processor_id());

	if (list_empty(&vq->list)) {
		/* First timer on this cpu, just program it. */
		list_add(&timer->entry, &vq->list);
		set_vtimer(timer->expires);
		vq->timer = timer->expires;
		vq->elapsed = 0;
	} else {
		/* Check progress of old timers. */
		expires = timer->expires;
		left = get_vtimer();
		if (likely((s64) expires < (s64) left)) {
			/* The new timer expires before the current timer. */
			set_vtimer(expires);
			vq->elapsed += vq->timer - left;
			vq->timer = expires;
		} else {
			vq->elapsed += vq->timer - left;
			vq->timer = left;
		}
		/* Insert new timer into per cpu list. */
		timer->expires += vq->elapsed;
		list_add_sorted(timer, &vq->list);
	}

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

static inline void prepare_vtimer(struct vtimer_list *timer)
{
	BUG_ON(!timer->function);
	BUG_ON(!timer->expires || timer->expires > VTIMER_MAX_SLICE);
	BUG_ON(vtimer_pending(timer));
	timer->cpu = get_cpu();
}

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

	timer = (struct vtimer_list *)new;
	prepare_vtimer(timer);
	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;
	prepare_vtimer(timer);
	timer->interval = timer->expires;
	internal_add_vtimer(timer);
}
EXPORT_SYMBOL(add_virt_timer_periodic);

int __mod_vtimer(struct vtimer_list *timer, __u64 expires, int periodic)
{
	struct vtimer_queue *vq;
	unsigned long flags;
	int cpu;

	BUG_ON(!timer->function);
	BUG_ON(!expires || expires > VTIMER_MAX_SLICE);

	if (timer->expires == expires && vtimer_pending(timer))
		return 1;

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

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

	/* if timer isn't pending add it on the current CPU */
	if (!vtimer_pending(timer)) {
		spin_unlock_irqrestore(&vq->lock, flags);

		if (periodic)
			timer->interval = expires;
		else
			timer->interval = 0;
		timer->expires = expires;
		timer->cpu = cpu;
		internal_add_vtimer(timer);
		return 0;
	}

	/* check if we run on the right CPU */
	BUG_ON(timer->cpu != cpu);

	list_del_init(&timer->entry);
	timer->expires = expires;
	if (periodic)
		timer->interval = expires;

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

/*
 * If we change a pending timer the function must be called on the CPU
 * where the timer is running on.
 *
 * returns whether it has modified a pending timer (1) or not (0)
 */
int mod_virt_timer(struct vtimer_list *timer, __u64 expires)
{
	return __mod_vtimer(timer, expires, 0);
}
EXPORT_SYMBOL(mod_virt_timer);

/*
 * If we change a pending timer the function must be called on the CPU
 * where the timer is running on.
 *
 * returns whether it has modified a pending timer (1) or not (0)
 */
int mod_virt_timer_periodic(struct vtimer_list *timer, __u64 expires)
{
	return __mod_vtimer(timer, expires, 1);
}
EXPORT_SYMBOL(mod_virt_timer_periodic);

/*
 * 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 *vq;

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

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

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

	spin_unlock_irqrestore(&vq->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 *vq;

	/* initialize per cpu vtimer structure */
	vq = &__get_cpu_var(virt_cpu_timer);
	INIT_LIST_HEAD(&vq->list);
	spin_lock_init(&vq->lock);

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

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

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