2 * arch/s390/kernel/vtime.c
3 * Virtual cpu timer based timer functions.
6 * Copyright (C) 2004 IBM Deutschland Entwicklung GmbH, IBM Corporation
7 * Author(s): Jan Glauber <jan.glauber@de.ibm.com>
10 #include <linux/module.h>
11 #include <linux/kernel.h>
12 #include <linux/time.h>
13 #include <linux/delay.h>
14 #include <linux/init.h>
15 #include <linux/smp.h>
16 #include <linux/types.h>
17 #include <linux/timex.h>
18 #include <linux/notifier.h>
19 #include <linux/kernel_stat.h>
20 #include <linux/rcupdate.h>
21 #include <linux/posix-timers.h>
23 #include <asm/s390_ext.h>
24 #include <asm/timer.h>
25 #include <asm/irq_regs.h>
26 #include <asm/cputime.h>
28 static DEFINE_PER_CPU(struct vtimer_queue, virt_cpu_timer);
30 DEFINE_PER_CPU(struct s390_idle_data, s390_idle);
32 static inline __u64 get_vtimer(void)
36 asm volatile("STPT %0" : "=m" (timer));
40 static inline void set_vtimer(__u64 expires)
44 asm volatile (" STPT %0\n" /* Store current cpu timer value */
45 " SPT %1" /* Set new value immediatly afterwards */
46 : "=m" (timer) : "m" (expires) );
47 S390_lowcore.system_timer += S390_lowcore.last_update_timer - timer;
48 S390_lowcore.last_update_timer = expires;
52 * Update process times based on virtual cpu times stored by entry.S
53 * to the lowcore fields user_timer, system_timer & steal_clock.
55 static void do_account_vtime(struct task_struct *tsk, int hardirq_offset)
57 struct thread_info *ti = task_thread_info(tsk);
58 __u64 timer, clock, user, system, steal;
60 timer = S390_lowcore.last_update_timer;
61 clock = S390_lowcore.last_update_clock;
62 asm volatile (" STPT %0\n" /* Store current cpu timer value */
63 " STCK %1" /* Store current tod clock value */
64 : "=m" (S390_lowcore.last_update_timer),
65 "=m" (S390_lowcore.last_update_clock) );
66 S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
67 S390_lowcore.steal_timer += S390_lowcore.last_update_clock - clock;
69 user = S390_lowcore.user_timer - ti->user_timer;
70 S390_lowcore.steal_timer -= user;
71 ti->user_timer = S390_lowcore.user_timer;
72 account_user_time(tsk, user, user);
74 system = S390_lowcore.system_timer - ti->system_timer;
75 S390_lowcore.steal_timer -= system;
76 ti->system_timer = S390_lowcore.system_timer;
77 account_system_time(tsk, hardirq_offset, system, system);
79 steal = S390_lowcore.steal_timer;
80 if ((s64) steal > 0) {
81 S390_lowcore.steal_timer = 0;
82 account_steal_time(steal);
86 void account_vtime(struct task_struct *prev, struct task_struct *next)
88 struct thread_info *ti;
90 do_account_vtime(prev, 0);
91 ti = task_thread_info(prev);
92 ti->user_timer = S390_lowcore.user_timer;
93 ti->system_timer = S390_lowcore.system_timer;
94 ti = task_thread_info(next);
95 S390_lowcore.user_timer = ti->user_timer;
96 S390_lowcore.system_timer = ti->system_timer;
99 void account_process_tick(struct task_struct *tsk, int user_tick)
101 do_account_vtime(tsk, HARDIRQ_OFFSET);
105 * Update process times based on virtual cpu times stored by entry.S
106 * to the lowcore fields user_timer, system_timer & steal_clock.
108 void account_system_vtime(struct task_struct *tsk)
110 struct thread_info *ti = task_thread_info(tsk);
113 timer = S390_lowcore.last_update_timer;
114 S390_lowcore.last_update_timer = get_vtimer();
115 S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
117 system = S390_lowcore.system_timer - ti->system_timer;
118 S390_lowcore.steal_timer -= system;
119 ti->system_timer = S390_lowcore.system_timer;
120 account_system_time(tsk, 0, system, system);
122 EXPORT_SYMBOL_GPL(account_system_vtime);
124 void vtime_start_cpu(__u64 int_clock, __u64 enter_timer)
126 struct s390_idle_data *idle = &__get_cpu_var(s390_idle);
127 struct vtimer_queue *vq = &__get_cpu_var(virt_cpu_timer);
128 __u64 idle_time, expires;
130 if (idle->idle_enter == 0ULL)
133 /* Account time spent with enabled wait psw loaded as idle time. */
134 idle_time = int_clock - idle->idle_enter;
135 account_idle_time(idle_time);
136 S390_lowcore.steal_timer +=
137 idle->idle_enter - S390_lowcore.last_update_clock;
138 S390_lowcore.last_update_clock = int_clock;
140 /* Account system time spent going idle. */
141 S390_lowcore.system_timer += S390_lowcore.last_update_timer - vq->idle;
142 S390_lowcore.last_update_timer = enter_timer;
144 /* Restart vtime CPU timer */
146 /* Program old expire value but first save progress. */
147 expires = vq->idle - enter_timer;
148 expires += get_vtimer();
151 /* Don't account the CPU timer delta while the cpu was idle. */
152 vq->elapsed -= vq->idle - enter_timer;
157 idle->idle_time += idle_time;
158 idle->idle_enter = 0ULL;
164 void vtime_stop_cpu(void)
166 struct s390_idle_data *idle = &__get_cpu_var(s390_idle);
167 struct vtimer_queue *vq = &__get_cpu_var(virt_cpu_timer);
170 /* Wait for external, I/O or machine check interrupt. */
171 psw.mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_IO | PSW_MASK_EXT;
173 idle->nohz_delay = 0;
175 /* Check if the CPU timer needs to be reprogrammed. */
177 __u64 vmax = VTIMER_MAX_SLICE;
179 * The inline assembly is equivalent to
180 * vq->idle = get_cpu_timer();
181 * set_cpu_timer(VTIMER_MAX_SLICE);
182 * idle->idle_enter = get_clock();
183 * __load_psw_mask(psw_kernel_bits | PSW_MASK_WAIT |
184 * PSW_MASK_IO | PSW_MASK_EXT);
185 * The difference is that the inline assembly makes sure that
186 * the last three instruction are stpt, stck and lpsw in that
187 * order. This is done to increase the precision.
194 #else /* CONFIG_64BIT */
197 #endif /* CONFIG_64BIT */
203 #else /* CONFIG_64BIT */
205 #endif /* CONFIG_64BIT */
207 : "=m" (idle->idle_enter), "=m" (vq->idle)
208 : "a" (&psw), "a" (&idle->idle_enter),
209 "a" (&vq->idle), "a" (&vmax), "m" (vmax), "m" (psw)
210 : "memory", "cc", "1");
213 * The inline assembly is equivalent to
214 * vq->idle = get_cpu_timer();
215 * idle->idle_enter = get_clock();
216 * __load_psw_mask(psw_kernel_bits | PSW_MASK_WAIT |
217 * PSW_MASK_IO | PSW_MASK_EXT);
218 * The difference is that the inline assembly makes sure that
219 * the last three instruction are stpt, stck and lpsw in that
220 * order. This is done to increase the precision.
227 #else /* CONFIG_64BIT */
230 #endif /* CONFIG_64BIT */
235 #else /* CONFIG_64BIT */
237 #endif /* CONFIG_64BIT */
239 : "=m" (idle->idle_enter), "=m" (vq->idle)
240 : "a" (&psw), "a" (&idle->idle_enter),
241 "a" (&vq->idle), "m" (psw)
242 : "memory", "cc", "1");
246 cputime64_t s390_get_idle_time(int cpu)
248 struct s390_idle_data *idle;
249 unsigned long long now, idle_time, idle_enter;
250 unsigned int sequence;
252 idle = &per_cpu(s390_idle, cpu);
256 sequence = idle->sequence;
261 idle_enter = idle->idle_enter;
262 if (idle_enter != 0ULL && idle_enter < now)
263 idle_time = now - idle_enter;
265 if (idle->sequence != sequence)
271 * Sorted add to a list. List is linear searched until first bigger
274 static void list_add_sorted(struct vtimer_list *timer, struct list_head *head)
276 struct vtimer_list *event;
278 list_for_each_entry(event, head, entry) {
279 if (event->expires > timer->expires) {
280 list_add_tail(&timer->entry, &event->entry);
284 list_add_tail(&timer->entry, head);
288 * Do the callback functions of expired vtimer events.
289 * Called from within the interrupt handler.
291 static void do_callbacks(struct list_head *cb_list)
293 struct vtimer_queue *vq;
294 struct vtimer_list *event, *tmp;
296 if (list_empty(cb_list))
299 vq = &__get_cpu_var(virt_cpu_timer);
301 list_for_each_entry_safe(event, tmp, cb_list, entry) {
302 list_del_init(&event->entry);
303 (event->function)(event->data);
304 if (event->interval) {
305 /* Recharge interval timer */
306 event->expires = event->interval + vq->elapsed;
307 spin_lock(&vq->lock);
308 list_add_sorted(event, &vq->list);
309 spin_unlock(&vq->lock);
315 * Handler for the virtual CPU timer.
317 static void do_cpu_timer_interrupt(__u16 error_code)
319 struct vtimer_queue *vq;
320 struct vtimer_list *event, *tmp;
321 struct list_head cb_list; /* the callback queue */
324 INIT_LIST_HEAD(&cb_list);
325 vq = &__get_cpu_var(virt_cpu_timer);
327 /* walk timer list, fire all expired events */
328 spin_lock(&vq->lock);
330 elapsed = vq->elapsed + (vq->timer - S390_lowcore.async_enter_timer);
331 BUG_ON((s64) elapsed < 0);
333 list_for_each_entry_safe(event, tmp, &vq->list, entry) {
334 if (event->expires < elapsed)
335 /* move expired timer to the callback queue */
336 list_move_tail(&event->entry, &cb_list);
338 event->expires -= elapsed;
340 spin_unlock(&vq->lock);
342 vq->do_spt = list_empty(&cb_list);
343 do_callbacks(&cb_list);
345 /* next event is first in list */
346 next = VTIMER_MAX_SLICE;
347 spin_lock(&vq->lock);
348 if (!list_empty(&vq->list)) {
349 event = list_first_entry(&vq->list, struct vtimer_list, entry);
350 next = event->expires;
353 spin_unlock(&vq->lock);
355 * To improve precision add the time spent by the
356 * interrupt handler to the elapsed time.
357 * Note: CPU timer counts down and we got an interrupt,
358 * the current content is negative
360 elapsed = S390_lowcore.async_enter_timer - get_vtimer();
361 set_vtimer(next - elapsed);
362 vq->timer = next - elapsed;
363 vq->elapsed = elapsed;
366 void init_virt_timer(struct vtimer_list *timer)
368 timer->function = NULL;
369 INIT_LIST_HEAD(&timer->entry);
371 EXPORT_SYMBOL(init_virt_timer);
373 static inline int vtimer_pending(struct vtimer_list *timer)
375 return (!list_empty(&timer->entry));
379 * this function should only run on the specified CPU
381 static void internal_add_vtimer(struct vtimer_list *timer)
383 struct vtimer_queue *vq;
387 vq = &per_cpu(virt_cpu_timer, timer->cpu);
388 spin_lock_irqsave(&vq->lock, flags);
390 BUG_ON(timer->cpu != smp_processor_id());
392 if (list_empty(&vq->list)) {
393 /* First timer on this cpu, just program it. */
394 list_add(&timer->entry, &vq->list);
395 set_vtimer(timer->expires);
396 vq->timer = timer->expires;
399 /* Check progress of old timers. */
400 expires = timer->expires;
402 if (likely((s64) expires < (s64) left)) {
403 /* The new timer expires before the current timer. */
405 vq->elapsed += vq->timer - left;
408 vq->elapsed += vq->timer - left;
411 /* Insert new timer into per cpu list. */
412 timer->expires += vq->elapsed;
413 list_add_sorted(timer, &vq->list);
416 spin_unlock_irqrestore(&vq->lock, flags);
417 /* release CPU acquired in prepare_vtimer or mod_virt_timer() */
421 static inline void prepare_vtimer(struct vtimer_list *timer)
423 BUG_ON(!timer->function);
424 BUG_ON(!timer->expires || timer->expires > VTIMER_MAX_SLICE);
425 BUG_ON(vtimer_pending(timer));
426 timer->cpu = get_cpu();
430 * add_virt_timer - add an oneshot virtual CPU timer
432 void add_virt_timer(void *new)
434 struct vtimer_list *timer;
436 timer = (struct vtimer_list *)new;
437 prepare_vtimer(timer);
439 internal_add_vtimer(timer);
441 EXPORT_SYMBOL(add_virt_timer);
444 * add_virt_timer_int - add an interval virtual CPU timer
446 void add_virt_timer_periodic(void *new)
448 struct vtimer_list *timer;
450 timer = (struct vtimer_list *)new;
451 prepare_vtimer(timer);
452 timer->interval = timer->expires;
453 internal_add_vtimer(timer);
455 EXPORT_SYMBOL(add_virt_timer_periodic);
457 int __mod_vtimer(struct vtimer_list *timer, __u64 expires, int periodic)
459 struct vtimer_queue *vq;
463 BUG_ON(!timer->function);
464 BUG_ON(!expires || expires > VTIMER_MAX_SLICE);
466 if (timer->expires == expires && vtimer_pending(timer))
470 vq = &per_cpu(virt_cpu_timer, cpu);
472 /* disable interrupts before test if timer is pending */
473 spin_lock_irqsave(&vq->lock, flags);
475 /* if timer isn't pending add it on the current CPU */
476 if (!vtimer_pending(timer)) {
477 spin_unlock_irqrestore(&vq->lock, flags);
480 timer->interval = expires;
483 timer->expires = expires;
485 internal_add_vtimer(timer);
489 /* check if we run on the right CPU */
490 BUG_ON(timer->cpu != cpu);
492 list_del_init(&timer->entry);
493 timer->expires = expires;
495 timer->interval = expires;
497 /* the timer can't expire anymore so we can release the lock */
498 spin_unlock_irqrestore(&vq->lock, flags);
499 internal_add_vtimer(timer);
504 * If we change a pending timer the function must be called on the CPU
505 * where the timer is running on.
507 * returns whether it has modified a pending timer (1) or not (0)
509 int mod_virt_timer(struct vtimer_list *timer, __u64 expires)
511 return __mod_vtimer(timer, expires, 0);
513 EXPORT_SYMBOL(mod_virt_timer);
516 * If we change a pending timer the function must be called on the CPU
517 * where the timer is running on.
519 * returns whether it has modified a pending timer (1) or not (0)
521 int mod_virt_timer_periodic(struct vtimer_list *timer, __u64 expires)
523 return __mod_vtimer(timer, expires, 1);
525 EXPORT_SYMBOL(mod_virt_timer_periodic);
528 * delete a virtual timer
530 * returns whether the deleted timer was pending (1) or not (0)
532 int del_virt_timer(struct vtimer_list *timer)
535 struct vtimer_queue *vq;
537 /* check if timer is pending */
538 if (!vtimer_pending(timer))
541 vq = &per_cpu(virt_cpu_timer, timer->cpu);
542 spin_lock_irqsave(&vq->lock, flags);
544 /* we don't interrupt a running timer, just let it expire! */
545 list_del_init(&timer->entry);
547 spin_unlock_irqrestore(&vq->lock, flags);
550 EXPORT_SYMBOL(del_virt_timer);
553 * Start the virtual CPU timer on the current CPU.
555 void init_cpu_vtimer(void)
557 struct vtimer_queue *vq;
559 /* initialize per cpu vtimer structure */
560 vq = &__get_cpu_var(virt_cpu_timer);
561 INIT_LIST_HEAD(&vq->list);
562 spin_lock_init(&vq->lock);
564 /* enable cpu timer interrupts */
568 void __init vtime_init(void)
570 /* request the cpu timer external interrupt */
571 if (register_external_interrupt(0x1005, do_cpu_timer_interrupt))
572 panic("Couldn't request external interrupt 0x1005");
574 /* Enable cpu timer interrupts on the boot cpu. */