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>
22 #include <linux/cpu.h>
23 #include <linux/kprobes.h>
25 #include <asm/timer.h>
26 #include <asm/irq_regs.h>
27 #include <asm/cputime.h>
31 static DEFINE_PER_CPU(struct vtimer_queue, virt_cpu_timer);
33 DEFINE_PER_CPU(struct s390_idle_data, s390_idle);
35 static inline __u64 get_vtimer(void)
39 asm volatile("STPT %0" : "=m" (timer));
43 static inline void set_vtimer(__u64 expires)
47 asm volatile (" STPT %0\n" /* Store current cpu timer value */
48 " SPT %1" /* Set new value immediately afterwards */
49 : "=m" (timer) : "m" (expires) );
50 S390_lowcore.system_timer += S390_lowcore.last_update_timer - timer;
51 S390_lowcore.last_update_timer = expires;
55 * Update process times based on virtual cpu times stored by entry.S
56 * to the lowcore fields user_timer, system_timer & steal_clock.
58 static void do_account_vtime(struct task_struct *tsk, int hardirq_offset)
60 struct thread_info *ti = task_thread_info(tsk);
61 __u64 timer, clock, user, system, steal;
63 timer = S390_lowcore.last_update_timer;
64 clock = S390_lowcore.last_update_clock;
65 asm volatile (" STPT %0\n" /* Store current cpu timer value */
66 " STCK %1" /* Store current tod clock value */
67 : "=m" (S390_lowcore.last_update_timer),
68 "=m" (S390_lowcore.last_update_clock) );
69 S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
70 S390_lowcore.steal_timer += S390_lowcore.last_update_clock - clock;
72 user = S390_lowcore.user_timer - ti->user_timer;
73 S390_lowcore.steal_timer -= user;
74 ti->user_timer = S390_lowcore.user_timer;
75 account_user_time(tsk, user, user);
77 system = S390_lowcore.system_timer - ti->system_timer;
78 S390_lowcore.steal_timer -= system;
79 ti->system_timer = S390_lowcore.system_timer;
80 account_system_time(tsk, hardirq_offset, system, system);
82 steal = S390_lowcore.steal_timer;
83 if ((s64) steal > 0) {
84 S390_lowcore.steal_timer = 0;
85 account_steal_time(steal);
89 void account_vtime(struct task_struct *prev, struct task_struct *next)
91 struct thread_info *ti;
93 do_account_vtime(prev, 0);
94 ti = task_thread_info(prev);
95 ti->user_timer = S390_lowcore.user_timer;
96 ti->system_timer = S390_lowcore.system_timer;
97 ti = task_thread_info(next);
98 S390_lowcore.user_timer = ti->user_timer;
99 S390_lowcore.system_timer = ti->system_timer;
102 void account_process_tick(struct task_struct *tsk, int user_tick)
104 do_account_vtime(tsk, HARDIRQ_OFFSET);
108 * Update process times based on virtual cpu times stored by entry.S
109 * to the lowcore fields user_timer, system_timer & steal_clock.
111 void account_system_vtime(struct task_struct *tsk)
113 struct thread_info *ti = task_thread_info(tsk);
116 timer = S390_lowcore.last_update_timer;
117 S390_lowcore.last_update_timer = get_vtimer();
118 S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
120 system = S390_lowcore.system_timer - ti->system_timer;
121 S390_lowcore.steal_timer -= system;
122 ti->system_timer = S390_lowcore.system_timer;
123 account_system_time(tsk, 0, system, system);
125 EXPORT_SYMBOL_GPL(account_system_vtime);
127 void __kprobes vtime_stop_cpu(void)
129 struct s390_idle_data *idle = &__get_cpu_var(s390_idle);
130 struct vtimer_queue *vq = &__get_cpu_var(virt_cpu_timer);
131 unsigned long long idle_time;
132 unsigned long psw_mask;
135 /* Don't trace preempt off for idle. */
136 stop_critical_timings();
138 /* Wait for external, I/O or machine check interrupt. */
139 psw_mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_DAT |
140 PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
141 idle->nohz_delay = 0;
143 /* Call the assembler magic in entry.S */
144 psw_idle(idle, vq, psw_mask, !list_empty(&vq->list));
146 /* Reenable preemption tracer. */
147 start_critical_timings();
149 /* Account time spent with enabled wait psw loaded as idle time. */
152 idle_time = idle->idle_exit - idle->idle_enter;
153 idle->idle_time += idle_time;
154 idle->idle_enter = idle->idle_exit = 0ULL;
156 account_idle_time(idle_time);
161 cputime64_t s390_get_idle_time(int cpu)
163 struct s390_idle_data *idle = &per_cpu(s390_idle, cpu);
164 unsigned long long now, idle_enter, idle_exit;
165 unsigned int sequence;
169 sequence = ACCESS_ONCE(idle->sequence);
170 idle_enter = ACCESS_ONCE(idle->idle_enter);
171 idle_exit = ACCESS_ONCE(idle->idle_exit);
172 } while ((sequence & 1) || (idle->sequence != sequence));
173 return idle_enter ? ((idle_exit ? : now) - idle_enter) : 0;
177 * Sorted add to a list. List is linear searched until first bigger
180 static void list_add_sorted(struct vtimer_list *timer, struct list_head *head)
182 struct vtimer_list *event;
184 list_for_each_entry(event, head, entry) {
185 if (event->expires > timer->expires) {
186 list_add_tail(&timer->entry, &event->entry);
190 list_add_tail(&timer->entry, head);
194 * Do the callback functions of expired vtimer events.
195 * Called from within the interrupt handler.
197 static void do_callbacks(struct list_head *cb_list)
199 struct vtimer_queue *vq;
200 struct vtimer_list *event, *tmp;
202 if (list_empty(cb_list))
205 vq = &__get_cpu_var(virt_cpu_timer);
207 list_for_each_entry_safe(event, tmp, cb_list, entry) {
208 list_del_init(&event->entry);
209 (event->function)(event->data);
210 if (event->interval) {
211 /* Recharge interval timer */
212 event->expires = event->interval + vq->elapsed;
213 spin_lock(&vq->lock);
214 list_add_sorted(event, &vq->list);
215 spin_unlock(&vq->lock);
221 * Handler for the virtual CPU timer.
223 static void do_cpu_timer_interrupt(struct ext_code ext_code,
224 unsigned int param32, unsigned long param64)
226 struct vtimer_queue *vq;
227 struct vtimer_list *event, *tmp;
228 struct list_head cb_list; /* the callback queue */
231 kstat_cpu(smp_processor_id()).irqs[EXTINT_TMR]++;
232 INIT_LIST_HEAD(&cb_list);
233 vq = &__get_cpu_var(virt_cpu_timer);
235 /* walk timer list, fire all expired events */
236 spin_lock(&vq->lock);
238 elapsed = vq->elapsed + (vq->timer - S390_lowcore.async_enter_timer);
239 BUG_ON((s64) elapsed < 0);
241 list_for_each_entry_safe(event, tmp, &vq->list, entry) {
242 if (event->expires < elapsed)
243 /* move expired timer to the callback queue */
244 list_move_tail(&event->entry, &cb_list);
246 event->expires -= elapsed;
248 spin_unlock(&vq->lock);
250 do_callbacks(&cb_list);
252 /* next event is first in list */
253 next = VTIMER_MAX_SLICE;
254 spin_lock(&vq->lock);
255 if (!list_empty(&vq->list)) {
256 event = list_first_entry(&vq->list, struct vtimer_list, entry);
257 next = event->expires;
259 spin_unlock(&vq->lock);
261 * To improve precision add the time spent by the
262 * interrupt handler to the elapsed time.
263 * Note: CPU timer counts down and we got an interrupt,
264 * the current content is negative
266 elapsed = S390_lowcore.async_enter_timer - get_vtimer();
267 set_vtimer(next - elapsed);
268 vq->timer = next - elapsed;
269 vq->elapsed = elapsed;
272 void init_virt_timer(struct vtimer_list *timer)
274 timer->function = NULL;
275 INIT_LIST_HEAD(&timer->entry);
277 EXPORT_SYMBOL(init_virt_timer);
279 static inline int vtimer_pending(struct vtimer_list *timer)
281 return (!list_empty(&timer->entry));
285 * this function should only run on the specified CPU
287 static void internal_add_vtimer(struct vtimer_list *timer)
289 struct vtimer_queue *vq;
293 vq = &per_cpu(virt_cpu_timer, timer->cpu);
294 spin_lock_irqsave(&vq->lock, flags);
296 BUG_ON(timer->cpu != smp_processor_id());
298 if (list_empty(&vq->list)) {
299 /* First timer on this cpu, just program it. */
300 list_add(&timer->entry, &vq->list);
301 set_vtimer(timer->expires);
302 vq->timer = timer->expires;
305 /* Check progress of old timers. */
306 expires = timer->expires;
308 if (likely((s64) expires < (s64) left)) {
309 /* The new timer expires before the current timer. */
311 vq->elapsed += vq->timer - left;
314 vq->elapsed += vq->timer - left;
317 /* Insert new timer into per cpu list. */
318 timer->expires += vq->elapsed;
319 list_add_sorted(timer, &vq->list);
322 spin_unlock_irqrestore(&vq->lock, flags);
323 /* release CPU acquired in prepare_vtimer or mod_virt_timer() */
327 static inline void prepare_vtimer(struct vtimer_list *timer)
329 BUG_ON(!timer->function);
330 BUG_ON(!timer->expires || timer->expires > VTIMER_MAX_SLICE);
331 BUG_ON(vtimer_pending(timer));
332 timer->cpu = get_cpu();
336 * add_virt_timer - add an oneshot virtual CPU timer
338 void add_virt_timer(void *new)
340 struct vtimer_list *timer;
342 timer = (struct vtimer_list *)new;
343 prepare_vtimer(timer);
345 internal_add_vtimer(timer);
347 EXPORT_SYMBOL(add_virt_timer);
350 * add_virt_timer_int - add an interval virtual CPU timer
352 void add_virt_timer_periodic(void *new)
354 struct vtimer_list *timer;
356 timer = (struct vtimer_list *)new;
357 prepare_vtimer(timer);
358 timer->interval = timer->expires;
359 internal_add_vtimer(timer);
361 EXPORT_SYMBOL(add_virt_timer_periodic);
363 static int __mod_vtimer(struct vtimer_list *timer, __u64 expires, int periodic)
365 struct vtimer_queue *vq;
369 BUG_ON(!timer->function);
370 BUG_ON(!expires || expires > VTIMER_MAX_SLICE);
372 if (timer->expires == expires && vtimer_pending(timer))
376 vq = &per_cpu(virt_cpu_timer, cpu);
378 /* disable interrupts before test if timer is pending */
379 spin_lock_irqsave(&vq->lock, flags);
381 /* if timer isn't pending add it on the current CPU */
382 if (!vtimer_pending(timer)) {
383 spin_unlock_irqrestore(&vq->lock, flags);
386 timer->interval = expires;
389 timer->expires = expires;
391 internal_add_vtimer(timer);
395 /* check if we run on the right CPU */
396 BUG_ON(timer->cpu != cpu);
398 list_del_init(&timer->entry);
399 timer->expires = expires;
401 timer->interval = expires;
403 /* the timer can't expire anymore so we can release the lock */
404 spin_unlock_irqrestore(&vq->lock, flags);
405 internal_add_vtimer(timer);
410 * If we change a pending timer the function must be called on the CPU
411 * where the timer is running on.
413 * returns whether it has modified a pending timer (1) or not (0)
415 int mod_virt_timer(struct vtimer_list *timer, __u64 expires)
417 return __mod_vtimer(timer, expires, 0);
419 EXPORT_SYMBOL(mod_virt_timer);
422 * If we change a pending timer the function must be called on the CPU
423 * where the timer is running on.
425 * returns whether it has modified a pending timer (1) or not (0)
427 int mod_virt_timer_periodic(struct vtimer_list *timer, __u64 expires)
429 return __mod_vtimer(timer, expires, 1);
431 EXPORT_SYMBOL(mod_virt_timer_periodic);
434 * delete a virtual timer
436 * returns whether the deleted timer was pending (1) or not (0)
438 int del_virt_timer(struct vtimer_list *timer)
441 struct vtimer_queue *vq;
443 /* check if timer is pending */
444 if (!vtimer_pending(timer))
447 vq = &per_cpu(virt_cpu_timer, timer->cpu);
448 spin_lock_irqsave(&vq->lock, flags);
450 /* we don't interrupt a running timer, just let it expire! */
451 list_del_init(&timer->entry);
453 spin_unlock_irqrestore(&vq->lock, flags);
456 EXPORT_SYMBOL(del_virt_timer);
459 * Start the virtual CPU timer on the current CPU.
461 void init_cpu_vtimer(void)
463 struct vtimer_queue *vq;
465 /* initialize per cpu vtimer structure */
466 vq = &__get_cpu_var(virt_cpu_timer);
467 INIT_LIST_HEAD(&vq->list);
468 spin_lock_init(&vq->lock);
470 /* enable cpu timer interrupts */
473 /* set initial cpu timer */
474 set_vtimer(0x7fffffffffffffffULL);
477 static int __cpuinit s390_nohz_notify(struct notifier_block *self,
478 unsigned long action, void *hcpu)
480 struct s390_idle_data *idle;
481 long cpu = (long) hcpu;
483 idle = &per_cpu(s390_idle, cpu);
486 case CPU_DYING_FROZEN:
487 idle->nohz_delay = 0;
494 void __init vtime_init(void)
496 /* request the cpu timer external interrupt */
497 if (register_external_interrupt(0x1005, do_cpu_timer_interrupt))
498 panic("Couldn't request external interrupt 0x1005");
500 /* Enable cpu timer interrupts on the boot cpu. */
502 cpu_notifier(s390_nohz_notify, 0);