2 * Virtual cpu timer based timer functions.
4 * Copyright IBM Corp. 2004, 2012
5 * Author(s): Jan Glauber <jan.glauber@de.ibm.com>
8 #include <linux/kernel_stat.h>
9 #include <linux/notifier.h>
10 #include <linux/kprobes.h>
11 #include <linux/export.h>
12 #include <linux/kernel.h>
13 #include <linux/timex.h>
14 #include <linux/types.h>
15 #include <linux/time.h>
16 #include <linux/cpu.h>
17 #include <linux/smp.h>
19 #include <asm/irq_regs.h>
20 #include <asm/cputime.h>
21 #include <asm/vtimer.h>
25 static void virt_timer_expire(void);
27 DEFINE_PER_CPU(struct s390_idle_data, s390_idle);
29 static LIST_HEAD(virt_timer_list);
30 static DEFINE_SPINLOCK(virt_timer_lock);
31 static atomic64_t virt_timer_current;
32 static atomic64_t virt_timer_elapsed;
34 static inline u64 get_vtimer(void)
38 asm volatile("stpt %0" : "=m" (timer));
42 static inline void set_vtimer(u64 expires)
47 " stpt %0\n" /* Store current cpu timer value */
48 " spt %1" /* Set new value imm. afterwards */
49 : "=m" (timer) : "m" (expires));
50 S390_lowcore.system_timer += S390_lowcore.last_update_timer - timer;
51 S390_lowcore.last_update_timer = expires;
54 static inline int virt_timer_forward(u64 elapsed)
56 BUG_ON(!irqs_disabled());
58 if (list_empty(&virt_timer_list))
60 elapsed = atomic64_add_return(elapsed, &virt_timer_elapsed);
61 return elapsed >= atomic64_read(&virt_timer_current);
65 * Update process times based on virtual cpu times stored by entry.S
66 * to the lowcore fields user_timer, system_timer & steal_clock.
68 static int do_account_vtime(struct task_struct *tsk, int hardirq_offset)
70 struct thread_info *ti = task_thread_info(tsk);
71 u64 timer, clock, user, system, steal;
73 timer = S390_lowcore.last_update_timer;
74 clock = S390_lowcore.last_update_clock;
76 " stpt %0\n" /* Store current cpu timer value */
77 " stck %1" /* Store current tod clock value */
78 : "=m" (S390_lowcore.last_update_timer),
79 "=m" (S390_lowcore.last_update_clock));
80 S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
81 S390_lowcore.steal_timer += S390_lowcore.last_update_clock - clock;
83 user = S390_lowcore.user_timer - ti->user_timer;
84 S390_lowcore.steal_timer -= user;
85 ti->user_timer = S390_lowcore.user_timer;
86 account_user_time(tsk, user, user);
88 system = S390_lowcore.system_timer - ti->system_timer;
89 S390_lowcore.steal_timer -= system;
90 ti->system_timer = S390_lowcore.system_timer;
91 account_system_time(tsk, hardirq_offset, system, system);
93 steal = S390_lowcore.steal_timer;
94 if ((s64) steal > 0) {
95 S390_lowcore.steal_timer = 0;
96 account_steal_time(steal);
99 return virt_timer_forward(user + system);
102 void vtime_task_switch(struct task_struct *prev)
104 struct thread_info *ti;
106 do_account_vtime(prev, 0);
107 ti = task_thread_info(prev);
108 ti->user_timer = S390_lowcore.user_timer;
109 ti->system_timer = S390_lowcore.system_timer;
110 ti = task_thread_info(current);
111 S390_lowcore.user_timer = ti->user_timer;
112 S390_lowcore.system_timer = ti->system_timer;
115 void account_process_tick(struct task_struct *tsk, int user_tick)
117 if (do_account_vtime(tsk, HARDIRQ_OFFSET))
122 * Update process times based on virtual cpu times stored by entry.S
123 * to the lowcore fields user_timer, system_timer & steal_clock.
125 void vtime_account(struct task_struct *tsk)
127 struct thread_info *ti = task_thread_info(tsk);
130 timer = S390_lowcore.last_update_timer;
131 S390_lowcore.last_update_timer = get_vtimer();
132 S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
134 system = S390_lowcore.system_timer - ti->system_timer;
135 S390_lowcore.steal_timer -= system;
136 ti->system_timer = S390_lowcore.system_timer;
137 account_system_time(tsk, 0, system, system);
139 virt_timer_forward(system);
141 EXPORT_SYMBOL_GPL(vtime_account);
143 void __vtime_account_system(struct task_struct *tsk)
144 __attribute__((alias("vtime_account")));
145 EXPORT_SYMBOL_GPL(__vtime_account_system);
147 void __kprobes vtime_stop_cpu(void)
149 struct s390_idle_data *idle = &__get_cpu_var(s390_idle);
150 unsigned long long idle_time;
151 unsigned long psw_mask;
154 /* Don't trace preempt off for idle. */
155 stop_critical_timings();
157 /* Wait for external, I/O or machine check interrupt. */
158 psw_mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_DAT |
159 PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
160 idle->nohz_delay = 0;
162 /* Call the assembler magic in entry.S */
163 psw_idle(idle, psw_mask);
165 /* Reenable preemption tracer. */
166 start_critical_timings();
168 /* Account time spent with enabled wait psw loaded as idle time. */
171 idle_time = idle->clock_idle_exit - idle->clock_idle_enter;
172 idle->clock_idle_enter = idle->clock_idle_exit = 0ULL;
173 idle->idle_time += idle_time;
175 account_idle_time(idle_time);
180 cputime64_t s390_get_idle_time(int cpu)
182 struct s390_idle_data *idle = &per_cpu(s390_idle, cpu);
183 unsigned long long now, idle_enter, idle_exit;
184 unsigned int sequence;
188 sequence = ACCESS_ONCE(idle->sequence);
189 idle_enter = ACCESS_ONCE(idle->clock_idle_enter);
190 idle_exit = ACCESS_ONCE(idle->clock_idle_exit);
191 } while ((sequence & 1) || (idle->sequence != sequence));
192 return idle_enter ? ((idle_exit ?: now) - idle_enter) : 0;
196 * Sorted add to a list. List is linear searched until first bigger
199 static void list_add_sorted(struct vtimer_list *timer, struct list_head *head)
201 struct vtimer_list *tmp;
203 list_for_each_entry(tmp, head, entry) {
204 if (tmp->expires > timer->expires) {
205 list_add_tail(&timer->entry, &tmp->entry);
209 list_add_tail(&timer->entry, head);
213 * Handler for expired virtual CPU timer.
215 static void virt_timer_expire(void)
217 struct vtimer_list *timer, *tmp;
218 unsigned long elapsed;
221 /* walk timer list, fire all expired timers */
222 spin_lock(&virt_timer_lock);
223 elapsed = atomic64_read(&virt_timer_elapsed);
224 list_for_each_entry_safe(timer, tmp, &virt_timer_list, entry) {
225 if (timer->expires < elapsed)
226 /* move expired timer to the callback queue */
227 list_move_tail(&timer->entry, &cb_list);
229 timer->expires -= elapsed;
231 if (!list_empty(&virt_timer_list)) {
232 timer = list_first_entry(&virt_timer_list,
233 struct vtimer_list, entry);
234 atomic64_set(&virt_timer_current, timer->expires);
236 atomic64_sub(elapsed, &virt_timer_elapsed);
237 spin_unlock(&virt_timer_lock);
239 /* Do callbacks and recharge periodic timers */
240 list_for_each_entry_safe(timer, tmp, &cb_list, entry) {
241 list_del_init(&timer->entry);
242 timer->function(timer->data);
243 if (timer->interval) {
244 /* Recharge interval timer */
245 timer->expires = timer->interval +
246 atomic64_read(&virt_timer_elapsed);
247 spin_lock(&virt_timer_lock);
248 list_add_sorted(timer, &virt_timer_list);
249 spin_unlock(&virt_timer_lock);
254 void init_virt_timer(struct vtimer_list *timer)
256 timer->function = NULL;
257 INIT_LIST_HEAD(&timer->entry);
259 EXPORT_SYMBOL(init_virt_timer);
261 static inline int vtimer_pending(struct vtimer_list *timer)
263 return !list_empty(&timer->entry);
266 static void internal_add_vtimer(struct vtimer_list *timer)
268 if (list_empty(&virt_timer_list)) {
269 /* First timer, just program it. */
270 atomic64_set(&virt_timer_current, timer->expires);
271 atomic64_set(&virt_timer_elapsed, 0);
272 list_add(&timer->entry, &virt_timer_list);
274 /* Update timer against current base. */
275 timer->expires += atomic64_read(&virt_timer_elapsed);
276 if (likely((s64) timer->expires <
277 (s64) atomic64_read(&virt_timer_current)))
278 /* The new timer expires before the current timer. */
279 atomic64_set(&virt_timer_current, timer->expires);
280 /* Insert new timer into the list. */
281 list_add_sorted(timer, &virt_timer_list);
285 static void __add_vtimer(struct vtimer_list *timer, int periodic)
289 timer->interval = periodic ? timer->expires : 0;
290 spin_lock_irqsave(&virt_timer_lock, flags);
291 internal_add_vtimer(timer);
292 spin_unlock_irqrestore(&virt_timer_lock, flags);
296 * add_virt_timer - add an oneshot virtual CPU timer
298 void add_virt_timer(struct vtimer_list *timer)
300 __add_vtimer(timer, 0);
302 EXPORT_SYMBOL(add_virt_timer);
305 * add_virt_timer_int - add an interval virtual CPU timer
307 void add_virt_timer_periodic(struct vtimer_list *timer)
309 __add_vtimer(timer, 1);
311 EXPORT_SYMBOL(add_virt_timer_periodic);
313 static int __mod_vtimer(struct vtimer_list *timer, u64 expires, int periodic)
318 BUG_ON(!timer->function);
320 if (timer->expires == expires && vtimer_pending(timer))
322 spin_lock_irqsave(&virt_timer_lock, flags);
323 rc = vtimer_pending(timer);
325 list_del_init(&timer->entry);
326 timer->interval = periodic ? expires : 0;
327 timer->expires = expires;
328 internal_add_vtimer(timer);
329 spin_unlock_irqrestore(&virt_timer_lock, flags);
334 * returns whether it has modified a pending timer (1) or not (0)
336 int mod_virt_timer(struct vtimer_list *timer, u64 expires)
338 return __mod_vtimer(timer, expires, 0);
340 EXPORT_SYMBOL(mod_virt_timer);
343 * returns whether it has modified a pending timer (1) or not (0)
345 int mod_virt_timer_periodic(struct vtimer_list *timer, u64 expires)
347 return __mod_vtimer(timer, expires, 1);
349 EXPORT_SYMBOL(mod_virt_timer_periodic);
352 * Delete a virtual timer.
354 * returns whether the deleted timer was pending (1) or not (0)
356 int del_virt_timer(struct vtimer_list *timer)
360 if (!vtimer_pending(timer))
362 spin_lock_irqsave(&virt_timer_lock, flags);
363 list_del_init(&timer->entry);
364 spin_unlock_irqrestore(&virt_timer_lock, flags);
367 EXPORT_SYMBOL(del_virt_timer);
370 * Start the virtual CPU timer on the current CPU.
372 void __cpuinit init_cpu_vtimer(void)
374 /* set initial cpu timer */
375 set_vtimer(VTIMER_MAX_SLICE);
378 static int __cpuinit s390_nohz_notify(struct notifier_block *self,
379 unsigned long action, void *hcpu)
381 struct s390_idle_data *idle;
382 long cpu = (long) hcpu;
384 idle = &per_cpu(s390_idle, cpu);
385 switch (action & ~CPU_TASKS_FROZEN) {
387 idle->nohz_delay = 0;
394 void __init vtime_init(void)
396 /* Enable cpu timer interrupts on the boot cpu. */
398 cpu_notifier(s390_nohz_notify, 0);