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/export.h>
10 #include <linux/kernel.h>
11 #include <linux/timex.h>
12 #include <linux/types.h>
13 #include <linux/time.h>
15 #include <asm/cputime.h>
16 #include <asm/vtimer.h>
17 #include <asm/vtime.h>
19 static void virt_timer_expire(void);
21 static LIST_HEAD(virt_timer_list);
22 static DEFINE_SPINLOCK(virt_timer_lock);
23 static atomic64_t virt_timer_current;
24 static atomic64_t virt_timer_elapsed;
26 static inline u64 get_vtimer(void)
30 asm volatile("stpt %0" : "=m" (timer));
34 static inline void set_vtimer(u64 expires)
39 " stpt %0\n" /* Store current cpu timer value */
40 " spt %1" /* Set new value imm. afterwards */
41 : "=m" (timer) : "m" (expires));
42 S390_lowcore.system_timer += S390_lowcore.last_update_timer - timer;
43 S390_lowcore.last_update_timer = expires;
46 static inline int virt_timer_forward(u64 elapsed)
48 BUG_ON(!irqs_disabled());
50 if (list_empty(&virt_timer_list))
52 elapsed = atomic64_add_return(elapsed, &virt_timer_elapsed);
53 return elapsed >= atomic64_read(&virt_timer_current);
57 * Update process times based on virtual cpu times stored by entry.S
58 * to the lowcore fields user_timer, system_timer & steal_clock.
60 static int do_account_vtime(struct task_struct *tsk, int hardirq_offset)
62 struct thread_info *ti = task_thread_info(tsk);
63 u64 timer, clock, user, system, steal;
65 timer = S390_lowcore.last_update_timer;
66 clock = S390_lowcore.last_update_clock;
68 " stpt %0\n" /* Store current cpu timer value */
69 #ifdef CONFIG_HAVE_MARCH_Z9_109_FEATURES
70 " stckf %1" /* Store current tod clock value */
72 " stck %1" /* Store current tod clock value */
74 : "=m" (S390_lowcore.last_update_timer),
75 "=m" (S390_lowcore.last_update_clock));
76 S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
77 S390_lowcore.steal_timer += S390_lowcore.last_update_clock - clock;
79 user = S390_lowcore.user_timer - ti->user_timer;
80 S390_lowcore.steal_timer -= user;
81 ti->user_timer = S390_lowcore.user_timer;
82 account_user_time(tsk, user, user);
84 system = S390_lowcore.system_timer - ti->system_timer;
85 S390_lowcore.steal_timer -= system;
86 ti->system_timer = S390_lowcore.system_timer;
87 account_system_time(tsk, hardirq_offset, system, system);
89 steal = S390_lowcore.steal_timer;
90 if ((s64) steal > 0) {
91 S390_lowcore.steal_timer = 0;
92 account_steal_time(steal);
95 return virt_timer_forward(user + system);
98 void vtime_task_switch(struct task_struct *prev)
100 struct thread_info *ti;
102 do_account_vtime(prev, 0);
103 ti = task_thread_info(prev);
104 ti->user_timer = S390_lowcore.user_timer;
105 ti->system_timer = S390_lowcore.system_timer;
106 ti = task_thread_info(current);
107 S390_lowcore.user_timer = ti->user_timer;
108 S390_lowcore.system_timer = ti->system_timer;
112 * In s390, accounting pending user time also implies
113 * accounting system time in order to correctly compute
114 * the stolen time accounting.
116 void vtime_account_user(struct task_struct *tsk)
118 if (do_account_vtime(tsk, HARDIRQ_OFFSET))
123 * Update process times based on virtual cpu times stored by entry.S
124 * to the lowcore fields user_timer, system_timer & steal_clock.
126 void vtime_account_irq_enter(struct task_struct *tsk)
128 struct thread_info *ti = task_thread_info(tsk);
131 timer = S390_lowcore.last_update_timer;
132 S390_lowcore.last_update_timer = get_vtimer();
133 S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
135 system = S390_lowcore.system_timer - ti->system_timer;
136 S390_lowcore.steal_timer -= system;
137 ti->system_timer = S390_lowcore.system_timer;
138 account_system_time(tsk, 0, system, system);
140 virt_timer_forward(system);
142 EXPORT_SYMBOL_GPL(vtime_account_irq_enter);
144 void vtime_account_system(struct task_struct *tsk)
145 __attribute__((alias("vtime_account_irq_enter")));
146 EXPORT_SYMBOL_GPL(vtime_account_system);
149 * Sorted add to a list. List is linear searched until first bigger
152 static void list_add_sorted(struct vtimer_list *timer, struct list_head *head)
154 struct vtimer_list *tmp;
156 list_for_each_entry(tmp, head, entry) {
157 if (tmp->expires > timer->expires) {
158 list_add_tail(&timer->entry, &tmp->entry);
162 list_add_tail(&timer->entry, head);
166 * Handler for expired virtual CPU timer.
168 static void virt_timer_expire(void)
170 struct vtimer_list *timer, *tmp;
171 unsigned long elapsed;
174 /* walk timer list, fire all expired timers */
175 spin_lock(&virt_timer_lock);
176 elapsed = atomic64_read(&virt_timer_elapsed);
177 list_for_each_entry_safe(timer, tmp, &virt_timer_list, entry) {
178 if (timer->expires < elapsed)
179 /* move expired timer to the callback queue */
180 list_move_tail(&timer->entry, &cb_list);
182 timer->expires -= elapsed;
184 if (!list_empty(&virt_timer_list)) {
185 timer = list_first_entry(&virt_timer_list,
186 struct vtimer_list, entry);
187 atomic64_set(&virt_timer_current, timer->expires);
189 atomic64_sub(elapsed, &virt_timer_elapsed);
190 spin_unlock(&virt_timer_lock);
192 /* Do callbacks and recharge periodic timers */
193 list_for_each_entry_safe(timer, tmp, &cb_list, entry) {
194 list_del_init(&timer->entry);
195 timer->function(timer->data);
196 if (timer->interval) {
197 /* Recharge interval timer */
198 timer->expires = timer->interval +
199 atomic64_read(&virt_timer_elapsed);
200 spin_lock(&virt_timer_lock);
201 list_add_sorted(timer, &virt_timer_list);
202 spin_unlock(&virt_timer_lock);
207 void init_virt_timer(struct vtimer_list *timer)
209 timer->function = NULL;
210 INIT_LIST_HEAD(&timer->entry);
212 EXPORT_SYMBOL(init_virt_timer);
214 static inline int vtimer_pending(struct vtimer_list *timer)
216 return !list_empty(&timer->entry);
219 static void internal_add_vtimer(struct vtimer_list *timer)
221 if (list_empty(&virt_timer_list)) {
222 /* First timer, just program it. */
223 atomic64_set(&virt_timer_current, timer->expires);
224 atomic64_set(&virt_timer_elapsed, 0);
225 list_add(&timer->entry, &virt_timer_list);
227 /* Update timer against current base. */
228 timer->expires += atomic64_read(&virt_timer_elapsed);
229 if (likely((s64) timer->expires <
230 (s64) atomic64_read(&virt_timer_current)))
231 /* The new timer expires before the current timer. */
232 atomic64_set(&virt_timer_current, timer->expires);
233 /* Insert new timer into the list. */
234 list_add_sorted(timer, &virt_timer_list);
238 static void __add_vtimer(struct vtimer_list *timer, int periodic)
242 timer->interval = periodic ? timer->expires : 0;
243 spin_lock_irqsave(&virt_timer_lock, flags);
244 internal_add_vtimer(timer);
245 spin_unlock_irqrestore(&virt_timer_lock, flags);
249 * add_virt_timer - add an oneshot virtual CPU timer
251 void add_virt_timer(struct vtimer_list *timer)
253 __add_vtimer(timer, 0);
255 EXPORT_SYMBOL(add_virt_timer);
258 * add_virt_timer_int - add an interval virtual CPU timer
260 void add_virt_timer_periodic(struct vtimer_list *timer)
262 __add_vtimer(timer, 1);
264 EXPORT_SYMBOL(add_virt_timer_periodic);
266 static int __mod_vtimer(struct vtimer_list *timer, u64 expires, int periodic)
271 BUG_ON(!timer->function);
273 if (timer->expires == expires && vtimer_pending(timer))
275 spin_lock_irqsave(&virt_timer_lock, flags);
276 rc = vtimer_pending(timer);
278 list_del_init(&timer->entry);
279 timer->interval = periodic ? expires : 0;
280 timer->expires = expires;
281 internal_add_vtimer(timer);
282 spin_unlock_irqrestore(&virt_timer_lock, flags);
287 * returns whether it has modified a pending timer (1) or not (0)
289 int mod_virt_timer(struct vtimer_list *timer, u64 expires)
291 return __mod_vtimer(timer, expires, 0);
293 EXPORT_SYMBOL(mod_virt_timer);
296 * returns whether it has modified a pending timer (1) or not (0)
298 int mod_virt_timer_periodic(struct vtimer_list *timer, u64 expires)
300 return __mod_vtimer(timer, expires, 1);
302 EXPORT_SYMBOL(mod_virt_timer_periodic);
305 * Delete a virtual timer.
307 * returns whether the deleted timer was pending (1) or not (0)
309 int del_virt_timer(struct vtimer_list *timer)
313 if (!vtimer_pending(timer))
315 spin_lock_irqsave(&virt_timer_lock, flags);
316 list_del_init(&timer->entry);
317 spin_unlock_irqrestore(&virt_timer_lock, flags);
320 EXPORT_SYMBOL(del_virt_timer);
323 * Start the virtual CPU timer on the current CPU.
325 void vtime_init(void)
327 /* set initial cpu timer */
328 set_vtimer(VTIMER_MAX_SLICE);