1 /*
2 * Virtual cpu timer based timer functions.
3 *
4 * Copyright IBM Corp. 2004, 2012
5 * Author(s): Jan Glauber <jan.glauber@de.ibm.com>
6 */
7
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>
14
15 #include <asm/cputime.h>
16 #include <asm/vtimer.h>
17 #include <asm/vtime.h>
18 #include <asm/cpu_mf.h>
19 #include <asm/smp.h>
20
21 static void virt_timer_expire(void);
22
23 static LIST_HEAD(virt_timer_list);
24 static DEFINE_SPINLOCK(virt_timer_lock);
25 static atomic64_t virt_timer_current;
26 static atomic64_t virt_timer_elapsed;
27
28 DEFINE_PER_CPU(u64, mt_cycles[8]);
29 static DEFINE_PER_CPU(u64, mt_scaling_mult) = { 1 };
30 static DEFINE_PER_CPU(u64, mt_scaling_div) = { 1 };
31 static DEFINE_PER_CPU(u64, mt_scaling_jiffies);
32
get_vtimer(void)33 static inline u64 get_vtimer(void)
34 {
35 u64 timer;
36
37 asm volatile("stpt %0" : "=m" (timer));
38 return timer;
39 }
40
set_vtimer(u64 expires)41 static inline void set_vtimer(u64 expires)
42 {
43 u64 timer;
44
45 asm volatile(
46 " stpt %0\n" /* Store current cpu timer value */
47 " spt %1" /* Set new value imm. afterwards */
48 : "=m" (timer) : "m" (expires));
49 S390_lowcore.system_timer += S390_lowcore.last_update_timer - timer;
50 S390_lowcore.last_update_timer = expires;
51 }
52
virt_timer_forward(u64 elapsed)53 static inline int virt_timer_forward(u64 elapsed)
54 {
55 BUG_ON(!irqs_disabled());
56
57 if (list_empty(&virt_timer_list))
58 return 0;
59 elapsed = atomic64_add_return(elapsed, &virt_timer_elapsed);
60 return elapsed >= atomic64_read(&virt_timer_current);
61 }
62
update_mt_scaling(void)63 static void update_mt_scaling(void)
64 {
65 u64 cycles_new[8], *cycles_old;
66 u64 delta, fac, mult, div;
67 int i;
68
69 stcctm5(smp_cpu_mtid + 1, cycles_new);
70 cycles_old = this_cpu_ptr(mt_cycles);
71 fac = 1;
72 mult = div = 0;
73 for (i = 0; i <= smp_cpu_mtid; i++) {
74 delta = cycles_new[i] - cycles_old[i];
75 div += delta;
76 mult *= i + 1;
77 mult += delta * fac;
78 fac *= i + 1;
79 }
80 div *= fac;
81 if (div > 0) {
82 /* Update scaling factor */
83 __this_cpu_write(mt_scaling_mult, mult);
84 __this_cpu_write(mt_scaling_div, div);
85 memcpy(cycles_old, cycles_new,
86 sizeof(u64) * (smp_cpu_mtid + 1));
87 }
88 __this_cpu_write(mt_scaling_jiffies, jiffies_64);
89 }
90
91 /*
92 * Update process times based on virtual cpu times stored by entry.S
93 * to the lowcore fields user_timer, system_timer & steal_clock.
94 */
do_account_vtime(struct task_struct * tsk,int hardirq_offset)95 static int do_account_vtime(struct task_struct *tsk, int hardirq_offset)
96 {
97 struct thread_info *ti = task_thread_info(tsk);
98 u64 timer, clock, user, system, steal;
99 u64 user_scaled, system_scaled;
100
101 timer = S390_lowcore.last_update_timer;
102 clock = S390_lowcore.last_update_clock;
103 asm volatile(
104 " stpt %0\n" /* Store current cpu timer value */
105 #ifdef CONFIG_HAVE_MARCH_Z9_109_FEATURES
106 " stckf %1" /* Store current tod clock value */
107 #else
108 " stck %1" /* Store current tod clock value */
109 #endif
110 : "=m" (S390_lowcore.last_update_timer),
111 "=m" (S390_lowcore.last_update_clock));
112 S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
113 S390_lowcore.steal_timer += S390_lowcore.last_update_clock - clock;
114
115 /* Update MT utilization calculation */
116 if (smp_cpu_mtid &&
117 time_after64(jiffies_64, this_cpu_read(mt_scaling_jiffies)))
118 update_mt_scaling();
119
120 user = S390_lowcore.user_timer - ti->user_timer;
121 S390_lowcore.steal_timer -= user;
122 ti->user_timer = S390_lowcore.user_timer;
123
124 system = S390_lowcore.system_timer - ti->system_timer;
125 S390_lowcore.steal_timer -= system;
126 ti->system_timer = S390_lowcore.system_timer;
127
128 user_scaled = user;
129 system_scaled = system;
130 /* Do MT utilization scaling */
131 if (smp_cpu_mtid) {
132 u64 mult = __this_cpu_read(mt_scaling_mult);
133 u64 div = __this_cpu_read(mt_scaling_div);
134
135 user_scaled = (user_scaled * mult) / div;
136 system_scaled = (system_scaled * mult) / div;
137 }
138 account_user_time(tsk, user, user_scaled);
139 account_system_time(tsk, hardirq_offset, system, system_scaled);
140
141 steal = S390_lowcore.steal_timer;
142 if ((s64) steal > 0) {
143 S390_lowcore.steal_timer = 0;
144 account_steal_time(steal);
145 }
146
147 return virt_timer_forward(user + system);
148 }
149
vtime_task_switch(struct task_struct * prev)150 void vtime_task_switch(struct task_struct *prev)
151 {
152 struct thread_info *ti;
153
154 do_account_vtime(prev, 0);
155 ti = task_thread_info(prev);
156 ti->user_timer = S390_lowcore.user_timer;
157 ti->system_timer = S390_lowcore.system_timer;
158 ti = task_thread_info(current);
159 S390_lowcore.user_timer = ti->user_timer;
160 S390_lowcore.system_timer = ti->system_timer;
161 }
162
163 /*
164 * In s390, accounting pending user time also implies
165 * accounting system time in order to correctly compute
166 * the stolen time accounting.
167 */
vtime_account_user(struct task_struct * tsk)168 void vtime_account_user(struct task_struct *tsk)
169 {
170 if (do_account_vtime(tsk, HARDIRQ_OFFSET))
171 virt_timer_expire();
172 }
173
174 /*
175 * Update process times based on virtual cpu times stored by entry.S
176 * to the lowcore fields user_timer, system_timer & steal_clock.
177 */
vtime_account_irq_enter(struct task_struct * tsk)178 void vtime_account_irq_enter(struct task_struct *tsk)
179 {
180 struct thread_info *ti = task_thread_info(tsk);
181 u64 timer, system, system_scaled;
182
183 timer = S390_lowcore.last_update_timer;
184 S390_lowcore.last_update_timer = get_vtimer();
185 S390_lowcore.system_timer += timer - S390_lowcore.last_update_timer;
186
187 /* Update MT utilization calculation */
188 if (smp_cpu_mtid &&
189 time_after64(jiffies_64, this_cpu_read(mt_scaling_jiffies)))
190 update_mt_scaling();
191
192 system = S390_lowcore.system_timer - ti->system_timer;
193 S390_lowcore.steal_timer -= system;
194 ti->system_timer = S390_lowcore.system_timer;
195 system_scaled = system;
196 /* Do MT utilization scaling */
197 if (smp_cpu_mtid) {
198 u64 mult = __this_cpu_read(mt_scaling_mult);
199 u64 div = __this_cpu_read(mt_scaling_div);
200
201 system_scaled = (system_scaled * mult) / div;
202 }
203 account_system_time(tsk, 0, system, system_scaled);
204
205 virt_timer_forward(system);
206 }
207 EXPORT_SYMBOL_GPL(vtime_account_irq_enter);
208
209 void vtime_account_system(struct task_struct *tsk)
210 __attribute__((alias("vtime_account_irq_enter")));
211 EXPORT_SYMBOL_GPL(vtime_account_system);
212
213 /*
214 * Sorted add to a list. List is linear searched until first bigger
215 * element is found.
216 */
list_add_sorted(struct vtimer_list * timer,struct list_head * head)217 static void list_add_sorted(struct vtimer_list *timer, struct list_head *head)
218 {
219 struct vtimer_list *tmp;
220
221 list_for_each_entry(tmp, head, entry) {
222 if (tmp->expires > timer->expires) {
223 list_add_tail(&timer->entry, &tmp->entry);
224 return;
225 }
226 }
227 list_add_tail(&timer->entry, head);
228 }
229
230 /*
231 * Handler for expired virtual CPU timer.
232 */
virt_timer_expire(void)233 static void virt_timer_expire(void)
234 {
235 struct vtimer_list *timer, *tmp;
236 unsigned long elapsed;
237 LIST_HEAD(cb_list);
238
239 /* walk timer list, fire all expired timers */
240 spin_lock(&virt_timer_lock);
241 elapsed = atomic64_read(&virt_timer_elapsed);
242 list_for_each_entry_safe(timer, tmp, &virt_timer_list, entry) {
243 if (timer->expires < elapsed)
244 /* move expired timer to the callback queue */
245 list_move_tail(&timer->entry, &cb_list);
246 else
247 timer->expires -= elapsed;
248 }
249 if (!list_empty(&virt_timer_list)) {
250 timer = list_first_entry(&virt_timer_list,
251 struct vtimer_list, entry);
252 atomic64_set(&virt_timer_current, timer->expires);
253 }
254 atomic64_sub(elapsed, &virt_timer_elapsed);
255 spin_unlock(&virt_timer_lock);
256
257 /* Do callbacks and recharge periodic timers */
258 list_for_each_entry_safe(timer, tmp, &cb_list, entry) {
259 list_del_init(&timer->entry);
260 timer->function(timer->data);
261 if (timer->interval) {
262 /* Recharge interval timer */
263 timer->expires = timer->interval +
264 atomic64_read(&virt_timer_elapsed);
265 spin_lock(&virt_timer_lock);
266 list_add_sorted(timer, &virt_timer_list);
267 spin_unlock(&virt_timer_lock);
268 }
269 }
270 }
271
init_virt_timer(struct vtimer_list * timer)272 void init_virt_timer(struct vtimer_list *timer)
273 {
274 timer->function = NULL;
275 INIT_LIST_HEAD(&timer->entry);
276 }
277 EXPORT_SYMBOL(init_virt_timer);
278
vtimer_pending(struct vtimer_list * timer)279 static inline int vtimer_pending(struct vtimer_list *timer)
280 {
281 return !list_empty(&timer->entry);
282 }
283
internal_add_vtimer(struct vtimer_list * timer)284 static void internal_add_vtimer(struct vtimer_list *timer)
285 {
286 if (list_empty(&virt_timer_list)) {
287 /* First timer, just program it. */
288 atomic64_set(&virt_timer_current, timer->expires);
289 atomic64_set(&virt_timer_elapsed, 0);
290 list_add(&timer->entry, &virt_timer_list);
291 } else {
292 /* Update timer against current base. */
293 timer->expires += atomic64_read(&virt_timer_elapsed);
294 if (likely((s64) timer->expires <
295 (s64) atomic64_read(&virt_timer_current)))
296 /* The new timer expires before the current timer. */
297 atomic64_set(&virt_timer_current, timer->expires);
298 /* Insert new timer into the list. */
299 list_add_sorted(timer, &virt_timer_list);
300 }
301 }
302
__add_vtimer(struct vtimer_list * timer,int periodic)303 static void __add_vtimer(struct vtimer_list *timer, int periodic)
304 {
305 unsigned long flags;
306
307 timer->interval = periodic ? timer->expires : 0;
308 spin_lock_irqsave(&virt_timer_lock, flags);
309 internal_add_vtimer(timer);
310 spin_unlock_irqrestore(&virt_timer_lock, flags);
311 }
312
313 /*
314 * add_virt_timer - add an oneshot virtual CPU timer
315 */
add_virt_timer(struct vtimer_list * timer)316 void add_virt_timer(struct vtimer_list *timer)
317 {
318 __add_vtimer(timer, 0);
319 }
320 EXPORT_SYMBOL(add_virt_timer);
321
322 /*
323 * add_virt_timer_int - add an interval virtual CPU timer
324 */
add_virt_timer_periodic(struct vtimer_list * timer)325 void add_virt_timer_periodic(struct vtimer_list *timer)
326 {
327 __add_vtimer(timer, 1);
328 }
329 EXPORT_SYMBOL(add_virt_timer_periodic);
330
__mod_vtimer(struct vtimer_list * timer,u64 expires,int periodic)331 static int __mod_vtimer(struct vtimer_list *timer, u64 expires, int periodic)
332 {
333 unsigned long flags;
334 int rc;
335
336 BUG_ON(!timer->function);
337
338 if (timer->expires == expires && vtimer_pending(timer))
339 return 1;
340 spin_lock_irqsave(&virt_timer_lock, flags);
341 rc = vtimer_pending(timer);
342 if (rc)
343 list_del_init(&timer->entry);
344 timer->interval = periodic ? expires : 0;
345 timer->expires = expires;
346 internal_add_vtimer(timer);
347 spin_unlock_irqrestore(&virt_timer_lock, flags);
348 return rc;
349 }
350
351 /*
352 * returns whether it has modified a pending timer (1) or not (0)
353 */
mod_virt_timer(struct vtimer_list * timer,u64 expires)354 int mod_virt_timer(struct vtimer_list *timer, u64 expires)
355 {
356 return __mod_vtimer(timer, expires, 0);
357 }
358 EXPORT_SYMBOL(mod_virt_timer);
359
360 /*
361 * returns whether it has modified a pending timer (1) or not (0)
362 */
mod_virt_timer_periodic(struct vtimer_list * timer,u64 expires)363 int mod_virt_timer_periodic(struct vtimer_list *timer, u64 expires)
364 {
365 return __mod_vtimer(timer, expires, 1);
366 }
367 EXPORT_SYMBOL(mod_virt_timer_periodic);
368
369 /*
370 * Delete a virtual timer.
371 *
372 * returns whether the deleted timer was pending (1) or not (0)
373 */
del_virt_timer(struct vtimer_list * timer)374 int del_virt_timer(struct vtimer_list *timer)
375 {
376 unsigned long flags;
377
378 if (!vtimer_pending(timer))
379 return 0;
380 spin_lock_irqsave(&virt_timer_lock, flags);
381 list_del_init(&timer->entry);
382 spin_unlock_irqrestore(&virt_timer_lock, flags);
383 return 1;
384 }
385 EXPORT_SYMBOL(del_virt_timer);
386
387 /*
388 * Start the virtual CPU timer on the current CPU.
389 */
vtime_init(void)390 void vtime_init(void)
391 {
392 /* set initial cpu timer */
393 set_vtimer(VTIMER_MAX_SLICE);
394 /* Setup initial MT scaling values */
395 if (smp_cpu_mtid) {
396 __this_cpu_write(mt_scaling_jiffies, jiffies);
397 __this_cpu_write(mt_scaling_mult, 1);
398 __this_cpu_write(mt_scaling_div, 1);
399 stcctm5(smp_cpu_mtid + 1, this_cpu_ptr(mt_cycles));
400 }
401 }
402