1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Virtual cpu timer based timer functions.
4 *
5 * Copyright IBM Corp. 2004, 2012
6 * Author(s): Jan Glauber <jan.glauber@de.ibm.com>
7 */
8
9 #include <linux/kernel_stat.h>
10 #include <linux/sched/cputime.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
17 #include <asm/vtimer.h>
18 #include <asm/vtime.h>
19 #include <asm/cpu_mf.h>
20 #include <asm/smp.h>
21
22 #include "entry.h"
23
24 static void virt_timer_expire(void);
25
26 static LIST_HEAD(virt_timer_list);
27 static DEFINE_SPINLOCK(virt_timer_lock);
28 static atomic64_t virt_timer_current;
29 static atomic64_t virt_timer_elapsed;
30
31 DEFINE_PER_CPU(u64, mt_cycles[8]);
32 static DEFINE_PER_CPU(u64, mt_scaling_mult) = { 1 };
33 static DEFINE_PER_CPU(u64, mt_scaling_div) = { 1 };
34 static DEFINE_PER_CPU(u64, mt_scaling_jiffies);
35
get_vtimer(void)36 static inline u64 get_vtimer(void)
37 {
38 u64 timer;
39
40 asm volatile("stpt %0" : "=Q" (timer));
41 return timer;
42 }
43
set_vtimer(u64 expires)44 static inline void set_vtimer(u64 expires)
45 {
46 u64 timer;
47
48 asm volatile(
49 " stpt %0\n" /* Store current cpu timer value */
50 " spt %1" /* Set new value imm. afterwards */
51 : "=Q" (timer) : "Q" (expires));
52 S390_lowcore.system_timer += S390_lowcore.last_update_timer - timer;
53 S390_lowcore.last_update_timer = expires;
54 }
55
virt_timer_forward(u64 elapsed)56 static inline int virt_timer_forward(u64 elapsed)
57 {
58 BUG_ON(!irqs_disabled());
59
60 if (list_empty(&virt_timer_list))
61 return 0;
62 elapsed = atomic64_add_return(elapsed, &virt_timer_elapsed);
63 return elapsed >= atomic64_read(&virt_timer_current);
64 }
65
update_mt_scaling(void)66 static void update_mt_scaling(void)
67 {
68 u64 cycles_new[8], *cycles_old;
69 u64 delta, fac, mult, div;
70 int i;
71
72 stcctm(MT_DIAG, smp_cpu_mtid + 1, cycles_new);
73 cycles_old = this_cpu_ptr(mt_cycles);
74 fac = 1;
75 mult = div = 0;
76 for (i = 0; i <= smp_cpu_mtid; i++) {
77 delta = cycles_new[i] - cycles_old[i];
78 div += delta;
79 mult *= i + 1;
80 mult += delta * fac;
81 fac *= i + 1;
82 }
83 div *= fac;
84 if (div > 0) {
85 /* Update scaling factor */
86 __this_cpu_write(mt_scaling_mult, mult);
87 __this_cpu_write(mt_scaling_div, div);
88 memcpy(cycles_old, cycles_new,
89 sizeof(u64) * (smp_cpu_mtid + 1));
90 }
91 __this_cpu_write(mt_scaling_jiffies, jiffies_64);
92 }
93
update_tsk_timer(unsigned long * tsk_vtime,u64 new)94 static inline u64 update_tsk_timer(unsigned long *tsk_vtime, u64 new)
95 {
96 u64 delta;
97
98 delta = new - *tsk_vtime;
99 *tsk_vtime = new;
100 return delta;
101 }
102
103
scale_vtime(u64 vtime)104 static inline u64 scale_vtime(u64 vtime)
105 {
106 u64 mult = __this_cpu_read(mt_scaling_mult);
107 u64 div = __this_cpu_read(mt_scaling_div);
108
109 if (smp_cpu_mtid)
110 return vtime * mult / div;
111 return vtime;
112 }
113
account_system_index_scaled(struct task_struct * p,u64 cputime,enum cpu_usage_stat index)114 static void account_system_index_scaled(struct task_struct *p, u64 cputime,
115 enum cpu_usage_stat index)
116 {
117 p->stimescaled += cputime_to_nsecs(scale_vtime(cputime));
118 account_system_index_time(p, cputime_to_nsecs(cputime), index);
119 }
120
121 /*
122 * Update process times based on virtual cpu times stored by entry.S
123 * to the lowcore fields user_timer, system_timer & steal_clock.
124 */
do_account_vtime(struct task_struct * tsk)125 static int do_account_vtime(struct task_struct *tsk)
126 {
127 u64 timer, clock, user, guest, system, hardirq, softirq;
128
129 timer = S390_lowcore.last_update_timer;
130 clock = S390_lowcore.last_update_clock;
131 asm volatile(
132 " stpt %0\n" /* Store current cpu timer value */
133 #ifdef CONFIG_HAVE_MARCH_Z9_109_FEATURES
134 " stckf %1" /* Store current tod clock value */
135 #else
136 " stck %1" /* Store current tod clock value */
137 #endif
138 : "=Q" (S390_lowcore.last_update_timer),
139 "=Q" (S390_lowcore.last_update_clock)
140 : : "cc");
141 clock = S390_lowcore.last_update_clock - clock;
142 timer -= S390_lowcore.last_update_timer;
143
144 if (hardirq_count())
145 S390_lowcore.hardirq_timer += timer;
146 else
147 S390_lowcore.system_timer += timer;
148
149 /* Update MT utilization calculation */
150 if (smp_cpu_mtid &&
151 time_after64(jiffies_64, this_cpu_read(mt_scaling_jiffies)))
152 update_mt_scaling();
153
154 /* Calculate cputime delta */
155 user = update_tsk_timer(&tsk->thread.user_timer,
156 READ_ONCE(S390_lowcore.user_timer));
157 guest = update_tsk_timer(&tsk->thread.guest_timer,
158 READ_ONCE(S390_lowcore.guest_timer));
159 system = update_tsk_timer(&tsk->thread.system_timer,
160 READ_ONCE(S390_lowcore.system_timer));
161 hardirq = update_tsk_timer(&tsk->thread.hardirq_timer,
162 READ_ONCE(S390_lowcore.hardirq_timer));
163 softirq = update_tsk_timer(&tsk->thread.softirq_timer,
164 READ_ONCE(S390_lowcore.softirq_timer));
165 S390_lowcore.steal_timer +=
166 clock - user - guest - system - hardirq - softirq;
167
168 /* Push account value */
169 if (user) {
170 account_user_time(tsk, cputime_to_nsecs(user));
171 tsk->utimescaled += cputime_to_nsecs(scale_vtime(user));
172 }
173
174 if (guest) {
175 account_guest_time(tsk, cputime_to_nsecs(guest));
176 tsk->utimescaled += cputime_to_nsecs(scale_vtime(guest));
177 }
178
179 if (system)
180 account_system_index_scaled(tsk, system, CPUTIME_SYSTEM);
181 if (hardirq)
182 account_system_index_scaled(tsk, hardirq, CPUTIME_IRQ);
183 if (softirq)
184 account_system_index_scaled(tsk, softirq, CPUTIME_SOFTIRQ);
185
186 return virt_timer_forward(user + guest + system + hardirq + softirq);
187 }
188
vtime_task_switch(struct task_struct * prev)189 void vtime_task_switch(struct task_struct *prev)
190 {
191 do_account_vtime(prev);
192 prev->thread.user_timer = S390_lowcore.user_timer;
193 prev->thread.guest_timer = S390_lowcore.guest_timer;
194 prev->thread.system_timer = S390_lowcore.system_timer;
195 prev->thread.hardirq_timer = S390_lowcore.hardirq_timer;
196 prev->thread.softirq_timer = S390_lowcore.softirq_timer;
197 S390_lowcore.user_timer = current->thread.user_timer;
198 S390_lowcore.guest_timer = current->thread.guest_timer;
199 S390_lowcore.system_timer = current->thread.system_timer;
200 S390_lowcore.hardirq_timer = current->thread.hardirq_timer;
201 S390_lowcore.softirq_timer = current->thread.softirq_timer;
202 }
203
204 /*
205 * In s390, accounting pending user time also implies
206 * accounting system time in order to correctly compute
207 * the stolen time accounting.
208 */
vtime_flush(struct task_struct * tsk)209 void vtime_flush(struct task_struct *tsk)
210 {
211 u64 steal, avg_steal;
212
213 if (do_account_vtime(tsk))
214 virt_timer_expire();
215
216 steal = S390_lowcore.steal_timer;
217 avg_steal = S390_lowcore.avg_steal_timer / 2;
218 if ((s64) steal > 0) {
219 S390_lowcore.steal_timer = 0;
220 account_steal_time(cputime_to_nsecs(steal));
221 avg_steal += steal;
222 }
223 S390_lowcore.avg_steal_timer = avg_steal;
224 }
225
226 /*
227 * Update process times based on virtual cpu times stored by entry.S
228 * to the lowcore fields user_timer, system_timer & steal_clock.
229 */
vtime_account_irq_enter(struct task_struct * tsk)230 void vtime_account_irq_enter(struct task_struct *tsk)
231 {
232 u64 timer;
233
234 timer = S390_lowcore.last_update_timer;
235 S390_lowcore.last_update_timer = get_vtimer();
236 timer -= S390_lowcore.last_update_timer;
237
238 if ((tsk->flags & PF_VCPU) && (irq_count() == 0))
239 S390_lowcore.guest_timer += timer;
240 else if (hardirq_count())
241 S390_lowcore.hardirq_timer += timer;
242 else if (in_serving_softirq())
243 S390_lowcore.softirq_timer += timer;
244 else
245 S390_lowcore.system_timer += timer;
246
247 virt_timer_forward(timer);
248 }
249 EXPORT_SYMBOL_GPL(vtime_account_irq_enter);
250
251 void vtime_account_kernel(struct task_struct *tsk)
252 __attribute__((alias("vtime_account_irq_enter")));
253 EXPORT_SYMBOL_GPL(vtime_account_kernel);
254
255 /*
256 * Sorted add to a list. List is linear searched until first bigger
257 * element is found.
258 */
list_add_sorted(struct vtimer_list * timer,struct list_head * head)259 static void list_add_sorted(struct vtimer_list *timer, struct list_head *head)
260 {
261 struct vtimer_list *tmp;
262
263 list_for_each_entry(tmp, head, entry) {
264 if (tmp->expires > timer->expires) {
265 list_add_tail(&timer->entry, &tmp->entry);
266 return;
267 }
268 }
269 list_add_tail(&timer->entry, head);
270 }
271
272 /*
273 * Handler for expired virtual CPU timer.
274 */
virt_timer_expire(void)275 static void virt_timer_expire(void)
276 {
277 struct vtimer_list *timer, *tmp;
278 unsigned long elapsed;
279 LIST_HEAD(cb_list);
280
281 /* walk timer list, fire all expired timers */
282 spin_lock(&virt_timer_lock);
283 elapsed = atomic64_read(&virt_timer_elapsed);
284 list_for_each_entry_safe(timer, tmp, &virt_timer_list, entry) {
285 if (timer->expires < elapsed)
286 /* move expired timer to the callback queue */
287 list_move_tail(&timer->entry, &cb_list);
288 else
289 timer->expires -= elapsed;
290 }
291 if (!list_empty(&virt_timer_list)) {
292 timer = list_first_entry(&virt_timer_list,
293 struct vtimer_list, entry);
294 atomic64_set(&virt_timer_current, timer->expires);
295 }
296 atomic64_sub(elapsed, &virt_timer_elapsed);
297 spin_unlock(&virt_timer_lock);
298
299 /* Do callbacks and recharge periodic timers */
300 list_for_each_entry_safe(timer, tmp, &cb_list, entry) {
301 list_del_init(&timer->entry);
302 timer->function(timer->data);
303 if (timer->interval) {
304 /* Recharge interval timer */
305 timer->expires = timer->interval +
306 atomic64_read(&virt_timer_elapsed);
307 spin_lock(&virt_timer_lock);
308 list_add_sorted(timer, &virt_timer_list);
309 spin_unlock(&virt_timer_lock);
310 }
311 }
312 }
313
init_virt_timer(struct vtimer_list * timer)314 void init_virt_timer(struct vtimer_list *timer)
315 {
316 timer->function = NULL;
317 INIT_LIST_HEAD(&timer->entry);
318 }
319 EXPORT_SYMBOL(init_virt_timer);
320
vtimer_pending(struct vtimer_list * timer)321 static inline int vtimer_pending(struct vtimer_list *timer)
322 {
323 return !list_empty(&timer->entry);
324 }
325
internal_add_vtimer(struct vtimer_list * timer)326 static void internal_add_vtimer(struct vtimer_list *timer)
327 {
328 if (list_empty(&virt_timer_list)) {
329 /* First timer, just program it. */
330 atomic64_set(&virt_timer_current, timer->expires);
331 atomic64_set(&virt_timer_elapsed, 0);
332 list_add(&timer->entry, &virt_timer_list);
333 } else {
334 /* Update timer against current base. */
335 timer->expires += atomic64_read(&virt_timer_elapsed);
336 if (likely((s64) timer->expires <
337 (s64) atomic64_read(&virt_timer_current)))
338 /* The new timer expires before the current timer. */
339 atomic64_set(&virt_timer_current, timer->expires);
340 /* Insert new timer into the list. */
341 list_add_sorted(timer, &virt_timer_list);
342 }
343 }
344
__add_vtimer(struct vtimer_list * timer,int periodic)345 static void __add_vtimer(struct vtimer_list *timer, int periodic)
346 {
347 unsigned long flags;
348
349 timer->interval = periodic ? timer->expires : 0;
350 spin_lock_irqsave(&virt_timer_lock, flags);
351 internal_add_vtimer(timer);
352 spin_unlock_irqrestore(&virt_timer_lock, flags);
353 }
354
355 /*
356 * add_virt_timer - add a oneshot virtual CPU timer
357 */
add_virt_timer(struct vtimer_list * timer)358 void add_virt_timer(struct vtimer_list *timer)
359 {
360 __add_vtimer(timer, 0);
361 }
362 EXPORT_SYMBOL(add_virt_timer);
363
364 /*
365 * add_virt_timer_int - add an interval virtual CPU timer
366 */
add_virt_timer_periodic(struct vtimer_list * timer)367 void add_virt_timer_periodic(struct vtimer_list *timer)
368 {
369 __add_vtimer(timer, 1);
370 }
371 EXPORT_SYMBOL(add_virt_timer_periodic);
372
__mod_vtimer(struct vtimer_list * timer,u64 expires,int periodic)373 static int __mod_vtimer(struct vtimer_list *timer, u64 expires, int periodic)
374 {
375 unsigned long flags;
376 int rc;
377
378 BUG_ON(!timer->function);
379
380 if (timer->expires == expires && vtimer_pending(timer))
381 return 1;
382 spin_lock_irqsave(&virt_timer_lock, flags);
383 rc = vtimer_pending(timer);
384 if (rc)
385 list_del_init(&timer->entry);
386 timer->interval = periodic ? expires : 0;
387 timer->expires = expires;
388 internal_add_vtimer(timer);
389 spin_unlock_irqrestore(&virt_timer_lock, flags);
390 return rc;
391 }
392
393 /*
394 * returns whether it has modified a pending timer (1) or not (0)
395 */
mod_virt_timer(struct vtimer_list * timer,u64 expires)396 int mod_virt_timer(struct vtimer_list *timer, u64 expires)
397 {
398 return __mod_vtimer(timer, expires, 0);
399 }
400 EXPORT_SYMBOL(mod_virt_timer);
401
402 /*
403 * returns whether it has modified a pending timer (1) or not (0)
404 */
mod_virt_timer_periodic(struct vtimer_list * timer,u64 expires)405 int mod_virt_timer_periodic(struct vtimer_list *timer, u64 expires)
406 {
407 return __mod_vtimer(timer, expires, 1);
408 }
409 EXPORT_SYMBOL(mod_virt_timer_periodic);
410
411 /*
412 * Delete a virtual timer.
413 *
414 * returns whether the deleted timer was pending (1) or not (0)
415 */
del_virt_timer(struct vtimer_list * timer)416 int del_virt_timer(struct vtimer_list *timer)
417 {
418 unsigned long flags;
419
420 if (!vtimer_pending(timer))
421 return 0;
422 spin_lock_irqsave(&virt_timer_lock, flags);
423 list_del_init(&timer->entry);
424 spin_unlock_irqrestore(&virt_timer_lock, flags);
425 return 1;
426 }
427 EXPORT_SYMBOL(del_virt_timer);
428
429 /*
430 * Start the virtual CPU timer on the current CPU.
431 */
vtime_init(void)432 void vtime_init(void)
433 {
434 /* set initial cpu timer */
435 set_vtimer(VTIMER_MAX_SLICE);
436 /* Setup initial MT scaling values */
437 if (smp_cpu_mtid) {
438 __this_cpu_write(mt_scaling_jiffies, jiffies);
439 __this_cpu_write(mt_scaling_mult, 1);
440 __this_cpu_write(mt_scaling_div, 1);
441 stcctm(MT_DIAG, smp_cpu_mtid + 1, this_cpu_ptr(mt_cycles));
442 }
443 }
444