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/export.h>
11 #include <linux/kernel.h>
12 #include <linux/timex.h>
13 #include <linux/types.h>
14 #include <linux/time.h>
15 #include <asm/alternative.h>
16 #include <asm/cputime.h>
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
36 static inline void set_vtimer(u64 expires)
37 {
38 struct lowcore *lc = get_lowcore();
39 u64 timer;
40
41 asm volatile(
42 " stpt %0\n" /* Store current cpu timer value */
43 " spt %1" /* Set new value imm. afterwards */
44 : "=Q" (timer) : "Q" (expires));
45 lc->system_timer += lc->last_update_timer - timer;
46 lc->last_update_timer = expires;
47 }
48
49 static inline int virt_timer_forward(u64 elapsed)
50 {
51 BUG_ON(!irqs_disabled());
52
53 if (list_empty(&virt_timer_list))
54 return 0;
55 elapsed = atomic64_add_return(elapsed, &virt_timer_elapsed);
56 return elapsed >= atomic64_read(&virt_timer_current);
57 }
58
59 static void update_mt_scaling(void)
60 {
61 u64 cycles_new[8], *cycles_old;
62 u64 delta, fac, mult, div;
63 int i;
64
65 stcctm(MT_DIAG, smp_cpu_mtid + 1, cycles_new);
66 cycles_old = this_cpu_ptr(mt_cycles);
67 fac = 1;
68 mult = div = 0;
69 for (i = 0; i <= smp_cpu_mtid; i++) {
70 delta = cycles_new[i] - cycles_old[i];
71 div += delta;
72 mult *= i + 1;
73 mult += delta * fac;
74 fac *= i + 1;
75 }
76 div *= fac;
77 if (div > 0) {
78 /* Update scaling factor */
79 __this_cpu_write(mt_scaling_mult, mult);
80 __this_cpu_write(mt_scaling_div, div);
81 memcpy(cycles_old, cycles_new,
82 sizeof(u64) * (smp_cpu_mtid + 1));
83 }
84 __this_cpu_write(mt_scaling_jiffies, jiffies_64);
85 }
86
87 static inline u64 update_tsk_timer(unsigned long *tsk_vtime, u64 new)
88 {
89 u64 delta;
90
91 delta = new - *tsk_vtime;
92 *tsk_vtime = new;
93 return delta;
94 }
95
96
97 static inline u64 scale_vtime(u64 vtime)
98 {
99 u64 mult = __this_cpu_read(mt_scaling_mult);
100 u64 div = __this_cpu_read(mt_scaling_div);
101
102 if (smp_cpu_mtid)
103 return vtime * mult / div;
104 return vtime;
105 }
106
107 static void account_system_index_scaled(struct task_struct *p, u64 cputime,
108 enum cpu_usage_stat index)
109 {
110 p->stimescaled += cputime_to_nsecs(scale_vtime(cputime));
111 account_system_index_time(p, cputime_to_nsecs(cputime), index);
112 }
113
114 /*
115 * Update process times based on virtual cpu times stored by entry.S
116 * to the lowcore fields user_timer, system_timer & steal_clock.
117 */
118 static int do_account_vtime(struct task_struct *tsk)
119 {
120 u64 timer, clock, user, guest, system, hardirq, softirq;
121 struct lowcore *lc = get_lowcore();
122
123 timer = lc->last_update_timer;
124 clock = lc->last_update_clock;
125 asm volatile(
126 " stpt %0\n" /* Store current cpu timer value */
127 " stckf %1" /* Store current tod clock value */
128 : "=Q" (lc->last_update_timer),
129 "=Q" (lc->last_update_clock)
130 : : "cc");
131 clock = lc->last_update_clock - clock;
132 timer -= lc->last_update_timer;
133
134 if (hardirq_count())
135 lc->hardirq_timer += timer;
136 else
137 lc->system_timer += timer;
138
139 /* Update MT utilization calculation */
140 if (smp_cpu_mtid &&
141 time_after64(jiffies_64, this_cpu_read(mt_scaling_jiffies)))
142 update_mt_scaling();
143
144 /* Calculate cputime delta */
145 user = update_tsk_timer(&tsk->thread.user_timer,
146 READ_ONCE(lc->user_timer));
147 guest = update_tsk_timer(&tsk->thread.guest_timer,
148 READ_ONCE(lc->guest_timer));
149 system = update_tsk_timer(&tsk->thread.system_timer,
150 READ_ONCE(lc->system_timer));
151 hardirq = update_tsk_timer(&tsk->thread.hardirq_timer,
152 READ_ONCE(lc->hardirq_timer));
153 softirq = update_tsk_timer(&tsk->thread.softirq_timer,
154 READ_ONCE(lc->softirq_timer));
155 lc->steal_timer +=
156 clock - user - guest - system - hardirq - softirq;
157
158 /* Push account value */
159 if (user) {
160 account_user_time(tsk, cputime_to_nsecs(user));
161 tsk->utimescaled += cputime_to_nsecs(scale_vtime(user));
162 }
163
164 if (guest) {
165 account_guest_time(tsk, cputime_to_nsecs(guest));
166 tsk->utimescaled += cputime_to_nsecs(scale_vtime(guest));
167 }
168
169 if (system)
170 account_system_index_scaled(tsk, system, CPUTIME_SYSTEM);
171 if (hardirq)
172 account_system_index_scaled(tsk, hardirq, CPUTIME_IRQ);
173 if (softirq)
174 account_system_index_scaled(tsk, softirq, CPUTIME_SOFTIRQ);
175
176 return virt_timer_forward(user + guest + system + hardirq + softirq);
177 }
178
179 void vtime_task_switch(struct task_struct *prev)
180 {
181 struct lowcore *lc = get_lowcore();
182
183 do_account_vtime(prev);
184 prev->thread.user_timer = lc->user_timer;
185 prev->thread.guest_timer = lc->guest_timer;
186 prev->thread.system_timer = lc->system_timer;
187 prev->thread.hardirq_timer = lc->hardirq_timer;
188 prev->thread.softirq_timer = lc->softirq_timer;
189 lc->user_timer = current->thread.user_timer;
190 lc->guest_timer = current->thread.guest_timer;
191 lc->system_timer = current->thread.system_timer;
192 lc->hardirq_timer = current->thread.hardirq_timer;
193 lc->softirq_timer = current->thread.softirq_timer;
194 }
195
196 /*
197 * In s390, accounting pending user time also implies
198 * accounting system time in order to correctly compute
199 * the stolen time accounting.
200 */
201 void vtime_flush(struct task_struct *tsk)
202 {
203 struct lowcore *lc = get_lowcore();
204 u64 steal, avg_steal;
205
206 if (do_account_vtime(tsk))
207 virt_timer_expire();
208
209 steal = lc->steal_timer;
210 avg_steal = lc->avg_steal_timer;
211 if ((s64) steal > 0) {
212 lc->steal_timer = 0;
213 account_steal_time(cputime_to_nsecs(steal));
214 avg_steal += steal;
215 }
216 lc->avg_steal_timer = avg_steal / 2;
217 }
218
219 static u64 vtime_delta(void)
220 {
221 struct lowcore *lc = get_lowcore();
222 u64 timer = lc->last_update_timer;
223
224 lc->last_update_timer = get_cpu_timer();
225 return timer - lc->last_update_timer;
226 }
227
228 /*
229 * Update process times based on virtual cpu times stored by entry.S
230 * to the lowcore fields user_timer, system_timer & steal_clock.
231 */
232 void vtime_account_kernel(struct task_struct *tsk)
233 {
234 struct lowcore *lc = get_lowcore();
235 u64 delta = vtime_delta();
236
237 if (tsk->flags & PF_VCPU)
238 lc->guest_timer += delta;
239 else
240 lc->system_timer += delta;
241
242 virt_timer_forward(delta);
243 }
244 EXPORT_SYMBOL_GPL(vtime_account_kernel);
245
246 void vtime_account_softirq(struct task_struct *tsk)
247 {
248 u64 delta = vtime_delta();
249
250 get_lowcore()->softirq_timer += delta;
251
252 virt_timer_forward(delta);
253 }
254
255 void vtime_account_hardirq(struct task_struct *tsk)
256 {
257 u64 delta = vtime_delta();
258
259 get_lowcore()->hardirq_timer += delta;
260
261 virt_timer_forward(delta);
262 }
263
264 /*
265 * Sorted add to a list. List is linear searched until first bigger
266 * element is found.
267 */
268 static void list_add_sorted(struct vtimer_list *timer, struct list_head *head)
269 {
270 struct vtimer_list *tmp;
271
272 list_for_each_entry(tmp, head, entry) {
273 if (tmp->expires > timer->expires) {
274 list_add_tail(&timer->entry, &tmp->entry);
275 return;
276 }
277 }
278 list_add_tail(&timer->entry, head);
279 }
280
281 /*
282 * Handler for expired virtual CPU timer.
283 */
284 static void virt_timer_expire(void)
285 {
286 struct vtimer_list *timer, *tmp;
287 unsigned long elapsed;
288 LIST_HEAD(cb_list);
289
290 /* walk timer list, fire all expired timers */
291 spin_lock(&virt_timer_lock);
292 elapsed = atomic64_read(&virt_timer_elapsed);
293 list_for_each_entry_safe(timer, tmp, &virt_timer_list, entry) {
294 if (timer->expires < elapsed)
295 /* move expired timer to the callback queue */
296 list_move_tail(&timer->entry, &cb_list);
297 else
298 timer->expires -= elapsed;
299 }
300 if (!list_empty(&virt_timer_list)) {
301 timer = list_first_entry(&virt_timer_list,
302 struct vtimer_list, entry);
303 atomic64_set(&virt_timer_current, timer->expires);
304 }
305 atomic64_sub(elapsed, &virt_timer_elapsed);
306 spin_unlock(&virt_timer_lock);
307
308 /* Do callbacks and recharge periodic timers */
309 list_for_each_entry_safe(timer, tmp, &cb_list, entry) {
310 list_del_init(&timer->entry);
311 timer->function(timer->data);
312 if (timer->interval) {
313 /* Recharge interval timer */
314 timer->expires = timer->interval +
315 atomic64_read(&virt_timer_elapsed);
316 spin_lock(&virt_timer_lock);
317 list_add_sorted(timer, &virt_timer_list);
318 spin_unlock(&virt_timer_lock);
319 }
320 }
321 }
322
323 void init_virt_timer(struct vtimer_list *timer)
324 {
325 timer->function = NULL;
326 INIT_LIST_HEAD(&timer->entry);
327 }
328 EXPORT_SYMBOL(init_virt_timer);
329
330 static inline int vtimer_pending(struct vtimer_list *timer)
331 {
332 return !list_empty(&timer->entry);
333 }
334
335 static void internal_add_vtimer(struct vtimer_list *timer)
336 {
337 if (list_empty(&virt_timer_list)) {
338 /* First timer, just program it. */
339 atomic64_set(&virt_timer_current, timer->expires);
340 atomic64_set(&virt_timer_elapsed, 0);
341 list_add(&timer->entry, &virt_timer_list);
342 } else {
343 /* Update timer against current base. */
344 timer->expires += atomic64_read(&virt_timer_elapsed);
345 if (likely((s64) timer->expires <
346 (s64) atomic64_read(&virt_timer_current)))
347 /* The new timer expires before the current timer. */
348 atomic64_set(&virt_timer_current, timer->expires);
349 /* Insert new timer into the list. */
350 list_add_sorted(timer, &virt_timer_list);
351 }
352 }
353
354 static void __add_vtimer(struct vtimer_list *timer, int periodic)
355 {
356 unsigned long flags;
357
358 timer->interval = periodic ? timer->expires : 0;
359 spin_lock_irqsave(&virt_timer_lock, flags);
360 internal_add_vtimer(timer);
361 spin_unlock_irqrestore(&virt_timer_lock, flags);
362 }
363
364 /*
365 * add_virt_timer - add a oneshot virtual CPU timer
366 */
367 void add_virt_timer(struct vtimer_list *timer)
368 {
369 __add_vtimer(timer, 0);
370 }
371 EXPORT_SYMBOL(add_virt_timer);
372
373 /*
374 * add_virt_timer_int - add an interval virtual CPU timer
375 */
376 void add_virt_timer_periodic(struct vtimer_list *timer)
377 {
378 __add_vtimer(timer, 1);
379 }
380 EXPORT_SYMBOL(add_virt_timer_periodic);
381
382 static int __mod_vtimer(struct vtimer_list *timer, u64 expires, int periodic)
383 {
384 unsigned long flags;
385 int rc;
386
387 BUG_ON(!timer->function);
388
389 if (timer->expires == expires && vtimer_pending(timer))
390 return 1;
391 spin_lock_irqsave(&virt_timer_lock, flags);
392 rc = vtimer_pending(timer);
393 if (rc)
394 list_del_init(&timer->entry);
395 timer->interval = periodic ? expires : 0;
396 timer->expires = expires;
397 internal_add_vtimer(timer);
398 spin_unlock_irqrestore(&virt_timer_lock, flags);
399 return rc;
400 }
401
402 /*
403 * returns whether it has modified a pending timer (1) or not (0)
404 */
405 int mod_virt_timer(struct vtimer_list *timer, u64 expires)
406 {
407 return __mod_vtimer(timer, expires, 0);
408 }
409 EXPORT_SYMBOL(mod_virt_timer);
410
411 /*
412 * returns whether it has modified a pending timer (1) or not (0)
413 */
414 int mod_virt_timer_periodic(struct vtimer_list *timer, u64 expires)
415 {
416 return __mod_vtimer(timer, expires, 1);
417 }
418 EXPORT_SYMBOL(mod_virt_timer_periodic);
419
420 /*
421 * Delete a virtual timer.
422 *
423 * returns whether the deleted timer was pending (1) or not (0)
424 */
425 int del_virt_timer(struct vtimer_list *timer)
426 {
427 unsigned long flags;
428
429 if (!vtimer_pending(timer))
430 return 0;
431 spin_lock_irqsave(&virt_timer_lock, flags);
432 list_del_init(&timer->entry);
433 spin_unlock_irqrestore(&virt_timer_lock, flags);
434 return 1;
435 }
436 EXPORT_SYMBOL(del_virt_timer);
437
438 /*
439 * Start the virtual CPU timer on the current CPU.
440 */
441 void vtime_init(void)
442 {
443 /* set initial cpu timer */
444 set_vtimer(VTIMER_MAX_SLICE);
445 /* Setup initial MT scaling values */
446 if (smp_cpu_mtid) {
447 __this_cpu_write(mt_scaling_jiffies, jiffies);
448 __this_cpu_write(mt_scaling_mult, 1);
449 __this_cpu_write(mt_scaling_div, 1);
450 stcctm(MT_DIAG, smp_cpu_mtid + 1, this_cpu_ptr(mt_cycles));
451 }
452 }
453
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