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1#include <linux/export.h>
2#include <linux/sched.h>
3#include <linux/tsacct_kern.h>
4#include <linux/kernel_stat.h>
5#include <linux/static_key.h>
6#include <linux/context_tracking.h>
7#include "sched.h"
8
9
10#ifdef CONFIG_IRQ_TIME_ACCOUNTING
11
12/*
13 * There are no locks covering percpu hardirq/softirq time.
14 * They are only modified in vtime_account, on corresponding CPU
15 * with interrupts disabled. So, writes are safe.
16 * They are read and saved off onto struct rq in update_rq_clock().
17 * This may result in other CPU reading this CPU's irq time and can
18 * race with irq/vtime_account on this CPU. We would either get old
19 * or new value with a side effect of accounting a slice of irq time to wrong
20 * task when irq is in progress while we read rq->clock. That is a worthy
21 * compromise in place of having locks on each irq in account_system_time.
22 */
23DEFINE_PER_CPU(u64, cpu_hardirq_time);
24DEFINE_PER_CPU(u64, cpu_softirq_time);
25
26static DEFINE_PER_CPU(u64, irq_start_time);
27static int sched_clock_irqtime;
28
29void enable_sched_clock_irqtime(void)
30{
31 sched_clock_irqtime = 1;
32}
33
34void disable_sched_clock_irqtime(void)
35{
36 sched_clock_irqtime = 0;
37}
38
39#ifndef CONFIG_64BIT
40DEFINE_PER_CPU(seqcount_t, irq_time_seq);
41#endif /* CONFIG_64BIT */
42
43/*
44 * Called before incrementing preempt_count on {soft,}irq_enter
45 * and before decrementing preempt_count on {soft,}irq_exit.
46 */
47void irqtime_account_irq(struct task_struct *curr)
48{
49 unsigned long flags;
50 s64 delta;
51 int cpu;
52
53 if (!sched_clock_irqtime)
54 return;
55
56 local_irq_save(flags);
57
58 cpu = smp_processor_id();
59 delta = sched_clock_cpu(cpu) - __this_cpu_read(irq_start_time);
60 __this_cpu_add(irq_start_time, delta);
61
62 irq_time_write_begin();
63 /*
64 * We do not account for softirq time from ksoftirqd here.
65 * We want to continue accounting softirq time to ksoftirqd thread
66 * in that case, so as not to confuse scheduler with a special task
67 * that do not consume any time, but still wants to run.
68 */
69 if (hardirq_count())
70 __this_cpu_add(cpu_hardirq_time, delta);
71 else if (in_serving_softirq() && curr != this_cpu_ksoftirqd())
72 __this_cpu_add(cpu_softirq_time, delta);
73
74 irq_time_write_end();
75 local_irq_restore(flags);
76}
77EXPORT_SYMBOL_GPL(irqtime_account_irq);
78
79static int irqtime_account_hi_update(void)
80{
81 u64 *cpustat = kcpustat_this_cpu->cpustat;
82 unsigned long flags;
83 u64 latest_ns;
84 int ret = 0;
85
86 local_irq_save(flags);
87 latest_ns = this_cpu_read(cpu_hardirq_time);
88 if (nsecs_to_cputime64(latest_ns) > cpustat[CPUTIME_IRQ])
89 ret = 1;
90 local_irq_restore(flags);
91 return ret;
92}
93
94static int irqtime_account_si_update(void)
95{
96 u64 *cpustat = kcpustat_this_cpu->cpustat;
97 unsigned long flags;
98 u64 latest_ns;
99 int ret = 0;
100
101 local_irq_save(flags);
102 latest_ns = this_cpu_read(cpu_softirq_time);
103 if (nsecs_to_cputime64(latest_ns) > cpustat[CPUTIME_SOFTIRQ])
104 ret = 1;
105 local_irq_restore(flags);
106 return ret;
107}
108
109#else /* CONFIG_IRQ_TIME_ACCOUNTING */
110
111#define sched_clock_irqtime (0)
112
113#endif /* !CONFIG_IRQ_TIME_ACCOUNTING */
114
115static inline void task_group_account_field(struct task_struct *p, int index,
116 u64 tmp)
117{
118 /*
119 * Since all updates are sure to touch the root cgroup, we
120 * get ourselves ahead and touch it first. If the root cgroup
121 * is the only cgroup, then nothing else should be necessary.
122 *
123 */
124 __this_cpu_add(kernel_cpustat.cpustat[index], tmp);
125
126 cpuacct_account_field(p, index, tmp);
127}
128
129/*
130 * Account user cpu time to a process.
131 * @p: the process that the cpu time gets accounted to
132 * @cputime: the cpu time spent in user space since the last update
133 * @cputime_scaled: cputime scaled by cpu frequency
134 */
135void account_user_time(struct task_struct *p, cputime_t cputime,
136 cputime_t cputime_scaled)
137{
138 int index;
139
140 /* Add user time to process. */
141 p->utime += cputime;
142 p->utimescaled += cputime_scaled;
143 account_group_user_time(p, cputime);
144
145 index = (task_nice(p) > 0) ? CPUTIME_NICE : CPUTIME_USER;
146
147 /* Add user time to cpustat. */
148 task_group_account_field(p, index, (__force u64) cputime);
149
150 /* Account for user time used */
151 acct_account_cputime(p);
152}
153
154/*
155 * Account guest cpu time to a process.
156 * @p: the process that the cpu time gets accounted to
157 * @cputime: the cpu time spent in virtual machine since the last update
158 * @cputime_scaled: cputime scaled by cpu frequency
159 */
160static void account_guest_time(struct task_struct *p, cputime_t cputime,
161 cputime_t cputime_scaled)
162{
163 u64 *cpustat = kcpustat_this_cpu->cpustat;
164
165 /* Add guest time to process. */
166 p->utime += cputime;
167 p->utimescaled += cputime_scaled;
168 account_group_user_time(p, cputime);
169 p->gtime += cputime;
170
171 /* Add guest time to cpustat. */
172 if (task_nice(p) > 0) {
173 cpustat[CPUTIME_NICE] += (__force u64) cputime;
174 cpustat[CPUTIME_GUEST_NICE] += (__force u64) cputime;
175 } else {
176 cpustat[CPUTIME_USER] += (__force u64) cputime;
177 cpustat[CPUTIME_GUEST] += (__force u64) cputime;
178 }
179}
180
181/*
182 * Account system cpu time to a process and desired cpustat field
183 * @p: the process that the cpu time gets accounted to
184 * @cputime: the cpu time spent in kernel space since the last update
185 * @cputime_scaled: cputime scaled by cpu frequency
186 * @target_cputime64: pointer to cpustat field that has to be updated
187 */
188static inline
189void __account_system_time(struct task_struct *p, cputime_t cputime,
190 cputime_t cputime_scaled, int index)
191{
192 /* Add system time to process. */
193 p->stime += cputime;
194 p->stimescaled += cputime_scaled;
195 account_group_system_time(p, cputime);
196
197 /* Add system time to cpustat. */
198 task_group_account_field(p, index, (__force u64) cputime);
199
200 /* Account for system time used */
201 acct_account_cputime(p);
202}
203
204/*
205 * Account system cpu time to a process.
206 * @p: the process that the cpu time gets accounted to
207 * @hardirq_offset: the offset to subtract from hardirq_count()
208 * @cputime: the cpu time spent in kernel space since the last update
209 * @cputime_scaled: cputime scaled by cpu frequency
210 */
211void account_system_time(struct task_struct *p, int hardirq_offset,
212 cputime_t cputime, cputime_t cputime_scaled)
213{
214 int index;
215
216 if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) {
217 account_guest_time(p, cputime, cputime_scaled);
218 return;
219 }
220
221 if (hardirq_count() - hardirq_offset)
222 index = CPUTIME_IRQ;
223 else if (in_serving_softirq())
224 index = CPUTIME_SOFTIRQ;
225 else
226 index = CPUTIME_SYSTEM;
227
228 __account_system_time(p, cputime, cputime_scaled, index);
229}
230
231/*
232 * Account for involuntary wait time.
233 * @cputime: the cpu time spent in involuntary wait
234 */
235void account_steal_time(cputime_t cputime)
236{
237 u64 *cpustat = kcpustat_this_cpu->cpustat;
238
239 cpustat[CPUTIME_STEAL] += (__force u64) cputime;
240}
241
242/*
243 * Account for idle time.
244 * @cputime: the cpu time spent in idle wait
245 */
246void account_idle_time(cputime_t cputime)
247{
248 u64 *cpustat = kcpustat_this_cpu->cpustat;
249 struct rq *rq = this_rq();
250
251 if (atomic_read(&rq->nr_iowait) > 0)
252 cpustat[CPUTIME_IOWAIT] += (__force u64) cputime;
253 else
254 cpustat[CPUTIME_IDLE] += (__force u64) cputime;
255}
256
257static __always_inline bool steal_account_process_tick(void)
258{
259#ifdef CONFIG_PARAVIRT
260 if (static_key_false(¶virt_steal_enabled)) {
261 u64 steal;
262 cputime_t steal_ct;
263
264 steal = paravirt_steal_clock(smp_processor_id());
265 steal -= this_rq()->prev_steal_time;
266
267 /*
268 * cputime_t may be less precise than nsecs (eg: if it's
269 * based on jiffies). Lets cast the result to cputime
270 * granularity and account the rest on the next rounds.
271 */
272 steal_ct = nsecs_to_cputime(steal);
273 this_rq()->prev_steal_time += cputime_to_nsecs(steal_ct);
274
275 account_steal_time(steal_ct);
276 return steal_ct;
277 }
278#endif
279 return false;
280}
281
282/*
283 * Accumulate raw cputime values of dead tasks (sig->[us]time) and live
284 * tasks (sum on group iteration) belonging to @tsk's group.
285 */
286void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
287{
288 struct signal_struct *sig = tsk->signal;
289 cputime_t utime, stime;
290 struct task_struct *t;
291
292 times->utime = sig->utime;
293 times->stime = sig->stime;
294 times->sum_exec_runtime = sig->sum_sched_runtime;
295
296 rcu_read_lock();
297 /* make sure we can trust tsk->thread_group list */
298 if (!likely(pid_alive(tsk)))
299 goto out;
300
301 t = tsk;
302 do {
303 task_cputime(t, &utime, &stime);
304 times->utime += utime;
305 times->stime += stime;
306 times->sum_exec_runtime += task_sched_runtime(t);
307 } while_each_thread(tsk, t);
308out:
309 rcu_read_unlock();
310}
311
312#ifdef CONFIG_IRQ_TIME_ACCOUNTING
313/*
314 * Account a tick to a process and cpustat
315 * @p: the process that the cpu time gets accounted to
316 * @user_tick: is the tick from userspace
317 * @rq: the pointer to rq
318 *
319 * Tick demultiplexing follows the order
320 * - pending hardirq update
321 * - pending softirq update
322 * - user_time
323 * - idle_time
324 * - system time
325 * - check for guest_time
326 * - else account as system_time
327 *
328 * Check for hardirq is done both for system and user time as there is
329 * no timer going off while we are on hardirq and hence we may never get an
330 * opportunity to update it solely in system time.
331 * p->stime and friends are only updated on system time and not on irq
332 * softirq as those do not count in task exec_runtime any more.
333 */
334static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
335 struct rq *rq, int ticks)
336{
337 cputime_t scaled = cputime_to_scaled(cputime_one_jiffy);
338 u64 cputime = (__force u64) cputime_one_jiffy;
339 u64 *cpustat = kcpustat_this_cpu->cpustat;
340
341 if (steal_account_process_tick())
342 return;
343
344 cputime *= ticks;
345 scaled *= ticks;
346
347 if (irqtime_account_hi_update()) {
348 cpustat[CPUTIME_IRQ] += cputime;
349 } else if (irqtime_account_si_update()) {
350 cpustat[CPUTIME_SOFTIRQ] += cputime;
351 } else if (this_cpu_ksoftirqd() == p) {
352 /*
353 * ksoftirqd time do not get accounted in cpu_softirq_time.
354 * So, we have to handle it separately here.
355 * Also, p->stime needs to be updated for ksoftirqd.
356 */
357 __account_system_time(p, cputime, scaled, CPUTIME_SOFTIRQ);
358 } else if (user_tick) {
359 account_user_time(p, cputime, scaled);
360 } else if (p == rq->idle) {
361 account_idle_time(cputime);
362 } else if (p->flags & PF_VCPU) { /* System time or guest time */
363 account_guest_time(p, cputime, scaled);
364 } else {
365 __account_system_time(p, cputime, scaled, CPUTIME_SYSTEM);
366 }
367}
368
369static void irqtime_account_idle_ticks(int ticks)
370{
371 struct rq *rq = this_rq();
372
373 irqtime_account_process_tick(current, 0, rq, ticks);
374}
375#else /* CONFIG_IRQ_TIME_ACCOUNTING */
376static inline void irqtime_account_idle_ticks(int ticks) {}
377static inline void irqtime_account_process_tick(struct task_struct *p, int user_tick,
378 struct rq *rq, int nr_ticks) {}
379#endif /* CONFIG_IRQ_TIME_ACCOUNTING */
380
381/*
382 * Use precise platform statistics if available:
383 */
384#ifdef CONFIG_VIRT_CPU_ACCOUNTING
385
386#ifndef __ARCH_HAS_VTIME_TASK_SWITCH
387void vtime_common_task_switch(struct task_struct *prev)
388{
389 if (is_idle_task(prev))
390 vtime_account_idle(prev);
391 else
392 vtime_account_system(prev);
393
394#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
395 vtime_account_user(prev);
396#endif
397 arch_vtime_task_switch(prev);
398}
399#endif
400
401/*
402 * Archs that account the whole time spent in the idle task
403 * (outside irq) as idle time can rely on this and just implement
404 * vtime_account_system() and vtime_account_idle(). Archs that
405 * have other meaning of the idle time (s390 only includes the
406 * time spent by the CPU when it's in low power mode) must override
407 * vtime_account().
408 */
409#ifndef __ARCH_HAS_VTIME_ACCOUNT
410void vtime_common_account_irq_enter(struct task_struct *tsk)
411{
412 if (!in_interrupt()) {
413 /*
414 * If we interrupted user, context_tracking_in_user()
415 * is 1 because the context tracking don't hook
416 * on irq entry/exit. This way we know if
417 * we need to flush user time on kernel entry.
418 */
419 if (context_tracking_in_user()) {
420 vtime_account_user(tsk);
421 return;
422 }
423
424 if (is_idle_task(tsk)) {
425 vtime_account_idle(tsk);
426 return;
427 }
428 }
429 vtime_account_system(tsk);
430}
431EXPORT_SYMBOL_GPL(vtime_common_account_irq_enter);
432#endif /* __ARCH_HAS_VTIME_ACCOUNT */
433#endif /* CONFIG_VIRT_CPU_ACCOUNTING */
434
435
436#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
437void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
438{
439 *ut = p->utime;
440 *st = p->stime;
441}
442
443void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
444{
445 struct task_cputime cputime;
446
447 thread_group_cputime(p, &cputime);
448
449 *ut = cputime.utime;
450 *st = cputime.stime;
451}
452#else /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
453/*
454 * Account a single tick of cpu time.
455 * @p: the process that the cpu time gets accounted to
456 * @user_tick: indicates if the tick is a user or a system tick
457 */
458void account_process_tick(struct task_struct *p, int user_tick)
459{
460 cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
461 struct rq *rq = this_rq();
462
463 if (vtime_accounting_enabled())
464 return;
465
466 if (sched_clock_irqtime) {
467 irqtime_account_process_tick(p, user_tick, rq, 1);
468 return;
469 }
470
471 if (steal_account_process_tick())
472 return;
473
474 if (user_tick)
475 account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);
476 else if ((p != rq->idle) || (irq_count() != HARDIRQ_OFFSET))
477 account_system_time(p, HARDIRQ_OFFSET, cputime_one_jiffy,
478 one_jiffy_scaled);
479 else
480 account_idle_time(cputime_one_jiffy);
481}
482
483/*
484 * Account multiple ticks of steal time.
485 * @p: the process from which the cpu time has been stolen
486 * @ticks: number of stolen ticks
487 */
488void account_steal_ticks(unsigned long ticks)
489{
490 account_steal_time(jiffies_to_cputime(ticks));
491}
492
493/*
494 * Account multiple ticks of idle time.
495 * @ticks: number of stolen ticks
496 */
497void account_idle_ticks(unsigned long ticks)
498{
499
500 if (sched_clock_irqtime) {
501 irqtime_account_idle_ticks(ticks);
502 return;
503 }
504
505 account_idle_time(jiffies_to_cputime(ticks));
506}
507
508/*
509 * Perform (stime * rtime) / total, but avoid multiplication overflow by
510 * loosing precision when the numbers are big.
511 */
512static cputime_t scale_stime(u64 stime, u64 rtime, u64 total)
513{
514 u64 scaled;
515
516 for (;;) {
517 /* Make sure "rtime" is the bigger of stime/rtime */
518 if (stime > rtime)
519 swap(rtime, stime);
520
521 /* Make sure 'total' fits in 32 bits */
522 if (total >> 32)
523 goto drop_precision;
524
525 /* Does rtime (and thus stime) fit in 32 bits? */
526 if (!(rtime >> 32))
527 break;
528
529 /* Can we just balance rtime/stime rather than dropping bits? */
530 if (stime >> 31)
531 goto drop_precision;
532
533 /* We can grow stime and shrink rtime and try to make them both fit */
534 stime <<= 1;
535 rtime >>= 1;
536 continue;
537
538drop_precision:
539 /* We drop from rtime, it has more bits than stime */
540 rtime >>= 1;
541 total >>= 1;
542 }
543
544 /*
545 * Make sure gcc understands that this is a 32x32->64 multiply,
546 * followed by a 64/32->64 divide.
547 */
548 scaled = div_u64((u64) (u32) stime * (u64) (u32) rtime, (u32)total);
549 return (__force cputime_t) scaled;
550}
551
552/*
553 * Adjust tick based cputime random precision against scheduler
554 * runtime accounting.
555 */
556static void cputime_adjust(struct task_cputime *curr,
557 struct cputime *prev,
558 cputime_t *ut, cputime_t *st)
559{
560 cputime_t rtime, stime, utime;
561
562 /*
563 * Tick based cputime accounting depend on random scheduling
564 * timeslices of a task to be interrupted or not by the timer.
565 * Depending on these circumstances, the number of these interrupts
566 * may be over or under-optimistic, matching the real user and system
567 * cputime with a variable precision.
568 *
569 * Fix this by scaling these tick based values against the total
570 * runtime accounted by the CFS scheduler.
571 */
572 rtime = nsecs_to_cputime(curr->sum_exec_runtime);
573
574 /*
575 * Update userspace visible utime/stime values only if actual execution
576 * time is bigger than already exported. Note that can happen, that we
577 * provided bigger values due to scaling inaccuracy on big numbers.
578 */
579 if (prev->stime + prev->utime >= rtime)
580 goto out;
581
582 stime = curr->stime;
583 utime = curr->utime;
584
585 if (utime == 0) {
586 stime = rtime;
587 } else if (stime == 0) {
588 utime = rtime;
589 } else {
590 cputime_t total = stime + utime;
591
592 stime = scale_stime((__force u64)stime,
593 (__force u64)rtime, (__force u64)total);
594 utime = rtime - stime;
595 }
596
597 /*
598 * If the tick based count grows faster than the scheduler one,
599 * the result of the scaling may go backward.
600 * Let's enforce monotonicity.
601 */
602 prev->stime = max(prev->stime, stime);
603 prev->utime = max(prev->utime, utime);
604
605out:
606 *ut = prev->utime;
607 *st = prev->stime;
608}
609
610void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
611{
612 struct task_cputime cputime = {
613 .sum_exec_runtime = p->se.sum_exec_runtime,
614 };
615
616 task_cputime(p, &cputime.utime, &cputime.stime);
617 cputime_adjust(&cputime, &p->prev_cputime, ut, st);
618}
619
620/*
621 * Must be called with siglock held.
622 */
623void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
624{
625 struct task_cputime cputime;
626
627 thread_group_cputime(p, &cputime);
628 cputime_adjust(&cputime, &p->signal->prev_cputime, ut, st);
629}
630#endif /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
631
632#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
633static unsigned long long vtime_delta(struct task_struct *tsk)
634{
635 unsigned long long clock;
636
637 clock = local_clock();
638 if (clock < tsk->vtime_snap)
639 return 0;
640
641 return clock - tsk->vtime_snap;
642}
643
644static cputime_t get_vtime_delta(struct task_struct *tsk)
645{
646 unsigned long long delta = vtime_delta(tsk);
647
648 WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_SLEEPING);
649 tsk->vtime_snap += delta;
650
651 /* CHECKME: always safe to convert nsecs to cputime? */
652 return nsecs_to_cputime(delta);
653}
654
655static void __vtime_account_system(struct task_struct *tsk)
656{
657 cputime_t delta_cpu = get_vtime_delta(tsk);
658
659 account_system_time(tsk, irq_count(), delta_cpu, cputime_to_scaled(delta_cpu));
660}
661
662void vtime_account_system(struct task_struct *tsk)
663{
664 write_seqlock(&tsk->vtime_seqlock);
665 __vtime_account_system(tsk);
666 write_sequnlock(&tsk->vtime_seqlock);
667}
668
669void vtime_gen_account_irq_exit(struct task_struct *tsk)
670{
671 write_seqlock(&tsk->vtime_seqlock);
672 __vtime_account_system(tsk);
673 if (context_tracking_in_user())
674 tsk->vtime_snap_whence = VTIME_USER;
675 write_sequnlock(&tsk->vtime_seqlock);
676}
677
678void vtime_account_user(struct task_struct *tsk)
679{
680 cputime_t delta_cpu;
681
682 write_seqlock(&tsk->vtime_seqlock);
683 delta_cpu = get_vtime_delta(tsk);
684 tsk->vtime_snap_whence = VTIME_SYS;
685 account_user_time(tsk, delta_cpu, cputime_to_scaled(delta_cpu));
686 write_sequnlock(&tsk->vtime_seqlock);
687}
688
689void vtime_user_enter(struct task_struct *tsk)
690{
691 write_seqlock(&tsk->vtime_seqlock);
692 __vtime_account_system(tsk);
693 tsk->vtime_snap_whence = VTIME_USER;
694 write_sequnlock(&tsk->vtime_seqlock);
695}
696
697void vtime_guest_enter(struct task_struct *tsk)
698{
699 /*
700 * The flags must be updated under the lock with
701 * the vtime_snap flush and update.
702 * That enforces a right ordering and update sequence
703 * synchronization against the reader (task_gtime())
704 * that can thus safely catch up with a tickless delta.
705 */
706 write_seqlock(&tsk->vtime_seqlock);
707 __vtime_account_system(tsk);
708 current->flags |= PF_VCPU;
709 write_sequnlock(&tsk->vtime_seqlock);
710}
711EXPORT_SYMBOL_GPL(vtime_guest_enter);
712
713void vtime_guest_exit(struct task_struct *tsk)
714{
715 write_seqlock(&tsk->vtime_seqlock);
716 __vtime_account_system(tsk);
717 current->flags &= ~PF_VCPU;
718 write_sequnlock(&tsk->vtime_seqlock);
719}
720EXPORT_SYMBOL_GPL(vtime_guest_exit);
721
722void vtime_account_idle(struct task_struct *tsk)
723{
724 cputime_t delta_cpu = get_vtime_delta(tsk);
725
726 account_idle_time(delta_cpu);
727}
728
729void arch_vtime_task_switch(struct task_struct *prev)
730{
731 write_seqlock(&prev->vtime_seqlock);
732 prev->vtime_snap_whence = VTIME_SLEEPING;
733 write_sequnlock(&prev->vtime_seqlock);
734
735 write_seqlock(¤t->vtime_seqlock);
736 current->vtime_snap_whence = VTIME_SYS;
737 current->vtime_snap = sched_clock_cpu(smp_processor_id());
738 write_sequnlock(¤t->vtime_seqlock);
739}
740
741void vtime_init_idle(struct task_struct *t, int cpu)
742{
743 unsigned long flags;
744
745 write_seqlock_irqsave(&t->vtime_seqlock, flags);
746 t->vtime_snap_whence = VTIME_SYS;
747 t->vtime_snap = sched_clock_cpu(cpu);
748 write_sequnlock_irqrestore(&t->vtime_seqlock, flags);
749}
750
751cputime_t task_gtime(struct task_struct *t)
752{
753 unsigned int seq;
754 cputime_t gtime;
755
756 do {
757 seq = read_seqbegin(&t->vtime_seqlock);
758
759 gtime = t->gtime;
760 if (t->flags & PF_VCPU)
761 gtime += vtime_delta(t);
762
763 } while (read_seqretry(&t->vtime_seqlock, seq));
764
765 return gtime;
766}
767
768/*
769 * Fetch cputime raw values from fields of task_struct and
770 * add up the pending nohz execution time since the last
771 * cputime snapshot.
772 */
773static void
774fetch_task_cputime(struct task_struct *t,
775 cputime_t *u_dst, cputime_t *s_dst,
776 cputime_t *u_src, cputime_t *s_src,
777 cputime_t *udelta, cputime_t *sdelta)
778{
779 unsigned int seq;
780 unsigned long long delta;
781
782 do {
783 *udelta = 0;
784 *sdelta = 0;
785
786 seq = read_seqbegin(&t->vtime_seqlock);
787
788 if (u_dst)
789 *u_dst = *u_src;
790 if (s_dst)
791 *s_dst = *s_src;
792
793 /* Task is sleeping, nothing to add */
794 if (t->vtime_snap_whence == VTIME_SLEEPING ||
795 is_idle_task(t))
796 continue;
797
798 delta = vtime_delta(t);
799
800 /*
801 * Task runs either in user or kernel space, add pending nohz time to
802 * the right place.
803 */
804 if (t->vtime_snap_whence == VTIME_USER || t->flags & PF_VCPU) {
805 *udelta = delta;
806 } else {
807 if (t->vtime_snap_whence == VTIME_SYS)
808 *sdelta = delta;
809 }
810 } while (read_seqretry(&t->vtime_seqlock, seq));
811}
812
813
814void task_cputime(struct task_struct *t, cputime_t *utime, cputime_t *stime)
815{
816 cputime_t udelta, sdelta;
817
818 fetch_task_cputime(t, utime, stime, &t->utime,
819 &t->stime, &udelta, &sdelta);
820 if (utime)
821 *utime += udelta;
822 if (stime)
823 *stime += sdelta;
824}
825
826void task_cputime_scaled(struct task_struct *t,
827 cputime_t *utimescaled, cputime_t *stimescaled)
828{
829 cputime_t udelta, sdelta;
830
831 fetch_task_cputime(t, utimescaled, stimescaled,
832 &t->utimescaled, &t->stimescaled, &udelta, &sdelta);
833 if (utimescaled)
834 *utimescaled += cputime_to_scaled(udelta);
835 if (stimescaled)
836 *stimescaled += cputime_to_scaled(sdelta);
837}
838#endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Simple CPU accounting cgroup controller
4 */
5
6#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
7 #include <asm/cputime.h>
8#endif
9
10#ifdef CONFIG_IRQ_TIME_ACCOUNTING
11
12/*
13 * There are no locks covering percpu hardirq/softirq time.
14 * They are only modified in vtime_account, on corresponding CPU
15 * with interrupts disabled. So, writes are safe.
16 * They are read and saved off onto struct rq in update_rq_clock().
17 * This may result in other CPU reading this CPU's irq time and can
18 * race with irq/vtime_account on this CPU. We would either get old
19 * or new value with a side effect of accounting a slice of irq time to wrong
20 * task when irq is in progress while we read rq->clock. That is a worthy
21 * compromise in place of having locks on each irq in account_system_time.
22 */
23DEFINE_PER_CPU(struct irqtime, cpu_irqtime);
24
25static int sched_clock_irqtime;
26
27void enable_sched_clock_irqtime(void)
28{
29 sched_clock_irqtime = 1;
30}
31
32void disable_sched_clock_irqtime(void)
33{
34 sched_clock_irqtime = 0;
35}
36
37static void irqtime_account_delta(struct irqtime *irqtime, u64 delta,
38 enum cpu_usage_stat idx)
39{
40 u64 *cpustat = kcpustat_this_cpu->cpustat;
41
42 u64_stats_update_begin(&irqtime->sync);
43 cpustat[idx] += delta;
44 irqtime->total += delta;
45 irqtime->tick_delta += delta;
46 u64_stats_update_end(&irqtime->sync);
47}
48
49/*
50 * Called after incrementing preempt_count on {soft,}irq_enter
51 * and before decrementing preempt_count on {soft,}irq_exit.
52 */
53void irqtime_account_irq(struct task_struct *curr, unsigned int offset)
54{
55 struct irqtime *irqtime = this_cpu_ptr(&cpu_irqtime);
56 unsigned int pc;
57 s64 delta;
58 int cpu;
59
60 if (!sched_clock_irqtime)
61 return;
62
63 cpu = smp_processor_id();
64 delta = sched_clock_cpu(cpu) - irqtime->irq_start_time;
65 irqtime->irq_start_time += delta;
66 pc = irq_count() - offset;
67
68 /*
69 * We do not account for softirq time from ksoftirqd here.
70 * We want to continue accounting softirq time to ksoftirqd thread
71 * in that case, so as not to confuse scheduler with a special task
72 * that do not consume any time, but still wants to run.
73 */
74 if (pc & HARDIRQ_MASK)
75 irqtime_account_delta(irqtime, delta, CPUTIME_IRQ);
76 else if ((pc & SOFTIRQ_OFFSET) && curr != this_cpu_ksoftirqd())
77 irqtime_account_delta(irqtime, delta, CPUTIME_SOFTIRQ);
78}
79
80static u64 irqtime_tick_accounted(u64 maxtime)
81{
82 struct irqtime *irqtime = this_cpu_ptr(&cpu_irqtime);
83 u64 delta;
84
85 delta = min(irqtime->tick_delta, maxtime);
86 irqtime->tick_delta -= delta;
87
88 return delta;
89}
90
91#else /* CONFIG_IRQ_TIME_ACCOUNTING */
92
93#define sched_clock_irqtime (0)
94
95static u64 irqtime_tick_accounted(u64 dummy)
96{
97 return 0;
98}
99
100#endif /* !CONFIG_IRQ_TIME_ACCOUNTING */
101
102static inline void task_group_account_field(struct task_struct *p, int index,
103 u64 tmp)
104{
105 /*
106 * Since all updates are sure to touch the root cgroup, we
107 * get ourselves ahead and touch it first. If the root cgroup
108 * is the only cgroup, then nothing else should be necessary.
109 *
110 */
111 __this_cpu_add(kernel_cpustat.cpustat[index], tmp);
112
113 cgroup_account_cputime_field(p, index, tmp);
114}
115
116/*
117 * Account user CPU time to a process.
118 * @p: the process that the CPU time gets accounted to
119 * @cputime: the CPU time spent in user space since the last update
120 */
121void account_user_time(struct task_struct *p, u64 cputime)
122{
123 int index;
124
125 /* Add user time to process. */
126 p->utime += cputime;
127 account_group_user_time(p, cputime);
128
129 index = (task_nice(p) > 0) ? CPUTIME_NICE : CPUTIME_USER;
130
131 /* Add user time to cpustat. */
132 task_group_account_field(p, index, cputime);
133
134 /* Account for user time used */
135 acct_account_cputime(p);
136}
137
138/*
139 * Account guest CPU time to a process.
140 * @p: the process that the CPU time gets accounted to
141 * @cputime: the CPU time spent in virtual machine since the last update
142 */
143void account_guest_time(struct task_struct *p, u64 cputime)
144{
145 u64 *cpustat = kcpustat_this_cpu->cpustat;
146
147 /* Add guest time to process. */
148 p->utime += cputime;
149 account_group_user_time(p, cputime);
150 p->gtime += cputime;
151
152 /* Add guest time to cpustat. */
153 if (task_nice(p) > 0) {
154 task_group_account_field(p, CPUTIME_NICE, cputime);
155 cpustat[CPUTIME_GUEST_NICE] += cputime;
156 } else {
157 task_group_account_field(p, CPUTIME_USER, cputime);
158 cpustat[CPUTIME_GUEST] += cputime;
159 }
160}
161
162/*
163 * Account system CPU time to a process and desired cpustat field
164 * @p: the process that the CPU time gets accounted to
165 * @cputime: the CPU time spent in kernel space since the last update
166 * @index: pointer to cpustat field that has to be updated
167 */
168void account_system_index_time(struct task_struct *p,
169 u64 cputime, enum cpu_usage_stat index)
170{
171 /* Add system time to process. */
172 p->stime += cputime;
173 account_group_system_time(p, cputime);
174
175 /* Add system time to cpustat. */
176 task_group_account_field(p, index, cputime);
177
178 /* Account for system time used */
179 acct_account_cputime(p);
180}
181
182/*
183 * Account system CPU time to a process.
184 * @p: the process that the CPU time gets accounted to
185 * @hardirq_offset: the offset to subtract from hardirq_count()
186 * @cputime: the CPU time spent in kernel space since the last update
187 */
188void account_system_time(struct task_struct *p, int hardirq_offset, u64 cputime)
189{
190 int index;
191
192 if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) {
193 account_guest_time(p, cputime);
194 return;
195 }
196
197 if (hardirq_count() - hardirq_offset)
198 index = CPUTIME_IRQ;
199 else if (in_serving_softirq())
200 index = CPUTIME_SOFTIRQ;
201 else
202 index = CPUTIME_SYSTEM;
203
204 account_system_index_time(p, cputime, index);
205}
206
207/*
208 * Account for involuntary wait time.
209 * @cputime: the CPU time spent in involuntary wait
210 */
211void account_steal_time(u64 cputime)
212{
213 u64 *cpustat = kcpustat_this_cpu->cpustat;
214
215 cpustat[CPUTIME_STEAL] += cputime;
216}
217
218/*
219 * Account for idle time.
220 * @cputime: the CPU time spent in idle wait
221 */
222void account_idle_time(u64 cputime)
223{
224 u64 *cpustat = kcpustat_this_cpu->cpustat;
225 struct rq *rq = this_rq();
226
227 if (atomic_read(&rq->nr_iowait) > 0)
228 cpustat[CPUTIME_IOWAIT] += cputime;
229 else
230 cpustat[CPUTIME_IDLE] += cputime;
231}
232
233
234#ifdef CONFIG_SCHED_CORE
235/*
236 * Account for forceidle time due to core scheduling.
237 *
238 * REQUIRES: schedstat is enabled.
239 */
240void __account_forceidle_time(struct task_struct *p, u64 delta)
241{
242 __schedstat_add(p->stats.core_forceidle_sum, delta);
243
244 task_group_account_field(p, CPUTIME_FORCEIDLE, delta);
245}
246#endif
247
248/*
249 * When a guest is interrupted for a longer amount of time, missed clock
250 * ticks are not redelivered later. Due to that, this function may on
251 * occasion account more time than the calling functions think elapsed.
252 */
253static __always_inline u64 steal_account_process_time(u64 maxtime)
254{
255#ifdef CONFIG_PARAVIRT
256 if (static_key_false(¶virt_steal_enabled)) {
257 u64 steal;
258
259 steal = paravirt_steal_clock(smp_processor_id());
260 steal -= this_rq()->prev_steal_time;
261 steal = min(steal, maxtime);
262 account_steal_time(steal);
263 this_rq()->prev_steal_time += steal;
264
265 return steal;
266 }
267#endif
268 return 0;
269}
270
271/*
272 * Account how much elapsed time was spent in steal, irq, or softirq time.
273 */
274static inline u64 account_other_time(u64 max)
275{
276 u64 accounted;
277
278 lockdep_assert_irqs_disabled();
279
280 accounted = steal_account_process_time(max);
281
282 if (accounted < max)
283 accounted += irqtime_tick_accounted(max - accounted);
284
285 return accounted;
286}
287
288#ifdef CONFIG_64BIT
289static inline u64 read_sum_exec_runtime(struct task_struct *t)
290{
291 return t->se.sum_exec_runtime;
292}
293#else
294static u64 read_sum_exec_runtime(struct task_struct *t)
295{
296 u64 ns;
297 struct rq_flags rf;
298 struct rq *rq;
299
300 rq = task_rq_lock(t, &rf);
301 ns = t->se.sum_exec_runtime;
302 task_rq_unlock(rq, t, &rf);
303
304 return ns;
305}
306#endif
307
308/*
309 * Accumulate raw cputime values of dead tasks (sig->[us]time) and live
310 * tasks (sum on group iteration) belonging to @tsk's group.
311 */
312void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
313{
314 struct signal_struct *sig = tsk->signal;
315 u64 utime, stime;
316 struct task_struct *t;
317 unsigned int seq, nextseq;
318 unsigned long flags;
319
320 /*
321 * Update current task runtime to account pending time since last
322 * scheduler action or thread_group_cputime() call. This thread group
323 * might have other running tasks on different CPUs, but updating
324 * their runtime can affect syscall performance, so we skip account
325 * those pending times and rely only on values updated on tick or
326 * other scheduler action.
327 */
328 if (same_thread_group(current, tsk))
329 (void) task_sched_runtime(current);
330
331 rcu_read_lock();
332 /* Attempt a lockless read on the first round. */
333 nextseq = 0;
334 do {
335 seq = nextseq;
336 flags = read_seqbegin_or_lock_irqsave(&sig->stats_lock, &seq);
337 times->utime = sig->utime;
338 times->stime = sig->stime;
339 times->sum_exec_runtime = sig->sum_sched_runtime;
340
341 for_each_thread(tsk, t) {
342 task_cputime(t, &utime, &stime);
343 times->utime += utime;
344 times->stime += stime;
345 times->sum_exec_runtime += read_sum_exec_runtime(t);
346 }
347 /* If lockless access failed, take the lock. */
348 nextseq = 1;
349 } while (need_seqretry(&sig->stats_lock, seq));
350 done_seqretry_irqrestore(&sig->stats_lock, seq, flags);
351 rcu_read_unlock();
352}
353
354#ifdef CONFIG_IRQ_TIME_ACCOUNTING
355/*
356 * Account a tick to a process and cpustat
357 * @p: the process that the CPU time gets accounted to
358 * @user_tick: is the tick from userspace
359 * @rq: the pointer to rq
360 *
361 * Tick demultiplexing follows the order
362 * - pending hardirq update
363 * - pending softirq update
364 * - user_time
365 * - idle_time
366 * - system time
367 * - check for guest_time
368 * - else account as system_time
369 *
370 * Check for hardirq is done both for system and user time as there is
371 * no timer going off while we are on hardirq and hence we may never get an
372 * opportunity to update it solely in system time.
373 * p->stime and friends are only updated on system time and not on irq
374 * softirq as those do not count in task exec_runtime any more.
375 */
376static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
377 int ticks)
378{
379 u64 other, cputime = TICK_NSEC * ticks;
380
381 /*
382 * When returning from idle, many ticks can get accounted at
383 * once, including some ticks of steal, irq, and softirq time.
384 * Subtract those ticks from the amount of time accounted to
385 * idle, or potentially user or system time. Due to rounding,
386 * other time can exceed ticks occasionally.
387 */
388 other = account_other_time(ULONG_MAX);
389 if (other >= cputime)
390 return;
391
392 cputime -= other;
393
394 if (this_cpu_ksoftirqd() == p) {
395 /*
396 * ksoftirqd time do not get accounted in cpu_softirq_time.
397 * So, we have to handle it separately here.
398 * Also, p->stime needs to be updated for ksoftirqd.
399 */
400 account_system_index_time(p, cputime, CPUTIME_SOFTIRQ);
401 } else if (user_tick) {
402 account_user_time(p, cputime);
403 } else if (p == this_rq()->idle) {
404 account_idle_time(cputime);
405 } else if (p->flags & PF_VCPU) { /* System time or guest time */
406 account_guest_time(p, cputime);
407 } else {
408 account_system_index_time(p, cputime, CPUTIME_SYSTEM);
409 }
410}
411
412static void irqtime_account_idle_ticks(int ticks)
413{
414 irqtime_account_process_tick(current, 0, ticks);
415}
416#else /* CONFIG_IRQ_TIME_ACCOUNTING */
417static inline void irqtime_account_idle_ticks(int ticks) { }
418static inline void irqtime_account_process_tick(struct task_struct *p, int user_tick,
419 int nr_ticks) { }
420#endif /* CONFIG_IRQ_TIME_ACCOUNTING */
421
422/*
423 * Use precise platform statistics if available:
424 */
425#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
426
427# ifndef __ARCH_HAS_VTIME_TASK_SWITCH
428void vtime_task_switch(struct task_struct *prev)
429{
430 if (is_idle_task(prev))
431 vtime_account_idle(prev);
432 else
433 vtime_account_kernel(prev);
434
435 vtime_flush(prev);
436 arch_vtime_task_switch(prev);
437}
438# endif
439
440void vtime_account_irq(struct task_struct *tsk, unsigned int offset)
441{
442 unsigned int pc = irq_count() - offset;
443
444 if (pc & HARDIRQ_OFFSET) {
445 vtime_account_hardirq(tsk);
446 } else if (pc & SOFTIRQ_OFFSET) {
447 vtime_account_softirq(tsk);
448 } else if (!IS_ENABLED(CONFIG_HAVE_VIRT_CPU_ACCOUNTING_IDLE) &&
449 is_idle_task(tsk)) {
450 vtime_account_idle(tsk);
451 } else {
452 vtime_account_kernel(tsk);
453 }
454}
455
456void cputime_adjust(struct task_cputime *curr, struct prev_cputime *prev,
457 u64 *ut, u64 *st)
458{
459 *ut = curr->utime;
460 *st = curr->stime;
461}
462
463void task_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
464{
465 *ut = p->utime;
466 *st = p->stime;
467}
468EXPORT_SYMBOL_GPL(task_cputime_adjusted);
469
470void thread_group_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
471{
472 struct task_cputime cputime;
473
474 thread_group_cputime(p, &cputime);
475
476 *ut = cputime.utime;
477 *st = cputime.stime;
478}
479
480#else /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE: */
481
482/*
483 * Account a single tick of CPU time.
484 * @p: the process that the CPU time gets accounted to
485 * @user_tick: indicates if the tick is a user or a system tick
486 */
487void account_process_tick(struct task_struct *p, int user_tick)
488{
489 u64 cputime, steal;
490
491 if (vtime_accounting_enabled_this_cpu())
492 return;
493
494 if (sched_clock_irqtime) {
495 irqtime_account_process_tick(p, user_tick, 1);
496 return;
497 }
498
499 cputime = TICK_NSEC;
500 steal = steal_account_process_time(ULONG_MAX);
501
502 if (steal >= cputime)
503 return;
504
505 cputime -= steal;
506
507 if (user_tick)
508 account_user_time(p, cputime);
509 else if ((p != this_rq()->idle) || (irq_count() != HARDIRQ_OFFSET))
510 account_system_time(p, HARDIRQ_OFFSET, cputime);
511 else
512 account_idle_time(cputime);
513}
514
515/*
516 * Account multiple ticks of idle time.
517 * @ticks: number of stolen ticks
518 */
519void account_idle_ticks(unsigned long ticks)
520{
521 u64 cputime, steal;
522
523 if (sched_clock_irqtime) {
524 irqtime_account_idle_ticks(ticks);
525 return;
526 }
527
528 cputime = ticks * TICK_NSEC;
529 steal = steal_account_process_time(ULONG_MAX);
530
531 if (steal >= cputime)
532 return;
533
534 cputime -= steal;
535 account_idle_time(cputime);
536}
537
538/*
539 * Adjust tick based cputime random precision against scheduler runtime
540 * accounting.
541 *
542 * Tick based cputime accounting depend on random scheduling timeslices of a
543 * task to be interrupted or not by the timer. Depending on these
544 * circumstances, the number of these interrupts may be over or
545 * under-optimistic, matching the real user and system cputime with a variable
546 * precision.
547 *
548 * Fix this by scaling these tick based values against the total runtime
549 * accounted by the CFS scheduler.
550 *
551 * This code provides the following guarantees:
552 *
553 * stime + utime == rtime
554 * stime_i+1 >= stime_i, utime_i+1 >= utime_i
555 *
556 * Assuming that rtime_i+1 >= rtime_i.
557 */
558void cputime_adjust(struct task_cputime *curr, struct prev_cputime *prev,
559 u64 *ut, u64 *st)
560{
561 u64 rtime, stime, utime;
562 unsigned long flags;
563
564 /* Serialize concurrent callers such that we can honour our guarantees */
565 raw_spin_lock_irqsave(&prev->lock, flags);
566 rtime = curr->sum_exec_runtime;
567
568 /*
569 * This is possible under two circumstances:
570 * - rtime isn't monotonic after all (a bug);
571 * - we got reordered by the lock.
572 *
573 * In both cases this acts as a filter such that the rest of the code
574 * can assume it is monotonic regardless of anything else.
575 */
576 if (prev->stime + prev->utime >= rtime)
577 goto out;
578
579 stime = curr->stime;
580 utime = curr->utime;
581
582 /*
583 * If either stime or utime are 0, assume all runtime is userspace.
584 * Once a task gets some ticks, the monotonicity code at 'update:'
585 * will ensure things converge to the observed ratio.
586 */
587 if (stime == 0) {
588 utime = rtime;
589 goto update;
590 }
591
592 if (utime == 0) {
593 stime = rtime;
594 goto update;
595 }
596
597 stime = mul_u64_u64_div_u64(stime, rtime, stime + utime);
598
599update:
600 /*
601 * Make sure stime doesn't go backwards; this preserves monotonicity
602 * for utime because rtime is monotonic.
603 *
604 * utime_i+1 = rtime_i+1 - stime_i
605 * = rtime_i+1 - (rtime_i - utime_i)
606 * = (rtime_i+1 - rtime_i) + utime_i
607 * >= utime_i
608 */
609 if (stime < prev->stime)
610 stime = prev->stime;
611 utime = rtime - stime;
612
613 /*
614 * Make sure utime doesn't go backwards; this still preserves
615 * monotonicity for stime, analogous argument to above.
616 */
617 if (utime < prev->utime) {
618 utime = prev->utime;
619 stime = rtime - utime;
620 }
621
622 prev->stime = stime;
623 prev->utime = utime;
624out:
625 *ut = prev->utime;
626 *st = prev->stime;
627 raw_spin_unlock_irqrestore(&prev->lock, flags);
628}
629
630void task_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
631{
632 struct task_cputime cputime = {
633 .sum_exec_runtime = p->se.sum_exec_runtime,
634 };
635
636 if (task_cputime(p, &cputime.utime, &cputime.stime))
637 cputime.sum_exec_runtime = task_sched_runtime(p);
638 cputime_adjust(&cputime, &p->prev_cputime, ut, st);
639}
640EXPORT_SYMBOL_GPL(task_cputime_adjusted);
641
642void thread_group_cputime_adjusted(struct task_struct *p, u64 *ut, u64 *st)
643{
644 struct task_cputime cputime;
645
646 thread_group_cputime(p, &cputime);
647 cputime_adjust(&cputime, &p->signal->prev_cputime, ut, st);
648}
649#endif /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
650
651#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
652static u64 vtime_delta(struct vtime *vtime)
653{
654 unsigned long long clock;
655
656 clock = sched_clock();
657 if (clock < vtime->starttime)
658 return 0;
659
660 return clock - vtime->starttime;
661}
662
663static u64 get_vtime_delta(struct vtime *vtime)
664{
665 u64 delta = vtime_delta(vtime);
666 u64 other;
667
668 /*
669 * Unlike tick based timing, vtime based timing never has lost
670 * ticks, and no need for steal time accounting to make up for
671 * lost ticks. Vtime accounts a rounded version of actual
672 * elapsed time. Limit account_other_time to prevent rounding
673 * errors from causing elapsed vtime to go negative.
674 */
675 other = account_other_time(delta);
676 WARN_ON_ONCE(vtime->state == VTIME_INACTIVE);
677 vtime->starttime += delta;
678
679 return delta - other;
680}
681
682static void vtime_account_system(struct task_struct *tsk,
683 struct vtime *vtime)
684{
685 vtime->stime += get_vtime_delta(vtime);
686 if (vtime->stime >= TICK_NSEC) {
687 account_system_time(tsk, irq_count(), vtime->stime);
688 vtime->stime = 0;
689 }
690}
691
692static void vtime_account_guest(struct task_struct *tsk,
693 struct vtime *vtime)
694{
695 vtime->gtime += get_vtime_delta(vtime);
696 if (vtime->gtime >= TICK_NSEC) {
697 account_guest_time(tsk, vtime->gtime);
698 vtime->gtime = 0;
699 }
700}
701
702static void __vtime_account_kernel(struct task_struct *tsk,
703 struct vtime *vtime)
704{
705 /* We might have scheduled out from guest path */
706 if (vtime->state == VTIME_GUEST)
707 vtime_account_guest(tsk, vtime);
708 else
709 vtime_account_system(tsk, vtime);
710}
711
712void vtime_account_kernel(struct task_struct *tsk)
713{
714 struct vtime *vtime = &tsk->vtime;
715
716 if (!vtime_delta(vtime))
717 return;
718
719 write_seqcount_begin(&vtime->seqcount);
720 __vtime_account_kernel(tsk, vtime);
721 write_seqcount_end(&vtime->seqcount);
722}
723
724void vtime_user_enter(struct task_struct *tsk)
725{
726 struct vtime *vtime = &tsk->vtime;
727
728 write_seqcount_begin(&vtime->seqcount);
729 vtime_account_system(tsk, vtime);
730 vtime->state = VTIME_USER;
731 write_seqcount_end(&vtime->seqcount);
732}
733
734void vtime_user_exit(struct task_struct *tsk)
735{
736 struct vtime *vtime = &tsk->vtime;
737
738 write_seqcount_begin(&vtime->seqcount);
739 vtime->utime += get_vtime_delta(vtime);
740 if (vtime->utime >= TICK_NSEC) {
741 account_user_time(tsk, vtime->utime);
742 vtime->utime = 0;
743 }
744 vtime->state = VTIME_SYS;
745 write_seqcount_end(&vtime->seqcount);
746}
747
748void vtime_guest_enter(struct task_struct *tsk)
749{
750 struct vtime *vtime = &tsk->vtime;
751 /*
752 * The flags must be updated under the lock with
753 * the vtime_starttime flush and update.
754 * That enforces a right ordering and update sequence
755 * synchronization against the reader (task_gtime())
756 * that can thus safely catch up with a tickless delta.
757 */
758 write_seqcount_begin(&vtime->seqcount);
759 vtime_account_system(tsk, vtime);
760 tsk->flags |= PF_VCPU;
761 vtime->state = VTIME_GUEST;
762 write_seqcount_end(&vtime->seqcount);
763}
764EXPORT_SYMBOL_GPL(vtime_guest_enter);
765
766void vtime_guest_exit(struct task_struct *tsk)
767{
768 struct vtime *vtime = &tsk->vtime;
769
770 write_seqcount_begin(&vtime->seqcount);
771 vtime_account_guest(tsk, vtime);
772 tsk->flags &= ~PF_VCPU;
773 vtime->state = VTIME_SYS;
774 write_seqcount_end(&vtime->seqcount);
775}
776EXPORT_SYMBOL_GPL(vtime_guest_exit);
777
778void vtime_account_idle(struct task_struct *tsk)
779{
780 account_idle_time(get_vtime_delta(&tsk->vtime));
781}
782
783void vtime_task_switch_generic(struct task_struct *prev)
784{
785 struct vtime *vtime = &prev->vtime;
786
787 write_seqcount_begin(&vtime->seqcount);
788 if (vtime->state == VTIME_IDLE)
789 vtime_account_idle(prev);
790 else
791 __vtime_account_kernel(prev, vtime);
792 vtime->state = VTIME_INACTIVE;
793 vtime->cpu = -1;
794 write_seqcount_end(&vtime->seqcount);
795
796 vtime = ¤t->vtime;
797
798 write_seqcount_begin(&vtime->seqcount);
799 if (is_idle_task(current))
800 vtime->state = VTIME_IDLE;
801 else if (current->flags & PF_VCPU)
802 vtime->state = VTIME_GUEST;
803 else
804 vtime->state = VTIME_SYS;
805 vtime->starttime = sched_clock();
806 vtime->cpu = smp_processor_id();
807 write_seqcount_end(&vtime->seqcount);
808}
809
810void vtime_init_idle(struct task_struct *t, int cpu)
811{
812 struct vtime *vtime = &t->vtime;
813 unsigned long flags;
814
815 local_irq_save(flags);
816 write_seqcount_begin(&vtime->seqcount);
817 vtime->state = VTIME_IDLE;
818 vtime->starttime = sched_clock();
819 vtime->cpu = cpu;
820 write_seqcount_end(&vtime->seqcount);
821 local_irq_restore(flags);
822}
823
824u64 task_gtime(struct task_struct *t)
825{
826 struct vtime *vtime = &t->vtime;
827 unsigned int seq;
828 u64 gtime;
829
830 if (!vtime_accounting_enabled())
831 return t->gtime;
832
833 do {
834 seq = read_seqcount_begin(&vtime->seqcount);
835
836 gtime = t->gtime;
837 if (vtime->state == VTIME_GUEST)
838 gtime += vtime->gtime + vtime_delta(vtime);
839
840 } while (read_seqcount_retry(&vtime->seqcount, seq));
841
842 return gtime;
843}
844
845/*
846 * Fetch cputime raw values from fields of task_struct and
847 * add up the pending nohz execution time since the last
848 * cputime snapshot.
849 */
850bool task_cputime(struct task_struct *t, u64 *utime, u64 *stime)
851{
852 struct vtime *vtime = &t->vtime;
853 unsigned int seq;
854 u64 delta;
855 int ret;
856
857 if (!vtime_accounting_enabled()) {
858 *utime = t->utime;
859 *stime = t->stime;
860 return false;
861 }
862
863 do {
864 ret = false;
865 seq = read_seqcount_begin(&vtime->seqcount);
866
867 *utime = t->utime;
868 *stime = t->stime;
869
870 /* Task is sleeping or idle, nothing to add */
871 if (vtime->state < VTIME_SYS)
872 continue;
873
874 ret = true;
875 delta = vtime_delta(vtime);
876
877 /*
878 * Task runs either in user (including guest) or kernel space,
879 * add pending nohz time to the right place.
880 */
881 if (vtime->state == VTIME_SYS)
882 *stime += vtime->stime + delta;
883 else
884 *utime += vtime->utime + delta;
885 } while (read_seqcount_retry(&vtime->seqcount, seq));
886
887 return ret;
888}
889
890static int vtime_state_fetch(struct vtime *vtime, int cpu)
891{
892 int state = READ_ONCE(vtime->state);
893
894 /*
895 * We raced against a context switch, fetch the
896 * kcpustat task again.
897 */
898 if (vtime->cpu != cpu && vtime->cpu != -1)
899 return -EAGAIN;
900
901 /*
902 * Two possible things here:
903 * 1) We are seeing the scheduling out task (prev) or any past one.
904 * 2) We are seeing the scheduling in task (next) but it hasn't
905 * passed though vtime_task_switch() yet so the pending
906 * cputime of the prev task may not be flushed yet.
907 *
908 * Case 1) is ok but 2) is not. So wait for a safe VTIME state.
909 */
910 if (state == VTIME_INACTIVE)
911 return -EAGAIN;
912
913 return state;
914}
915
916static u64 kcpustat_user_vtime(struct vtime *vtime)
917{
918 if (vtime->state == VTIME_USER)
919 return vtime->utime + vtime_delta(vtime);
920 else if (vtime->state == VTIME_GUEST)
921 return vtime->gtime + vtime_delta(vtime);
922 return 0;
923}
924
925static int kcpustat_field_vtime(u64 *cpustat,
926 struct task_struct *tsk,
927 enum cpu_usage_stat usage,
928 int cpu, u64 *val)
929{
930 struct vtime *vtime = &tsk->vtime;
931 unsigned int seq;
932
933 do {
934 int state;
935
936 seq = read_seqcount_begin(&vtime->seqcount);
937
938 state = vtime_state_fetch(vtime, cpu);
939 if (state < 0)
940 return state;
941
942 *val = cpustat[usage];
943
944 /*
945 * Nice VS unnice cputime accounting may be inaccurate if
946 * the nice value has changed since the last vtime update.
947 * But proper fix would involve interrupting target on nice
948 * updates which is a no go on nohz_full (although the scheduler
949 * may still interrupt the target if rescheduling is needed...)
950 */
951 switch (usage) {
952 case CPUTIME_SYSTEM:
953 if (state == VTIME_SYS)
954 *val += vtime->stime + vtime_delta(vtime);
955 break;
956 case CPUTIME_USER:
957 if (task_nice(tsk) <= 0)
958 *val += kcpustat_user_vtime(vtime);
959 break;
960 case CPUTIME_NICE:
961 if (task_nice(tsk) > 0)
962 *val += kcpustat_user_vtime(vtime);
963 break;
964 case CPUTIME_GUEST:
965 if (state == VTIME_GUEST && task_nice(tsk) <= 0)
966 *val += vtime->gtime + vtime_delta(vtime);
967 break;
968 case CPUTIME_GUEST_NICE:
969 if (state == VTIME_GUEST && task_nice(tsk) > 0)
970 *val += vtime->gtime + vtime_delta(vtime);
971 break;
972 default:
973 break;
974 }
975 } while (read_seqcount_retry(&vtime->seqcount, seq));
976
977 return 0;
978}
979
980u64 kcpustat_field(struct kernel_cpustat *kcpustat,
981 enum cpu_usage_stat usage, int cpu)
982{
983 u64 *cpustat = kcpustat->cpustat;
984 u64 val = cpustat[usage];
985 struct rq *rq;
986 int err;
987
988 if (!vtime_accounting_enabled_cpu(cpu))
989 return val;
990
991 rq = cpu_rq(cpu);
992
993 for (;;) {
994 struct task_struct *curr;
995
996 rcu_read_lock();
997 curr = rcu_dereference(rq->curr);
998 if (WARN_ON_ONCE(!curr)) {
999 rcu_read_unlock();
1000 return cpustat[usage];
1001 }
1002
1003 err = kcpustat_field_vtime(cpustat, curr, usage, cpu, &val);
1004 rcu_read_unlock();
1005
1006 if (!err)
1007 return val;
1008
1009 cpu_relax();
1010 }
1011}
1012EXPORT_SYMBOL_GPL(kcpustat_field);
1013
1014static int kcpustat_cpu_fetch_vtime(struct kernel_cpustat *dst,
1015 const struct kernel_cpustat *src,
1016 struct task_struct *tsk, int cpu)
1017{
1018 struct vtime *vtime = &tsk->vtime;
1019 unsigned int seq;
1020
1021 do {
1022 u64 *cpustat;
1023 u64 delta;
1024 int state;
1025
1026 seq = read_seqcount_begin(&vtime->seqcount);
1027
1028 state = vtime_state_fetch(vtime, cpu);
1029 if (state < 0)
1030 return state;
1031
1032 *dst = *src;
1033 cpustat = dst->cpustat;
1034
1035 /* Task is sleeping, dead or idle, nothing to add */
1036 if (state < VTIME_SYS)
1037 continue;
1038
1039 delta = vtime_delta(vtime);
1040
1041 /*
1042 * Task runs either in user (including guest) or kernel space,
1043 * add pending nohz time to the right place.
1044 */
1045 if (state == VTIME_SYS) {
1046 cpustat[CPUTIME_SYSTEM] += vtime->stime + delta;
1047 } else if (state == VTIME_USER) {
1048 if (task_nice(tsk) > 0)
1049 cpustat[CPUTIME_NICE] += vtime->utime + delta;
1050 else
1051 cpustat[CPUTIME_USER] += vtime->utime + delta;
1052 } else {
1053 WARN_ON_ONCE(state != VTIME_GUEST);
1054 if (task_nice(tsk) > 0) {
1055 cpustat[CPUTIME_GUEST_NICE] += vtime->gtime + delta;
1056 cpustat[CPUTIME_NICE] += vtime->gtime + delta;
1057 } else {
1058 cpustat[CPUTIME_GUEST] += vtime->gtime + delta;
1059 cpustat[CPUTIME_USER] += vtime->gtime + delta;
1060 }
1061 }
1062 } while (read_seqcount_retry(&vtime->seqcount, seq));
1063
1064 return 0;
1065}
1066
1067void kcpustat_cpu_fetch(struct kernel_cpustat *dst, int cpu)
1068{
1069 const struct kernel_cpustat *src = &kcpustat_cpu(cpu);
1070 struct rq *rq;
1071 int err;
1072
1073 if (!vtime_accounting_enabled_cpu(cpu)) {
1074 *dst = *src;
1075 return;
1076 }
1077
1078 rq = cpu_rq(cpu);
1079
1080 for (;;) {
1081 struct task_struct *curr;
1082
1083 rcu_read_lock();
1084 curr = rcu_dereference(rq->curr);
1085 if (WARN_ON_ONCE(!curr)) {
1086 rcu_read_unlock();
1087 *dst = *src;
1088 return;
1089 }
1090
1091 err = kcpustat_cpu_fetch_vtime(dst, src, curr, cpu);
1092 rcu_read_unlock();
1093
1094 if (!err)
1095 return;
1096
1097 cpu_relax();
1098 }
1099}
1100EXPORT_SYMBOL_GPL(kcpustat_cpu_fetch);
1101
1102#endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */