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