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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_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 */