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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#include <linux/export.h>
2#include <linux/sched.h>
3#include <linux/tsacct_kern.h>
4#include <linux/kernel_stat.h>
5#include <linux/static_key.h>
6#include <linux/context_tracking.h>
7#include "sched.h"
8
9
10#ifdef CONFIG_IRQ_TIME_ACCOUNTING
11
12/*
13 * There are no locks covering percpu hardirq/softirq time.
14 * They are only modified in vtime_account, on corresponding CPU
15 * with interrupts disabled. So, writes are safe.
16 * They are read and saved off onto struct rq in update_rq_clock().
17 * This may result in other CPU reading this CPU's irq time and can
18 * race with irq/vtime_account on this CPU. We would either get old
19 * or new value with a side effect of accounting a slice of irq time to wrong
20 * task when irq is in progress while we read rq->clock. That is a worthy
21 * compromise in place of having locks on each irq in account_system_time.
22 */
23DEFINE_PER_CPU(u64, cpu_hardirq_time);
24DEFINE_PER_CPU(u64, cpu_softirq_time);
25
26static DEFINE_PER_CPU(u64, irq_start_time);
27static int sched_clock_irqtime;
28
29void enable_sched_clock_irqtime(void)
30{
31 sched_clock_irqtime = 1;
32}
33
34void disable_sched_clock_irqtime(void)
35{
36 sched_clock_irqtime = 0;
37}
38
39#ifndef CONFIG_64BIT
40DEFINE_PER_CPU(seqcount_t, irq_time_seq);
41#endif /* CONFIG_64BIT */
42
43/*
44 * Called before incrementing preempt_count on {soft,}irq_enter
45 * and before decrementing preempt_count on {soft,}irq_exit.
46 */
47void irqtime_account_irq(struct task_struct *curr)
48{
49 unsigned long flags;
50 s64 delta;
51 int cpu;
52
53 if (!sched_clock_irqtime)
54 return;
55
56 local_irq_save(flags);
57
58 cpu = smp_processor_id();
59 delta = sched_clock_cpu(cpu) - __this_cpu_read(irq_start_time);
60 __this_cpu_add(irq_start_time, delta);
61
62 irq_time_write_begin();
63 /*
64 * We do not account for softirq time from ksoftirqd here.
65 * We want to continue accounting softirq time to ksoftirqd thread
66 * in that case, so as not to confuse scheduler with a special task
67 * that do not consume any time, but still wants to run.
68 */
69 if (hardirq_count())
70 __this_cpu_add(cpu_hardirq_time, delta);
71 else if (in_serving_softirq() && curr != this_cpu_ksoftirqd())
72 __this_cpu_add(cpu_softirq_time, delta);
73
74 irq_time_write_end();
75 local_irq_restore(flags);
76}
77EXPORT_SYMBOL_GPL(irqtime_account_irq);
78
79static int irqtime_account_hi_update(void)
80{
81 u64 *cpustat = kcpustat_this_cpu->cpustat;
82 unsigned long flags;
83 u64 latest_ns;
84 int ret = 0;
85
86 local_irq_save(flags);
87 latest_ns = this_cpu_read(cpu_hardirq_time);
88 if (nsecs_to_cputime64(latest_ns) > cpustat[CPUTIME_IRQ])
89 ret = 1;
90 local_irq_restore(flags);
91 return ret;
92}
93
94static int irqtime_account_si_update(void)
95{
96 u64 *cpustat = kcpustat_this_cpu->cpustat;
97 unsigned long flags;
98 u64 latest_ns;
99 int ret = 0;
100
101 local_irq_save(flags);
102 latest_ns = this_cpu_read(cpu_softirq_time);
103 if (nsecs_to_cputime64(latest_ns) > cpustat[CPUTIME_SOFTIRQ])
104 ret = 1;
105 local_irq_restore(flags);
106 return ret;
107}
108
109#else /* CONFIG_IRQ_TIME_ACCOUNTING */
110
111#define sched_clock_irqtime (0)
112
113#endif /* !CONFIG_IRQ_TIME_ACCOUNTING */
114
115static inline void task_group_account_field(struct task_struct *p, int index,
116 u64 tmp)
117{
118 /*
119 * Since all updates are sure to touch the root cgroup, we
120 * get ourselves ahead and touch it first. If the root cgroup
121 * is the only cgroup, then nothing else should be necessary.
122 *
123 */
124 __this_cpu_add(kernel_cpustat.cpustat[index], tmp);
125
126 cpuacct_account_field(p, index, tmp);
127}
128
129/*
130 * Account user cpu time to a process.
131 * @p: the process that the cpu time gets accounted to
132 * @cputime: the cpu time spent in user space since the last update
133 * @cputime_scaled: cputime scaled by cpu frequency
134 */
135void account_user_time(struct task_struct *p, cputime_t cputime,
136 cputime_t cputime_scaled)
137{
138 int index;
139
140 /* Add user time to process. */
141 p->utime += cputime;
142 p->utimescaled += cputime_scaled;
143 account_group_user_time(p, cputime);
144
145 index = (task_nice(p) > 0) ? CPUTIME_NICE : CPUTIME_USER;
146
147 /* Add user time to cpustat. */
148 task_group_account_field(p, index, (__force u64) cputime);
149
150 /* Account for user time used */
151 acct_account_cputime(p);
152}
153
154/*
155 * Account guest cpu time to a process.
156 * @p: the process that the cpu time gets accounted to
157 * @cputime: the cpu time spent in virtual machine since the last update
158 * @cputime_scaled: cputime scaled by cpu frequency
159 */
160static void account_guest_time(struct task_struct *p, cputime_t cputime,
161 cputime_t cputime_scaled)
162{
163 u64 *cpustat = kcpustat_this_cpu->cpustat;
164
165 /* Add guest time to process. */
166 p->utime += cputime;
167 p->utimescaled += cputime_scaled;
168 account_group_user_time(p, cputime);
169 p->gtime += cputime;
170
171 /* Add guest time to cpustat. */
172 if (task_nice(p) > 0) {
173 cpustat[CPUTIME_NICE] += (__force u64) cputime;
174 cpustat[CPUTIME_GUEST_NICE] += (__force u64) cputime;
175 } else {
176 cpustat[CPUTIME_USER] += (__force u64) cputime;
177 cpustat[CPUTIME_GUEST] += (__force u64) cputime;
178 }
179}
180
181/*
182 * Account system cpu time to a process and desired cpustat field
183 * @p: the process that the cpu time gets accounted to
184 * @cputime: the cpu time spent in kernel space since the last update
185 * @cputime_scaled: cputime scaled by cpu frequency
186 * @target_cputime64: pointer to cpustat field that has to be updated
187 */
188static inline
189void __account_system_time(struct task_struct *p, cputime_t cputime,
190 cputime_t cputime_scaled, int index)
191{
192 /* Add system time to process. */
193 p->stime += cputime;
194 p->stimescaled += cputime_scaled;
195 account_group_system_time(p, cputime);
196
197 /* Add system time to cpustat. */
198 task_group_account_field(p, index, (__force u64) cputime);
199
200 /* Account for system time used */
201 acct_account_cputime(p);
202}
203
204/*
205 * Account system cpu time to a process.
206 * @p: the process that the cpu time gets accounted to
207 * @hardirq_offset: the offset to subtract from hardirq_count()
208 * @cputime: the cpu time spent in kernel space since the last update
209 * @cputime_scaled: cputime scaled by cpu frequency
210 */
211void account_system_time(struct task_struct *p, int hardirq_offset,
212 cputime_t cputime, cputime_t cputime_scaled)
213{
214 int index;
215
216 if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) {
217 account_guest_time(p, cputime, cputime_scaled);
218 return;
219 }
220
221 if (hardirq_count() - hardirq_offset)
222 index = CPUTIME_IRQ;
223 else if (in_serving_softirq())
224 index = CPUTIME_SOFTIRQ;
225 else
226 index = CPUTIME_SYSTEM;
227
228 __account_system_time(p, cputime, cputime_scaled, index);
229}
230
231/*
232 * Account for involuntary wait time.
233 * @cputime: the cpu time spent in involuntary wait
234 */
235void account_steal_time(cputime_t cputime)
236{
237 u64 *cpustat = kcpustat_this_cpu->cpustat;
238
239 cpustat[CPUTIME_STEAL] += (__force u64) cputime;
240}
241
242/*
243 * Account for idle time.
244 * @cputime: the cpu time spent in idle wait
245 */
246void account_idle_time(cputime_t cputime)
247{
248 u64 *cpustat = kcpustat_this_cpu->cpustat;
249 struct rq *rq = this_rq();
250
251 if (atomic_read(&rq->nr_iowait) > 0)
252 cpustat[CPUTIME_IOWAIT] += (__force u64) cputime;
253 else
254 cpustat[CPUTIME_IDLE] += (__force u64) cputime;
255}
256
257static __always_inline bool steal_account_process_tick(void)
258{
259#ifdef CONFIG_PARAVIRT
260 if (static_key_false(¶virt_steal_enabled)) {
261 u64 steal;
262 cputime_t steal_ct;
263
264 steal = paravirt_steal_clock(smp_processor_id());
265 steal -= this_rq()->prev_steal_time;
266
267 /*
268 * cputime_t may be less precise than nsecs (eg: if it's
269 * based on jiffies). Lets cast the result to cputime
270 * granularity and account the rest on the next rounds.
271 */
272 steal_ct = nsecs_to_cputime(steal);
273 this_rq()->prev_steal_time += cputime_to_nsecs(steal_ct);
274
275 account_steal_time(steal_ct);
276 return steal_ct;
277 }
278#endif
279 return false;
280}
281
282/*
283 * Accumulate raw cputime values of dead tasks (sig->[us]time) and live
284 * tasks (sum on group iteration) belonging to @tsk's group.
285 */
286void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
287{
288 struct signal_struct *sig = tsk->signal;
289 cputime_t utime, stime;
290 struct task_struct *t;
291
292 times->utime = sig->utime;
293 times->stime = sig->stime;
294 times->sum_exec_runtime = sig->sum_sched_runtime;
295
296 rcu_read_lock();
297 /* make sure we can trust tsk->thread_group list */
298 if (!likely(pid_alive(tsk)))
299 goto out;
300
301 t = tsk;
302 do {
303 task_cputime(t, &utime, &stime);
304 times->utime += utime;
305 times->stime += stime;
306 times->sum_exec_runtime += task_sched_runtime(t);
307 } while_each_thread(tsk, t);
308out:
309 rcu_read_unlock();
310}
311
312#ifdef CONFIG_IRQ_TIME_ACCOUNTING
313/*
314 * Account a tick to a process and cpustat
315 * @p: the process that the cpu time gets accounted to
316 * @user_tick: is the tick from userspace
317 * @rq: the pointer to rq
318 *
319 * Tick demultiplexing follows the order
320 * - pending hardirq update
321 * - pending softirq update
322 * - user_time
323 * - idle_time
324 * - system time
325 * - check for guest_time
326 * - else account as system_time
327 *
328 * Check for hardirq is done both for system and user time as there is
329 * no timer going off while we are on hardirq and hence we may never get an
330 * opportunity to update it solely in system time.
331 * p->stime and friends are only updated on system time and not on irq
332 * softirq as those do not count in task exec_runtime any more.
333 */
334static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
335 struct rq *rq, int ticks)
336{
337 cputime_t scaled = cputime_to_scaled(cputime_one_jiffy);
338 u64 cputime = (__force u64) cputime_one_jiffy;
339 u64 *cpustat = kcpustat_this_cpu->cpustat;
340
341 if (steal_account_process_tick())
342 return;
343
344 cputime *= ticks;
345 scaled *= ticks;
346
347 if (irqtime_account_hi_update()) {
348 cpustat[CPUTIME_IRQ] += cputime;
349 } else if (irqtime_account_si_update()) {
350 cpustat[CPUTIME_SOFTIRQ] += cputime;
351 } else if (this_cpu_ksoftirqd() == p) {
352 /*
353 * ksoftirqd time do not get accounted in cpu_softirq_time.
354 * So, we have to handle it separately here.
355 * Also, p->stime needs to be updated for ksoftirqd.
356 */
357 __account_system_time(p, cputime, scaled, CPUTIME_SOFTIRQ);
358 } else if (user_tick) {
359 account_user_time(p, cputime, scaled);
360 } else if (p == rq->idle) {
361 account_idle_time(cputime);
362 } else if (p->flags & PF_VCPU) { /* System time or guest time */
363 account_guest_time(p, cputime, scaled);
364 } else {
365 __account_system_time(p, cputime, scaled, CPUTIME_SYSTEM);
366 }
367}
368
369static void irqtime_account_idle_ticks(int ticks)
370{
371 struct rq *rq = this_rq();
372
373 irqtime_account_process_tick(current, 0, rq, ticks);
374}
375#else /* CONFIG_IRQ_TIME_ACCOUNTING */
376static inline void irqtime_account_idle_ticks(int ticks) {}
377static inline void irqtime_account_process_tick(struct task_struct *p, int user_tick,
378 struct rq *rq, int nr_ticks) {}
379#endif /* CONFIG_IRQ_TIME_ACCOUNTING */
380
381/*
382 * Use precise platform statistics if available:
383 */
384#ifdef CONFIG_VIRT_CPU_ACCOUNTING
385
386#ifndef __ARCH_HAS_VTIME_TASK_SWITCH
387void vtime_common_task_switch(struct task_struct *prev)
388{
389 if (is_idle_task(prev))
390 vtime_account_idle(prev);
391 else
392 vtime_account_system(prev);
393
394#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
395 vtime_account_user(prev);
396#endif
397 arch_vtime_task_switch(prev);
398}
399#endif
400
401/*
402 * Archs that account the whole time spent in the idle task
403 * (outside irq) as idle time can rely on this and just implement
404 * vtime_account_system() and vtime_account_idle(). Archs that
405 * have other meaning of the idle time (s390 only includes the
406 * time spent by the CPU when it's in low power mode) must override
407 * vtime_account().
408 */
409#ifndef __ARCH_HAS_VTIME_ACCOUNT
410void vtime_common_account_irq_enter(struct task_struct *tsk)
411{
412 if (!in_interrupt()) {
413 /*
414 * If we interrupted user, context_tracking_in_user()
415 * is 1 because the context tracking don't hook
416 * on irq entry/exit. This way we know if
417 * we need to flush user time on kernel entry.
418 */
419 if (context_tracking_in_user()) {
420 vtime_account_user(tsk);
421 return;
422 }
423
424 if (is_idle_task(tsk)) {
425 vtime_account_idle(tsk);
426 return;
427 }
428 }
429 vtime_account_system(tsk);
430}
431EXPORT_SYMBOL_GPL(vtime_common_account_irq_enter);
432#endif /* __ARCH_HAS_VTIME_ACCOUNT */
433#endif /* CONFIG_VIRT_CPU_ACCOUNTING */
434
435
436#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
437void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
438{
439 *ut = p->utime;
440 *st = p->stime;
441}
442
443void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
444{
445 struct task_cputime cputime;
446
447 thread_group_cputime(p, &cputime);
448
449 *ut = cputime.utime;
450 *st = cputime.stime;
451}
452#else /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
453/*
454 * Account a single tick of cpu time.
455 * @p: the process that the cpu time gets accounted to
456 * @user_tick: indicates if the tick is a user or a system tick
457 */
458void account_process_tick(struct task_struct *p, int user_tick)
459{
460 cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
461 struct rq *rq = this_rq();
462
463 if (vtime_accounting_enabled())
464 return;
465
466 if (sched_clock_irqtime) {
467 irqtime_account_process_tick(p, user_tick, rq, 1);
468 return;
469 }
470
471 if (steal_account_process_tick())
472 return;
473
474 if (user_tick)
475 account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);
476 else if ((p != rq->idle) || (irq_count() != HARDIRQ_OFFSET))
477 account_system_time(p, HARDIRQ_OFFSET, cputime_one_jiffy,
478 one_jiffy_scaled);
479 else
480 account_idle_time(cputime_one_jiffy);
481}
482
483/*
484 * Account multiple ticks of steal time.
485 * @p: the process from which the cpu time has been stolen
486 * @ticks: number of stolen ticks
487 */
488void account_steal_ticks(unsigned long ticks)
489{
490 account_steal_time(jiffies_to_cputime(ticks));
491}
492
493/*
494 * Account multiple ticks of idle time.
495 * @ticks: number of stolen ticks
496 */
497void account_idle_ticks(unsigned long ticks)
498{
499
500 if (sched_clock_irqtime) {
501 irqtime_account_idle_ticks(ticks);
502 return;
503 }
504
505 account_idle_time(jiffies_to_cputime(ticks));
506}
507
508/*
509 * Perform (stime * rtime) / total, but avoid multiplication overflow by
510 * loosing precision when the numbers are big.
511 */
512static cputime_t scale_stime(u64 stime, u64 rtime, u64 total)
513{
514 u64 scaled;
515
516 for (;;) {
517 /* Make sure "rtime" is the bigger of stime/rtime */
518 if (stime > rtime)
519 swap(rtime, stime);
520
521 /* Make sure 'total' fits in 32 bits */
522 if (total >> 32)
523 goto drop_precision;
524
525 /* Does rtime (and thus stime) fit in 32 bits? */
526 if (!(rtime >> 32))
527 break;
528
529 /* Can we just balance rtime/stime rather than dropping bits? */
530 if (stime >> 31)
531 goto drop_precision;
532
533 /* We can grow stime and shrink rtime and try to make them both fit */
534 stime <<= 1;
535 rtime >>= 1;
536 continue;
537
538drop_precision:
539 /* We drop from rtime, it has more bits than stime */
540 rtime >>= 1;
541 total >>= 1;
542 }
543
544 /*
545 * Make sure gcc understands that this is a 32x32->64 multiply,
546 * followed by a 64/32->64 divide.
547 */
548 scaled = div_u64((u64) (u32) stime * (u64) (u32) rtime, (u32)total);
549 return (__force cputime_t) scaled;
550}
551
552/*
553 * Adjust tick based cputime random precision against scheduler
554 * runtime accounting.
555 */
556static void cputime_adjust(struct task_cputime *curr,
557 struct cputime *prev,
558 cputime_t *ut, cputime_t *st)
559{
560 cputime_t rtime, stime, utime;
561
562 /*
563 * Tick based cputime accounting depend on random scheduling
564 * timeslices of a task to be interrupted or not by the timer.
565 * Depending on these circumstances, the number of these interrupts
566 * may be over or under-optimistic, matching the real user and system
567 * cputime with a variable precision.
568 *
569 * Fix this by scaling these tick based values against the total
570 * runtime accounted by the CFS scheduler.
571 */
572 rtime = nsecs_to_cputime(curr->sum_exec_runtime);
573
574 /*
575 * Update userspace visible utime/stime values only if actual execution
576 * time is bigger than already exported. Note that can happen, that we
577 * provided bigger values due to scaling inaccuracy on big numbers.
578 */
579 if (prev->stime + prev->utime >= rtime)
580 goto out;
581
582 stime = curr->stime;
583 utime = curr->utime;
584
585 if (utime == 0) {
586 stime = rtime;
587 } else if (stime == 0) {
588 utime = rtime;
589 } else {
590 cputime_t total = stime + utime;
591
592 stime = scale_stime((__force u64)stime,
593 (__force u64)rtime, (__force u64)total);
594 utime = rtime - stime;
595 }
596
597 /*
598 * If the tick based count grows faster than the scheduler one,
599 * the result of the scaling may go backward.
600 * Let's enforce monotonicity.
601 */
602 prev->stime = max(prev->stime, stime);
603 prev->utime = max(prev->utime, utime);
604
605out:
606 *ut = prev->utime;
607 *st = prev->stime;
608}
609
610void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
611{
612 struct task_cputime cputime = {
613 .sum_exec_runtime = p->se.sum_exec_runtime,
614 };
615
616 task_cputime(p, &cputime.utime, &cputime.stime);
617 cputime_adjust(&cputime, &p->prev_cputime, ut, st);
618}
619
620/*
621 * Must be called with siglock held.
622 */
623void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
624{
625 struct task_cputime cputime;
626
627 thread_group_cputime(p, &cputime);
628 cputime_adjust(&cputime, &p->signal->prev_cputime, ut, st);
629}
630#endif /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
631
632#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
633static unsigned long long vtime_delta(struct task_struct *tsk)
634{
635 unsigned long long clock;
636
637 clock = local_clock();
638 if (clock < tsk->vtime_snap)
639 return 0;
640
641 return clock - tsk->vtime_snap;
642}
643
644static cputime_t get_vtime_delta(struct task_struct *tsk)
645{
646 unsigned long long delta = vtime_delta(tsk);
647
648 WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_SLEEPING);
649 tsk->vtime_snap += delta;
650
651 /* CHECKME: always safe to convert nsecs to cputime? */
652 return nsecs_to_cputime(delta);
653}
654
655static void __vtime_account_system(struct task_struct *tsk)
656{
657 cputime_t delta_cpu = get_vtime_delta(tsk);
658
659 account_system_time(tsk, irq_count(), delta_cpu, cputime_to_scaled(delta_cpu));
660}
661
662void vtime_account_system(struct task_struct *tsk)
663{
664 write_seqlock(&tsk->vtime_seqlock);
665 __vtime_account_system(tsk);
666 write_sequnlock(&tsk->vtime_seqlock);
667}
668
669void vtime_gen_account_irq_exit(struct task_struct *tsk)
670{
671 write_seqlock(&tsk->vtime_seqlock);
672 __vtime_account_system(tsk);
673 if (context_tracking_in_user())
674 tsk->vtime_snap_whence = VTIME_USER;
675 write_sequnlock(&tsk->vtime_seqlock);
676}
677
678void vtime_account_user(struct task_struct *tsk)
679{
680 cputime_t delta_cpu;
681
682 write_seqlock(&tsk->vtime_seqlock);
683 delta_cpu = get_vtime_delta(tsk);
684 tsk->vtime_snap_whence = VTIME_SYS;
685 account_user_time(tsk, delta_cpu, cputime_to_scaled(delta_cpu));
686 write_sequnlock(&tsk->vtime_seqlock);
687}
688
689void vtime_user_enter(struct task_struct *tsk)
690{
691 write_seqlock(&tsk->vtime_seqlock);
692 __vtime_account_system(tsk);
693 tsk->vtime_snap_whence = VTIME_USER;
694 write_sequnlock(&tsk->vtime_seqlock);
695}
696
697void vtime_guest_enter(struct task_struct *tsk)
698{
699 /*
700 * The flags must be updated under the lock with
701 * the vtime_snap flush and update.
702 * That enforces a right ordering and update sequence
703 * synchronization against the reader (task_gtime())
704 * that can thus safely catch up with a tickless delta.
705 */
706 write_seqlock(&tsk->vtime_seqlock);
707 __vtime_account_system(tsk);
708 current->flags |= PF_VCPU;
709 write_sequnlock(&tsk->vtime_seqlock);
710}
711EXPORT_SYMBOL_GPL(vtime_guest_enter);
712
713void vtime_guest_exit(struct task_struct *tsk)
714{
715 write_seqlock(&tsk->vtime_seqlock);
716 __vtime_account_system(tsk);
717 current->flags &= ~PF_VCPU;
718 write_sequnlock(&tsk->vtime_seqlock);
719}
720EXPORT_SYMBOL_GPL(vtime_guest_exit);
721
722void vtime_account_idle(struct task_struct *tsk)
723{
724 cputime_t delta_cpu = get_vtime_delta(tsk);
725
726 account_idle_time(delta_cpu);
727}
728
729void arch_vtime_task_switch(struct task_struct *prev)
730{
731 write_seqlock(&prev->vtime_seqlock);
732 prev->vtime_snap_whence = VTIME_SLEEPING;
733 write_sequnlock(&prev->vtime_seqlock);
734
735 write_seqlock(¤t->vtime_seqlock);
736 current->vtime_snap_whence = VTIME_SYS;
737 current->vtime_snap = sched_clock_cpu(smp_processor_id());
738 write_sequnlock(¤t->vtime_seqlock);
739}
740
741void vtime_init_idle(struct task_struct *t, int cpu)
742{
743 unsigned long flags;
744
745 write_seqlock_irqsave(&t->vtime_seqlock, flags);
746 t->vtime_snap_whence = VTIME_SYS;
747 t->vtime_snap = sched_clock_cpu(cpu);
748 write_sequnlock_irqrestore(&t->vtime_seqlock, flags);
749}
750
751cputime_t task_gtime(struct task_struct *t)
752{
753 unsigned int seq;
754 cputime_t gtime;
755
756 do {
757 seq = read_seqbegin(&t->vtime_seqlock);
758
759 gtime = t->gtime;
760 if (t->flags & PF_VCPU)
761 gtime += vtime_delta(t);
762
763 } while (read_seqretry(&t->vtime_seqlock, seq));
764
765 return gtime;
766}
767
768/*
769 * Fetch cputime raw values from fields of task_struct and
770 * add up the pending nohz execution time since the last
771 * cputime snapshot.
772 */
773static void
774fetch_task_cputime(struct task_struct *t,
775 cputime_t *u_dst, cputime_t *s_dst,
776 cputime_t *u_src, cputime_t *s_src,
777 cputime_t *udelta, cputime_t *sdelta)
778{
779 unsigned int seq;
780 unsigned long long delta;
781
782 do {
783 *udelta = 0;
784 *sdelta = 0;
785
786 seq = read_seqbegin(&t->vtime_seqlock);
787
788 if (u_dst)
789 *u_dst = *u_src;
790 if (s_dst)
791 *s_dst = *s_src;
792
793 /* Task is sleeping, nothing to add */
794 if (t->vtime_snap_whence == VTIME_SLEEPING ||
795 is_idle_task(t))
796 continue;
797
798 delta = vtime_delta(t);
799
800 /*
801 * Task runs either in user or kernel space, add pending nohz time to
802 * the right place.
803 */
804 if (t->vtime_snap_whence == VTIME_USER || t->flags & PF_VCPU) {
805 *udelta = delta;
806 } else {
807 if (t->vtime_snap_whence == VTIME_SYS)
808 *sdelta = delta;
809 }
810 } while (read_seqretry(&t->vtime_seqlock, seq));
811}
812
813
814void task_cputime(struct task_struct *t, cputime_t *utime, cputime_t *stime)
815{
816 cputime_t udelta, sdelta;
817
818 fetch_task_cputime(t, utime, stime, &t->utime,
819 &t->stime, &udelta, &sdelta);
820 if (utime)
821 *utime += udelta;
822 if (stime)
823 *stime += sdelta;
824}
825
826void task_cputime_scaled(struct task_struct *t,
827 cputime_t *utimescaled, cputime_t *stimescaled)
828{
829 cputime_t udelta, sdelta;
830
831 fetch_task_cputime(t, utimescaled, stimescaled,
832 &t->utimescaled, &t->stimescaled, &udelta, &sdelta);
833 if (utimescaled)
834 *utimescaled += cputime_to_scaled(udelta);
835 if (stimescaled)
836 *stimescaled += cputime_to_scaled(sdelta);
837}
838#endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */