kernel/sched/cputime.c

   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  */
  23 DEFINE_PER_CPU(u64, cpu_hardirq_time);
  24 DEFINE_PER_CPU(u64, cpu_softirq_time);
  25
  26 static DEFINE_PER_CPU(u64, irq_start_time);
  27 static int sched_clock_irqtime;
  28
  29 void enable_sched_clock_irqtime(void)
  30 {
  31         sched_clock_irqtime = 1;
  32 }
  33
  34 void disable_sched_clock_irqtime(void)
  35 {
  36         sched_clock_irqtime = 0;
  37 }
  38
  39 #ifndef CONFIG_64BIT
  40 DEFINE_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  */
  47 void 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 }
  77 EXPORT_SYMBOL_GPL(irqtime_account_irq);
  78
  79 static 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
  94 static 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
 115 static 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         __get_cpu_var(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  */
 135 void 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  */
 160 static 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  */
 188 static inline
 189 void __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  */
 211 void 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  */
 235 void 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  */
 246 void 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
 257 static __always_inline bool steal_account_process_tick(void)
 258 {
 259 #ifdef CONFIG_PARAVIRT
 260         if (static_key_false(&paravirt_steal_enabled)) {
 261                 u64 steal, st = 0;
 262
 263                 steal = paravirt_steal_clock(smp_processor_id());
 264                 steal -= this_rq()->prev_steal_time;
 265
 266                 st = steal_ticks(steal);
 267                 this_rq()->prev_steal_time += st * TICK_NSEC;
 268
 269                 account_steal_time(st);
 270                 return st;
 271         }
 272 #endif
 273         return false;
 274 }
 275
 276 /*
 277  * Accumulate raw cputime values of dead tasks (sig->[us]time) and live
 278  * tasks (sum on group iteration) belonging to @tsk's group.
 279  */
 280 void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
 281 {
 282         struct signal_struct *sig = tsk->signal;
 283         cputime_t utime, stime;
 284         struct task_struct *t;
 285
 286         times->utime = sig->utime;
 287         times->stime = sig->stime;
 288         times->sum_exec_runtime = sig->sum_sched_runtime;
 289
 290         rcu_read_lock();
 291         /* make sure we can trust tsk->thread_group list */
 292         if (!likely(pid_alive(tsk)))
 293                 goto out;
 294
 295         t = tsk;
 296         do {
 297                 task_cputime(tsk, &utime, &stime);
 298                 times->utime += utime;
 299                 times->stime += stime;
 300                 times->sum_exec_runtime += task_sched_runtime(t);
 301         } while_each_thread(tsk, t);
 302 out:
 303         rcu_read_unlock();
 304 }
 305
 306 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
 307 /*
 308  * Account a tick to a process and cpustat
 309  * @p: the process that the cpu time gets accounted to
 310  * @user_tick: is the tick from userspace
 311  * @rq: the pointer to rq
 312  *
 313  * Tick demultiplexing follows the order
 314  * - pending hardirq update
 315  * - pending softirq update
 316  * - user_time
 317  * - idle_time
 318  * - system time
 319  *   - check for guest_time
 320  *   - else account as system_time
 321  *
 322  * Check for hardirq is done both for system and user time as there is
 323  * no timer going off while we are on hardirq and hence we may never get an
 324  * opportunity to update it solely in system time.
 325  * p->stime and friends are only updated on system time and not on irq
 326  * softirq as those do not count in task exec_runtime any more.
 327  */
 328 static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
 329                                                 struct rq *rq)
 330 {
 331         cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
 332         u64 *cpustat = kcpustat_this_cpu->cpustat;
 333
 334         if (steal_account_process_tick())
 335                 return;
 336
 337         if (irqtime_account_hi_update()) {
 338                 cpustat[CPUTIME_IRQ] += (__force u64) cputime_one_jiffy;
 339         } else if (irqtime_account_si_update()) {
 340                 cpustat[CPUTIME_SOFTIRQ] += (__force u64) cputime_one_jiffy;
 341         } else if (this_cpu_ksoftirqd() == p) {
 342                 /*
 343                  * ksoftirqd time do not get accounted in cpu_softirq_time.
 344                  * So, we have to handle it separately here.
 345                  * Also, p->stime needs to be updated for ksoftirqd.
 346                  */
 347                 __account_system_time(p, cputime_one_jiffy, one_jiffy_scaled,
 348                                         CPUTIME_SOFTIRQ);
 349         } else if (user_tick) {
 350                 account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);
 351         } else if (p == rq->idle) {
 352                 account_idle_time(cputime_one_jiffy);
 353         } else if (p->flags & PF_VCPU) { /* System time or guest time */
 354                 account_guest_time(p, cputime_one_jiffy, one_jiffy_scaled);
 355         } else {
 356                 __account_system_time(p, cputime_one_jiffy, one_jiffy_scaled,
 357                                         CPUTIME_SYSTEM);
 358         }
 359 }
 360
 361 static void irqtime_account_idle_ticks(int ticks)
 362 {
 363         int i;
 364         struct rq *rq = this_rq();
 365
 366         for (i = 0; i < ticks; i++)
 367                 irqtime_account_process_tick(current, 0, rq);
 368 }
 369 #else /* CONFIG_IRQ_TIME_ACCOUNTING */
 370 static inline void irqtime_account_idle_ticks(int ticks) {}
 371 static inline void irqtime_account_process_tick(struct task_struct *p, int user_tick,
 372                                                 struct rq *rq) {}
 373 #endif /* CONFIG_IRQ_TIME_ACCOUNTING */
 374
 375 /*
 376  * Use precise platform statistics if available:
 377  */
 378 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
 379
 380 #ifndef __ARCH_HAS_VTIME_TASK_SWITCH
 381 void vtime_task_switch(struct task_struct *prev)
 382 {
 383         if (!vtime_accounting_enabled())
 384                 return;
 385
 386         if (is_idle_task(prev))
 387                 vtime_account_idle(prev);
 388         else
 389                 vtime_account_system(prev);
 390
 391 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
 392         vtime_account_user(prev);
 393 #endif
 394         arch_vtime_task_switch(prev);
 395 }
 396 #endif
 397
 398 /*
 399  * Archs that account the whole time spent in the idle task
 400  * (outside irq) as idle time can rely on this and just implement
 401  * vtime_account_system() and vtime_account_idle(). Archs that
 402  * have other meaning of the idle time (s390 only includes the
 403  * time spent by the CPU when it's in low power mode) must override
 404  * vtime_account().
 405  */
 406 #ifndef __ARCH_HAS_VTIME_ACCOUNT
 407 void vtime_account_irq_enter(struct task_struct *tsk)
 408 {
 409         if (!vtime_accounting_enabled())
 410                 return;
 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 }
 431 EXPORT_SYMBOL_GPL(vtime_account_irq_enter);
 432 #endif /* __ARCH_HAS_VTIME_ACCOUNT */
 433 #endif /* CONFIG_VIRT_CPU_ACCOUNTING */
 434
 435
 436 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
 437 void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
 438 {
 439         *ut = p->utime;
 440         *st = p->stime;
 441 }
 442
 443 void 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  */
 458 void 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);
 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  */
 488 void 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  */
 497 void 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 with reduced chances
 510  * of multiplication overflows by using smaller factors
 511  * like quotient and remainders of divisions between
 512  * rtime and total.
 513  */
 514 static cputime_t scale_stime(u64 stime, u64 rtime, u64 total)
 515 {
 516         u64 rem, res, scaled;
 517
 518         if (rtime >= total) {
 519                 /*
 520                  * Scale up to rtime / total then add
 521                  * the remainder scaled to stime / total.
 522                  */
 523                 res = div64_u64_rem(rtime, total, &rem);
 524                 scaled = stime * res;
 525                 scaled += div64_u64(stime * rem, total);
 526         } else {
 527                 /*
 528                  * Same in reverse: scale down to total / rtime
 529                  * then substract that result scaled to
 530                  * to the remaining part.
 531                  */
 532                 res = div64_u64_rem(total, rtime, &rem);
 533                 scaled = div64_u64(stime, res);
 534                 scaled -= div64_u64(scaled * rem, total);
 535         }
 536
 537         return (__force cputime_t) scaled;
 538 }
 539
 540 /*
 541  * Adjust tick based cputime random precision against scheduler
 542  * runtime accounting.
 543  */
 544 static void cputime_adjust(struct task_cputime *curr,
 545                            struct cputime *prev,
 546                            cputime_t *ut, cputime_t *st)
 547 {
 548         cputime_t rtime, stime, total;
 549
 550         if (vtime_accounting_enabled()) {
 551                 *ut = curr->utime;
 552                 *st = curr->stime;
 553                 return;
 554         }
 555
 556         stime = curr->stime;
 557         total = stime + curr->utime;
 558
 559         /*
 560          * Tick based cputime accounting depend on random scheduling
 561          * timeslices of a task to be interrupted or not by the timer.
 562          * Depending on these circumstances, the number of these interrupts
 563          * may be over or under-optimistic, matching the real user and system
 564          * cputime with a variable precision.
 565          *
 566          * Fix this by scaling these tick based values against the total
 567          * runtime accounted by the CFS scheduler.
 568          */
 569         rtime = nsecs_to_cputime(curr->sum_exec_runtime);
 570
 571         if (!rtime) {
 572                 stime = 0;
 573         } else if (!total) {
 574                 stime = rtime;
 575         } else {
 576                 stime = scale_stime((__force u64)stime,
 577                                     (__force u64)rtime, (__force u64)total);
 578         }
 579
 580         /*
 581          * If the tick based count grows faster than the scheduler one,
 582          * the result of the scaling may go backward.
 583          * Let's enforce monotonicity.
 584          */
 585         prev->stime = max(prev->stime, stime);
 586         prev->utime = max(prev->utime, rtime - prev->stime);
 587
 588         *ut = prev->utime;
 589         *st = prev->stime;
 590 }
 591
 592 void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
 593 {
 594         struct task_cputime cputime = {
 595                 .sum_exec_runtime = p->se.sum_exec_runtime,
 596         };
 597
 598         task_cputime(p, &cputime.utime, &cputime.stime);
 599         cputime_adjust(&cputime, &p->prev_cputime, ut, st);
 600 }
 601
 602 /*
 603  * Must be called with siglock held.
 604  */
 605 void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
 606 {
 607         struct task_cputime cputime;
 608
 609         thread_group_cputime(p, &cputime);
 610         cputime_adjust(&cputime, &p->signal->prev_cputime, ut, st);
 611 }
 612 #endif /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
 613
 614 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
 615 static unsigned long long vtime_delta(struct task_struct *tsk)
 616 {
 617         unsigned long long clock;
 618
 619         clock = local_clock();
 620         if (clock < tsk->vtime_snap)
 621                 return 0;
 622
 623         return clock - tsk->vtime_snap;
 624 }
 625
 626 static cputime_t get_vtime_delta(struct task_struct *tsk)
 627 {
 628         unsigned long long delta = vtime_delta(tsk);
 629
 630         WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_SLEEPING);
 631         tsk->vtime_snap += delta;
 632
 633         /* CHECKME: always safe to convert nsecs to cputime? */
 634         return nsecs_to_cputime(delta);
 635 }
 636
 637 static void __vtime_account_system(struct task_struct *tsk)
 638 {
 639         cputime_t delta_cpu = get_vtime_delta(tsk);
 640
 641         account_system_time(tsk, irq_count(), delta_cpu, cputime_to_scaled(delta_cpu));
 642 }
 643
 644 void vtime_account_system(struct task_struct *tsk)
 645 {
 646         if (!vtime_accounting_enabled())
 647                 return;
 648
 649         write_seqlock(&tsk->vtime_seqlock);
 650         __vtime_account_system(tsk);
 651         write_sequnlock(&tsk->vtime_seqlock);
 652 }
 653
 654 void vtime_account_irq_exit(struct task_struct *tsk)
 655 {
 656         if (!vtime_accounting_enabled())
 657                 return;
 658
 659         write_seqlock(&tsk->vtime_seqlock);
 660         if (context_tracking_in_user())
 661                 tsk->vtime_snap_whence = VTIME_USER;
 662         __vtime_account_system(tsk);
 663         write_sequnlock(&tsk->vtime_seqlock);
 664 }
 665
 666 void vtime_account_user(struct task_struct *tsk)
 667 {
 668         cputime_t delta_cpu;
 669
 670         if (!vtime_accounting_enabled())
 671                 return;
 672
 673         delta_cpu = get_vtime_delta(tsk);
 674
 675         write_seqlock(&tsk->vtime_seqlock);
 676         tsk->vtime_snap_whence = VTIME_SYS;
 677         account_user_time(tsk, delta_cpu, cputime_to_scaled(delta_cpu));
 678         write_sequnlock(&tsk->vtime_seqlock);
 679 }
 680
 681 void vtime_user_enter(struct task_struct *tsk)
 682 {
 683         if (!vtime_accounting_enabled())
 684                 return;
 685
 686         write_seqlock(&tsk->vtime_seqlock);
 687         tsk->vtime_snap_whence = VTIME_USER;
 688         __vtime_account_system(tsk);
 689         write_sequnlock(&tsk->vtime_seqlock);
 690 }
 691
 692 void vtime_guest_enter(struct task_struct *tsk)
 693 {
 694         write_seqlock(&tsk->vtime_seqlock);
 695         __vtime_account_system(tsk);
 696         current->flags |= PF_VCPU;
 697         write_sequnlock(&tsk->vtime_seqlock);
 698 }
 699
 700 void vtime_guest_exit(struct task_struct *tsk)
 701 {
 702         write_seqlock(&tsk->vtime_seqlock);
 703         __vtime_account_system(tsk);
 704         current->flags &= ~PF_VCPU;
 705         write_sequnlock(&tsk->vtime_seqlock);
 706 }
 707
 708 void vtime_account_idle(struct task_struct *tsk)
 709 {
 710         cputime_t delta_cpu = get_vtime_delta(tsk);
 711
 712         account_idle_time(delta_cpu);
 713 }
 714
 715 bool vtime_accounting_enabled(void)
 716 {
 717         return context_tracking_active();
 718 }
 719
 720 void arch_vtime_task_switch(struct task_struct *prev)
 721 {
 722         write_seqlock(&prev->vtime_seqlock);
 723         prev->vtime_snap_whence = VTIME_SLEEPING;
 724         write_sequnlock(&prev->vtime_seqlock);
 725
 726         write_seqlock(&current->vtime_seqlock);
 727         current->vtime_snap_whence = VTIME_SYS;
 728         current->vtime_snap = sched_clock();
 729         write_sequnlock(&current->vtime_seqlock);
 730 }
 731
 732 void vtime_init_idle(struct task_struct *t)
 733 {
 734         unsigned long flags;
 735
 736         write_seqlock_irqsave(&t->vtime_seqlock, flags);
 737         t->vtime_snap_whence = VTIME_SYS;
 738         t->vtime_snap = sched_clock();
 739         write_sequnlock_irqrestore(&t->vtime_seqlock, flags);
 740 }
 741
 742 cputime_t task_gtime(struct task_struct *t)
 743 {
 744         unsigned int seq;
 745         cputime_t gtime;
 746
 747         do {
 748                 seq = read_seqbegin(&t->vtime_seqlock);
 749
 750                 gtime = t->gtime;
 751                 if (t->flags & PF_VCPU)
 752                         gtime += vtime_delta(t);
 753
 754         } while (read_seqretry(&t->vtime_seqlock, seq));
 755
 756         return gtime;
 757 }
 758
 759 /*
 760  * Fetch cputime raw values from fields of task_struct and
 761  * add up the pending nohz execution time since the last
 762  * cputime snapshot.
 763  */
 764 static void
 765 fetch_task_cputime(struct task_struct *t,
 766                    cputime_t *u_dst, cputime_t *s_dst,
 767                    cputime_t *u_src, cputime_t *s_src,
 768                    cputime_t *udelta, cputime_t *sdelta)
 769 {
 770         unsigned int seq;
 771         unsigned long long delta;
 772
 773         do {
 774                 *udelta = 0;
 775                 *sdelta = 0;
 776
 777                 seq = read_seqbegin(&t->vtime_seqlock);
 778
 779                 if (u_dst)
 780                         *u_dst = *u_src;
 781                 if (s_dst)
 782                         *s_dst = *s_src;
 783
 784                 /* Task is sleeping, nothing to add */
 785                 if (t->vtime_snap_whence == VTIME_SLEEPING ||
 786                     is_idle_task(t))
 787                         continue;
 788
 789                 delta = vtime_delta(t);
 790
 791                 /*
 792                  * Task runs either in user or kernel space, add pending nohz time to
 793                  * the right place.
 794                  */
 795                 if (t->vtime_snap_whence == VTIME_USER || t->flags & PF_VCPU) {
 796                         *udelta = delta;
 797                 } else {
 798                         if (t->vtime_snap_whence == VTIME_SYS)
 799                                 *sdelta = delta;
 800                 }
 801         } while (read_seqretry(&t->vtime_seqlock, seq));
 802 }
 803
 804
 805 void task_cputime(struct task_struct *t, cputime_t *utime, cputime_t *stime)
 806 {
 807         cputime_t udelta, sdelta;
 808
 809         fetch_task_cputime(t, utime, stime, &t->utime,
 810                            &t->stime, &udelta, &sdelta);
 811         if (utime)
 812                 *utime += udelta;
 813         if (stime)
 814                 *stime += sdelta;
 815 }
 816
 817 void task_cputime_scaled(struct task_struct *t,
 818                          cputime_t *utimescaled, cputime_t *stimescaled)
 819 {
 820         cputime_t udelta, sdelta;
 821
 822         fetch_task_cputime(t, utimescaled, stimescaled,
 823                            &t->utimescaled, &t->stimescaled, &udelta, &sdelta);
 824         if (utimescaled)
 825                 *utimescaled += cputime_to_scaled(udelta);
 826         if (stimescaled)
 827                 *stimescaled += cputime_to_scaled(sdelta);
 828 }
 829 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */