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 #ifdef CONFIG_CGROUP_CPUACCT
 119         struct kernel_cpustat *kcpustat;
 120         struct cpuacct *ca;
 121 #endif
 122         /*
 123          * Since all updates are sure to touch the root cgroup, we
 124          * get ourselves ahead and touch it first. If the root cgroup
 125          * is the only cgroup, then nothing else should be necessary.
 126          *
 127          */
 128         __get_cpu_var(kernel_cpustat).cpustat[index] += tmp;
 129
 130 #ifdef CONFIG_CGROUP_CPUACCT
 131         if (unlikely(!cpuacct_subsys.active))
 132                 return;
 133
 134         rcu_read_lock();
 135         ca = task_ca(p);
 136         while (ca && (ca != &root_cpuacct)) {
 137                 kcpustat = this_cpu_ptr(ca->cpustat);
 138                 kcpustat->cpustat[index] += tmp;
 139                 ca = parent_ca(ca);
 140         }
 141         rcu_read_unlock();
 142 #endif
 143 }
 144
 145 /*
 146  * Account user cpu time to a process.
 147  * @p: the process that the cpu time gets accounted to
 148  * @cputime: the cpu time spent in user space since the last update
 149  * @cputime_scaled: cputime scaled by cpu frequency
 150  */
 151 void account_user_time(struct task_struct *p, cputime_t cputime,
 152                        cputime_t cputime_scaled)
 153 {
 154         int index;
 155
 156         /* Add user time to process. */
 157         p->utime += cputime;
 158         p->utimescaled += cputime_scaled;
 159         account_group_user_time(p, cputime);
 160
 161         index = (TASK_NICE(p) > 0) ? CPUTIME_NICE : CPUTIME_USER;
 162
 163         /* Add user time to cpustat. */
 164         task_group_account_field(p, index, (__force u64) cputime);
 165
 166         /* Account for user time used */
 167         acct_account_cputime(p);
 168 }
 169
 170 /*
 171  * Account guest cpu time to a process.
 172  * @p: the process that the cpu time gets accounted to
 173  * @cputime: the cpu time spent in virtual machine since the last update
 174  * @cputime_scaled: cputime scaled by cpu frequency
 175  */
 176 static void account_guest_time(struct task_struct *p, cputime_t cputime,
 177                                cputime_t cputime_scaled)
 178 {
 179         u64 *cpustat = kcpustat_this_cpu->cpustat;
 180
 181         /* Add guest time to process. */
 182         p->utime += cputime;
 183         p->utimescaled += cputime_scaled;
 184         account_group_user_time(p, cputime);
 185         p->gtime += cputime;
 186
 187         /* Add guest time to cpustat. */
 188         if (TASK_NICE(p) > 0) {
 189                 cpustat[CPUTIME_NICE] += (__force u64) cputime;
 190                 cpustat[CPUTIME_GUEST_NICE] += (__force u64) cputime;
 191         } else {
 192                 cpustat[CPUTIME_USER] += (__force u64) cputime;
 193                 cpustat[CPUTIME_GUEST] += (__force u64) cputime;
 194         }
 195 }
 196
 197 /*
 198  * Account system cpu time to a process and desired cpustat field
 199  * @p: the process that the cpu time gets accounted to
 200  * @cputime: the cpu time spent in kernel space since the last update
 201  * @cputime_scaled: cputime scaled by cpu frequency
 202  * @target_cputime64: pointer to cpustat field that has to be updated
 203  */
 204 static inline
 205 void __account_system_time(struct task_struct *p, cputime_t cputime,
 206                         cputime_t cputime_scaled, int index)
 207 {
 208         /* Add system time to process. */
 209         p->stime += cputime;
 210         p->stimescaled += cputime_scaled;
 211         account_group_system_time(p, cputime);
 212
 213         /* Add system time to cpustat. */
 214         task_group_account_field(p, index, (__force u64) cputime);
 215
 216         /* Account for system time used */
 217         acct_account_cputime(p);
 218 }
 219
 220 /*
 221  * Account system cpu time to a process.
 222  * @p: the process that the cpu time gets accounted to
 223  * @hardirq_offset: the offset to subtract from hardirq_count()
 224  * @cputime: the cpu time spent in kernel space since the last update
 225  * @cputime_scaled: cputime scaled by cpu frequency
 226  */
 227 void account_system_time(struct task_struct *p, int hardirq_offset,
 228                          cputime_t cputime, cputime_t cputime_scaled)
 229 {
 230         int index;
 231
 232         if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) {
 233                 account_guest_time(p, cputime, cputime_scaled);
 234                 return;
 235         }
 236
 237         if (hardirq_count() - hardirq_offset)
 238                 index = CPUTIME_IRQ;
 239         else if (in_serving_softirq())
 240                 index = CPUTIME_SOFTIRQ;
 241         else
 242                 index = CPUTIME_SYSTEM;
 243
 244         __account_system_time(p, cputime, cputime_scaled, index);
 245 }
 246
 247 /*
 248  * Account for involuntary wait time.
 249  * @cputime: the cpu time spent in involuntary wait
 250  */
 251 void account_steal_time(cputime_t cputime)
 252 {
 253         u64 *cpustat = kcpustat_this_cpu->cpustat;
 254
 255         cpustat[CPUTIME_STEAL] += (__force u64) cputime;
 256 }
 257
 258 /*
 259  * Account for idle time.
 260  * @cputime: the cpu time spent in idle wait
 261  */
 262 void account_idle_time(cputime_t cputime)
 263 {
 264         u64 *cpustat = kcpustat_this_cpu->cpustat;
 265         struct rq *rq = this_rq();
 266
 267         if (atomic_read(&rq->nr_iowait) > 0)
 268                 cpustat[CPUTIME_IOWAIT] += (__force u64) cputime;
 269         else
 270                 cpustat[CPUTIME_IDLE] += (__force u64) cputime;
 271 }
 272
 273 static __always_inline bool steal_account_process_tick(void)
 274 {
 275 #ifdef CONFIG_PARAVIRT
 276         if (static_key_false(&paravirt_steal_enabled)) {
 277                 u64 steal, st = 0;
 278
 279                 steal = paravirt_steal_clock(smp_processor_id());
 280                 steal -= this_rq()->prev_steal_time;
 281
 282                 st = steal_ticks(steal);
 283                 this_rq()->prev_steal_time += st * TICK_NSEC;
 284
 285                 account_steal_time(st);
 286                 return st;
 287         }
 288 #endif
 289         return false;
 290 }
 291
 292 /*
 293  * Accumulate raw cputime values of dead tasks (sig->[us]time) and live
 294  * tasks (sum on group iteration) belonging to @tsk's group.
 295  */
 296 void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times)
 297 {
 298         struct signal_struct *sig = tsk->signal;
 299         cputime_t utime, stime;
 300         struct task_struct *t;
 301
 302         times->utime = sig->utime;
 303         times->stime = sig->stime;
 304         times->sum_exec_runtime = sig->sum_sched_runtime;
 305
 306         rcu_read_lock();
 307         /* make sure we can trust tsk->thread_group list */
 308         if (!likely(pid_alive(tsk)))
 309                 goto out;
 310
 311         t = tsk;
 312         do {
 313                 task_cputime(tsk, &utime, &stime);
 314                 times->utime += utime;
 315                 times->stime += stime;
 316                 times->sum_exec_runtime += task_sched_runtime(t);
 317         } while_each_thread(tsk, t);
 318 out:
 319         rcu_read_unlock();
 320 }
 321
 322 #ifdef CONFIG_IRQ_TIME_ACCOUNTING
 323 /*
 324  * Account a tick to a process and cpustat
 325  * @p: the process that the cpu time gets accounted to
 326  * @user_tick: is the tick from userspace
 327  * @rq: the pointer to rq
 328  *
 329  * Tick demultiplexing follows the order
 330  * - pending hardirq update
 331  * - pending softirq update
 332  * - user_time
 333  * - idle_time
 334  * - system time
 335  *   - check for guest_time
 336  *   - else account as system_time
 337  *
 338  * Check for hardirq is done both for system and user time as there is
 339  * no timer going off while we are on hardirq and hence we may never get an
 340  * opportunity to update it solely in system time.
 341  * p->stime and friends are only updated on system time and not on irq
 342  * softirq as those do not count in task exec_runtime any more.
 343  */
 344 static void irqtime_account_process_tick(struct task_struct *p, int user_tick,
 345                                                 struct rq *rq)
 346 {
 347         cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
 348         u64 *cpustat = kcpustat_this_cpu->cpustat;
 349
 350         if (steal_account_process_tick())
 351                 return;
 352
 353         if (irqtime_account_hi_update()) {
 354                 cpustat[CPUTIME_IRQ] += (__force u64) cputime_one_jiffy;
 355         } else if (irqtime_account_si_update()) {
 356                 cpustat[CPUTIME_SOFTIRQ] += (__force u64) cputime_one_jiffy;
 357         } else if (this_cpu_ksoftirqd() == p) {
 358                 /*
 359                  * ksoftirqd time do not get accounted in cpu_softirq_time.
 360                  * So, we have to handle it separately here.
 361                  * Also, p->stime needs to be updated for ksoftirqd.
 362                  */
 363                 __account_system_time(p, cputime_one_jiffy, one_jiffy_scaled,
 364                                         CPUTIME_SOFTIRQ);
 365         } else if (user_tick) {
 366                 account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);
 367         } else if (p == rq->idle) {
 368                 account_idle_time(cputime_one_jiffy);
 369         } else if (p->flags & PF_VCPU) { /* System time or guest time */
 370                 account_guest_time(p, cputime_one_jiffy, one_jiffy_scaled);
 371         } else {
 372                 __account_system_time(p, cputime_one_jiffy, one_jiffy_scaled,
 373                                         CPUTIME_SYSTEM);
 374         }
 375 }
 376
 377 static void irqtime_account_idle_ticks(int ticks)
 378 {
 379         int i;
 380         struct rq *rq = this_rq();
 381
 382         for (i = 0; i < ticks; i++)
 383                 irqtime_account_process_tick(current, 0, rq);
 384 }
 385 #else /* CONFIG_IRQ_TIME_ACCOUNTING */
 386 static inline void irqtime_account_idle_ticks(int ticks) {}
 387 static inline void irqtime_account_process_tick(struct task_struct *p, int user_tick,
 388                                                 struct rq *rq) {}
 389 #endif /* CONFIG_IRQ_TIME_ACCOUNTING */
 390
 391 #ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
 392 /*
 393  * Account a single tick of cpu time.
 394  * @p: the process that the cpu time gets accounted to
 395  * @user_tick: indicates if the tick is a user or a system tick
 396  */
 397 void account_process_tick(struct task_struct *p, int user_tick)
 398 {
 399         cputime_t one_jiffy_scaled = cputime_to_scaled(cputime_one_jiffy);
 400         struct rq *rq = this_rq();
 401
 402         if (vtime_accounting_enabled())
 403                 return;
 404
 405         if (sched_clock_irqtime) {
 406                 irqtime_account_process_tick(p, user_tick, rq);
 407                 return;
 408         }
 409
 410         if (steal_account_process_tick())
 411                 return;
 412
 413         if (user_tick)
 414                 account_user_time(p, cputime_one_jiffy, one_jiffy_scaled);
 415         else if ((p != rq->idle) || (irq_count() != HARDIRQ_OFFSET))
 416                 account_system_time(p, HARDIRQ_OFFSET, cputime_one_jiffy,
 417                                     one_jiffy_scaled);
 418         else
 419                 account_idle_time(cputime_one_jiffy);
 420 }
 421
 422 /*
 423  * Account multiple ticks of steal time.
 424  * @p: the process from which the cpu time has been stolen
 425  * @ticks: number of stolen ticks
 426  */
 427 void account_steal_ticks(unsigned long ticks)
 428 {
 429         account_steal_time(jiffies_to_cputime(ticks));
 430 }
 431
 432 /*
 433  * Account multiple ticks of idle time.
 434  * @ticks: number of stolen ticks
 435  */
 436 void account_idle_ticks(unsigned long ticks)
 437 {
 438
 439         if (sched_clock_irqtime) {
 440                 irqtime_account_idle_ticks(ticks);
 441                 return;
 442         }
 443
 444         account_idle_time(jiffies_to_cputime(ticks));
 445 }
 446 #endif /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
 447
 448 /*
 449  * Use precise platform statistics if available:
 450  */
 451 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
 452 void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
 453 {
 454         *ut = p->utime;
 455         *st = p->stime;
 456 }
 457
 458 void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
 459 {
 460         struct task_cputime cputime;
 461
 462         thread_group_cputime(p, &cputime);
 463
 464         *ut = cputime.utime;
 465         *st = cputime.stime;
 466 }
 467
 468 #ifndef __ARCH_HAS_VTIME_TASK_SWITCH
 469 void vtime_task_switch(struct task_struct *prev)
 470 {
 471         if (!vtime_accounting_enabled())
 472                 return;
 473
 474         if (is_idle_task(prev))
 475                 vtime_account_idle(prev);
 476         else
 477                 vtime_account_system(prev);
 478
 479 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
 480         vtime_account_user(prev);
 481 #endif
 482         arch_vtime_task_switch(prev);
 483 }
 484 #endif
 485
 486 /*
 487  * Archs that account the whole time spent in the idle task
 488  * (outside irq) as idle time can rely on this and just implement
 489  * vtime_account_system() and vtime_account_idle(). Archs that
 490  * have other meaning of the idle time (s390 only includes the
 491  * time spent by the CPU when it's in low power mode) must override
 492  * vtime_account().
 493  */
 494 #ifndef __ARCH_HAS_VTIME_ACCOUNT
 495 void vtime_account_irq_enter(struct task_struct *tsk)
 496 {
 497         if (!vtime_accounting_enabled())
 498                 return;
 499
 500         if (!in_interrupt()) {
 501                 /*
 502                  * If we interrupted user, context_tracking_in_user()
 503                  * is 1 because the context tracking don't hook
 504                  * on irq entry/exit. This way we know if
 505                  * we need to flush user time on kernel entry.
 506                  */
 507                 if (context_tracking_in_user()) {
 508                         vtime_account_user(tsk);
 509                         return;
 510                 }
 511
 512                 if (is_idle_task(tsk)) {
 513                         vtime_account_idle(tsk);
 514                         return;
 515                 }
 516         }
 517         vtime_account_system(tsk);
 518 }
 519 EXPORT_SYMBOL_GPL(vtime_account_irq_enter);
 520 #endif /* __ARCH_HAS_VTIME_ACCOUNT */
 521
 522 #else /* !CONFIG_VIRT_CPU_ACCOUNTING */
 523
 524 static cputime_t scale_stime(cputime_t stime, cputime_t rtime, cputime_t total)
 525 {
 526         u64 temp = (__force u64) rtime;
 527
 528         temp *= (__force u64) stime;
 529
 530         if (sizeof(cputime_t) == 4)
 531                 temp = div_u64(temp, (__force u32) total);
 532         else
 533                 temp = div64_u64(temp, (__force u64) total);
 534
 535         return (__force cputime_t) temp;
 536 }
 537
 538 /*
 539  * Adjust tick based cputime random precision against scheduler
 540  * runtime accounting.
 541  */
 542 static void cputime_adjust(struct task_cputime *curr,
 543                            struct cputime *prev,
 544                            cputime_t *ut, cputime_t *st)
 545 {
 546         cputime_t rtime, stime, total;
 547
 548         stime = curr->stime;
 549         total = stime + curr->utime;
 550
 551         /*
 552          * Tick based cputime accounting depend on random scheduling
 553          * timeslices of a task to be interrupted or not by the timer.
 554          * Depending on these circumstances, the number of these interrupts
 555          * may be over or under-optimistic, matching the real user and system
 556          * cputime with a variable precision.
 557          *
 558          * Fix this by scaling these tick based values against the total
 559          * runtime accounted by the CFS scheduler.
 560          */
 561         rtime = nsecs_to_cputime(curr->sum_exec_runtime);
 562
 563         if (total)
 564                 stime = scale_stime(stime, rtime, total);
 565         else
 566                 stime = rtime;
 567
 568         /*
 569          * If the tick based count grows faster than the scheduler one,
 570          * the result of the scaling may go backward.
 571          * Let's enforce monotonicity.
 572          */
 573         prev->stime = max(prev->stime, stime);
 574         prev->utime = max(prev->utime, rtime - prev->stime);
 575
 576         *ut = prev->utime;
 577         *st = prev->stime;
 578 }
 579
 580 void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
 581 {
 582         struct task_cputime cputime = {
 583                 .sum_exec_runtime = p->se.sum_exec_runtime,
 584         };
 585
 586         task_cputime(p, &cputime.utime, &cputime.stime);
 587         cputime_adjust(&cputime, &p->prev_cputime, ut, st);
 588 }
 589
 590 /*
 591  * Must be called with siglock held.
 592  */
 593 void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
 594 {
 595         struct task_cputime cputime;
 596
 597         thread_group_cputime(p, &cputime);
 598         cputime_adjust(&cputime, &p->signal->prev_cputime, ut, st);
 599 }
 600 #endif /* !CONFIG_VIRT_CPU_ACCOUNTING */
 601
 602 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
 603 static unsigned long long vtime_delta(struct task_struct *tsk)
 604 {
 605         unsigned long long clock;
 606
 607         clock = local_clock();
 608         if (clock < tsk->vtime_snap)
 609                 return 0;
 610
 611         return clock - tsk->vtime_snap;
 612 }
 613
 614 static cputime_t get_vtime_delta(struct task_struct *tsk)
 615 {
 616         unsigned long long delta = vtime_delta(tsk);
 617
 618         WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_SLEEPING);
 619         tsk->vtime_snap += delta;
 620
 621         /* CHECKME: always safe to convert nsecs to cputime? */
 622         return nsecs_to_cputime(delta);
 623 }
 624
 625 static void __vtime_account_system(struct task_struct *tsk)
 626 {
 627         cputime_t delta_cpu = get_vtime_delta(tsk);
 628
 629         account_system_time(tsk, irq_count(), delta_cpu, cputime_to_scaled(delta_cpu));
 630 }
 631
 632 void vtime_account_system(struct task_struct *tsk)
 633 {
 634         if (!vtime_accounting_enabled())
 635                 return;
 636
 637         write_seqlock(&tsk->vtime_seqlock);
 638         __vtime_account_system(tsk);
 639         write_sequnlock(&tsk->vtime_seqlock);
 640 }
 641
 642 void vtime_account_irq_exit(struct task_struct *tsk)
 643 {
 644         if (!vtime_accounting_enabled())
 645                 return;
 646
 647         write_seqlock(&tsk->vtime_seqlock);
 648         if (context_tracking_in_user())
 649                 tsk->vtime_snap_whence = VTIME_USER;
 650         __vtime_account_system(tsk);
 651         write_sequnlock(&tsk->vtime_seqlock);
 652 }
 653
 654 void vtime_account_user(struct task_struct *tsk)
 655 {
 656         cputime_t delta_cpu;
 657
 658         if (!vtime_accounting_enabled())
 659                 return;
 660
 661         delta_cpu = get_vtime_delta(tsk);
 662
 663         write_seqlock(&tsk->vtime_seqlock);
 664         tsk->vtime_snap_whence = VTIME_SYS;
 665         account_user_time(tsk, delta_cpu, cputime_to_scaled(delta_cpu));
 666         write_sequnlock(&tsk->vtime_seqlock);
 667 }
 668
 669 void vtime_user_enter(struct task_struct *tsk)
 670 {
 671         if (!vtime_accounting_enabled())
 672                 return;
 673
 674         write_seqlock(&tsk->vtime_seqlock);
 675         tsk->vtime_snap_whence = VTIME_USER;
 676         __vtime_account_system(tsk);
 677         write_sequnlock(&tsk->vtime_seqlock);
 678 }
 679
 680 void vtime_guest_enter(struct task_struct *tsk)
 681 {
 682         write_seqlock(&tsk->vtime_seqlock);
 683         __vtime_account_system(tsk);
 684         current->flags |= PF_VCPU;
 685         write_sequnlock(&tsk->vtime_seqlock);
 686 }
 687
 688 void vtime_guest_exit(struct task_struct *tsk)
 689 {
 690         write_seqlock(&tsk->vtime_seqlock);
 691         __vtime_account_system(tsk);
 692         current->flags &= ~PF_VCPU;
 693         write_sequnlock(&tsk->vtime_seqlock);
 694 }
 695
 696 void vtime_account_idle(struct task_struct *tsk)
 697 {
 698         cputime_t delta_cpu = get_vtime_delta(tsk);
 699
 700         account_idle_time(delta_cpu);
 701 }
 702
 703 bool vtime_accounting_enabled(void)
 704 {
 705         return context_tracking_active();
 706 }
 707
 708 void arch_vtime_task_switch(struct task_struct *prev)
 709 {
 710         write_seqlock(&prev->vtime_seqlock);
 711         prev->vtime_snap_whence = VTIME_SLEEPING;
 712         write_sequnlock(&prev->vtime_seqlock);
 713
 714         write_seqlock(&current->vtime_seqlock);
 715         current->vtime_snap_whence = VTIME_SYS;
 716         current->vtime_snap = sched_clock();
 717         write_sequnlock(&current->vtime_seqlock);
 718 }
 719
 720 void vtime_init_idle(struct task_struct *t)
 721 {
 722         unsigned long flags;
 723
 724         write_seqlock_irqsave(&t->vtime_seqlock, flags);
 725         t->vtime_snap_whence = VTIME_SYS;
 726         t->vtime_snap = sched_clock();
 727         write_sequnlock_irqrestore(&t->vtime_seqlock, flags);
 728 }
 729
 730 cputime_t task_gtime(struct task_struct *t)
 731 {
 732         unsigned int seq;
 733         cputime_t gtime;
 734
 735         do {
 736                 seq = read_seqbegin(&t->vtime_seqlock);
 737
 738                 gtime = t->gtime;
 739                 if (t->flags & PF_VCPU)
 740                         gtime += vtime_delta(t);
 741
 742         } while (read_seqretry(&t->vtime_seqlock, seq));
 743
 744         return gtime;
 745 }
 746
 747 /*
 748  * Fetch cputime raw values from fields of task_struct and
 749  * add up the pending nohz execution time since the last
 750  * cputime snapshot.
 751  */
 752 static void
 753 fetch_task_cputime(struct task_struct *t,
 754                    cputime_t *u_dst, cputime_t *s_dst,
 755                    cputime_t *u_src, cputime_t *s_src,
 756                    cputime_t *udelta, cputime_t *sdelta)
 757 {
 758         unsigned int seq;
 759         unsigned long long delta;
 760
 761         do {
 762                 *udelta = 0;
 763                 *sdelta = 0;
 764
 765                 seq = read_seqbegin(&t->vtime_seqlock);
 766
 767                 if (u_dst)
 768                         *u_dst = *u_src;
 769                 if (s_dst)
 770                         *s_dst = *s_src;
 771
 772                 /* Task is sleeping, nothing to add */
 773                 if (t->vtime_snap_whence == VTIME_SLEEPING ||
 774                     is_idle_task(t))
 775                         continue;
 776
 777                 delta = vtime_delta(t);
 778
 779                 /*
 780                  * Task runs either in user or kernel space, add pending nohz time to
 781                  * the right place.
 782                  */
 783                 if (t->vtime_snap_whence == VTIME_USER || t->flags & PF_VCPU) {
 784                         *udelta = delta;
 785                 } else {
 786                         if (t->vtime_snap_whence == VTIME_SYS)
 787                                 *sdelta = delta;
 788                 }
 789         } while (read_seqretry(&t->vtime_seqlock, seq));
 790 }
 791
 792
 793 void task_cputime(struct task_struct *t, cputime_t *utime, cputime_t *stime)
 794 {
 795         cputime_t udelta, sdelta;
 796
 797         fetch_task_cputime(t, utime, stime, &t->utime,
 798                            &t->stime, &udelta, &sdelta);
 799         if (utime)
 800                 *utime += udelta;
 801         if (stime)
 802                 *stime += sdelta;
 803 }
 804
 805 void task_cputime_scaled(struct task_struct *t,
 806                          cputime_t *utimescaled, cputime_t *stimescaled)
 807 {
 808         cputime_t udelta, sdelta;
 809
 810         fetch_task_cputime(t, utimescaled, stimescaled,
 811                            &t->utimescaled, &t->stimescaled, &udelta, &sdelta);
 812         if (utimescaled)
 813                 *utimescaled += cputime_to_scaled(udelta);
 814         if (stimescaled)
 815                 *stimescaled += cputime_to_scaled(sdelta);
 816 }
 817 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */