Pileus Git - ~andy/linux/blob - 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(t, &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, but avoid multiplication overflow by
 510  * loosing precision when the numbers are big.
 511  */
 512 static 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                         u64 tmp = rtime; rtime = stime; stime = tmp;
 520                 }
 521
 522                 /* Make sure 'total' fits in 32 bits */
 523                 if (total >> 32)
 524                         goto drop_precision;
 525
 526                 /* Does rtime (and thus stime) fit in 32 bits? */
 527                 if (!(rtime >> 32))
 528                         break;
 529
 530                 /* Can we just balance rtime/stime rather than dropping bits? */
 531                 if (stime >> 31)
 532                         goto drop_precision;
 533
 534                 /* We can grow stime and shrink rtime and try to make them both fit */
 535                 stime <<= 1;
 536                 rtime >>= 1;
 537                 continue;
 538
 539 drop_precision:
 540                 /* We drop from rtime, it has more bits than stime */
 541                 rtime >>= 1;
 542                 total >>= 1;
 543         }
 544
 545         /*
 546          * Make sure gcc understands that this is a 32x32->64 multiply,
 547          * followed by a 64/32->64 divide.
 548          */
 549         scaled = div_u64((u64) (u32) stime * (u64) (u32) rtime, (u32)total);
 550         return (__force cputime_t) scaled;
 551 }
 552
 553 /*
 554  * Adjust tick based cputime random precision against scheduler
 555  * runtime accounting.
 556  */
 557 static void cputime_adjust(struct task_cputime *curr,
 558                            struct cputime *prev,
 559                            cputime_t *ut, cputime_t *st)
 560 {
 561         cputime_t rtime, stime, utime, total;
 562
 563         if (vtime_accounting_enabled()) {
 564                 *ut = curr->utime;
 565                 *st = curr->stime;
 566                 return;
 567         }
 568
 569         stime = curr->stime;
 570         total = stime + curr->utime;
 571
 572         /*
 573          * Tick based cputime accounting depend on random scheduling
 574          * timeslices of a task to be interrupted or not by the timer.
 575          * Depending on these circumstances, the number of these interrupts
 576          * may be over or under-optimistic, matching the real user and system
 577          * cputime with a variable precision.
 578          *
 579          * Fix this by scaling these tick based values against the total
 580          * runtime accounted by the CFS scheduler.
 581          */
 582         rtime = nsecs_to_cputime(curr->sum_exec_runtime);
 583
 584         /*
 585          * Update userspace visible utime/stime values only if actual execution
 586          * time is bigger than already exported. Note that can happen, that we
 587          * provided bigger values due to scaling inaccuracy on big numbers.
 588          */
 589         if (prev->stime + prev->utime >= rtime)
 590                 goto out;
 591
 592         if (total) {
 593                 stime = scale_stime((__force u64)stime,
 594                                     (__force u64)rtime, (__force u64)total);
 595                 utime = rtime - stime;
 596         } else {
 597                 stime = rtime;
 598                 utime = 0;
 599         }
 600
 601         /*
 602          * If the tick based count grows faster than the scheduler one,
 603          * the result of the scaling may go backward.
 604          * Let's enforce monotonicity.
 605          */
 606         prev->stime = max(prev->stime, stime);
 607         prev->utime = max(prev->utime, utime);
 608
 609 out:
 610         *ut = prev->utime;
 611         *st = prev->stime;
 612 }
 613
 614 void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
 615 {
 616         struct task_cputime cputime = {
 617                 .sum_exec_runtime = p->se.sum_exec_runtime,
 618         };
 619
 620         task_cputime(p, &cputime.utime, &cputime.stime);
 621         cputime_adjust(&cputime, &p->prev_cputime, ut, st);
 622 }
 623
 624 /*
 625  * Must be called with siglock held.
 626  */
 627 void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
 628 {
 629         struct task_cputime cputime;
 630
 631         thread_group_cputime(p, &cputime);
 632         cputime_adjust(&cputime, &p->signal->prev_cputime, ut, st);
 633 }
 634 #endif /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
 635
 636 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
 637 static unsigned long long vtime_delta(struct task_struct *tsk)
 638 {
 639         unsigned long long clock;
 640
 641         clock = local_clock();
 642         if (clock < tsk->vtime_snap)
 643                 return 0;
 644
 645         return clock - tsk->vtime_snap;
 646 }
 647
 648 static cputime_t get_vtime_delta(struct task_struct *tsk)
 649 {
 650         unsigned long long delta = vtime_delta(tsk);
 651
 652         WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_SLEEPING);
 653         tsk->vtime_snap += delta;
 654
 655         /* CHECKME: always safe to convert nsecs to cputime? */
 656         return nsecs_to_cputime(delta);
 657 }
 658
 659 static void __vtime_account_system(struct task_struct *tsk)
 660 {
 661         cputime_t delta_cpu = get_vtime_delta(tsk);
 662
 663         account_system_time(tsk, irq_count(), delta_cpu, cputime_to_scaled(delta_cpu));
 664 }
 665
 666 void vtime_account_system(struct task_struct *tsk)
 667 {
 668         if (!vtime_accounting_enabled())
 669                 return;
 670
 671         write_seqlock(&tsk->vtime_seqlock);
 672         __vtime_account_system(tsk);
 673         write_sequnlock(&tsk->vtime_seqlock);
 674 }
 675
 676 void vtime_account_irq_exit(struct task_struct *tsk)
 677 {
 678         if (!vtime_accounting_enabled())
 679                 return;
 680
 681         write_seqlock(&tsk->vtime_seqlock);
 682         if (context_tracking_in_user())
 683                 tsk->vtime_snap_whence = VTIME_USER;
 684         __vtime_account_system(tsk);
 685         write_sequnlock(&tsk->vtime_seqlock);
 686 }
 687
 688 void vtime_account_user(struct task_struct *tsk)
 689 {
 690         cputime_t delta_cpu;
 691
 692         if (!vtime_accounting_enabled())
 693                 return;
 694
 695         delta_cpu = get_vtime_delta(tsk);
 696
 697         write_seqlock(&tsk->vtime_seqlock);
 698         tsk->vtime_snap_whence = VTIME_SYS;
 699         account_user_time(tsk, delta_cpu, cputime_to_scaled(delta_cpu));
 700         write_sequnlock(&tsk->vtime_seqlock);
 701 }
 702
 703 void vtime_user_enter(struct task_struct *tsk)
 704 {
 705         if (!vtime_accounting_enabled())
 706                 return;
 707
 708         write_seqlock(&tsk->vtime_seqlock);
 709         tsk->vtime_snap_whence = VTIME_USER;
 710         __vtime_account_system(tsk);
 711         write_sequnlock(&tsk->vtime_seqlock);
 712 }
 713
 714 void vtime_guest_enter(struct task_struct *tsk)
 715 {
 716         write_seqlock(&tsk->vtime_seqlock);
 717         __vtime_account_system(tsk);
 718         current->flags |= PF_VCPU;
 719         write_sequnlock(&tsk->vtime_seqlock);
 720 }
 721
 722 void vtime_guest_exit(struct task_struct *tsk)
 723 {
 724         write_seqlock(&tsk->vtime_seqlock);
 725         __vtime_account_system(tsk);
 726         current->flags &= ~PF_VCPU;
 727         write_sequnlock(&tsk->vtime_seqlock);
 728 }
 729
 730 void vtime_account_idle(struct task_struct *tsk)
 731 {
 732         cputime_t delta_cpu = get_vtime_delta(tsk);
 733
 734         account_idle_time(delta_cpu);
 735 }
 736
 737 bool vtime_accounting_enabled(void)
 738 {
 739         return context_tracking_active();
 740 }
 741
 742 void arch_vtime_task_switch(struct task_struct *prev)
 743 {
 744         write_seqlock(&prev->vtime_seqlock);
 745         prev->vtime_snap_whence = VTIME_SLEEPING;
 746         write_sequnlock(&prev->vtime_seqlock);
 747
 748         write_seqlock(&current->vtime_seqlock);
 749         current->vtime_snap_whence = VTIME_SYS;
 750         current->vtime_snap = sched_clock();
 751         write_sequnlock(&current->vtime_seqlock);
 752 }
 753
 754 void vtime_init_idle(struct task_struct *t)
 755 {
 756         unsigned long flags;
 757
 758         write_seqlock_irqsave(&t->vtime_seqlock, flags);
 759         t->vtime_snap_whence = VTIME_SYS;
 760         t->vtime_snap = sched_clock();
 761         write_sequnlock_irqrestore(&t->vtime_seqlock, flags);
 762 }
 763
 764 cputime_t task_gtime(struct task_struct *t)
 765 {
 766         unsigned int seq;
 767         cputime_t gtime;
 768
 769         do {
 770                 seq = read_seqbegin(&t->vtime_seqlock);
 771
 772                 gtime = t->gtime;
 773                 if (t->flags & PF_VCPU)
 774                         gtime += vtime_delta(t);
 775
 776         } while (read_seqretry(&t->vtime_seqlock, seq));
 777
 778         return gtime;
 779 }
 780
 781 /*
 782  * Fetch cputime raw values from fields of task_struct and
 783  * add up the pending nohz execution time since the last
 784  * cputime snapshot.
 785  */
 786 static void
 787 fetch_task_cputime(struct task_struct *t,
 788                    cputime_t *u_dst, cputime_t *s_dst,
 789                    cputime_t *u_src, cputime_t *s_src,
 790                    cputime_t *udelta, cputime_t *sdelta)
 791 {
 792         unsigned int seq;
 793         unsigned long long delta;
 794
 795         do {
 796                 *udelta = 0;
 797                 *sdelta = 0;
 798
 799                 seq = read_seqbegin(&t->vtime_seqlock);
 800
 801                 if (u_dst)
 802                         *u_dst = *u_src;
 803                 if (s_dst)
 804                         *s_dst = *s_src;
 805
 806                 /* Task is sleeping, nothing to add */
 807                 if (t->vtime_snap_whence == VTIME_SLEEPING ||
 808                     is_idle_task(t))
 809                         continue;
 810
 811                 delta = vtime_delta(t);
 812
 813                 /*
 814                  * Task runs either in user or kernel space, add pending nohz time to
 815                  * the right place.
 816                  */
 817                 if (t->vtime_snap_whence == VTIME_USER || t->flags & PF_VCPU) {
 818                         *udelta = delta;
 819                 } else {
 820                         if (t->vtime_snap_whence == VTIME_SYS)
 821                                 *sdelta = delta;
 822                 }
 823         } while (read_seqretry(&t->vtime_seqlock, seq));
 824 }
 825
 826
 827 void task_cputime(struct task_struct *t, cputime_t *utime, cputime_t *stime)
 828 {
 829         cputime_t udelta, sdelta;
 830
 831         fetch_task_cputime(t, utime, stime, &t->utime,
 832                            &t->stime, &udelta, &sdelta);
 833         if (utime)
 834                 *utime += udelta;
 835         if (stime)
 836                 *stime += sdelta;
 837 }
 838
 839 void task_cputime_scaled(struct task_struct *t,
 840                          cputime_t *utimescaled, cputime_t *stimescaled)
 841 {
 842         cputime_t udelta, sdelta;
 843
 844         fetch_task_cputime(t, utimescaled, stimescaled,
 845                            &t->utimescaled, &t->stimescaled, &udelta, &sdelta);
 846         if (utimescaled)
 847                 *utimescaled += cputime_to_scaled(udelta);
 848         if (stimescaled)
 849                 *stimescaled += cputime_to_scaled(sdelta);
 850 }
 851 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */