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, int ticks)
 330 {
 331         cputime_t scaled = cputime_to_scaled(cputime_one_jiffy);
 332         u64 cputime = (__force u64) cputime_one_jiffy;
 333         u64 *cpustat = kcpustat_this_cpu->cpustat;
 334
 335         if (steal_account_process_tick())
 336                 return;
 337
 338         cputime *= ticks;
 339         scaled *= ticks;
 340
 341         if (irqtime_account_hi_update()) {
 342                 cpustat[CPUTIME_IRQ] += cputime;
 343         } else if (irqtime_account_si_update()) {
 344                 cpustat[CPUTIME_SOFTIRQ] += cputime;
 345         } else if (this_cpu_ksoftirqd() == p) {
 346                 /*
 347                  * ksoftirqd time do not get accounted in cpu_softirq_time.
 348                  * So, we have to handle it separately here.
 349                  * Also, p->stime needs to be updated for ksoftirqd.
 350                  */
 351                 __account_system_time(p, cputime, scaled, CPUTIME_SOFTIRQ);
 352         } else if (user_tick) {
 353                 account_user_time(p, cputime, scaled);
 354         } else if (p == rq->idle) {
 355                 account_idle_time(cputime);
 356         } else if (p->flags & PF_VCPU) { /* System time or guest time */
 357                 account_guest_time(p, cputime, scaled);
 358         } else {
 359                 __account_system_time(p, cputime, scaled,       CPUTIME_SYSTEM);
 360         }
 361 }
 362
 363 static void irqtime_account_idle_ticks(int ticks)
 364 {
 365         struct rq *rq = this_rq();
 366
 367         irqtime_account_process_tick(current, 0, rq, ticks);
 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, int nr_ticks) {}
 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, 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  */
 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;
 562
 563         if (vtime_accounting_enabled()) {
 564                 *ut = curr->utime;
 565                 *st = curr->stime;
 566                 return;
 567         }
 568
 569         /*
 570          * Tick based cputime accounting depend on random scheduling
 571          * timeslices of a task to be interrupted or not by the timer.
 572          * Depending on these circumstances, the number of these interrupts
 573          * may be over or under-optimistic, matching the real user and system
 574          * cputime with a variable precision.
 575          *
 576          * Fix this by scaling these tick based values against the total
 577          * runtime accounted by the CFS scheduler.
 578          */
 579         rtime = nsecs_to_cputime(curr->sum_exec_runtime);
 580
 581         /*
 582          * Update userspace visible utime/stime values only if actual execution
 583          * time is bigger than already exported. Note that can happen, that we
 584          * provided bigger values due to scaling inaccuracy on big numbers.
 585          */
 586         if (prev->stime + prev->utime >= rtime)
 587                 goto out;
 588
 589         stime = curr->stime;
 590         utime = curr->utime;
 591
 592         if (utime == 0) {
 593                 stime = rtime;
 594         } else if (stime == 0) {
 595                 utime = rtime;
 596         } else {
 597                 cputime_t total = stime + utime;
 598
 599                 stime = scale_stime((__force u64)stime,
 600                                     (__force u64)rtime, (__force u64)total);
 601                 utime = rtime - stime;
 602         }
 603
 604         /*
 605          * If the tick based count grows faster than the scheduler one,
 606          * the result of the scaling may go backward.
 607          * Let's enforce monotonicity.
 608          */
 609         prev->stime = max(prev->stime, stime);
 610         prev->utime = max(prev->utime, utime);
 611
 612 out:
 613         *ut = prev->utime;
 614         *st = prev->stime;
 615 }
 616
 617 void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
 618 {
 619         struct task_cputime cputime = {
 620                 .sum_exec_runtime = p->se.sum_exec_runtime,
 621         };
 622
 623         task_cputime(p, &cputime.utime, &cputime.stime);
 624         cputime_adjust(&cputime, &p->prev_cputime, ut, st);
 625 }
 626
 627 /*
 628  * Must be called with siglock held.
 629  */
 630 void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st)
 631 {
 632         struct task_cputime cputime;
 633
 634         thread_group_cputime(p, &cputime);
 635         cputime_adjust(&cputime, &p->signal->prev_cputime, ut, st);
 636 }
 637 #endif /* !CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
 638
 639 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
 640 static unsigned long long vtime_delta(struct task_struct *tsk)
 641 {
 642         unsigned long long clock;
 643
 644         clock = local_clock();
 645         if (clock < tsk->vtime_snap)
 646                 return 0;
 647
 648         return clock - tsk->vtime_snap;
 649 }
 650
 651 static cputime_t get_vtime_delta(struct task_struct *tsk)
 652 {
 653         unsigned long long delta = vtime_delta(tsk);
 654
 655         WARN_ON_ONCE(tsk->vtime_snap_whence == VTIME_SLEEPING);
 656         tsk->vtime_snap += delta;
 657
 658         /* CHECKME: always safe to convert nsecs to cputime? */
 659         return nsecs_to_cputime(delta);
 660 }
 661
 662 static void __vtime_account_system(struct task_struct *tsk)
 663 {
 664         cputime_t delta_cpu = get_vtime_delta(tsk);
 665
 666         account_system_time(tsk, irq_count(), delta_cpu, cputime_to_scaled(delta_cpu));
 667 }
 668
 669 void vtime_account_system(struct task_struct *tsk)
 670 {
 671         if (!vtime_accounting_enabled())
 672                 return;
 673
 674         write_seqlock(&tsk->vtime_seqlock);
 675         __vtime_account_system(tsk);
 676         write_sequnlock(&tsk->vtime_seqlock);
 677 }
 678
 679 void vtime_account_irq_exit(struct task_struct *tsk)
 680 {
 681         if (!vtime_accounting_enabled())
 682                 return;
 683
 684         write_seqlock(&tsk->vtime_seqlock);
 685         if (context_tracking_in_user())
 686                 tsk->vtime_snap_whence = VTIME_USER;
 687         __vtime_account_system(tsk);
 688         write_sequnlock(&tsk->vtime_seqlock);
 689 }
 690
 691 void vtime_account_user(struct task_struct *tsk)
 692 {
 693         cputime_t delta_cpu;
 694
 695         if (!vtime_accounting_enabled())
 696                 return;
 697
 698         delta_cpu = get_vtime_delta(tsk);
 699
 700         write_seqlock(&tsk->vtime_seqlock);
 701         tsk->vtime_snap_whence = VTIME_SYS;
 702         account_user_time(tsk, delta_cpu, cputime_to_scaled(delta_cpu));
 703         write_sequnlock(&tsk->vtime_seqlock);
 704 }
 705
 706 void vtime_user_enter(struct task_struct *tsk)
 707 {
 708         if (!vtime_accounting_enabled())
 709                 return;
 710
 711         write_seqlock(&tsk->vtime_seqlock);
 712         tsk->vtime_snap_whence = VTIME_USER;
 713         __vtime_account_system(tsk);
 714         write_sequnlock(&tsk->vtime_seqlock);
 715 }
 716
 717 void vtime_guest_enter(struct task_struct *tsk)
 718 {
 719         write_seqlock(&tsk->vtime_seqlock);
 720         __vtime_account_system(tsk);
 721         current->flags |= PF_VCPU;
 722         write_sequnlock(&tsk->vtime_seqlock);
 723 }
 724
 725 void vtime_guest_exit(struct task_struct *tsk)
 726 {
 727         write_seqlock(&tsk->vtime_seqlock);
 728         __vtime_account_system(tsk);
 729         current->flags &= ~PF_VCPU;
 730         write_sequnlock(&tsk->vtime_seqlock);
 731 }
 732
 733 void vtime_account_idle(struct task_struct *tsk)
 734 {
 735         cputime_t delta_cpu = get_vtime_delta(tsk);
 736
 737         account_idle_time(delta_cpu);
 738 }
 739
 740 bool vtime_accounting_enabled(void)
 741 {
 742         return context_tracking_active();
 743 }
 744
 745 void arch_vtime_task_switch(struct task_struct *prev)
 746 {
 747         write_seqlock(&prev->vtime_seqlock);
 748         prev->vtime_snap_whence = VTIME_SLEEPING;
 749         write_sequnlock(&prev->vtime_seqlock);
 750
 751         write_seqlock(&current->vtime_seqlock);
 752         current->vtime_snap_whence = VTIME_SYS;
 753         current->vtime_snap = sched_clock_cpu(smp_processor_id());
 754         write_sequnlock(&current->vtime_seqlock);
 755 }
 756
 757 void vtime_init_idle(struct task_struct *t, int cpu)
 758 {
 759         unsigned long flags;
 760
 761         write_seqlock_irqsave(&t->vtime_seqlock, flags);
 762         t->vtime_snap_whence = VTIME_SYS;
 763         t->vtime_snap = sched_clock_cpu(cpu);
 764         write_sequnlock_irqrestore(&t->vtime_seqlock, flags);
 765 }
 766
 767 cputime_t task_gtime(struct task_struct *t)
 768 {
 769         unsigned int seq;
 770         cputime_t gtime;
 771
 772         do {
 773                 seq = read_seqbegin(&t->vtime_seqlock);
 774
 775                 gtime = t->gtime;
 776                 if (t->flags & PF_VCPU)
 777                         gtime += vtime_delta(t);
 778
 779         } while (read_seqretry(&t->vtime_seqlock, seq));
 780
 781         return gtime;
 782 }
 783
 784 /*
 785  * Fetch cputime raw values from fields of task_struct and
 786  * add up the pending nohz execution time since the last
 787  * cputime snapshot.
 788  */
 789 static void
 790 fetch_task_cputime(struct task_struct *t,
 791                    cputime_t *u_dst, cputime_t *s_dst,
 792                    cputime_t *u_src, cputime_t *s_src,
 793                    cputime_t *udelta, cputime_t *sdelta)
 794 {
 795         unsigned int seq;
 796         unsigned long long delta;
 797
 798         do {
 799                 *udelta = 0;
 800                 *sdelta = 0;
 801
 802                 seq = read_seqbegin(&t->vtime_seqlock);
 803
 804                 if (u_dst)
 805                         *u_dst = *u_src;
 806                 if (s_dst)
 807                         *s_dst = *s_src;
 808
 809                 /* Task is sleeping, nothing to add */
 810                 if (t->vtime_snap_whence == VTIME_SLEEPING ||
 811                     is_idle_task(t))
 812                         continue;
 813
 814                 delta = vtime_delta(t);
 815
 816                 /*
 817                  * Task runs either in user or kernel space, add pending nohz time to
 818                  * the right place.
 819                  */
 820                 if (t->vtime_snap_whence == VTIME_USER || t->flags & PF_VCPU) {
 821                         *udelta = delta;
 822                 } else {
 823                         if (t->vtime_snap_whence == VTIME_SYS)
 824                                 *sdelta = delta;
 825                 }
 826         } while (read_seqretry(&t->vtime_seqlock, seq));
 827 }
 828
 829
 830 void task_cputime(struct task_struct *t, cputime_t *utime, cputime_t *stime)
 831 {
 832         cputime_t udelta, sdelta;
 833
 834         fetch_task_cputime(t, utime, stime, &t->utime,
 835                            &t->stime, &udelta, &sdelta);
 836         if (utime)
 837                 *utime += udelta;
 838         if (stime)
 839                 *stime += sdelta;
 840 }
 841
 842 void task_cputime_scaled(struct task_struct *t,
 843                          cputime_t *utimescaled, cputime_t *stimescaled)
 844 {
 845         cputime_t udelta, sdelta;
 846
 847         fetch_task_cputime(t, utimescaled, stimescaled,
 848                            &t->utimescaled, &t->stimescaled, &udelta, &sdelta);
 849         if (utimescaled)
 850                 *utimescaled += cputime_to_scaled(udelta);
 851         if (stimescaled)
 852                 *stimescaled += cputime_to_scaled(sdelta);
 853 }
 854 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */