kernel/time/posix-cpu-timers.c

   1 /*
   2  * Implement CPU time clocks for the POSIX clock interface.
   3  */
   4
   5 #include <linux/sched/signal.h>
   6 #include <linux/sched/cputime.h>
   7 #include <linux/posix-timers.h>
   8 #include <linux/errno.h>
   9 #include <linux/math64.h>
  10 #include <linux/uaccess.h>
  11 #include <linux/kernel_stat.h>
  12 #include <trace/events/timer.h>
  13 #include <linux/tick.h>
  14 #include <linux/workqueue.h>
  15
  16 /*
  17  * Called after updating RLIMIT_CPU to run cpu timer and update
  18  * tsk->signal->cputime_expires expiration cache if necessary. Needs
  19  * siglock protection since other code may update expiration cache as
  20  * well.
  21  */
  22 void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new)
  23 {
  24         u64 nsecs = rlim_new * NSEC_PER_SEC;
  25
  26         spin_lock_irq(&task->sighand->siglock);
  27         set_process_cpu_timer(task, CPUCLOCK_PROF, &nsecs, NULL);
  28         spin_unlock_irq(&task->sighand->siglock);
  29 }
  30
  31 static int check_clock(const clockid_t which_clock)
  32 {
  33         int error = 0;
  34         struct task_struct *p;
  35         const pid_t pid = CPUCLOCK_PID(which_clock);
  36
  37         if (CPUCLOCK_WHICH(which_clock) >= CPUCLOCK_MAX)
  38                 return -EINVAL;
  39
  40         if (pid == 0)
  41                 return 0;
  42
  43         rcu_read_lock();
  44         p = find_task_by_vpid(pid);
  45         if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ?
  46                    same_thread_group(p, current) : has_group_leader_pid(p))) {
  47                 error = -EINVAL;
  48         }
  49         rcu_read_unlock();
  50
  51         return error;
  52 }
  53
  54 /*
  55  * Update expiry time from increment, and increase overrun count,
  56  * given the current clock sample.
  57  */
  58 static void bump_cpu_timer(struct k_itimer *timer, u64 now)
  59 {
  60         int i;
  61         u64 delta, incr;
  62
  63         if (timer->it.cpu.incr == 0)
  64                 return;
  65
  66         if (now < timer->it.cpu.expires)
  67                 return;
  68
  69         incr = timer->it.cpu.incr;
  70         delta = now + incr - timer->it.cpu.expires;
  71
  72         /* Don't use (incr*2 < delta), incr*2 might overflow. */
  73         for (i = 0; incr < delta - incr; i++)
  74                 incr = incr << 1;
  75
  76         for (; i >= 0; incr >>= 1, i--) {
  77                 if (delta < incr)
  78                         continue;
  79
  80                 timer->it.cpu.expires += incr;
  81                 timer->it_overrun += 1 << i;
  82                 delta -= incr;
  83         }
  84 }
  85
  86 /**
  87  * task_cputime_zero - Check a task_cputime struct for all zero fields.
  88  *
  89  * @cputime:    The struct to compare.
  90  *
  91  * Checks @cputime to see if all fields are zero.  Returns true if all fields
  92  * are zero, false if any field is nonzero.
  93  */
  94 static inline int task_cputime_zero(const struct task_cputime *cputime)
  95 {
  96         if (!cputime->utime && !cputime->stime && !cputime->sum_exec_runtime)
  97                 return 1;
  98         return 0;
  99 }
 100
 101 static inline u64 prof_ticks(struct task_struct *p)
 102 {
 103         u64 utime, stime;
 104
 105         task_cputime(p, &utime, &stime);
 106
 107         return utime + stime;
 108 }
 109 static inline u64 virt_ticks(struct task_struct *p)
 110 {
 111         u64 utime, stime;
 112
 113         task_cputime(p, &utime, &stime);
 114
 115         return utime;
 116 }
 117
 118 static int
 119 posix_cpu_clock_getres(const clockid_t which_clock, struct timespec64 *tp)
 120 {
 121         int error = check_clock(which_clock);
 122         if (!error) {
 123                 tp->tv_sec = 0;
 124                 tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ);
 125                 if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) {
 126                         /*
 127                          * If sched_clock is using a cycle counter, we
 128                          * don't have any idea of its true resolution
 129                          * exported, but it is much more than 1s/HZ.
 130                          */
 131                         tp->tv_nsec = 1;
 132                 }
 133         }
 134         return error;
 135 }
 136
 137 static int
 138 posix_cpu_clock_set(const clockid_t which_clock, const struct timespec64 *tp)
 139 {
 140         /*
 141          * You can never reset a CPU clock, but we check for other errors
 142          * in the call before failing with EPERM.
 143          */
 144         int error = check_clock(which_clock);
 145         if (error == 0) {
 146                 error = -EPERM;
 147         }
 148         return error;
 149 }
 150
 151
 152 /*
 153  * Sample a per-thread clock for the given task.
 154  */
 155 static int cpu_clock_sample(const clockid_t which_clock,
 156                             struct task_struct *p, u64 *sample)
 157 {
 158         switch (CPUCLOCK_WHICH(which_clock)) {
 159         default:
 160                 return -EINVAL;
 161         case CPUCLOCK_PROF:
 162                 *sample = prof_ticks(p);
 163                 break;
 164         case CPUCLOCK_VIRT:
 165                 *sample = virt_ticks(p);
 166                 break;
 167         case CPUCLOCK_SCHED:
 168                 *sample = task_sched_runtime(p);
 169                 break;
 170         }
 171         return 0;
 172 }
 173
 174 /*
 175  * Set cputime to sum_cputime if sum_cputime > cputime. Use cmpxchg
 176  * to avoid race conditions with concurrent updates to cputime.
 177  */
 178 static inline void __update_gt_cputime(atomic64_t *cputime, u64 sum_cputime)
 179 {
 180         u64 curr_cputime;
 181 retry:
 182         curr_cputime = atomic64_read(cputime);
 183         if (sum_cputime > curr_cputime) {
 184                 if (atomic64_cmpxchg(cputime, curr_cputime, sum_cputime) != curr_cputime)
 185                         goto retry;
 186         }
 187 }
 188
 189 static void update_gt_cputime(struct task_cputime_atomic *cputime_atomic, struct task_cputime *sum)
 190 {
 191         __update_gt_cputime(&cputime_atomic->utime, sum->utime);
 192         __update_gt_cputime(&cputime_atomic->stime, sum->stime);
 193         __update_gt_cputime(&cputime_atomic->sum_exec_runtime, sum->sum_exec_runtime);
 194 }
 195
 196 /* Sample task_cputime_atomic values in "atomic_timers", store results in "times". */
 197 static inline void sample_cputime_atomic(struct task_cputime *times,
 198                                          struct task_cputime_atomic *atomic_times)
 199 {
 200         times->utime = atomic64_read(&atomic_times->utime);
 201         times->stime = atomic64_read(&atomic_times->stime);
 202         times->sum_exec_runtime = atomic64_read(&atomic_times->sum_exec_runtime);
 203 }
 204
 205 void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times)
 206 {
 207         struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
 208         struct task_cputime sum;
 209
 210         /* Check if cputimer isn't running. This is accessed without locking. */
 211         if (!READ_ONCE(cputimer->running)) {
 212                 /*
 213                  * The POSIX timer interface allows for absolute time expiry
 214                  * values through the TIMER_ABSTIME flag, therefore we have
 215                  * to synchronize the timer to the clock every time we start it.
 216                  */
 217                 thread_group_cputime(tsk, &sum);
 218                 update_gt_cputime(&cputimer->cputime_atomic, &sum);
 219
 220                 /*
 221                  * We're setting cputimer->running without a lock. Ensure
 222                  * this only gets written to in one operation. We set
 223                  * running after update_gt_cputime() as a small optimization,
 224                  * but barriers are not required because update_gt_cputime()
 225                  * can handle concurrent updates.
 226                  */
 227                 WRITE_ONCE(cputimer->running, true);
 228         }
 229         sample_cputime_atomic(times, &cputimer->cputime_atomic);
 230 }
 231
 232 /*
 233  * Sample a process (thread group) clock for the given group_leader task.
 234  * Must be called with task sighand lock held for safe while_each_thread()
 235  * traversal.
 236  */
 237 static int cpu_clock_sample_group(const clockid_t which_clock,
 238                                   struct task_struct *p,
 239                                   u64 *sample)
 240 {
 241         struct task_cputime cputime;
 242
 243         switch (CPUCLOCK_WHICH(which_clock)) {
 244         default:
 245                 return -EINVAL;
 246         case CPUCLOCK_PROF:
 247                 thread_group_cputime(p, &cputime);
 248                 *sample = cputime.utime + cputime.stime;
 249                 break;
 250         case CPUCLOCK_VIRT:
 251                 thread_group_cputime(p, &cputime);
 252                 *sample = cputime.utime;
 253                 break;
 254         case CPUCLOCK_SCHED:
 255                 thread_group_cputime(p, &cputime);
 256                 *sample = cputime.sum_exec_runtime;
 257                 break;
 258         }
 259         return 0;
 260 }
 261
 262 static int posix_cpu_clock_get_task(struct task_struct *tsk,
 263                                     const clockid_t which_clock,
 264                                     struct timespec64 *tp)
 265 {
 266         int err = -EINVAL;
 267         u64 rtn;
 268
 269         if (CPUCLOCK_PERTHREAD(which_clock)) {
 270                 if (same_thread_group(tsk, current))
 271                         err = cpu_clock_sample(which_clock, tsk, &rtn);
 272         } else {
 273                 if (tsk == current || thread_group_leader(tsk))
 274                         err = cpu_clock_sample_group(which_clock, tsk, &rtn);
 275         }
 276
 277         if (!err)
 278                 *tp = ns_to_timespec64(rtn);
 279
 280         return err;
 281 }
 282
 283
 284 static int posix_cpu_clock_get(const clockid_t which_clock, struct timespec64 *tp)
 285 {
 286         const pid_t pid = CPUCLOCK_PID(which_clock);
 287         int err = -EINVAL;
 288
 289         if (pid == 0) {
 290                 /*
 291                  * Special case constant value for our own clocks.
 292                  * We don't have to do any lookup to find ourselves.
 293                  */
 294                 err = posix_cpu_clock_get_task(current, which_clock, tp);
 295         } else {
 296                 /*
 297                  * Find the given PID, and validate that the caller
 298                  * should be able to see it.
 299                  */
 300                 struct task_struct *p;
 301                 rcu_read_lock();
 302                 p = find_task_by_vpid(pid);
 303                 if (p)
 304                         err = posix_cpu_clock_get_task(p, which_clock, tp);
 305                 rcu_read_unlock();
 306         }
 307
 308         return err;
 309 }
 310
 311 /*
 312  * Validate the clockid_t for a new CPU-clock timer, and initialize the timer.
 313  * This is called from sys_timer_create() and do_cpu_nanosleep() with the
 314  * new timer already all-zeros initialized.
 315  */
 316 static int posix_cpu_timer_create(struct k_itimer *new_timer)
 317 {
 318         int ret = 0;
 319         const pid_t pid = CPUCLOCK_PID(new_timer->it_clock);
 320         struct task_struct *p;
 321
 322         if (CPUCLOCK_WHICH(new_timer->it_clock) >= CPUCLOCK_MAX)
 323                 return -EINVAL;
 324
 325         INIT_LIST_HEAD(&new_timer->it.cpu.entry);
 326
 327         rcu_read_lock();
 328         if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {
 329                 if (pid == 0) {
 330                         p = current;
 331                 } else {
 332                         p = find_task_by_vpid(pid);
 333                         if (p && !same_thread_group(p, current))
 334                                 p = NULL;
 335                 }
 336         } else {
 337                 if (pid == 0) {
 338                         p = current->group_leader;
 339                 } else {
 340                         p = find_task_by_vpid(pid);
 341                         if (p && !has_group_leader_pid(p))
 342                                 p = NULL;
 343                 }
 344         }
 345         new_timer->it.cpu.task = p;
 346         if (p) {
 347                 get_task_struct(p);
 348         } else {
 349                 ret = -EINVAL;
 350         }
 351         rcu_read_unlock();
 352
 353         return ret;
 354 }
 355
 356 /*
 357  * Clean up a CPU-clock timer that is about to be destroyed.
 358  * This is called from timer deletion with the timer already locked.
 359  * If we return TIMER_RETRY, it's necessary to release the timer's lock
 360  * and try again.  (This happens when the timer is in the middle of firing.)
 361  */
 362 static int posix_cpu_timer_del(struct k_itimer *timer)
 363 {
 364         int ret = 0;
 365         unsigned long flags;
 366         struct sighand_struct *sighand;
 367         struct task_struct *p = timer->it.cpu.task;
 368
 369         WARN_ON_ONCE(p == NULL);
 370
 371         /*
 372          * Protect against sighand release/switch in exit/exec and process/
 373          * thread timer list entry concurrent read/writes.
 374          */
 375         sighand = lock_task_sighand(p, &flags);
 376         if (unlikely(sighand == NULL)) {
 377                 /*
 378                  * We raced with the reaping of the task.
 379                  * The deletion should have cleared us off the list.
 380                  */
 381                 WARN_ON_ONCE(!list_empty(&timer->it.cpu.entry));
 382         } else {
 383                 if (timer->it.cpu.firing)
 384                         ret = TIMER_RETRY;
 385                 else
 386                         list_del(&timer->it.cpu.entry);
 387
 388                 unlock_task_sighand(p, &flags);
 389         }
 390
 391         if (!ret)
 392                 put_task_struct(p);
 393
 394         return ret;
 395 }
 396
 397 static void cleanup_timers_list(struct list_head *head)
 398 {
 399         struct cpu_timer_list *timer, *next;
 400
 401         list_for_each_entry_safe(timer, next, head, entry)
 402                 list_del_init(&timer->entry);
 403 }
 404
 405 /*
 406  * Clean out CPU timers still ticking when a thread exited.  The task
 407  * pointer is cleared, and the expiry time is replaced with the residual
 408  * time for later timer_gettime calls to return.
 409  * This must be called with the siglock held.
 410  */
 411 static void cleanup_timers(struct list_head *head)
 412 {
 413         cleanup_timers_list(head);
 414         cleanup_timers_list(++head);
 415         cleanup_timers_list(++head);
 416 }
 417
 418 /*
 419  * These are both called with the siglock held, when the current thread
 420  * is being reaped.  When the final (leader) thread in the group is reaped,
 421  * posix_cpu_timers_exit_group will be called after posix_cpu_timers_exit.
 422  */
 423 void posix_cpu_timers_exit(struct task_struct *tsk)
 424 {
 425         cleanup_timers(tsk->cpu_timers);
 426 }
 427 void posix_cpu_timers_exit_group(struct task_struct *tsk)
 428 {
 429         cleanup_timers(tsk->signal->cpu_timers);
 430 }
 431
 432 static inline int expires_gt(u64 expires, u64 new_exp)
 433 {
 434         return expires == 0 || expires > new_exp;
 435 }
 436
 437 /*
 438  * Insert the timer on the appropriate list before any timers that
 439  * expire later.  This must be called with the sighand lock held.
 440  */
 441 static void arm_timer(struct k_itimer *timer)
 442 {
 443         struct task_struct *p = timer->it.cpu.task;
 444         struct list_head *head, *listpos;
 445         struct task_cputime *cputime_expires;
 446         struct cpu_timer_list *const nt = &timer->it.cpu;
 447         struct cpu_timer_list *next;
 448
 449         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
 450                 head = p->cpu_timers;
 451                 cputime_expires = &p->cputime_expires;
 452         } else {
 453                 head = p->signal->cpu_timers;
 454                 cputime_expires = &p->signal->cputime_expires;
 455         }
 456         head += CPUCLOCK_WHICH(timer->it_clock);
 457
 458         listpos = head;
 459         list_for_each_entry(next, head, entry) {
 460                 if (nt->expires < next->expires)
 461                         break;
 462                 listpos = &next->entry;
 463         }
 464         list_add(&nt->entry, listpos);
 465
 466         if (listpos == head) {
 467                 u64 exp = nt->expires;
 468
 469                 /*
 470                  * We are the new earliest-expiring POSIX 1.b timer, hence
 471                  * need to update expiration cache. Take into account that
 472                  * for process timers we share expiration cache with itimers
 473                  * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME.
 474                  */
 475
 476                 switch (CPUCLOCK_WHICH(timer->it_clock)) {
 477                 case CPUCLOCK_PROF:
 478                         if (expires_gt(cputime_expires->prof_exp, exp))
 479                                 cputime_expires->prof_exp = exp;
 480                         break;
 481                 case CPUCLOCK_VIRT:
 482                         if (expires_gt(cputime_expires->virt_exp, exp))
 483                                 cputime_expires->virt_exp = exp;
 484                         break;
 485                 case CPUCLOCK_SCHED:
 486                         if (expires_gt(cputime_expires->sched_exp, exp))
 487                                 cputime_expires->sched_exp = exp;
 488                         break;
 489                 }
 490                 if (CPUCLOCK_PERTHREAD(timer->it_clock))
 491                         tick_dep_set_task(p, TICK_DEP_BIT_POSIX_TIMER);
 492                 else
 493                         tick_dep_set_signal(p->signal, TICK_DEP_BIT_POSIX_TIMER);
 494         }
 495 }
 496
 497 /*
 498  * The timer is locked, fire it and arrange for its reload.
 499  */
 500 static void cpu_timer_fire(struct k_itimer *timer)
 501 {
 502         if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) {
 503                 /*
 504                  * User don't want any signal.
 505                  */
 506                 timer->it.cpu.expires = 0;
 507         } else if (unlikely(timer->sigq == NULL)) {
 508                 /*
 509                  * This a special case for clock_nanosleep,
 510                  * not a normal timer from sys_timer_create.
 511                  */
 512                 wake_up_process(timer->it_process);
 513                 timer->it.cpu.expires = 0;
 514         } else if (timer->it.cpu.incr == 0) {
 515                 /*
 516                  * One-shot timer.  Clear it as soon as it's fired.
 517                  */
 518                 posix_timer_event(timer, 0);
 519                 timer->it.cpu.expires = 0;
 520         } else if (posix_timer_event(timer, ++timer->it_requeue_pending)) {
 521                 /*
 522                  * The signal did not get queued because the signal
 523                  * was ignored, so we won't get any callback to
 524                  * reload the timer.  But we need to keep it
 525                  * ticking in case the signal is deliverable next time.
 526                  */
 527                 posix_cpu_timer_schedule(timer);
 528         }
 529 }
 530
 531 /*
 532  * Sample a process (thread group) timer for the given group_leader task.
 533  * Must be called with task sighand lock held for safe while_each_thread()
 534  * traversal.
 535  */
 536 static int cpu_timer_sample_group(const clockid_t which_clock,
 537                                   struct task_struct *p, u64 *sample)
 538 {
 539         struct task_cputime cputime;
 540
 541         thread_group_cputimer(p, &cputime);
 542         switch (CPUCLOCK_WHICH(which_clock)) {
 543         default:
 544                 return -EINVAL;
 545         case CPUCLOCK_PROF:
 546                 *sample = cputime.utime + cputime.stime;
 547                 break;
 548         case CPUCLOCK_VIRT:
 549                 *sample = cputime.utime;
 550                 break;
 551         case CPUCLOCK_SCHED:
 552                 *sample = cputime.sum_exec_runtime;
 553                 break;
 554         }
 555         return 0;
 556 }
 557
 558 /*
 559  * Guts of sys_timer_settime for CPU timers.
 560  * This is called with the timer locked and interrupts disabled.
 561  * If we return TIMER_RETRY, it's necessary to release the timer's lock
 562  * and try again.  (This happens when the timer is in the middle of firing.)
 563  */
 564 static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags,
 565                                struct itimerspec64 *new, struct itimerspec64 *old)
 566 {
 567         unsigned long flags;
 568         struct sighand_struct *sighand;
 569         struct task_struct *p = timer->it.cpu.task;
 570         u64 old_expires, new_expires, old_incr, val;
 571         int ret;
 572
 573         WARN_ON_ONCE(p == NULL);
 574
 575         new_expires = timespec64_to_ns(&new->it_value);
 576
 577         /*
 578          * Protect against sighand release/switch in exit/exec and p->cpu_timers
 579          * and p->signal->cpu_timers read/write in arm_timer()
 580          */
 581         sighand = lock_task_sighand(p, &flags);
 582         /*
 583          * If p has just been reaped, we can no
 584          * longer get any information about it at all.
 585          */
 586         if (unlikely(sighand == NULL)) {
 587                 return -ESRCH;
 588         }
 589
 590         /*
 591          * Disarm any old timer after extracting its expiry time.
 592          */
 593         WARN_ON_ONCE(!irqs_disabled());
 594
 595         ret = 0;
 596         old_incr = timer->it.cpu.incr;
 597         old_expires = timer->it.cpu.expires;
 598         if (unlikely(timer->it.cpu.firing)) {
 599                 timer->it.cpu.firing = -1;
 600                 ret = TIMER_RETRY;
 601         } else
 602                 list_del_init(&timer->it.cpu.entry);
 603
 604         /*
 605          * We need to sample the current value to convert the new
 606          * value from to relative and absolute, and to convert the
 607          * old value from absolute to relative.  To set a process
 608          * timer, we need a sample to balance the thread expiry
 609          * times (in arm_timer).  With an absolute time, we must
 610          * check if it's already passed.  In short, we need a sample.
 611          */
 612         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
 613                 cpu_clock_sample(timer->it_clock, p, &val);
 614         } else {
 615                 cpu_timer_sample_group(timer->it_clock, p, &val);
 616         }
 617
 618         if (old) {
 619                 if (old_expires == 0) {
 620                         old->it_value.tv_sec = 0;
 621                         old->it_value.tv_nsec = 0;
 622                 } else {
 623                         /*
 624                          * Update the timer in case it has
 625                          * overrun already.  If it has,
 626                          * we'll report it as having overrun
 627                          * and with the next reloaded timer
 628                          * already ticking, though we are
 629                          * swallowing that pending
 630                          * notification here to install the
 631                          * new setting.
 632                          */
 633                         bump_cpu_timer(timer, val);
 634                         if (val < timer->it.cpu.expires) {
 635                                 old_expires = timer->it.cpu.expires - val;
 636                                 old->it_value = ns_to_timespec64(old_expires);
 637                         } else {
 638                                 old->it_value.tv_nsec = 1;
 639                                 old->it_value.tv_sec = 0;
 640                         }
 641                 }
 642         }
 643
 644         if (unlikely(ret)) {
 645                 /*
 646                  * We are colliding with the timer actually firing.
 647                  * Punt after filling in the timer's old value, and
 648                  * disable this firing since we are already reporting
 649                  * it as an overrun (thanks to bump_cpu_timer above).
 650                  */
 651                 unlock_task_sighand(p, &flags);
 652                 goto out;
 653         }
 654
 655         if (new_expires != 0 && !(timer_flags & TIMER_ABSTIME)) {
 656                 new_expires += val;
 657         }
 658
 659         /*
 660          * Install the new expiry time (or zero).
 661          * For a timer with no notification action, we don't actually
 662          * arm the timer (we'll just fake it for timer_gettime).
 663          */
 664         timer->it.cpu.expires = new_expires;
 665         if (new_expires != 0 && val < new_expires) {
 666                 arm_timer(timer);
 667         }
 668
 669         unlock_task_sighand(p, &flags);
 670         /*
 671          * Install the new reload setting, and
 672          * set up the signal and overrun bookkeeping.
 673          */
 674         timer->it.cpu.incr = timespec64_to_ns(&new->it_interval);
 675
 676         /*
 677          * This acts as a modification timestamp for the timer,
 678          * so any automatic reload attempt will punt on seeing
 679          * that we have reset the timer manually.
 680          */
 681         timer->it_requeue_pending = (timer->it_requeue_pending + 2) &
 682                 ~REQUEUE_PENDING;
 683         timer->it_overrun_last = 0;
 684         timer->it_overrun = -1;
 685
 686         if (new_expires != 0 && !(val < new_expires)) {
 687                 /*
 688                  * The designated time already passed, so we notify
 689                  * immediately, even if the thread never runs to
 690                  * accumulate more time on this clock.
 691                  */
 692                 cpu_timer_fire(timer);
 693         }
 694
 695         ret = 0;
 696  out:
 697         if (old)
 698                 old->it_interval = ns_to_timespec64(old_incr);
 699
 700         return ret;
 701 }
 702
 703 static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec64 *itp)
 704 {
 705         u64 now;
 706         struct task_struct *p = timer->it.cpu.task;
 707
 708         WARN_ON_ONCE(p == NULL);
 709
 710         /*
 711          * Easy part: convert the reload time.
 712          */
 713         itp->it_interval = ns_to_timespec64(timer->it.cpu.incr);
 714
 715         if (timer->it.cpu.expires == 0) {       /* Timer not armed at all.  */
 716                 itp->it_value.tv_sec = itp->it_value.tv_nsec = 0;
 717                 return;
 718         }
 719
 720         /*
 721          * Sample the clock to take the difference with the expiry time.
 722          */
 723         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
 724                 cpu_clock_sample(timer->it_clock, p, &now);
 725         } else {
 726                 struct sighand_struct *sighand;
 727                 unsigned long flags;
 728
 729                 /*
 730                  * Protect against sighand release/switch in exit/exec and
 731                  * also make timer sampling safe if it ends up calling
 732                  * thread_group_cputime().
 733                  */
 734                 sighand = lock_task_sighand(p, &flags);
 735                 if (unlikely(sighand == NULL)) {
 736                         /*
 737                          * The process has been reaped.
 738                          * We can't even collect a sample any more.
 739                          * Call the timer disarmed, nothing else to do.
 740                          */
 741                         timer->it.cpu.expires = 0;
 742                         itp->it_value = ns_to_timespec64(timer->it.cpu.expires);
 743                         return;
 744                 } else {
 745                         cpu_timer_sample_group(timer->it_clock, p, &now);
 746                         unlock_task_sighand(p, &flags);
 747                 }
 748         }
 749
 750         if (now < timer->it.cpu.expires) {
 751                 itp->it_value = ns_to_timespec64(timer->it.cpu.expires - now);
 752         } else {
 753                 /*
 754                  * The timer should have expired already, but the firing
 755                  * hasn't taken place yet.  Say it's just about to expire.
 756                  */
 757                 itp->it_value.tv_nsec = 1;
 758                 itp->it_value.tv_sec = 0;
 759         }
 760 }
 761
 762 static unsigned long long
 763 check_timers_list(struct list_head *timers,
 764                   struct list_head *firing,
 765                   unsigned long long curr)
 766 {
 767         int maxfire = 20;
 768
 769         while (!list_empty(timers)) {
 770                 struct cpu_timer_list *t;
 771
 772                 t = list_first_entry(timers, struct cpu_timer_list, entry);
 773
 774                 if (!--maxfire || curr < t->expires)
 775                         return t->expires;
 776
 777                 t->firing = 1;
 778                 list_move_tail(&t->entry, firing);
 779         }
 780
 781         return 0;
 782 }
 783
 784 /*
 785  * Check for any per-thread CPU timers that have fired and move them off
 786  * the tsk->cpu_timers[N] list onto the firing list.  Here we update the
 787  * tsk->it_*_expires values to reflect the remaining thread CPU timers.
 788  */
 789 static void check_thread_timers(struct task_struct *tsk,
 790                                 struct list_head *firing)
 791 {
 792         struct list_head *timers = tsk->cpu_timers;
 793         struct signal_struct *const sig = tsk->signal;
 794         struct task_cputime *tsk_expires = &tsk->cputime_expires;
 795         u64 expires;
 796         unsigned long soft;
 797
 798         /*
 799          * If cputime_expires is zero, then there are no active
 800          * per thread CPU timers.
 801          */
 802         if (task_cputime_zero(&tsk->cputime_expires))
 803                 return;
 804
 805         expires = check_timers_list(timers, firing, prof_ticks(tsk));
 806         tsk_expires->prof_exp = expires;
 807
 808         expires = check_timers_list(++timers, firing, virt_ticks(tsk));
 809         tsk_expires->virt_exp = expires;
 810
 811         tsk_expires->sched_exp = check_timers_list(++timers, firing,
 812                                                    tsk->se.sum_exec_runtime);
 813
 814         /*
 815          * Check for the special case thread timers.
 816          */
 817         soft = READ_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_cur);
 818         if (soft != RLIM_INFINITY) {
 819                 unsigned long hard =
 820                         READ_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_max);
 821
 822                 if (hard != RLIM_INFINITY &&
 823                     tsk->rt.timeout > DIV_ROUND_UP(hard, USEC_PER_SEC/HZ)) {
 824                         /*
 825                          * At the hard limit, we just die.
 826                          * No need to calculate anything else now.
 827                          */
 828                         if (print_fatal_signals) {
 829                                 pr_info("CPU Watchdog Timeout (hard): %s[%d]\n",
 830                                         tsk->comm, task_pid_nr(tsk));
 831                         }
 832                         __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
 833                         return;
 834                 }
 835                 if (tsk->rt.timeout > DIV_ROUND_UP(soft, USEC_PER_SEC/HZ)) {
 836                         /*
 837                          * At the soft limit, send a SIGXCPU every second.
 838                          */
 839                         if (soft < hard) {
 840                                 soft += USEC_PER_SEC;
 841                                 sig->rlim[RLIMIT_RTTIME].rlim_cur = soft;
 842                         }
 843                         if (print_fatal_signals) {
 844                                 pr_info("RT Watchdog Timeout (soft): %s[%d]\n",
 845                                         tsk->comm, task_pid_nr(tsk));
 846                         }
 847                         __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
 848                 }
 849         }
 850         if (task_cputime_zero(tsk_expires))
 851                 tick_dep_clear_task(tsk, TICK_DEP_BIT_POSIX_TIMER);
 852 }
 853
 854 static inline void stop_process_timers(struct signal_struct *sig)
 855 {
 856         struct thread_group_cputimer *cputimer = &sig->cputimer;
 857
 858         /* Turn off cputimer->running. This is done without locking. */
 859         WRITE_ONCE(cputimer->running, false);
 860         tick_dep_clear_signal(sig, TICK_DEP_BIT_POSIX_TIMER);
 861 }
 862
 863 static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
 864                              u64 *expires, u64 cur_time, int signo)
 865 {
 866         if (!it->expires)
 867                 return;
 868
 869         if (cur_time >= it->expires) {
 870                 if (it->incr)
 871                         it->expires += it->incr;
 872                 else
 873                         it->expires = 0;
 874
 875                 trace_itimer_expire(signo == SIGPROF ?
 876                                     ITIMER_PROF : ITIMER_VIRTUAL,
 877                                     tsk->signal->leader_pid, cur_time);
 878                 __group_send_sig_info(signo, SEND_SIG_PRIV, tsk);
 879         }
 880
 881         if (it->expires && (!*expires || it->expires < *expires))
 882                 *expires = it->expires;
 883 }
 884
 885 /*
 886  * Check for any per-thread CPU timers that have fired and move them
 887  * off the tsk->*_timers list onto the firing list.  Per-thread timers
 888  * have already been taken off.
 889  */
 890 static void check_process_timers(struct task_struct *tsk,
 891                                  struct list_head *firing)
 892 {
 893         struct signal_struct *const sig = tsk->signal;
 894         u64 utime, ptime, virt_expires, prof_expires;
 895         u64 sum_sched_runtime, sched_expires;
 896         struct list_head *timers = sig->cpu_timers;
 897         struct task_cputime cputime;
 898         unsigned long soft;
 899
 900         /*
 901          * If cputimer is not running, then there are no active
 902          * process wide timers (POSIX 1.b, itimers, RLIMIT_CPU).
 903          */
 904         if (!READ_ONCE(tsk->signal->cputimer.running))
 905                 return;
 906
 907         /*
 908          * Signify that a thread is checking for process timers.
 909          * Write access to this field is protected by the sighand lock.
 910          */
 911         sig->cputimer.checking_timer = true;
 912
 913         /*
 914          * Collect the current process totals.
 915          */
 916         thread_group_cputimer(tsk, &cputime);
 917         utime = cputime.utime;
 918         ptime = utime + cputime.stime;
 919         sum_sched_runtime = cputime.sum_exec_runtime;
 920
 921         prof_expires = check_timers_list(timers, firing, ptime);
 922         virt_expires = check_timers_list(++timers, firing, utime);
 923         sched_expires = check_timers_list(++timers, firing, sum_sched_runtime);
 924
 925         /*
 926          * Check for the special case process timers.
 927          */
 928         check_cpu_itimer(tsk, &sig->it[CPUCLOCK_PROF], &prof_expires, ptime,
 929                          SIGPROF);
 930         check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT], &virt_expires, utime,
 931                          SIGVTALRM);
 932         soft = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
 933         if (soft != RLIM_INFINITY) {
 934                 unsigned long psecs = div_u64(ptime, NSEC_PER_SEC);
 935                 unsigned long hard =
 936                         READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_max);
 937                 u64 x;
 938                 if (psecs >= hard) {
 939                         /*
 940                          * At the hard limit, we just die.
 941                          * No need to calculate anything else now.
 942                          */
 943                         if (print_fatal_signals) {
 944                                 pr_info("RT Watchdog Timeout (hard): %s[%d]\n",
 945                                         tsk->comm, task_pid_nr(tsk));
 946                         }
 947                         __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk);
 948                         return;
 949                 }
 950                 if (psecs >= soft) {
 951                         /*
 952                          * At the soft limit, send a SIGXCPU every second.
 953                          */
 954                         if (print_fatal_signals) {
 955                                 pr_info("CPU Watchdog Timeout (soft): %s[%d]\n",
 956                                         tsk->comm, task_pid_nr(tsk));
 957                         }
 958                         __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
 959                         if (soft < hard) {
 960                                 soft++;
 961                                 sig->rlim[RLIMIT_CPU].rlim_cur = soft;
 962                         }
 963                 }
 964                 x = soft * NSEC_PER_SEC;
 965                 if (!prof_expires || x < prof_expires)
 966                         prof_expires = x;
 967         }
 968
 969         sig->cputime_expires.prof_exp = prof_expires;
 970         sig->cputime_expires.virt_exp = virt_expires;
 971         sig->cputime_expires.sched_exp = sched_expires;
 972         if (task_cputime_zero(&sig->cputime_expires))
 973                 stop_process_timers(sig);
 974
 975         sig->cputimer.checking_timer = false;
 976 }
 977
 978 /*
 979  * This is called from the signal code (via do_schedule_next_timer)
 980  * when the last timer signal was delivered and we have to reload the timer.
 981  */
 982 void posix_cpu_timer_schedule(struct k_itimer *timer)
 983 {
 984         struct sighand_struct *sighand;
 985         unsigned long flags;
 986         struct task_struct *p = timer->it.cpu.task;
 987         u64 now;
 988
 989         WARN_ON_ONCE(p == NULL);
 990
 991         /*
 992          * Fetch the current sample and update the timer's expiry time.
 993          */
 994         if (CPUCLOCK_PERTHREAD(timer->it_clock)) {
 995                 cpu_clock_sample(timer->it_clock, p, &now);
 996                 bump_cpu_timer(timer, now);
 997                 if (unlikely(p->exit_state))
 998                         goto out;
 999
1000                 /* Protect timer list r/w in arm_timer() */
1001                 sighand = lock_task_sighand(p, &flags);
1002                 if (!sighand)
1003                         goto out;
1004         } else {
1005                 /*
1006                  * Protect arm_timer() and timer sampling in case of call to
1007                  * thread_group_cputime().
1008                  */
1009                 sighand = lock_task_sighand(p, &flags);
1010                 if (unlikely(sighand == NULL)) {
1011                         /*
1012                          * The process has been reaped.
1013                          * We can't even collect a sample any more.
1014                          */
1015                         timer->it.cpu.expires = 0;
1016                         goto out;
1017                 } else if (unlikely(p->exit_state) && thread_group_empty(p)) {
1018                         unlock_task_sighand(p, &flags);
1019                         /* Optimizations: if the process is dying, no need to rearm */
1020                         goto out;
1021                 }
1022                 cpu_timer_sample_group(timer->it_clock, p, &now);
1023                 bump_cpu_timer(timer, now);
1024                 /* Leave the sighand locked for the call below.  */
1025         }
1026
1027         /*
1028          * Now re-arm for the new expiry time.
1029          */
1030         WARN_ON_ONCE(!irqs_disabled());
1031         arm_timer(timer);
1032         unlock_task_sighand(p, &flags);
1033
1034 out:
1035         timer->it_overrun_last = timer->it_overrun;
1036         timer->it_overrun = -1;
1037         ++timer->it_requeue_pending;
1038 }
1039
1040 /**
1041  * task_cputime_expired - Compare two task_cputime entities.
1042  *
1043  * @sample:     The task_cputime structure to be checked for expiration.
1044  * @expires:    Expiration times, against which @sample will be checked.
1045  *
1046  * Checks @sample against @expires to see if any field of @sample has expired.
1047  * Returns true if any field of the former is greater than the corresponding
1048  * field of the latter if the latter field is set.  Otherwise returns false.
1049  */
1050 static inline int task_cputime_expired(const struct task_cputime *sample,
1051                                         const struct task_cputime *expires)
1052 {
1053         if (expires->utime && sample->utime >= expires->utime)
1054                 return 1;
1055         if (expires->stime && sample->utime + sample->stime >= expires->stime)
1056                 return 1;
1057         if (expires->sum_exec_runtime != 0 &&
1058             sample->sum_exec_runtime >= expires->sum_exec_runtime)
1059                 return 1;
1060         return 0;
1061 }
1062
1063 /**
1064  * fastpath_timer_check - POSIX CPU timers fast path.
1065  *
1066  * @tsk:        The task (thread) being checked.
1067  *
1068  * Check the task and thread group timers.  If both are zero (there are no
1069  * timers set) return false.  Otherwise snapshot the task and thread group
1070  * timers and compare them with the corresponding expiration times.  Return
1071  * true if a timer has expired, else return false.
1072  */
1073 static inline int fastpath_timer_check(struct task_struct *tsk)
1074 {
1075         struct signal_struct *sig;
1076
1077         if (!task_cputime_zero(&tsk->cputime_expires)) {
1078                 struct task_cputime task_sample;
1079
1080                 task_cputime(tsk, &task_sample.utime, &task_sample.stime);
1081                 task_sample.sum_exec_runtime = tsk->se.sum_exec_runtime;
1082                 if (task_cputime_expired(&task_sample, &tsk->cputime_expires))
1083                         return 1;
1084         }
1085
1086         sig = tsk->signal;
1087         /*
1088          * Check if thread group timers expired when the cputimer is
1089          * running and no other thread in the group is already checking
1090          * for thread group cputimers. These fields are read without the
1091          * sighand lock. However, this is fine because this is meant to
1092          * be a fastpath heuristic to determine whether we should try to
1093          * acquire the sighand lock to check/handle timers.
1094          *
1095          * In the worst case scenario, if 'running' or 'checking_timer' gets
1096          * set but the current thread doesn't see the change yet, we'll wait
1097          * until the next thread in the group gets a scheduler interrupt to
1098          * handle the timer. This isn't an issue in practice because these
1099          * types of delays with signals actually getting sent are expected.
1100          */
1101         if (READ_ONCE(sig->cputimer.running) &&
1102             !READ_ONCE(sig->cputimer.checking_timer)) {
1103                 struct task_cputime group_sample;
1104
1105                 sample_cputime_atomic(&group_sample, &sig->cputimer.cputime_atomic);
1106
1107                 if (task_cputime_expired(&group_sample, &sig->cputime_expires))
1108                         return 1;
1109         }
1110
1111         return 0;
1112 }
1113
1114 /*
1115  * This is called from the timer interrupt handler.  The irq handler has
1116  * already updated our counts.  We need to check if any timers fire now.
1117  * Interrupts are disabled.
1118  */
1119 void run_posix_cpu_timers(struct task_struct *tsk)
1120 {
1121         LIST_HEAD(firing);
1122         struct k_itimer *timer, *next;
1123         unsigned long flags;
1124
1125         WARN_ON_ONCE(!irqs_disabled());
1126
1127         /*
1128          * The fast path checks that there are no expired thread or thread
1129          * group timers.  If that's so, just return.
1130          */
1131         if (!fastpath_timer_check(tsk))
1132                 return;
1133
1134         if (!lock_task_sighand(tsk, &flags))
1135                 return;
1136         /*
1137          * Here we take off tsk->signal->cpu_timers[N] and
1138          * tsk->cpu_timers[N] all the timers that are firing, and
1139          * put them on the firing list.
1140          */
1141         check_thread_timers(tsk, &firing);
1142
1143         check_process_timers(tsk, &firing);
1144
1145         /*
1146          * We must release these locks before taking any timer's lock.
1147          * There is a potential race with timer deletion here, as the
1148          * siglock now protects our private firing list.  We have set
1149          * the firing flag in each timer, so that a deletion attempt
1150          * that gets the timer lock before we do will give it up and
1151          * spin until we've taken care of that timer below.
1152          */
1153         unlock_task_sighand(tsk, &flags);
1154
1155         /*
1156          * Now that all the timers on our list have the firing flag,
1157          * no one will touch their list entries but us.  We'll take
1158          * each timer's lock before clearing its firing flag, so no
1159          * timer call will interfere.
1160          */
1161         list_for_each_entry_safe(timer, next, &firing, it.cpu.entry) {
1162                 int cpu_firing;
1163
1164                 spin_lock(&timer->it_lock);
1165                 list_del_init(&timer->it.cpu.entry);
1166                 cpu_firing = timer->it.cpu.firing;
1167                 timer->it.cpu.firing = 0;
1168                 /*
1169                  * The firing flag is -1 if we collided with a reset
1170                  * of the timer, which already reported this
1171                  * almost-firing as an overrun.  So don't generate an event.
1172                  */
1173                 if (likely(cpu_firing >= 0))
1174                         cpu_timer_fire(timer);
1175                 spin_unlock(&timer->it_lock);
1176         }
1177 }
1178
1179 /*
1180  * Set one of the process-wide special case CPU timers or RLIMIT_CPU.
1181  * The tsk->sighand->siglock must be held by the caller.
1182  */
1183 void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx,
1184                            u64 *newval, u64 *oldval)
1185 {
1186         u64 now;
1187
1188         WARN_ON_ONCE(clock_idx == CPUCLOCK_SCHED);
1189         cpu_timer_sample_group(clock_idx, tsk, &now);
1190
1191         if (oldval) {
1192                 /*
1193                  * We are setting itimer. The *oldval is absolute and we update
1194                  * it to be relative, *newval argument is relative and we update
1195                  * it to be absolute.
1196                  */
1197                 if (*oldval) {
1198                         if (*oldval <= now) {
1199                                 /* Just about to fire. */
1200                                 *oldval = TICK_NSEC;
1201                         } else {
1202                                 *oldval -= now;
1203                         }
1204                 }
1205
1206                 if (!*newval)
1207                         return;
1208                 *newval += now;
1209         }
1210
1211         /*
1212          * Update expiration cache if we are the earliest timer, or eventually
1213          * RLIMIT_CPU limit is earlier than prof_exp cpu timer expire.
1214          */
1215         switch (clock_idx) {
1216         case CPUCLOCK_PROF:
1217                 if (expires_gt(tsk->signal->cputime_expires.prof_exp, *newval))
1218                         tsk->signal->cputime_expires.prof_exp = *newval;
1219                 break;
1220         case CPUCLOCK_VIRT:
1221                 if (expires_gt(tsk->signal->cputime_expires.virt_exp, *newval))
1222                         tsk->signal->cputime_expires.virt_exp = *newval;
1223                 break;
1224         }
1225
1226         tick_dep_set_signal(tsk->signal, TICK_DEP_BIT_POSIX_TIMER);
1227 }
1228
1229 static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
1230                             struct timespec64 *rqtp, struct itimerspec64 *it)
1231 {
1232         struct k_itimer timer;
1233         int error;
1234
1235         /*
1236          * Set up a temporary timer and then wait for it to go off.
1237          */
1238         memset(&timer, 0, sizeof timer);
1239         spin_lock_init(&timer.it_lock);
1240         timer.it_clock = which_clock;
1241         timer.it_overrun = -1;
1242         error = posix_cpu_timer_create(&timer);
1243         timer.it_process = current;
1244         if (!error) {
1245                 static struct itimerspec64 zero_it;
1246
1247                 memset(it, 0, sizeof *it);
1248                 it->it_value = *rqtp;
1249
1250                 spin_lock_irq(&timer.it_lock);
1251                 error = posix_cpu_timer_set(&timer, flags, it, NULL);
1252                 if (error) {
1253                         spin_unlock_irq(&timer.it_lock);
1254                         return error;
1255                 }
1256
1257                 while (!signal_pending(current)) {
1258                         if (timer.it.cpu.expires == 0) {
1259                                 /*
1260                                  * Our timer fired and was reset, below
1261                                  * deletion can not fail.
1262                                  */
1263                                 posix_cpu_timer_del(&timer);
1264                                 spin_unlock_irq(&timer.it_lock);
1265                                 return 0;
1266                         }
1267
1268                         /*
1269                          * Block until cpu_timer_fire (or a signal) wakes us.
1270                          */
1271                         __set_current_state(TASK_INTERRUPTIBLE);
1272                         spin_unlock_irq(&timer.it_lock);
1273                         schedule();
1274                         spin_lock_irq(&timer.it_lock);
1275                 }
1276
1277                 /*
1278                  * We were interrupted by a signal.
1279                  */
1280                 *rqtp = ns_to_timespec64(timer.it.cpu.expires);
1281                 error = posix_cpu_timer_set(&timer, 0, &zero_it, it);
1282                 if (!error) {
1283                         /*
1284                          * Timer is now unarmed, deletion can not fail.
1285                          */
1286                         posix_cpu_timer_del(&timer);
1287                 }
1288                 spin_unlock_irq(&timer.it_lock);
1289
1290                 while (error == TIMER_RETRY) {
1291                         /*
1292                          * We need to handle case when timer was or is in the
1293                          * middle of firing. In other cases we already freed
1294                          * resources.
1295                          */
1296                         spin_lock_irq(&timer.it_lock);
1297                         error = posix_cpu_timer_del(&timer);
1298                         spin_unlock_irq(&timer.it_lock);
1299                 }
1300
1301                 if ((it->it_value.tv_sec | it->it_value.tv_nsec) == 0) {
1302                         /*
1303                          * It actually did fire already.
1304                          */
1305                         return 0;
1306                 }
1307
1308                 error = -ERESTART_RESTARTBLOCK;
1309         }
1310
1311         return error;
1312 }
1313
1314 static long posix_cpu_nsleep_restart(struct restart_block *restart_block);
1315
1316 static int posix_cpu_nsleep(const clockid_t which_clock, int flags,
1317                             struct timespec64 *rqtp, struct timespec __user *rmtp)
1318 {
1319         struct restart_block *restart_block = &current->restart_block;
1320         struct itimerspec64 it;
1321         struct timespec ts;
1322         int error;
1323
1324         /*
1325          * Diagnose required errors first.
1326          */
1327         if (CPUCLOCK_PERTHREAD(which_clock) &&
1328             (CPUCLOCK_PID(which_clock) == 0 ||
1329              CPUCLOCK_PID(which_clock) == task_pid_vnr(current)))
1330                 return -EINVAL;
1331
1332         error = do_cpu_nanosleep(which_clock, flags, rqtp, &it);
1333
1334         if (error == -ERESTART_RESTARTBLOCK) {
1335
1336                 if (flags & TIMER_ABSTIME)
1337                         return -ERESTARTNOHAND;
1338                 /*
1339                  * Report back to the user the time still remaining.
1340                  */
1341                 ts = timespec64_to_timespec(it.it_value);
1342                 if (rmtp && copy_to_user(rmtp, &ts, sizeof(*rmtp)))
1343                         return -EFAULT;
1344
1345                 restart_block->fn = posix_cpu_nsleep_restart;
1346                 restart_block->nanosleep.clockid = which_clock;
1347                 restart_block->nanosleep.rmtp = rmtp;
1348                 restart_block->nanosleep.expires = timespec64_to_ns(rqtp);
1349         }
1350         return error;
1351 }
1352
1353 static long posix_cpu_nsleep_restart(struct restart_block *restart_block)
1354 {
1355         clockid_t which_clock = restart_block->nanosleep.clockid;
1356         struct itimerspec64 it;
1357         struct timespec64 t;
1358         struct timespec tmp;
1359         int error;
1360
1361         t = ns_to_timespec64(restart_block->nanosleep.expires);
1362
1363         error = do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t, &it);
1364
1365         if (error == -ERESTART_RESTARTBLOCK) {
1366                 struct timespec __user *rmtp = restart_block->nanosleep.rmtp;
1367                 /*
1368                  * Report back to the user the time still remaining.
1369                  */
1370                  tmp = timespec64_to_timespec(it.it_value);
1371                 if (rmtp && copy_to_user(rmtp, &tmp, sizeof(*rmtp)))
1372                         return -EFAULT;
1373
1374                 restart_block->nanosleep.expires = timespec64_to_ns(&t);
1375         }
1376         return error;
1377
1378 }
1379
1380 #define PROCESS_CLOCK   MAKE_PROCESS_CPUCLOCK(0, CPUCLOCK_SCHED)
1381 #define THREAD_CLOCK    MAKE_THREAD_CPUCLOCK(0, CPUCLOCK_SCHED)
1382
1383 static int process_cpu_clock_getres(const clockid_t which_clock,
1384                                     struct timespec64 *tp)
1385 {
1386         return posix_cpu_clock_getres(PROCESS_CLOCK, tp);
1387 }
1388 static int process_cpu_clock_get(const clockid_t which_clock,
1389                                  struct timespec64 *tp)
1390 {
1391         return posix_cpu_clock_get(PROCESS_CLOCK, tp);
1392 }
1393 static int process_cpu_timer_create(struct k_itimer *timer)
1394 {
1395         timer->it_clock = PROCESS_CLOCK;
1396         return posix_cpu_timer_create(timer);
1397 }
1398 static int process_cpu_nsleep(const clockid_t which_clock, int flags,
1399                               struct timespec64 *rqtp,
1400                               struct timespec __user *rmtp)
1401 {
1402         return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp, rmtp);
1403 }
1404 static long process_cpu_nsleep_restart(struct restart_block *restart_block)
1405 {
1406         return -EINVAL;
1407 }
1408 static int thread_cpu_clock_getres(const clockid_t which_clock,
1409                                    struct timespec64 *tp)
1410 {
1411         return posix_cpu_clock_getres(THREAD_CLOCK, tp);
1412 }
1413 static int thread_cpu_clock_get(const clockid_t which_clock,
1414                                 struct timespec64 *tp)
1415 {
1416         return posix_cpu_clock_get(THREAD_CLOCK, tp);
1417 }
1418 static int thread_cpu_timer_create(struct k_itimer *timer)
1419 {
1420         timer->it_clock = THREAD_CLOCK;
1421         return posix_cpu_timer_create(timer);
1422 }
1423
1424 struct k_clock clock_posix_cpu = {
1425         .clock_getres   = posix_cpu_clock_getres,
1426         .clock_set      = posix_cpu_clock_set,
1427         .clock_get      = posix_cpu_clock_get,
1428         .timer_create   = posix_cpu_timer_create,
1429         .nsleep         = posix_cpu_nsleep,
1430         .nsleep_restart = posix_cpu_nsleep_restart,
1431         .timer_set      = posix_cpu_timer_set,
1432         .timer_del      = posix_cpu_timer_del,
1433         .timer_get      = posix_cpu_timer_get,
1434 };
1435
1436 static __init int init_posix_cpu_timers(void)
1437 {
1438         struct k_clock process = {
1439                 .clock_getres   = process_cpu_clock_getres,
1440                 .clock_get      = process_cpu_clock_get,
1441                 .timer_create   = process_cpu_timer_create,
1442                 .nsleep         = process_cpu_nsleep,
1443                 .nsleep_restart = process_cpu_nsleep_restart,
1444         };
1445         struct k_clock thread = {
1446                 .clock_getres   = thread_cpu_clock_getres,
1447                 .clock_get      = thread_cpu_clock_get,
1448                 .timer_create   = thread_cpu_timer_create,
1449         };
1450
1451         posix_timers_register_clock(CLOCK_PROCESS_CPUTIME_ID, &process);
1452         posix_timers_register_clock(CLOCK_THREAD_CPUTIME_ID, &thread);
1453
1454         return 0;
1455 }
1456 __initcall(init_posix_cpu_timers);