| /* |
| * Implement CPU time clocks for the POSIX clock interface. |
| */ |
| |
| #include <linux/sched/signal.h> |
| #include <linux/sched/cputime.h> |
| #include <linux/posix-timers.h> |
| #include <linux/errno.h> |
| #include <linux/math64.h> |
| #include <linux/uaccess.h> |
| #include <linux/kernel_stat.h> |
| #include <trace/events/timer.h> |
| #include <linux/tick.h> |
| #include <linux/workqueue.h> |
| #include <linux/compat.h> |
| |
| #include "posix-timers.h" |
| |
| static void posix_cpu_timer_rearm(struct k_itimer *timer); |
| |
| /* |
| * Called after updating RLIMIT_CPU to run cpu timer and update |
| * tsk->signal->cputime_expires expiration cache if necessary. Needs |
| * siglock protection since other code may update expiration cache as |
| * well. |
| */ |
| void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new) |
| { |
| u64 nsecs = rlim_new * NSEC_PER_SEC; |
| |
| spin_lock_irq(&task->sighand->siglock); |
| set_process_cpu_timer(task, CPUCLOCK_PROF, &nsecs, NULL); |
| spin_unlock_irq(&task->sighand->siglock); |
| } |
| |
| static int check_clock(const clockid_t which_clock) |
| { |
| int error = 0; |
| struct task_struct *p; |
| const pid_t pid = CPUCLOCK_PID(which_clock); |
| |
| if (CPUCLOCK_WHICH(which_clock) >= CPUCLOCK_MAX) |
| return -EINVAL; |
| |
| if (pid == 0) |
| return 0; |
| |
| rcu_read_lock(); |
| p = find_task_by_vpid(pid); |
| if (!p || !(CPUCLOCK_PERTHREAD(which_clock) ? |
| same_thread_group(p, current) : has_group_leader_pid(p))) { |
| error = -EINVAL; |
| } |
| rcu_read_unlock(); |
| |
| return error; |
| } |
| |
| /* |
| * Update expiry time from increment, and increase overrun count, |
| * given the current clock sample. |
| */ |
| static void bump_cpu_timer(struct k_itimer *timer, u64 now) |
| { |
| int i; |
| u64 delta, incr; |
| |
| if (timer->it.cpu.incr == 0) |
| return; |
| |
| if (now < timer->it.cpu.expires) |
| return; |
| |
| incr = timer->it.cpu.incr; |
| delta = now + incr - timer->it.cpu.expires; |
| |
| /* Don't use (incr*2 < delta), incr*2 might overflow. */ |
| for (i = 0; incr < delta - incr; i++) |
| incr = incr << 1; |
| |
| for (; i >= 0; incr >>= 1, i--) { |
| if (delta < incr) |
| continue; |
| |
| timer->it.cpu.expires += incr; |
| timer->it_overrun += 1 << i; |
| delta -= incr; |
| } |
| } |
| |
| /** |
| * task_cputime_zero - Check a task_cputime struct for all zero fields. |
| * |
| * @cputime: The struct to compare. |
| * |
| * Checks @cputime to see if all fields are zero. Returns true if all fields |
| * are zero, false if any field is nonzero. |
| */ |
| static inline int task_cputime_zero(const struct task_cputime *cputime) |
| { |
| if (!cputime->utime && !cputime->stime && !cputime->sum_exec_runtime) |
| return 1; |
| return 0; |
| } |
| |
| static inline u64 prof_ticks(struct task_struct *p) |
| { |
| u64 utime, stime; |
| |
| task_cputime(p, &utime, &stime); |
| |
| return utime + stime; |
| } |
| static inline u64 virt_ticks(struct task_struct *p) |
| { |
| u64 utime, stime; |
| |
| task_cputime(p, &utime, &stime); |
| |
| return utime; |
| } |
| |
| static int |
| posix_cpu_clock_getres(const clockid_t which_clock, struct timespec64 *tp) |
| { |
| int error = check_clock(which_clock); |
| if (!error) { |
| tp->tv_sec = 0; |
| tp->tv_nsec = ((NSEC_PER_SEC + HZ - 1) / HZ); |
| if (CPUCLOCK_WHICH(which_clock) == CPUCLOCK_SCHED) { |
| /* |
| * If sched_clock is using a cycle counter, we |
| * don't have any idea of its true resolution |
| * exported, but it is much more than 1s/HZ. |
| */ |
| tp->tv_nsec = 1; |
| } |
| } |
| return error; |
| } |
| |
| static int |
| posix_cpu_clock_set(const clockid_t which_clock, const struct timespec64 *tp) |
| { |
| /* |
| * You can never reset a CPU clock, but we check for other errors |
| * in the call before failing with EPERM. |
| */ |
| int error = check_clock(which_clock); |
| if (error == 0) { |
| error = -EPERM; |
| } |
| return error; |
| } |
| |
| |
| /* |
| * Sample a per-thread clock for the given task. |
| */ |
| static int cpu_clock_sample(const clockid_t which_clock, |
| struct task_struct *p, u64 *sample) |
| { |
| switch (CPUCLOCK_WHICH(which_clock)) { |
| default: |
| return -EINVAL; |
| case CPUCLOCK_PROF: |
| *sample = prof_ticks(p); |
| break; |
| case CPUCLOCK_VIRT: |
| *sample = virt_ticks(p); |
| break; |
| case CPUCLOCK_SCHED: |
| *sample = task_sched_runtime(p); |
| break; |
| } |
| return 0; |
| } |
| |
| /* |
| * Set cputime to sum_cputime if sum_cputime > cputime. Use cmpxchg |
| * to avoid race conditions with concurrent updates to cputime. |
| */ |
| static inline void __update_gt_cputime(atomic64_t *cputime, u64 sum_cputime) |
| { |
| u64 curr_cputime; |
| retry: |
| curr_cputime = atomic64_read(cputime); |
| if (sum_cputime > curr_cputime) { |
| if (atomic64_cmpxchg(cputime, curr_cputime, sum_cputime) != curr_cputime) |
| goto retry; |
| } |
| } |
| |
| static void update_gt_cputime(struct task_cputime_atomic *cputime_atomic, struct task_cputime *sum) |
| { |
| __update_gt_cputime(&cputime_atomic->utime, sum->utime); |
| __update_gt_cputime(&cputime_atomic->stime, sum->stime); |
| __update_gt_cputime(&cputime_atomic->sum_exec_runtime, sum->sum_exec_runtime); |
| } |
| |
| /* Sample task_cputime_atomic values in "atomic_timers", store results in "times". */ |
| static inline void sample_cputime_atomic(struct task_cputime *times, |
| struct task_cputime_atomic *atomic_times) |
| { |
| times->utime = atomic64_read(&atomic_times->utime); |
| times->stime = atomic64_read(&atomic_times->stime); |
| times->sum_exec_runtime = atomic64_read(&atomic_times->sum_exec_runtime); |
| } |
| |
| void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times) |
| { |
| struct thread_group_cputimer *cputimer = &tsk->signal->cputimer; |
| struct task_cputime sum; |
| |
| /* Check if cputimer isn't running. This is accessed without locking. */ |
| if (!READ_ONCE(cputimer->running)) { |
| /* |
| * The POSIX timer interface allows for absolute time expiry |
| * values through the TIMER_ABSTIME flag, therefore we have |
| * to synchronize the timer to the clock every time we start it. |
| */ |
| thread_group_cputime(tsk, &sum); |
| update_gt_cputime(&cputimer->cputime_atomic, &sum); |
| |
| /* |
| * We're setting cputimer->running without a lock. Ensure |
| * this only gets written to in one operation. We set |
| * running after update_gt_cputime() as a small optimization, |
| * but barriers are not required because update_gt_cputime() |
| * can handle concurrent updates. |
| */ |
| WRITE_ONCE(cputimer->running, true); |
| } |
| sample_cputime_atomic(times, &cputimer->cputime_atomic); |
| } |
| |
| /* |
| * Sample a process (thread group) clock for the given group_leader task. |
| * Must be called with task sighand lock held for safe while_each_thread() |
| * traversal. |
| */ |
| static int cpu_clock_sample_group(const clockid_t which_clock, |
| struct task_struct *p, |
| u64 *sample) |
| { |
| struct task_cputime cputime; |
| |
| switch (CPUCLOCK_WHICH(which_clock)) { |
| default: |
| return -EINVAL; |
| case CPUCLOCK_PROF: |
| thread_group_cputime(p, &cputime); |
| *sample = cputime.utime + cputime.stime; |
| break; |
| case CPUCLOCK_VIRT: |
| thread_group_cputime(p, &cputime); |
| *sample = cputime.utime; |
| break; |
| case CPUCLOCK_SCHED: |
| thread_group_cputime(p, &cputime); |
| *sample = cputime.sum_exec_runtime; |
| break; |
| } |
| return 0; |
| } |
| |
| static int posix_cpu_clock_get_task(struct task_struct *tsk, |
| const clockid_t which_clock, |
| struct timespec64 *tp) |
| { |
| int err = -EINVAL; |
| u64 rtn; |
| |
| if (CPUCLOCK_PERTHREAD(which_clock)) { |
| if (same_thread_group(tsk, current)) |
| err = cpu_clock_sample(which_clock, tsk, &rtn); |
| } else { |
| if (tsk == current || thread_group_leader(tsk)) |
| err = cpu_clock_sample_group(which_clock, tsk, &rtn); |
| } |
| |
| if (!err) |
| *tp = ns_to_timespec64(rtn); |
| |
| return err; |
| } |
| |
| |
| static int posix_cpu_clock_get(const clockid_t which_clock, struct timespec64 *tp) |
| { |
| const pid_t pid = CPUCLOCK_PID(which_clock); |
| int err = -EINVAL; |
| |
| if (pid == 0) { |
| /* |
| * Special case constant value for our own clocks. |
| * We don't have to do any lookup to find ourselves. |
| */ |
| err = posix_cpu_clock_get_task(current, which_clock, tp); |
| } else { |
| /* |
| * Find the given PID, and validate that the caller |
| * should be able to see it. |
| */ |
| struct task_struct *p; |
| rcu_read_lock(); |
| p = find_task_by_vpid(pid); |
| if (p) |
| err = posix_cpu_clock_get_task(p, which_clock, tp); |
| rcu_read_unlock(); |
| } |
| |
| return err; |
| } |
| |
| /* |
| * Validate the clockid_t for a new CPU-clock timer, and initialize the timer. |
| * This is called from sys_timer_create() and do_cpu_nanosleep() with the |
| * new timer already all-zeros initialized. |
| */ |
| static int posix_cpu_timer_create(struct k_itimer *new_timer) |
| { |
| int ret = 0; |
| const pid_t pid = CPUCLOCK_PID(new_timer->it_clock); |
| struct task_struct *p; |
| |
| if (CPUCLOCK_WHICH(new_timer->it_clock) >= CPUCLOCK_MAX) |
| return -EINVAL; |
| |
| new_timer->kclock = &clock_posix_cpu; |
| |
| INIT_LIST_HEAD(&new_timer->it.cpu.entry); |
| |
| rcu_read_lock(); |
| if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) { |
| if (pid == 0) { |
| p = current; |
| } else { |
| p = find_task_by_vpid(pid); |
| if (p && !same_thread_group(p, current)) |
| p = NULL; |
| } |
| } else { |
| if (pid == 0) { |
| p = current->group_leader; |
| } else { |
| p = find_task_by_vpid(pid); |
| if (p && !has_group_leader_pid(p)) |
| p = NULL; |
| } |
| } |
| new_timer->it.cpu.task = p; |
| if (p) { |
| get_task_struct(p); |
| } else { |
| ret = -EINVAL; |
| } |
| rcu_read_unlock(); |
| |
| return ret; |
| } |
| |
| /* |
| * Clean up a CPU-clock timer that is about to be destroyed. |
| * This is called from timer deletion with the timer already locked. |
| * If we return TIMER_RETRY, it's necessary to release the timer's lock |
| * and try again. (This happens when the timer is in the middle of firing.) |
| */ |
| static int posix_cpu_timer_del(struct k_itimer *timer) |
| { |
| int ret = 0; |
| unsigned long flags; |
| struct sighand_struct *sighand; |
| struct task_struct *p = timer->it.cpu.task; |
| |
| WARN_ON_ONCE(p == NULL); |
| |
| /* |
| * Protect against sighand release/switch in exit/exec and process/ |
| * thread timer list entry concurrent read/writes. |
| */ |
| sighand = lock_task_sighand(p, &flags); |
| if (unlikely(sighand == NULL)) { |
| /* |
| * We raced with the reaping of the task. |
| * The deletion should have cleared us off the list. |
| */ |
| WARN_ON_ONCE(!list_empty(&timer->it.cpu.entry)); |
| } else { |
| if (timer->it.cpu.firing) |
| ret = TIMER_RETRY; |
| else |
| list_del(&timer->it.cpu.entry); |
| |
| unlock_task_sighand(p, &flags); |
| } |
| |
| if (!ret) |
| put_task_struct(p); |
| |
| return ret; |
| } |
| |
| static void cleanup_timers_list(struct list_head *head) |
| { |
| struct cpu_timer_list *timer, *next; |
| |
| list_for_each_entry_safe(timer, next, head, entry) |
| list_del_init(&timer->entry); |
| } |
| |
| /* |
| * Clean out CPU timers still ticking when a thread exited. The task |
| * pointer is cleared, and the expiry time is replaced with the residual |
| * time for later timer_gettime calls to return. |
| * This must be called with the siglock held. |
| */ |
| static void cleanup_timers(struct list_head *head) |
| { |
| cleanup_timers_list(head); |
| cleanup_timers_list(++head); |
| cleanup_timers_list(++head); |
| } |
| |
| /* |
| * These are both called with the siglock held, when the current thread |
| * is being reaped. When the final (leader) thread in the group is reaped, |
| * posix_cpu_timers_exit_group will be called after posix_cpu_timers_exit. |
| */ |
| void posix_cpu_timers_exit(struct task_struct *tsk) |
| { |
| cleanup_timers(tsk->cpu_timers); |
| } |
| void posix_cpu_timers_exit_group(struct task_struct *tsk) |
| { |
| cleanup_timers(tsk->signal->cpu_timers); |
| } |
| |
| static inline int expires_gt(u64 expires, u64 new_exp) |
| { |
| return expires == 0 || expires > new_exp; |
| } |
| |
| /* |
| * Insert the timer on the appropriate list before any timers that |
| * expire later. This must be called with the sighand lock held. |
| */ |
| static void arm_timer(struct k_itimer *timer) |
| { |
| struct task_struct *p = timer->it.cpu.task; |
| struct list_head *head, *listpos; |
| struct task_cputime *cputime_expires; |
| struct cpu_timer_list *const nt = &timer->it.cpu; |
| struct cpu_timer_list *next; |
| |
| if (CPUCLOCK_PERTHREAD(timer->it_clock)) { |
| head = p->cpu_timers; |
| cputime_expires = &p->cputime_expires; |
| } else { |
| head = p->signal->cpu_timers; |
| cputime_expires = &p->signal->cputime_expires; |
| } |
| head += CPUCLOCK_WHICH(timer->it_clock); |
| |
| listpos = head; |
| list_for_each_entry(next, head, entry) { |
| if (nt->expires < next->expires) |
| break; |
| listpos = &next->entry; |
| } |
| list_add(&nt->entry, listpos); |
| |
| if (listpos == head) { |
| u64 exp = nt->expires; |
| |
| /* |
| * We are the new earliest-expiring POSIX 1.b timer, hence |
| * need to update expiration cache. Take into account that |
| * for process timers we share expiration cache with itimers |
| * and RLIMIT_CPU and for thread timers with RLIMIT_RTTIME. |
| */ |
| |
| switch (CPUCLOCK_WHICH(timer->it_clock)) { |
| case CPUCLOCK_PROF: |
| if (expires_gt(cputime_expires->prof_exp, exp)) |
| cputime_expires->prof_exp = exp; |
| break; |
| case CPUCLOCK_VIRT: |
| if (expires_gt(cputime_expires->virt_exp, exp)) |
| cputime_expires->virt_exp = exp; |
| break; |
| case CPUCLOCK_SCHED: |
| if (expires_gt(cputime_expires->sched_exp, exp)) |
| cputime_expires->sched_exp = exp; |
| break; |
| } |
| if (CPUCLOCK_PERTHREAD(timer->it_clock)) |
| tick_dep_set_task(p, TICK_DEP_BIT_POSIX_TIMER); |
| else |
| tick_dep_set_signal(p->signal, TICK_DEP_BIT_POSIX_TIMER); |
| } |
| } |
| |
| /* |
| * The timer is locked, fire it and arrange for its reload. |
| */ |
| static void cpu_timer_fire(struct k_itimer *timer) |
| { |
| if ((timer->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE) { |
| /* |
| * User don't want any signal. |
| */ |
| timer->it.cpu.expires = 0; |
| } else if (unlikely(timer->sigq == NULL)) { |
| /* |
| * This a special case for clock_nanosleep, |
| * not a normal timer from sys_timer_create. |
| */ |
| wake_up_process(timer->it_process); |
| timer->it.cpu.expires = 0; |
| } else if (timer->it.cpu.incr == 0) { |
| /* |
| * One-shot timer. Clear it as soon as it's fired. |
| */ |
| posix_timer_event(timer, 0); |
| timer->it.cpu.expires = 0; |
| } else if (posix_timer_event(timer, ++timer->it_requeue_pending)) { |
| /* |
| * The signal did not get queued because the signal |
| * was ignored, so we won't get any callback to |
| * reload the timer. But we need to keep it |
| * ticking in case the signal is deliverable next time. |
| */ |
| posix_cpu_timer_rearm(timer); |
| ++timer->it_requeue_pending; |
| } |
| } |
| |
| /* |
| * Sample a process (thread group) timer for the given group_leader task. |
| * Must be called with task sighand lock held for safe while_each_thread() |
| * traversal. |
| */ |
| static int cpu_timer_sample_group(const clockid_t which_clock, |
| struct task_struct *p, u64 *sample) |
| { |
| struct task_cputime cputime; |
| |
| thread_group_cputimer(p, &cputime); |
| switch (CPUCLOCK_WHICH(which_clock)) { |
| default: |
| return -EINVAL; |
| case CPUCLOCK_PROF: |
| *sample = cputime.utime + cputime.stime; |
| break; |
| case CPUCLOCK_VIRT: |
| *sample = cputime.utime; |
| break; |
| case CPUCLOCK_SCHED: |
| *sample = cputime.sum_exec_runtime; |
| break; |
| } |
| return 0; |
| } |
| |
| /* |
| * Guts of sys_timer_settime for CPU timers. |
| * This is called with the timer locked and interrupts disabled. |
| * If we return TIMER_RETRY, it's necessary to release the timer's lock |
| * and try again. (This happens when the timer is in the middle of firing.) |
| */ |
| static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags, |
| struct itimerspec64 *new, struct itimerspec64 *old) |
| { |
| unsigned long flags; |
| struct sighand_struct *sighand; |
| struct task_struct *p = timer->it.cpu.task; |
| u64 old_expires, new_expires, old_incr, val; |
| int ret; |
| |
| WARN_ON_ONCE(p == NULL); |
| |
| /* |
| * Use the to_ktime conversion because that clamps the maximum |
| * value to KTIME_MAX and avoid multiplication overflows. |
| */ |
| new_expires = ktime_to_ns(timespec64_to_ktime(new->it_value)); |
| |
| /* |
| * Protect against sighand release/switch in exit/exec and p->cpu_timers |
| * and p->signal->cpu_timers read/write in arm_timer() |
| */ |
| sighand = lock_task_sighand(p, &flags); |
| /* |
| * If p has just been reaped, we can no |
| * longer get any information about it at all. |
| */ |
| if (unlikely(sighand == NULL)) { |
| return -ESRCH; |
| } |
| |
| /* |
| * Disarm any old timer after extracting its expiry time. |
| */ |
| WARN_ON_ONCE(!irqs_disabled()); |
| |
| ret = 0; |
| old_incr = timer->it.cpu.incr; |
| old_expires = timer->it.cpu.expires; |
| if (unlikely(timer->it.cpu.firing)) { |
| timer->it.cpu.firing = -1; |
| ret = TIMER_RETRY; |
| } else |
| list_del_init(&timer->it.cpu.entry); |
| |
| /* |
| * We need to sample the current value to convert the new |
| * value from to relative and absolute, and to convert the |
| * old value from absolute to relative. To set a process |
| * timer, we need a sample to balance the thread expiry |
| * times (in arm_timer). With an absolute time, we must |
| * check if it's already passed. In short, we need a sample. |
| */ |
| if (CPUCLOCK_PERTHREAD(timer->it_clock)) { |
| cpu_clock_sample(timer->it_clock, p, &val); |
| } else { |
| cpu_timer_sample_group(timer->it_clock, p, &val); |
| } |
| |
| if (old) { |
| if (old_expires == 0) { |
| old->it_value.tv_sec = 0; |
| old->it_value.tv_nsec = 0; |
| } else { |
| /* |
| * Update the timer in case it has |
| * overrun already. If it has, |
| * we'll report it as having overrun |
| * and with the next reloaded timer |
| * already ticking, though we are |
| * swallowing that pending |
| * notification here to install the |
| * new setting. |
| */ |
| bump_cpu_timer(timer, val); |
| if (val < timer->it.cpu.expires) { |
| old_expires = timer->it.cpu.expires - val; |
| old->it_value = ns_to_timespec64(old_expires); |
| } else { |
| old->it_value.tv_nsec = 1; |
| old->it_value.tv_sec = 0; |
| } |
| } |
| } |
| |
| if (unlikely(ret)) { |
| /* |
| * We are colliding with the timer actually firing. |
| * Punt after filling in the timer's old value, and |
| * disable this firing since we are already reporting |
| * it as an overrun (thanks to bump_cpu_timer above). |
| */ |
| unlock_task_sighand(p, &flags); |
| goto out; |
| } |
| |
| if (new_expires != 0 && !(timer_flags & TIMER_ABSTIME)) { |
| new_expires += val; |
| } |
| |
| /* |
| * Install the new expiry time (or zero). |
| * For a timer with no notification action, we don't actually |
| * arm the timer (we'll just fake it for timer_gettime). |
| */ |
| timer->it.cpu.expires = new_expires; |
| if (new_expires != 0 && val < new_expires) { |
| arm_timer(timer); |
| } |
| |
| unlock_task_sighand(p, &flags); |
| /* |
| * Install the new reload setting, and |
| * set up the signal and overrun bookkeeping. |
| */ |
| timer->it.cpu.incr = timespec64_to_ns(&new->it_interval); |
| |
| /* |
| * This acts as a modification timestamp for the timer, |
| * so any automatic reload attempt will punt on seeing |
| * that we have reset the timer manually. |
| */ |
| timer->it_requeue_pending = (timer->it_requeue_pending + 2) & |
| ~REQUEUE_PENDING; |
| timer->it_overrun_last = 0; |
| timer->it_overrun = -1; |
| |
| if (new_expires != 0 && !(val < new_expires)) { |
| /* |
| * The designated time already passed, so we notify |
| * immediately, even if the thread never runs to |
| * accumulate more time on this clock. |
| */ |
| cpu_timer_fire(timer); |
| } |
| |
| ret = 0; |
| out: |
| if (old) |
| old->it_interval = ns_to_timespec64(old_incr); |
| |
| return ret; |
| } |
| |
| static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec64 *itp) |
| { |
| u64 now; |
| struct task_struct *p = timer->it.cpu.task; |
| |
| WARN_ON_ONCE(p == NULL); |
| |
| /* |
| * Easy part: convert the reload time. |
| */ |
| itp->it_interval = ns_to_timespec64(timer->it.cpu.incr); |
| |
| if (!timer->it.cpu.expires) |
| return; |
| |
| /* |
| * Sample the clock to take the difference with the expiry time. |
| */ |
| if (CPUCLOCK_PERTHREAD(timer->it_clock)) { |
| cpu_clock_sample(timer->it_clock, p, &now); |
| } else { |
| struct sighand_struct *sighand; |
| unsigned long flags; |
| |
| /* |
| * Protect against sighand release/switch in exit/exec and |
| * also make timer sampling safe if it ends up calling |
| * thread_group_cputime(). |
| */ |
| sighand = lock_task_sighand(p, &flags); |
| if (unlikely(sighand == NULL)) { |
| /* |
| * The process has been reaped. |
| * We can't even collect a sample any more. |
| * Call the timer disarmed, nothing else to do. |
| */ |
| timer->it.cpu.expires = 0; |
| return; |
| } else { |
| cpu_timer_sample_group(timer->it_clock, p, &now); |
| unlock_task_sighand(p, &flags); |
| } |
| } |
| |
| if (now < timer->it.cpu.expires) { |
| itp->it_value = ns_to_timespec64(timer->it.cpu.expires - now); |
| } else { |
| /* |
| * The timer should have expired already, but the firing |
| * hasn't taken place yet. Say it's just about to expire. |
| */ |
| itp->it_value.tv_nsec = 1; |
| itp->it_value.tv_sec = 0; |
| } |
| } |
| |
| static unsigned long long |
| check_timers_list(struct list_head *timers, |
| struct list_head *firing, |
| unsigned long long curr) |
| { |
| int maxfire = 20; |
| |
| while (!list_empty(timers)) { |
| struct cpu_timer_list *t; |
| |
| t = list_first_entry(timers, struct cpu_timer_list, entry); |
| |
| if (!--maxfire || curr < t->expires) |
| return t->expires; |
| |
| t->firing = 1; |
| list_move_tail(&t->entry, firing); |
| } |
| |
| return 0; |
| } |
| |
| /* |
| * Check for any per-thread CPU timers that have fired and move them off |
| * the tsk->cpu_timers[N] list onto the firing list. Here we update the |
| * tsk->it_*_expires values to reflect the remaining thread CPU timers. |
| */ |
| static void check_thread_timers(struct task_struct *tsk, |
| struct list_head *firing) |
| { |
| struct list_head *timers = tsk->cpu_timers; |
| struct signal_struct *const sig = tsk->signal; |
| struct task_cputime *tsk_expires = &tsk->cputime_expires; |
| u64 expires; |
| unsigned long soft; |
| |
| /* |
| * If cputime_expires is zero, then there are no active |
| * per thread CPU timers. |
| */ |
| if (task_cputime_zero(&tsk->cputime_expires)) |
| return; |
| |
| expires = check_timers_list(timers, firing, prof_ticks(tsk)); |
| tsk_expires->prof_exp = expires; |
| |
| expires = check_timers_list(++timers, firing, virt_ticks(tsk)); |
| tsk_expires->virt_exp = expires; |
| |
| tsk_expires->sched_exp = check_timers_list(++timers, firing, |
| tsk->se.sum_exec_runtime); |
| |
| /* |
| * Check for the special case thread timers. |
| */ |
| soft = READ_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_cur); |
| if (soft != RLIM_INFINITY) { |
| unsigned long hard = |
| READ_ONCE(sig->rlim[RLIMIT_RTTIME].rlim_max); |
| |
| if (hard != RLIM_INFINITY && |
| tsk->rt.timeout > DIV_ROUND_UP(hard, USEC_PER_SEC/HZ)) { |
| /* |
| * At the hard limit, we just die. |
| * No need to calculate anything else now. |
| */ |
| if (print_fatal_signals) { |
| pr_info("CPU Watchdog Timeout (hard): %s[%d]\n", |
| tsk->comm, task_pid_nr(tsk)); |
| } |
| __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk); |
| return; |
| } |
| if (tsk->rt.timeout > DIV_ROUND_UP(soft, USEC_PER_SEC/HZ)) { |
| /* |
| * At the soft limit, send a SIGXCPU every second. |
| */ |
| if (soft < hard) { |
| soft += USEC_PER_SEC; |
| sig->rlim[RLIMIT_RTTIME].rlim_cur = soft; |
| } |
| if (print_fatal_signals) { |
| pr_info("RT Watchdog Timeout (soft): %s[%d]\n", |
| tsk->comm, task_pid_nr(tsk)); |
| } |
| __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk); |
| } |
| } |
| if (task_cputime_zero(tsk_expires)) |
| tick_dep_clear_task(tsk, TICK_DEP_BIT_POSIX_TIMER); |
| } |
| |
| static inline void stop_process_timers(struct signal_struct *sig) |
| { |
| struct thread_group_cputimer *cputimer = &sig->cputimer; |
| |
| /* Turn off cputimer->running. This is done without locking. */ |
| WRITE_ONCE(cputimer->running, false); |
| tick_dep_clear_signal(sig, TICK_DEP_BIT_POSIX_TIMER); |
| } |
| |
| static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it, |
| u64 *expires, u64 cur_time, int signo) |
| { |
| if (!it->expires) |
| return; |
| |
| if (cur_time >= it->expires) { |
| if (it->incr) |
| it->expires += it->incr; |
| else |
| it->expires = 0; |
| |
| trace_itimer_expire(signo == SIGPROF ? |
| ITIMER_PROF : ITIMER_VIRTUAL, |
| tsk->signal->leader_pid, cur_time); |
| __group_send_sig_info(signo, SEND_SIG_PRIV, tsk); |
| } |
| |
| if (it->expires && (!*expires || it->expires < *expires)) |
| *expires = it->expires; |
| } |
| |
| /* |
| * Check for any per-thread CPU timers that have fired and move them |
| * off the tsk->*_timers list onto the firing list. Per-thread timers |
| * have already been taken off. |
| */ |
| static void check_process_timers(struct task_struct *tsk, |
| struct list_head *firing) |
| { |
| struct signal_struct *const sig = tsk->signal; |
| u64 utime, ptime, virt_expires, prof_expires; |
| u64 sum_sched_runtime, sched_expires; |
| struct list_head *timers = sig->cpu_timers; |
| struct task_cputime cputime; |
| unsigned long soft; |
| |
| /* |
| * If cputimer is not running, then there are no active |
| * process wide timers (POSIX 1.b, itimers, RLIMIT_CPU). |
| */ |
| if (!READ_ONCE(tsk->signal->cputimer.running)) |
| return; |
| |
| /* |
| * Signify that a thread is checking for process timers. |
| * Write access to this field is protected by the sighand lock. |
| */ |
| sig->cputimer.checking_timer = true; |
| |
| /* |
| * Collect the current process totals. |
| */ |
| thread_group_cputimer(tsk, &cputime); |
| utime = cputime.utime; |
| ptime = utime + cputime.stime; |
| sum_sched_runtime = cputime.sum_exec_runtime; |
| |
| prof_expires = check_timers_list(timers, firing, ptime); |
| virt_expires = check_timers_list(++timers, firing, utime); |
| sched_expires = check_timers_list(++timers, firing, sum_sched_runtime); |
| |
| /* |
| * Check for the special case process timers. |
| */ |
| check_cpu_itimer(tsk, &sig->it[CPUCLOCK_PROF], &prof_expires, ptime, |
| SIGPROF); |
| check_cpu_itimer(tsk, &sig->it[CPUCLOCK_VIRT], &virt_expires, utime, |
| SIGVTALRM); |
| soft = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur); |
| if (soft != RLIM_INFINITY) { |
| unsigned long psecs = div_u64(ptime, NSEC_PER_SEC); |
| unsigned long hard = |
| READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_max); |
| u64 x; |
| if (psecs >= hard) { |
| /* |
| * At the hard limit, we just die. |
| * No need to calculate anything else now. |
| */ |
| if (print_fatal_signals) { |
| pr_info("RT Watchdog Timeout (hard): %s[%d]\n", |
| tsk->comm, task_pid_nr(tsk)); |
| } |
| __group_send_sig_info(SIGKILL, SEND_SIG_PRIV, tsk); |
| return; |
| } |
| if (psecs >= soft) { |
| /* |
| * At the soft limit, send a SIGXCPU every second. |
| */ |
| if (print_fatal_signals) { |
| pr_info("CPU Watchdog Timeout (soft): %s[%d]\n", |
| tsk->comm, task_pid_nr(tsk)); |
| } |
| __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk); |
| if (soft < hard) { |
| soft++; |
| sig->rlim[RLIMIT_CPU].rlim_cur = soft; |
| } |
| } |
| x = soft * NSEC_PER_SEC; |
| if (!prof_expires || x < prof_expires) |
| prof_expires = x; |
| } |
| |
| sig->cputime_expires.prof_exp = prof_expires; |
| sig->cputime_expires.virt_exp = virt_expires; |
| sig->cputime_expires.sched_exp = sched_expires; |
| if (task_cputime_zero(&sig->cputime_expires)) |
| stop_process_timers(sig); |
| |
| sig->cputimer.checking_timer = false; |
| } |
| |
| /* |
| * This is called from the signal code (via posixtimer_rearm) |
| * when the last timer signal was delivered and we have to reload the timer. |
| */ |
| static void posix_cpu_timer_rearm(struct k_itimer *timer) |
| { |
| struct sighand_struct *sighand; |
| unsigned long flags; |
| struct task_struct *p = timer->it.cpu.task; |
| u64 now; |
| |
| WARN_ON_ONCE(p == NULL); |
| |
| /* |
| * Fetch the current sample and update the timer's expiry time. |
| */ |
| if (CPUCLOCK_PERTHREAD(timer->it_clock)) { |
| cpu_clock_sample(timer->it_clock, p, &now); |
| bump_cpu_timer(timer, now); |
| if (unlikely(p->exit_state)) |
| return; |
| |
| /* Protect timer list r/w in arm_timer() */ |
| sighand = lock_task_sighand(p, &flags); |
| if (!sighand) |
| return; |
| } else { |
| /* |
| * Protect arm_timer() and timer sampling in case of call to |
| * thread_group_cputime(). |
| */ |
| sighand = lock_task_sighand(p, &flags); |
| if (unlikely(sighand == NULL)) { |
| /* |
| * The process has been reaped. |
| * We can't even collect a sample any more. |
| */ |
| timer->it.cpu.expires = 0; |
| return; |
| } else if (unlikely(p->exit_state) && thread_group_empty(p)) { |
| /* If the process is dying, no need to rearm */ |
| goto unlock; |
| } |
| cpu_timer_sample_group(timer->it_clock, p, &now); |
| bump_cpu_timer(timer, now); |
| /* Leave the sighand locked for the call below. */ |
| } |
| |
| /* |
| * Now re-arm for the new expiry time. |
| */ |
| WARN_ON_ONCE(!irqs_disabled()); |
| arm_timer(timer); |
| unlock: |
| unlock_task_sighand(p, &flags); |
| } |
| |
| /** |
| * task_cputime_expired - Compare two task_cputime entities. |
| * |
| * @sample: The task_cputime structure to be checked for expiration. |
| * @expires: Expiration times, against which @sample will be checked. |
| * |
| * Checks @sample against @expires to see if any field of @sample has expired. |
| * Returns true if any field of the former is greater than the corresponding |
| * field of the latter if the latter field is set. Otherwise returns false. |
| */ |
| static inline int task_cputime_expired(const struct task_cputime *sample, |
| const struct task_cputime *expires) |
| { |
| if (expires->utime && sample->utime >= expires->utime) |
| return 1; |
| if (expires->stime && sample->utime + sample->stime >= expires->stime) |
| return 1; |
| if (expires->sum_exec_runtime != 0 && |
| sample->sum_exec_runtime >= expires->sum_exec_runtime) |
| return 1; |
| return 0; |
| } |
| |
| /** |
| * fastpath_timer_check - POSIX CPU timers fast path. |
| * |
| * @tsk: The task (thread) being checked. |
| * |
| * Check the task and thread group timers. If both are zero (there are no |
| * timers set) return false. Otherwise snapshot the task and thread group |
| * timers and compare them with the corresponding expiration times. Return |
| * true if a timer has expired, else return false. |
| */ |
| static inline int fastpath_timer_check(struct task_struct *tsk) |
| { |
| struct signal_struct *sig; |
| |
| if (!task_cputime_zero(&tsk->cputime_expires)) { |
| struct task_cputime task_sample; |
| |
| task_cputime(tsk, &task_sample.utime, &task_sample.stime); |
| task_sample.sum_exec_runtime = tsk->se.sum_exec_runtime; |
| if (task_cputime_expired(&task_sample, &tsk->cputime_expires)) |
| return 1; |
| } |
| |
| sig = tsk->signal; |
| /* |
| * Check if thread group timers expired when the cputimer is |
| * running and no other thread in the group is already checking |
| * for thread group cputimers. These fields are read without the |
| * sighand lock. However, this is fine because this is meant to |
| * be a fastpath heuristic to determine whether we should try to |
| * acquire the sighand lock to check/handle timers. |
| * |
| * In the worst case scenario, if 'running' or 'checking_timer' gets |
| * set but the current thread doesn't see the change yet, we'll wait |
| * until the next thread in the group gets a scheduler interrupt to |
| * handle the timer. This isn't an issue in practice because these |
| * types of delays with signals actually getting sent are expected. |
| */ |
| if (READ_ONCE(sig->cputimer.running) && |
| !READ_ONCE(sig->cputimer.checking_timer)) { |
| struct task_cputime group_sample; |
| |
| sample_cputime_atomic(&group_sample, &sig->cputimer.cputime_atomic); |
| |
| if (task_cputime_expired(&group_sample, &sig->cputime_expires)) |
| return 1; |
| } |
| |
| return 0; |
| } |
| |
| /* |
| * This is called from the timer interrupt handler. The irq handler has |
| * already updated our counts. We need to check if any timers fire now. |
| * Interrupts are disabled. |
| */ |
| void run_posix_cpu_timers(struct task_struct *tsk) |
| { |
| LIST_HEAD(firing); |
| struct k_itimer *timer, *next; |
| unsigned long flags; |
| |
| WARN_ON_ONCE(!irqs_disabled()); |
| |
| /* |
| * The fast path checks that there are no expired thread or thread |
| * group timers. If that's so, just return. |
| */ |
| if (!fastpath_timer_check(tsk)) |
| return; |
| |
| if (!lock_task_sighand(tsk, &flags)) |
| return; |
| /* |
| * Here we take off tsk->signal->cpu_timers[N] and |
| * tsk->cpu_timers[N] all the timers that are firing, and |
| * put them on the firing list. |
| */ |
| check_thread_timers(tsk, &firing); |
| |
| check_process_timers(tsk, &firing); |
| |
| /* |
| * We must release these locks before taking any timer's lock. |
| * There is a potential race with timer deletion here, as the |
| * siglock now protects our private firing list. We have set |
| * the firing flag in each timer, so that a deletion attempt |
| * that gets the timer lock before we do will give it up and |
| * spin until we've taken care of that timer below. |
| */ |
| unlock_task_sighand(tsk, &flags); |
| |
| /* |
| * Now that all the timers on our list have the firing flag, |
| * no one will touch their list entries but us. We'll take |
| * each timer's lock before clearing its firing flag, so no |
| * timer call will interfere. |
| */ |
| list_for_each_entry_safe(timer, next, &firing, it.cpu.entry) { |
| int cpu_firing; |
| |
| spin_lock(&timer->it_lock); |
| list_del_init(&timer->it.cpu.entry); |
| cpu_firing = timer->it.cpu.firing; |
| timer->it.cpu.firing = 0; |
| /* |
| * The firing flag is -1 if we collided with a reset |
| * of the timer, which already reported this |
| * almost-firing as an overrun. So don't generate an event. |
| */ |
| if (likely(cpu_firing >= 0)) |
| cpu_timer_fire(timer); |
| spin_unlock(&timer->it_lock); |
| } |
| } |
| |
| /* |
| * Set one of the process-wide special case CPU timers or RLIMIT_CPU. |
| * The tsk->sighand->siglock must be held by the caller. |
| */ |
| void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx, |
| u64 *newval, u64 *oldval) |
| { |
| u64 now; |
| |
| WARN_ON_ONCE(clock_idx == CPUCLOCK_SCHED); |
| cpu_timer_sample_group(clock_idx, tsk, &now); |
| |
| if (oldval) { |
| /* |
| * We are setting itimer. The *oldval is absolute and we update |
| * it to be relative, *newval argument is relative and we update |
| * it to be absolute. |
| */ |
| if (*oldval) { |
| if (*oldval <= now) { |
| /* Just about to fire. */ |
| *oldval = TICK_NSEC; |
| } else { |
| *oldval -= now; |
| } |
| } |
| |
| if (!*newval) |
| return; |
| *newval += now; |
| } |
| |
| /* |
| * Update expiration cache if we are the earliest timer, or eventually |
| * RLIMIT_CPU limit is earlier than prof_exp cpu timer expire. |
| */ |
| switch (clock_idx) { |
| case CPUCLOCK_PROF: |
| if (expires_gt(tsk->signal->cputime_expires.prof_exp, *newval)) |
| tsk->signal->cputime_expires.prof_exp = *newval; |
| break; |
| case CPUCLOCK_VIRT: |
| if (expires_gt(tsk->signal->cputime_expires.virt_exp, *newval)) |
| tsk->signal->cputime_expires.virt_exp = *newval; |
| break; |
| } |
| |
| tick_dep_set_signal(tsk->signal, TICK_DEP_BIT_POSIX_TIMER); |
| } |
| |
| static int do_cpu_nanosleep(const clockid_t which_clock, int flags, |
| const struct timespec64 *rqtp) |
| { |
| struct itimerspec64 it; |
| struct k_itimer timer; |
| u64 expires; |
| int error; |
| |
| /* |
| * Set up a temporary timer and then wait for it to go off. |
| */ |
| memset(&timer, 0, sizeof timer); |
| spin_lock_init(&timer.it_lock); |
| timer.it_clock = which_clock; |
| timer.it_overrun = -1; |
| error = posix_cpu_timer_create(&timer); |
| timer.it_process = current; |
| if (!error) { |
| static struct itimerspec64 zero_it; |
| struct restart_block *restart; |
| |
| memset(&it, 0, sizeof(it)); |
| it.it_value = *rqtp; |
| |
| spin_lock_irq(&timer.it_lock); |
| error = posix_cpu_timer_set(&timer, flags, &it, NULL); |
| if (error) { |
| spin_unlock_irq(&timer.it_lock); |
| return error; |
| } |
| |
| while (!signal_pending(current)) { |
| if (timer.it.cpu.expires == 0) { |
| /* |
| * Our timer fired and was reset, below |
| * deletion can not fail. |
| */ |
| posix_cpu_timer_del(&timer); |
| spin_unlock_irq(&timer.it_lock); |
| return 0; |
| } |
| |
| /* |
| * Block until cpu_timer_fire (or a signal) wakes us. |
| */ |
| __set_current_state(TASK_INTERRUPTIBLE); |
| spin_unlock_irq(&timer.it_lock); |
| schedule(); |
| spin_lock_irq(&timer.it_lock); |
| } |
| |
| /* |
| * We were interrupted by a signal. |
| */ |
| expires = timer.it.cpu.expires; |
| error = posix_cpu_timer_set(&timer, 0, &zero_it, &it); |
| if (!error) { |
| /* |
| * Timer is now unarmed, deletion can not fail. |
| */ |
| posix_cpu_timer_del(&timer); |
| } |
| spin_unlock_irq(&timer.it_lock); |
| |
| while (error == TIMER_RETRY) { |
| /* |
| * We need to handle case when timer was or is in the |
| * middle of firing. In other cases we already freed |
| * resources. |
| */ |
| spin_lock_irq(&timer.it_lock); |
| error = posix_cpu_timer_del(&timer); |
| spin_unlock_irq(&timer.it_lock); |
| } |
| |
| if ((it.it_value.tv_sec | it.it_value.tv_nsec) == 0) { |
| /* |
| * It actually did fire already. |
| */ |
| return 0; |
| } |
| |
| error = -ERESTART_RESTARTBLOCK; |
| /* |
| * Report back to the user the time still remaining. |
| */ |
| restart = ¤t->restart_block; |
| restart->nanosleep.expires = expires; |
| if (restart->nanosleep.type != TT_NONE) { |
| struct timespec ts; |
| |
| ts = timespec64_to_timespec(it.it_value); |
| error = nanosleep_copyout(restart, &ts); |
| } |
| } |
| |
| return error; |
| } |
| |
| static long posix_cpu_nsleep_restart(struct restart_block *restart_block); |
| |
| static int posix_cpu_nsleep(const clockid_t which_clock, int flags, |
| const struct timespec64 *rqtp) |
| { |
| struct restart_block *restart_block = ¤t->restart_block; |
| int error; |
| |
| /* |
| * Diagnose required errors first. |
| */ |
| if (CPUCLOCK_PERTHREAD(which_clock) && |
| (CPUCLOCK_PID(which_clock) == 0 || |
| CPUCLOCK_PID(which_clock) == task_pid_vnr(current))) |
| return -EINVAL; |
| |
| error = do_cpu_nanosleep(which_clock, flags, rqtp); |
| |
| if (error == -ERESTART_RESTARTBLOCK) { |
| |
| if (flags & TIMER_ABSTIME) |
| return -ERESTARTNOHAND; |
| |
| restart_block->fn = posix_cpu_nsleep_restart; |
| restart_block->nanosleep.clockid = which_clock; |
| } |
| return error; |
| } |
| |
| static long posix_cpu_nsleep_restart(struct restart_block *restart_block) |
| { |
| clockid_t which_clock = restart_block->nanosleep.clockid; |
| struct timespec64 t; |
| |
| t = ns_to_timespec64(restart_block->nanosleep.expires); |
| |
| return do_cpu_nanosleep(which_clock, TIMER_ABSTIME, &t); |
| } |
| |
| #define PROCESS_CLOCK MAKE_PROCESS_CPUCLOCK(0, CPUCLOCK_SCHED) |
| #define THREAD_CLOCK MAKE_THREAD_CPUCLOCK(0, CPUCLOCK_SCHED) |
| |
| static int process_cpu_clock_getres(const clockid_t which_clock, |
| struct timespec64 *tp) |
| { |
| return posix_cpu_clock_getres(PROCESS_CLOCK, tp); |
| } |
| static int process_cpu_clock_get(const clockid_t which_clock, |
| struct timespec64 *tp) |
| { |
| return posix_cpu_clock_get(PROCESS_CLOCK, tp); |
| } |
| static int process_cpu_timer_create(struct k_itimer *timer) |
| { |
| timer->it_clock = PROCESS_CLOCK; |
| return posix_cpu_timer_create(timer); |
| } |
| static int process_cpu_nsleep(const clockid_t which_clock, int flags, |
| const struct timespec64 *rqtp) |
| { |
| return posix_cpu_nsleep(PROCESS_CLOCK, flags, rqtp); |
| } |
| static int thread_cpu_clock_getres(const clockid_t which_clock, |
| struct timespec64 *tp) |
| { |
| return posix_cpu_clock_getres(THREAD_CLOCK, tp); |
| } |
| static int thread_cpu_clock_get(const clockid_t which_clock, |
| struct timespec64 *tp) |
| { |
| return posix_cpu_clock_get(THREAD_CLOCK, tp); |
| } |
| static int thread_cpu_timer_create(struct k_itimer *timer) |
| { |
| timer->it_clock = THREAD_CLOCK; |
| return posix_cpu_timer_create(timer); |
| } |
| |
| const struct k_clock clock_posix_cpu = { |
| .clock_getres = posix_cpu_clock_getres, |
| .clock_set = posix_cpu_clock_set, |
| .clock_get = posix_cpu_clock_get, |
| .timer_create = posix_cpu_timer_create, |
| .nsleep = posix_cpu_nsleep, |
| .timer_set = posix_cpu_timer_set, |
| .timer_del = posix_cpu_timer_del, |
| .timer_get = posix_cpu_timer_get, |
| .timer_rearm = posix_cpu_timer_rearm, |
| }; |
| |
| const struct k_clock clock_process = { |
| .clock_getres = process_cpu_clock_getres, |
| .clock_get = process_cpu_clock_get, |
| .timer_create = process_cpu_timer_create, |
| .nsleep = process_cpu_nsleep, |
| }; |
| |
| const struct k_clock clock_thread = { |
| .clock_getres = thread_cpu_clock_getres, |
| .clock_get = thread_cpu_clock_get, |
| .timer_create = thread_cpu_timer_create, |
| }; |