| /* |
| * linux/kernel/itimer.c |
| * |
| * Copyright (C) 1992 Darren Senn |
| */ |
| |
| /* These are all the functions necessary to implement itimers */ |
| |
| #include <linux/mm.h> |
| #include <linux/interrupt.h> |
| #include <linux/syscalls.h> |
| #include <linux/time.h> |
| #include <linux/posix-timers.h> |
| #include <linux/hrtimer.h> |
| #include <trace/events/timer.h> |
| |
| #include <asm/uaccess.h> |
| |
| /** |
| * itimer_get_remtime - get remaining time for the timer |
| * |
| * @timer: the timer to read |
| * |
| * Returns the delta between the expiry time and now, which can be |
| * less than zero or 1usec for an pending expired timer |
| */ |
| static struct timeval itimer_get_remtime(struct hrtimer *timer) |
| { |
| ktime_t rem = hrtimer_get_remaining(timer); |
| |
| /* |
| * Racy but safe: if the itimer expires after the above |
| * hrtimer_get_remtime() call but before this condition |
| * then we return 0 - which is correct. |
| */ |
| if (hrtimer_active(timer)) { |
| if (rem.tv64 <= 0) |
| rem.tv64 = NSEC_PER_USEC; |
| } else |
| rem.tv64 = 0; |
| |
| return ktime_to_timeval(rem); |
| } |
| |
| static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id, |
| struct itimerval *const value) |
| { |
| cputime_t cval, cinterval; |
| struct cpu_itimer *it = &tsk->signal->it[clock_id]; |
| |
| spin_lock_irq(&tsk->sighand->siglock); |
| |
| cval = it->expires; |
| cinterval = it->incr; |
| if (cval) { |
| struct task_cputime cputime; |
| cputime_t t; |
| |
| thread_group_cputimer(tsk, &cputime); |
| if (clock_id == CPUCLOCK_PROF) |
| t = cputime.utime + cputime.stime; |
| else |
| /* CPUCLOCK_VIRT */ |
| t = cputime.utime; |
| |
| if (cval < t) |
| /* about to fire */ |
| cval = cputime_one_jiffy; |
| else |
| cval = cval - t; |
| } |
| |
| spin_unlock_irq(&tsk->sighand->siglock); |
| |
| cputime_to_timeval(cval, &value->it_value); |
| cputime_to_timeval(cinterval, &value->it_interval); |
| } |
| |
| int do_getitimer(int which, struct itimerval *value) |
| { |
| struct task_struct *tsk = current; |
| |
| switch (which) { |
| case ITIMER_REAL: |
| spin_lock_irq(&tsk->sighand->siglock); |
| value->it_value = itimer_get_remtime(&tsk->signal->real_timer); |
| value->it_interval = |
| ktime_to_timeval(tsk->signal->it_real_incr); |
| spin_unlock_irq(&tsk->sighand->siglock); |
| break; |
| case ITIMER_VIRTUAL: |
| get_cpu_itimer(tsk, CPUCLOCK_VIRT, value); |
| break; |
| case ITIMER_PROF: |
| get_cpu_itimer(tsk, CPUCLOCK_PROF, value); |
| break; |
| default: |
| return(-EINVAL); |
| } |
| return 0; |
| } |
| |
| SYSCALL_DEFINE2(getitimer, int, which, struct itimerval __user *, value) |
| { |
| int error = -EFAULT; |
| struct itimerval get_buffer; |
| |
| if (value) { |
| error = do_getitimer(which, &get_buffer); |
| if (!error && |
| copy_to_user(value, &get_buffer, sizeof(get_buffer))) |
| error = -EFAULT; |
| } |
| return error; |
| } |
| |
| |
| /* |
| * The timer is automagically restarted, when interval != 0 |
| */ |
| enum hrtimer_restart it_real_fn(struct hrtimer *timer) |
| { |
| struct signal_struct *sig = |
| container_of(timer, struct signal_struct, real_timer); |
| |
| trace_itimer_expire(ITIMER_REAL, sig->leader_pid, 0); |
| kill_pid_info(SIGALRM, SEND_SIG_PRIV, sig->leader_pid); |
| |
| return HRTIMER_NORESTART; |
| } |
| |
| static inline u32 cputime_sub_ns(cputime_t ct, s64 real_ns) |
| { |
| struct timespec ts; |
| s64 cpu_ns; |
| |
| cputime_to_timespec(ct, &ts); |
| cpu_ns = timespec_to_ns(&ts); |
| |
| return (cpu_ns <= real_ns) ? 0 : cpu_ns - real_ns; |
| } |
| |
| static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id, |
| const struct itimerval *const value, |
| struct itimerval *const ovalue) |
| { |
| cputime_t cval, nval, cinterval, ninterval; |
| s64 ns_ninterval, ns_nval; |
| u32 error, incr_error; |
| struct cpu_itimer *it = &tsk->signal->it[clock_id]; |
| |
| nval = timeval_to_cputime(&value->it_value); |
| ns_nval = timeval_to_ns(&value->it_value); |
| ninterval = timeval_to_cputime(&value->it_interval); |
| ns_ninterval = timeval_to_ns(&value->it_interval); |
| |
| error = cputime_sub_ns(nval, ns_nval); |
| incr_error = cputime_sub_ns(ninterval, ns_ninterval); |
| |
| spin_lock_irq(&tsk->sighand->siglock); |
| |
| cval = it->expires; |
| cinterval = it->incr; |
| if (cval || nval) { |
| if (nval > 0) |
| nval += cputime_one_jiffy; |
| set_process_cpu_timer(tsk, clock_id, &nval, &cval); |
| } |
| it->expires = nval; |
| it->incr = ninterval; |
| it->error = error; |
| it->incr_error = incr_error; |
| trace_itimer_state(clock_id == CPUCLOCK_VIRT ? |
| ITIMER_VIRTUAL : ITIMER_PROF, value, nval); |
| |
| spin_unlock_irq(&tsk->sighand->siglock); |
| |
| if (ovalue) { |
| cputime_to_timeval(cval, &ovalue->it_value); |
| cputime_to_timeval(cinterval, &ovalue->it_interval); |
| } |
| } |
| |
| /* |
| * Returns true if the timeval is in canonical form |
| */ |
| #define timeval_valid(t) \ |
| (((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC)) |
| |
| int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue) |
| { |
| struct task_struct *tsk = current; |
| struct hrtimer *timer; |
| ktime_t expires; |
| |
| /* |
| * Validate the timevals in value. |
| */ |
| if (!timeval_valid(&value->it_value) || |
| !timeval_valid(&value->it_interval)) |
| return -EINVAL; |
| |
| switch (which) { |
| case ITIMER_REAL: |
| again: |
| spin_lock_irq(&tsk->sighand->siglock); |
| timer = &tsk->signal->real_timer; |
| if (ovalue) { |
| ovalue->it_value = itimer_get_remtime(timer); |
| ovalue->it_interval |
| = ktime_to_timeval(tsk->signal->it_real_incr); |
| } |
| /* We are sharing ->siglock with it_real_fn() */ |
| if (hrtimer_try_to_cancel(timer) < 0) { |
| spin_unlock_irq(&tsk->sighand->siglock); |
| goto again; |
| } |
| expires = timeval_to_ktime(value->it_value); |
| if (expires.tv64 != 0) { |
| tsk->signal->it_real_incr = |
| timeval_to_ktime(value->it_interval); |
| hrtimer_start(timer, expires, HRTIMER_MODE_REL); |
| } else |
| tsk->signal->it_real_incr.tv64 = 0; |
| |
| trace_itimer_state(ITIMER_REAL, value, 0); |
| spin_unlock_irq(&tsk->sighand->siglock); |
| break; |
| case ITIMER_VIRTUAL: |
| set_cpu_itimer(tsk, CPUCLOCK_VIRT, value, ovalue); |
| break; |
| case ITIMER_PROF: |
| set_cpu_itimer(tsk, CPUCLOCK_PROF, value, ovalue); |
| break; |
| default: |
| return -EINVAL; |
| } |
| return 0; |
| } |
| |
| /** |
| * alarm_setitimer - set alarm in seconds |
| * |
| * @seconds: number of seconds until alarm |
| * 0 disables the alarm |
| * |
| * Returns the remaining time in seconds of a pending timer or 0 when |
| * the timer is not active. |
| * |
| * On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid |
| * negative timeval settings which would cause immediate expiry. |
| */ |
| unsigned int alarm_setitimer(unsigned int seconds) |
| { |
| struct itimerval it_new, it_old; |
| |
| #if BITS_PER_LONG < 64 |
| if (seconds > INT_MAX) |
| seconds = INT_MAX; |
| #endif |
| it_new.it_value.tv_sec = seconds; |
| it_new.it_value.tv_usec = 0; |
| it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0; |
| |
| do_setitimer(ITIMER_REAL, &it_new, &it_old); |
| |
| /* |
| * We can't return 0 if we have an alarm pending ... And we'd |
| * better return too much than too little anyway |
| */ |
| if ((!it_old.it_value.tv_sec && it_old.it_value.tv_usec) || |
| it_old.it_value.tv_usec >= 500000) |
| it_old.it_value.tv_sec++; |
| |
| return it_old.it_value.tv_sec; |
| } |
| |
| SYSCALL_DEFINE3(setitimer, int, which, struct itimerval __user *, value, |
| struct itimerval __user *, ovalue) |
| { |
| struct itimerval set_buffer, get_buffer; |
| int error; |
| |
| if (value) { |
| if(copy_from_user(&set_buffer, value, sizeof(set_buffer))) |
| return -EFAULT; |
| } else |
| memset((char *) &set_buffer, 0, sizeof(set_buffer)); |
| |
| error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL); |
| if (error || !ovalue) |
| return error; |
| |
| if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer))) |
| return -EFAULT; |
| return 0; |
| } |