/* * linux/kernel/itimer.c * * Copyright (C) 1992 Darren Senn */ /* These are all the functions necessary to implement itimers */ #include <linux/mm.h> #include <linux/smp_lock.h> #include <linux/interrupt.h> #include <linux/syscalls.h> #include <linux/time.h> #include <linux/posix-timers.h> #include <linux/hrtimer.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); } int do_getitimer(int which, struct itimerval *value) { struct task_struct *tsk = current; cputime_t cinterval, cval; 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: read_lock(&tasklist_lock); spin_lock_irq(&tsk->sighand->siglock); cval = tsk->signal->it_virt_expires; cinterval = tsk->signal->it_virt_incr; if (!cputime_eq(cval, cputime_zero)) { struct task_struct *t = tsk; cputime_t utime = tsk->signal->utime; do { utime = cputime_add(utime, t->utime); t = next_thread(t); } while (t != tsk); if (cputime_le(cval, utime)) { /* about to fire */ cval = jiffies_to_cputime(1); } else { cval = cputime_sub(cval, utime); } } spin_unlock_irq(&tsk->sighand->siglock); read_unlock(&tasklist_lock); cputime_to_timeval(cval, &value->it_value); cputime_to_timeval(cinterval, &value->it_interval); break; case ITIMER_PROF: read_lock(&tasklist_lock); spin_lock_irq(&tsk->sighand->siglock); cval = tsk->signal->it_prof_expires; cinterval = tsk->signal->it_prof_incr; if (!cputime_eq(cval, cputime_zero)) { struct task_struct *t = tsk; cputime_t ptime = cputime_add(tsk->signal->utime, tsk->signal->stime); do { ptime = cputime_add(ptime, cputime_add(t->utime, t->stime)); t = next_thread(t); } while (t != tsk); if (cputime_le(cval, ptime)) { /* about to fire */ cval = jiffies_to_cputime(1); } else { cval = cputime_sub(cval, ptime); } } spin_unlock_irq(&tsk->sighand->siglock); read_unlock(&tasklist_lock); cputime_to_timeval(cval, &value->it_value); cputime_to_timeval(cinterval, &value->it_interval); break; default: return(-EINVAL); } return 0; } asmlinkage long sys_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); send_group_sig_info(SIGALRM, SEND_SIG_PRIV, sig->tsk); return HRTIMER_NORESTART; } /* * We do not care about correctness. We just sanitize the values so * the ktime_t operations which expect normalized values do not * break. This converts negative values to long timeouts similar to * the code in kernel versions < 2.6.16 * * Print a limited number of warning messages when an invalid timeval * is detected. */ static void fixup_timeval(struct timeval *tv, int interval) { static int warnlimit = 10; unsigned long tmp; if (warnlimit > 0) { warnlimit--; printk(KERN_WARNING "setitimer: %s (pid = %d) provided " "invalid timeval %s: tv_sec = %ld tv_usec = %ld\n", current->comm, current->pid, interval ? "it_interval" : "it_value", tv->tv_sec, (long) tv->tv_usec); } tmp = tv->tv_usec; if (tmp >= USEC_PER_SEC) { tv->tv_usec = tmp % USEC_PER_SEC; tv->tv_sec += tmp / USEC_PER_SEC; } tmp = tv->tv_sec; if (tmp > LONG_MAX) tv->tv_sec = LONG_MAX; } /* * 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)) /* * Check for invalid timevals, sanitize them and print a limited * number of warnings. */ static void check_itimerval(struct itimerval *value) { if (unlikely(!timeval_valid(&value->it_value))) fixup_timeval(&value->it_value, 0); if (unlikely(!timeval_valid(&value->it_interval))) fixup_timeval(&value->it_interval, 1); } int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue) { struct task_struct *tsk = current; struct hrtimer *timer; ktime_t expires; cputime_t cval, cinterval, nval, ninterval; /* * Validate the timevals in value. * * Note: Although the spec requires that invalid values shall * return -EINVAL, we just fixup the value and print a limited * number of warnings in order not to break users of this * historical misfeature. * * Scheduled for replacement in March 2007 */ check_itimerval(value); 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; spin_unlock_irq(&tsk->sighand->siglock); break; case ITIMER_VIRTUAL: nval = timeval_to_cputime(&value->it_value); ninterval = timeval_to_cputime(&value->it_interval); read_lock(&tasklist_lock); spin_lock_irq(&tsk->sighand->siglock); cval = tsk->signal->it_virt_expires; cinterval = tsk->signal->it_virt_incr; if (!cputime_eq(cval, cputime_zero) || !cputime_eq(nval, cputime_zero)) { if (cputime_gt(nval, cputime_zero)) nval = cputime_add(nval, jiffies_to_cputime(1)); set_process_cpu_timer(tsk, CPUCLOCK_VIRT, &nval, &cval); } tsk->signal->it_virt_expires = nval; tsk->signal->it_virt_incr = ninterval; spin_unlock_irq(&tsk->sighand->siglock); read_unlock(&tasklist_lock); if (ovalue) { cputime_to_timeval(cval, &ovalue->it_value); cputime_to_timeval(cinterval, &ovalue->it_interval); } break; case ITIMER_PROF: nval = timeval_to_cputime(&value->it_value); ninterval = timeval_to_cputime(&value->it_interval); read_lock(&tasklist_lock); spin_lock_irq(&tsk->sighand->siglock); cval = tsk->signal->it_prof_expires; cinterval = tsk->signal->it_prof_incr; if (!cputime_eq(cval, cputime_zero) || !cputime_eq(nval, cputime_zero)) { if (cputime_gt(nval, cputime_zero)) nval = cputime_add(nval, jiffies_to_cputime(1)); set_process_cpu_timer(tsk, CPUCLOCK_PROF, &nval, &cval); } tsk->signal->it_prof_expires = nval; tsk->signal->it_prof_incr = ninterval; spin_unlock_irq(&tsk->sighand->siglock); read_unlock(&tasklist_lock); if (ovalue) { cputime_to_timeval(cval, &ovalue->it_value); cputime_to_timeval(cinterval, &ovalue->it_interval); } 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; } asmlinkage long sys_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; }