15cee9645SThomas Gleixner /* 25cee9645SThomas Gleixner * linux/kernel/itimer.c 35cee9645SThomas Gleixner * 45cee9645SThomas Gleixner * Copyright (C) 1992 Darren Senn 55cee9645SThomas Gleixner */ 65cee9645SThomas Gleixner 75cee9645SThomas Gleixner /* These are all the functions necessary to implement itimers */ 85cee9645SThomas Gleixner 95cee9645SThomas Gleixner #include <linux/mm.h> 105cee9645SThomas Gleixner #include <linux/interrupt.h> 115cee9645SThomas Gleixner #include <linux/syscalls.h> 125cee9645SThomas Gleixner #include <linux/time.h> 133f07c014SIngo Molnar #include <linux/sched/signal.h> 145cee9645SThomas Gleixner #include <linux/posix-timers.h> 155cee9645SThomas Gleixner #include <linux/hrtimer.h> 165cee9645SThomas Gleixner #include <trace/events/timer.h> 175cee9645SThomas Gleixner 187c0f6ba6SLinus Torvalds #include <linux/uaccess.h> 195cee9645SThomas Gleixner 205cee9645SThomas Gleixner /** 215cee9645SThomas Gleixner * itimer_get_remtime - get remaining time for the timer 225cee9645SThomas Gleixner * 235cee9645SThomas Gleixner * @timer: the timer to read 245cee9645SThomas Gleixner * 255cee9645SThomas Gleixner * Returns the delta between the expiry time and now, which can be 265cee9645SThomas Gleixner * less than zero or 1usec for an pending expired timer 275cee9645SThomas Gleixner */ 285cee9645SThomas Gleixner static struct timeval itimer_get_remtime(struct hrtimer *timer) 295cee9645SThomas Gleixner { 3051cbb524SThomas Gleixner ktime_t rem = __hrtimer_get_remaining(timer, true); 315cee9645SThomas Gleixner 325cee9645SThomas Gleixner /* 335cee9645SThomas Gleixner * Racy but safe: if the itimer expires after the above 345cee9645SThomas Gleixner * hrtimer_get_remtime() call but before this condition 355cee9645SThomas Gleixner * then we return 0 - which is correct. 365cee9645SThomas Gleixner */ 375cee9645SThomas Gleixner if (hrtimer_active(timer)) { 382456e855SThomas Gleixner if (rem <= 0) 392456e855SThomas Gleixner rem = NSEC_PER_USEC; 405cee9645SThomas Gleixner } else 412456e855SThomas Gleixner rem = 0; 425cee9645SThomas Gleixner 435cee9645SThomas Gleixner return ktime_to_timeval(rem); 445cee9645SThomas Gleixner } 455cee9645SThomas Gleixner 465cee9645SThomas Gleixner static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id, 475cee9645SThomas Gleixner struct itimerval *const value) 485cee9645SThomas Gleixner { 49858cf3a8SFrederic Weisbecker u64 val, interval; 505cee9645SThomas Gleixner struct cpu_itimer *it = &tsk->signal->it[clock_id]; 515cee9645SThomas Gleixner 525cee9645SThomas Gleixner spin_lock_irq(&tsk->sighand->siglock); 535cee9645SThomas Gleixner 54858cf3a8SFrederic Weisbecker val = it->expires; 55858cf3a8SFrederic Weisbecker interval = it->incr; 56858cf3a8SFrederic Weisbecker if (val) { 57ebd7e7fcSFrederic Weisbecker struct task_cputime cputime; 58858cf3a8SFrederic Weisbecker u64 t; 595cee9645SThomas Gleixner 605cee9645SThomas Gleixner thread_group_cputimer(tsk, &cputime); 615cee9645SThomas Gleixner if (clock_id == CPUCLOCK_PROF) 62858cf3a8SFrederic Weisbecker t = cputime.utime + cputime.stime; 635cee9645SThomas Gleixner else 645cee9645SThomas Gleixner /* CPUCLOCK_VIRT */ 65858cf3a8SFrederic Weisbecker t = cputime.utime; 665cee9645SThomas Gleixner 67858cf3a8SFrederic Weisbecker if (val < t) 685cee9645SThomas Gleixner /* about to fire */ 69858cf3a8SFrederic Weisbecker val = TICK_NSEC; 705cee9645SThomas Gleixner else 71858cf3a8SFrederic Weisbecker val -= t; 725cee9645SThomas Gleixner } 735cee9645SThomas Gleixner 745cee9645SThomas Gleixner spin_unlock_irq(&tsk->sighand->siglock); 755cee9645SThomas Gleixner 76858cf3a8SFrederic Weisbecker value->it_value = ns_to_timeval(val); 77858cf3a8SFrederic Weisbecker value->it_interval = ns_to_timeval(interval); 785cee9645SThomas Gleixner } 795cee9645SThomas Gleixner 805cee9645SThomas Gleixner int do_getitimer(int which, struct itimerval *value) 815cee9645SThomas Gleixner { 825cee9645SThomas Gleixner struct task_struct *tsk = current; 835cee9645SThomas Gleixner 845cee9645SThomas Gleixner switch (which) { 855cee9645SThomas Gleixner case ITIMER_REAL: 865cee9645SThomas Gleixner spin_lock_irq(&tsk->sighand->siglock); 875cee9645SThomas Gleixner value->it_value = itimer_get_remtime(&tsk->signal->real_timer); 885cee9645SThomas Gleixner value->it_interval = 895cee9645SThomas Gleixner ktime_to_timeval(tsk->signal->it_real_incr); 905cee9645SThomas Gleixner spin_unlock_irq(&tsk->sighand->siglock); 915cee9645SThomas Gleixner break; 925cee9645SThomas Gleixner case ITIMER_VIRTUAL: 935cee9645SThomas Gleixner get_cpu_itimer(tsk, CPUCLOCK_VIRT, value); 945cee9645SThomas Gleixner break; 955cee9645SThomas Gleixner case ITIMER_PROF: 965cee9645SThomas Gleixner get_cpu_itimer(tsk, CPUCLOCK_PROF, value); 975cee9645SThomas Gleixner break; 985cee9645SThomas Gleixner default: 995cee9645SThomas Gleixner return(-EINVAL); 1005cee9645SThomas Gleixner } 1015cee9645SThomas Gleixner return 0; 1025cee9645SThomas Gleixner } 1035cee9645SThomas Gleixner 1045cee9645SThomas Gleixner SYSCALL_DEFINE2(getitimer, int, which, struct itimerval __user *, value) 1055cee9645SThomas Gleixner { 1065cee9645SThomas Gleixner int error = -EFAULT; 1075cee9645SThomas Gleixner struct itimerval get_buffer; 1085cee9645SThomas Gleixner 1095cee9645SThomas Gleixner if (value) { 1105cee9645SThomas Gleixner error = do_getitimer(which, &get_buffer); 1115cee9645SThomas Gleixner if (!error && 1125cee9645SThomas Gleixner copy_to_user(value, &get_buffer, sizeof(get_buffer))) 1135cee9645SThomas Gleixner error = -EFAULT; 1145cee9645SThomas Gleixner } 1155cee9645SThomas Gleixner return error; 1165cee9645SThomas Gleixner } 1175cee9645SThomas Gleixner 1185cee9645SThomas Gleixner 1195cee9645SThomas Gleixner /* 1205cee9645SThomas Gleixner * The timer is automagically restarted, when interval != 0 1215cee9645SThomas Gleixner */ 1225cee9645SThomas Gleixner enum hrtimer_restart it_real_fn(struct hrtimer *timer) 1235cee9645SThomas Gleixner { 1245cee9645SThomas Gleixner struct signal_struct *sig = 1255cee9645SThomas Gleixner container_of(timer, struct signal_struct, real_timer); 1265cee9645SThomas Gleixner 1275cee9645SThomas Gleixner trace_itimer_expire(ITIMER_REAL, sig->leader_pid, 0); 1285cee9645SThomas Gleixner kill_pid_info(SIGALRM, SEND_SIG_PRIV, sig->leader_pid); 1295cee9645SThomas Gleixner 1305cee9645SThomas Gleixner return HRTIMER_NORESTART; 1315cee9645SThomas Gleixner } 1325cee9645SThomas Gleixner 1335cee9645SThomas Gleixner static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id, 1345cee9645SThomas Gleixner const struct itimerval *const value, 1355cee9645SThomas Gleixner struct itimerval *const ovalue) 1365cee9645SThomas Gleixner { 137858cf3a8SFrederic Weisbecker u64 oval, nval, ointerval, ninterval; 1385cee9645SThomas Gleixner struct cpu_itimer *it = &tsk->signal->it[clock_id]; 1395cee9645SThomas Gleixner 140858cf3a8SFrederic Weisbecker nval = timeval_to_ns(&value->it_value); 141858cf3a8SFrederic Weisbecker ninterval = timeval_to_ns(&value->it_interval); 1425cee9645SThomas Gleixner 1435cee9645SThomas Gleixner spin_lock_irq(&tsk->sighand->siglock); 1445cee9645SThomas Gleixner 145858cf3a8SFrederic Weisbecker oval = it->expires; 146858cf3a8SFrederic Weisbecker ointerval = it->incr; 147858cf3a8SFrederic Weisbecker if (oval || nval) { 1485cee9645SThomas Gleixner if (nval > 0) 149858cf3a8SFrederic Weisbecker nval += TICK_NSEC; 150858cf3a8SFrederic Weisbecker set_process_cpu_timer(tsk, clock_id, &nval, &oval); 1515cee9645SThomas Gleixner } 1525cee9645SThomas Gleixner it->expires = nval; 1535cee9645SThomas Gleixner it->incr = ninterval; 1545cee9645SThomas Gleixner trace_itimer_state(clock_id == CPUCLOCK_VIRT ? 1555cee9645SThomas Gleixner ITIMER_VIRTUAL : ITIMER_PROF, value, nval); 1565cee9645SThomas Gleixner 1575cee9645SThomas Gleixner spin_unlock_irq(&tsk->sighand->siglock); 1585cee9645SThomas Gleixner 1595cee9645SThomas Gleixner if (ovalue) { 160858cf3a8SFrederic Weisbecker ovalue->it_value = ns_to_timeval(oval); 161858cf3a8SFrederic Weisbecker ovalue->it_interval = ns_to_timeval(ointerval); 1625cee9645SThomas Gleixner } 1635cee9645SThomas Gleixner } 1645cee9645SThomas Gleixner 1655cee9645SThomas Gleixner /* 1665cee9645SThomas Gleixner * Returns true if the timeval is in canonical form 1675cee9645SThomas Gleixner */ 1685cee9645SThomas Gleixner #define timeval_valid(t) \ 1695cee9645SThomas Gleixner (((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC)) 1705cee9645SThomas Gleixner 1715cee9645SThomas Gleixner int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue) 1725cee9645SThomas Gleixner { 1735cee9645SThomas Gleixner struct task_struct *tsk = current; 1745cee9645SThomas Gleixner struct hrtimer *timer; 1755cee9645SThomas Gleixner ktime_t expires; 1765cee9645SThomas Gleixner 1775cee9645SThomas Gleixner /* 1785cee9645SThomas Gleixner * Validate the timevals in value. 1795cee9645SThomas Gleixner */ 1805cee9645SThomas Gleixner if (!timeval_valid(&value->it_value) || 1815cee9645SThomas Gleixner !timeval_valid(&value->it_interval)) 1825cee9645SThomas Gleixner return -EINVAL; 1835cee9645SThomas Gleixner 1845cee9645SThomas Gleixner switch (which) { 1855cee9645SThomas Gleixner case ITIMER_REAL: 1865cee9645SThomas Gleixner again: 1875cee9645SThomas Gleixner spin_lock_irq(&tsk->sighand->siglock); 1885cee9645SThomas Gleixner timer = &tsk->signal->real_timer; 1895cee9645SThomas Gleixner if (ovalue) { 1905cee9645SThomas Gleixner ovalue->it_value = itimer_get_remtime(timer); 1915cee9645SThomas Gleixner ovalue->it_interval 1925cee9645SThomas Gleixner = ktime_to_timeval(tsk->signal->it_real_incr); 1935cee9645SThomas Gleixner } 1945cee9645SThomas Gleixner /* We are sharing ->siglock with it_real_fn() */ 1955cee9645SThomas Gleixner if (hrtimer_try_to_cancel(timer) < 0) { 1965cee9645SThomas Gleixner spin_unlock_irq(&tsk->sighand->siglock); 1975cee9645SThomas Gleixner goto again; 1985cee9645SThomas Gleixner } 1995cee9645SThomas Gleixner expires = timeval_to_ktime(value->it_value); 2002456e855SThomas Gleixner if (expires != 0) { 2015cee9645SThomas Gleixner tsk->signal->it_real_incr = 2025cee9645SThomas Gleixner timeval_to_ktime(value->it_interval); 2035cee9645SThomas Gleixner hrtimer_start(timer, expires, HRTIMER_MODE_REL); 2045cee9645SThomas Gleixner } else 2052456e855SThomas Gleixner tsk->signal->it_real_incr = 0; 2065cee9645SThomas Gleixner 2075cee9645SThomas Gleixner trace_itimer_state(ITIMER_REAL, value, 0); 2085cee9645SThomas Gleixner spin_unlock_irq(&tsk->sighand->siglock); 2095cee9645SThomas Gleixner break; 2105cee9645SThomas Gleixner case ITIMER_VIRTUAL: 2115cee9645SThomas Gleixner set_cpu_itimer(tsk, CPUCLOCK_VIRT, value, ovalue); 2125cee9645SThomas Gleixner break; 2135cee9645SThomas Gleixner case ITIMER_PROF: 2145cee9645SThomas Gleixner set_cpu_itimer(tsk, CPUCLOCK_PROF, value, ovalue); 2155cee9645SThomas Gleixner break; 2165cee9645SThomas Gleixner default: 2175cee9645SThomas Gleixner return -EINVAL; 2185cee9645SThomas Gleixner } 2195cee9645SThomas Gleixner return 0; 2205cee9645SThomas Gleixner } 2215cee9645SThomas Gleixner 22274ba181eSNicolas Pitre #ifdef __ARCH_WANT_SYS_ALARM 22374ba181eSNicolas Pitre 2245cee9645SThomas Gleixner /** 2255cee9645SThomas Gleixner * alarm_setitimer - set alarm in seconds 2265cee9645SThomas Gleixner * 2275cee9645SThomas Gleixner * @seconds: number of seconds until alarm 2285cee9645SThomas Gleixner * 0 disables the alarm 2295cee9645SThomas Gleixner * 2305cee9645SThomas Gleixner * Returns the remaining time in seconds of a pending timer or 0 when 2315cee9645SThomas Gleixner * the timer is not active. 2325cee9645SThomas Gleixner * 2335cee9645SThomas Gleixner * On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid 2345cee9645SThomas Gleixner * negative timeval settings which would cause immediate expiry. 2355cee9645SThomas Gleixner */ 23674ba181eSNicolas Pitre static unsigned int alarm_setitimer(unsigned int seconds) 2375cee9645SThomas Gleixner { 2385cee9645SThomas Gleixner struct itimerval it_new, it_old; 2395cee9645SThomas Gleixner 2405cee9645SThomas Gleixner #if BITS_PER_LONG < 64 2415cee9645SThomas Gleixner if (seconds > INT_MAX) 2425cee9645SThomas Gleixner seconds = INT_MAX; 2435cee9645SThomas Gleixner #endif 2445cee9645SThomas Gleixner it_new.it_value.tv_sec = seconds; 2455cee9645SThomas Gleixner it_new.it_value.tv_usec = 0; 2465cee9645SThomas Gleixner it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0; 2475cee9645SThomas Gleixner 2485cee9645SThomas Gleixner do_setitimer(ITIMER_REAL, &it_new, &it_old); 2495cee9645SThomas Gleixner 2505cee9645SThomas Gleixner /* 2515cee9645SThomas Gleixner * We can't return 0 if we have an alarm pending ... And we'd 2525cee9645SThomas Gleixner * better return too much than too little anyway 2535cee9645SThomas Gleixner */ 2545cee9645SThomas Gleixner if ((!it_old.it_value.tv_sec && it_old.it_value.tv_usec) || 2555cee9645SThomas Gleixner it_old.it_value.tv_usec >= 500000) 2565cee9645SThomas Gleixner it_old.it_value.tv_sec++; 2575cee9645SThomas Gleixner 2585cee9645SThomas Gleixner return it_old.it_value.tv_sec; 2595cee9645SThomas Gleixner } 2605cee9645SThomas Gleixner 26174ba181eSNicolas Pitre /* 26274ba181eSNicolas Pitre * For backwards compatibility? This can be done in libc so Alpha 26374ba181eSNicolas Pitre * and all newer ports shouldn't need it. 26474ba181eSNicolas Pitre */ 26574ba181eSNicolas Pitre SYSCALL_DEFINE1(alarm, unsigned int, seconds) 26674ba181eSNicolas Pitre { 26774ba181eSNicolas Pitre return alarm_setitimer(seconds); 26874ba181eSNicolas Pitre } 26974ba181eSNicolas Pitre 27074ba181eSNicolas Pitre #endif 27174ba181eSNicolas Pitre 2725cee9645SThomas Gleixner SYSCALL_DEFINE3(setitimer, int, which, struct itimerval __user *, value, 2735cee9645SThomas Gleixner struct itimerval __user *, ovalue) 2745cee9645SThomas Gleixner { 2755cee9645SThomas Gleixner struct itimerval set_buffer, get_buffer; 2765cee9645SThomas Gleixner int error; 2775cee9645SThomas Gleixner 2785cee9645SThomas Gleixner if (value) { 2795cee9645SThomas Gleixner if(copy_from_user(&set_buffer, value, sizeof(set_buffer))) 2805cee9645SThomas Gleixner return -EFAULT; 2815cee9645SThomas Gleixner } else { 2825cee9645SThomas Gleixner memset(&set_buffer, 0, sizeof(set_buffer)); 2835cee9645SThomas Gleixner printk_once(KERN_WARNING "%s calls setitimer() with new_value NULL pointer." 2845cee9645SThomas Gleixner " Misfeature support will be removed\n", 2855cee9645SThomas Gleixner current->comm); 2865cee9645SThomas Gleixner } 2875cee9645SThomas Gleixner 2885cee9645SThomas Gleixner error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL); 2895cee9645SThomas Gleixner if (error || !ovalue) 2905cee9645SThomas Gleixner return error; 2915cee9645SThomas Gleixner 2925cee9645SThomas Gleixner if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer))) 2935cee9645SThomas Gleixner return -EFAULT; 2945cee9645SThomas Gleixner return 0; 2955cee9645SThomas Gleixner } 296