1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 1992 Darren Senn
6 /* These are all the functions necessary to implement itimers */
9 #include <linux/interrupt.h>
10 #include <linux/syscalls.h>
11 #include <linux/time.h>
12 #include <linux/sched/signal.h>
13 #include <linux/sched/cputime.h>
14 #include <linux/posix-timers.h>
15 #include <linux/hrtimer.h>
16 #include <trace/events/timer.h>
17 #include <linux/compat.h>
19 #include <linux/uaccess.h>
22 * itimer_get_remtime - get remaining time for the timer
24 * @timer: the timer to read
26 * Returns the delta between the expiry time and now, which can be
27 * less than zero or 1usec for an pending expired timer
29 static struct timeval itimer_get_remtime(struct hrtimer *timer)
31 ktime_t rem = __hrtimer_get_remaining(timer, true);
34 * Racy but safe: if the itimer expires after the above
35 * hrtimer_get_remtime() call but before this condition
36 * then we return 0 - which is correct.
38 if (hrtimer_active(timer)) {
44 return ktime_to_timeval(rem);
47 static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
48 struct itimerval *const value)
51 struct cpu_itimer *it = &tsk->signal->it[clock_id];
53 spin_lock_irq(&tsk->sighand->siglock);
58 struct task_cputime cputime;
61 thread_group_cputimer(tsk, &cputime);
62 if (clock_id == CPUCLOCK_PROF)
63 t = cputime.utime + cputime.stime;
75 spin_unlock_irq(&tsk->sighand->siglock);
77 value->it_value = ns_to_timeval(val);
78 value->it_interval = ns_to_timeval(interval);
81 int do_getitimer(int which, struct itimerval *value)
83 struct task_struct *tsk = current;
87 spin_lock_irq(&tsk->sighand->siglock);
88 value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
90 ktime_to_timeval(tsk->signal->it_real_incr);
91 spin_unlock_irq(&tsk->sighand->siglock);
94 get_cpu_itimer(tsk, CPUCLOCK_VIRT, value);
97 get_cpu_itimer(tsk, CPUCLOCK_PROF, value);
105 SYSCALL_DEFINE2(getitimer, int, which, struct itimerval __user *, value)
108 struct itimerval get_buffer;
111 error = do_getitimer(which, &get_buffer);
113 copy_to_user(value, &get_buffer, sizeof(get_buffer)))
120 COMPAT_SYSCALL_DEFINE2(getitimer, int, which,
121 struct compat_itimerval __user *, it)
123 struct itimerval kit;
124 int error = do_getitimer(which, &kit);
126 if (!error && put_compat_itimerval(it, &kit))
134 * The timer is automagically restarted, when interval != 0
136 enum hrtimer_restart it_real_fn(struct hrtimer *timer)
138 struct signal_struct *sig =
139 container_of(timer, struct signal_struct, real_timer);
140 struct pid *leader_pid = sig->pids[PIDTYPE_TGID];
142 trace_itimer_expire(ITIMER_REAL, leader_pid, 0);
143 kill_pid_info(SIGALRM, SEND_SIG_PRIV, leader_pid);
145 return HRTIMER_NORESTART;
148 static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
149 const struct itimerval *const value,
150 struct itimerval *const ovalue)
152 u64 oval, nval, ointerval, ninterval;
153 struct cpu_itimer *it = &tsk->signal->it[clock_id];
156 * Use the to_ktime conversion because that clamps the maximum
157 * value to KTIME_MAX and avoid multiplication overflows.
159 nval = ktime_to_ns(timeval_to_ktime(value->it_value));
160 ninterval = ktime_to_ns(timeval_to_ktime(value->it_interval));
162 spin_lock_irq(&tsk->sighand->siglock);
165 ointerval = it->incr;
169 set_process_cpu_timer(tsk, clock_id, &nval, &oval);
172 it->incr = ninterval;
173 trace_itimer_state(clock_id == CPUCLOCK_VIRT ?
174 ITIMER_VIRTUAL : ITIMER_PROF, value, nval);
176 spin_unlock_irq(&tsk->sighand->siglock);
179 ovalue->it_value = ns_to_timeval(oval);
180 ovalue->it_interval = ns_to_timeval(ointerval);
185 * Returns true if the timeval is in canonical form
187 #define timeval_valid(t) \
188 (((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC))
190 int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
192 struct task_struct *tsk = current;
193 struct hrtimer *timer;
197 * Validate the timevals in value.
199 if (!timeval_valid(&value->it_value) ||
200 !timeval_valid(&value->it_interval))
206 spin_lock_irq(&tsk->sighand->siglock);
207 timer = &tsk->signal->real_timer;
209 ovalue->it_value = itimer_get_remtime(timer);
211 = ktime_to_timeval(tsk->signal->it_real_incr);
213 /* We are sharing ->siglock with it_real_fn() */
214 if (hrtimer_try_to_cancel(timer) < 0) {
215 spin_unlock_irq(&tsk->sighand->siglock);
218 expires = timeval_to_ktime(value->it_value);
220 tsk->signal->it_real_incr =
221 timeval_to_ktime(value->it_interval);
222 hrtimer_start(timer, expires, HRTIMER_MODE_REL);
224 tsk->signal->it_real_incr = 0;
226 trace_itimer_state(ITIMER_REAL, value, 0);
227 spin_unlock_irq(&tsk->sighand->siglock);
230 set_cpu_itimer(tsk, CPUCLOCK_VIRT, value, ovalue);
233 set_cpu_itimer(tsk, CPUCLOCK_PROF, value, ovalue);
241 #ifdef __ARCH_WANT_SYS_ALARM
244 * alarm_setitimer - set alarm in seconds
246 * @seconds: number of seconds until alarm
247 * 0 disables the alarm
249 * Returns the remaining time in seconds of a pending timer or 0 when
250 * the timer is not active.
252 * On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid
253 * negative timeval settings which would cause immediate expiry.
255 static unsigned int alarm_setitimer(unsigned int seconds)
257 struct itimerval it_new, it_old;
259 #if BITS_PER_LONG < 64
260 if (seconds > INT_MAX)
263 it_new.it_value.tv_sec = seconds;
264 it_new.it_value.tv_usec = 0;
265 it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
267 do_setitimer(ITIMER_REAL, &it_new, &it_old);
270 * We can't return 0 if we have an alarm pending ... And we'd
271 * better return too much than too little anyway
273 if ((!it_old.it_value.tv_sec && it_old.it_value.tv_usec) ||
274 it_old.it_value.tv_usec >= 500000)
275 it_old.it_value.tv_sec++;
277 return it_old.it_value.tv_sec;
281 * For backwards compatibility? This can be done in libc so Alpha
282 * and all newer ports shouldn't need it.
284 SYSCALL_DEFINE1(alarm, unsigned int, seconds)
286 return alarm_setitimer(seconds);
291 SYSCALL_DEFINE3(setitimer, int, which, struct itimerval __user *, value,
292 struct itimerval __user *, ovalue)
294 struct itimerval set_buffer, get_buffer;
298 if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
301 memset(&set_buffer, 0, sizeof(set_buffer));
302 printk_once(KERN_WARNING "%s calls setitimer() with new_value NULL pointer."
303 " Misfeature support will be removed\n",
307 error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
308 if (error || !ovalue)
311 if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))
317 COMPAT_SYSCALL_DEFINE3(setitimer, int, which,
318 struct compat_itimerval __user *, in,
319 struct compat_itimerval __user *, out)
321 struct itimerval kin, kout;
325 if (get_compat_itimerval(&kin, in))
328 memset(&kin, 0, sizeof(kin));
331 error = do_setitimer(which, &kin, out ? &kout : NULL);
334 if (put_compat_itimerval(out, &kout))