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 u64 t, samples[CPUCLOCK_MAX];
60 thread_group_sample_cputime(tsk, samples);
61 t = samples[clock_id];
70 spin_unlock_irq(&tsk->sighand->siglock);
72 value->it_value = ns_to_timeval(val);
73 value->it_interval = ns_to_timeval(interval);
76 int do_getitimer(int which, struct itimerval *value)
78 struct task_struct *tsk = current;
82 spin_lock_irq(&tsk->sighand->siglock);
83 value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
85 ktime_to_timeval(tsk->signal->it_real_incr);
86 spin_unlock_irq(&tsk->sighand->siglock);
89 get_cpu_itimer(tsk, CPUCLOCK_VIRT, value);
92 get_cpu_itimer(tsk, CPUCLOCK_PROF, value);
100 SYSCALL_DEFINE2(getitimer, int, which, struct itimerval __user *, value)
103 struct itimerval get_buffer;
106 error = do_getitimer(which, &get_buffer);
108 copy_to_user(value, &get_buffer, sizeof(get_buffer)))
115 COMPAT_SYSCALL_DEFINE2(getitimer, int, which,
116 struct compat_itimerval __user *, it)
118 struct itimerval kit;
119 int error = do_getitimer(which, &kit);
121 if (!error && put_compat_itimerval(it, &kit))
129 * The timer is automagically restarted, when interval != 0
131 enum hrtimer_restart it_real_fn(struct hrtimer *timer)
133 struct signal_struct *sig =
134 container_of(timer, struct signal_struct, real_timer);
135 struct pid *leader_pid = sig->pids[PIDTYPE_TGID];
137 trace_itimer_expire(ITIMER_REAL, leader_pid, 0);
138 kill_pid_info(SIGALRM, SEND_SIG_PRIV, leader_pid);
140 return HRTIMER_NORESTART;
143 static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
144 const struct itimerval *const value,
145 struct itimerval *const ovalue)
147 u64 oval, nval, ointerval, ninterval;
148 struct cpu_itimer *it = &tsk->signal->it[clock_id];
151 * Use the to_ktime conversion because that clamps the maximum
152 * value to KTIME_MAX and avoid multiplication overflows.
154 nval = ktime_to_ns(timeval_to_ktime(value->it_value));
155 ninterval = ktime_to_ns(timeval_to_ktime(value->it_interval));
157 spin_lock_irq(&tsk->sighand->siglock);
160 ointerval = it->incr;
164 set_process_cpu_timer(tsk, clock_id, &nval, &oval);
167 it->incr = ninterval;
168 trace_itimer_state(clock_id == CPUCLOCK_VIRT ?
169 ITIMER_VIRTUAL : ITIMER_PROF, value, nval);
171 spin_unlock_irq(&tsk->sighand->siglock);
174 ovalue->it_value = ns_to_timeval(oval);
175 ovalue->it_interval = ns_to_timeval(ointerval);
180 * Returns true if the timeval is in canonical form
182 #define timeval_valid(t) \
183 (((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC))
185 int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
187 struct task_struct *tsk = current;
188 struct hrtimer *timer;
192 * Validate the timevals in value.
194 if (!timeval_valid(&value->it_value) ||
195 !timeval_valid(&value->it_interval))
201 spin_lock_irq(&tsk->sighand->siglock);
202 timer = &tsk->signal->real_timer;
204 ovalue->it_value = itimer_get_remtime(timer);
206 = ktime_to_timeval(tsk->signal->it_real_incr);
208 /* We are sharing ->siglock with it_real_fn() */
209 if (hrtimer_try_to_cancel(timer) < 0) {
210 spin_unlock_irq(&tsk->sighand->siglock);
211 hrtimer_cancel_wait_running(timer);
214 expires = timeval_to_ktime(value->it_value);
216 tsk->signal->it_real_incr =
217 timeval_to_ktime(value->it_interval);
218 hrtimer_start(timer, expires, HRTIMER_MODE_REL);
220 tsk->signal->it_real_incr = 0;
222 trace_itimer_state(ITIMER_REAL, value, 0);
223 spin_unlock_irq(&tsk->sighand->siglock);
226 set_cpu_itimer(tsk, CPUCLOCK_VIRT, value, ovalue);
229 set_cpu_itimer(tsk, CPUCLOCK_PROF, value, ovalue);
237 #ifdef __ARCH_WANT_SYS_ALARM
240 * alarm_setitimer - set alarm in seconds
242 * @seconds: number of seconds until alarm
243 * 0 disables the alarm
245 * Returns the remaining time in seconds of a pending timer or 0 when
246 * the timer is not active.
248 * On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid
249 * negative timeval settings which would cause immediate expiry.
251 static unsigned int alarm_setitimer(unsigned int seconds)
253 struct itimerval it_new, it_old;
255 #if BITS_PER_LONG < 64
256 if (seconds > INT_MAX)
259 it_new.it_value.tv_sec = seconds;
260 it_new.it_value.tv_usec = 0;
261 it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
263 do_setitimer(ITIMER_REAL, &it_new, &it_old);
266 * We can't return 0 if we have an alarm pending ... And we'd
267 * better return too much than too little anyway
269 if ((!it_old.it_value.tv_sec && it_old.it_value.tv_usec) ||
270 it_old.it_value.tv_usec >= 500000)
271 it_old.it_value.tv_sec++;
273 return it_old.it_value.tv_sec;
277 * For backwards compatibility? This can be done in libc so Alpha
278 * and all newer ports shouldn't need it.
280 SYSCALL_DEFINE1(alarm, unsigned int, seconds)
282 return alarm_setitimer(seconds);
287 SYSCALL_DEFINE3(setitimer, int, which, struct itimerval __user *, value,
288 struct itimerval __user *, ovalue)
290 struct itimerval set_buffer, get_buffer;
294 if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
297 memset(&set_buffer, 0, sizeof(set_buffer));
298 printk_once(KERN_WARNING "%s calls setitimer() with new_value NULL pointer."
299 " Misfeature support will be removed\n",
303 error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
304 if (error || !ovalue)
307 if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))
313 COMPAT_SYSCALL_DEFINE3(setitimer, int, which,
314 struct compat_itimerval __user *, in,
315 struct compat_itimerval __user *, out)
317 struct itimerval kin, kout;
321 if (get_compat_itimerval(&kin, in))
324 memset(&kin, 0, sizeof(kin));
327 error = do_setitimer(which, &kin, out ? &kout : NULL);
330 if (put_compat_itimerval(out, &kout))