2 * linux/kernel/itimer.c
4 * Copyright (C) 1992 Darren Senn
7 /* These are all the functions necessary to implement itimers */
10 #include <linux/interrupt.h>
11 #include <linux/syscalls.h>
12 #include <linux/time.h>
13 #include <linux/posix-timers.h>
14 #include <linux/hrtimer.h>
15 #include <trace/events/timer.h>
17 #include <linux/uaccess.h>
20 * itimer_get_remtime - get remaining time for the timer
22 * @timer: the timer to read
24 * Returns the delta between the expiry time and now, which can be
25 * less than zero or 1usec for an pending expired timer
27 static struct timeval itimer_get_remtime(struct hrtimer *timer)
29 ktime_t rem = __hrtimer_get_remaining(timer, true);
32 * Racy but safe: if the itimer expires after the above
33 * hrtimer_get_remtime() call but before this condition
34 * then we return 0 - which is correct.
36 if (hrtimer_active(timer)) {
42 return ktime_to_timeval(rem);
45 static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
46 struct itimerval *const value)
49 struct cpu_itimer *it = &tsk->signal->it[clock_id];
51 spin_lock_irq(&tsk->sighand->siglock);
56 struct task_cputime cputime;
59 thread_group_cputimer(tsk, &cputime);
60 if (clock_id == CPUCLOCK_PROF)
61 t = cputime.utime + cputime.stime;
73 spin_unlock_irq(&tsk->sighand->siglock);
75 value->it_value = ns_to_timeval(val);
76 value->it_interval = ns_to_timeval(interval);
79 int do_getitimer(int which, struct itimerval *value)
81 struct task_struct *tsk = current;
85 spin_lock_irq(&tsk->sighand->siglock);
86 value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
88 ktime_to_timeval(tsk->signal->it_real_incr);
89 spin_unlock_irq(&tsk->sighand->siglock);
92 get_cpu_itimer(tsk, CPUCLOCK_VIRT, value);
95 get_cpu_itimer(tsk, CPUCLOCK_PROF, value);
103 SYSCALL_DEFINE2(getitimer, int, which, struct itimerval __user *, value)
106 struct itimerval get_buffer;
109 error = do_getitimer(which, &get_buffer);
111 copy_to_user(value, &get_buffer, sizeof(get_buffer)))
119 * The timer is automagically restarted, when interval != 0
121 enum hrtimer_restart it_real_fn(struct hrtimer *timer)
123 struct signal_struct *sig =
124 container_of(timer, struct signal_struct, real_timer);
126 trace_itimer_expire(ITIMER_REAL, sig->leader_pid, 0);
127 kill_pid_info(SIGALRM, SEND_SIG_PRIV, sig->leader_pid);
129 return HRTIMER_NORESTART;
132 static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
133 const struct itimerval *const value,
134 struct itimerval *const ovalue)
136 u64 oval, nval, ointerval, ninterval;
137 struct cpu_itimer *it = &tsk->signal->it[clock_id];
139 nval = timeval_to_ns(&value->it_value);
140 ninterval = timeval_to_ns(&value->it_interval);
142 spin_lock_irq(&tsk->sighand->siglock);
145 ointerval = it->incr;
149 set_process_cpu_timer(tsk, clock_id, &nval, &oval);
152 it->incr = ninterval;
153 trace_itimer_state(clock_id == CPUCLOCK_VIRT ?
154 ITIMER_VIRTUAL : ITIMER_PROF, value, nval);
156 spin_unlock_irq(&tsk->sighand->siglock);
159 ovalue->it_value = ns_to_timeval(oval);
160 ovalue->it_interval = ns_to_timeval(ointerval);
165 * Returns true if the timeval is in canonical form
167 #define timeval_valid(t) \
168 (((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC))
170 int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
172 struct task_struct *tsk = current;
173 struct hrtimer *timer;
177 * Validate the timevals in value.
179 if (!timeval_valid(&value->it_value) ||
180 !timeval_valid(&value->it_interval))
186 spin_lock_irq(&tsk->sighand->siglock);
187 timer = &tsk->signal->real_timer;
189 ovalue->it_value = itimer_get_remtime(timer);
191 = ktime_to_timeval(tsk->signal->it_real_incr);
193 /* We are sharing ->siglock with it_real_fn() */
194 if (hrtimer_try_to_cancel(timer) < 0) {
195 spin_unlock_irq(&tsk->sighand->siglock);
198 expires = timeval_to_ktime(value->it_value);
200 tsk->signal->it_real_incr =
201 timeval_to_ktime(value->it_interval);
202 hrtimer_start(timer, expires, HRTIMER_MODE_REL);
204 tsk->signal->it_real_incr = 0;
206 trace_itimer_state(ITIMER_REAL, value, 0);
207 spin_unlock_irq(&tsk->sighand->siglock);
210 set_cpu_itimer(tsk, CPUCLOCK_VIRT, value, ovalue);
213 set_cpu_itimer(tsk, CPUCLOCK_PROF, value, ovalue);
221 #ifdef __ARCH_WANT_SYS_ALARM
224 * alarm_setitimer - set alarm in seconds
226 * @seconds: number of seconds until alarm
227 * 0 disables the alarm
229 * Returns the remaining time in seconds of a pending timer or 0 when
230 * the timer is not active.
232 * On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid
233 * negative timeval settings which would cause immediate expiry.
235 static unsigned int alarm_setitimer(unsigned int seconds)
237 struct itimerval it_new, it_old;
239 #if BITS_PER_LONG < 64
240 if (seconds > INT_MAX)
243 it_new.it_value.tv_sec = seconds;
244 it_new.it_value.tv_usec = 0;
245 it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
247 do_setitimer(ITIMER_REAL, &it_new, &it_old);
250 * We can't return 0 if we have an alarm pending ... And we'd
251 * better return too much than too little anyway
253 if ((!it_old.it_value.tv_sec && it_old.it_value.tv_usec) ||
254 it_old.it_value.tv_usec >= 500000)
255 it_old.it_value.tv_sec++;
257 return it_old.it_value.tv_sec;
261 * For backwards compatibility? This can be done in libc so Alpha
262 * and all newer ports shouldn't need it.
264 SYSCALL_DEFINE1(alarm, unsigned int, seconds)
266 return alarm_setitimer(seconds);
271 SYSCALL_DEFINE3(setitimer, int, which, struct itimerval __user *, value,
272 struct itimerval __user *, ovalue)
274 struct itimerval set_buffer, get_buffer;
278 if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
281 memset(&set_buffer, 0, sizeof(set_buffer));
282 printk_once(KERN_WARNING "%s calls setitimer() with new_value NULL pointer."
283 " Misfeature support will be removed\n",
287 error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
288 if (error || !ovalue)
291 if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))