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 <asm/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)) {
38 rem.tv64 = NSEC_PER_USEC;
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)
48 cputime_t cval, cinterval;
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;
68 cval = cputime_one_jiffy;
73 spin_unlock_irq(&tsk->sighand->siglock);
75 cputime_to_timeval(cval, &value->it_value);
76 cputime_to_timeval(cinterval, &value->it_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 inline u32 cputime_sub_ns(cputime_t ct, s64 real_ns)
137 cputime_to_timespec(ct, &ts);
138 cpu_ns = timespec_to_ns(&ts);
140 return (cpu_ns <= real_ns) ? 0 : cpu_ns - real_ns;
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 cputime_t cval, nval, cinterval, ninterval;
148 s64 ns_ninterval, ns_nval;
149 u32 error, incr_error;
150 struct cpu_itimer *it = &tsk->signal->it[clock_id];
152 nval = timeval_to_cputime(&value->it_value);
153 ns_nval = timeval_to_ns(&value->it_value);
154 ninterval = timeval_to_cputime(&value->it_interval);
155 ns_ninterval = timeval_to_ns(&value->it_interval);
157 error = cputime_sub_ns(nval, ns_nval);
158 incr_error = cputime_sub_ns(ninterval, ns_ninterval);
160 spin_lock_irq(&tsk->sighand->siglock);
163 cinterval = it->incr;
166 nval += cputime_one_jiffy;
167 set_process_cpu_timer(tsk, clock_id, &nval, &cval);
170 it->incr = ninterval;
172 it->incr_error = incr_error;
173 trace_itimer_state(clock_id == CPUCLOCK_VIRT ?
174 ITIMER_VIRTUAL : ITIMER_PROF, value, nval);
176 spin_unlock_irq(&tsk->sighand->siglock);
179 cputime_to_timeval(cval, &ovalue->it_value);
180 cputime_to_timeval(cinterval, &ovalue->it_interval);
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);
219 if (expires.tv64 != 0) {
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.tv64 = 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);
242 * alarm_setitimer - set alarm in seconds
244 * @seconds: number of seconds until alarm
245 * 0 disables the alarm
247 * Returns the remaining time in seconds of a pending timer or 0 when
248 * the timer is not active.
250 * On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid
251 * negative timeval settings which would cause immediate expiry.
253 unsigned int alarm_setitimer(unsigned int seconds)
255 struct itimerval it_new, it_old;
257 #if BITS_PER_LONG < 64
258 if (seconds > INT_MAX)
261 it_new.it_value.tv_sec = seconds;
262 it_new.it_value.tv_usec = 0;
263 it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
265 do_setitimer(ITIMER_REAL, &it_new, &it_old);
268 * We can't return 0 if we have an alarm pending ... And we'd
269 * better return too much than too little anyway
271 if ((!it_old.it_value.tv_sec && it_old.it_value.tv_usec) ||
272 it_old.it_value.tv_usec >= 500000)
273 it_old.it_value.tv_sec++;
275 return it_old.it_value.tv_sec;
278 SYSCALL_DEFINE3(setitimer, int, which, struct itimerval __user *, value,
279 struct itimerval __user *, ovalue)
281 struct itimerval set_buffer, get_buffer;
285 if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
288 memset(&set_buffer, 0, sizeof(set_buffer));
289 printk_once(KERN_WARNING "%s calls setitimer() with new_value NULL pointer."
290 " Misfeature support will be removed\n",
294 error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
295 if (error || !ovalue)
298 if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))