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
);
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
);
55 if (!cputime_eq(cval
, cputime_zero
)) {
56 struct task_cputime cputime
;
59 thread_group_cputimer(tsk
, &cputime
);
60 if (clock_id
== CPUCLOCK_PROF
)
61 t
= cputime_add(cputime
.utime
, cputime
.stime
);
66 if (cputime_le(cval
, t
))
68 cval
= cputime_one_jiffy
;
70 cval
= cputime_sub(cval
, t
);
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
;
164 if (!cputime_eq(cval
, cputime_zero
) ||
165 !cputime_eq(nval
, cputime_zero
)) {
166 if (cputime_gt(nval
, cputime_zero
))
167 nval
= cputime_add(nval
, cputime_one_jiffy
);
168 set_process_cpu_timer(tsk
, clock_id
, &nval
, &cval
);
171 it
->incr
= ninterval
;
173 it
->incr_error
= incr_error
;
174 trace_itimer_state(clock_id
== CPUCLOCK_VIRT
?
175 ITIMER_VIRTUAL
: ITIMER_PROF
, value
, nval
);
177 spin_unlock_irq(&tsk
->sighand
->siglock
);
180 cputime_to_timeval(cval
, &ovalue
->it_value
);
181 cputime_to_timeval(cinterval
, &ovalue
->it_interval
);
186 * Returns true if the timeval is in canonical form
188 #define timeval_valid(t) \
189 (((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC))
191 int do_setitimer(int which
, struct itimerval
*value
, struct itimerval
*ovalue
)
193 struct task_struct
*tsk
= current
;
194 struct hrtimer
*timer
;
198 * Validate the timevals in value.
200 if (!timeval_valid(&value
->it_value
) ||
201 !timeval_valid(&value
->it_interval
))
207 spin_lock_irq(&tsk
->sighand
->siglock
);
208 timer
= &tsk
->signal
->real_timer
;
210 ovalue
->it_value
= itimer_get_remtime(timer
);
212 = ktime_to_timeval(tsk
->signal
->it_real_incr
);
214 /* We are sharing ->siglock with it_real_fn() */
215 if (hrtimer_try_to_cancel(timer
) < 0) {
216 spin_unlock_irq(&tsk
->sighand
->siglock
);
219 expires
= timeval_to_ktime(value
->it_value
);
220 if (expires
.tv64
!= 0) {
221 tsk
->signal
->it_real_incr
=
222 timeval_to_ktime(value
->it_interval
);
223 hrtimer_start(timer
, expires
, HRTIMER_MODE_REL
);
225 tsk
->signal
->it_real_incr
.tv64
= 0;
227 trace_itimer_state(ITIMER_REAL
, value
, 0);
228 spin_unlock_irq(&tsk
->sighand
->siglock
);
231 set_cpu_itimer(tsk
, CPUCLOCK_VIRT
, value
, ovalue
);
234 set_cpu_itimer(tsk
, CPUCLOCK_PROF
, value
, ovalue
);
243 * alarm_setitimer - set alarm in seconds
245 * @seconds: number of seconds until alarm
246 * 0 disables the alarm
248 * Returns the remaining time in seconds of a pending timer or 0 when
249 * the timer is not active.
251 * On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid
252 * negative timeval settings which would cause immediate expiry.
254 unsigned int alarm_setitimer(unsigned int seconds
)
256 struct itimerval it_new
, it_old
;
258 #if BITS_PER_LONG < 64
259 if (seconds
> INT_MAX
)
262 it_new
.it_value
.tv_sec
= seconds
;
263 it_new
.it_value
.tv_usec
= 0;
264 it_new
.it_interval
.tv_sec
= it_new
.it_interval
.tv_usec
= 0;
266 do_setitimer(ITIMER_REAL
, &it_new
, &it_old
);
269 * We can't return 0 if we have an alarm pending ... And we'd
270 * better return too much than too little anyway
272 if ((!it_old
.it_value
.tv_sec
&& it_old
.it_value
.tv_usec
) ||
273 it_old
.it_value
.tv_usec
>= 500000)
274 it_old
.it_value
.tv_sec
++;
276 return it_old
.it_value
.tv_sec
;
279 SYSCALL_DEFINE3(setitimer
, int, which
, struct itimerval __user
*, value
,
280 struct itimerval __user
*, ovalue
)
282 struct itimerval set_buffer
, get_buffer
;
286 if(copy_from_user(&set_buffer
, value
, sizeof(set_buffer
)))
289 memset((char *) &set_buffer
, 0, sizeof(set_buffer
));
291 error
= do_setitimer(which
, &set_buffer
, ovalue
? &get_buffer
: NULL
);
292 if (error
|| !ovalue
)
295 if (copy_to_user(ovalue
, &get_buffer
, sizeof(get_buffer
)))
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