1 /*
2 * linux/kernel/itimer.c
3 *
4 * Copyright (C) 1992 Darren Senn
5 */
6
7 /* These are all the functions necessary to implement itimers */
8
9 #include <linux/mm.h>
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
16 #include <asm/uaccess.h>
17
18 /**
19 * itimer_get_remtime - get remaining time for the timer
20 *
21 * @timer: the timer to read
22 *
23 * Returns the delta between the expiry time and now, which can be
24 * less than zero or 1usec for an pending expired timer
25 */
26 static struct timeval itimer_get_remtime(struct hrtimer *timer)
27 {
28 ktime_t rem = hrtimer_get_remaining(timer);
29
30 /*
31 * Racy but safe: if the itimer expires after the above
32 * hrtimer_get_remtime() call but before this condition
33 * then we return 0 - which is correct.
34 */
35 if (hrtimer_active(timer)) {
36 if (rem.tv64 <= 0)
37 rem.tv64 = NSEC_PER_USEC;
38 } else
39 rem.tv64 = 0;
40
41 return ktime_to_timeval(rem);
42 }
43
44 int do_getitimer(int which, struct itimerval *value)
45 {
46 struct task_struct *tsk = current;
47 cputime_t cinterval, cval;
48
49 switch (which) {
50 case ITIMER_REAL:
51 spin_lock_irq(&tsk->sighand->siglock);
52 value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
53 value->it_interval =
54 ktime_to_timeval(tsk->signal->it_real_incr);
55 spin_unlock_irq(&tsk->sighand->siglock);
56 break;
57 case ITIMER_VIRTUAL:
58 read_lock(&tasklist_lock);
59 spin_lock_irq(&tsk->sighand->siglock);
60 cval = tsk->signal->it_virt_expires;
61 cinterval = tsk->signal->it_virt_incr;
62 if (!cputime_eq(cval, cputime_zero)) {
63 struct task_struct *t = tsk;
64 cputime_t utime = tsk->signal->utime;
65 do {
66 utime = cputime_add(utime, t->utime);
67 t = next_thread(t);
68 } while (t != tsk);
69 if (cputime_le(cval, utime)) { /* about to fire */
70 cval = jiffies_to_cputime(1);
71 } else {
72 cval = cputime_sub(cval, utime);
73 }
74 }
75 spin_unlock_irq(&tsk->sighand->siglock);
76 read_unlock(&tasklist_lock);
77 cputime_to_timeval(cval, &value->it_value);
78 cputime_to_timeval(cinterval, &value->it_interval);
79 break;
80 case ITIMER_PROF:
81 read_lock(&tasklist_lock);
82 spin_lock_irq(&tsk->sighand->siglock);
83 cval = tsk->signal->it_prof_expires;
84 cinterval = tsk->signal->it_prof_incr;
85 if (!cputime_eq(cval, cputime_zero)) {
86 struct task_struct *t = tsk;
87 cputime_t ptime = cputime_add(tsk->signal->utime,
88 tsk->signal->stime);
89 do {
90 ptime = cputime_add(ptime,
91 cputime_add(t->utime,
92 t->stime));
93 t = next_thread(t);
94 } while (t != tsk);
95 if (cputime_le(cval, ptime)) { /* about to fire */
96 cval = jiffies_to_cputime(1);
97 } else {
98 cval = cputime_sub(cval, ptime);
99 }
100 }
101 spin_unlock_irq(&tsk->sighand->siglock);
102 read_unlock(&tasklist_lock);
103 cputime_to_timeval(cval, &value->it_value);
104 cputime_to_timeval(cinterval, &value->it_interval);
105 break;
106 default:
107 return(-EINVAL);
108 }
109 return 0;
110 }
111
112 asmlinkage long sys_getitimer(int which, struct itimerval __user *value)
113 {
114 int error = -EFAULT;
115 struct itimerval get_buffer;
116
117 if (value) {
118 error = do_getitimer(which, &get_buffer);
119 if (!error &&
120 copy_to_user(value, &get_buffer, sizeof(get_buffer)))
121 error = -EFAULT;
122 }
123 return error;
124 }
125
126
127 /*
128 * The timer is automagically restarted, when interval != 0
129 */
130 enum hrtimer_restart it_real_fn(struct hrtimer *timer)
131 {
132 struct signal_struct *sig =
133 container_of(timer, struct signal_struct, real_timer);
134
135 kill_pid_info(SIGALRM, SEND_SIG_PRIV, sig->leader_pid);
136
137 return HRTIMER_NORESTART;
138 }
139
140 /*
141 * Returns true if the timeval is in canonical form
142 */
143 #define timeval_valid(t) \
144 (((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC))
145
146 int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
147 {
148 struct task_struct *tsk = current;
149 struct hrtimer *timer;
150 ktime_t expires;
151 cputime_t cval, cinterval, nval, ninterval;
152
153 /*
154 * Validate the timevals in value.
155 */
156 if (!timeval_valid(&value->it_value) ||
157 !timeval_valid(&value->it_interval))
158 return -EINVAL;
159
160 switch (which) {
161 case ITIMER_REAL:
162 again:
163 spin_lock_irq(&tsk->sighand->siglock);
164 timer = &tsk->signal->real_timer;
165 if (ovalue) {
166 ovalue->it_value = itimer_get_remtime(timer);
167 ovalue->it_interval
168 = ktime_to_timeval(tsk->signal->it_real_incr);
169 }
170 /* We are sharing ->siglock with it_real_fn() */
171 if (hrtimer_try_to_cancel(timer) < 0) {
172 spin_unlock_irq(&tsk->sighand->siglock);
173 hrtimer_wait_for_timer(&tsk->signal->real_timer);
174 goto again;
175 }
176 expires = timeval_to_ktime(value->it_value);
177 if (expires.tv64 != 0) {
178 tsk->signal->it_real_incr =
179 timeval_to_ktime(value->it_interval);
180 hrtimer_start(timer, expires, HRTIMER_MODE_REL);
181 } else
182 tsk->signal->it_real_incr.tv64 = 0;
183
184 spin_unlock_irq(&tsk->sighand->siglock);
185 break;
186 case ITIMER_VIRTUAL:
187 nval = timeval_to_cputime(&value->it_value);
188 ninterval = timeval_to_cputime(&value->it_interval);
189 read_lock(&tasklist_lock);
190 spin_lock_irq(&tsk->sighand->siglock);
191 cval = tsk->signal->it_virt_expires;
192 cinterval = tsk->signal->it_virt_incr;
193 if (!cputime_eq(cval, cputime_zero) ||
194 !cputime_eq(nval, cputime_zero)) {
195 if (cputime_gt(nval, cputime_zero))
196 nval = cputime_add(nval,
197 jiffies_to_cputime(1));
198 set_process_cpu_timer(tsk, CPUCLOCK_VIRT,
199 &nval, &cval);
200 }
201 tsk->signal->it_virt_expires = nval;
202 tsk->signal->it_virt_incr = ninterval;
203 spin_unlock_irq(&tsk->sighand->siglock);
204 read_unlock(&tasklist_lock);
205 if (ovalue) {
206 cputime_to_timeval(cval, &ovalue->it_value);
207 cputime_to_timeval(cinterval, &ovalue->it_interval);
208 }
209 break;
210 case ITIMER_PROF:
211 nval = timeval_to_cputime(&value->it_value);
212 ninterval = timeval_to_cputime(&value->it_interval);
213 read_lock(&tasklist_lock);
214 spin_lock_irq(&tsk->sighand->siglock);
215 cval = tsk->signal->it_prof_expires;
216 cinterval = tsk->signal->it_prof_incr;
217 if (!cputime_eq(cval, cputime_zero) ||
218 !cputime_eq(nval, cputime_zero)) {
219 if (cputime_gt(nval, cputime_zero))
220 nval = cputime_add(nval,
221 jiffies_to_cputime(1));
222 set_process_cpu_timer(tsk, CPUCLOCK_PROF,
223 &nval, &cval);
224 }
225 tsk->signal->it_prof_expires = nval;
226 tsk->signal->it_prof_incr = ninterval;
227 spin_unlock_irq(&tsk->sighand->siglock);
228 read_unlock(&tasklist_lock);
229 if (ovalue) {
230 cputime_to_timeval(cval, &ovalue->it_value);
231 cputime_to_timeval(cinterval, &ovalue->it_interval);
232 }
233 break;
234 default:
235 return -EINVAL;
236 }
237 return 0;
238 }
239
240 /**
241 * alarm_setitimer - set alarm in seconds
242 *
243 * @seconds: number of seconds until alarm
244 * 0 disables the alarm
245 *
246 * Returns the remaining time in seconds of a pending timer or 0 when
247 * the timer is not active.
248 *
249 * On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid
250 * negative timeval settings which would cause immediate expiry.
251 */
252 unsigned int alarm_setitimer(unsigned int seconds)
253 {
254 struct itimerval it_new, it_old;
255
256 #if BITS_PER_LONG < 64
257 if (seconds > INT_MAX)
258 seconds = INT_MAX;
259 #endif
260 it_new.it_value.tv_sec = seconds;
261 it_new.it_value.tv_usec = 0;
262 it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
263
264 do_setitimer(ITIMER_REAL, &it_new, &it_old);
265
266 /*
267 * We can't return 0 if we have an alarm pending ... And we'd
268 * better return too much than too little anyway
269 */
270 if ((!it_old.it_value.tv_sec && it_old.it_value.tv_usec) ||
271 it_old.it_value.tv_usec >= 500000)
272 it_old.it_value.tv_sec++;
273
274 return it_old.it_value.tv_sec;
275 }
276
277 asmlinkage long sys_setitimer(int which,
278 struct itimerval __user *value,
279 struct itimerval __user *ovalue)
280 {
281 struct itimerval set_buffer, get_buffer;
282 int error;
283
284 if (value) {
285 if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
286 return -EFAULT;
287 } else
288 memset((char *) &set_buffer, 0, sizeof(set_buffer));
289
290 error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
291 if (error || !ovalue)
292 return error;
293
294 if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))
295 return -EFAULT;
296 return 0;
297 }
298
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