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/smp_lock.h>
11 #include <linux/interrupt.h>
12 #include <linux/syscalls.h>
13 #include <linux/time.h>
14 #include <linux/posix-timers.h>
15 #include <linux/hrtimer.h>
16
17 #include <asm/uaccess.h>
18
19 /**
20 * itimer_get_remtime - get remaining time for the timer
21 *
22 * @timer: the timer to read
23 *
24 * Returns the delta between the expiry time and now, which can be
25 * less than zero or 1usec for an pending expired timer
26 */
27 static struct timeval itimer_get_remtime(struct hrtimer *timer)
28 {
29 ktime_t rem = hrtimer_get_remaining(timer);
30
31 /*
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.
35 */
36 if (hrtimer_active(timer)) {
37 if (rem.tv64 <= 0)
38 rem.tv64 = NSEC_PER_USEC;
39 } else
40 rem.tv64 = 0;
41
42 return ktime_to_timeval(rem);
43 }
44
45 int do_getitimer(int which, struct itimerval *value)
46 {
47 struct task_struct *tsk = current;
48 cputime_t cinterval, cval;
49
50 switch (which) {
51 case ITIMER_REAL:
52 spin_lock_irq(&tsk->sighand->siglock);
53 value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
54 value->it_interval =
55 ktime_to_timeval(tsk->signal->it_real_incr);
56 spin_unlock_irq(&tsk->sighand->siglock);
57 break;
58 case ITIMER_VIRTUAL:
59 read_lock(&tasklist_lock);
60 spin_lock_irq(&tsk->sighand->siglock);
61 cval = tsk->signal->it_virt_expires;
62 cinterval = tsk->signal->it_virt_incr;
63 if (!cputime_eq(cval, cputime_zero)) {
64 struct task_struct *t = tsk;
65 cputime_t utime = tsk->signal->utime;
66 do {
67 utime = cputime_add(utime, t->utime);
68 t = next_thread(t);
69 } while (t != tsk);
70 if (cputime_le(cval, utime)) { /* about to fire */
71 cval = jiffies_to_cputime(1);
72 } else {
73 cval = cputime_sub(cval, utime);
74 }
75 }
76 spin_unlock_irq(&tsk->sighand->siglock);
77 read_unlock(&tasklist_lock);
78 cputime_to_timeval(cval, &value->it_value);
79 cputime_to_timeval(cinterval, &value->it_interval);
80 break;
81 case ITIMER_PROF:
82 read_lock(&tasklist_lock);
83 spin_lock_irq(&tsk->sighand->siglock);
84 cval = tsk->signal->it_prof_expires;
85 cinterval = tsk->signal->it_prof_incr;
86 if (!cputime_eq(cval, cputime_zero)) {
87 struct task_struct *t = tsk;
88 cputime_t ptime = cputime_add(tsk->signal->utime,
89 tsk->signal->stime);
90 do {
91 ptime = cputime_add(ptime,
92 cputime_add(t->utime,
93 t->stime));
94 t = next_thread(t);
95 } while (t != tsk);
96 if (cputime_le(cval, ptime)) { /* about to fire */
97 cval = jiffies_to_cputime(1);
98 } else {
99 cval = cputime_sub(cval, ptime);
100 }
101 }
102 spin_unlock_irq(&tsk->sighand->siglock);
103 read_unlock(&tasklist_lock);
104 cputime_to_timeval(cval, &value->it_value);
105 cputime_to_timeval(cinterval, &value->it_interval);
106 break;
107 default:
108 return(-EINVAL);
109 }
110 return 0;
111 }
112
113 asmlinkage long sys_getitimer(int which, struct itimerval __user *value)
114 {
115 int error = -EFAULT;
116 struct itimerval get_buffer;
117
118 if (value) {
119 error = do_getitimer(which, &get_buffer);
120 if (!error &&
121 copy_to_user(value, &get_buffer, sizeof(get_buffer)))
122 error = -EFAULT;
123 }
124 return error;
125 }
126
127
128 /*
129 * The timer is automagically restarted, when interval != 0
130 */
131 int it_real_fn(struct hrtimer *timer)
132 {
133 struct signal_struct *sig =
134 container_of(timer, struct signal_struct, real_timer);
135
136 send_group_sig_info(SIGALRM, SEND_SIG_PRIV, sig->tsk);
137
138 if (sig->it_real_incr.tv64 != 0) {
139 hrtimer_forward(timer, timer->base->softirq_time,
140 sig->it_real_incr);
141 return HRTIMER_RESTART;
142 }
143 return HRTIMER_NORESTART;
144 }
145
146 /*
147 * We do not care about correctness. We just sanitize the values so
148 * the ktime_t operations which expect normalized values do not
149 * break. This converts negative values to long timeouts similar to
150 * the code in kernel versions < 2.6.16
151 *
152 * Print a limited number of warning messages when an invalid timeval
153 * is detected.
154 */
155 static void fixup_timeval(struct timeval *tv, int interval)
156 {
157 static int warnlimit = 10;
158 unsigned long tmp;
159
160 if (warnlimit > 0) {
161 warnlimit--;
162 printk(KERN_WARNING
163 "setitimer: %s (pid = %d) provided "
164 "invalid timeval %s: tv_sec = %ld tv_usec = %ld\n",
165 current->comm, current->pid,
166 interval ? "it_interval" : "it_value",
167 tv->tv_sec, (long) tv->tv_usec);
168 }
169
170 tmp = tv->tv_usec;
171 if (tmp >= USEC_PER_SEC) {
172 tv->tv_usec = tmp % USEC_PER_SEC;
173 tv->tv_sec += tmp / USEC_PER_SEC;
174 }
175
176 tmp = tv->tv_sec;
177 if (tmp > LONG_MAX)
178 tv->tv_sec = LONG_MAX;
179 }
180
181 /*
182 * Returns true if the timeval is in canonical form
183 */
184 #define timeval_valid(t) \
185 (((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC))
186
187 /*
188 * Check for invalid timevals, sanitize them and print a limited
189 * number of warnings.
190 */
191 static void check_itimerval(struct itimerval *value) {
192
193 if (unlikely(!timeval_valid(&value->it_value)))
194 fixup_timeval(&value->it_value, 0);
195
196 if (unlikely(!timeval_valid(&value->it_interval)))
197 fixup_timeval(&value->it_interval, 1);
198 }
199
200 int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
201 {
202 struct task_struct *tsk = current;
203 struct hrtimer *timer;
204 ktime_t expires;
205 cputime_t cval, cinterval, nval, ninterval;
206
207 /*
208 * Validate the timevals in value.
209 *
210 * Note: Although the spec requires that invalid values shall
211 * return -EINVAL, we just fixup the value and print a limited
212 * number of warnings in order not to break users of this
213 * historical misfeature.
214 *
215 * Scheduled for replacement in March 2007
216 */
217 check_itimerval(value);
218
219 switch (which) {
220 case ITIMER_REAL:
221 again:
222 spin_lock_irq(&tsk->sighand->siglock);
223 timer = &tsk->signal->real_timer;
224 if (ovalue) {
225 ovalue->it_value = itimer_get_remtime(timer);
226 ovalue->it_interval
227 = ktime_to_timeval(tsk->signal->it_real_incr);
228 }
229 /* We are sharing ->siglock with it_real_fn() */
230 if (hrtimer_try_to_cancel(timer) < 0) {
231 spin_unlock_irq(&tsk->sighand->siglock);
232 goto again;
233 }
234 tsk->signal->it_real_incr =
235 timeval_to_ktime(value->it_interval);
236 expires = timeval_to_ktime(value->it_value);
237 if (expires.tv64 != 0)
238 hrtimer_start(timer, expires, HRTIMER_REL);
239 spin_unlock_irq(&tsk->sighand->siglock);
240 break;
241 case ITIMER_VIRTUAL:
242 nval = timeval_to_cputime(&value->it_value);
243 ninterval = timeval_to_cputime(&value->it_interval);
244 read_lock(&tasklist_lock);
245 spin_lock_irq(&tsk->sighand->siglock);
246 cval = tsk->signal->it_virt_expires;
247 cinterval = tsk->signal->it_virt_incr;
248 if (!cputime_eq(cval, cputime_zero) ||
249 !cputime_eq(nval, cputime_zero)) {
250 if (cputime_gt(nval, cputime_zero))
251 nval = cputime_add(nval,
252 jiffies_to_cputime(1));
253 set_process_cpu_timer(tsk, CPUCLOCK_VIRT,
254 &nval, &cval);
255 }
256 tsk->signal->it_virt_expires = nval;
257 tsk->signal->it_virt_incr = ninterval;
258 spin_unlock_irq(&tsk->sighand->siglock);
259 read_unlock(&tasklist_lock);
260 if (ovalue) {
261 cputime_to_timeval(cval, &ovalue->it_value);
262 cputime_to_timeval(cinterval, &ovalue->it_interval);
263 }
264 break;
265 case ITIMER_PROF:
266 nval = timeval_to_cputime(&value->it_value);
267 ninterval = timeval_to_cputime(&value->it_interval);
268 read_lock(&tasklist_lock);
269 spin_lock_irq(&tsk->sighand->siglock);
270 cval = tsk->signal->it_prof_expires;
271 cinterval = tsk->signal->it_prof_incr;
272 if (!cputime_eq(cval, cputime_zero) ||
273 !cputime_eq(nval, cputime_zero)) {
274 if (cputime_gt(nval, cputime_zero))
275 nval = cputime_add(nval,
276 jiffies_to_cputime(1));
277 set_process_cpu_timer(tsk, CPUCLOCK_PROF,
278 &nval, &cval);
279 }
280 tsk->signal->it_prof_expires = nval;
281 tsk->signal->it_prof_incr = ninterval;
282 spin_unlock_irq(&tsk->sighand->siglock);
283 read_unlock(&tasklist_lock);
284 if (ovalue) {
285 cputime_to_timeval(cval, &ovalue->it_value);
286 cputime_to_timeval(cinterval, &ovalue->it_interval);
287 }
288 break;
289 default:
290 return -EINVAL;
291 }
292 return 0;
293 }
294
295 /**
296 * alarm_setitimer - set alarm in seconds
297 *
298 * @seconds: number of seconds until alarm
299 * 0 disables the alarm
300 *
301 * Returns the remaining time in seconds of a pending timer or 0 when
302 * the timer is not active.
303 *
304 * On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid
305 * negative timeval settings which would cause immediate expiry.
306 */
307 unsigned int alarm_setitimer(unsigned int seconds)
308 {
309 struct itimerval it_new, it_old;
310
311 #if BITS_PER_LONG < 64
312 if (seconds > INT_MAX)
313 seconds = INT_MAX;
314 #endif
315 it_new.it_value.tv_sec = seconds;
316 it_new.it_value.tv_usec = 0;
317 it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
318
319 do_setitimer(ITIMER_REAL, &it_new, &it_old);
320
321 /*
322 * We can't return 0 if we have an alarm pending ... And we'd
323 * better return too much than too little anyway
324 */
325 if ((!it_old.it_value.tv_sec && it_old.it_value.tv_usec) ||
326 it_old.it_value.tv_usec >= 500000)
327 it_old.it_value.tv_sec++;
328
329 return it_old.it_value.tv_sec;
330 }
331
332 asmlinkage long sys_setitimer(int which,
333 struct itimerval __user *value,
334 struct itimerval __user *ovalue)
335 {
336 struct itimerval set_buffer, get_buffer;
337 int error;
338
339 if (value) {
340 if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
341 return -EFAULT;
342 } else
343 memset((char *) &set_buffer, 0, sizeof(set_buffer));
344
345 error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
346 if (error || !ovalue)
347 return error;
348
349 if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))
350 return -EFAULT;
351 return 0;
352 }
353
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