projects/linux·blob v5.0 · refs

338 lines · 8.0 KiB

1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 1992 Darren Senn
4 */
5
6/* These are all the functions necessary to implement itimers */
7
8#include <linux/mm.h>
9#include <linux/interrupt.h>
10#include <linux/syscalls.h>
11#include <linux/time.h>
12#include <linux/sched/signal.h>
13#include <linux/sched/cputime.h>
14#include <linux/posix-timers.h>
15#include <linux/hrtimer.h>
16#include <trace/events/timer.h>
17#include <linux/compat.h>
18
19#include <linux/uaccess.h>
20
21/**
22 * itimer_get_remtime - get remaining time for the timer
23 *
24 * @timer: the timer to read
25 *
26 * Returns the delta between the expiry time and now, which can be
27 * less than zero or 1usec for an pending expired timer
28 */
29static struct timeval itimer_get_remtime(struct hrtimer *timer)
30{
31 ktime_t rem = __hrtimer_get_remaining(timer, true);
32
33 /*
34 * Racy but safe: if the itimer expires after the above
35 * hrtimer_get_remtime() call but before this condition
36 * then we return 0 - which is correct.
37 */
38 if (hrtimer_active(timer)) {
39 if (rem <= 0)
40 rem = NSEC_PER_USEC;
41 } else
42 rem = 0;
43
44 return ktime_to_timeval(rem);
45}
46
47static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
48 struct itimerval *const value)
49{
50 u64 val, interval;
51 struct cpu_itimer *it = &tsk->signal->it[clock_id];
52
53 spin_lock_irq(&tsk->sighand->siglock);
54
55 val = it->expires;
56 interval = it->incr;
57 if (val) {
58 struct task_cputime cputime;
59 u64 t;
60
61 thread_group_cputimer(tsk, &cputime);
62 if (clock_id == CPUCLOCK_PROF)
63 t = cputime.utime + cputime.stime;
64 else
65 /* CPUCLOCK_VIRT */
66 t = cputime.utime;
67
68 if (val < t)
69 /* about to fire */
70 val = TICK_NSEC;
71 else
72 val -= t;
73 }
74
75 spin_unlock_irq(&tsk->sighand->siglock);
76
77 value->it_value = ns_to_timeval(val);
78 value->it_interval = ns_to_timeval(interval);
79}
80
81int do_getitimer(int which, struct itimerval *value)
82{
83 struct task_struct *tsk = current;
84
85 switch (which) {
86 case ITIMER_REAL:
87 spin_lock_irq(&tsk->sighand->siglock);
88 value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
89 value->it_interval =
90 ktime_to_timeval(tsk->signal->it_real_incr);
91 spin_unlock_irq(&tsk->sighand->siglock);
92 break;
93 case ITIMER_VIRTUAL:
94 get_cpu_itimer(tsk, CPUCLOCK_VIRT, value);
95 break;
96 case ITIMER_PROF:
97 get_cpu_itimer(tsk, CPUCLOCK_PROF, value);
98 break;
99 default:
100 return(-EINVAL);
101 }
102 return 0;
103}
104
105SYSCALL_DEFINE2(getitimer, int, which, struct itimerval __user *, value)
106{
107 int error = -EFAULT;
108 struct itimerval get_buffer;
109
110 if (value) {
111 error = do_getitimer(which, &get_buffer);
112 if (!error &&
113 copy_to_user(value, &get_buffer, sizeof(get_buffer)))
114 error = -EFAULT;
115 }
116 return error;
117}
118
119#ifdef CONFIG_COMPAT
120COMPAT_SYSCALL_DEFINE2(getitimer, int, which,
121 struct compat_itimerval __user *, it)
122{
123 struct itimerval kit;
124 int error = do_getitimer(which, &kit);
125
126 if (!error && put_compat_itimerval(it, &kit))
127 error = -EFAULT;
128 return error;
129}
130#endif
131
132
133/*
134 * The timer is automagically restarted, when interval != 0
135 */
136enum hrtimer_restart it_real_fn(struct hrtimer *timer)
137{
138 struct signal_struct *sig =
139 container_of(timer, struct signal_struct, real_timer);
140 struct pid *leader_pid = sig->pids[PIDTYPE_TGID];
141
142 trace_itimer_expire(ITIMER_REAL, leader_pid, 0);
143 kill_pid_info(SIGALRM, SEND_SIG_PRIV, leader_pid);
144
145 return HRTIMER_NORESTART;
146}
147
148static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
149 const struct itimerval *const value,
150 struct itimerval *const ovalue)
151{
152 u64 oval, nval, ointerval, ninterval;
153 struct cpu_itimer *it = &tsk->signal->it[clock_id];
154
155 /*
156 * Use the to_ktime conversion because that clamps the maximum
157 * value to KTIME_MAX and avoid multiplication overflows.
158 */
159 nval = ktime_to_ns(timeval_to_ktime(value->it_value));
160 ninterval = ktime_to_ns(timeval_to_ktime(value->it_interval));
161
162 spin_lock_irq(&tsk->sighand->siglock);
163
164 oval = it->expires;
165 ointerval = it->incr;
166 if (oval || nval) {
167 if (nval > 0)
168 nval += TICK_NSEC;
169 set_process_cpu_timer(tsk, clock_id, &nval, &oval);
170 }
171 it->expires = nval;
172 it->incr = ninterval;
173 trace_itimer_state(clock_id == CPUCLOCK_VIRT ?
174 ITIMER_VIRTUAL : ITIMER_PROF, value, nval);
175
176 spin_unlock_irq(&tsk->sighand->siglock);
177
178 if (ovalue) {
179 ovalue->it_value = ns_to_timeval(oval);
180 ovalue->it_interval = ns_to_timeval(ointerval);
181 }
182}
183
184/*
185 * Returns true if the timeval is in canonical form
186 */
187#define timeval_valid(t) \
188 (((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC))
189
190int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
191{
192 struct task_struct *tsk = current;
193 struct hrtimer *timer;
194 ktime_t expires;
195
196 /*
197 * Validate the timevals in value.
198 */
199 if (!timeval_valid(&value->it_value) ||
200 !timeval_valid(&value->it_interval))
201 return -EINVAL;
202
203 switch (which) {
204 case ITIMER_REAL:
205again:
206 spin_lock_irq(&tsk->sighand->siglock);
207 timer = &tsk->signal->real_timer;
208 if (ovalue) {
209 ovalue->it_value = itimer_get_remtime(timer);
210 ovalue->it_interval
211 = ktime_to_timeval(tsk->signal->it_real_incr);
212 }
213 /* We are sharing ->siglock with it_real_fn() */
214 if (hrtimer_try_to_cancel(timer) < 0) {
215 spin_unlock_irq(&tsk->sighand->siglock);
216 goto again;
217 }
218 expires = timeval_to_ktime(value->it_value);
219 if (expires != 0) {
220 tsk->signal->it_real_incr =
221 timeval_to_ktime(value->it_interval);
222 hrtimer_start(timer, expires, HRTIMER_MODE_REL);
223 } else
224 tsk->signal->it_real_incr = 0;
225
226 trace_itimer_state(ITIMER_REAL, value, 0);
227 spin_unlock_irq(&tsk->sighand->siglock);
228 break;
229 case ITIMER_VIRTUAL:
230 set_cpu_itimer(tsk, CPUCLOCK_VIRT, value, ovalue);
231 break;
232 case ITIMER_PROF:
233 set_cpu_itimer(tsk, CPUCLOCK_PROF, value, ovalue);
234 break;
235 default:
236 return -EINVAL;
237 }
238 return 0;
239}
240
241#ifdef __ARCH_WANT_SYS_ALARM
242
243/**
244 * alarm_setitimer - set alarm in seconds
245 *
246 * @seconds: number of seconds until alarm
247 * 0 disables the alarm
248 *
249 * Returns the remaining time in seconds of a pending timer or 0 when
250 * the timer is not active.
251 *
252 * On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid
253 * negative timeval settings which would cause immediate expiry.
254 */
255static unsigned int alarm_setitimer(unsigned int seconds)
256{
257 struct itimerval it_new, it_old;
258
259#if BITS_PER_LONG < 64
260 if (seconds > INT_MAX)
261 seconds = INT_MAX;
262#endif
263 it_new.it_value.tv_sec = seconds;
264 it_new.it_value.tv_usec = 0;
265 it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
266
267 do_setitimer(ITIMER_REAL, &it_new, &it_old);
268
269 /*
270 * We can't return 0 if we have an alarm pending ... And we'd
271 * better return too much than too little anyway
272 */
273 if ((!it_old.it_value.tv_sec && it_old.it_value.tv_usec) ||
274 it_old.it_value.tv_usec >= 500000)
275 it_old.it_value.tv_sec++;
276
277 return it_old.it_value.tv_sec;
278}
279
280/*
281 * For backwards compatibility? This can be done in libc so Alpha
282 * and all newer ports shouldn't need it.
283 */
284SYSCALL_DEFINE1(alarm, unsigned int, seconds)
285{
286 return alarm_setitimer(seconds);
287}
288
289#endif
290
291SYSCALL_DEFINE3(setitimer, int, which, struct itimerval __user *, value,
292 struct itimerval __user *, ovalue)
293{
294 struct itimerval set_buffer, get_buffer;
295 int error;
296
297 if (value) {
298 if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
299 return -EFAULT;
300 } else {
301 memset(&set_buffer, 0, sizeof(set_buffer));
302 printk_once(KERN_WARNING "%s calls setitimer() with new_value NULL pointer."
303 " Misfeature support will be removed\n",
304 current->comm);
305 }
306
307 error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
308 if (error || !ovalue)
309 return error;
310
311 if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))
312 return -EFAULT;
313 return 0;
314}
315
316#ifdef CONFIG_COMPAT
317COMPAT_SYSCALL_DEFINE3(setitimer, int, which,
318 struct compat_itimerval __user *, in,
319 struct compat_itimerval __user *, out)
320{
321 struct itimerval kin, kout;
322 int error;
323
324 if (in) {
325 if (get_compat_itimerval(&kin, in))
326 return -EFAULT;
327 } else {
328 memset(&kin, 0, sizeof(kin));
329 }
330
331 error = do_setitimer(which, &kin, out ? &kout : NULL);
332 if (error || !out)
333 return error;
334 if (put_compat_itimerval(out, &kout))
335 return -EFAULT;
336 return 0;
337}
338#endif