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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#include <trace/events/timer.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 */
27static struct timeval itimer_get_remtime(struct hrtimer *timer)
28{
29 ktime_t rem = __hrtimer_get_remaining(timer, true);
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
45static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
46 struct itimerval *const value)
47{
48 cputime_t cval, cinterval;
49 struct cpu_itimer *it = &tsk->signal->it[clock_id];
50
51 spin_lock_irq(&tsk->sighand->siglock);
52
53 cval = it->expires;
54 cinterval = it->incr;
55 if (cval) {
56 struct task_cputime cputime;
57 cputime_t t;
58
59 thread_group_cputimer(tsk, &cputime);
60 if (clock_id == CPUCLOCK_PROF)
61 t = cputime.utime + cputime.stime;
62 else
63 /* CPUCLOCK_VIRT */
64 t = cputime.utime;
65
66 if (cval < t)
67 /* about to fire */
68 cval = cputime_one_jiffy;
69 else
70 cval = cval - t;
71 }
72
73 spin_unlock_irq(&tsk->sighand->siglock);
74
75 cputime_to_timeval(cval, &value->it_value);
76 cputime_to_timeval(cinterval, &value->it_interval);
77}
78
79int do_getitimer(int which, struct itimerval *value)
80{
81 struct task_struct *tsk = current;
82
83 switch (which) {
84 case ITIMER_REAL:
85 spin_lock_irq(&tsk->sighand->siglock);
86 value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
87 value->it_interval =
88 ktime_to_timeval(tsk->signal->it_real_incr);
89 spin_unlock_irq(&tsk->sighand->siglock);
90 break;
91 case ITIMER_VIRTUAL:
92 get_cpu_itimer(tsk, CPUCLOCK_VIRT, value);
93 break;
94 case ITIMER_PROF:
95 get_cpu_itimer(tsk, CPUCLOCK_PROF, value);
96 break;
97 default:
98 return(-EINVAL);
99 }
100 return 0;
101}
102
103SYSCALL_DEFINE2(getitimer, int, which, struct itimerval __user *, value)
104{
105 int error = -EFAULT;
106 struct itimerval get_buffer;
107
108 if (value) {
109 error = do_getitimer(which, &get_buffer);
110 if (!error &&
111 copy_to_user(value, &get_buffer, sizeof(get_buffer)))
112 error = -EFAULT;
113 }
114 return error;
115}
116
117
118/*
119 * The timer is automagically restarted, when interval != 0
120 */
121enum hrtimer_restart it_real_fn(struct hrtimer *timer)
122{
123 struct signal_struct *sig =
124 container_of(timer, struct signal_struct, real_timer);
125
126 trace_itimer_expire(ITIMER_REAL, sig->leader_pid, 0);
127 kill_pid_info(SIGALRM, SEND_SIG_PRIV, sig->leader_pid);
128
129 return HRTIMER_NORESTART;
130}
131
132static inline u32 cputime_sub_ns(cputime_t ct, s64 real_ns)
133{
134 struct timespec ts;
135 s64 cpu_ns;
136
137 cputime_to_timespec(ct, &ts);
138 cpu_ns = timespec_to_ns(&ts);
139
140 return (cpu_ns <= real_ns) ? 0 : cpu_ns - real_ns;
141}
142
143static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
144 const struct itimerval *const value,
145 struct itimerval *const ovalue)
146{
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];
151
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);
156
157 error = cputime_sub_ns(nval, ns_nval);
158 incr_error = cputime_sub_ns(ninterval, ns_ninterval);
159
160 spin_lock_irq(&tsk->sighand->siglock);
161
162 cval = it->expires;
163 cinterval = it->incr;
164 if (cval || nval) {
165 if (nval > 0)
166 nval += cputime_one_jiffy;
167 set_process_cpu_timer(tsk, clock_id, &nval, &cval);
168 }
169 it->expires = nval;
170 it->incr = ninterval;
171 it->error = error;
172 it->incr_error = incr_error;
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 cputime_to_timeval(cval, &ovalue->it_value);
180 cputime_to_timeval(cinterval, &ovalue->it_interval);
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.tv64 != 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.tv64 = 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/**
242 * alarm_setitimer - set alarm in seconds
243 *
244 * @seconds: number of seconds until alarm
245 * 0 disables the alarm
246 *
247 * Returns the remaining time in seconds of a pending timer or 0 when
248 * the timer is not active.
249 *
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.
252 */
253unsigned int alarm_setitimer(unsigned int seconds)
254{
255 struct itimerval it_new, it_old;
256
257#if BITS_PER_LONG < 64
258 if (seconds > INT_MAX)
259 seconds = INT_MAX;
260#endif
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;
264
265 do_setitimer(ITIMER_REAL, &it_new, &it_old);
266
267 /*
268 * We can't return 0 if we have an alarm pending ... And we'd
269 * better return too much than too little anyway
270 */
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++;
274
275 return it_old.it_value.tv_sec;
276}
277
278SYSCALL_DEFINE3(setitimer, int, which, 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(&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",
291 current->comm);
292 }
293
294 error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
295 if (error || !ovalue)
296 return error;
297
298 if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))
299 return -EFAULT;
300 return 0;
301}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/kernel/itimer.c
4 *
5 * Copyright (C) 1992 Darren Senn
6 */
7
8/* These are all the functions necessary to implement itimers */
9
10#include <linux/mm.h>
11#include <linux/interrupt.h>
12#include <linux/syscalls.h>
13#include <linux/time.h>
14#include <linux/sched/signal.h>
15#include <linux/sched/cputime.h>
16#include <linux/posix-timers.h>
17#include <linux/hrtimer.h>
18#include <trace/events/timer.h>
19#include <linux/compat.h>
20
21#include <linux/uaccess.h>
22
23/**
24 * itimer_get_remtime - get remaining time for the timer
25 *
26 * @timer: the timer to read
27 *
28 * Returns the delta between the expiry time and now, which can be
29 * less than zero or 1usec for an pending expired timer
30 */
31static struct timeval itimer_get_remtime(struct hrtimer *timer)
32{
33 ktime_t rem = __hrtimer_get_remaining(timer, true);
34
35 /*
36 * Racy but safe: if the itimer expires after the above
37 * hrtimer_get_remtime() call but before this condition
38 * then we return 0 - which is correct.
39 */
40 if (hrtimer_active(timer)) {
41 if (rem <= 0)
42 rem = NSEC_PER_USEC;
43 } else
44 rem = 0;
45
46 return ktime_to_timeval(rem);
47}
48
49static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
50 struct itimerval *const value)
51{
52 u64 val, interval;
53 struct cpu_itimer *it = &tsk->signal->it[clock_id];
54
55 spin_lock_irq(&tsk->sighand->siglock);
56
57 val = it->expires;
58 interval = it->incr;
59 if (val) {
60 struct task_cputime cputime;
61 u64 t;
62
63 thread_group_cputimer(tsk, &cputime);
64 if (clock_id == CPUCLOCK_PROF)
65 t = cputime.utime + cputime.stime;
66 else
67 /* CPUCLOCK_VIRT */
68 t = cputime.utime;
69
70 if (val < t)
71 /* about to fire */
72 val = TICK_NSEC;
73 else
74 val -= t;
75 }
76
77 spin_unlock_irq(&tsk->sighand->siglock);
78
79 value->it_value = ns_to_timeval(val);
80 value->it_interval = ns_to_timeval(interval);
81}
82
83int do_getitimer(int which, struct itimerval *value)
84{
85 struct task_struct *tsk = current;
86
87 switch (which) {
88 case ITIMER_REAL:
89 spin_lock_irq(&tsk->sighand->siglock);
90 value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
91 value->it_interval =
92 ktime_to_timeval(tsk->signal->it_real_incr);
93 spin_unlock_irq(&tsk->sighand->siglock);
94 break;
95 case ITIMER_VIRTUAL:
96 get_cpu_itimer(tsk, CPUCLOCK_VIRT, value);
97 break;
98 case ITIMER_PROF:
99 get_cpu_itimer(tsk, CPUCLOCK_PROF, value);
100 break;
101 default:
102 return(-EINVAL);
103 }
104 return 0;
105}
106
107SYSCALL_DEFINE2(getitimer, int, which, struct itimerval __user *, value)
108{
109 int error = -EFAULT;
110 struct itimerval get_buffer;
111
112 if (value) {
113 error = do_getitimer(which, &get_buffer);
114 if (!error &&
115 copy_to_user(value, &get_buffer, sizeof(get_buffer)))
116 error = -EFAULT;
117 }
118 return error;
119}
120
121#ifdef CONFIG_COMPAT
122COMPAT_SYSCALL_DEFINE2(getitimer, int, which,
123 struct compat_itimerval __user *, it)
124{
125 struct itimerval kit;
126 int error = do_getitimer(which, &kit);
127
128 if (!error && put_compat_itimerval(it, &kit))
129 error = -EFAULT;
130 return error;
131}
132#endif
133
134
135/*
136 * The timer is automagically restarted, when interval != 0
137 */
138enum hrtimer_restart it_real_fn(struct hrtimer *timer)
139{
140 struct signal_struct *sig =
141 container_of(timer, struct signal_struct, real_timer);
142
143 trace_itimer_expire(ITIMER_REAL, sig->leader_pid, 0);
144 kill_pid_info(SIGALRM, SEND_SIG_PRIV, sig->leader_pid);
145
146 return HRTIMER_NORESTART;
147}
148
149static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
150 const struct itimerval *const value,
151 struct itimerval *const ovalue)
152{
153 u64 oval, nval, ointerval, ninterval;
154 struct cpu_itimer *it = &tsk->signal->it[clock_id];
155
156 /*
157 * Use the to_ktime conversion because that clamps the maximum
158 * value to KTIME_MAX and avoid multiplication overflows.
159 */
160 nval = ktime_to_ns(timeval_to_ktime(value->it_value));
161 ninterval = ktime_to_ns(timeval_to_ktime(value->it_interval));
162
163 spin_lock_irq(&tsk->sighand->siglock);
164
165 oval = it->expires;
166 ointerval = it->incr;
167 if (oval || nval) {
168 if (nval > 0)
169 nval += TICK_NSEC;
170 set_process_cpu_timer(tsk, clock_id, &nval, &oval);
171 }
172 it->expires = nval;
173 it->incr = ninterval;
174 trace_itimer_state(clock_id == CPUCLOCK_VIRT ?
175 ITIMER_VIRTUAL : ITIMER_PROF, value, nval);
176
177 spin_unlock_irq(&tsk->sighand->siglock);
178
179 if (ovalue) {
180 ovalue->it_value = ns_to_timeval(oval);
181 ovalue->it_interval = ns_to_timeval(ointerval);
182 }
183}
184
185/*
186 * Returns true if the timeval is in canonical form
187 */
188#define timeval_valid(t) \
189 (((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC))
190
191int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
192{
193 struct task_struct *tsk = current;
194 struct hrtimer *timer;
195 ktime_t expires;
196
197 /*
198 * Validate the timevals in value.
199 */
200 if (!timeval_valid(&value->it_value) ||
201 !timeval_valid(&value->it_interval))
202 return -EINVAL;
203
204 switch (which) {
205 case ITIMER_REAL:
206again:
207 spin_lock_irq(&tsk->sighand->siglock);
208 timer = &tsk->signal->real_timer;
209 if (ovalue) {
210 ovalue->it_value = itimer_get_remtime(timer);
211 ovalue->it_interval
212 = ktime_to_timeval(tsk->signal->it_real_incr);
213 }
214 /* We are sharing ->siglock with it_real_fn() */
215 if (hrtimer_try_to_cancel(timer) < 0) {
216 spin_unlock_irq(&tsk->sighand->siglock);
217 goto again;
218 }
219 expires = timeval_to_ktime(value->it_value);
220 if (expires != 0) {
221 tsk->signal->it_real_incr =
222 timeval_to_ktime(value->it_interval);
223 hrtimer_start(timer, expires, HRTIMER_MODE_REL);
224 } else
225 tsk->signal->it_real_incr = 0;
226
227 trace_itimer_state(ITIMER_REAL, value, 0);
228 spin_unlock_irq(&tsk->sighand->siglock);
229 break;
230 case ITIMER_VIRTUAL:
231 set_cpu_itimer(tsk, CPUCLOCK_VIRT, value, ovalue);
232 break;
233 case ITIMER_PROF:
234 set_cpu_itimer(tsk, CPUCLOCK_PROF, value, ovalue);
235 break;
236 default:
237 return -EINVAL;
238 }
239 return 0;
240}
241
242#ifdef __ARCH_WANT_SYS_ALARM
243
244/**
245 * alarm_setitimer - set alarm in seconds
246 *
247 * @seconds: number of seconds until alarm
248 * 0 disables the alarm
249 *
250 * Returns the remaining time in seconds of a pending timer or 0 when
251 * the timer is not active.
252 *
253 * On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid
254 * negative timeval settings which would cause immediate expiry.
255 */
256static unsigned int alarm_setitimer(unsigned int seconds)
257{
258 struct itimerval it_new, it_old;
259
260#if BITS_PER_LONG < 64
261 if (seconds > INT_MAX)
262 seconds = INT_MAX;
263#endif
264 it_new.it_value.tv_sec = seconds;
265 it_new.it_value.tv_usec = 0;
266 it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
267
268 do_setitimer(ITIMER_REAL, &it_new, &it_old);
269
270 /*
271 * We can't return 0 if we have an alarm pending ... And we'd
272 * better return too much than too little anyway
273 */
274 if ((!it_old.it_value.tv_sec && it_old.it_value.tv_usec) ||
275 it_old.it_value.tv_usec >= 500000)
276 it_old.it_value.tv_sec++;
277
278 return it_old.it_value.tv_sec;
279}
280
281/*
282 * For backwards compatibility? This can be done in libc so Alpha
283 * and all newer ports shouldn't need it.
284 */
285SYSCALL_DEFINE1(alarm, unsigned int, seconds)
286{
287 return alarm_setitimer(seconds);
288}
289
290#endif
291
292SYSCALL_DEFINE3(setitimer, int, which, struct itimerval __user *, value,
293 struct itimerval __user *, ovalue)
294{
295 struct itimerval set_buffer, get_buffer;
296 int error;
297
298 if (value) {
299 if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
300 return -EFAULT;
301 } else {
302 memset(&set_buffer, 0, sizeof(set_buffer));
303 printk_once(KERN_WARNING "%s calls setitimer() with new_value NULL pointer."
304 " Misfeature support will be removed\n",
305 current->comm);
306 }
307
308 error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
309 if (error || !ovalue)
310 return error;
311
312 if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))
313 return -EFAULT;
314 return 0;
315}
316
317#ifdef CONFIG_COMPAT
318COMPAT_SYSCALL_DEFINE3(setitimer, int, which,
319 struct compat_itimerval __user *, in,
320 struct compat_itimerval __user *, out)
321{
322 struct itimerval kin, kout;
323 int error;
324
325 if (in) {
326 if (get_compat_itimerval(&kin, in))
327 return -EFAULT;
328 } else {
329 memset(&kin, 0, sizeof(kin));
330 }
331
332 error = do_setitimer(which, &kin, out ? &kout : NULL);
333 if (error || !out)
334 return error;
335 if (put_compat_itimerval(out, &kout))
336 return -EFAULT;
337 return 0;
338}
339#endif