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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 u64 t, samples[CPUCLOCK_MAX];
59
60 thread_group_sample_cputime(tsk, samples);
61 t = samples[clock_id];
62
63 if (val < t)
64 /* about to fire */
65 val = TICK_NSEC;
66 else
67 val -= t;
68 }
69
70 spin_unlock_irq(&tsk->sighand->siglock);
71
72 value->it_value = ns_to_timeval(val);
73 value->it_interval = ns_to_timeval(interval);
74}
75
76int do_getitimer(int which, struct itimerval *value)
77{
78 struct task_struct *tsk = current;
79
80 switch (which) {
81 case ITIMER_REAL:
82 spin_lock_irq(&tsk->sighand->siglock);
83 value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
84 value->it_interval =
85 ktime_to_timeval(tsk->signal->it_real_incr);
86 spin_unlock_irq(&tsk->sighand->siglock);
87 break;
88 case ITIMER_VIRTUAL:
89 get_cpu_itimer(tsk, CPUCLOCK_VIRT, value);
90 break;
91 case ITIMER_PROF:
92 get_cpu_itimer(tsk, CPUCLOCK_PROF, value);
93 break;
94 default:
95 return(-EINVAL);
96 }
97 return 0;
98}
99
100SYSCALL_DEFINE2(getitimer, int, which, struct itimerval __user *, value)
101{
102 int error = -EFAULT;
103 struct itimerval get_buffer;
104
105 if (value) {
106 error = do_getitimer(which, &get_buffer);
107 if (!error &&
108 copy_to_user(value, &get_buffer, sizeof(get_buffer)))
109 error = -EFAULT;
110 }
111 return error;
112}
113
114#ifdef CONFIG_COMPAT
115COMPAT_SYSCALL_DEFINE2(getitimer, int, which,
116 struct compat_itimerval __user *, it)
117{
118 struct itimerval kit;
119 int error = do_getitimer(which, &kit);
120
121 if (!error && put_compat_itimerval(it, &kit))
122 error = -EFAULT;
123 return error;
124}
125#endif
126
127
128/*
129 * The timer is automagically restarted, when interval != 0
130 */
131enum hrtimer_restart it_real_fn(struct hrtimer *timer)
132{
133 struct signal_struct *sig =
134 container_of(timer, struct signal_struct, real_timer);
135 struct pid *leader_pid = sig->pids[PIDTYPE_TGID];
136
137 trace_itimer_expire(ITIMER_REAL, leader_pid, 0);
138 kill_pid_info(SIGALRM, SEND_SIG_PRIV, leader_pid);
139
140 return HRTIMER_NORESTART;
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 u64 oval, nval, ointerval, ninterval;
148 struct cpu_itimer *it = &tsk->signal->it[clock_id];
149
150 /*
151 * Use the to_ktime conversion because that clamps the maximum
152 * value to KTIME_MAX and avoid multiplication overflows.
153 */
154 nval = ktime_to_ns(timeval_to_ktime(value->it_value));
155 ninterval = ktime_to_ns(timeval_to_ktime(value->it_interval));
156
157 spin_lock_irq(&tsk->sighand->siglock);
158
159 oval = it->expires;
160 ointerval = it->incr;
161 if (oval || nval) {
162 if (nval > 0)
163 nval += TICK_NSEC;
164 set_process_cpu_timer(tsk, clock_id, &nval, &oval);
165 }
166 it->expires = nval;
167 it->incr = ninterval;
168 trace_itimer_state(clock_id == CPUCLOCK_VIRT ?
169 ITIMER_VIRTUAL : ITIMER_PROF, value, nval);
170
171 spin_unlock_irq(&tsk->sighand->siglock);
172
173 if (ovalue) {
174 ovalue->it_value = ns_to_timeval(oval);
175 ovalue->it_interval = ns_to_timeval(ointerval);
176 }
177}
178
179/*
180 * Returns true if the timeval is in canonical form
181 */
182#define timeval_valid(t) \
183 (((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC))
184
185int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
186{
187 struct task_struct *tsk = current;
188 struct hrtimer *timer;
189 ktime_t expires;
190
191 /*
192 * Validate the timevals in value.
193 */
194 if (!timeval_valid(&value->it_value) ||
195 !timeval_valid(&value->it_interval))
196 return -EINVAL;
197
198 switch (which) {
199 case ITIMER_REAL:
200again:
201 spin_lock_irq(&tsk->sighand->siglock);
202 timer = &tsk->signal->real_timer;
203 if (ovalue) {
204 ovalue->it_value = itimer_get_remtime(timer);
205 ovalue->it_interval
206 = ktime_to_timeval(tsk->signal->it_real_incr);
207 }
208 /* We are sharing ->siglock with it_real_fn() */
209 if (hrtimer_try_to_cancel(timer) < 0) {
210 spin_unlock_irq(&tsk->sighand->siglock);
211 hrtimer_cancel_wait_running(timer);
212 goto again;
213 }
214 expires = timeval_to_ktime(value->it_value);
215 if (expires != 0) {
216 tsk->signal->it_real_incr =
217 timeval_to_ktime(value->it_interval);
218 hrtimer_start(timer, expires, HRTIMER_MODE_REL);
219 } else
220 tsk->signal->it_real_incr = 0;
221
222 trace_itimer_state(ITIMER_REAL, value, 0);
223 spin_unlock_irq(&tsk->sighand->siglock);
224 break;
225 case ITIMER_VIRTUAL:
226 set_cpu_itimer(tsk, CPUCLOCK_VIRT, value, ovalue);
227 break;
228 case ITIMER_PROF:
229 set_cpu_itimer(tsk, CPUCLOCK_PROF, value, ovalue);
230 break;
231 default:
232 return -EINVAL;
233 }
234 return 0;
235}
236
237#ifdef __ARCH_WANT_SYS_ALARM
238
239/**
240 * alarm_setitimer - set alarm in seconds
241 *
242 * @seconds: number of seconds until alarm
243 * 0 disables the alarm
244 *
245 * Returns the remaining time in seconds of a pending timer or 0 when
246 * the timer is not active.
247 *
248 * On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid
249 * negative timeval settings which would cause immediate expiry.
250 */
251static unsigned int alarm_setitimer(unsigned int seconds)
252{
253 struct itimerval it_new, it_old;
254
255#if BITS_PER_LONG < 64
256 if (seconds > INT_MAX)
257 seconds = INT_MAX;
258#endif
259 it_new.it_value.tv_sec = seconds;
260 it_new.it_value.tv_usec = 0;
261 it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
262
263 do_setitimer(ITIMER_REAL, &it_new, &it_old);
264
265 /*
266 * We can't return 0 if we have an alarm pending ... And we'd
267 * better return too much than too little anyway
268 */
269 if ((!it_old.it_value.tv_sec && it_old.it_value.tv_usec) ||
270 it_old.it_value.tv_usec >= 500000)
271 it_old.it_value.tv_sec++;
272
273 return it_old.it_value.tv_sec;
274}
275
276/*
277 * For backwards compatibility? This can be done in libc so Alpha
278 * and all newer ports shouldn't need it.
279 */
280SYSCALL_DEFINE1(alarm, unsigned int, seconds)
281{
282 return alarm_setitimer(seconds);
283}
284
285#endif
286
287SYSCALL_DEFINE3(setitimer, int, which, struct itimerval __user *, value,
288 struct itimerval __user *, ovalue)
289{
290 struct itimerval set_buffer, get_buffer;
291 int error;
292
293 if (value) {
294 if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
295 return -EFAULT;
296 } else {
297 memset(&set_buffer, 0, sizeof(set_buffer));
298 printk_once(KERN_WARNING "%s calls setitimer() with new_value NULL pointer."
299 " Misfeature support will be removed\n",
300 current->comm);
301 }
302
303 error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
304 if (error || !ovalue)
305 return error;
306
307 if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))
308 return -EFAULT;
309 return 0;
310}
311
312#ifdef CONFIG_COMPAT
313COMPAT_SYSCALL_DEFINE3(setitimer, int, which,
314 struct compat_itimerval __user *, in,
315 struct compat_itimerval __user *, out)
316{
317 struct itimerval kin, kout;
318 int error;
319
320 if (in) {
321 if (get_compat_itimerval(&kin, in))
322 return -EFAULT;
323 } else {
324 memset(&kin, 0, sizeof(kin));
325 }
326
327 error = do_setitimer(which, &kin, out ? &kout : NULL);
328 if (error || !out)
329 return error;
330 if (put_compat_itimerval(out, &kout))
331 return -EFAULT;
332 return 0;
333}
334#endif
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}