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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 | */ |
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 | static 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 (!cputime_eq(cval, cputime_zero)) { |
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_add(cputime.utime, cputime.stime); |
62 | else |
63 | /* CPUCLOCK_VIRT */ |
64 | t = cputime.utime; |
65 | |
66 | if (cputime_le(cval, t)) |
67 | /* about to fire */ |
68 | cval = cputime_one_jiffy; |
69 | else |
70 | cval = cputime_sub(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 | |
79 | int 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 | |
103 | SYSCALL_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 | */ |
121 | enum 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 | |
132 | static 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 | |
143 | static 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 (!cputime_eq(cval, cputime_zero) || |
165 | !cputime_eq(nval, cputime_zero)) { |
166 | if (cputime_gt(nval, cputime_zero)) |
167 | nval = cputime_add(nval, cputime_one_jiffy); |
168 | set_process_cpu_timer(tsk, clock_id, &nval, &cval); |
169 | } |
170 | it->expires = nval; |
171 | it->incr = ninterval; |
172 | it->error = error; |
173 | it->incr_error = incr_error; |
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 | cputime_to_timeval(cval, &ovalue->it_value); |
181 | cputime_to_timeval(cinterval, &ovalue->it_interval); |
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 | |
191 | int 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: |
206 | again: |
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.tv64 != 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.tv64 = 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 | /** |
243 | * alarm_setitimer - set alarm in seconds |
244 | * |
245 | * @seconds: number of seconds until alarm |
246 | * 0 disables the alarm |
247 | * |
248 | * Returns the remaining time in seconds of a pending timer or 0 when |
249 | * the timer is not active. |
250 | * |
251 | * On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid |
252 | * negative timeval settings which would cause immediate expiry. |
253 | */ |
254 | unsigned int alarm_setitimer(unsigned int seconds) |
255 | { |
256 | struct itimerval it_new, it_old; |
257 | |
258 | #if BITS_PER_LONG < 64 |
259 | if (seconds > INT_MAX) |
260 | seconds = INT_MAX; |
261 | #endif |
262 | it_new.it_value.tv_sec = seconds; |
263 | it_new.it_value.tv_usec = 0; |
264 | it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0; |
265 | |
266 | do_setitimer(ITIMER_REAL, &it_new, &it_old); |
267 | |
268 | /* |
269 | * We can't return 0 if we have an alarm pending ... And we'd |
270 | * better return too much than too little anyway |
271 | */ |
272 | if ((!it_old.it_value.tv_sec && it_old.it_value.tv_usec) || |
273 | it_old.it_value.tv_usec >= 500000) |
274 | it_old.it_value.tv_sec++; |
275 | |
276 | return it_old.it_value.tv_sec; |
277 | } |
278 | |
279 | SYSCALL_DEFINE3(setitimer, int, which, struct itimerval __user *, value, |
280 | struct itimerval __user *, ovalue) |
281 | { |
282 | struct itimerval set_buffer, get_buffer; |
283 | int error; |
284 | |
285 | if (value) { |
286 | if(copy_from_user(&set_buffer, value, sizeof(set_buffer))) |
287 | return -EFAULT; |
288 | } else |
289 | memset((char *) &set_buffer, 0, sizeof(set_buffer)); |
290 | |
291 | error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL); |
292 | if (error || !ovalue) |
293 | return error; |
294 | |
295 | if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer))) |
296 | return -EFAULT; |
297 | return 0; |
298 | } |
299 |
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