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1da177e Linux-2.6.12-rc2
Linus Torvalds authored
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>
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14 #include <linux/hrtimer.h>
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15 #include <trace/events/timer.h>
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16
17 #include <asm/uaccess.h>
18
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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)
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28 {
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29 ktime_t rem = hrtimer_get_remaining(timer);
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30
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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);
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Linus Torvalds authored
43 }
44
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45 static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
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46 struct itimerval *const value)
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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 */
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68 cval = cputime_one_jiffy;
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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
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Linus Torvalds authored
79 int do_getitimer(int which, struct itimerval *value)
80 {
81 struct task_struct *tsk = current;
82
83 switch (which) {
84 case ITIMER_REAL:
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85 spin_lock_irq(&tsk->sighand->siglock);
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86 value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
87 value->it_interval =
88 ktime_to_timeval(tsk->signal->it_real_incr);
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89 spin_unlock_irq(&tsk->sighand->siglock);
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90 break;
91 case ITIMER_VIRTUAL:
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92 get_cpu_itimer(tsk, CPUCLOCK_VIRT, value);
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93 break;
94 case ITIMER_PROF:
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95 get_cpu_itimer(tsk, CPUCLOCK_PROF, value);
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96 break;
97 default:
98 return(-EINVAL);
99 }
100 return 0;
101 }
102
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103 SYSCALL_DEFINE2(getitimer, int, which, struct itimerval __user *, value)
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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
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118 /*
119 * The timer is automagically restarted, when interval != 0
120 */
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121 enum hrtimer_restart it_real_fn(struct hrtimer *timer)
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122 {
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123 struct signal_struct *sig =
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124 container_of(timer, struct signal_struct, real_timer);
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125
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126 trace_itimer_expire(ITIMER_REAL, sig->leader_pid, 0);
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Oleg Nesterov authored
127 kill_pid_info(SIGALRM, SEND_SIG_PRIV, sig->leader_pid);
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128
129 return HRTIMER_NORESTART;
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130 }
131
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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
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143 static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
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144 const struct itimerval *const value,
145 struct itimerval *const ovalue)
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146 {
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147 cputime_t cval, nval, cinterval, ninterval;
148 s64 ns_ninterval, ns_nval;
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149 u32 error, incr_error;
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150 struct cpu_itimer *it = &tsk->signal->it[clock_id];
151
152 nval = timeval_to_cputime(&value->it_value);
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153 ns_nval = timeval_to_ns(&value->it_value);
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154 ninterval = timeval_to_cputime(&value->it_interval);
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155 ns_ninterval = timeval_to_ns(&value->it_interval);
156
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157 error = cputime_sub_ns(nval, ns_nval);
158 incr_error = cputime_sub_ns(ninterval, ns_ninterval);
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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))
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167 nval = cputime_add(nval, cputime_one_jiffy);
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168 set_process_cpu_timer(tsk, clock_id, &nval, &cval);
169 }
170 it->expires = nval;
171 it->incr = ninterval;
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172 it->error = error;
173 it->incr_error = incr_error;
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174 trace_itimer_state(clock_id == CPUCLOCK_VIRT ?
175 ITIMER_VIRTUAL : ITIMER_PROF, value, nval);
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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
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Thomas Gleixner authored
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
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
191 int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
192 {
193 struct task_struct *tsk = current;
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194 struct hrtimer *timer;
195 ktime_t expires;
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196
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197 /*
198 * Validate the timevals in value.
199 */
35bab75 @AdrianBunk The scheduled -EINVAL for invalid timevals in setitimer
AdrianBunk authored
200 if (!timeval_valid(&value->it_value) ||
201 !timeval_valid(&value->it_interval))
202 return -EINVAL;
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203
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204 switch (which) {
205 case ITIMER_REAL:
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206 again:
207 spin_lock_irq(&tsk->sighand->siglock);
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208 timer = &tsk->signal->real_timer;
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209 if (ovalue) {
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210 ovalue->it_value = itimer_get_remtime(timer);
211 ovalue->it_interval
212 = ktime_to_timeval(tsk->signal->it_real_incr);
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213 }
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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 }
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219 expires = timeval_to_ktime(value->it_value);
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220 if (expires.tv64 != 0) {
221 tsk->signal->it_real_incr =
222 timeval_to_ktime(value->it_interval);
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223 hrtimer_start(timer, expires, HRTIMER_MODE_REL);
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224 } else
225 tsk->signal->it_real_incr.tv64 = 0;
226
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227 trace_itimer_state(ITIMER_REAL, value, 0);
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228 spin_unlock_irq(&tsk->sighand->siglock);
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229 break;
230 case ITIMER_VIRTUAL:
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231 set_cpu_itimer(tsk, CPUCLOCK_VIRT, value, ovalue);
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232 break;
233 case ITIMER_PROF:
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sgruszka authored
234 set_cpu_itimer(tsk, CPUCLOCK_PROF, value, ovalue);
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235 break;
236 default:
237 return -EINVAL;
238 }
239 return 0;
240 }
241
c08b8a4 [PATCH] sys_alarm() unsigned signed conversion fixup
Thomas Gleixner authored
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
362e9c0 [CVE-2009-0029] System call wrappers part 05
Heiko Carstens authored
279 SYSCALL_DEFINE3(setitimer, int, which, struct itimerval __user *, value,
280 struct itimerval __user *, ovalue)
1da177e Linux-2.6.12-rc2
Linus Torvalds authored
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)))
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296 return -EFAULT;
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297 return 0;
298 }
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