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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070010#include <linux/interrupt.h>
11#include <linux/syscalls.h>
12#include <linux/time.h>
13#include <linux/posix-timers.h>
Thomas Gleixner2ff678b2006-01-09 20:52:34 -080014#include <linux/hrtimer.h>
Xiao Guangrong3f0a5252009-08-10 10:52:30 +080015#include <trace/events/timer.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070016
17#include <asm/uaccess.h>
18
Thomas Gleixner2ff678b2006-01-09 20:52:34 -080019/**
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)
Linus Torvalds1da177e2005-04-16 15:20:36 -070028{
Thomas Gleixner2ff678b2006-01-09 20:52:34 -080029 ktime_t rem = hrtimer_get_remaining(timer);
Linus Torvalds1da177e2005-04-16 15:20:36 -070030
Thomas Gleixner2ff678b2006-01-09 20:52:34 -080031 /*
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);
Linus Torvalds1da177e2005-04-16 15:20:36 -070043}
44
Stanislaw Gruszka42c4ab42009-07-29 12:15:26 +020045static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
Stanislaw Gruszka8356b5f2009-07-29 12:15:27 +020046 struct itimerval *const value)
Stanislaw Gruszka42c4ab42009-07-29 12:15:26 +020047{
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 */
Stanislaw Gruszkaa42548a2009-07-29 12:15:29 +020068 cval = cputime_one_jiffy;
Stanislaw Gruszka42c4ab42009-07-29 12:15:26 +020069 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
Linus Torvalds1da177e2005-04-16 15:20:36 -070079int do_getitimer(int which, struct itimerval *value)
80{
81 struct task_struct *tsk = current;
Linus Torvalds1da177e2005-04-16 15:20:36 -070082
83 switch (which) {
84 case ITIMER_REAL:
Thomas Gleixnerbc1978d2006-02-01 03:05:08 -080085 spin_lock_irq(&tsk->sighand->siglock);
Thomas Gleixner2ff678b2006-01-09 20:52:34 -080086 value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
87 value->it_interval =
88 ktime_to_timeval(tsk->signal->it_real_incr);
Thomas Gleixnerbc1978d2006-02-01 03:05:08 -080089 spin_unlock_irq(&tsk->sighand->siglock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070090 break;
91 case ITIMER_VIRTUAL:
Stanislaw Gruszka42c4ab42009-07-29 12:15:26 +020092 get_cpu_itimer(tsk, CPUCLOCK_VIRT, value);
Linus Torvalds1da177e2005-04-16 15:20:36 -070093 break;
94 case ITIMER_PROF:
Stanislaw Gruszka42c4ab42009-07-29 12:15:26 +020095 get_cpu_itimer(tsk, CPUCLOCK_PROF, value);
Linus Torvalds1da177e2005-04-16 15:20:36 -070096 break;
97 default:
98 return(-EINVAL);
99 }
100 return 0;
101}
102
Heiko Carstensb290ebe2009-01-14 14:14:06 +0100103SYSCALL_DEFINE2(getitimer, int, which, struct itimerval __user *, value)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104{
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
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117
Thomas Gleixner2ff678b2006-01-09 20:52:34 -0800118/*
119 * The timer is automagically restarted, when interval != 0
120 */
Thomas Gleixnerc9cb2e32007-02-16 01:27:49 -0800121enum hrtimer_restart it_real_fn(struct hrtimer *timer)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122{
Roman Zippel05cfb612006-03-26 01:38:12 -0800123 struct signal_struct *sig =
Daniel Walker0719e372007-10-18 03:06:11 -0700124 container_of(timer, struct signal_struct, real_timer);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125
Xiao Guangrong3f0a5252009-08-10 10:52:30 +0800126 trace_itimer_expire(ITIMER_REAL, sig->leader_pid, 0);
Oleg Nesterovfea9d172008-02-08 04:19:19 -0800127 kill_pid_info(SIGALRM, SEND_SIG_PRIV, sig->leader_pid);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128
Thomas Gleixner2ff678b2006-01-09 20:52:34 -0800129 return HRTIMER_NORESTART;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130}
131
Stanislaw Gruszka8356b5f2009-07-29 12:15:27 +0200132static inline u32 cputime_sub_ns(cputime_t ct, s64 real_ns)
Stanislaw Gruszka42c4ab42009-07-29 12:15:26 +0200133{
Stanislaw Gruszka8356b5f2009-07-29 12:15:27 +0200134 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;
Stanislaw Gruszka42c4ab42009-07-29 12:15:26 +0200149 struct cpu_itimer *it = &tsk->signal->it[clock_id];
150
151 nval = timeval_to_cputime(&value->it_value);
Stanislaw Gruszka8356b5f2009-07-29 12:15:27 +0200152 ns_nval = timeval_to_ns(&value->it_value);
Stanislaw Gruszka42c4ab42009-07-29 12:15:26 +0200153 ninterval = timeval_to_cputime(&value->it_interval);
Stanislaw Gruszka8356b5f2009-07-29 12:15:27 +0200154 ns_ninterval = timeval_to_ns(&value->it_interval);
155
156 it->incr_error = cputime_sub_ns(ninterval, ns_ninterval);
157 it->error = cputime_sub_ns(nval, ns_nval);
Stanislaw Gruszka42c4ab42009-07-29 12:15:26 +0200158
159 spin_lock_irq(&tsk->sighand->siglock);
160
161 cval = it->expires;
162 cinterval = it->incr;
163 if (!cputime_eq(cval, cputime_zero) ||
164 !cputime_eq(nval, cputime_zero)) {
165 if (cputime_gt(nval, cputime_zero))
Stanislaw Gruszkaa42548a2009-07-29 12:15:29 +0200166 nval = cputime_add(nval, cputime_one_jiffy);
Stanislaw Gruszka42c4ab42009-07-29 12:15:26 +0200167 set_process_cpu_timer(tsk, clock_id, &nval, &cval);
168 }
169 it->expires = nval;
170 it->incr = ninterval;
Xiao Guangrong3f0a5252009-08-10 10:52:30 +0800171 trace_itimer_state(clock_id == CPUCLOCK_VIRT ?
172 ITIMER_VIRTUAL : ITIMER_PROF, value, nval);
Stanislaw Gruszka42c4ab42009-07-29 12:15:26 +0200173
174 spin_unlock_irq(&tsk->sighand->siglock);
175
176 if (ovalue) {
177 cputime_to_timeval(cval, &ovalue->it_value);
178 cputime_to_timeval(cinterval, &ovalue->it_interval);
179 }
180}
181
Thomas Gleixner7d99b7d2006-03-25 03:06:35 -0800182/*
Thomas Gleixner7d99b7d2006-03-25 03:06:35 -0800183 * Returns true if the timeval is in canonical form
184 */
185#define timeval_valid(t) \
186 (((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC))
187
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
189{
190 struct task_struct *tsk = current;
Thomas Gleixner2ff678b2006-01-09 20:52:34 -0800191 struct hrtimer *timer;
192 ktime_t expires;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193
Thomas Gleixner7d99b7d2006-03-25 03:06:35 -0800194 /*
195 * Validate the timevals in value.
Thomas Gleixner7d99b7d2006-03-25 03:06:35 -0800196 */
Adrian Bunk35bab752007-05-08 00:30:49 -0700197 if (!timeval_valid(&value->it_value) ||
198 !timeval_valid(&value->it_interval))
199 return -EINVAL;
Thomas Gleixner7d99b7d2006-03-25 03:06:35 -0800200
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201 switch (which) {
202 case ITIMER_REAL:
Thomas Gleixnerbc1978d2006-02-01 03:05:08 -0800203again:
204 spin_lock_irq(&tsk->sighand->siglock);
Thomas Gleixner2ff678b2006-01-09 20:52:34 -0800205 timer = &tsk->signal->real_timer;
Thomas Gleixner2ff678b2006-01-09 20:52:34 -0800206 if (ovalue) {
207 ovalue->it_value = itimer_get_remtime(timer);
208 ovalue->it_interval
209 = ktime_to_timeval(tsk->signal->it_real_incr);
Oleg Nesterovf01b1b02005-06-28 20:44:47 -0700210 }
Thomas Gleixnera16a1c02006-02-01 03:05:09 -0800211 /* We are sharing ->siglock with it_real_fn() */
212 if (hrtimer_try_to_cancel(timer) < 0) {
213 spin_unlock_irq(&tsk->sighand->siglock);
214 goto again;
215 }
Thomas Gleixner2ff678b2006-01-09 20:52:34 -0800216 expires = timeval_to_ktime(value->it_value);
Thomas Gleixner8bfd9a72007-02-16 01:28:12 -0800217 if (expires.tv64 != 0) {
218 tsk->signal->it_real_incr =
219 timeval_to_ktime(value->it_interval);
Thomas Gleixnerc9cb2e32007-02-16 01:27:49 -0800220 hrtimer_start(timer, expires, HRTIMER_MODE_REL);
Thomas Gleixner8bfd9a72007-02-16 01:28:12 -0800221 } else
222 tsk->signal->it_real_incr.tv64 = 0;
223
Xiao Guangrong3f0a5252009-08-10 10:52:30 +0800224 trace_itimer_state(ITIMER_REAL, value, 0);
Thomas Gleixnerbc1978d2006-02-01 03:05:08 -0800225 spin_unlock_irq(&tsk->sighand->siglock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700226 break;
227 case ITIMER_VIRTUAL:
Stanislaw Gruszka42c4ab42009-07-29 12:15:26 +0200228 set_cpu_itimer(tsk, CPUCLOCK_VIRT, value, ovalue);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700229 break;
230 case ITIMER_PROF:
Stanislaw Gruszka42c4ab42009-07-29 12:15:26 +0200231 set_cpu_itimer(tsk, CPUCLOCK_PROF, value, ovalue);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232 break;
233 default:
234 return -EINVAL;
235 }
236 return 0;
237}
238
Thomas Gleixnerc08b8a42006-03-25 03:06:33 -0800239/**
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 */
251unsigned 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
Heiko Carstens362e9c02009-01-14 14:14:07 +0100276SYSCALL_DEFINE3(setitimer, int, which, struct itimerval __user *, value,
277 struct itimerval __user *, ovalue)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278{
279 struct itimerval set_buffer, get_buffer;
280 int error;
281
282 if (value) {
283 if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
284 return -EFAULT;
285 } else
286 memset((char *) &set_buffer, 0, sizeof(set_buffer));
287
288 error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
289 if (error || !ovalue)
290 return error;
291
292 if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))
Daniel Walker0719e372007-10-18 03:06:11 -0700293 return -EFAULT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294 return 0;
295}