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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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070015
16#include <asm/uaccess.h>
17
Thomas Gleixner2ff678b2006-01-09 20:52:34 -080018/**
19 * itimer_get_remtime - get remaining time for the timer
20 *
21 * @timer: the timer to read
22 *
23 * Returns the delta between the expiry time and now, which can be
24 * less than zero or 1usec for an pending expired timer
25 */
26static struct timeval itimer_get_remtime(struct hrtimer *timer)
Linus Torvalds1da177e2005-04-16 15:20:36 -070027{
Thomas Gleixner2ff678b2006-01-09 20:52:34 -080028 ktime_t rem = hrtimer_get_remaining(timer);
Linus Torvalds1da177e2005-04-16 15:20:36 -070029
Thomas Gleixner2ff678b2006-01-09 20:52:34 -080030 /*
31 * Racy but safe: if the itimer expires after the above
32 * hrtimer_get_remtime() call but before this condition
33 * then we return 0 - which is correct.
34 */
35 if (hrtimer_active(timer)) {
36 if (rem.tv64 <= 0)
37 rem.tv64 = NSEC_PER_USEC;
38 } else
39 rem.tv64 = 0;
40
41 return ktime_to_timeval(rem);
Linus Torvalds1da177e2005-04-16 15:20:36 -070042}
43
Stanislaw Gruszka42c4ab42009-07-29 12:15:26 +020044static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
45 struct itimerval *value)
46{
47 cputime_t cval, cinterval;
48 struct cpu_itimer *it = &tsk->signal->it[clock_id];
49
50 spin_lock_irq(&tsk->sighand->siglock);
51
52 cval = it->expires;
53 cinterval = it->incr;
54 if (!cputime_eq(cval, cputime_zero)) {
55 struct task_cputime cputime;
56 cputime_t t;
57
58 thread_group_cputimer(tsk, &cputime);
59 if (clock_id == CPUCLOCK_PROF)
60 t = cputime_add(cputime.utime, cputime.stime);
61 else
62 /* CPUCLOCK_VIRT */
63 t = cputime.utime;
64
65 if (cputime_le(cval, t))
66 /* about to fire */
67 cval = jiffies_to_cputime(1);
68 else
69 cval = cputime_sub(cval, t);
70 }
71
72 spin_unlock_irq(&tsk->sighand->siglock);
73
74 cputime_to_timeval(cval, &value->it_value);
75 cputime_to_timeval(cinterval, &value->it_interval);
76}
77
Linus Torvalds1da177e2005-04-16 15:20:36 -070078int do_getitimer(int which, struct itimerval *value)
79{
80 struct task_struct *tsk = current;
Linus Torvalds1da177e2005-04-16 15:20:36 -070081
82 switch (which) {
83 case ITIMER_REAL:
Thomas Gleixnerbc1978d2006-02-01 03:05:08 -080084 spin_lock_irq(&tsk->sighand->siglock);
Thomas Gleixner2ff678b2006-01-09 20:52:34 -080085 value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
86 value->it_interval =
87 ktime_to_timeval(tsk->signal->it_real_incr);
Thomas Gleixnerbc1978d2006-02-01 03:05:08 -080088 spin_unlock_irq(&tsk->sighand->siglock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070089 break;
90 case ITIMER_VIRTUAL:
Stanislaw Gruszka42c4ab42009-07-29 12:15:26 +020091 get_cpu_itimer(tsk, CPUCLOCK_VIRT, value);
Linus Torvalds1da177e2005-04-16 15:20:36 -070092 break;
93 case ITIMER_PROF:
Stanislaw Gruszka42c4ab42009-07-29 12:15:26 +020094 get_cpu_itimer(tsk, CPUCLOCK_PROF, value);
Linus Torvalds1da177e2005-04-16 15:20:36 -070095 break;
96 default:
97 return(-EINVAL);
98 }
99 return 0;
100}
101
Heiko Carstensb290ebe2009-01-14 14:14:06 +0100102SYSCALL_DEFINE2(getitimer, int, which, struct itimerval __user *, value)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103{
104 int error = -EFAULT;
105 struct itimerval get_buffer;
106
107 if (value) {
108 error = do_getitimer(which, &get_buffer);
109 if (!error &&
110 copy_to_user(value, &get_buffer, sizeof(get_buffer)))
111 error = -EFAULT;
112 }
113 return error;
114}
115
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116
Thomas Gleixner2ff678b2006-01-09 20:52:34 -0800117/*
118 * The timer is automagically restarted, when interval != 0
119 */
Thomas Gleixnerc9cb2e32007-02-16 01:27:49 -0800120enum hrtimer_restart it_real_fn(struct hrtimer *timer)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121{
Roman Zippel05cfb612006-03-26 01:38:12 -0800122 struct signal_struct *sig =
Daniel Walker0719e372007-10-18 03:06:11 -0700123 container_of(timer, struct signal_struct, real_timer);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124
Oleg Nesterovfea9d172008-02-08 04:19:19 -0800125 kill_pid_info(SIGALRM, SEND_SIG_PRIV, sig->leader_pid);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126
Thomas Gleixner2ff678b2006-01-09 20:52:34 -0800127 return HRTIMER_NORESTART;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128}
129
Stanislaw Gruszka42c4ab42009-07-29 12:15:26 +0200130static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
131 struct itimerval *value, struct itimerval *ovalue)
132{
133 cputime_t cval, cinterval, nval, ninterval;
134 struct cpu_itimer *it = &tsk->signal->it[clock_id];
135
136 nval = timeval_to_cputime(&value->it_value);
137 ninterval = timeval_to_cputime(&value->it_interval);
138
139 spin_lock_irq(&tsk->sighand->siglock);
140
141 cval = it->expires;
142 cinterval = it->incr;
143 if (!cputime_eq(cval, cputime_zero) ||
144 !cputime_eq(nval, cputime_zero)) {
145 if (cputime_gt(nval, cputime_zero))
146 nval = cputime_add(nval, jiffies_to_cputime(1));
147 set_process_cpu_timer(tsk, clock_id, &nval, &cval);
148 }
149 it->expires = nval;
150 it->incr = ninterval;
151
152 spin_unlock_irq(&tsk->sighand->siglock);
153
154 if (ovalue) {
155 cputime_to_timeval(cval, &ovalue->it_value);
156 cputime_to_timeval(cinterval, &ovalue->it_interval);
157 }
158}
159
Thomas Gleixner7d99b7d2006-03-25 03:06:35 -0800160/*
Thomas Gleixner7d99b7d2006-03-25 03:06:35 -0800161 * Returns true if the timeval is in canonical form
162 */
163#define timeval_valid(t) \
164 (((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC))
165
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
167{
168 struct task_struct *tsk = current;
Thomas Gleixner2ff678b2006-01-09 20:52:34 -0800169 struct hrtimer *timer;
170 ktime_t expires;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700171
Thomas Gleixner7d99b7d2006-03-25 03:06:35 -0800172 /*
173 * Validate the timevals in value.
Thomas Gleixner7d99b7d2006-03-25 03:06:35 -0800174 */
Adrian Bunk35bab752007-05-08 00:30:49 -0700175 if (!timeval_valid(&value->it_value) ||
176 !timeval_valid(&value->it_interval))
177 return -EINVAL;
Thomas Gleixner7d99b7d2006-03-25 03:06:35 -0800178
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179 switch (which) {
180 case ITIMER_REAL:
Thomas Gleixnerbc1978d2006-02-01 03:05:08 -0800181again:
182 spin_lock_irq(&tsk->sighand->siglock);
Thomas Gleixner2ff678b2006-01-09 20:52:34 -0800183 timer = &tsk->signal->real_timer;
Thomas Gleixner2ff678b2006-01-09 20:52:34 -0800184 if (ovalue) {
185 ovalue->it_value = itimer_get_remtime(timer);
186 ovalue->it_interval
187 = ktime_to_timeval(tsk->signal->it_real_incr);
Oleg Nesterovf01b1b02005-06-28 20:44:47 -0700188 }
Thomas Gleixnera16a1c02006-02-01 03:05:09 -0800189 /* We are sharing ->siglock with it_real_fn() */
190 if (hrtimer_try_to_cancel(timer) < 0) {
191 spin_unlock_irq(&tsk->sighand->siglock);
192 goto again;
193 }
Thomas Gleixner2ff678b2006-01-09 20:52:34 -0800194 expires = timeval_to_ktime(value->it_value);
Thomas Gleixner8bfd9a72007-02-16 01:28:12 -0800195 if (expires.tv64 != 0) {
196 tsk->signal->it_real_incr =
197 timeval_to_ktime(value->it_interval);
Thomas Gleixnerc9cb2e32007-02-16 01:27:49 -0800198 hrtimer_start(timer, expires, HRTIMER_MODE_REL);
Thomas Gleixner8bfd9a72007-02-16 01:28:12 -0800199 } else
200 tsk->signal->it_real_incr.tv64 = 0;
201
Thomas Gleixnerbc1978d2006-02-01 03:05:08 -0800202 spin_unlock_irq(&tsk->sighand->siglock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203 break;
204 case ITIMER_VIRTUAL:
Stanislaw Gruszka42c4ab42009-07-29 12:15:26 +0200205 set_cpu_itimer(tsk, CPUCLOCK_VIRT, value, ovalue);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700206 break;
207 case ITIMER_PROF:
Stanislaw Gruszka42c4ab42009-07-29 12:15:26 +0200208 set_cpu_itimer(tsk, CPUCLOCK_PROF, value, ovalue);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209 break;
210 default:
211 return -EINVAL;
212 }
213 return 0;
214}
215
Thomas Gleixnerc08b8a42006-03-25 03:06:33 -0800216/**
217 * alarm_setitimer - set alarm in seconds
218 *
219 * @seconds: number of seconds until alarm
220 * 0 disables the alarm
221 *
222 * Returns the remaining time in seconds of a pending timer or 0 when
223 * the timer is not active.
224 *
225 * On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid
226 * negative timeval settings which would cause immediate expiry.
227 */
228unsigned int alarm_setitimer(unsigned int seconds)
229{
230 struct itimerval it_new, it_old;
231
232#if BITS_PER_LONG < 64
233 if (seconds > INT_MAX)
234 seconds = INT_MAX;
235#endif
236 it_new.it_value.tv_sec = seconds;
237 it_new.it_value.tv_usec = 0;
238 it_new.it_interval.tv_sec = it_new.it_interval.tv_usec = 0;
239
240 do_setitimer(ITIMER_REAL, &it_new, &it_old);
241
242 /*
243 * We can't return 0 if we have an alarm pending ... And we'd
244 * better return too much than too little anyway
245 */
246 if ((!it_old.it_value.tv_sec && it_old.it_value.tv_usec) ||
247 it_old.it_value.tv_usec >= 500000)
248 it_old.it_value.tv_sec++;
249
250 return it_old.it_value.tv_sec;
251}
252
Heiko Carstens362e9c02009-01-14 14:14:07 +0100253SYSCALL_DEFINE3(setitimer, int, which, struct itimerval __user *, value,
254 struct itimerval __user *, ovalue)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255{
256 struct itimerval set_buffer, get_buffer;
257 int error;
258
259 if (value) {
260 if(copy_from_user(&set_buffer, value, sizeof(set_buffer)))
261 return -EFAULT;
262 } else
263 memset((char *) &set_buffer, 0, sizeof(set_buffer));
264
265 error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
266 if (error || !ovalue)
267 return error;
268
269 if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer)))
Daniel Walker0719e372007-10-18 03:06:11 -0700270 return -EFAULT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271 return 0;
272}