mm/page_alloc: prevent merging between isolated and other pageblocks
[linux-2.6-block.git] / kernel / time / itimer.c
CommitLineData
1da177e4
LT
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>
1da177e4
LT
10#include <linux/interrupt.h>
11#include <linux/syscalls.h>
12#include <linux/time.h>
13#include <linux/posix-timers.h>
2ff678b8 14#include <linux/hrtimer.h>
3f0a525e 15#include <trace/events/timer.h>
1da177e4
LT
16
17#include <asm/uaccess.h>
18
2ff678b8
TG
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)
1da177e4 28{
51cbb524 29 ktime_t rem = __hrtimer_get_remaining(timer, true);
1da177e4 30
2ff678b8
TG
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);
1da177e4
LT
43}
44
42c4ab41 45static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
8356b5f9 46 struct itimerval *const value)
42c4ab41
SG
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;
64861634 55 if (cval) {
42c4ab41
SG
56 struct task_cputime cputime;
57 cputime_t t;
58
59 thread_group_cputimer(tsk, &cputime);
60 if (clock_id == CPUCLOCK_PROF)
64861634 61 t = cputime.utime + cputime.stime;
42c4ab41
SG
62 else
63 /* CPUCLOCK_VIRT */
64 t = cputime.utime;
65
64861634 66 if (cval < t)
42c4ab41 67 /* about to fire */
a42548a1 68 cval = cputime_one_jiffy;
42c4ab41 69 else
64861634 70 cval = cval - t;
42c4ab41
SG
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
1da177e4
LT
79int do_getitimer(int which, struct itimerval *value)
80{
81 struct task_struct *tsk = current;
1da177e4
LT
82
83 switch (which) {
84 case ITIMER_REAL:
bc1978d4 85 spin_lock_irq(&tsk->sighand->siglock);
2ff678b8
TG
86 value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
87 value->it_interval =
88 ktime_to_timeval(tsk->signal->it_real_incr);
bc1978d4 89 spin_unlock_irq(&tsk->sighand->siglock);
1da177e4
LT
90 break;
91 case ITIMER_VIRTUAL:
42c4ab41 92 get_cpu_itimer(tsk, CPUCLOCK_VIRT, value);
1da177e4
LT
93 break;
94 case ITIMER_PROF:
42c4ab41 95 get_cpu_itimer(tsk, CPUCLOCK_PROF, value);
1da177e4
LT
96 break;
97 default:
98 return(-EINVAL);
99 }
100 return 0;
101}
102
b290ebe2 103SYSCALL_DEFINE2(getitimer, int, which, struct itimerval __user *, value)
1da177e4
LT
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
1da177e4 117
2ff678b8
TG
118/*
119 * The timer is automagically restarted, when interval != 0
120 */
c9cb2e3d 121enum hrtimer_restart it_real_fn(struct hrtimer *timer)
1da177e4 122{
05cfb614 123 struct signal_struct *sig =
0719e370 124 container_of(timer, struct signal_struct, real_timer);
1da177e4 125
3f0a525e 126 trace_itimer_expire(ITIMER_REAL, sig->leader_pid, 0);
fea9d175 127 kill_pid_info(SIGALRM, SEND_SIG_PRIV, sig->leader_pid);
2ff678b8 128
2ff678b8 129 return HRTIMER_NORESTART;
1da177e4
LT
130}
131
8356b5f9
SG
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
42c4ab41 143static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
8356b5f9
SG
144 const struct itimerval *const value,
145 struct itimerval *const ovalue)
42c4ab41 146{
8356b5f9
SG
147 cputime_t cval, nval, cinterval, ninterval;
148 s64 ns_ninterval, ns_nval;
8747d793 149 u32 error, incr_error;
42c4ab41
SG
150 struct cpu_itimer *it = &tsk->signal->it[clock_id];
151
152 nval = timeval_to_cputime(&value->it_value);
8356b5f9 153 ns_nval = timeval_to_ns(&value->it_value);
42c4ab41 154 ninterval = timeval_to_cputime(&value->it_interval);
8356b5f9
SG
155 ns_ninterval = timeval_to_ns(&value->it_interval);
156
8747d793
SG
157 error = cputime_sub_ns(nval, ns_nval);
158 incr_error = cputime_sub_ns(ninterval, ns_ninterval);
42c4ab41
SG
159
160 spin_lock_irq(&tsk->sighand->siglock);
161
162 cval = it->expires;
163 cinterval = it->incr;
64861634
MS
164 if (cval || nval) {
165 if (nval > 0)
166 nval += cputime_one_jiffy;
42c4ab41
SG
167 set_process_cpu_timer(tsk, clock_id, &nval, &cval);
168 }
169 it->expires = nval;
170 it->incr = ninterval;
8747d793
SG
171 it->error = error;
172 it->incr_error = incr_error;
3f0a525e
XG
173 trace_itimer_state(clock_id == CPUCLOCK_VIRT ?
174 ITIMER_VIRTUAL : ITIMER_PROF, value, nval);
42c4ab41
SG
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
7d99b7d6
TG
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
1da177e4
LT
190int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
191{
192 struct task_struct *tsk = current;
2ff678b8
TG
193 struct hrtimer *timer;
194 ktime_t expires;
1da177e4 195
7d99b7d6
TG
196 /*
197 * Validate the timevals in value.
7d99b7d6 198 */
35bab756
AB
199 if (!timeval_valid(&value->it_value) ||
200 !timeval_valid(&value->it_interval))
201 return -EINVAL;
7d99b7d6 202
1da177e4
LT
203 switch (which) {
204 case ITIMER_REAL:
bc1978d4
TG
205again:
206 spin_lock_irq(&tsk->sighand->siglock);
2ff678b8 207 timer = &tsk->signal->real_timer;
1da177e4 208 if (ovalue) {
2ff678b8
TG
209 ovalue->it_value = itimer_get_remtime(timer);
210 ovalue->it_interval
211 = ktime_to_timeval(tsk->signal->it_real_incr);
1da177e4 212 }
a16a1c09
TG
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 }
2ff678b8 218 expires = timeval_to_ktime(value->it_value);
8bfd9a7a
TG
219 if (expires.tv64 != 0) {
220 tsk->signal->it_real_incr =
221 timeval_to_ktime(value->it_interval);
c9cb2e3d 222 hrtimer_start(timer, expires, HRTIMER_MODE_REL);
8bfd9a7a
TG
223 } else
224 tsk->signal->it_real_incr.tv64 = 0;
225
3f0a525e 226 trace_itimer_state(ITIMER_REAL, value, 0);
bc1978d4 227 spin_unlock_irq(&tsk->sighand->siglock);
1da177e4
LT
228 break;
229 case ITIMER_VIRTUAL:
42c4ab41 230 set_cpu_itimer(tsk, CPUCLOCK_VIRT, value, ovalue);
1da177e4
LT
231 break;
232 case ITIMER_PROF:
42c4ab41 233 set_cpu_itimer(tsk, CPUCLOCK_PROF, value, ovalue);
1da177e4
LT
234 break;
235 default:
236 return -EINVAL;
237 }
238 return 0;
239}
240
c08b8a49
TG
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
362e9c07
HC
278SYSCALL_DEFINE3(setitimer, int, which, struct itimerval __user *, value,
279 struct itimerval __user *, ovalue)
1da177e4
LT
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;
aa2bf9bc 287 } else {
9886f444
TG
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);
aa2bf9bc 292 }
1da177e4
LT
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)))
0719e370 299 return -EFAULT;
1da177e4
LT
300 return 0;
301}