arm: tegra: register save and restore ops
[linux-3.10.git] / kernel / itimer.c
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 (cval) {
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.utime + cputime.stime;
62                 else
63                         /* CPUCLOCK_VIRT */
64                         t = cputime.utime;
65
66                 if (cval < t)
67                         /* about to fire */
68                         cval = cputime_one_jiffy;
69                 else
70                         cval = 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 (cval || nval) {
165                 if (nval > 0)
166                         nval += cputime_one_jiffy;
167                 set_process_cpu_timer(tsk, clock_id, &nval, &cval);
168         }
169         it->expires = nval;
170         it->incr = ninterval;
171         it->error = error;
172         it->incr_error = incr_error;
173         trace_itimer_state(clock_id == CPUCLOCK_VIRT ?
174                            ITIMER_VIRTUAL : ITIMER_PROF, value, nval);
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
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
190 int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue)
191 {
192         struct task_struct *tsk = current;
193         struct hrtimer *timer;
194         ktime_t expires;
195
196         /*
197          * Validate the timevals in value.
198          */
199         if (!timeval_valid(&value->it_value) ||
200             !timeval_valid(&value->it_interval))
201                 return -EINVAL;
202
203         switch (which) {
204         case ITIMER_REAL:
205 again:
206                 spin_lock_irq(&tsk->sighand->siglock);
207                 timer = &tsk->signal->real_timer;
208                 if (ovalue) {
209                         ovalue->it_value = itimer_get_remtime(timer);
210                         ovalue->it_interval
211                                 = ktime_to_timeval(tsk->signal->it_real_incr);
212                 }
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                 }
218                 expires = timeval_to_ktime(value->it_value);
219                 if (expires.tv64 != 0) {
220                         tsk->signal->it_real_incr =
221                                 timeval_to_ktime(value->it_interval);
222                         hrtimer_start(timer, expires, HRTIMER_MODE_REL);
223                 } else
224                         tsk->signal->it_real_incr.tv64 = 0;
225
226                 trace_itimer_state(ITIMER_REAL, value, 0);
227                 spin_unlock_irq(&tsk->sighand->siglock);
228                 break;
229         case ITIMER_VIRTUAL:
230                 set_cpu_itimer(tsk, CPUCLOCK_VIRT, value, ovalue);
231                 break;
232         case ITIMER_PROF:
233                 set_cpu_itimer(tsk, CPUCLOCK_PROF, value, ovalue);
234                 break;
235         default:
236                 return -EINVAL;
237         }
238         return 0;
239 }
240
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  */
253 unsigned 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
278 SYSCALL_DEFINE3(setitimer, int, which, struct itimerval __user *, value,
279                 struct itimerval __user *, ovalue)
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;
287         } else {
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);
292         }
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)))
299                 return -EFAULT;
300         return 0;
301 }