| 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((char *) &set_buffer, 0, sizeof(set_buffer)); |
| 289 | |
| 290 | error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL); |
| 291 | if (error || !ovalue) |
| 292 | return error; |
| 293 | |
| 294 | if (copy_to_user(ovalue, &get_buffer, sizeof(get_buffer))) |
| 295 | return -EFAULT; |
| 296 | return 0; |
| 297 | } |