Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * linux/kernel/time.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | * | |
6 | * This file contains the interface functions for the various | |
7 | * time related system calls: time, stime, gettimeofday, settimeofday, | |
8 | * adjtime | |
9 | */ | |
10 | /* | |
11 | * Modification history kernel/time.c | |
12 | * | |
13 | * 1993-09-02 Philip Gladstone | |
14 | * Created file with time related functions from sched.c and adjtimex() | |
15 | * 1993-10-08 Torsten Duwe | |
16 | * adjtime interface update and CMOS clock write code | |
17 | * 1995-08-13 Torsten Duwe | |
18 | * kernel PLL updated to 1994-12-13 specs (rfc-1589) | |
19 | * 1999-01-16 Ulrich Windl | |
20 | * Introduced error checking for many cases in adjtimex(). | |
21 | * Updated NTP code according to technical memorandum Jan '96 | |
22 | * "A Kernel Model for Precision Timekeeping" by Dave Mills | |
23 | * Allow time_constant larger than MAXTC(6) for NTP v4 (MAXTC == 10) | |
24 | * (Even though the technical memorandum forbids it) | |
25 | * 2004-07-14 Christoph Lameter | |
26 | * Added getnstimeofday to allow the posix timer functions to return | |
27 | * with nanosecond accuracy | |
28 | */ | |
29 | ||
30 | #include <linux/module.h> | |
31 | #include <linux/timex.h> | |
c59ede7b | 32 | #include <linux/capability.h> |
1da177e4 | 33 | #include <linux/errno.h> |
1da177e4 LT |
34 | #include <linux/syscalls.h> |
35 | #include <linux/security.h> | |
36 | #include <linux/fs.h> | |
37 | #include <linux/module.h> | |
38 | ||
39 | #include <asm/uaccess.h> | |
40 | #include <asm/unistd.h> | |
41 | ||
42 | /* | |
43 | * The timezone where the local system is located. Used as a default by some | |
44 | * programs who obtain this value by using gettimeofday. | |
45 | */ | |
46 | struct timezone sys_tz; | |
47 | ||
48 | EXPORT_SYMBOL(sys_tz); | |
49 | ||
50 | #ifdef __ARCH_WANT_SYS_TIME | |
51 | ||
52 | /* | |
53 | * sys_time() can be implemented in user-level using | |
54 | * sys_gettimeofday(). Is this for backwards compatibility? If so, | |
55 | * why not move it into the appropriate arch directory (for those | |
56 | * architectures that need it). | |
57 | */ | |
58 | asmlinkage long sys_time(time_t __user * tloc) | |
59 | { | |
20082208 LT |
60 | time_t i; |
61 | struct timespec tv; | |
1da177e4 | 62 | |
20082208 LT |
63 | getnstimeofday(&tv); |
64 | i = tv.tv_sec; | |
1da177e4 LT |
65 | |
66 | if (tloc) { | |
20082208 | 67 | if (put_user(i,tloc)) |
1da177e4 LT |
68 | i = -EFAULT; |
69 | } | |
70 | return i; | |
71 | } | |
72 | ||
73 | /* | |
74 | * sys_stime() can be implemented in user-level using | |
75 | * sys_settimeofday(). Is this for backwards compatibility? If so, | |
76 | * why not move it into the appropriate arch directory (for those | |
77 | * architectures that need it). | |
78 | */ | |
79 | ||
80 | asmlinkage long sys_stime(time_t __user *tptr) | |
81 | { | |
82 | struct timespec tv; | |
83 | int err; | |
84 | ||
85 | if (get_user(tv.tv_sec, tptr)) | |
86 | return -EFAULT; | |
87 | ||
88 | tv.tv_nsec = 0; | |
89 | ||
90 | err = security_settime(&tv, NULL); | |
91 | if (err) | |
92 | return err; | |
93 | ||
94 | do_settimeofday(&tv); | |
95 | return 0; | |
96 | } | |
97 | ||
98 | #endif /* __ARCH_WANT_SYS_TIME */ | |
99 | ||
100 | asmlinkage long sys_gettimeofday(struct timeval __user *tv, struct timezone __user *tz) | |
101 | { | |
102 | if (likely(tv != NULL)) { | |
103 | struct timeval ktv; | |
104 | do_gettimeofday(&ktv); | |
105 | if (copy_to_user(tv, &ktv, sizeof(ktv))) | |
106 | return -EFAULT; | |
107 | } | |
108 | if (unlikely(tz != NULL)) { | |
109 | if (copy_to_user(tz, &sys_tz, sizeof(sys_tz))) | |
110 | return -EFAULT; | |
111 | } | |
112 | return 0; | |
113 | } | |
114 | ||
115 | /* | |
116 | * Adjust the time obtained from the CMOS to be UTC time instead of | |
117 | * local time. | |
118 | * | |
119 | * This is ugly, but preferable to the alternatives. Otherwise we | |
120 | * would either need to write a program to do it in /etc/rc (and risk | |
121 | * confusion if the program gets run more than once; it would also be | |
122 | * hard to make the program warp the clock precisely n hours) or | |
123 | * compile in the timezone information into the kernel. Bad, bad.... | |
124 | * | |
125 | * - TYT, 1992-01-01 | |
126 | * | |
127 | * The best thing to do is to keep the CMOS clock in universal time (UTC) | |
128 | * as real UNIX machines always do it. This avoids all headaches about | |
129 | * daylight saving times and warping kernel clocks. | |
130 | */ | |
77933d72 | 131 | static inline void warp_clock(void) |
1da177e4 LT |
132 | { |
133 | write_seqlock_irq(&xtime_lock); | |
134 | wall_to_monotonic.tv_sec -= sys_tz.tz_minuteswest * 60; | |
135 | xtime.tv_sec += sys_tz.tz_minuteswest * 60; | |
1da177e4 LT |
136 | write_sequnlock_irq(&xtime_lock); |
137 | clock_was_set(); | |
138 | } | |
139 | ||
140 | /* | |
141 | * In case for some reason the CMOS clock has not already been running | |
142 | * in UTC, but in some local time: The first time we set the timezone, | |
143 | * we will warp the clock so that it is ticking UTC time instead of | |
144 | * local time. Presumably, if someone is setting the timezone then we | |
145 | * are running in an environment where the programs understand about | |
146 | * timezones. This should be done at boot time in the /etc/rc script, | |
147 | * as soon as possible, so that the clock can be set right. Otherwise, | |
148 | * various programs will get confused when the clock gets warped. | |
149 | */ | |
150 | ||
151 | int do_sys_settimeofday(struct timespec *tv, struct timezone *tz) | |
152 | { | |
153 | static int firsttime = 1; | |
154 | int error = 0; | |
155 | ||
951069e3 | 156 | if (tv && !timespec_valid(tv)) |
718bcceb TG |
157 | return -EINVAL; |
158 | ||
1da177e4 LT |
159 | error = security_settime(tv, tz); |
160 | if (error) | |
161 | return error; | |
162 | ||
163 | if (tz) { | |
164 | /* SMP safe, global irq locking makes it work. */ | |
165 | sys_tz = *tz; | |
166 | if (firsttime) { | |
167 | firsttime = 0; | |
168 | if (!tv) | |
169 | warp_clock(); | |
170 | } | |
171 | } | |
172 | if (tv) | |
173 | { | |
174 | /* SMP safe, again the code in arch/foo/time.c should | |
175 | * globally block out interrupts when it runs. | |
176 | */ | |
177 | return do_settimeofday(tv); | |
178 | } | |
179 | return 0; | |
180 | } | |
181 | ||
182 | asmlinkage long sys_settimeofday(struct timeval __user *tv, | |
183 | struct timezone __user *tz) | |
184 | { | |
185 | struct timeval user_tv; | |
186 | struct timespec new_ts; | |
187 | struct timezone new_tz; | |
188 | ||
189 | if (tv) { | |
190 | if (copy_from_user(&user_tv, tv, sizeof(*tv))) | |
191 | return -EFAULT; | |
192 | new_ts.tv_sec = user_tv.tv_sec; | |
193 | new_ts.tv_nsec = user_tv.tv_usec * NSEC_PER_USEC; | |
194 | } | |
195 | if (tz) { | |
196 | if (copy_from_user(&new_tz, tz, sizeof(*tz))) | |
197 | return -EFAULT; | |
198 | } | |
199 | ||
200 | return do_sys_settimeofday(tv ? &new_ts : NULL, tz ? &new_tz : NULL); | |
201 | } | |
202 | ||
1da177e4 LT |
203 | asmlinkage long sys_adjtimex(struct timex __user *txc_p) |
204 | { | |
205 | struct timex txc; /* Local copy of parameter */ | |
206 | int ret; | |
207 | ||
208 | /* Copy the user data space into the kernel copy | |
209 | * structure. But bear in mind that the structures | |
210 | * may change | |
211 | */ | |
212 | if(copy_from_user(&txc, txc_p, sizeof(struct timex))) | |
213 | return -EFAULT; | |
214 | ret = do_adjtimex(&txc); | |
215 | return copy_to_user(txc_p, &txc, sizeof(struct timex)) ? -EFAULT : ret; | |
216 | } | |
217 | ||
218 | inline struct timespec current_kernel_time(void) | |
219 | { | |
220 | struct timespec now; | |
221 | unsigned long seq; | |
222 | ||
223 | do { | |
224 | seq = read_seqbegin(&xtime_lock); | |
225 | ||
226 | now = xtime; | |
227 | } while (read_seqretry(&xtime_lock, seq)); | |
228 | ||
229 | return now; | |
230 | } | |
231 | ||
232 | EXPORT_SYMBOL(current_kernel_time); | |
233 | ||
234 | /** | |
235 | * current_fs_time - Return FS time | |
236 | * @sb: Superblock. | |
237 | * | |
8ba8e95e | 238 | * Return the current time truncated to the time granularity supported by |
1da177e4 LT |
239 | * the fs. |
240 | */ | |
241 | struct timespec current_fs_time(struct super_block *sb) | |
242 | { | |
243 | struct timespec now = current_kernel_time(); | |
244 | return timespec_trunc(now, sb->s_time_gran); | |
245 | } | |
246 | EXPORT_SYMBOL(current_fs_time); | |
247 | ||
753e9c5c ED |
248 | /* |
249 | * Convert jiffies to milliseconds and back. | |
250 | * | |
251 | * Avoid unnecessary multiplications/divisions in the | |
252 | * two most common HZ cases: | |
253 | */ | |
254 | unsigned int inline jiffies_to_msecs(const unsigned long j) | |
255 | { | |
256 | #if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ) | |
257 | return (MSEC_PER_SEC / HZ) * j; | |
258 | #elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC) | |
259 | return (j + (HZ / MSEC_PER_SEC) - 1)/(HZ / MSEC_PER_SEC); | |
260 | #else | |
261 | return (j * MSEC_PER_SEC) / HZ; | |
262 | #endif | |
263 | } | |
264 | EXPORT_SYMBOL(jiffies_to_msecs); | |
265 | ||
266 | unsigned int inline jiffies_to_usecs(const unsigned long j) | |
267 | { | |
268 | #if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ) | |
269 | return (USEC_PER_SEC / HZ) * j; | |
270 | #elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC) | |
271 | return (j + (HZ / USEC_PER_SEC) - 1)/(HZ / USEC_PER_SEC); | |
272 | #else | |
273 | return (j * USEC_PER_SEC) / HZ; | |
274 | #endif | |
275 | } | |
276 | EXPORT_SYMBOL(jiffies_to_usecs); | |
277 | ||
1da177e4 | 278 | /** |
8ba8e95e | 279 | * timespec_trunc - Truncate timespec to a granularity |
1da177e4 | 280 | * @t: Timespec |
8ba8e95e | 281 | * @gran: Granularity in ns. |
1da177e4 | 282 | * |
8ba8e95e | 283 | * Truncate a timespec to a granularity. gran must be smaller than a second. |
1da177e4 LT |
284 | * Always rounds down. |
285 | * | |
286 | * This function should be only used for timestamps returned by | |
287 | * current_kernel_time() or CURRENT_TIME, not with do_gettimeofday() because | |
288 | * it doesn't handle the better resolution of the later. | |
289 | */ | |
290 | struct timespec timespec_trunc(struct timespec t, unsigned gran) | |
291 | { | |
292 | /* | |
293 | * Division is pretty slow so avoid it for common cases. | |
294 | * Currently current_kernel_time() never returns better than | |
295 | * jiffies resolution. Exploit that. | |
296 | */ | |
297 | if (gran <= jiffies_to_usecs(1) * 1000) { | |
298 | /* nothing */ | |
299 | } else if (gran == 1000000000) { | |
300 | t.tv_nsec = 0; | |
301 | } else { | |
302 | t.tv_nsec -= t.tv_nsec % gran; | |
303 | } | |
304 | return t; | |
305 | } | |
306 | EXPORT_SYMBOL(timespec_trunc); | |
307 | ||
cf3c769b | 308 | #ifndef CONFIG_GENERIC_TIME |
1da177e4 LT |
309 | /* |
310 | * Simulate gettimeofday using do_gettimeofday which only allows a timeval | |
311 | * and therefore only yields usec accuracy | |
312 | */ | |
313 | void getnstimeofday(struct timespec *tv) | |
314 | { | |
315 | struct timeval x; | |
316 | ||
317 | do_gettimeofday(&x); | |
318 | tv->tv_sec = x.tv_sec; | |
319 | tv->tv_nsec = x.tv_usec * NSEC_PER_USEC; | |
320 | } | |
c6ecf7ed | 321 | EXPORT_SYMBOL_GPL(getnstimeofday); |
1da177e4 LT |
322 | #endif |
323 | ||
753be622 TG |
324 | /* Converts Gregorian date to seconds since 1970-01-01 00:00:00. |
325 | * Assumes input in normal date format, i.e. 1980-12-31 23:59:59 | |
326 | * => year=1980, mon=12, day=31, hour=23, min=59, sec=59. | |
327 | * | |
328 | * [For the Julian calendar (which was used in Russia before 1917, | |
329 | * Britain & colonies before 1752, anywhere else before 1582, | |
330 | * and is still in use by some communities) leave out the | |
331 | * -year/100+year/400 terms, and add 10.] | |
332 | * | |
333 | * This algorithm was first published by Gauss (I think). | |
334 | * | |
335 | * WARNING: this function will overflow on 2106-02-07 06:28:16 on | |
336 | * machines were long is 32-bit! (However, as time_t is signed, we | |
337 | * will already get problems at other places on 2038-01-19 03:14:08) | |
338 | */ | |
339 | unsigned long | |
f4818900 IM |
340 | mktime(const unsigned int year0, const unsigned int mon0, |
341 | const unsigned int day, const unsigned int hour, | |
342 | const unsigned int min, const unsigned int sec) | |
753be622 | 343 | { |
f4818900 IM |
344 | unsigned int mon = mon0, year = year0; |
345 | ||
346 | /* 1..12 -> 11,12,1..10 */ | |
347 | if (0 >= (int) (mon -= 2)) { | |
348 | mon += 12; /* Puts Feb last since it has leap day */ | |
753be622 TG |
349 | year -= 1; |
350 | } | |
351 | ||
352 | return ((((unsigned long) | |
353 | (year/4 - year/100 + year/400 + 367*mon/12 + day) + | |
354 | year*365 - 719499 | |
355 | )*24 + hour /* now have hours */ | |
356 | )*60 + min /* now have minutes */ | |
357 | )*60 + sec; /* finally seconds */ | |
358 | } | |
359 | ||
199e7056 AM |
360 | EXPORT_SYMBOL(mktime); |
361 | ||
753be622 TG |
362 | /** |
363 | * set_normalized_timespec - set timespec sec and nsec parts and normalize | |
364 | * | |
365 | * @ts: pointer to timespec variable to be set | |
366 | * @sec: seconds to set | |
367 | * @nsec: nanoseconds to set | |
368 | * | |
369 | * Set seconds and nanoseconds field of a timespec variable and | |
370 | * normalize to the timespec storage format | |
371 | * | |
372 | * Note: The tv_nsec part is always in the range of | |
373 | * 0 <= tv_nsec < NSEC_PER_SEC | |
374 | * For negative values only the tv_sec field is negative ! | |
375 | */ | |
f4818900 | 376 | void set_normalized_timespec(struct timespec *ts, time_t sec, long nsec) |
753be622 TG |
377 | { |
378 | while (nsec >= NSEC_PER_SEC) { | |
379 | nsec -= NSEC_PER_SEC; | |
380 | ++sec; | |
381 | } | |
382 | while (nsec < 0) { | |
383 | nsec += NSEC_PER_SEC; | |
384 | --sec; | |
385 | } | |
386 | ts->tv_sec = sec; | |
387 | ts->tv_nsec = nsec; | |
388 | } | |
389 | ||
f8f46da3 TG |
390 | /** |
391 | * ns_to_timespec - Convert nanoseconds to timespec | |
392 | * @nsec: the nanoseconds value to be converted | |
393 | * | |
394 | * Returns the timespec representation of the nsec parameter. | |
395 | */ | |
df869b63 | 396 | struct timespec ns_to_timespec(const s64 nsec) |
f8f46da3 TG |
397 | { |
398 | struct timespec ts; | |
399 | ||
88fc3897 GA |
400 | if (!nsec) |
401 | return (struct timespec) {0, 0}; | |
402 | ||
403 | ts.tv_sec = div_long_long_rem_signed(nsec, NSEC_PER_SEC, &ts.tv_nsec); | |
404 | if (unlikely(nsec < 0)) | |
405 | set_normalized_timespec(&ts, ts.tv_sec, ts.tv_nsec); | |
f8f46da3 TG |
406 | |
407 | return ts; | |
408 | } | |
85795d64 | 409 | EXPORT_SYMBOL(ns_to_timespec); |
f8f46da3 TG |
410 | |
411 | /** | |
412 | * ns_to_timeval - Convert nanoseconds to timeval | |
413 | * @nsec: the nanoseconds value to be converted | |
414 | * | |
415 | * Returns the timeval representation of the nsec parameter. | |
416 | */ | |
df869b63 | 417 | struct timeval ns_to_timeval(const s64 nsec) |
f8f46da3 TG |
418 | { |
419 | struct timespec ts = ns_to_timespec(nsec); | |
420 | struct timeval tv; | |
421 | ||
422 | tv.tv_sec = ts.tv_sec; | |
423 | tv.tv_usec = (suseconds_t) ts.tv_nsec / 1000; | |
424 | ||
425 | return tv; | |
426 | } | |
b7aa0bf7 | 427 | EXPORT_SYMBOL(ns_to_timeval); |
f8f46da3 | 428 | |
41cf5445 IM |
429 | /* |
430 | * When we convert to jiffies then we interpret incoming values | |
431 | * the following way: | |
432 | * | |
433 | * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET) | |
434 | * | |
435 | * - 'too large' values [that would result in larger than | |
436 | * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too. | |
437 | * | |
438 | * - all other values are converted to jiffies by either multiplying | |
439 | * the input value by a factor or dividing it with a factor | |
440 | * | |
441 | * We must also be careful about 32-bit overflows. | |
442 | */ | |
8b9365d7 IM |
443 | unsigned long msecs_to_jiffies(const unsigned int m) |
444 | { | |
41cf5445 IM |
445 | /* |
446 | * Negative value, means infinite timeout: | |
447 | */ | |
448 | if ((int)m < 0) | |
8b9365d7 | 449 | return MAX_JIFFY_OFFSET; |
41cf5445 | 450 | |
8b9365d7 | 451 | #if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ) |
41cf5445 IM |
452 | /* |
453 | * HZ is equal to or smaller than 1000, and 1000 is a nice | |
454 | * round multiple of HZ, divide with the factor between them, | |
455 | * but round upwards: | |
456 | */ | |
8b9365d7 IM |
457 | return (m + (MSEC_PER_SEC / HZ) - 1) / (MSEC_PER_SEC / HZ); |
458 | #elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC) | |
41cf5445 IM |
459 | /* |
460 | * HZ is larger than 1000, and HZ is a nice round multiple of | |
461 | * 1000 - simply multiply with the factor between them. | |
462 | * | |
463 | * But first make sure the multiplication result cannot | |
464 | * overflow: | |
465 | */ | |
466 | if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET)) | |
467 | return MAX_JIFFY_OFFSET; | |
468 | ||
8b9365d7 IM |
469 | return m * (HZ / MSEC_PER_SEC); |
470 | #else | |
41cf5445 IM |
471 | /* |
472 | * Generic case - multiply, round and divide. But first | |
473 | * check that if we are doing a net multiplication, that | |
474 | * we wouldnt overflow: | |
475 | */ | |
476 | if (HZ > MSEC_PER_SEC && m > jiffies_to_msecs(MAX_JIFFY_OFFSET)) | |
477 | return MAX_JIFFY_OFFSET; | |
478 | ||
8b9365d7 IM |
479 | return (m * HZ + MSEC_PER_SEC - 1) / MSEC_PER_SEC; |
480 | #endif | |
481 | } | |
482 | EXPORT_SYMBOL(msecs_to_jiffies); | |
483 | ||
484 | unsigned long usecs_to_jiffies(const unsigned int u) | |
485 | { | |
486 | if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET)) | |
487 | return MAX_JIFFY_OFFSET; | |
488 | #if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ) | |
489 | return (u + (USEC_PER_SEC / HZ) - 1) / (USEC_PER_SEC / HZ); | |
490 | #elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC) | |
491 | return u * (HZ / USEC_PER_SEC); | |
492 | #else | |
493 | return (u * HZ + USEC_PER_SEC - 1) / USEC_PER_SEC; | |
494 | #endif | |
495 | } | |
496 | EXPORT_SYMBOL(usecs_to_jiffies); | |
497 | ||
498 | /* | |
499 | * The TICK_NSEC - 1 rounds up the value to the next resolution. Note | |
500 | * that a remainder subtract here would not do the right thing as the | |
501 | * resolution values don't fall on second boundries. I.e. the line: | |
502 | * nsec -= nsec % TICK_NSEC; is NOT a correct resolution rounding. | |
503 | * | |
504 | * Rather, we just shift the bits off the right. | |
505 | * | |
506 | * The >> (NSEC_JIFFIE_SC - SEC_JIFFIE_SC) converts the scaled nsec | |
507 | * value to a scaled second value. | |
508 | */ | |
509 | unsigned long | |
510 | timespec_to_jiffies(const struct timespec *value) | |
511 | { | |
512 | unsigned long sec = value->tv_sec; | |
513 | long nsec = value->tv_nsec + TICK_NSEC - 1; | |
514 | ||
515 | if (sec >= MAX_SEC_IN_JIFFIES){ | |
516 | sec = MAX_SEC_IN_JIFFIES; | |
517 | nsec = 0; | |
518 | } | |
519 | return (((u64)sec * SEC_CONVERSION) + | |
520 | (((u64)nsec * NSEC_CONVERSION) >> | |
521 | (NSEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC; | |
522 | ||
523 | } | |
524 | EXPORT_SYMBOL(timespec_to_jiffies); | |
525 | ||
526 | void | |
527 | jiffies_to_timespec(const unsigned long jiffies, struct timespec *value) | |
528 | { | |
529 | /* | |
530 | * Convert jiffies to nanoseconds and separate with | |
531 | * one divide. | |
532 | */ | |
533 | u64 nsec = (u64)jiffies * TICK_NSEC; | |
534 | value->tv_sec = div_long_long_rem(nsec, NSEC_PER_SEC, &value->tv_nsec); | |
535 | } | |
536 | EXPORT_SYMBOL(jiffies_to_timespec); | |
537 | ||
538 | /* Same for "timeval" | |
539 | * | |
540 | * Well, almost. The problem here is that the real system resolution is | |
541 | * in nanoseconds and the value being converted is in micro seconds. | |
542 | * Also for some machines (those that use HZ = 1024, in-particular), | |
543 | * there is a LARGE error in the tick size in microseconds. | |
544 | ||
545 | * The solution we use is to do the rounding AFTER we convert the | |
546 | * microsecond part. Thus the USEC_ROUND, the bits to be shifted off. | |
547 | * Instruction wise, this should cost only an additional add with carry | |
548 | * instruction above the way it was done above. | |
549 | */ | |
550 | unsigned long | |
551 | timeval_to_jiffies(const struct timeval *value) | |
552 | { | |
553 | unsigned long sec = value->tv_sec; | |
554 | long usec = value->tv_usec; | |
555 | ||
556 | if (sec >= MAX_SEC_IN_JIFFIES){ | |
557 | sec = MAX_SEC_IN_JIFFIES; | |
558 | usec = 0; | |
559 | } | |
560 | return (((u64)sec * SEC_CONVERSION) + | |
561 | (((u64)usec * USEC_CONVERSION + USEC_ROUND) >> | |
562 | (USEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC; | |
563 | } | |
456a09dc | 564 | EXPORT_SYMBOL(timeval_to_jiffies); |
8b9365d7 IM |
565 | |
566 | void jiffies_to_timeval(const unsigned long jiffies, struct timeval *value) | |
567 | { | |
568 | /* | |
569 | * Convert jiffies to nanoseconds and separate with | |
570 | * one divide. | |
571 | */ | |
572 | u64 nsec = (u64)jiffies * TICK_NSEC; | |
573 | long tv_usec; | |
574 | ||
575 | value->tv_sec = div_long_long_rem(nsec, NSEC_PER_SEC, &tv_usec); | |
576 | tv_usec /= NSEC_PER_USEC; | |
577 | value->tv_usec = tv_usec; | |
578 | } | |
456a09dc | 579 | EXPORT_SYMBOL(jiffies_to_timeval); |
8b9365d7 IM |
580 | |
581 | /* | |
582 | * Convert jiffies/jiffies_64 to clock_t and back. | |
583 | */ | |
584 | clock_t jiffies_to_clock_t(long x) | |
585 | { | |
586 | #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0 | |
587 | return x / (HZ / USER_HZ); | |
588 | #else | |
589 | u64 tmp = (u64)x * TICK_NSEC; | |
590 | do_div(tmp, (NSEC_PER_SEC / USER_HZ)); | |
591 | return (long)tmp; | |
592 | #endif | |
593 | } | |
594 | EXPORT_SYMBOL(jiffies_to_clock_t); | |
595 | ||
596 | unsigned long clock_t_to_jiffies(unsigned long x) | |
597 | { | |
598 | #if (HZ % USER_HZ)==0 | |
599 | if (x >= ~0UL / (HZ / USER_HZ)) | |
600 | return ~0UL; | |
601 | return x * (HZ / USER_HZ); | |
602 | #else | |
603 | u64 jif; | |
604 | ||
605 | /* Don't worry about loss of precision here .. */ | |
606 | if (x >= ~0UL / HZ * USER_HZ) | |
607 | return ~0UL; | |
608 | ||
609 | /* .. but do try to contain it here */ | |
610 | jif = x * (u64) HZ; | |
611 | do_div(jif, USER_HZ); | |
612 | return jif; | |
613 | #endif | |
614 | } | |
615 | EXPORT_SYMBOL(clock_t_to_jiffies); | |
616 | ||
617 | u64 jiffies_64_to_clock_t(u64 x) | |
618 | { | |
619 | #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0 | |
620 | do_div(x, HZ / USER_HZ); | |
621 | #else | |
622 | /* | |
623 | * There are better ways that don't overflow early, | |
624 | * but even this doesn't overflow in hundreds of years | |
625 | * in 64 bits, so.. | |
626 | */ | |
627 | x *= TICK_NSEC; | |
628 | do_div(x, (NSEC_PER_SEC / USER_HZ)); | |
629 | #endif | |
630 | return x; | |
631 | } | |
632 | ||
633 | EXPORT_SYMBOL(jiffies_64_to_clock_t); | |
634 | ||
635 | u64 nsec_to_clock_t(u64 x) | |
636 | { | |
637 | #if (NSEC_PER_SEC % USER_HZ) == 0 | |
638 | do_div(x, (NSEC_PER_SEC / USER_HZ)); | |
639 | #elif (USER_HZ % 512) == 0 | |
640 | x *= USER_HZ/512; | |
641 | do_div(x, (NSEC_PER_SEC / 512)); | |
642 | #else | |
643 | /* | |
644 | * max relative error 5.7e-8 (1.8s per year) for USER_HZ <= 1024, | |
645 | * overflow after 64.99 years. | |
646 | * exact for HZ=60, 72, 90, 120, 144, 180, 300, 600, 900, ... | |
647 | */ | |
648 | x *= 9; | |
649 | do_div(x, (unsigned long)((9ull * NSEC_PER_SEC + (USER_HZ/2)) / | |
650 | USER_HZ)); | |
651 | #endif | |
652 | return x; | |
653 | } | |
654 | ||
1da177e4 LT |
655 | #if (BITS_PER_LONG < 64) |
656 | u64 get_jiffies_64(void) | |
657 | { | |
658 | unsigned long seq; | |
659 | u64 ret; | |
660 | ||
661 | do { | |
662 | seq = read_seqbegin(&xtime_lock); | |
663 | ret = jiffies_64; | |
664 | } while (read_seqretry(&xtime_lock, seq)); | |
665 | return ret; | |
666 | } | |
667 | ||
668 | EXPORT_SYMBOL(get_jiffies_64); | |
669 | #endif | |
670 | ||
671 | EXPORT_SYMBOL(jiffies); |