Commit | Line | Data |
---|---|---|
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 | |
6fa6c3b1 | 12 | * |
1da177e4 | 13 | * 1993-09-02 Philip Gladstone |
0a0fca9d | 14 | * Created file with time related functions from sched/core.c and adjtimex() |
1da177e4 LT |
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 | ||
9984de1a | 30 | #include <linux/export.h> |
1da177e4 | 31 | #include <linux/timex.h> |
c59ede7b | 32 | #include <linux/capability.h> |
189374ae | 33 | #include <linux/timekeeper_internal.h> |
1da177e4 | 34 | #include <linux/errno.h> |
1da177e4 LT |
35 | #include <linux/syscalls.h> |
36 | #include <linux/security.h> | |
37 | #include <linux/fs.h> | |
71abb3af | 38 | #include <linux/math64.h> |
e3d5a27d | 39 | #include <linux/ptrace.h> |
1da177e4 LT |
40 | |
41 | #include <asm/uaccess.h> | |
42 | #include <asm/unistd.h> | |
43 | ||
bdc80787 | 44 | #include "timeconst.h" |
8b094cd0 | 45 | #include "timekeeping.h" |
bdc80787 | 46 | |
6fa6c3b1 | 47 | /* |
1da177e4 LT |
48 | * The timezone where the local system is located. Used as a default by some |
49 | * programs who obtain this value by using gettimeofday. | |
50 | */ | |
51 | struct timezone sys_tz; | |
52 | ||
53 | EXPORT_SYMBOL(sys_tz); | |
54 | ||
55 | #ifdef __ARCH_WANT_SYS_TIME | |
56 | ||
57 | /* | |
58 | * sys_time() can be implemented in user-level using | |
59 | * sys_gettimeofday(). Is this for backwards compatibility? If so, | |
60 | * why not move it into the appropriate arch directory (for those | |
61 | * architectures that need it). | |
62 | */ | |
58fd3aa2 | 63 | SYSCALL_DEFINE1(time, time_t __user *, tloc) |
1da177e4 | 64 | { |
f20bf612 | 65 | time_t i = get_seconds(); |
1da177e4 LT |
66 | |
67 | if (tloc) { | |
20082208 | 68 | if (put_user(i,tloc)) |
e3d5a27d | 69 | return -EFAULT; |
1da177e4 | 70 | } |
e3d5a27d | 71 | force_successful_syscall_return(); |
1da177e4 LT |
72 | return i; |
73 | } | |
74 | ||
75 | /* | |
76 | * sys_stime() can be implemented in user-level using | |
77 | * sys_settimeofday(). Is this for backwards compatibility? If so, | |
78 | * why not move it into the appropriate arch directory (for those | |
79 | * architectures that need it). | |
80 | */ | |
6fa6c3b1 | 81 | |
58fd3aa2 | 82 | SYSCALL_DEFINE1(stime, time_t __user *, tptr) |
1da177e4 LT |
83 | { |
84 | struct timespec tv; | |
85 | int err; | |
86 | ||
87 | if (get_user(tv.tv_sec, tptr)) | |
88 | return -EFAULT; | |
89 | ||
90 | tv.tv_nsec = 0; | |
91 | ||
92 | err = security_settime(&tv, NULL); | |
93 | if (err) | |
94 | return err; | |
95 | ||
96 | do_settimeofday(&tv); | |
97 | return 0; | |
98 | } | |
99 | ||
100 | #endif /* __ARCH_WANT_SYS_TIME */ | |
101 | ||
58fd3aa2 HC |
102 | SYSCALL_DEFINE2(gettimeofday, struct timeval __user *, tv, |
103 | struct timezone __user *, tz) | |
1da177e4 LT |
104 | { |
105 | if (likely(tv != NULL)) { | |
106 | struct timeval ktv; | |
107 | do_gettimeofday(&ktv); | |
108 | if (copy_to_user(tv, &ktv, sizeof(ktv))) | |
109 | return -EFAULT; | |
110 | } | |
111 | if (unlikely(tz != NULL)) { | |
112 | if (copy_to_user(tz, &sys_tz, sizeof(sys_tz))) | |
113 | return -EFAULT; | |
114 | } | |
115 | return 0; | |
116 | } | |
117 | ||
84e345e4 PB |
118 | /* |
119 | * Indicates if there is an offset between the system clock and the hardware | |
120 | * clock/persistent clock/rtc. | |
121 | */ | |
122 | int persistent_clock_is_local; | |
123 | ||
1da177e4 LT |
124 | /* |
125 | * Adjust the time obtained from the CMOS to be UTC time instead of | |
126 | * local time. | |
6fa6c3b1 | 127 | * |
1da177e4 LT |
128 | * This is ugly, but preferable to the alternatives. Otherwise we |
129 | * would either need to write a program to do it in /etc/rc (and risk | |
6fa6c3b1 | 130 | * confusion if the program gets run more than once; it would also be |
1da177e4 LT |
131 | * hard to make the program warp the clock precisely n hours) or |
132 | * compile in the timezone information into the kernel. Bad, bad.... | |
133 | * | |
bdc80787 | 134 | * - TYT, 1992-01-01 |
1da177e4 LT |
135 | * |
136 | * The best thing to do is to keep the CMOS clock in universal time (UTC) | |
137 | * as real UNIX machines always do it. This avoids all headaches about | |
138 | * daylight saving times and warping kernel clocks. | |
139 | */ | |
77933d72 | 140 | static inline void warp_clock(void) |
1da177e4 | 141 | { |
c30bd099 DZ |
142 | if (sys_tz.tz_minuteswest != 0) { |
143 | struct timespec adjust; | |
bd45b7a3 | 144 | |
84e345e4 | 145 | persistent_clock_is_local = 1; |
7859e404 JS |
146 | adjust.tv_sec = sys_tz.tz_minuteswest * 60; |
147 | adjust.tv_nsec = 0; | |
148 | timekeeping_inject_offset(&adjust); | |
c30bd099 | 149 | } |
1da177e4 LT |
150 | } |
151 | ||
152 | /* | |
153 | * In case for some reason the CMOS clock has not already been running | |
154 | * in UTC, but in some local time: The first time we set the timezone, | |
155 | * we will warp the clock so that it is ticking UTC time instead of | |
156 | * local time. Presumably, if someone is setting the timezone then we | |
157 | * are running in an environment where the programs understand about | |
158 | * timezones. This should be done at boot time in the /etc/rc script, | |
159 | * as soon as possible, so that the clock can be set right. Otherwise, | |
160 | * various programs will get confused when the clock gets warped. | |
161 | */ | |
162 | ||
1e6d7679 | 163 | int do_sys_settimeofday(const struct timespec *tv, const struct timezone *tz) |
1da177e4 LT |
164 | { |
165 | static int firsttime = 1; | |
166 | int error = 0; | |
167 | ||
951069e3 | 168 | if (tv && !timespec_valid(tv)) |
718bcceb TG |
169 | return -EINVAL; |
170 | ||
1da177e4 LT |
171 | error = security_settime(tv, tz); |
172 | if (error) | |
173 | return error; | |
174 | ||
175 | if (tz) { | |
1da177e4 | 176 | sys_tz = *tz; |
2c622148 | 177 | update_vsyscall_tz(); |
1da177e4 LT |
178 | if (firsttime) { |
179 | firsttime = 0; | |
180 | if (!tv) | |
181 | warp_clock(); | |
182 | } | |
183 | } | |
184 | if (tv) | |
1da177e4 | 185 | return do_settimeofday(tv); |
1da177e4 LT |
186 | return 0; |
187 | } | |
188 | ||
58fd3aa2 HC |
189 | SYSCALL_DEFINE2(settimeofday, struct timeval __user *, tv, |
190 | struct timezone __user *, tz) | |
1da177e4 LT |
191 | { |
192 | struct timeval user_tv; | |
193 | struct timespec new_ts; | |
194 | struct timezone new_tz; | |
195 | ||
196 | if (tv) { | |
197 | if (copy_from_user(&user_tv, tv, sizeof(*tv))) | |
198 | return -EFAULT; | |
199 | new_ts.tv_sec = user_tv.tv_sec; | |
200 | new_ts.tv_nsec = user_tv.tv_usec * NSEC_PER_USEC; | |
201 | } | |
202 | if (tz) { | |
203 | if (copy_from_user(&new_tz, tz, sizeof(*tz))) | |
204 | return -EFAULT; | |
205 | } | |
206 | ||
207 | return do_sys_settimeofday(tv ? &new_ts : NULL, tz ? &new_tz : NULL); | |
208 | } | |
209 | ||
58fd3aa2 | 210 | SYSCALL_DEFINE1(adjtimex, struct timex __user *, txc_p) |
1da177e4 LT |
211 | { |
212 | struct timex txc; /* Local copy of parameter */ | |
213 | int ret; | |
214 | ||
215 | /* Copy the user data space into the kernel copy | |
216 | * structure. But bear in mind that the structures | |
217 | * may change | |
218 | */ | |
219 | if(copy_from_user(&txc, txc_p, sizeof(struct timex))) | |
220 | return -EFAULT; | |
221 | ret = do_adjtimex(&txc); | |
222 | return copy_to_user(txc_p, &txc, sizeof(struct timex)) ? -EFAULT : ret; | |
223 | } | |
224 | ||
1da177e4 LT |
225 | /** |
226 | * current_fs_time - Return FS time | |
227 | * @sb: Superblock. | |
228 | * | |
8ba8e95e | 229 | * Return the current time truncated to the time granularity supported by |
1da177e4 LT |
230 | * the fs. |
231 | */ | |
232 | struct timespec current_fs_time(struct super_block *sb) | |
233 | { | |
234 | struct timespec now = current_kernel_time(); | |
235 | return timespec_trunc(now, sb->s_time_gran); | |
236 | } | |
237 | EXPORT_SYMBOL(current_fs_time); | |
238 | ||
753e9c5c ED |
239 | /* |
240 | * Convert jiffies to milliseconds and back. | |
241 | * | |
242 | * Avoid unnecessary multiplications/divisions in the | |
243 | * two most common HZ cases: | |
244 | */ | |
af3b5628 | 245 | unsigned int jiffies_to_msecs(const unsigned long j) |
753e9c5c ED |
246 | { |
247 | #if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ) | |
248 | return (MSEC_PER_SEC / HZ) * j; | |
249 | #elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC) | |
250 | return (j + (HZ / MSEC_PER_SEC) - 1)/(HZ / MSEC_PER_SEC); | |
251 | #else | |
bdc80787 | 252 | # if BITS_PER_LONG == 32 |
b9095fd8 | 253 | return (HZ_TO_MSEC_MUL32 * j) >> HZ_TO_MSEC_SHR32; |
bdc80787 PA |
254 | # else |
255 | return (j * HZ_TO_MSEC_NUM) / HZ_TO_MSEC_DEN; | |
256 | # endif | |
753e9c5c ED |
257 | #endif |
258 | } | |
259 | EXPORT_SYMBOL(jiffies_to_msecs); | |
260 | ||
af3b5628 | 261 | unsigned int jiffies_to_usecs(const unsigned long j) |
753e9c5c ED |
262 | { |
263 | #if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ) | |
264 | return (USEC_PER_SEC / HZ) * j; | |
265 | #elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC) | |
266 | return (j + (HZ / USEC_PER_SEC) - 1)/(HZ / USEC_PER_SEC); | |
267 | #else | |
bdc80787 | 268 | # if BITS_PER_LONG == 32 |
b9095fd8 | 269 | return (HZ_TO_USEC_MUL32 * j) >> HZ_TO_USEC_SHR32; |
bdc80787 PA |
270 | # else |
271 | return (j * HZ_TO_USEC_NUM) / HZ_TO_USEC_DEN; | |
272 | # endif | |
753e9c5c ED |
273 | #endif |
274 | } | |
275 | EXPORT_SYMBOL(jiffies_to_usecs); | |
276 | ||
1da177e4 | 277 | /** |
8ba8e95e | 278 | * timespec_trunc - Truncate timespec to a granularity |
1da177e4 | 279 | * @t: Timespec |
8ba8e95e | 280 | * @gran: Granularity in ns. |
1da177e4 | 281 | * |
8ba8e95e | 282 | * Truncate a timespec to a granularity. gran must be smaller than a second. |
1da177e4 LT |
283 | * Always rounds down. |
284 | * | |
285 | * This function should be only used for timestamps returned by | |
286 | * current_kernel_time() or CURRENT_TIME, not with do_gettimeofday() because | |
3eb05676 | 287 | * it doesn't handle the better resolution of the latter. |
1da177e4 LT |
288 | */ |
289 | struct timespec timespec_trunc(struct timespec t, unsigned gran) | |
290 | { | |
291 | /* | |
292 | * Division is pretty slow so avoid it for common cases. | |
293 | * Currently current_kernel_time() never returns better than | |
294 | * jiffies resolution. Exploit that. | |
295 | */ | |
296 | if (gran <= jiffies_to_usecs(1) * 1000) { | |
297 | /* nothing */ | |
298 | } else if (gran == 1000000000) { | |
299 | t.tv_nsec = 0; | |
300 | } else { | |
301 | t.tv_nsec -= t.tv_nsec % gran; | |
302 | } | |
303 | return t; | |
304 | } | |
305 | EXPORT_SYMBOL(timespec_trunc); | |
306 | ||
753be622 TG |
307 | /* Converts Gregorian date to seconds since 1970-01-01 00:00:00. |
308 | * Assumes input in normal date format, i.e. 1980-12-31 23:59:59 | |
309 | * => year=1980, mon=12, day=31, hour=23, min=59, sec=59. | |
310 | * | |
311 | * [For the Julian calendar (which was used in Russia before 1917, | |
312 | * Britain & colonies before 1752, anywhere else before 1582, | |
313 | * and is still in use by some communities) leave out the | |
314 | * -year/100+year/400 terms, and add 10.] | |
315 | * | |
316 | * This algorithm was first published by Gauss (I think). | |
317 | * | |
318 | * WARNING: this function will overflow on 2106-02-07 06:28:16 on | |
3eb05676 | 319 | * machines where long is 32-bit! (However, as time_t is signed, we |
753be622 TG |
320 | * will already get problems at other places on 2038-01-19 03:14:08) |
321 | */ | |
322 | unsigned long | |
f4818900 IM |
323 | mktime(const unsigned int year0, const unsigned int mon0, |
324 | const unsigned int day, const unsigned int hour, | |
325 | const unsigned int min, const unsigned int sec) | |
753be622 | 326 | { |
f4818900 IM |
327 | unsigned int mon = mon0, year = year0; |
328 | ||
329 | /* 1..12 -> 11,12,1..10 */ | |
330 | if (0 >= (int) (mon -= 2)) { | |
331 | mon += 12; /* Puts Feb last since it has leap day */ | |
753be622 TG |
332 | year -= 1; |
333 | } | |
334 | ||
335 | return ((((unsigned long) | |
336 | (year/4 - year/100 + year/400 + 367*mon/12 + day) + | |
337 | year*365 - 719499 | |
338 | )*24 + hour /* now have hours */ | |
339 | )*60 + min /* now have minutes */ | |
340 | )*60 + sec; /* finally seconds */ | |
341 | } | |
342 | ||
199e7056 AM |
343 | EXPORT_SYMBOL(mktime); |
344 | ||
753be622 TG |
345 | /** |
346 | * set_normalized_timespec - set timespec sec and nsec parts and normalize | |
347 | * | |
348 | * @ts: pointer to timespec variable to be set | |
349 | * @sec: seconds to set | |
350 | * @nsec: nanoseconds to set | |
351 | * | |
352 | * Set seconds and nanoseconds field of a timespec variable and | |
353 | * normalize to the timespec storage format | |
354 | * | |
355 | * Note: The tv_nsec part is always in the range of | |
bdc80787 | 356 | * 0 <= tv_nsec < NSEC_PER_SEC |
753be622 TG |
357 | * For negative values only the tv_sec field is negative ! |
358 | */ | |
12e09337 | 359 | void set_normalized_timespec(struct timespec *ts, time_t sec, s64 nsec) |
753be622 TG |
360 | { |
361 | while (nsec >= NSEC_PER_SEC) { | |
12e09337 TG |
362 | /* |
363 | * The following asm() prevents the compiler from | |
364 | * optimising this loop into a modulo operation. See | |
365 | * also __iter_div_u64_rem() in include/linux/time.h | |
366 | */ | |
367 | asm("" : "+rm"(nsec)); | |
753be622 TG |
368 | nsec -= NSEC_PER_SEC; |
369 | ++sec; | |
370 | } | |
371 | while (nsec < 0) { | |
12e09337 | 372 | asm("" : "+rm"(nsec)); |
753be622 TG |
373 | nsec += NSEC_PER_SEC; |
374 | --sec; | |
375 | } | |
376 | ts->tv_sec = sec; | |
377 | ts->tv_nsec = nsec; | |
378 | } | |
7c3f944e | 379 | EXPORT_SYMBOL(set_normalized_timespec); |
753be622 | 380 | |
f8f46da3 TG |
381 | /** |
382 | * ns_to_timespec - Convert nanoseconds to timespec | |
383 | * @nsec: the nanoseconds value to be converted | |
384 | * | |
385 | * Returns the timespec representation of the nsec parameter. | |
386 | */ | |
df869b63 | 387 | struct timespec ns_to_timespec(const s64 nsec) |
f8f46da3 TG |
388 | { |
389 | struct timespec ts; | |
f8bd2258 | 390 | s32 rem; |
f8f46da3 | 391 | |
88fc3897 GA |
392 | if (!nsec) |
393 | return (struct timespec) {0, 0}; | |
394 | ||
f8bd2258 RZ |
395 | ts.tv_sec = div_s64_rem(nsec, NSEC_PER_SEC, &rem); |
396 | if (unlikely(rem < 0)) { | |
397 | ts.tv_sec--; | |
398 | rem += NSEC_PER_SEC; | |
399 | } | |
400 | ts.tv_nsec = rem; | |
f8f46da3 TG |
401 | |
402 | return ts; | |
403 | } | |
85795d64 | 404 | EXPORT_SYMBOL(ns_to_timespec); |
f8f46da3 TG |
405 | |
406 | /** | |
407 | * ns_to_timeval - Convert nanoseconds to timeval | |
408 | * @nsec: the nanoseconds value to be converted | |
409 | * | |
410 | * Returns the timeval representation of the nsec parameter. | |
411 | */ | |
df869b63 | 412 | struct timeval ns_to_timeval(const s64 nsec) |
f8f46da3 TG |
413 | { |
414 | struct timespec ts = ns_to_timespec(nsec); | |
415 | struct timeval tv; | |
416 | ||
417 | tv.tv_sec = ts.tv_sec; | |
418 | tv.tv_usec = (suseconds_t) ts.tv_nsec / 1000; | |
419 | ||
420 | return tv; | |
421 | } | |
b7aa0bf7 | 422 | EXPORT_SYMBOL(ns_to_timeval); |
f8f46da3 | 423 | |
49cd6f86 JS |
424 | #if BITS_PER_LONG == 32 |
425 | /** | |
426 | * set_normalized_timespec - set timespec sec and nsec parts and normalize | |
427 | * | |
428 | * @ts: pointer to timespec variable to be set | |
429 | * @sec: seconds to set | |
430 | * @nsec: nanoseconds to set | |
431 | * | |
432 | * Set seconds and nanoseconds field of a timespec variable and | |
433 | * normalize to the timespec storage format | |
434 | * | |
435 | * Note: The tv_nsec part is always in the range of | |
436 | * 0 <= tv_nsec < NSEC_PER_SEC | |
437 | * For negative values only the tv_sec field is negative ! | |
438 | */ | |
439 | void set_normalized_timespec64(struct timespec64 *ts, time64_t sec, s64 nsec) | |
440 | { | |
441 | while (nsec >= NSEC_PER_SEC) { | |
442 | /* | |
443 | * The following asm() prevents the compiler from | |
444 | * optimising this loop into a modulo operation. See | |
445 | * also __iter_div_u64_rem() in include/linux/time.h | |
446 | */ | |
447 | asm("" : "+rm"(nsec)); | |
448 | nsec -= NSEC_PER_SEC; | |
449 | ++sec; | |
450 | } | |
451 | while (nsec < 0) { | |
452 | asm("" : "+rm"(nsec)); | |
453 | nsec += NSEC_PER_SEC; | |
454 | --sec; | |
455 | } | |
456 | ts->tv_sec = sec; | |
457 | ts->tv_nsec = nsec; | |
458 | } | |
459 | EXPORT_SYMBOL(set_normalized_timespec64); | |
460 | ||
461 | /** | |
462 | * ns_to_timespec64 - Convert nanoseconds to timespec64 | |
463 | * @nsec: the nanoseconds value to be converted | |
464 | * | |
465 | * Returns the timespec64 representation of the nsec parameter. | |
466 | */ | |
467 | struct timespec64 ns_to_timespec64(const s64 nsec) | |
468 | { | |
469 | struct timespec64 ts; | |
470 | s32 rem; | |
471 | ||
472 | if (!nsec) | |
473 | return (struct timespec64) {0, 0}; | |
474 | ||
475 | ts.tv_sec = div_s64_rem(nsec, NSEC_PER_SEC, &rem); | |
476 | if (unlikely(rem < 0)) { | |
477 | ts.tv_sec--; | |
478 | rem += NSEC_PER_SEC; | |
479 | } | |
480 | ts.tv_nsec = rem; | |
481 | ||
482 | return ts; | |
483 | } | |
484 | EXPORT_SYMBOL(ns_to_timespec64); | |
485 | #endif | |
41cf5445 IM |
486 | /* |
487 | * When we convert to jiffies then we interpret incoming values | |
488 | * the following way: | |
489 | * | |
490 | * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET) | |
491 | * | |
492 | * - 'too large' values [that would result in larger than | |
493 | * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too. | |
494 | * | |
495 | * - all other values are converted to jiffies by either multiplying | |
496 | * the input value by a factor or dividing it with a factor | |
497 | * | |
498 | * We must also be careful about 32-bit overflows. | |
499 | */ | |
8b9365d7 IM |
500 | unsigned long msecs_to_jiffies(const unsigned int m) |
501 | { | |
41cf5445 IM |
502 | /* |
503 | * Negative value, means infinite timeout: | |
504 | */ | |
505 | if ((int)m < 0) | |
8b9365d7 | 506 | return MAX_JIFFY_OFFSET; |
41cf5445 | 507 | |
8b9365d7 | 508 | #if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ) |
41cf5445 IM |
509 | /* |
510 | * HZ is equal to or smaller than 1000, and 1000 is a nice | |
511 | * round multiple of HZ, divide with the factor between them, | |
512 | * but round upwards: | |
513 | */ | |
8b9365d7 IM |
514 | return (m + (MSEC_PER_SEC / HZ) - 1) / (MSEC_PER_SEC / HZ); |
515 | #elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC) | |
41cf5445 IM |
516 | /* |
517 | * HZ is larger than 1000, and HZ is a nice round multiple of | |
518 | * 1000 - simply multiply with the factor between them. | |
519 | * | |
520 | * But first make sure the multiplication result cannot | |
521 | * overflow: | |
522 | */ | |
523 | if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET)) | |
524 | return MAX_JIFFY_OFFSET; | |
525 | ||
8b9365d7 IM |
526 | return m * (HZ / MSEC_PER_SEC); |
527 | #else | |
41cf5445 IM |
528 | /* |
529 | * Generic case - multiply, round and divide. But first | |
530 | * check that if we are doing a net multiplication, that | |
bdc80787 | 531 | * we wouldn't overflow: |
41cf5445 IM |
532 | */ |
533 | if (HZ > MSEC_PER_SEC && m > jiffies_to_msecs(MAX_JIFFY_OFFSET)) | |
534 | return MAX_JIFFY_OFFSET; | |
535 | ||
b9095fd8 | 536 | return (MSEC_TO_HZ_MUL32 * m + MSEC_TO_HZ_ADJ32) |
bdc80787 | 537 | >> MSEC_TO_HZ_SHR32; |
8b9365d7 IM |
538 | #endif |
539 | } | |
540 | EXPORT_SYMBOL(msecs_to_jiffies); | |
541 | ||
542 | unsigned long usecs_to_jiffies(const unsigned int u) | |
543 | { | |
544 | if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET)) | |
545 | return MAX_JIFFY_OFFSET; | |
546 | #if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ) | |
547 | return (u + (USEC_PER_SEC / HZ) - 1) / (USEC_PER_SEC / HZ); | |
548 | #elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC) | |
549 | return u * (HZ / USEC_PER_SEC); | |
550 | #else | |
b9095fd8 | 551 | return (USEC_TO_HZ_MUL32 * u + USEC_TO_HZ_ADJ32) |
bdc80787 | 552 | >> USEC_TO_HZ_SHR32; |
8b9365d7 IM |
553 | #endif |
554 | } | |
555 | EXPORT_SYMBOL(usecs_to_jiffies); | |
556 | ||
557 | /* | |
558 | * The TICK_NSEC - 1 rounds up the value to the next resolution. Note | |
559 | * that a remainder subtract here would not do the right thing as the | |
560 | * resolution values don't fall on second boundries. I.e. the line: | |
561 | * nsec -= nsec % TICK_NSEC; is NOT a correct resolution rounding. | |
562 | * | |
563 | * Rather, we just shift the bits off the right. | |
564 | * | |
565 | * The >> (NSEC_JIFFIE_SC - SEC_JIFFIE_SC) converts the scaled nsec | |
566 | * value to a scaled second value. | |
567 | */ | |
568 | unsigned long | |
569 | timespec_to_jiffies(const struct timespec *value) | |
570 | { | |
571 | unsigned long sec = value->tv_sec; | |
572 | long nsec = value->tv_nsec + TICK_NSEC - 1; | |
573 | ||
574 | if (sec >= MAX_SEC_IN_JIFFIES){ | |
575 | sec = MAX_SEC_IN_JIFFIES; | |
576 | nsec = 0; | |
577 | } | |
578 | return (((u64)sec * SEC_CONVERSION) + | |
579 | (((u64)nsec * NSEC_CONVERSION) >> | |
580 | (NSEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC; | |
581 | ||
582 | } | |
583 | EXPORT_SYMBOL(timespec_to_jiffies); | |
584 | ||
585 | void | |
586 | jiffies_to_timespec(const unsigned long jiffies, struct timespec *value) | |
587 | { | |
588 | /* | |
589 | * Convert jiffies to nanoseconds and separate with | |
590 | * one divide. | |
591 | */ | |
f8bd2258 RZ |
592 | u32 rem; |
593 | value->tv_sec = div_u64_rem((u64)jiffies * TICK_NSEC, | |
594 | NSEC_PER_SEC, &rem); | |
595 | value->tv_nsec = rem; | |
8b9365d7 IM |
596 | } |
597 | EXPORT_SYMBOL(jiffies_to_timespec); | |
598 | ||
599 | /* Same for "timeval" | |
600 | * | |
601 | * Well, almost. The problem here is that the real system resolution is | |
602 | * in nanoseconds and the value being converted is in micro seconds. | |
603 | * Also for some machines (those that use HZ = 1024, in-particular), | |
604 | * there is a LARGE error in the tick size in microseconds. | |
605 | ||
606 | * The solution we use is to do the rounding AFTER we convert the | |
607 | * microsecond part. Thus the USEC_ROUND, the bits to be shifted off. | |
608 | * Instruction wise, this should cost only an additional add with carry | |
609 | * instruction above the way it was done above. | |
610 | */ | |
611 | unsigned long | |
612 | timeval_to_jiffies(const struct timeval *value) | |
613 | { | |
614 | unsigned long sec = value->tv_sec; | |
615 | long usec = value->tv_usec; | |
616 | ||
617 | if (sec >= MAX_SEC_IN_JIFFIES){ | |
618 | sec = MAX_SEC_IN_JIFFIES; | |
619 | usec = 0; | |
620 | } | |
621 | return (((u64)sec * SEC_CONVERSION) + | |
622 | (((u64)usec * USEC_CONVERSION + USEC_ROUND) >> | |
623 | (USEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC; | |
624 | } | |
456a09dc | 625 | EXPORT_SYMBOL(timeval_to_jiffies); |
8b9365d7 IM |
626 | |
627 | void jiffies_to_timeval(const unsigned long jiffies, struct timeval *value) | |
628 | { | |
629 | /* | |
630 | * Convert jiffies to nanoseconds and separate with | |
631 | * one divide. | |
632 | */ | |
f8bd2258 | 633 | u32 rem; |
8b9365d7 | 634 | |
f8bd2258 RZ |
635 | value->tv_sec = div_u64_rem((u64)jiffies * TICK_NSEC, |
636 | NSEC_PER_SEC, &rem); | |
637 | value->tv_usec = rem / NSEC_PER_USEC; | |
8b9365d7 | 638 | } |
456a09dc | 639 | EXPORT_SYMBOL(jiffies_to_timeval); |
8b9365d7 IM |
640 | |
641 | /* | |
642 | * Convert jiffies/jiffies_64 to clock_t and back. | |
643 | */ | |
cbbc719f | 644 | clock_t jiffies_to_clock_t(unsigned long x) |
8b9365d7 IM |
645 | { |
646 | #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0 | |
6ffc787a DF |
647 | # if HZ < USER_HZ |
648 | return x * (USER_HZ / HZ); | |
649 | # else | |
8b9365d7 | 650 | return x / (HZ / USER_HZ); |
6ffc787a | 651 | # endif |
8b9365d7 | 652 | #else |
71abb3af | 653 | return div_u64((u64)x * TICK_NSEC, NSEC_PER_SEC / USER_HZ); |
8b9365d7 IM |
654 | #endif |
655 | } | |
656 | EXPORT_SYMBOL(jiffies_to_clock_t); | |
657 | ||
658 | unsigned long clock_t_to_jiffies(unsigned long x) | |
659 | { | |
660 | #if (HZ % USER_HZ)==0 | |
661 | if (x >= ~0UL / (HZ / USER_HZ)) | |
662 | return ~0UL; | |
663 | return x * (HZ / USER_HZ); | |
664 | #else | |
8b9365d7 IM |
665 | /* Don't worry about loss of precision here .. */ |
666 | if (x >= ~0UL / HZ * USER_HZ) | |
667 | return ~0UL; | |
668 | ||
669 | /* .. but do try to contain it here */ | |
71abb3af | 670 | return div_u64((u64)x * HZ, USER_HZ); |
8b9365d7 IM |
671 | #endif |
672 | } | |
673 | EXPORT_SYMBOL(clock_t_to_jiffies); | |
674 | ||
675 | u64 jiffies_64_to_clock_t(u64 x) | |
676 | { | |
677 | #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0 | |
6ffc787a | 678 | # if HZ < USER_HZ |
71abb3af | 679 | x = div_u64(x * USER_HZ, HZ); |
ec03d707 | 680 | # elif HZ > USER_HZ |
71abb3af | 681 | x = div_u64(x, HZ / USER_HZ); |
ec03d707 AM |
682 | # else |
683 | /* Nothing to do */ | |
6ffc787a | 684 | # endif |
8b9365d7 IM |
685 | #else |
686 | /* | |
687 | * There are better ways that don't overflow early, | |
688 | * but even this doesn't overflow in hundreds of years | |
689 | * in 64 bits, so.. | |
690 | */ | |
71abb3af | 691 | x = div_u64(x * TICK_NSEC, (NSEC_PER_SEC / USER_HZ)); |
8b9365d7 IM |
692 | #endif |
693 | return x; | |
694 | } | |
8b9365d7 IM |
695 | EXPORT_SYMBOL(jiffies_64_to_clock_t); |
696 | ||
697 | u64 nsec_to_clock_t(u64 x) | |
698 | { | |
699 | #if (NSEC_PER_SEC % USER_HZ) == 0 | |
71abb3af | 700 | return div_u64(x, NSEC_PER_SEC / USER_HZ); |
8b9365d7 | 701 | #elif (USER_HZ % 512) == 0 |
71abb3af | 702 | return div_u64(x * USER_HZ / 512, NSEC_PER_SEC / 512); |
8b9365d7 IM |
703 | #else |
704 | /* | |
705 | * max relative error 5.7e-8 (1.8s per year) for USER_HZ <= 1024, | |
706 | * overflow after 64.99 years. | |
707 | * exact for HZ=60, 72, 90, 120, 144, 180, 300, 600, 900, ... | |
708 | */ | |
71abb3af | 709 | return div_u64(x * 9, (9ull * NSEC_PER_SEC + (USER_HZ / 2)) / USER_HZ); |
8b9365d7 | 710 | #endif |
8b9365d7 IM |
711 | } |
712 | ||
b7b20df9 | 713 | /** |
a1dabb6b | 714 | * nsecs_to_jiffies64 - Convert nsecs in u64 to jiffies64 |
b7b20df9 HS |
715 | * |
716 | * @n: nsecs in u64 | |
717 | * | |
718 | * Unlike {m,u}secs_to_jiffies, type of input is not unsigned int but u64. | |
719 | * And this doesn't return MAX_JIFFY_OFFSET since this function is designed | |
720 | * for scheduler, not for use in device drivers to calculate timeout value. | |
721 | * | |
722 | * note: | |
723 | * NSEC_PER_SEC = 10^9 = (5^9 * 2^9) = (1953125 * 512) | |
724 | * ULLONG_MAX ns = 18446744073.709551615 secs = about 584 years | |
725 | */ | |
a1dabb6b | 726 | u64 nsecs_to_jiffies64(u64 n) |
b7b20df9 HS |
727 | { |
728 | #if (NSEC_PER_SEC % HZ) == 0 | |
729 | /* Common case, HZ = 100, 128, 200, 250, 256, 500, 512, 1000 etc. */ | |
730 | return div_u64(n, NSEC_PER_SEC / HZ); | |
731 | #elif (HZ % 512) == 0 | |
732 | /* overflow after 292 years if HZ = 1024 */ | |
733 | return div_u64(n * HZ / 512, NSEC_PER_SEC / 512); | |
734 | #else | |
735 | /* | |
736 | * Generic case - optimized for cases where HZ is a multiple of 3. | |
737 | * overflow after 64.99 years, exact for HZ = 60, 72, 90, 120 etc. | |
738 | */ | |
739 | return div_u64(n * 9, (9ull * NSEC_PER_SEC + HZ / 2) / HZ); | |
740 | #endif | |
741 | } | |
742 | ||
a1dabb6b VP |
743 | /** |
744 | * nsecs_to_jiffies - Convert nsecs in u64 to jiffies | |
745 | * | |
746 | * @n: nsecs in u64 | |
747 | * | |
748 | * Unlike {m,u}secs_to_jiffies, type of input is not unsigned int but u64. | |
749 | * And this doesn't return MAX_JIFFY_OFFSET since this function is designed | |
750 | * for scheduler, not for use in device drivers to calculate timeout value. | |
751 | * | |
752 | * note: | |
753 | * NSEC_PER_SEC = 10^9 = (5^9 * 2^9) = (1953125 * 512) | |
754 | * ULLONG_MAX ns = 18446744073.709551615 secs = about 584 years | |
755 | */ | |
756 | unsigned long nsecs_to_jiffies(u64 n) | |
757 | { | |
758 | return (unsigned long)nsecs_to_jiffies64(n); | |
759 | } | |
760 | ||
df0cc053 TG |
761 | /* |
762 | * Add two timespec values and do a safety check for overflow. | |
763 | * It's assumed that both values are valid (>= 0) | |
764 | */ | |
765 | struct timespec timespec_add_safe(const struct timespec lhs, | |
766 | const struct timespec rhs) | |
767 | { | |
768 | struct timespec res; | |
769 | ||
770 | set_normalized_timespec(&res, lhs.tv_sec + rhs.tv_sec, | |
771 | lhs.tv_nsec + rhs.tv_nsec); | |
772 | ||
773 | if (res.tv_sec < lhs.tv_sec || res.tv_sec < rhs.tv_sec) | |
774 | res.tv_sec = TIME_T_MAX; | |
775 | ||
776 | return res; | |
777 | } |