| 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/core.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/export.h>
|
| 31 | #include <linux/timex.h>
|
| 32 | #include <linux/capability.h>
|
| 33 | #include <linux/timekeeper_internal.h>
|
| 34 | #include <linux/errno.h>
|
| 35 | #include <linux/syscalls.h>
|
| 36 | #include <linux/security.h>
|
| 37 | #include <linux/fs.h>
|
| 38 | #include <linux/math64.h>
|
| 39 | #include <linux/ptrace.h>
|
| 40 |
|
| 41 | #include <asm/uaccess.h>
|
| 42 | #include <asm/unistd.h>
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| 43 |
|
| 44 | #include <generated/timeconst.h>
|
| 45 | #include "timekeeping.h"
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| 46 |
|
| 47 | |
| 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
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| 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 |
|
| 63 | SYSCALL_DEFINE1(time, time_t __user *, tloc)
|
| 64 | {
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| 65 | time_t i = get_seconds();
|
| 66 |
|
| 67 | if (tloc) {
|
| 68 | if (put_user(i,tloc))
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| 69 | return -EFAULT;
|
| 70 | }
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| 71 | force_successful_syscall_return();
|
| 72 | return i;
|
| 73 | }
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| 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 |
|
| 81 |
|
| 82 | SYSCALL_DEFINE1(stime, time_t __user *, tptr)
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| 83 | {
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| 84 | struct timespec tv;
|
| 85 | int err;
|
| 86 |
|
| 87 | if (get_user(tv.tv_sec, tptr))
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| 88 | return -EFAULT;
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| 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
|
| 101 |
|
| 102 | SYSCALL_DEFINE2(gettimeofday, struct timeval __user *, tv,
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| 103 | struct timezone __user *, tz)
|
| 104 | {
|
| 105 | if (likely(tv != NULL)) {
|
| 106 | struct timeval ktv;
|
| 107 | do_gettimeofday(&ktv);
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| 108 | if (copy_to_user(tv, &ktv, sizeof(ktv)))
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| 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 |
|
| 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 |
|
| 124 | |
| 125 | * Adjust the time obtained from the CMOS to be UTC time instead of
|
| 126 | * local time.
|
| 127 | *
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| 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
|
| 130 | * confusion if the program gets run more than once; it would also be
|
| 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 | *
|
| 134 | * - TYT, 1992-01-01
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| 135 | *
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| 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 |
|
| 140 | static inline void warp_clock(void)
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| 141 | {
|
| 142 | if (sys_tz.tz_minuteswest != 0) {
|
| 143 | struct timespec adjust;
|
| 144 |
|
| 145 | persistent_clock_is_local = 1;
|
| 146 | adjust.tv_sec = sys_tz.tz_minuteswest * 60;
|
| 147 | adjust.tv_nsec = 0;
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| 148 | timekeeping_inject_offset(&adjust);
|
| 149 | }
|
| 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 |
|
| 163 | int do_sys_settimeofday64(const struct timespec64 *tv, const struct timezone *tz)
|
| 164 | {
|
| 165 | static int firsttime = 1;
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| 166 | int error = 0;
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| 167 |
|
| 168 | if (tv && !timespec64_valid(tv))
|
| 169 | return -EINVAL;
|
| 170 |
|
| 171 | error = security_settime64(tv, tz);
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| 172 | if (error)
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| 173 | return error;
|
| 174 |
|
| 175 | if (tz) {
|
| 176 |
|
| 177 | if (tz->tz_minuteswest > 15*60 || tz->tz_minuteswest < -15*60)
|
| 178 | return -EINVAL;
|
| 179 |
|
| 180 | sys_tz = *tz;
|
| 181 | update_vsyscall_tz();
|
| 182 | if (firsttime) {
|
| 183 | firsttime = 0;
|
| 184 | if (!tv)
|
| 185 | warp_clock();
|
| 186 | }
|
| 187 | }
|
| 188 | if (tv)
|
| 189 | return do_settimeofday64(tv);
|
| 190 | return 0;
|
| 191 | }
|
| 192 |
|
| 193 | SYSCALL_DEFINE2(settimeofday, struct timeval __user *, tv,
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| 194 | struct timezone __user *, tz)
|
| 195 | {
|
| 196 | struct timeval user_tv;
|
| 197 | struct timespec new_ts;
|
| 198 | struct timezone new_tz;
|
| 199 |
|
| 200 | if (tv) {
|
| 201 | if (copy_from_user(&user_tv, tv, sizeof(*tv)))
|
| 202 | return -EFAULT;
|
| 203 |
|
| 204 | if (!timeval_valid(&user_tv))
|
| 205 | return -EINVAL;
|
| 206 |
|
| 207 | new_ts.tv_sec = user_tv.tv_sec;
|
| 208 | new_ts.tv_nsec = user_tv.tv_usec * NSEC_PER_USEC;
|
| 209 | }
|
| 210 | if (tz) {
|
| 211 | if (copy_from_user(&new_tz, tz, sizeof(*tz)))
|
| 212 | return -EFAULT;
|
| 213 | }
|
| 214 |
|
| 215 | return do_sys_settimeofday(tv ? &new_ts : NULL, tz ? &new_tz : NULL);
|
| 216 | }
|
| 217 |
|
| 218 | SYSCALL_DEFINE1(adjtimex, struct timex __user *, txc_p)
|
| 219 | {
|
| 220 | struct timex txc;
|
| 221 | int ret;
|
| 222 |
|
| 223 | |
| 224 | * structure. But bear in mind that the structures
|
| 225 | * may change
|
| 226 |
|
| 227 | if(copy_from_user(&txc, txc_p, sizeof(struct timex)))
|
| 228 | return -EFAULT;
|
| 229 | ret = do_adjtimex(&txc);
|
| 230 | return copy_to_user(txc_p, &txc, sizeof(struct timex)) ? -EFAULT : ret;
|
| 231 | }
|
| 232 |
|
| 233 | |
| 234 | * current_fs_time - Return FS time
|
| 235 | * @sb: Superblock.
|
| 236 | *
|
| 237 | * Return the current time truncated to the time granularity supported by
|
| 238 | * the fs.
|
| 239 |
|
| 240 | struct timespec current_fs_time(struct super_block *sb)
|
| 241 | {
|
| 242 | struct timespec now = current_kernel_time();
|
| 243 | return timespec_trunc(now, sb->s_time_gran);
|
| 244 | }
|
| 245 | EXPORT_SYMBOL(current_fs_time);
|
| 246 |
|
| 247 | |
| 248 | * Convert jiffies to milliseconds and back.
|
| 249 | *
|
| 250 | * Avoid unnecessary multiplications/divisions in the
|
| 251 | * two most common HZ cases:
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| 252 |
|
| 253 | unsigned int jiffies_to_msecs(const unsigned long j)
|
| 254 | {
|
| 255 | #if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
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| 256 | return (MSEC_PER_SEC / HZ) * j;
|
| 257 | #elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)
|
| 258 | return (j + (HZ / MSEC_PER_SEC) - 1)/(HZ / MSEC_PER_SEC);
|
| 259 | #else
|
| 260 | # if BITS_PER_LONG == 32
|
| 261 | return (HZ_TO_MSEC_MUL32 * j) >> HZ_TO_MSEC_SHR32;
|
| 262 | # else
|
| 263 | return (j * HZ_TO_MSEC_NUM) / HZ_TO_MSEC_DEN;
|
| 264 | # endif
|
| 265 | #endif
|
| 266 | }
|
| 267 | EXPORT_SYMBOL(jiffies_to_msecs);
|
| 268 |
|
| 269 | unsigned int jiffies_to_usecs(const unsigned long j)
|
| 270 | {
|
| 271 | |
| 272 | * Hz usually doesn't go much further MSEC_PER_SEC.
|
| 273 | * jiffies_to_usecs() and usecs_to_jiffies() depend on that.
|
| 274 |
|
| 275 | BUILD_BUG_ON(HZ > USEC_PER_SEC);
|
| 276 |
|
| 277 | #if !(USEC_PER_SEC % HZ)
|
| 278 | return (USEC_PER_SEC / HZ) * j;
|
| 279 | #else
|
| 280 | # if BITS_PER_LONG == 32
|
| 281 | return (HZ_TO_USEC_MUL32 * j) >> HZ_TO_USEC_SHR32;
|
| 282 | # else
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| 283 | return (j * HZ_TO_USEC_NUM) / HZ_TO_USEC_DEN;
|
| 284 | # endif
|
| 285 | #endif
|
| 286 | }
|
| 287 | EXPORT_SYMBOL(jiffies_to_usecs);
|
| 288 |
|
| 289 | |
| 290 | * timespec_trunc - Truncate timespec to a granularity
|
| 291 | * @t: Timespec
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| 292 | * @gran: Granularity in ns.
|
| 293 | *
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| 294 | * Truncate a timespec to a granularity. Always rounds down. gran must
|
| 295 | * not be 0 nor greater than a second (NSEC_PER_SEC, or 10^9 ns).
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| 296 |
|
| 297 | struct timespec timespec_trunc(struct timespec t, unsigned gran)
|
| 298 | {
|
| 299 |
|
| 300 | if (gran == 1) {
|
| 301 |
|
| 302 | } else if (gran == NSEC_PER_SEC) {
|
| 303 | t.tv_nsec = 0;
|
| 304 | } else if (gran > 1 && gran < NSEC_PER_SEC) {
|
| 305 | t.tv_nsec -= t.tv_nsec % gran;
|
| 306 | } else {
|
| 307 | WARN(1, "illegal file time granularity: %u", gran);
|
| 308 | }
|
| 309 | return t;
|
| 310 | }
|
| 311 | EXPORT_SYMBOL(timespec_trunc);
|
| 312 |
|
| 313 | |
| 314 | * mktime64 - Converts date to seconds.
|
| 315 | * Converts Gregorian date to seconds since 1970-01-01 00:00:00.
|
| 316 | * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
|
| 317 | * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
|
| 318 | *
|
| 319 | * [For the Julian calendar (which was used in Russia before 1917,
|
| 320 | * Britain & colonies before 1752, anywhere else before 1582,
|
| 321 | * and is still in use by some communities) leave out the
|
| 322 | * -year/100+year/400 terms, and add 10.]
|
| 323 | *
|
| 324 | * This algorithm was first published by Gauss (I think).
|
| 325 | *
|
| 326 | * A leap second can be indicated by calling this function with sec as
|
| 327 | * 60 (allowable under ISO 8601). The leap second is treated the same
|
| 328 | * as the following second since they don't exist in UNIX time.
|
| 329 | *
|
| 330 | * An encoding of midnight at the end of the day as 24:00:00 - ie. midnight
|
| 331 | * tomorrow - (allowable under ISO 8601) is supported.
|
| 332 |
|
| 333 | time64_t mktime64(const unsigned int year0, const unsigned int mon0,
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| 334 | const unsigned int day, const unsigned int hour,
|
| 335 | const unsigned int min, const unsigned int sec)
|
| 336 | {
|
| 337 | unsigned int mon = mon0, year = year0;
|
| 338 |
|
| 339 |
|
| 340 | if (0 >= (int) (mon -= 2)) {
|
| 341 | mon += 12;
|
| 342 | year -= 1;
|
| 343 | }
|
| 344 |
|
| 345 | return ((((time64_t)
|
| 346 | (year/4 - year/100 + year/400 + 367*mon/12 + day) +
|
| 347 | year*365 - 719499
|
| 348 | )*24 + hour
|
| 349 | )*60 + min
|
| 350 | )*60 + sec;
|
| 351 | }
|
| 352 | EXPORT_SYMBOL(mktime64);
|
| 353 |
|
| 354 | |
| 355 | * set_normalized_timespec - set timespec sec and nsec parts and normalize
|
| 356 | *
|
| 357 | * @ts: pointer to timespec variable to be set
|
| 358 | * @sec: seconds to set
|
| 359 | * @nsec: nanoseconds to set
|
| 360 | *
|
| 361 | * Set seconds and nanoseconds field of a timespec variable and
|
| 362 | * normalize to the timespec storage format
|
| 363 | *
|
| 364 | * Note: The tv_nsec part is always in the range of
|
| 365 | * 0 <= tv_nsec < NSEC_PER_SEC
|
| 366 | * For negative values only the tv_sec field is negative !
|
| 367 |
|
| 368 | void set_normalized_timespec(struct timespec *ts, time_t sec, s64 nsec)
|
| 369 | {
|
| 370 | while (nsec >= NSEC_PER_SEC) {
|
| 371 | |
| 372 | * The following asm() prevents the compiler from
|
| 373 | * optimising this loop into a modulo operation. See
|
| 374 | * also __iter_div_u64_rem() in include/linux/time.h
|
| 375 |
|
| 376 | asm("" : "+rm"(nsec));
|
| 377 | nsec -= NSEC_PER_SEC;
|
| 378 | ++sec;
|
| 379 | }
|
| 380 | while (nsec < 0) {
|
| 381 | asm("" : "+rm"(nsec));
|
| 382 | nsec += NSEC_PER_SEC;
|
| 383 | --sec;
|
| 384 | }
|
| 385 | ts->tv_sec = sec;
|
| 386 | ts->tv_nsec = nsec;
|
| 387 | }
|
| 388 | EXPORT_SYMBOL(set_normalized_timespec);
|
| 389 |
|
| 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 |
|
| 396 | struct timespec ns_to_timespec(const s64 nsec)
|
| 397 | {
|
| 398 | struct timespec ts;
|
| 399 | s32 rem;
|
| 400 |
|
| 401 | if (!nsec)
|
| 402 | return (struct timespec) {0, 0};
|
| 403 |
|
| 404 | ts.tv_sec = div_s64_rem(nsec, NSEC_PER_SEC, &rem);
|
| 405 | if (unlikely(rem < 0)) {
|
| 406 | ts.tv_sec--;
|
| 407 | rem += NSEC_PER_SEC;
|
| 408 | }
|
| 409 | ts.tv_nsec = rem;
|
| 410 |
|
| 411 | return ts;
|
| 412 | }
|
| 413 | EXPORT_SYMBOL(ns_to_timespec);
|
| 414 |
|
| 415 | |
| 416 | * ns_to_timeval - Convert nanoseconds to timeval
|
| 417 | * @nsec: the nanoseconds value to be converted
|
| 418 | *
|
| 419 | * Returns the timeval representation of the nsec parameter.
|
| 420 |
|
| 421 | struct timeval ns_to_timeval(const s64 nsec)
|
| 422 | {
|
| 423 | struct timespec ts = ns_to_timespec(nsec);
|
| 424 | struct timeval tv;
|
| 425 |
|
| 426 | tv.tv_sec = ts.tv_sec;
|
| 427 | tv.tv_usec = (suseconds_t) ts.tv_nsec / 1000;
|
| 428 |
|
| 429 | return tv;
|
| 430 | }
|
| 431 | EXPORT_SYMBOL(ns_to_timeval);
|
| 432 |
|
| 433 | #if BITS_PER_LONG == 32
|
| 434 | |
| 435 | * set_normalized_timespec - set timespec sec and nsec parts and normalize
|
| 436 | *
|
| 437 | * @ts: pointer to timespec variable to be set
|
| 438 | * @sec: seconds to set
|
| 439 | * @nsec: nanoseconds to set
|
| 440 | *
|
| 441 | * Set seconds and nanoseconds field of a timespec variable and
|
| 442 | * normalize to the timespec storage format
|
| 443 | *
|
| 444 | * Note: The tv_nsec part is always in the range of
|
| 445 | * 0 <= tv_nsec < NSEC_PER_SEC
|
| 446 | * For negative values only the tv_sec field is negative !
|
| 447 |
|
| 448 | void set_normalized_timespec64(struct timespec64 *ts, time64_t sec, s64 nsec)
|
| 449 | {
|
| 450 | while (nsec >= NSEC_PER_SEC) {
|
| 451 | |
| 452 | * The following asm() prevents the compiler from
|
| 453 | * optimising this loop into a modulo operation. See
|
| 454 | * also __iter_div_u64_rem() in include/linux/time.h
|
| 455 |
|
| 456 | asm("" : "+rm"(nsec));
|
| 457 | nsec -= NSEC_PER_SEC;
|
| 458 | ++sec;
|
| 459 | }
|
| 460 | while (nsec < 0) {
|
| 461 | asm("" : "+rm"(nsec));
|
| 462 | nsec += NSEC_PER_SEC;
|
| 463 | --sec;
|
| 464 | }
|
| 465 | ts->tv_sec = sec;
|
| 466 | ts->tv_nsec = nsec;
|
| 467 | }
|
| 468 | EXPORT_SYMBOL(set_normalized_timespec64);
|
| 469 |
|
| 470 | |
| 471 | * ns_to_timespec64 - Convert nanoseconds to timespec64
|
| 472 | * @nsec: the nanoseconds value to be converted
|
| 473 | *
|
| 474 | * Returns the timespec64 representation of the nsec parameter.
|
| 475 |
|
| 476 | struct timespec64 ns_to_timespec64(const s64 nsec)
|
| 477 | {
|
| 478 | struct timespec64 ts;
|
| 479 | s32 rem;
|
| 480 |
|
| 481 | if (!nsec)
|
| 482 | return (struct timespec64) {0, 0};
|
| 483 |
|
| 484 | ts.tv_sec = div_s64_rem(nsec, NSEC_PER_SEC, &rem);
|
| 485 | if (unlikely(rem < 0)) {
|
| 486 | ts.tv_sec--;
|
| 487 | rem += NSEC_PER_SEC;
|
| 488 | }
|
| 489 | ts.tv_nsec = rem;
|
| 490 |
|
| 491 | return ts;
|
| 492 | }
|
| 493 | EXPORT_SYMBOL(ns_to_timespec64);
|
| 494 | #endif
|
| 495 | |
| 496 | * msecs_to_jiffies: - convert milliseconds to jiffies
|
| 497 | * @m: time in milliseconds
|
| 498 | *
|
| 499 | * conversion is done as follows:
|
| 500 | *
|
| 501 | * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET)
|
| 502 | *
|
| 503 | * - 'too large' values [that would result in larger than
|
| 504 | * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.
|
| 505 | *
|
| 506 | * - all other values are converted to jiffies by either multiplying
|
| 507 | * the input value by a factor or dividing it with a factor and
|
| 508 | * handling any 32-bit overflows.
|
| 509 | * for the details see __msecs_to_jiffies()
|
| 510 | *
|
| 511 | * msecs_to_jiffies() checks for the passed in value being a constant
|
| 512 | * via __builtin_constant_p() allowing gcc to eliminate most of the
|
| 513 | * code, __msecs_to_jiffies() is called if the value passed does not
|
| 514 | * allow constant folding and the actual conversion must be done at
|
| 515 | * runtime.
|
| 516 | * the _msecs_to_jiffies helpers are the HZ dependent conversion
|
| 517 | * routines found in include/linux/jiffies.h
|
| 518 |
|
| 519 | unsigned long __msecs_to_jiffies(const unsigned int m)
|
| 520 | {
|
| 521 | |
| 522 | * Negative value, means infinite timeout:
|
| 523 |
|
| 524 | if ((int)m < 0)
|
| 525 | return MAX_JIFFY_OFFSET;
|
| 526 | return _msecs_to_jiffies(m);
|
| 527 | }
|
| 528 | EXPORT_SYMBOL(__msecs_to_jiffies);
|
| 529 |
|
| 530 | unsigned long __usecs_to_jiffies(const unsigned int u)
|
| 531 | {
|
| 532 | if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET))
|
| 533 | return MAX_JIFFY_OFFSET;
|
| 534 | return _usecs_to_jiffies(u);
|
| 535 | }
|
| 536 | EXPORT_SYMBOL(__usecs_to_jiffies);
|
| 537 |
|
| 538 | |
| 539 | * The TICK_NSEC - 1 rounds up the value to the next resolution. Note
|
| 540 | * that a remainder subtract here would not do the right thing as the
|
| 541 | * resolution values don't fall on second boundries. I.e. the line:
|
| 542 | * nsec -= nsec % TICK_NSEC; is NOT a correct resolution rounding.
|
| 543 | * Note that due to the small error in the multiplier here, this
|
| 544 | * rounding is incorrect for sufficiently large values of tv_nsec, but
|
| 545 | * well formed timespecs should have tv_nsec < NSEC_PER_SEC, so we're
|
| 546 | * OK.
|
| 547 | *
|
| 548 | * Rather, we just shift the bits off the right.
|
| 549 | *
|
| 550 | * The >> (NSEC_JIFFIE_SC - SEC_JIFFIE_SC) converts the scaled nsec
|
| 551 | * value to a scaled second value.
|
| 552 |
|
| 553 | static unsigned long
|
| 554 | __timespec64_to_jiffies(u64 sec, long nsec)
|
| 555 | {
|
| 556 | nsec = nsec + TICK_NSEC - 1;
|
| 557 |
|
| 558 | if (sec >= MAX_SEC_IN_JIFFIES){
|
| 559 | sec = MAX_SEC_IN_JIFFIES;
|
| 560 | nsec = 0;
|
| 561 | }
|
| 562 | return ((sec * SEC_CONVERSION) +
|
| 563 | (((u64)nsec * NSEC_CONVERSION) >>
|
| 564 | (NSEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC;
|
| 565 |
|
| 566 | }
|
| 567 |
|
| 568 | static unsigned long
|
| 569 | __timespec_to_jiffies(unsigned long sec, long nsec)
|
| 570 | {
|
| 571 | return __timespec64_to_jiffies((u64)sec, nsec);
|
| 572 | }
|
| 573 |
|
| 574 | unsigned long
|
| 575 | timespec64_to_jiffies(const struct timespec64 *value)
|
| 576 | {
|
| 577 | return __timespec64_to_jiffies(value->tv_sec, value->tv_nsec);
|
| 578 | }
|
| 579 | EXPORT_SYMBOL(timespec64_to_jiffies);
|
| 580 |
|
| 581 | void
|
| 582 | jiffies_to_timespec64(const unsigned long jiffies, struct timespec64 *value)
|
| 583 | {
|
| 584 | |
| 585 | * Convert jiffies to nanoseconds and separate with
|
| 586 | * one divide.
|
| 587 |
|
| 588 | u32 rem;
|
| 589 | value->tv_sec = div_u64_rem((u64)jiffies * TICK_NSEC,
|
| 590 | NSEC_PER_SEC, &rem);
|
| 591 | value->tv_nsec = rem;
|
| 592 | }
|
| 593 | EXPORT_SYMBOL(jiffies_to_timespec64);
|
| 594 |
|
| 595 | |
| 596 | * We could use a similar algorithm to timespec_to_jiffies (with a
|
| 597 | * different multiplier for usec instead of nsec). But this has a
|
| 598 | * problem with rounding: we can't exactly add TICK_NSEC - 1 to the
|
| 599 | * usec value, since it's not necessarily integral.
|
| 600 | *
|
| 601 | * We could instead round in the intermediate scaled representation
|
| 602 | * (i.e. in units of 1/2^(large scale) jiffies) but that's also
|
| 603 | * perilous: the scaling introduces a small positive error, which
|
| 604 | * combined with a division-rounding-upward (i.e. adding 2^(scale) - 1
|
| 605 | * units to the intermediate before shifting) leads to accidental
|
| 606 | * overflow and overestimates.
|
| 607 | *
|
| 608 | * At the cost of one additional multiplication by a constant, just
|
| 609 | * use the timespec implementation.
|
| 610 |
|
| 611 | unsigned long
|
| 612 | timeval_to_jiffies(const struct timeval *value)
|
| 613 | {
|
| 614 | return __timespec_to_jiffies(value->tv_sec,
|
| 615 | value->tv_usec * NSEC_PER_USEC);
|
| 616 | }
|
| 617 | EXPORT_SYMBOL(timeval_to_jiffies);
|
| 618 |
|
| 619 | void jiffies_to_timeval(const unsigned long jiffies, struct timeval *value)
|
| 620 | {
|
| 621 | |
| 622 | * Convert jiffies to nanoseconds and separate with
|
| 623 | * one divide.
|
| 624 |
|
| 625 | u32 rem;
|
| 626 |
|
| 627 | value->tv_sec = div_u64_rem((u64)jiffies * TICK_NSEC,
|
| 628 | NSEC_PER_SEC, &rem);
|
| 629 | value->tv_usec = rem / NSEC_PER_USEC;
|
| 630 | }
|
| 631 | EXPORT_SYMBOL(jiffies_to_timeval);
|
| 632 |
|
| 633 | |
| 634 | * Convert jiffies/jiffies_64 to clock_t and back.
|
| 635 |
|
| 636 | clock_t jiffies_to_clock_t(unsigned long x)
|
| 637 | {
|
| 638 | #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
|
| 639 | # if HZ < USER_HZ
|
| 640 | return x * (USER_HZ / HZ);
|
| 641 | # else
|
| 642 | return x / (HZ / USER_HZ);
|
| 643 | # endif
|
| 644 | #else
|
| 645 | return div_u64((u64)x * TICK_NSEC, NSEC_PER_SEC / USER_HZ);
|
| 646 | #endif
|
| 647 | }
|
| 648 | EXPORT_SYMBOL(jiffies_to_clock_t);
|
| 649 |
|
| 650 | unsigned long clock_t_to_jiffies(unsigned long x)
|
| 651 | {
|
| 652 | #if (HZ % USER_HZ)==0
|
| 653 | if (x >= ~0UL / (HZ / USER_HZ))
|
| 654 | return ~0UL;
|
| 655 | return x * (HZ / USER_HZ);
|
| 656 | #else
|
| 657 |
|
| 658 | if (x >= ~0UL / HZ * USER_HZ)
|
| 659 | return ~0UL;
|
| 660 |
|
| 661 |
|
| 662 | return div_u64((u64)x * HZ, USER_HZ);
|
| 663 | #endif
|
| 664 | }
|
| 665 | EXPORT_SYMBOL(clock_t_to_jiffies);
|
| 666 |
|
| 667 | u64 jiffies_64_to_clock_t(u64 x)
|
| 668 | {
|
| 669 | #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
|
| 670 | # if HZ < USER_HZ
|
| 671 | x = div_u64(x * USER_HZ, HZ);
|
| 672 | # elif HZ > USER_HZ
|
| 673 | x = div_u64(x, HZ / USER_HZ);
|
| 674 | # else
|
| 675 |
|
| 676 | # endif
|
| 677 | #else
|
| 678 | |
| 679 | * There are better ways that don't overflow early,
|
| 680 | * but even this doesn't overflow in hundreds of years
|
| 681 | * in 64 bits, so..
|
| 682 |
|
| 683 | x = div_u64(x * TICK_NSEC, (NSEC_PER_SEC / USER_HZ));
|
| 684 | #endif
|
| 685 | return x;
|
| 686 | }
|
| 687 | EXPORT_SYMBOL(jiffies_64_to_clock_t);
|
| 688 |
|
| 689 | u64 nsec_to_clock_t(u64 x)
|
| 690 | {
|
| 691 | #if (NSEC_PER_SEC % USER_HZ) == 0
|
| 692 | return div_u64(x, NSEC_PER_SEC / USER_HZ);
|
| 693 | #elif (USER_HZ % 512) == 0
|
| 694 | return div_u64(x * USER_HZ / 512, NSEC_PER_SEC / 512);
|
| 695 | #else
|
| 696 | |
| 697 | * max relative error 5.7e-8 (1.8s per year) for USER_HZ <= 1024,
|
| 698 | * overflow after 64.99 years.
|
| 699 | * exact for HZ=60, 72, 90, 120, 144, 180, 300, 600, 900, ...
|
| 700 |
|
| 701 | return div_u64(x * 9, (9ull * NSEC_PER_SEC + (USER_HZ / 2)) / USER_HZ);
|
| 702 | #endif
|
| 703 | }
|
| 704 |
|
| 705 | |
| 706 | * nsecs_to_jiffies64 - Convert nsecs in u64 to jiffies64
|
| 707 | *
|
| 708 | * @n: nsecs in u64
|
| 709 | *
|
| 710 | * Unlike {m,u}secs_to_jiffies, type of input is not unsigned int but u64.
|
| 711 | * And this doesn't return MAX_JIFFY_OFFSET since this function is designed
|
| 712 | * for scheduler, not for use in device drivers to calculate timeout value.
|
| 713 | *
|
| 714 | * note:
|
| 715 | * NSEC_PER_SEC = 10^9 = (5^9 * 2^9) = (1953125 * 512)
|
| 716 | * ULLONG_MAX ns = 18446744073.709551615 secs = about 584 years
|
| 717 |
|
| 718 | u64 nsecs_to_jiffies64(u64 n)
|
| 719 | {
|
| 720 | #if (NSEC_PER_SEC % HZ) == 0
|
| 721 |
|
| 722 | return div_u64(n, NSEC_PER_SEC / HZ);
|
| 723 | #elif (HZ % 512) == 0
|
| 724 |
|
| 725 | return div_u64(n * HZ / 512, NSEC_PER_SEC / 512);
|
| 726 | #else
|
| 727 | |
| 728 | * Generic case - optimized for cases where HZ is a multiple of 3.
|
| 729 | * overflow after 64.99 years, exact for HZ = 60, 72, 90, 120 etc.
|
| 730 |
|
| 731 | return div_u64(n * 9, (9ull * NSEC_PER_SEC + HZ / 2) / HZ);
|
| 732 | #endif
|
| 733 | }
|
| 734 | EXPORT_SYMBOL(nsecs_to_jiffies64);
|
| 735 |
|
| 736 | |
| 737 | * nsecs_to_jiffies - Convert nsecs in u64 to jiffies
|
| 738 | *
|
| 739 | * @n: nsecs in u64
|
| 740 | *
|
| 741 | * Unlike {m,u}secs_to_jiffies, type of input is not unsigned int but u64.
|
| 742 | * And this doesn't return MAX_JIFFY_OFFSET since this function is designed
|
| 743 | * for scheduler, not for use in device drivers to calculate timeout value.
|
| 744 | *
|
| 745 | * note:
|
| 746 | * NSEC_PER_SEC = 10^9 = (5^9 * 2^9) = (1953125 * 512)
|
| 747 | * ULLONG_MAX ns = 18446744073.709551615 secs = about 584 years
|
| 748 |
|
| 749 | unsigned long nsecs_to_jiffies(u64 n)
|
| 750 | {
|
| 751 | return (unsigned long)nsecs_to_jiffies64(n);
|
| 752 | }
|
| 753 | EXPORT_SYMBOL_GPL(nsecs_to_jiffies);
|
| 754 |
|
| 755 | |
| 756 | * Add two timespec values and do a safety check for overflow.
|
| 757 | * It's assumed that both values are valid (>= 0)
|
| 758 |
|
| 759 | struct timespec timespec_add_safe(const struct timespec lhs,
|
| 760 | const struct timespec rhs)
|
| 761 | {
|
| 762 | struct timespec res;
|
| 763 |
|
| 764 | set_normalized_timespec(&res, lhs.tv_sec + rhs.tv_sec,
|
| 765 | lhs.tv_nsec + rhs.tv_nsec);
|
| 766 |
|
| 767 | if (res.tv_sec < lhs.tv_sec || res.tv_sec < rhs.tv_sec)
|
| 768 | res.tv_sec = TIME_T_MAX;
|
| 769 |
|
| 770 | return res;
|
| 771 | }
|
| 772 |
|
| 773 | |
| 774 | * Add two timespec64 values and do a safety check for overflow.
|
| 775 | * It's assumed that both values are valid (>= 0).
|
| 776 | * And, each timespec64 is in normalized form.
|
| 777 |
|
| 778 | struct timespec64 timespec64_add_safe(const struct timespec64 lhs,
|
| 779 | const struct timespec64 rhs)
|
| 780 | {
|
| 781 | struct timespec64 res;
|
| 782 |
|
| 783 | set_normalized_timespec64(&res, (timeu64_t) lhs.tv_sec + rhs.tv_sec,
|
| 784 | lhs.tv_nsec + rhs.tv_nsec);
|
| 785 |
|
| 786 | if (unlikely(res.tv_sec < lhs.tv_sec || res.tv_sec < rhs.tv_sec)) {
|
| 787 | res.tv_sec = TIME64_MAX;
|
| 788 | res.tv_nsec = 0;
|
| 789 | }
|
| 790 |
|
| 791 | return res;
|
| 792 | }
|