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 <linux/uaccess.h> 42 #include <linux/compat.h> 43 #include <asm/unistd.h> 44 45 #include <generated/timeconst.h> 46 #include "timekeeping.h" 47 48 /* 49 * The timezone where the local system is located. Used as a default by some 50 * programs who obtain this value by using gettimeofday. 51 */ 52 struct timezone sys_tz; 53 54 EXPORT_SYMBOL(sys_tz); 55 56 #ifdef __ARCH_WANT_SYS_TIME 57 58 /* 59 * sys_time() can be implemented in user-level using 60 * sys_gettimeofday(). Is this for backwards compatibility? If so, 61 * why not move it into the appropriate arch directory (for those 62 * architectures that need it). 63 */ 64 SYSCALL_DEFINE1(time, time_t __user *, tloc) 65 { 66 time_t i = get_seconds(); 67 68 if (tloc) { 69 if (put_user(i,tloc)) 70 return -EFAULT; 71 } 72 force_successful_syscall_return(); 73 return i; 74 } 75 76 /* 77 * sys_stime() can be implemented in user-level using 78 * sys_settimeofday(). Is this for backwards compatibility? If so, 79 * why not move it into the appropriate arch directory (for those 80 * architectures that need it). 81 */ 82 83 SYSCALL_DEFINE1(stime, time_t __user *, tptr) 84 { 85 struct timespec64 tv; 86 int err; 87 88 if (get_user(tv.tv_sec, tptr)) 89 return -EFAULT; 90 91 tv.tv_nsec = 0; 92 93 err = security_settime64(&tv, NULL); 94 if (err) 95 return err; 96 97 do_settimeofday64(&tv); 98 return 0; 99 } 100 101 #endif /* __ARCH_WANT_SYS_TIME */ 102 103 #ifdef CONFIG_COMPAT 104 #ifdef __ARCH_WANT_COMPAT_SYS_TIME 105 106 /* compat_time_t is a 32 bit "long" and needs to get converted. */ 107 COMPAT_SYSCALL_DEFINE1(time, compat_time_t __user *, tloc) 108 { 109 struct timeval tv; 110 compat_time_t i; 111 112 do_gettimeofday(&tv); 113 i = tv.tv_sec; 114 115 if (tloc) { 116 if (put_user(i,tloc)) 117 return -EFAULT; 118 } 119 force_successful_syscall_return(); 120 return i; 121 } 122 123 COMPAT_SYSCALL_DEFINE1(stime, compat_time_t __user *, tptr) 124 { 125 struct timespec64 tv; 126 int err; 127 128 if (get_user(tv.tv_sec, tptr)) 129 return -EFAULT; 130 131 tv.tv_nsec = 0; 132 133 err = security_settime64(&tv, NULL); 134 if (err) 135 return err; 136 137 do_settimeofday64(&tv); 138 return 0; 139 } 140 141 #endif /* __ARCH_WANT_COMPAT_SYS_TIME */ 142 #endif 143 144 SYSCALL_DEFINE2(gettimeofday, struct timeval __user *, tv, 145 struct timezone __user *, tz) 146 { 147 if (likely(tv != NULL)) { 148 struct timeval ktv; 149 do_gettimeofday(&ktv); 150 if (copy_to_user(tv, &ktv, sizeof(ktv))) 151 return -EFAULT; 152 } 153 if (unlikely(tz != NULL)) { 154 if (copy_to_user(tz, &sys_tz, sizeof(sys_tz))) 155 return -EFAULT; 156 } 157 return 0; 158 } 159 160 /* 161 * In case for some reason the CMOS clock has not already been running 162 * in UTC, but in some local time: The first time we set the timezone, 163 * we will warp the clock so that it is ticking UTC time instead of 164 * local time. Presumably, if someone is setting the timezone then we 165 * are running in an environment where the programs understand about 166 * timezones. This should be done at boot time in the /etc/rc script, 167 * as soon as possible, so that the clock can be set right. Otherwise, 168 * various programs will get confused when the clock gets warped. 169 */ 170 171 int do_sys_settimeofday64(const struct timespec64 *tv, const struct timezone *tz) 172 { 173 static int firsttime = 1; 174 int error = 0; 175 176 if (tv && !timespec64_valid(tv)) 177 return -EINVAL; 178 179 error = security_settime64(tv, tz); 180 if (error) 181 return error; 182 183 if (tz) { 184 /* Verify we're witin the +-15 hrs range */ 185 if (tz->tz_minuteswest > 15*60 || tz->tz_minuteswest < -15*60) 186 return -EINVAL; 187 188 sys_tz = *tz; 189 update_vsyscall_tz(); 190 if (firsttime) { 191 firsttime = 0; 192 if (!tv) 193 timekeeping_warp_clock(); 194 } 195 } 196 if (tv) 197 return do_settimeofday64(tv); 198 return 0; 199 } 200 201 SYSCALL_DEFINE2(settimeofday, struct timeval __user *, tv, 202 struct timezone __user *, tz) 203 { 204 struct timespec64 new_ts; 205 struct timeval user_tv; 206 struct timezone new_tz; 207 208 if (tv) { 209 if (copy_from_user(&user_tv, tv, sizeof(*tv))) 210 return -EFAULT; 211 212 if (!timeval_valid(&user_tv)) 213 return -EINVAL; 214 215 new_ts.tv_sec = user_tv.tv_sec; 216 new_ts.tv_nsec = user_tv.tv_usec * NSEC_PER_USEC; 217 } 218 if (tz) { 219 if (copy_from_user(&new_tz, tz, sizeof(*tz))) 220 return -EFAULT; 221 } 222 223 return do_sys_settimeofday64(tv ? &new_ts : NULL, tz ? &new_tz : NULL); 224 } 225 226 #ifdef CONFIG_COMPAT 227 COMPAT_SYSCALL_DEFINE2(gettimeofday, struct compat_timeval __user *, tv, 228 struct timezone __user *, tz) 229 { 230 if (tv) { 231 struct timeval ktv; 232 233 do_gettimeofday(&ktv); 234 if (compat_put_timeval(&ktv, tv)) 235 return -EFAULT; 236 } 237 if (tz) { 238 if (copy_to_user(tz, &sys_tz, sizeof(sys_tz))) 239 return -EFAULT; 240 } 241 242 return 0; 243 } 244 245 COMPAT_SYSCALL_DEFINE2(settimeofday, struct compat_timeval __user *, tv, 246 struct timezone __user *, tz) 247 { 248 struct timespec64 new_ts; 249 struct timeval user_tv; 250 struct timezone new_tz; 251 252 if (tv) { 253 if (compat_get_timeval(&user_tv, tv)) 254 return -EFAULT; 255 new_ts.tv_sec = user_tv.tv_sec; 256 new_ts.tv_nsec = user_tv.tv_usec * NSEC_PER_USEC; 257 } 258 if (tz) { 259 if (copy_from_user(&new_tz, tz, sizeof(*tz))) 260 return -EFAULT; 261 } 262 263 return do_sys_settimeofday64(tv ? &new_ts : NULL, tz ? &new_tz : NULL); 264 } 265 #endif 266 267 SYSCALL_DEFINE1(adjtimex, struct timex __user *, txc_p) 268 { 269 struct timex txc; /* Local copy of parameter */ 270 int ret; 271 272 /* Copy the user data space into the kernel copy 273 * structure. But bear in mind that the structures 274 * may change 275 */ 276 if (copy_from_user(&txc, txc_p, sizeof(struct timex))) 277 return -EFAULT; 278 ret = do_adjtimex(&txc); 279 return copy_to_user(txc_p, &txc, sizeof(struct timex)) ? -EFAULT : ret; 280 } 281 282 #ifdef CONFIG_COMPAT 283 284 COMPAT_SYSCALL_DEFINE1(adjtimex, struct compat_timex __user *, utp) 285 { 286 struct timex txc; 287 int err, ret; 288 289 err = compat_get_timex(&txc, utp); 290 if (err) 291 return err; 292 293 ret = do_adjtimex(&txc); 294 295 err = compat_put_timex(utp, &txc); 296 if (err) 297 return err; 298 299 return ret; 300 } 301 #endif 302 303 /* 304 * Convert jiffies to milliseconds and back. 305 * 306 * Avoid unnecessary multiplications/divisions in the 307 * two most common HZ cases: 308 */ 309 unsigned int jiffies_to_msecs(const unsigned long j) 310 { 311 #if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ) 312 return (MSEC_PER_SEC / HZ) * j; 313 #elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC) 314 return (j + (HZ / MSEC_PER_SEC) - 1)/(HZ / MSEC_PER_SEC); 315 #else 316 # if BITS_PER_LONG == 32 317 return (HZ_TO_MSEC_MUL32 * j) >> HZ_TO_MSEC_SHR32; 318 # else 319 return (j * HZ_TO_MSEC_NUM) / HZ_TO_MSEC_DEN; 320 # endif 321 #endif 322 } 323 EXPORT_SYMBOL(jiffies_to_msecs); 324 325 unsigned int jiffies_to_usecs(const unsigned long j) 326 { 327 /* 328 * Hz usually doesn't go much further MSEC_PER_SEC. 329 * jiffies_to_usecs() and usecs_to_jiffies() depend on that. 330 */ 331 BUILD_BUG_ON(HZ > USEC_PER_SEC); 332 333 #if !(USEC_PER_SEC % HZ) 334 return (USEC_PER_SEC / HZ) * j; 335 #else 336 # if BITS_PER_LONG == 32 337 return (HZ_TO_USEC_MUL32 * j) >> HZ_TO_USEC_SHR32; 338 # else 339 return (j * HZ_TO_USEC_NUM) / HZ_TO_USEC_DEN; 340 # endif 341 #endif 342 } 343 EXPORT_SYMBOL(jiffies_to_usecs); 344 345 /** 346 * timespec_trunc - Truncate timespec to a granularity 347 * @t: Timespec 348 * @gran: Granularity in ns. 349 * 350 * Truncate a timespec to a granularity. Always rounds down. gran must 351 * not be 0 nor greater than a second (NSEC_PER_SEC, or 10^9 ns). 352 */ 353 struct timespec timespec_trunc(struct timespec t, unsigned gran) 354 { 355 /* Avoid division in the common cases 1 ns and 1 s. */ 356 if (gran == 1) { 357 /* nothing */ 358 } else if (gran == NSEC_PER_SEC) { 359 t.tv_nsec = 0; 360 } else if (gran > 1 && gran < NSEC_PER_SEC) { 361 t.tv_nsec -= t.tv_nsec % gran; 362 } else { 363 WARN(1, "illegal file time granularity: %u", gran); 364 } 365 return t; 366 } 367 EXPORT_SYMBOL(timespec_trunc); 368 369 /* 370 * mktime64 - Converts date to seconds. 371 * Converts Gregorian date to seconds since 1970-01-01 00:00:00. 372 * Assumes input in normal date format, i.e. 1980-12-31 23:59:59 373 * => year=1980, mon=12, day=31, hour=23, min=59, sec=59. 374 * 375 * [For the Julian calendar (which was used in Russia before 1917, 376 * Britain & colonies before 1752, anywhere else before 1582, 377 * and is still in use by some communities) leave out the 378 * -year/100+year/400 terms, and add 10.] 379 * 380 * This algorithm was first published by Gauss (I think). 381 * 382 * A leap second can be indicated by calling this function with sec as 383 * 60 (allowable under ISO 8601). The leap second is treated the same 384 * as the following second since they don't exist in UNIX time. 385 * 386 * An encoding of midnight at the end of the day as 24:00:00 - ie. midnight 387 * tomorrow - (allowable under ISO 8601) is supported. 388 */ 389 time64_t mktime64(const unsigned int year0, const unsigned int mon0, 390 const unsigned int day, const unsigned int hour, 391 const unsigned int min, const unsigned int sec) 392 { 393 unsigned int mon = mon0, year = year0; 394 395 /* 1..12 -> 11,12,1..10 */ 396 if (0 >= (int) (mon -= 2)) { 397 mon += 12; /* Puts Feb last since it has leap day */ 398 year -= 1; 399 } 400 401 return ((((time64_t) 402 (year/4 - year/100 + year/400 + 367*mon/12 + day) + 403 year*365 - 719499 404 )*24 + hour /* now have hours - midnight tomorrow handled here */ 405 )*60 + min /* now have minutes */ 406 )*60 + sec; /* finally seconds */ 407 } 408 EXPORT_SYMBOL(mktime64); 409 410 #if __BITS_PER_LONG == 32 411 /** 412 * set_normalized_timespec - set timespec sec and nsec parts and normalize 413 * 414 * @ts: pointer to timespec variable to be set 415 * @sec: seconds to set 416 * @nsec: nanoseconds to set 417 * 418 * Set seconds and nanoseconds field of a timespec variable and 419 * normalize to the timespec storage format 420 * 421 * Note: The tv_nsec part is always in the range of 422 * 0 <= tv_nsec < NSEC_PER_SEC 423 * For negative values only the tv_sec field is negative ! 424 */ 425 void set_normalized_timespec(struct timespec *ts, time_t sec, s64 nsec) 426 { 427 while (nsec >= NSEC_PER_SEC) { 428 /* 429 * The following asm() prevents the compiler from 430 * optimising this loop into a modulo operation. See 431 * also __iter_div_u64_rem() in include/linux/time.h 432 */ 433 asm("" : "+rm"(nsec)); 434 nsec -= NSEC_PER_SEC; 435 ++sec; 436 } 437 while (nsec < 0) { 438 asm("" : "+rm"(nsec)); 439 nsec += NSEC_PER_SEC; 440 --sec; 441 } 442 ts->tv_sec = sec; 443 ts->tv_nsec = nsec; 444 } 445 EXPORT_SYMBOL(set_normalized_timespec); 446 447 /** 448 * ns_to_timespec - Convert nanoseconds to timespec 449 * @nsec: the nanoseconds value to be converted 450 * 451 * Returns the timespec representation of the nsec parameter. 452 */ 453 struct timespec ns_to_timespec(const s64 nsec) 454 { 455 struct timespec ts; 456 s32 rem; 457 458 if (!nsec) 459 return (struct timespec) {0, 0}; 460 461 ts.tv_sec = div_s64_rem(nsec, NSEC_PER_SEC, &rem); 462 if (unlikely(rem < 0)) { 463 ts.tv_sec--; 464 rem += NSEC_PER_SEC; 465 } 466 ts.tv_nsec = rem; 467 468 return ts; 469 } 470 EXPORT_SYMBOL(ns_to_timespec); 471 #endif 472 473 /** 474 * ns_to_timeval - Convert nanoseconds to timeval 475 * @nsec: the nanoseconds value to be converted 476 * 477 * Returns the timeval representation of the nsec parameter. 478 */ 479 struct timeval ns_to_timeval(const s64 nsec) 480 { 481 struct timespec ts = ns_to_timespec(nsec); 482 struct timeval tv; 483 484 tv.tv_sec = ts.tv_sec; 485 tv.tv_usec = (suseconds_t) ts.tv_nsec / 1000; 486 487 return tv; 488 } 489 EXPORT_SYMBOL(ns_to_timeval); 490 491 struct __kernel_old_timeval ns_to_kernel_old_timeval(const s64 nsec) 492 { 493 struct timespec64 ts = ns_to_timespec64(nsec); 494 struct __kernel_old_timeval tv; 495 496 tv.tv_sec = ts.tv_sec; 497 tv.tv_usec = (suseconds_t)ts.tv_nsec / 1000; 498 499 return tv; 500 } 501 EXPORT_SYMBOL(ns_to_kernel_old_timeval); 502 503 /** 504 * set_normalized_timespec - set timespec sec and nsec parts and normalize 505 * 506 * @ts: pointer to timespec variable to be set 507 * @sec: seconds to set 508 * @nsec: nanoseconds to set 509 * 510 * Set seconds and nanoseconds field of a timespec variable and 511 * normalize to the timespec storage format 512 * 513 * Note: The tv_nsec part is always in the range of 514 * 0 <= tv_nsec < NSEC_PER_SEC 515 * For negative values only the tv_sec field is negative ! 516 */ 517 void set_normalized_timespec64(struct timespec64 *ts, time64_t sec, s64 nsec) 518 { 519 while (nsec >= NSEC_PER_SEC) { 520 /* 521 * The following asm() prevents the compiler from 522 * optimising this loop into a modulo operation. See 523 * also __iter_div_u64_rem() in include/linux/time.h 524 */ 525 asm("" : "+rm"(nsec)); 526 nsec -= NSEC_PER_SEC; 527 ++sec; 528 } 529 while (nsec < 0) { 530 asm("" : "+rm"(nsec)); 531 nsec += NSEC_PER_SEC; 532 --sec; 533 } 534 ts->tv_sec = sec; 535 ts->tv_nsec = nsec; 536 } 537 EXPORT_SYMBOL(set_normalized_timespec64); 538 539 /** 540 * ns_to_timespec64 - Convert nanoseconds to timespec64 541 * @nsec: the nanoseconds value to be converted 542 * 543 * Returns the timespec64 representation of the nsec parameter. 544 */ 545 struct timespec64 ns_to_timespec64(const s64 nsec) 546 { 547 struct timespec64 ts; 548 s32 rem; 549 550 if (!nsec) 551 return (struct timespec64) {0, 0}; 552 553 ts.tv_sec = div_s64_rem(nsec, NSEC_PER_SEC, &rem); 554 if (unlikely(rem < 0)) { 555 ts.tv_sec--; 556 rem += NSEC_PER_SEC; 557 } 558 ts.tv_nsec = rem; 559 560 return ts; 561 } 562 EXPORT_SYMBOL(ns_to_timespec64); 563 564 /** 565 * msecs_to_jiffies: - convert milliseconds to jiffies 566 * @m: time in milliseconds 567 * 568 * conversion is done as follows: 569 * 570 * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET) 571 * 572 * - 'too large' values [that would result in larger than 573 * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too. 574 * 575 * - all other values are converted to jiffies by either multiplying 576 * the input value by a factor or dividing it with a factor and 577 * handling any 32-bit overflows. 578 * for the details see __msecs_to_jiffies() 579 * 580 * msecs_to_jiffies() checks for the passed in value being a constant 581 * via __builtin_constant_p() allowing gcc to eliminate most of the 582 * code, __msecs_to_jiffies() is called if the value passed does not 583 * allow constant folding and the actual conversion must be done at 584 * runtime. 585 * the _msecs_to_jiffies helpers are the HZ dependent conversion 586 * routines found in include/linux/jiffies.h 587 */ 588 unsigned long __msecs_to_jiffies(const unsigned int m) 589 { 590 /* 591 * Negative value, means infinite timeout: 592 */ 593 if ((int)m < 0) 594 return MAX_JIFFY_OFFSET; 595 return _msecs_to_jiffies(m); 596 } 597 EXPORT_SYMBOL(__msecs_to_jiffies); 598 599 unsigned long __usecs_to_jiffies(const unsigned int u) 600 { 601 if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET)) 602 return MAX_JIFFY_OFFSET; 603 return _usecs_to_jiffies(u); 604 } 605 EXPORT_SYMBOL(__usecs_to_jiffies); 606 607 /* 608 * The TICK_NSEC - 1 rounds up the value to the next resolution. Note 609 * that a remainder subtract here would not do the right thing as the 610 * resolution values don't fall on second boundries. I.e. the line: 611 * nsec -= nsec % TICK_NSEC; is NOT a correct resolution rounding. 612 * Note that due to the small error in the multiplier here, this 613 * rounding is incorrect for sufficiently large values of tv_nsec, but 614 * well formed timespecs should have tv_nsec < NSEC_PER_SEC, so we're 615 * OK. 616 * 617 * Rather, we just shift the bits off the right. 618 * 619 * The >> (NSEC_JIFFIE_SC - SEC_JIFFIE_SC) converts the scaled nsec 620 * value to a scaled second value. 621 */ 622 static unsigned long 623 __timespec64_to_jiffies(u64 sec, long nsec) 624 { 625 nsec = nsec + TICK_NSEC - 1; 626 627 if (sec >= MAX_SEC_IN_JIFFIES){ 628 sec = MAX_SEC_IN_JIFFIES; 629 nsec = 0; 630 } 631 return ((sec * SEC_CONVERSION) + 632 (((u64)nsec * NSEC_CONVERSION) >> 633 (NSEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC; 634 635 } 636 637 static unsigned long 638 __timespec_to_jiffies(unsigned long sec, long nsec) 639 { 640 return __timespec64_to_jiffies((u64)sec, nsec); 641 } 642 643 unsigned long 644 timespec64_to_jiffies(const struct timespec64 *value) 645 { 646 return __timespec64_to_jiffies(value->tv_sec, value->tv_nsec); 647 } 648 EXPORT_SYMBOL(timespec64_to_jiffies); 649 650 void 651 jiffies_to_timespec64(const unsigned long jiffies, struct timespec64 *value) 652 { 653 /* 654 * Convert jiffies to nanoseconds and separate with 655 * one divide. 656 */ 657 u32 rem; 658 value->tv_sec = div_u64_rem((u64)jiffies * TICK_NSEC, 659 NSEC_PER_SEC, &rem); 660 value->tv_nsec = rem; 661 } 662 EXPORT_SYMBOL(jiffies_to_timespec64); 663 664 /* 665 * We could use a similar algorithm to timespec_to_jiffies (with a 666 * different multiplier for usec instead of nsec). But this has a 667 * problem with rounding: we can't exactly add TICK_NSEC - 1 to the 668 * usec value, since it's not necessarily integral. 669 * 670 * We could instead round in the intermediate scaled representation 671 * (i.e. in units of 1/2^(large scale) jiffies) but that's also 672 * perilous: the scaling introduces a small positive error, which 673 * combined with a division-rounding-upward (i.e. adding 2^(scale) - 1 674 * units to the intermediate before shifting) leads to accidental 675 * overflow and overestimates. 676 * 677 * At the cost of one additional multiplication by a constant, just 678 * use the timespec implementation. 679 */ 680 unsigned long 681 timeval_to_jiffies(const struct timeval *value) 682 { 683 return __timespec_to_jiffies(value->tv_sec, 684 value->tv_usec * NSEC_PER_USEC); 685 } 686 EXPORT_SYMBOL(timeval_to_jiffies); 687 688 void jiffies_to_timeval(const unsigned long jiffies, struct timeval *value) 689 { 690 /* 691 * Convert jiffies to nanoseconds and separate with 692 * one divide. 693 */ 694 u32 rem; 695 696 value->tv_sec = div_u64_rem((u64)jiffies * TICK_NSEC, 697 NSEC_PER_SEC, &rem); 698 value->tv_usec = rem / NSEC_PER_USEC; 699 } 700 EXPORT_SYMBOL(jiffies_to_timeval); 701 702 /* 703 * Convert jiffies/jiffies_64 to clock_t and back. 704 */ 705 clock_t jiffies_to_clock_t(unsigned long x) 706 { 707 #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0 708 # if HZ < USER_HZ 709 return x * (USER_HZ / HZ); 710 # else 711 return x / (HZ / USER_HZ); 712 # endif 713 #else 714 return div_u64((u64)x * TICK_NSEC, NSEC_PER_SEC / USER_HZ); 715 #endif 716 } 717 EXPORT_SYMBOL(jiffies_to_clock_t); 718 719 unsigned long clock_t_to_jiffies(unsigned long x) 720 { 721 #if (HZ % USER_HZ)==0 722 if (x >= ~0UL / (HZ / USER_HZ)) 723 return ~0UL; 724 return x * (HZ / USER_HZ); 725 #else 726 /* Don't worry about loss of precision here .. */ 727 if (x >= ~0UL / HZ * USER_HZ) 728 return ~0UL; 729 730 /* .. but do try to contain it here */ 731 return div_u64((u64)x * HZ, USER_HZ); 732 #endif 733 } 734 EXPORT_SYMBOL(clock_t_to_jiffies); 735 736 u64 jiffies_64_to_clock_t(u64 x) 737 { 738 #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0 739 # if HZ < USER_HZ 740 x = div_u64(x * USER_HZ, HZ); 741 # elif HZ > USER_HZ 742 x = div_u64(x, HZ / USER_HZ); 743 # else 744 /* Nothing to do */ 745 # endif 746 #else 747 /* 748 * There are better ways that don't overflow early, 749 * but even this doesn't overflow in hundreds of years 750 * in 64 bits, so.. 751 */ 752 x = div_u64(x * TICK_NSEC, (NSEC_PER_SEC / USER_HZ)); 753 #endif 754 return x; 755 } 756 EXPORT_SYMBOL(jiffies_64_to_clock_t); 757 758 u64 nsec_to_clock_t(u64 x) 759 { 760 #if (NSEC_PER_SEC % USER_HZ) == 0 761 return div_u64(x, NSEC_PER_SEC / USER_HZ); 762 #elif (USER_HZ % 512) == 0 763 return div_u64(x * USER_HZ / 512, NSEC_PER_SEC / 512); 764 #else 765 /* 766 * max relative error 5.7e-8 (1.8s per year) for USER_HZ <= 1024, 767 * overflow after 64.99 years. 768 * exact for HZ=60, 72, 90, 120, 144, 180, 300, 600, 900, ... 769 */ 770 return div_u64(x * 9, (9ull * NSEC_PER_SEC + (USER_HZ / 2)) / USER_HZ); 771 #endif 772 } 773 774 u64 jiffies64_to_nsecs(u64 j) 775 { 776 #if !(NSEC_PER_SEC % HZ) 777 return (NSEC_PER_SEC / HZ) * j; 778 # else 779 return div_u64(j * HZ_TO_NSEC_NUM, HZ_TO_NSEC_DEN); 780 #endif 781 } 782 EXPORT_SYMBOL(jiffies64_to_nsecs); 783 784 /** 785 * nsecs_to_jiffies64 - Convert nsecs in u64 to jiffies64 786 * 787 * @n: nsecs in u64 788 * 789 * Unlike {m,u}secs_to_jiffies, type of input is not unsigned int but u64. 790 * And this doesn't return MAX_JIFFY_OFFSET since this function is designed 791 * for scheduler, not for use in device drivers to calculate timeout value. 792 * 793 * note: 794 * NSEC_PER_SEC = 10^9 = (5^9 * 2^9) = (1953125 * 512) 795 * ULLONG_MAX ns = 18446744073.709551615 secs = about 584 years 796 */ 797 u64 nsecs_to_jiffies64(u64 n) 798 { 799 #if (NSEC_PER_SEC % HZ) == 0 800 /* Common case, HZ = 100, 128, 200, 250, 256, 500, 512, 1000 etc. */ 801 return div_u64(n, NSEC_PER_SEC / HZ); 802 #elif (HZ % 512) == 0 803 /* overflow after 292 years if HZ = 1024 */ 804 return div_u64(n * HZ / 512, NSEC_PER_SEC / 512); 805 #else 806 /* 807 * Generic case - optimized for cases where HZ is a multiple of 3. 808 * overflow after 64.99 years, exact for HZ = 60, 72, 90, 120 etc. 809 */ 810 return div_u64(n * 9, (9ull * NSEC_PER_SEC + HZ / 2) / HZ); 811 #endif 812 } 813 EXPORT_SYMBOL(nsecs_to_jiffies64); 814 815 /** 816 * nsecs_to_jiffies - Convert nsecs in u64 to jiffies 817 * 818 * @n: nsecs in u64 819 * 820 * Unlike {m,u}secs_to_jiffies, type of input is not unsigned int but u64. 821 * And this doesn't return MAX_JIFFY_OFFSET since this function is designed 822 * for scheduler, not for use in device drivers to calculate timeout value. 823 * 824 * note: 825 * NSEC_PER_SEC = 10^9 = (5^9 * 2^9) = (1953125 * 512) 826 * ULLONG_MAX ns = 18446744073.709551615 secs = about 584 years 827 */ 828 unsigned long nsecs_to_jiffies(u64 n) 829 { 830 return (unsigned long)nsecs_to_jiffies64(n); 831 } 832 EXPORT_SYMBOL_GPL(nsecs_to_jiffies); 833 834 /* 835 * Add two timespec64 values and do a safety check for overflow. 836 * It's assumed that both values are valid (>= 0). 837 * And, each timespec64 is in normalized form. 838 */ 839 struct timespec64 timespec64_add_safe(const struct timespec64 lhs, 840 const struct timespec64 rhs) 841 { 842 struct timespec64 res; 843 844 set_normalized_timespec64(&res, (timeu64_t) lhs.tv_sec + rhs.tv_sec, 845 lhs.tv_nsec + rhs.tv_nsec); 846 847 if (unlikely(res.tv_sec < lhs.tv_sec || res.tv_sec < rhs.tv_sec)) { 848 res.tv_sec = TIME64_MAX; 849 res.tv_nsec = 0; 850 } 851 852 return res; 853 } 854 855 int get_timespec64(struct timespec64 *ts, 856 const struct timespec __user *uts) 857 { 858 struct timespec kts; 859 int ret; 860 861 ret = copy_from_user(&kts, uts, sizeof(kts)); 862 if (ret) 863 return -EFAULT; 864 865 ts->tv_sec = kts.tv_sec; 866 ts->tv_nsec = kts.tv_nsec; 867 868 return 0; 869 } 870 EXPORT_SYMBOL_GPL(get_timespec64); 871 872 int put_timespec64(const struct timespec64 *ts, 873 struct timespec __user *uts) 874 { 875 struct timespec kts = { 876 .tv_sec = ts->tv_sec, 877 .tv_nsec = ts->tv_nsec 878 }; 879 return copy_to_user(uts, &kts, sizeof(kts)) ? -EFAULT : 0; 880 } 881 EXPORT_SYMBOL_GPL(put_timespec64); 882 883 int get_itimerspec64(struct itimerspec64 *it, 884 const struct itimerspec __user *uit) 885 { 886 int ret; 887 888 ret = get_timespec64(&it->it_interval, &uit->it_interval); 889 if (ret) 890 return ret; 891 892 ret = get_timespec64(&it->it_value, &uit->it_value); 893 894 return ret; 895 } 896 EXPORT_SYMBOL_GPL(get_itimerspec64); 897 898 int put_itimerspec64(const struct itimerspec64 *it, 899 struct itimerspec __user *uit) 900 { 901 int ret; 902 903 ret = put_timespec64(&it->it_interval, &uit->it_interval); 904 if (ret) 905 return ret; 906 907 ret = put_timespec64(&it->it_value, &uit->it_value); 908 909 return ret; 910 } 911 EXPORT_SYMBOL_GPL(put_itimerspec64); 912