projects / apple / xnu.git / blame
| Commit | Line | Data |
|---|---|---|
| 39037602 A |
1 | /* |
| 2 | * Copyright (c) 2015 Apple Inc. All rights reserved. | |
| 3 | * | |
| 4 | * @APPLE_LICENSE_HEADER_START@ | |
| 5 | * | |
| 6 | * This file contains Original Code and/or Modifications of Original Code | |
| 7 | * as defined in and that are subject to the Apple Public Source License | |
| 8 | * Version 2.0 (the 'License'). You may not use this file except in | |
| 9 | * compliance with the License. Please obtain a copy of the License at | |
| 10 | * http://www.opensource.apple.com/apsl/ and read it before using this | |
| 11 | * file. | |
| 12 | * | |
| 13 | * The Original Code and all software distributed under the License are | |
| 14 | * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER | |
| 15 | * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, | |
| 16 | * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, | |
| 17 | * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. | |
| 18 | * Please see the License for the specific language governing rights and | |
| 19 | * limitations under the License. | |
| 20 | * | |
| 21 | * @APPLE_LICENSE_HEADER_END@ | |
| 22 | */ | |
| 23 | #include <stdbool.h> | |
| 24 | #include <sys/types.h> | |
| 25 | #include <sys/time.h> | |
| 26 | #include <mach/mach_time.h> | |
| 27 | #include <sys/time.h> | |
| 28 | #include <machine/cpu_capabilities.h> | |
| 29 | ||
| 30 | // From __commpage_gettimeofday.c | |
| 31 | extern int __commpage_gettimeofday_internal(struct timeval *tp, uint64_t *tbr_out); | |
| 32 | extern kern_return_t _mach_continuous_time(uint64_t* absolute_time, uint64_t* cont_time); | |
| 33 | // From mach_continuous_time.c | |
| 34 | extern uint64_t _mach_continuous_time_base(void); | |
| 35 | // Underlying syscall stub | |
| 36 | extern int __gettimeofday_with_mach(struct timeval *, struct timezone *, uint64_t *); | |
| 37 | ||
| 38 | kern_return_t | |
| 39 | mach_get_times(uint64_t* absolute_time, uint64_t* cont_time, struct timespec *tp) { | |
| 40 | if (tp == NULL) { | |
| 41 | return _mach_continuous_time(absolute_time, cont_time); | |
| 42 | } | |
| 43 | ||
| 44 | uint64_t continuous_time_base_prior = -1, continuous_time_base_post = -1; | |
| 45 | uint64_t tbr; | |
| 46 | struct timeval tv; | |
| 47 | ||
| 48 | do { | |
| 49 | /* | |
| 50 | * We need to capture the result of gettimeofday without our continuous | |
| 51 | * time base changing. Once we have that, and the value for absolute | |
| 52 | * time that was used to compute the timespec, we can just add the base | |
| 53 | * to get the accompanying continuous time. | |
| 54 | */ | |
| 55 | continuous_time_base_prior = _mach_continuous_time_base(); | |
| 56 | ||
| 57 | /* | |
| 58 | * This call has the necessary memory barriers for this retry loop, | |
| 59 | * since it is implemented with a retry loop of its own. | |
| 60 | */ | |
| 61 | if (__commpage_gettimeofday_internal(&tv, &tbr)) { | |
| 62 | tbr = 0; | |
| 63 | if (__gettimeofday_with_mach(&tv, NULL, &tbr) < 0) { | |
| 64 | return KERN_FAILURE; | |
| 65 | } else if (tbr == 0) { | |
| 66 | // On an old kernel, likely chroot'ed. (remove next year) | |
| 67 | tbr = mach_absolute_time(); | |
| 68 | } | |
| 69 | } | |
| 70 | ||
| 71 | continuous_time_base_post = _mach_continuous_time_base(); | |
| 72 | } while (__builtin_expect(continuous_time_base_prior != continuous_time_base_post, 0)); | |
| 73 | ||
| 74 | if (absolute_time) *absolute_time = tbr; | |
| 75 | if (cont_time) *cont_time = continuous_time_base_prior + tbr; | |
| 76 | tp->tv_sec = tv.tv_sec; | |
| 77 | tp->tv_nsec = tv.tv_usec * NSEC_PER_USEC; | |
| 78 | ||
| 79 | return KERN_SUCCESS; | |
| 80 | } |