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 <stddef.h> | |
| 24 | #include <stdbool.h> | |
| 25 | #include <sys/types.h> | |
| 26 | #include <machine/cpu_capabilities.h> | |
| 27 | #include <mach/mach_time.h> | |
| 28 | ||
| 29 | __attribute__((visibility("hidden"))) | |
| 30 | uint64_t | |
| 31 | _mach_continuous_time_base(void) | |
| 32 | { | |
| 33 | #if !defined(__x86_64__) && !defined(__arm64__) | |
| 34 | // Deal with the lack of 64-bit loads on arm32 (see mach_approximate_time.s) | |
| 35 | while(1) { | |
| 36 | volatile uint64_t *base_ptr = (volatile uint64_t*)_COMM_PAGE_CONT_TIMEBASE; | |
| 37 | uint64_t read1, read2; | |
| 38 | read1 = *base_ptr; | |
| 39 | #if defined(__i386__) | |
| 40 | __asm__ volatile("lfence" ::: "memory"); | |
| 41 | #else | |
| 42 | #error "unsupported arch" | |
| 43 | #endif | |
| 44 | read2 = *base_ptr; | |
| 45 | ||
| 46 | if(__builtin_expect((read1 == read2), 1)) | |
| 47 | return read1; | |
| 48 | } | |
| 49 | #else // 64-bit | |
| 50 | return *(volatile uint64_t*)_COMM_PAGE_CONT_TIMEBASE; | |
| 51 | #endif // 64-bit | |
| 52 | } | |
| 53 | ||
| 54 | ||
| 55 | __attribute__((visibility("hidden"))) | |
| 56 | kern_return_t | |
| 57 | _mach_continuous_time(uint64_t* absolute_time, uint64_t* cont_time) | |
| 58 | { | |
| 59 | volatile uint64_t *base_ptr = (volatile uint64_t*)_COMM_PAGE_CONT_TIMEBASE; | |
| 60 | volatile uint64_t read1, read2; | |
| 61 | volatile uint64_t absolute; | |
| 62 | ||
| 63 | do { | |
| 64 | read1 = *base_ptr; | |
| 65 | absolute = mach_absolute_time(); | |
| 66 | read2 = *base_ptr; | |
| 67 | } while (__builtin_expect((read1 != read2), 0)); | |
| 68 | ||
| 69 | if (absolute_time) *absolute_time = absolute; | |
| 70 | if (cont_time) *cont_time = absolute + read1; | |
| 71 | ||
| 72 | return KERN_SUCCESS; | |
| 73 | } | |
| 74 | ||
| 75 | uint64_t | |
| 76 | mach_continuous_time(void) | |
| 77 | { | |
| 78 | uint64_t cont_time; | |
| 79 | _mach_continuous_time(NULL, &cont_time); | |
| 80 | return cont_time; | |
| 81 | } | |
| 82 | ||
| 83 | uint64_t | |
| 84 | mach_continuous_approximate_time(void) | |
| 85 | { | |
| 86 | /* | |
| 87 | * No retry loop here because if we use a slightly too old timebase that's | |
| 88 | * okay, we are approximate time anyway. | |
| 89 | */ | |
| 90 | volatile register uint64_t time_base = _mach_continuous_time_base(); | |
| 91 | return time_base + mach_approximate_time(); | |
| 92 | } |