| 1 | /* |
| 2 | * Copyright (C) 2010 Pierre-Marc Fournier |
| 3 | * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 4 | * |
| 5 | * SPDX-License-Identifier: GPL-2.0-only |
| 6 | * |
| 7 | */ |
| 8 | |
| 9 | #ifndef _UST_CLOCK_H |
| 10 | #define _UST_CLOCK_H |
| 11 | |
| 12 | #include <common/compat/time.h> |
| 13 | #include <sys/time.h> |
| 14 | #include <stdint.h> |
| 15 | #include <stddef.h> |
| 16 | #include <stdio.h> |
| 17 | #include <urcu/system.h> |
| 18 | #include <urcu/arch.h> |
| 19 | #include <lttng/ust-clock.h> |
| 20 | |
| 21 | #include <common/uuid.h> |
| 22 | |
| 23 | /* TRACE CLOCK */ |
| 24 | |
| 25 | struct lttng_trace_clock { |
| 26 | uint64_t (*read64)(void); |
| 27 | uint64_t (*freq)(void); |
| 28 | int (*uuid)(char *uuid); |
| 29 | const char *(*name)(void); |
| 30 | const char *(*description)(void); |
| 31 | }; |
| 32 | |
| 33 | extern struct lttng_trace_clock *lttng_trace_clock; |
| 34 | |
| 35 | void lttng_ust_clock_init(void); |
| 36 | |
| 37 | /* |
| 38 | * Currently using the kernel MONOTONIC clock, waiting for kernel-side |
| 39 | * LTTng to implement mmap'd trace clock. |
| 40 | */ |
| 41 | |
| 42 | /* Choosing correct trace clock */ |
| 43 | |
| 44 | static __inline__ |
| 45 | uint64_t trace_clock_read64_monotonic(void) |
| 46 | { |
| 47 | struct timespec ts; |
| 48 | |
| 49 | if (lttng_clock_gettime(CLOCK_MONOTONIC, &ts)) { |
| 50 | /* TODO Report error cleanly up the chain. */ |
| 51 | PERROR("clock_gettime CLOCK_MONOTONIC"); |
| 52 | ts.tv_sec = 0; |
| 53 | ts.tv_nsec = 0; |
| 54 | } |
| 55 | return ((uint64_t) ts.tv_sec * 1000000000ULL) + ts.tv_nsec; |
| 56 | } |
| 57 | |
| 58 | static __inline__ |
| 59 | uint64_t trace_clock_freq_monotonic(void) |
| 60 | { |
| 61 | return 1000000000ULL; |
| 62 | } |
| 63 | |
| 64 | static __inline__ |
| 65 | int trace_clock_uuid_monotonic(char *uuid) |
| 66 | { |
| 67 | int ret = 0; |
| 68 | size_t len; |
| 69 | FILE *fp; |
| 70 | |
| 71 | /* |
| 72 | * boot_id needs to be read once before being used concurrently |
| 73 | * to deal with a Linux kernel race. A fix is proposed for |
| 74 | * upstream, but the work-around is needed for older kernels. |
| 75 | */ |
| 76 | fp = fopen("/proc/sys/kernel/random/boot_id", "r"); |
| 77 | if (!fp) { |
| 78 | return -ENOENT; |
| 79 | } |
| 80 | len = fread(uuid, 1, LTTNG_UST_UUID_STR_LEN - 1, fp); |
| 81 | if (len < LTTNG_UST_UUID_STR_LEN - 1) { |
| 82 | ret = -EINVAL; |
| 83 | goto end; |
| 84 | } |
| 85 | uuid[LTTNG_UST_UUID_STR_LEN - 1] = '\0'; |
| 86 | end: |
| 87 | fclose(fp); |
| 88 | return ret; |
| 89 | } |
| 90 | |
| 91 | static __inline__ |
| 92 | const char *trace_clock_name_monotonic(void) |
| 93 | { |
| 94 | return "monotonic"; |
| 95 | } |
| 96 | |
| 97 | static __inline__ |
| 98 | const char *trace_clock_description_monotonic(void) |
| 99 | { |
| 100 | return "Monotonic Clock"; |
| 101 | } |
| 102 | |
| 103 | static __inline__ |
| 104 | uint64_t trace_clock_read64(void) |
| 105 | { |
| 106 | struct lttng_trace_clock *ltc = CMM_LOAD_SHARED(lttng_trace_clock); |
| 107 | |
| 108 | if (caa_likely(!ltc)) { |
| 109 | return trace_clock_read64_monotonic(); |
| 110 | } else { |
| 111 | cmm_read_barrier_depends(); /* load ltc before content */ |
| 112 | return ltc->read64(); |
| 113 | } |
| 114 | } |
| 115 | |
| 116 | static __inline__ |
| 117 | uint64_t trace_clock_freq(void) |
| 118 | { |
| 119 | struct lttng_trace_clock *ltc = CMM_LOAD_SHARED(lttng_trace_clock); |
| 120 | |
| 121 | if (!ltc) { |
| 122 | return trace_clock_freq_monotonic(); |
| 123 | } else { |
| 124 | cmm_read_barrier_depends(); /* load ltc before content */ |
| 125 | return ltc->freq(); |
| 126 | } |
| 127 | } |
| 128 | |
| 129 | static __inline__ |
| 130 | int trace_clock_uuid(char *uuid) |
| 131 | { |
| 132 | struct lttng_trace_clock *ltc = CMM_LOAD_SHARED(lttng_trace_clock); |
| 133 | |
| 134 | cmm_read_barrier_depends(); /* load ltc before content */ |
| 135 | /* Use default UUID cb when NULL */ |
| 136 | if (!ltc || !ltc->uuid) { |
| 137 | return trace_clock_uuid_monotonic(uuid); |
| 138 | } else { |
| 139 | return ltc->uuid(uuid); |
| 140 | } |
| 141 | } |
| 142 | |
| 143 | static __inline__ |
| 144 | const char *trace_clock_name(void) |
| 145 | { |
| 146 | struct lttng_trace_clock *ltc = CMM_LOAD_SHARED(lttng_trace_clock); |
| 147 | |
| 148 | if (!ltc) { |
| 149 | return trace_clock_name_monotonic(); |
| 150 | } else { |
| 151 | cmm_read_barrier_depends(); /* load ltc before content */ |
| 152 | return ltc->name(); |
| 153 | } |
| 154 | } |
| 155 | |
| 156 | static __inline__ |
| 157 | const char *trace_clock_description(void) |
| 158 | { |
| 159 | struct lttng_trace_clock *ltc = CMM_LOAD_SHARED(lttng_trace_clock); |
| 160 | |
| 161 | if (!ltc) { |
| 162 | return trace_clock_description_monotonic(); |
| 163 | } else { |
| 164 | cmm_read_barrier_depends(); /* load ltc before content */ |
| 165 | return ltc->description(); |
| 166 | } |
| 167 | } |
| 168 | |
| 169 | #endif /* _UST_CLOCK_H */ |