liblttng-ust/lttng-clock.c

   1 /*
   2  * SPDX-License-Identifier: LGPL-2.1-only
   3  *
   4  * Copyright (C) 2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  */
   6
   7 #define _LGPL_SOURCE
   8 #include <error.h>
   9 #include <dlfcn.h>
  10 #include <stdlib.h>
  11 #include <stdint.h>
  12 #include <usterr-signal-safe.h>
  13 #include <lttng/ust-clock.h>
  14 #include <urcu/system.h>
  15 #include <urcu/arch.h>
  16
  17 #include "clock.h"
  18 #include "getenv.h"
  19
  20 struct lttng_trace_clock *lttng_trace_clock;
  21
  22 static
  23 struct lttng_trace_clock user_tc;
  24
  25 static
  26 void *clock_handle;
  27
  28 int lttng_ust_trace_clock_set_read64_cb(uint64_t (*read64)(void))
  29 {
  30         if (CMM_LOAD_SHARED(lttng_trace_clock))
  31                 return -EBUSY;
  32         user_tc.read64 = read64;
  33         return 0;
  34 }
  35
  36 int lttng_ust_trace_clock_set_freq_cb(uint64_t (*freq)(void))
  37 {
  38         if (CMM_LOAD_SHARED(lttng_trace_clock))
  39                 return -EBUSY;
  40         user_tc.freq = freq;
  41         return 0;
  42 }
  43
  44 int lttng_ust_trace_clock_set_uuid_cb(int (*uuid)(char *uuid))
  45 {
  46         if (CMM_LOAD_SHARED(lttng_trace_clock))
  47                 return -EBUSY;
  48         user_tc.uuid = uuid;
  49         return 0;
  50 }
  51
  52 int lttng_ust_trace_clock_set_name_cb(const char *(*name)(void))
  53 {
  54         if (CMM_LOAD_SHARED(lttng_trace_clock))
  55                 return -EBUSY;
  56         user_tc.name = name;
  57         return 0;
  58 }
  59
  60 int lttng_ust_trace_clock_set_description_cb(const char *(*description)(void))
  61 {
  62         if (CMM_LOAD_SHARED(lttng_trace_clock))
  63                 return -EBUSY;
  64         user_tc.description = description;
  65         return 0;
  66 }
  67
  68 int lttng_ust_enable_trace_clock_override(void)
  69 {
  70         if (CMM_LOAD_SHARED(lttng_trace_clock))
  71                 return -EBUSY;
  72         if (!user_tc.read64)
  73                 return -EINVAL;
  74         if (!user_tc.freq)
  75                 return -EINVAL;
  76         if (!user_tc.name)
  77                 return -EINVAL;
  78         if (!user_tc.description)
  79                 return -EINVAL;
  80         /* Use default uuid cb when NULL */
  81         cmm_smp_mb();   /* Store callbacks before trace clock */
  82         CMM_STORE_SHARED(lttng_trace_clock, &user_tc);
  83         return 0;
  84 }
  85
  86 void lttng_ust_clock_init(void)
  87 {
  88         const char *libname;
  89         void (*libinit)(void);
  90
  91         if (clock_handle)
  92                 return;
  93         libname = lttng_getenv("LTTNG_UST_CLOCK_PLUGIN");
  94         if (!libname)
  95                 return;
  96         clock_handle = dlopen(libname, RTLD_NOW);
  97         if (!clock_handle) {
  98                 PERROR("Cannot load LTTng UST clock override library %s",
  99                         libname);
 100                 return;
 101         }
 102         dlerror();
 103         libinit = (void (*)(void)) dlsym(clock_handle,
 104                 "lttng_ust_clock_plugin_init");
 105         if (!libinit) {
 106                 PERROR("Cannot find LTTng UST clock override library %s initialization function lttng_ust_clock_plugin_init()",
 107                         libname);
 108                 return;
 109         }
 110         libinit();
 111 }