liblttng-ust/lttng-clock.c

   1 /*
   2  * Copyright (C) 2014  Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; version 2.1 of
   7  * the License.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with this library; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
  17  */
  18
  19 #define _GNU_SOURCE
  20 #include <error.h>
  21 #include <dlfcn.h>
  22 #include <stdlib.h>
  23 #include <usterr-signal-safe.h>
  24 #include <lttng/ust-clock.h>
  25 #include <urcu/system.h>
  26 #include <urcu/arch.h>
  27
  28 #include "clock.h"
  29
  30 struct lttng_trace_clock *lttng_trace_clock;
  31
  32 static
  33 struct lttng_trace_clock user_tc;
  34
  35 int lttng_ust_trace_clock_set_read64_cb(uint64_t (*read64)(void))
  36 {
  37         if (CMM_LOAD_SHARED(lttng_trace_clock))
  38                 return -EBUSY;
  39         user_tc.read64 = read64;
  40         return 0;
  41 }
  42
  43 int lttng_ust_trace_clock_set_freq_cb(uint64_t (*freq)(void))
  44 {
  45         if (CMM_LOAD_SHARED(lttng_trace_clock))
  46                 return -EBUSY;
  47         user_tc.freq = freq;
  48         return 0;
  49 }
  50
  51 int lttng_ust_trace_clock_set_uuid_cb(int (*uuid)(char *uuid))
  52 {
  53         if (CMM_LOAD_SHARED(lttng_trace_clock))
  54                 return -EBUSY;
  55         user_tc.uuid = uuid;
  56         return 0;
  57 }
  58
  59 int lttng_ust_trace_clock_set_name_cb(const char *(*name)(void))
  60 {
  61         if (CMM_LOAD_SHARED(lttng_trace_clock))
  62                 return -EBUSY;
  63         user_tc.name = name;
  64         return 0;
  65 }
  66
  67 int lttng_ust_trace_clock_set_description_cb(const char *(*description)(void))
  68 {
  69         if (CMM_LOAD_SHARED(lttng_trace_clock))
  70                 return -EBUSY;
  71         user_tc.description = description;
  72         return 0;
  73 }
  74
  75 int lttng_ust_enable_trace_clock_override(void)
  76 {
  77         if (CMM_LOAD_SHARED(lttng_trace_clock))
  78                 return -EBUSY;
  79         if (!user_tc.read64)
  80                 return -EINVAL;
  81         if (!user_tc.freq)
  82                 return -EINVAL;
  83         if (!user_tc.name)
  84                 return -EINVAL;
  85         if (!user_tc.description)
  86                 return -EINVAL;
  87         /* Use default uuid cb when NULL */
  88         cmm_smp_mb();   /* Store callbacks before trace clock */
  89         CMM_STORE_SHARED(lttng_trace_clock, &user_tc);
  90         return 0;
  91 }
  92
  93 void lttng_ust_clock_init(void)
  94 {
  95         const char *libname;
  96         void *handle;
  97         void (*libinit)(void);
  98
  99
 100         libname = secure_getenv("LTTNG_UST_CLOCK_PLUGIN");
 101         if (!libname)
 102                 return;
 103         handle = dlopen(libname, RTLD_NOW);
 104         if (!handle) {
 105                 PERROR("Cannot load LTTng UST clock override library %s",
 106                         libname);
 107                 return;
 108         }
 109         dlerror();
 110         libinit = (void (*)(void)) dlsym(handle,
 111                 "lttng_ust_clock_plugin_init");
 112         if (!libinit) {
 113                 PERROR("Cannot find LTTng UST clock override library %s initialization function lttng_ust_clock_plugin_init()",
 114                         libname);
 115                 return;
 116         }
 117         libinit();
 118 }