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 #include "getenv.h"
  30
  31 struct lttng_trace_clock *lttng_trace_clock;
  32
  33 static
  34 struct lttng_trace_clock user_tc;
  35
  36 int lttng_ust_trace_clock_set_read64_cb(uint64_t (*read64)(void))
  37 {
  38         if (CMM_LOAD_SHARED(lttng_trace_clock))
  39                 return -EBUSY;
  40         user_tc.read64 = read64;
  41         return 0;
  42 }
  43
  44 int lttng_ust_trace_clock_set_freq_cb(uint64_t (*freq)(void))
  45 {
  46         if (CMM_LOAD_SHARED(lttng_trace_clock))
  47                 return -EBUSY;
  48         user_tc.freq = freq;
  49         return 0;
  50 }
  51
  52 int lttng_ust_trace_clock_set_uuid_cb(int (*uuid)(char *uuid))
  53 {
  54         if (CMM_LOAD_SHARED(lttng_trace_clock))
  55                 return -EBUSY;
  56         user_tc.uuid = uuid;
  57         return 0;
  58 }
  59
  60 int lttng_ust_trace_clock_set_name_cb(const char *(*name)(void))
  61 {
  62         if (CMM_LOAD_SHARED(lttng_trace_clock))
  63                 return -EBUSY;
  64         user_tc.name = name;
  65         return 0;
  66 }
  67
  68 int lttng_ust_trace_clock_set_description_cb(const char *(*description)(void))
  69 {
  70         if (CMM_LOAD_SHARED(lttng_trace_clock))
  71                 return -EBUSY;
  72         user_tc.description = description;
  73         return 0;
  74 }
  75
  76 int lttng_ust_enable_trace_clock_override(void)
  77 {
  78         if (CMM_LOAD_SHARED(lttng_trace_clock))
  79                 return -EBUSY;
  80         if (!user_tc.read64)
  81                 return -EINVAL;
  82         if (!user_tc.freq)
  83                 return -EINVAL;
  84         if (!user_tc.name)
  85                 return -EINVAL;
  86         if (!user_tc.description)
  87                 return -EINVAL;
  88         /* Use default uuid cb when NULL */
  89         cmm_smp_mb();   /* Store callbacks before trace clock */
  90         CMM_STORE_SHARED(lttng_trace_clock, &user_tc);
  91         return 0;
  92 }
  93
  94 void lttng_ust_clock_init(void)
  95 {
  96         const char *libname;
  97         void *handle;
  98         void (*libinit)(void);
  99
 100
 101         libname = lttng_secure_getenv("LTTNG_UST_CLOCK_PLUGIN");
 102         if (!libname)
 103                 return;
 104         handle = dlopen(libname, RTLD_NOW);
 105         if (!handle) {
 106                 PERROR("Cannot load LTTng UST clock override library %s",
 107                         libname);
 108                 return;
 109         }
 110         dlerror();
 111         libinit = (void (*)(void)) dlsym(handle,
 112                 "lttng_ust_clock_plugin_init");
 113         if (!libinit) {
 114                 PERROR("Cannot find LTTng UST clock override library %s initialization function lttng_ust_clock_plugin_init()",
 115                         libname);
 116                 return;
 117         }
 118         libinit();
 119 }