liblttng-ust-baddr/lttng-ust-baddr.c

   1 /*
   2  * Copyright (C) 2013  Paul Woegerer <paul_woegerer@mentor.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; either
   7  * version 2.1 of the License, or (at your option) any later version.
   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 <dlfcn.h>
  21 #include <link.h>
  22
  23 #include <sys/types.h>
  24 #include <sys/stat.h>
  25 #include <unistd.h>
  26 #include <limits.h>
  27 #include <stdlib.h>
  28 #include <errno.h>
  29 #include <stdint.h>
  30 #include <stddef.h>
  31 #include <stdio.h>
  32 #include "usterr.h"
  33
  34 #include "lttng-ust-baddr.h"
  35
  36 #define TRACEPOINT_DEFINE
  37 #include "ust_baddr_statedump.h"
  38
  39 static int
  40 extract_soinfo_events(struct dl_phdr_info *info, size_t size, void *data)
  41 {
  42         int j;
  43         int num_loadable_segment = 0;
  44
  45         for (j = 0; j < info->dlpi_phnum; j++) {
  46                 char resolved_path[PATH_MAX];
  47                 struct stat sostat;
  48                 void *base_addr_ptr;
  49
  50                 if (info->dlpi_phdr[j].p_type != PT_LOAD)
  51                         continue;
  52
  53                 /* Calculate virtual memory address of the loadable segment */
  54                 base_addr_ptr = (void *) info->dlpi_addr
  55                         + info->dlpi_phdr[j].p_vaddr;
  56
  57                 num_loadable_segment += 1;
  58                 if ((info->dlpi_name == NULL || info->dlpi_name[0] == 0)
  59                                 && num_loadable_segment == 1) {
  60                         /*
  61                          * If the iterated element is the executable itself we
  62                          * have to use Dl_info to determine its full path
  63                          */
  64                         Dl_info dl_info = { 0 };
  65                         if (!dladdr(base_addr_ptr, &dl_info))
  66                                 return 0;
  67                         if (!realpath(dl_info.dli_fname, resolved_path))
  68                                 return 0;
  69                 } else {
  70                         /*
  71                          * For regular dl_phdr_info entries we have to check if
  72                          * the path to the shared object really exists
  73                          */
  74                         if (!realpath(info->dlpi_name, resolved_path)) {
  75                                 /* Found vDSO, put the 'path' into brackets */
  76                                 snprintf(resolved_path, PATH_MAX - 1, "[%s]",
  77                                                 info->dlpi_name);
  78                         }
  79                 }
  80
  81                 if (stat(resolved_path, &sostat)) {
  82                         sostat.st_size = 0;
  83                         sostat.st_mtime = -1;
  84                 }
  85
  86                 tracepoint(ust_baddr_statedump, soinfo,
  87                                 (struct lttng_session *) data, base_addr_ptr,
  88                                 resolved_path, sostat.st_size, sostat.st_mtime);
  89
  90                 /*
  91                  * We are only interested in the base address (lowest virtual
  92                  * address associated with the memory image), skip the rest
  93                  */
  94                 break;
  95         }
  96         return 0;
  97 }
  98
  99 int
 100 lttng_ust_baddr_statedump(struct lttng_session *session)
 101 {
 102         /*
 103          * Iterate through the list of currently loaded shared objects and
 104          * generate events for loadable segments using extract_soinfo_events
 105          */
 106         dl_iterate_phdr(extract_soinfo_events, session);
 107         return 0;
 108 }