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 <sys/stat.h>
  26 #include <unistd.h>
  27 #include <limits.h>
  28 #include <stdlib.h>
  29 #include <errno.h>
  30 #include <stdint.h>
  31 #include <stddef.h>
  32 #include <stdio.h>
  33 #include "usterr.h"
  34
  35 #define TRACEPOINT_DEFINE
  36 #include "ust_baddr.h"
  37 #include "ust_baddr_statedump.h"
  38
  39 int
  40 lttng_ust_push_baddr(void *so_base, const char *so_name)
  41 {
  42         char resolved_path[PATH_MAX];
  43         struct stat sostat;
  44
  45         if (!realpath(so_name, resolved_path)) {
  46                 ERR("could not resolve path '%s'", so_name);
  47                 return 0;
  48         }
  49
  50         if (stat(resolved_path, &sostat)) {
  51                 ERR("could not access file status for %s", resolved_path);
  52                 return 0;
  53         }
  54
  55         tracepoint(ust_baddr, push,
  56                 so_base, resolved_path, sostat.st_size, sostat.st_mtime);
  57         return 0;
  58 }
  59
  60 int
  61 lttng_ust_pop_baddr(void *so_base)
  62 {
  63         tracepoint(ust_baddr, pop, so_base);
  64         return 0;
  65 }
  66
  67 static int
  68 extract_soinfo_events(struct dl_phdr_info *info, size_t size, void *data)
  69 {
  70         int j;
  71         int num_loadable_segment = 0;
  72
  73         for (j = 0; j < info->dlpi_phnum; j++) {
  74                 char resolved_path[PATH_MAX];
  75                 struct stat sostat;
  76                 void *base_addr_ptr;
  77
  78                 if (info->dlpi_phdr[j].p_type != PT_LOAD)
  79                         continue;
  80
  81                 /* Calculate virtual memory address of the loadable segment */
  82                 base_addr_ptr = (void *) info->dlpi_addr
  83                         + info->dlpi_phdr[j].p_vaddr;
  84
  85                 num_loadable_segment += 1;
  86                 if ((info->dlpi_name == NULL || info->dlpi_name[0] == 0)
  87                                 && num_loadable_segment == 1) {
  88                         /*
  89                          * If the iterated element is the executable itself we
  90                          * have to use Dl_info to determine its full path
  91                          */
  92                         Dl_info dl_info = { 0 };
  93                         if (!dladdr(base_addr_ptr, &dl_info))
  94                                 return 0;
  95                         if (!realpath(dl_info.dli_fname, resolved_path))
  96                                 return 0;
  97                 } else {
  98                         /*
  99                          * For regular dl_phdr_info entries we have to check if
 100                          * the path to the shared object really exists
 101                          */
 102                         if (!realpath(info->dlpi_name, resolved_path)) {
 103                                 /* Found vDSO, put the 'path' into brackets */
 104                                 snprintf(resolved_path, PATH_MAX - 1, "[%s]",
 105                                                 info->dlpi_name);
 106                         }
 107                 }
 108
 109                 if (stat(resolved_path, &sostat)) {
 110                         sostat.st_size = 0;
 111                         sostat.st_mtime = -1;
 112                 }
 113
 114                 tracepoint(ust_baddr_statedump, soinfo,
 115                                 (struct lttng_session *) data, base_addr_ptr,
 116                                 resolved_path, sostat.st_size, sostat.st_mtime);
 117
 118                 /*
 119                  * We are only interested in the base address (lowest virtual
 120                  * address associated with the memory image), skip the rest
 121                  */
 122                 break;
 123         }
 124         return 0;
 125 }
 126
 127 int
 128 lttng_ust_baddr_statedump(struct lttng_session *session)
 129 {
 130         /*
 131          * Iterate through the list of currently loaded shared objects and
 132          * generate events for loadable segments using extract_soinfo_events
 133          */
 134         dl_iterate_phdr(extract_soinfo_events, session);
 135         return 0;
 136 }