liblttng-ust/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
  40 int extract_soinfo_events(struct dl_phdr_info *info, size_t size, void *data)
  41 {
  42         int j;
  43         int num_loadable_segment = 0;
  44         void *owner = data;
  45         struct cds_list_head *sessionsp;
  46
  47         sessionsp = _lttng_get_sessions();
  48
  49         for (j = 0; j < info->dlpi_phnum; j++) {
  50                 char resolved_path[PATH_MAX];
  51                 struct stat sostat;
  52                 void *base_addr_ptr;
  53                 struct lttng_session *session;
  54
  55                 if (info->dlpi_phdr[j].p_type != PT_LOAD)
  56                         continue;
  57
  58                 /* Calculate virtual memory address of the loadable segment */
  59                 base_addr_ptr = (void *) info->dlpi_addr
  60                         + info->dlpi_phdr[j].p_vaddr;
  61
  62                 num_loadable_segment += 1;
  63                 if ((info->dlpi_name == NULL || info->dlpi_name[0] == 0)
  64                                 && num_loadable_segment == 1) {
  65                         /*
  66                          * If the iterated element is the executable itself we
  67                          * have to use Dl_info to determine its full path
  68                          */
  69                         Dl_info dl_info = { 0 };
  70                         if (!dladdr(base_addr_ptr, &dl_info))
  71                                 return 0;
  72                         if (!realpath(dl_info.dli_fname, resolved_path))
  73                                 return 0;
  74                 } else {
  75                         /*
  76                          * For regular dl_phdr_info entries we have to check if
  77                          * the path to the shared object really exists
  78                          */
  79                         if (!realpath(info->dlpi_name, resolved_path)) {
  80                                 /* Found vDSO, put the 'path' into brackets */
  81                                 snprintf(resolved_path, PATH_MAX - 1, "[%s]",
  82                                                 info->dlpi_name);
  83                         }
  84                 }
  85
  86                 if (stat(resolved_path, &sostat)) {
  87                         sostat.st_size = 0;
  88                         sostat.st_mtime = -1;
  89                 }
  90
  91                 /*
  92                  * UST lock needs to be nested within dynamic loader
  93                  * lock.
  94                  */
  95                 ust_lock();
  96                 cds_list_for_each_entry(session, sessionsp, node) {
  97                         if (session->owner != owner)
  98                                 continue;
  99                         if (!session->statedump_pending)
 100                                 continue;
 101                         tracepoint(ust_baddr_statedump, soinfo,
 102                                         session, base_addr_ptr,
 103                                         resolved_path, sostat.st_size,
 104                                         sostat.st_mtime);
 105                 }
 106                 ust_unlock();
 107
 108                 /*
 109                  * We are only interested in the base address (lowest virtual
 110                  * address associated with the memory image), skip the rest
 111                  */
 112                 break;
 113         }
 114         return 0;
 115 }
 116
 117 int lttng_ust_baddr_statedump(void *owner)
 118 {
 119         if (getenv("LTTNG_UST_WITHOUT_BADDR_STATEDUMP"))
 120                 return 0;
 121         /*
 122          * Iterate through the list of currently loaded shared objects and
 123          * generate events for loadable segments using
 124          * extract_soinfo_events.
 125          */
 126         dl_iterate_phdr(extract_soinfo_events, owner);
 127         return 0;
 128 }