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
  33 #include <usterr-signal-safe.h>
  34 #include "lttng-tracer-core.h"
  35 #include "lttng-ust-baddr.h"
  36
  37 #define TRACEPOINT_DEFINE
  38 #include "ust_baddr_statedump.h"
  39
  40 static
  41 int extract_soinfo_events(struct dl_phdr_info *info, size_t size, void *data)
  42 {
  43         int j;
  44         int num_loadable_segment = 0;
  45         void *owner = data;
  46         struct cds_list_head *sessionsp;
  47
  48         for (j = 0; j < info->dlpi_phnum; j++) {
  49                 char resolved_path[PATH_MAX];
  50                 struct stat sostat;
  51                 void *base_addr_ptr;
  52                 struct lttng_session *session;
  53
  54                 if (info->dlpi_phdr[j].p_type != PT_LOAD)
  55                         continue;
  56
  57                 /* Calculate virtual memory address of the loadable segment */
  58                 base_addr_ptr = (void *) info->dlpi_addr
  59                         + info->dlpi_phdr[j].p_vaddr;
  60
  61                 num_loadable_segment += 1;
  62                 if ((info->dlpi_name == NULL || info->dlpi_name[0] == 0)
  63                                 && num_loadable_segment == 1) {
  64                         /*
  65                          * If the iterated element is the executable itself we
  66                          * have to use Dl_info to determine its full path
  67                          */
  68                         Dl_info dl_info = { 0 };
  69                         if (!dladdr(base_addr_ptr, &dl_info))
  70                                 return 0;
  71                         if (!realpath(dl_info.dli_fname, resolved_path))
  72                                 return 0;
  73                 } else {
  74                         /*
  75                          * For regular dl_phdr_info entries we have to check if
  76                          * the path to the shared object really exists
  77                          */
  78                         if (!realpath(info->dlpi_name, resolved_path)) {
  79                                 /* Found vDSO, put the 'path' into brackets */
  80                                 snprintf(resolved_path, PATH_MAX - 1, "[%s]",
  81                                                 info->dlpi_name);
  82                         }
  83                 }
  84
  85                 if (stat(resolved_path, &sostat)) {
  86                         sostat.st_size = 0;
  87                         sostat.st_mtime = -1;
  88                 }
  89
  90                 /*
  91                  * UST lock needs to be nested within dynamic loader
  92                  * lock.
  93                  */
  94                 if (ust_lock()) {
  95                         /*
  96                          * Stop iteration on headers if need to exit.
  97                          */
  98                         ust_unlock();
  99                         return 1;
 100                 }
 101
 102                 sessionsp = _lttng_get_sessions();
 103                 cds_list_for_each_entry(session, sessionsp, node) {
 104                         if (session->owner != owner)
 105                                 continue;
 106                         if (!session->statedump_pending)
 107                                 continue;
 108                         tracepoint(ust_baddr_statedump, soinfo,
 109                                         session, base_addr_ptr,
 110                                         resolved_path, sostat.st_size,
 111                                         sostat.st_mtime);
 112                 }
 113                 ust_unlock();
 114                 /*
 115                  * We are only interested in the base address (lowest virtual
 116                  * address associated with the memory image), skip the rest
 117                  */
 118                 break;
 119         }
 120         return 0;
 121 }
 122
 123 int lttng_ust_baddr_statedump(void *owner)
 124 {
 125         if (getenv("LTTNG_UST_WITHOUT_BADDR_STATEDUMP"))
 126                 return 0;
 127         /*
 128          * Iterate through the list of currently loaded shared objects and
 129          * generate events for loadable segments using
 130          * extract_soinfo_events.
 131          */
 132         dl_iterate_phdr(extract_soinfo_events, owner);
 133         return 0;
 134 }