| 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 _LGPL_SOURCE |
| 20 | #define _GNU_SOURCE |
| 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 | #define TRACEPOINT_CREATE_PROBES |
| 39 | #define TP_SESSION_CHECK |
| 40 | #include "ust_baddr_statedump.h" |
| 41 | |
| 42 | struct extract_data { |
| 43 | void *owner; |
| 44 | void *exec_baddr; /* executable base address */ |
| 45 | }; |
| 46 | |
| 47 | /* |
| 48 | * Trace baddr into all sessions for which statedump is pending owned by |
| 49 | * the caller thread. |
| 50 | */ |
| 51 | static |
| 52 | int trace_baddr(void *base_addr_ptr, |
| 53 | const char *resolved_path, |
| 54 | int vdso, |
| 55 | void *owner) |
| 56 | { |
| 57 | struct cds_list_head *sessionsp; |
| 58 | struct lttng_session *session; |
| 59 | struct stat sostat; |
| 60 | |
| 61 | if (vdso || stat(resolved_path, &sostat)) { |
| 62 | sostat.st_size = 0; |
| 63 | sostat.st_mtime = -1; |
| 64 | } |
| 65 | /* |
| 66 | * UST lock nests within dynamic loader lock. |
| 67 | */ |
| 68 | if (ust_lock()) { |
| 69 | /* |
| 70 | * Stop iteration on headers if need to exit. |
| 71 | */ |
| 72 | ust_unlock(); |
| 73 | return 1; |
| 74 | } |
| 75 | |
| 76 | sessionsp = _lttng_get_sessions(); |
| 77 | cds_list_for_each_entry(session, sessionsp, node) { |
| 78 | if (session->owner != owner) |
| 79 | continue; |
| 80 | if (!session->statedump_pending) |
| 81 | continue; |
| 82 | tracepoint(ust_baddr_statedump, soinfo, |
| 83 | session, base_addr_ptr, |
| 84 | resolved_path, sostat.st_size, |
| 85 | sostat.st_mtime); |
| 86 | } |
| 87 | ust_unlock(); |
| 88 | return 0; |
| 89 | } |
| 90 | |
| 91 | static |
| 92 | int extract_soinfo_events(struct dl_phdr_info *info, size_t size, void *_data) |
| 93 | { |
| 94 | int j; |
| 95 | struct extract_data *data = _data; |
| 96 | void *owner = data->owner; |
| 97 | |
| 98 | for (j = 0; j < info->dlpi_phnum; j++) { |
| 99 | char resolved_path[PATH_MAX]; |
| 100 | void *base_addr_ptr; |
| 101 | int vdso = 0; |
| 102 | |
| 103 | if (info->dlpi_phdr[j].p_type != PT_LOAD) |
| 104 | continue; |
| 105 | |
| 106 | /* Calculate virtual memory address of the loadable segment */ |
| 107 | base_addr_ptr = (void *) info->dlpi_addr |
| 108 | + info->dlpi_phdr[j].p_vaddr; |
| 109 | |
| 110 | if ((info->dlpi_name == NULL || info->dlpi_name[0] == 0) |
| 111 | && !data->exec_baddr) { |
| 112 | /* |
| 113 | * Only the first phdr encountered is considered |
| 114 | * as the program executable. The following |
| 115 | * could be e.g. vdso. Don't mistakenly dump |
| 116 | * them as being the program executable. |
| 117 | */ |
| 118 | data->exec_baddr = base_addr_ptr; |
| 119 | /* |
| 120 | * Deal with program executable outside of phdr |
| 121 | * iteration. |
| 122 | */ |
| 123 | break; |
| 124 | } |
| 125 | if (info->dlpi_name == NULL || info->dlpi_name[0] == 0) { |
| 126 | /* Found vDSO. */ |
| 127 | snprintf(resolved_path, PATH_MAX - 1, "[vdso]"); |
| 128 | vdso = 1; |
| 129 | } else { |
| 130 | /* |
| 131 | * For regular dl_phdr_info entries we have to check if |
| 132 | * the path to the shared object really exists. |
| 133 | */ |
| 134 | if (!realpath(info->dlpi_name, resolved_path)) { |
| 135 | /* Path unknown, put the 'path' into brackets */ |
| 136 | snprintf(resolved_path, PATH_MAX - 1, "[%s]", |
| 137 | info->dlpi_name); |
| 138 | vdso = 1; |
| 139 | } |
| 140 | } |
| 141 | if (trace_baddr(base_addr_ptr, resolved_path, vdso, owner)) { |
| 142 | return 1; |
| 143 | } |
| 144 | /* |
| 145 | * We are only interested in the base address (lowest virtual |
| 146 | * address associated with the memory image), skip the rest |
| 147 | */ |
| 148 | break; |
| 149 | } |
| 150 | return 0; |
| 151 | } |
| 152 | |
| 153 | static |
| 154 | void dump_exec_baddr(struct extract_data *data) |
| 155 | { |
| 156 | void *owner = data->owner; |
| 157 | Dl_info dl_info = { 0 }; |
| 158 | void *base_addr_ptr; |
| 159 | char resolved_path[PATH_MAX]; |
| 160 | |
| 161 | base_addr_ptr = data->exec_baddr; |
| 162 | if (!base_addr_ptr) |
| 163 | return; |
| 164 | /* |
| 165 | * We have to use Dl_info to determine the executable full path. |
| 166 | */ |
| 167 | if (!dladdr(base_addr_ptr, &dl_info)) |
| 168 | return; |
| 169 | if (!realpath(dl_info.dli_fname, resolved_path)) |
| 170 | return; |
| 171 | trace_baddr(base_addr_ptr, resolved_path, 0, owner); |
| 172 | } |
| 173 | |
| 174 | int lttng_ust_baddr_statedump(void *owner) |
| 175 | { |
| 176 | struct extract_data data; |
| 177 | |
| 178 | if (getenv("LTTNG_UST_WITHOUT_BADDR_STATEDUMP")) |
| 179 | return 0; |
| 180 | |
| 181 | data.owner = owner; |
| 182 | data.exec_baddr = NULL; |
| 183 | /* |
| 184 | * Iterate through the list of currently loaded shared objects and |
| 185 | * generate events for loadable segments using |
| 186 | * extract_soinfo_events. |
| 187 | */ |
| 188 | dl_iterate_phdr(extract_soinfo_events, &data); |
| 189 | /* |
| 190 | * We cannot call dladdr() from within phdr iteration, without |
| 191 | * causing constructor vs dynamic loader vs multithread internal |
| 192 | * deadlocks, so dump the executable outside of the phdr |
| 193 | * iteration. |
| 194 | */ |
| 195 | dump_exec_baddr(&data); |
| 196 | return 0; |
| 197 | } |
| 198 | |
| 199 | void lttng_ust_baddr_statedump_init(void) |
| 200 | { |
| 201 | __tracepoints__init(); |
| 202 | __tracepoints__ptrs_init(); |
| 203 | __lttng_events_init__ust_baddr_statedump(); |
| 204 | } |
| 205 | |
| 206 | void lttng_ust_baddr_statedump_destroy(void) |
| 207 | { |
| 208 | __lttng_events_exit__ust_baddr_statedump(); |
| 209 | __tracepoints__ptrs_destroy(); |
| 210 | __tracepoints__destroy(); |
| 211 | } |