| 1 | /* BSD user-level threads support. |
| 2 | |
| 3 | Copyright (C) 2005-2019 Free Software Foundation, Inc. |
| 4 | |
| 5 | This file is part of GDB. |
| 6 | |
| 7 | This program is free software; you can redistribute it and/or modify |
| 8 | it under the terms of the GNU General Public License as published by |
| 9 | the Free Software Foundation; either version 3 of the License, or |
| 10 | (at your option) any later version. |
| 11 | |
| 12 | This program is distributed in the hope that it will be useful, |
| 13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 15 | GNU General Public License for more details. |
| 16 | |
| 17 | You should have received a copy of the GNU General Public License |
| 18 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 19 | |
| 20 | #include "defs.h" |
| 21 | #include "gdbcore.h" |
| 22 | #include "gdbthread.h" |
| 23 | #include "inferior.h" |
| 24 | #include "objfiles.h" |
| 25 | #include "observable.h" |
| 26 | #include "regcache.h" |
| 27 | #include "solib.h" |
| 28 | #include "solist.h" |
| 29 | #include "symfile.h" |
| 30 | #include "target.h" |
| 31 | |
| 32 | #include "gdb_obstack.h" |
| 33 | |
| 34 | #include "bsd-uthread.h" |
| 35 | |
| 36 | static const target_info bsd_uthread_target_info = { |
| 37 | "bsd-uthreads", |
| 38 | N_("BSD user-level threads"), |
| 39 | N_("BSD user-level threads") |
| 40 | }; |
| 41 | |
| 42 | struct bsd_uthread_target final : public target_ops |
| 43 | { |
| 44 | const target_info &info () const override |
| 45 | { return bsd_uthread_target_info; } |
| 46 | |
| 47 | strata stratum () const override { return thread_stratum; } |
| 48 | |
| 49 | void close () override; |
| 50 | |
| 51 | void mourn_inferior () override; |
| 52 | |
| 53 | void fetch_registers (struct regcache *, int) override; |
| 54 | void store_registers (struct regcache *, int) override; |
| 55 | |
| 56 | ptid_t wait (ptid_t, struct target_waitstatus *, int) override; |
| 57 | void resume (ptid_t, int, enum gdb_signal) override; |
| 58 | |
| 59 | bool thread_alive (ptid_t ptid) override; |
| 60 | |
| 61 | void update_thread_list () override; |
| 62 | |
| 63 | const char *extra_thread_info (struct thread_info *) override; |
| 64 | |
| 65 | std::string pid_to_str (ptid_t) override; |
| 66 | }; |
| 67 | |
| 68 | static bsd_uthread_target bsd_uthread_ops; |
| 69 | \f |
| 70 | |
| 71 | /* Architecture-specific operations. */ |
| 72 | |
| 73 | /* Per-architecture data key. */ |
| 74 | static struct gdbarch_data *bsd_uthread_data; |
| 75 | |
| 76 | struct bsd_uthread_ops |
| 77 | { |
| 78 | /* Supply registers for an inactive thread to a register cache. */ |
| 79 | void (*supply_uthread)(struct regcache *, int, CORE_ADDR); |
| 80 | |
| 81 | /* Collect registers for an inactive thread from a register cache. */ |
| 82 | void (*collect_uthread)(const struct regcache *, int, CORE_ADDR); |
| 83 | }; |
| 84 | |
| 85 | static void * |
| 86 | bsd_uthread_init (struct obstack *obstack) |
| 87 | { |
| 88 | struct bsd_uthread_ops *ops; |
| 89 | |
| 90 | ops = OBSTACK_ZALLOC (obstack, struct bsd_uthread_ops); |
| 91 | return ops; |
| 92 | } |
| 93 | |
| 94 | /* Set the function that supplies registers from an inactive thread |
| 95 | for architecture GDBARCH to SUPPLY_UTHREAD. */ |
| 96 | |
| 97 | void |
| 98 | bsd_uthread_set_supply_uthread (struct gdbarch *gdbarch, |
| 99 | void (*supply_uthread) (struct regcache *, |
| 100 | int, CORE_ADDR)) |
| 101 | { |
| 102 | struct bsd_uthread_ops *ops |
| 103 | = (struct bsd_uthread_ops *) gdbarch_data (gdbarch, bsd_uthread_data); |
| 104 | |
| 105 | ops->supply_uthread = supply_uthread; |
| 106 | } |
| 107 | |
| 108 | /* Set the function that collects registers for an inactive thread for |
| 109 | architecture GDBARCH to SUPPLY_UTHREAD. */ |
| 110 | |
| 111 | void |
| 112 | bsd_uthread_set_collect_uthread (struct gdbarch *gdbarch, |
| 113 | void (*collect_uthread) (const struct regcache *, |
| 114 | int, CORE_ADDR)) |
| 115 | { |
| 116 | struct bsd_uthread_ops *ops |
| 117 | = (struct bsd_uthread_ops *) gdbarch_data (gdbarch, bsd_uthread_data); |
| 118 | |
| 119 | ops->collect_uthread = collect_uthread; |
| 120 | } |
| 121 | |
| 122 | /* Magic number to help recognize a valid thread structure. */ |
| 123 | #define BSD_UTHREAD_PTHREAD_MAGIC 0xd09ba115 |
| 124 | |
| 125 | /* Check whether the thread structure at ADDR is valid. */ |
| 126 | |
| 127 | static void |
| 128 | bsd_uthread_check_magic (CORE_ADDR addr) |
| 129 | { |
| 130 | enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ()); |
| 131 | ULONGEST magic = read_memory_unsigned_integer (addr, 4, byte_order); |
| 132 | |
| 133 | if (magic != BSD_UTHREAD_PTHREAD_MAGIC) |
| 134 | error (_("Bad magic")); |
| 135 | } |
| 136 | |
| 137 | /* Thread states. */ |
| 138 | #define BSD_UTHREAD_PS_RUNNING 0 |
| 139 | #define BSD_UTHREAD_PS_DEAD 18 |
| 140 | |
| 141 | /* Address of the pointer to the thread structure for the running |
| 142 | thread. */ |
| 143 | static CORE_ADDR bsd_uthread_thread_run_addr; |
| 144 | |
| 145 | /* Address of the list of all threads. */ |
| 146 | static CORE_ADDR bsd_uthread_thread_list_addr; |
| 147 | |
| 148 | /* Offsets of various "interesting" bits in the thread structure. */ |
| 149 | static int bsd_uthread_thread_state_offset = -1; |
| 150 | static int bsd_uthread_thread_next_offset = -1; |
| 151 | static int bsd_uthread_thread_ctx_offset; |
| 152 | |
| 153 | /* Name of shared threads library. */ |
| 154 | static const char *bsd_uthread_solib_name; |
| 155 | |
| 156 | /* Non-zero if the thread startum implemented by this module is active. */ |
| 157 | static int bsd_uthread_active; |
| 158 | |
| 159 | static CORE_ADDR |
| 160 | bsd_uthread_lookup_address (const char *name, struct objfile *objfile) |
| 161 | { |
| 162 | struct bound_minimal_symbol sym; |
| 163 | |
| 164 | sym = lookup_minimal_symbol (name, NULL, objfile); |
| 165 | if (sym.minsym) |
| 166 | return BMSYMBOL_VALUE_ADDRESS (sym); |
| 167 | |
| 168 | return 0; |
| 169 | } |
| 170 | |
| 171 | static int |
| 172 | bsd_uthread_lookup_offset (const char *name, struct objfile *objfile) |
| 173 | { |
| 174 | enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ()); |
| 175 | CORE_ADDR addr; |
| 176 | |
| 177 | addr = bsd_uthread_lookup_address (name, objfile); |
| 178 | if (addr == 0) |
| 179 | return 0; |
| 180 | |
| 181 | return read_memory_unsigned_integer (addr, 4, byte_order); |
| 182 | } |
| 183 | |
| 184 | static CORE_ADDR |
| 185 | bsd_uthread_read_memory_address (CORE_ADDR addr) |
| 186 | { |
| 187 | struct type *ptr_type = builtin_type (target_gdbarch ())->builtin_data_ptr; |
| 188 | return read_memory_typed_address (addr, ptr_type); |
| 189 | } |
| 190 | |
| 191 | /* If OBJFILE contains the symbols corresponding to one of the |
| 192 | supported user-level threads libraries, activate the thread stratum |
| 193 | implemented by this module. */ |
| 194 | |
| 195 | static int |
| 196 | bsd_uthread_activate (struct objfile *objfile) |
| 197 | { |
| 198 | struct gdbarch *gdbarch = target_gdbarch (); |
| 199 | struct bsd_uthread_ops *ops |
| 200 | = (struct bsd_uthread_ops *) gdbarch_data (gdbarch, bsd_uthread_data); |
| 201 | |
| 202 | /* Skip if the thread stratum has already been activated. */ |
| 203 | if (bsd_uthread_active) |
| 204 | return 0; |
| 205 | |
| 206 | /* There's no point in enabling this module if no |
| 207 | architecture-specific operations are provided. */ |
| 208 | if (!ops->supply_uthread) |
| 209 | return 0; |
| 210 | |
| 211 | bsd_uthread_thread_run_addr = |
| 212 | bsd_uthread_lookup_address ("_thread_run", objfile); |
| 213 | if (bsd_uthread_thread_run_addr == 0) |
| 214 | return 0; |
| 215 | |
| 216 | bsd_uthread_thread_list_addr = |
| 217 | bsd_uthread_lookup_address ("_thread_list", objfile); |
| 218 | if (bsd_uthread_thread_list_addr == 0) |
| 219 | return 0; |
| 220 | |
| 221 | bsd_uthread_thread_state_offset = |
| 222 | bsd_uthread_lookup_offset ("_thread_state_offset", objfile); |
| 223 | if (bsd_uthread_thread_state_offset == 0) |
| 224 | return 0; |
| 225 | |
| 226 | bsd_uthread_thread_next_offset = |
| 227 | bsd_uthread_lookup_offset ("_thread_next_offset", objfile); |
| 228 | if (bsd_uthread_thread_next_offset == 0) |
| 229 | return 0; |
| 230 | |
| 231 | bsd_uthread_thread_ctx_offset = |
| 232 | bsd_uthread_lookup_offset ("_thread_ctx_offset", objfile); |
| 233 | |
| 234 | push_target (&bsd_uthread_ops); |
| 235 | bsd_uthread_active = 1; |
| 236 | return 1; |
| 237 | } |
| 238 | |
| 239 | /* Cleanup due to deactivation. */ |
| 240 | |
| 241 | void |
| 242 | bsd_uthread_target::close () |
| 243 | { |
| 244 | bsd_uthread_active = 0; |
| 245 | bsd_uthread_thread_run_addr = 0; |
| 246 | bsd_uthread_thread_list_addr = 0; |
| 247 | bsd_uthread_thread_state_offset = 0; |
| 248 | bsd_uthread_thread_next_offset = 0; |
| 249 | bsd_uthread_thread_ctx_offset = 0; |
| 250 | bsd_uthread_solib_name = NULL; |
| 251 | } |
| 252 | |
| 253 | /* Deactivate the thread stratum implemented by this module. */ |
| 254 | |
| 255 | static void |
| 256 | bsd_uthread_deactivate (void) |
| 257 | { |
| 258 | /* Skip if the thread stratum has already been deactivated. */ |
| 259 | if (!bsd_uthread_active) |
| 260 | return; |
| 261 | |
| 262 | unpush_target (&bsd_uthread_ops); |
| 263 | } |
| 264 | |
| 265 | static void |
| 266 | bsd_uthread_inferior_created (struct target_ops *ops, int from_tty) |
| 267 | { |
| 268 | bsd_uthread_activate (NULL); |
| 269 | } |
| 270 | |
| 271 | /* Likely candidates for the threads library. */ |
| 272 | static const char *bsd_uthread_solib_names[] = |
| 273 | { |
| 274 | "/usr/lib/libc_r.so", /* FreeBSD */ |
| 275 | "/usr/lib/libpthread.so", /* OpenBSD */ |
| 276 | NULL |
| 277 | }; |
| 278 | |
| 279 | static void |
| 280 | bsd_uthread_solib_loaded (struct so_list *so) |
| 281 | { |
| 282 | const char **names = bsd_uthread_solib_names; |
| 283 | |
| 284 | for (names = bsd_uthread_solib_names; *names; names++) |
| 285 | { |
| 286 | if (startswith (so->so_original_name, *names)) |
| 287 | { |
| 288 | solib_read_symbols (so, 0); |
| 289 | |
| 290 | if (bsd_uthread_activate (so->objfile)) |
| 291 | { |
| 292 | bsd_uthread_solib_name = so->so_original_name; |
| 293 | return; |
| 294 | } |
| 295 | } |
| 296 | } |
| 297 | } |
| 298 | |
| 299 | static void |
| 300 | bsd_uthread_solib_unloaded (struct so_list *so) |
| 301 | { |
| 302 | if (!bsd_uthread_solib_name) |
| 303 | return; |
| 304 | |
| 305 | if (strcmp (so->so_original_name, bsd_uthread_solib_name) == 0) |
| 306 | bsd_uthread_deactivate (); |
| 307 | } |
| 308 | |
| 309 | void |
| 310 | bsd_uthread_target::mourn_inferior () |
| 311 | { |
| 312 | beneath ()->mourn_inferior (); |
| 313 | bsd_uthread_deactivate (); |
| 314 | } |
| 315 | |
| 316 | void |
| 317 | bsd_uthread_target::fetch_registers (struct regcache *regcache, int regnum) |
| 318 | { |
| 319 | struct gdbarch *gdbarch = regcache->arch (); |
| 320 | struct bsd_uthread_ops *uthread_ops |
| 321 | = (struct bsd_uthread_ops *) gdbarch_data (gdbarch, bsd_uthread_data); |
| 322 | ptid_t ptid = regcache->ptid (); |
| 323 | CORE_ADDR addr = ptid.tid (); |
| 324 | CORE_ADDR active_addr; |
| 325 | scoped_restore save_inferior_ptid = make_scoped_restore (&inferior_ptid); |
| 326 | |
| 327 | /* We are doing operations (e.g. reading memory) that rely on |
| 328 | inferior_ptid. */ |
| 329 | inferior_ptid = ptid; |
| 330 | |
| 331 | /* Always fetch the appropriate registers from the layer beneath. */ |
| 332 | beneath ()->fetch_registers (regcache, regnum); |
| 333 | |
| 334 | /* FIXME: That might have gotten us more than we asked for. Make |
| 335 | sure we overwrite all relevant registers with values from the |
| 336 | thread structure. This can go once we fix the underlying target. */ |
| 337 | regnum = -1; |
| 338 | |
| 339 | active_addr = bsd_uthread_read_memory_address (bsd_uthread_thread_run_addr); |
| 340 | if (addr != 0 && addr != active_addr) |
| 341 | { |
| 342 | bsd_uthread_check_magic (addr); |
| 343 | uthread_ops->supply_uthread (regcache, regnum, |
| 344 | addr + bsd_uthread_thread_ctx_offset); |
| 345 | } |
| 346 | } |
| 347 | |
| 348 | void |
| 349 | bsd_uthread_target::store_registers (struct regcache *regcache, int regnum) |
| 350 | { |
| 351 | struct gdbarch *gdbarch = regcache->arch (); |
| 352 | struct bsd_uthread_ops *uthread_ops |
| 353 | = (struct bsd_uthread_ops *) gdbarch_data (gdbarch, bsd_uthread_data); |
| 354 | ptid_t ptid = regcache->ptid (); |
| 355 | CORE_ADDR addr = ptid.tid (); |
| 356 | CORE_ADDR active_addr; |
| 357 | scoped_restore save_inferior_ptid = make_scoped_restore (&inferior_ptid); |
| 358 | |
| 359 | /* We are doing operations (e.g. reading memory) that rely on |
| 360 | inferior_ptid. */ |
| 361 | inferior_ptid = ptid; |
| 362 | |
| 363 | active_addr = bsd_uthread_read_memory_address (bsd_uthread_thread_run_addr); |
| 364 | if (addr != 0 && addr != active_addr) |
| 365 | { |
| 366 | bsd_uthread_check_magic (addr); |
| 367 | uthread_ops->collect_uthread (regcache, regnum, |
| 368 | addr + bsd_uthread_thread_ctx_offset); |
| 369 | } |
| 370 | else |
| 371 | { |
| 372 | /* Updating the thread that is currently running; pass the |
| 373 | request to the layer beneath. */ |
| 374 | beneath ()->store_registers (regcache, regnum); |
| 375 | } |
| 376 | } |
| 377 | |
| 378 | ptid_t |
| 379 | bsd_uthread_target::wait (ptid_t ptid, struct target_waitstatus *status, |
| 380 | int options) |
| 381 | { |
| 382 | enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ()); |
| 383 | CORE_ADDR addr; |
| 384 | |
| 385 | /* Pass the request to the layer beneath. */ |
| 386 | ptid = beneath ()->wait (ptid, status, options); |
| 387 | |
| 388 | /* If the process is no longer alive, there's no point in figuring |
| 389 | out the thread ID. It will fail anyway. */ |
| 390 | if (status->kind == TARGET_WAITKIND_SIGNALLED |
| 391 | || status->kind == TARGET_WAITKIND_EXITED) |
| 392 | return ptid; |
| 393 | |
| 394 | /* Fetch the corresponding thread ID, and augment the returned |
| 395 | process ID with it. */ |
| 396 | addr = bsd_uthread_read_memory_address (bsd_uthread_thread_run_addr); |
| 397 | if (addr != 0) |
| 398 | { |
| 399 | gdb_byte buf[4]; |
| 400 | |
| 401 | /* FIXME: For executables linked statically with the threads |
| 402 | library, we end up here before the program has actually been |
| 403 | executed. In that case ADDR will be garbage since it has |
| 404 | been read from the wrong virtual memory image. */ |
| 405 | if (target_read_memory (addr, buf, 4) == 0) |
| 406 | { |
| 407 | ULONGEST magic = extract_unsigned_integer (buf, 4, byte_order); |
| 408 | if (magic == BSD_UTHREAD_PTHREAD_MAGIC) |
| 409 | ptid = ptid_t (ptid.pid (), 0, addr); |
| 410 | } |
| 411 | } |
| 412 | |
| 413 | /* If INFERIOR_PTID doesn't have a tid member yet, and we now have a |
| 414 | ptid with tid set, then ptid is still the initial thread of |
| 415 | the process. Notify GDB core about it. */ |
| 416 | if (inferior_ptid.tid () == 0 |
| 417 | && ptid.tid () != 0 && !in_thread_list (ptid)) |
| 418 | thread_change_ptid (inferior_ptid, ptid); |
| 419 | |
| 420 | /* Don't let the core see a ptid without a corresponding thread. */ |
| 421 | thread_info *thread = find_thread_ptid (ptid); |
| 422 | if (thread == NULL || thread->state == THREAD_EXITED) |
| 423 | add_thread (ptid); |
| 424 | |
| 425 | return ptid; |
| 426 | } |
| 427 | |
| 428 | void |
| 429 | bsd_uthread_target::resume (ptid_t ptid, int step, enum gdb_signal sig) |
| 430 | { |
| 431 | /* Pass the request to the layer beneath. */ |
| 432 | beneath ()->resume (ptid, step, sig); |
| 433 | } |
| 434 | |
| 435 | bool |
| 436 | bsd_uthread_target::thread_alive (ptid_t ptid) |
| 437 | { |
| 438 | enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ()); |
| 439 | CORE_ADDR addr = ptid.tid (); |
| 440 | |
| 441 | if (addr != 0) |
| 442 | { |
| 443 | int offset = bsd_uthread_thread_state_offset; |
| 444 | ULONGEST state; |
| 445 | |
| 446 | bsd_uthread_check_magic (addr); |
| 447 | |
| 448 | state = read_memory_unsigned_integer (addr + offset, 4, byte_order); |
| 449 | if (state == BSD_UTHREAD_PS_DEAD) |
| 450 | return false; |
| 451 | } |
| 452 | |
| 453 | return beneath ()->thread_alive (ptid); |
| 454 | } |
| 455 | |
| 456 | void |
| 457 | bsd_uthread_target::update_thread_list () |
| 458 | { |
| 459 | pid_t pid = inferior_ptid.pid (); |
| 460 | int offset = bsd_uthread_thread_next_offset; |
| 461 | CORE_ADDR addr; |
| 462 | |
| 463 | prune_threads (); |
| 464 | |
| 465 | addr = bsd_uthread_read_memory_address (bsd_uthread_thread_list_addr); |
| 466 | while (addr != 0) |
| 467 | { |
| 468 | ptid_t ptid = ptid_t (pid, 0, addr); |
| 469 | |
| 470 | thread_info *thread = find_thread_ptid (ptid); |
| 471 | if (thread == nullptr || thread->state == THREAD_EXITED) |
| 472 | { |
| 473 | /* If INFERIOR_PTID doesn't have a tid member yet, then ptid |
| 474 | is still the initial thread of the process. Notify GDB |
| 475 | core about it. */ |
| 476 | if (inferior_ptid.tid () == 0) |
| 477 | thread_change_ptid (inferior_ptid, ptid); |
| 478 | else |
| 479 | add_thread (ptid); |
| 480 | } |
| 481 | |
| 482 | addr = bsd_uthread_read_memory_address (addr + offset); |
| 483 | } |
| 484 | } |
| 485 | |
| 486 | /* Possible states a thread can be in. */ |
| 487 | static const char *bsd_uthread_state[] = |
| 488 | { |
| 489 | "RUNNING", |
| 490 | "SIGTHREAD", |
| 491 | "MUTEX_WAIT", |
| 492 | "COND_WAIT", |
| 493 | "FDLR_WAIT", |
| 494 | "FDLW_WAIT", |
| 495 | "FDR_WAIT", |
| 496 | "FDW_WAIT", |
| 497 | "FILE_WAIT", |
| 498 | "POLL_WAIT", |
| 499 | "SELECT_WAIT", |
| 500 | "SLEEP_WAIT", |
| 501 | "WAIT_WAIT", |
| 502 | "SIGSUSPEND", |
| 503 | "SIGWAIT", |
| 504 | "SPINBLOCK", |
| 505 | "JOIN", |
| 506 | "SUSPENDED", |
| 507 | "DEAD", |
| 508 | "DEADLOCK" |
| 509 | }; |
| 510 | |
| 511 | /* Return a string describing th state of the thread specified by |
| 512 | INFO. */ |
| 513 | |
| 514 | const char * |
| 515 | bsd_uthread_target::extra_thread_info (thread_info *info) |
| 516 | { |
| 517 | enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ()); |
| 518 | CORE_ADDR addr = info->ptid.tid (); |
| 519 | |
| 520 | if (addr != 0) |
| 521 | { |
| 522 | int offset = bsd_uthread_thread_state_offset; |
| 523 | ULONGEST state; |
| 524 | |
| 525 | state = read_memory_unsigned_integer (addr + offset, 4, byte_order); |
| 526 | if (state < ARRAY_SIZE (bsd_uthread_state)) |
| 527 | return bsd_uthread_state[state]; |
| 528 | } |
| 529 | |
| 530 | return NULL; |
| 531 | } |
| 532 | |
| 533 | std::string |
| 534 | bsd_uthread_target::pid_to_str (ptid_t ptid) |
| 535 | { |
| 536 | if (ptid.tid () != 0) |
| 537 | return string_printf ("process %d, thread 0x%lx", |
| 538 | ptid.pid (), ptid.tid ()); |
| 539 | |
| 540 | return normal_pid_to_str (ptid); |
| 541 | } |
| 542 | |
| 543 | void |
| 544 | _initialize_bsd_uthread (void) |
| 545 | { |
| 546 | bsd_uthread_data = gdbarch_data_register_pre_init (bsd_uthread_init); |
| 547 | |
| 548 | gdb::observers::inferior_created.attach (bsd_uthread_inferior_created); |
| 549 | gdb::observers::solib_loaded.attach (bsd_uthread_solib_loaded); |
| 550 | gdb::observers::solib_unloaded.attach (bsd_uthread_solib_unloaded); |
| 551 | } |