gdb/bsd-uthread.c

   1 /* BSD user-level threads support.
   2
   3    Copyright (C) 2005-2017 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 "observer.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 /* HACK: Save the bsd_uthreads ops returned by bsd_uthread_target.  */
  37 static struct target_ops *bsd_uthread_ops_hack;
  38 \f
  39
  40 /* Architecture-specific operations.  */
  41
  42 /* Per-architecture data key.  */
  43 static struct gdbarch_data *bsd_uthread_data;
  44
  45 struct bsd_uthread_ops
  46 {
  47   /* Supply registers for an inactive thread to a register cache.  */
  48   void (*supply_uthread)(struct regcache *, int, CORE_ADDR);
  49
  50   /* Collect registers for an inactive thread from a register cache.  */
  51   void (*collect_uthread)(const struct regcache *, int, CORE_ADDR);
  52 };
  53
  54 static void *
  55 bsd_uthread_init (struct obstack *obstack)
  56 {
  57   struct bsd_uthread_ops *ops;
  58
  59   ops = OBSTACK_ZALLOC (obstack, struct bsd_uthread_ops);
  60   return ops;
  61 }
  62
  63 /* Set the function that supplies registers from an inactive thread
  64    for architecture GDBARCH to SUPPLY_UTHREAD.  */
  65
  66 void
  67 bsd_uthread_set_supply_uthread (struct gdbarch *gdbarch,
  68                                 void (*supply_uthread) (struct regcache *,
  69                                                         int, CORE_ADDR))
  70 {
  71   struct bsd_uthread_ops *ops
  72     = (struct bsd_uthread_ops *) gdbarch_data (gdbarch, bsd_uthread_data);
  73
  74   ops->supply_uthread = supply_uthread;
  75 }
  76
  77 /* Set the function that collects registers for an inactive thread for
  78    architecture GDBARCH to SUPPLY_UTHREAD.  */
  79
  80 void
  81 bsd_uthread_set_collect_uthread (struct gdbarch *gdbarch,
  82                          void (*collect_uthread) (const struct regcache *,
  83                                                   int, CORE_ADDR))
  84 {
  85   struct bsd_uthread_ops *ops
  86     = (struct bsd_uthread_ops *) gdbarch_data (gdbarch, bsd_uthread_data);
  87
  88   ops->collect_uthread = collect_uthread;
  89 }
  90
  91 /* Magic number to help recognize a valid thread structure.  */
  92 #define BSD_UTHREAD_PTHREAD_MAGIC       0xd09ba115
  93
  94 /* Check whether the thread structure at ADDR is valid.  */
  95
  96 static void
  97 bsd_uthread_check_magic (CORE_ADDR addr)
  98 {
  99   enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
 100   ULONGEST magic = read_memory_unsigned_integer (addr, 4, byte_order);
 101
 102   if (magic != BSD_UTHREAD_PTHREAD_MAGIC)
 103     error (_("Bad magic"));
 104 }
 105
 106 /* Thread states.  */
 107 #define BSD_UTHREAD_PS_RUNNING  0
 108 #define BSD_UTHREAD_PS_DEAD     18
 109
 110 /* Address of the pointer to the thread structure for the running
 111    thread.  */
 112 static CORE_ADDR bsd_uthread_thread_run_addr;
 113
 114 /* Address of the list of all threads.  */
 115 static CORE_ADDR bsd_uthread_thread_list_addr;
 116
 117 /* Offsets of various "interesting" bits in the thread structure.  */
 118 static int bsd_uthread_thread_state_offset = -1;
 119 static int bsd_uthread_thread_next_offset = -1;
 120 static int bsd_uthread_thread_ctx_offset;
 121
 122 /* Name of shared threads library.  */
 123 static const char *bsd_uthread_solib_name;
 124
 125 /* Non-zero if the thread startum implemented by this module is active.  */
 126 static int bsd_uthread_active;
 127
 128 static CORE_ADDR
 129 bsd_uthread_lookup_address (const char *name, struct objfile *objfile)
 130 {
 131   struct bound_minimal_symbol sym;
 132
 133   sym = lookup_minimal_symbol (name, NULL, objfile);
 134   if (sym.minsym)
 135     return BMSYMBOL_VALUE_ADDRESS (sym);
 136
 137   return 0;
 138 }
 139
 140 static int
 141 bsd_uthread_lookup_offset (const char *name, struct objfile *objfile)
 142 {
 143   enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
 144   CORE_ADDR addr;
 145
 146   addr = bsd_uthread_lookup_address (name, objfile);
 147   if (addr == 0)
 148     return 0;
 149
 150   return read_memory_unsigned_integer (addr, 4, byte_order);
 151 }
 152
 153 static CORE_ADDR
 154 bsd_uthread_read_memory_address (CORE_ADDR addr)
 155 {
 156   struct type *ptr_type = builtin_type (target_gdbarch ())->builtin_data_ptr;
 157   return read_memory_typed_address (addr, ptr_type);
 158 }
 159
 160 /* If OBJFILE contains the symbols corresponding to one of the
 161    supported user-level threads libraries, activate the thread stratum
 162    implemented by this module.  */
 163
 164 static int
 165 bsd_uthread_activate (struct objfile *objfile)
 166 {
 167   struct gdbarch *gdbarch = target_gdbarch ();
 168   struct bsd_uthread_ops *ops
 169     = (struct bsd_uthread_ops *) gdbarch_data (gdbarch, bsd_uthread_data);
 170
 171   /* Skip if the thread stratum has already been activated.  */
 172   if (bsd_uthread_active)
 173     return 0;
 174
 175   /* There's no point in enabling this module if no
 176      architecture-specific operations are provided.  */
 177   if (!ops->supply_uthread)
 178     return 0;
 179
 180   bsd_uthread_thread_run_addr =
 181     bsd_uthread_lookup_address ("_thread_run", objfile);
 182   if (bsd_uthread_thread_run_addr == 0)
 183     return 0;
 184
 185   bsd_uthread_thread_list_addr =
 186     bsd_uthread_lookup_address ("_thread_list", objfile);
 187   if (bsd_uthread_thread_list_addr == 0)
 188     return 0;
 189
 190   bsd_uthread_thread_state_offset =
 191     bsd_uthread_lookup_offset ("_thread_state_offset", objfile);
 192   if (bsd_uthread_thread_state_offset == 0)
 193     return 0;
 194
 195   bsd_uthread_thread_next_offset =
 196     bsd_uthread_lookup_offset ("_thread_next_offset", objfile);
 197   if (bsd_uthread_thread_next_offset == 0)
 198     return 0;
 199
 200   bsd_uthread_thread_ctx_offset =
 201     bsd_uthread_lookup_offset ("_thread_ctx_offset", objfile);
 202
 203   push_target (bsd_uthread_ops_hack);
 204   bsd_uthread_active = 1;
 205   return 1;
 206 }
 207
 208 /* Cleanup due to deactivation.  */
 209
 210 static void
 211 bsd_uthread_close (struct target_ops *self)
 212 {
 213   bsd_uthread_active = 0;
 214   bsd_uthread_thread_run_addr = 0;
 215   bsd_uthread_thread_list_addr = 0;
 216   bsd_uthread_thread_state_offset = 0;
 217   bsd_uthread_thread_next_offset = 0;
 218   bsd_uthread_thread_ctx_offset = 0;
 219   bsd_uthread_solib_name = NULL;
 220 }
 221
 222 /* Deactivate the thread stratum implemented by this module.  */
 223
 224 static void
 225 bsd_uthread_deactivate (void)
 226 {
 227   /* Skip if the thread stratum has already been deactivated.  */
 228   if (!bsd_uthread_active)
 229     return;
 230
 231   unpush_target (bsd_uthread_ops_hack);
 232 }
 233
 234 static void
 235 bsd_uthread_inferior_created (struct target_ops *ops, int from_tty)
 236 {
 237   bsd_uthread_activate (NULL);
 238 }
 239
 240 /* Likely candidates for the threads library.  */
 241 static const char *bsd_uthread_solib_names[] =
 242 {
 243   "/usr/lib/libc_r.so",         /* FreeBSD */
 244   "/usr/lib/libpthread.so",     /* OpenBSD */
 245   NULL
 246 };
 247
 248 static void
 249 bsd_uthread_solib_loaded (struct so_list *so)
 250 {
 251   const char **names = bsd_uthread_solib_names;
 252
 253   for (names = bsd_uthread_solib_names; *names; names++)
 254     {
 255       if (startswith (so->so_original_name, *names))
 256         {
 257           solib_read_symbols (so, 0);
 258
 259           if (bsd_uthread_activate (so->objfile))
 260             {
 261               bsd_uthread_solib_name = so->so_original_name;
 262               return;
 263             }
 264         }
 265     }
 266 }
 267
 268 static void
 269 bsd_uthread_solib_unloaded (struct so_list *so)
 270 {
 271   if (!bsd_uthread_solib_name)
 272     return;
 273
 274   if (strcmp (so->so_original_name, bsd_uthread_solib_name) == 0)
 275     bsd_uthread_deactivate ();
 276 }
 277
 278 static void
 279 bsd_uthread_mourn_inferior (struct target_ops *ops)
 280 {
 281   struct target_ops *beneath = find_target_beneath (ops);
 282   beneath->to_mourn_inferior (beneath);
 283   bsd_uthread_deactivate ();
 284 }
 285
 286 static void
 287 bsd_uthread_fetch_registers (struct target_ops *ops,
 288                              struct regcache *regcache, int regnum)
 289 {
 290   struct gdbarch *gdbarch = regcache->arch ();
 291   struct bsd_uthread_ops *uthread_ops
 292     = (struct bsd_uthread_ops *) gdbarch_data (gdbarch, bsd_uthread_data);
 293   ptid_t ptid = regcache_get_ptid (regcache);
 294   CORE_ADDR addr = ptid_get_tid (ptid);
 295   struct target_ops *beneath = find_target_beneath (ops);
 296   CORE_ADDR active_addr;
 297   scoped_restore save_inferior_ptid = make_scoped_restore (&inferior_ptid);
 298
 299   /* We are doing operations (e.g. reading memory) that rely on
 300      inferior_ptid.  */
 301   inferior_ptid = ptid;
 302
 303   /* Always fetch the appropriate registers from the layer beneath.  */
 304   beneath->to_fetch_registers (beneath, regcache, regnum);
 305
 306   /* FIXME: That might have gotten us more than we asked for.  Make
 307      sure we overwrite all relevant registers with values from the
 308      thread structure.  This can go once we fix the underlying target.  */
 309   regnum = -1;
 310
 311   active_addr = bsd_uthread_read_memory_address (bsd_uthread_thread_run_addr);
 312   if (addr != 0 && addr != active_addr)
 313     {
 314       bsd_uthread_check_magic (addr);
 315       uthread_ops->supply_uthread (regcache, regnum,
 316                                    addr + bsd_uthread_thread_ctx_offset);
 317     }
 318 }
 319
 320 static void
 321 bsd_uthread_store_registers (struct target_ops *ops,
 322                              struct regcache *regcache, int regnum)
 323 {
 324   struct gdbarch *gdbarch = regcache->arch ();
 325   struct bsd_uthread_ops *uthread_ops
 326     = (struct bsd_uthread_ops *) gdbarch_data (gdbarch, bsd_uthread_data);
 327   struct target_ops *beneath = find_target_beneath (ops);
 328   ptid_t ptid = regcache_get_ptid (regcache);
 329   CORE_ADDR addr = ptid_get_tid (ptid);
 330   CORE_ADDR active_addr;
 331   scoped_restore save_inferior_ptid = make_scoped_restore (&inferior_ptid);
 332
 333   /* We are doing operations (e.g. reading memory) that rely on
 334      inferior_ptid.  */
 335   inferior_ptid = ptid;
 336
 337   active_addr = bsd_uthread_read_memory_address (bsd_uthread_thread_run_addr);
 338   if (addr != 0 && addr != active_addr)
 339     {
 340       bsd_uthread_check_magic (addr);
 341       uthread_ops->collect_uthread (regcache, regnum,
 342                                     addr + bsd_uthread_thread_ctx_offset);
 343     }
 344   else
 345     {
 346       /* Updating the thread that is currently running; pass the
 347          request to the layer beneath.  */
 348       beneath->to_store_registers (beneath, regcache, regnum);
 349     }
 350 }
 351
 352 static ptid_t
 353 bsd_uthread_wait (struct target_ops *ops,
 354                   ptid_t ptid, struct target_waitstatus *status, int options)
 355 {
 356   enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
 357   CORE_ADDR addr;
 358   struct target_ops *beneath = find_target_beneath (ops);
 359
 360   /* Pass the request to the layer beneath.  */
 361   ptid = beneath->to_wait (beneath, ptid, status, options);
 362
 363   /* If the process is no longer alive, there's no point in figuring
 364      out the thread ID.  It will fail anyway.  */
 365   if (status->kind == TARGET_WAITKIND_SIGNALLED
 366       || status->kind == TARGET_WAITKIND_EXITED)
 367     return ptid;
 368
 369   /* Fetch the corresponding thread ID, and augment the returned
 370      process ID with it.  */
 371   addr = bsd_uthread_read_memory_address (bsd_uthread_thread_run_addr);
 372   if (addr != 0)
 373     {
 374       gdb_byte buf[4];
 375
 376       /* FIXME: For executables linked statically with the threads
 377          library, we end up here before the program has actually been
 378          executed.  In that case ADDR will be garbage since it has
 379          been read from the wrong virtual memory image.  */
 380       if (target_read_memory (addr, buf, 4) == 0)
 381         {
 382           ULONGEST magic = extract_unsigned_integer (buf, 4, byte_order);
 383           if (magic == BSD_UTHREAD_PTHREAD_MAGIC)
 384             ptid = ptid_build (ptid_get_pid (ptid), 0, addr);
 385         }
 386     }
 387
 388   /* If INFERIOR_PTID doesn't have a tid member yet, and we now have a
 389      ptid with tid set, then ptid is still the initial thread of
 390      the process.  Notify GDB core about it.  */
 391   if (ptid_get_tid (inferior_ptid) == 0
 392       && ptid_get_tid (ptid) != 0 && !in_thread_list (ptid))
 393     thread_change_ptid (inferior_ptid, ptid);
 394
 395   /* Don't let the core see a ptid without a corresponding thread.  */
 396   if (!in_thread_list (ptid) || is_exited (ptid))
 397     add_thread (ptid);
 398
 399   return ptid;
 400 }
 401
 402 static void
 403 bsd_uthread_resume (struct target_ops *ops,
 404                     ptid_t ptid, int step, enum gdb_signal sig)
 405 {
 406   /* Pass the request to the layer beneath.  */
 407   struct target_ops *beneath = find_target_beneath (ops);
 408   beneath->to_resume (beneath, ptid, step, sig);
 409 }
 410
 411 static int
 412 bsd_uthread_thread_alive (struct target_ops *ops, ptid_t ptid)
 413 {
 414   enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
 415   struct target_ops *beneath = find_target_beneath (ops);
 416   CORE_ADDR addr = ptid_get_tid (ptid);
 417
 418   if (addr != 0)
 419     {
 420       int offset = bsd_uthread_thread_state_offset;
 421       ULONGEST state;
 422
 423       bsd_uthread_check_magic (addr);
 424
 425       state = read_memory_unsigned_integer (addr + offset, 4, byte_order);
 426       if (state == BSD_UTHREAD_PS_DEAD)
 427         return 0;
 428     }
 429
 430   return beneath->to_thread_alive (beneath, ptid);
 431 }
 432
 433 static void
 434 bsd_uthread_update_thread_list (struct target_ops *ops)
 435 {
 436   pid_t pid = ptid_get_pid (inferior_ptid);
 437   int offset = bsd_uthread_thread_next_offset;
 438   CORE_ADDR addr;
 439
 440   prune_threads ();
 441
 442   addr = bsd_uthread_read_memory_address (bsd_uthread_thread_list_addr);
 443   while (addr != 0)
 444     {
 445       ptid_t ptid = ptid_build (pid, 0, addr);
 446
 447       if (!in_thread_list (ptid) || is_exited (ptid))
 448         {
 449           /* If INFERIOR_PTID doesn't have a tid member yet, then ptid
 450              is still the initial thread of the process.  Notify GDB
 451              core about it.  */
 452           if (ptid_get_tid (inferior_ptid) == 0)
 453             thread_change_ptid (inferior_ptid, ptid);
 454           else
 455             add_thread (ptid);
 456         }
 457
 458       addr = bsd_uthread_read_memory_address (addr + offset);
 459     }
 460 }
 461
 462 /* Possible states a thread can be in.  */
 463 static const char *bsd_uthread_state[] =
 464 {
 465   "RUNNING",
 466   "SIGTHREAD",
 467   "MUTEX_WAIT",
 468   "COND_WAIT",
 469   "FDLR_WAIT",
 470   "FDLW_WAIT",
 471   "FDR_WAIT",
 472   "FDW_WAIT",
 473   "FILE_WAIT",
 474   "POLL_WAIT",
 475   "SELECT_WAIT",
 476   "SLEEP_WAIT",
 477   "WAIT_WAIT",
 478   "SIGSUSPEND",
 479   "SIGWAIT",
 480   "SPINBLOCK",
 481   "JOIN",
 482   "SUSPENDED",
 483   "DEAD",
 484   "DEADLOCK"
 485 };
 486
 487 /* Return a string describing th state of the thread specified by
 488    INFO.  */
 489
 490 static const char *
 491 bsd_uthread_extra_thread_info (struct target_ops *self,
 492                                struct thread_info *info)
 493 {
 494   enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
 495   CORE_ADDR addr = ptid_get_tid (info->ptid);
 496
 497   if (addr != 0)
 498     {
 499       int offset = bsd_uthread_thread_state_offset;
 500       ULONGEST state;
 501
 502       state = read_memory_unsigned_integer (addr + offset, 4, byte_order);
 503       if (state < ARRAY_SIZE (bsd_uthread_state))
 504         return bsd_uthread_state[state];
 505     }
 506
 507   return NULL;
 508 }
 509
 510 static const char *
 511 bsd_uthread_pid_to_str (struct target_ops *ops, ptid_t ptid)
 512 {
 513   if (ptid_get_tid (ptid) != 0)
 514     {
 515       static char buf[64];
 516
 517       xsnprintf (buf, sizeof buf, "process %d, thread 0x%lx",
 518                  ptid_get_pid (ptid), ptid_get_tid (ptid));
 519       return buf;
 520     }
 521
 522   return normal_pid_to_str (ptid);
 523 }
 524
 525 static struct target_ops *
 526 bsd_uthread_target (void)
 527 {
 528   struct target_ops *t = XCNEW (struct target_ops);
 529
 530   t->to_shortname = "bsd-uthreads";
 531   t->to_longname = "BSD user-level threads";
 532   t->to_doc = "BSD user-level threads";
 533   t->to_close = bsd_uthread_close;
 534   t->to_mourn_inferior = bsd_uthread_mourn_inferior;
 535   t->to_fetch_registers = bsd_uthread_fetch_registers;
 536   t->to_store_registers = bsd_uthread_store_registers;
 537   t->to_wait = bsd_uthread_wait;
 538   t->to_resume = bsd_uthread_resume;
 539   t->to_thread_alive = bsd_uthread_thread_alive;
 540   t->to_update_thread_list = bsd_uthread_update_thread_list;
 541   t->to_extra_thread_info = bsd_uthread_extra_thread_info;
 542   t->to_pid_to_str = bsd_uthread_pid_to_str;
 543   t->to_stratum = thread_stratum;
 544   t->to_magic = OPS_MAGIC;
 545   bsd_uthread_ops_hack = t;
 546
 547   return t;
 548 }
 549
 550 void
 551 _initialize_bsd_uthread (void)
 552 {
 553   complete_target_initialization (bsd_uthread_target ());
 554
 555   bsd_uthread_data = gdbarch_data_register_pre_init (bsd_uthread_init);
 556
 557   observer_attach_inferior_created (bsd_uthread_inferior_created);
 558   observer_attach_solib_loaded (bsd_uthread_solib_loaded);
 559   observer_attach_solib_unloaded (bsd_uthread_solib_unloaded);
 560 }