gdb/bsd-uthread.c

   1 /* BSD user-level threads support.
   2
   3    Copyright (C) 2005-2015 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 = get_regcache_arch (regcache);
 291   struct bsd_uthread_ops *uthread_ops
 292     = (struct bsd_uthread_ops *) gdbarch_data (gdbarch, bsd_uthread_data);
 293   CORE_ADDR addr = ptid_get_tid (inferior_ptid);
 294   struct target_ops *beneath = find_target_beneath (ops);
 295   CORE_ADDR active_addr;
 296
 297   /* Always fetch the appropriate registers from the layer beneath.  */
 298   beneath->to_fetch_registers (beneath, regcache, regnum);
 299
 300   /* FIXME: That might have gotten us more than we asked for.  Make
 301      sure we overwrite all relevant registers with values from the
 302      thread structure.  This can go once we fix the underlying target.  */
 303   regnum = -1;
 304
 305   active_addr = bsd_uthread_read_memory_address (bsd_uthread_thread_run_addr);
 306   if (addr != 0 && addr != active_addr)
 307     {
 308       bsd_uthread_check_magic (addr);
 309       uthread_ops->supply_uthread (regcache, regnum,
 310                                    addr + bsd_uthread_thread_ctx_offset);
 311     }
 312 }
 313
 314 static void
 315 bsd_uthread_store_registers (struct target_ops *ops,
 316                              struct regcache *regcache, int regnum)
 317 {
 318   struct gdbarch *gdbarch = get_regcache_arch (regcache);
 319   struct bsd_uthread_ops *uthread_ops
 320     = (struct bsd_uthread_ops *) gdbarch_data (gdbarch, bsd_uthread_data);
 321   struct target_ops *beneath = find_target_beneath (ops);
 322   CORE_ADDR addr = ptid_get_tid (inferior_ptid);
 323   CORE_ADDR active_addr;
 324
 325   active_addr = bsd_uthread_read_memory_address (bsd_uthread_thread_run_addr);
 326   if (addr != 0 && addr != active_addr)
 327     {
 328       bsd_uthread_check_magic (addr);
 329       uthread_ops->collect_uthread (regcache, regnum,
 330                                     addr + bsd_uthread_thread_ctx_offset);
 331     }
 332   else
 333     {
 334       /* Updating the thread that is currently running; pass the
 335          request to the layer beneath.  */
 336       beneath->to_store_registers (beneath, regcache, regnum);
 337     }
 338 }
 339
 340 static ptid_t
 341 bsd_uthread_wait (struct target_ops *ops,
 342                   ptid_t ptid, struct target_waitstatus *status, int options)
 343 {
 344   enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
 345   CORE_ADDR addr;
 346   struct target_ops *beneath = find_target_beneath (ops);
 347
 348   /* Pass the request to the layer beneath.  */
 349   ptid = beneath->to_wait (beneath, ptid, status, options);
 350
 351   /* If the process is no longer alive, there's no point in figuring
 352      out the thread ID.  It will fail anyway.  */
 353   if (status->kind == TARGET_WAITKIND_SIGNALLED
 354       || status->kind == TARGET_WAITKIND_EXITED)
 355     return ptid;
 356
 357   /* Fetch the corresponding thread ID, and augment the returned
 358      process ID with it.  */
 359   addr = bsd_uthread_read_memory_address (bsd_uthread_thread_run_addr);
 360   if (addr != 0)
 361     {
 362       gdb_byte buf[4];
 363
 364       /* FIXME: For executables linked statically with the threads
 365          library, we end up here before the program has actually been
 366          executed.  In that case ADDR will be garbage since it has
 367          been read from the wrong virtual memory image.  */
 368       if (target_read_memory (addr, buf, 4) == 0)
 369         {
 370           ULONGEST magic = extract_unsigned_integer (buf, 4, byte_order);
 371           if (magic == BSD_UTHREAD_PTHREAD_MAGIC)
 372             ptid = ptid_build (ptid_get_pid (ptid), 0, addr);
 373         }
 374     }
 375
 376   /* If INFERIOR_PTID doesn't have a tid member yet, and we now have a
 377      ptid with tid set, then ptid is still the initial thread of
 378      the process.  Notify GDB core about it.  */
 379   if (ptid_get_tid (inferior_ptid) == 0
 380       && ptid_get_tid (ptid) != 0 && !in_thread_list (ptid))
 381     thread_change_ptid (inferior_ptid, ptid);
 382
 383   /* Don't let the core see a ptid without a corresponding thread.  */
 384   if (!in_thread_list (ptid) || is_exited (ptid))
 385     add_thread (ptid);
 386
 387   return ptid;
 388 }
 389
 390 static void
 391 bsd_uthread_resume (struct target_ops *ops,
 392                     ptid_t ptid, int step, enum gdb_signal sig)
 393 {
 394   /* Pass the request to the layer beneath.  */
 395   struct target_ops *beneath = find_target_beneath (ops);
 396   beneath->to_resume (beneath, ptid, step, sig);
 397 }
 398
 399 static int
 400 bsd_uthread_thread_alive (struct target_ops *ops, ptid_t ptid)
 401 {
 402   enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
 403   struct target_ops *beneath = find_target_beneath (ops);
 404   CORE_ADDR addr = ptid_get_tid (inferior_ptid);
 405
 406   if (addr != 0)
 407     {
 408       int offset = bsd_uthread_thread_state_offset;
 409       ULONGEST state;
 410
 411       bsd_uthread_check_magic (addr);
 412
 413       state = read_memory_unsigned_integer (addr + offset, 4, byte_order);
 414       if (state == BSD_UTHREAD_PS_DEAD)
 415         return 0;
 416     }
 417
 418   return beneath->to_thread_alive (beneath, ptid);
 419 }
 420
 421 static void
 422 bsd_uthread_update_thread_list (struct target_ops *ops)
 423 {
 424   pid_t pid = ptid_get_pid (inferior_ptid);
 425   int offset = bsd_uthread_thread_next_offset;
 426   CORE_ADDR addr;
 427
 428   prune_threads ();
 429
 430   addr = bsd_uthread_read_memory_address (bsd_uthread_thread_list_addr);
 431   while (addr != 0)
 432     {
 433       ptid_t ptid = ptid_build (pid, 0, addr);
 434
 435       if (!in_thread_list (ptid) || is_exited (ptid))
 436         {
 437           /* If INFERIOR_PTID doesn't have a tid member yet, then ptid
 438              is still the initial thread of the process.  Notify GDB
 439              core about it.  */
 440           if (ptid_get_tid (inferior_ptid) == 0)
 441             thread_change_ptid (inferior_ptid, ptid);
 442           else
 443             add_thread (ptid);
 444         }
 445
 446       addr = bsd_uthread_read_memory_address (addr + offset);
 447     }
 448 }
 449
 450 /* Possible states a thread can be in.  */
 451 static char *bsd_uthread_state[] =
 452 {
 453   "RUNNING",
 454   "SIGTHREAD",
 455   "MUTEX_WAIT",
 456   "COND_WAIT",
 457   "FDLR_WAIT",
 458   "FDLW_WAIT",
 459   "FDR_WAIT",
 460   "FDW_WAIT",
 461   "FILE_WAIT",
 462   "POLL_WAIT",
 463   "SELECT_WAIT",
 464   "SLEEP_WAIT",
 465   "WAIT_WAIT",
 466   "SIGSUSPEND",
 467   "SIGWAIT",
 468   "SPINBLOCK",
 469   "JOIN",
 470   "SUSPENDED",
 471   "DEAD",
 472   "DEADLOCK"
 473 };
 474
 475 /* Return a string describing th state of the thread specified by
 476    INFO.  */
 477
 478 static char *
 479 bsd_uthread_extra_thread_info (struct target_ops *self,
 480                                struct thread_info *info)
 481 {
 482   enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
 483   CORE_ADDR addr = ptid_get_tid (info->ptid);
 484
 485   if (addr != 0)
 486     {
 487       int offset = bsd_uthread_thread_state_offset;
 488       ULONGEST state;
 489
 490       state = read_memory_unsigned_integer (addr + offset, 4, byte_order);
 491       if (state < ARRAY_SIZE (bsd_uthread_state))
 492         return bsd_uthread_state[state];
 493     }
 494
 495   return NULL;
 496 }
 497
 498 static char *
 499 bsd_uthread_pid_to_str (struct target_ops *ops, ptid_t ptid)
 500 {
 501   if (ptid_get_tid (ptid) != 0)
 502     {
 503       static char buf[64];
 504
 505       xsnprintf (buf, sizeof buf, "process %d, thread 0x%lx",
 506                  ptid_get_pid (ptid), ptid_get_tid (ptid));
 507       return buf;
 508     }
 509
 510   return normal_pid_to_str (ptid);
 511 }
 512
 513 static struct target_ops *
 514 bsd_uthread_target (void)
 515 {
 516   struct target_ops *t = XCNEW (struct target_ops);
 517
 518   t->to_shortname = "bsd-uthreads";
 519   t->to_longname = "BSD user-level threads";
 520   t->to_doc = "BSD user-level threads";
 521   t->to_close = bsd_uthread_close;
 522   t->to_mourn_inferior = bsd_uthread_mourn_inferior;
 523   t->to_fetch_registers = bsd_uthread_fetch_registers;
 524   t->to_store_registers = bsd_uthread_store_registers;
 525   t->to_wait = bsd_uthread_wait;
 526   t->to_resume = bsd_uthread_resume;
 527   t->to_thread_alive = bsd_uthread_thread_alive;
 528   t->to_update_thread_list = bsd_uthread_update_thread_list;
 529   t->to_extra_thread_info = bsd_uthread_extra_thread_info;
 530   t->to_pid_to_str = bsd_uthread_pid_to_str;
 531   t->to_stratum = thread_stratum;
 532   t->to_magic = OPS_MAGIC;
 533   bsd_uthread_ops_hack = t;
 534
 535   return t;
 536 }
 537
 538 /* Provide a prototype to silence -Wmissing-prototypes.  */
 539 extern initialize_file_ftype _initialize_bsd_uthread;
 540
 541 void
 542 _initialize_bsd_uthread (void)
 543 {
 544   complete_target_initialization (bsd_uthread_target ());
 545
 546   bsd_uthread_data = gdbarch_data_register_pre_init (bsd_uthread_init);
 547
 548   observer_attach_inferior_created (bsd_uthread_inferior_created);
 549   observer_attach_solib_loaded (bsd_uthread_solib_loaded);
 550   observer_attach_solib_unloaded (bsd_uthread_solib_unloaded);
 551 }