gdb/bsd-uthread.c

   1 /* BSD user-level threads support.
   2
   3    Copyright 2005 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 2 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, write to the Free Software
  19    Foundation, Inc., 59 Temple Place - Suite 330,
  20    Boston, MA 02111-1307, USA.  */
  21
  22 #include "defs.h"
  23 #include "gdbcore.h"
  24 #include "gdbthread.h"
  25 #include "inferior.h"
  26 #include "objfiles.h"
  27 #include "observer.h"
  28 #include "regcache.h"
  29 #include "solib.h"
  30 #include "solist.h"
  31 #include "symfile.h"
  32 #include "target.h"
  33
  34 #include "gdb_assert.h"
  35 #include "gdb_obstack.h"
  36
  37 #include "bsd-uthread.h"
  38
  39 /* HACK: Save the bsd_uthreads ops returned by bsd_uthread_target.  */
  40 static struct target_ops *bsd_uthread_ops_hack;
  41 \f
  42
  43 /* Architecture-specific operations.  */
  44
  45 /* Per-architecture data key.  */
  46 static struct gdbarch_data *bsd_uthread_data;
  47
  48 struct bsd_uthread_ops
  49 {
  50   /* Supply registers for an inactive thread to a register cache.  */
  51   void (*supply_uthread)(struct regcache *, int, CORE_ADDR);
  52
  53   /* Collect registers for an inactive thread from a register cache.  */
  54   void (*collect_uthread)(const struct regcache *, int, CORE_ADDR);
  55 };
  56
  57 static void *
  58 bsd_uthread_init (struct obstack *obstack)
  59 {
  60   struct bsd_uthread_ops *ops;
  61
  62   ops = OBSTACK_ZALLOC (obstack, struct bsd_uthread_ops);
  63   return ops;
  64 }
  65
  66 /* Set the function that supplies registers from an inactive thread
  67    for architecture GDBARCH to SUPPLY_UTHREAD.  */
  68
  69 void
  70 bsd_uthread_set_supply_uthread (struct gdbarch *gdbarch,
  71                                 void (*supply_uthread) (struct regcache *,
  72                                                         int, CORE_ADDR))
  73 {
  74   struct bsd_uthread_ops *ops = gdbarch_data (gdbarch, bsd_uthread_data);
  75   ops->supply_uthread = supply_uthread;
  76 }
  77
  78 /* Set the function that collects registers for an inactive thread for
  79    architecture GDBARCH to SUPPLY_UTHREAD.  */
  80
  81 void
  82 bsd_uthread_set_collect_uthread (struct gdbarch *gdbarch,
  83                          void (*collect_uthread) (const struct regcache *,
  84                                                   int, CORE_ADDR))
  85 {
  86   struct bsd_uthread_ops *ops = gdbarch_data (gdbarch, bsd_uthread_data);
  87   ops->collect_uthread = collect_uthread;
  88 }
  89
  90 /* Magic number to help recognize a valid thread structure.  */
  91 #define BSD_UTHREAD_PTHREAD_MAGIC       0xd09ba115
  92
  93 /* Check whether the thread structure at ADDR is valid.  */
  94
  95 static void
  96 bsd_uthread_check_magic (CORE_ADDR addr)
  97 {
  98   ULONGEST magic = read_memory_unsigned_integer (addr, 4);
  99
 100   if (magic != BSD_UTHREAD_PTHREAD_MAGIC)
 101     error (_("Bad magic"));
 102 }
 103
 104 /* Thread states.  */
 105 #define BSD_UTHREAD_PS_RUNNING  0
 106 #define BSD_UTHREAD_PS_DEAD     18
 107
 108 /* Address of the pointer to the the thread structure for the running
 109    thread.  */
 110 static CORE_ADDR bsd_uthread_thread_run_addr;
 111
 112 /* Address of the list of all threads.  */
 113 static CORE_ADDR bsd_uthread_thread_list_addr;
 114
 115 /* Offsets of various "interesting" bits in the thread structure.  */
 116 static int bsd_uthread_thread_state_offset = -1;
 117 static int bsd_uthread_thread_next_offset = -1;
 118 static int bsd_uthread_thread_ctx_offset;
 119
 120 /* Name of shared threads library.  */
 121 static const char *bsd_uthread_solib_name;
 122
 123 /* Non-zero if the thread startum implemented by this module is active.  */
 124 static int bsd_uthread_active;
 125
 126 static CORE_ADDR
 127 bsd_uthread_lookup_address (const char *name, struct objfile *objfile)
 128 {
 129   struct minimal_symbol *sym;
 130
 131   sym = lookup_minimal_symbol (name, NULL, objfile);
 132   if (sym)
 133     return SYMBOL_VALUE_ADDRESS (sym);
 134
 135   return 0;
 136 }
 137
 138 static int
 139 bsd_uthread_lookup_offset (const char *name, struct objfile *objfile)
 140 {
 141   CORE_ADDR addr;
 142
 143   addr = bsd_uthread_lookup_address (name, objfile);
 144   if (addr == 0)
 145     return 0;
 146
 147   return read_memory_unsigned_integer (addr, 4);
 148 }
 149
 150 /* If OBJFILE contains the symbols corresponding to one of the
 151    supported user-level threads libraries, activate the thread stratum
 152    implemented by this module.  */
 153
 154 static int
 155 bsd_uthread_activate (struct objfile *objfile)
 156 {
 157   struct gdbarch *gdbarch = current_gdbarch;
 158   struct bsd_uthread_ops *ops = gdbarch_data (gdbarch, bsd_uthread_data);
 159
 160   /* Skip if the thread stratum has already been activated.  */
 161   if (bsd_uthread_active)
 162     return 0;
 163
 164   /* There's no point in enabling this module if no
 165      architecture-specific operations are provided.  */
 166   if (!ops->supply_uthread)
 167     return 0;
 168
 169   bsd_uthread_thread_run_addr =
 170     bsd_uthread_lookup_address ("_thread_run", objfile);
 171   if (bsd_uthread_thread_run_addr == 0)
 172     return 0;
 173
 174   bsd_uthread_thread_list_addr =
 175     bsd_uthread_lookup_address ("_thread_list", objfile);
 176   if (bsd_uthread_thread_list_addr == 0)
 177     return 0;
 178
 179   bsd_uthread_thread_state_offset =
 180     bsd_uthread_lookup_offset ("_thread_state_offset", objfile);
 181   if (bsd_uthread_thread_state_offset == 0)
 182     return 0;
 183
 184   bsd_uthread_thread_next_offset =
 185     bsd_uthread_lookup_offset ("_thread_next_offset", objfile);
 186   if (bsd_uthread_thread_next_offset == 0)
 187     return 0;
 188
 189   bsd_uthread_thread_ctx_offset =
 190     bsd_uthread_lookup_offset ("_thread_ctx_offset", objfile);
 191
 192   push_target (bsd_uthread_ops_hack);
 193   bsd_uthread_active = 1;
 194   return 1;
 195 }
 196
 197 /* Deactivate the thread stratum implemented by this module.  */
 198
 199 static void
 200 bsd_uthread_deactivate (void)
 201 {
 202   /* Skip if the thread stratum has already been deactivated.  */
 203   if (!bsd_uthread_active)
 204     return;
 205
 206   bsd_uthread_active = 0;
 207   unpush_target (bsd_uthread_ops_hack);
 208
 209   bsd_uthread_thread_run_addr = 0;
 210   bsd_uthread_thread_list_addr = 0;
 211   bsd_uthread_thread_state_offset = 0;
 212   bsd_uthread_thread_next_offset = 0;
 213   bsd_uthread_thread_ctx_offset = 0;
 214   bsd_uthread_solib_name = NULL;
 215 }
 216
 217 void
 218 bsd_uthread_inferior_created (struct target_ops *ops, int from_tty)
 219 {
 220   bsd_uthread_activate (NULL);
 221 }
 222
 223 /* Likely candidates for the threads library.  */
 224 static const char *bsd_uthread_solib_names[] =
 225 {
 226   "/usr/lib/libc_r.so",         /* FreeBSD */
 227   "/usr/lib/libpthread.so",     /* OpenBSD */
 228   NULL
 229 };
 230
 231 void
 232 bsd_uthread_solib_loaded (struct so_list *so)
 233 {
 234   const char **names = bsd_uthread_solib_names;
 235
 236   for (names = bsd_uthread_solib_names; *names; names++)
 237     {
 238       if (strncmp (so->so_original_name, *names, strlen (*names)) == 0)
 239         {
 240           solib_read_symbols (so, so->from_tty);
 241
 242           if (bsd_uthread_activate (so->objfile))
 243             {
 244               bsd_uthread_solib_name == so->so_original_name;
 245               return;
 246             }
 247         }
 248     }
 249 }
 250
 251 void
 252 bsd_uthread_solib_unloaded (struct so_list *so)
 253 {
 254   if (!bsd_uthread_solib_name)
 255     return;
 256
 257   if (strcmp (so->so_original_name, bsd_uthread_solib_name) == 0)
 258     bsd_uthread_deactivate ();
 259 }
 260
 261 static void
 262 bsd_uthread_mourn_inferior (void)
 263 {
 264   find_target_beneath (bsd_uthread_ops_hack)->to_mourn_inferior ();
 265   bsd_uthread_deactivate ();
 266 }
 267
 268 static void
 269 bsd_uthread_fetch_registers (int regnum)
 270 {
 271   struct gdbarch *gdbarch = current_gdbarch;
 272   struct bsd_uthread_ops *ops = gdbarch_data (gdbarch, bsd_uthread_data);
 273   CORE_ADDR addr = ptid_get_tid (inferior_ptid);
 274   CORE_ADDR active_addr;
 275
 276   /* Always fetch the appropriate registers from the layer beneath.  */
 277   find_target_beneath (bsd_uthread_ops_hack)->to_fetch_registers (regnum);
 278
 279   /* FIXME: That might have gotten us more than we asked for.  Make
 280      sure we overwrite all relevant registers with values from the
 281      thread structure.  This can go once we fix the underlying target.  */
 282   regnum = -1;
 283
 284   active_addr = read_memory_typed_address (bsd_uthread_thread_run_addr,
 285                                            builtin_type_void_data_ptr);
 286   if (addr != 0 && addr != active_addr)
 287     {
 288       bsd_uthread_check_magic (addr);
 289       ops->supply_uthread (current_regcache, regnum,
 290                            addr + bsd_uthread_thread_ctx_offset);
 291     }
 292 }
 293
 294 static void
 295 bsd_uthread_store_registers (int regnum)
 296 {
 297   struct gdbarch *gdbarch = current_gdbarch;
 298   struct bsd_uthread_ops *ops = gdbarch_data (gdbarch, bsd_uthread_data);
 299   CORE_ADDR addr = ptid_get_tid (inferior_ptid);
 300   CORE_ADDR active_addr;
 301
 302   active_addr = read_memory_typed_address (bsd_uthread_thread_run_addr,
 303                                            builtin_type_void_data_ptr);
 304   if (addr != 0 && addr != active_addr)
 305     {
 306       bsd_uthread_check_magic (addr);
 307       ops->collect_uthread (current_regcache, regnum,
 308                             addr + bsd_uthread_thread_ctx_offset);
 309     }
 310   else
 311     {
 312       /* Updating the thread that is currently running; pass the
 313          request to the layer beneath.  */
 314       find_target_beneath (bsd_uthread_ops_hack)->to_store_registers (regnum);
 315     }
 316 }
 317
 318 /* FIXME: This function is only there because otherwise GDB tries to
 319    invoke deprecate_xfer_memory.  */
 320
 321 static LONGEST
 322 bsd_uthread_xfer_partial (struct target_ops *ops, enum target_object object,
 323                           const char *annex, gdb_byte *readbuf,
 324                           const gdb_byte *writebuf,
 325                           ULONGEST offset, LONGEST len)
 326 {
 327   gdb_assert (ops->beneath->to_xfer_partial);
 328   return ops->beneath->to_xfer_partial (ops->beneath, object, annex, readbuf,
 329                                         writebuf, offset, len);
 330 }
 331
 332 static ptid_t
 333 bsd_uthread_wait (ptid_t ptid, struct target_waitstatus *status)
 334 {
 335   CORE_ADDR addr;
 336
 337   /* Pass the request to the layer beneath.  */
 338   ptid = find_target_beneath (bsd_uthread_ops_hack)->to_wait (ptid, status);
 339
 340   /* Fetch the corresponding thread ID, and augment the returned
 341      process ID with it.  */
 342   addr = read_memory_typed_address (bsd_uthread_thread_run_addr,
 343                                     builtin_type_void_data_ptr);
 344   if (addr != 0)
 345     {
 346       gdb_byte buf[4];
 347
 348       /* FIXME: For executables linked statically with the threads
 349          library, we end up here before the program has actually been
 350          executed.  In that case ADDR will be garbage since it has
 351          been read from the wrong virtual memory image.  */
 352       if (target_read_memory (addr, buf, 4) == 0)
 353         {
 354           ULONGEST magic = extract_unsigned_integer (buf, 4);
 355           if (magic == BSD_UTHREAD_PTHREAD_MAGIC)
 356             ptid = ptid_build (ptid_get_pid (ptid), 0, addr);
 357         }
 358     }
 359
 360   /* HACK: Twiddle INFERIOR_PTID such that the initial thread of a
 361      process isn't recognized as a new thread.  */
 362   if (ptid_get_tid (ptid) != 0 && !in_thread_list (ptid)
 363       && ptid_get_tid (inferior_ptid) == 0)
 364     {
 365       add_thread (ptid);
 366       inferior_ptid = ptid;
 367     }
 368
 369   return ptid;
 370 }
 371
 372 static void
 373 bsd_uthread_resume (ptid_t ptid, int step, enum target_signal sig)
 374 {
 375   /* Pass the request to the layer beneath.  */
 376   find_target_beneath (bsd_uthread_ops_hack)->to_resume (ptid, step, sig);
 377 }
 378
 379 static int
 380 bsd_uthread_thread_alive (ptid_t ptid)
 381 {
 382   CORE_ADDR addr = ptid_get_tid (inferior_ptid);
 383
 384   if (addr != 0)
 385     {
 386       int offset = bsd_uthread_thread_state_offset;
 387       ULONGEST state;
 388
 389       bsd_uthread_check_magic (addr);
 390
 391       state = read_memory_unsigned_integer (addr + offset, 4);
 392       if (state == BSD_UTHREAD_PS_DEAD)
 393         return 0;
 394     }
 395
 396   return find_target_beneath (bsd_uthread_ops_hack)->to_thread_alive (ptid);
 397 }
 398
 399 static void
 400 bsd_uthread_find_new_threads (void)
 401 {
 402   pid_t pid = ptid_get_pid (inferior_ptid);
 403   int offset = bsd_uthread_thread_next_offset;
 404   CORE_ADDR addr;
 405
 406   addr = read_memory_typed_address (bsd_uthread_thread_list_addr,
 407                                     builtin_type_void_data_ptr);
 408   while (addr != 0)
 409     {
 410       ptid_t ptid = ptid_build (pid, 0, addr);
 411
 412       if (!in_thread_list (ptid))
 413         add_thread (ptid);
 414
 415       addr = read_memory_typed_address (addr + offset,
 416                                         builtin_type_void_data_ptr);
 417     }
 418 }
 419
 420 /* Possible states a thread can be in.  */
 421 static char *bsd_uthread_state[] =
 422 {
 423   "RUNNING",
 424   "SIGTHREAD",
 425   "MUTEX_WAIT",
 426   "COND_WAIT",
 427   "FDLR_WAIT",
 428   "FDLW_WAIT",
 429   "FDR_WAIT",
 430   "FDW_WAIT",
 431   "FILE_WAIT",
 432   "POLL_WAIT",
 433   "SELECT_WAIT",
 434   "SLEEP_WAIT",
 435   "WAIT_WAIT",
 436   "SIGSUSPEND",
 437   "SIGWAIT",
 438   "SPINBLOCK",
 439   "JOIN",
 440   "SUSPENDED",
 441   "DEAD",
 442   "DEADLOCK"
 443 };
 444
 445 /* Return a string describing th state of the thread specified by
 446    INFO.  */
 447
 448 static char *
 449 bsd_uthread_extra_thread_info (struct thread_info *info)
 450 {
 451   CORE_ADDR addr = ptid_get_tid (info->ptid);
 452
 453   if (addr != 0)
 454     {
 455       int offset = bsd_uthread_thread_state_offset;
 456       ULONGEST state;
 457
 458       state = read_memory_unsigned_integer (addr + offset, 4);
 459       if (state < ARRAY_SIZE (bsd_uthread_state))
 460         return bsd_uthread_state[state];
 461     }
 462
 463   return NULL;
 464 }
 465
 466 static char *
 467 bsd_uthread_pid_to_str (ptid_t ptid)
 468 {
 469   if (ptid_get_tid (ptid) != 0)
 470     {
 471       static char buf[64];
 472
 473       xsnprintf (buf, sizeof buf, "process %d, thread 0x%lx",
 474                  ptid_get_pid (ptid), ptid_get_tid (ptid));
 475       return buf;
 476     }
 477
 478   return normal_pid_to_str (ptid);
 479 }
 480
 481 struct target_ops *
 482 bsd_uthread_target (void)
 483 {
 484   struct target_ops *t = XZALLOC (struct target_ops);
 485
 486   t->to_shortname = "bsd-uthreads";
 487   t->to_longname = "BSD user-level threads";
 488   t->to_doc = "BSD user-level threads";
 489   t->to_mourn_inferior = bsd_uthread_mourn_inferior;
 490   t->to_fetch_registers = bsd_uthread_fetch_registers;
 491   t->to_store_registers = bsd_uthread_store_registers;
 492   t->to_xfer_partial = bsd_uthread_xfer_partial;
 493   t->to_wait = bsd_uthread_wait;
 494   t->to_resume = bsd_uthread_resume;
 495   t->to_thread_alive = bsd_uthread_thread_alive;
 496   t->to_find_new_threads = bsd_uthread_find_new_threads;
 497   t->to_extra_thread_info = bsd_uthread_extra_thread_info;
 498   t->to_pid_to_str = bsd_uthread_pid_to_str;
 499   t->to_stratum = thread_stratum;
 500   t->to_magic = OPS_MAGIC;
 501   bsd_uthread_ops_hack = t;
 502
 503   return t;
 504 }
 505
 506 void
 507 _initialize_bsd_uthread (void)
 508 {
 509   add_target (bsd_uthread_target ());
 510
 511   bsd_uthread_data = gdbarch_data_register_pre_init (bsd_uthread_init);
 512
 513   observer_attach_inferior_created (bsd_uthread_inferior_created);
 514   observer_attach_solib_loaded (bsd_uthread_solib_loaded);
 515   observer_attach_solib_unloaded (bsd_uthread_solib_unloaded);
 516 }