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