gdb/gdbserver/thread-db.c

   1 /* Thread management interface, for the remote server for GDB.
   2    Copyright (C) 2002, 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
   3
   4    Contributed by MontaVista Software.
   5
   6    This file is part of GDB.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 2 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program; if not, write to the Free Software
  20    Foundation, Inc., 51 Franklin Street, Fifth Floor,
  21    Boston, MA 02110-1301, USA.  */
  22
  23 #include "server.h"
  24
  25 #include "linux-low.h"
  26
  27 extern int debug_threads;
  28
  29 #ifdef HAVE_THREAD_DB_H
  30 #include <thread_db.h>
  31 #endif
  32
  33 #include "gdb_proc_service.h"
  34
  35 #include <stdint.h>
  36
  37 /* Structure that identifies the child process for the
  38    <proc_service.h> interface.  */
  39 static struct ps_prochandle proc_handle;
  40
  41 /* Connection to the libthread_db library.  */
  42 static td_thragent_t *thread_agent;
  43
  44 static int find_first_thread (void);
  45 static int find_new_threads_callback (const td_thrhandle_t *th_p, void *data);
  46
  47 static char *
  48 thread_db_err_str (td_err_e err)
  49 {
  50   static char buf[64];
  51
  52   switch (err)
  53     {
  54     case TD_OK:
  55       return "generic 'call succeeded'";
  56     case TD_ERR:
  57       return "generic error";
  58     case TD_NOTHR:
  59       return "no thread to satisfy query";
  60     case TD_NOSV:
  61       return "no sync handle to satisfy query";
  62     case TD_NOLWP:
  63       return "no LWP to satisfy query";
  64     case TD_BADPH:
  65       return "invalid process handle";
  66     case TD_BADTH:
  67       return "invalid thread handle";
  68     case TD_BADSH:
  69       return "invalid synchronization handle";
  70     case TD_BADTA:
  71       return "invalid thread agent";
  72     case TD_BADKEY:
  73       return "invalid key";
  74     case TD_NOMSG:
  75       return "no event message for getmsg";
  76     case TD_NOFPREGS:
  77       return "FPU register set not available";
  78     case TD_NOLIBTHREAD:
  79       return "application not linked with libthread";
  80     case TD_NOEVENT:
  81       return "requested event is not supported";
  82     case TD_NOCAPAB:
  83       return "capability not available";
  84     case TD_DBERR:
  85       return "debugger service failed";
  86     case TD_NOAPLIC:
  87       return "operation not applicable to";
  88     case TD_NOTSD:
  89       return "no thread-specific data for this thread";
  90     case TD_MALLOC:
  91       return "malloc failed";
  92     case TD_PARTIALREG:
  93       return "only part of register set was written/read";
  94     case TD_NOXREGS:
  95       return "X register set not available for this thread";
  96 #ifdef HAVE_TD_VERSION
  97     case TD_VERSION:
  98       return "version mismatch between libthread_db and libpthread";
  99 #endif
 100     default:
 101       snprintf (buf, sizeof (buf), "unknown thread_db error '%d'", err);
 102       return buf;
 103     }
 104 }
 105
 106 #if 0
 107 static char *
 108 thread_db_state_str (td_thr_state_e state)
 109 {
 110   static char buf[64];
 111
 112   switch (state)
 113     {
 114     case TD_THR_STOPPED:
 115       return "stopped by debugger";
 116     case TD_THR_RUN:
 117       return "runnable";
 118     case TD_THR_ACTIVE:
 119       return "active";
 120     case TD_THR_ZOMBIE:
 121       return "zombie";
 122     case TD_THR_SLEEP:
 123       return "sleeping";
 124     case TD_THR_STOPPED_ASLEEP:
 125       return "stopped by debugger AND blocked";
 126     default:
 127       snprintf (buf, sizeof (buf), "unknown thread_db state %d", state);
 128       return buf;
 129     }
 130 }
 131 #endif
 132
 133 static void
 134 thread_db_create_event (CORE_ADDR where)
 135 {
 136   td_event_msg_t msg;
 137   td_err_e err;
 138   struct process_info *process;
 139
 140   if (debug_threads)
 141     fprintf (stderr, "Thread creation event.\n");
 142
 143   /* FIXME: This assumes we don't get another event.
 144      In the LinuxThreads implementation, this is safe,
 145      because all events come from the manager thread
 146      (except for its own creation, of course).  */
 147   err = td_ta_event_getmsg (thread_agent, &msg);
 148   if (err != TD_OK)
 149     fprintf (stderr, "thread getmsg err: %s\n",
 150              thread_db_err_str (err));
 151
 152   /* If we do not know about the main thread yet, this would be a good time to
 153      find it.  We need to do this to pick up the main thread before any newly
 154      created threads.  */
 155   process = get_thread_process (current_inferior);
 156   if (process->thread_known == 0)
 157     find_first_thread ();
 158
 159   /* msg.event == TD_EVENT_CREATE */
 160
 161   find_new_threads_callback (msg.th_p, NULL);
 162 }
 163
 164 #if 0
 165 static void
 166 thread_db_death_event (CORE_ADDR where)
 167 {
 168   if (debug_threads)
 169     fprintf (stderr, "Thread death event.\n");
 170 }
 171 #endif
 172
 173 static int
 174 thread_db_enable_reporting ()
 175 {
 176   td_thr_events_t events;
 177   td_notify_t notify;
 178   td_err_e err;
 179
 180   /* Set the process wide mask saying which events we're interested in.  */
 181   td_event_emptyset (&events);
 182   td_event_addset (&events, TD_CREATE);
 183
 184 #if 0
 185   /* This is reported to be broken in glibc 2.1.3.  A different approach
 186      will be necessary to support that.  */
 187   td_event_addset (&events, TD_DEATH);
 188 #endif
 189
 190   err = td_ta_set_event (thread_agent, &events);
 191   if (err != TD_OK)
 192     {
 193       warning ("Unable to set global thread event mask: %s",
 194                thread_db_err_str (err));
 195       return 0;
 196     }
 197
 198   /* Get address for thread creation breakpoint.  */
 199   err = td_ta_event_addr (thread_agent, TD_CREATE, &notify);
 200   if (err != TD_OK)
 201     {
 202       warning ("Unable to get location for thread creation breakpoint: %s",
 203                thread_db_err_str (err));
 204       return 0;
 205     }
 206   set_breakpoint_at ((CORE_ADDR) (unsigned long) notify.u.bptaddr,
 207                      thread_db_create_event);
 208
 209 #if 0
 210   /* Don't concern ourselves with reported thread deaths, only
 211      with actual thread deaths (via wait).  */
 212
 213   /* Get address for thread death breakpoint.  */
 214   err = td_ta_event_addr (thread_agent, TD_DEATH, &notify);
 215   if (err != TD_OK)
 216     {
 217       warning ("Unable to get location for thread death breakpoint: %s",
 218                thread_db_err_str (err));
 219       return;
 220     }
 221   set_breakpoint_at ((CORE_ADDR) (unsigned long) notify.u.bptaddr,
 222                      thread_db_death_event);
 223 #endif
 224
 225   return 1;
 226 }
 227
 228 static int
 229 find_first_thread (void)
 230 {
 231   td_thrhandle_t th;
 232   td_thrinfo_t ti;
 233   td_err_e err;
 234   struct thread_info *inferior;
 235   struct process_info *process;
 236
 237   inferior = (struct thread_info *) all_threads.head;
 238   process = get_thread_process (inferior);
 239   if (process->thread_known)
 240     return 1;
 241
 242   /* Get information about the one thread we know we have.  */
 243   err = td_ta_map_lwp2thr (thread_agent, process->lwpid, &th);
 244   if (err != TD_OK)
 245     error ("Cannot get first thread handle: %s", thread_db_err_str (err));
 246
 247   err = td_thr_get_info (&th, &ti);
 248   if (err != TD_OK)
 249     error ("Cannot get first thread info: %s", thread_db_err_str (err));
 250
 251   if (debug_threads)
 252     fprintf (stderr, "Found first thread %ld (LWP %d)\n",
 253              ti.ti_tid, ti.ti_lid);
 254
 255   if (process->lwpid != ti.ti_lid)
 256     fatal ("PID mismatch!  Expected %ld, got %ld",
 257            (long) process->lwpid, (long) ti.ti_lid);
 258
 259   /* If the new thread ID is zero, a final thread ID will be available
 260      later.  Do not enable thread debugging yet.  */
 261   if (ti.ti_tid == 0)
 262     {
 263       err = td_thr_event_enable (&th, 1);
 264       if (err != TD_OK)
 265         error ("Cannot enable thread event reporting for %d: %s",
 266                ti.ti_lid, thread_db_err_str (err));
 267       return 0;
 268     }
 269
 270   /* Switch to indexing the threads list by TID.  */
 271   change_inferior_id (&all_threads, ti.ti_tid);
 272
 273   new_thread_notify (ti.ti_tid);
 274
 275   process->tid = ti.ti_tid;
 276   process->lwpid = ti.ti_lid;
 277   process->thread_known = 1;
 278   process->th = th;
 279
 280   err = td_thr_event_enable (&th, 1);
 281   if (err != TD_OK)
 282     error ("Cannot enable thread event reporting for %d: %s",
 283            ti.ti_lid, thread_db_err_str (err));
 284
 285   return 1;
 286 }
 287
 288 static void
 289 maybe_attach_thread (const td_thrhandle_t *th_p, td_thrinfo_t *ti_p)
 290 {
 291   td_err_e err;
 292   struct thread_info *inferior;
 293   struct process_info *process;
 294
 295   inferior = (struct thread_info *) find_inferior_id (&all_threads,
 296                                                       ti_p->ti_tid);
 297   if (inferior != NULL)
 298     return;
 299
 300   if (debug_threads)
 301     fprintf (stderr, "Attaching to thread %ld (LWP %d)\n",
 302              ti_p->ti_tid, ti_p->ti_lid);
 303   linux_attach_lwp (ti_p->ti_lid, ti_p->ti_tid);
 304   inferior = (struct thread_info *) find_inferior_id (&all_threads,
 305                                                       ti_p->ti_tid);
 306   if (inferior == NULL)
 307     {
 308       warning ("Could not attach to thread %ld (LWP %d)\n",
 309                ti_p->ti_tid, ti_p->ti_lid);
 310       return;
 311     }
 312
 313   process = inferior_target_data (inferior);
 314
 315   new_thread_notify (ti_p->ti_tid);
 316
 317   process->tid = ti_p->ti_tid;
 318   process->lwpid = ti_p->ti_lid;
 319
 320   process->thread_known = 1;
 321   process->th = *th_p;
 322   err = td_thr_event_enable (th_p, 1);
 323   if (err != TD_OK)
 324     error ("Cannot enable thread event reporting for %d: %s",
 325            ti_p->ti_lid, thread_db_err_str (err));
 326 }
 327
 328 static int
 329 find_new_threads_callback (const td_thrhandle_t *th_p, void *data)
 330 {
 331   td_thrinfo_t ti;
 332   td_err_e err;
 333
 334   err = td_thr_get_info (th_p, &ti);
 335   if (err != TD_OK)
 336     error ("Cannot get thread info: %s", thread_db_err_str (err));
 337
 338   /* Check for zombies.  */
 339   if (ti.ti_state == TD_THR_UNKNOWN || ti.ti_state == TD_THR_ZOMBIE)
 340     return 0;
 341
 342   maybe_attach_thread (th_p, &ti);
 343
 344   return 0;
 345 }
 346
 347 static void
 348 thread_db_find_new_threads (void)
 349 {
 350   td_err_e err;
 351
 352   /* This function is only called when we first initialize thread_db.
 353      First locate the initial thread.  If it is not ready for
 354      debugging yet, then stop.  */
 355   if (find_first_thread () == 0)
 356     return;
 357
 358   /* Iterate over all user-space threads to discover new threads.  */
 359   err = td_ta_thr_iter (thread_agent, find_new_threads_callback, NULL,
 360                         TD_THR_ANY_STATE, TD_THR_LOWEST_PRIORITY,
 361                         TD_SIGNO_MASK, TD_THR_ANY_USER_FLAGS);
 362   if (err != TD_OK)
 363     error ("Cannot find new threads: %s", thread_db_err_str (err));
 364 }
 365
 366 /* Cache all future symbols that thread_db might request.  We can not
 367    request symbols at arbitrary states in the remote protocol, only
 368    when the client tells us that new symbols are available.  So when
 369    we load the thread library, make sure to check the entire list.  */
 370
 371 static void
 372 thread_db_look_up_symbols (void)
 373 {
 374   const char **sym_list = td_symbol_list ();
 375   CORE_ADDR unused;
 376
 377   for (sym_list = td_symbol_list (); *sym_list; sym_list++)
 378     look_up_one_symbol (*sym_list, &unused);
 379 }
 380
 381 int
 382 thread_db_get_tls_address (struct thread_info *thread, CORE_ADDR offset,
 383                            CORE_ADDR load_module, CORE_ADDR *address)
 384 {
 385 #if HAVE_TD_THR_TLS_GET_ADDR
 386   psaddr_t addr;
 387   td_err_e err;
 388   struct process_info *process;
 389
 390   process = get_thread_process (thread);
 391   if (!process->thread_known)
 392     find_first_thread ();
 393   if (!process->thread_known)
 394     return TD_NOTHR;
 395
 396   /* Note the cast through uintptr_t: this interface only works if
 397      a target address fits in a psaddr_t, which is a host pointer.
 398      So a 32-bit debugger can not access 64-bit TLS through this.  */
 399   err = td_thr_tls_get_addr (&process->th, (psaddr_t) (uintptr_t) load_module,
 400                              offset, &addr);
 401   if (err == TD_OK)
 402     {
 403       *address = (CORE_ADDR) (uintptr_t) addr;
 404       return 0;
 405     }
 406   else
 407     return err;
 408 #else
 409   return -1;
 410 #endif
 411 }
 412
 413 int
 414 thread_db_init ()
 415 {
 416   int err;
 417
 418   /* FIXME drow/2004-10-16: This is the "overall process ID", which
 419      GNU/Linux calls tgid, "thread group ID".  When we support
 420      attaching to threads, the original thread may not be the correct
 421      thread.  We would have to get the process ID from /proc for NPTL.
 422      For LinuxThreads we could do something similar: follow the chain
 423      of parent processes until we find the highest one we're attached
 424      to, and use its tgid.
 425
 426      This isn't the only place in gdbserver that assumes that the first
 427      process in the list is the thread group leader.  */
 428   proc_handle.pid = ((struct inferior_list_entry *)current_inferior)->id;
 429
 430   /* Allow new symbol lookups.  */
 431   all_symbols_looked_up = 0;
 432
 433   err = td_ta_new (&proc_handle, &thread_agent);
 434   switch (err)
 435     {
 436     case TD_NOLIBTHREAD:
 437       /* No thread library was detected.  */
 438       return 0;
 439
 440     case TD_OK:
 441       /* The thread library was detected.  */
 442
 443       if (thread_db_enable_reporting () == 0)
 444         return 0;
 445       thread_db_find_new_threads ();
 446       thread_db_look_up_symbols ();
 447       all_symbols_looked_up = 1;
 448       return 1;
 449
 450     default:
 451       warning ("error initializing thread_db library: %s",
 452                thread_db_err_str (err));
 453     }
 454
 455   return 0;
 456 }