gdb/gdbserver/thread-db.c

   1 /* Thread management interface, for the remote server for GDB.
   2    Copyright (C) 2002, 2004, 2005, 2006, 2007, 2008, 2009
   3    Free Software Foundation, Inc.
   4
   5    Contributed by MontaVista Software.
   6
   7    This file is part of GDB.
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  21
  22 #include "server.h"
  23
  24 #include "linux-low.h"
  25
  26 extern int debug_threads;
  27
  28 static int thread_db_use_events;
  29
  30 #ifdef HAVE_THREAD_DB_H
  31 #include <thread_db.h>
  32 #endif
  33
  34 #include "gdb_proc_service.h"
  35
  36 #include <stdint.h>
  37
  38 static int find_one_thread (ptid_t);
  39 static int find_new_threads_callback (const td_thrhandle_t *th_p, void *data);
  40
  41 static const char *
  42 thread_db_err_str (td_err_e err)
  43 {
  44   static char buf[64];
  45
  46   switch (err)
  47     {
  48     case TD_OK:
  49       return "generic 'call succeeded'";
  50     case TD_ERR:
  51       return "generic error";
  52     case TD_NOTHR:
  53       return "no thread to satisfy query";
  54     case TD_NOSV:
  55       return "no sync handle to satisfy query";
  56     case TD_NOLWP:
  57       return "no LWP to satisfy query";
  58     case TD_BADPH:
  59       return "invalid process handle";
  60     case TD_BADTH:
  61       return "invalid thread handle";
  62     case TD_BADSH:
  63       return "invalid synchronization handle";
  64     case TD_BADTA:
  65       return "invalid thread agent";
  66     case TD_BADKEY:
  67       return "invalid key";
  68     case TD_NOMSG:
  69       return "no event message for getmsg";
  70     case TD_NOFPREGS:
  71       return "FPU register set not available";
  72     case TD_NOLIBTHREAD:
  73       return "application not linked with libthread";
  74     case TD_NOEVENT:
  75       return "requested event is not supported";
  76     case TD_NOCAPAB:
  77       return "capability not available";
  78     case TD_DBERR:
  79       return "debugger service failed";
  80     case TD_NOAPLIC:
  81       return "operation not applicable to";
  82     case TD_NOTSD:
  83       return "no thread-specific data for this thread";
  84     case TD_MALLOC:
  85       return "malloc failed";
  86     case TD_PARTIALREG:
  87       return "only part of register set was written/read";
  88     case TD_NOXREGS:
  89       return "X register set not available for this thread";
  90 #ifdef HAVE_TD_VERSION
  91     case TD_VERSION:
  92       return "version mismatch between libthread_db and libpthread";
  93 #endif
  94     default:
  95       snprintf (buf, sizeof (buf), "unknown thread_db error '%d'", err);
  96       return buf;
  97     }
  98 }
  99
 100 #if 0
 101 static char *
 102 thread_db_state_str (td_thr_state_e state)
 103 {
 104   static char buf[64];
 105
 106   switch (state)
 107     {
 108     case TD_THR_STOPPED:
 109       return "stopped by debugger";
 110     case TD_THR_RUN:
 111       return "runnable";
 112     case TD_THR_ACTIVE:
 113       return "active";
 114     case TD_THR_ZOMBIE:
 115       return "zombie";
 116     case TD_THR_SLEEP:
 117       return "sleeping";
 118     case TD_THR_STOPPED_ASLEEP:
 119       return "stopped by debugger AND blocked";
 120     default:
 121       snprintf (buf, sizeof (buf), "unknown thread_db state %d", state);
 122       return buf;
 123     }
 124 }
 125 #endif
 126
 127 static int
 128 thread_db_create_event (CORE_ADDR where)
 129 {
 130   td_event_msg_t msg;
 131   td_err_e err;
 132   struct lwp_info *lwp;
 133   struct process_info_private *proc = current_process()->private;
 134
 135   if (debug_threads)
 136     fprintf (stderr, "Thread creation event.\n");
 137
 138   /* FIXME: This assumes we don't get another event.
 139      In the LinuxThreads implementation, this is safe,
 140      because all events come from the manager thread
 141      (except for its own creation, of course).  */
 142   err = td_ta_event_getmsg (proc->thread_agent, &msg);
 143   if (err != TD_OK)
 144     fprintf (stderr, "thread getmsg err: %s\n",
 145              thread_db_err_str (err));
 146
 147   /* If we do not know about the main thread yet, this would be a good time to
 148      find it.  We need to do this to pick up the main thread before any newly
 149      created threads.  */
 150   lwp = get_thread_lwp (current_inferior);
 151   if (lwp->thread_known == 0)
 152     find_one_thread (lwp->head.id);
 153
 154   /* msg.event == TD_EVENT_CREATE */
 155
 156   find_new_threads_callback (msg.th_p, NULL);
 157
 158   return 0;
 159 }
 160
 161 #if 0
 162 static int
 163 thread_db_death_event (CORE_ADDR where)
 164 {
 165   if (debug_threads)
 166     fprintf (stderr, "Thread death event.\n");
 167
 168   return 0;
 169 }
 170 #endif
 171
 172 static int
 173 thread_db_enable_reporting ()
 174 {
 175   td_thr_events_t events;
 176   td_notify_t notify;
 177   td_err_e err;
 178   struct process_info_private *proc = current_process()->private;
 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 (proc->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 (proc->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 (proc->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_one_thread (ptid_t ptid)
 230 {
 231   td_thrhandle_t th;
 232   td_thrinfo_t ti;
 233   td_err_e err;
 234   struct thread_info *inferior;
 235   struct lwp_info *lwp;
 236   struct process_info_private *proc = current_process()->private;
 237   int lwpid = ptid_get_lwp (ptid);
 238
 239   inferior = (struct thread_info *) find_inferior_id (&all_threads, ptid);
 240   lwp = get_thread_lwp (inferior);
 241   if (lwp->thread_known)
 242     return 1;
 243
 244   /* Get information about this thread.  */
 245   err = td_ta_map_lwp2thr (proc->thread_agent, lwpid, &th);
 246   if (err != TD_OK)
 247     error ("Cannot get thread handle for LWP %d: %s",
 248            lwpid, thread_db_err_str (err));
 249
 250   err = td_thr_get_info (&th, &ti);
 251   if (err != TD_OK)
 252     error ("Cannot get thread info for LWP %d: %s",
 253            lwpid, thread_db_err_str (err));
 254
 255   if (debug_threads)
 256     fprintf (stderr, "Found thread %ld (LWP %d)\n",
 257              ti.ti_tid, ti.ti_lid);
 258
 259   if (lwpid != ti.ti_lid)
 260     {
 261       warning ("PID mismatch!  Expected %ld, got %ld",
 262                (long) lwpid, (long) ti.ti_lid);
 263       return 0;
 264     }
 265
 266   if (thread_db_use_events)
 267     {
 268       err = td_thr_event_enable (&th, 1);
 269       if (err != TD_OK)
 270         error ("Cannot enable thread event reporting for %d: %s",
 271                ti.ti_lid, thread_db_err_str (err));
 272     }
 273
 274   /* If the new thread ID is zero, a final thread ID will be available
 275      later.  Do not enable thread debugging yet.  */
 276   if (ti.ti_tid == 0)
 277     return 0;
 278
 279   lwp->thread_known = 1;
 280   lwp->th = th;
 281
 282   return 1;
 283 }
 284
 285 static void
 286 maybe_attach_thread (const td_thrhandle_t *th_p, td_thrinfo_t *ti_p)
 287 {
 288   td_err_e err;
 289   struct lwp_info *lwp;
 290
 291   lwp = find_lwp_pid (pid_to_ptid (ti_p->ti_lid));
 292   if (lwp != NULL)
 293     return;
 294
 295   if (debug_threads)
 296     fprintf (stderr, "Attaching to thread %ld (LWP %d)\n",
 297              ti_p->ti_tid, ti_p->ti_lid);
 298   linux_attach_lwp (ti_p->ti_lid);
 299   lwp = find_lwp_pid (pid_to_ptid (ti_p->ti_lid));
 300   if (lwp == NULL)
 301     {
 302       warning ("Could not attach to thread %ld (LWP %d)\n",
 303                ti_p->ti_tid, ti_p->ti_lid);
 304       return;
 305     }
 306
 307   lwp->thread_known = 1;
 308   lwp->th = *th_p;
 309
 310   if (thread_db_use_events)
 311     {
 312       err = td_thr_event_enable (th_p, 1);
 313       if (err != TD_OK)
 314         error ("Cannot enable thread event reporting for %d: %s",
 315                ti_p->ti_lid, thread_db_err_str (err));
 316     }
 317 }
 318
 319 static int
 320 find_new_threads_callback (const td_thrhandle_t *th_p, void *data)
 321 {
 322   td_thrinfo_t ti;
 323   td_err_e err;
 324
 325   err = td_thr_get_info (th_p, &ti);
 326   if (err != TD_OK)
 327     error ("Cannot get thread info: %s", thread_db_err_str (err));
 328
 329   /* Check for zombies.  */
 330   if (ti.ti_state == TD_THR_UNKNOWN || ti.ti_state == TD_THR_ZOMBIE)
 331     return 0;
 332
 333   maybe_attach_thread (th_p, &ti);
 334
 335   return 0;
 336 }
 337
 338 static void
 339 thread_db_find_new_threads (void)
 340 {
 341   td_err_e err;
 342   ptid_t ptid = ((struct inferior_list_entry *) current_inferior)->id;
 343   struct process_info_private *proc = current_process()->private;
 344
 345   /* This function is only called when we first initialize thread_db.
 346      First locate the initial thread.  If it is not ready for
 347      debugging yet, then stop.  */
 348   if (find_one_thread (ptid) == 0)
 349     return;
 350
 351   /* Iterate over all user-space threads to discover new threads.  */
 352   err = td_ta_thr_iter (proc->thread_agent,
 353                         find_new_threads_callback, NULL,
 354                         TD_THR_ANY_STATE, TD_THR_LOWEST_PRIORITY,
 355                         TD_SIGNO_MASK, TD_THR_ANY_USER_FLAGS);
 356   if (err != TD_OK)
 357     error ("Cannot find new threads: %s", thread_db_err_str (err));
 358 }
 359
 360 /* Cache all future symbols that thread_db might request.  We can not
 361    request symbols at arbitrary states in the remote protocol, only
 362    when the client tells us that new symbols are available.  So when
 363    we load the thread library, make sure to check the entire list.  */
 364
 365 static void
 366 thread_db_look_up_symbols (void)
 367 {
 368   const char **sym_list = td_symbol_list ();
 369   CORE_ADDR unused;
 370
 371   for (sym_list = td_symbol_list (); *sym_list; sym_list++)
 372     look_up_one_symbol (*sym_list, &unused);
 373 }
 374
 375 int
 376 thread_db_get_tls_address (struct thread_info *thread, CORE_ADDR offset,
 377                            CORE_ADDR load_module, CORE_ADDR *address)
 378 {
 379 #if HAVE_TD_THR_TLS_GET_ADDR
 380   psaddr_t addr;
 381   td_err_e err;
 382   struct lwp_info *lwp;
 383   struct thread_info *saved_inferior;
 384
 385   lwp = get_thread_lwp (thread);
 386   if (!lwp->thread_known)
 387     find_one_thread (lwp->head.id);
 388   if (!lwp->thread_known)
 389     return TD_NOTHR;
 390
 391   saved_inferior = current_inferior;
 392   current_inferior = thread;
 393   /* Note the cast through uintptr_t: this interface only works if
 394      a target address fits in a psaddr_t, which is a host pointer.
 395      So a 32-bit debugger can not access 64-bit TLS through this.  */
 396   err = td_thr_tls_get_addr (&lwp->th, (psaddr_t) (uintptr_t) load_module,
 397                              offset, &addr);
 398   current_inferior = saved_inferior;
 399   if (err == TD_OK)
 400     {
 401       *address = (CORE_ADDR) (uintptr_t) addr;
 402       return 0;
 403     }
 404   else
 405     return err;
 406 #else
 407   return -1;
 408 #endif
 409 }
 410
 411 int
 412 thread_db_init (int use_events)
 413 {
 414   int err;
 415   struct process_info *proc = current_process ();
 416   struct process_info_private *priv = proc->private;
 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
 429   thread_db_use_events = use_events;
 430
 431   err = td_ta_new (&priv->proc_handle, &priv->thread_agent);
 432   switch (err)
 433     {
 434     case TD_NOLIBTHREAD:
 435       /* No thread library was detected.  */
 436       return 0;
 437
 438     case TD_OK:
 439       /* The thread library was detected.  */
 440
 441       if (use_events && thread_db_enable_reporting () == 0)
 442         return 0;
 443       thread_db_find_new_threads ();
 444       thread_db_look_up_symbols ();
 445       proc->all_symbols_looked_up = 1;
 446       return 1;
 447
 448     default:
 449       warning ("error initializing thread_db library: %s",
 450                thread_db_err_str (err));
 451     }
 452
 453   return 0;
 454 }