1 /* libthread_db assisted debugging support, generic parts.
3 Copyright (C) 1999, 2000, 2001, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
4 2010 Free Software Foundation, Inc.
6 This file is part of GDB.
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 3 of the License, or
11 (at your option) any later version.
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.
18 You should have received a copy of the GNU General Public License
19 along with this program. If not, see <http://www.gnu.org/licenses/>. */
23 #include "gdb_assert.h"
25 #include "gdb_proc_service.h"
26 #include "gdb_thread_db.h"
30 #include "exceptions.h"
32 #include "gdbthread.h"
39 #include "solib-svr4.h"
42 #include "linux-nat.h"
46 #ifdef HAVE_GNU_LIBC_VERSION_H
47 #include <gnu/libc-version.h>
50 /* GNU/Linux libthread_db support.
52 libthread_db is a library, provided along with libpthread.so, which
53 exposes the internals of the thread library to a debugger. It
54 allows GDB to find existing threads, new threads as they are
55 created, thread IDs (usually, the result of pthread_self), and
56 thread-local variables.
58 The libthread_db interface originates on Solaris, where it is
59 both more powerful and more complicated. This implementation
60 only works for LinuxThreads and NPTL, the two glibc threading
61 libraries. It assumes that each thread is permanently assigned
62 to a single light-weight process (LWP).
64 libthread_db-specific information is stored in the "private" field
65 of struct thread_info. When the field is NULL we do not yet have
66 information about the new thread; this could be temporary (created,
67 but the thread library's data structures do not reflect it yet)
68 or permanent (created using clone instead of pthread_create).
70 Process IDs managed by linux-thread-db.c match those used by
71 linux-nat.c: a common PID for all processes, an LWP ID for each
72 thread, and no TID. We save the TID in private. Keeping it out
73 of the ptid_t prevents thread IDs changing when libpthread is
74 loaded or unloaded. */
76 static char *libthread_db_search_path;
78 /* If we're running on GNU/Linux, we must explicitly attach to any new
81 /* This module's target vector. */
82 static struct target_ops thread_db_ops;
84 /* Non-zero if we have determined the signals used by the threads
86 static int thread_signals;
87 static sigset_t thread_stop_set;
88 static sigset_t thread_print_set;
92 struct thread_db_info *next;
94 /* Process id this object refers to. */
97 /* Handle from dlopen for libthread_db.so. */
100 /* Structure that identifies the child process for the
101 <proc_service.h> interface. */
102 struct ps_prochandle proc_handle;
104 /* Connection to the libthread_db library. */
105 td_thragent_t *thread_agent;
107 /* True if we need to apply the workaround for glibc/BZ5983. When
108 we catch a PTRACE_O_TRACEFORK, and go query the child's thread
109 list, nptl_db returns the parent's threads in addition to the new
110 (single) child thread. If this flag is set, we do extra work to
111 be able to ignore such stale entries. */
112 int need_stale_parent_threads_check;
114 /* Location of the thread creation event breakpoint. The code at
115 this location in the child process will be called by the pthread
116 library whenever a new thread is created. By setting a special
117 breakpoint at this location, GDB can detect when a new thread is
118 created. We obtain this location via the td_ta_event_addr
120 CORE_ADDR td_create_bp_addr;
122 /* Location of the thread death event breakpoint. */
123 CORE_ADDR td_death_bp_addr;
125 /* Pointers to the libthread_db functions. */
127 td_err_e (*td_init_p) (void);
129 td_err_e (*td_ta_new_p) (struct ps_prochandle * ps,
131 td_err_e (*td_ta_map_id2thr_p) (const td_thragent_t *ta, thread_t pt,
132 td_thrhandle_t *__th);
133 td_err_e (*td_ta_map_lwp2thr_p) (const td_thragent_t *ta,
134 lwpid_t lwpid, td_thrhandle_t *th);
135 td_err_e (*td_ta_thr_iter_p) (const td_thragent_t *ta,
136 td_thr_iter_f *callback, void *cbdata_p,
137 td_thr_state_e state, int ti_pri,
138 sigset_t *ti_sigmask_p,
139 unsigned int ti_user_flags);
140 td_err_e (*td_ta_event_addr_p) (const td_thragent_t *ta,
141 td_event_e event, td_notify_t *ptr);
142 td_err_e (*td_ta_set_event_p) (const td_thragent_t *ta,
143 td_thr_events_t *event);
144 td_err_e (*td_ta_clear_event_p) (const td_thragent_t *ta,
145 td_thr_events_t *event);
146 td_err_e (*td_ta_event_getmsg_p) (const td_thragent_t *ta,
147 td_event_msg_t *msg);
149 td_err_e (*td_thr_validate_p) (const td_thrhandle_t *th);
150 td_err_e (*td_thr_get_info_p) (const td_thrhandle_t *th,
151 td_thrinfo_t *infop);
152 td_err_e (*td_thr_event_enable_p) (const td_thrhandle_t *th,
155 td_err_e (*td_thr_tls_get_addr_p) (const td_thrhandle_t *th,
156 psaddr_t map_address,
157 size_t offset, psaddr_t *address);
160 /* List of known processes using thread_db, and the required
162 struct thread_db_info *thread_db_list;
164 static void thread_db_find_new_threads_1 (ptid_t ptid);
165 static void thread_db_find_new_threads_2 (ptid_t ptid, int until_no_new);
167 /* Add the current inferior to the list of processes using libpthread.
168 Return a pointer to the newly allocated object that was added to
169 THREAD_DB_LIST. HANDLE is the handle returned by dlopen'ing
172 static struct thread_db_info *
173 add_thread_db_info (void *handle)
175 struct thread_db_info *info;
177 info = xcalloc (1, sizeof (*info));
178 info->pid = ptid_get_pid (inferior_ptid);
179 info->handle = handle;
180 info->need_stale_parent_threads_check = 1;
182 info->next = thread_db_list;
183 thread_db_list = info;
188 /* Return the thread_db_info object representing the bookkeeping
189 related to process PID, if any; NULL otherwise. */
191 static struct thread_db_info *
192 get_thread_db_info (int pid)
194 struct thread_db_info *info;
196 for (info = thread_db_list; info; info = info->next)
197 if (pid == info->pid)
203 /* When PID has exited or has been detached, we no longer want to keep
204 track of it as using libpthread. Call this function to discard
205 thread_db related info related to PID. Note that this closes
206 LIBTHREAD_DB_SO's dlopen'ed handle. */
209 delete_thread_db_info (int pid)
211 struct thread_db_info *info, *info_prev;
215 for (info = thread_db_list; info; info_prev = info, info = info->next)
216 if (pid == info->pid)
222 if (info->handle != NULL)
223 dlclose (info->handle);
226 info_prev->next = info->next;
228 thread_db_list = info->next;
233 /* Prototypes for local functions. */
234 static int attach_thread (ptid_t ptid, const td_thrhandle_t *th_p,
235 const td_thrinfo_t *ti_p);
236 static void detach_thread (ptid_t ptid);
239 /* Use "struct private_thread_info" to cache thread state. This is
240 a substantial optimization. */
242 struct private_thread_info
244 /* Flag set when we see a TD_DEATH event for this thread. */
245 unsigned int dying:1;
247 /* Cached thread state. */
254 thread_db_err_str (td_err_e err)
261 return "generic 'call succeeded'";
263 return "generic error";
265 return "no thread to satisfy query";
267 return "no sync handle to satisfy query";
269 return "no LWP to satisfy query";
271 return "invalid process handle";
273 return "invalid thread handle";
275 return "invalid synchronization handle";
277 return "invalid thread agent";
279 return "invalid key";
281 return "no event message for getmsg";
283 return "FPU register set not available";
285 return "application not linked with libthread";
287 return "requested event is not supported";
289 return "capability not available";
291 return "debugger service failed";
293 return "operation not applicable to";
295 return "no thread-specific data for this thread";
297 return "malloc failed";
299 return "only part of register set was written/read";
301 return "X register set not available for this thread";
302 #ifdef THREAD_DB_HAS_TD_NOTALLOC
304 return "thread has not yet allocated TLS for given module";
306 #ifdef THREAD_DB_HAS_TD_VERSION
308 return "versions of libpthread and libthread_db do not match";
310 #ifdef THREAD_DB_HAS_TD_NOTLS
312 return "there is no TLS segment in the given module";
315 snprintf (buf, sizeof (buf), "unknown thread_db error '%d'", err);
320 /* Return 1 if any threads have been registered. There may be none if
321 the threading library is not fully initialized yet. */
324 have_threads_callback (struct thread_info *thread, void *args)
326 int pid = * (int *) args;
328 if (ptid_get_pid (thread->ptid) != pid)
331 return thread->private != NULL;
335 have_threads (ptid_t ptid)
337 int pid = ptid_get_pid (ptid);
339 return iterate_over_threads (have_threads_callback, &pid) != NULL;
342 struct thread_get_info_inout
344 struct thread_info *thread_info;
345 struct thread_db_info *thread_db_info;
348 /* A callback function for td_ta_thr_iter, which we use to map all
351 THP is a handle to the current thread; if INFOP is not NULL, the
352 struct thread_info associated with this thread is returned in
355 If the thread is a zombie, TD_THR_ZOMBIE is returned. Otherwise,
356 zero is returned to indicate success. */
359 thread_get_info_callback (const td_thrhandle_t *thp, void *argp)
364 struct thread_get_info_inout *inout;
365 struct thread_db_info *info;
368 info = inout->thread_db_info;
370 err = info->td_thr_get_info_p (thp, &ti);
372 error (_("thread_get_info_callback: cannot get thread info: %s"),
373 thread_db_err_str (err));
375 /* Fill the cache. */
376 thread_ptid = ptid_build (info->pid, ti.ti_lid, 0);
377 inout->thread_info = find_thread_ptid (thread_ptid);
379 /* In the case of a zombie thread, don't continue. We don't want to
380 attach to it thinking it is a new thread. */
381 if (ti.ti_state == TD_THR_UNKNOWN || ti.ti_state == TD_THR_ZOMBIE)
382 return TD_THR_ZOMBIE;
384 if (inout->thread_info == NULL)
386 /* New thread. Attach to it now (why wait?). */
387 if (!have_threads (thread_ptid))
388 thread_db_find_new_threads_1 (thread_ptid);
390 attach_thread (thread_ptid, thp, &ti);
391 inout->thread_info = find_thread_ptid (thread_ptid);
392 gdb_assert (inout->thread_info != NULL);
398 /* Convert between user-level thread ids and LWP ids. */
401 thread_from_lwp (ptid_t ptid)
405 struct thread_db_info *info;
406 struct thread_get_info_inout io = {0};
408 /* This ptid comes from linux-nat.c, which should always fill in the
410 gdb_assert (GET_LWP (ptid) != 0);
412 info = get_thread_db_info (GET_PID (ptid));
414 /* Access an lwp we know is stopped. */
415 info->proc_handle.ptid = ptid;
416 err = info->td_ta_map_lwp2thr_p (info->thread_agent, GET_LWP (ptid), &th);
418 error (_("Cannot find user-level thread for LWP %ld: %s"),
419 GET_LWP (ptid), thread_db_err_str (err));
421 /* Fetch the thread info. If we get back TD_THR_ZOMBIE, then the
422 event thread has already died. If another gdb interface has called
423 thread_alive() previously, the thread won't be found on the thread list
424 anymore. In that case, we don't want to process this ptid anymore
425 to avoid the possibility of later treating it as a newly
426 discovered thread id that we should add to the list. Thus,
427 we return a -1 ptid which is also how the thread list marks a
429 io.thread_db_info = info;
430 io.thread_info = NULL;
431 if (thread_get_info_callback (&th, &io) == TD_THR_ZOMBIE
432 && io.thread_info == NULL)
433 return minus_one_ptid;
435 gdb_assert (ptid_get_tid (ptid) == 0);
440 /* Attach to lwp PTID, doing whatever else is required to have this
441 LWP under the debugger's control --- e.g., enabling event
442 reporting. Returns true on success. */
444 thread_db_attach_lwp (ptid_t ptid)
449 struct thread_db_info *info;
451 info = get_thread_db_info (GET_PID (ptid));
456 /* This ptid comes from linux-nat.c, which should always fill in the
458 gdb_assert (GET_LWP (ptid) != 0);
460 /* Access an lwp we know is stopped. */
461 info->proc_handle.ptid = ptid;
463 /* If we have only looked at the first thread before libpthread was
464 initialized, we may not know its thread ID yet. Make sure we do
465 before we add another thread to the list. */
466 if (!have_threads (ptid))
467 thread_db_find_new_threads_1 (ptid);
469 err = info->td_ta_map_lwp2thr_p (info->thread_agent, GET_LWP (ptid), &th);
471 /* Cannot find user-level thread. */
474 err = info->td_thr_get_info_p (&th, &ti);
477 warning (_("Cannot get thread info: %s"), thread_db_err_str (err));
481 attach_thread (ptid, &th, &ti);
486 verbose_dlsym (void *handle, const char *name)
488 void *sym = dlsym (handle, name);
490 warning (_("Symbol \"%s\" not found in libthread_db: %s"), name, dlerror ());
495 enable_thread_event (int event, CORE_ADDR *bp)
499 struct thread_db_info *info;
501 info = get_thread_db_info (GET_PID (inferior_ptid));
503 /* Access an lwp we know is stopped. */
504 info->proc_handle.ptid = inferior_ptid;
506 /* Get the breakpoint address for thread EVENT. */
507 err = info->td_ta_event_addr_p (info->thread_agent, event, ¬ify);
511 /* Set up the breakpoint. */
512 gdb_assert (exec_bfd);
513 (*bp) = (gdbarch_convert_from_func_ptr_addr
515 /* Do proper sign extension for the target. */
516 (bfd_get_sign_extend_vma (exec_bfd) > 0
517 ? (CORE_ADDR) (intptr_t) notify.u.bptaddr
518 : (CORE_ADDR) (uintptr_t) notify.u.bptaddr),
520 create_thread_event_breakpoint (target_gdbarch, *bp);
526 enable_thread_event_reporting (void)
528 td_thr_events_t events;
530 #ifdef HAVE_GNU_LIBC_VERSION_H
531 const char *libc_version;
532 int libc_major, libc_minor;
534 struct thread_db_info *info;
536 info = get_thread_db_info (GET_PID (inferior_ptid));
538 /* We cannot use the thread event reporting facility if these
539 functions aren't available. */
540 if (info->td_ta_event_addr_p == NULL
541 || info->td_ta_set_event_p == NULL
542 || info->td_ta_event_getmsg_p == NULL
543 || info->td_thr_event_enable_p == NULL)
546 /* Set the process wide mask saying which events we're interested in. */
547 td_event_emptyset (&events);
548 td_event_addset (&events, TD_CREATE);
550 #ifdef HAVE_GNU_LIBC_VERSION_H
551 /* The event reporting facility is broken for TD_DEATH events in
552 glibc 2.1.3, so don't enable it if we have glibc but a lower
554 libc_version = gnu_get_libc_version ();
555 if (sscanf (libc_version, "%d.%d", &libc_major, &libc_minor) == 2
556 && (libc_major > 2 || (libc_major == 2 && libc_minor > 1)))
558 td_event_addset (&events, TD_DEATH);
560 err = info->td_ta_set_event_p (info->thread_agent, &events);
563 warning (_("Unable to set global thread event mask: %s"),
564 thread_db_err_str (err));
568 /* Delete previous thread event breakpoints, if any. */
569 remove_thread_event_breakpoints ();
570 info->td_create_bp_addr = 0;
571 info->td_death_bp_addr = 0;
573 /* Set up the thread creation event. */
574 err = enable_thread_event (TD_CREATE, &info->td_create_bp_addr);
577 warning (_("Unable to get location for thread creation breakpoint: %s"),
578 thread_db_err_str (err));
582 /* Set up the thread death event. */
583 err = enable_thread_event (TD_DEATH, &info->td_death_bp_addr);
586 warning (_("Unable to get location for thread death breakpoint: %s"),
587 thread_db_err_str (err));
592 /* Same as thread_db_find_new_threads_1, but silently ignore errors. */
595 thread_db_find_new_threads_silently (ptid_t ptid)
597 volatile struct gdb_exception except;
599 TRY_CATCH (except, RETURN_MASK_ERROR)
601 thread_db_find_new_threads_2 (ptid, 1);
604 if (except.reason < 0 && info_verbose)
606 exception_fprintf (gdb_stderr, except,
607 "Warning: thread_db_find_new_threads_silently: ");
611 /* Lookup a library in which given symbol resides.
612 Note: this is looking in GDB process, not in the inferior.
613 Returns library name, or NULL. */
616 dladdr_to_soname (const void *addr)
620 if (dladdr (addr, &info) != 0)
621 return info.dli_fname;
625 /* Attempt to initialize dlopen()ed libthread_db, described by HANDLE.
627 Failure could happen if libthread_db does not have symbols we expect,
628 or when it refuses to work with the current inferior (e.g. due to
629 version mismatch between libthread_db and libpthread). */
632 try_thread_db_load_1 (struct thread_db_info *info)
636 /* Initialize pointers to the dynamic library functions we will use.
637 Essential functions first. */
639 info->td_init_p = verbose_dlsym (info->handle, "td_init");
640 if (info->td_init_p == NULL)
643 err = info->td_init_p ();
646 warning (_("Cannot initialize libthread_db: %s"), thread_db_err_str (err));
650 info->td_ta_new_p = verbose_dlsym (info->handle, "td_ta_new");
651 if (info->td_ta_new_p == NULL)
654 /* Initialize the structure that identifies the child process. */
655 info->proc_handle.ptid = inferior_ptid;
657 /* Now attempt to open a connection to the thread library. */
658 err = info->td_ta_new_p (&info->proc_handle, &info->thread_agent);
662 printf_unfiltered (_("td_ta_new failed: %s\n"),
663 thread_db_err_str (err));
668 #ifdef THREAD_DB_HAS_TD_VERSION
671 /* The errors above are not unexpected and silently ignored:
672 they just mean we haven't found correct version of
676 warning (_("td_ta_new failed: %s"), thread_db_err_str (err));
681 info->td_ta_map_id2thr_p = verbose_dlsym (info->handle, "td_ta_map_id2thr");
682 if (info->td_ta_map_id2thr_p == NULL)
685 info->td_ta_map_lwp2thr_p = verbose_dlsym (info->handle, "td_ta_map_lwp2thr");
686 if (info->td_ta_map_lwp2thr_p == NULL)
689 info->td_ta_thr_iter_p = verbose_dlsym (info->handle, "td_ta_thr_iter");
690 if (info->td_ta_thr_iter_p == NULL)
693 info->td_thr_validate_p = verbose_dlsym (info->handle, "td_thr_validate");
694 if (info->td_thr_validate_p == NULL)
697 info->td_thr_get_info_p = verbose_dlsym (info->handle, "td_thr_get_info");
698 if (info->td_thr_get_info_p == NULL)
701 /* These are not essential. */
702 info->td_ta_event_addr_p = dlsym (info->handle, "td_ta_event_addr");
703 info->td_ta_set_event_p = dlsym (info->handle, "td_ta_set_event");
704 info->td_ta_clear_event_p = dlsym (info->handle, "td_ta_clear_event");
705 info->td_ta_event_getmsg_p = dlsym (info->handle, "td_ta_event_getmsg");
706 info->td_thr_event_enable_p = dlsym (info->handle, "td_thr_event_enable");
707 info->td_thr_tls_get_addr_p = dlsym (info->handle, "td_thr_tls_get_addr");
709 printf_unfiltered (_("[Thread debugging using libthread_db enabled]\n"));
711 if (info_verbose || *libthread_db_search_path)
715 library = dladdr_to_soname (*info->td_ta_new_p);
717 library = LIBTHREAD_DB_SO;
719 printf_unfiltered (_("Using host libthread_db library \"%s\".\n"),
723 /* The thread library was detected. Activate the thread_db target
724 if this is the first process using it. */
725 if (thread_db_list->next == NULL)
726 push_target (&thread_db_ops);
728 enable_thread_event_reporting ();
730 /* There appears to be a bug in glibc-2.3.6: calls to td_thr_get_info fail
731 with TD_ERR for statically linked executables if td_thr_get_info is
732 called before glibc has initialized itself. Silently ignore such
733 errors, and let gdb enumerate threads again later. */
734 thread_db_find_new_threads_silently (inferior_ptid);
739 /* Attempt to use LIBRARY as libthread_db. LIBRARY could be absolute,
740 relative, or just LIBTHREAD_DB. */
743 try_thread_db_load (const char *library)
746 struct thread_db_info *info;
749 printf_unfiltered (_("Trying host libthread_db library: %s.\n"),
751 handle = dlopen (library, RTLD_NOW);
755 printf_unfiltered (_("dlopen failed: %s.\n"), dlerror ());
759 if (info_verbose && strchr (library, '/') == NULL)
763 td_init = dlsym (handle, "td_init");
766 const char *const libpath = dladdr_to_soname (td_init);
769 printf_unfiltered (_("Host %s resolved to: %s.\n"),
774 info = add_thread_db_info (handle);
776 if (try_thread_db_load_1 (info))
779 /* This library "refused" to work on current inferior. */
780 delete_thread_db_info (GET_PID (inferior_ptid));
785 /* Search libthread_db_search_path for libthread_db which "agrees"
786 to work on current inferior. */
789 thread_db_load_search (void)
792 const char *search_path = libthread_db_search_path;
797 const char *end = strchr (search_path, ':');
801 size_t len = end - search_path;
803 if (len + 1 + strlen (LIBTHREAD_DB_SO) + 1 > sizeof (path))
805 char *cp = xmalloc (len + 1);
807 memcpy (cp, search_path, len);
809 warning (_("libthread_db_search_path component too long,"
810 " ignored: %s."), cp);
812 search_path += len + 1;
815 memcpy (path, search_path, len);
817 search_path += len + 1;
821 size_t len = strlen (search_path);
823 if (len + 1 + strlen (LIBTHREAD_DB_SO) + 1 > sizeof (path))
825 warning (_("libthread_db_search_path component too long,"
826 " ignored: %s."), search_path);
829 memcpy (path, search_path, len + 1);
833 strcat (path, LIBTHREAD_DB_SO);
834 if (try_thread_db_load (path))
841 rc = try_thread_db_load (LIBTHREAD_DB_SO);
845 /* Attempt to load and initialize libthread_db.
850 thread_db_load (void)
853 struct thread_db_info *info;
855 info = get_thread_db_info (GET_PID (inferior_ptid));
860 /* Don't attempt to use thread_db on targets which can not run
861 (executables not running yet, core files) for now. */
862 if (!target_has_execution)
865 /* Don't attempt to use thread_db for remote targets. */
866 if (!target_can_run (¤t_target))
869 if (thread_db_load_search ())
872 /* None of the libthread_db's on our search path, not the system default
873 ones worked. If the executable is dynamically linked against
874 libpthread, try loading libthread_db from the same directory. */
877 if (libpthread_name_p (obj->name))
879 char path[PATH_MAX], *cp;
881 gdb_assert (strlen (obj->name) < sizeof (path));
882 strcpy (path, obj->name);
883 cp = strrchr (path, '/');
887 warning (_("Expected absolute pathname for libpthread in the"
888 " inferior, but got %s."), path);
890 else if (cp + 1 + strlen (LIBTHREAD_DB_SO) + 1 > path + sizeof (path))
892 warning (_("Unexpected: path to libpthread in the inferior is"
893 " too long: %s"), path);
897 strcpy (cp + 1, LIBTHREAD_DB_SO);
898 if (try_thread_db_load (path))
901 warning (_("Unable to find libthread_db matching inferior's thread"
902 " library, thread debugging will not be available."));
905 /* Either this executable isn't using libpthread at all, or it is
906 statically linked. Since we can't easily distinguish these two cases,
907 no warning is issued. */
912 disable_thread_event_reporting (struct thread_db_info *info)
914 if (info->td_ta_clear_event_p != NULL)
916 td_thr_events_t events;
918 /* Set the process wide mask saying we aren't interested in any
920 td_event_fillset (&events);
921 info->td_ta_clear_event_p (info->thread_agent, &events);
924 info->td_create_bp_addr = 0;
925 info->td_death_bp_addr = 0;
929 check_thread_signals (void)
936 lin_thread_get_thread_signals (&mask);
937 sigemptyset (&thread_stop_set);
938 sigemptyset (&thread_print_set);
940 for (i = 1; i < NSIG; i++)
942 if (sigismember (&mask, i))
944 if (signal_stop_update (target_signal_from_host (i), 0))
945 sigaddset (&thread_stop_set, i);
946 if (signal_print_update (target_signal_from_host (i), 0))
947 sigaddset (&thread_print_set, i);
954 /* Check whether thread_db is usable. This function is called when
955 an inferior is created (or otherwise acquired, e.g. attached to)
956 and when new shared libraries are loaded into a running process. */
959 check_for_thread_db (void)
961 /* Do nothing if we couldn't load libthread_db.so.1. */
962 if (!thread_db_load ())
967 thread_db_new_objfile (struct objfile *objfile)
969 /* This observer must always be called with inferior_ptid set
973 check_for_thread_db ();
976 /* Attach to a new thread. This function is called when we receive a
977 TD_CREATE event or when we iterate over all threads and find one
978 that wasn't already in our list. Returns true on success. */
981 attach_thread (ptid_t ptid, const td_thrhandle_t *th_p,
982 const td_thrinfo_t *ti_p)
984 struct private_thread_info *private;
985 struct thread_info *tp = NULL;
987 struct thread_db_info *info;
989 /* If we're being called after a TD_CREATE event, we may already
990 know about this thread. There are two ways this can happen. We
991 may have iterated over all threads between the thread creation
992 and the TD_CREATE event, for instance when the user has issued
993 the `info threads' command before the SIGTRAP for hitting the
994 thread creation breakpoint was reported. Alternatively, the
995 thread may have exited and a new one been created with the same
996 thread ID. In the first case we don't need to do anything; in
997 the second case we should discard information about the dead
998 thread and attach to the new one. */
999 if (in_thread_list (ptid))
1001 tp = find_thread_ptid (ptid);
1002 gdb_assert (tp != NULL);
1004 /* If tp->private is NULL, then GDB is already attached to this
1005 thread, but we do not know anything about it. We can learn
1006 about it here. This can only happen if we have some other
1007 way besides libthread_db to notice new threads (i.e.
1008 PTRACE_EVENT_CLONE); assume the same mechanism notices thread
1009 exit, so this can not be a stale thread recreated with the
1011 if (tp->private != NULL)
1013 if (!tp->private->dying)
1016 delete_thread (ptid);
1021 check_thread_signals ();
1023 if (ti_p->ti_state == TD_THR_UNKNOWN || ti_p->ti_state == TD_THR_ZOMBIE)
1024 return 0; /* A zombie thread -- do not attach. */
1026 /* Under GNU/Linux, we have to attach to each and every thread. */
1028 && lin_lwp_attach_lwp (BUILD_LWP (ti_p->ti_lid, GET_PID (ptid))) < 0)
1031 /* Construct the thread's private data. */
1032 private = xmalloc (sizeof (struct private_thread_info));
1033 memset (private, 0, sizeof (struct private_thread_info));
1035 /* A thread ID of zero may mean the thread library has not initialized
1036 yet. But we shouldn't even get here if that's the case. FIXME:
1037 if we change GDB to always have at least one thread in the thread
1038 list this will have to go somewhere else; maybe private == NULL
1039 until the thread_db target claims it. */
1040 gdb_assert (ti_p->ti_tid != 0);
1041 private->th = *th_p;
1042 private->tid = ti_p->ti_tid;
1044 /* Add the thread to GDB's thread list. */
1046 tp = add_thread_with_info (ptid, private);
1048 tp->private = private;
1050 info = get_thread_db_info (GET_PID (ptid));
1052 /* Enable thread event reporting for this thread. */
1053 err = info->td_thr_event_enable_p (th_p, 1);
1055 error (_("Cannot enable thread event reporting for %s: %s"),
1056 target_pid_to_str (ptid), thread_db_err_str (err));
1061 detach_thread (ptid_t ptid)
1063 struct thread_info *thread_info;
1065 /* Don't delete the thread now, because it still reports as active
1066 until it has executed a few instructions after the event
1067 breakpoint - if we deleted it now, "info threads" would cause us
1068 to re-attach to it. Just mark it as having had a TD_DEATH
1069 event. This means that we won't delete it from our thread list
1070 until we notice that it's dead (via prune_threads), or until
1071 something re-uses its thread ID. We'll report the thread exit
1072 when the underlying LWP dies. */
1073 thread_info = find_thread_ptid (ptid);
1074 gdb_assert (thread_info != NULL && thread_info->private != NULL);
1075 thread_info->private->dying = 1;
1079 thread_db_detach (struct target_ops *ops, char *args, int from_tty)
1081 struct target_ops *target_beneath = find_target_beneath (ops);
1082 struct thread_db_info *info;
1084 info = get_thread_db_info (GET_PID (inferior_ptid));
1088 disable_thread_event_reporting (info);
1090 /* Delete the old thread event breakpoints. Note that unlike
1091 when mourning, we can remove them here because there's still
1092 a live inferior to poke at. In any case, GDB will not try to
1093 insert anything in the inferior when removing a
1095 remove_thread_event_breakpoints ();
1097 delete_thread_db_info (GET_PID (inferior_ptid));
1100 target_beneath->to_detach (target_beneath, args, from_tty);
1102 /* NOTE: From this point on, inferior_ptid is null_ptid. */
1104 /* If there are no more processes using libpthread, detach the
1105 thread_db target ops. */
1106 if (!thread_db_list)
1107 unpush_target (&thread_db_ops);
1110 /* Check if PID is currently stopped at the location of a thread event
1111 breakpoint location. If it is, read the event message and act upon
1115 check_event (ptid_t ptid)
1117 struct regcache *regcache = get_thread_regcache (ptid);
1118 struct gdbarch *gdbarch = get_regcache_arch (regcache);
1124 struct thread_db_info *info;
1126 info = get_thread_db_info (GET_PID (ptid));
1128 /* Bail out early if we're not at a thread event breakpoint. */
1129 stop_pc = regcache_read_pc (regcache)
1130 - gdbarch_decr_pc_after_break (gdbarch);
1131 if (stop_pc != info->td_create_bp_addr
1132 && stop_pc != info->td_death_bp_addr)
1135 /* Access an lwp we know is stopped. */
1136 info->proc_handle.ptid = ptid;
1138 /* If we have only looked at the first thread before libpthread was
1139 initialized, we may not know its thread ID yet. Make sure we do
1140 before we add another thread to the list. */
1141 if (!have_threads (ptid))
1142 thread_db_find_new_threads_1 (ptid);
1144 /* If we are at a create breakpoint, we do not know what new lwp
1145 was created and cannot specifically locate the event message for it.
1146 We have to call td_ta_event_getmsg() to get
1147 the latest message. Since we have no way of correlating whether
1148 the event message we get back corresponds to our breakpoint, we must
1149 loop and read all event messages, processing them appropriately.
1150 This guarantees we will process the correct message before continuing
1151 from the breakpoint.
1153 Currently, death events are not enabled. If they are enabled,
1154 the death event can use the td_thr_event_getmsg() interface to
1155 get the message specifically for that lwp and avoid looping
1162 err = info->td_ta_event_getmsg_p (info->thread_agent, &msg);
1165 if (err == TD_NOMSG)
1168 error (_("Cannot get thread event message: %s"),
1169 thread_db_err_str (err));
1172 err = info->td_thr_get_info_p (msg.th_p, &ti);
1174 error (_("Cannot get thread info: %s"), thread_db_err_str (err));
1176 ptid = ptid_build (GET_PID (ptid), ti.ti_lid, 0);
1181 /* Call attach_thread whether or not we already know about a
1182 thread with this thread ID. */
1183 attach_thread (ptid, msg.th_p, &ti);
1189 if (!in_thread_list (ptid))
1190 error (_("Spurious thread death event."));
1192 detach_thread (ptid);
1197 error (_("Spurious thread event."));
1204 thread_db_wait (struct target_ops *ops,
1205 ptid_t ptid, struct target_waitstatus *ourstatus,
1208 struct thread_db_info *info;
1209 struct target_ops *beneath = find_target_beneath (ops);
1211 ptid = beneath->to_wait (beneath, ptid, ourstatus, options);
1213 if (ourstatus->kind == TARGET_WAITKIND_IGNORE)
1216 if (ourstatus->kind == TARGET_WAITKIND_EXITED
1217 || ourstatus->kind == TARGET_WAITKIND_SIGNALLED)
1220 info = get_thread_db_info (GET_PID (ptid));
1222 /* If this process isn't using thread_db, we're done. */
1226 if (ourstatus->kind == TARGET_WAITKIND_EXECD)
1228 /* New image, it may or may not end up using thread_db. Assume
1229 not unless we find otherwise. */
1230 delete_thread_db_info (GET_PID (ptid));
1231 if (!thread_db_list)
1232 unpush_target (&thread_db_ops);
1234 /* Thread event breakpoints are deleted by
1235 update_breakpoints_after_exec. */
1240 /* If we do not know about the main thread yet, this would be a good time to
1242 if (ourstatus->kind == TARGET_WAITKIND_STOPPED && !have_threads (ptid))
1243 thread_db_find_new_threads_1 (ptid);
1245 if (ourstatus->kind == TARGET_WAITKIND_STOPPED
1246 && ourstatus->value.sig == TARGET_SIGNAL_TRAP)
1247 /* Check for a thread event. */
1250 if (have_threads (ptid))
1252 /* Change ptids back into the higher level PID + TID format. If
1253 the thread is dead and no longer on the thread list, we will
1254 get back a dead ptid. This can occur if the thread death
1255 event gets postponed by other simultaneous events. In such a
1256 case, we want to just ignore the event and continue on. */
1258 ptid = thread_from_lwp (ptid);
1259 if (GET_PID (ptid) == -1)
1260 ourstatus->kind = TARGET_WAITKIND_SPURIOUS;
1267 thread_db_mourn_inferior (struct target_ops *ops)
1269 struct target_ops *target_beneath = find_target_beneath (ops);
1271 delete_thread_db_info (GET_PID (inferior_ptid));
1273 target_beneath->to_mourn_inferior (target_beneath);
1275 /* Delete the old thread event breakpoints. Do this after mourning
1276 the inferior, so that we don't try to uninsert them. */
1277 remove_thread_event_breakpoints ();
1279 /* Detach thread_db target ops. */
1280 if (!thread_db_list)
1281 unpush_target (ops);
1284 struct callback_data
1286 struct thread_db_info *info;
1291 find_new_threads_callback (const td_thrhandle_t *th_p, void *data)
1296 struct thread_info *tp;
1297 struct callback_data *cb_data = data;
1298 struct thread_db_info *info = cb_data->info;
1300 err = info->td_thr_get_info_p (th_p, &ti);
1302 error (_("find_new_threads_callback: cannot get thread info: %s"),
1303 thread_db_err_str (err));
1305 if (ti.ti_state == TD_THR_UNKNOWN || ti.ti_state == TD_THR_ZOMBIE)
1306 return 0; /* A zombie -- ignore. */
1310 /* A thread ID of zero means that this is the main thread, but
1311 glibc has not yet initialized thread-local storage and the
1312 pthread library. We do not know what the thread's TID will
1313 be yet. Just enable event reporting and otherwise ignore
1316 /* In that case, we're not stopped in a fork syscall and don't
1317 need this glibc bug workaround. */
1318 info->need_stale_parent_threads_check = 0;
1320 err = info->td_thr_event_enable_p (th_p, 1);
1322 error (_("Cannot enable thread event reporting for LWP %d: %s"),
1323 (int) ti.ti_lid, thread_db_err_str (err));
1328 /* Ignore stale parent threads, caused by glibc/BZ5983. This is a
1329 bit expensive, as it needs to open /proc/pid/status, so try to
1330 avoid doing the work if we know we don't have to. */
1331 if (info->need_stale_parent_threads_check)
1333 int tgid = linux_proc_get_tgid (ti.ti_lid);
1335 if (tgid != -1 && tgid != info->pid)
1339 ptid = ptid_build (info->pid, ti.ti_lid, 0);
1340 tp = find_thread_ptid (ptid);
1341 if (tp == NULL || tp->private == NULL)
1343 if (attach_thread (ptid, th_p, &ti))
1344 cb_data->new_threads += 1;
1346 /* Problem attaching this thread; perhaps it exited before we
1348 This could mean that the thread list inside glibc itself is in
1349 inconsistent state, and libthread_db could go on looping forever
1350 (observed with glibc-2.3.6). To prevent that, terminate
1351 iteration: thread_db_find_new_threads_2 will retry. */
1358 /* Helper for thread_db_find_new_threads_2.
1359 Returns number of new threads found. */
1362 find_new_threads_once (struct thread_db_info *info, int iteration,
1365 volatile struct gdb_exception except;
1366 struct callback_data data;
1367 td_err_e err = TD_ERR;
1370 data.new_threads = 0;
1372 TRY_CATCH (except, RETURN_MASK_ERROR)
1374 /* Iterate over all user-space threads to discover new threads. */
1375 err = info->td_ta_thr_iter_p (info->thread_agent,
1376 find_new_threads_callback,
1379 TD_THR_LOWEST_PRIORITY,
1381 TD_THR_ANY_USER_FLAGS);
1386 if (except.reason < 0)
1387 exception_fprintf (gdb_stderr, except,
1388 "Warning: find_new_threads_once: ");
1390 printf_filtered (_("Found %d new threads in iteration %d.\n"),
1391 data.new_threads, iteration);
1397 return data.new_threads;
1400 /* Search for new threads, accessing memory through stopped thread
1401 PTID. If UNTIL_NO_NEW is true, repeat searching until several
1402 searches in a row do not discover any new threads. */
1405 thread_db_find_new_threads_2 (ptid_t ptid, int until_no_new)
1408 struct lwp_info *lp;
1409 struct thread_db_info *info;
1410 int pid = ptid_get_pid (ptid);
1413 /* In linux, we can only read memory through a stopped lwp. */
1415 if (lp->stopped && ptid_get_pid (lp->ptid) == pid)
1419 /* There is no stopped thread. Bail out. */
1422 info = get_thread_db_info (GET_PID (ptid));
1424 /* Access an lwp we know is stopped. */
1425 info->proc_handle.ptid = ptid;
1429 /* Require 4 successive iterations which do not find any new threads.
1430 The 4 is a heuristic: there is an inherent race here, and I have
1431 seen that 2 iterations in a row are not always sufficient to
1432 "capture" all threads. */
1433 for (i = 0, loop = 0; loop < 4; ++i, ++loop)
1434 if (find_new_threads_once (info, i, NULL) != 0)
1435 /* Found some new threads. Restart the loop from beginning. */
1440 find_new_threads_once (info, 0, &err);
1442 error (_("Cannot find new threads: %s"), thread_db_err_str (err));
1447 thread_db_find_new_threads_1 (ptid_t ptid)
1449 thread_db_find_new_threads_2 (ptid, 0);
1453 update_thread_core (struct lwp_info *info, void *closure)
1455 info->core = linux_nat_core_of_thread_1 (info->ptid);
1460 thread_db_find_new_threads (struct target_ops *ops)
1462 struct thread_db_info *info;
1464 info = get_thread_db_info (GET_PID (inferior_ptid));
1469 thread_db_find_new_threads_1 (inferior_ptid);
1471 iterate_over_lwps (minus_one_ptid /* iterate over all */,
1472 update_thread_core, NULL);
1476 thread_db_pid_to_str (struct target_ops *ops, ptid_t ptid)
1478 struct thread_info *thread_info = find_thread_ptid (ptid);
1479 struct target_ops *beneath;
1481 if (thread_info != NULL && thread_info->private != NULL)
1483 static char buf[64];
1486 tid = thread_info->private->tid;
1487 snprintf (buf, sizeof (buf), "Thread 0x%lx (LWP %ld)",
1488 tid, GET_LWP (ptid));
1493 beneath = find_target_beneath (ops);
1494 if (beneath->to_pid_to_str (beneath, ptid))
1495 return beneath->to_pid_to_str (beneath, ptid);
1497 return normal_pid_to_str (ptid);
1500 /* Return a string describing the state of the thread specified by
1504 thread_db_extra_thread_info (struct thread_info *info)
1506 if (info->private == NULL)
1509 if (info->private->dying)
1515 /* Get the address of the thread local variable in load module LM which
1516 is stored at OFFSET within the thread local storage for thread PTID. */
1519 thread_db_get_thread_local_address (struct target_ops *ops,
1524 struct thread_info *thread_info;
1525 struct target_ops *beneath;
1527 /* If we have not discovered any threads yet, check now. */
1528 if (!have_threads (ptid))
1529 thread_db_find_new_threads_1 (ptid);
1531 /* Find the matching thread. */
1532 thread_info = find_thread_ptid (ptid);
1534 if (thread_info != NULL && thread_info->private != NULL)
1538 struct thread_db_info *info;
1540 info = get_thread_db_info (GET_PID (ptid));
1542 /* glibc doesn't provide the needed interface. */
1543 if (!info->td_thr_tls_get_addr_p)
1544 throw_error (TLS_NO_LIBRARY_SUPPORT_ERROR,
1545 _("No TLS library support"));
1547 /* Caller should have verified that lm != 0. */
1548 gdb_assert (lm != 0);
1550 /* Finally, get the address of the variable. */
1551 /* Note the cast through uintptr_t: this interface only works if
1552 a target address fits in a psaddr_t, which is a host pointer.
1553 So a 32-bit debugger can not access 64-bit TLS through this. */
1554 err = info->td_thr_tls_get_addr_p (&thread_info->private->th,
1555 (psaddr_t)(uintptr_t) lm,
1558 #ifdef THREAD_DB_HAS_TD_NOTALLOC
1559 /* The memory hasn't been allocated, yet. */
1560 if (err == TD_NOTALLOC)
1561 /* Now, if libthread_db provided the initialization image's
1562 address, we *could* try to build a non-lvalue value from
1563 the initialization image. */
1564 throw_error (TLS_NOT_ALLOCATED_YET_ERROR,
1565 _("TLS not allocated yet"));
1568 /* Something else went wrong. */
1570 throw_error (TLS_GENERIC_ERROR,
1571 (("%s")), thread_db_err_str (err));
1573 /* Cast assuming host == target. Joy. */
1574 /* Do proper sign extension for the target. */
1575 gdb_assert (exec_bfd);
1576 return (bfd_get_sign_extend_vma (exec_bfd) > 0
1577 ? (CORE_ADDR) (intptr_t) address
1578 : (CORE_ADDR) (uintptr_t) address);
1581 beneath = find_target_beneath (ops);
1582 if (beneath->to_get_thread_local_address)
1583 return beneath->to_get_thread_local_address (beneath, ptid, lm, offset);
1585 throw_error (TLS_GENERIC_ERROR,
1586 _("TLS not supported on this target"));
1589 /* Callback routine used to find a thread based on the TID part of
1593 thread_db_find_thread_from_tid (struct thread_info *thread, void *data)
1595 long *tid = (long *) data;
1597 if (thread->private->tid == *tid)
1603 /* Implement the to_get_ada_task_ptid target method for this target. */
1606 thread_db_get_ada_task_ptid (long lwp, long thread)
1608 struct thread_info *thread_info;
1610 thread_db_find_new_threads_1 (inferior_ptid);
1611 thread_info = iterate_over_threads (thread_db_find_thread_from_tid, &thread);
1613 gdb_assert (thread_info != NULL);
1615 return (thread_info->ptid);
1619 thread_db_resume (struct target_ops *ops,
1620 ptid_t ptid, int step, enum target_signal signo)
1622 struct target_ops *beneath = find_target_beneath (ops);
1623 struct thread_db_info *info;
1625 if (ptid_equal (ptid, minus_one_ptid))
1626 info = get_thread_db_info (GET_PID (inferior_ptid));
1628 info = get_thread_db_info (GET_PID (ptid));
1630 /* This workaround is only needed for child fork lwps stopped in a
1631 PTRACE_O_TRACEFORK event. When the inferior is resumed, the
1632 workaround can be disabled. */
1634 info->need_stale_parent_threads_check = 0;
1636 beneath->to_resume (beneath, ptid, step, signo);
1640 init_thread_db_ops (void)
1642 thread_db_ops.to_shortname = "multi-thread";
1643 thread_db_ops.to_longname = "multi-threaded child process.";
1644 thread_db_ops.to_doc = "Threads and pthreads support.";
1645 thread_db_ops.to_detach = thread_db_detach;
1646 thread_db_ops.to_wait = thread_db_wait;
1647 thread_db_ops.to_resume = thread_db_resume;
1648 thread_db_ops.to_mourn_inferior = thread_db_mourn_inferior;
1649 thread_db_ops.to_find_new_threads = thread_db_find_new_threads;
1650 thread_db_ops.to_pid_to_str = thread_db_pid_to_str;
1651 thread_db_ops.to_stratum = thread_stratum;
1652 thread_db_ops.to_has_thread_control = tc_schedlock;
1653 thread_db_ops.to_get_thread_local_address
1654 = thread_db_get_thread_local_address;
1655 thread_db_ops.to_extra_thread_info = thread_db_extra_thread_info;
1656 thread_db_ops.to_get_ada_task_ptid = thread_db_get_ada_task_ptid;
1657 thread_db_ops.to_magic = OPS_MAGIC;
1660 /* Provide a prototype to silence -Wmissing-prototypes. */
1661 extern initialize_file_ftype _initialize_thread_db;
1664 _initialize_thread_db (void)
1666 init_thread_db_ops ();
1667 add_target (&thread_db_ops);
1669 /* Defer loading of libthread_db.so until inferior is running.
1670 This allows gdb to load correct libthread_db for a given
1671 executable -- there could be mutiple versions of glibc,
1672 compiled with LinuxThreads or NPTL, and until there is
1673 a running inferior, we can't tell which libthread_db is
1674 the correct one to load. */
1676 libthread_db_search_path = xstrdup (LIBTHREAD_DB_SEARCH_PATH);
1678 add_setshow_optional_filename_cmd ("libthread-db-search-path",
1680 &libthread_db_search_path, _("\
1681 Set search path for libthread_db."), _("\
1682 Show the current search path or libthread_db."), _("\
1683 This path is used to search for libthread_db to be loaded into \
1687 &setlist, &showlist);
1688 /* Add ourselves to objfile event chain. */
1689 observer_attach_new_objfile (thread_db_new_objfile);