1 /* libthread_db assisted debugging support, generic parts.
3 Copyright (C) 1999, 2000, 2001, 2003, 2004, 2005, 2006, 2007, 2008, 2009
4 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_event_getmsg_p) (const td_thragent_t *ta,
145 td_event_msg_t *msg);
147 td_err_e (*td_thr_validate_p) (const td_thrhandle_t *th);
148 td_err_e (*td_thr_get_info_p) (const td_thrhandle_t *th,
149 td_thrinfo_t *infop);
150 td_err_e (*td_thr_event_enable_p) (const td_thrhandle_t *th,
153 td_err_e (*td_thr_tls_get_addr_p) (const td_thrhandle_t *th,
155 size_t offset, void **address);
158 /* List of known processes using thread_db, and the required
160 struct thread_db_info *thread_db_list;
162 static void thread_db_find_new_threads_1 (ptid_t ptid);
164 /* Add the current inferior to the list of processes using libpthread.
165 Return a pointer to the newly allocated object that was added to
166 THREAD_DB_LIST. HANDLE is the handle returned by dlopen'ing
169 static struct thread_db_info *
170 add_thread_db_info (void *handle)
173 struct thread_db_info *info;
175 info = xcalloc (1, sizeof (*info));
176 info->pid = ptid_get_pid (inferior_ptid);
177 info->handle = handle;
178 info->need_stale_parent_threads_check = 1;
180 info->next = thread_db_list;
181 thread_db_list = info;
186 /* Return the thread_db_info object representing the bookkeeping
187 related to process PID, if any; NULL otherwise. */
189 static struct thread_db_info *
190 get_thread_db_info (int pid)
192 struct thread_db_info *info;
194 for (info = thread_db_list; info; info = info->next)
195 if (pid == info->pid)
201 /* When PID has exited or has been detached, we no longer want to keep
202 track of it as using libpthread. Call this function to discard
203 thread_db related info related to PID. Note that this closes
204 LIBTHREAD_DB_SO's dlopen'ed handle. */
207 delete_thread_db_info (int pid)
209 struct thread_db_info *info, *info_prev;
213 for (info = thread_db_list; info; info_prev = info, info = info->next)
214 if (pid == info->pid)
220 if (info->handle != NULL)
221 dlclose (info->handle);
224 info_prev->next = info->next;
226 thread_db_list = info->next;
231 /* Prototypes for local functions. */
232 static void attach_thread (ptid_t ptid, const td_thrhandle_t *th_p,
233 const td_thrinfo_t *ti_p);
234 static void detach_thread (ptid_t ptid);
237 /* Use "struct private_thread_info" to cache thread state. This is
238 a substantial optimization. */
240 struct private_thread_info
242 /* Flag set when we see a TD_DEATH event for this thread. */
243 unsigned int dying:1;
245 /* Cached thread state. */
252 thread_db_err_str (td_err_e err)
259 return "generic 'call succeeded'";
261 return "generic error";
263 return "no thread to satisfy query";
265 return "no sync handle to satisfy query";
267 return "no LWP to satisfy query";
269 return "invalid process handle";
271 return "invalid thread handle";
273 return "invalid synchronization handle";
275 return "invalid thread agent";
277 return "invalid key";
279 return "no event message for getmsg";
281 return "FPU register set not available";
283 return "application not linked with libthread";
285 return "requested event is not supported";
287 return "capability not available";
289 return "debugger service failed";
291 return "operation not applicable to";
293 return "no thread-specific data for this thread";
295 return "malloc failed";
297 return "only part of register set was written/read";
299 return "X register set not available for this thread";
300 #ifdef THREAD_DB_HAS_TD_NOTALLOC
302 return "thread has not yet allocated TLS for given module";
304 #ifdef THREAD_DB_HAS_TD_VERSION
306 return "versions of libpthread and libthread_db do not match";
308 #ifdef THREAD_DB_HAS_TD_NOTLS
310 return "there is no TLS segment in the given module";
313 snprintf (buf, sizeof (buf), "unknown thread_db error '%d'", err);
318 /* Return 1 if any threads have been registered. There may be none if
319 the threading library is not fully initialized yet. */
322 have_threads_callback (struct thread_info *thread, void *args)
324 int pid = * (int *) args;
325 if (ptid_get_pid (thread->ptid) != pid)
328 return thread->private != NULL;
332 have_threads (ptid_t ptid)
334 int pid = ptid_get_pid (ptid);
336 return iterate_over_threads (have_threads_callback, &pid) != NULL;
339 struct thread_get_info_inout
341 struct thread_info *thread_info;
342 struct thread_db_info *thread_db_info;
345 /* A callback function for td_ta_thr_iter, which we use to map all
348 THP is a handle to the current thread; if INFOP is not NULL, the
349 struct thread_info associated with this thread is returned in
352 If the thread is a zombie, TD_THR_ZOMBIE is returned. Otherwise,
353 zero is returned to indicate success. */
356 thread_get_info_callback (const td_thrhandle_t *thp, void *argp)
361 struct thread_get_info_inout *inout;
362 struct thread_db_info *info;
365 info = inout->thread_db_info;
367 err = info->td_thr_get_info_p (thp, &ti);
369 error (_("thread_get_info_callback: cannot get thread info: %s"),
370 thread_db_err_str (err));
372 /* Fill the cache. */
373 thread_ptid = ptid_build (info->pid, ti.ti_lid, 0);
374 inout->thread_info = find_thread_pid (thread_ptid);
376 /* In the case of a zombie thread, don't continue. We don't want to
377 attach to it thinking it is a new thread. */
378 if (ti.ti_state == TD_THR_UNKNOWN || ti.ti_state == TD_THR_ZOMBIE)
379 return TD_THR_ZOMBIE;
381 if (inout->thread_info == NULL)
383 /* New thread. Attach to it now (why wait?). */
384 if (!have_threads (thread_ptid))
385 thread_db_find_new_threads_1 (thread_ptid);
387 attach_thread (thread_ptid, thp, &ti);
388 inout->thread_info = find_thread_pid (thread_ptid);
389 gdb_assert (inout->thread_info != NULL);
395 /* Convert between user-level thread ids and LWP ids. */
398 thread_from_lwp (ptid_t ptid)
403 struct thread_db_info *info;
404 struct thread_get_info_inout io = {0};
406 /* This ptid comes from linux-nat.c, which should always fill in the
408 gdb_assert (GET_LWP (ptid) != 0);
410 info = get_thread_db_info (GET_PID (ptid));
412 /* Access an lwp we know is stopped. */
413 info->proc_handle.ptid = ptid;
414 err = info->td_ta_map_lwp2thr_p (info->thread_agent, GET_LWP (ptid), &th);
416 error (_("Cannot find user-level thread for LWP %ld: %s"),
417 GET_LWP (ptid), thread_db_err_str (err));
419 /* Fetch the thread info. If we get back TD_THR_ZOMBIE, then the
420 event thread has already died. If another gdb interface has called
421 thread_alive() previously, the thread won't be found on the thread list
422 anymore. In that case, we don't want to process this ptid anymore
423 to avoid the possibility of later treating it as a newly
424 discovered thread id that we should add to the list. Thus,
425 we return a -1 ptid which is also how the thread list marks a
427 io.thread_db_info = info;
428 io.thread_info = NULL;
429 if (thread_get_info_callback (&th, &io) == TD_THR_ZOMBIE
430 && io.thread_info == NULL)
431 return minus_one_ptid;
433 gdb_assert (ptid_get_tid (ptid) == 0);
438 /* Attach to lwp PTID, doing whatever else is required to have this
439 LWP under the debugger's control --- e.g., enabling event
440 reporting. Returns true on success. */
442 thread_db_attach_lwp (ptid_t ptid)
447 struct thread_db_info *info;
449 info = get_thread_db_info (GET_PID (ptid));
454 /* This ptid comes from linux-nat.c, which should always fill in the
456 gdb_assert (GET_LWP (ptid) != 0);
458 /* Access an lwp we know is stopped. */
459 info->proc_handle.ptid = ptid;
461 /* If we have only looked at the first thread before libpthread was
462 initialized, we may not know its thread ID yet. Make sure we do
463 before we add another thread to the list. */
464 if (!have_threads (ptid))
465 thread_db_find_new_threads_1 (ptid);
467 err = info->td_ta_map_lwp2thr_p (info->thread_agent, GET_LWP (ptid), &th);
469 /* Cannot find user-level thread. */
472 err = info->td_thr_get_info_p (&th, &ti);
475 warning (_("Cannot get thread info: %s"), thread_db_err_str (err));
479 attach_thread (ptid, &th, &ti);
484 verbose_dlsym (void *handle, const char *name)
486 void *sym = dlsym (handle, name);
488 warning (_("Symbol \"%s\" not found in libthread_db: %s"), name, dlerror ());
493 enable_thread_event (int event, CORE_ADDR *bp)
497 struct thread_db_info *info;
499 info = get_thread_db_info (GET_PID (inferior_ptid));
501 /* Access an lwp we know is stopped. */
502 info->proc_handle.ptid = inferior_ptid;
504 /* Get the breakpoint address for thread EVENT. */
505 err = info->td_ta_event_addr_p (info->thread_agent, event, ¬ify);
509 /* Set up the breakpoint. */
510 gdb_assert (exec_bfd);
511 (*bp) = (gdbarch_convert_from_func_ptr_addr
513 /* Do proper sign extension for the target. */
514 (bfd_get_sign_extend_vma (exec_bfd) > 0
515 ? (CORE_ADDR) (intptr_t) notify.u.bptaddr
516 : (CORE_ADDR) (uintptr_t) notify.u.bptaddr),
518 create_thread_event_breakpoint ((*bp));
524 enable_thread_event_reporting (void)
526 td_thr_events_t events;
529 #ifdef HAVE_GNU_LIBC_VERSION_H
530 const char *libc_version;
531 int libc_major, libc_minor;
533 struct thread_db_info *info;
535 info = get_thread_db_info (GET_PID (inferior_ptid));
537 /* We cannot use the thread event reporting facility if these
538 functions aren't available. */
539 if (info->td_ta_event_addr_p == NULL
540 || info->td_ta_set_event_p == NULL
541 || info->td_ta_event_getmsg_p == NULL
542 || info->td_thr_event_enable_p == NULL)
545 /* Set the process wide mask saying which events we're interested in. */
546 td_event_emptyset (&events);
547 td_event_addset (&events, TD_CREATE);
549 #ifdef HAVE_GNU_LIBC_VERSION_H
550 /* The event reporting facility is broken for TD_DEATH events in
551 glibc 2.1.3, so don't enable it if we have glibc but a lower
553 libc_version = gnu_get_libc_version ();
554 if (sscanf (libc_version, "%d.%d", &libc_major, &libc_minor) == 2
555 && (libc_major > 2 || (libc_major == 2 && libc_minor > 1)))
557 td_event_addset (&events, TD_DEATH);
559 err = info->td_ta_set_event_p (info->thread_agent, &events);
562 warning (_("Unable to set global thread event mask: %s"),
563 thread_db_err_str (err));
567 /* Delete previous thread event breakpoints, if any. */
568 remove_thread_event_breakpoints ();
569 info->td_create_bp_addr = 0;
570 info->td_death_bp_addr = 0;
572 /* Set up the thread creation event. */
573 err = enable_thread_event (TD_CREATE, &info->td_create_bp_addr);
576 warning (_("Unable to get location for thread creation breakpoint: %s"),
577 thread_db_err_str (err));
581 /* Set up the thread death event. */
582 err = enable_thread_event (TD_DEATH, &info->td_death_bp_addr);
585 warning (_("Unable to get location for thread death breakpoint: %s"),
586 thread_db_err_str (err));
591 /* Lookup a library in which given symbol resides.
592 Note: this is looking in GDB process, not in the inferior.
593 Returns library name, or NULL. */
596 dladdr_to_soname (const void *addr)
600 if (dladdr (addr, &info) != 0)
601 return info.dli_fname;
605 /* Attempt to initialize dlopen()ed libthread_db, described by HANDLE.
607 Failure could happen if libthread_db does not have symbols we expect,
608 or when it refuses to work with the current inferior (e.g. due to
609 version mismatch between libthread_db and libpthread). */
612 try_thread_db_load_1 (struct thread_db_info *info)
616 /* Initialize pointers to the dynamic library functions we will use.
617 Essential functions first. */
619 info->td_init_p = verbose_dlsym (info->handle, "td_init");
620 if (info->td_init_p == NULL)
623 err = info->td_init_p ();
626 warning (_("Cannot initialize libthread_db: %s"), thread_db_err_str (err));
630 info->td_ta_new_p = verbose_dlsym (info->handle, "td_ta_new");
631 if (info->td_ta_new_p == NULL)
634 /* Initialize the structure that identifies the child process. */
635 info->proc_handle.ptid = inferior_ptid;
637 /* Now attempt to open a connection to the thread library. */
638 err = info->td_ta_new_p (&info->proc_handle, &info->thread_agent);
642 printf_unfiltered (_("td_ta_new failed: %s\n"),
643 thread_db_err_str (err));
648 #ifdef THREAD_DB_HAS_TD_VERSION
651 /* The errors above are not unexpected and silently ignored:
652 they just mean we haven't found correct version of
656 warning (_("td_ta_new failed: %s"), thread_db_err_str (err));
661 info->td_ta_map_id2thr_p = verbose_dlsym (info->handle, "td_ta_map_id2thr");
662 if (info->td_ta_map_id2thr_p == NULL)
665 info->td_ta_map_lwp2thr_p = verbose_dlsym (info->handle, "td_ta_map_lwp2thr");
666 if (info->td_ta_map_lwp2thr_p == NULL)
669 info->td_ta_thr_iter_p = verbose_dlsym (info->handle, "td_ta_thr_iter");
670 if (info->td_ta_thr_iter_p == NULL)
673 info->td_thr_validate_p = verbose_dlsym (info->handle, "td_thr_validate");
674 if (info->td_thr_validate_p == NULL)
677 info->td_thr_get_info_p = verbose_dlsym (info->handle, "td_thr_get_info");
678 if (info->td_thr_get_info_p == NULL)
681 /* These are not essential. */
682 info->td_ta_event_addr_p = dlsym (info->handle, "td_ta_event_addr");
683 info->td_ta_set_event_p = dlsym (info->handle, "td_ta_set_event");
684 info->td_ta_event_getmsg_p = dlsym (info->handle, "td_ta_event_getmsg");
685 info->td_thr_event_enable_p = dlsym (info->handle, "td_thr_event_enable");
686 info->td_thr_tls_get_addr_p = dlsym (info->handle, "td_thr_tls_get_addr");
688 printf_unfiltered (_("[Thread debugging using libthread_db enabled]\n"));
690 if (info_verbose || *libthread_db_search_path)
694 library = dladdr_to_soname (*info->td_ta_new_p);
696 library = LIBTHREAD_DB_SO;
698 printf_unfiltered (_("Using host libthread_db library \"%s\".\n"),
702 /* The thread library was detected. Activate the thread_db target
703 if this is the first process using it. */
704 if (thread_db_list->next == NULL)
705 push_target (&thread_db_ops);
707 enable_thread_event_reporting ();
708 thread_db_find_new_threads_1 (inferior_ptid);
712 /* Attempt to use LIBRARY as libthread_db. LIBRARY could be absolute,
713 relative, or just LIBTHREAD_DB. */
716 try_thread_db_load (const char *library)
719 struct thread_db_info *info;
722 printf_unfiltered (_("Trying host libthread_db library: %s.\n"),
724 handle = dlopen (library, RTLD_NOW);
728 printf_unfiltered (_("dlopen failed: %s.\n"), dlerror ());
732 if (info_verbose && strchr (library, '/') == NULL)
736 td_init = dlsym (handle, "td_init");
739 const char *const libpath = dladdr_to_soname (td_init);
742 printf_unfiltered (_("Host %s resolved to: %s.\n"),
747 info = add_thread_db_info (handle);
749 if (try_thread_db_load_1 (info))
752 /* This library "refused" to work on current inferior. */
753 delete_thread_db_info (GET_PID (inferior_ptid));
758 /* Search libthread_db_search_path for libthread_db which "agrees"
759 to work on current inferior. */
762 thread_db_load_search (void)
765 const char *search_path = libthread_db_search_path;
770 const char *end = strchr (search_path, ':');
773 size_t len = end - search_path;
774 if (len + 1 + strlen (LIBTHREAD_DB_SO) + 1 > sizeof (path))
776 char *cp = xmalloc (len + 1);
777 memcpy (cp, search_path, len);
779 warning (_("libthread_db_search_path component too long,"
780 " ignored: %s."), cp);
782 search_path += len + 1;
785 memcpy (path, search_path, len);
787 search_path += len + 1;
791 size_t len = strlen (search_path);
793 if (len + 1 + strlen (LIBTHREAD_DB_SO) + 1 > sizeof (path))
795 warning (_("libthread_db_search_path component too long,"
796 " ignored: %s."), search_path);
799 memcpy (path, search_path, len + 1);
803 strcat (path, LIBTHREAD_DB_SO);
804 if (try_thread_db_load (path))
811 rc = try_thread_db_load (LIBTHREAD_DB_SO);
815 /* Attempt to load and initialize libthread_db.
820 thread_db_load (void)
823 struct thread_db_info *info;
825 info = get_thread_db_info (GET_PID (inferior_ptid));
830 /* Don't attempt to use thread_db on targets which can not run
831 (executables not running yet, core files) for now. */
832 if (!target_has_execution)
835 /* Don't attempt to use thread_db for remote targets. */
836 if (!target_can_run (¤t_target))
839 if (thread_db_load_search ())
842 /* None of the libthread_db's on our search path, not the system default
843 ones worked. If the executable is dynamically linked against
844 libpthread, try loading libthread_db from the same directory. */
847 if (libpthread_name_p (obj->name))
849 char path[PATH_MAX], *cp;
851 gdb_assert (strlen (obj->name) < sizeof (path));
852 strcpy (path, obj->name);
853 cp = strrchr (path, '/');
857 warning (_("Expected absolute pathname for libpthread in the"
858 " inferior, but got %s."), path);
860 else if (cp + 1 + strlen (LIBTHREAD_DB_SO) + 1 > path + sizeof (path))
862 warning (_("Unexpected: path to libpthread in the inferior is"
863 " too long: %s"), path);
867 strcpy (cp + 1, LIBTHREAD_DB_SO);
868 if (try_thread_db_load (path))
871 warning (_("Unable to find libthread_db matching inferior's thread"
872 " library, thread debugging will not be available."));
875 /* Either this executable isn't using libpthread at all, or it is
876 statically linked. Since we can't easily distinguish these two cases,
877 no warning is issued. */
882 disable_thread_event_reporting (void)
884 td_thr_events_t events;
885 struct thread_db_info *info;
887 info = get_thread_db_info (GET_PID (inferior_ptid));
889 /* Set the process wide mask saying we aren't interested in any
891 td_event_emptyset (&events);
892 info->td_ta_set_event_p (info->thread_agent, &events);
894 /* Delete thread event breakpoints, if any. */
895 remove_thread_event_breakpoints ();
896 info->td_create_bp_addr = 0;
897 info->td_death_bp_addr = 0;
901 check_thread_signals (void)
903 #ifdef GET_THREAD_SIGNALS
909 GET_THREAD_SIGNALS (&mask);
910 sigemptyset (&thread_stop_set);
911 sigemptyset (&thread_print_set);
913 for (i = 1; i < NSIG; i++)
915 if (sigismember (&mask, i))
917 if (signal_stop_update (target_signal_from_host (i), 0))
918 sigaddset (&thread_stop_set, i);
919 if (signal_print_update (target_signal_from_host (i), 0))
920 sigaddset (&thread_print_set, i);
928 /* Check whether thread_db is usable. This function is called when
929 an inferior is created (or otherwise acquired, e.g. attached to)
930 and when new shared libraries are loaded into a running process. */
933 check_for_thread_db (void)
936 static void *last_loaded;
938 /* Do nothing if we couldn't load libthread_db.so.1. */
939 if (!thread_db_load ())
944 thread_db_new_objfile (struct objfile *objfile)
946 /* This observer must always be called with inferior_ptid set
950 check_for_thread_db ();
953 /* Attach to a new thread. This function is called when we receive a
954 TD_CREATE event or when we iterate over all threads and find one
955 that wasn't already in our list. */
958 attach_thread (ptid_t ptid, const td_thrhandle_t *th_p,
959 const td_thrinfo_t *ti_p)
961 struct private_thread_info *private;
962 struct thread_info *tp = NULL;
964 struct thread_db_info *info;
966 /* If we're being called after a TD_CREATE event, we may already
967 know about this thread. There are two ways this can happen. We
968 may have iterated over all threads between the thread creation
969 and the TD_CREATE event, for instance when the user has issued
970 the `info threads' command before the SIGTRAP for hitting the
971 thread creation breakpoint was reported. Alternatively, the
972 thread may have exited and a new one been created with the same
973 thread ID. In the first case we don't need to do anything; in
974 the second case we should discard information about the dead
975 thread and attach to the new one. */
976 if (in_thread_list (ptid))
978 tp = find_thread_pid (ptid);
979 gdb_assert (tp != NULL);
981 /* If tp->private is NULL, then GDB is already attached to this
982 thread, but we do not know anything about it. We can learn
983 about it here. This can only happen if we have some other
984 way besides libthread_db to notice new threads (i.e.
985 PTRACE_EVENT_CLONE); assume the same mechanism notices thread
986 exit, so this can not be a stale thread recreated with the
988 if (tp->private != NULL)
990 if (!tp->private->dying)
993 delete_thread (ptid);
998 check_thread_signals ();
1000 if (ti_p->ti_state == TD_THR_UNKNOWN || ti_p->ti_state == TD_THR_ZOMBIE)
1001 return; /* A zombie thread -- do not attach. */
1003 /* Under GNU/Linux, we have to attach to each and every thread. */
1005 && lin_lwp_attach_lwp (BUILD_LWP (ti_p->ti_lid, GET_PID (ptid))) < 0)
1008 /* Construct the thread's private data. */
1009 private = xmalloc (sizeof (struct private_thread_info));
1010 memset (private, 0, sizeof (struct private_thread_info));
1012 /* A thread ID of zero may mean the thread library has not initialized
1013 yet. But we shouldn't even get here if that's the case. FIXME:
1014 if we change GDB to always have at least one thread in the thread
1015 list this will have to go somewhere else; maybe private == NULL
1016 until the thread_db target claims it. */
1017 gdb_assert (ti_p->ti_tid != 0);
1018 private->th = *th_p;
1019 private->tid = ti_p->ti_tid;
1021 /* Add the thread to GDB's thread list. */
1023 tp = add_thread_with_info (ptid, private);
1025 tp->private = private;
1027 info = get_thread_db_info (GET_PID (ptid));
1029 /* Enable thread event reporting for this thread. */
1030 err = info->td_thr_event_enable_p (th_p, 1);
1032 error (_("Cannot enable thread event reporting for %s: %s"),
1033 target_pid_to_str (ptid), thread_db_err_str (err));
1037 detach_thread (ptid_t ptid)
1039 struct thread_info *thread_info;
1041 /* Don't delete the thread now, because it still reports as active
1042 until it has executed a few instructions after the event
1043 breakpoint - if we deleted it now, "info threads" would cause us
1044 to re-attach to it. Just mark it as having had a TD_DEATH
1045 event. This means that we won't delete it from our thread list
1046 until we notice that it's dead (via prune_threads), or until
1047 something re-uses its thread ID. We'll report the thread exit
1048 when the underlying LWP dies. */
1049 thread_info = find_thread_pid (ptid);
1050 gdb_assert (thread_info != NULL && thread_info->private != NULL);
1051 thread_info->private->dying = 1;
1055 thread_db_detach (struct target_ops *ops, char *args, int from_tty)
1057 struct target_ops *target_beneath = find_target_beneath (ops);
1058 struct thread_db_info *info;
1060 info = get_thread_db_info (GET_PID (inferior_ptid));
1064 disable_thread_event_reporting ();
1066 /* Delete the old thread event breakpoints. Note that unlike
1067 when mourning, we can remove them here because there's still
1068 a live inferior to poke at. In any case, GDB will not try to
1069 insert anything in the inferior when removing a
1071 remove_thread_event_breakpoints ();
1073 delete_thread_db_info (GET_PID (inferior_ptid));
1076 target_beneath->to_detach (target_beneath, args, from_tty);
1078 /* NOTE: From this point on, inferior_ptid is null_ptid. */
1080 /* If there are no more processes using libpthread, detach the
1081 thread_db target ops. */
1082 if (!thread_db_list)
1083 unpush_target (&thread_db_ops);
1086 /* Check if PID is currently stopped at the location of a thread event
1087 breakpoint location. If it is, read the event message and act upon
1091 check_event (ptid_t ptid)
1093 struct regcache *regcache = get_thread_regcache (ptid);
1094 struct gdbarch *gdbarch = get_regcache_arch (regcache);
1100 struct thread_db_info *info;
1102 info = get_thread_db_info (GET_PID (ptid));
1104 /* Bail out early if we're not at a thread event breakpoint. */
1105 stop_pc = regcache_read_pc (regcache)
1106 - gdbarch_decr_pc_after_break (gdbarch);
1107 if (stop_pc != info->td_create_bp_addr
1108 && stop_pc != info->td_death_bp_addr)
1111 /* Access an lwp we know is stopped. */
1112 info->proc_handle.ptid = ptid;
1114 /* If we have only looked at the first thread before libpthread was
1115 initialized, we may not know its thread ID yet. Make sure we do
1116 before we add another thread to the list. */
1117 if (!have_threads (ptid))
1118 thread_db_find_new_threads_1 (ptid);
1120 /* If we are at a create breakpoint, we do not know what new lwp
1121 was created and cannot specifically locate the event message for it.
1122 We have to call td_ta_event_getmsg() to get
1123 the latest message. Since we have no way of correlating whether
1124 the event message we get back corresponds to our breakpoint, we must
1125 loop and read all event messages, processing them appropriately.
1126 This guarantees we will process the correct message before continuing
1127 from the breakpoint.
1129 Currently, death events are not enabled. If they are enabled,
1130 the death event can use the td_thr_event_getmsg() interface to
1131 get the message specifically for that lwp and avoid looping
1138 err = info->td_ta_event_getmsg_p (info->thread_agent, &msg);
1141 if (err == TD_NOMSG)
1144 error (_("Cannot get thread event message: %s"),
1145 thread_db_err_str (err));
1148 err = info->td_thr_get_info_p (msg.th_p, &ti);
1150 error (_("Cannot get thread info: %s"), thread_db_err_str (err));
1152 ptid = ptid_build (GET_PID (ptid), ti.ti_lid, 0);
1157 /* Call attach_thread whether or not we already know about a
1158 thread with this thread ID. */
1159 attach_thread (ptid, msg.th_p, &ti);
1165 if (!in_thread_list (ptid))
1166 error (_("Spurious thread death event."));
1168 detach_thread (ptid);
1173 error (_("Spurious thread event."));
1180 thread_db_wait (struct target_ops *ops,
1181 ptid_t ptid, struct target_waitstatus *ourstatus)
1183 struct thread_db_info *info;
1184 struct target_ops *beneath = find_target_beneath (ops);
1186 ptid = beneath->to_wait (beneath, ptid, ourstatus);
1188 if (ourstatus->kind == TARGET_WAITKIND_IGNORE)
1191 if (ourstatus->kind == TARGET_WAITKIND_EXITED
1192 || ourstatus->kind == TARGET_WAITKIND_SIGNALLED)
1195 info = get_thread_db_info (GET_PID (ptid));
1197 /* If this process isn't using thread_db, we're done. */
1201 if (ourstatus->kind == TARGET_WAITKIND_EXECD)
1203 /* Breakpoints have already been marked non-inserted by the
1204 layer below. We're safe in knowing that removing them will
1205 not write the shadows of the old image into the new
1207 remove_thread_event_breakpoints ();
1209 /* New image, it may or may not end up using thread_db. Assume
1210 not unless we find otherwise. */
1211 delete_thread_db_info (GET_PID (ptid));
1212 if (!thread_db_list)
1213 unpush_target (&thread_db_ops);
1218 /* If we do not know about the main thread yet, this would be a good time to
1220 if (ourstatus->kind == TARGET_WAITKIND_STOPPED && !have_threads (ptid))
1221 thread_db_find_new_threads_1 (ptid);
1223 if (ourstatus->kind == TARGET_WAITKIND_STOPPED
1224 && ourstatus->value.sig == TARGET_SIGNAL_TRAP)
1225 /* Check for a thread event. */
1228 if (have_threads (ptid))
1230 /* Change ptids back into the higher level PID + TID format. If
1231 the thread is dead and no longer on the thread list, we will
1232 get back a dead ptid. This can occur if the thread death
1233 event gets postponed by other simultaneous events. In such a
1234 case, we want to just ignore the event and continue on. */
1236 ptid = thread_from_lwp (ptid);
1237 if (GET_PID (ptid) == -1)
1238 ourstatus->kind = TARGET_WAITKIND_SPURIOUS;
1245 thread_db_mourn_inferior (struct target_ops *ops)
1247 struct target_ops *target_beneath = find_target_beneath (ops);
1249 delete_thread_db_info (GET_PID (inferior_ptid));
1251 /* Delete the old thread event breakpoints. Mark breakpoints out,
1252 so that we don't try to un-insert them. */
1253 mark_breakpoints_out ();
1254 remove_thread_event_breakpoints ();
1256 target_beneath->to_mourn_inferior (target_beneath);
1258 /* Detach thread_db target ops. */
1259 if (!thread_db_list)
1260 unpush_target (ops);
1264 find_new_threads_callback (const td_thrhandle_t *th_p, void *data)
1269 struct thread_info *tp;
1270 struct thread_db_info *info = data;
1272 err = info->td_thr_get_info_p (th_p, &ti);
1274 error (_("find_new_threads_callback: cannot get thread info: %s"),
1275 thread_db_err_str (err));
1277 if (ti.ti_state == TD_THR_UNKNOWN || ti.ti_state == TD_THR_ZOMBIE)
1278 return 0; /* A zombie -- ignore. */
1282 /* A thread ID of zero means that this is the main thread, but
1283 glibc has not yet initialized thread-local storage and the
1284 pthread library. We do not know what the thread's TID will
1285 be yet. Just enable event reporting and otherwise ignore
1288 /* In that case, we're not stopped in a fork syscall and don't
1289 need this glibc bug workaround. */
1290 info->need_stale_parent_threads_check = 0;
1292 err = info->td_thr_event_enable_p (th_p, 1);
1294 error (_("Cannot enable thread event reporting for LWP %d: %s"),
1295 (int) ti.ti_lid, thread_db_err_str (err));
1300 /* Ignore stale parent threads, caused by glibc/BZ5983. This is a
1301 bit expensive, as it needs to open /proc/pid/status, so try to
1302 avoid doing the work if we know we don't have to. */
1303 if (info->need_stale_parent_threads_check)
1305 int tgid = linux_proc_get_tgid (ti.ti_lid);
1306 if (tgid != -1 && tgid != info->pid)
1310 ptid = ptid_build (info->pid, ti.ti_lid, 0);
1311 tp = find_thread_pid (ptid);
1312 if (tp == NULL || tp->private == NULL)
1313 attach_thread (ptid, th_p, &ti);
1318 /* Search for new threads, accessing memory through stopped thread
1322 thread_db_find_new_threads_1 (ptid_t ptid)
1325 struct lwp_info *lp;
1326 struct thread_db_info *info;
1327 int pid = ptid_get_pid (ptid);
1329 /* In linux, we can only read memory through a stopped lwp. */
1331 if (lp->stopped && ptid_get_pid (lp->ptid) == pid)
1335 /* There is no stopped thread. Bail out. */
1338 info = get_thread_db_info (GET_PID (ptid));
1340 /* Access an lwp we know is stopped. */
1341 info->proc_handle.ptid = ptid;
1342 /* Iterate over all user-space threads to discover new threads. */
1343 err = info->td_ta_thr_iter_p (info->thread_agent, find_new_threads_callback,
1344 info, TD_THR_ANY_STATE, TD_THR_LOWEST_PRIORITY,
1345 TD_SIGNO_MASK, TD_THR_ANY_USER_FLAGS);
1347 error (_("Cannot find new threads: %s"), thread_db_err_str (err));
1351 thread_db_find_new_threads (struct target_ops *ops)
1353 struct thread_db_info *info;
1355 info = get_thread_db_info (GET_PID (inferior_ptid));
1360 thread_db_find_new_threads_1 (inferior_ptid);
1364 thread_db_pid_to_str (struct target_ops *ops, ptid_t ptid)
1366 struct thread_info *thread_info = find_thread_pid (ptid);
1367 struct target_ops *beneath;
1369 if (thread_info != NULL && thread_info->private != NULL)
1371 static char buf[64];
1374 tid = thread_info->private->tid;
1375 snprintf (buf, sizeof (buf), "Thread 0x%lx (LWP %ld)",
1376 tid, GET_LWP (ptid));
1381 beneath = find_target_beneath (ops);
1382 if (beneath->to_pid_to_str (beneath, ptid))
1383 return beneath->to_pid_to_str (beneath, ptid);
1385 return normal_pid_to_str (ptid);
1388 /* Return a string describing the state of the thread specified by
1392 thread_db_extra_thread_info (struct thread_info *info)
1394 if (info->private == NULL)
1397 if (info->private->dying)
1403 /* Get the address of the thread local variable in load module LM which
1404 is stored at OFFSET within the thread local storage for thread PTID. */
1407 thread_db_get_thread_local_address (struct target_ops *ops,
1412 struct thread_info *thread_info;
1413 struct target_ops *beneath;
1415 /* If we have not discovered any threads yet, check now. */
1416 if (!have_threads (ptid))
1417 thread_db_find_new_threads_1 (ptid);
1419 /* Find the matching thread. */
1420 thread_info = find_thread_pid (ptid);
1422 if (thread_info != NULL && thread_info->private != NULL)
1426 struct thread_db_info *info;
1428 info = get_thread_db_info (GET_PID (ptid));
1430 /* glibc doesn't provide the needed interface. */
1431 if (!info->td_thr_tls_get_addr_p)
1432 throw_error (TLS_NO_LIBRARY_SUPPORT_ERROR,
1433 _("No TLS library support"));
1435 /* Caller should have verified that lm != 0. */
1436 gdb_assert (lm != 0);
1438 /* Finally, get the address of the variable. */
1439 err = info->td_thr_tls_get_addr_p (&thread_info->private->th,
1440 (void *)(size_t) lm,
1443 #ifdef THREAD_DB_HAS_TD_NOTALLOC
1444 /* The memory hasn't been allocated, yet. */
1445 if (err == TD_NOTALLOC)
1446 /* Now, if libthread_db provided the initialization image's
1447 address, we *could* try to build a non-lvalue value from
1448 the initialization image. */
1449 throw_error (TLS_NOT_ALLOCATED_YET_ERROR,
1450 _("TLS not allocated yet"));
1453 /* Something else went wrong. */
1455 throw_error (TLS_GENERIC_ERROR,
1456 (("%s")), thread_db_err_str (err));
1458 /* Cast assuming host == target. Joy. */
1459 /* Do proper sign extension for the target. */
1460 gdb_assert (exec_bfd);
1461 return (bfd_get_sign_extend_vma (exec_bfd) > 0
1462 ? (CORE_ADDR) (intptr_t) address
1463 : (CORE_ADDR) (uintptr_t) address);
1466 beneath = find_target_beneath (ops);
1467 if (beneath->to_get_thread_local_address)
1468 return beneath->to_get_thread_local_address (beneath, ptid, lm, offset);
1470 throw_error (TLS_GENERIC_ERROR,
1471 _("TLS not supported on this target"));
1474 /* Callback routine used to find a thread based on the TID part of
1478 thread_db_find_thread_from_tid (struct thread_info *thread, void *data)
1480 long *tid = (long *) data;
1482 if (thread->private->tid == *tid)
1488 /* Implement the to_get_ada_task_ptid target method for this target. */
1491 thread_db_get_ada_task_ptid (long lwp, long thread)
1493 struct thread_info *thread_info;
1495 thread_db_find_new_threads_1 (inferior_ptid);
1496 thread_info = iterate_over_threads (thread_db_find_thread_from_tid, &thread);
1498 gdb_assert (thread_info != NULL);
1500 return (thread_info->ptid);
1504 thread_db_resume (struct target_ops *ops,
1505 ptid_t ptid, int step, enum target_signal signo)
1507 struct target_ops *beneath = find_target_beneath (ops);
1508 struct thread_db_info *info;
1510 if (ptid_equal (ptid, minus_one_ptid))
1511 info = get_thread_db_info (GET_PID (inferior_ptid));
1513 info = get_thread_db_info (GET_PID (ptid));
1515 /* This workaround is only needed for child fork lwps stopped in a
1516 PTRACE_O_TRACEFORK event. When the inferior is resumed, the
1517 workaround can be disabled. */
1519 info->need_stale_parent_threads_check = 0;
1521 beneath->to_resume (beneath, ptid, step, signo);
1525 init_thread_db_ops (void)
1527 thread_db_ops.to_shortname = "multi-thread";
1528 thread_db_ops.to_longname = "multi-threaded child process.";
1529 thread_db_ops.to_doc = "Threads and pthreads support.";
1530 thread_db_ops.to_detach = thread_db_detach;
1531 thread_db_ops.to_wait = thread_db_wait;
1532 thread_db_ops.to_resume = thread_db_resume;
1533 thread_db_ops.to_mourn_inferior = thread_db_mourn_inferior;
1534 thread_db_ops.to_find_new_threads = thread_db_find_new_threads;
1535 thread_db_ops.to_pid_to_str = thread_db_pid_to_str;
1536 thread_db_ops.to_stratum = thread_stratum;
1537 thread_db_ops.to_has_thread_control = tc_schedlock;
1538 thread_db_ops.to_get_thread_local_address
1539 = thread_db_get_thread_local_address;
1540 thread_db_ops.to_extra_thread_info = thread_db_extra_thread_info;
1541 thread_db_ops.to_get_ada_task_ptid = thread_db_get_ada_task_ptid;
1542 thread_db_ops.to_magic = OPS_MAGIC;
1545 /* Provide a prototype to silence -Wmissing-prototypes. */
1546 extern initialize_file_ftype _initialize_thread_db;
1549 _initialize_thread_db (void)
1551 init_thread_db_ops ();
1552 add_target (&thread_db_ops);
1554 /* Defer loading of libthread_db.so until inferior is running.
1555 This allows gdb to load correct libthread_db for a given
1556 executable -- there could be mutiple versions of glibc,
1557 compiled with LinuxThreads or NPTL, and until there is
1558 a running inferior, we can't tell which libthread_db is
1559 the correct one to load. */
1561 libthread_db_search_path = xstrdup (LIBTHREAD_DB_SEARCH_PATH);
1563 add_setshow_optional_filename_cmd ("libthread-db-search-path",
1565 &libthread_db_search_path, _("\
1566 Set search path for libthread_db."), _("\
1567 Show the current search path or libthread_db."), _("\
1568 This path is used to search for libthread_db to be loaded into \
1572 &setlist, &showlist);
1573 /* Add ourselves to objfile event chain. */
1574 observer_attach_new_objfile (thread_db_new_objfile);