1 /* libthread_db assisted debugging support, generic parts.
3 Copyright (C) 1999, 2000, 2001, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
4 2010, 2011 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;
79 set_libthread_db_search_path (char *ignored, int from_tty,
80 struct cmd_list_element *c)
82 if (*libthread_db_search_path == '\0')
84 xfree (libthread_db_search_path);
85 libthread_db_search_path = xstrdup (LIBTHREAD_DB_SEARCH_PATH);
89 /* If non-zero, print details of libthread_db processing. */
91 static int libthread_db_debug;
94 show_libthread_db_debug (struct ui_file *file, int from_tty,
95 struct cmd_list_element *c, const char *value)
97 fprintf_filtered (file, _("libthread-db debugging is %s.\n"), value);
101 /* If we're running on GNU/Linux, we must explicitly attach to any new
104 /* This module's target vector. */
105 static struct target_ops thread_db_ops;
107 /* Non-zero if we have determined the signals used by the threads
109 static int thread_signals;
110 static sigset_t thread_stop_set;
111 static sigset_t thread_print_set;
113 struct thread_db_info
115 struct thread_db_info *next;
117 /* Process id this object refers to. */
120 /* Handle from dlopen for libthread_db.so. */
123 /* Structure that identifies the child process for the
124 <proc_service.h> interface. */
125 struct ps_prochandle proc_handle;
127 /* Connection to the libthread_db library. */
128 td_thragent_t *thread_agent;
130 /* True if we need to apply the workaround for glibc/BZ5983. When
131 we catch a PTRACE_O_TRACEFORK, and go query the child's thread
132 list, nptl_db returns the parent's threads in addition to the new
133 (single) child thread. If this flag is set, we do extra work to
134 be able to ignore such stale entries. */
135 int need_stale_parent_threads_check;
137 /* Location of the thread creation event breakpoint. The code at
138 this location in the child process will be called by the pthread
139 library whenever a new thread is created. By setting a special
140 breakpoint at this location, GDB can detect when a new thread is
141 created. We obtain this location via the td_ta_event_addr
143 CORE_ADDR td_create_bp_addr;
145 /* Location of the thread death event breakpoint. */
146 CORE_ADDR td_death_bp_addr;
148 /* Pointers to the libthread_db functions. */
150 td_err_e (*td_init_p) (void);
152 td_err_e (*td_ta_new_p) (struct ps_prochandle * ps,
154 td_err_e (*td_ta_map_id2thr_p) (const td_thragent_t *ta, thread_t pt,
155 td_thrhandle_t *__th);
156 td_err_e (*td_ta_map_lwp2thr_p) (const td_thragent_t *ta,
157 lwpid_t lwpid, td_thrhandle_t *th);
158 td_err_e (*td_ta_thr_iter_p) (const td_thragent_t *ta,
159 td_thr_iter_f *callback, void *cbdata_p,
160 td_thr_state_e state, int ti_pri,
161 sigset_t *ti_sigmask_p,
162 unsigned int ti_user_flags);
163 td_err_e (*td_ta_event_addr_p) (const td_thragent_t *ta,
164 td_event_e event, td_notify_t *ptr);
165 td_err_e (*td_ta_set_event_p) (const td_thragent_t *ta,
166 td_thr_events_t *event);
167 td_err_e (*td_ta_clear_event_p) (const td_thragent_t *ta,
168 td_thr_events_t *event);
169 td_err_e (*td_ta_event_getmsg_p) (const td_thragent_t *ta,
170 td_event_msg_t *msg);
172 td_err_e (*td_thr_validate_p) (const td_thrhandle_t *th);
173 td_err_e (*td_thr_get_info_p) (const td_thrhandle_t *th,
174 td_thrinfo_t *infop);
175 td_err_e (*td_thr_event_enable_p) (const td_thrhandle_t *th,
178 td_err_e (*td_thr_tls_get_addr_p) (const td_thrhandle_t *th,
179 psaddr_t map_address,
180 size_t offset, psaddr_t *address);
183 /* List of known processes using thread_db, and the required
185 struct thread_db_info *thread_db_list;
187 static void thread_db_find_new_threads_1 (ptid_t ptid);
188 static void thread_db_find_new_threads_2 (ptid_t ptid, int until_no_new);
190 /* Add the current inferior to the list of processes using libpthread.
191 Return a pointer to the newly allocated object that was added to
192 THREAD_DB_LIST. HANDLE is the handle returned by dlopen'ing
195 static struct thread_db_info *
196 add_thread_db_info (void *handle)
198 struct thread_db_info *info;
200 info = xcalloc (1, sizeof (*info));
201 info->pid = ptid_get_pid (inferior_ptid);
202 info->handle = handle;
204 /* The workaround works by reading from /proc/pid/status, so it is
205 disabled for core files. */
206 if (target_has_execution)
207 info->need_stale_parent_threads_check = 1;
209 info->next = thread_db_list;
210 thread_db_list = info;
215 /* Return the thread_db_info object representing the bookkeeping
216 related to process PID, if any; NULL otherwise. */
218 static struct thread_db_info *
219 get_thread_db_info (int pid)
221 struct thread_db_info *info;
223 for (info = thread_db_list; info; info = info->next)
224 if (pid == info->pid)
230 /* When PID has exited or has been detached, we no longer want to keep
231 track of it as using libpthread. Call this function to discard
232 thread_db related info related to PID. Note that this closes
233 LIBTHREAD_DB_SO's dlopen'ed handle. */
236 delete_thread_db_info (int pid)
238 struct thread_db_info *info, *info_prev;
242 for (info = thread_db_list; info; info_prev = info, info = info->next)
243 if (pid == info->pid)
249 if (info->handle != NULL)
250 dlclose (info->handle);
253 info_prev->next = info->next;
255 thread_db_list = info->next;
260 /* Prototypes for local functions. */
261 static int attach_thread (ptid_t ptid, const td_thrhandle_t *th_p,
262 const td_thrinfo_t *ti_p);
263 static void detach_thread (ptid_t ptid);
266 /* Use "struct private_thread_info" to cache thread state. This is
267 a substantial optimization. */
269 struct private_thread_info
271 /* Flag set when we see a TD_DEATH event for this thread. */
272 unsigned int dying:1;
274 /* Cached thread state. */
281 thread_db_err_str (td_err_e err)
288 return "generic 'call succeeded'";
290 return "generic error";
292 return "no thread to satisfy query";
294 return "no sync handle to satisfy query";
296 return "no LWP to satisfy query";
298 return "invalid process handle";
300 return "invalid thread handle";
302 return "invalid synchronization handle";
304 return "invalid thread agent";
306 return "invalid key";
308 return "no event message for getmsg";
310 return "FPU register set not available";
312 return "application not linked with libthread";
314 return "requested event is not supported";
316 return "capability not available";
318 return "debugger service failed";
320 return "operation not applicable to";
322 return "no thread-specific data for this thread";
324 return "malloc failed";
326 return "only part of register set was written/read";
328 return "X register set not available for this thread";
329 #ifdef THREAD_DB_HAS_TD_NOTALLOC
331 return "thread has not yet allocated TLS for given module";
333 #ifdef THREAD_DB_HAS_TD_VERSION
335 return "versions of libpthread and libthread_db do not match";
337 #ifdef THREAD_DB_HAS_TD_NOTLS
339 return "there is no TLS segment in the given module";
342 snprintf (buf, sizeof (buf), "unknown thread_db error '%d'", err);
347 /* Return 1 if any threads have been registered. There may be none if
348 the threading library is not fully initialized yet. */
351 have_threads_callback (struct thread_info *thread, void *args)
353 int pid = * (int *) args;
355 if (ptid_get_pid (thread->ptid) != pid)
358 return thread->private != NULL;
362 have_threads (ptid_t ptid)
364 int pid = ptid_get_pid (ptid);
366 return iterate_over_threads (have_threads_callback, &pid) != NULL;
369 struct thread_get_info_inout
371 struct thread_info *thread_info;
372 struct thread_db_info *thread_db_info;
375 /* A callback function for td_ta_thr_iter, which we use to map all
378 THP is a handle to the current thread; if INFOP is not NULL, the
379 struct thread_info associated with this thread is returned in
382 If the thread is a zombie, TD_THR_ZOMBIE is returned. Otherwise,
383 zero is returned to indicate success. */
386 thread_get_info_callback (const td_thrhandle_t *thp, void *argp)
391 struct thread_get_info_inout *inout;
392 struct thread_db_info *info;
395 info = inout->thread_db_info;
397 err = info->td_thr_get_info_p (thp, &ti);
399 error (_("thread_get_info_callback: cannot get thread info: %s"),
400 thread_db_err_str (err));
402 /* Fill the cache. */
403 thread_ptid = ptid_build (info->pid, ti.ti_lid, 0);
404 inout->thread_info = find_thread_ptid (thread_ptid);
406 /* In the case of a zombie thread, don't continue. We don't want to
407 attach to it thinking it is a new thread. */
408 if (ti.ti_state == TD_THR_UNKNOWN || ti.ti_state == TD_THR_ZOMBIE)
409 return TD_THR_ZOMBIE;
411 if (inout->thread_info == NULL)
413 /* New thread. Attach to it now (why wait?). */
414 if (!have_threads (thread_ptid))
415 thread_db_find_new_threads_1 (thread_ptid);
417 attach_thread (thread_ptid, thp, &ti);
418 inout->thread_info = find_thread_ptid (thread_ptid);
419 gdb_assert (inout->thread_info != NULL);
425 /* Convert between user-level thread ids and LWP ids. */
428 thread_from_lwp (ptid_t ptid)
432 struct thread_db_info *info;
433 struct thread_get_info_inout io = {0};
435 /* This ptid comes from linux-nat.c, which should always fill in the
437 gdb_assert (GET_LWP (ptid) != 0);
439 info = get_thread_db_info (GET_PID (ptid));
441 /* Access an lwp we know is stopped. */
442 info->proc_handle.ptid = ptid;
443 err = info->td_ta_map_lwp2thr_p (info->thread_agent, GET_LWP (ptid), &th);
445 error (_("Cannot find user-level thread for LWP %ld: %s"),
446 GET_LWP (ptid), thread_db_err_str (err));
448 /* Fetch the thread info. If we get back TD_THR_ZOMBIE, then the
449 event thread has already died. If another gdb interface has called
450 thread_alive() previously, the thread won't be found on the thread list
451 anymore. In that case, we don't want to process this ptid anymore
452 to avoid the possibility of later treating it as a newly
453 discovered thread id that we should add to the list. Thus,
454 we return a -1 ptid which is also how the thread list marks a
456 io.thread_db_info = info;
457 io.thread_info = NULL;
458 if (thread_get_info_callback (&th, &io) == TD_THR_ZOMBIE
459 && io.thread_info == NULL)
460 return minus_one_ptid;
462 gdb_assert (ptid_get_tid (ptid) == 0);
467 /* Attach to lwp PTID, doing whatever else is required to have this
468 LWP under the debugger's control --- e.g., enabling event
469 reporting. Returns true on success. */
471 thread_db_attach_lwp (ptid_t ptid)
476 struct thread_db_info *info;
478 info = get_thread_db_info (GET_PID (ptid));
483 /* This ptid comes from linux-nat.c, which should always fill in the
485 gdb_assert (GET_LWP (ptid) != 0);
487 /* Access an lwp we know is stopped. */
488 info->proc_handle.ptid = ptid;
490 /* If we have only looked at the first thread before libpthread was
491 initialized, we may not know its thread ID yet. Make sure we do
492 before we add another thread to the list. */
493 if (!have_threads (ptid))
494 thread_db_find_new_threads_1 (ptid);
496 err = info->td_ta_map_lwp2thr_p (info->thread_agent, GET_LWP (ptid), &th);
498 /* Cannot find user-level thread. */
501 err = info->td_thr_get_info_p (&th, &ti);
504 warning (_("Cannot get thread info: %s"), thread_db_err_str (err));
508 attach_thread (ptid, &th, &ti);
513 verbose_dlsym (void *handle, const char *name)
515 void *sym = dlsym (handle, name);
517 warning (_("Symbol \"%s\" not found in libthread_db: %s"),
523 enable_thread_event (int event, CORE_ADDR *bp)
527 struct thread_db_info *info;
529 info = get_thread_db_info (GET_PID (inferior_ptid));
531 /* Access an lwp we know is stopped. */
532 info->proc_handle.ptid = inferior_ptid;
534 /* Get the breakpoint address for thread EVENT. */
535 err = info->td_ta_event_addr_p (info->thread_agent, event, ¬ify);
539 /* Set up the breakpoint. */
540 gdb_assert (exec_bfd);
541 (*bp) = (gdbarch_convert_from_func_ptr_addr
543 /* Do proper sign extension for the target. */
544 (bfd_get_sign_extend_vma (exec_bfd) > 0
545 ? (CORE_ADDR) (intptr_t) notify.u.bptaddr
546 : (CORE_ADDR) (uintptr_t) notify.u.bptaddr),
548 create_thread_event_breakpoint (target_gdbarch, *bp);
554 enable_thread_event_reporting (void)
556 td_thr_events_t events;
558 #ifdef HAVE_GNU_LIBC_VERSION_H
559 const char *libc_version;
560 int libc_major, libc_minor;
562 struct thread_db_info *info;
564 info = get_thread_db_info (GET_PID (inferior_ptid));
566 /* We cannot use the thread event reporting facility if these
567 functions aren't available. */
568 if (info->td_ta_event_addr_p == NULL
569 || info->td_ta_set_event_p == NULL
570 || info->td_ta_event_getmsg_p == NULL
571 || info->td_thr_event_enable_p == NULL)
574 /* Set the process wide mask saying which events we're interested in. */
575 td_event_emptyset (&events);
576 td_event_addset (&events, TD_CREATE);
578 #ifdef HAVE_GNU_LIBC_VERSION_H
579 /* The event reporting facility is broken for TD_DEATH events in
580 glibc 2.1.3, so don't enable it if we have glibc but a lower
582 libc_version = gnu_get_libc_version ();
583 if (sscanf (libc_version, "%d.%d", &libc_major, &libc_minor) == 2
584 && (libc_major > 2 || (libc_major == 2 && libc_minor > 1)))
586 td_event_addset (&events, TD_DEATH);
588 err = info->td_ta_set_event_p (info->thread_agent, &events);
591 warning (_("Unable to set global thread event mask: %s"),
592 thread_db_err_str (err));
596 /* Delete previous thread event breakpoints, if any. */
597 remove_thread_event_breakpoints ();
598 info->td_create_bp_addr = 0;
599 info->td_death_bp_addr = 0;
601 /* Set up the thread creation event. */
602 err = enable_thread_event (TD_CREATE, &info->td_create_bp_addr);
605 warning (_("Unable to get location for thread creation breakpoint: %s"),
606 thread_db_err_str (err));
610 /* Set up the thread death event. */
611 err = enable_thread_event (TD_DEATH, &info->td_death_bp_addr);
614 warning (_("Unable to get location for thread death breakpoint: %s"),
615 thread_db_err_str (err));
620 /* Same as thread_db_find_new_threads_1, but silently ignore errors. */
623 thread_db_find_new_threads_silently (ptid_t ptid)
625 volatile struct gdb_exception except;
627 TRY_CATCH (except, RETURN_MASK_ERROR)
629 thread_db_find_new_threads_2 (ptid, 1);
632 if (except.reason < 0 && libthread_db_debug)
634 exception_fprintf (gdb_stderr, except,
635 "Warning: thread_db_find_new_threads_silently: ");
639 /* Lookup a library in which given symbol resides.
640 Note: this is looking in GDB process, not in the inferior.
641 Returns library name, or NULL. */
644 dladdr_to_soname (const void *addr)
648 if (dladdr (addr, &info) != 0)
649 return info.dli_fname;
653 /* Attempt to initialize dlopen()ed libthread_db, described by HANDLE.
655 Failure could happen if libthread_db does not have symbols we expect,
656 or when it refuses to work with the current inferior (e.g. due to
657 version mismatch between libthread_db and libpthread). */
660 try_thread_db_load_1 (struct thread_db_info *info)
664 /* Initialize pointers to the dynamic library functions we will use.
665 Essential functions first. */
667 info->td_init_p = verbose_dlsym (info->handle, "td_init");
668 if (info->td_init_p == NULL)
671 err = info->td_init_p ();
674 warning (_("Cannot initialize libthread_db: %s"),
675 thread_db_err_str (err));
679 info->td_ta_new_p = verbose_dlsym (info->handle, "td_ta_new");
680 if (info->td_ta_new_p == NULL)
683 /* Initialize the structure that identifies the child process. */
684 info->proc_handle.ptid = inferior_ptid;
686 /* Now attempt to open a connection to the thread library. */
687 err = info->td_ta_new_p (&info->proc_handle, &info->thread_agent);
690 if (libthread_db_debug)
691 printf_unfiltered (_("td_ta_new failed: %s\n"),
692 thread_db_err_str (err));
697 #ifdef THREAD_DB_HAS_TD_VERSION
700 /* The errors above are not unexpected and silently ignored:
701 they just mean we haven't found correct version of
705 warning (_("td_ta_new failed: %s"), thread_db_err_str (err));
710 info->td_ta_map_id2thr_p = verbose_dlsym (info->handle, "td_ta_map_id2thr");
711 if (info->td_ta_map_id2thr_p == NULL)
714 info->td_ta_map_lwp2thr_p = verbose_dlsym (info->handle,
715 "td_ta_map_lwp2thr");
716 if (info->td_ta_map_lwp2thr_p == NULL)
719 info->td_ta_thr_iter_p = verbose_dlsym (info->handle, "td_ta_thr_iter");
720 if (info->td_ta_thr_iter_p == NULL)
723 info->td_thr_validate_p = verbose_dlsym (info->handle, "td_thr_validate");
724 if (info->td_thr_validate_p == NULL)
727 info->td_thr_get_info_p = verbose_dlsym (info->handle, "td_thr_get_info");
728 if (info->td_thr_get_info_p == NULL)
731 /* These are not essential. */
732 info->td_ta_event_addr_p = dlsym (info->handle, "td_ta_event_addr");
733 info->td_ta_set_event_p = dlsym (info->handle, "td_ta_set_event");
734 info->td_ta_clear_event_p = dlsym (info->handle, "td_ta_clear_event");
735 info->td_ta_event_getmsg_p = dlsym (info->handle, "td_ta_event_getmsg");
736 info->td_thr_event_enable_p = dlsym (info->handle, "td_thr_event_enable");
737 info->td_thr_tls_get_addr_p = dlsym (info->handle, "td_thr_tls_get_addr");
739 printf_unfiltered (_("[Thread debugging using libthread_db enabled]\n"));
741 if (libthread_db_debug || *libthread_db_search_path)
745 library = dladdr_to_soname (*info->td_ta_new_p);
747 library = LIBTHREAD_DB_SO;
749 printf_unfiltered (_("Using host libthread_db library \"%s\".\n"),
753 /* The thread library was detected. Activate the thread_db target
754 if this is the first process using it. */
755 if (thread_db_list->next == NULL)
756 push_target (&thread_db_ops);
758 /* Enable event reporting, but not when debugging a core file. */
759 if (target_has_execution)
760 enable_thread_event_reporting ();
762 /* There appears to be a bug in glibc-2.3.6: calls to td_thr_get_info fail
763 with TD_ERR for statically linked executables if td_thr_get_info is
764 called before glibc has initialized itself. Silently ignore such
765 errors, and let gdb enumerate threads again later. */
766 thread_db_find_new_threads_silently (inferior_ptid);
771 /* Attempt to use LIBRARY as libthread_db. LIBRARY could be absolute,
772 relative, or just LIBTHREAD_DB. */
775 try_thread_db_load (const char *library)
778 struct thread_db_info *info;
780 if (libthread_db_debug)
781 printf_unfiltered (_("Trying host libthread_db library: %s.\n"),
783 handle = dlopen (library, RTLD_NOW);
786 if (libthread_db_debug)
787 printf_unfiltered (_("dlopen failed: %s.\n"), dlerror ());
791 if (libthread_db_debug && strchr (library, '/') == NULL)
795 td_init = dlsym (handle, "td_init");
798 const char *const libpath = dladdr_to_soname (td_init);
801 printf_unfiltered (_("Host %s resolved to: %s.\n"),
806 info = add_thread_db_info (handle);
808 if (try_thread_db_load_1 (info))
811 /* This library "refused" to work on current inferior. */
812 delete_thread_db_info (GET_PID (inferior_ptid));
817 /* Search libthread_db_search_path for libthread_db which "agrees"
818 to work on current inferior. */
821 thread_db_load_search (void)
824 const char *search_path = libthread_db_search_path;
829 const char *end = strchr (search_path, ':');
833 size_t len = end - search_path;
835 if (len + 1 + strlen (LIBTHREAD_DB_SO) + 1 > sizeof (path))
837 char *cp = xmalloc (len + 1);
839 memcpy (cp, search_path, len);
841 warning (_("libthread_db_search_path component too long,"
842 " ignored: %s."), cp);
844 search_path += len + 1;
847 memcpy (path, search_path, len);
849 search_path += len + 1;
853 size_t len = strlen (search_path);
855 if (len + 1 + strlen (LIBTHREAD_DB_SO) + 1 > sizeof (path))
857 warning (_("libthread_db_search_path component too long,"
858 " ignored: %s."), search_path);
861 memcpy (path, search_path, len + 1);
865 strcat (path, LIBTHREAD_DB_SO);
866 if (try_thread_db_load (path))
873 rc = try_thread_db_load (LIBTHREAD_DB_SO);
877 /* Attempt to load and initialize libthread_db.
878 Return 1 on success. */
881 thread_db_load (void)
884 struct thread_db_info *info;
886 info = get_thread_db_info (GET_PID (inferior_ptid));
891 /* Don't attempt to use thread_db on executables not running
893 if (!target_has_registers)
896 /* Don't attempt to use thread_db for remote targets. */
897 if (!(target_can_run (¤t_target) || core_bfd))
900 if (thread_db_load_search ())
903 /* None of the libthread_db's on our search path, not the system default
904 ones worked. If the executable is dynamically linked against
905 libpthread, try loading libthread_db from the same directory. */
908 if (libpthread_name_p (obj->name))
910 char path[PATH_MAX], *cp;
912 gdb_assert (strlen (obj->name) < sizeof (path));
913 strcpy (path, obj->name);
914 cp = strrchr (path, '/');
918 warning (_("Expected absolute pathname for libpthread in the"
919 " inferior, but got %s."), path);
921 else if (cp + 1 + strlen (LIBTHREAD_DB_SO) + 1 > path + sizeof (path))
923 warning (_("Unexpected: path to libpthread in the inferior is"
924 " too long: %s"), path);
928 strcpy (cp + 1, LIBTHREAD_DB_SO);
929 if (try_thread_db_load (path))
932 warning (_("Unable to find libthread_db matching inferior's thread"
933 " library, thread debugging will not be available."));
936 /* Either this executable isn't using libpthread at all, or it is
937 statically linked. Since we can't easily distinguish these two cases,
938 no warning is issued. */
943 disable_thread_event_reporting (struct thread_db_info *info)
945 if (info->td_ta_clear_event_p != NULL)
947 td_thr_events_t events;
949 /* Set the process wide mask saying we aren't interested in any
951 td_event_fillset (&events);
952 info->td_ta_clear_event_p (info->thread_agent, &events);
955 info->td_create_bp_addr = 0;
956 info->td_death_bp_addr = 0;
960 check_thread_signals (void)
967 lin_thread_get_thread_signals (&mask);
968 sigemptyset (&thread_stop_set);
969 sigemptyset (&thread_print_set);
971 for (i = 1; i < NSIG; i++)
973 if (sigismember (&mask, i))
975 if (signal_stop_update (target_signal_from_host (i), 0))
976 sigaddset (&thread_stop_set, i);
977 if (signal_print_update (target_signal_from_host (i), 0))
978 sigaddset (&thread_print_set, i);
985 /* Check whether thread_db is usable. This function is called when
986 an inferior is created (or otherwise acquired, e.g. attached to)
987 and when new shared libraries are loaded into a running process. */
990 check_for_thread_db (void)
992 /* Do nothing if we couldn't load libthread_db.so.1. */
993 if (!thread_db_load ())
998 thread_db_new_objfile (struct objfile *objfile)
1000 /* This observer must always be called with inferior_ptid set
1003 if (objfile != NULL)
1004 check_for_thread_db ();
1007 /* Attach to a new thread. This function is called when we receive a
1008 TD_CREATE event or when we iterate over all threads and find one
1009 that wasn't already in our list. Returns true on success. */
1012 attach_thread (ptid_t ptid, const td_thrhandle_t *th_p,
1013 const td_thrinfo_t *ti_p)
1015 struct private_thread_info *private;
1016 struct thread_info *tp = NULL;
1018 struct thread_db_info *info;
1020 /* If we're being called after a TD_CREATE event, we may already
1021 know about this thread. There are two ways this can happen. We
1022 may have iterated over all threads between the thread creation
1023 and the TD_CREATE event, for instance when the user has issued
1024 the `info threads' command before the SIGTRAP for hitting the
1025 thread creation breakpoint was reported. Alternatively, the
1026 thread may have exited and a new one been created with the same
1027 thread ID. In the first case we don't need to do anything; in
1028 the second case we should discard information about the dead
1029 thread and attach to the new one. */
1030 if (in_thread_list (ptid))
1032 tp = find_thread_ptid (ptid);
1033 gdb_assert (tp != NULL);
1035 /* If tp->private is NULL, then GDB is already attached to this
1036 thread, but we do not know anything about it. We can learn
1037 about it here. This can only happen if we have some other
1038 way besides libthread_db to notice new threads (i.e.
1039 PTRACE_EVENT_CLONE); assume the same mechanism notices thread
1040 exit, so this can not be a stale thread recreated with the
1042 if (tp->private != NULL)
1044 if (!tp->private->dying)
1047 delete_thread (ptid);
1052 if (target_has_execution)
1053 check_thread_signals ();
1055 if (ti_p->ti_state == TD_THR_UNKNOWN || ti_p->ti_state == TD_THR_ZOMBIE)
1056 return 0; /* A zombie thread -- do not attach. */
1058 /* Under GNU/Linux, we have to attach to each and every thread. */
1059 if (target_has_execution
1061 && lin_lwp_attach_lwp (BUILD_LWP (ti_p->ti_lid, GET_PID (ptid))) < 0)
1064 /* Construct the thread's private data. */
1065 private = xmalloc (sizeof (struct private_thread_info));
1066 memset (private, 0, sizeof (struct private_thread_info));
1068 /* A thread ID of zero may mean the thread library has not initialized
1069 yet. But we shouldn't even get here if that's the case. FIXME:
1070 if we change GDB to always have at least one thread in the thread
1071 list this will have to go somewhere else; maybe private == NULL
1072 until the thread_db target claims it. */
1073 gdb_assert (ti_p->ti_tid != 0);
1074 private->th = *th_p;
1075 private->tid = ti_p->ti_tid;
1077 /* Add the thread to GDB's thread list. */
1079 add_thread_with_info (ptid, private);
1081 tp->private = private;
1083 info = get_thread_db_info (GET_PID (ptid));
1085 /* Enable thread event reporting for this thread, except when
1086 debugging a core file. */
1087 if (target_has_execution)
1089 err = info->td_thr_event_enable_p (th_p, 1);
1091 error (_("Cannot enable thread event reporting for %s: %s"),
1092 target_pid_to_str (ptid), thread_db_err_str (err));
1099 detach_thread (ptid_t ptid)
1101 struct thread_info *thread_info;
1103 /* Don't delete the thread now, because it still reports as active
1104 until it has executed a few instructions after the event
1105 breakpoint - if we deleted it now, "info threads" would cause us
1106 to re-attach to it. Just mark it as having had a TD_DEATH
1107 event. This means that we won't delete it from our thread list
1108 until we notice that it's dead (via prune_threads), or until
1109 something re-uses its thread ID. We'll report the thread exit
1110 when the underlying LWP dies. */
1111 thread_info = find_thread_ptid (ptid);
1112 gdb_assert (thread_info != NULL && thread_info->private != NULL);
1113 thread_info->private->dying = 1;
1117 thread_db_detach (struct target_ops *ops, char *args, int from_tty)
1119 struct target_ops *target_beneath = find_target_beneath (ops);
1120 struct thread_db_info *info;
1122 info = get_thread_db_info (GET_PID (inferior_ptid));
1126 if (target_has_execution)
1128 disable_thread_event_reporting (info);
1130 /* Delete the old thread event breakpoints. Note that
1131 unlike when mourning, we can remove them here because
1132 there's still a live inferior to poke at. In any case,
1133 GDB will not try to insert anything in the inferior when
1134 removing a breakpoint. */
1135 remove_thread_event_breakpoints ();
1138 delete_thread_db_info (GET_PID (inferior_ptid));
1141 target_beneath->to_detach (target_beneath, args, from_tty);
1143 /* NOTE: From this point on, inferior_ptid is null_ptid. */
1145 /* If there are no more processes using libpthread, detach the
1146 thread_db target ops. */
1147 if (!thread_db_list)
1148 unpush_target (&thread_db_ops);
1151 /* Check if PID is currently stopped at the location of a thread event
1152 breakpoint location. If it is, read the event message and act upon
1156 check_event (ptid_t ptid)
1158 struct regcache *regcache = get_thread_regcache (ptid);
1159 struct gdbarch *gdbarch = get_regcache_arch (regcache);
1165 struct thread_db_info *info;
1167 info = get_thread_db_info (GET_PID (ptid));
1169 /* Bail out early if we're not at a thread event breakpoint. */
1170 stop_pc = regcache_read_pc (regcache)
1171 - gdbarch_decr_pc_after_break (gdbarch);
1172 if (stop_pc != info->td_create_bp_addr
1173 && stop_pc != info->td_death_bp_addr)
1176 /* Access an lwp we know is stopped. */
1177 info->proc_handle.ptid = ptid;
1179 /* If we have only looked at the first thread before libpthread was
1180 initialized, we may not know its thread ID yet. Make sure we do
1181 before we add another thread to the list. */
1182 if (!have_threads (ptid))
1183 thread_db_find_new_threads_1 (ptid);
1185 /* If we are at a create breakpoint, we do not know what new lwp
1186 was created and cannot specifically locate the event message for it.
1187 We have to call td_ta_event_getmsg() to get
1188 the latest message. Since we have no way of correlating whether
1189 the event message we get back corresponds to our breakpoint, we must
1190 loop and read all event messages, processing them appropriately.
1191 This guarantees we will process the correct message before continuing
1192 from the breakpoint.
1194 Currently, death events are not enabled. If they are enabled,
1195 the death event can use the td_thr_event_getmsg() interface to
1196 get the message specifically for that lwp and avoid looping
1203 err = info->td_ta_event_getmsg_p (info->thread_agent, &msg);
1206 if (err == TD_NOMSG)
1209 error (_("Cannot get thread event message: %s"),
1210 thread_db_err_str (err));
1213 err = info->td_thr_get_info_p (msg.th_p, &ti);
1215 error (_("Cannot get thread info: %s"), thread_db_err_str (err));
1217 ptid = ptid_build (GET_PID (ptid), ti.ti_lid, 0);
1222 /* Call attach_thread whether or not we already know about a
1223 thread with this thread ID. */
1224 attach_thread (ptid, msg.th_p, &ti);
1230 if (!in_thread_list (ptid))
1231 error (_("Spurious thread death event."));
1233 detach_thread (ptid);
1238 error (_("Spurious thread event."));
1245 thread_db_wait (struct target_ops *ops,
1246 ptid_t ptid, struct target_waitstatus *ourstatus,
1249 struct thread_db_info *info;
1250 struct target_ops *beneath = find_target_beneath (ops);
1252 ptid = beneath->to_wait (beneath, ptid, ourstatus, options);
1254 if (ourstatus->kind == TARGET_WAITKIND_IGNORE)
1257 if (ourstatus->kind == TARGET_WAITKIND_EXITED
1258 || ourstatus->kind == TARGET_WAITKIND_SIGNALLED)
1261 info = get_thread_db_info (GET_PID (ptid));
1263 /* If this process isn't using thread_db, we're done. */
1267 if (ourstatus->kind == TARGET_WAITKIND_EXECD)
1269 /* New image, it may or may not end up using thread_db. Assume
1270 not unless we find otherwise. */
1271 delete_thread_db_info (GET_PID (ptid));
1272 if (!thread_db_list)
1273 unpush_target (&thread_db_ops);
1275 /* Thread event breakpoints are deleted by
1276 update_breakpoints_after_exec. */
1281 /* If we do not know about the main thread yet, this would be a good time to
1283 if (ourstatus->kind == TARGET_WAITKIND_STOPPED && !have_threads (ptid))
1284 thread_db_find_new_threads_1 (ptid);
1286 if (ourstatus->kind == TARGET_WAITKIND_STOPPED
1287 && ourstatus->value.sig == TARGET_SIGNAL_TRAP)
1288 /* Check for a thread event. */
1291 if (have_threads (ptid))
1293 /* Change ptids back into the higher level PID + TID format. If
1294 the thread is dead and no longer on the thread list, we will
1295 get back a dead ptid. This can occur if the thread death
1296 event gets postponed by other simultaneous events. In such a
1297 case, we want to just ignore the event and continue on. */
1299 ptid = thread_from_lwp (ptid);
1300 if (GET_PID (ptid) == -1)
1301 ourstatus->kind = TARGET_WAITKIND_SPURIOUS;
1308 thread_db_mourn_inferior (struct target_ops *ops)
1310 struct target_ops *target_beneath = find_target_beneath (ops);
1312 delete_thread_db_info (GET_PID (inferior_ptid));
1314 target_beneath->to_mourn_inferior (target_beneath);
1316 /* Delete the old thread event breakpoints. Do this after mourning
1317 the inferior, so that we don't try to uninsert them. */
1318 remove_thread_event_breakpoints ();
1320 /* Detach thread_db target ops. */
1321 if (!thread_db_list)
1322 unpush_target (ops);
1325 struct callback_data
1327 struct thread_db_info *info;
1332 find_new_threads_callback (const td_thrhandle_t *th_p, void *data)
1337 struct thread_info *tp;
1338 struct callback_data *cb_data = data;
1339 struct thread_db_info *info = cb_data->info;
1341 err = info->td_thr_get_info_p (th_p, &ti);
1343 error (_("find_new_threads_callback: cannot get thread info: %s"),
1344 thread_db_err_str (err));
1346 if (ti.ti_state == TD_THR_UNKNOWN || ti.ti_state == TD_THR_ZOMBIE)
1347 return 0; /* A zombie -- ignore. */
1351 /* A thread ID of zero means that this is the main thread, but
1352 glibc has not yet initialized thread-local storage and the
1353 pthread library. We do not know what the thread's TID will
1354 be yet. Just enable event reporting and otherwise ignore
1357 /* In that case, we're not stopped in a fork syscall and don't
1358 need this glibc bug workaround. */
1359 info->need_stale_parent_threads_check = 0;
1361 if (target_has_execution)
1363 err = info->td_thr_event_enable_p (th_p, 1);
1365 error (_("Cannot enable thread event reporting for LWP %d: %s"),
1366 (int) ti.ti_lid, thread_db_err_str (err));
1372 /* Ignore stale parent threads, caused by glibc/BZ5983. This is a
1373 bit expensive, as it needs to open /proc/pid/status, so try to
1374 avoid doing the work if we know we don't have to. */
1375 if (info->need_stale_parent_threads_check)
1377 int tgid = linux_proc_get_tgid (ti.ti_lid);
1379 if (tgid != -1 && tgid != info->pid)
1383 ptid = ptid_build (info->pid, ti.ti_lid, 0);
1384 tp = find_thread_ptid (ptid);
1385 if (tp == NULL || tp->private == NULL)
1387 if (attach_thread (ptid, th_p, &ti))
1388 cb_data->new_threads += 1;
1390 /* Problem attaching this thread; perhaps it exited before we
1392 This could mean that the thread list inside glibc itself is in
1393 inconsistent state, and libthread_db could go on looping forever
1394 (observed with glibc-2.3.6). To prevent that, terminate
1395 iteration: thread_db_find_new_threads_2 will retry. */
1402 /* Helper for thread_db_find_new_threads_2.
1403 Returns number of new threads found. */
1406 find_new_threads_once (struct thread_db_info *info, int iteration,
1409 volatile struct gdb_exception except;
1410 struct callback_data data;
1411 td_err_e err = TD_ERR;
1414 data.new_threads = 0;
1416 TRY_CATCH (except, RETURN_MASK_ERROR)
1418 /* Iterate over all user-space threads to discover new threads. */
1419 err = info->td_ta_thr_iter_p (info->thread_agent,
1420 find_new_threads_callback,
1423 TD_THR_LOWEST_PRIORITY,
1425 TD_THR_ANY_USER_FLAGS);
1428 if (libthread_db_debug)
1430 if (except.reason < 0)
1431 exception_fprintf (gdb_stderr, except,
1432 "Warning: find_new_threads_once: ");
1434 printf_filtered (_("Found %d new threads in iteration %d.\n"),
1435 data.new_threads, iteration);
1441 return data.new_threads;
1444 /* Search for new threads, accessing memory through stopped thread
1445 PTID. If UNTIL_NO_NEW is true, repeat searching until several
1446 searches in a row do not discover any new threads. */
1449 thread_db_find_new_threads_2 (ptid_t ptid, int until_no_new)
1452 struct thread_db_info *info;
1453 int pid = ptid_get_pid (ptid);
1456 if (target_has_execution)
1458 struct lwp_info *lp;
1460 /* In linux, we can only read memory through a stopped lwp. */
1462 if (lp->stopped && ptid_get_pid (lp->ptid) == pid)
1466 /* There is no stopped thread. Bail out. */
1470 info = get_thread_db_info (GET_PID (ptid));
1472 /* Access an lwp we know is stopped. */
1473 info->proc_handle.ptid = ptid;
1477 /* Require 4 successive iterations which do not find any new threads.
1478 The 4 is a heuristic: there is an inherent race here, and I have
1479 seen that 2 iterations in a row are not always sufficient to
1480 "capture" all threads. */
1481 for (i = 0, loop = 0; loop < 4; ++i, ++loop)
1482 if (find_new_threads_once (info, i, NULL) != 0)
1483 /* Found some new threads. Restart the loop from beginning. */
1488 find_new_threads_once (info, 0, &err);
1490 error (_("Cannot find new threads: %s"), thread_db_err_str (err));
1495 thread_db_find_new_threads_1 (ptid_t ptid)
1497 thread_db_find_new_threads_2 (ptid, 0);
1501 update_thread_core (struct lwp_info *info, void *closure)
1503 info->core = linux_nat_core_of_thread_1 (info->ptid);
1508 thread_db_find_new_threads (struct target_ops *ops)
1510 struct thread_db_info *info;
1512 info = get_thread_db_info (GET_PID (inferior_ptid));
1517 thread_db_find_new_threads_1 (inferior_ptid);
1519 if (target_has_execution)
1520 iterate_over_lwps (minus_one_ptid /* iterate over all */,
1521 update_thread_core, NULL);
1525 thread_db_pid_to_str (struct target_ops *ops, ptid_t ptid)
1527 struct thread_info *thread_info = find_thread_ptid (ptid);
1528 struct target_ops *beneath;
1530 if (thread_info != NULL && thread_info->private != NULL)
1532 static char buf[64];
1535 tid = thread_info->private->tid;
1536 snprintf (buf, sizeof (buf), "Thread 0x%lx (LWP %ld)",
1537 tid, GET_LWP (ptid));
1542 beneath = find_target_beneath (ops);
1543 if (beneath->to_pid_to_str (beneath, ptid))
1544 return beneath->to_pid_to_str (beneath, ptid);
1546 return normal_pid_to_str (ptid);
1549 /* Return a string describing the state of the thread specified by
1553 thread_db_extra_thread_info (struct thread_info *info)
1555 if (info->private == NULL)
1558 if (info->private->dying)
1564 /* Get the address of the thread local variable in load module LM which
1565 is stored at OFFSET within the thread local storage for thread PTID. */
1568 thread_db_get_thread_local_address (struct target_ops *ops,
1573 struct thread_info *thread_info;
1574 struct target_ops *beneath;
1576 /* If we have not discovered any threads yet, check now. */
1577 if (!have_threads (ptid))
1578 thread_db_find_new_threads_1 (ptid);
1580 /* Find the matching thread. */
1581 thread_info = find_thread_ptid (ptid);
1583 if (thread_info != NULL && thread_info->private != NULL)
1587 struct thread_db_info *info;
1589 info = get_thread_db_info (GET_PID (ptid));
1591 /* glibc doesn't provide the needed interface. */
1592 if (!info->td_thr_tls_get_addr_p)
1593 throw_error (TLS_NO_LIBRARY_SUPPORT_ERROR,
1594 _("No TLS library support"));
1596 /* Caller should have verified that lm != 0. */
1597 gdb_assert (lm != 0);
1599 /* Finally, get the address of the variable. */
1600 /* Note the cast through uintptr_t: this interface only works if
1601 a target address fits in a psaddr_t, which is a host pointer.
1602 So a 32-bit debugger can not access 64-bit TLS through this. */
1603 err = info->td_thr_tls_get_addr_p (&thread_info->private->th,
1604 (psaddr_t)(uintptr_t) lm,
1607 #ifdef THREAD_DB_HAS_TD_NOTALLOC
1608 /* The memory hasn't been allocated, yet. */
1609 if (err == TD_NOTALLOC)
1610 /* Now, if libthread_db provided the initialization image's
1611 address, we *could* try to build a non-lvalue value from
1612 the initialization image. */
1613 throw_error (TLS_NOT_ALLOCATED_YET_ERROR,
1614 _("TLS not allocated yet"));
1617 /* Something else went wrong. */
1619 throw_error (TLS_GENERIC_ERROR,
1620 (("%s")), thread_db_err_str (err));
1622 /* Cast assuming host == target. Joy. */
1623 /* Do proper sign extension for the target. */
1624 gdb_assert (exec_bfd);
1625 return (bfd_get_sign_extend_vma (exec_bfd) > 0
1626 ? (CORE_ADDR) (intptr_t) address
1627 : (CORE_ADDR) (uintptr_t) address);
1630 beneath = find_target_beneath (ops);
1631 if (beneath->to_get_thread_local_address)
1632 return beneath->to_get_thread_local_address (beneath, ptid, lm, offset);
1634 throw_error (TLS_GENERIC_ERROR,
1635 _("TLS not supported on this target"));
1638 /* Callback routine used to find a thread based on the TID part of
1642 thread_db_find_thread_from_tid (struct thread_info *thread, void *data)
1644 long *tid = (long *) data;
1646 if (thread->private->tid == *tid)
1652 /* Implement the to_get_ada_task_ptid target method for this target. */
1655 thread_db_get_ada_task_ptid (long lwp, long thread)
1657 struct thread_info *thread_info;
1659 thread_db_find_new_threads_1 (inferior_ptid);
1660 thread_info = iterate_over_threads (thread_db_find_thread_from_tid, &thread);
1662 gdb_assert (thread_info != NULL);
1664 return (thread_info->ptid);
1668 thread_db_resume (struct target_ops *ops,
1669 ptid_t ptid, int step, enum target_signal signo)
1671 struct target_ops *beneath = find_target_beneath (ops);
1672 struct thread_db_info *info;
1674 if (ptid_equal (ptid, minus_one_ptid))
1675 info = get_thread_db_info (GET_PID (inferior_ptid));
1677 info = get_thread_db_info (GET_PID (ptid));
1679 /* This workaround is only needed for child fork lwps stopped in a
1680 PTRACE_O_TRACEFORK event. When the inferior is resumed, the
1681 workaround can be disabled. */
1683 info->need_stale_parent_threads_check = 0;
1685 beneath->to_resume (beneath, ptid, step, signo);
1689 init_thread_db_ops (void)
1691 thread_db_ops.to_shortname = "multi-thread";
1692 thread_db_ops.to_longname = "multi-threaded child process.";
1693 thread_db_ops.to_doc = "Threads and pthreads support.";
1694 thread_db_ops.to_detach = thread_db_detach;
1695 thread_db_ops.to_wait = thread_db_wait;
1696 thread_db_ops.to_resume = thread_db_resume;
1697 thread_db_ops.to_mourn_inferior = thread_db_mourn_inferior;
1698 thread_db_ops.to_find_new_threads = thread_db_find_new_threads;
1699 thread_db_ops.to_pid_to_str = thread_db_pid_to_str;
1700 thread_db_ops.to_stratum = thread_stratum;
1701 thread_db_ops.to_has_thread_control = tc_schedlock;
1702 thread_db_ops.to_get_thread_local_address
1703 = thread_db_get_thread_local_address;
1704 thread_db_ops.to_extra_thread_info = thread_db_extra_thread_info;
1705 thread_db_ops.to_get_ada_task_ptid = thread_db_get_ada_task_ptid;
1706 thread_db_ops.to_magic = OPS_MAGIC;
1709 /* Provide a prototype to silence -Wmissing-prototypes. */
1710 extern initialize_file_ftype _initialize_thread_db;
1713 _initialize_thread_db (void)
1715 init_thread_db_ops ();
1716 add_target (&thread_db_ops);
1718 /* Defer loading of libthread_db.so until inferior is running.
1719 This allows gdb to load correct libthread_db for a given
1720 executable -- there could be mutiple versions of glibc,
1721 compiled with LinuxThreads or NPTL, and until there is
1722 a running inferior, we can't tell which libthread_db is
1723 the correct one to load. */
1725 libthread_db_search_path = xstrdup (LIBTHREAD_DB_SEARCH_PATH);
1727 add_setshow_optional_filename_cmd ("libthread-db-search-path",
1729 &libthread_db_search_path, _("\
1730 Set search path for libthread_db."), _("\
1731 Show the current search path or libthread_db."), _("\
1732 This path is used to search for libthread_db to be loaded into \
1734 Its value is a colon (':') separate list of directories to search.\n\
1735 Setting the search path to an empty list resets it to its default value."),
1736 set_libthread_db_search_path,
1738 &setlist, &showlist);
1740 add_setshow_zinteger_cmd ("libthread-db", class_maintenance,
1741 &libthread_db_debug, _("\
1742 Set libthread-db debugging."), _("\
1743 Show libthread-db debugging."), _("\
1744 When non-zero, libthread-db debugging is enabled."),
1746 show_libthread_db_debug,
1747 &setdebuglist, &showdebuglist);
1749 /* Add ourselves to objfile event chain. */
1750 observer_attach_new_objfile (thread_db_new_objfile);