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
);
163 static void thread_db_find_new_threads_2 (ptid_t ptid
, int until_no_new
);
165 /* Add the current inferior to the list of processes using libpthread.
166 Return a pointer to the newly allocated object that was added to
167 THREAD_DB_LIST. HANDLE is the handle returned by dlopen'ing
170 static struct thread_db_info
*
171 add_thread_db_info (void *handle
)
174 struct thread_db_info
*info
;
176 info
= xcalloc (1, sizeof (*info
));
177 info
->pid
= ptid_get_pid (inferior_ptid
);
178 info
->handle
= handle
;
179 info
->need_stale_parent_threads_check
= 1;
181 info
->next
= thread_db_list
;
182 thread_db_list
= info
;
187 /* Return the thread_db_info object representing the bookkeeping
188 related to process PID, if any; NULL otherwise. */
190 static struct thread_db_info
*
191 get_thread_db_info (int pid
)
193 struct thread_db_info
*info
;
195 for (info
= thread_db_list
; info
; info
= info
->next
)
196 if (pid
== info
->pid
)
202 /* When PID has exited or has been detached, we no longer want to keep
203 track of it as using libpthread. Call this function to discard
204 thread_db related info related to PID. Note that this closes
205 LIBTHREAD_DB_SO's dlopen'ed handle. */
208 delete_thread_db_info (int pid
)
210 struct thread_db_info
*info
, *info_prev
;
214 for (info
= thread_db_list
; info
; info_prev
= info
, info
= info
->next
)
215 if (pid
== info
->pid
)
221 if (info
->handle
!= NULL
)
222 dlclose (info
->handle
);
225 info_prev
->next
= info
->next
;
227 thread_db_list
= info
->next
;
232 /* Prototypes for local functions. */
233 static int attach_thread (ptid_t ptid
, const td_thrhandle_t
*th_p
,
234 const td_thrinfo_t
*ti_p
);
235 static void detach_thread (ptid_t ptid
);
238 /* Use "struct private_thread_info" to cache thread state. This is
239 a substantial optimization. */
241 struct private_thread_info
243 /* Flag set when we see a TD_DEATH event for this thread. */
244 unsigned int dying
:1;
246 /* Cached thread state. */
253 thread_db_err_str (td_err_e err
)
260 return "generic 'call succeeded'";
262 return "generic error";
264 return "no thread to satisfy query";
266 return "no sync handle to satisfy query";
268 return "no LWP to satisfy query";
270 return "invalid process handle";
272 return "invalid thread handle";
274 return "invalid synchronization handle";
276 return "invalid thread agent";
278 return "invalid key";
280 return "no event message for getmsg";
282 return "FPU register set not available";
284 return "application not linked with libthread";
286 return "requested event is not supported";
288 return "capability not available";
290 return "debugger service failed";
292 return "operation not applicable to";
294 return "no thread-specific data for this thread";
296 return "malloc failed";
298 return "only part of register set was written/read";
300 return "X register set not available for this thread";
301 #ifdef THREAD_DB_HAS_TD_NOTALLOC
303 return "thread has not yet allocated TLS for given module";
305 #ifdef THREAD_DB_HAS_TD_VERSION
307 return "versions of libpthread and libthread_db do not match";
309 #ifdef THREAD_DB_HAS_TD_NOTLS
311 return "there is no TLS segment in the given module";
314 snprintf (buf
, sizeof (buf
), "unknown thread_db error '%d'", err
);
319 /* Return 1 if any threads have been registered. There may be none if
320 the threading library is not fully initialized yet. */
323 have_threads_callback (struct thread_info
*thread
, void *args
)
325 int pid
= * (int *) args
;
326 if (ptid_get_pid (thread
->ptid
) != pid
)
329 return thread
->private != NULL
;
333 have_threads (ptid_t ptid
)
335 int pid
= ptid_get_pid (ptid
);
337 return iterate_over_threads (have_threads_callback
, &pid
) != NULL
;
340 struct thread_get_info_inout
342 struct thread_info
*thread_info
;
343 struct thread_db_info
*thread_db_info
;
346 /* A callback function for td_ta_thr_iter, which we use to map all
349 THP is a handle to the current thread; if INFOP is not NULL, the
350 struct thread_info associated with this thread is returned in
353 If the thread is a zombie, TD_THR_ZOMBIE is returned. Otherwise,
354 zero is returned to indicate success. */
357 thread_get_info_callback (const td_thrhandle_t
*thp
, void *argp
)
362 struct thread_get_info_inout
*inout
;
363 struct thread_db_info
*info
;
366 info
= inout
->thread_db_info
;
368 err
= info
->td_thr_get_info_p (thp
, &ti
);
370 error (_("thread_get_info_callback: cannot get thread info: %s"),
371 thread_db_err_str (err
));
373 /* Fill the cache. */
374 thread_ptid
= ptid_build (info
->pid
, ti
.ti_lid
, 0);
375 inout
->thread_info
= find_thread_ptid (thread_ptid
);
377 /* In the case of a zombie thread, don't continue. We don't want to
378 attach to it thinking it is a new thread. */
379 if (ti
.ti_state
== TD_THR_UNKNOWN
|| ti
.ti_state
== TD_THR_ZOMBIE
)
380 return TD_THR_ZOMBIE
;
382 if (inout
->thread_info
== NULL
)
384 /* New thread. Attach to it now (why wait?). */
385 if (!have_threads (thread_ptid
))
386 thread_db_find_new_threads_1 (thread_ptid
);
388 attach_thread (thread_ptid
, thp
, &ti
);
389 inout
->thread_info
= find_thread_ptid (thread_ptid
);
390 gdb_assert (inout
->thread_info
!= NULL
);
396 /* Convert between user-level thread ids and LWP ids. */
399 thread_from_lwp (ptid_t ptid
)
404 struct thread_db_info
*info
;
405 struct thread_get_info_inout io
= {0};
407 /* This ptid comes from linux-nat.c, which should always fill in the
409 gdb_assert (GET_LWP (ptid
) != 0);
411 info
= get_thread_db_info (GET_PID (ptid
));
413 /* Access an lwp we know is stopped. */
414 info
->proc_handle
.ptid
= ptid
;
415 err
= info
->td_ta_map_lwp2thr_p (info
->thread_agent
, GET_LWP (ptid
), &th
);
417 error (_("Cannot find user-level thread for LWP %ld: %s"),
418 GET_LWP (ptid
), thread_db_err_str (err
));
420 /* Fetch the thread info. If we get back TD_THR_ZOMBIE, then the
421 event thread has already died. If another gdb interface has called
422 thread_alive() previously, the thread won't be found on the thread list
423 anymore. In that case, we don't want to process this ptid anymore
424 to avoid the possibility of later treating it as a newly
425 discovered thread id that we should add to the list. Thus,
426 we return a -1 ptid which is also how the thread list marks a
428 io
.thread_db_info
= info
;
429 io
.thread_info
= NULL
;
430 if (thread_get_info_callback (&th
, &io
) == TD_THR_ZOMBIE
431 && io
.thread_info
== NULL
)
432 return minus_one_ptid
;
434 gdb_assert (ptid_get_tid (ptid
) == 0);
439 /* Attach to lwp PTID, doing whatever else is required to have this
440 LWP under the debugger's control --- e.g., enabling event
441 reporting. Returns true on success. */
443 thread_db_attach_lwp (ptid_t ptid
)
448 struct thread_db_info
*info
;
450 info
= get_thread_db_info (GET_PID (ptid
));
455 /* This ptid comes from linux-nat.c, which should always fill in the
457 gdb_assert (GET_LWP (ptid
) != 0);
459 /* Access an lwp we know is stopped. */
460 info
->proc_handle
.ptid
= ptid
;
462 /* If we have only looked at the first thread before libpthread was
463 initialized, we may not know its thread ID yet. Make sure we do
464 before we add another thread to the list. */
465 if (!have_threads (ptid
))
466 thread_db_find_new_threads_1 (ptid
);
468 err
= info
->td_ta_map_lwp2thr_p (info
->thread_agent
, GET_LWP (ptid
), &th
);
470 /* Cannot find user-level thread. */
473 err
= info
->td_thr_get_info_p (&th
, &ti
);
476 warning (_("Cannot get thread info: %s"), thread_db_err_str (err
));
480 attach_thread (ptid
, &th
, &ti
);
485 verbose_dlsym (void *handle
, const char *name
)
487 void *sym
= dlsym (handle
, name
);
489 warning (_("Symbol \"%s\" not found in libthread_db: %s"), name
, dlerror ());
494 enable_thread_event (int event
, CORE_ADDR
*bp
)
498 struct thread_db_info
*info
;
500 info
= get_thread_db_info (GET_PID (inferior_ptid
));
502 /* Access an lwp we know is stopped. */
503 info
->proc_handle
.ptid
= inferior_ptid
;
505 /* Get the breakpoint address for thread EVENT. */
506 err
= info
->td_ta_event_addr_p (info
->thread_agent
, event
, ¬ify
);
510 /* Set up the breakpoint. */
511 gdb_assert (exec_bfd
);
512 (*bp
) = (gdbarch_convert_from_func_ptr_addr
514 /* Do proper sign extension for the target. */
515 (bfd_get_sign_extend_vma (exec_bfd
) > 0
516 ? (CORE_ADDR
) (intptr_t) notify
.u
.bptaddr
517 : (CORE_ADDR
) (uintptr_t) notify
.u
.bptaddr
),
519 create_thread_event_breakpoint (target_gdbarch
, *bp
);
525 enable_thread_event_reporting (void)
527 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_event_getmsg_p
= dlsym (info
->handle
, "td_ta_event_getmsg");
705 info
->td_thr_event_enable_p
= dlsym (info
->handle
, "td_thr_event_enable");
706 info
->td_thr_tls_get_addr_p
= dlsym (info
->handle
, "td_thr_tls_get_addr");
708 printf_unfiltered (_("[Thread debugging using libthread_db enabled]\n"));
710 if (info_verbose
|| *libthread_db_search_path
)
714 library
= dladdr_to_soname (*info
->td_ta_new_p
);
716 library
= LIBTHREAD_DB_SO
;
718 printf_unfiltered (_("Using host libthread_db library \"%s\".\n"),
722 /* The thread library was detected. Activate the thread_db target
723 if this is the first process using it. */
724 if (thread_db_list
->next
== NULL
)
725 push_target (&thread_db_ops
);
727 enable_thread_event_reporting ();
729 /* There appears to be a bug in glibc-2.3.6: calls to td_thr_get_info fail
730 with TD_ERR for statically linked executables if td_thr_get_info is
731 called before glibc has initialized itself. Silently ignore such
732 errors, and let gdb enumerate threads again later. */
733 thread_db_find_new_threads_silently (inferior_ptid
);
738 /* Attempt to use LIBRARY as libthread_db. LIBRARY could be absolute,
739 relative, or just LIBTHREAD_DB. */
742 try_thread_db_load (const char *library
)
745 struct thread_db_info
*info
;
748 printf_unfiltered (_("Trying host libthread_db library: %s.\n"),
750 handle
= dlopen (library
, RTLD_NOW
);
754 printf_unfiltered (_("dlopen failed: %s.\n"), dlerror ());
758 if (info_verbose
&& strchr (library
, '/') == NULL
)
762 td_init
= dlsym (handle
, "td_init");
765 const char *const libpath
= dladdr_to_soname (td_init
);
768 printf_unfiltered (_("Host %s resolved to: %s.\n"),
773 info
= add_thread_db_info (handle
);
775 if (try_thread_db_load_1 (info
))
778 /* This library "refused" to work on current inferior. */
779 delete_thread_db_info (GET_PID (inferior_ptid
));
784 /* Search libthread_db_search_path for libthread_db which "agrees"
785 to work on current inferior. */
788 thread_db_load_search (void)
791 const char *search_path
= libthread_db_search_path
;
796 const char *end
= strchr (search_path
, ':');
799 size_t len
= end
- search_path
;
800 if (len
+ 1 + strlen (LIBTHREAD_DB_SO
) + 1 > sizeof (path
))
802 char *cp
= xmalloc (len
+ 1);
803 memcpy (cp
, search_path
, len
);
805 warning (_("libthread_db_search_path component too long,"
806 " ignored: %s."), cp
);
808 search_path
+= len
+ 1;
811 memcpy (path
, search_path
, len
);
813 search_path
+= len
+ 1;
817 size_t len
= strlen (search_path
);
819 if (len
+ 1 + strlen (LIBTHREAD_DB_SO
) + 1 > sizeof (path
))
821 warning (_("libthread_db_search_path component too long,"
822 " ignored: %s."), search_path
);
825 memcpy (path
, search_path
, len
+ 1);
829 strcat (path
, LIBTHREAD_DB_SO
);
830 if (try_thread_db_load (path
))
837 rc
= try_thread_db_load (LIBTHREAD_DB_SO
);
841 /* Attempt to load and initialize libthread_db.
846 thread_db_load (void)
849 struct thread_db_info
*info
;
851 info
= get_thread_db_info (GET_PID (inferior_ptid
));
856 /* Don't attempt to use thread_db on targets which can not run
857 (executables not running yet, core files) for now. */
858 if (!target_has_execution
)
861 /* Don't attempt to use thread_db for remote targets. */
862 if (!target_can_run (¤t_target
))
865 if (thread_db_load_search ())
868 /* None of the libthread_db's on our search path, not the system default
869 ones worked. If the executable is dynamically linked against
870 libpthread, try loading libthread_db from the same directory. */
873 if (libpthread_name_p (obj
->name
))
875 char path
[PATH_MAX
], *cp
;
877 gdb_assert (strlen (obj
->name
) < sizeof (path
));
878 strcpy (path
, obj
->name
);
879 cp
= strrchr (path
, '/');
883 warning (_("Expected absolute pathname for libpthread in the"
884 " inferior, but got %s."), path
);
886 else if (cp
+ 1 + strlen (LIBTHREAD_DB_SO
) + 1 > path
+ sizeof (path
))
888 warning (_("Unexpected: path to libpthread in the inferior is"
889 " too long: %s"), path
);
893 strcpy (cp
+ 1, LIBTHREAD_DB_SO
);
894 if (try_thread_db_load (path
))
897 warning (_("Unable to find libthread_db matching inferior's thread"
898 " library, thread debugging will not be available."));
901 /* Either this executable isn't using libpthread at all, or it is
902 statically linked. Since we can't easily distinguish these two cases,
903 no warning is issued. */
908 disable_thread_event_reporting (void)
910 td_thr_events_t events
;
911 struct thread_db_info
*info
;
913 info
= get_thread_db_info (GET_PID (inferior_ptid
));
915 /* Set the process wide mask saying we aren't interested in any
917 td_event_emptyset (&events
);
918 info
->td_ta_set_event_p (info
->thread_agent
, &events
);
920 /* Delete thread event breakpoints, if any. */
921 remove_thread_event_breakpoints ();
922 info
->td_create_bp_addr
= 0;
923 info
->td_death_bp_addr
= 0;
927 check_thread_signals (void)
929 #ifdef GET_THREAD_SIGNALS
935 GET_THREAD_SIGNALS (&mask
);
936 sigemptyset (&thread_stop_set
);
937 sigemptyset (&thread_print_set
);
939 for (i
= 1; i
< NSIG
; i
++)
941 if (sigismember (&mask
, i
))
943 if (signal_stop_update (target_signal_from_host (i
), 0))
944 sigaddset (&thread_stop_set
, i
);
945 if (signal_print_update (target_signal_from_host (i
), 0))
946 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)
962 static void *last_loaded
;
964 /* Do nothing if we couldn't load libthread_db.so.1. */
965 if (!thread_db_load ())
970 thread_db_new_objfile (struct objfile
*objfile
)
972 /* This observer must always be called with inferior_ptid set
976 check_for_thread_db ();
979 /* Attach to a new thread. This function is called when we receive a
980 TD_CREATE event or when we iterate over all threads and find one
981 that wasn't already in our list. Returns true on success. */
984 attach_thread (ptid_t ptid
, const td_thrhandle_t
*th_p
,
985 const td_thrinfo_t
*ti_p
)
987 struct private_thread_info
*private;
988 struct thread_info
*tp
= NULL
;
990 struct thread_db_info
*info
;
992 /* If we're being called after a TD_CREATE event, we may already
993 know about this thread. There are two ways this can happen. We
994 may have iterated over all threads between the thread creation
995 and the TD_CREATE event, for instance when the user has issued
996 the `info threads' command before the SIGTRAP for hitting the
997 thread creation breakpoint was reported. Alternatively, the
998 thread may have exited and a new one been created with the same
999 thread ID. In the first case we don't need to do anything; in
1000 the second case we should discard information about the dead
1001 thread and attach to the new one. */
1002 if (in_thread_list (ptid
))
1004 tp
= find_thread_ptid (ptid
);
1005 gdb_assert (tp
!= NULL
);
1007 /* If tp->private is NULL, then GDB is already attached to this
1008 thread, but we do not know anything about it. We can learn
1009 about it here. This can only happen if we have some other
1010 way besides libthread_db to notice new threads (i.e.
1011 PTRACE_EVENT_CLONE); assume the same mechanism notices thread
1012 exit, so this can not be a stale thread recreated with the
1014 if (tp
->private != NULL
)
1016 if (!tp
->private->dying
)
1019 delete_thread (ptid
);
1024 check_thread_signals ();
1026 if (ti_p
->ti_state
== TD_THR_UNKNOWN
|| ti_p
->ti_state
== TD_THR_ZOMBIE
)
1027 return 0; /* A zombie thread -- do not attach. */
1029 /* Under GNU/Linux, we have to attach to each and every thread. */
1031 && lin_lwp_attach_lwp (BUILD_LWP (ti_p
->ti_lid
, GET_PID (ptid
))) < 0)
1034 /* Construct the thread's private data. */
1035 private = xmalloc (sizeof (struct private_thread_info
));
1036 memset (private, 0, sizeof (struct private_thread_info
));
1038 /* A thread ID of zero may mean the thread library has not initialized
1039 yet. But we shouldn't even get here if that's the case. FIXME:
1040 if we change GDB to always have at least one thread in the thread
1041 list this will have to go somewhere else; maybe private == NULL
1042 until the thread_db target claims it. */
1043 gdb_assert (ti_p
->ti_tid
!= 0);
1044 private->th
= *th_p
;
1045 private->tid
= ti_p
->ti_tid
;
1047 /* Add the thread to GDB's thread list. */
1049 tp
= add_thread_with_info (ptid
, private);
1051 tp
->private = private;
1053 info
= get_thread_db_info (GET_PID (ptid
));
1055 /* Enable thread event reporting for this thread. */
1056 err
= info
->td_thr_event_enable_p (th_p
, 1);
1058 error (_("Cannot enable thread event reporting for %s: %s"),
1059 target_pid_to_str (ptid
), thread_db_err_str (err
));
1064 detach_thread (ptid_t ptid
)
1066 struct thread_info
*thread_info
;
1068 /* Don't delete the thread now, because it still reports as active
1069 until it has executed a few instructions after the event
1070 breakpoint - if we deleted it now, "info threads" would cause us
1071 to re-attach to it. Just mark it as having had a TD_DEATH
1072 event. This means that we won't delete it from our thread list
1073 until we notice that it's dead (via prune_threads), or until
1074 something re-uses its thread ID. We'll report the thread exit
1075 when the underlying LWP dies. */
1076 thread_info
= find_thread_ptid (ptid
);
1077 gdb_assert (thread_info
!= NULL
&& thread_info
->private != NULL
);
1078 thread_info
->private->dying
= 1;
1082 thread_db_detach (struct target_ops
*ops
, char *args
, int from_tty
)
1084 struct target_ops
*target_beneath
= find_target_beneath (ops
);
1085 struct thread_db_info
*info
;
1087 info
= get_thread_db_info (GET_PID (inferior_ptid
));
1091 disable_thread_event_reporting ();
1093 /* Delete the old thread event breakpoints. Note that unlike
1094 when mourning, we can remove them here because there's still
1095 a live inferior to poke at. In any case, GDB will not try to
1096 insert anything in the inferior when removing a
1098 remove_thread_event_breakpoints ();
1100 delete_thread_db_info (GET_PID (inferior_ptid
));
1103 target_beneath
->to_detach (target_beneath
, args
, from_tty
);
1105 /* NOTE: From this point on, inferior_ptid is null_ptid. */
1107 /* If there are no more processes using libpthread, detach the
1108 thread_db target ops. */
1109 if (!thread_db_list
)
1110 unpush_target (&thread_db_ops
);
1113 /* Check if PID is currently stopped at the location of a thread event
1114 breakpoint location. If it is, read the event message and act upon
1118 check_event (ptid_t ptid
)
1120 struct regcache
*regcache
= get_thread_regcache (ptid
);
1121 struct gdbarch
*gdbarch
= get_regcache_arch (regcache
);
1127 struct thread_db_info
*info
;
1129 info
= get_thread_db_info (GET_PID (ptid
));
1131 /* Bail out early if we're not at a thread event breakpoint. */
1132 stop_pc
= regcache_read_pc (regcache
)
1133 - gdbarch_decr_pc_after_break (gdbarch
);
1134 if (stop_pc
!= info
->td_create_bp_addr
1135 && stop_pc
!= info
->td_death_bp_addr
)
1138 /* Access an lwp we know is stopped. */
1139 info
->proc_handle
.ptid
= ptid
;
1141 /* If we have only looked at the first thread before libpthread was
1142 initialized, we may not know its thread ID yet. Make sure we do
1143 before we add another thread to the list. */
1144 if (!have_threads (ptid
))
1145 thread_db_find_new_threads_1 (ptid
);
1147 /* If we are at a create breakpoint, we do not know what new lwp
1148 was created and cannot specifically locate the event message for it.
1149 We have to call td_ta_event_getmsg() to get
1150 the latest message. Since we have no way of correlating whether
1151 the event message we get back corresponds to our breakpoint, we must
1152 loop and read all event messages, processing them appropriately.
1153 This guarantees we will process the correct message before continuing
1154 from the breakpoint.
1156 Currently, death events are not enabled. If they are enabled,
1157 the death event can use the td_thr_event_getmsg() interface to
1158 get the message specifically for that lwp and avoid looping
1165 err
= info
->td_ta_event_getmsg_p (info
->thread_agent
, &msg
);
1168 if (err
== TD_NOMSG
)
1171 error (_("Cannot get thread event message: %s"),
1172 thread_db_err_str (err
));
1175 err
= info
->td_thr_get_info_p (msg
.th_p
, &ti
);
1177 error (_("Cannot get thread info: %s"), thread_db_err_str (err
));
1179 ptid
= ptid_build (GET_PID (ptid
), ti
.ti_lid
, 0);
1184 /* Call attach_thread whether or not we already know about a
1185 thread with this thread ID. */
1186 attach_thread (ptid
, msg
.th_p
, &ti
);
1192 if (!in_thread_list (ptid
))
1193 error (_("Spurious thread death event."));
1195 detach_thread (ptid
);
1200 error (_("Spurious thread event."));
1207 thread_db_wait (struct target_ops
*ops
,
1208 ptid_t ptid
, struct target_waitstatus
*ourstatus
,
1211 struct thread_db_info
*info
;
1212 struct target_ops
*beneath
= find_target_beneath (ops
);
1214 ptid
= beneath
->to_wait (beneath
, ptid
, ourstatus
, options
);
1216 if (ourstatus
->kind
== TARGET_WAITKIND_IGNORE
)
1219 if (ourstatus
->kind
== TARGET_WAITKIND_EXITED
1220 || ourstatus
->kind
== TARGET_WAITKIND_SIGNALLED
)
1223 info
= get_thread_db_info (GET_PID (ptid
));
1225 /* If this process isn't using thread_db, we're done. */
1229 if (ourstatus
->kind
== TARGET_WAITKIND_EXECD
)
1231 /* New image, it may or may not end up using thread_db. Assume
1232 not unless we find otherwise. */
1233 delete_thread_db_info (GET_PID (ptid
));
1234 if (!thread_db_list
)
1235 unpush_target (&thread_db_ops
);
1237 /* Thread event breakpoints are deleted by
1238 update_breakpoints_after_exec. */
1243 /* If we do not know about the main thread yet, this would be a good time to
1245 if (ourstatus
->kind
== TARGET_WAITKIND_STOPPED
&& !have_threads (ptid
))
1246 thread_db_find_new_threads_1 (ptid
);
1248 if (ourstatus
->kind
== TARGET_WAITKIND_STOPPED
1249 && ourstatus
->value
.sig
== TARGET_SIGNAL_TRAP
)
1250 /* Check for a thread event. */
1253 if (have_threads (ptid
))
1255 /* Change ptids back into the higher level PID + TID format. If
1256 the thread is dead and no longer on the thread list, we will
1257 get back a dead ptid. This can occur if the thread death
1258 event gets postponed by other simultaneous events. In such a
1259 case, we want to just ignore the event and continue on. */
1261 ptid
= thread_from_lwp (ptid
);
1262 if (GET_PID (ptid
) == -1)
1263 ourstatus
->kind
= TARGET_WAITKIND_SPURIOUS
;
1270 thread_db_mourn_inferior (struct target_ops
*ops
)
1272 struct target_ops
*target_beneath
= find_target_beneath (ops
);
1274 delete_thread_db_info (GET_PID (inferior_ptid
));
1276 target_beneath
->to_mourn_inferior (target_beneath
);
1278 /* Delete the old thread event breakpoints. Do this after mourning
1279 the inferior, so that we don't try to uninsert them. */
1280 remove_thread_event_breakpoints ();
1282 /* Detach thread_db target ops. */
1283 if (!thread_db_list
)
1284 unpush_target (ops
);
1287 struct callback_data
1289 struct thread_db_info
*info
;
1294 find_new_threads_callback (const td_thrhandle_t
*th_p
, void *data
)
1299 struct thread_info
*tp
;
1300 struct callback_data
*cb_data
= data
;
1301 struct thread_db_info
*info
= cb_data
->info
;
1303 err
= info
->td_thr_get_info_p (th_p
, &ti
);
1305 error (_("find_new_threads_callback: cannot get thread info: %s"),
1306 thread_db_err_str (err
));
1308 if (ti
.ti_state
== TD_THR_UNKNOWN
|| ti
.ti_state
== TD_THR_ZOMBIE
)
1309 return 0; /* A zombie -- ignore. */
1313 /* A thread ID of zero means that this is the main thread, but
1314 glibc has not yet initialized thread-local storage and the
1315 pthread library. We do not know what the thread's TID will
1316 be yet. Just enable event reporting and otherwise ignore
1319 /* In that case, we're not stopped in a fork syscall and don't
1320 need this glibc bug workaround. */
1321 info
->need_stale_parent_threads_check
= 0;
1323 err
= info
->td_thr_event_enable_p (th_p
, 1);
1325 error (_("Cannot enable thread event reporting for LWP %d: %s"),
1326 (int) ti
.ti_lid
, thread_db_err_str (err
));
1331 /* Ignore stale parent threads, caused by glibc/BZ5983. This is a
1332 bit expensive, as it needs to open /proc/pid/status, so try to
1333 avoid doing the work if we know we don't have to. */
1334 if (info
->need_stale_parent_threads_check
)
1336 int tgid
= linux_proc_get_tgid (ti
.ti_lid
);
1337 if (tgid
!= -1 && tgid
!= info
->pid
)
1341 ptid
= ptid_build (info
->pid
, ti
.ti_lid
, 0);
1342 tp
= find_thread_ptid (ptid
);
1343 if (tp
== NULL
|| tp
->private == NULL
)
1345 if (attach_thread (ptid
, th_p
, &ti
))
1346 cb_data
->new_threads
+= 1;
1348 /* Problem attaching this thread; perhaps it exited before we
1350 This could mean that the thread list inside glibc itself is in
1351 inconsistent state, and libthread_db could go on looping forever
1352 (observed with glibc-2.3.6). To prevent that, terminate
1353 iteration: thread_db_find_new_threads_2 will retry. */
1360 /* Helper for thread_db_find_new_threads_2.
1361 Returns number of new threads found. */
1364 find_new_threads_once (struct thread_db_info
*info
, int iteration
,
1367 volatile struct gdb_exception except
;
1368 struct callback_data data
;
1372 data
.new_threads
= 0;
1374 TRY_CATCH (except
, RETURN_MASK_ERROR
)
1376 /* Iterate over all user-space threads to discover new threads. */
1377 err
= info
->td_ta_thr_iter_p (info
->thread_agent
,
1378 find_new_threads_callback
,
1381 TD_THR_LOWEST_PRIORITY
,
1383 TD_THR_ANY_USER_FLAGS
);
1388 if (except
.reason
< 0)
1389 exception_fprintf (gdb_stderr
, except
,
1390 "Warning: find_new_threads_once: ");
1392 printf_filtered (_("Found %d new threads in iteration %d.\n"),
1393 data
.new_threads
, iteration
);
1399 return data
.new_threads
;
1402 /* Search for new threads, accessing memory through stopped thread
1403 PTID. If UNTIL_NO_NEW is true, repeat searching until several
1404 searches in a row do not discover any new threads. */
1407 thread_db_find_new_threads_2 (ptid_t ptid
, int until_no_new
)
1410 struct lwp_info
*lp
;
1411 struct thread_db_info
*info
;
1412 int pid
= ptid_get_pid (ptid
);
1415 /* In linux, we can only read memory through a stopped lwp. */
1417 if (lp
->stopped
&& ptid_get_pid (lp
->ptid
) == pid
)
1421 /* There is no stopped thread. Bail out. */
1424 info
= get_thread_db_info (GET_PID (ptid
));
1426 /* Access an lwp we know is stopped. */
1427 info
->proc_handle
.ptid
= ptid
;
1431 /* Require 4 successive iterations which do not find any new threads.
1432 The 4 is a heuristic: there is an inherent race here, and I have
1433 seen that 2 iterations in a row are not always sufficient to
1434 "capture" all threads. */
1435 for (i
= 0, loop
= 0; loop
< 4; ++i
, ++loop
)
1436 if (find_new_threads_once (info
, i
, NULL
) != 0)
1437 /* Found some new threads. Restart the loop from beginning. */
1444 find_new_threads_once (info
, 0, &err
);
1446 error (_("Cannot find new threads: %s"), thread_db_err_str (err
));
1451 thread_db_find_new_threads_1 (ptid_t ptid
)
1453 thread_db_find_new_threads_2 (ptid
, 0);
1458 thread_db_find_new_threads (struct target_ops
*ops
)
1460 struct thread_db_info
*info
;
1462 info
= get_thread_db_info (GET_PID (inferior_ptid
));
1467 thread_db_find_new_threads_1 (inferior_ptid
);
1471 thread_db_pid_to_str (struct target_ops
*ops
, ptid_t ptid
)
1473 struct thread_info
*thread_info
= find_thread_ptid (ptid
);
1474 struct target_ops
*beneath
;
1476 if (thread_info
!= NULL
&& thread_info
->private != NULL
)
1478 static char buf
[64];
1481 tid
= thread_info
->private->tid
;
1482 snprintf (buf
, sizeof (buf
), "Thread 0x%lx (LWP %ld)",
1483 tid
, GET_LWP (ptid
));
1488 beneath
= find_target_beneath (ops
);
1489 if (beneath
->to_pid_to_str (beneath
, ptid
))
1490 return beneath
->to_pid_to_str (beneath
, ptid
);
1492 return normal_pid_to_str (ptid
);
1495 /* Return a string describing the state of the thread specified by
1499 thread_db_extra_thread_info (struct thread_info
*info
)
1501 if (info
->private == NULL
)
1504 if (info
->private->dying
)
1510 /* Get the address of the thread local variable in load module LM which
1511 is stored at OFFSET within the thread local storage for thread PTID. */
1514 thread_db_get_thread_local_address (struct target_ops
*ops
,
1519 struct thread_info
*thread_info
;
1520 struct target_ops
*beneath
;
1522 /* If we have not discovered any threads yet, check now. */
1523 if (!have_threads (ptid
))
1524 thread_db_find_new_threads_1 (ptid
);
1526 /* Find the matching thread. */
1527 thread_info
= find_thread_ptid (ptid
);
1529 if (thread_info
!= NULL
&& thread_info
->private != NULL
)
1533 struct thread_db_info
*info
;
1535 info
= get_thread_db_info (GET_PID (ptid
));
1537 /* glibc doesn't provide the needed interface. */
1538 if (!info
->td_thr_tls_get_addr_p
)
1539 throw_error (TLS_NO_LIBRARY_SUPPORT_ERROR
,
1540 _("No TLS library support"));
1542 /* Caller should have verified that lm != 0. */
1543 gdb_assert (lm
!= 0);
1545 /* Finally, get the address of the variable. */
1546 err
= info
->td_thr_tls_get_addr_p (&thread_info
->private->th
,
1547 (void *)(size_t) lm
,
1550 #ifdef THREAD_DB_HAS_TD_NOTALLOC
1551 /* The memory hasn't been allocated, yet. */
1552 if (err
== TD_NOTALLOC
)
1553 /* Now, if libthread_db provided the initialization image's
1554 address, we *could* try to build a non-lvalue value from
1555 the initialization image. */
1556 throw_error (TLS_NOT_ALLOCATED_YET_ERROR
,
1557 _("TLS not allocated yet"));
1560 /* Something else went wrong. */
1562 throw_error (TLS_GENERIC_ERROR
,
1563 (("%s")), thread_db_err_str (err
));
1565 /* Cast assuming host == target. Joy. */
1566 /* Do proper sign extension for the target. */
1567 gdb_assert (exec_bfd
);
1568 return (bfd_get_sign_extend_vma (exec_bfd
) > 0
1569 ? (CORE_ADDR
) (intptr_t) address
1570 : (CORE_ADDR
) (uintptr_t) address
);
1573 beneath
= find_target_beneath (ops
);
1574 if (beneath
->to_get_thread_local_address
)
1575 return beneath
->to_get_thread_local_address (beneath
, ptid
, lm
, offset
);
1577 throw_error (TLS_GENERIC_ERROR
,
1578 _("TLS not supported on this target"));
1581 /* Callback routine used to find a thread based on the TID part of
1585 thread_db_find_thread_from_tid (struct thread_info
*thread
, void *data
)
1587 long *tid
= (long *) data
;
1589 if (thread
->private->tid
== *tid
)
1595 /* Implement the to_get_ada_task_ptid target method for this target. */
1598 thread_db_get_ada_task_ptid (long lwp
, long thread
)
1600 struct thread_info
*thread_info
;
1602 thread_db_find_new_threads_1 (inferior_ptid
);
1603 thread_info
= iterate_over_threads (thread_db_find_thread_from_tid
, &thread
);
1605 gdb_assert (thread_info
!= NULL
);
1607 return (thread_info
->ptid
);
1611 thread_db_resume (struct target_ops
*ops
,
1612 ptid_t ptid
, int step
, enum target_signal signo
)
1614 struct target_ops
*beneath
= find_target_beneath (ops
);
1615 struct thread_db_info
*info
;
1617 if (ptid_equal (ptid
, minus_one_ptid
))
1618 info
= get_thread_db_info (GET_PID (inferior_ptid
));
1620 info
= get_thread_db_info (GET_PID (ptid
));
1622 /* This workaround is only needed for child fork lwps stopped in a
1623 PTRACE_O_TRACEFORK event. When the inferior is resumed, the
1624 workaround can be disabled. */
1626 info
->need_stale_parent_threads_check
= 0;
1628 beneath
->to_resume (beneath
, ptid
, step
, signo
);
1632 init_thread_db_ops (void)
1634 thread_db_ops
.to_shortname
= "multi-thread";
1635 thread_db_ops
.to_longname
= "multi-threaded child process.";
1636 thread_db_ops
.to_doc
= "Threads and pthreads support.";
1637 thread_db_ops
.to_detach
= thread_db_detach
;
1638 thread_db_ops
.to_wait
= thread_db_wait
;
1639 thread_db_ops
.to_resume
= thread_db_resume
;
1640 thread_db_ops
.to_mourn_inferior
= thread_db_mourn_inferior
;
1641 thread_db_ops
.to_find_new_threads
= thread_db_find_new_threads
;
1642 thread_db_ops
.to_pid_to_str
= thread_db_pid_to_str
;
1643 thread_db_ops
.to_stratum
= thread_stratum
;
1644 thread_db_ops
.to_has_thread_control
= tc_schedlock
;
1645 thread_db_ops
.to_get_thread_local_address
1646 = thread_db_get_thread_local_address
;
1647 thread_db_ops
.to_extra_thread_info
= thread_db_extra_thread_info
;
1648 thread_db_ops
.to_get_ada_task_ptid
= thread_db_get_ada_task_ptid
;
1649 thread_db_ops
.to_magic
= OPS_MAGIC
;
1652 /* Provide a prototype to silence -Wmissing-prototypes. */
1653 extern initialize_file_ftype _initialize_thread_db
;
1656 _initialize_thread_db (void)
1658 init_thread_db_ops ();
1659 add_target (&thread_db_ops
);
1661 /* Defer loading of libthread_db.so until inferior is running.
1662 This allows gdb to load correct libthread_db for a given
1663 executable -- there could be mutiple versions of glibc,
1664 compiled with LinuxThreads or NPTL, and until there is
1665 a running inferior, we can't tell which libthread_db is
1666 the correct one to load. */
1668 libthread_db_search_path
= xstrdup (LIBTHREAD_DB_SEARCH_PATH
);
1670 add_setshow_optional_filename_cmd ("libthread-db-search-path",
1672 &libthread_db_search_path
, _("\
1673 Set search path for libthread_db."), _("\
1674 Show the current search path or libthread_db."), _("\
1675 This path is used to search for libthread_db to be loaded into \
1679 &setlist
, &showlist
);
1680 /* Add ourselves to objfile event chain. */
1681 observer_attach_new_objfile (thread_db_new_objfile
);