1 /* libthread_db assisted debugging support, generic parts.
3 Copyright (C) 1999-2018 Free Software Foundation, Inc.
5 This file is part of GDB.
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>. */
22 #include "gdb_proc_service.h"
23 #include "nat/gdb_thread_db.h"
28 #include "gdbthread.h"
36 #include "solib-svr4.h"
38 #include "observable.h"
39 #include "linux-nat.h"
40 #include "nat/linux-procfs.h"
41 #include "nat/linux-ptrace.h"
42 #include "nat/linux-osdata.h"
43 #include "auto-load.h"
44 #include "cli/cli-utils.h"
47 #include "nat/linux-namespaces.h"
49 #include "common/pathstuff.h"
51 /* GNU/Linux libthread_db support.
53 libthread_db is a library, provided along with libpthread.so, which
54 exposes the internals of the thread library to a debugger. It
55 allows GDB to find existing threads, new threads as they are
56 created, thread IDs (usually, the result of pthread_self), and
57 thread-local variables.
59 The libthread_db interface originates on Solaris, where it is both
60 more powerful and more complicated. This implementation only works
61 for NPTL, the glibc threading library. It assumes that each thread
62 is permanently assigned to a single light-weight process (LWP). At
63 some point it also supported the older LinuxThreads library, but it
66 libthread_db-specific information is stored in the "private" field
67 of struct thread_info. When the field is NULL we do not yet have
68 information about the new thread; this could be temporary (created,
69 but the thread library's data structures do not reflect it yet)
70 or permanent (created using clone instead of pthread_create).
72 Process IDs managed by linux-thread-db.c match those used by
73 linux-nat.c: a common PID for all processes, an LWP ID for each
74 thread, and no TID. We save the TID in private. Keeping it out
75 of the ptid_t prevents thread IDs changing when libpthread is
76 loaded or unloaded. */
78 class thread_db_target final
: public target_ops
83 const char *shortname () override
84 { return "multi-thread"; }
85 const char *longname () override
86 { return _("multi-threaded child process."); }
87 const char *doc () override
88 { return _("Threads and pthreads support."); }
90 void detach (inferior
*, int) override
;
91 ptid_t
wait (ptid_t
, struct target_waitstatus
*, int) override
;
92 void resume (ptid_t
, int, enum gdb_signal
) override
;
93 void mourn_inferior () override
;
94 void update_thread_list () override
;
95 const char *pid_to_str (ptid_t
) override
;
96 CORE_ADDR
get_thread_local_address (ptid_t ptid
,
97 CORE_ADDR load_module_addr
,
98 CORE_ADDR offset
) override
;
99 const char *extra_thread_info (struct thread_info
*) override
;
100 ptid_t
get_ada_task_ptid (long lwp
, long thread
) override
;
102 thread_info
*thread_handle_to_thread_info (const gdb_byte
*thread_handle
,
104 inferior
*inf
) override
;
107 thread_db_target::thread_db_target ()
109 this->to_stratum
= thread_stratum
;
112 static char *libthread_db_search_path
;
114 /* Set to non-zero if thread_db auto-loading is enabled
115 by the "set auto-load libthread-db" command. */
116 static int auto_load_thread_db
= 1;
118 /* "show" command for the auto_load_thread_db configuration variable. */
121 show_auto_load_thread_db (struct ui_file
*file
, int from_tty
,
122 struct cmd_list_element
*c
, const char *value
)
124 fprintf_filtered (file
, _("Auto-loading of inferior specific libthread_db "
130 set_libthread_db_search_path (const char *ignored
, int from_tty
,
131 struct cmd_list_element
*c
)
133 if (*libthread_db_search_path
== '\0')
135 xfree (libthread_db_search_path
);
136 libthread_db_search_path
= xstrdup (LIBTHREAD_DB_SEARCH_PATH
);
140 /* If non-zero, print details of libthread_db processing. */
142 static unsigned int libthread_db_debug
;
145 show_libthread_db_debug (struct ui_file
*file
, int from_tty
,
146 struct cmd_list_element
*c
, const char *value
)
148 fprintf_filtered (file
, _("libthread-db debugging is %s.\n"), value
);
151 /* If we're running on GNU/Linux, we must explicitly attach to any new
154 /* This module's target vector. */
155 static thread_db_target the_thread_db_target
;
157 /* Non-zero if we have determined the signals used by the threads
159 static int thread_signals
;
160 static sigset_t thread_stop_set
;
161 static sigset_t thread_print_set
;
163 struct thread_db_info
165 struct thread_db_info
*next
;
167 /* Process id this object refers to. */
170 /* Handle from dlopen for libthread_db.so. */
173 /* Absolute pathname from gdb_realpath to disk file used for dlopen-ing
174 HANDLE. It may be NULL for system library. */
177 /* Structure that identifies the child process for the
178 <proc_service.h> interface. */
179 struct ps_prochandle proc_handle
;
181 /* Connection to the libthread_db library. */
182 td_thragent_t
*thread_agent
;
184 /* True if we need to apply the workaround for glibc/BZ5983. When
185 we catch a PTRACE_O_TRACEFORK, and go query the child's thread
186 list, nptl_db returns the parent's threads in addition to the new
187 (single) child thread. If this flag is set, we do extra work to
188 be able to ignore such stale entries. */
189 int need_stale_parent_threads_check
;
191 /* Pointers to the libthread_db functions. */
193 td_init_ftype
*td_init_p
;
194 td_ta_new_ftype
*td_ta_new_p
;
195 td_ta_map_lwp2thr_ftype
*td_ta_map_lwp2thr_p
;
196 td_ta_thr_iter_ftype
*td_ta_thr_iter_p
;
197 td_thr_get_info_ftype
*td_thr_get_info_p
;
198 td_thr_tls_get_addr_ftype
*td_thr_tls_get_addr_p
;
199 td_thr_tlsbase_ftype
*td_thr_tlsbase_p
;
202 /* List of known processes using thread_db, and the required
204 struct thread_db_info
*thread_db_list
;
206 static void thread_db_find_new_threads_1 (ptid_t ptid
);
207 static void thread_db_find_new_threads_2 (ptid_t ptid
, int until_no_new
);
209 static void check_thread_signals (void);
211 static struct thread_info
*record_thread
212 (struct thread_db_info
*info
, struct thread_info
*tp
,
213 ptid_t ptid
, const td_thrhandle_t
*th_p
, const td_thrinfo_t
*ti_p
);
215 /* Add the current inferior to the list of processes using libpthread.
216 Return a pointer to the newly allocated object that was added to
217 THREAD_DB_LIST. HANDLE is the handle returned by dlopen'ing
220 static struct thread_db_info
*
221 add_thread_db_info (void *handle
)
223 struct thread_db_info
*info
= XCNEW (struct thread_db_info
);
225 info
->pid
= ptid_get_pid (inferior_ptid
);
226 info
->handle
= handle
;
228 /* The workaround works by reading from /proc/pid/status, so it is
229 disabled for core files. */
230 if (target_has_execution
)
231 info
->need_stale_parent_threads_check
= 1;
233 info
->next
= thread_db_list
;
234 thread_db_list
= info
;
239 /* Return the thread_db_info object representing the bookkeeping
240 related to process PID, if any; NULL otherwise. */
242 static struct thread_db_info
*
243 get_thread_db_info (int pid
)
245 struct thread_db_info
*info
;
247 for (info
= thread_db_list
; info
; info
= info
->next
)
248 if (pid
== info
->pid
)
254 /* When PID has exited or has been detached, we no longer want to keep
255 track of it as using libpthread. Call this function to discard
256 thread_db related info related to PID. Note that this closes
257 LIBTHREAD_DB_SO's dlopen'ed handle. */
260 delete_thread_db_info (int pid
)
262 struct thread_db_info
*info
, *info_prev
;
266 for (info
= thread_db_list
; info
; info_prev
= info
, info
= info
->next
)
267 if (pid
== info
->pid
)
273 if (info
->handle
!= NULL
)
274 dlclose (info
->handle
);
276 xfree (info
->filename
);
279 info_prev
->next
= info
->next
;
281 thread_db_list
= info
->next
;
286 /* Use "struct private_thread_info" to cache thread state. This is
287 a substantial optimization. */
289 struct thread_db_thread_info
: public private_thread_info
291 /* Flag set when we see a TD_DEATH event for this thread. */
294 /* Cached thread state. */
295 td_thrhandle_t th
{};
299 static thread_db_thread_info
*
300 get_thread_db_thread_info (thread_info
*thread
)
302 return static_cast<thread_db_thread_info
*> (thread
->priv
.get ());
306 thread_db_err_str (td_err_e err
)
313 return "generic 'call succeeded'";
315 return "generic error";
317 return "no thread to satisfy query";
319 return "no sync handle to satisfy query";
321 return "no LWP to satisfy query";
323 return "invalid process handle";
325 return "invalid thread handle";
327 return "invalid synchronization handle";
329 return "invalid thread agent";
331 return "invalid key";
333 return "no event message for getmsg";
335 return "FPU register set not available";
337 return "application not linked with libthread";
339 return "requested event is not supported";
341 return "capability not available";
343 return "debugger service failed";
345 return "operation not applicable to";
347 return "no thread-specific data for this thread";
349 return "malloc failed";
351 return "only part of register set was written/read";
353 return "X register set not available for this thread";
354 #ifdef THREAD_DB_HAS_TD_NOTALLOC
356 return "thread has not yet allocated TLS for given module";
358 #ifdef THREAD_DB_HAS_TD_VERSION
360 return "versions of libpthread and libthread_db do not match";
362 #ifdef THREAD_DB_HAS_TD_NOTLS
364 return "there is no TLS segment in the given module";
367 snprintf (buf
, sizeof (buf
), "unknown thread_db error '%d'", err
);
372 /* Fetch the user-level thread id of PTID. */
374 static struct thread_info
*
375 thread_from_lwp (ptid_t ptid
)
380 struct thread_db_info
*info
;
381 struct thread_info
*tp
;
383 /* Just in case td_ta_map_lwp2thr doesn't initialize it completely. */
386 /* This ptid comes from linux-nat.c, which should always fill in the
388 gdb_assert (ptid_get_lwp (ptid
) != 0);
390 info
= get_thread_db_info (ptid_get_pid (ptid
));
392 /* Access an lwp we know is stopped. */
393 info
->proc_handle
.ptid
= ptid
;
394 err
= info
->td_ta_map_lwp2thr_p (info
->thread_agent
, ptid_get_lwp (ptid
),
397 error (_("Cannot find user-level thread for LWP %ld: %s"),
398 ptid_get_lwp (ptid
), thread_db_err_str (err
));
400 err
= info
->td_thr_get_info_p (&th
, &ti
);
402 error (_("thread_get_info_callback: cannot get thread info: %s"),
403 thread_db_err_str (err
));
405 /* Fill the cache. */
406 tp
= find_thread_ptid (ptid
);
407 return record_thread (info
, tp
, ptid
, &th
, &ti
);
411 /* See linux-nat.h. */
414 thread_db_notice_clone (ptid_t parent
, ptid_t child
)
416 struct thread_db_info
*info
;
418 info
= get_thread_db_info (ptid_get_pid (child
));
423 thread_from_lwp (child
);
425 /* If we do not know about the main thread yet, this would be a good
427 thread_from_lwp (parent
);
432 verbose_dlsym (void *handle
, const char *name
)
434 void *sym
= dlsym (handle
, name
);
436 warning (_("Symbol \"%s\" not found in libthread_db: %s"),
441 /* Verify inferior's '\0'-terminated symbol VER_SYMBOL starts with "%d.%d" and
442 return 1 if this version is lower (and not equal) to
443 VER_MAJOR_MIN.VER_MINOR_MIN. Return 0 in all other cases. */
446 inferior_has_bug (const char *ver_symbol
, int ver_major_min
, int ver_minor_min
)
448 struct bound_minimal_symbol version_msym
;
449 CORE_ADDR version_addr
;
450 gdb::unique_xmalloc_ptr
<char> version
;
451 int err
, got
, retval
= 0;
453 version_msym
= lookup_minimal_symbol (ver_symbol
, NULL
, NULL
);
454 if (version_msym
.minsym
== NULL
)
457 version_addr
= BMSYMBOL_VALUE_ADDRESS (version_msym
);
458 got
= target_read_string (version_addr
, &version
, 32, &err
);
459 if (err
== 0 && memchr (version
.get (), 0, got
) == version
.get () + got
- 1)
463 retval
= (sscanf (version
.get (), "%d.%d", &major
, &minor
) == 2
464 && (major
< ver_major_min
465 || (major
== ver_major_min
&& minor
< ver_minor_min
)));
471 /* Similar as thread_db_find_new_threads_1, but try to silently ignore errors
474 Return 1 if the caller should abort libthread_db initialization. Return 0
478 thread_db_find_new_threads_silently (ptid_t ptid
)
483 thread_db_find_new_threads_2 (ptid
, 1);
486 CATCH (except
, RETURN_MASK_ERROR
)
488 if (libthread_db_debug
)
489 exception_fprintf (gdb_stdlog
, except
,
490 "Warning: thread_db_find_new_threads_silently: ");
492 /* There is a bug fixed between nptl 2.6.1 and 2.7 by
493 commit 7d9d8bd18906fdd17364f372b160d7ab896ce909
494 where calls to td_thr_get_info fail with TD_ERR for statically linked
495 executables if td_thr_get_info is called before glibc has initialized
498 If the nptl bug is NOT present in the inferior and still thread_db
499 reports an error return 1. It means the inferior has corrupted thread
500 list and GDB should fall back only to LWPs.
502 If the nptl bug is present in the inferior return 0 to silently ignore
503 such errors, and let gdb enumerate threads again later. In such case
504 GDB cannot properly display LWPs if the inferior thread list is
505 corrupted. For core files it does not apply, no 'later enumeration'
508 if (!target_has_execution
|| !inferior_has_bug ("nptl_version", 2, 7))
510 exception_fprintf (gdb_stderr
, except
,
511 _("Warning: couldn't activate thread debugging "
512 "using libthread_db: "));
521 /* Lookup a library in which given symbol resides.
522 Note: this is looking in GDB process, not in the inferior.
523 Returns library name, or NULL. */
526 dladdr_to_soname (const void *addr
)
530 if (dladdr (addr
, &info
) != 0)
531 return info
.dli_fname
;
535 /* Attempt to initialize dlopen()ed libthread_db, described by INFO.
537 Failure could happen if libthread_db does not have symbols we expect,
538 or when it refuses to work with the current inferior (e.g. due to
539 version mismatch between libthread_db and libpthread). */
542 try_thread_db_load_1 (struct thread_db_info
*info
)
546 /* Initialize pointers to the dynamic library functions we will use.
547 Essential functions first. */
549 #define TDB_VERBOSE_DLSYM(info, func) \
550 info->func ## _p = (func ## _ftype *) verbose_dlsym (info->handle, #func)
552 #define TDB_DLSYM(info, func) \
553 info->func ## _p = (func ## _ftype *) dlsym (info->handle, #func)
562 CHK (TDB_VERBOSE_DLSYM (info
, td_init
));
564 err
= info
->td_init_p ();
567 warning (_("Cannot initialize libthread_db: %s"),
568 thread_db_err_str (err
));
572 CHK (TDB_VERBOSE_DLSYM (info
, td_ta_new
));
574 /* Initialize the structure that identifies the child process. */
575 info
->proc_handle
.ptid
= inferior_ptid
;
577 /* Now attempt to open a connection to the thread library. */
578 err
= info
->td_ta_new_p (&info
->proc_handle
, &info
->thread_agent
);
581 if (libthread_db_debug
)
582 fprintf_unfiltered (gdb_stdlog
, _("td_ta_new failed: %s\n"),
583 thread_db_err_str (err
));
588 #ifdef THREAD_DB_HAS_TD_VERSION
591 /* The errors above are not unexpected and silently ignored:
592 they just mean we haven't found correct version of
596 warning (_("td_ta_new failed: %s"), thread_db_err_str (err
));
601 /* These are essential. */
602 CHK (TDB_VERBOSE_DLSYM (info
, td_ta_map_lwp2thr
));
603 CHK (TDB_VERBOSE_DLSYM (info
, td_thr_get_info
));
605 /* These are not essential. */
606 TDB_DLSYM (info
, td_thr_tls_get_addr
);
607 TDB_DLSYM (info
, td_thr_tlsbase
);
609 /* It's best to avoid td_ta_thr_iter if possible. That walks data
610 structures in the inferior's address space that may be corrupted,
611 or, if the target is running, may change while we walk them. If
612 there's execution (and /proc is mounted), then we're already
613 attached to all LWPs. Use thread_from_lwp, which uses
614 td_ta_map_lwp2thr instead, which does not walk the thread list.
616 td_ta_map_lwp2thr uses ps_get_thread_area, but we can't use that
617 currently on core targets, as it uses ptrace directly. */
618 if (target_has_execution
619 && linux_proc_task_list_dir_exists (ptid_get_pid (inferior_ptid
)))
620 info
->td_ta_thr_iter_p
= NULL
;
622 CHK (TDB_VERBOSE_DLSYM (info
, td_ta_thr_iter
));
624 #undef TDB_VERBOSE_DLSYM
628 if (info
->td_ta_thr_iter_p
== NULL
)
631 int pid
= ptid_get_pid (inferior_ptid
);
633 linux_stop_and_wait_all_lwps ();
636 if (ptid_get_pid (lp
->ptid
) == pid
)
637 thread_from_lwp (lp
->ptid
);
639 linux_unstop_all_lwps ();
641 else if (thread_db_find_new_threads_silently (inferior_ptid
) != 0)
643 /* Even if libthread_db initializes, if the thread list is
644 corrupted, we'd not manage to list any threads. Better reject this
645 thread_db, and fall back to at least listing LWPs. */
649 printf_unfiltered (_("[Thread debugging using libthread_db enabled]\n"));
651 if (*libthread_db_search_path
|| libthread_db_debug
)
653 struct ui_file
*file
;
656 library
= dladdr_to_soname ((const void *) *info
->td_ta_new_p
);
658 library
= LIBTHREAD_DB_SO
;
660 /* If we'd print this to gdb_stdout when debug output is
661 disabled, still print it to gdb_stdout if debug output is
662 enabled. User visible output should not depend on debug
664 file
= *libthread_db_search_path
!= '\0' ? gdb_stdout
: gdb_stdlog
;
665 fprintf_unfiltered (file
, _("Using host libthread_db library \"%s\".\n"),
669 /* The thread library was detected. Activate the thread_db target
670 if this is the first process using it. */
671 if (thread_db_list
->next
== NULL
)
672 push_target (&the_thread_db_target
);
677 /* Attempt to use LIBRARY as libthread_db. LIBRARY could be absolute,
678 relative, or just LIBTHREAD_DB. */
681 try_thread_db_load (const char *library
, int check_auto_load_safe
)
684 struct thread_db_info
*info
;
686 if (libthread_db_debug
)
687 fprintf_unfiltered (gdb_stdlog
,
688 _("Trying host libthread_db library: %s.\n"),
691 if (check_auto_load_safe
)
693 if (access (library
, R_OK
) != 0)
695 /* Do not print warnings by file_is_auto_load_safe if the library does
696 not exist at this place. */
697 if (libthread_db_debug
)
698 fprintf_unfiltered (gdb_stdlog
, _("open failed: %s.\n"),
699 safe_strerror (errno
));
703 if (!file_is_auto_load_safe (library
, _("auto-load: Loading libthread-db "
704 "library \"%s\" from explicit "
710 handle
= dlopen (library
, RTLD_NOW
);
713 if (libthread_db_debug
)
714 fprintf_unfiltered (gdb_stdlog
, _("dlopen failed: %s.\n"), dlerror ());
718 if (libthread_db_debug
&& strchr (library
, '/') == NULL
)
722 td_init
= dlsym (handle
, "td_init");
725 const char *const libpath
= dladdr_to_soname (td_init
);
728 fprintf_unfiltered (gdb_stdlog
, _("Host %s resolved to: %s.\n"),
733 info
= add_thread_db_info (handle
);
735 /* Do not save system library name, that one is always trusted. */
736 if (strchr (library
, '/') != NULL
)
737 info
->filename
= gdb_realpath (library
).release ();
739 if (try_thread_db_load_1 (info
))
742 /* This library "refused" to work on current inferior. */
743 delete_thread_db_info (ptid_get_pid (inferior_ptid
));
747 /* Subroutine of try_thread_db_load_from_pdir to simplify it.
748 Try loading libthread_db in directory(OBJ)/SUBDIR.
749 SUBDIR may be NULL. It may also be something like "../lib64".
750 The result is true for success. */
753 try_thread_db_load_from_pdir_1 (struct objfile
*obj
, const char *subdir
)
755 const char *obj_name
= objfile_name (obj
);
757 if (obj_name
[0] != '/')
759 warning (_("Expected absolute pathname for libpthread in the"
760 " inferior, but got %s."), obj_name
);
764 std::string path
= obj_name
;
765 size_t cp
= path
.rfind ('/');
766 /* This should at minimum hit the first character. */
767 gdb_assert (cp
!= std::string::npos
);
768 path
.resize (cp
+ 1);
770 path
= path
+ subdir
+ "/";
771 path
+= LIBTHREAD_DB_SO
;
773 return try_thread_db_load (path
.c_str (), 1);
776 /* Handle $pdir in libthread-db-search-path.
777 Look for libthread_db in directory(libpthread)/SUBDIR.
778 SUBDIR may be NULL. It may also be something like "../lib64".
779 The result is true for success. */
782 try_thread_db_load_from_pdir (const char *subdir
)
786 if (!auto_load_thread_db
)
790 if (libpthread_name_p (objfile_name (obj
)))
792 if (try_thread_db_load_from_pdir_1 (obj
, subdir
))
795 /* We may have found the separate-debug-info version of
796 libpthread, and it may live in a directory without a matching
798 if (obj
->separate_debug_objfile_backlink
!= NULL
)
799 return try_thread_db_load_from_pdir_1 (obj
->separate_debug_objfile_backlink
,
808 /* Handle $sdir in libthread-db-search-path.
809 Look for libthread_db in the system dirs, or wherever a plain
810 dlopen(file_without_path) will look.
811 The result is true for success. */
814 try_thread_db_load_from_sdir (void)
816 return try_thread_db_load (LIBTHREAD_DB_SO
, 0);
819 /* Try to load libthread_db from directory DIR of length DIR_LEN.
820 The result is true for success. */
823 try_thread_db_load_from_dir (const char *dir
, size_t dir_len
)
825 if (!auto_load_thread_db
)
828 std::string path
= std::string (dir
, dir_len
) + "/" + LIBTHREAD_DB_SO
;
830 return try_thread_db_load (path
.c_str (), 1);
833 /* Search libthread_db_search_path for libthread_db which "agrees"
834 to work on current inferior.
835 The result is true for success. */
838 thread_db_load_search (void)
842 std::vector
<gdb::unique_xmalloc_ptr
<char>> dir_vec
843 = dirnames_to_char_ptr_vec (libthread_db_search_path
);
845 for (const gdb::unique_xmalloc_ptr
<char> &this_dir_up
: dir_vec
)
847 const char *this_dir
= this_dir_up
.get ();
848 const int pdir_len
= sizeof ("$pdir") - 1;
851 this_dir_len
= strlen (this_dir
);
853 if (strncmp (this_dir
, "$pdir", pdir_len
) == 0
854 && (this_dir
[pdir_len
] == '\0'
855 || this_dir
[pdir_len
] == '/'))
857 const char *subdir
= NULL
;
859 std::string subdir_holder
;
860 if (this_dir
[pdir_len
] == '/')
862 subdir_holder
= std::string (this_dir
+ pdir_len
+ 1);
863 subdir
= subdir_holder
.c_str ();
865 rc
= try_thread_db_load_from_pdir (subdir
);
869 else if (strcmp (this_dir
, "$sdir") == 0)
871 if (try_thread_db_load_from_sdir ())
879 if (try_thread_db_load_from_dir (this_dir
, this_dir_len
))
887 if (libthread_db_debug
)
888 fprintf_unfiltered (gdb_stdlog
,
889 _("thread_db_load_search returning %d\n"), rc
);
893 /* Return non-zero if the inferior has a libpthread. */
896 has_libpthread (void)
901 if (libpthread_name_p (objfile_name (obj
)))
907 /* Attempt to load and initialize libthread_db.
908 Return 1 on success. */
911 thread_db_load (void)
913 struct thread_db_info
*info
;
915 info
= get_thread_db_info (ptid_get_pid (inferior_ptid
));
920 /* Don't attempt to use thread_db on executables not running
922 if (!target_has_registers
)
925 /* Don't attempt to use thread_db for remote targets. */
926 if (!(target_can_run () || core_bfd
))
929 if (thread_db_load_search ())
932 /* We couldn't find a libthread_db.
933 If the inferior has a libpthread warn the user. */
934 if (has_libpthread ())
936 warning (_("Unable to find libthread_db matching inferior's thread"
937 " library, thread debugging will not be available."));
941 /* Either this executable isn't using libpthread at all, or it is
942 statically linked. Since we can't easily distinguish these two cases,
943 no warning is issued. */
948 check_thread_signals (void)
955 lin_thread_get_thread_signals (&mask
);
956 sigemptyset (&thread_stop_set
);
957 sigemptyset (&thread_print_set
);
959 for (i
= 1; i
< NSIG
; i
++)
961 if (sigismember (&mask
, i
))
963 if (signal_stop_update (gdb_signal_from_host (i
), 0))
964 sigaddset (&thread_stop_set
, i
);
965 if (signal_print_update (gdb_signal_from_host (i
), 0))
966 sigaddset (&thread_print_set
, i
);
973 /* Check whether thread_db is usable. This function is called when
974 an inferior is created (or otherwise acquired, e.g. attached to)
975 and when new shared libraries are loaded into a running process. */
978 check_for_thread_db (void)
980 /* Do nothing if we couldn't load libthread_db.so.1. */
981 if (!thread_db_load ())
985 /* This function is called via the new_objfile observer. */
988 thread_db_new_objfile (struct objfile
*objfile
)
990 /* This observer must always be called with inferior_ptid set
994 /* libpthread with separate debug info has its debug info file already
995 loaded (and notified without successful thread_db initialization)
996 the time gdb::observers::new_objfile.notify is called for the library itself.
997 Static executables have their separate debug info loaded already
998 before the inferior has started. */
999 && objfile
->separate_debug_objfile_backlink
== NULL
1000 /* Only check for thread_db if we loaded libpthread,
1001 or if this is the main symbol file.
1002 We need to check OBJF_MAINLINE to handle the case of debugging
1003 a statically linked executable AND the symbol file is specified AFTER
1004 the exec file is loaded (e.g., gdb -c core ; file foo).
1005 For dynamically linked executables, libpthread can be near the end
1006 of the list of shared libraries to load, and in an app of several
1007 thousand shared libraries, this can otherwise be painful. */
1008 && ((objfile
->flags
& OBJF_MAINLINE
) != 0
1009 || libpthread_name_p (objfile_name (objfile
))))
1010 check_for_thread_db ();
1014 check_pid_namespace_match (void)
1016 /* Check is only relevant for local targets targets. */
1017 if (target_can_run ())
1019 /* If the child is in a different PID namespace, its idea of its
1020 PID will differ from our idea of its PID. When we scan the
1021 child's thread list, we'll mistakenly think it has no threads
1022 since the thread PID fields won't match the PID we give to
1024 if (!linux_ns_same (ptid_get_pid (inferior_ptid
), LINUX_NS_PID
))
1026 warning (_ ("Target and debugger are in different PID "
1027 "namespaces; thread lists and other data are "
1028 "likely unreliable. "
1029 "Connect to gdbserver inside the container."));
1034 /* This function is called via the inferior_created observer.
1035 This handles the case of debugging statically linked executables. */
1038 thread_db_inferior_created (struct target_ops
*target
, int from_tty
)
1040 check_pid_namespace_match ();
1041 check_for_thread_db ();
1044 /* Update the thread's state (what's displayed in "info threads"),
1045 from libthread_db thread state information. */
1048 update_thread_state (thread_db_thread_info
*priv
,
1049 const td_thrinfo_t
*ti_p
)
1051 priv
->dying
= (ti_p
->ti_state
== TD_THR_UNKNOWN
1052 || ti_p
->ti_state
== TD_THR_ZOMBIE
);
1055 /* Record a new thread in GDB's thread list. Creates the thread's
1056 private info. If TP is NULL or TP is marked as having exited,
1057 creates a new thread. Otherwise, uses TP. */
1059 static struct thread_info
*
1060 record_thread (struct thread_db_info
*info
,
1061 struct thread_info
*tp
,
1062 ptid_t ptid
, const td_thrhandle_t
*th_p
,
1063 const td_thrinfo_t
*ti_p
)
1065 /* A thread ID of zero may mean the thread library has not
1066 initialized yet. Leave private == NULL until the thread library
1068 if (ti_p
->ti_tid
== 0)
1071 /* Construct the thread's private data. */
1072 thread_db_thread_info
*priv
= new thread_db_thread_info
;
1075 priv
->tid
= ti_p
->ti_tid
;
1076 update_thread_state (priv
, ti_p
);
1078 /* Add the thread to GDB's thread list. If we already know about a
1079 thread with this PTID, but it's marked exited, then the kernel
1080 reused the tid of an old thread. */
1081 if (tp
== NULL
|| tp
->state
== THREAD_EXITED
)
1082 tp
= add_thread_with_info (ptid
, priv
);
1084 tp
->priv
.reset (priv
);
1086 if (target_has_execution
)
1087 check_thread_signals ();
1093 thread_db_target::detach (inferior
*inf
, int from_tty
)
1095 struct target_ops
*target_beneath
= find_target_beneath (this);
1097 delete_thread_db_info (inf
->pid
);
1099 target_beneath
->detach (inf
, from_tty
);
1101 /* NOTE: From this point on, inferior_ptid is null_ptid. */
1103 /* If there are no more processes using libpthread, detach the
1104 thread_db target ops. */
1105 if (!thread_db_list
)
1106 unpush_target (this);
1110 thread_db_target::wait (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
1113 struct thread_db_info
*info
;
1114 struct target_ops
*beneath
= find_target_beneath (this);
1116 ptid
= beneath
->wait (ptid
, ourstatus
, options
);
1118 switch (ourstatus
->kind
)
1120 case TARGET_WAITKIND_IGNORE
:
1121 case TARGET_WAITKIND_EXITED
:
1122 case TARGET_WAITKIND_THREAD_EXITED
:
1123 case TARGET_WAITKIND_SIGNALLED
:
1127 info
= get_thread_db_info (ptid_get_pid (ptid
));
1129 /* If this process isn't using thread_db, we're done. */
1133 if (ourstatus
->kind
== TARGET_WAITKIND_EXECD
)
1135 /* New image, it may or may not end up using thread_db. Assume
1136 not unless we find otherwise. */
1137 delete_thread_db_info (ptid_get_pid (ptid
));
1138 if (!thread_db_list
)
1139 unpush_target (&the_thread_db_target
);
1144 /* Fill in the thread's user-level thread id and status. */
1145 thread_from_lwp (ptid
);
1151 thread_db_target::mourn_inferior ()
1153 struct target_ops
*target_beneath
= find_target_beneath (this);
1155 delete_thread_db_info (ptid_get_pid (inferior_ptid
));
1157 target_beneath
->mourn_inferior ();
1159 /* Detach thread_db target ops. */
1160 if (!thread_db_list
)
1161 unpush_target (&the_thread_db_target
);
1164 struct callback_data
1166 struct thread_db_info
*info
;
1171 find_new_threads_callback (const td_thrhandle_t
*th_p
, void *data
)
1176 struct thread_info
*tp
;
1177 struct callback_data
*cb_data
= (struct callback_data
*) data
;
1178 struct thread_db_info
*info
= cb_data
->info
;
1180 err
= info
->td_thr_get_info_p (th_p
, &ti
);
1182 error (_("find_new_threads_callback: cannot get thread info: %s"),
1183 thread_db_err_str (err
));
1185 if (ti
.ti_lid
== -1)
1187 /* A thread with kernel thread ID -1 is either a thread that
1188 exited and was joined, or a thread that is being created but
1189 hasn't started yet, and that is reusing the tcb/stack of a
1190 thread that previously exited and was joined. (glibc marks
1191 terminated and joined threads with kernel thread ID -1. See
1193 if (libthread_db_debug
)
1194 fprintf_unfiltered (gdb_stdlog
,
1195 "thread_db: skipping exited and "
1196 "joined thread (0x%lx)\n",
1197 (unsigned long) ti
.ti_tid
);
1203 /* A thread ID of zero means that this is the main thread, but
1204 glibc has not yet initialized thread-local storage and the
1205 pthread library. We do not know what the thread's TID will
1208 /* In that case, we're not stopped in a fork syscall and don't
1209 need this glibc bug workaround. */
1210 info
->need_stale_parent_threads_check
= 0;
1215 /* Ignore stale parent threads, caused by glibc/BZ5983. This is a
1216 bit expensive, as it needs to open /proc/pid/status, so try to
1217 avoid doing the work if we know we don't have to. */
1218 if (info
->need_stale_parent_threads_check
)
1220 int tgid
= linux_proc_get_tgid (ti
.ti_lid
);
1222 if (tgid
!= -1 && tgid
!= info
->pid
)
1226 ptid
= ptid_build (info
->pid
, ti
.ti_lid
, 0);
1227 tp
= find_thread_ptid (ptid
);
1228 if (tp
== NULL
|| tp
->priv
== NULL
)
1229 record_thread (info
, tp
, ptid
, th_p
, &ti
);
1234 /* Helper for thread_db_find_new_threads_2.
1235 Returns number of new threads found. */
1238 find_new_threads_once (struct thread_db_info
*info
, int iteration
,
1241 struct callback_data data
;
1242 td_err_e err
= TD_ERR
;
1245 data
.new_threads
= 0;
1247 /* See comment in thread_db_update_thread_list. */
1248 gdb_assert (info
->td_ta_thr_iter_p
!= NULL
);
1252 /* Iterate over all user-space threads to discover new threads. */
1253 err
= info
->td_ta_thr_iter_p (info
->thread_agent
,
1254 find_new_threads_callback
,
1257 TD_THR_LOWEST_PRIORITY
,
1259 TD_THR_ANY_USER_FLAGS
);
1261 CATCH (except
, RETURN_MASK_ERROR
)
1263 if (libthread_db_debug
)
1265 exception_fprintf (gdb_stdlog
, except
,
1266 "Warning: find_new_threads_once: ");
1271 if (libthread_db_debug
)
1273 fprintf_unfiltered (gdb_stdlog
,
1274 _("Found %d new threads in iteration %d.\n"),
1275 data
.new_threads
, iteration
);
1281 return data
.new_threads
;
1284 /* Search for new threads, accessing memory through stopped thread
1285 PTID. If UNTIL_NO_NEW is true, repeat searching until several
1286 searches in a row do not discover any new threads. */
1289 thread_db_find_new_threads_2 (ptid_t ptid
, int until_no_new
)
1291 td_err_e err
= TD_OK
;
1292 struct thread_db_info
*info
;
1295 info
= get_thread_db_info (ptid_get_pid (ptid
));
1297 /* Access an lwp we know is stopped. */
1298 info
->proc_handle
.ptid
= ptid
;
1302 /* Require 4 successive iterations which do not find any new threads.
1303 The 4 is a heuristic: there is an inherent race here, and I have
1304 seen that 2 iterations in a row are not always sufficient to
1305 "capture" all threads. */
1306 for (i
= 0, loop
= 0; loop
< 4 && err
== TD_OK
; ++i
, ++loop
)
1307 if (find_new_threads_once (info
, i
, &err
) != 0)
1309 /* Found some new threads. Restart the loop from beginning. */
1314 find_new_threads_once (info
, 0, &err
);
1317 error (_("Cannot find new threads: %s"), thread_db_err_str (err
));
1321 thread_db_find_new_threads_1 (ptid_t ptid
)
1323 thread_db_find_new_threads_2 (ptid
, 0);
1326 /* Implement the to_update_thread_list target method for this
1330 thread_db_target::update_thread_list ()
1332 struct thread_db_info
*info
;
1333 struct inferior
*inf
;
1339 struct thread_info
*thread
;
1344 info
= get_thread_db_info (inf
->pid
);
1348 thread
= any_live_thread_of_process (inf
->pid
);
1349 if (thread
== NULL
|| thread
->executing
)
1352 /* It's best to avoid td_ta_thr_iter if possible. That walks
1353 data structures in the inferior's address space that may be
1354 corrupted, or, if the target is running, the list may change
1355 while we walk it. In the latter case, it's possible that a
1356 thread exits just at the exact time that causes GDB to get
1357 stuck in an infinite loop. To avoid pausing all threads
1358 whenever the core wants to refresh the thread list, we
1359 instead use thread_from_lwp immediately when we see an LWP
1360 stop. That uses thread_db entry points that do not walk
1361 libpthread's thread list, so should be safe, as well as more
1363 if (target_has_execution_1 (thread
->ptid
))
1366 thread_db_find_new_threads_1 (thread
->ptid
);
1369 /* Give the beneath target a chance to do extra processing. */
1370 this->beneath
->update_thread_list ();
1374 thread_db_target::pid_to_str (ptid_t ptid
)
1376 struct thread_info
*thread_info
= find_thread_ptid (ptid
);
1377 struct target_ops
*beneath
;
1379 if (thread_info
!= NULL
&& thread_info
->priv
!= NULL
)
1381 static char buf
[64];
1382 thread_db_thread_info
*priv
= get_thread_db_thread_info (thread_info
);
1384 snprintf (buf
, sizeof (buf
), "Thread 0x%lx (LWP %ld)",
1385 (unsigned long) priv
->tid
, ptid_get_lwp (ptid
));
1390 beneath
= find_target_beneath (this);
1391 return beneath
->pid_to_str (ptid
);
1394 /* Return a string describing the state of the thread specified by
1398 thread_db_target::extra_thread_info (thread_info
*info
)
1400 if (info
->priv
== NULL
)
1403 thread_db_thread_info
*priv
= get_thread_db_thread_info (info
);
1411 /* Return pointer to the thread_info struct which corresponds to
1412 THREAD_HANDLE (having length HANDLE_LEN). */
1415 thread_db_target::thread_handle_to_thread_info (const gdb_byte
*thread_handle
,
1419 struct thread_info
*tp
;
1420 thread_t handle_tid
;
1422 /* Thread handle sizes must match in order to proceed. We don't use an
1423 assert here because the resulting internal error will cause GDB to
1424 exit. This isn't necessarily an internal error due to the possibility
1425 of garbage being passed as the thread handle via the python interface. */
1426 if (handle_len
!= sizeof (handle_tid
))
1427 error (_("Thread handle size mismatch: %d vs %zu (from libthread_db)"),
1428 handle_len
, sizeof (handle_tid
));
1430 handle_tid
= * (const thread_t
*) thread_handle
;
1432 ALL_NON_EXITED_THREADS (tp
)
1434 thread_db_thread_info
*priv
= get_thread_db_thread_info (tp
);
1436 if (tp
->inf
== inf
&& priv
!= NULL
&& handle_tid
== priv
->tid
)
1443 /* Get the address of the thread local variable in load module LM which
1444 is stored at OFFSET within the thread local storage for thread PTID. */
1447 thread_db_target::get_thread_local_address (ptid_t ptid
,
1451 struct thread_info
*thread_info
;
1452 struct target_ops
*beneath
;
1454 /* Find the matching thread. */
1455 thread_info
= find_thread_ptid (ptid
);
1457 /* We may not have discovered the thread yet. */
1458 if (thread_info
!= NULL
&& thread_info
->priv
== NULL
)
1459 thread_info
= thread_from_lwp (ptid
);
1461 if (thread_info
!= NULL
&& thread_info
->priv
!= NULL
)
1465 thread_db_info
*info
= get_thread_db_info (ptid_get_pid (ptid
));
1466 thread_db_thread_info
*priv
= get_thread_db_thread_info (thread_info
);
1468 /* Finally, get the address of the variable. */
1471 /* glibc doesn't provide the needed interface. */
1472 if (!info
->td_thr_tls_get_addr_p
)
1473 throw_error (TLS_NO_LIBRARY_SUPPORT_ERROR
,
1474 _("No TLS library support"));
1476 /* Note the cast through uintptr_t: this interface only works if
1477 a target address fits in a psaddr_t, which is a host pointer.
1478 So a 32-bit debugger can not access 64-bit TLS through this. */
1479 err
= info
->td_thr_tls_get_addr_p (&priv
->th
,
1480 (psaddr_t
)(uintptr_t) lm
,
1485 /* If glibc doesn't provide the needed interface throw an error
1486 that LM is zero - normally cases it should not be. */
1487 if (!info
->td_thr_tlsbase_p
)
1488 throw_error (TLS_LOAD_MODULE_NOT_FOUND_ERROR
,
1489 _("TLS load module not found"));
1491 /* This code path handles the case of -static -pthread executables:
1492 https://sourceware.org/ml/libc-help/2014-03/msg00024.html
1493 For older GNU libc r_debug.r_map is NULL. For GNU libc after
1494 PR libc/16831 due to GDB PR threads/16954 LOAD_MODULE is also NULL.
1495 The constant number 1 depends on GNU __libc_setup_tls
1496 initialization of l_tls_modid to 1. */
1497 err
= info
->td_thr_tlsbase_p (&priv
->th
, 1, &address
);
1498 address
= (char *) address
+ offset
;
1501 #ifdef THREAD_DB_HAS_TD_NOTALLOC
1502 /* The memory hasn't been allocated, yet. */
1503 if (err
== TD_NOTALLOC
)
1504 /* Now, if libthread_db provided the initialization image's
1505 address, we *could* try to build a non-lvalue value from
1506 the initialization image. */
1507 throw_error (TLS_NOT_ALLOCATED_YET_ERROR
,
1508 _("TLS not allocated yet"));
1511 /* Something else went wrong. */
1513 throw_error (TLS_GENERIC_ERROR
,
1514 (("%s")), thread_db_err_str (err
));
1516 /* Cast assuming host == target. Joy. */
1517 /* Do proper sign extension for the target. */
1518 gdb_assert (exec_bfd
);
1519 return (bfd_get_sign_extend_vma (exec_bfd
) > 0
1520 ? (CORE_ADDR
) (intptr_t) address
1521 : (CORE_ADDR
) (uintptr_t) address
);
1524 beneath
= find_target_beneath (this);
1525 return beneath
->get_thread_local_address (ptid
, lm
, offset
);
1528 /* Implement the to_get_ada_task_ptid target method for this target. */
1531 thread_db_target::get_ada_task_ptid (long lwp
, long thread
)
1533 /* NPTL uses a 1:1 model, so the LWP id suffices. */
1534 return ptid_build (ptid_get_pid (inferior_ptid
), lwp
, 0);
1538 thread_db_target::resume (ptid_t ptid
, int step
, enum gdb_signal signo
)
1540 struct target_ops
*beneath
= find_target_beneath (this);
1541 struct thread_db_info
*info
;
1543 if (ptid_equal (ptid
, minus_one_ptid
))
1544 info
= get_thread_db_info (ptid_get_pid (inferior_ptid
));
1546 info
= get_thread_db_info (ptid_get_pid (ptid
));
1548 /* This workaround is only needed for child fork lwps stopped in a
1549 PTRACE_O_TRACEFORK event. When the inferior is resumed, the
1550 workaround can be disabled. */
1552 info
->need_stale_parent_threads_check
= 0;
1554 beneath
->resume (ptid
, step
, signo
);
1557 /* std::sort helper function for info_auto_load_libthread_db, sort the
1558 thread_db_info pointers primarily by their FILENAME and secondarily by their
1559 PID, both in ascending order. */
1562 info_auto_load_libthread_db_compare (const struct thread_db_info
*a
,
1563 const struct thread_db_info
*b
)
1567 retval
= strcmp (a
->filename
, b
->filename
);
1571 return a
->pid
< b
->pid
;
1574 /* Implement 'info auto-load libthread-db'. */
1577 info_auto_load_libthread_db (const char *args
, int from_tty
)
1579 struct ui_out
*uiout
= current_uiout
;
1580 const char *cs
= args
? args
: "";
1581 struct thread_db_info
*info
;
1582 unsigned unique_filenames
;
1583 size_t max_filename_len
, pids_len
;
1586 cs
= skip_spaces (cs
);
1588 error (_("'info auto-load libthread-db' does not accept any parameters"));
1590 std::vector
<struct thread_db_info
*> array
;
1591 for (info
= thread_db_list
; info
; info
= info
->next
)
1592 if (info
->filename
!= NULL
)
1593 array
.push_back (info
);
1595 /* Sort ARRAY by filenames and PIDs. */
1596 std::sort (array
.begin (), array
.end (),
1597 info_auto_load_libthread_db_compare
);
1599 /* Calculate the number of unique filenames (rows) and the maximum string
1600 length of PIDs list for the unique filenames (columns). */
1602 unique_filenames
= 0;
1603 max_filename_len
= 0;
1605 for (i
= 0; i
< array
.size (); i
++)
1607 int pid
= array
[i
]->pid
;
1608 size_t this_pid_len
;
1610 for (this_pid_len
= 0; pid
!= 0; pid
/= 10)
1613 if (i
== 0 || strcmp (array
[i
- 1]->filename
, array
[i
]->filename
) != 0)
1616 max_filename_len
= std::max (max_filename_len
,
1617 strlen (array
[i
]->filename
));
1620 pids_len
-= strlen (", ");
1623 pids_len
+= this_pid_len
+ strlen (", ");
1626 pids_len
-= strlen (", ");
1628 /* Table header shifted right by preceding "libthread-db: " would not match
1630 if (array
.size () > 0 && args
== auto_load_info_scripts_pattern_nl
)
1634 ui_out_emit_table
table_emitter (uiout
, 2, unique_filenames
,
1635 "LinuxThreadDbTable");
1637 uiout
->table_header (max_filename_len
, ui_left
, "filename", "Filename");
1638 uiout
->table_header (pids_len
, ui_left
, "PIDs", "Pids");
1639 uiout
->table_body ();
1641 /* Note I is incremented inside the cycle, not at its end. */
1642 for (i
= 0; i
< array
.size ();)
1644 ui_out_emit_tuple
tuple_emitter (uiout
, NULL
);
1647 uiout
->field_string ("filename", info
->filename
);
1650 while (i
< array
.size () && strcmp (info
->filename
,
1651 array
[i
]->filename
) == 0)
1655 string_appendf (pids
, "%u", array
[i
]->pid
);
1659 uiout
->field_string ("pids", pids
.c_str ());
1666 uiout
->message (_("No auto-loaded libthread-db.\n"));
1670 _initialize_thread_db (void)
1672 /* Defer loading of libthread_db.so until inferior is running.
1673 This allows gdb to load correct libthread_db for a given
1674 executable -- there could be multiple versions of glibc,
1675 and until there is a running inferior, we can't tell which
1676 libthread_db is the correct one to load. */
1678 libthread_db_search_path
= xstrdup (LIBTHREAD_DB_SEARCH_PATH
);
1680 add_setshow_optional_filename_cmd ("libthread-db-search-path",
1682 &libthread_db_search_path
, _("\
1683 Set search path for libthread_db."), _("\
1684 Show the current search path or libthread_db."), _("\
1685 This path is used to search for libthread_db to be loaded into \
1687 Its value is a colon (':') separate list of directories to search.\n\
1688 Setting the search path to an empty list resets it to its default value."),
1689 set_libthread_db_search_path
,
1691 &setlist
, &showlist
);
1693 add_setshow_zuinteger_cmd ("libthread-db", class_maintenance
,
1694 &libthread_db_debug
, _("\
1695 Set libthread-db debugging."), _("\
1696 Show libthread-db debugging."), _("\
1697 When non-zero, libthread-db debugging is enabled."),
1699 show_libthread_db_debug
,
1700 &setdebuglist
, &showdebuglist
);
1702 add_setshow_boolean_cmd ("libthread-db", class_support
,
1703 &auto_load_thread_db
, _("\
1704 Enable or disable auto-loading of inferior specific libthread_db."), _("\
1705 Show whether auto-loading inferior specific libthread_db is enabled."), _("\
1706 If enabled, libthread_db will be searched in 'set libthread-db-search-path'\n\
1707 locations to load libthread_db compatible with the inferior.\n\
1708 Standard system libthread_db still gets loaded even with this option off.\n\
1709 This options has security implications for untrusted inferiors."),
1710 NULL
, show_auto_load_thread_db
,
1711 auto_load_set_cmdlist_get (),
1712 auto_load_show_cmdlist_get ());
1714 add_cmd ("libthread-db", class_info
, info_auto_load_libthread_db
,
1715 _("Print the list of loaded inferior specific libthread_db.\n\
1716 Usage: info auto-load libthread-db"),
1717 auto_load_info_cmdlist_get ());
1719 /* Add ourselves to objfile event chain. */
1720 gdb::observers::new_objfile
.attach (thread_db_new_objfile
);
1722 /* Add ourselves to inferior_created event chain.
1723 This is needed to handle debugging statically linked programs where
1724 the new_objfile observer won't get called for libpthread. */
1725 gdb::observers::inferior_created
.attach (thread_db_inferior_created
);