1 /* libthread_db assisted debugging support, generic parts.
3 Copyright (C) 1999-2015 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"
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"
49 /* GNU/Linux libthread_db support.
51 libthread_db is a library, provided along with libpthread.so, which
52 exposes the internals of the thread library to a debugger. It
53 allows GDB to find existing threads, new threads as they are
54 created, thread IDs (usually, the result of pthread_self), and
55 thread-local variables.
57 The libthread_db interface originates on Solaris, where it is
58 both more powerful and more complicated. This implementation
59 only works for LinuxThreads and NPTL, the two glibc threading
60 libraries. It assumes that each thread is permanently assigned
61 to a single light-weight process (LWP).
63 libthread_db-specific information is stored in the "private" field
64 of struct thread_info. When the field is NULL we do not yet have
65 information about the new thread; this could be temporary (created,
66 but the thread library's data structures do not reflect it yet)
67 or permanent (created using clone instead of pthread_create).
69 Process IDs managed by linux-thread-db.c match those used by
70 linux-nat.c: a common PID for all processes, an LWP ID for each
71 thread, and no TID. We save the TID in private. Keeping it out
72 of the ptid_t prevents thread IDs changing when libpthread is
73 loaded or unloaded. */
75 static char *libthread_db_search_path
;
77 /* Set to non-zero if thread_db auto-loading is enabled
78 by the "set auto-load libthread-db" command. */
79 static int auto_load_thread_db
= 1;
81 /* Returns true if we need to use thread_db thread create/death event
82 breakpoints to learn about threads. */
85 thread_db_use_events (void)
87 /* Not necessary if the kernel supports clone events. */
88 return !linux_supports_traceclone ();
91 /* "show" command for the auto_load_thread_db configuration variable. */
94 show_auto_load_thread_db (struct ui_file
*file
, int from_tty
,
95 struct cmd_list_element
*c
, const char *value
)
97 fprintf_filtered (file
, _("Auto-loading of inferior specific libthread_db "
103 set_libthread_db_search_path (char *ignored
, int from_tty
,
104 struct cmd_list_element
*c
)
106 if (*libthread_db_search_path
== '\0')
108 xfree (libthread_db_search_path
);
109 libthread_db_search_path
= xstrdup (LIBTHREAD_DB_SEARCH_PATH
);
113 /* If non-zero, print details of libthread_db processing. */
115 static unsigned int libthread_db_debug
;
118 show_libthread_db_debug (struct ui_file
*file
, int from_tty
,
119 struct cmd_list_element
*c
, const char *value
)
121 fprintf_filtered (file
, _("libthread-db debugging is %s.\n"), value
);
124 /* If we're running on GNU/Linux, we must explicitly attach to any new
127 /* This module's target vector. */
128 static struct target_ops thread_db_ops
;
130 /* Non-zero if we have determined the signals used by the threads
132 static int thread_signals
;
133 static sigset_t thread_stop_set
;
134 static sigset_t thread_print_set
;
136 struct thread_db_info
138 struct thread_db_info
*next
;
140 /* Process id this object refers to. */
143 /* Handle from dlopen for libthread_db.so. */
146 /* Absolute pathname from gdb_realpath to disk file used for dlopen-ing
147 HANDLE. It may be NULL for system library. */
150 /* Structure that identifies the child process for the
151 <proc_service.h> interface. */
152 struct ps_prochandle proc_handle
;
154 /* Connection to the libthread_db library. */
155 td_thragent_t
*thread_agent
;
157 /* True if we need to apply the workaround for glibc/BZ5983. When
158 we catch a PTRACE_O_TRACEFORK, and go query the child's thread
159 list, nptl_db returns the parent's threads in addition to the new
160 (single) child thread. If this flag is set, we do extra work to
161 be able to ignore such stale entries. */
162 int need_stale_parent_threads_check
;
164 /* Location of the thread creation event breakpoint. The code at
165 this location in the child process will be called by the pthread
166 library whenever a new thread is created. By setting a special
167 breakpoint at this location, GDB can detect when a new thread is
168 created. We obtain this location via the td_ta_event_addr
170 CORE_ADDR td_create_bp_addr
;
172 /* Location of the thread death event breakpoint. */
173 CORE_ADDR td_death_bp_addr
;
175 /* Pointers to the libthread_db functions. */
177 td_err_e (*td_init_p
) (void);
179 td_err_e (*td_ta_new_p
) (struct ps_prochandle
* ps
,
181 td_err_e (*td_ta_map_id2thr_p
) (const td_thragent_t
*ta
, thread_t pt
,
182 td_thrhandle_t
*__th
);
183 td_err_e (*td_ta_map_lwp2thr_p
) (const td_thragent_t
*ta
,
184 lwpid_t lwpid
, td_thrhandle_t
*th
);
185 td_err_e (*td_ta_thr_iter_p
) (const td_thragent_t
*ta
,
186 td_thr_iter_f
*callback
, void *cbdata_p
,
187 td_thr_state_e state
, int ti_pri
,
188 sigset_t
*ti_sigmask_p
,
189 unsigned int ti_user_flags
);
190 td_err_e (*td_ta_event_addr_p
) (const td_thragent_t
*ta
,
191 td_event_e event
, td_notify_t
*ptr
);
192 td_err_e (*td_ta_set_event_p
) (const td_thragent_t
*ta
,
193 td_thr_events_t
*event
);
194 td_err_e (*td_ta_clear_event_p
) (const td_thragent_t
*ta
,
195 td_thr_events_t
*event
);
196 td_err_e (*td_ta_event_getmsg_p
) (const td_thragent_t
*ta
,
197 td_event_msg_t
*msg
);
199 td_err_e (*td_thr_get_info_p
) (const td_thrhandle_t
*th
,
200 td_thrinfo_t
*infop
);
201 td_err_e (*td_thr_event_enable_p
) (const td_thrhandle_t
*th
,
204 td_err_e (*td_thr_tls_get_addr_p
) (const td_thrhandle_t
*th
,
205 psaddr_t map_address
,
206 size_t offset
, psaddr_t
*address
);
207 td_err_e (*td_thr_tlsbase_p
) (const td_thrhandle_t
*th
,
208 unsigned long int modid
,
212 /* List of known processes using thread_db, and the required
214 struct thread_db_info
*thread_db_list
;
216 static void thread_db_find_new_threads_1 (ptid_t ptid
);
217 static void thread_db_find_new_threads_2 (ptid_t ptid
, int until_no_new
);
219 static void check_thread_signals (void);
221 static void record_thread (struct thread_db_info
*info
,
222 struct thread_info
*tp
,
223 ptid_t ptid
, const td_thrhandle_t
*th_p
,
224 const td_thrinfo_t
*ti_p
);
226 /* Add the current inferior to the list of processes using libpthread.
227 Return a pointer to the newly allocated object that was added to
228 THREAD_DB_LIST. HANDLE is the handle returned by dlopen'ing
231 static struct thread_db_info
*
232 add_thread_db_info (void *handle
)
234 struct thread_db_info
*info
;
236 info
= xcalloc (1, sizeof (*info
));
237 info
->pid
= ptid_get_pid (inferior_ptid
);
238 info
->handle
= handle
;
240 /* The workaround works by reading from /proc/pid/status, so it is
241 disabled for core files. */
242 if (target_has_execution
)
243 info
->need_stale_parent_threads_check
= 1;
245 info
->next
= thread_db_list
;
246 thread_db_list
= info
;
251 /* Return the thread_db_info object representing the bookkeeping
252 related to process PID, if any; NULL otherwise. */
254 static struct thread_db_info
*
255 get_thread_db_info (int pid
)
257 struct thread_db_info
*info
;
259 for (info
= thread_db_list
; info
; info
= info
->next
)
260 if (pid
== info
->pid
)
266 /* When PID has exited or has been detached, we no longer want to keep
267 track of it as using libpthread. Call this function to discard
268 thread_db related info related to PID. Note that this closes
269 LIBTHREAD_DB_SO's dlopen'ed handle. */
272 delete_thread_db_info (int pid
)
274 struct thread_db_info
*info
, *info_prev
;
278 for (info
= thread_db_list
; info
; info_prev
= info
, info
= info
->next
)
279 if (pid
== info
->pid
)
285 if (info
->handle
!= NULL
)
286 dlclose (info
->handle
);
288 xfree (info
->filename
);
291 info_prev
->next
= info
->next
;
293 thread_db_list
= info
->next
;
298 /* Prototypes for local functions. */
299 static int attach_thread (ptid_t ptid
, const td_thrhandle_t
*th_p
,
300 const td_thrinfo_t
*ti_p
);
301 static void detach_thread (ptid_t ptid
);
304 /* Use "struct private_thread_info" to cache thread state. This is
305 a substantial optimization. */
307 struct private_thread_info
309 /* Flag set when we see a TD_DEATH event for this thread. */
310 unsigned int dying
:1;
312 /* Cached thread state. */
319 thread_db_err_str (td_err_e err
)
326 return "generic 'call succeeded'";
328 return "generic error";
330 return "no thread to satisfy query";
332 return "no sync handle to satisfy query";
334 return "no LWP to satisfy query";
336 return "invalid process handle";
338 return "invalid thread handle";
340 return "invalid synchronization handle";
342 return "invalid thread agent";
344 return "invalid key";
346 return "no event message for getmsg";
348 return "FPU register set not available";
350 return "application not linked with libthread";
352 return "requested event is not supported";
354 return "capability not available";
356 return "debugger service failed";
358 return "operation not applicable to";
360 return "no thread-specific data for this thread";
362 return "malloc failed";
364 return "only part of register set was written/read";
366 return "X register set not available for this thread";
367 #ifdef THREAD_DB_HAS_TD_NOTALLOC
369 return "thread has not yet allocated TLS for given module";
371 #ifdef THREAD_DB_HAS_TD_VERSION
373 return "versions of libpthread and libthread_db do not match";
375 #ifdef THREAD_DB_HAS_TD_NOTLS
377 return "there is no TLS segment in the given module";
380 snprintf (buf
, sizeof (buf
), "unknown thread_db error '%d'", err
);
385 /* Return 1 if any threads have been registered. There may be none if
386 the threading library is not fully initialized yet. */
389 have_threads_callback (struct thread_info
*thread
, void *args
)
391 int pid
= * (int *) args
;
393 if (ptid_get_pid (thread
->ptid
) != pid
)
396 return thread
->priv
!= NULL
;
400 have_threads (ptid_t ptid
)
402 int pid
= ptid_get_pid (ptid
);
404 return iterate_over_threads (have_threads_callback
, &pid
) != NULL
;
408 /* Fetch the user-level thread id of PTID. */
411 thread_from_lwp (ptid_t ptid
)
416 struct thread_db_info
*info
;
417 struct thread_info
*tp
;
419 /* Just in case td_ta_map_lwp2thr doesn't initialize it completely. */
422 /* This ptid comes from linux-nat.c, which should always fill in the
424 gdb_assert (ptid_get_lwp (ptid
) != 0);
426 info
= get_thread_db_info (ptid_get_pid (ptid
));
428 /* Access an lwp we know is stopped. */
429 info
->proc_handle
.ptid
= ptid
;
430 err
= info
->td_ta_map_lwp2thr_p (info
->thread_agent
, ptid_get_lwp (ptid
),
433 error (_("Cannot find user-level thread for LWP %ld: %s"),
434 ptid_get_lwp (ptid
), thread_db_err_str (err
));
436 err
= info
->td_thr_get_info_p (&th
, &ti
);
438 error (_("thread_get_info_callback: cannot get thread info: %s"),
439 thread_db_err_str (err
));
441 /* Fill the cache. */
442 tp
= find_thread_ptid (ptid
);
443 record_thread (info
, tp
, ptid
, &th
, &ti
);
447 /* See linux-nat.h. */
450 thread_db_notice_clone (ptid_t parent
, ptid_t child
)
455 struct thread_db_info
*info
;
457 info
= get_thread_db_info (ptid_get_pid (child
));
462 thread_from_lwp (child
);
464 /* If we do not know about the main thread yet, this would be a good
466 thread_from_lwp (parent
);
471 verbose_dlsym (void *handle
, const char *name
)
473 void *sym
= dlsym (handle
, name
);
475 warning (_("Symbol \"%s\" not found in libthread_db: %s"),
481 enable_thread_event (int event
, CORE_ADDR
*bp
)
485 struct thread_db_info
*info
;
487 info
= get_thread_db_info (ptid_get_pid (inferior_ptid
));
489 /* Access an lwp we know is stopped. */
490 info
->proc_handle
.ptid
= inferior_ptid
;
492 /* Get the breakpoint address for thread EVENT. */
493 err
= info
->td_ta_event_addr_p (info
->thread_agent
, event
, ¬ify
);
497 /* Set up the breakpoint. */
498 gdb_assert (exec_bfd
);
499 (*bp
) = (gdbarch_convert_from_func_ptr_addr
501 /* Do proper sign extension for the target. */
502 (bfd_get_sign_extend_vma (exec_bfd
) > 0
503 ? (CORE_ADDR
) (intptr_t) notify
.u
.bptaddr
504 : (CORE_ADDR
) (uintptr_t) notify
.u
.bptaddr
),
506 create_thread_event_breakpoint (target_gdbarch (), *bp
);
511 /* Verify inferior's '\0'-terminated symbol VER_SYMBOL starts with "%d.%d" and
512 return 1 if this version is lower (and not equal) to
513 VER_MAJOR_MIN.VER_MINOR_MIN. Return 0 in all other cases. */
516 inferior_has_bug (const char *ver_symbol
, int ver_major_min
, int ver_minor_min
)
518 struct bound_minimal_symbol version_msym
;
519 CORE_ADDR version_addr
;
521 int err
, got
, retval
= 0;
523 version_msym
= lookup_minimal_symbol (ver_symbol
, NULL
, NULL
);
524 if (version_msym
.minsym
== NULL
)
527 version_addr
= BMSYMBOL_VALUE_ADDRESS (version_msym
);
528 got
= target_read_string (version_addr
, &version
, 32, &err
);
529 if (err
== 0 && memchr (version
, 0, got
) == &version
[got
-1])
533 retval
= (sscanf (version
, "%d.%d", &major
, &minor
) == 2
534 && (major
< ver_major_min
535 || (major
== ver_major_min
&& minor
< ver_minor_min
)));
543 enable_thread_event_reporting (void)
545 td_thr_events_t events
;
547 struct thread_db_info
*info
;
549 info
= get_thread_db_info (ptid_get_pid (inferior_ptid
));
551 /* We cannot use the thread event reporting facility if these
552 functions aren't available. */
553 if (info
->td_ta_event_addr_p
== NULL
554 || info
->td_ta_set_event_p
== NULL
555 || info
->td_ta_event_getmsg_p
== NULL
556 || info
->td_thr_event_enable_p
== NULL
)
559 /* Set the process wide mask saying which events we're interested in. */
560 td_event_emptyset (&events
);
561 td_event_addset (&events
, TD_CREATE
);
563 /* There is a bug fixed between linuxthreads 2.1.3 and 2.2 by
564 commit 2e4581e4fba917f1779cd0a010a45698586c190a
565 * manager.c (pthread_exited): Correctly report event as TD_REAP
566 instead of TD_DEATH. Fix comments.
567 where event reporting facility is broken for TD_DEATH events,
568 so don't enable it if we have glibc but a lower version. */
569 if (!inferior_has_bug ("__linuxthreads_version", 2, 2))
570 td_event_addset (&events
, TD_DEATH
);
572 err
= info
->td_ta_set_event_p (info
->thread_agent
, &events
);
575 warning (_("Unable to set global thread event mask: %s"),
576 thread_db_err_str (err
));
580 /* Delete previous thread event breakpoints, if any. */
581 remove_thread_event_breakpoints ();
582 info
->td_create_bp_addr
= 0;
583 info
->td_death_bp_addr
= 0;
585 /* Set up the thread creation event. */
586 err
= enable_thread_event (TD_CREATE
, &info
->td_create_bp_addr
);
589 warning (_("Unable to get location for thread creation breakpoint: %s"),
590 thread_db_err_str (err
));
594 /* Set up the thread death event. */
595 err
= enable_thread_event (TD_DEATH
, &info
->td_death_bp_addr
);
598 warning (_("Unable to get location for thread death breakpoint: %s"),
599 thread_db_err_str (err
));
604 /* Similar as thread_db_find_new_threads_1, but try to silently ignore errors
607 Return 1 if the caller should abort libthread_db initialization. Return 0
611 thread_db_find_new_threads_silently (ptid_t ptid
)
616 thread_db_find_new_threads_2 (ptid
, 1);
619 CATCH (except
, RETURN_MASK_ERROR
)
621 if (libthread_db_debug
)
622 exception_fprintf (gdb_stdlog
, except
,
623 "Warning: thread_db_find_new_threads_silently: ");
625 /* There is a bug fixed between nptl 2.6.1 and 2.7 by
626 commit 7d9d8bd18906fdd17364f372b160d7ab896ce909
627 where calls to td_thr_get_info fail with TD_ERR for statically linked
628 executables if td_thr_get_info is called before glibc has initialized
631 If the nptl bug is NOT present in the inferior and still thread_db
632 reports an error return 1. It means the inferior has corrupted thread
633 list and GDB should fall back only to LWPs.
635 If the nptl bug is present in the inferior return 0 to silently ignore
636 such errors, and let gdb enumerate threads again later. In such case
637 GDB cannot properly display LWPs if the inferior thread list is
638 corrupted. For core files it does not apply, no 'later enumeration'
641 if (!target_has_execution
|| !inferior_has_bug ("nptl_version", 2, 7))
643 exception_fprintf (gdb_stderr
, except
,
644 _("Warning: couldn't activate thread debugging "
645 "using libthread_db: "));
654 /* Lookup a library in which given symbol resides.
655 Note: this is looking in GDB process, not in the inferior.
656 Returns library name, or NULL. */
659 dladdr_to_soname (const void *addr
)
663 if (dladdr (addr
, &info
) != 0)
664 return info
.dli_fname
;
668 /* Attempt to initialize dlopen()ed libthread_db, described by INFO.
670 Failure could happen if libthread_db does not have symbols we expect,
671 or when it refuses to work with the current inferior (e.g. due to
672 version mismatch between libthread_db and libpthread). */
675 try_thread_db_load_1 (struct thread_db_info
*info
)
679 /* Initialize pointers to the dynamic library functions we will use.
680 Essential functions first. */
682 info
->td_init_p
= verbose_dlsym (info
->handle
, "td_init");
683 if (info
->td_init_p
== NULL
)
686 err
= info
->td_init_p ();
689 warning (_("Cannot initialize libthread_db: %s"),
690 thread_db_err_str (err
));
694 info
->td_ta_new_p
= verbose_dlsym (info
->handle
, "td_ta_new");
695 if (info
->td_ta_new_p
== NULL
)
698 /* Initialize the structure that identifies the child process. */
699 info
->proc_handle
.ptid
= inferior_ptid
;
701 /* Now attempt to open a connection to the thread library. */
702 err
= info
->td_ta_new_p (&info
->proc_handle
, &info
->thread_agent
);
705 if (libthread_db_debug
)
706 fprintf_unfiltered (gdb_stdlog
, _("td_ta_new failed: %s\n"),
707 thread_db_err_str (err
));
712 #ifdef THREAD_DB_HAS_TD_VERSION
715 /* The errors above are not unexpected and silently ignored:
716 they just mean we haven't found correct version of
720 warning (_("td_ta_new failed: %s"), thread_db_err_str (err
));
725 info
->td_ta_map_id2thr_p
= verbose_dlsym (info
->handle
, "td_ta_map_id2thr");
726 if (info
->td_ta_map_id2thr_p
== NULL
)
729 info
->td_ta_map_lwp2thr_p
= verbose_dlsym (info
->handle
,
730 "td_ta_map_lwp2thr");
731 if (info
->td_ta_map_lwp2thr_p
== NULL
)
734 info
->td_ta_thr_iter_p
= verbose_dlsym (info
->handle
, "td_ta_thr_iter");
735 if (info
->td_ta_thr_iter_p
== NULL
)
738 info
->td_thr_get_info_p
= verbose_dlsym (info
->handle
, "td_thr_get_info");
739 if (info
->td_thr_get_info_p
== NULL
)
742 /* These are not essential. */
743 info
->td_ta_event_addr_p
= dlsym (info
->handle
, "td_ta_event_addr");
744 info
->td_ta_set_event_p
= dlsym (info
->handle
, "td_ta_set_event");
745 info
->td_ta_clear_event_p
= dlsym (info
->handle
, "td_ta_clear_event");
746 info
->td_ta_event_getmsg_p
= dlsym (info
->handle
, "td_ta_event_getmsg");
747 info
->td_thr_event_enable_p
= dlsym (info
->handle
, "td_thr_event_enable");
748 info
->td_thr_tls_get_addr_p
= dlsym (info
->handle
, "td_thr_tls_get_addr");
749 info
->td_thr_tlsbase_p
= dlsym (info
->handle
, "td_thr_tlsbase");
751 /* It's best to avoid td_ta_thr_iter if possible. That walks data
752 structures in the inferior's address space that may be corrupted,
753 or, if the target is running, may change while we walk them. If
754 there's execution (and /proc is mounted), then we're already
755 attached to all LWPs. Use thread_from_lwp, which uses
756 td_ta_map_lwp2thr instead, which does not walk the thread list.
758 td_ta_map_lwp2thr uses ps_get_thread_area, but we can't use that
759 currently on core targets, as it uses ptrace directly. */
760 if (target_has_execution
761 && linux_proc_task_list_dir_exists (ptid_get_pid (inferior_ptid
)))
764 int pid
= ptid_get_pid (inferior_ptid
);
766 linux_stop_and_wait_all_lwps ();
769 if (ptid_get_pid (lp
->ptid
) == pid
)
770 thread_from_lwp (lp
->ptid
);
772 linux_unstop_all_lwps ();
774 else if (thread_db_find_new_threads_silently (inferior_ptid
) != 0)
776 /* Even if libthread_db initializes, if the thread list is
777 corrupted, we'd not manage to list any threads. Better reject this
778 thread_db, and fall back to at least listing LWPs. */
782 printf_unfiltered (_("[Thread debugging using libthread_db enabled]\n"));
784 if (*libthread_db_search_path
|| libthread_db_debug
)
786 struct ui_file
*file
;
789 library
= dladdr_to_soname (*info
->td_ta_new_p
);
791 library
= LIBTHREAD_DB_SO
;
793 /* If we'd print this to gdb_stdout when debug output is
794 disabled, still print it to gdb_stdout if debug output is
795 enabled. User visible output should not depend on debug
797 file
= *libthread_db_search_path
!= '\0' ? gdb_stdout
: gdb_stdlog
;
798 fprintf_unfiltered (file
, _("Using host libthread_db library \"%s\".\n"),
802 /* The thread library was detected. Activate the thread_db target
803 if this is the first process using it. */
804 if (thread_db_list
->next
== NULL
)
805 push_target (&thread_db_ops
);
807 /* Enable event reporting, but not when debugging a core file. */
808 if (target_has_execution
&& thread_db_use_events ())
809 enable_thread_event_reporting ();
814 /* Attempt to use LIBRARY as libthread_db. LIBRARY could be absolute,
815 relative, or just LIBTHREAD_DB. */
818 try_thread_db_load (const char *library
, int check_auto_load_safe
)
821 struct thread_db_info
*info
;
823 if (libthread_db_debug
)
824 fprintf_unfiltered (gdb_stdlog
,
825 _("Trying host libthread_db library: %s.\n"),
828 if (check_auto_load_safe
)
830 if (access (library
, R_OK
) != 0)
832 /* Do not print warnings by file_is_auto_load_safe if the library does
833 not exist at this place. */
834 if (libthread_db_debug
)
835 fprintf_unfiltered (gdb_stdlog
, _("open failed: %s.\n"),
836 safe_strerror (errno
));
840 if (!file_is_auto_load_safe (library
, _("auto-load: Loading libthread-db "
841 "library \"%s\" from explicit "
847 handle
= dlopen (library
, RTLD_NOW
);
850 if (libthread_db_debug
)
851 fprintf_unfiltered (gdb_stdlog
, _("dlopen failed: %s.\n"), dlerror ());
855 if (libthread_db_debug
&& strchr (library
, '/') == NULL
)
859 td_init
= dlsym (handle
, "td_init");
862 const char *const libpath
= dladdr_to_soname (td_init
);
865 fprintf_unfiltered (gdb_stdlog
, _("Host %s resolved to: %s.\n"),
870 info
= add_thread_db_info (handle
);
872 /* Do not save system library name, that one is always trusted. */
873 if (strchr (library
, '/') != NULL
)
874 info
->filename
= gdb_realpath (library
);
876 if (try_thread_db_load_1 (info
))
879 /* This library "refused" to work on current inferior. */
880 delete_thread_db_info (ptid_get_pid (inferior_ptid
));
884 /* Subroutine of try_thread_db_load_from_pdir to simplify it.
885 Try loading libthread_db in directory(OBJ)/SUBDIR.
886 SUBDIR may be NULL. It may also be something like "../lib64".
887 The result is true for success. */
890 try_thread_db_load_from_pdir_1 (struct objfile
*obj
, const char *subdir
)
892 struct cleanup
*cleanup
;
895 const char *obj_name
= objfile_name (obj
);
897 if (obj_name
[0] != '/')
899 warning (_("Expected absolute pathname for libpthread in the"
900 " inferior, but got %s."), obj_name
);
904 path
= xmalloc (strlen (obj_name
) + (subdir
? strlen (subdir
) + 1 : 0)
905 + 1 + strlen (LIBTHREAD_DB_SO
) + 1);
906 cleanup
= make_cleanup (xfree
, path
);
908 strcpy (path
, obj_name
);
909 cp
= strrchr (path
, '/');
910 /* This should at minimum hit the first character. */
911 gdb_assert (cp
!= NULL
);
918 strcat (cp
, LIBTHREAD_DB_SO
);
920 result
= try_thread_db_load (path
, 1);
922 do_cleanups (cleanup
);
926 /* Handle $pdir in libthread-db-search-path.
927 Look for libthread_db in directory(libpthread)/SUBDIR.
928 SUBDIR may be NULL. It may also be something like "../lib64".
929 The result is true for success. */
932 try_thread_db_load_from_pdir (const char *subdir
)
936 if (!auto_load_thread_db
)
940 if (libpthread_name_p (objfile_name (obj
)))
942 if (try_thread_db_load_from_pdir_1 (obj
, subdir
))
945 /* We may have found the separate-debug-info version of
946 libpthread, and it may live in a directory without a matching
948 if (obj
->separate_debug_objfile_backlink
!= NULL
)
949 return try_thread_db_load_from_pdir_1 (obj
->separate_debug_objfile_backlink
,
958 /* Handle $sdir in libthread-db-search-path.
959 Look for libthread_db in the system dirs, or wherever a plain
960 dlopen(file_without_path) will look.
961 The result is true for success. */
964 try_thread_db_load_from_sdir (void)
966 return try_thread_db_load (LIBTHREAD_DB_SO
, 0);
969 /* Try to load libthread_db from directory DIR of length DIR_LEN.
970 The result is true for success. */
973 try_thread_db_load_from_dir (const char *dir
, size_t dir_len
)
975 struct cleanup
*cleanup
;
979 if (!auto_load_thread_db
)
982 path
= xmalloc (dir_len
+ 1 + strlen (LIBTHREAD_DB_SO
) + 1);
983 cleanup
= make_cleanup (xfree
, path
);
985 memcpy (path
, dir
, dir_len
);
987 strcpy (path
+ dir_len
+ 1, LIBTHREAD_DB_SO
);
989 result
= try_thread_db_load (path
, 1);
991 do_cleanups (cleanup
);
995 /* Search libthread_db_search_path for libthread_db which "agrees"
996 to work on current inferior.
997 The result is true for success. */
1000 thread_db_load_search (void)
1002 VEC (char_ptr
) *dir_vec
;
1003 struct cleanup
*cleanups
;
1007 dir_vec
= dirnames_to_char_ptr_vec (libthread_db_search_path
);
1008 cleanups
= make_cleanup_free_char_ptr_vec (dir_vec
);
1010 for (i
= 0; VEC_iterate (char_ptr
, dir_vec
, i
, this_dir
); ++i
)
1012 const int pdir_len
= sizeof ("$pdir") - 1;
1013 size_t this_dir_len
;
1015 this_dir_len
= strlen (this_dir
);
1017 if (strncmp (this_dir
, "$pdir", pdir_len
) == 0
1018 && (this_dir
[pdir_len
] == '\0'
1019 || this_dir
[pdir_len
] == '/'))
1021 char *subdir
= NULL
;
1022 struct cleanup
*free_subdir_cleanup
1023 = make_cleanup (null_cleanup
, NULL
);
1025 if (this_dir
[pdir_len
] == '/')
1027 subdir
= xmalloc (strlen (this_dir
));
1028 make_cleanup (xfree
, subdir
);
1029 strcpy (subdir
, this_dir
+ pdir_len
+ 1);
1031 rc
= try_thread_db_load_from_pdir (subdir
);
1032 do_cleanups (free_subdir_cleanup
);
1036 else if (strcmp (this_dir
, "$sdir") == 0)
1038 if (try_thread_db_load_from_sdir ())
1046 if (try_thread_db_load_from_dir (this_dir
, this_dir_len
))
1054 do_cleanups (cleanups
);
1055 if (libthread_db_debug
)
1056 fprintf_unfiltered (gdb_stdlog
,
1057 _("thread_db_load_search returning %d\n"), rc
);
1061 /* Return non-zero if the inferior has a libpthread. */
1064 has_libpthread (void)
1066 struct objfile
*obj
;
1069 if (libpthread_name_p (objfile_name (obj
)))
1075 /* Attempt to load and initialize libthread_db.
1076 Return 1 on success. */
1079 thread_db_load (void)
1081 struct thread_db_info
*info
;
1083 info
= get_thread_db_info (ptid_get_pid (inferior_ptid
));
1088 /* Don't attempt to use thread_db on executables not running
1090 if (!target_has_registers
)
1093 /* Don't attempt to use thread_db for remote targets. */
1094 if (!(target_can_run (¤t_target
) || core_bfd
))
1097 if (thread_db_load_search ())
1100 /* We couldn't find a libthread_db.
1101 If the inferior has a libpthread warn the user. */
1102 if (has_libpthread ())
1104 warning (_("Unable to find libthread_db matching inferior's thread"
1105 " library, thread debugging will not be available."));
1109 /* Either this executable isn't using libpthread at all, or it is
1110 statically linked. Since we can't easily distinguish these two cases,
1111 no warning is issued. */
1116 disable_thread_event_reporting (struct thread_db_info
*info
)
1118 if (info
->td_ta_clear_event_p
!= NULL
)
1120 td_thr_events_t events
;
1122 /* Set the process wide mask saying we aren't interested in any
1124 td_event_fillset (&events
);
1125 info
->td_ta_clear_event_p (info
->thread_agent
, &events
);
1128 info
->td_create_bp_addr
= 0;
1129 info
->td_death_bp_addr
= 0;
1133 check_thread_signals (void)
1135 if (!thread_signals
)
1140 lin_thread_get_thread_signals (&mask
);
1141 sigemptyset (&thread_stop_set
);
1142 sigemptyset (&thread_print_set
);
1144 for (i
= 1; i
< NSIG
; i
++)
1146 if (sigismember (&mask
, i
))
1148 if (signal_stop_update (gdb_signal_from_host (i
), 0))
1149 sigaddset (&thread_stop_set
, i
);
1150 if (signal_print_update (gdb_signal_from_host (i
), 0))
1151 sigaddset (&thread_print_set
, i
);
1158 /* Check whether thread_db is usable. This function is called when
1159 an inferior is created (or otherwise acquired, e.g. attached to)
1160 and when new shared libraries are loaded into a running process. */
1163 check_for_thread_db (void)
1165 /* Do nothing if we couldn't load libthread_db.so.1. */
1166 if (!thread_db_load ())
1170 /* This function is called via the new_objfile observer. */
1173 thread_db_new_objfile (struct objfile
*objfile
)
1175 /* This observer must always be called with inferior_ptid set
1179 /* libpthread with separate debug info has its debug info file already
1180 loaded (and notified without successful thread_db initialization)
1181 the time observer_notify_new_objfile is called for the library itself.
1182 Static executables have their separate debug info loaded already
1183 before the inferior has started. */
1184 && objfile
->separate_debug_objfile_backlink
== NULL
1185 /* Only check for thread_db if we loaded libpthread,
1186 or if this is the main symbol file.
1187 We need to check OBJF_MAINLINE to handle the case of debugging
1188 a statically linked executable AND the symbol file is specified AFTER
1189 the exec file is loaded (e.g., gdb -c core ; file foo).
1190 For dynamically linked executables, libpthread can be near the end
1191 of the list of shared libraries to load, and in an app of several
1192 thousand shared libraries, this can otherwise be painful. */
1193 && ((objfile
->flags
& OBJF_MAINLINE
) != 0
1194 || libpthread_name_p (objfile_name (objfile
))))
1195 check_for_thread_db ();
1199 check_pid_namespace_match (void)
1201 /* Check is only relevant for local targets targets. */
1202 if (target_can_run (¤t_target
))
1204 /* If the child is in a different PID namespace, its idea of its
1205 PID will differ from our idea of its PID. When we scan the
1206 child's thread list, we'll mistakenly think it has no threads
1207 since the thread PID fields won't match the PID we give to
1209 char *our_pid_ns
= linux_proc_pid_get_ns (getpid (), "pid");
1210 char *inferior_pid_ns
= linux_proc_pid_get_ns (
1211 ptid_get_pid (inferior_ptid
), "pid");
1213 if (our_pid_ns
!= NULL
&& inferior_pid_ns
!= NULL
1214 && strcmp (our_pid_ns
, inferior_pid_ns
) != 0)
1216 warning (_ ("Target and debugger are in different PID "
1217 "namespaces; thread lists and other data are "
1218 "likely unreliable"));
1222 xfree (inferior_pid_ns
);
1226 /* This function is called via the inferior_created observer.
1227 This handles the case of debugging statically linked executables. */
1230 thread_db_inferior_created (struct target_ops
*target
, int from_tty
)
1232 check_pid_namespace_match ();
1233 check_for_thread_db ();
1236 /* Update the thread's state (what's displayed in "info threads"),
1237 from libthread_db thread state information. */
1240 update_thread_state (struct private_thread_info
*priv
,
1241 const td_thrinfo_t
*ti_p
)
1243 priv
->dying
= (ti_p
->ti_state
== TD_THR_UNKNOWN
1244 || ti_p
->ti_state
== TD_THR_ZOMBIE
);
1247 /* Attach to a new thread. This function is called when we receive a
1248 TD_CREATE event or when we iterate over all threads and find one
1249 that wasn't already in our list. Returns true on success. */
1252 attach_thread (ptid_t ptid
, const td_thrhandle_t
*th_p
,
1253 const td_thrinfo_t
*ti_p
)
1255 struct thread_info
*tp
;
1256 struct thread_db_info
*info
;
1258 /* If we're being called after a TD_CREATE event, we may already
1259 know about this thread. There are two ways this can happen. We
1260 may have iterated over all threads between the thread creation
1261 and the TD_CREATE event, for instance when the user has issued
1262 the `info threads' command before the SIGTRAP for hitting the
1263 thread creation breakpoint was reported. Alternatively, the
1264 thread may have exited and a new one been created with the same
1265 thread ID. In the first case we don't need to do anything; in
1266 the second case we should discard information about the dead
1267 thread and attach to the new one. */
1268 tp
= find_thread_ptid (ptid
);
1271 /* If tp->priv is NULL, then GDB is already attached to this
1272 thread, but we do not know anything about it. We can learn
1273 about it here. This can only happen if we have some other
1274 way besides libthread_db to notice new threads (i.e.
1275 PTRACE_EVENT_CLONE); assume the same mechanism notices thread
1276 exit, so this can not be a stale thread recreated with the
1278 if (tp
->priv
!= NULL
)
1280 if (!tp
->priv
->dying
)
1283 delete_thread (ptid
);
1288 /* Under GNU/Linux, we have to attach to each and every thread. */
1289 if (target_has_execution
1294 res
= lin_lwp_attach_lwp (ptid_build (ptid_get_pid (ptid
),
1298 /* Error, stop iterating. */
1303 /* Pretend this thread doesn't exist yet, and keep
1308 /* Otherwise, we sucessfully attached to the thread. */
1311 info
= get_thread_db_info (ptid_get_pid (ptid
));
1312 record_thread (info
, tp
, ptid
, th_p
, ti_p
);
1316 /* Record a new thread in GDB's thread list. Creates the thread's
1317 private info. If TP is NULL, creates a new thread. Otherwise,
1321 record_thread (struct thread_db_info
*info
,
1322 struct thread_info
*tp
,
1323 ptid_t ptid
, const td_thrhandle_t
*th_p
,
1324 const td_thrinfo_t
*ti_p
)
1327 struct private_thread_info
*priv
;
1328 int new_thread
= (tp
== NULL
);
1330 /* A thread ID of zero may mean the thread library has not
1331 initialized yet. Leave private == NULL until the thread library
1333 if (ti_p
->ti_tid
== 0)
1336 /* Construct the thread's private data. */
1337 priv
= xmalloc (sizeof (struct private_thread_info
));
1338 memset (priv
, 0, sizeof (struct private_thread_info
));
1341 priv
->tid
= ti_p
->ti_tid
;
1342 update_thread_state (priv
, ti_p
);
1344 /* Add the thread to GDB's thread list. If we already know about a
1345 thread with this PTID, but it's marked exited, then the kernel
1346 reused the tid of an old thread. */
1347 if (tp
== NULL
|| tp
->state
== THREAD_EXITED
)
1348 tp
= add_thread_with_info (ptid
, priv
);
1352 /* Enable thread event reporting for this thread, except when
1353 debugging a core file. */
1354 if (target_has_execution
&& thread_db_use_events () && new_thread
)
1356 err
= info
->td_thr_event_enable_p (th_p
, 1);
1358 error (_("Cannot enable thread event reporting for %s: %s"),
1359 target_pid_to_str (ptid
), thread_db_err_str (err
));
1362 if (target_has_execution
)
1363 check_thread_signals ();
1367 detach_thread (ptid_t ptid
)
1369 struct thread_info
*thread_info
;
1371 /* Don't delete the thread now, because it still reports as active
1372 until it has executed a few instructions after the event
1373 breakpoint - if we deleted it now, "info threads" would cause us
1374 to re-attach to it. Just mark it as having had a TD_DEATH
1375 event. This means that we won't delete it from our thread list
1376 until we notice that it's dead (via prune_threads), or until
1377 something re-uses its thread ID. We'll report the thread exit
1378 when the underlying LWP dies. */
1379 thread_info
= find_thread_ptid (ptid
);
1380 gdb_assert (thread_info
!= NULL
&& thread_info
->priv
!= NULL
);
1381 thread_info
->priv
->dying
= 1;
1385 thread_db_detach (struct target_ops
*ops
, const char *args
, int from_tty
)
1387 struct target_ops
*target_beneath
= find_target_beneath (ops
);
1388 struct thread_db_info
*info
;
1390 info
= get_thread_db_info (ptid_get_pid (inferior_ptid
));
1394 if (target_has_execution
&& thread_db_use_events ())
1396 disable_thread_event_reporting (info
);
1398 /* Delete the old thread event breakpoints. Note that
1399 unlike when mourning, we can remove them here because
1400 there's still a live inferior to poke at. In any case,
1401 GDB will not try to insert anything in the inferior when
1402 removing a breakpoint. */
1403 remove_thread_event_breakpoints ();
1406 delete_thread_db_info (ptid_get_pid (inferior_ptid
));
1409 target_beneath
->to_detach (target_beneath
, args
, from_tty
);
1411 /* NOTE: From this point on, inferior_ptid is null_ptid. */
1413 /* If there are no more processes using libpthread, detach the
1414 thread_db target ops. */
1415 if (!thread_db_list
)
1416 unpush_target (&thread_db_ops
);
1419 /* Check if PID is currently stopped at the location of a thread event
1420 breakpoint location. If it is, read the event message and act upon
1424 check_event (ptid_t ptid
)
1426 struct regcache
*regcache
= get_thread_regcache (ptid
);
1427 struct gdbarch
*gdbarch
= get_regcache_arch (regcache
);
1433 struct thread_db_info
*info
;
1435 info
= get_thread_db_info (ptid_get_pid (ptid
));
1437 /* Bail out early if we're not at a thread event breakpoint. */
1438 stop_pc
= regcache_read_pc (regcache
);
1439 if (!target_supports_stopped_by_sw_breakpoint ())
1440 stop_pc
-= gdbarch_decr_pc_after_break (gdbarch
);
1442 if (stop_pc
!= info
->td_create_bp_addr
1443 && stop_pc
!= info
->td_death_bp_addr
)
1446 /* Access an lwp we know is stopped. */
1447 info
->proc_handle
.ptid
= ptid
;
1449 /* If we have only looked at the first thread before libpthread was
1450 initialized, we may not know its thread ID yet. Make sure we do
1451 before we add another thread to the list. */
1452 if (!have_threads (ptid
))
1453 thread_db_find_new_threads_1 (ptid
);
1455 /* If we are at a create breakpoint, we do not know what new lwp
1456 was created and cannot specifically locate the event message for it.
1457 We have to call td_ta_event_getmsg() to get
1458 the latest message. Since we have no way of correlating whether
1459 the event message we get back corresponds to our breakpoint, we must
1460 loop and read all event messages, processing them appropriately.
1461 This guarantees we will process the correct message before continuing
1462 from the breakpoint.
1464 Currently, death events are not enabled. If they are enabled,
1465 the death event can use the td_thr_event_getmsg() interface to
1466 get the message specifically for that lwp and avoid looping
1473 err
= info
->td_ta_event_getmsg_p (info
->thread_agent
, &msg
);
1476 if (err
== TD_NOMSG
)
1479 error (_("Cannot get thread event message: %s"),
1480 thread_db_err_str (err
));
1483 err
= info
->td_thr_get_info_p (msg
.th_p
, &ti
);
1485 error (_("Cannot get thread info: %s"), thread_db_err_str (err
));
1487 ptid
= ptid_build (ptid_get_pid (ptid
), ti
.ti_lid
, 0);
1492 /* Call attach_thread whether or not we already know about a
1493 thread with this thread ID. */
1494 attach_thread (ptid
, msg
.th_p
, &ti
);
1500 if (!in_thread_list (ptid
))
1501 error (_("Spurious thread death event."));
1503 detach_thread (ptid
);
1508 error (_("Spurious thread event."));
1515 thread_db_wait (struct target_ops
*ops
,
1516 ptid_t ptid
, struct target_waitstatus
*ourstatus
,
1519 struct thread_db_info
*info
;
1520 struct target_ops
*beneath
= find_target_beneath (ops
);
1522 ptid
= beneath
->to_wait (beneath
, ptid
, ourstatus
, options
);
1524 if (ourstatus
->kind
== TARGET_WAITKIND_IGNORE
)
1527 if (ourstatus
->kind
== TARGET_WAITKIND_EXITED
1528 || ourstatus
->kind
== TARGET_WAITKIND_SIGNALLED
)
1531 info
= get_thread_db_info (ptid_get_pid (ptid
));
1533 /* If this process isn't using thread_db, we're done. */
1537 if (ourstatus
->kind
== TARGET_WAITKIND_EXECD
)
1539 /* New image, it may or may not end up using thread_db. Assume
1540 not unless we find otherwise. */
1541 delete_thread_db_info (ptid_get_pid (ptid
));
1542 if (!thread_db_list
)
1543 unpush_target (&thread_db_ops
);
1545 /* Thread event breakpoints are deleted by
1546 update_breakpoints_after_exec. */
1551 if (ourstatus
->kind
== TARGET_WAITKIND_STOPPED
1552 && ourstatus
->value
.sig
== GDB_SIGNAL_TRAP
)
1553 /* Check for a thread event. */
1556 /* Fill in the thread's user-level thread id and status. */
1557 thread_from_lwp (ptid
);
1563 thread_db_mourn_inferior (struct target_ops
*ops
)
1565 struct target_ops
*target_beneath
= find_target_beneath (ops
);
1567 delete_thread_db_info (ptid_get_pid (inferior_ptid
));
1569 target_beneath
->to_mourn_inferior (target_beneath
);
1571 /* Delete the old thread event breakpoints. Do this after mourning
1572 the inferior, so that we don't try to uninsert them. */
1573 remove_thread_event_breakpoints ();
1575 /* Detach thread_db target ops. */
1576 if (!thread_db_list
)
1577 unpush_target (ops
);
1580 struct callback_data
1582 struct thread_db_info
*info
;
1587 find_new_threads_callback (const td_thrhandle_t
*th_p
, void *data
)
1592 struct thread_info
*tp
;
1593 struct callback_data
*cb_data
= data
;
1594 struct thread_db_info
*info
= cb_data
->info
;
1596 err
= info
->td_thr_get_info_p (th_p
, &ti
);
1598 error (_("find_new_threads_callback: cannot get thread info: %s"),
1599 thread_db_err_str (err
));
1601 if (ti
.ti_lid
== -1)
1603 /* A thread with kernel thread ID -1 is either a thread that
1604 exited and was joined, or a thread that is being created but
1605 hasn't started yet, and that is reusing the tcb/stack of a
1606 thread that previously exited and was joined. (glibc marks
1607 terminated and joined threads with kernel thread ID -1. See
1609 if (libthread_db_debug
)
1610 fprintf_unfiltered (gdb_stdlog
,
1611 "thread_db: skipping exited and "
1612 "joined thread (0x%lx)\n", ti
.ti_tid
);
1618 /* A thread ID of zero means that this is the main thread, but
1619 glibc has not yet initialized thread-local storage and the
1620 pthread library. We do not know what the thread's TID will
1621 be yet. Just enable event reporting and otherwise ignore
1624 /* In that case, we're not stopped in a fork syscall and don't
1625 need this glibc bug workaround. */
1626 info
->need_stale_parent_threads_check
= 0;
1628 if (target_has_execution
&& thread_db_use_events ())
1630 err
= info
->td_thr_event_enable_p (th_p
, 1);
1632 error (_("Cannot enable thread event reporting for LWP %d: %s"),
1633 (int) ti
.ti_lid
, thread_db_err_str (err
));
1639 /* Ignore stale parent threads, caused by glibc/BZ5983. This is a
1640 bit expensive, as it needs to open /proc/pid/status, so try to
1641 avoid doing the work if we know we don't have to. */
1642 if (info
->need_stale_parent_threads_check
)
1644 int tgid
= linux_proc_get_tgid (ti
.ti_lid
);
1646 if (tgid
!= -1 && tgid
!= info
->pid
)
1650 ptid
= ptid_build (info
->pid
, ti
.ti_lid
, 0);
1651 tp
= find_thread_ptid (ptid
);
1652 if (tp
== NULL
|| tp
->priv
== NULL
)
1654 if (attach_thread (ptid
, th_p
, &ti
))
1655 cb_data
->new_threads
+= 1;
1657 /* Problem attaching this thread; perhaps it exited before we
1659 This could mean that the thread list inside glibc itself is in
1660 inconsistent state, and libthread_db could go on looping forever
1661 (observed with glibc-2.3.6). To prevent that, terminate
1662 iteration: thread_db_find_new_threads_2 will retry. */
1665 else if (target_has_execution
&& !thread_db_use_events ())
1667 /* Need to update this if not using the libthread_db events
1668 (particularly, the TD_DEATH event). */
1669 update_thread_state (tp
->priv
, &ti
);
1675 /* Helper for thread_db_find_new_threads_2.
1676 Returns number of new threads found. */
1679 find_new_threads_once (struct thread_db_info
*info
, int iteration
,
1682 struct callback_data data
;
1683 td_err_e err
= TD_ERR
;
1686 data
.new_threads
= 0;
1688 /* See comment in thread_db_update_thread_list. */
1689 gdb_assert (!target_has_execution
|| thread_db_use_events ());
1693 /* Iterate over all user-space threads to discover new threads. */
1694 err
= info
->td_ta_thr_iter_p (info
->thread_agent
,
1695 find_new_threads_callback
,
1698 TD_THR_LOWEST_PRIORITY
,
1700 TD_THR_ANY_USER_FLAGS
);
1702 CATCH (except
, RETURN_MASK_ERROR
)
1704 if (libthread_db_debug
)
1706 exception_fprintf (gdb_stdlog
, except
,
1707 "Warning: find_new_threads_once: ");
1712 if (libthread_db_debug
)
1714 fprintf_unfiltered (gdb_stdlog
,
1715 _("Found %d new threads in iteration %d.\n"),
1716 data
.new_threads
, iteration
);
1722 return data
.new_threads
;
1725 /* Search for new threads, accessing memory through stopped thread
1726 PTID. If UNTIL_NO_NEW is true, repeat searching until several
1727 searches in a row do not discover any new threads. */
1730 thread_db_find_new_threads_2 (ptid_t ptid
, int until_no_new
)
1732 td_err_e err
= TD_OK
;
1733 struct thread_db_info
*info
;
1736 info
= get_thread_db_info (ptid_get_pid (ptid
));
1738 /* Access an lwp we know is stopped. */
1739 info
->proc_handle
.ptid
= ptid
;
1743 /* Require 4 successive iterations which do not find any new threads.
1744 The 4 is a heuristic: there is an inherent race here, and I have
1745 seen that 2 iterations in a row are not always sufficient to
1746 "capture" all threads. */
1747 for (i
= 0, loop
= 0; loop
< 4 && err
== TD_OK
; ++i
, ++loop
)
1748 if (find_new_threads_once (info
, i
, &err
) != 0)
1750 /* Found some new threads. Restart the loop from beginning. */
1755 find_new_threads_once (info
, 0, &err
);
1758 error (_("Cannot find new threads: %s"), thread_db_err_str (err
));
1762 thread_db_find_new_threads_1 (ptid_t ptid
)
1764 thread_db_find_new_threads_2 (ptid
, 0);
1768 update_thread_core (struct lwp_info
*info
, void *closure
)
1770 info
->core
= linux_common_core_of_thread (info
->ptid
);
1774 /* Update the thread list using td_ta_thr_iter. */
1777 thread_db_update_thread_list_td_ta_thr_iter (struct target_ops
*ops
)
1779 struct thread_db_info
*info
;
1780 struct inferior
*inf
;
1786 struct thread_info
*thread
;
1791 info
= get_thread_db_info (inf
->pid
);
1795 thread
= any_live_thread_of_process (inf
->pid
);
1796 if (thread
== NULL
|| thread
->executing
)
1799 thread_db_find_new_threads_1 (thread
->ptid
);
1803 /* Implement the to_update_thread_list target method for this
1807 thread_db_update_thread_list (struct target_ops
*ops
)
1809 /* It's best to avoid td_ta_thr_iter if possible. That walks data
1810 structures in the inferior's address space that may be corrupted,
1811 or, if the target is running, the list may change while we walk
1812 it. In the latter case, it's possible that a thread exits just
1813 at the exact time that causes GDB to get stuck in an infinite
1814 loop. To avoid pausing all threads whenever the core wants to
1815 refresh the thread list, if the kernel supports clone events
1816 (meaning we're always already attached to all LWPs), we use
1817 thread_from_lwp immediately when we see an LWP stop. That uses
1818 thread_db entry points that do not walk libpthread's thread list,
1819 so should be safe, as well as more efficient. */
1820 if (target_has_execution
&& !thread_db_use_events ())
1821 ops
->beneath
->to_update_thread_list (ops
->beneath
);
1823 thread_db_update_thread_list_td_ta_thr_iter (ops
);
1825 if (target_has_execution
)
1826 iterate_over_lwps (minus_one_ptid
/* iterate over all */,
1827 update_thread_core
, NULL
);
1831 thread_db_pid_to_str (struct target_ops
*ops
, ptid_t ptid
)
1833 struct thread_info
*thread_info
= find_thread_ptid (ptid
);
1834 struct target_ops
*beneath
;
1836 if (thread_info
!= NULL
&& thread_info
->priv
!= NULL
)
1838 static char buf
[64];
1841 tid
= thread_info
->priv
->tid
;
1842 snprintf (buf
, sizeof (buf
), "Thread 0x%lx (LWP %ld)",
1843 tid
, ptid_get_lwp (ptid
));
1848 beneath
= find_target_beneath (ops
);
1849 return beneath
->to_pid_to_str (beneath
, ptid
);
1852 /* Return a string describing the state of the thread specified by
1856 thread_db_extra_thread_info (struct target_ops
*self
,
1857 struct thread_info
*info
)
1859 if (info
->priv
== NULL
)
1862 if (info
->priv
->dying
)
1868 /* Get the address of the thread local variable in load module LM which
1869 is stored at OFFSET within the thread local storage for thread PTID. */
1872 thread_db_get_thread_local_address (struct target_ops
*ops
,
1877 struct thread_info
*thread_info
;
1878 struct target_ops
*beneath
;
1880 /* If we have not discovered any threads yet, check now. */
1881 if (!have_threads (ptid
))
1882 thread_db_find_new_threads_1 (ptid
);
1884 /* Find the matching thread. */
1885 thread_info
= find_thread_ptid (ptid
);
1887 if (thread_info
!= NULL
&& thread_info
->priv
!= NULL
)
1891 struct thread_db_info
*info
;
1893 info
= get_thread_db_info (ptid_get_pid (ptid
));
1895 /* Finally, get the address of the variable. */
1898 /* glibc doesn't provide the needed interface. */
1899 if (!info
->td_thr_tls_get_addr_p
)
1900 throw_error (TLS_NO_LIBRARY_SUPPORT_ERROR
,
1901 _("No TLS library support"));
1903 /* Note the cast through uintptr_t: this interface only works if
1904 a target address fits in a psaddr_t, which is a host pointer.
1905 So a 32-bit debugger can not access 64-bit TLS through this. */
1906 err
= info
->td_thr_tls_get_addr_p (&thread_info
->priv
->th
,
1907 (psaddr_t
)(uintptr_t) lm
,
1912 /* If glibc doesn't provide the needed interface throw an error
1913 that LM is zero - normally cases it should not be. */
1914 if (!info
->td_thr_tlsbase_p
)
1915 throw_error (TLS_LOAD_MODULE_NOT_FOUND_ERROR
,
1916 _("TLS load module not found"));
1918 /* This code path handles the case of -static -pthread executables:
1919 https://sourceware.org/ml/libc-help/2014-03/msg00024.html
1920 For older GNU libc r_debug.r_map is NULL. For GNU libc after
1921 PR libc/16831 due to GDB PR threads/16954 LOAD_MODULE is also NULL.
1922 The constant number 1 depends on GNU __libc_setup_tls
1923 initialization of l_tls_modid to 1. */
1924 err
= info
->td_thr_tlsbase_p (&thread_info
->priv
->th
,
1926 address
= (char *) address
+ offset
;
1929 #ifdef THREAD_DB_HAS_TD_NOTALLOC
1930 /* The memory hasn't been allocated, yet. */
1931 if (err
== TD_NOTALLOC
)
1932 /* Now, if libthread_db provided the initialization image's
1933 address, we *could* try to build a non-lvalue value from
1934 the initialization image. */
1935 throw_error (TLS_NOT_ALLOCATED_YET_ERROR
,
1936 _("TLS not allocated yet"));
1939 /* Something else went wrong. */
1941 throw_error (TLS_GENERIC_ERROR
,
1942 (("%s")), thread_db_err_str (err
));
1944 /* Cast assuming host == target. Joy. */
1945 /* Do proper sign extension for the target. */
1946 gdb_assert (exec_bfd
);
1947 return (bfd_get_sign_extend_vma (exec_bfd
) > 0
1948 ? (CORE_ADDR
) (intptr_t) address
1949 : (CORE_ADDR
) (uintptr_t) address
);
1952 beneath
= find_target_beneath (ops
);
1953 return beneath
->to_get_thread_local_address (beneath
, ptid
, lm
, offset
);
1956 /* Implement the to_get_ada_task_ptid target method for this target. */
1959 thread_db_get_ada_task_ptid (struct target_ops
*self
, long lwp
, long thread
)
1961 /* NPTL uses a 1:1 model, so the LWP id suffices. */
1962 return ptid_build (ptid_get_pid (inferior_ptid
), lwp
, 0);
1966 thread_db_resume (struct target_ops
*ops
,
1967 ptid_t ptid
, int step
, enum gdb_signal signo
)
1969 struct target_ops
*beneath
= find_target_beneath (ops
);
1970 struct thread_db_info
*info
;
1972 if (ptid_equal (ptid
, minus_one_ptid
))
1973 info
= get_thread_db_info (ptid_get_pid (inferior_ptid
));
1975 info
= get_thread_db_info (ptid_get_pid (ptid
));
1977 /* This workaround is only needed for child fork lwps stopped in a
1978 PTRACE_O_TRACEFORK event. When the inferior is resumed, the
1979 workaround can be disabled. */
1981 info
->need_stale_parent_threads_check
= 0;
1983 beneath
->to_resume (beneath
, ptid
, step
, signo
);
1986 /* qsort helper function for info_auto_load_libthread_db, sort the
1987 thread_db_info pointers primarily by their FILENAME and secondarily by their
1988 PID, both in ascending order. */
1991 info_auto_load_libthread_db_compare (const void *ap
, const void *bp
)
1993 struct thread_db_info
*a
= *(struct thread_db_info
**) ap
;
1994 struct thread_db_info
*b
= *(struct thread_db_info
**) bp
;
1997 retval
= strcmp (a
->filename
, b
->filename
);
2001 return (a
->pid
> b
->pid
) - (a
->pid
- b
->pid
);
2004 /* Implement 'info auto-load libthread-db'. */
2007 info_auto_load_libthread_db (char *args
, int from_tty
)
2009 struct ui_out
*uiout
= current_uiout
;
2010 const char *cs
= args
? args
: "";
2011 struct thread_db_info
*info
, **array
;
2012 unsigned info_count
, unique_filenames
;
2013 size_t max_filename_len
, max_pids_len
, pids_len
;
2014 struct cleanup
*back_to
;
2018 cs
= skip_spaces_const (cs
);
2020 error (_("'info auto-load libthread-db' does not accept any parameters"));
2023 for (info
= thread_db_list
; info
; info
= info
->next
)
2024 if (info
->filename
!= NULL
)
2027 array
= xmalloc (sizeof (*array
) * info_count
);
2028 back_to
= make_cleanup (xfree
, array
);
2031 for (info
= thread_db_list
; info
; info
= info
->next
)
2032 if (info
->filename
!= NULL
)
2033 array
[info_count
++] = info
;
2035 /* Sort ARRAY by filenames and PIDs. */
2037 qsort (array
, info_count
, sizeof (*array
),
2038 info_auto_load_libthread_db_compare
);
2040 /* Calculate the number of unique filenames (rows) and the maximum string
2041 length of PIDs list for the unique filenames (columns). */
2043 unique_filenames
= 0;
2044 max_filename_len
= 0;
2047 for (i
= 0; i
< info_count
; i
++)
2049 int pid
= array
[i
]->pid
;
2050 size_t this_pid_len
;
2052 for (this_pid_len
= 0; pid
!= 0; pid
/= 10)
2055 if (i
== 0 || strcmp (array
[i
- 1]->filename
, array
[i
]->filename
) != 0)
2058 max_filename_len
= max (max_filename_len
,
2059 strlen (array
[i
]->filename
));
2063 pids_len
-= strlen (", ");
2064 max_pids_len
= max (max_pids_len
, pids_len
);
2068 pids_len
+= this_pid_len
+ strlen (", ");
2072 pids_len
-= strlen (", ");
2073 max_pids_len
= max (max_pids_len
, pids_len
);
2076 /* Table header shifted right by preceding "libthread-db: " would not match
2078 if (info_count
> 0 && args
== auto_load_info_scripts_pattern_nl
)
2079 ui_out_text (uiout
, "\n");
2081 make_cleanup_ui_out_table_begin_end (uiout
, 2, unique_filenames
,
2082 "LinuxThreadDbTable");
2084 ui_out_table_header (uiout
, max_filename_len
, ui_left
, "filename",
2086 ui_out_table_header (uiout
, pids_len
, ui_left
, "PIDs", "Pids");
2087 ui_out_table_body (uiout
);
2089 pids
= xmalloc (max_pids_len
+ 1);
2090 make_cleanup (xfree
, pids
);
2092 /* Note I is incremented inside the cycle, not at its end. */
2093 for (i
= 0; i
< info_count
;)
2095 struct cleanup
*chain
= make_cleanup_ui_out_tuple_begin_end (uiout
, NULL
);
2099 ui_out_field_string (uiout
, "filename", info
->filename
);
2102 while (i
< info_count
&& strcmp (info
->filename
, array
[i
]->filename
) == 0)
2104 if (pids_end
!= pids
)
2109 pids_end
+= xsnprintf (pids_end
, &pids
[max_pids_len
+ 1] - pids_end
,
2110 "%u", array
[i
]->pid
);
2111 gdb_assert (pids_end
< &pids
[max_pids_len
+ 1]);
2117 ui_out_field_string (uiout
, "pids", pids
);
2119 ui_out_text (uiout
, "\n");
2120 do_cleanups (chain
);
2123 do_cleanups (back_to
);
2125 if (info_count
== 0)
2126 ui_out_message (uiout
, 0, _("No auto-loaded libthread-db.\n"));
2130 init_thread_db_ops (void)
2132 thread_db_ops
.to_shortname
= "multi-thread";
2133 thread_db_ops
.to_longname
= "multi-threaded child process.";
2134 thread_db_ops
.to_doc
= "Threads and pthreads support.";
2135 thread_db_ops
.to_detach
= thread_db_detach
;
2136 thread_db_ops
.to_wait
= thread_db_wait
;
2137 thread_db_ops
.to_resume
= thread_db_resume
;
2138 thread_db_ops
.to_mourn_inferior
= thread_db_mourn_inferior
;
2139 thread_db_ops
.to_update_thread_list
= thread_db_update_thread_list
;
2140 thread_db_ops
.to_pid_to_str
= thread_db_pid_to_str
;
2141 thread_db_ops
.to_stratum
= thread_stratum
;
2142 thread_db_ops
.to_has_thread_control
= tc_schedlock
;
2143 thread_db_ops
.to_get_thread_local_address
2144 = thread_db_get_thread_local_address
;
2145 thread_db_ops
.to_extra_thread_info
= thread_db_extra_thread_info
;
2146 thread_db_ops
.to_get_ada_task_ptid
= thread_db_get_ada_task_ptid
;
2147 thread_db_ops
.to_magic
= OPS_MAGIC
;
2149 complete_target_initialization (&thread_db_ops
);
2152 /* Provide a prototype to silence -Wmissing-prototypes. */
2153 extern initialize_file_ftype _initialize_thread_db
;
2156 _initialize_thread_db (void)
2158 init_thread_db_ops ();
2160 /* Defer loading of libthread_db.so until inferior is running.
2161 This allows gdb to load correct libthread_db for a given
2162 executable -- there could be mutiple versions of glibc,
2163 compiled with LinuxThreads or NPTL, and until there is
2164 a running inferior, we can't tell which libthread_db is
2165 the correct one to load. */
2167 libthread_db_search_path
= xstrdup (LIBTHREAD_DB_SEARCH_PATH
);
2169 add_setshow_optional_filename_cmd ("libthread-db-search-path",
2171 &libthread_db_search_path
, _("\
2172 Set search path for libthread_db."), _("\
2173 Show the current search path or libthread_db."), _("\
2174 This path is used to search for libthread_db to be loaded into \
2176 Its value is a colon (':') separate list of directories to search.\n\
2177 Setting the search path to an empty list resets it to its default value."),
2178 set_libthread_db_search_path
,
2180 &setlist
, &showlist
);
2182 add_setshow_zuinteger_cmd ("libthread-db", class_maintenance
,
2183 &libthread_db_debug
, _("\
2184 Set libthread-db debugging."), _("\
2185 Show libthread-db debugging."), _("\
2186 When non-zero, libthread-db debugging is enabled."),
2188 show_libthread_db_debug
,
2189 &setdebuglist
, &showdebuglist
);
2191 add_setshow_boolean_cmd ("libthread-db", class_support
,
2192 &auto_load_thread_db
, _("\
2193 Enable or disable auto-loading of inferior specific libthread_db."), _("\
2194 Show whether auto-loading inferior specific libthread_db is enabled."), _("\
2195 If enabled, libthread_db will be searched in 'set libthread-db-search-path'\n\
2196 locations to load libthread_db compatible with the inferior.\n\
2197 Standard system libthread_db still gets loaded even with this option off.\n\
2198 This options has security implications for untrusted inferiors."),
2199 NULL
, show_auto_load_thread_db
,
2200 auto_load_set_cmdlist_get (),
2201 auto_load_show_cmdlist_get ());
2203 add_cmd ("libthread-db", class_info
, info_auto_load_libthread_db
,
2204 _("Print the list of loaded inferior specific libthread_db.\n\
2205 Usage: info auto-load libthread-db"),
2206 auto_load_info_cmdlist_get ());
2208 /* Add ourselves to objfile event chain. */
2209 observer_attach_new_objfile (thread_db_new_objfile
);
2211 /* Add ourselves to inferior_created event chain.
2212 This is needed to handle debugging statically linked programs where
2213 the new_objfile observer won't get called for libpthread. */
2214 observer_attach_inferior_created (thread_db_inferior_created
);