1 /* libthread_db assisted debugging support, generic parts.
3 Copyright (C) 1999, 2000, 2001, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
4 2010 Free Software Foundation, Inc.
6 This file is part of GDB.
8 This program is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 3 of the License, or
11 (at your option) any later version.
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with this program. If not, see <http://www.gnu.org/licenses/>. */
23 #include "gdb_assert.h"
25 #include "gdb_proc_service.h"
26 #include "gdb_thread_db.h"
30 #include "exceptions.h"
32 #include "gdbthread.h"
39 #include "solib-svr4.h"
42 #include "linux-nat.h"
46 #ifdef HAVE_GNU_LIBC_VERSION_H
47 #include <gnu/libc-version.h>
50 /* GNU/Linux libthread_db support.
52 libthread_db is a library, provided along with libpthread.so, which
53 exposes the internals of the thread library to a debugger. It
54 allows GDB to find existing threads, new threads as they are
55 created, thread IDs (usually, the result of pthread_self), and
56 thread-local variables.
58 The libthread_db interface originates on Solaris, where it is
59 both more powerful and more complicated. This implementation
60 only works for LinuxThreads and NPTL, the two glibc threading
61 libraries. It assumes that each thread is permanently assigned
62 to a single light-weight process (LWP).
64 libthread_db-specific information is stored in the "private" field
65 of struct thread_info. When the field is NULL we do not yet have
66 information about the new thread; this could be temporary (created,
67 but the thread library's data structures do not reflect it yet)
68 or permanent (created using clone instead of pthread_create).
70 Process IDs managed by linux-thread-db.c match those used by
71 linux-nat.c: a common PID for all processes, an LWP ID for each
72 thread, and no TID. We save the TID in private. Keeping it out
73 of the ptid_t prevents thread IDs changing when libpthread is
74 loaded or unloaded. */
76 static char *libthread_db_search_path
;
78 /* If we're running on GNU/Linux, we must explicitly attach to any new
81 /* This module's target vector. */
82 static struct target_ops thread_db_ops
;
84 /* Non-zero if we have determined the signals used by the threads
86 static int thread_signals
;
87 static sigset_t thread_stop_set
;
88 static sigset_t thread_print_set
;
92 struct thread_db_info
*next
;
94 /* Process id this object refers to. */
97 /* Handle from dlopen for libthread_db.so. */
100 /* Structure that identifies the child process for the
101 <proc_service.h> interface. */
102 struct ps_prochandle proc_handle
;
104 /* Connection to the libthread_db library. */
105 td_thragent_t
*thread_agent
;
107 /* True if we need to apply the workaround for glibc/BZ5983. When
108 we catch a PTRACE_O_TRACEFORK, and go query the child's thread
109 list, nptl_db returns the parent's threads in addition to the new
110 (single) child thread. If this flag is set, we do extra work to
111 be able to ignore such stale entries. */
112 int need_stale_parent_threads_check
;
114 /* Location of the thread creation event breakpoint. The code at
115 this location in the child process will be called by the pthread
116 library whenever a new thread is created. By setting a special
117 breakpoint at this location, GDB can detect when a new thread is
118 created. We obtain this location via the td_ta_event_addr
120 CORE_ADDR td_create_bp_addr
;
122 /* Location of the thread death event breakpoint. */
123 CORE_ADDR td_death_bp_addr
;
125 /* Pointers to the libthread_db functions. */
127 td_err_e (*td_init_p
) (void);
129 td_err_e (*td_ta_new_p
) (struct ps_prochandle
* ps
,
131 td_err_e (*td_ta_map_id2thr_p
) (const td_thragent_t
*ta
, thread_t pt
,
132 td_thrhandle_t
*__th
);
133 td_err_e (*td_ta_map_lwp2thr_p
) (const td_thragent_t
*ta
,
134 lwpid_t lwpid
, td_thrhandle_t
*th
);
135 td_err_e (*td_ta_thr_iter_p
) (const td_thragent_t
*ta
,
136 td_thr_iter_f
*callback
, void *cbdata_p
,
137 td_thr_state_e state
, int ti_pri
,
138 sigset_t
*ti_sigmask_p
,
139 unsigned int ti_user_flags
);
140 td_err_e (*td_ta_event_addr_p
) (const td_thragent_t
*ta
,
141 td_event_e event
, td_notify_t
*ptr
);
142 td_err_e (*td_ta_set_event_p
) (const td_thragent_t
*ta
,
143 td_thr_events_t
*event
);
144 td_err_e (*td_ta_clear_event_p
) (const td_thragent_t
*ta
,
145 td_thr_events_t
*event
);
146 td_err_e (*td_ta_event_getmsg_p
) (const td_thragent_t
*ta
,
147 td_event_msg_t
*msg
);
149 td_err_e (*td_thr_validate_p
) (const td_thrhandle_t
*th
);
150 td_err_e (*td_thr_get_info_p
) (const td_thrhandle_t
*th
,
151 td_thrinfo_t
*infop
);
152 td_err_e (*td_thr_event_enable_p
) (const td_thrhandle_t
*th
,
155 td_err_e (*td_thr_tls_get_addr_p
) (const td_thrhandle_t
*th
,
156 psaddr_t map_address
,
157 size_t offset
, psaddr_t
*address
);
160 /* List of known processes using thread_db, and the required
162 struct thread_db_info
*thread_db_list
;
164 static void thread_db_find_new_threads_1 (ptid_t ptid
);
165 static void thread_db_find_new_threads_2 (ptid_t ptid
, int until_no_new
);
167 /* Add the current inferior to the list of processes using libpthread.
168 Return a pointer to the newly allocated object that was added to
169 THREAD_DB_LIST. HANDLE is the handle returned by dlopen'ing
172 static struct thread_db_info
*
173 add_thread_db_info (void *handle
)
175 struct thread_db_info
*info
;
177 info
= xcalloc (1, sizeof (*info
));
178 info
->pid
= ptid_get_pid (inferior_ptid
);
179 info
->handle
= handle
;
180 info
->need_stale_parent_threads_check
= 1;
182 info
->next
= thread_db_list
;
183 thread_db_list
= info
;
188 /* Return the thread_db_info object representing the bookkeeping
189 related to process PID, if any; NULL otherwise. */
191 static struct thread_db_info
*
192 get_thread_db_info (int pid
)
194 struct thread_db_info
*info
;
196 for (info
= thread_db_list
; info
; info
= info
->next
)
197 if (pid
== info
->pid
)
203 /* When PID has exited or has been detached, we no longer want to keep
204 track of it as using libpthread. Call this function to discard
205 thread_db related info related to PID. Note that this closes
206 LIBTHREAD_DB_SO's dlopen'ed handle. */
209 delete_thread_db_info (int pid
)
211 struct thread_db_info
*info
, *info_prev
;
215 for (info
= thread_db_list
; info
; info_prev
= info
, info
= info
->next
)
216 if (pid
== info
->pid
)
222 if (info
->handle
!= NULL
)
223 dlclose (info
->handle
);
226 info_prev
->next
= info
->next
;
228 thread_db_list
= info
->next
;
233 /* Prototypes for local functions. */
234 static int attach_thread (ptid_t ptid
, const td_thrhandle_t
*th_p
,
235 const td_thrinfo_t
*ti_p
);
236 static void detach_thread (ptid_t ptid
);
239 /* Use "struct private_thread_info" to cache thread state. This is
240 a substantial optimization. */
242 struct private_thread_info
244 /* Flag set when we see a TD_DEATH event for this thread. */
245 unsigned int dying
:1;
247 /* Cached thread state. */
254 thread_db_err_str (td_err_e err
)
261 return "generic 'call succeeded'";
263 return "generic error";
265 return "no thread to satisfy query";
267 return "no sync handle to satisfy query";
269 return "no LWP to satisfy query";
271 return "invalid process handle";
273 return "invalid thread handle";
275 return "invalid synchronization handle";
277 return "invalid thread agent";
279 return "invalid key";
281 return "no event message for getmsg";
283 return "FPU register set not available";
285 return "application not linked with libthread";
287 return "requested event is not supported";
289 return "capability not available";
291 return "debugger service failed";
293 return "operation not applicable to";
295 return "no thread-specific data for this thread";
297 return "malloc failed";
299 return "only part of register set was written/read";
301 return "X register set not available for this thread";
302 #ifdef THREAD_DB_HAS_TD_NOTALLOC
304 return "thread has not yet allocated TLS for given module";
306 #ifdef THREAD_DB_HAS_TD_VERSION
308 return "versions of libpthread and libthread_db do not match";
310 #ifdef THREAD_DB_HAS_TD_NOTLS
312 return "there is no TLS segment in the given module";
315 snprintf (buf
, sizeof (buf
), "unknown thread_db error '%d'", err
);
320 /* Return 1 if any threads have been registered. There may be none if
321 the threading library is not fully initialized yet. */
324 have_threads_callback (struct thread_info
*thread
, void *args
)
326 int pid
= * (int *) args
;
327 if (ptid_get_pid (thread
->ptid
) != pid
)
330 return thread
->private != NULL
;
334 have_threads (ptid_t ptid
)
336 int pid
= ptid_get_pid (ptid
);
338 return iterate_over_threads (have_threads_callback
, &pid
) != NULL
;
341 struct thread_get_info_inout
343 struct thread_info
*thread_info
;
344 struct thread_db_info
*thread_db_info
;
347 /* A callback function for td_ta_thr_iter, which we use to map all
350 THP is a handle to the current thread; if INFOP is not NULL, the
351 struct thread_info associated with this thread is returned in
354 If the thread is a zombie, TD_THR_ZOMBIE is returned. Otherwise,
355 zero is returned to indicate success. */
358 thread_get_info_callback (const td_thrhandle_t
*thp
, void *argp
)
363 struct thread_get_info_inout
*inout
;
364 struct thread_db_info
*info
;
367 info
= inout
->thread_db_info
;
369 err
= info
->td_thr_get_info_p (thp
, &ti
);
371 error (_("thread_get_info_callback: cannot get thread info: %s"),
372 thread_db_err_str (err
));
374 /* Fill the cache. */
375 thread_ptid
= ptid_build (info
->pid
, ti
.ti_lid
, 0);
376 inout
->thread_info
= find_thread_ptid (thread_ptid
);
378 /* In the case of a zombie thread, don't continue. We don't want to
379 attach to it thinking it is a new thread. */
380 if (ti
.ti_state
== TD_THR_UNKNOWN
|| ti
.ti_state
== TD_THR_ZOMBIE
)
381 return TD_THR_ZOMBIE
;
383 if (inout
->thread_info
== NULL
)
385 /* New thread. Attach to it now (why wait?). */
386 if (!have_threads (thread_ptid
))
387 thread_db_find_new_threads_1 (thread_ptid
);
389 attach_thread (thread_ptid
, thp
, &ti
);
390 inout
->thread_info
= find_thread_ptid (thread_ptid
);
391 gdb_assert (inout
->thread_info
!= NULL
);
397 /* Convert between user-level thread ids and LWP ids. */
400 thread_from_lwp (ptid_t ptid
)
404 struct thread_db_info
*info
;
405 struct thread_get_info_inout io
= {0};
407 /* This ptid comes from linux-nat.c, which should always fill in the
409 gdb_assert (GET_LWP (ptid
) != 0);
411 info
= get_thread_db_info (GET_PID (ptid
));
413 /* Access an lwp we know is stopped. */
414 info
->proc_handle
.ptid
= ptid
;
415 err
= info
->td_ta_map_lwp2thr_p (info
->thread_agent
, GET_LWP (ptid
), &th
);
417 error (_("Cannot find user-level thread for LWP %ld: %s"),
418 GET_LWP (ptid
), thread_db_err_str (err
));
420 /* Fetch the thread info. If we get back TD_THR_ZOMBIE, then the
421 event thread has already died. If another gdb interface has called
422 thread_alive() previously, the thread won't be found on the thread list
423 anymore. In that case, we don't want to process this ptid anymore
424 to avoid the possibility of later treating it as a newly
425 discovered thread id that we should add to the list. Thus,
426 we return a -1 ptid which is also how the thread list marks a
428 io
.thread_db_info
= info
;
429 io
.thread_info
= NULL
;
430 if (thread_get_info_callback (&th
, &io
) == TD_THR_ZOMBIE
431 && io
.thread_info
== NULL
)
432 return minus_one_ptid
;
434 gdb_assert (ptid_get_tid (ptid
) == 0);
439 /* Attach to lwp PTID, doing whatever else is required to have this
440 LWP under the debugger's control --- e.g., enabling event
441 reporting. Returns true on success. */
443 thread_db_attach_lwp (ptid_t ptid
)
448 struct thread_db_info
*info
;
450 info
= get_thread_db_info (GET_PID (ptid
));
455 /* This ptid comes from linux-nat.c, which should always fill in the
457 gdb_assert (GET_LWP (ptid
) != 0);
459 /* Access an lwp we know is stopped. */
460 info
->proc_handle
.ptid
= ptid
;
462 /* If we have only looked at the first thread before libpthread was
463 initialized, we may not know its thread ID yet. Make sure we do
464 before we add another thread to the list. */
465 if (!have_threads (ptid
))
466 thread_db_find_new_threads_1 (ptid
);
468 err
= info
->td_ta_map_lwp2thr_p (info
->thread_agent
, GET_LWP (ptid
), &th
);
470 /* Cannot find user-level thread. */
473 err
= info
->td_thr_get_info_p (&th
, &ti
);
476 warning (_("Cannot get thread info: %s"), thread_db_err_str (err
));
480 attach_thread (ptid
, &th
, &ti
);
485 verbose_dlsym (void *handle
, const char *name
)
487 void *sym
= dlsym (handle
, name
);
489 warning (_("Symbol \"%s\" not found in libthread_db: %s"), name
, dlerror ());
494 enable_thread_event (int event
, CORE_ADDR
*bp
)
498 struct thread_db_info
*info
;
500 info
= get_thread_db_info (GET_PID (inferior_ptid
));
502 /* Access an lwp we know is stopped. */
503 info
->proc_handle
.ptid
= inferior_ptid
;
505 /* Get the breakpoint address for thread EVENT. */
506 err
= info
->td_ta_event_addr_p (info
->thread_agent
, event
, ¬ify
);
510 /* Set up the breakpoint. */
511 gdb_assert (exec_bfd
);
512 (*bp
) = (gdbarch_convert_from_func_ptr_addr
514 /* Do proper sign extension for the target. */
515 (bfd_get_sign_extend_vma (exec_bfd
) > 0
516 ? (CORE_ADDR
) (intptr_t) notify
.u
.bptaddr
517 : (CORE_ADDR
) (uintptr_t) notify
.u
.bptaddr
),
519 create_thread_event_breakpoint (target_gdbarch
, *bp
);
525 enable_thread_event_reporting (void)
527 td_thr_events_t events
;
529 #ifdef HAVE_GNU_LIBC_VERSION_H
530 const char *libc_version
;
531 int libc_major
, libc_minor
;
533 struct thread_db_info
*info
;
535 info
= get_thread_db_info (GET_PID (inferior_ptid
));
537 /* We cannot use the thread event reporting facility if these
538 functions aren't available. */
539 if (info
->td_ta_event_addr_p
== NULL
540 || info
->td_ta_set_event_p
== NULL
541 || info
->td_ta_event_getmsg_p
== NULL
542 || info
->td_thr_event_enable_p
== NULL
)
545 /* Set the process wide mask saying which events we're interested in. */
546 td_event_emptyset (&events
);
547 td_event_addset (&events
, TD_CREATE
);
549 #ifdef HAVE_GNU_LIBC_VERSION_H
550 /* The event reporting facility is broken for TD_DEATH events in
551 glibc 2.1.3, so don't enable it if we have glibc but a lower
553 libc_version
= gnu_get_libc_version ();
554 if (sscanf (libc_version
, "%d.%d", &libc_major
, &libc_minor
) == 2
555 && (libc_major
> 2 || (libc_major
== 2 && libc_minor
> 1)))
557 td_event_addset (&events
, TD_DEATH
);
559 err
= info
->td_ta_set_event_p (info
->thread_agent
, &events
);
562 warning (_("Unable to set global thread event mask: %s"),
563 thread_db_err_str (err
));
567 /* Delete previous thread event breakpoints, if any. */
568 remove_thread_event_breakpoints ();
569 info
->td_create_bp_addr
= 0;
570 info
->td_death_bp_addr
= 0;
572 /* Set up the thread creation event. */
573 err
= enable_thread_event (TD_CREATE
, &info
->td_create_bp_addr
);
576 warning (_("Unable to get location for thread creation breakpoint: %s"),
577 thread_db_err_str (err
));
581 /* Set up the thread death event. */
582 err
= enable_thread_event (TD_DEATH
, &info
->td_death_bp_addr
);
585 warning (_("Unable to get location for thread death breakpoint: %s"),
586 thread_db_err_str (err
));
591 /* Same as thread_db_find_new_threads_1, but silently ignore errors. */
594 thread_db_find_new_threads_silently (ptid_t ptid
)
596 volatile struct gdb_exception except
;
598 TRY_CATCH (except
, RETURN_MASK_ERROR
)
600 thread_db_find_new_threads_2 (ptid
, 1);
603 if (except
.reason
< 0 && info_verbose
)
605 exception_fprintf (gdb_stderr
, except
,
606 "Warning: thread_db_find_new_threads_silently: ");
610 /* Lookup a library in which given symbol resides.
611 Note: this is looking in GDB process, not in the inferior.
612 Returns library name, or NULL. */
615 dladdr_to_soname (const void *addr
)
619 if (dladdr (addr
, &info
) != 0)
620 return info
.dli_fname
;
624 /* Attempt to initialize dlopen()ed libthread_db, described by HANDLE.
626 Failure could happen if libthread_db does not have symbols we expect,
627 or when it refuses to work with the current inferior (e.g. due to
628 version mismatch between libthread_db and libpthread). */
631 try_thread_db_load_1 (struct thread_db_info
*info
)
635 /* Initialize pointers to the dynamic library functions we will use.
636 Essential functions first. */
638 info
->td_init_p
= verbose_dlsym (info
->handle
, "td_init");
639 if (info
->td_init_p
== NULL
)
642 err
= info
->td_init_p ();
645 warning (_("Cannot initialize libthread_db: %s"), thread_db_err_str (err
));
649 info
->td_ta_new_p
= verbose_dlsym (info
->handle
, "td_ta_new");
650 if (info
->td_ta_new_p
== NULL
)
653 /* Initialize the structure that identifies the child process. */
654 info
->proc_handle
.ptid
= inferior_ptid
;
656 /* Now attempt to open a connection to the thread library. */
657 err
= info
->td_ta_new_p (&info
->proc_handle
, &info
->thread_agent
);
661 printf_unfiltered (_("td_ta_new failed: %s\n"),
662 thread_db_err_str (err
));
667 #ifdef THREAD_DB_HAS_TD_VERSION
670 /* The errors above are not unexpected and silently ignored:
671 they just mean we haven't found correct version of
675 warning (_("td_ta_new failed: %s"), thread_db_err_str (err
));
680 info
->td_ta_map_id2thr_p
= verbose_dlsym (info
->handle
, "td_ta_map_id2thr");
681 if (info
->td_ta_map_id2thr_p
== NULL
)
684 info
->td_ta_map_lwp2thr_p
= verbose_dlsym (info
->handle
, "td_ta_map_lwp2thr");
685 if (info
->td_ta_map_lwp2thr_p
== NULL
)
688 info
->td_ta_thr_iter_p
= verbose_dlsym (info
->handle
, "td_ta_thr_iter");
689 if (info
->td_ta_thr_iter_p
== NULL
)
692 info
->td_thr_validate_p
= verbose_dlsym (info
->handle
, "td_thr_validate");
693 if (info
->td_thr_validate_p
== NULL
)
696 info
->td_thr_get_info_p
= verbose_dlsym (info
->handle
, "td_thr_get_info");
697 if (info
->td_thr_get_info_p
== NULL
)
700 /* These are not essential. */
701 info
->td_ta_event_addr_p
= dlsym (info
->handle
, "td_ta_event_addr");
702 info
->td_ta_set_event_p
= dlsym (info
->handle
, "td_ta_set_event");
703 info
->td_ta_clear_event_p
= dlsym (info
->handle
, "td_ta_clear_event");
704 info
->td_ta_event_getmsg_p
= dlsym (info
->handle
, "td_ta_event_getmsg");
705 info
->td_thr_event_enable_p
= dlsym (info
->handle
, "td_thr_event_enable");
706 info
->td_thr_tls_get_addr_p
= dlsym (info
->handle
, "td_thr_tls_get_addr");
708 printf_unfiltered (_("[Thread debugging using libthread_db enabled]\n"));
710 if (info_verbose
|| *libthread_db_search_path
)
714 library
= dladdr_to_soname (*info
->td_ta_new_p
);
716 library
= LIBTHREAD_DB_SO
;
718 printf_unfiltered (_("Using host libthread_db library \"%s\".\n"),
722 /* The thread library was detected. Activate the thread_db target
723 if this is the first process using it. */
724 if (thread_db_list
->next
== NULL
)
725 push_target (&thread_db_ops
);
727 enable_thread_event_reporting ();
729 /* There appears to be a bug in glibc-2.3.6: calls to td_thr_get_info fail
730 with TD_ERR for statically linked executables if td_thr_get_info is
731 called before glibc has initialized itself. Silently ignore such
732 errors, and let gdb enumerate threads again later. */
733 thread_db_find_new_threads_silently (inferior_ptid
);
738 /* Attempt to use LIBRARY as libthread_db. LIBRARY could be absolute,
739 relative, or just LIBTHREAD_DB. */
742 try_thread_db_load (const char *library
)
745 struct thread_db_info
*info
;
748 printf_unfiltered (_("Trying host libthread_db library: %s.\n"),
750 handle
= dlopen (library
, RTLD_NOW
);
754 printf_unfiltered (_("dlopen failed: %s.\n"), dlerror ());
758 if (info_verbose
&& strchr (library
, '/') == NULL
)
762 td_init
= dlsym (handle
, "td_init");
765 const char *const libpath
= dladdr_to_soname (td_init
);
768 printf_unfiltered (_("Host %s resolved to: %s.\n"),
773 info
= add_thread_db_info (handle
);
775 if (try_thread_db_load_1 (info
))
778 /* This library "refused" to work on current inferior. */
779 delete_thread_db_info (GET_PID (inferior_ptid
));
784 /* Search libthread_db_search_path for libthread_db which "agrees"
785 to work on current inferior. */
788 thread_db_load_search (void)
791 const char *search_path
= libthread_db_search_path
;
796 const char *end
= strchr (search_path
, ':');
799 size_t len
= end
- search_path
;
800 if (len
+ 1 + strlen (LIBTHREAD_DB_SO
) + 1 > sizeof (path
))
802 char *cp
= xmalloc (len
+ 1);
803 memcpy (cp
, search_path
, len
);
805 warning (_("libthread_db_search_path component too long,"
806 " ignored: %s."), cp
);
808 search_path
+= len
+ 1;
811 memcpy (path
, search_path
, len
);
813 search_path
+= len
+ 1;
817 size_t len
= strlen (search_path
);
819 if (len
+ 1 + strlen (LIBTHREAD_DB_SO
) + 1 > sizeof (path
))
821 warning (_("libthread_db_search_path component too long,"
822 " ignored: %s."), search_path
);
825 memcpy (path
, search_path
, len
+ 1);
829 strcat (path
, LIBTHREAD_DB_SO
);
830 if (try_thread_db_load (path
))
837 rc
= try_thread_db_load (LIBTHREAD_DB_SO
);
841 /* Attempt to load and initialize libthread_db.
846 thread_db_load (void)
849 struct thread_db_info
*info
;
851 info
= get_thread_db_info (GET_PID (inferior_ptid
));
856 /* Don't attempt to use thread_db on targets which can not run
857 (executables not running yet, core files) for now. */
858 if (!target_has_execution
)
861 /* Don't attempt to use thread_db for remote targets. */
862 if (!target_can_run (¤t_target
))
865 if (thread_db_load_search ())
868 /* None of the libthread_db's on our search path, not the system default
869 ones worked. If the executable is dynamically linked against
870 libpthread, try loading libthread_db from the same directory. */
873 if (libpthread_name_p (obj
->name
))
875 char path
[PATH_MAX
], *cp
;
877 gdb_assert (strlen (obj
->name
) < sizeof (path
));
878 strcpy (path
, obj
->name
);
879 cp
= strrchr (path
, '/');
883 warning (_("Expected absolute pathname for libpthread in the"
884 " inferior, but got %s."), path
);
886 else if (cp
+ 1 + strlen (LIBTHREAD_DB_SO
) + 1 > path
+ sizeof (path
))
888 warning (_("Unexpected: path to libpthread in the inferior is"
889 " too long: %s"), path
);
893 strcpy (cp
+ 1, LIBTHREAD_DB_SO
);
894 if (try_thread_db_load (path
))
897 warning (_("Unable to find libthread_db matching inferior's thread"
898 " library, thread debugging will not be available."));
901 /* Either this executable isn't using libpthread at all, or it is
902 statically linked. Since we can't easily distinguish these two cases,
903 no warning is issued. */
908 disable_thread_event_reporting (struct thread_db_info
*info
)
910 if (info
->td_ta_clear_event_p
!= NULL
)
912 td_thr_events_t events
;
914 /* Set the process wide mask saying we aren't interested in any
916 td_event_fillset (&events
);
917 info
->td_ta_clear_event_p (info
->thread_agent
, &events
);
920 info
->td_create_bp_addr
= 0;
921 info
->td_death_bp_addr
= 0;
925 check_thread_signals (void)
927 #ifdef GET_THREAD_SIGNALS
933 GET_THREAD_SIGNALS (&mask
);
934 sigemptyset (&thread_stop_set
);
935 sigemptyset (&thread_print_set
);
937 for (i
= 1; i
< NSIG
; i
++)
939 if (sigismember (&mask
, i
))
941 if (signal_stop_update (target_signal_from_host (i
), 0))
942 sigaddset (&thread_stop_set
, i
);
943 if (signal_print_update (target_signal_from_host (i
), 0))
944 sigaddset (&thread_print_set
, i
);
952 /* Check whether thread_db is usable. This function is called when
953 an inferior is created (or otherwise acquired, e.g. attached to)
954 and when new shared libraries are loaded into a running process. */
957 check_for_thread_db (void)
959 /* Do nothing if we couldn't load libthread_db.so.1. */
960 if (!thread_db_load ())
965 thread_db_new_objfile (struct objfile
*objfile
)
967 /* This observer must always be called with inferior_ptid set
971 check_for_thread_db ();
974 /* Attach to a new thread. This function is called when we receive a
975 TD_CREATE event or when we iterate over all threads and find one
976 that wasn't already in our list. Returns true on success. */
979 attach_thread (ptid_t ptid
, const td_thrhandle_t
*th_p
,
980 const td_thrinfo_t
*ti_p
)
982 struct private_thread_info
*private;
983 struct thread_info
*tp
= NULL
;
985 struct thread_db_info
*info
;
987 /* If we're being called after a TD_CREATE event, we may already
988 know about this thread. There are two ways this can happen. We
989 may have iterated over all threads between the thread creation
990 and the TD_CREATE event, for instance when the user has issued
991 the `info threads' command before the SIGTRAP for hitting the
992 thread creation breakpoint was reported. Alternatively, the
993 thread may have exited and a new one been created with the same
994 thread ID. In the first case we don't need to do anything; in
995 the second case we should discard information about the dead
996 thread and attach to the new one. */
997 if (in_thread_list (ptid
))
999 tp
= find_thread_ptid (ptid
);
1000 gdb_assert (tp
!= NULL
);
1002 /* If tp->private is NULL, then GDB is already attached to this
1003 thread, but we do not know anything about it. We can learn
1004 about it here. This can only happen if we have some other
1005 way besides libthread_db to notice new threads (i.e.
1006 PTRACE_EVENT_CLONE); assume the same mechanism notices thread
1007 exit, so this can not be a stale thread recreated with the
1009 if (tp
->private != NULL
)
1011 if (!tp
->private->dying
)
1014 delete_thread (ptid
);
1019 check_thread_signals ();
1021 if (ti_p
->ti_state
== TD_THR_UNKNOWN
|| ti_p
->ti_state
== TD_THR_ZOMBIE
)
1022 return 0; /* A zombie thread -- do not attach. */
1024 /* Under GNU/Linux, we have to attach to each and every thread. */
1026 && lin_lwp_attach_lwp (BUILD_LWP (ti_p
->ti_lid
, GET_PID (ptid
))) < 0)
1029 /* Construct the thread's private data. */
1030 private = xmalloc (sizeof (struct private_thread_info
));
1031 memset (private, 0, sizeof (struct private_thread_info
));
1033 /* A thread ID of zero may mean the thread library has not initialized
1034 yet. But we shouldn't even get here if that's the case. FIXME:
1035 if we change GDB to always have at least one thread in the thread
1036 list this will have to go somewhere else; maybe private == NULL
1037 until the thread_db target claims it. */
1038 gdb_assert (ti_p
->ti_tid
!= 0);
1039 private->th
= *th_p
;
1040 private->tid
= ti_p
->ti_tid
;
1042 /* Add the thread to GDB's thread list. */
1044 tp
= add_thread_with_info (ptid
, private);
1046 tp
->private = private;
1048 info
= get_thread_db_info (GET_PID (ptid
));
1050 /* Enable thread event reporting for this thread. */
1051 err
= info
->td_thr_event_enable_p (th_p
, 1);
1053 error (_("Cannot enable thread event reporting for %s: %s"),
1054 target_pid_to_str (ptid
), thread_db_err_str (err
));
1059 detach_thread (ptid_t ptid
)
1061 struct thread_info
*thread_info
;
1063 /* Don't delete the thread now, because it still reports as active
1064 until it has executed a few instructions after the event
1065 breakpoint - if we deleted it now, "info threads" would cause us
1066 to re-attach to it. Just mark it as having had a TD_DEATH
1067 event. This means that we won't delete it from our thread list
1068 until we notice that it's dead (via prune_threads), or until
1069 something re-uses its thread ID. We'll report the thread exit
1070 when the underlying LWP dies. */
1071 thread_info
= find_thread_ptid (ptid
);
1072 gdb_assert (thread_info
!= NULL
&& thread_info
->private != NULL
);
1073 thread_info
->private->dying
= 1;
1077 thread_db_detach (struct target_ops
*ops
, char *args
, int from_tty
)
1079 struct target_ops
*target_beneath
= find_target_beneath (ops
);
1080 struct thread_db_info
*info
;
1082 info
= get_thread_db_info (GET_PID (inferior_ptid
));
1086 disable_thread_event_reporting (info
);
1088 /* Delete the old thread event breakpoints. Note that unlike
1089 when mourning, we can remove them here because there's still
1090 a live inferior to poke at. In any case, GDB will not try to
1091 insert anything in the inferior when removing a
1093 remove_thread_event_breakpoints ();
1095 delete_thread_db_info (GET_PID (inferior_ptid
));
1098 target_beneath
->to_detach (target_beneath
, args
, from_tty
);
1100 /* NOTE: From this point on, inferior_ptid is null_ptid. */
1102 /* If there are no more processes using libpthread, detach the
1103 thread_db target ops. */
1104 if (!thread_db_list
)
1105 unpush_target (&thread_db_ops
);
1108 /* Check if PID is currently stopped at the location of a thread event
1109 breakpoint location. If it is, read the event message and act upon
1113 check_event (ptid_t ptid
)
1115 struct regcache
*regcache
= get_thread_regcache (ptid
);
1116 struct gdbarch
*gdbarch
= get_regcache_arch (regcache
);
1122 struct thread_db_info
*info
;
1124 info
= get_thread_db_info (GET_PID (ptid
));
1126 /* Bail out early if we're not at a thread event breakpoint. */
1127 stop_pc
= regcache_read_pc (regcache
)
1128 - gdbarch_decr_pc_after_break (gdbarch
);
1129 if (stop_pc
!= info
->td_create_bp_addr
1130 && stop_pc
!= info
->td_death_bp_addr
)
1133 /* Access an lwp we know is stopped. */
1134 info
->proc_handle
.ptid
= ptid
;
1136 /* If we have only looked at the first thread before libpthread was
1137 initialized, we may not know its thread ID yet. Make sure we do
1138 before we add another thread to the list. */
1139 if (!have_threads (ptid
))
1140 thread_db_find_new_threads_1 (ptid
);
1142 /* If we are at a create breakpoint, we do not know what new lwp
1143 was created and cannot specifically locate the event message for it.
1144 We have to call td_ta_event_getmsg() to get
1145 the latest message. Since we have no way of correlating whether
1146 the event message we get back corresponds to our breakpoint, we must
1147 loop and read all event messages, processing them appropriately.
1148 This guarantees we will process the correct message before continuing
1149 from the breakpoint.
1151 Currently, death events are not enabled. If they are enabled,
1152 the death event can use the td_thr_event_getmsg() interface to
1153 get the message specifically for that lwp and avoid looping
1160 err
= info
->td_ta_event_getmsg_p (info
->thread_agent
, &msg
);
1163 if (err
== TD_NOMSG
)
1166 error (_("Cannot get thread event message: %s"),
1167 thread_db_err_str (err
));
1170 err
= info
->td_thr_get_info_p (msg
.th_p
, &ti
);
1172 error (_("Cannot get thread info: %s"), thread_db_err_str (err
));
1174 ptid
= ptid_build (GET_PID (ptid
), ti
.ti_lid
, 0);
1179 /* Call attach_thread whether or not we already know about a
1180 thread with this thread ID. */
1181 attach_thread (ptid
, msg
.th_p
, &ti
);
1187 if (!in_thread_list (ptid
))
1188 error (_("Spurious thread death event."));
1190 detach_thread (ptid
);
1195 error (_("Spurious thread event."));
1202 thread_db_wait (struct target_ops
*ops
,
1203 ptid_t ptid
, struct target_waitstatus
*ourstatus
,
1206 struct thread_db_info
*info
;
1207 struct target_ops
*beneath
= find_target_beneath (ops
);
1209 ptid
= beneath
->to_wait (beneath
, ptid
, ourstatus
, options
);
1211 if (ourstatus
->kind
== TARGET_WAITKIND_IGNORE
)
1214 if (ourstatus
->kind
== TARGET_WAITKIND_EXITED
1215 || ourstatus
->kind
== TARGET_WAITKIND_SIGNALLED
)
1218 info
= get_thread_db_info (GET_PID (ptid
));
1220 /* If this process isn't using thread_db, we're done. */
1224 if (ourstatus
->kind
== TARGET_WAITKIND_EXECD
)
1226 /* New image, it may or may not end up using thread_db. Assume
1227 not unless we find otherwise. */
1228 delete_thread_db_info (GET_PID (ptid
));
1229 if (!thread_db_list
)
1230 unpush_target (&thread_db_ops
);
1232 /* Thread event breakpoints are deleted by
1233 update_breakpoints_after_exec. */
1238 /* If we do not know about the main thread yet, this would be a good time to
1240 if (ourstatus
->kind
== TARGET_WAITKIND_STOPPED
&& !have_threads (ptid
))
1241 thread_db_find_new_threads_1 (ptid
);
1243 if (ourstatus
->kind
== TARGET_WAITKIND_STOPPED
1244 && ourstatus
->value
.sig
== TARGET_SIGNAL_TRAP
)
1245 /* Check for a thread event. */
1248 if (have_threads (ptid
))
1250 /* Change ptids back into the higher level PID + TID format. If
1251 the thread is dead and no longer on the thread list, we will
1252 get back a dead ptid. This can occur if the thread death
1253 event gets postponed by other simultaneous events. In such a
1254 case, we want to just ignore the event and continue on. */
1256 ptid
= thread_from_lwp (ptid
);
1257 if (GET_PID (ptid
) == -1)
1258 ourstatus
->kind
= TARGET_WAITKIND_SPURIOUS
;
1265 thread_db_mourn_inferior (struct target_ops
*ops
)
1267 struct target_ops
*target_beneath
= find_target_beneath (ops
);
1269 delete_thread_db_info (GET_PID (inferior_ptid
));
1271 target_beneath
->to_mourn_inferior (target_beneath
);
1273 /* Delete the old thread event breakpoints. Do this after mourning
1274 the inferior, so that we don't try to uninsert them. */
1275 remove_thread_event_breakpoints ();
1277 /* Detach thread_db target ops. */
1278 if (!thread_db_list
)
1279 unpush_target (ops
);
1282 struct callback_data
1284 struct thread_db_info
*info
;
1289 find_new_threads_callback (const td_thrhandle_t
*th_p
, void *data
)
1294 struct thread_info
*tp
;
1295 struct callback_data
*cb_data
= data
;
1296 struct thread_db_info
*info
= cb_data
->info
;
1298 err
= info
->td_thr_get_info_p (th_p
, &ti
);
1300 error (_("find_new_threads_callback: cannot get thread info: %s"),
1301 thread_db_err_str (err
));
1303 if (ti
.ti_state
== TD_THR_UNKNOWN
|| ti
.ti_state
== TD_THR_ZOMBIE
)
1304 return 0; /* A zombie -- ignore. */
1308 /* A thread ID of zero means that this is the main thread, but
1309 glibc has not yet initialized thread-local storage and the
1310 pthread library. We do not know what the thread's TID will
1311 be yet. Just enable event reporting and otherwise ignore
1314 /* In that case, we're not stopped in a fork syscall and don't
1315 need this glibc bug workaround. */
1316 info
->need_stale_parent_threads_check
= 0;
1318 err
= info
->td_thr_event_enable_p (th_p
, 1);
1320 error (_("Cannot enable thread event reporting for LWP %d: %s"),
1321 (int) ti
.ti_lid
, thread_db_err_str (err
));
1326 /* Ignore stale parent threads, caused by glibc/BZ5983. This is a
1327 bit expensive, as it needs to open /proc/pid/status, so try to
1328 avoid doing the work if we know we don't have to. */
1329 if (info
->need_stale_parent_threads_check
)
1331 int tgid
= linux_proc_get_tgid (ti
.ti_lid
);
1332 if (tgid
!= -1 && tgid
!= info
->pid
)
1336 ptid
= ptid_build (info
->pid
, ti
.ti_lid
, 0);
1337 tp
= find_thread_ptid (ptid
);
1338 if (tp
== NULL
|| tp
->private == NULL
)
1340 if (attach_thread (ptid
, th_p
, &ti
))
1341 cb_data
->new_threads
+= 1;
1343 /* Problem attaching this thread; perhaps it exited before we
1345 This could mean that the thread list inside glibc itself is in
1346 inconsistent state, and libthread_db could go on looping forever
1347 (observed with glibc-2.3.6). To prevent that, terminate
1348 iteration: thread_db_find_new_threads_2 will retry. */
1355 /* Helper for thread_db_find_new_threads_2.
1356 Returns number of new threads found. */
1359 find_new_threads_once (struct thread_db_info
*info
, int iteration
,
1362 volatile struct gdb_exception except
;
1363 struct callback_data data
;
1364 td_err_e err
= TD_ERR
;
1367 data
.new_threads
= 0;
1369 TRY_CATCH (except
, RETURN_MASK_ERROR
)
1371 /* Iterate over all user-space threads to discover new threads. */
1372 err
= info
->td_ta_thr_iter_p (info
->thread_agent
,
1373 find_new_threads_callback
,
1376 TD_THR_LOWEST_PRIORITY
,
1378 TD_THR_ANY_USER_FLAGS
);
1383 if (except
.reason
< 0)
1384 exception_fprintf (gdb_stderr
, except
,
1385 "Warning: find_new_threads_once: ");
1387 printf_filtered (_("Found %d new threads in iteration %d.\n"),
1388 data
.new_threads
, iteration
);
1394 return data
.new_threads
;
1397 /* Search for new threads, accessing memory through stopped thread
1398 PTID. If UNTIL_NO_NEW is true, repeat searching until several
1399 searches in a row do not discover any new threads. */
1402 thread_db_find_new_threads_2 (ptid_t ptid
, int until_no_new
)
1405 struct lwp_info
*lp
;
1406 struct thread_db_info
*info
;
1407 int pid
= ptid_get_pid (ptid
);
1410 /* In linux, we can only read memory through a stopped lwp. */
1412 if (lp
->stopped
&& ptid_get_pid (lp
->ptid
) == pid
)
1416 /* There is no stopped thread. Bail out. */
1419 info
= get_thread_db_info (GET_PID (ptid
));
1421 /* Access an lwp we know is stopped. */
1422 info
->proc_handle
.ptid
= ptid
;
1426 /* Require 4 successive iterations which do not find any new threads.
1427 The 4 is a heuristic: there is an inherent race here, and I have
1428 seen that 2 iterations in a row are not always sufficient to
1429 "capture" all threads. */
1430 for (i
= 0, loop
= 0; loop
< 4; ++i
, ++loop
)
1431 if (find_new_threads_once (info
, i
, NULL
) != 0)
1432 /* Found some new threads. Restart the loop from beginning. */
1437 find_new_threads_once (info
, 0, &err
);
1439 error (_("Cannot find new threads: %s"), thread_db_err_str (err
));
1444 thread_db_find_new_threads_1 (ptid_t ptid
)
1446 thread_db_find_new_threads_2 (ptid
, 0);
1450 update_thread_core (struct lwp_info
*info
, void *closure
)
1452 info
->core
= linux_nat_core_of_thread_1 (info
->ptid
);
1457 thread_db_find_new_threads (struct target_ops
*ops
)
1459 struct thread_db_info
*info
;
1461 info
= get_thread_db_info (GET_PID (inferior_ptid
));
1466 thread_db_find_new_threads_1 (inferior_ptid
);
1468 iterate_over_lwps (minus_one_ptid
/* iterate over all */,
1469 update_thread_core
, NULL
);
1473 thread_db_pid_to_str (struct target_ops
*ops
, ptid_t ptid
)
1475 struct thread_info
*thread_info
= find_thread_ptid (ptid
);
1476 struct target_ops
*beneath
;
1478 if (thread_info
!= NULL
&& thread_info
->private != NULL
)
1480 static char buf
[64];
1483 tid
= thread_info
->private->tid
;
1484 snprintf (buf
, sizeof (buf
), "Thread 0x%lx (LWP %ld)",
1485 tid
, GET_LWP (ptid
));
1490 beneath
= find_target_beneath (ops
);
1491 if (beneath
->to_pid_to_str (beneath
, ptid
))
1492 return beneath
->to_pid_to_str (beneath
, ptid
);
1494 return normal_pid_to_str (ptid
);
1497 /* Return a string describing the state of the thread specified by
1501 thread_db_extra_thread_info (struct thread_info
*info
)
1503 if (info
->private == NULL
)
1506 if (info
->private->dying
)
1512 /* Get the address of the thread local variable in load module LM which
1513 is stored at OFFSET within the thread local storage for thread PTID. */
1516 thread_db_get_thread_local_address (struct target_ops
*ops
,
1521 struct thread_info
*thread_info
;
1522 struct target_ops
*beneath
;
1524 /* If we have not discovered any threads yet, check now. */
1525 if (!have_threads (ptid
))
1526 thread_db_find_new_threads_1 (ptid
);
1528 /* Find the matching thread. */
1529 thread_info
= find_thread_ptid (ptid
);
1531 if (thread_info
!= NULL
&& thread_info
->private != NULL
)
1535 struct thread_db_info
*info
;
1537 info
= get_thread_db_info (GET_PID (ptid
));
1539 /* glibc doesn't provide the needed interface. */
1540 if (!info
->td_thr_tls_get_addr_p
)
1541 throw_error (TLS_NO_LIBRARY_SUPPORT_ERROR
,
1542 _("No TLS library support"));
1544 /* Caller should have verified that lm != 0. */
1545 gdb_assert (lm
!= 0);
1547 /* Finally, get the address of the variable. */
1548 /* Note the cast through uintptr_t: this interface only works if
1549 a target address fits in a psaddr_t, which is a host pointer.
1550 So a 32-bit debugger can not access 64-bit TLS through this. */
1551 err
= info
->td_thr_tls_get_addr_p (&thread_info
->private->th
,
1552 (psaddr_t
)(uintptr_t) lm
,
1555 #ifdef THREAD_DB_HAS_TD_NOTALLOC
1556 /* The memory hasn't been allocated, yet. */
1557 if (err
== TD_NOTALLOC
)
1558 /* Now, if libthread_db provided the initialization image's
1559 address, we *could* try to build a non-lvalue value from
1560 the initialization image. */
1561 throw_error (TLS_NOT_ALLOCATED_YET_ERROR
,
1562 _("TLS not allocated yet"));
1565 /* Something else went wrong. */
1567 throw_error (TLS_GENERIC_ERROR
,
1568 (("%s")), thread_db_err_str (err
));
1570 /* Cast assuming host == target. Joy. */
1571 /* Do proper sign extension for the target. */
1572 gdb_assert (exec_bfd
);
1573 return (bfd_get_sign_extend_vma (exec_bfd
) > 0
1574 ? (CORE_ADDR
) (intptr_t) address
1575 : (CORE_ADDR
) (uintptr_t) address
);
1578 beneath
= find_target_beneath (ops
);
1579 if (beneath
->to_get_thread_local_address
)
1580 return beneath
->to_get_thread_local_address (beneath
, ptid
, lm
, offset
);
1582 throw_error (TLS_GENERIC_ERROR
,
1583 _("TLS not supported on this target"));
1586 /* Callback routine used to find a thread based on the TID part of
1590 thread_db_find_thread_from_tid (struct thread_info
*thread
, void *data
)
1592 long *tid
= (long *) data
;
1594 if (thread
->private->tid
== *tid
)
1600 /* Implement the to_get_ada_task_ptid target method for this target. */
1603 thread_db_get_ada_task_ptid (long lwp
, long thread
)
1605 struct thread_info
*thread_info
;
1607 thread_db_find_new_threads_1 (inferior_ptid
);
1608 thread_info
= iterate_over_threads (thread_db_find_thread_from_tid
, &thread
);
1610 gdb_assert (thread_info
!= NULL
);
1612 return (thread_info
->ptid
);
1616 thread_db_resume (struct target_ops
*ops
,
1617 ptid_t ptid
, int step
, enum target_signal signo
)
1619 struct target_ops
*beneath
= find_target_beneath (ops
);
1620 struct thread_db_info
*info
;
1622 if (ptid_equal (ptid
, minus_one_ptid
))
1623 info
= get_thread_db_info (GET_PID (inferior_ptid
));
1625 info
= get_thread_db_info (GET_PID (ptid
));
1627 /* This workaround is only needed for child fork lwps stopped in a
1628 PTRACE_O_TRACEFORK event. When the inferior is resumed, the
1629 workaround can be disabled. */
1631 info
->need_stale_parent_threads_check
= 0;
1633 beneath
->to_resume (beneath
, ptid
, step
, signo
);
1637 init_thread_db_ops (void)
1639 thread_db_ops
.to_shortname
= "multi-thread";
1640 thread_db_ops
.to_longname
= "multi-threaded child process.";
1641 thread_db_ops
.to_doc
= "Threads and pthreads support.";
1642 thread_db_ops
.to_detach
= thread_db_detach
;
1643 thread_db_ops
.to_wait
= thread_db_wait
;
1644 thread_db_ops
.to_resume
= thread_db_resume
;
1645 thread_db_ops
.to_mourn_inferior
= thread_db_mourn_inferior
;
1646 thread_db_ops
.to_find_new_threads
= thread_db_find_new_threads
;
1647 thread_db_ops
.to_pid_to_str
= thread_db_pid_to_str
;
1648 thread_db_ops
.to_stratum
= thread_stratum
;
1649 thread_db_ops
.to_has_thread_control
= tc_schedlock
;
1650 thread_db_ops
.to_get_thread_local_address
1651 = thread_db_get_thread_local_address
;
1652 thread_db_ops
.to_extra_thread_info
= thread_db_extra_thread_info
;
1653 thread_db_ops
.to_get_ada_task_ptid
= thread_db_get_ada_task_ptid
;
1654 thread_db_ops
.to_magic
= OPS_MAGIC
;
1657 /* Provide a prototype to silence -Wmissing-prototypes. */
1658 extern initialize_file_ftype _initialize_thread_db
;
1661 _initialize_thread_db (void)
1663 init_thread_db_ops ();
1664 add_target (&thread_db_ops
);
1666 /* Defer loading of libthread_db.so until inferior is running.
1667 This allows gdb to load correct libthread_db for a given
1668 executable -- there could be mutiple versions of glibc,
1669 compiled with LinuxThreads or NPTL, and until there is
1670 a running inferior, we can't tell which libthread_db is
1671 the correct one to load. */
1673 libthread_db_search_path
= xstrdup (LIBTHREAD_DB_SEARCH_PATH
);
1675 add_setshow_optional_filename_cmd ("libthread-db-search-path",
1677 &libthread_db_search_path
, _("\
1678 Set search path for libthread_db."), _("\
1679 Show the current search path or libthread_db."), _("\
1680 This path is used to search for libthread_db to be loaded into \
1684 &setlist
, &showlist
);
1685 /* Add ourselves to objfile event chain. */
1686 observer_attach_new_objfile (thread_db_new_objfile
);