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-osdata.h"
42 #include "auto-load.h"
43 #include "cli/cli-utils.h"
48 /* GNU/Linux libthread_db support.
50 libthread_db is a library, provided along with libpthread.so, which
51 exposes the internals of the thread library to a debugger. It
52 allows GDB to find existing threads, new threads as they are
53 created, thread IDs (usually, the result of pthread_self), and
54 thread-local variables.
56 The libthread_db interface originates on Solaris, where it is
57 both more powerful and more complicated. This implementation
58 only works for LinuxThreads and NPTL, the two glibc threading
59 libraries. It assumes that each thread is permanently assigned
60 to a single light-weight process (LWP).
62 libthread_db-specific information is stored in the "private" field
63 of struct thread_info. When the field is NULL we do not yet have
64 information about the new thread; this could be temporary (created,
65 but the thread library's data structures do not reflect it yet)
66 or permanent (created using clone instead of pthread_create).
68 Process IDs managed by linux-thread-db.c match those used by
69 linux-nat.c: a common PID for all processes, an LWP ID for each
70 thread, and no TID. We save the TID in private. Keeping it out
71 of the ptid_t prevents thread IDs changing when libpthread is
72 loaded or unloaded. */
74 static char *libthread_db_search_path
;
76 /* Set to non-zero if thread_db auto-loading is enabled
77 by the "set auto-load libthread-db" command. */
78 static int auto_load_thread_db
= 1;
80 /* "show" command for the auto_load_thread_db configuration variable. */
83 show_auto_load_thread_db (struct ui_file
*file
, int from_tty
,
84 struct cmd_list_element
*c
, const char *value
)
86 fprintf_filtered (file
, _("Auto-loading of inferior specific libthread_db "
92 set_libthread_db_search_path (char *ignored
, int from_tty
,
93 struct cmd_list_element
*c
)
95 if (*libthread_db_search_path
== '\0')
97 xfree (libthread_db_search_path
);
98 libthread_db_search_path
= xstrdup (LIBTHREAD_DB_SEARCH_PATH
);
102 /* If non-zero, print details of libthread_db processing. */
104 static unsigned int libthread_db_debug
;
107 show_libthread_db_debug (struct ui_file
*file
, int from_tty
,
108 struct cmd_list_element
*c
, const char *value
)
110 fprintf_filtered (file
, _("libthread-db debugging is %s.\n"), value
);
113 /* If we're running on GNU/Linux, we must explicitly attach to any new
116 /* This module's target vector. */
117 static struct target_ops thread_db_ops
;
119 /* Non-zero if we have determined the signals used by the threads
121 static int thread_signals
;
122 static sigset_t thread_stop_set
;
123 static sigset_t thread_print_set
;
125 struct thread_db_info
127 struct thread_db_info
*next
;
129 /* Process id this object refers to. */
132 /* Handle from dlopen for libthread_db.so. */
135 /* Absolute pathname from gdb_realpath to disk file used for dlopen-ing
136 HANDLE. It may be NULL for system library. */
139 /* Structure that identifies the child process for the
140 <proc_service.h> interface. */
141 struct ps_prochandle proc_handle
;
143 /* Connection to the libthread_db library. */
144 td_thragent_t
*thread_agent
;
146 /* True if we need to apply the workaround for glibc/BZ5983. When
147 we catch a PTRACE_O_TRACEFORK, and go query the child's thread
148 list, nptl_db returns the parent's threads in addition to the new
149 (single) child thread. If this flag is set, we do extra work to
150 be able to ignore such stale entries. */
151 int need_stale_parent_threads_check
;
153 /* Location of the thread creation event breakpoint. The code at
154 this location in the child process will be called by the pthread
155 library whenever a new thread is created. By setting a special
156 breakpoint at this location, GDB can detect when a new thread is
157 created. We obtain this location via the td_ta_event_addr
159 CORE_ADDR td_create_bp_addr
;
161 /* Location of the thread death event breakpoint. */
162 CORE_ADDR td_death_bp_addr
;
164 /* Pointers to the libthread_db functions. */
166 td_err_e (*td_init_p
) (void);
168 td_err_e (*td_ta_new_p
) (struct ps_prochandle
* ps
,
170 td_err_e (*td_ta_map_id2thr_p
) (const td_thragent_t
*ta
, thread_t pt
,
171 td_thrhandle_t
*__th
);
172 td_err_e (*td_ta_map_lwp2thr_p
) (const td_thragent_t
*ta
,
173 lwpid_t lwpid
, td_thrhandle_t
*th
);
174 td_err_e (*td_ta_thr_iter_p
) (const td_thragent_t
*ta
,
175 td_thr_iter_f
*callback
, void *cbdata_p
,
176 td_thr_state_e state
, int ti_pri
,
177 sigset_t
*ti_sigmask_p
,
178 unsigned int ti_user_flags
);
179 td_err_e (*td_ta_event_addr_p
) (const td_thragent_t
*ta
,
180 td_event_e event
, td_notify_t
*ptr
);
181 td_err_e (*td_ta_set_event_p
) (const td_thragent_t
*ta
,
182 td_thr_events_t
*event
);
183 td_err_e (*td_ta_clear_event_p
) (const td_thragent_t
*ta
,
184 td_thr_events_t
*event
);
185 td_err_e (*td_ta_event_getmsg_p
) (const td_thragent_t
*ta
,
186 td_event_msg_t
*msg
);
188 td_err_e (*td_thr_validate_p
) (const td_thrhandle_t
*th
);
189 td_err_e (*td_thr_get_info_p
) (const td_thrhandle_t
*th
,
190 td_thrinfo_t
*infop
);
191 td_err_e (*td_thr_event_enable_p
) (const td_thrhandle_t
*th
,
194 td_err_e (*td_thr_tls_get_addr_p
) (const td_thrhandle_t
*th
,
195 psaddr_t map_address
,
196 size_t offset
, psaddr_t
*address
);
197 td_err_e (*td_thr_tlsbase_p
) (const td_thrhandle_t
*th
,
198 unsigned long int modid
,
202 /* List of known processes using thread_db, and the required
204 struct thread_db_info
*thread_db_list
;
206 static void thread_db_find_new_threads_1 (ptid_t ptid
);
207 static void thread_db_find_new_threads_2 (ptid_t ptid
, int until_no_new
);
209 /* Add the current inferior to the list of processes using libpthread.
210 Return a pointer to the newly allocated object that was added to
211 THREAD_DB_LIST. HANDLE is the handle returned by dlopen'ing
214 static struct thread_db_info
*
215 add_thread_db_info (void *handle
)
217 struct thread_db_info
*info
;
219 info
= xcalloc (1, sizeof (*info
));
220 info
->pid
= ptid_get_pid (inferior_ptid
);
221 info
->handle
= handle
;
223 /* The workaround works by reading from /proc/pid/status, so it is
224 disabled for core files. */
225 if (target_has_execution
)
226 info
->need_stale_parent_threads_check
= 1;
228 info
->next
= thread_db_list
;
229 thread_db_list
= info
;
234 /* Return the thread_db_info object representing the bookkeeping
235 related to process PID, if any; NULL otherwise. */
237 static struct thread_db_info
*
238 get_thread_db_info (int pid
)
240 struct thread_db_info
*info
;
242 for (info
= thread_db_list
; info
; info
= info
->next
)
243 if (pid
== info
->pid
)
249 /* When PID has exited or has been detached, we no longer want to keep
250 track of it as using libpthread. Call this function to discard
251 thread_db related info related to PID. Note that this closes
252 LIBTHREAD_DB_SO's dlopen'ed handle. */
255 delete_thread_db_info (int pid
)
257 struct thread_db_info
*info
, *info_prev
;
261 for (info
= thread_db_list
; info
; info_prev
= info
, info
= info
->next
)
262 if (pid
== info
->pid
)
268 if (info
->handle
!= NULL
)
269 dlclose (info
->handle
);
271 xfree (info
->filename
);
274 info_prev
->next
= info
->next
;
276 thread_db_list
= info
->next
;
281 /* Prototypes for local functions. */
282 static int attach_thread (ptid_t ptid
, const td_thrhandle_t
*th_p
,
283 const td_thrinfo_t
*ti_p
);
284 static void detach_thread (ptid_t ptid
);
287 /* Use "struct private_thread_info" to cache thread state. This is
288 a substantial optimization. */
290 struct private_thread_info
292 /* Flag set when we see a TD_DEATH event for this thread. */
293 unsigned int dying
:1;
295 /* Cached thread state. */
302 thread_db_err_str (td_err_e err
)
309 return "generic 'call succeeded'";
311 return "generic error";
313 return "no thread to satisfy query";
315 return "no sync handle to satisfy query";
317 return "no LWP to satisfy query";
319 return "invalid process handle";
321 return "invalid thread handle";
323 return "invalid synchronization handle";
325 return "invalid thread agent";
327 return "invalid key";
329 return "no event message for getmsg";
331 return "FPU register set not available";
333 return "application not linked with libthread";
335 return "requested event is not supported";
337 return "capability not available";
339 return "debugger service failed";
341 return "operation not applicable to";
343 return "no thread-specific data for this thread";
345 return "malloc failed";
347 return "only part of register set was written/read";
349 return "X register set not available for this thread";
350 #ifdef THREAD_DB_HAS_TD_NOTALLOC
352 return "thread has not yet allocated TLS for given module";
354 #ifdef THREAD_DB_HAS_TD_VERSION
356 return "versions of libpthread and libthread_db do not match";
358 #ifdef THREAD_DB_HAS_TD_NOTLS
360 return "there is no TLS segment in the given module";
363 snprintf (buf
, sizeof (buf
), "unknown thread_db error '%d'", err
);
368 /* Return 1 if any threads have been registered. There may be none if
369 the threading library is not fully initialized yet. */
372 have_threads_callback (struct thread_info
*thread
, void *args
)
374 int pid
= * (int *) args
;
376 if (ptid_get_pid (thread
->ptid
) != pid
)
379 return thread
->private != NULL
;
383 have_threads (ptid_t ptid
)
385 int pid
= ptid_get_pid (ptid
);
387 return iterate_over_threads (have_threads_callback
, &pid
) != NULL
;
390 struct thread_get_info_inout
392 struct thread_info
*thread_info
;
393 struct thread_db_info
*thread_db_info
;
396 /* A callback function for td_ta_thr_iter, which we use to map all
399 THP is a handle to the current thread; if INFOP is not NULL, the
400 struct thread_info associated with this thread is returned in
403 If the thread is a zombie, TD_THR_ZOMBIE is returned. Otherwise,
404 zero is returned to indicate success. */
407 thread_get_info_callback (const td_thrhandle_t
*thp
, void *argp
)
412 struct thread_get_info_inout
*inout
;
413 struct thread_db_info
*info
;
416 info
= inout
->thread_db_info
;
418 err
= info
->td_thr_get_info_p (thp
, &ti
);
420 error (_("thread_get_info_callback: cannot get thread info: %s"),
421 thread_db_err_str (err
));
423 /* Fill the cache. */
424 thread_ptid
= ptid_build (info
->pid
, ti
.ti_lid
, 0);
425 inout
->thread_info
= find_thread_ptid (thread_ptid
);
427 if (inout
->thread_info
== NULL
)
429 /* New thread. Attach to it now (why wait?). */
430 if (!have_threads (thread_ptid
))
431 thread_db_find_new_threads_1 (thread_ptid
);
433 attach_thread (thread_ptid
, thp
, &ti
);
434 inout
->thread_info
= find_thread_ptid (thread_ptid
);
435 gdb_assert (inout
->thread_info
!= NULL
);
441 /* Fetch the user-level thread id of PTID. */
444 thread_from_lwp (ptid_t ptid
)
448 struct thread_db_info
*info
;
449 struct thread_get_info_inout io
= {0};
451 /* Just in case td_ta_map_lwp2thr doesn't initialize it completely. */
454 /* This ptid comes from linux-nat.c, which should always fill in the
456 gdb_assert (ptid_get_lwp (ptid
) != 0);
458 info
= get_thread_db_info (ptid_get_pid (ptid
));
460 /* Access an lwp we know is stopped. */
461 info
->proc_handle
.ptid
= ptid
;
462 err
= info
->td_ta_map_lwp2thr_p (info
->thread_agent
, ptid_get_lwp (ptid
),
465 error (_("Cannot find user-level thread for LWP %ld: %s"),
466 ptid_get_lwp (ptid
), thread_db_err_str (err
));
468 /* Long-winded way of fetching the thread info. */
469 io
.thread_db_info
= info
;
470 io
.thread_info
= NULL
;
471 thread_get_info_callback (&th
, &io
);
475 /* Attach to lwp PTID, doing whatever else is required to have this
476 LWP under the debugger's control --- e.g., enabling event
477 reporting. Returns true on success. */
479 thread_db_attach_lwp (ptid_t ptid
)
484 struct thread_db_info
*info
;
486 info
= get_thread_db_info (ptid_get_pid (ptid
));
491 /* This ptid comes from linux-nat.c, which should always fill in the
493 gdb_assert (ptid_get_lwp (ptid
) != 0);
495 /* Access an lwp we know is stopped. */
496 info
->proc_handle
.ptid
= ptid
;
498 /* If we have only looked at the first thread before libpthread was
499 initialized, we may not know its thread ID yet. Make sure we do
500 before we add another thread to the list. */
501 if (!have_threads (ptid
))
502 thread_db_find_new_threads_1 (ptid
);
504 err
= info
->td_ta_map_lwp2thr_p (info
->thread_agent
, ptid_get_lwp (ptid
),
507 /* Cannot find user-level thread. */
510 err
= info
->td_thr_get_info_p (&th
, &ti
);
513 warning (_("Cannot get thread info: %s"), thread_db_err_str (err
));
517 attach_thread (ptid
, &th
, &ti
);
522 verbose_dlsym (void *handle
, const char *name
)
524 void *sym
= dlsym (handle
, name
);
526 warning (_("Symbol \"%s\" not found in libthread_db: %s"),
532 enable_thread_event (int event
, CORE_ADDR
*bp
)
536 struct thread_db_info
*info
;
538 info
= get_thread_db_info (ptid_get_pid (inferior_ptid
));
540 /* Access an lwp we know is stopped. */
541 info
->proc_handle
.ptid
= inferior_ptid
;
543 /* Get the breakpoint address for thread EVENT. */
544 err
= info
->td_ta_event_addr_p (info
->thread_agent
, event
, ¬ify
);
548 /* Set up the breakpoint. */
549 gdb_assert (exec_bfd
);
550 (*bp
) = (gdbarch_convert_from_func_ptr_addr
552 /* Do proper sign extension for the target. */
553 (bfd_get_sign_extend_vma (exec_bfd
) > 0
554 ? (CORE_ADDR
) (intptr_t) notify
.u
.bptaddr
555 : (CORE_ADDR
) (uintptr_t) notify
.u
.bptaddr
),
557 create_thread_event_breakpoint (target_gdbarch (), *bp
);
562 /* Verify inferior's '\0'-terminated symbol VER_SYMBOL starts with "%d.%d" and
563 return 1 if this version is lower (and not equal) to
564 VER_MAJOR_MIN.VER_MINOR_MIN. Return 0 in all other cases. */
567 inferior_has_bug (const char *ver_symbol
, int ver_major_min
, int ver_minor_min
)
569 struct bound_minimal_symbol version_msym
;
570 CORE_ADDR version_addr
;
572 int err
, got
, retval
= 0;
574 version_msym
= lookup_minimal_symbol (ver_symbol
, NULL
, NULL
);
575 if (version_msym
.minsym
== NULL
)
578 version_addr
= BMSYMBOL_VALUE_ADDRESS (version_msym
);
579 got
= target_read_string (version_addr
, &version
, 32, &err
);
580 if (err
== 0 && memchr (version
, 0, got
) == &version
[got
-1])
584 retval
= (sscanf (version
, "%d.%d", &major
, &minor
) == 2
585 && (major
< ver_major_min
586 || (major
== ver_major_min
&& minor
< ver_minor_min
)));
594 enable_thread_event_reporting (void)
596 td_thr_events_t events
;
598 struct thread_db_info
*info
;
600 info
= get_thread_db_info (ptid_get_pid (inferior_ptid
));
602 /* We cannot use the thread event reporting facility if these
603 functions aren't available. */
604 if (info
->td_ta_event_addr_p
== NULL
605 || info
->td_ta_set_event_p
== NULL
606 || info
->td_ta_event_getmsg_p
== NULL
607 || info
->td_thr_event_enable_p
== NULL
)
610 /* Set the process wide mask saying which events we're interested in. */
611 td_event_emptyset (&events
);
612 td_event_addset (&events
, TD_CREATE
);
614 /* There is a bug fixed between linuxthreads 2.1.3 and 2.2 by
615 commit 2e4581e4fba917f1779cd0a010a45698586c190a
616 * manager.c (pthread_exited): Correctly report event as TD_REAP
617 instead of TD_DEATH. Fix comments.
618 where event reporting facility is broken for TD_DEATH events,
619 so don't enable it if we have glibc but a lower version. */
620 if (!inferior_has_bug ("__linuxthreads_version", 2, 2))
621 td_event_addset (&events
, TD_DEATH
);
623 err
= info
->td_ta_set_event_p (info
->thread_agent
, &events
);
626 warning (_("Unable to set global thread event mask: %s"),
627 thread_db_err_str (err
));
631 /* Delete previous thread event breakpoints, if any. */
632 remove_thread_event_breakpoints ();
633 info
->td_create_bp_addr
= 0;
634 info
->td_death_bp_addr
= 0;
636 /* Set up the thread creation event. */
637 err
= enable_thread_event (TD_CREATE
, &info
->td_create_bp_addr
);
640 warning (_("Unable to get location for thread creation breakpoint: %s"),
641 thread_db_err_str (err
));
645 /* Set up the thread death event. */
646 err
= enable_thread_event (TD_DEATH
, &info
->td_death_bp_addr
);
649 warning (_("Unable to get location for thread death breakpoint: %s"),
650 thread_db_err_str (err
));
655 /* Similar as thread_db_find_new_threads_1, but try to silently ignore errors
658 Return 1 if the caller should abort libthread_db initialization. Return 0
662 thread_db_find_new_threads_silently (ptid_t ptid
)
664 volatile struct gdb_exception except
;
666 TRY_CATCH (except
, RETURN_MASK_ERROR
)
668 thread_db_find_new_threads_2 (ptid
, 1);
671 if (except
.reason
< 0)
673 if (libthread_db_debug
)
674 exception_fprintf (gdb_stdlog
, except
,
675 "Warning: thread_db_find_new_threads_silently: ");
677 /* There is a bug fixed between nptl 2.6.1 and 2.7 by
678 commit 7d9d8bd18906fdd17364f372b160d7ab896ce909
679 where calls to td_thr_get_info fail with TD_ERR for statically linked
680 executables if td_thr_get_info is called before glibc has initialized
683 If the nptl bug is NOT present in the inferior and still thread_db
684 reports an error return 1. It means the inferior has corrupted thread
685 list and GDB should fall back only to LWPs.
687 If the nptl bug is present in the inferior return 0 to silently ignore
688 such errors, and let gdb enumerate threads again later. In such case
689 GDB cannot properly display LWPs if the inferior thread list is
690 corrupted. For core files it does not apply, no 'later enumeration'
693 if (!target_has_execution
|| !inferior_has_bug ("nptl_version", 2, 7))
695 exception_fprintf (gdb_stderr
, except
,
696 _("Warning: couldn't activate thread debugging "
697 "using libthread_db: "));
704 /* Lookup a library in which given symbol resides.
705 Note: this is looking in GDB process, not in the inferior.
706 Returns library name, or NULL. */
709 dladdr_to_soname (const void *addr
)
713 if (dladdr (addr
, &info
) != 0)
714 return info
.dli_fname
;
718 /* Attempt to initialize dlopen()ed libthread_db, described by INFO.
720 Failure could happen if libthread_db does not have symbols we expect,
721 or when it refuses to work with the current inferior (e.g. due to
722 version mismatch between libthread_db and libpthread). */
725 try_thread_db_load_1 (struct thread_db_info
*info
)
729 /* Initialize pointers to the dynamic library functions we will use.
730 Essential functions first. */
732 info
->td_init_p
= verbose_dlsym (info
->handle
, "td_init");
733 if (info
->td_init_p
== NULL
)
736 err
= info
->td_init_p ();
739 warning (_("Cannot initialize libthread_db: %s"),
740 thread_db_err_str (err
));
744 info
->td_ta_new_p
= verbose_dlsym (info
->handle
, "td_ta_new");
745 if (info
->td_ta_new_p
== NULL
)
748 /* Initialize the structure that identifies the child process. */
749 info
->proc_handle
.ptid
= inferior_ptid
;
751 /* Now attempt to open a connection to the thread library. */
752 err
= info
->td_ta_new_p (&info
->proc_handle
, &info
->thread_agent
);
755 if (libthread_db_debug
)
756 fprintf_unfiltered (gdb_stdlog
, _("td_ta_new failed: %s\n"),
757 thread_db_err_str (err
));
762 #ifdef THREAD_DB_HAS_TD_VERSION
765 /* The errors above are not unexpected and silently ignored:
766 they just mean we haven't found correct version of
770 warning (_("td_ta_new failed: %s"), thread_db_err_str (err
));
775 info
->td_ta_map_id2thr_p
= verbose_dlsym (info
->handle
, "td_ta_map_id2thr");
776 if (info
->td_ta_map_id2thr_p
== NULL
)
779 info
->td_ta_map_lwp2thr_p
= verbose_dlsym (info
->handle
,
780 "td_ta_map_lwp2thr");
781 if (info
->td_ta_map_lwp2thr_p
== NULL
)
784 info
->td_ta_thr_iter_p
= verbose_dlsym (info
->handle
, "td_ta_thr_iter");
785 if (info
->td_ta_thr_iter_p
== NULL
)
788 info
->td_thr_validate_p
= verbose_dlsym (info
->handle
, "td_thr_validate");
789 if (info
->td_thr_validate_p
== NULL
)
792 info
->td_thr_get_info_p
= verbose_dlsym (info
->handle
, "td_thr_get_info");
793 if (info
->td_thr_get_info_p
== NULL
)
796 /* These are not essential. */
797 info
->td_ta_event_addr_p
= dlsym (info
->handle
, "td_ta_event_addr");
798 info
->td_ta_set_event_p
= dlsym (info
->handle
, "td_ta_set_event");
799 info
->td_ta_clear_event_p
= dlsym (info
->handle
, "td_ta_clear_event");
800 info
->td_ta_event_getmsg_p
= dlsym (info
->handle
, "td_ta_event_getmsg");
801 info
->td_thr_event_enable_p
= dlsym (info
->handle
, "td_thr_event_enable");
802 info
->td_thr_tls_get_addr_p
= dlsym (info
->handle
, "td_thr_tls_get_addr");
803 info
->td_thr_tlsbase_p
= dlsym (info
->handle
, "td_thr_tlsbase");
805 if (thread_db_find_new_threads_silently (inferior_ptid
) != 0)
807 /* Even if libthread_db initializes, if the thread list is
808 corrupted, we'd not manage to list any threads. Better reject this
809 thread_db, and fall back to at least listing LWPs. */
813 printf_unfiltered (_("[Thread debugging using libthread_db enabled]\n"));
815 if (*libthread_db_search_path
|| libthread_db_debug
)
817 struct ui_file
*file
;
820 library
= dladdr_to_soname (*info
->td_ta_new_p
);
822 library
= LIBTHREAD_DB_SO
;
824 /* If we'd print this to gdb_stdout when debug output is
825 disabled, still print it to gdb_stdout if debug output is
826 enabled. User visible output should not depend on debug
828 file
= *libthread_db_search_path
!= '\0' ? gdb_stdout
: gdb_stdlog
;
829 fprintf_unfiltered (file
, _("Using host libthread_db library \"%s\".\n"),
833 /* The thread library was detected. Activate the thread_db target
834 if this is the first process using it. */
835 if (thread_db_list
->next
== NULL
)
836 push_target (&thread_db_ops
);
838 /* Enable event reporting, but not when debugging a core file. */
839 if (target_has_execution
)
840 enable_thread_event_reporting ();
845 /* Attempt to use LIBRARY as libthread_db. LIBRARY could be absolute,
846 relative, or just LIBTHREAD_DB. */
849 try_thread_db_load (const char *library
, int check_auto_load_safe
)
852 struct thread_db_info
*info
;
854 if (libthread_db_debug
)
855 fprintf_unfiltered (gdb_stdlog
,
856 _("Trying host libthread_db library: %s.\n"),
859 if (check_auto_load_safe
)
861 if (access (library
, R_OK
) != 0)
863 /* Do not print warnings by file_is_auto_load_safe if the library does
864 not exist at this place. */
865 if (libthread_db_debug
)
866 fprintf_unfiltered (gdb_stdlog
, _("open failed: %s.\n"),
867 safe_strerror (errno
));
871 if (!file_is_auto_load_safe (library
, _("auto-load: Loading libthread-db "
872 "library \"%s\" from explicit "
878 handle
= dlopen (library
, RTLD_NOW
);
881 if (libthread_db_debug
)
882 fprintf_unfiltered (gdb_stdlog
, _("dlopen failed: %s.\n"), dlerror ());
886 if (libthread_db_debug
&& strchr (library
, '/') == NULL
)
890 td_init
= dlsym (handle
, "td_init");
893 const char *const libpath
= dladdr_to_soname (td_init
);
896 fprintf_unfiltered (gdb_stdlog
, _("Host %s resolved to: %s.\n"),
901 info
= add_thread_db_info (handle
);
903 /* Do not save system library name, that one is always trusted. */
904 if (strchr (library
, '/') != NULL
)
905 info
->filename
= gdb_realpath (library
);
907 if (try_thread_db_load_1 (info
))
910 /* This library "refused" to work on current inferior. */
911 delete_thread_db_info (ptid_get_pid (inferior_ptid
));
915 /* Subroutine of try_thread_db_load_from_pdir to simplify it.
916 Try loading libthread_db in directory(OBJ)/SUBDIR.
917 SUBDIR may be NULL. It may also be something like "../lib64".
918 The result is true for success. */
921 try_thread_db_load_from_pdir_1 (struct objfile
*obj
, const char *subdir
)
923 struct cleanup
*cleanup
;
926 const char *obj_name
= objfile_name (obj
);
928 if (obj_name
[0] != '/')
930 warning (_("Expected absolute pathname for libpthread in the"
931 " inferior, but got %s."), obj_name
);
935 path
= xmalloc (strlen (obj_name
) + (subdir
? strlen (subdir
) + 1 : 0)
936 + 1 + strlen (LIBTHREAD_DB_SO
) + 1);
937 cleanup
= make_cleanup (xfree
, path
);
939 strcpy (path
, obj_name
);
940 cp
= strrchr (path
, '/');
941 /* This should at minimum hit the first character. */
942 gdb_assert (cp
!= NULL
);
949 strcat (cp
, LIBTHREAD_DB_SO
);
951 result
= try_thread_db_load (path
, 1);
953 do_cleanups (cleanup
);
957 /* Handle $pdir in libthread-db-search-path.
958 Look for libthread_db in directory(libpthread)/SUBDIR.
959 SUBDIR may be NULL. It may also be something like "../lib64".
960 The result is true for success. */
963 try_thread_db_load_from_pdir (const char *subdir
)
967 if (!auto_load_thread_db
)
971 if (libpthread_name_p (objfile_name (obj
)))
973 if (try_thread_db_load_from_pdir_1 (obj
, subdir
))
976 /* We may have found the separate-debug-info version of
977 libpthread, and it may live in a directory without a matching
979 if (obj
->separate_debug_objfile_backlink
!= NULL
)
980 return try_thread_db_load_from_pdir_1 (obj
->separate_debug_objfile_backlink
,
989 /* Handle $sdir in libthread-db-search-path.
990 Look for libthread_db in the system dirs, or wherever a plain
991 dlopen(file_without_path) will look.
992 The result is true for success. */
995 try_thread_db_load_from_sdir (void)
997 return try_thread_db_load (LIBTHREAD_DB_SO
, 0);
1000 /* Try to load libthread_db from directory DIR of length DIR_LEN.
1001 The result is true for success. */
1004 try_thread_db_load_from_dir (const char *dir
, size_t dir_len
)
1006 struct cleanup
*cleanup
;
1010 if (!auto_load_thread_db
)
1013 path
= xmalloc (dir_len
+ 1 + strlen (LIBTHREAD_DB_SO
) + 1);
1014 cleanup
= make_cleanup (xfree
, path
);
1016 memcpy (path
, dir
, dir_len
);
1017 path
[dir_len
] = '/';
1018 strcpy (path
+ dir_len
+ 1, LIBTHREAD_DB_SO
);
1020 result
= try_thread_db_load (path
, 1);
1022 do_cleanups (cleanup
);
1026 /* Search libthread_db_search_path for libthread_db which "agrees"
1027 to work on current inferior.
1028 The result is true for success. */
1031 thread_db_load_search (void)
1033 VEC (char_ptr
) *dir_vec
;
1034 struct cleanup
*cleanups
;
1038 dir_vec
= dirnames_to_char_ptr_vec (libthread_db_search_path
);
1039 cleanups
= make_cleanup_free_char_ptr_vec (dir_vec
);
1041 for (i
= 0; VEC_iterate (char_ptr
, dir_vec
, i
, this_dir
); ++i
)
1043 const int pdir_len
= sizeof ("$pdir") - 1;
1044 size_t this_dir_len
;
1046 this_dir_len
= strlen (this_dir
);
1048 if (strncmp (this_dir
, "$pdir", pdir_len
) == 0
1049 && (this_dir
[pdir_len
] == '\0'
1050 || this_dir
[pdir_len
] == '/'))
1052 char *subdir
= NULL
;
1053 struct cleanup
*free_subdir_cleanup
1054 = make_cleanup (null_cleanup
, NULL
);
1056 if (this_dir
[pdir_len
] == '/')
1058 subdir
= xmalloc (strlen (this_dir
));
1059 make_cleanup (xfree
, subdir
);
1060 strcpy (subdir
, this_dir
+ pdir_len
+ 1);
1062 rc
= try_thread_db_load_from_pdir (subdir
);
1063 do_cleanups (free_subdir_cleanup
);
1067 else if (strcmp (this_dir
, "$sdir") == 0)
1069 if (try_thread_db_load_from_sdir ())
1077 if (try_thread_db_load_from_dir (this_dir
, this_dir_len
))
1085 do_cleanups (cleanups
);
1086 if (libthread_db_debug
)
1087 fprintf_unfiltered (gdb_stdlog
,
1088 _("thread_db_load_search returning %d\n"), rc
);
1092 /* Return non-zero if the inferior has a libpthread. */
1095 has_libpthread (void)
1097 struct objfile
*obj
;
1100 if (libpthread_name_p (objfile_name (obj
)))
1106 /* Attempt to load and initialize libthread_db.
1107 Return 1 on success. */
1110 thread_db_load (void)
1112 struct thread_db_info
*info
;
1114 info
= get_thread_db_info (ptid_get_pid (inferior_ptid
));
1119 /* Don't attempt to use thread_db on executables not running
1121 if (!target_has_registers
)
1124 /* Don't attempt to use thread_db for remote targets. */
1125 if (!(target_can_run (¤t_target
) || core_bfd
))
1128 if (thread_db_load_search ())
1131 /* We couldn't find a libthread_db.
1132 If the inferior has a libpthread warn the user. */
1133 if (has_libpthread ())
1135 warning (_("Unable to find libthread_db matching inferior's thread"
1136 " library, thread debugging will not be available."));
1140 /* Either this executable isn't using libpthread at all, or it is
1141 statically linked. Since we can't easily distinguish these two cases,
1142 no warning is issued. */
1147 disable_thread_event_reporting (struct thread_db_info
*info
)
1149 if (info
->td_ta_clear_event_p
!= NULL
)
1151 td_thr_events_t events
;
1153 /* Set the process wide mask saying we aren't interested in any
1155 td_event_fillset (&events
);
1156 info
->td_ta_clear_event_p (info
->thread_agent
, &events
);
1159 info
->td_create_bp_addr
= 0;
1160 info
->td_death_bp_addr
= 0;
1164 check_thread_signals (void)
1166 if (!thread_signals
)
1171 lin_thread_get_thread_signals (&mask
);
1172 sigemptyset (&thread_stop_set
);
1173 sigemptyset (&thread_print_set
);
1175 for (i
= 1; i
< NSIG
; i
++)
1177 if (sigismember (&mask
, i
))
1179 if (signal_stop_update (gdb_signal_from_host (i
), 0))
1180 sigaddset (&thread_stop_set
, i
);
1181 if (signal_print_update (gdb_signal_from_host (i
), 0))
1182 sigaddset (&thread_print_set
, i
);
1189 /* Check whether thread_db is usable. This function is called when
1190 an inferior is created (or otherwise acquired, e.g. attached to)
1191 and when new shared libraries are loaded into a running process. */
1194 check_for_thread_db (void)
1196 /* Do nothing if we couldn't load libthread_db.so.1. */
1197 if (!thread_db_load ())
1201 /* This function is called via the new_objfile observer. */
1204 thread_db_new_objfile (struct objfile
*objfile
)
1206 /* This observer must always be called with inferior_ptid set
1210 /* libpthread with separate debug info has its debug info file already
1211 loaded (and notified without successful thread_db initialization)
1212 the time observer_notify_new_objfile is called for the library itself.
1213 Static executables have their separate debug info loaded already
1214 before the inferior has started. */
1215 && objfile
->separate_debug_objfile_backlink
== NULL
1216 /* Only check for thread_db if we loaded libpthread,
1217 or if this is the main symbol file.
1218 We need to check OBJF_MAINLINE to handle the case of debugging
1219 a statically linked executable AND the symbol file is specified AFTER
1220 the exec file is loaded (e.g., gdb -c core ; file foo).
1221 For dynamically linked executables, libpthread can be near the end
1222 of the list of shared libraries to load, and in an app of several
1223 thousand shared libraries, this can otherwise be painful. */
1224 && ((objfile
->flags
& OBJF_MAINLINE
) != 0
1225 || libpthread_name_p (objfile_name (objfile
))))
1226 check_for_thread_db ();
1230 check_pid_namespace_match (void)
1232 /* Check is only relevant for local targets targets. */
1233 if (target_can_run (¤t_target
))
1235 /* If the child is in a different PID namespace, its idea of its
1236 PID will differ from our idea of its PID. When we scan the
1237 child's thread list, we'll mistakenly think it has no threads
1238 since the thread PID fields won't match the PID we give to
1240 char *our_pid_ns
= linux_proc_pid_get_ns (getpid (), "pid");
1241 char *inferior_pid_ns
= linux_proc_pid_get_ns (
1242 ptid_get_pid (inferior_ptid
), "pid");
1244 if (our_pid_ns
!= NULL
&& inferior_pid_ns
!= NULL
1245 && strcmp (our_pid_ns
, inferior_pid_ns
) != 0)
1247 warning (_ ("Target and debugger are in different PID "
1248 "namespaces; thread lists and other data are "
1249 "likely unreliable"));
1253 xfree (inferior_pid_ns
);
1257 /* This function is called via the inferior_created observer.
1258 This handles the case of debugging statically linked executables. */
1261 thread_db_inferior_created (struct target_ops
*target
, int from_tty
)
1263 check_pid_namespace_match ();
1264 check_for_thread_db ();
1267 /* Attach to a new thread. This function is called when we receive a
1268 TD_CREATE event or when we iterate over all threads and find one
1269 that wasn't already in our list. Returns true on success. */
1272 attach_thread (ptid_t ptid
, const td_thrhandle_t
*th_p
,
1273 const td_thrinfo_t
*ti_p
)
1275 struct private_thread_info
*private;
1276 struct thread_info
*tp
;
1278 struct thread_db_info
*info
;
1280 /* If we're being called after a TD_CREATE event, we may already
1281 know about this thread. There are two ways this can happen. We
1282 may have iterated over all threads between the thread creation
1283 and the TD_CREATE event, for instance when the user has issued
1284 the `info threads' command before the SIGTRAP for hitting the
1285 thread creation breakpoint was reported. Alternatively, the
1286 thread may have exited and a new one been created with the same
1287 thread ID. In the first case we don't need to do anything; in
1288 the second case we should discard information about the dead
1289 thread and attach to the new one. */
1290 tp
= find_thread_ptid (ptid
);
1293 /* If tp->private is NULL, then GDB is already attached to this
1294 thread, but we do not know anything about it. We can learn
1295 about it here. This can only happen if we have some other
1296 way besides libthread_db to notice new threads (i.e.
1297 PTRACE_EVENT_CLONE); assume the same mechanism notices thread
1298 exit, so this can not be a stale thread recreated with the
1300 if (tp
->private != NULL
)
1302 if (!tp
->private->dying
)
1305 delete_thread (ptid
);
1310 if (target_has_execution
)
1311 check_thread_signals ();
1313 /* Under GNU/Linux, we have to attach to each and every thread. */
1314 if (target_has_execution
1319 res
= lin_lwp_attach_lwp (ptid_build (ptid_get_pid (ptid
),
1323 /* Error, stop iterating. */
1328 /* Pretend this thread doesn't exist yet, and keep
1333 /* Otherwise, we sucessfully attached to the thread. */
1336 /* Construct the thread's private data. */
1337 private = xmalloc (sizeof (struct private_thread_info
));
1338 memset (private, 0, sizeof (struct private_thread_info
));
1340 /* A thread ID of zero may mean the thread library has not initialized
1341 yet. But we shouldn't even get here if that's the case. FIXME:
1342 if we change GDB to always have at least one thread in the thread
1343 list this will have to go somewhere else; maybe private == NULL
1344 until the thread_db target claims it. */
1345 gdb_assert (ti_p
->ti_tid
!= 0);
1346 private->th
= *th_p
;
1347 private->tid
= ti_p
->ti_tid
;
1348 if (ti_p
->ti_state
== TD_THR_UNKNOWN
|| ti_p
->ti_state
== TD_THR_ZOMBIE
)
1351 /* Add the thread to GDB's thread list. */
1353 add_thread_with_info (ptid
, private);
1355 tp
->private = private;
1357 info
= get_thread_db_info (ptid_get_pid (ptid
));
1359 /* Enable thread event reporting for this thread, except when
1360 debugging a core file. */
1361 if (target_has_execution
)
1363 err
= info
->td_thr_event_enable_p (th_p
, 1);
1365 error (_("Cannot enable thread event reporting for %s: %s"),
1366 target_pid_to_str (ptid
), thread_db_err_str (err
));
1373 detach_thread (ptid_t ptid
)
1375 struct thread_info
*thread_info
;
1377 /* Don't delete the thread now, because it still reports as active
1378 until it has executed a few instructions after the event
1379 breakpoint - if we deleted it now, "info threads" would cause us
1380 to re-attach to it. Just mark it as having had a TD_DEATH
1381 event. This means that we won't delete it from our thread list
1382 until we notice that it's dead (via prune_threads), or until
1383 something re-uses its thread ID. We'll report the thread exit
1384 when the underlying LWP dies. */
1385 thread_info
= find_thread_ptid (ptid
);
1386 gdb_assert (thread_info
!= NULL
&& thread_info
->private != NULL
);
1387 thread_info
->private->dying
= 1;
1391 thread_db_detach (struct target_ops
*ops
, const char *args
, int from_tty
)
1393 struct target_ops
*target_beneath
= find_target_beneath (ops
);
1394 struct thread_db_info
*info
;
1396 info
= get_thread_db_info (ptid_get_pid (inferior_ptid
));
1400 if (target_has_execution
)
1402 disable_thread_event_reporting (info
);
1404 /* Delete the old thread event breakpoints. Note that
1405 unlike when mourning, we can remove them here because
1406 there's still a live inferior to poke at. In any case,
1407 GDB will not try to insert anything in the inferior when
1408 removing a breakpoint. */
1409 remove_thread_event_breakpoints ();
1412 delete_thread_db_info (ptid_get_pid (inferior_ptid
));
1415 target_beneath
->to_detach (target_beneath
, args
, from_tty
);
1417 /* NOTE: From this point on, inferior_ptid is null_ptid. */
1419 /* If there are no more processes using libpthread, detach the
1420 thread_db target ops. */
1421 if (!thread_db_list
)
1422 unpush_target (&thread_db_ops
);
1425 /* Check if PID is currently stopped at the location of a thread event
1426 breakpoint location. If it is, read the event message and act upon
1430 check_event (ptid_t ptid
)
1432 struct regcache
*regcache
= get_thread_regcache (ptid
);
1433 struct gdbarch
*gdbarch
= get_regcache_arch (regcache
);
1439 struct thread_db_info
*info
;
1441 info
= get_thread_db_info (ptid_get_pid (ptid
));
1443 /* Bail out early if we're not at a thread event breakpoint. */
1444 stop_pc
= regcache_read_pc (regcache
)
1445 - target_decr_pc_after_break (gdbarch
);
1446 if (stop_pc
!= info
->td_create_bp_addr
1447 && stop_pc
!= info
->td_death_bp_addr
)
1450 /* Access an lwp we know is stopped. */
1451 info
->proc_handle
.ptid
= ptid
;
1453 /* If we have only looked at the first thread before libpthread was
1454 initialized, we may not know its thread ID yet. Make sure we do
1455 before we add another thread to the list. */
1456 if (!have_threads (ptid
))
1457 thread_db_find_new_threads_1 (ptid
);
1459 /* If we are at a create breakpoint, we do not know what new lwp
1460 was created and cannot specifically locate the event message for it.
1461 We have to call td_ta_event_getmsg() to get
1462 the latest message. Since we have no way of correlating whether
1463 the event message we get back corresponds to our breakpoint, we must
1464 loop and read all event messages, processing them appropriately.
1465 This guarantees we will process the correct message before continuing
1466 from the breakpoint.
1468 Currently, death events are not enabled. If they are enabled,
1469 the death event can use the td_thr_event_getmsg() interface to
1470 get the message specifically for that lwp and avoid looping
1477 err
= info
->td_ta_event_getmsg_p (info
->thread_agent
, &msg
);
1480 if (err
== TD_NOMSG
)
1483 error (_("Cannot get thread event message: %s"),
1484 thread_db_err_str (err
));
1487 err
= info
->td_thr_get_info_p (msg
.th_p
, &ti
);
1489 error (_("Cannot get thread info: %s"), thread_db_err_str (err
));
1491 ptid
= ptid_build (ptid_get_pid (ptid
), ti
.ti_lid
, 0);
1496 /* Call attach_thread whether or not we already know about a
1497 thread with this thread ID. */
1498 attach_thread (ptid
, msg
.th_p
, &ti
);
1504 if (!in_thread_list (ptid
))
1505 error (_("Spurious thread death event."));
1507 detach_thread (ptid
);
1512 error (_("Spurious thread event."));
1519 thread_db_wait (struct target_ops
*ops
,
1520 ptid_t ptid
, struct target_waitstatus
*ourstatus
,
1523 struct thread_db_info
*info
;
1524 struct target_ops
*beneath
= find_target_beneath (ops
);
1526 ptid
= beneath
->to_wait (beneath
, ptid
, ourstatus
, options
);
1528 if (ourstatus
->kind
== TARGET_WAITKIND_IGNORE
)
1531 if (ourstatus
->kind
== TARGET_WAITKIND_EXITED
1532 || ourstatus
->kind
== TARGET_WAITKIND_SIGNALLED
)
1535 info
= get_thread_db_info (ptid_get_pid (ptid
));
1537 /* If this process isn't using thread_db, we're done. */
1541 if (ourstatus
->kind
== TARGET_WAITKIND_EXECD
)
1543 /* New image, it may or may not end up using thread_db. Assume
1544 not unless we find otherwise. */
1545 delete_thread_db_info (ptid_get_pid (ptid
));
1546 if (!thread_db_list
)
1547 unpush_target (&thread_db_ops
);
1549 /* Thread event breakpoints are deleted by
1550 update_breakpoints_after_exec. */
1555 /* If we do not know about the main thread yet, this would be a good time to
1557 if (ourstatus
->kind
== TARGET_WAITKIND_STOPPED
&& !have_threads (ptid
))
1558 thread_db_find_new_threads_1 (ptid
);
1560 if (ourstatus
->kind
== TARGET_WAITKIND_STOPPED
1561 && ourstatus
->value
.sig
== GDB_SIGNAL_TRAP
)
1562 /* Check for a thread event. */
1565 if (have_threads (ptid
))
1567 /* Fill in the thread's user-level thread id. */
1568 thread_from_lwp (ptid
);
1575 thread_db_mourn_inferior (struct target_ops
*ops
)
1577 struct target_ops
*target_beneath
= find_target_beneath (ops
);
1579 delete_thread_db_info (ptid_get_pid (inferior_ptid
));
1581 target_beneath
->to_mourn_inferior (target_beneath
);
1583 /* Delete the old thread event breakpoints. Do this after mourning
1584 the inferior, so that we don't try to uninsert them. */
1585 remove_thread_event_breakpoints ();
1587 /* Detach thread_db target ops. */
1588 if (!thread_db_list
)
1589 unpush_target (ops
);
1592 struct callback_data
1594 struct thread_db_info
*info
;
1599 find_new_threads_callback (const td_thrhandle_t
*th_p
, void *data
)
1604 struct thread_info
*tp
;
1605 struct callback_data
*cb_data
= data
;
1606 struct thread_db_info
*info
= cb_data
->info
;
1608 err
= info
->td_thr_get_info_p (th_p
, &ti
);
1610 error (_("find_new_threads_callback: cannot get thread info: %s"),
1611 thread_db_err_str (err
));
1613 if (ti
.ti_lid
== -1)
1615 /* A thread with kernel thread ID -1 is either a thread that
1616 exited and was joined, or a thread that is being created but
1617 hasn't started yet, and that is reusing the tcb/stack of a
1618 thread that previously exited and was joined. (glibc marks
1619 terminated and joined threads with kernel thread ID -1. See
1626 /* A thread ID of zero means that this is the main thread, but
1627 glibc has not yet initialized thread-local storage and the
1628 pthread library. We do not know what the thread's TID will
1629 be yet. Just enable event reporting and otherwise ignore
1632 /* In that case, we're not stopped in a fork syscall and don't
1633 need this glibc bug workaround. */
1634 info
->need_stale_parent_threads_check
= 0;
1636 if (target_has_execution
)
1638 err
= info
->td_thr_event_enable_p (th_p
, 1);
1640 error (_("Cannot enable thread event reporting for LWP %d: %s"),
1641 (int) ti
.ti_lid
, thread_db_err_str (err
));
1647 /* Ignore stale parent threads, caused by glibc/BZ5983. This is a
1648 bit expensive, as it needs to open /proc/pid/status, so try to
1649 avoid doing the work if we know we don't have to. */
1650 if (info
->need_stale_parent_threads_check
)
1652 int tgid
= linux_proc_get_tgid (ti
.ti_lid
);
1654 if (tgid
!= -1 && tgid
!= info
->pid
)
1658 ptid
= ptid_build (info
->pid
, ti
.ti_lid
, 0);
1659 tp
= find_thread_ptid (ptid
);
1660 if (tp
== NULL
|| tp
->private == NULL
)
1662 if (attach_thread (ptid
, th_p
, &ti
))
1663 cb_data
->new_threads
+= 1;
1665 /* Problem attaching this thread; perhaps it exited before we
1667 This could mean that the thread list inside glibc itself is in
1668 inconsistent state, and libthread_db could go on looping forever
1669 (observed with glibc-2.3.6). To prevent that, terminate
1670 iteration: thread_db_find_new_threads_2 will retry. */
1677 /* Helper for thread_db_find_new_threads_2.
1678 Returns number of new threads found. */
1681 find_new_threads_once (struct thread_db_info
*info
, int iteration
,
1684 volatile struct gdb_exception except
;
1685 struct callback_data data
;
1686 td_err_e err
= TD_ERR
;
1689 data
.new_threads
= 0;
1691 TRY_CATCH (except
, RETURN_MASK_ERROR
)
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
);
1703 if (libthread_db_debug
)
1705 if (except
.reason
< 0)
1706 exception_fprintf (gdb_stdlog
, except
,
1707 "Warning: find_new_threads_once: ");
1709 fprintf_unfiltered (gdb_stdlog
,
1710 _("Found %d new threads in iteration %d.\n"),
1711 data
.new_threads
, iteration
);
1717 return data
.new_threads
;
1720 /* Search for new threads, accessing memory through stopped thread
1721 PTID. If UNTIL_NO_NEW is true, repeat searching until several
1722 searches in a row do not discover any new threads. */
1725 thread_db_find_new_threads_2 (ptid_t ptid
, int until_no_new
)
1727 td_err_e err
= TD_OK
;
1728 struct thread_db_info
*info
;
1731 info
= get_thread_db_info (ptid_get_pid (ptid
));
1733 /* Access an lwp we know is stopped. */
1734 info
->proc_handle
.ptid
= ptid
;
1738 /* Require 4 successive iterations which do not find any new threads.
1739 The 4 is a heuristic: there is an inherent race here, and I have
1740 seen that 2 iterations in a row are not always sufficient to
1741 "capture" all threads. */
1742 for (i
= 0, loop
= 0; loop
< 4 && err
== TD_OK
; ++i
, ++loop
)
1743 if (find_new_threads_once (info
, i
, &err
) != 0)
1745 /* Found some new threads. Restart the loop from beginning. */
1750 find_new_threads_once (info
, 0, &err
);
1753 error (_("Cannot find new threads: %s"), thread_db_err_str (err
));
1757 thread_db_find_new_threads_1 (ptid_t ptid
)
1759 thread_db_find_new_threads_2 (ptid
, 0);
1763 update_thread_core (struct lwp_info
*info
, void *closure
)
1765 info
->core
= linux_common_core_of_thread (info
->ptid
);
1770 thread_db_update_thread_list (struct target_ops
*ops
)
1772 struct thread_db_info
*info
;
1773 struct inferior
*inf
;
1779 struct thread_info
*thread
;
1784 info
= get_thread_db_info (inf
->pid
);
1788 thread
= any_live_thread_of_process (inf
->pid
);
1789 if (thread
== NULL
|| thread
->executing
)
1792 thread_db_find_new_threads_1 (thread
->ptid
);
1795 if (target_has_execution
)
1796 iterate_over_lwps (minus_one_ptid
/* iterate over all */,
1797 update_thread_core
, NULL
);
1801 thread_db_pid_to_str (struct target_ops
*ops
, ptid_t ptid
)
1803 struct thread_info
*thread_info
= find_thread_ptid (ptid
);
1804 struct target_ops
*beneath
;
1806 if (thread_info
!= NULL
&& thread_info
->private != NULL
)
1808 static char buf
[64];
1811 tid
= thread_info
->private->tid
;
1812 snprintf (buf
, sizeof (buf
), "Thread 0x%lx (LWP %ld)",
1813 tid
, ptid_get_lwp (ptid
));
1818 beneath
= find_target_beneath (ops
);
1819 return beneath
->to_pid_to_str (beneath
, ptid
);
1822 /* Return a string describing the state of the thread specified by
1826 thread_db_extra_thread_info (struct target_ops
*self
,
1827 struct thread_info
*info
)
1829 if (info
->private == NULL
)
1832 if (info
->private->dying
)
1838 /* Get the address of the thread local variable in load module LM which
1839 is stored at OFFSET within the thread local storage for thread PTID. */
1842 thread_db_get_thread_local_address (struct target_ops
*ops
,
1847 struct thread_info
*thread_info
;
1848 struct target_ops
*beneath
;
1850 /* If we have not discovered any threads yet, check now. */
1851 if (!have_threads (ptid
))
1852 thread_db_find_new_threads_1 (ptid
);
1854 /* Find the matching thread. */
1855 thread_info
= find_thread_ptid (ptid
);
1857 if (thread_info
!= NULL
&& thread_info
->private != NULL
)
1861 struct thread_db_info
*info
;
1863 info
= get_thread_db_info (ptid_get_pid (ptid
));
1865 /* Finally, get the address of the variable. */
1868 /* glibc doesn't provide the needed interface. */
1869 if (!info
->td_thr_tls_get_addr_p
)
1870 throw_error (TLS_NO_LIBRARY_SUPPORT_ERROR
,
1871 _("No TLS library support"));
1873 /* Note the cast through uintptr_t: this interface only works if
1874 a target address fits in a psaddr_t, which is a host pointer.
1875 So a 32-bit debugger can not access 64-bit TLS through this. */
1876 err
= info
->td_thr_tls_get_addr_p (&thread_info
->private->th
,
1877 (psaddr_t
)(uintptr_t) lm
,
1882 /* If glibc doesn't provide the needed interface throw an error
1883 that LM is zero - normally cases it should not be. */
1884 if (!info
->td_thr_tlsbase_p
)
1885 throw_error (TLS_LOAD_MODULE_NOT_FOUND_ERROR
,
1886 _("TLS load module not found"));
1888 /* This code path handles the case of -static -pthread executables:
1889 https://sourceware.org/ml/libc-help/2014-03/msg00024.html
1890 For older GNU libc r_debug.r_map is NULL. For GNU libc after
1891 PR libc/16831 due to GDB PR threads/16954 LOAD_MODULE is also NULL.
1892 The constant number 1 depends on GNU __libc_setup_tls
1893 initialization of l_tls_modid to 1. */
1894 err
= info
->td_thr_tlsbase_p (&thread_info
->private->th
,
1896 address
= (char *) address
+ offset
;
1899 #ifdef THREAD_DB_HAS_TD_NOTALLOC
1900 /* The memory hasn't been allocated, yet. */
1901 if (err
== TD_NOTALLOC
)
1902 /* Now, if libthread_db provided the initialization image's
1903 address, we *could* try to build a non-lvalue value from
1904 the initialization image. */
1905 throw_error (TLS_NOT_ALLOCATED_YET_ERROR
,
1906 _("TLS not allocated yet"));
1909 /* Something else went wrong. */
1911 throw_error (TLS_GENERIC_ERROR
,
1912 (("%s")), thread_db_err_str (err
));
1914 /* Cast assuming host == target. Joy. */
1915 /* Do proper sign extension for the target. */
1916 gdb_assert (exec_bfd
);
1917 return (bfd_get_sign_extend_vma (exec_bfd
) > 0
1918 ? (CORE_ADDR
) (intptr_t) address
1919 : (CORE_ADDR
) (uintptr_t) address
);
1922 beneath
= find_target_beneath (ops
);
1923 return beneath
->to_get_thread_local_address (beneath
, ptid
, lm
, offset
);
1926 /* Callback routine used to find a thread based on the TID part of
1930 thread_db_find_thread_from_tid (struct thread_info
*thread
, void *data
)
1932 long *tid
= (long *) data
;
1934 if (thread
->private->tid
== *tid
)
1940 /* Implement the to_get_ada_task_ptid target method for this target. */
1943 thread_db_get_ada_task_ptid (struct target_ops
*self
, long lwp
, long thread
)
1945 struct thread_info
*thread_info
;
1947 thread_db_find_new_threads_1 (inferior_ptid
);
1948 thread_info
= iterate_over_threads (thread_db_find_thread_from_tid
, &thread
);
1950 gdb_assert (thread_info
!= NULL
);
1952 return (thread_info
->ptid
);
1956 thread_db_resume (struct target_ops
*ops
,
1957 ptid_t ptid
, int step
, enum gdb_signal signo
)
1959 struct target_ops
*beneath
= find_target_beneath (ops
);
1960 struct thread_db_info
*info
;
1962 if (ptid_equal (ptid
, minus_one_ptid
))
1963 info
= get_thread_db_info (ptid_get_pid (inferior_ptid
));
1965 info
= get_thread_db_info (ptid_get_pid (ptid
));
1967 /* This workaround is only needed for child fork lwps stopped in a
1968 PTRACE_O_TRACEFORK event. When the inferior is resumed, the
1969 workaround can be disabled. */
1971 info
->need_stale_parent_threads_check
= 0;
1973 beneath
->to_resume (beneath
, ptid
, step
, signo
);
1976 /* qsort helper function for info_auto_load_libthread_db, sort the
1977 thread_db_info pointers primarily by their FILENAME and secondarily by their
1978 PID, both in ascending order. */
1981 info_auto_load_libthread_db_compare (const void *ap
, const void *bp
)
1983 struct thread_db_info
*a
= *(struct thread_db_info
**) ap
;
1984 struct thread_db_info
*b
= *(struct thread_db_info
**) bp
;
1987 retval
= strcmp (a
->filename
, b
->filename
);
1991 return (a
->pid
> b
->pid
) - (a
->pid
- b
->pid
);
1994 /* Implement 'info auto-load libthread-db'. */
1997 info_auto_load_libthread_db (char *args
, int from_tty
)
1999 struct ui_out
*uiout
= current_uiout
;
2000 const char *cs
= args
? args
: "";
2001 struct thread_db_info
*info
, **array
;
2002 unsigned info_count
, unique_filenames
;
2003 size_t max_filename_len
, max_pids_len
, pids_len
;
2004 struct cleanup
*back_to
;
2008 cs
= skip_spaces_const (cs
);
2010 error (_("'info auto-load libthread-db' does not accept any parameters"));
2013 for (info
= thread_db_list
; info
; info
= info
->next
)
2014 if (info
->filename
!= NULL
)
2017 array
= xmalloc (sizeof (*array
) * info_count
);
2018 back_to
= make_cleanup (xfree
, array
);
2021 for (info
= thread_db_list
; info
; info
= info
->next
)
2022 if (info
->filename
!= NULL
)
2023 array
[info_count
++] = info
;
2025 /* Sort ARRAY by filenames and PIDs. */
2027 qsort (array
, info_count
, sizeof (*array
),
2028 info_auto_load_libthread_db_compare
);
2030 /* Calculate the number of unique filenames (rows) and the maximum string
2031 length of PIDs list for the unique filenames (columns). */
2033 unique_filenames
= 0;
2034 max_filename_len
= 0;
2037 for (i
= 0; i
< info_count
; i
++)
2039 int pid
= array
[i
]->pid
;
2040 size_t this_pid_len
;
2042 for (this_pid_len
= 0; pid
!= 0; pid
/= 10)
2045 if (i
== 0 || strcmp (array
[i
- 1]->filename
, array
[i
]->filename
) != 0)
2048 max_filename_len
= max (max_filename_len
,
2049 strlen (array
[i
]->filename
));
2053 pids_len
-= strlen (", ");
2054 max_pids_len
= max (max_pids_len
, pids_len
);
2058 pids_len
+= this_pid_len
+ strlen (", ");
2062 pids_len
-= strlen (", ");
2063 max_pids_len
= max (max_pids_len
, pids_len
);
2066 /* Table header shifted right by preceding "libthread-db: " would not match
2068 if (info_count
> 0 && args
== auto_load_info_scripts_pattern_nl
)
2069 ui_out_text (uiout
, "\n");
2071 make_cleanup_ui_out_table_begin_end (uiout
, 2, unique_filenames
,
2072 "LinuxThreadDbTable");
2074 ui_out_table_header (uiout
, max_filename_len
, ui_left
, "filename",
2076 ui_out_table_header (uiout
, pids_len
, ui_left
, "PIDs", "Pids");
2077 ui_out_table_body (uiout
);
2079 pids
= xmalloc (max_pids_len
+ 1);
2080 make_cleanup (xfree
, pids
);
2082 /* Note I is incremented inside the cycle, not at its end. */
2083 for (i
= 0; i
< info_count
;)
2085 struct cleanup
*chain
= make_cleanup_ui_out_tuple_begin_end (uiout
, NULL
);
2089 ui_out_field_string (uiout
, "filename", info
->filename
);
2092 while (i
< info_count
&& strcmp (info
->filename
, array
[i
]->filename
) == 0)
2094 if (pids_end
!= pids
)
2099 pids_end
+= xsnprintf (pids_end
, &pids
[max_pids_len
+ 1] - pids_end
,
2100 "%u", array
[i
]->pid
);
2101 gdb_assert (pids_end
< &pids
[max_pids_len
+ 1]);
2107 ui_out_field_string (uiout
, "pids", pids
);
2109 ui_out_text (uiout
, "\n");
2110 do_cleanups (chain
);
2113 do_cleanups (back_to
);
2115 if (info_count
== 0)
2116 ui_out_message (uiout
, 0, _("No auto-loaded libthread-db.\n"));
2120 init_thread_db_ops (void)
2122 thread_db_ops
.to_shortname
= "multi-thread";
2123 thread_db_ops
.to_longname
= "multi-threaded child process.";
2124 thread_db_ops
.to_doc
= "Threads and pthreads support.";
2125 thread_db_ops
.to_detach
= thread_db_detach
;
2126 thread_db_ops
.to_wait
= thread_db_wait
;
2127 thread_db_ops
.to_resume
= thread_db_resume
;
2128 thread_db_ops
.to_mourn_inferior
= thread_db_mourn_inferior
;
2129 thread_db_ops
.to_update_thread_list
= thread_db_update_thread_list
;
2130 thread_db_ops
.to_pid_to_str
= thread_db_pid_to_str
;
2131 thread_db_ops
.to_stratum
= thread_stratum
;
2132 thread_db_ops
.to_has_thread_control
= tc_schedlock
;
2133 thread_db_ops
.to_get_thread_local_address
2134 = thread_db_get_thread_local_address
;
2135 thread_db_ops
.to_extra_thread_info
= thread_db_extra_thread_info
;
2136 thread_db_ops
.to_get_ada_task_ptid
= thread_db_get_ada_task_ptid
;
2137 thread_db_ops
.to_magic
= OPS_MAGIC
;
2139 complete_target_initialization (&thread_db_ops
);
2142 /* Provide a prototype to silence -Wmissing-prototypes. */
2143 extern initialize_file_ftype _initialize_thread_db
;
2146 _initialize_thread_db (void)
2148 init_thread_db_ops ();
2150 /* Defer loading of libthread_db.so until inferior is running.
2151 This allows gdb to load correct libthread_db for a given
2152 executable -- there could be mutiple versions of glibc,
2153 compiled with LinuxThreads or NPTL, and until there is
2154 a running inferior, we can't tell which libthread_db is
2155 the correct one to load. */
2157 libthread_db_search_path
= xstrdup (LIBTHREAD_DB_SEARCH_PATH
);
2159 add_setshow_optional_filename_cmd ("libthread-db-search-path",
2161 &libthread_db_search_path
, _("\
2162 Set search path for libthread_db."), _("\
2163 Show the current search path or libthread_db."), _("\
2164 This path is used to search for libthread_db to be loaded into \
2166 Its value is a colon (':') separate list of directories to search.\n\
2167 Setting the search path to an empty list resets it to its default value."),
2168 set_libthread_db_search_path
,
2170 &setlist
, &showlist
);
2172 add_setshow_zuinteger_cmd ("libthread-db", class_maintenance
,
2173 &libthread_db_debug
, _("\
2174 Set libthread-db debugging."), _("\
2175 Show libthread-db debugging."), _("\
2176 When non-zero, libthread-db debugging is enabled."),
2178 show_libthread_db_debug
,
2179 &setdebuglist
, &showdebuglist
);
2181 add_setshow_boolean_cmd ("libthread-db", class_support
,
2182 &auto_load_thread_db
, _("\
2183 Enable or disable auto-loading of inferior specific libthread_db."), _("\
2184 Show whether auto-loading inferior specific libthread_db is enabled."), _("\
2185 If enabled, libthread_db will be searched in 'set libthread-db-search-path'\n\
2186 locations to load libthread_db compatible with the inferior.\n\
2187 Standard system libthread_db still gets loaded even with this option off.\n\
2188 This options has security implications for untrusted inferiors."),
2189 NULL
, show_auto_load_thread_db
,
2190 auto_load_set_cmdlist_get (),
2191 auto_load_show_cmdlist_get ());
2193 add_cmd ("libthread-db", class_info
, info_auto_load_libthread_db
,
2194 _("Print the list of loaded inferior specific libthread_db.\n\
2195 Usage: info auto-load libthread-db"),
2196 auto_load_info_cmdlist_get ());
2198 /* Add ourselves to objfile event chain. */
2199 observer_attach_new_objfile (thread_db_new_objfile
);
2201 /* Add ourselves to inferior_created event chain.
2202 This is needed to handle debugging statically linked programs where
2203 the new_objfile observer won't get called for libpthread. */
2204 observer_attach_inferior_created (thread_db_inferior_created
);