1 /* Multi-threaded debugging support for GNU/Linux (LWP layer).
2 Copyright 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
4 This file is part of GDB.
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
23 #include "gdb_assert.h"
24 #include "gdb_string.h"
27 #ifdef HAVE_TKILL_SYSCALL
29 #include <sys/syscall.h>
31 #include <sys/ptrace.h>
34 #include "gdbthread.h"
40 static int debug_lin_lwp
;
41 extern char *strsignal (int sig
);
43 #include "linux-nat.h"
45 /* On GNU/Linux there are no real LWP's. The closest thing to LWP's
46 are processes sharing the same VM space. A multi-threaded process
47 is basically a group of such processes. However, such a grouping
48 is almost entirely a user-space issue; the kernel doesn't enforce
49 such a grouping at all (this might change in the future). In
50 general, we'll rely on the threads library (i.e. the GNU/Linux
51 Threads library) to provide such a grouping.
53 It is perfectly well possible to write a multi-threaded application
54 without the assistance of a threads library, by using the clone
55 system call directly. This module should be able to give some
56 rudimentary support for debugging such applications if developers
57 specify the CLONE_PTRACE flag in the clone system call, and are
58 using the Linux kernel 2.4 or above.
60 Note that there are some peculiarities in GNU/Linux that affect
63 - In general one should specify the __WCLONE flag to waitpid in
64 order to make it report events for any of the cloned processes
65 (and leave it out for the initial process). However, if a cloned
66 process has exited the exit status is only reported if the
67 __WCLONE flag is absent. Linux kernel 2.4 has a __WALL flag, but
68 we cannot use it since GDB must work on older systems too.
70 - When a traced, cloned process exits and is waited for by the
71 debugger, the kernel reassigns it to the original parent and
72 keeps it around as a "zombie". Somehow, the GNU/Linux Threads
73 library doesn't notice this, which leads to the "zombie problem":
74 When debugged a multi-threaded process that spawns a lot of
75 threads will run out of processes, even if the threads exit,
76 because the "zombies" stay around. */
78 /* List of known LWPs. */
79 static struct lwp_info
*lwp_list
;
81 /* Number of LWPs in the list. */
84 /* Non-zero if we're running in "threaded" mode. */
88 #define GET_LWP(ptid) ptid_get_lwp (ptid)
89 #define GET_PID(ptid) ptid_get_pid (ptid)
90 #define is_lwp(ptid) (GET_LWP (ptid) != 0)
91 #define BUILD_LWP(lwp, pid) ptid_build (pid, lwp, 0)
93 /* If the last reported event was a SIGTRAP, this variable is set to
94 the process id of the LWP/thread that got it. */
98 /* This module's target-specific operations. */
99 static struct target_ops lin_lwp_ops
;
101 /* The standard child operations. */
102 extern struct target_ops child_ops
;
104 /* Since we cannot wait (in lin_lwp_wait) for the initial process and
105 any cloned processes with a single call to waitpid, we have to use
106 the WNOHANG flag and call waitpid in a loop. To optimize
107 things a bit we use `sigsuspend' to wake us up when a process has
108 something to report (it will send us a SIGCHLD if it has). To make
109 this work we have to juggle with the signal mask. We save the
110 original signal mask such that we can restore it before creating a
111 new process in order to avoid blocking certain signals in the
112 inferior. We then block SIGCHLD during the waitpid/sigsuspend
115 /* Original signal mask. */
116 static sigset_t normal_mask
;
118 /* Signal mask for use with sigsuspend in lin_lwp_wait, initialized in
119 _initialize_lin_lwp. */
120 static sigset_t suspend_mask
;
122 /* Signals to block to make that sigsuspend work. */
123 static sigset_t blocked_mask
;
126 /* Prototypes for local functions. */
127 static int stop_wait_callback (struct lwp_info
*lp
, void *data
);
128 static int lin_lwp_thread_alive (ptid_t ptid
);
130 /* Convert wait status STATUS to a string. Used for printing debug
134 status_to_str (int status
)
138 if (WIFSTOPPED (status
))
139 snprintf (buf
, sizeof (buf
), "%s (stopped)",
140 strsignal (WSTOPSIG (status
)));
141 else if (WIFSIGNALED (status
))
142 snprintf (buf
, sizeof (buf
), "%s (terminated)",
143 strsignal (WSTOPSIG (status
)));
145 snprintf (buf
, sizeof (buf
), "%d (exited)", WEXITSTATUS (status
));
150 /* Initialize the list of LWPs. Note that this module, contrary to
151 what GDB's generic threads layer does for its thread list,
152 re-initializes the LWP lists whenever we mourn or detach (which
153 doesn't involve mourning) the inferior. */
158 struct lwp_info
*lp
, *lpnext
;
160 for (lp
= lwp_list
; lp
; lp
= lpnext
)
171 /* Add the LWP specified by PID to the list. If this causes the
172 number of LWPs to become larger than one, go into "threaded" mode.
173 Return a pointer to the structure describing the new LWP. */
175 static struct lwp_info
*
176 add_lwp (ptid_t ptid
)
180 gdb_assert (is_lwp (ptid
));
182 lp
= (struct lwp_info
*) xmalloc (sizeof (struct lwp_info
));
184 memset (lp
, 0, sizeof (struct lwp_info
));
196 /* Remove the LWP specified by PID from the list. */
199 delete_lwp (ptid_t ptid
)
201 struct lwp_info
*lp
, *lpprev
;
205 for (lp
= lwp_list
; lp
; lpprev
= lp
, lp
= lp
->next
)
206 if (ptid_equal (lp
->ptid
, ptid
))
212 /* We don't go back to "non-threaded" mode if the number of threads
213 becomes less than two. */
217 lpprev
->next
= lp
->next
;
224 /* Return a pointer to the structure describing the LWP corresponding
225 to PID. If no corresponding LWP could be found, return NULL. */
227 static struct lwp_info
*
228 find_lwp_pid (ptid_t ptid
)
234 lwp
= GET_LWP (ptid
);
236 lwp
= GET_PID (ptid
);
238 for (lp
= lwp_list
; lp
; lp
= lp
->next
)
239 if (lwp
== GET_LWP (lp
->ptid
))
245 /* Call CALLBACK with its second argument set to DATA for every LWP in
246 the list. If CALLBACK returns 1 for a particular LWP, return a
247 pointer to the structure describing that LWP immediately.
248 Otherwise return NULL. */
251 iterate_over_lwps (int (*callback
) (struct lwp_info
*, void *), void *data
)
253 struct lwp_info
*lp
, *lpnext
;
255 for (lp
= lwp_list
; lp
; lp
= lpnext
)
258 if ((*callback
) (lp
, data
))
268 lin_lwp_open (char *args
, int from_tty
)
270 push_target (&lin_lwp_ops
);
274 /* Attach to the LWP specified by PID. If VERBOSE is non-zero, print
275 a message telling the user that a new LWP has been added to the
279 lin_lwp_attach_lwp (ptid_t ptid
, int verbose
)
283 gdb_assert (is_lwp (ptid
));
285 /* Make sure SIGCHLD is blocked. We don't want SIGCHLD events
286 to interrupt either the ptrace() or waitpid() calls below. */
287 if (!sigismember (&blocked_mask
, SIGCHLD
))
289 sigaddset (&blocked_mask
, SIGCHLD
);
290 sigprocmask (SIG_BLOCK
, &blocked_mask
, NULL
);
294 printf_filtered ("[New %s]\n", target_pid_to_str (ptid
));
296 lp
= find_lwp_pid (ptid
);
300 /* We assume that we're already attached to any LWP that has an
301 id equal to the overall process id. */
302 if (GET_LWP (ptid
) != GET_PID (ptid
))
307 if (ptrace (PTRACE_ATTACH
, GET_LWP (ptid
), 0, 0) < 0)
308 error ("Can't attach %s: %s", target_pid_to_str (ptid
),
309 safe_strerror (errno
));
312 fprintf_unfiltered (gdb_stdlog
,
313 "LLAL: PTRACE_ATTACH %s, 0, 0 (OK)\n",
314 target_pid_to_str (ptid
));
316 pid
= waitpid (GET_LWP (ptid
), &status
, 0);
317 if (pid
== -1 && errno
== ECHILD
)
319 /* Try again with __WCLONE to check cloned processes. */
320 pid
= waitpid (GET_LWP (ptid
), &status
, __WCLONE
);
324 gdb_assert (pid
== GET_LWP (ptid
)
325 && WIFSTOPPED (status
) && WSTOPSIG (status
));
327 child_post_attach (pid
);
333 fprintf_unfiltered (gdb_stdlog
,
334 "LLAL: waitpid %s received %s\n",
335 target_pid_to_str (ptid
),
336 status_to_str (status
));
341 /* We assume that the LWP representing the original process
342 is already stopped. Mark it as stopped in the data structure
343 that the lin-lwp layer uses to keep track of threads. Note
344 that this won't have already been done since the main thread
345 will have, we assume, been stopped by an attach from a
352 lin_lwp_attach (char *args
, int from_tty
)
358 /* FIXME: We should probably accept a list of process id's, and
359 attach all of them. */
360 child_ops
.to_attach (args
, from_tty
);
362 /* Add the initial process as the first LWP to the list. */
363 lp
= add_lwp (BUILD_LWP (GET_PID (inferior_ptid
), GET_PID (inferior_ptid
)));
365 /* Make sure the initial process is stopped. The user-level threads
366 layer might want to poke around in the inferior, and that won't
367 work if things haven't stabilized yet. */
368 pid
= waitpid (GET_PID (inferior_ptid
), &status
, 0);
369 if (pid
== -1 && errno
== ECHILD
)
371 warning ("%s is a cloned process", target_pid_to_str (inferior_ptid
));
373 /* Try again with __WCLONE to check cloned processes. */
374 pid
= waitpid (GET_PID (inferior_ptid
), &status
, __WCLONE
);
378 gdb_assert (pid
== GET_PID (inferior_ptid
)
379 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGSTOP
);
383 /* Fake the SIGSTOP that core GDB expects. */
384 lp
->status
= W_STOPCODE (SIGSTOP
);
388 fprintf_unfiltered (gdb_stdlog
,
389 "LLA: waitpid %ld, faking SIGSTOP\n", (long) pid
);
394 detach_callback (struct lwp_info
*lp
, void *data
)
396 gdb_assert (lp
->status
== 0 || WIFSTOPPED (lp
->status
));
398 if (debug_lin_lwp
&& lp
->status
)
399 fprintf_unfiltered (gdb_stdlog
, "DC: Pending %s for %s on detach.\n",
400 strsignal (WSTOPSIG (lp
->status
)),
401 target_pid_to_str (lp
->ptid
));
403 while (lp
->signalled
&& lp
->stopped
)
406 if (ptrace (PTRACE_CONT
, GET_LWP (lp
->ptid
), 0,
407 WSTOPSIG (lp
->status
)) < 0)
408 error ("Can't continue %s: %s", target_pid_to_str (lp
->ptid
),
409 safe_strerror (errno
));
412 fprintf_unfiltered (gdb_stdlog
,
413 "DC: PTRACE_CONTINUE (%s, 0, %s) (OK)\n",
414 target_pid_to_str (lp
->ptid
),
415 status_to_str (lp
->status
));
420 stop_wait_callback (lp
, NULL
);
422 gdb_assert (lp
->status
== 0 || WIFSTOPPED (lp
->status
));
425 /* We don't actually detach from the LWP that has an id equal to the
426 overall process id just yet. */
427 if (GET_LWP (lp
->ptid
) != GET_PID (lp
->ptid
))
430 if (ptrace (PTRACE_DETACH
, GET_LWP (lp
->ptid
), 0,
431 WSTOPSIG (lp
->status
)) < 0)
432 error ("Can't detach %s: %s", target_pid_to_str (lp
->ptid
),
433 safe_strerror (errno
));
436 fprintf_unfiltered (gdb_stdlog
,
437 "PTRACE_DETACH (%s, %s, 0) (OK)\n",
438 target_pid_to_str (lp
->ptid
),
439 strsignal (WSTOPSIG (lp
->status
)));
441 delete_lwp (lp
->ptid
);
448 lin_lwp_detach (char *args
, int from_tty
)
450 iterate_over_lwps (detach_callback
, NULL
);
452 /* Only the initial process should be left right now. */
453 gdb_assert (num_lwps
== 1);
455 trap_ptid
= null_ptid
;
457 /* Destroy LWP info; it's no longer valid. */
460 /* Restore the original signal mask. */
461 sigprocmask (SIG_SETMASK
, &normal_mask
, NULL
);
462 sigemptyset (&blocked_mask
);
464 inferior_ptid
= pid_to_ptid (GET_PID (inferior_ptid
));
465 child_ops
.to_detach (args
, from_tty
);
472 resume_callback (struct lwp_info
*lp
, void *data
)
474 if (lp
->stopped
&& lp
->status
== 0)
476 struct thread_info
*tp
;
478 child_resume (pid_to_ptid (GET_LWP (lp
->ptid
)), 0, TARGET_SIGNAL_0
);
480 fprintf_unfiltered (gdb_stdlog
,
481 "RC: PTRACE_CONT %s, 0, 0 (resume sibling)\n",
482 target_pid_to_str (lp
->ptid
));
491 resume_clear_callback (struct lwp_info
*lp
, void *data
)
498 resume_set_callback (struct lwp_info
*lp
, void *data
)
505 lin_lwp_resume (ptid_t ptid
, int step
, enum target_signal signo
)
510 /* A specific PTID means `step only this process id'. */
511 resume_all
= (PIDGET (ptid
) == -1);
514 iterate_over_lwps (resume_set_callback
, NULL
);
516 iterate_over_lwps (resume_clear_callback
, NULL
);
518 /* If PID is -1, it's the current inferior that should be
519 handled specially. */
520 if (PIDGET (ptid
) == -1)
521 ptid
= inferior_ptid
;
523 lp
= find_lwp_pid (ptid
);
526 ptid
= pid_to_ptid (GET_LWP (lp
->ptid
));
528 /* Remember if we're stepping. */
531 /* Mark this LWP as resumed. */
534 /* If we have a pending wait status for this thread, there is no
535 point in resuming the process. */
538 /* FIXME: What should we do if we are supposed to continue
539 this thread with a signal? */
540 gdb_assert (signo
== TARGET_SIGNAL_0
);
544 /* Mark LWP as not stopped to prevent it from being continued by
550 iterate_over_lwps (resume_callback
, NULL
);
552 child_resume (ptid
, step
, signo
);
554 fprintf_unfiltered (gdb_stdlog
,
555 "LLR: %s %s, %s (resume event thread)\n",
556 step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
557 target_pid_to_str (ptid
),
558 signo
? strsignal (signo
) : "0");
562 /* Issue kill to specified lwp. */
564 static int tkill_failed
;
567 kill_lwp (int lwpid
, int signo
)
571 /* Use tkill, if possible, in case we are using nptl threads. If tkill
572 fails, then we are not using nptl threads and we should be using kill. */
574 #ifdef HAVE_TKILL_SYSCALL
577 int ret
= syscall (__NR_tkill
, lwpid
, signo
);
585 return kill (lwpid
, signo
);
588 /* Wait for LP to stop. Returns the wait status, or 0 if the LWP has
592 wait_lwp (struct lwp_info
*lp
)
598 gdb_assert (!lp
->stopped
);
599 gdb_assert (lp
->status
== 0);
601 pid
= waitpid (GET_LWP (lp
->ptid
), &status
, 0);
602 if (pid
== -1 && errno
== ECHILD
)
604 pid
= waitpid (GET_LWP (lp
->ptid
), &status
, __WCLONE
);
605 if (pid
== -1 && errno
== ECHILD
)
607 /* The thread has previously exited. We need to delete it now
608 because in the case of NPTL threads, there won't be an
609 exit event unless it is the main thread. */
612 fprintf_unfiltered (gdb_stdlog
, "WL: %s vanished.\n",
613 target_pid_to_str (lp
->ptid
));
619 gdb_assert (pid
== GET_LWP (lp
->ptid
));
623 fprintf_unfiltered (gdb_stdlog
,
624 "WL: waitpid %s received %s\n",
625 target_pid_to_str (lp
->ptid
),
626 status_to_str (status
));
630 /* Check if the thread has exited. */
631 if (WIFEXITED (status
) || WIFSIGNALED (status
))
635 fprintf_unfiltered (gdb_stdlog
, "WL: %s exited.\n",
636 target_pid_to_str (lp
->ptid
));
641 if (in_thread_list (lp
->ptid
))
643 /* Core GDB cannot deal with us deleting the current thread. */
644 if (!ptid_equal (lp
->ptid
, inferior_ptid
))
645 delete_thread (lp
->ptid
);
646 printf_unfiltered ("[%s exited]\n",
647 target_pid_to_str (lp
->ptid
));
650 delete_lwp (lp
->ptid
);
654 gdb_assert (WIFSTOPPED (status
));
659 /* Send a SIGSTOP to LP. */
662 stop_callback (struct lwp_info
*lp
, void *data
)
664 if (!lp
->stopped
&& !lp
->signalled
)
670 fprintf_unfiltered (gdb_stdlog
,
671 "SC: kill %s **<SIGSTOP>**\n",
672 target_pid_to_str (lp
->ptid
));
675 ret
= kill_lwp (GET_LWP (lp
->ptid
), SIGSTOP
);
678 fprintf_unfiltered (gdb_stdlog
,
679 "SC: lwp kill %d %s\n",
681 errno
? safe_strerror (errno
) : "ERRNO-OK");
685 gdb_assert (lp
->status
== 0);
691 /* Wait until LP is stopped. If DATA is non-null it is interpreted as
692 a pointer to a set of signals to be flushed immediately. */
695 stop_wait_callback (struct lwp_info
*lp
, void *data
)
697 sigset_t
*flush_mask
= data
;
699 if (!lp
->stopped
&& lp
->signalled
)
703 status
= wait_lwp (lp
);
707 /* Ignore any signals in FLUSH_MASK. */
708 if (flush_mask
&& sigismember (flush_mask
, WSTOPSIG (status
)))
711 ptrace (PTRACE_CONT
, GET_LWP (lp
->ptid
), 0, 0);
713 fprintf_unfiltered (gdb_stdlog
,
714 "PTRACE_CONT %s, 0, 0 (%s)\n",
715 target_pid_to_str (lp
->ptid
),
716 errno
? safe_strerror (errno
) : "OK");
718 return stop_wait_callback (lp
, flush_mask
);
721 if (WSTOPSIG (status
) != SIGSTOP
)
723 if (WSTOPSIG (status
) == SIGTRAP
)
725 /* If a LWP other than the LWP that we're reporting an
726 event for has hit a GDB breakpoint (as opposed to
727 some random trap signal), then just arrange for it to
728 hit it again later. We don't keep the SIGTRAP status
729 and don't forward the SIGTRAP signal to the LWP. We
730 will handle the current event, eventually we will
731 resume all LWPs, and this one will get its breakpoint
734 If we do not do this, then we run the risk that the
735 user will delete or disable the breakpoint, but the
736 thread will have already tripped on it. */
738 /* Now resume this LWP and get the SIGSTOP event. */
740 ptrace (PTRACE_CONT
, GET_LWP (lp
->ptid
), 0, 0);
743 fprintf_unfiltered (gdb_stdlog
,
744 "PTRACE_CONT %s, 0, 0 (%s)\n",
745 target_pid_to_str (lp
->ptid
),
746 errno
? safe_strerror (errno
) : "OK");
748 fprintf_unfiltered (gdb_stdlog
,
749 "SWC: Candidate SIGTRAP event in %s\n",
750 target_pid_to_str (lp
->ptid
));
752 /* Hold the SIGTRAP for handling by lin_lwp_wait. */
753 stop_wait_callback (lp
, data
);
754 /* If there's another event, throw it back into the queue. */
759 fprintf_unfiltered (gdb_stdlog
,
760 "SWC: kill %s, %s\n",
761 target_pid_to_str (lp
->ptid
),
762 status_to_str ((int) status
));
764 kill_lwp (GET_LWP (lp
->ptid
), WSTOPSIG (lp
->status
));
766 /* Save the sigtrap event. */
772 /* The thread was stopped with a signal other than
773 SIGSTOP, and didn't accidentally trip a breakpoint. */
777 fprintf_unfiltered (gdb_stdlog
,
778 "SWC: Pending event %s in %s\n",
779 status_to_str ((int) status
),
780 target_pid_to_str (lp
->ptid
));
782 /* Now resume this LWP and get the SIGSTOP event. */
784 ptrace (PTRACE_CONT
, GET_LWP (lp
->ptid
), 0, 0);
786 fprintf_unfiltered (gdb_stdlog
,
787 "SWC: PTRACE_CONT %s, 0, 0 (%s)\n",
788 target_pid_to_str (lp
->ptid
),
789 errno
? safe_strerror (errno
) : "OK");
791 /* Hold this event/waitstatus while we check to see if
792 there are any more (we still want to get that SIGSTOP). */
793 stop_wait_callback (lp
, data
);
794 /* If the lp->status field is still empty, use it to hold
795 this event. If not, then this event must be returned
796 to the event queue of the LWP. */
803 fprintf_unfiltered (gdb_stdlog
,
804 "SWC: kill %s, %s\n",
805 target_pid_to_str (lp
->ptid
),
806 status_to_str ((int) status
));
808 kill_lwp (GET_LWP (lp
->ptid
), WSTOPSIG (status
));
815 /* We caught the SIGSTOP that we intended to catch, so
816 there's no SIGSTOP pending. */
825 /* Return non-zero if LP has a wait status pending. */
828 status_callback (struct lwp_info
*lp
, void *data
)
830 /* Only report a pending wait status if we pretend that this has
831 indeed been resumed. */
832 return (lp
->status
!= 0 && lp
->resumed
);
835 /* Return non-zero if LP isn't stopped. */
838 running_callback (struct lwp_info
*lp
, void *data
)
840 return (lp
->stopped
== 0);
843 /* Count the LWP's that have had events. */
846 count_events_callback (struct lwp_info
*lp
, void *data
)
850 gdb_assert (count
!= NULL
);
852 /* Count only LWPs that have a SIGTRAP event pending. */
854 && WIFSTOPPED (lp
->status
) && WSTOPSIG (lp
->status
) == SIGTRAP
)
860 /* Select the LWP (if any) that is currently being single-stepped. */
863 select_singlestep_lwp_callback (struct lwp_info
*lp
, void *data
)
865 if (lp
->step
&& lp
->status
!= 0)
871 /* Select the Nth LWP that has had a SIGTRAP event. */
874 select_event_lwp_callback (struct lwp_info
*lp
, void *data
)
876 int *selector
= data
;
878 gdb_assert (selector
!= NULL
);
880 /* Select only LWPs that have a SIGTRAP event pending. */
882 && WIFSTOPPED (lp
->status
) && WSTOPSIG (lp
->status
) == SIGTRAP
)
883 if ((*selector
)-- == 0)
890 cancel_breakpoints_callback (struct lwp_info
*lp
, void *data
)
892 struct lwp_info
*event_lp
= data
;
894 /* Leave the LWP that has been elected to receive a SIGTRAP alone. */
898 /* If a LWP other than the LWP that we're reporting an event for has
899 hit a GDB breakpoint (as opposed to some random trap signal),
900 then just arrange for it to hit it again later. We don't keep
901 the SIGTRAP status and don't forward the SIGTRAP signal to the
902 LWP. We will handle the current event, eventually we will resume
903 all LWPs, and this one will get its breakpoint trap again.
905 If we do not do this, then we run the risk that the user will
906 delete or disable the breakpoint, but the LWP will have already
910 && WIFSTOPPED (lp
->status
) && WSTOPSIG (lp
->status
) == SIGTRAP
911 && breakpoint_inserted_here_p (read_pc_pid (lp
->ptid
) -
912 DECR_PC_AFTER_BREAK
))
915 fprintf_unfiltered (gdb_stdlog
,
916 "CBC: Push back breakpoint for %s\n",
917 target_pid_to_str (lp
->ptid
));
919 /* Back up the PC if necessary. */
920 if (DECR_PC_AFTER_BREAK
)
921 write_pc_pid (read_pc_pid (lp
->ptid
) - DECR_PC_AFTER_BREAK
, lp
->ptid
);
923 /* Throw away the SIGTRAP. */
930 /* Select one LWP out of those that have events pending. */
933 select_event_lwp (struct lwp_info
**orig_lp
, int *status
)
937 struct lwp_info
*event_lp
;
939 /* Record the wait status for the origional LWP. */
940 (*orig_lp
)->status
= *status
;
942 /* Give preference to any LWP that is being single-stepped. */
943 event_lp
= iterate_over_lwps (select_singlestep_lwp_callback
, NULL
);
944 if (event_lp
!= NULL
)
947 fprintf_unfiltered (gdb_stdlog
,
948 "SEL: Select single-step %s\n",
949 target_pid_to_str (event_lp
->ptid
));
953 /* No single-stepping LWP. Select one at random, out of those
954 which have had SIGTRAP events. */
956 /* First see how many SIGTRAP events we have. */
957 iterate_over_lwps (count_events_callback
, &num_events
);
959 /* Now randomly pick a LWP out of those that have had a SIGTRAP. */
960 random_selector
= (int)
961 ((num_events
* (double) rand ()) / (RAND_MAX
+ 1.0));
963 if (debug_lin_lwp
&& num_events
> 1)
964 fprintf_unfiltered (gdb_stdlog
,
965 "SEL: Found %d SIGTRAP events, selecting #%d\n",
966 num_events
, random_selector
);
968 event_lp
= iterate_over_lwps (select_event_lwp_callback
,
972 if (event_lp
!= NULL
)
974 /* Switch the event LWP. */
976 *status
= event_lp
->status
;
979 /* Flush the wait status for the event LWP. */
980 (*orig_lp
)->status
= 0;
983 /* Return non-zero if LP has been resumed. */
986 resumed_callback (struct lwp_info
*lp
, void *data
)
993 /* We need to override child_wait to support attaching to cloned
994 processes, since a normal wait (as done by the default version)
995 ignores those processes. */
997 /* Wait for child PTID to do something. Return id of the child,
998 minus_one_ptid in case of error; store status into *OURSTATUS. */
1001 child_wait (ptid_t ptid
, struct target_waitstatus
*ourstatus
)
1009 set_sigint_trap (); /* Causes SIGINT to be passed on to the
1010 attached process. */
1013 pid
= waitpid (GET_PID (ptid
), &status
, 0);
1014 if (pid
== -1 && errno
== ECHILD
)
1015 /* Try again with __WCLONE to check cloned processes. */
1016 pid
= waitpid (GET_PID (ptid
), &status
, __WCLONE
);
1020 fprintf_unfiltered (gdb_stdlog
,
1021 "CW: waitpid %ld received %s\n",
1022 (long) pid
, status_to_str (status
));
1027 /* Make sure we don't report an event for the exit of the
1028 original program, if we've detached from it. */
1029 if (pid
!= -1 && !WIFSTOPPED (status
) && pid
!= GET_PID (inferior_ptid
))
1035 /* Check for stop events reported by a process we didn't already
1036 know about - in this case, anything other than inferior_ptid.
1038 If we're expecting to receive stopped processes after fork,
1039 vfork, and clone events, then we'll just add the new one to
1040 our list and go back to waiting for the event to be reported
1041 - the stopped process might be returned from waitpid before
1042 or after the event is. If we want to handle debugging of
1043 CLONE_PTRACE processes we need to do more here, i.e. switch
1044 to multi-threaded mode. */
1045 if (pid
!= -1 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGSTOP
1046 && pid
!= GET_PID (inferior_ptid
))
1048 linux_record_stopped_pid (pid
);
1053 clear_sigio_trap ();
1054 clear_sigint_trap ();
1056 while (pid
== -1 && save_errno
== EINTR
);
1060 warning ("Child process unexpectedly missing: %s",
1061 safe_strerror (errno
));
1063 /* Claim it exited with unknown signal. */
1064 ourstatus
->kind
= TARGET_WAITKIND_SIGNALLED
;
1065 ourstatus
->value
.sig
= TARGET_SIGNAL_UNKNOWN
;
1066 return minus_one_ptid
;
1069 /* Handle GNU/Linux's extended waitstatus for trace events. */
1070 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
&& status
>> 16 != 0)
1071 return linux_handle_extended_wait (pid
, status
, ourstatus
);
1073 store_waitstatus (ourstatus
, status
);
1074 return pid_to_ptid (pid
);
1079 /* Stop an active thread, verify it still exists, then resume it. */
1082 stop_and_resume_callback (struct lwp_info
*lp
, void *data
)
1084 struct lwp_info
*ptr
;
1086 if (!lp
->stopped
&& !lp
->signalled
)
1088 stop_callback (lp
, NULL
);
1089 stop_wait_callback (lp
, NULL
);
1090 /* Resume if the lwp still exists. */
1091 for (ptr
= lwp_list
; ptr
; ptr
= ptr
->next
)
1093 resume_callback (lp
, NULL
);
1099 lin_lwp_wait (ptid_t ptid
, struct target_waitstatus
*ourstatus
)
1101 struct lwp_info
*lp
= NULL
;
1104 pid_t pid
= PIDGET (ptid
);
1105 sigset_t flush_mask
;
1107 sigemptyset (&flush_mask
);
1109 /* Make sure SIGCHLD is blocked. */
1110 if (!sigismember (&blocked_mask
, SIGCHLD
))
1112 sigaddset (&blocked_mask
, SIGCHLD
);
1113 sigprocmask (SIG_BLOCK
, &blocked_mask
, NULL
);
1118 /* Make sure there is at least one LWP that has been resumed, at
1119 least if there are any LWPs at all. */
1120 gdb_assert (num_lwps
== 0 || iterate_over_lwps (resumed_callback
, NULL
));
1122 /* First check if there is a LWP with a wait status pending. */
1125 /* Any LWP that's been resumed will do. */
1126 lp
= iterate_over_lwps (status_callback
, NULL
);
1129 status
= lp
->status
;
1132 if (debug_lin_lwp
&& status
)
1133 fprintf_unfiltered (gdb_stdlog
,
1134 "LLW: Using pending wait status %s for %s.\n",
1135 status_to_str (status
),
1136 target_pid_to_str (lp
->ptid
));
1139 /* But if we don't fine one, we'll have to wait, and check both
1140 cloned and uncloned processes. We start with the cloned
1142 options
= __WCLONE
| WNOHANG
;
1144 else if (is_lwp (ptid
))
1147 fprintf_unfiltered (gdb_stdlog
,
1148 "LLW: Waiting for specific LWP %s.\n",
1149 target_pid_to_str (ptid
));
1151 /* We have a specific LWP to check. */
1152 lp
= find_lwp_pid (ptid
);
1154 status
= lp
->status
;
1157 if (debug_lin_lwp
&& status
)
1158 fprintf_unfiltered (gdb_stdlog
,
1159 "LLW: Using pending wait status %s for %s.\n",
1160 status_to_str (status
),
1161 target_pid_to_str (lp
->ptid
));
1163 /* If we have to wait, take into account whether PID is a cloned
1164 process or not. And we have to convert it to something that
1165 the layer beneath us can understand. */
1166 options
= lp
->cloned
? __WCLONE
: 0;
1167 pid
= GET_LWP (ptid
);
1170 if (status
&& lp
->signalled
)
1172 /* A pending SIGSTOP may interfere with the normal stream of
1173 events. In a typical case where interference is a problem,
1174 we have a SIGSTOP signal pending for LWP A while
1175 single-stepping it, encounter an event in LWP B, and take the
1176 pending SIGSTOP while trying to stop LWP A. After processing
1177 the event in LWP B, LWP A is continued, and we'll never see
1178 the SIGTRAP associated with the last time we were
1179 single-stepping LWP A. */
1181 /* Resume the thread. It should halt immediately returning the
1183 registers_changed ();
1184 child_resume (pid_to_ptid (GET_LWP (lp
->ptid
)), lp
->step
,
1187 fprintf_unfiltered (gdb_stdlog
,
1188 "LLW: %s %s, 0, 0 (expect SIGSTOP)\n",
1189 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
1190 target_pid_to_str (lp
->ptid
));
1192 gdb_assert (lp
->resumed
);
1194 /* This should catch the pending SIGSTOP. */
1195 stop_wait_callback (lp
, NULL
);
1198 set_sigint_trap (); /* Causes SIGINT to be passed on to the
1199 attached process. */
1206 lwpid
= waitpid (pid
, &status
, options
);
1209 gdb_assert (pid
== -1 || lwpid
== pid
);
1213 fprintf_unfiltered (gdb_stdlog
,
1214 "LLW: waitpid %ld received %s\n",
1215 (long) lwpid
, status_to_str (status
));
1218 lp
= find_lwp_pid (pid_to_ptid (lwpid
));
1220 /* Check for stop events reported by a process we didn't
1221 already know about - anything not already in our LWP
1224 If we're expecting to receive stopped processes after
1225 fork, vfork, and clone events, then we'll just add the
1226 new one to our list and go back to waiting for the event
1227 to be reported - the stopped process might be returned
1228 from waitpid before or after the event is. */
1229 if (WIFSTOPPED (status
) && !lp
)
1231 linux_record_stopped_pid (lwpid
);
1236 /* Make sure we don't report an event for the exit of an LWP not in
1237 our list, i.e. not part of the current process. This can happen
1238 if we detach from a program we original forked and then it
1240 if (!WIFSTOPPED (status
) && !lp
)
1246 /* NOTE drow/2003-06-17: This code seems to be meant for debugging
1247 CLONE_PTRACE processes which do not use the thread library -
1248 otherwise we wouldn't find the new LWP this way. That doesn't
1249 currently work, and the following code is currently unreachable
1250 due to the two blocks above. If it's fixed some day, this code
1251 should be broken out into a function so that we can also pick up
1252 LWPs from the new interface. */
1255 lp
= add_lwp (BUILD_LWP (lwpid
, GET_PID (inferior_ptid
)));
1256 if (options
& __WCLONE
)
1261 gdb_assert (WIFSTOPPED (status
)
1262 && WSTOPSIG (status
) == SIGSTOP
);
1265 if (!in_thread_list (inferior_ptid
))
1267 inferior_ptid
= BUILD_LWP (GET_PID (inferior_ptid
),
1268 GET_PID (inferior_ptid
));
1269 add_thread (inferior_ptid
);
1272 add_thread (lp
->ptid
);
1273 printf_unfiltered ("[New %s]\n",
1274 target_pid_to_str (lp
->ptid
));
1278 /* Check if the thread has exited. */
1279 if ((WIFEXITED (status
) || WIFSIGNALED (status
)) && num_lwps
> 1)
1281 if (in_thread_list (lp
->ptid
))
1283 /* Core GDB cannot deal with us deleting the current
1285 if (!ptid_equal (lp
->ptid
, inferior_ptid
))
1286 delete_thread (lp
->ptid
);
1287 printf_unfiltered ("[%s exited]\n",
1288 target_pid_to_str (lp
->ptid
));
1291 /* If this is the main thread, we must stop all threads and
1292 verify if they are still alive. This is because in the nptl
1293 thread model, there is no signal issued for exiting LWPs
1294 other than the main thread. We only get the main thread
1295 exit signal once all child threads have already exited.
1296 If we stop all the threads and use the stop_wait_callback
1297 to check if they have exited we can determine whether this
1298 signal should be ignored or whether it means the end of the
1299 debugged application, regardless of which threading model
1301 if (GET_PID (lp
->ptid
) == GET_LWP (lp
->ptid
))
1304 iterate_over_lwps (stop_and_resume_callback
, NULL
);
1308 fprintf_unfiltered (gdb_stdlog
,
1309 "LLW: %s exited.\n",
1310 target_pid_to_str (lp
->ptid
));
1312 delete_lwp (lp
->ptid
);
1314 /* If there is at least one more LWP, then the exit signal
1315 was not the end of the debugged application and should be
1319 /* Make sure there is at least one thread running. */
1320 gdb_assert (iterate_over_lwps (running_callback
, NULL
));
1322 /* Discard the event. */
1328 /* Check if the current LWP has previously exited. In the nptl
1329 thread model, LWPs other than the main thread do not issue
1330 signals when they exit so we must check whenever the thread
1331 has stopped. A similar check is made in stop_wait_callback(). */
1332 if (num_lwps
> 1 && !lin_lwp_thread_alive (lp
->ptid
))
1334 if (in_thread_list (lp
->ptid
))
1336 /* Core GDB cannot deal with us deleting the current
1338 if (!ptid_equal (lp
->ptid
, inferior_ptid
))
1339 delete_thread (lp
->ptid
);
1340 printf_unfiltered ("[%s exited]\n",
1341 target_pid_to_str (lp
->ptid
));
1344 fprintf_unfiltered (gdb_stdlog
,
1345 "LLW: %s exited.\n",
1346 target_pid_to_str (lp
->ptid
));
1348 delete_lwp (lp
->ptid
);
1350 /* Make sure there is at least one thread running. */
1351 gdb_assert (iterate_over_lwps (running_callback
, NULL
));
1353 /* Discard the event. */
1358 /* Make sure we don't report a SIGSTOP that we sent
1359 ourselves in an attempt to stop an LWP. */
1361 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGSTOP
)
1364 fprintf_unfiltered (gdb_stdlog
,
1365 "LLW: Delayed SIGSTOP caught for %s.\n",
1366 target_pid_to_str (lp
->ptid
));
1368 /* This is a delayed SIGSTOP. */
1371 registers_changed ();
1372 child_resume (pid_to_ptid (GET_LWP (lp
->ptid
)), lp
->step
,
1375 fprintf_unfiltered (gdb_stdlog
,
1376 "LLW: %s %s, 0, 0 (discard SIGSTOP)\n",
1378 "PTRACE_SINGLESTEP" : "PTRACE_CONT",
1379 target_pid_to_str (lp
->ptid
));
1382 gdb_assert (lp
->resumed
);
1384 /* Discard the event. */
1394 /* Alternate between checking cloned and uncloned processes. */
1395 options
^= __WCLONE
;
1397 /* And suspend every time we have checked both. */
1398 if (options
& __WCLONE
)
1399 sigsuspend (&suspend_mask
);
1402 /* We shouldn't end up here unless we want to try again. */
1403 gdb_assert (status
== 0);
1406 clear_sigio_trap ();
1407 clear_sigint_trap ();
1411 /* Don't report signals that GDB isn't interested in, such as
1412 signals that are neither printed nor stopped upon. Stopping all
1413 threads can be a bit time-consuming so if we want decent
1414 performance with heavily multi-threaded programs, especially when
1415 they're using a high frequency timer, we'd better avoid it if we
1418 if (WIFSTOPPED (status
))
1420 int signo
= target_signal_from_host (WSTOPSIG (status
));
1422 if (signal_stop_state (signo
) == 0
1423 && signal_print_state (signo
) == 0
1424 && signal_pass_state (signo
) == 1)
1426 /* FIMXE: kettenis/2001-06-06: Should we resume all threads
1427 here? It is not clear we should. GDB may not expect
1428 other threads to run. On the other hand, not resuming
1429 newly attached threads may cause an unwanted delay in
1430 getting them running. */
1431 registers_changed ();
1432 child_resume (pid_to_ptid (GET_LWP (lp
->ptid
)), lp
->step
, signo
);
1434 fprintf_unfiltered (gdb_stdlog
,
1435 "LLW: %s %s, %s (preempt 'handle')\n",
1437 "PTRACE_SINGLESTEP" : "PTRACE_CONT",
1438 target_pid_to_str (lp
->ptid
),
1439 signo
? strsignal (signo
) : "0");
1445 if (signo
== TARGET_SIGNAL_INT
&& signal_pass_state (signo
) == 0)
1447 /* If ^C/BREAK is typed at the tty/console, SIGINT gets
1448 forwarded to the entire process group, that is, all LWP's
1449 will receive it. Since we only want to report it once,
1450 we try to flush it from all LWPs except this one. */
1451 sigaddset (&flush_mask
, SIGINT
);
1455 /* This LWP is stopped now. */
1459 fprintf_unfiltered (gdb_stdlog
, "LLW: Candidate event %s in %s.\n",
1460 status_to_str (status
), target_pid_to_str (lp
->ptid
));
1462 /* Now stop all other LWP's ... */
1463 iterate_over_lwps (stop_callback
, NULL
);
1465 /* ... and wait until all of them have reported back that they're no
1467 iterate_over_lwps (stop_wait_callback
, &flush_mask
);
1469 /* If we're not waiting for a specific LWP, choose an event LWP from
1470 among those that have had events. Giving equal priority to all
1471 LWPs that have had events helps prevent starvation. */
1473 select_event_lwp (&lp
, &status
);
1475 /* Now that we've selected our final event LWP, cancel any
1476 breakpoints in other LWPs that have hit a GDB breakpoint. See
1477 the comment in cancel_breakpoints_callback to find out why. */
1478 iterate_over_lwps (cancel_breakpoints_callback
, lp
);
1480 /* If we're not running in "threaded" mode, we'll report the bare
1483 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
)
1485 trap_ptid
= (threaded
? lp
->ptid
: pid_to_ptid (GET_LWP (lp
->ptid
)));
1487 fprintf_unfiltered (gdb_stdlog
,
1488 "LLW: trap_ptid is %s.\n",
1489 target_pid_to_str (trap_ptid
));
1492 trap_ptid
= null_ptid
;
1494 /* Handle GNU/Linux's extended waitstatus for trace events. */
1495 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
&& status
>> 16 != 0)
1497 linux_handle_extended_wait (ptid_get_pid (trap_ptid
),
1502 store_waitstatus (ourstatus
, status
);
1503 return (threaded
? lp
->ptid
: pid_to_ptid (GET_LWP (lp
->ptid
)));
1507 kill_callback (struct lwp_info
*lp
, void *data
)
1510 ptrace (PTRACE_KILL
, GET_LWP (lp
->ptid
), 0, 0);
1512 fprintf_unfiltered (gdb_stdlog
,
1513 "KC: PTRACE_KILL %s, 0, 0 (%s)\n",
1514 target_pid_to_str (lp
->ptid
),
1515 errno
? safe_strerror (errno
) : "OK");
1521 kill_wait_callback (struct lwp_info
*lp
, void *data
)
1525 /* We must make sure that there are no pending events (delayed
1526 SIGSTOPs, pending SIGTRAPs, etc.) to make sure the current
1527 program doesn't interfere with any following debugging session. */
1529 /* For cloned processes we must check both with __WCLONE and
1530 without, since the exit status of a cloned process isn't reported
1536 pid
= waitpid (GET_LWP (lp
->ptid
), NULL
, __WCLONE
);
1537 if (pid
!= (pid_t
) -1 && debug_lin_lwp
)
1539 fprintf_unfiltered (gdb_stdlog
,
1540 "KWC: wait %s received unknown.\n",
1541 target_pid_to_str (lp
->ptid
));
1544 while (pid
== GET_LWP (lp
->ptid
));
1546 gdb_assert (pid
== -1 && errno
== ECHILD
);
1551 pid
= waitpid (GET_LWP (lp
->ptid
), NULL
, 0);
1552 if (pid
!= (pid_t
) -1 && debug_lin_lwp
)
1554 fprintf_unfiltered (gdb_stdlog
,
1555 "KWC: wait %s received unk.\n",
1556 target_pid_to_str (lp
->ptid
));
1559 while (pid
== GET_LWP (lp
->ptid
));
1561 gdb_assert (pid
== -1 && errno
== ECHILD
);
1568 /* Kill all LWP's ... */
1569 iterate_over_lwps (kill_callback
, NULL
);
1571 /* ... and wait until we've flushed all events. */
1572 iterate_over_lwps (kill_wait_callback
, NULL
);
1574 target_mourn_inferior ();
1578 lin_lwp_create_inferior (char *exec_file
, char *allargs
, char **env
)
1580 child_ops
.to_create_inferior (exec_file
, allargs
, env
);
1584 lin_lwp_mourn_inferior (void)
1586 trap_ptid
= null_ptid
;
1588 /* Destroy LWP info; it's no longer valid. */
1591 /* Restore the original signal mask. */
1592 sigprocmask (SIG_SETMASK
, &normal_mask
, NULL
);
1593 sigemptyset (&blocked_mask
);
1595 child_ops
.to_mourn_inferior ();
1599 lin_lwp_xfer_memory (CORE_ADDR memaddr
, char *myaddr
, int len
, int write
,
1600 struct mem_attrib
*attrib
, struct target_ops
*target
)
1602 struct cleanup
*old_chain
= save_inferior_ptid ();
1605 if (is_lwp (inferior_ptid
))
1606 inferior_ptid
= pid_to_ptid (GET_LWP (inferior_ptid
));
1608 xfer
= linux_proc_xfer_memory (memaddr
, myaddr
, len
, write
, attrib
, target
);
1610 xfer
= child_xfer_memory (memaddr
, myaddr
, len
, write
, attrib
, target
);
1612 do_cleanups (old_chain
);
1617 lin_lwp_thread_alive (ptid_t ptid
)
1619 gdb_assert (is_lwp (ptid
));
1622 ptrace (PTRACE_PEEKUSER
, GET_LWP (ptid
), 0, 0);
1624 fprintf_unfiltered (gdb_stdlog
,
1625 "LLTA: PTRACE_PEEKUSER %s, 0, 0 (%s)\n",
1626 target_pid_to_str (ptid
),
1627 errno
? safe_strerror (errno
) : "OK");
1635 lin_lwp_pid_to_str (ptid_t ptid
)
1637 static char buf
[64];
1641 snprintf (buf
, sizeof (buf
), "LWP %ld", GET_LWP (ptid
));
1645 return normal_pid_to_str (ptid
);
1649 init_lin_lwp_ops (void)
1652 lin_lwp_ops
.to_open
= lin_lwp_open
;
1654 lin_lwp_ops
.to_shortname
= "lwp-layer";
1655 lin_lwp_ops
.to_longname
= "lwp-layer";
1656 lin_lwp_ops
.to_doc
= "Low level threads support (LWP layer)";
1657 lin_lwp_ops
.to_attach
= lin_lwp_attach
;
1658 lin_lwp_ops
.to_detach
= lin_lwp_detach
;
1659 lin_lwp_ops
.to_resume
= lin_lwp_resume
;
1660 lin_lwp_ops
.to_wait
= lin_lwp_wait
;
1661 /* fetch_inferior_registers and store_inferior_registers will
1662 honor the LWP id, so we can use them directly. */
1663 lin_lwp_ops
.to_fetch_registers
= fetch_inferior_registers
;
1664 lin_lwp_ops
.to_store_registers
= store_inferior_registers
;
1665 lin_lwp_ops
.to_xfer_memory
= lin_lwp_xfer_memory
;
1666 lin_lwp_ops
.to_kill
= lin_lwp_kill
;
1667 lin_lwp_ops
.to_create_inferior
= lin_lwp_create_inferior
;
1668 lin_lwp_ops
.to_mourn_inferior
= lin_lwp_mourn_inferior
;
1669 lin_lwp_ops
.to_thread_alive
= lin_lwp_thread_alive
;
1670 lin_lwp_ops
.to_pid_to_str
= lin_lwp_pid_to_str
;
1671 lin_lwp_ops
.to_post_startup_inferior
= child_post_startup_inferior
;
1672 lin_lwp_ops
.to_post_attach
= child_post_attach
;
1673 lin_lwp_ops
.to_insert_fork_catchpoint
= child_insert_fork_catchpoint
;
1674 lin_lwp_ops
.to_insert_vfork_catchpoint
= child_insert_vfork_catchpoint
;
1675 lin_lwp_ops
.to_insert_exec_catchpoint
= child_insert_exec_catchpoint
;
1677 lin_lwp_ops
.to_stratum
= thread_stratum
;
1678 lin_lwp_ops
.to_has_thread_control
= tc_schedlock
;
1679 lin_lwp_ops
.to_magic
= OPS_MAGIC
;
1683 sigchld_handler (int signo
)
1685 /* Do nothing. The only reason for this handler is that it allows
1686 us to use sigsuspend in lin_lwp_wait above to wait for the
1687 arrival of a SIGCHLD. */
1691 _initialize_lin_lwp (void)
1693 struct sigaction action
;
1695 extern void thread_db_init (struct target_ops
*);
1697 init_lin_lwp_ops ();
1698 add_target (&lin_lwp_ops
);
1699 thread_db_init (&lin_lwp_ops
);
1701 /* Save the original signal mask. */
1702 sigprocmask (SIG_SETMASK
, NULL
, &normal_mask
);
1704 action
.sa_handler
= sigchld_handler
;
1705 sigemptyset (&action
.sa_mask
);
1706 action
.sa_flags
= 0;
1707 sigaction (SIGCHLD
, &action
, NULL
);
1709 /* Make sure we don't block SIGCHLD during a sigsuspend. */
1710 sigprocmask (SIG_SETMASK
, NULL
, &suspend_mask
);
1711 sigdelset (&suspend_mask
, SIGCHLD
);
1713 sigemptyset (&blocked_mask
);
1715 add_show_from_set (add_set_cmd ("lin-lwp", no_class
, var_zinteger
,
1716 (char *) &debug_lin_lwp
,
1717 "Set debugging of GNU/Linux lwp module.\n\
1718 Enables printf debugging output.\n", &setdebuglist
), &showdebuglist
);
1722 /* FIXME: kettenis/2000-08-26: The stuff on this page is specific to
1723 the GNU/Linux Threads library and therefore doesn't really belong
1726 /* Read variable NAME in the target and return its value if found.
1727 Otherwise return zero. It is assumed that the type of the variable
1731 get_signo (const char *name
)
1733 struct minimal_symbol
*ms
;
1736 ms
= lookup_minimal_symbol (name
, NULL
, NULL
);
1740 if (target_read_memory (SYMBOL_VALUE_ADDRESS (ms
), (char *) &signo
,
1741 sizeof (signo
)) != 0)
1747 /* Return the set of signals used by the threads library in *SET. */
1750 lin_thread_get_thread_signals (sigset_t
*set
)
1752 struct sigaction action
;
1753 int restart
, cancel
;
1757 restart
= get_signo ("__pthread_sig_restart");
1761 cancel
= get_signo ("__pthread_sig_cancel");
1765 sigaddset (set
, restart
);
1766 sigaddset (set
, cancel
);
1768 /* The GNU/Linux Threads library makes terminating threads send a
1769 special "cancel" signal instead of SIGCHLD. Make sure we catch
1770 those (to prevent them from terminating GDB itself, which is
1771 likely to be their default action) and treat them the same way as
1774 action
.sa_handler
= sigchld_handler
;
1775 sigemptyset (&action
.sa_mask
);
1776 action
.sa_flags
= 0;
1777 sigaction (cancel
, &action
, NULL
);
1779 /* We block the "cancel" signal throughout this code ... */
1780 sigaddset (&blocked_mask
, cancel
);
1781 sigprocmask (SIG_BLOCK
, &blocked_mask
, NULL
);
1783 /* ... except during a sigsuspend. */
1784 sigdelset (&suspend_mask
, cancel
);