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 /* On GNU/Linux there are no real LWP's. The closest thing to LWP's
44 are processes sharing the same VM space. A multi-threaded process
45 is basically a group of such processes. However, such a grouping
46 is almost entirely a user-space issue; the kernel doesn't enforce
47 such a grouping at all (this might change in the future). In
48 general, we'll rely on the threads library (i.e. the GNU/Linux
49 Threads library) to provide such a grouping.
51 It is perfectly well possible to write a multi-threaded application
52 without the assistance of a threads library, by using the clone
53 system call directly. This module should be able to give some
54 rudimentary support for debugging such applications if developers
55 specify the CLONE_PTRACE flag in the clone system call, and are
56 using the Linux kernel 2.4 or above.
58 Note that there are some peculiarities in GNU/Linux that affect
61 - In general one should specify the __WCLONE flag to waitpid in
62 order to make it report events for any of the cloned processes
63 (and leave it out for the initial process). However, if a cloned
64 process has exited the exit status is only reported if the
65 __WCLONE flag is absent. Linux kernel 2.4 has a __WALL flag, but
66 we cannot use it since GDB must work on older systems too.
68 - When a traced, cloned process exits and is waited for by the
69 debugger, the kernel reassigns it to the original parent and
70 keeps it around as a "zombie". Somehow, the GNU/Linux Threads
71 library doesn't notice this, which leads to the "zombie problem":
72 When debugged a multi-threaded process that spawns a lot of
73 threads will run out of processes, even if the threads exit,
74 because the "zombies" stay around. */
76 /* Structure describing a LWP. */
79 /* The process id of the LWP. This is a combination of the LWP id
80 and overall process id. */
83 /* Non-zero if this LWP is cloned. In this context "cloned" means
84 that the LWP is reporting to its parent using a signal other than
88 /* Non-zero if we sent this LWP a SIGSTOP (but the LWP didn't report
92 /* Non-zero if this LWP is stopped. */
95 /* Non-zero if this LWP will be/has been resumed. Note that an LWP
96 can be marked both as stopped and resumed at the same time. This
97 happens if we try to resume an LWP that has a wait status
98 pending. We shouldn't let the LWP run until that wait status has
99 been processed, but we should not report that wait status if GDB
100 didn't try to let the LWP run. */
103 /* If non-zero, a pending wait status. */
106 /* Non-zero if we were stepping this LWP. */
109 /* Next LWP in list. */
110 struct lwp_info
*next
;
113 /* List of known LWPs. */
114 static struct lwp_info
*lwp_list
;
116 /* Number of LWPs in the list. */
119 /* Non-zero if we're running in "threaded" mode. */
123 #define GET_LWP(ptid) ptid_get_lwp (ptid)
124 #define GET_PID(ptid) ptid_get_pid (ptid)
125 #define is_lwp(ptid) (GET_LWP (ptid) != 0)
126 #define BUILD_LWP(lwp, pid) ptid_build (pid, lwp, 0)
128 /* If the last reported event was a SIGTRAP, this variable is set to
129 the process id of the LWP/thread that got it. */
133 /* This module's target-specific operations. */
134 static struct target_ops lin_lwp_ops
;
136 /* The standard child operations. */
137 extern struct target_ops child_ops
;
139 /* Since we cannot wait (in lin_lwp_wait) for the initial process and
140 any cloned processes with a single call to waitpid, we have to use
141 the WNOHANG flag and call waitpid in a loop. To optimize
142 things a bit we use `sigsuspend' to wake us up when a process has
143 something to report (it will send us a SIGCHLD if it has). To make
144 this work we have to juggle with the signal mask. We save the
145 original signal mask such that we can restore it before creating a
146 new process in order to avoid blocking certain signals in the
147 inferior. We then block SIGCHLD during the waitpid/sigsuspend
150 /* Original signal mask. */
151 static sigset_t normal_mask
;
153 /* Signal mask for use with sigsuspend in lin_lwp_wait, initialized in
154 _initialize_lin_lwp. */
155 static sigset_t suspend_mask
;
157 /* Signals to block to make that sigsuspend work. */
158 static sigset_t blocked_mask
;
161 /* Prototypes for local functions. */
162 static int stop_wait_callback (struct lwp_info
*lp
, void *data
);
163 static int lin_lwp_thread_alive (ptid_t ptid
);
165 /* Convert wait status STATUS to a string. Used for printing debug
169 status_to_str (int status
)
173 if (WIFSTOPPED (status
))
174 snprintf (buf
, sizeof (buf
), "%s (stopped)",
175 strsignal (WSTOPSIG (status
)));
176 else if (WIFSIGNALED (status
))
177 snprintf (buf
, sizeof (buf
), "%s (terminated)",
178 strsignal (WSTOPSIG (status
)));
180 snprintf (buf
, sizeof (buf
), "%d (exited)", WEXITSTATUS (status
));
185 /* Initialize the list of LWPs. Note that this module, contrary to
186 what GDB's generic threads layer does for its thread list,
187 re-initializes the LWP lists whenever we mourn or detach (which
188 doesn't involve mourning) the inferior. */
193 struct lwp_info
*lp
, *lpnext
;
195 for (lp
= lwp_list
; lp
; lp
= lpnext
)
206 /* Add the LWP specified by PID to the list. If this causes the
207 number of LWPs to become larger than one, go into "threaded" mode.
208 Return a pointer to the structure describing the new LWP. */
210 static struct lwp_info
*
211 add_lwp (ptid_t ptid
)
215 gdb_assert (is_lwp (ptid
));
217 lp
= (struct lwp_info
*) xmalloc (sizeof (struct lwp_info
));
219 memset (lp
, 0, sizeof (struct lwp_info
));
231 /* Remove the LWP specified by PID from the list. */
234 delete_lwp (ptid_t ptid
)
236 struct lwp_info
*lp
, *lpprev
;
240 for (lp
= lwp_list
; lp
; lpprev
= lp
, lp
= lp
->next
)
241 if (ptid_equal (lp
->ptid
, ptid
))
247 /* We don't go back to "non-threaded" mode if the number of threads
248 becomes less than two. */
252 lpprev
->next
= lp
->next
;
259 /* Return a pointer to the structure describing the LWP corresponding
260 to PID. If no corresponding LWP could be found, return NULL. */
262 static struct lwp_info
*
263 find_lwp_pid (ptid_t ptid
)
269 lwp
= GET_LWP (ptid
);
271 lwp
= GET_PID (ptid
);
273 for (lp
= lwp_list
; lp
; lp
= lp
->next
)
274 if (lwp
== GET_LWP (lp
->ptid
))
280 /* Call CALLBACK with its second argument set to DATA for every LWP in
281 the list. If CALLBACK returns 1 for a particular LWP, return a
282 pointer to the structure describing that LWP immediately.
283 Otherwise return NULL. */
286 iterate_over_lwps (int (*callback
) (struct lwp_info
*, void *), void *data
)
288 struct lwp_info
*lp
, *lpnext
;
290 for (lp
= lwp_list
; lp
; lp
= lpnext
)
293 if ((*callback
) (lp
, data
))
301 /* Implementation of the PREPARE_TO_PROCEED hook for the GNU/Linux LWP
304 Note that this implementation is potentially redundant now that
305 default_prepare_to_proceed() has been added.
307 FIXME This may not support switching threads after Ctrl-C
308 correctly. The default implementation does support this. */
311 lin_lwp_prepare_to_proceed (void)
313 if (!ptid_equal (trap_ptid
, null_ptid
)
314 && !ptid_equal (inferior_ptid
, trap_ptid
))
316 /* Switched over from TRAP_PID. */
317 CORE_ADDR stop_pc
= read_pc ();
320 /* Avoid switching where it wouldn't do any good, i.e. if both
321 threads are at the same breakpoint. */
322 trap_pc
= read_pc_pid (trap_ptid
);
323 if (trap_pc
!= stop_pc
&& breakpoint_here_p (trap_pc
))
325 /* User hasn't deleted the breakpoint. Return non-zero, and
326 switch back to TRAP_PID. */
327 inferior_ptid
= trap_ptid
;
329 /* FIXME: Is this stuff really necessary? */
330 flush_cached_frames ();
331 registers_changed ();
343 lin_lwp_open (char *args
, int from_tty
)
345 push_target (&lin_lwp_ops
);
349 /* Attach to the LWP specified by PID. If VERBOSE is non-zero, print
350 a message telling the user that a new LWP has been added to the
354 lin_lwp_attach_lwp (ptid_t ptid
, int verbose
)
358 gdb_assert (is_lwp (ptid
));
360 /* Make sure SIGCHLD is blocked. We don't want SIGCHLD events
361 to interrupt either the ptrace() or waitpid() calls below. */
362 if (!sigismember (&blocked_mask
, SIGCHLD
))
364 sigaddset (&blocked_mask
, SIGCHLD
);
365 sigprocmask (SIG_BLOCK
, &blocked_mask
, NULL
);
369 printf_filtered ("[New %s]\n", target_pid_to_str (ptid
));
371 lp
= find_lwp_pid (ptid
);
375 /* We assume that we're already attached to any LWP that has an
376 id equal to the overall process id. */
377 if (GET_LWP (ptid
) != GET_PID (ptid
))
382 if (ptrace (PTRACE_ATTACH
, GET_LWP (ptid
), 0, 0) < 0)
383 error ("Can't attach %s: %s", target_pid_to_str (ptid
),
384 safe_strerror (errno
));
387 fprintf_unfiltered (gdb_stdlog
,
388 "LLAL: PTRACE_ATTACH %s, 0, 0 (OK)\n",
389 target_pid_to_str (ptid
));
391 pid
= waitpid (GET_LWP (ptid
), &status
, 0);
392 if (pid
== -1 && errno
== ECHILD
)
394 /* Try again with __WCLONE to check cloned processes. */
395 pid
= waitpid (GET_LWP (ptid
), &status
, __WCLONE
);
399 gdb_assert (pid
== GET_LWP (ptid
)
400 && WIFSTOPPED (status
) && WSTOPSIG (status
));
406 fprintf_unfiltered (gdb_stdlog
,
407 "LLAL: waitpid %s received %s\n",
408 target_pid_to_str (ptid
),
409 status_to_str (status
));
414 /* We assume that the LWP representing the original process
415 is already stopped. Mark it as stopped in the data structure
416 that the lin-lwp layer uses to keep track of threads. Note
417 that this won't have already been done since the main thread
418 will have, we assume, been stopped by an attach from a
425 lin_lwp_attach (char *args
, int from_tty
)
431 /* FIXME: We should probably accept a list of process id's, and
432 attach all of them. */
433 child_ops
.to_attach (args
, from_tty
);
435 /* Add the initial process as the first LWP to the list. */
436 lp
= add_lwp (BUILD_LWP (GET_PID (inferior_ptid
), GET_PID (inferior_ptid
)));
438 /* Make sure the initial process is stopped. The user-level threads
439 layer might want to poke around in the inferior, and that won't
440 work if things haven't stabilized yet. */
441 pid
= waitpid (GET_PID (inferior_ptid
), &status
, 0);
442 if (pid
== -1 && errno
== ECHILD
)
444 warning ("%s is a cloned process", target_pid_to_str (inferior_ptid
));
446 /* Try again with __WCLONE to check cloned processes. */
447 pid
= waitpid (GET_PID (inferior_ptid
), &status
, __WCLONE
);
451 gdb_assert (pid
== GET_PID (inferior_ptid
)
452 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGSTOP
);
456 /* Fake the SIGSTOP that core GDB expects. */
457 lp
->status
= W_STOPCODE (SIGSTOP
);
461 fprintf_unfiltered (gdb_stdlog
,
462 "LLA: waitpid %ld, faking SIGSTOP\n", (long) pid
);
467 detach_callback (struct lwp_info
*lp
, void *data
)
469 gdb_assert (lp
->status
== 0 || WIFSTOPPED (lp
->status
));
471 if (debug_lin_lwp
&& lp
->status
)
472 fprintf_unfiltered (gdb_stdlog
, "DC: Pending %s for %s on detach.\n",
473 strsignal (WSTOPSIG (lp
->status
)),
474 target_pid_to_str (lp
->ptid
));
476 while (lp
->signalled
&& lp
->stopped
)
479 if (ptrace (PTRACE_CONT
, GET_LWP (lp
->ptid
), 0,
480 WSTOPSIG (lp
->status
)) < 0)
481 error ("Can't continue %s: %s", target_pid_to_str (lp
->ptid
),
482 safe_strerror (errno
));
485 fprintf_unfiltered (gdb_stdlog
,
486 "DC: PTRACE_CONTINUE (%s, 0, %s) (OK)\n",
487 target_pid_to_str (lp
->ptid
),
488 status_to_str (lp
->status
));
493 stop_wait_callback (lp
, NULL
);
495 gdb_assert (lp
->status
== 0 || WIFSTOPPED (lp
->status
));
498 /* We don't actually detach from the LWP that has an id equal to the
499 overall process id just yet. */
500 if (GET_LWP (lp
->ptid
) != GET_PID (lp
->ptid
))
503 if (ptrace (PTRACE_DETACH
, GET_LWP (lp
->ptid
), 0,
504 WSTOPSIG (lp
->status
)) < 0)
505 error ("Can't detach %s: %s", target_pid_to_str (lp
->ptid
),
506 safe_strerror (errno
));
509 fprintf_unfiltered (gdb_stdlog
,
510 "PTRACE_DETACH (%s, %s, 0) (OK)\n",
511 target_pid_to_str (lp
->ptid
),
512 strsignal (WSTOPSIG (lp
->status
)));
514 delete_lwp (lp
->ptid
);
521 lin_lwp_detach (char *args
, int from_tty
)
523 iterate_over_lwps (detach_callback
, NULL
);
525 /* Only the initial process should be left right now. */
526 gdb_assert (num_lwps
== 1);
528 trap_ptid
= null_ptid
;
530 /* Destroy LWP info; it's no longer valid. */
533 /* Restore the original signal mask. */
534 sigprocmask (SIG_SETMASK
, &normal_mask
, NULL
);
535 sigemptyset (&blocked_mask
);
537 inferior_ptid
= pid_to_ptid (GET_PID (inferior_ptid
));
538 child_ops
.to_detach (args
, from_tty
);
545 resume_callback (struct lwp_info
*lp
, void *data
)
547 if (lp
->stopped
&& lp
->status
== 0)
549 struct thread_info
*tp
;
551 child_resume (pid_to_ptid (GET_LWP (lp
->ptid
)), 0, TARGET_SIGNAL_0
);
553 fprintf_unfiltered (gdb_stdlog
,
554 "RC: PTRACE_CONT %s, 0, 0 (resume sibling)\n",
555 target_pid_to_str (lp
->ptid
));
564 resume_clear_callback (struct lwp_info
*lp
, void *data
)
571 resume_set_callback (struct lwp_info
*lp
, void *data
)
578 lin_lwp_resume (ptid_t ptid
, int step
, enum target_signal signo
)
583 /* A specific PTID means `step only this process id'. */
584 resume_all
= (PIDGET (ptid
) == -1);
587 iterate_over_lwps (resume_set_callback
, NULL
);
589 iterate_over_lwps (resume_clear_callback
, NULL
);
591 /* If PID is -1, it's the current inferior that should be
592 handled specially. */
593 if (PIDGET (ptid
) == -1)
594 ptid
= inferior_ptid
;
596 lp
= find_lwp_pid (ptid
);
599 ptid
= pid_to_ptid (GET_LWP (lp
->ptid
));
601 /* Remember if we're stepping. */
604 /* Mark this LWP as resumed. */
607 /* If we have a pending wait status for this thread, there is no
608 point in resuming the process. */
611 /* FIXME: What should we do if we are supposed to continue
612 this thread with a signal? */
613 gdb_assert (signo
== TARGET_SIGNAL_0
);
617 /* Mark LWP as not stopped to prevent it from being continued by
623 iterate_over_lwps (resume_callback
, NULL
);
625 child_resume (ptid
, step
, signo
);
627 fprintf_unfiltered (gdb_stdlog
,
628 "LLR: %s %s, %s (resume event thread)\n",
629 step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
630 target_pid_to_str (ptid
),
631 signo
? strsignal (signo
) : "0");
635 /* Issue kill to specified lwp. */
637 static int tkill_failed
;
640 kill_lwp (int lwpid
, int signo
)
644 /* Use tkill, if possible, in case we are using nptl threads. If tkill
645 fails, then we are not using nptl threads and we should be using kill. */
647 #ifdef HAVE_TKILL_SYSCALL
650 int ret
= syscall (__NR_tkill
, lwpid
, signo
);
658 return kill (lwpid
, signo
);
661 /* Send a SIGSTOP to LP. */
664 stop_callback (struct lwp_info
*lp
, void *data
)
666 if (!lp
->stopped
&& !lp
->signalled
)
672 fprintf_unfiltered (gdb_stdlog
,
673 "SC: kill %s **<SIGSTOP>**\n",
674 target_pid_to_str (lp
->ptid
));
677 ret
= kill_lwp (GET_LWP (lp
->ptid
), SIGSTOP
);
680 fprintf_unfiltered (gdb_stdlog
,
681 "SC: lwp kill %d %s\n",
683 errno
? safe_strerror (errno
) : "ERRNO-OK");
687 gdb_assert (lp
->status
== 0);
693 /* Wait until LP is stopped. If DATA is non-null it is interpreted as
694 a pointer to a set of signals to be flushed immediately. */
697 stop_wait_callback (struct lwp_info
*lp
, void *data
)
699 sigset_t
*flush_mask
= data
;
701 if (!lp
->stopped
&& lp
->signalled
)
706 gdb_assert (lp
->status
== 0);
708 pid
= waitpid (GET_LWP (lp
->ptid
), &status
, 0);
709 if (pid
== -1 && errno
== ECHILD
)
711 pid
= waitpid (GET_LWP (lp
->ptid
), &status
, __WCLONE
);
712 if (pid
== -1 && errno
== ECHILD
)
714 /* The thread has previously exited. We need to delete it now
715 because in the case of nptl threads, there won't be an
716 exit event unless it is the main thread. */
718 fprintf_unfiltered (gdb_stdlog
,
720 target_pid_to_str (lp
->ptid
));
721 delete_lwp (lp
->ptid
);
726 gdb_assert (pid
== GET_LWP (lp
->ptid
));
730 fprintf_unfiltered (gdb_stdlog
,
731 "SWC: waitpid %s received %s\n",
732 target_pid_to_str (lp
->ptid
),
733 status_to_str (status
));
736 /* Check if the thread has exited. */
737 if (WIFEXITED (status
) || WIFSIGNALED (status
))
739 gdb_assert (num_lwps
> 1);
741 if (in_thread_list (lp
->ptid
))
743 /* Core GDB cannot deal with us deleting the current
745 if (!ptid_equal (lp
->ptid
, inferior_ptid
))
746 delete_thread (lp
->ptid
);
747 printf_unfiltered ("[%s exited]\n",
748 target_pid_to_str (lp
->ptid
));
751 fprintf_unfiltered (gdb_stdlog
,
753 target_pid_to_str (lp
->ptid
));
755 delete_lwp (lp
->ptid
);
759 /* Check if the current LWP has previously exited. For nptl threads,
760 there is no exit signal issued for LWPs that are not the
761 main thread so we should check whenever the thread is stopped. */
762 if (!lin_lwp_thread_alive (lp
->ptid
))
764 if (in_thread_list (lp
->ptid
))
766 /* Core GDB cannot deal with us deleting the current
768 if (!ptid_equal (lp
->ptid
, inferior_ptid
))
769 delete_thread (lp
->ptid
);
770 printf_unfiltered ("[%s exited]\n",
771 target_pid_to_str (lp
->ptid
));
774 fprintf_unfiltered (gdb_stdlog
,
775 "SWC: %s already exited.\n",
776 target_pid_to_str (lp
->ptid
));
778 delete_lwp (lp
->ptid
);
782 gdb_assert (WIFSTOPPED (status
));
784 /* Ignore any signals in FLUSH_MASK. */
785 if (flush_mask
&& sigismember (flush_mask
, WSTOPSIG (status
)))
788 ptrace (PTRACE_CONT
, GET_LWP (lp
->ptid
), 0, 0);
790 fprintf_unfiltered (gdb_stdlog
,
791 "PTRACE_CONT %s, 0, 0 (%s)\n",
792 target_pid_to_str (lp
->ptid
),
793 errno
? safe_strerror (errno
) : "OK");
795 return stop_wait_callback (lp
, flush_mask
);
798 if (WSTOPSIG (status
) != SIGSTOP
)
800 if (WSTOPSIG (status
) == SIGTRAP
)
802 /* If a LWP other than the LWP that we're reporting an
803 event for has hit a GDB breakpoint (as opposed to
804 some random trap signal), then just arrange for it to
805 hit it again later. We don't keep the SIGTRAP status
806 and don't forward the SIGTRAP signal to the LWP. We
807 will handle the current event, eventually we will
808 resume all LWPs, and this one will get its breakpoint
811 If we do not do this, then we run the risk that the
812 user will delete or disable the breakpoint, but the
813 thread will have already tripped on it. */
815 /* Now resume this LWP and get the SIGSTOP event. */
817 ptrace (PTRACE_CONT
, GET_LWP (lp
->ptid
), 0, 0);
820 fprintf_unfiltered (gdb_stdlog
,
821 "PTRACE_CONT %s, 0, 0 (%s)\n",
822 target_pid_to_str (lp
->ptid
),
823 errno
? safe_strerror (errno
) : "OK");
825 fprintf_unfiltered (gdb_stdlog
,
826 "SWC: Candidate SIGTRAP event in %s\n",
827 target_pid_to_str (lp
->ptid
));
829 /* Hold the SIGTRAP for handling by lin_lwp_wait. */
830 stop_wait_callback (lp
, data
);
831 /* If there's another event, throw it back into the queue. */
836 fprintf_unfiltered (gdb_stdlog
,
837 "SWC: kill %s, %s\n",
838 target_pid_to_str (lp
->ptid
),
839 status_to_str ((int) status
));
841 kill_lwp (GET_LWP (lp
->ptid
), WSTOPSIG (lp
->status
));
843 /* Save the sigtrap event. */
849 /* The thread was stopped with a signal other than
850 SIGSTOP, and didn't accidentally trip a breakpoint. */
854 fprintf_unfiltered (gdb_stdlog
,
855 "SWC: Pending event %s in %s\n",
856 status_to_str ((int) status
),
857 target_pid_to_str (lp
->ptid
));
859 /* Now resume this LWP and get the SIGSTOP event. */
861 ptrace (PTRACE_CONT
, GET_LWP (lp
->ptid
), 0, 0);
863 fprintf_unfiltered (gdb_stdlog
,
864 "SWC: PTRACE_CONT %s, 0, 0 (%s)\n",
865 target_pid_to_str (lp
->ptid
),
866 errno
? safe_strerror (errno
) : "OK");
868 /* Hold this event/waitstatus while we check to see if
869 there are any more (we still want to get that SIGSTOP). */
870 stop_wait_callback (lp
, data
);
871 /* If the lp->status field is still empty, use it to hold
872 this event. If not, then this event must be returned
873 to the event queue of the LWP. */
880 fprintf_unfiltered (gdb_stdlog
,
881 "SWC: kill %s, %s\n",
882 target_pid_to_str (lp
->ptid
),
883 status_to_str ((int) status
));
885 kill_lwp (GET_LWP (lp
->ptid
), WSTOPSIG (status
));
892 /* We caught the SIGSTOP that we intended to catch, so
893 there's no SIGSTOP pending. */
902 /* Return non-zero if LP has a wait status pending. */
905 status_callback (struct lwp_info
*lp
, void *data
)
907 /* Only report a pending wait status if we pretend that this has
908 indeed been resumed. */
909 return (lp
->status
!= 0 && lp
->resumed
);
912 /* Return non-zero if LP isn't stopped. */
915 running_callback (struct lwp_info
*lp
, void *data
)
917 return (lp
->stopped
== 0);
920 /* Count the LWP's that have had events. */
923 count_events_callback (struct lwp_info
*lp
, void *data
)
927 gdb_assert (count
!= NULL
);
929 /* Count only LWPs that have a SIGTRAP event pending. */
931 && WIFSTOPPED (lp
->status
) && WSTOPSIG (lp
->status
) == SIGTRAP
)
937 /* Select the LWP (if any) that is currently being single-stepped. */
940 select_singlestep_lwp_callback (struct lwp_info
*lp
, void *data
)
942 if (lp
->step
&& lp
->status
!= 0)
948 /* Select the Nth LWP that has had a SIGTRAP event. */
951 select_event_lwp_callback (struct lwp_info
*lp
, void *data
)
953 int *selector
= data
;
955 gdb_assert (selector
!= NULL
);
957 /* Select only LWPs that have a SIGTRAP event pending. */
959 && WIFSTOPPED (lp
->status
) && WSTOPSIG (lp
->status
) == SIGTRAP
)
960 if ((*selector
)-- == 0)
967 cancel_breakpoints_callback (struct lwp_info
*lp
, void *data
)
969 struct lwp_info
*event_lp
= data
;
971 /* Leave the LWP that has been elected to receive a SIGTRAP alone. */
975 /* If a LWP other than the LWP that we're reporting an event for has
976 hit a GDB breakpoint (as opposed to some random trap signal),
977 then just arrange for it to hit it again later. We don't keep
978 the SIGTRAP status and don't forward the SIGTRAP signal to the
979 LWP. We will handle the current event, eventually we will resume
980 all LWPs, and this one will get its breakpoint trap again.
982 If we do not do this, then we run the risk that the user will
983 delete or disable the breakpoint, but the LWP will have already
987 && WIFSTOPPED (lp
->status
) && WSTOPSIG (lp
->status
) == SIGTRAP
988 && breakpoint_inserted_here_p (read_pc_pid (lp
->ptid
) -
989 DECR_PC_AFTER_BREAK
))
992 fprintf_unfiltered (gdb_stdlog
,
993 "CBC: Push back breakpoint for %s\n",
994 target_pid_to_str (lp
->ptid
));
996 /* Back up the PC if necessary. */
997 if (DECR_PC_AFTER_BREAK
)
998 write_pc_pid (read_pc_pid (lp
->ptid
) - DECR_PC_AFTER_BREAK
, lp
->ptid
);
1000 /* Throw away the SIGTRAP. */
1007 /* Select one LWP out of those that have events pending. */
1010 select_event_lwp (struct lwp_info
**orig_lp
, int *status
)
1013 int random_selector
;
1014 struct lwp_info
*event_lp
;
1016 /* Record the wait status for the origional LWP. */
1017 (*orig_lp
)->status
= *status
;
1019 /* Give preference to any LWP that is being single-stepped. */
1020 event_lp
= iterate_over_lwps (select_singlestep_lwp_callback
, NULL
);
1021 if (event_lp
!= NULL
)
1024 fprintf_unfiltered (gdb_stdlog
,
1025 "SEL: Select single-step %s\n",
1026 target_pid_to_str (event_lp
->ptid
));
1030 /* No single-stepping LWP. Select one at random, out of those
1031 which have had SIGTRAP events. */
1033 /* First see how many SIGTRAP events we have. */
1034 iterate_over_lwps (count_events_callback
, &num_events
);
1036 /* Now randomly pick a LWP out of those that have had a SIGTRAP. */
1037 random_selector
= (int)
1038 ((num_events
* (double) rand ()) / (RAND_MAX
+ 1.0));
1040 if (debug_lin_lwp
&& num_events
> 1)
1041 fprintf_unfiltered (gdb_stdlog
,
1042 "SEL: Found %d SIGTRAP events, selecting #%d\n",
1043 num_events
, random_selector
);
1045 event_lp
= iterate_over_lwps (select_event_lwp_callback
,
1049 if (event_lp
!= NULL
)
1051 /* Switch the event LWP. */
1052 *orig_lp
= event_lp
;
1053 *status
= event_lp
->status
;
1056 /* Flush the wait status for the event LWP. */
1057 (*orig_lp
)->status
= 0;
1060 /* Return non-zero if LP has been resumed. */
1063 resumed_callback (struct lwp_info
*lp
, void *data
)
1070 /* We need to override child_wait to support attaching to cloned
1071 processes, since a normal wait (as done by the default version)
1072 ignores those processes. */
1074 /* Wait for child PTID to do something. Return id of the child,
1075 minus_one_ptid in case of error; store status into *OURSTATUS. */
1078 child_wait (ptid_t ptid
, struct target_waitstatus
*ourstatus
)
1086 set_sigint_trap (); /* Causes SIGINT to be passed on to the
1087 attached process. */
1090 pid
= waitpid (GET_PID (ptid
), &status
, 0);
1091 if (pid
== -1 && errno
== ECHILD
)
1092 /* Try again with __WCLONE to check cloned processes. */
1093 pid
= waitpid (GET_PID (ptid
), &status
, __WCLONE
);
1097 fprintf_unfiltered (gdb_stdlog
,
1098 "CW: waitpid %ld received %s\n",
1099 (long) pid
, status_to_str (status
));
1104 /* Make sure we don't report an event for the exit of the
1105 original program, if we've detached from it. */
1106 if (pid
!= -1 && !WIFSTOPPED (status
) && pid
!= GET_PID (inferior_ptid
))
1112 clear_sigio_trap ();
1113 clear_sigint_trap ();
1115 while (pid
== -1 && save_errno
== EINTR
);
1119 warning ("Child process unexpectedly missing: %s",
1120 safe_strerror (errno
));
1122 /* Claim it exited with unknown signal. */
1123 ourstatus
->kind
= TARGET_WAITKIND_SIGNALLED
;
1124 ourstatus
->value
.sig
= TARGET_SIGNAL_UNKNOWN
;
1125 return minus_one_ptid
;
1128 store_waitstatus (ourstatus
, status
);
1129 return pid_to_ptid (pid
);
1134 /* Stop an active thread, verify it still exists, then resume it. */
1137 stop_and_resume_callback (struct lwp_info
*lp
, void *data
)
1139 struct lwp_info
*ptr
;
1141 if (!lp
->stopped
&& !lp
->signalled
)
1143 stop_callback (lp
, NULL
);
1144 stop_wait_callback (lp
, NULL
);
1145 /* Resume if the lwp still exists. */
1146 for (ptr
= lwp_list
; ptr
; ptr
= ptr
->next
)
1148 resume_callback (lp
, NULL
);
1154 lin_lwp_wait (ptid_t ptid
, struct target_waitstatus
*ourstatus
)
1156 struct lwp_info
*lp
= NULL
;
1159 pid_t pid
= PIDGET (ptid
);
1160 sigset_t flush_mask
;
1162 sigemptyset (&flush_mask
);
1164 /* Make sure SIGCHLD is blocked. */
1165 if (!sigismember (&blocked_mask
, SIGCHLD
))
1167 sigaddset (&blocked_mask
, SIGCHLD
);
1168 sigprocmask (SIG_BLOCK
, &blocked_mask
, NULL
);
1173 /* Make sure there is at least one LWP that has been resumed, at
1174 least if there are any LWPs at all. */
1175 gdb_assert (num_lwps
== 0 || iterate_over_lwps (resumed_callback
, NULL
));
1177 /* First check if there is a LWP with a wait status pending. */
1180 /* Any LWP that's been resumed will do. */
1181 lp
= iterate_over_lwps (status_callback
, NULL
);
1184 status
= lp
->status
;
1187 if (debug_lin_lwp
&& status
)
1188 fprintf_unfiltered (gdb_stdlog
,
1189 "LLW: Using pending wait status %s for %s.\n",
1190 status_to_str (status
),
1191 target_pid_to_str (lp
->ptid
));
1194 /* But if we don't fine one, we'll have to wait, and check both
1195 cloned and uncloned processes. We start with the cloned
1197 options
= __WCLONE
| WNOHANG
;
1199 else if (is_lwp (ptid
))
1202 fprintf_unfiltered (gdb_stdlog
,
1203 "LLW: Waiting for specific LWP %s.\n",
1204 target_pid_to_str (ptid
));
1206 /* We have a specific LWP to check. */
1207 lp
= find_lwp_pid (ptid
);
1209 status
= lp
->status
;
1212 if (debug_lin_lwp
&& status
)
1213 fprintf_unfiltered (gdb_stdlog
,
1214 "LLW: Using pending wait status %s for %s.\n",
1215 status_to_str (status
),
1216 target_pid_to_str (lp
->ptid
));
1218 /* If we have to wait, take into account whether PID is a cloned
1219 process or not. And we have to convert it to something that
1220 the layer beneath us can understand. */
1221 options
= lp
->cloned
? __WCLONE
: 0;
1222 pid
= GET_LWP (ptid
);
1225 if (status
&& lp
->signalled
)
1227 /* A pending SIGSTOP may interfere with the normal stream of
1228 events. In a typical case where interference is a problem,
1229 we have a SIGSTOP signal pending for LWP A while
1230 single-stepping it, encounter an event in LWP B, and take the
1231 pending SIGSTOP while trying to stop LWP A. After processing
1232 the event in LWP B, LWP A is continued, and we'll never see
1233 the SIGTRAP associated with the last time we were
1234 single-stepping LWP A. */
1236 /* Resume the thread. It should halt immediately returning the
1238 registers_changed ();
1239 child_resume (pid_to_ptid (GET_LWP (lp
->ptid
)), lp
->step
,
1242 fprintf_unfiltered (gdb_stdlog
,
1243 "LLW: %s %s, 0, 0 (expect SIGSTOP)\n",
1244 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
1245 target_pid_to_str (lp
->ptid
));
1247 gdb_assert (lp
->resumed
);
1249 /* This should catch the pending SIGSTOP. */
1250 stop_wait_callback (lp
, NULL
);
1253 set_sigint_trap (); /* Causes SIGINT to be passed on to the
1254 attached process. */
1261 lwpid
= waitpid (pid
, &status
, options
);
1264 gdb_assert (pid
== -1 || lwpid
== pid
);
1268 fprintf_unfiltered (gdb_stdlog
,
1269 "LLW: waitpid %ld received %s\n",
1270 (long) lwpid
, status_to_str (status
));
1273 lp
= find_lwp_pid (pid_to_ptid (lwpid
));
1275 /* Make sure we don't report an event for the exit of an LWP not in
1276 our list, i.e. not part of the current process. This can happen
1277 if we detach from a program we original forked and then it
1279 if (!WIFSTOPPED (status
) && !lp
)
1287 lp
= add_lwp (BUILD_LWP (lwpid
, GET_PID (inferior_ptid
)));
1288 if (options
& __WCLONE
)
1293 gdb_assert (WIFSTOPPED (status
)
1294 && WSTOPSIG (status
) == SIGSTOP
);
1297 if (!in_thread_list (inferior_ptid
))
1299 inferior_ptid
= BUILD_LWP (GET_PID (inferior_ptid
),
1300 GET_PID (inferior_ptid
));
1301 add_thread (inferior_ptid
);
1304 add_thread (lp
->ptid
);
1305 printf_unfiltered ("[New %s]\n",
1306 target_pid_to_str (lp
->ptid
));
1310 /* Check if the thread has exited. */
1311 if ((WIFEXITED (status
) || WIFSIGNALED (status
)) && num_lwps
> 1)
1313 if (in_thread_list (lp
->ptid
))
1315 /* Core GDB cannot deal with us deleting the current
1317 if (!ptid_equal (lp
->ptid
, inferior_ptid
))
1318 delete_thread (lp
->ptid
);
1319 printf_unfiltered ("[%s exited]\n",
1320 target_pid_to_str (lp
->ptid
));
1323 /* If this is the main thread, we must stop all threads and
1324 verify if they are still alive. This is because in the nptl
1325 thread model, there is no signal issued for exiting LWPs
1326 other than the main thread. We only get the main thread
1327 exit signal once all child threads have already exited.
1328 If we stop all the threads and use the stop_wait_callback
1329 to check if they have exited we can determine whether this
1330 signal should be ignored or whether it means the end of the
1331 debugged application, regardless of which threading model
1333 if (GET_PID (lp
->ptid
) == GET_LWP (lp
->ptid
))
1336 iterate_over_lwps (stop_and_resume_callback
, NULL
);
1340 fprintf_unfiltered (gdb_stdlog
,
1341 "LLW: %s exited.\n",
1342 target_pid_to_str (lp
->ptid
));
1344 delete_lwp (lp
->ptid
);
1346 /* If there is at least one more LWP, then the exit signal
1347 was not the end of the debugged application and should be
1351 /* Make sure there is at least one thread running. */
1352 gdb_assert (iterate_over_lwps (running_callback
, NULL
));
1354 /* Discard the event. */
1360 /* Check if the current LWP has previously exited. In the nptl
1361 thread model, LWPs other than the main thread do not issue
1362 signals when they exit so we must check whenever the thread
1363 has stopped. A similar check is made in stop_wait_callback(). */
1364 if (num_lwps
> 1 && !lin_lwp_thread_alive (lp
->ptid
))
1366 if (in_thread_list (lp
->ptid
))
1368 /* Core GDB cannot deal with us deleting the current
1370 if (!ptid_equal (lp
->ptid
, inferior_ptid
))
1371 delete_thread (lp
->ptid
);
1372 printf_unfiltered ("[%s exited]\n",
1373 target_pid_to_str (lp
->ptid
));
1376 fprintf_unfiltered (gdb_stdlog
,
1377 "LLW: %s exited.\n",
1378 target_pid_to_str (lp
->ptid
));
1380 delete_lwp (lp
->ptid
);
1382 /* Make sure there is at least one thread running. */
1383 gdb_assert (iterate_over_lwps (running_callback
, NULL
));
1385 /* Discard the event. */
1390 /* Make sure we don't report a SIGSTOP that we sent
1391 ourselves in an attempt to stop an LWP. */
1393 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGSTOP
)
1396 fprintf_unfiltered (gdb_stdlog
,
1397 "LLW: Delayed SIGSTOP caught for %s.\n",
1398 target_pid_to_str (lp
->ptid
));
1400 /* This is a delayed SIGSTOP. */
1403 registers_changed ();
1404 child_resume (pid_to_ptid (GET_LWP (lp
->ptid
)), lp
->step
,
1407 fprintf_unfiltered (gdb_stdlog
,
1408 "LLW: %s %s, 0, 0 (discard SIGSTOP)\n",
1410 "PTRACE_SINGLESTEP" : "PTRACE_CONT",
1411 target_pid_to_str (lp
->ptid
));
1414 gdb_assert (lp
->resumed
);
1416 /* Discard the event. */
1426 /* Alternate between checking cloned and uncloned processes. */
1427 options
^= __WCLONE
;
1429 /* And suspend every time we have checked both. */
1430 if (options
& __WCLONE
)
1431 sigsuspend (&suspend_mask
);
1434 /* We shouldn't end up here unless we want to try again. */
1435 gdb_assert (status
== 0);
1438 clear_sigio_trap ();
1439 clear_sigint_trap ();
1443 /* Don't report signals that GDB isn't interested in, such as
1444 signals that are neither printed nor stopped upon. Stopping all
1445 threads can be a bit time-consuming so if we want decent
1446 performance with heavily multi-threaded programs, especially when
1447 they're using a high frequency timer, we'd better avoid it if we
1450 if (WIFSTOPPED (status
))
1452 int signo
= target_signal_from_host (WSTOPSIG (status
));
1454 if (signal_stop_state (signo
) == 0
1455 && signal_print_state (signo
) == 0
1456 && signal_pass_state (signo
) == 1)
1458 /* FIMXE: kettenis/2001-06-06: Should we resume all threads
1459 here? It is not clear we should. GDB may not expect
1460 other threads to run. On the other hand, not resuming
1461 newly attached threads may cause an unwanted delay in
1462 getting them running. */
1463 registers_changed ();
1464 child_resume (pid_to_ptid (GET_LWP (lp
->ptid
)), lp
->step
, signo
);
1466 fprintf_unfiltered (gdb_stdlog
,
1467 "LLW: %s %s, %s (preempt 'handle')\n",
1469 "PTRACE_SINGLESTEP" : "PTRACE_CONT",
1470 target_pid_to_str (lp
->ptid
),
1471 signo
? strsignal (signo
) : "0");
1477 if (signo
== TARGET_SIGNAL_INT
&& signal_pass_state (signo
) == 0)
1479 /* If ^C/BREAK is typed at the tty/console, SIGINT gets
1480 forwarded to the entire process group, that is, all LWP's
1481 will receive it. Since we only want to report it once,
1482 we try to flush it from all LWPs except this one. */
1483 sigaddset (&flush_mask
, SIGINT
);
1487 /* This LWP is stopped now. */
1491 fprintf_unfiltered (gdb_stdlog
, "LLW: Candidate event %s in %s.\n",
1492 status_to_str (status
), target_pid_to_str (lp
->ptid
));
1494 /* Now stop all other LWP's ... */
1495 iterate_over_lwps (stop_callback
, NULL
);
1497 /* ... and wait until all of them have reported back that they're no
1499 iterate_over_lwps (stop_wait_callback
, &flush_mask
);
1501 /* If we're not waiting for a specific LWP, choose an event LWP from
1502 among those that have had events. Giving equal priority to all
1503 LWPs that have had events helps prevent starvation. */
1505 select_event_lwp (&lp
, &status
);
1507 /* Now that we've selected our final event LWP, cancel any
1508 breakpoints in other LWPs that have hit a GDB breakpoint. See
1509 the comment in cancel_breakpoints_callback to find out why. */
1510 iterate_over_lwps (cancel_breakpoints_callback
, lp
);
1512 /* If we're not running in "threaded" mode, we'll report the bare
1515 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
)
1517 trap_ptid
= (threaded
? lp
->ptid
: pid_to_ptid (GET_LWP (lp
->ptid
)));
1519 fprintf_unfiltered (gdb_stdlog
,
1520 "LLW: trap_ptid is %s.\n",
1521 target_pid_to_str (trap_ptid
));
1524 trap_ptid
= null_ptid
;
1526 store_waitstatus (ourstatus
, status
);
1527 return (threaded
? lp
->ptid
: pid_to_ptid (GET_LWP (lp
->ptid
)));
1531 kill_callback (struct lwp_info
*lp
, void *data
)
1534 ptrace (PTRACE_KILL
, GET_LWP (lp
->ptid
), 0, 0);
1536 fprintf_unfiltered (gdb_stdlog
,
1537 "KC: PTRACE_KILL %s, 0, 0 (%s)\n",
1538 target_pid_to_str (lp
->ptid
),
1539 errno
? safe_strerror (errno
) : "OK");
1545 kill_wait_callback (struct lwp_info
*lp
, void *data
)
1549 /* We must make sure that there are no pending events (delayed
1550 SIGSTOPs, pending SIGTRAPs, etc.) to make sure the current
1551 program doesn't interfere with any following debugging session. */
1553 /* For cloned processes we must check both with __WCLONE and
1554 without, since the exit status of a cloned process isn't reported
1560 pid
= waitpid (GET_LWP (lp
->ptid
), NULL
, __WCLONE
);
1561 if (pid
!= (pid_t
) -1 && debug_lin_lwp
)
1563 fprintf_unfiltered (gdb_stdlog
,
1564 "KWC: wait %s received unknown.\n",
1565 target_pid_to_str (lp
->ptid
));
1568 while (pid
== GET_LWP (lp
->ptid
));
1570 gdb_assert (pid
== -1 && errno
== ECHILD
);
1575 pid
= waitpid (GET_LWP (lp
->ptid
), NULL
, 0);
1576 if (pid
!= (pid_t
) -1 && debug_lin_lwp
)
1578 fprintf_unfiltered (gdb_stdlog
,
1579 "KWC: wait %s received unk.\n",
1580 target_pid_to_str (lp
->ptid
));
1583 while (pid
== GET_LWP (lp
->ptid
));
1585 gdb_assert (pid
== -1 && errno
== ECHILD
);
1592 /* Kill all LWP's ... */
1593 iterate_over_lwps (kill_callback
, NULL
);
1595 /* ... and wait until we've flushed all events. */
1596 iterate_over_lwps (kill_wait_callback
, NULL
);
1598 target_mourn_inferior ();
1602 lin_lwp_create_inferior (char *exec_file
, char *allargs
, char **env
)
1604 child_ops
.to_create_inferior (exec_file
, allargs
, env
);
1608 lin_lwp_mourn_inferior (void)
1610 trap_ptid
= null_ptid
;
1612 /* Destroy LWP info; it's no longer valid. */
1615 /* Restore the original signal mask. */
1616 sigprocmask (SIG_SETMASK
, &normal_mask
, NULL
);
1617 sigemptyset (&blocked_mask
);
1619 child_ops
.to_mourn_inferior ();
1623 lin_lwp_xfer_memory (CORE_ADDR memaddr
, char *myaddr
, int len
, int write
,
1624 struct mem_attrib
*attrib
, struct target_ops
*target
)
1626 struct cleanup
*old_chain
= save_inferior_ptid ();
1629 if (is_lwp (inferior_ptid
))
1630 inferior_ptid
= pid_to_ptid (GET_LWP (inferior_ptid
));
1632 xfer
= linux_proc_xfer_memory (memaddr
, myaddr
, len
, write
, attrib
, target
);
1634 xfer
= child_xfer_memory (memaddr
, myaddr
, len
, write
, attrib
, target
);
1636 do_cleanups (old_chain
);
1641 lin_lwp_thread_alive (ptid_t ptid
)
1643 gdb_assert (is_lwp (ptid
));
1646 ptrace (PTRACE_PEEKUSER
, GET_LWP (ptid
), 0, 0);
1648 fprintf_unfiltered (gdb_stdlog
,
1649 "LLTA: PTRACE_PEEKUSER %s, 0, 0 (%s)\n",
1650 target_pid_to_str (ptid
),
1651 errno
? safe_strerror (errno
) : "OK");
1659 lin_lwp_pid_to_str (ptid_t ptid
)
1661 static char buf
[64];
1665 snprintf (buf
, sizeof (buf
), "LWP %ld", GET_LWP (ptid
));
1669 return normal_pid_to_str (ptid
);
1673 init_lin_lwp_ops (void)
1676 lin_lwp_ops
.to_open
= lin_lwp_open
;
1678 lin_lwp_ops
.to_shortname
= "lwp-layer";
1679 lin_lwp_ops
.to_longname
= "lwp-layer";
1680 lin_lwp_ops
.to_doc
= "Low level threads support (LWP layer)";
1681 lin_lwp_ops
.to_attach
= lin_lwp_attach
;
1682 lin_lwp_ops
.to_detach
= lin_lwp_detach
;
1683 lin_lwp_ops
.to_resume
= lin_lwp_resume
;
1684 lin_lwp_ops
.to_wait
= lin_lwp_wait
;
1685 /* fetch_inferior_registers and store_inferior_registers will
1686 honor the LWP id, so we can use them directly. */
1687 lin_lwp_ops
.to_fetch_registers
= fetch_inferior_registers
;
1688 lin_lwp_ops
.to_store_registers
= store_inferior_registers
;
1689 lin_lwp_ops
.to_xfer_memory
= lin_lwp_xfer_memory
;
1690 lin_lwp_ops
.to_kill
= lin_lwp_kill
;
1691 lin_lwp_ops
.to_create_inferior
= lin_lwp_create_inferior
;
1692 lin_lwp_ops
.to_mourn_inferior
= lin_lwp_mourn_inferior
;
1693 lin_lwp_ops
.to_thread_alive
= lin_lwp_thread_alive
;
1694 lin_lwp_ops
.to_pid_to_str
= lin_lwp_pid_to_str
;
1695 lin_lwp_ops
.to_stratum
= thread_stratum
;
1696 lin_lwp_ops
.to_has_thread_control
= tc_schedlock
;
1697 lin_lwp_ops
.to_magic
= OPS_MAGIC
;
1701 sigchld_handler (int signo
)
1703 /* Do nothing. The only reason for this handler is that it allows
1704 us to use sigsuspend in lin_lwp_wait above to wait for the
1705 arrival of a SIGCHLD. */
1709 _initialize_lin_lwp (void)
1711 struct sigaction action
;
1713 extern void thread_db_init (struct target_ops
*);
1715 init_lin_lwp_ops ();
1716 add_target (&lin_lwp_ops
);
1717 thread_db_init (&lin_lwp_ops
);
1719 /* Save the original signal mask. */
1720 sigprocmask (SIG_SETMASK
, NULL
, &normal_mask
);
1722 action
.sa_handler
= sigchld_handler
;
1723 sigemptyset (&action
.sa_mask
);
1724 action
.sa_flags
= 0;
1725 sigaction (SIGCHLD
, &action
, NULL
);
1727 /* Make sure we don't block SIGCHLD during a sigsuspend. */
1728 sigprocmask (SIG_SETMASK
, NULL
, &suspend_mask
);
1729 sigdelset (&suspend_mask
, SIGCHLD
);
1731 sigemptyset (&blocked_mask
);
1733 add_show_from_set (add_set_cmd ("lin-lwp", no_class
, var_zinteger
,
1734 (char *) &debug_lin_lwp
,
1735 "Set debugging of GNU/Linux lwp module.\n\
1736 Enables printf debugging output.\n", &setdebuglist
), &showdebuglist
);
1740 /* FIXME: kettenis/2000-08-26: The stuff on this page is specific to
1741 the GNU/Linux Threads library and therefore doesn't really belong
1744 /* Read variable NAME in the target and return its value if found.
1745 Otherwise return zero. It is assumed that the type of the variable
1749 get_signo (const char *name
)
1751 struct minimal_symbol
*ms
;
1754 ms
= lookup_minimal_symbol (name
, NULL
, NULL
);
1758 if (target_read_memory (SYMBOL_VALUE_ADDRESS (ms
), (char *) &signo
,
1759 sizeof (signo
)) != 0)
1765 /* Return the set of signals used by the threads library in *SET. */
1768 lin_thread_get_thread_signals (sigset_t
*set
)
1770 struct sigaction action
;
1771 int restart
, cancel
;
1775 restart
= get_signo ("__pthread_sig_restart");
1779 cancel
= get_signo ("__pthread_sig_cancel");
1783 sigaddset (set
, restart
);
1784 sigaddset (set
, cancel
);
1786 /* The GNU/Linux Threads library makes terminating threads send a
1787 special "cancel" signal instead of SIGCHLD. Make sure we catch
1788 those (to prevent them from terminating GDB itself, which is
1789 likely to be their default action) and treat them the same way as
1792 action
.sa_handler
= sigchld_handler
;
1793 sigemptyset (&action
.sa_mask
);
1794 action
.sa_flags
= 0;
1795 sigaction (cancel
, &action
, NULL
);
1797 /* We block the "cancel" signal throughout this code ... */
1798 sigaddset (&blocked_mask
, cancel
);
1799 sigprocmask (SIG_BLOCK
, &blocked_mask
, NULL
);
1801 /* ... except during a sigsuspend. */
1802 sigdelset (&suspend_mask
, cancel
);