1 /* Multi-threaded debugging support for Linux (LWP layer).
2 Copyright 2000, 2001 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"
26 #include <sys/ptrace.h>
29 #include "gdbthread.h"
35 static int debug_lin_lwp
;
36 extern const char *strsignal (int sig
);
38 /* On Linux there are no real LWP's. The closest thing to LWP's are
39 processes sharing the same VM space. A multi-threaded process is
40 basically a group of such processes. However, such a grouping is
41 almost entirely a user-space issue; the kernel doesn't enforce such
42 a grouping at all (this might change in the future). In general,
43 we'll rely on the threads library (i.e. the LinuxThreads library)
44 to provide such a grouping.
46 It is perfectly well possible to write a multi-threaded application
47 without the assistance of a threads library, by using the clone
48 system call directly. This module should be able to give some
49 rudimentary support for debugging such applications if developers
50 specify the CLONE_PTRACE flag in the clone system call, and are
51 using Linux 2.4 or above.
53 Note that there are some peculiarities in Linux that affect this
56 - In general one should specify the __WCLONE flag to waitpid in
57 order to make it report events for any of the cloned processes
58 (and leave it out for the initial process). However, if a cloned
59 process has exited the exit status is only reported if the
60 __WCLONE flag is absent. Linux 2.4 has a __WALL flag, but we
61 cannot use it since GDB must work on older systems too.
63 - When a traced, cloned process exits and is waited for by the
64 debugger, the kernel reassigns it to the original parent and
65 keeps it around as a "zombie". Somehow, the LinuxThreads library
66 doesn't notice this, which leads to the "zombie problem": When
67 debugged a multi-threaded process that spawns a lot of threads
68 will run out of processes, even if the threads exit, because the
69 "zombies" stay around. */
71 /* Structure describing a LWP. */
74 /* The process id of the LWP. This is a combination of the LWP id
75 and overall process id. */
78 /* Non-zero if we sent this LWP a SIGSTOP (but the LWP didn't report
82 /* Non-zero if this LWP is stopped. */
85 /* If non-zero, a pending wait status. */
88 /* Non-zero if we were stepping this LWP. */
91 /* Next LWP in list. */
92 struct lwp_info
*next
;
95 /* List of known LWPs. */
96 static struct lwp_info
*lwp_list
;
98 /* Number of LWPs in the list. */
101 /* Non-zero if we're running in "threaded" mode. */
105 #define GET_LWP(ptid) ptid_get_lwp (ptid)
106 #define GET_PID(ptid) ptid_get_pid (ptid)
107 #define is_lwp(ptid) (GET_LWP (ptid) != 0)
108 #define BUILD_LWP(lwp, pid) ptid_build (pid, lwp, 0)
110 #define is_cloned(pid) (GET_LWP (pid) != GET_PID (pid))
112 /* If the last reported event was a SIGTRAP, this variable is set to
113 the process id of the LWP/thread that got it. */
117 /* This module's target-specific operations. */
118 static struct target_ops lin_lwp_ops
;
120 /* The standard child operations. */
121 extern struct target_ops child_ops
;
123 /* Since we cannot wait (in lin_lwp_wait) for the initial process and
124 any cloned processes with a single call to waitpid, we have to use
125 the WNOHANG flag and call waitpid in a loop. To optimize
126 things a bit we use `sigsuspend' to wake us up when a process has
127 something to report (it will send us a SIGCHLD if it has). To make
128 this work we have to juggle with the signal mask. We save the
129 original signal mask such that we can restore it before creating a
130 new process in order to avoid blocking certain signals in the
131 inferior. We then block SIGCHLD during the waitpid/sigsuspend
134 /* Original signal mask. */
135 static sigset_t normal_mask
;
137 /* Signal mask for use with sigsuspend in lin_lwp_wait, initialized in
138 _initialize_lin_lwp. */
139 static sigset_t suspend_mask
;
141 /* Signals to block to make that sigsuspend work. */
142 static sigset_t blocked_mask
;
145 /* Prototypes for local functions. */
146 static int stop_wait_callback (struct lwp_info
*lp
, void *data
);
149 /* Initialize the list of LWPs. Note that this module, contrary to
150 what GDB's generic threads layer does for its thread list,
151 re-initializes the LWP lists whenever we mourn or detach (which
152 doesn't involve mourning) the inferior. */
157 struct lwp_info
*lp
, *lpnext
;
159 for (lp
= lwp_list
; lp
; lp
= lpnext
)
170 /* Add the LWP specified by PID to the list. If this causes the
171 number of LWPs to become larger than one, go into "threaded" mode.
172 Return a pointer to the structure describing the new LWP. */
174 static struct lwp_info
*
175 add_lwp (ptid_t ptid
)
179 gdb_assert (is_lwp (ptid
));
181 lp
= (struct lwp_info
*) xmalloc (sizeof (struct lwp_info
));
183 memset (lp
, 0, sizeof (struct lwp_info
));
195 /* Remove the LWP specified by PID from the list. */
198 delete_lwp (ptid_t ptid
)
200 struct lwp_info
*lp
, *lpprev
;
204 for (lp
= lwp_list
; lp
; lpprev
= lp
, lp
= lp
->next
)
205 if (ptid_equal (lp
->ptid
, ptid
))
211 /* We don't go back to "non-threaded" mode if the number of threads
212 becomes less than two. */
216 lpprev
->next
= lp
->next
;
223 /* Return a pointer to the structure describing the LWP corresponding
224 to PID. If no corresponding LWP could be found, return NULL. */
226 static struct lwp_info
*
227 find_lwp_pid (ptid_t ptid
)
233 lwp
= GET_LWP (ptid
);
235 lwp
= GET_PID (ptid
);
237 for (lp
= lwp_list
; lp
; lp
= lp
->next
)
238 if (lwp
== GET_LWP (lp
->ptid
))
244 /* Call CALLBACK with its second argument set to DATA for every LWP in
245 the list. If CALLBACK returns 1 for a particular LWP, return a
246 pointer to the structure describing that LWP immediately.
247 Otherwise return NULL. */
250 iterate_over_lwps (int (*callback
) (struct lwp_info
*, void *), void *data
)
254 for (lp
= lwp_list
; lp
; lp
= lp
->next
)
255 if ((*callback
) (lp
, data
))
262 /* Implementation of the PREPARE_TO_PROCEED hook for the Linux LWP
265 Note that this implementation is potentially redundant now that
266 default_prepare_to_proceed() has been added. */
269 lin_lwp_prepare_to_proceed (void)
271 if (! ptid_equal (trap_ptid
, null_ptid
)
272 && ! ptid_equal (inferior_ptid
, trap_ptid
))
274 /* Switched over from TRAP_PID. */
275 CORE_ADDR stop_pc
= read_pc ();
278 /* Avoid switching where it wouldn't do any good, i.e. if both
279 threads are at the same breakpoint. */
280 trap_pc
= read_pc_pid (trap_ptid
);
281 if (trap_pc
!= stop_pc
&& breakpoint_here_p (trap_pc
))
283 /* User hasn't deleted the breakpoint. Return non-zero, and
284 switch back to TRAP_PID. */
285 inferior_ptid
= trap_ptid
;
287 /* FIXME: Is this stuff really necessary? */
288 flush_cached_frames ();
289 registers_changed ();
301 lin_lwp_open (char *args
, int from_tty
)
303 push_target (&lin_lwp_ops
);
307 /* Attach to the LWP specified by PID. If VERBOSE is non-zero, print
308 a message telling the user that a new LWP has been added to the
312 lin_lwp_attach_lwp (ptid_t ptid
, int verbose
)
316 gdb_assert (is_lwp (ptid
));
319 printf_filtered ("[New %s]\n", target_pid_to_str (ptid
));
321 /* We assume that we're already tracing the initial process. */
322 if (is_cloned (ptid
) && ptrace (PTRACE_ATTACH
, GET_LWP (ptid
), 0, 0) < 0)
323 error ("Can't attach %s: %s", target_pid_to_str (ptid
), strerror (errno
));
325 lp
= find_lwp_pid (ptid
);
329 if (is_cloned (ptid
))
332 stop_wait_callback (lp
, NULL
);
337 lin_lwp_attach (char *args
, int from_tty
)
341 /* FIXME: We should probably accept a list of process id's, and
342 attach all of them. */
343 child_ops
.to_attach (args
, from_tty
);
345 /* Add the initial process as the first LWP to the list. */
346 lp
= add_lwp (BUILD_LWP (PIDGET (inferior_ptid
), PIDGET (inferior_ptid
)));
348 /* Make sure the initial process is stopped. The user-level threads
349 layer might want to poke around in the inferior, and that won't
350 work if things haven't stabilized yet. */
352 stop_wait_callback (lp
, NULL
);
353 gdb_assert (lp
->status
== 0);
355 /* Fake the SIGSTOP that core GDB expects. */
356 lp
->status
= W_STOPCODE (SIGSTOP
);
360 detach_callback (struct lwp_info
*lp
, void *data
)
362 gdb_assert (lp
->status
== 0 || WIFSTOPPED (lp
->status
));
364 if (debug_lin_lwp
&& lp
->status
)
365 fprintf_unfiltered (gdb_stdlog
, "Pending %s for LWP %ld on detach.\n",
366 strsignal (WSTOPSIG (lp
->status
)), GET_LWP (lp
->ptid
));
368 while (lp
->signalled
&& lp
->stopped
)
370 if (ptrace (PTRACE_CONT
, GET_LWP (lp
->ptid
), 0,
371 WSTOPSIG (lp
->status
)) < 0)
372 error ("Can't continue %s: %s", target_pid_to_str (lp
->ptid
),
378 stop_wait_callback (lp
, NULL
);
380 gdb_assert (lp
->status
== 0 || WIFSTOPPED (lp
->status
));
383 if (is_cloned (lp
->ptid
))
385 if (ptrace (PTRACE_DETACH
, GET_LWP (lp
->ptid
), 0,
386 WSTOPSIG (lp
->status
)) < 0)
387 error ("Can't detach %s: %s", target_pid_to_str (lp
->ptid
),
390 delete_lwp (lp
->ptid
);
397 lin_lwp_detach (char *args
, int from_tty
)
399 iterate_over_lwps (detach_callback
, NULL
);
401 /* Only the initial (uncloned) process should be left right now. */
402 gdb_assert (num_lwps
== 1);
404 trap_ptid
= null_ptid
;
406 /* Destroy LWP info; it's no longer valid. */
409 /* Restore the original signal mask. */
410 sigprocmask (SIG_SETMASK
, &normal_mask
, NULL
);
411 sigemptyset (&blocked_mask
);
413 inferior_ptid
= pid_to_ptid (GET_PID (inferior_ptid
));
414 child_ops
.to_detach (args
, from_tty
);
418 struct private_thread_info
423 /* Return non-zero if TP corresponds to the LWP specified by DATA
424 (which is assumed to be a pointer to a `struct lwp_info'. */
427 find_lwp_callback (struct thread_info
*tp
, void *data
)
429 struct lwp_info
*lp
= data
;
431 if (tp
->private->lwpid
== GET_LWP (lp
->ptid
))
440 resume_callback (struct lwp_info
*lp
, void *data
)
442 if (lp
->stopped
&& lp
->status
== 0)
444 struct thread_info
*tp
;
447 /* FIXME: kettenis/2000-08-26: This should really be handled
448 properly by core GDB. */
450 tp
= find_thread_pid (lp
->ptid
);
452 tp
= iterate_over_threads (find_lwp_callback
, lp
);
455 /* If we were previously stepping the thread, and now continue
456 the thread we must invalidate the stepping range. However,
457 if there is a step_resume breakpoint for this thread, we must
458 preserve the stepping range to make it possible to continue
459 stepping once we hit it. */
460 if (tp
->step_range_end
&& tp
->step_resume_breakpoint
== NULL
)
462 gdb_assert (lp
->step
);
463 tp
->step_range_start
= tp
->step_range_end
= 0;
467 child_resume (pid_to_ptid (GET_LWP (lp
->ptid
)), 0, TARGET_SIGNAL_0
);
476 lin_lwp_resume (ptid_t ptid
, int step
, enum target_signal signo
)
481 /* Apparently the interpretation of PID is dependent on STEP: If
482 STEP is non-zero, a specific PID means `step only this process
483 id'. But if STEP is zero, then PID means `continue *all*
484 processes, but give the signal only to this one'. */
485 resume_all
= (PIDGET (ptid
) == -1) || !step
;
487 /* If PID is -1, it's the current inferior that should be
488 handled specially. */
489 if (PIDGET (ptid
) == -1)
490 ptid
= inferior_ptid
;
492 lp
= find_lwp_pid (ptid
);
495 ptid
= pid_to_ptid (GET_LWP (lp
->ptid
));
497 /* Remember if we're stepping. */
500 /* If we have a pending wait status for this thread, there is no
501 point in resuming the process. */
504 /* FIXME: What should we do if we are supposed to continue
505 this thread with a signal? */
506 gdb_assert (signo
== TARGET_SIGNAL_0
);
510 /* Mark LWP as not stopped to prevent it from being continued by
516 iterate_over_lwps (resume_callback
, NULL
);
518 child_resume (ptid
, step
, signo
);
522 /* Send a SIGSTOP to LP. */
525 stop_callback (struct lwp_info
*lp
, void *data
)
527 if (! lp
->stopped
&& ! lp
->signalled
)
531 ret
= kill (GET_LWP (lp
->ptid
), SIGSTOP
);
532 gdb_assert (ret
== 0);
535 gdb_assert (lp
->status
== 0);
541 /* Wait until LP is stopped. */
544 stop_wait_callback (struct lwp_info
*lp
, void *data
)
546 if (! lp
->stopped
&& lp
->signalled
)
552 gdb_assert (lp
->status
== 0);
554 pid
= waitpid (GET_LWP (lp
->ptid
), &status
,
555 is_cloned (lp
->ptid
) ? __WCLONE
: 0);
556 if (pid
== -1 && errno
== ECHILD
)
557 /* OK, the proccess has disappeared. We'll catch the actual
558 exit event in lin_lwp_wait. */
561 gdb_assert (pid
== GET_LWP (lp
->ptid
));
563 if (WIFEXITED (status
) || WIFSIGNALED (status
))
565 gdb_assert (num_lwps
> 1);
567 if (in_thread_list (lp
->ptid
))
569 /* Core GDB cannot deal with us deleting the current
571 if (!ptid_equal (lp
->ptid
, inferior_ptid
))
572 delete_thread (lp
->ptid
);
573 printf_unfiltered ("[%s exited]\n",
574 target_pid_to_str (lp
->ptid
));
577 fprintf_unfiltered (gdb_stdlog
,
578 "%s exited.\n", target_pid_to_str (lp
->ptid
));
580 delete_lwp (lp
->ptid
);
584 gdb_assert (WIFSTOPPED (status
));
587 if (WSTOPSIG (status
) != SIGSTOP
)
589 if (WSTOPSIG (status
) == SIGTRAP
590 && breakpoint_inserted_here_p (read_pc_pid (pid_to_ptid (pid
))
591 - DECR_PC_AFTER_BREAK
))
593 /* If a LWP other than the LWP that we're reporting an
594 event for has hit a GDB breakpoint (as opposed to
595 some random trap signal), then just arrange for it to
596 hit it again later. We don't keep the SIGTRAP status
597 and don't forward the SIGTRAP signal to the LWP. We
598 will handle the current event, eventually we will
599 resume all LWPs, and this one will get its breakpoint
602 If we do not do this, then we run the risk that the
603 user will delete or disable the breakpoint, but the
604 thread will have already tripped on it. */
607 fprintf_unfiltered (gdb_stdlog
,
608 "Tripped breakpoint at %lx in LWP %d"
609 " while waiting for SIGSTOP.\n",
610 (long) read_pc_pid (lp
->ptid
), pid
);
612 /* Set the PC to before the trap. */
613 if (DECR_PC_AFTER_BREAK
)
614 write_pc_pid (read_pc_pid (pid_to_ptid (pid
))
615 - DECR_PC_AFTER_BREAK
,
618 /* Now resume this LWP and get the SIGSTOP event. */
619 ptrace (PTRACE_CONT
, GET_LWP (lp
->ptid
), 0, 0);
620 goto get_another_event
;
622 else if (WSTOPSIG (status
) == SIGINT
&&
623 signal_pass_state (SIGINT
) == 0)
625 /* Since SIGINT gets forwarded to the entire process group
626 (in the case where ^C/BREAK is typed at the tty/console),
627 just ignore all SIGINT events from all lwp's except for
628 the one that was caught by lin_lwp_wait. */
630 /* Now resume this LWP and get the SIGSTP event. */
631 ptrace (PTRACE_CONT
, GET_LWP (lp
->ptid
), 0, 0);
632 goto get_another_event
;
637 fprintf_unfiltered (gdb_stdlog
,
638 "Received %s in LWP %d while waiting for SIGSTOP.\n",
639 strsignal (WSTOPSIG (status
)), pid
);
641 /* The thread was stopped with a signal other than
642 SIGSTOP, and didn't accidentally trip a breakpoint.
643 Record the wait status. */
649 /* We caught the SIGSTOP that we intended to catch, so
650 there's no SIGSTOP pending. */
658 /* Return non-zero if LP has a wait status pending. */
661 status_callback (struct lwp_info
*lp
, void *data
)
663 return (lp
->status
!= 0);
666 /* Return non-zero if LP isn't stopped. */
669 running_callback (struct lwp_info
*lp
, void *data
)
671 return (lp
->stopped
== 0);
675 lin_lwp_wait (ptid_t ptid
, struct target_waitstatus
*ourstatus
)
677 struct lwp_info
*lp
= NULL
;
680 pid_t pid
= PIDGET (ptid
);
682 /* Make sure SIGCHLD is blocked. */
683 if (! sigismember (&blocked_mask
, SIGCHLD
))
685 sigaddset (&blocked_mask
, SIGCHLD
);
686 sigprocmask (SIG_BLOCK
, &blocked_mask
, NULL
);
691 /* First check if there is a LWP with a wait status pending. */
694 /* Any LWP will do. */
695 lp
= iterate_over_lwps (status_callback
, NULL
);
699 fprintf_unfiltered (gdb_stdlog
,
700 "Using pending wait status for LWP %ld.\n",
707 /* But if we don't fine one, we'll have to wait, and check both
708 cloned and uncloned processes. We start with the cloned
710 options
= __WCLONE
| WNOHANG
;
712 else if (is_lwp (ptid
))
715 fprintf_unfiltered (gdb_stdlog
,
716 "Waiting for specific LWP %ld.\n",
719 /* We have a specific LWP to check. */
720 lp
= find_lwp_pid (ptid
);
727 fprintf_unfiltered (gdb_stdlog
,
728 "Using pending wait status for LWP %ld.\n",
731 /* If we have to wait, take into account whether PID is a cloned
732 process or not. And we have to convert it to something that
733 the layer beneath us can understand. */
734 options
= is_cloned (lp
->ptid
) ? __WCLONE
: 0;
735 pid
= GET_LWP (ptid
);
738 if (status
&& lp
->signalled
)
740 /* A pending SIGSTOP may interfere with the normal stream of
741 events. In a typical case where interference is a problem,
742 we have a SIGSTOP signal pending for LWP A while
743 single-stepping it, encounter an event in LWP B, and take the
744 pending SIGSTOP while trying to stop LWP A. After processing
745 the event in LWP B, LWP A is continued, and we'll never see
746 the SIGTRAP associated with the last time we were
747 single-stepping LWP A. */
749 /* Resume the thread. It should halt immediately returning the
751 child_resume (pid_to_ptid (GET_LWP (lp
->ptid
)), lp
->step
,
755 /* This should catch the pending SIGSTOP. */
756 stop_wait_callback (lp
, NULL
);
759 set_sigint_trap (); /* Causes SIGINT to be passed on to the
767 lwpid
= waitpid (pid
, &status
, options
);
770 gdb_assert (pid
== -1 || lwpid
== pid
);
772 lp
= find_lwp_pid (pid_to_ptid (lwpid
));
775 lp
= add_lwp (BUILD_LWP (lwpid
, GET_PID (inferior_ptid
)));
778 gdb_assert (WIFSTOPPED (status
)
779 && WSTOPSIG (status
) == SIGSTOP
);
782 if (! in_thread_list (inferior_ptid
))
784 inferior_ptid
= BUILD_LWP (GET_PID (inferior_ptid
),
785 GET_PID (inferior_ptid
));
786 add_thread (inferior_ptid
);
789 add_thread (lp
->ptid
);
790 printf_unfiltered ("[New %s]\n",
791 target_pid_to_str (lp
->ptid
));
795 /* Make sure we don't report a TARGET_WAITKIND_EXITED or
796 TARGET_WAITKIND_SIGNALLED event if there are still LWP's
797 left in the process. */
798 if ((WIFEXITED (status
) || WIFSIGNALED (status
)) && num_lwps
> 1)
800 if (in_thread_list (lp
->ptid
))
802 /* Core GDB cannot deal with us deleting the current
804 if (! ptid_equal (lp
->ptid
, inferior_ptid
))
805 delete_thread (lp
->ptid
);
806 printf_unfiltered ("[%s exited]\n",
807 target_pid_to_str (lp
->ptid
));
810 fprintf_unfiltered (gdb_stdlog
,
812 target_pid_to_str (lp
->ptid
));
814 delete_lwp (lp
->ptid
);
816 /* Make sure there is at least one thread running. */
817 gdb_assert (iterate_over_lwps (running_callback
, NULL
));
819 /* Discard the event. */
824 /* Make sure we don't report a SIGSTOP that we sent
825 ourselves in an attempt to stop an LWP. */
826 if (lp
->signalled
&& WIFSTOPPED (status
)
827 && WSTOPSIG (status
) == SIGSTOP
)
830 fprintf_unfiltered (gdb_stdlog
,
831 "Delayed SIGSTOP caught for %s.\n",
832 target_pid_to_str (lp
->ptid
));
834 /* This is a delayed SIGSTOP. */
837 child_resume (pid_to_ptid (GET_LWP (lp
->ptid
)), lp
->step
,
841 /* Discard the event. */
851 /* Alternate between checking cloned and uncloned processes. */
854 /* And suspend every time we have checked both. */
855 if (options
& __WCLONE
)
856 sigsuspend (&suspend_mask
);
859 /* We shouldn't end up here unless we want to try again. */
860 gdb_assert (status
== 0);
864 clear_sigint_trap ();
868 /* Don't report signals that GDB isn't interested in, such as
869 signals that are neither printed nor stopped upon. Stopping all
870 threads can be a bit time-consuming so if we want decent
871 performance with heavily multi-threaded programs, especially when
872 they're using a high frequency timer, we'd better avoid it if we
875 if (WIFSTOPPED (status
))
877 int signo
= target_signal_from_host (WSTOPSIG (status
));
879 if (signal_stop_state (signo
) == 0
880 && signal_print_state (signo
) == 0
881 && signal_pass_state (signo
) == 1)
883 /* First mark this LWP as "not stopped", so that
884 resume_callback will not resume it. */
886 /* Resume all threads except this one
887 (mainly to get the newly attached ones). */
888 iterate_over_lwps (resume_callback
, NULL
);
889 /* Now resume this thread, forwarding the signal to it. */
890 child_resume (pid_to_ptid (GET_LWP (lp
->ptid
)), lp
->step
, signo
);
896 /* This LWP is stopped now. */
899 /* Now stop all other LWP's ... */
900 iterate_over_lwps (stop_callback
, NULL
);
902 /* ... and wait until all of them have reported back that they're no
904 iterate_over_lwps (stop_wait_callback
, NULL
);
906 /* If we're not running in "threaded" mode, we'll report the bare
909 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
)
910 trap_ptid
= (threaded
? lp
->ptid
: pid_to_ptid (GET_LWP (lp
->ptid
)));
912 trap_ptid
= null_ptid
;
914 store_waitstatus (ourstatus
, status
);
915 return (threaded
? lp
->ptid
: pid_to_ptid (GET_LWP (lp
->ptid
)));
919 kill_callback (struct lwp_info
*lp
, void *data
)
921 ptrace (PTRACE_KILL
, GET_LWP (lp
->ptid
), 0, 0);
926 kill_wait_callback (struct lwp_info
*lp
, void *data
)
930 /* We must make sure that there are no pending events (delayed
931 SIGSTOPs, pending SIGTRAPs, etc.) to make sure the current
932 program doesn't interfere with any following debugging session. */
934 /* For cloned processes we must check both with __WCLONE and
935 without, since the exit status of a cloned process isn't reported
937 if (is_cloned (lp
->ptid
))
941 pid
= waitpid (GET_LWP (lp
->ptid
), NULL
, __WCLONE
);
943 while (pid
== GET_LWP (lp
->ptid
));
945 gdb_assert (pid
== -1 && errno
== ECHILD
);
950 pid
= waitpid (GET_LWP (lp
->ptid
), NULL
, 0);
952 while (pid
== GET_LWP (lp
->ptid
));
954 gdb_assert (pid
== -1 && errno
== ECHILD
);
961 /* Kill all LWP's ... */
962 iterate_over_lwps (kill_callback
, NULL
);
964 /* ... and wait until we've flushed all events. */
965 iterate_over_lwps (kill_wait_callback
, NULL
);
967 target_mourn_inferior ();
971 lin_lwp_create_inferior (char *exec_file
, char *allargs
, char **env
)
973 child_ops
.to_create_inferior (exec_file
, allargs
, env
);
977 lin_lwp_mourn_inferior (void)
979 trap_ptid
= null_ptid
;
981 /* Destroy LWP info; it's no longer valid. */
984 /* Restore the original signal mask. */
985 sigprocmask (SIG_SETMASK
, &normal_mask
, NULL
);
986 sigemptyset (&blocked_mask
);
988 child_ops
.to_mourn_inferior ();
992 lin_lwp_fetch_registers (int regno
)
994 struct cleanup
*old_chain
= save_inferior_ptid ();
996 if (is_lwp (inferior_ptid
))
997 inferior_ptid
= pid_to_ptid (GET_LWP (inferior_ptid
));
999 fetch_inferior_registers (regno
);
1001 do_cleanups (old_chain
);
1005 lin_lwp_store_registers (int regno
)
1007 struct cleanup
*old_chain
= save_inferior_ptid ();
1009 if (is_lwp (inferior_ptid
))
1010 inferior_ptid
= pid_to_ptid (GET_LWP (inferior_ptid
));
1012 store_inferior_registers (regno
);
1014 do_cleanups (old_chain
);
1018 lin_lwp_xfer_memory (CORE_ADDR memaddr
, char *myaddr
, int len
, int write
,
1019 struct mem_attrib
*attrib
,
1020 struct target_ops
*target
)
1022 struct cleanup
*old_chain
= save_inferior_ptid ();
1025 if (is_lwp (inferior_ptid
))
1026 inferior_ptid
= pid_to_ptid (GET_LWP (inferior_ptid
));
1028 xfer
= child_xfer_memory (memaddr
, myaddr
, len
, write
, attrib
, target
);
1030 do_cleanups (old_chain
);
1035 lin_lwp_thread_alive (ptid_t ptid
)
1037 gdb_assert (is_lwp (ptid
));
1040 ptrace (PTRACE_PEEKUSER
, GET_LWP (ptid
), 0, 0);
1048 lin_lwp_pid_to_str (ptid_t ptid
)
1050 static char buf
[64];
1054 snprintf (buf
, sizeof (buf
), "LWP %ld", GET_LWP (ptid
));
1058 return normal_pid_to_str (ptid
);
1062 init_lin_lwp_ops (void)
1065 lin_lwp_ops
.to_open
= lin_lwp_open
;
1067 lin_lwp_ops
.to_shortname
= "lwp-layer";
1068 lin_lwp_ops
.to_longname
= "lwp-layer";
1069 lin_lwp_ops
.to_doc
= "Low level threads support (LWP layer)";
1070 lin_lwp_ops
.to_attach
= lin_lwp_attach
;
1071 lin_lwp_ops
.to_detach
= lin_lwp_detach
;
1072 lin_lwp_ops
.to_resume
= lin_lwp_resume
;
1073 lin_lwp_ops
.to_wait
= lin_lwp_wait
;
1074 lin_lwp_ops
.to_fetch_registers
= lin_lwp_fetch_registers
;
1075 lin_lwp_ops
.to_store_registers
= lin_lwp_store_registers
;
1076 lin_lwp_ops
.to_xfer_memory
= lin_lwp_xfer_memory
;
1077 lin_lwp_ops
.to_kill
= lin_lwp_kill
;
1078 lin_lwp_ops
.to_create_inferior
= lin_lwp_create_inferior
;
1079 lin_lwp_ops
.to_mourn_inferior
= lin_lwp_mourn_inferior
;
1080 lin_lwp_ops
.to_thread_alive
= lin_lwp_thread_alive
;
1081 lin_lwp_ops
.to_pid_to_str
= lin_lwp_pid_to_str
;
1082 lin_lwp_ops
.to_stratum
= thread_stratum
;
1083 lin_lwp_ops
.to_has_thread_control
= tc_schedlock
;
1084 lin_lwp_ops
.to_magic
= OPS_MAGIC
;
1088 sigchld_handler (int signo
)
1090 /* Do nothing. The only reason for this handler is that it allows
1091 us to use sigsuspend in lin_lwp_wait above to wait for the
1092 arrival of a SIGCHLD. */
1096 _initialize_lin_lwp (void)
1098 struct sigaction action
;
1100 extern void thread_db_init (struct target_ops
*);
1102 init_lin_lwp_ops ();
1103 add_target (&lin_lwp_ops
);
1104 thread_db_init (&lin_lwp_ops
);
1106 /* Save the original signal mask. */
1107 sigprocmask (SIG_SETMASK
, NULL
, &normal_mask
);
1109 action
.sa_handler
= sigchld_handler
;
1110 sigemptyset (&action
.sa_mask
);
1111 action
.sa_flags
= 0;
1112 sigaction (SIGCHLD
, &action
, NULL
);
1114 /* Make sure we don't block SIGCHLD during a sigsuspend. */
1115 sigprocmask (SIG_SETMASK
, NULL
, &suspend_mask
);
1116 sigdelset (&suspend_mask
, SIGCHLD
);
1118 sigemptyset (&blocked_mask
);
1120 add_show_from_set (add_set_cmd ("lin-lwp", no_class
, var_zinteger
,
1121 (char *) &debug_lin_lwp
,
1122 "Set debugging of linux lwp module.\n\
1123 Enables printf debugging output.\n",
1129 /* FIXME: kettenis/2000-08-26: The stuff on this page is specific to
1130 the LinuxThreads library and therefore doesn't really belong here. */
1132 /* Read variable NAME in the target and return its value if found.
1133 Otherwise return zero. It is assumed that the type of the variable
1137 get_signo (const char *name
)
1139 struct minimal_symbol
*ms
;
1142 ms
= lookup_minimal_symbol (name
, NULL
, NULL
);
1146 if (target_read_memory (SYMBOL_VALUE_ADDRESS (ms
), (char *) &signo
,
1147 sizeof (signo
)) != 0)
1153 /* Return the set of signals used by the threads library in *SET. */
1156 lin_thread_get_thread_signals (sigset_t
*set
)
1158 struct sigaction action
;
1159 int restart
, cancel
;
1163 restart
= get_signo ("__pthread_sig_restart");
1167 cancel
= get_signo ("__pthread_sig_cancel");
1171 sigaddset (set
, restart
);
1172 sigaddset (set
, cancel
);
1174 /* The LinuxThreads library makes terminating threads send a special
1175 "cancel" signal instead of SIGCHLD. Make sure we catch those (to
1176 prevent them from terminating GDB itself, which is likely to be
1177 their default action) and treat them the same way as SIGCHLD. */
1179 action
.sa_handler
= sigchld_handler
;
1180 sigemptyset (&action
.sa_mask
);
1181 action
.sa_flags
= 0;
1182 sigaction (cancel
, &action
, NULL
);
1184 /* We block the "cancel" signal throughout this code ... */
1185 sigaddset (&blocked_mask
, cancel
);
1186 sigprocmask (SIG_BLOCK
, &blocked_mask
, NULL
);
1188 /* ... except during a sigsuspend. */
1189 sigdelset (&suspend_mask
, cancel
);