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"
37 extern const char *strsignal (int sig
);
40 /* On Linux there are no real LWP's. The closest thing to LWP's are
41 processes sharing the same VM space. A multi-threaded process is
42 basically a group of such processes. However, such a grouping is
43 almost entirely a user-space issue; the kernel doesn't enforce such
44 a grouping at all (this might change in the future). In general,
45 we'll rely on the threads library (i.e. the LinuxThreads library)
46 to provide such a grouping.
48 It is perfectly well possible to write a multi-threaded application
49 without the assistance of a threads library, by using the clone
50 system call directly. This module should be able to give some
51 rudimentary support for debugging such applications if developers
52 specify the CLONE_PTRACE flag in the clone system call, and are
53 using Linux 2.4 or above.
55 Note that there are some peculiarities in Linux that affect this
58 - In general one should specify the __WCLONE flag to waitpid in
59 order to make it report events for any of the cloned processes
60 (and leave it out for the initial process). However, if a cloned
61 process has exited the exit status is only reported if the
62 __WCLONE flag is absent. Linux 2.4 has a __WALL flag, but we
63 cannot use it since GDB must work on older systems too.
65 - When a traced, cloned process exits and is waited for by the
66 debugger, the kernel reassigns it to the origional parent and
67 keeps it around as a "zombie". Somehow, the LinuxThreads library
68 doesn't notice this, which leads to the "zombie problem": When
69 debugged a multi-threaded process that spawns a lot of threads
70 will run out of processes, even if the threads exit, because the
71 "zombies" stay around. */
73 /* Structure describing a LWP. */
76 /* The process id of the LWP. This is a combination of the LWP id
77 and overall process id. */
80 /* Non-zero if we sent this LWP a SIGSTOP (but the LWP didn't report
84 /* Non-zero if this LWP is stopped. */
87 /* If non-zero, a pending wait status. */
90 /* Non-zero if we were stepping this LWP. */
93 /* Next LWP in list. */
94 struct lwp_info
*next
;
97 /* List of known LWPs. */
98 static struct lwp_info
*lwp_list
;
100 /* Number of LWPs in the list. */
103 /* Non-zero if we're running in "threaded" mode. */
108 #define TIDGET(PID) (((PID) & 0x7fffffff) >> 16)
109 #define PIDGET(PID) (((PID) & 0xffff))
110 #define MERGEPID(PID, TID) (((PID) & 0xffff) | ((TID) << 16))
113 #define THREAD_FLAG 0x80000000
114 #define is_lwp(pid) (((pid) & THREAD_FLAG) == 0 && TIDGET (pid))
115 #define GET_LWP(pid) TIDGET (pid)
116 #define GET_PID(pid) PIDGET (pid)
117 #define BUILD_LWP(tid, pid) MERGEPID (pid, tid)
119 #define is_cloned(pid) (GET_LWP (pid) != GET_PID (pid))
121 /* If the last reported event was a SIGTRAP, this variable is set to
122 the process id of the LWP/thread that got it. */
126 /* This module's target-specific operations. */
127 static struct target_ops lin_lwp_ops
;
129 /* The standard child operations. */
130 extern struct target_ops child_ops
;
132 /* Since we cannot wait (in lin_lwp_wait) for the initial process and
133 any cloned processes with a single call to waitpid, we have to use
134 use the WNOHANG flag and call waitpid in a loop. To optimize
135 things a bit we use `sigsuspend' to wake us up when a process has
136 something to report (it will send us a SIGCHLD if it has). To make
137 this work we have to juggle with the signal mask. We save the
138 origional signal mask such that we can restore it before creating a
139 new process in order to avoid blocking certain signals in the
140 inferior. We then block SIGCHLD during the waitpid/sigsuspend
143 /* Origional signal mask. */
144 static sigset_t normal_mask
;
146 /* Signal mask for use with sigsuspend in lin_lwp_wait, initialized in
147 _initialize_lin_lwp. */
148 static sigset_t suspend_mask
;
150 /* Signals to block to make that sigsuspend work. */
151 static sigset_t blocked_mask
;
154 /* Prototypes for local functions. */
155 static void lin_lwp_mourn_inferior (void);
158 /* Initialize the list of LWPs. */
163 struct lwp_info
*lp
, *lpnext
;
165 for (lp
= lwp_list
; lp
; lp
= lpnext
)
176 /* Add the LWP specified by PID to the list. If this causes the
177 number of LWPs to become larger than one, go into "threaded" mode.
178 Return a pointer to the structure describing the new LWP. */
180 static struct lwp_info
*
185 gdb_assert (is_lwp (pid
));
187 lp
= (struct lwp_info
*) xmalloc (sizeof (struct lwp_info
));
189 memset (lp
, 0, sizeof (struct lwp_info
));
201 /* Remove the LWP specified by PID from the list. */
206 struct lwp_info
*lp
, *lpprev
;
210 for (lp
= lwp_list
; lp
; lpprev
= lp
, lp
= lp
->next
)
217 /* We don't go back to "non-threaded" mode if the number of threads
218 becomes less than two. */
222 lpprev
->next
= lp
->next
;
229 /* Return a pointer to the structure describing the LWP corresponding
230 to PID. If no corresponding LWP could be found, return NULL. */
232 static struct lwp_info
*
233 find_lwp_pid (int pid
)
240 for (lp
= lwp_list
; lp
; lp
= lp
->next
)
241 if (pid
== GET_LWP (lp
->pid
))
247 /* Call CALLBACK with its second argument set to DATA for every LWP in
248 the list. If CALLBACK returns 1 for a particular LWP, return a
249 pointer to the structure describing that LWP immediately.
250 Otherwise return NULL. */
253 iterate_over_lwps (int (*callback
) (struct lwp_info
*, void *), void *data
)
257 for (lp
= lwp_list
; lp
; lp
= lp
->next
)
258 if ((*callback
) (lp
, data
))
265 /* Helper functions. */
268 restore_inferior_pid (void *arg
)
270 int *saved_pid_ptr
= arg
;
271 inferior_pid
= *saved_pid_ptr
;
275 static struct cleanup
*
276 save_inferior_pid (void)
280 saved_pid_ptr
= xmalloc (sizeof (int));
281 *saved_pid_ptr
= inferior_pid
;
282 return make_cleanup (restore_inferior_pid
, saved_pid_ptr
);
286 /* Implementation of the PREPARE_TO_PROCEED hook for the Linux LWP layer. */
289 lin_lwp_prepare_to_proceed (void)
291 if (trap_pid
&& inferior_pid
!= trap_pid
)
293 /* Switched over from TRAP_PID. */
294 CORE_ADDR stop_pc
= read_pc ();
297 /* Avoid switching where it wouldn't do any good, i.e. if both
298 threads are at the same breakpoint. */
299 trap_pc
= read_pc_pid (trap_pid
);
300 if (trap_pc
!= stop_pc
&& breakpoint_here_p (trap_pc
))
302 /* User hasn't deleted the breakpoint. Return non-zero, and
303 switch back to TRAP_PID. */
304 inferior_pid
= trap_pid
;
306 /* FIXME: Is this stuff really necessary? */
307 flush_cached_frames ();
308 registers_changed ();
320 lin_lwp_open (char *args
, int from_tty
)
322 push_target (&lin_lwp_ops
);
326 /* Attach to the LWP specified by PID. If VERBOSE is non-zero, print
327 a message telling the user that a new LWP has been added to the
331 lin_lwp_attach_lwp (int pid
, int verbose
)
335 gdb_assert (is_lwp (pid
));
338 printf_filtered ("[New %s]\n", target_pid_to_str (pid
));
340 if (ptrace (PTRACE_ATTACH
, GET_LWP (pid
), 0, 0) < 0)
341 error ("Can't attach %s: %s", target_pid_to_str (pid
), strerror (errno
));
348 lin_lwp_attach (char *args
, int from_tty
)
350 /* FIXME: We should probably accept a list of process id's, and
351 attach all of them. */
352 error("Not implemented yet");
356 lin_lwp_detach (char *args
, int from_tty
)
358 /* FIXME: Provide implementation when we implement lin_lwp_attach. */
359 error ("Not implemented yet");
363 struct private_thread_info
368 /* Return non-zero if TP corresponds to the LWP specified by DATA
369 (which is assumed to be a pointer to a `struct lwp_info'. */
372 find_lwp_callback (struct thread_info
*tp
, void *data
)
374 struct lwp_info
*lp
= data
;
376 if (tp
->private->lwpid
== GET_LWP (lp
->pid
))
385 resume_callback (struct lwp_info
*lp
, void *data
)
387 if (lp
->stopped
&& lp
->status
== 0)
389 struct thread_info
*tp
;
392 /* FIXME: kettenis/2000-08-26: This should really be handled
393 properly by core GDB. */
395 tp
= find_thread_pid (lp
->pid
);
397 tp
= iterate_over_threads (find_lwp_callback
, lp
);
400 /* If we were previously stepping the thread, and now continue
401 the thread we must invalidate the stepping range. However,
402 if there is a step_resume breakpoint for this thread, we must
403 preserve the stepping range to make it possible to continue
404 stepping once we hit it. */
405 if (tp
->step_range_end
&& tp
->step_resume_breakpoint
== NULL
)
407 gdb_assert (lp
->step
);
408 tp
->step_range_start
= tp
->step_range_end
= 0;
412 child_resume (GET_LWP (lp
->pid
), 0, TARGET_SIGNAL_0
);
421 lin_lwp_resume (int pid
, int step
, enum target_signal signo
)
426 /* Apparently the interpretation of PID is dependent on STEP: If
427 STEP is non-zero, a specific PID means `step only this process
428 id'. But if STEP is zero, then PID means `continue *all*
429 processes, but give the signal only to this one'. */
430 resume_all
= (pid
== -1) || !step
;
432 /* If PID is -1, it's the current inferior that should be
437 lp
= find_lwp_pid (pid
);
440 pid
= GET_LWP (lp
->pid
);
442 /* Mark LWP as not stopped to prevent it from being continued by
446 /* Remember if we're stepping. */
449 /* If we have a pending wait status for this thread, there is no
450 point in resuming the process. */
453 /* FIXME: What should we do if we are supposed to continue
454 this thread with a signal? */
455 gdb_assert (signo
== TARGET_SIGNAL_0
);
461 iterate_over_lwps (resume_callback
, NULL
);
463 child_resume (pid
, step
, signo
);
467 /* Send a SIGSTOP to LP. */
470 stop_callback (struct lwp_info
*lp
, void *data
)
472 if (! lp
->stopped
&& ! lp
->signalled
)
476 ret
= kill (GET_LWP (lp
->pid
), SIGSTOP
);
477 gdb_assert (ret
== 0);
480 gdb_assert (lp
->status
== 0);
486 /* Wait until LP is stopped. */
489 stop_wait_callback (struct lwp_info
*lp
, void *data
)
491 if (! lp
->stopped
&& lp
->signalled
)
496 gdb_assert (lp
->status
== 0);
498 pid
= waitpid (GET_LWP (lp
->pid
), &status
,
499 is_cloned (lp
->pid
) ? __WCLONE
: 0);
500 if (pid
== -1 && errno
== ECHILD
)
501 /* OK, the proccess has disappeared. We'll catch the actual
502 exit event in lin_lwp_wait. */
505 gdb_assert (pid
== GET_LWP (lp
->pid
));
507 if (WIFEXITED (status
) || WIFSIGNALED (status
))
509 gdb_assert (num_lwps
> 1);
511 if (in_thread_list (lp
->pid
))
513 /* Core GDB cannot deal with us deleting the current
515 if (lp
->pid
!= inferior_pid
)
516 delete_thread (lp
->pid
);
517 printf_unfiltered ("[%s exited]\n",
518 target_pid_to_str (lp
->pid
));
521 printf ("%s exited.\n", target_pid_to_str (lp
->pid
));
523 delete_lwp (lp
->pid
);
527 gdb_assert (WIFSTOPPED (status
));
530 if (WSTOPSIG (status
) != SIGSTOP
)
532 if (WSTOPSIG (status
) == SIGTRAP
533 && breakpoint_inserted_here_p (read_pc_pid (pid
)
534 - DECR_PC_AFTER_BREAK
))
536 /* If a LWP other than the LWP that we're reporting an
537 event for has hit a GDB breakpoint (as opposed to
538 some random trap signal), then just arrange for it to
539 hit it again later. We don't keep the SIGTRAP status
540 and don't forward the SIGTRAP signal to the LWP. We
541 will handle the current event, eventually we will
542 resume all LWPs, and this one will get its breakpoint
545 If we do not do this, then we run the risk that the
546 user will delete or disable the breakpoint, but the
547 thread will have already tripped on it. */
549 printf ("Tripped breakpoint at %lx in LWP %d"
550 " while waiting for SIGSTOP.\n",
551 (long) read_pc_pid (lp
->pid
), pid
);
553 /* Set the PC to before the trap. */
554 if (DECR_PC_AFTER_BREAK
)
555 write_pc_pid (read_pc_pid (pid
) - DECR_PC_AFTER_BREAK
, pid
);
560 printf ("Received %s in LWP %d while waiting for SIGSTOP.\n",
561 strsignal (WSTOPSIG (status
)), pid
);
563 /* The thread was stopped with a signal other than
564 SIGSTOP, and didn't accidentiliy trip a breakpoint.
565 Record the wait status. */
571 /* We caught the SIGSTOP that we intended to catch, so
572 there's no SIGSTOP pending. */
580 /* Return non-zero if LP has a wait status pending. */
583 status_callback (struct lwp_info
*lp
, void *data
)
585 return (lp
->status
!= 0);
588 /* Return non-zero if LP isn't stopped. */
591 running_callback (struct lwp_info
*lp
, void *data
)
593 return (lp
->stopped
== 0);
597 lin_lwp_wait (int pid
, struct target_waitstatus
*ourstatus
)
599 struct lwp_info
*lp
= NULL
;
603 /* Make sure SIGCHLD is blocked. */
604 if (! sigismember (&blocked_mask
, SIGCHLD
))
606 sigaddset (&blocked_mask
, SIGCHLD
);
607 sigprocmask (SIG_BLOCK
, &blocked_mask
, NULL
);
612 /* First check if there is a LWP with a wait status pending. */
615 /* Any LWP will do. */
616 lp
= iterate_over_lwps (status_callback
, NULL
);
620 printf ("Using pending wait status for LWP %d.\n",
627 /* But if we don't fine one, we'll have to wait, and check both
628 cloned and uncloned processes. We start with the cloned
630 options
= __WCLONE
| WNOHANG
;
632 else if (is_lwp (pid
))
635 printf ("Waiting for specific LWP %d.\n", GET_LWP (pid
));
637 /* We have a specific LWP to check. */
638 lp
= find_lwp_pid (GET_LWP (pid
));
644 printf ("Using pending wait status for LWP %d.\n",
648 /* If we have to wait, take into account whether PID is a cloned
649 process or not. And we have to convert it to something that
650 the layer beneath us can understand. */
651 options
= is_cloned (lp
->pid
) ? __WCLONE
: 0;
655 if (status
&& lp
->signalled
)
657 /* A pending SIGSTOP may interfere with the normal stream of
658 events. In a typical case where interference is a problem,
659 we have a SIGSTOP signal pending for LWP A while
660 single-stepping it, encounter an event in LWP B, and take the
661 pending SIGSTOP while trying to stop LWP A. After processing
662 the event in LWP B, LWP A is continued, and we'll never see
663 the SIGTRAP associated with the last time we were
664 single-stepping LWP A. */
666 /* Resume the thread. It should halt immediately returning the
668 child_resume (GET_LWP (lp
->pid
), lp
->step
, TARGET_SIGNAL_0
);
671 /* This should catch the pending SIGSTOP. */
672 stop_wait_callback (lp
, NULL
);
675 set_sigint_trap (); /* Causes SIGINT to be passed on to the
683 lwpid
= waitpid (pid
, &status
, options
);
686 gdb_assert (pid
== -1 || lwpid
== pid
);
688 lp
= find_lwp_pid (lwpid
);
691 lp
= add_lwp (BUILD_LWP (lwpid
, inferior_pid
));
694 gdb_assert (WIFSTOPPED (status
)
695 && WSTOPSIG (status
) == SIGSTOP
);
698 if (! in_thread_list (inferior_pid
))
700 inferior_pid
= BUILD_LWP (inferior_pid
, inferior_pid
);
701 add_thread (inferior_pid
);
704 add_thread (lp
->pid
);
705 printf_unfiltered ("[New %s]\n",
706 target_pid_to_str (lp
->pid
));
710 /* Make sure we don't report a TARGET_WAITKIND_EXITED or
711 TARGET_WAITKIND_SIGNALLED event if there are still LWP's
712 left in the process. */
713 if ((WIFEXITED (status
) || WIFSIGNALED (status
)) && num_lwps
> 1)
715 if (in_thread_list (lp
->pid
))
717 /* Core GDB cannot deal with us deleting the current
719 if (lp
->pid
!= inferior_pid
)
720 delete_thread (lp
->pid
);
721 printf_unfiltered ("[%s exited]\n",
722 target_pid_to_str (lp
->pid
));
725 printf ("%s exited.\n", target_pid_to_str (lp
->pid
));
727 delete_lwp (lp
->pid
);
729 /* Make sure there is at least one thread running. */
730 gdb_assert (iterate_over_lwps (running_callback
, NULL
));
732 /* Discard the event. */
737 /* Make sure we don't report a SIGSTOP that we sent
738 ourselves in an attempt to stop an LWP. */
739 if (lp
->signalled
&& WIFSTOPPED (status
)
740 && WSTOPSIG (status
) == SIGSTOP
)
743 printf ("Delayed SIGSTOP caught for %s.\n",
744 target_pid_to_str (lp
->pid
));
746 /* This is a delayed SIGSTOP. */
749 child_resume (GET_LWP (lp
->pid
), lp
->step
, TARGET_SIGNAL_0
);
752 /* Discard the event. */
762 /* Alternate between checking cloned and uncloned processes. */
765 /* And suspend every time we have checked both. */
766 if (options
& __WCLONE
)
767 sigsuspend (&suspend_mask
);
770 /* We shouldn't end up here unless we want to try again. */
771 gdb_assert (status
== 0);
775 clear_sigint_trap ();
779 /* Don't report signals that GDB isn't interested in, such as
780 signals that are neither printed nor stopped upon. Stopping all
781 threads can be a bit time-consuming so if we want decent
782 performance with heavily multi-threaded programs, especially when
783 they're using a high frequency timer, we'd better avoid it if we
786 if (WIFSTOPPED (status
))
788 int signo
= target_signal_from_host (WSTOPSIG (status
));
790 if (signal_stop_state (signo
) == 0
791 && signal_print_state (signo
) == 0
792 && signal_pass_state (signo
) == 1)
794 child_resume (GET_LWP (lp
->pid
), lp
->step
, signo
);
801 /* This LWP is stopped now. */
804 /* Now stop all other LWP's ... */
805 iterate_over_lwps (stop_callback
, NULL
);
807 /* ... and wait until all of them have reported back that they're no
809 iterate_over_lwps (stop_wait_callback
, NULL
);
811 /* If we're not running in "threaded" mode, we'll report the bare
814 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
)
815 trap_pid
= (threaded
? lp
->pid
: GET_LWP (lp
->pid
));
819 store_waitstatus (ourstatus
, status
);
820 return (threaded
? lp
->pid
: GET_LWP (lp
->pid
));
824 kill_callback (struct lwp_info
*lp
, void *data
)
826 ptrace (PTRACE_KILL
, GET_LWP (lp
->pid
), 0, 0);
831 kill_wait_callback (struct lwp_info
*lp
, void *data
)
835 /* We must make sure that there are no pending events (delayed
836 SIGSTOPs, pending SIGTRAPs, etc.) to make sure the current
837 program doesn't interfere with any following debugging session. */
839 /* For cloned processes we must check both with __WCLONE and
840 without, since the exit status of a cloned process isn't reported
842 if (is_cloned (lp
->pid
))
846 pid
= waitpid (GET_LWP (lp
->pid
), NULL
, __WCLONE
);
848 while (pid
== GET_LWP (lp
->pid
));
850 gdb_assert (pid
== -1 && errno
== ECHILD
);
855 pid
= waitpid (GET_LWP (lp
->pid
), NULL
, 0);
857 while (pid
== GET_LWP (lp
->pid
));
859 gdb_assert (pid
== -1 && errno
== ECHILD
);
866 /* Kill all LWP's ... */
867 iterate_over_lwps (kill_callback
, NULL
);
869 /* ... and wait until we've flushed all events. */
870 iterate_over_lwps (kill_wait_callback
, NULL
);
872 target_mourn_inferior ();
876 lin_lwp_create_inferior (char *exec_file
, char *allargs
, char **env
)
878 struct target_ops
*target_beneath
;
883 target_beneath
= find_target_beneath (&lin_lwp_ops
);
885 target_beneath
= &child_ops
;
887 target_beneath
->to_create_inferior (exec_file
, allargs
, env
);
891 lin_lwp_mourn_inferior (void)
893 struct target_ops
*target_beneath
;
899 /* Restore the origional signal mask. */
900 sigprocmask (SIG_SETMASK
, &normal_mask
, NULL
);
901 sigemptyset (&blocked_mask
);
904 target_beneath
= find_target_beneath (&lin_lwp_ops
);
906 target_beneath
= &child_ops
;
908 target_beneath
->to_mourn_inferior ();
912 lin_lwp_fetch_registers (int regno
)
914 struct cleanup
*old_chain
= save_inferior_pid ();
916 if (is_lwp (inferior_pid
))
917 inferior_pid
= GET_LWP (inferior_pid
);
919 fetch_inferior_registers (regno
);
921 do_cleanups (old_chain
);
925 lin_lwp_store_registers (int regno
)
927 struct cleanup
*old_chain
= save_inferior_pid ();
929 if (is_lwp (inferior_pid
))
930 inferior_pid
= GET_LWP (inferior_pid
);
932 store_inferior_registers (regno
);
934 do_cleanups (old_chain
);
938 lin_lwp_xfer_memory (CORE_ADDR memaddr
, char *myaddr
, int len
, int write
,
939 struct mem_attrib
*attrib
,
940 struct target_ops
*target
)
942 struct cleanup
*old_chain
= save_inferior_pid ();
945 if (is_lwp (inferior_pid
))
946 inferior_pid
= GET_LWP (inferior_pid
);
948 xfer
= child_xfer_memory (memaddr
, myaddr
, len
, write
, attrib
, target
);
950 do_cleanups (old_chain
);
955 lin_lwp_thread_alive (int pid
)
957 gdb_assert (is_lwp (pid
));
960 ptrace (PTRACE_PEEKUSER
, GET_LWP (pid
), 0, 0);
968 lin_lwp_pid_to_str (int pid
)
974 snprintf (buf
, sizeof (buf
), "LWP %d", GET_LWP (pid
));
978 return normal_pid_to_str (pid
);
982 init_lin_lwp_ops (void)
985 lin_lwp_ops
.to_open
= lin_lwp_open
;
987 lin_lwp_ops
.to_shortname
= "lwp-layer";
988 lin_lwp_ops
.to_longname
= "lwp-layer";
989 lin_lwp_ops
.to_doc
= "Low level threads support (LWP layer)";
990 lin_lwp_ops
.to_attach
= lin_lwp_attach
;
991 lin_lwp_ops
.to_detach
= lin_lwp_detach
;
992 lin_lwp_ops
.to_resume
= lin_lwp_resume
;
993 lin_lwp_ops
.to_wait
= lin_lwp_wait
;
994 lin_lwp_ops
.to_fetch_registers
= lin_lwp_fetch_registers
;
995 lin_lwp_ops
.to_store_registers
= lin_lwp_store_registers
;
996 lin_lwp_ops
.to_xfer_memory
= lin_lwp_xfer_memory
;
997 lin_lwp_ops
.to_kill
= lin_lwp_kill
;
998 lin_lwp_ops
.to_create_inferior
= lin_lwp_create_inferior
;
999 lin_lwp_ops
.to_mourn_inferior
= lin_lwp_mourn_inferior
;
1000 lin_lwp_ops
.to_thread_alive
= lin_lwp_thread_alive
;
1001 lin_lwp_ops
.to_pid_to_str
= lin_lwp_pid_to_str
;
1002 lin_lwp_ops
.to_stratum
= thread_stratum
;
1003 lin_lwp_ops
.to_has_thread_control
= tc_schedlock
;
1004 lin_lwp_ops
.to_magic
= OPS_MAGIC
;
1008 sigchld_handler (int signo
)
1010 /* Do nothing. The only reason for this handler is that it allows
1011 us to use sigsuspend in lin_lwp_wait above to wait for the
1012 arrival of a SIGCHLD. */
1016 _initialize_lin_lwp (void)
1018 struct sigaction action
;
1020 extern void thread_db_init (struct target_ops
*);
1022 init_lin_lwp_ops ();
1023 add_target (&lin_lwp_ops
);
1024 thread_db_init (&lin_lwp_ops
);
1026 /* Save the origional signal mask. */
1027 sigprocmask (SIG_SETMASK
, NULL
, &normal_mask
);
1029 action
.sa_handler
= sigchld_handler
;
1030 sigemptyset (&action
.sa_mask
);
1031 action
.sa_flags
= 0;
1032 sigaction (SIGCHLD
, &action
, NULL
);
1034 /* Make sure we don't block SIGCHLD during a sigsuspend. */
1035 sigprocmask (SIG_SETMASK
, NULL
, &suspend_mask
);
1036 sigdelset (&suspend_mask
, SIGCHLD
);
1038 sigemptyset (&blocked_mask
);
1042 /* FIXME: kettenis/2000-08-26: The stuff on this page is specific to
1043 the LinuxThreads library and therefore doesn't really belong here. */
1045 /* Read variable NAME in the target and return its value if found.
1046 Otherwise return zero. It is assumed that the type of the variable
1050 get_signo (const char *name
)
1052 struct minimal_symbol
*ms
;
1055 ms
= lookup_minimal_symbol (name
, NULL
, NULL
);
1059 if (target_read_memory (SYMBOL_VALUE_ADDRESS (ms
), (char *) &signo
,
1060 sizeof (signo
)) != 0)
1066 /* Return the set of signals used by the threads library in *SET. */
1069 lin_thread_get_thread_signals (sigset_t
*set
)
1071 struct sigaction action
;
1072 int restart
, cancel
;
1076 restart
= get_signo ("__pthread_sig_restart");
1080 cancel
= get_signo ("__pthread_sig_cancel");
1084 sigaddset (set
, restart
);
1085 sigaddset (set
, cancel
);
1087 /* The LinuxThreads library makes terminating threads send a special
1088 "cancel" signal instead of SIGCHLD. Make sure we catch those (to
1089 prevent them from terminating GDB itself, which is likely to be
1090 their default action) and treat them the same way as SIGCHLD. */
1092 action
.sa_handler
= sigchld_handler
;
1093 sigemptyset (&action
.sa_mask
);
1094 action
.sa_flags
= 0;
1095 sigaction (cancel
, &action
, NULL
);
1097 /* We block the "cancel" signal throughout this code ... */
1098 sigaddset (&blocked_mask
, cancel
);
1099 sigprocmask (SIG_BLOCK
, &blocked_mask
, NULL
);
1101 /* ... except during a sigsuspend. */
1102 sigdelset (&suspend_mask
, cancel
);
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