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 /* Non-zero if this LWP will be/has been resumed. Note that an LWP
86 can be marked both as stopped and resumed at the same time. This
87 happens if we try to resume an LWP that has a wait status
88 pending. We shouldn't let the LWP run until that wait status has
89 been processed, but we should not report that wait status if GDB
90 didn't try to let the LWP run. */
93 /* If non-zero, a pending wait status. */
96 /* Non-zero if we were stepping this LWP. */
99 /* Next LWP in list. */
100 struct lwp_info
*next
;
103 /* List of known LWPs. */
104 static struct lwp_info
*lwp_list
;
106 /* Number of LWPs in the list. */
109 /* Non-zero if we're running in "threaded" mode. */
113 #define GET_LWP(ptid) ptid_get_lwp (ptid)
114 #define GET_PID(ptid) ptid_get_pid (ptid)
115 #define is_lwp(ptid) (GET_LWP (ptid) != 0)
116 #define BUILD_LWP(lwp, pid) ptid_build (pid, lwp, 0)
118 #define is_cloned(pid) (GET_LWP (pid) != GET_PID (pid))
120 /* If the last reported event was a SIGTRAP, this variable is set to
121 the process id of the LWP/thread that got it. */
125 /* This module's target-specific operations. */
126 static struct target_ops lin_lwp_ops
;
128 /* The standard child operations. */
129 extern struct target_ops child_ops
;
131 /* Since we cannot wait (in lin_lwp_wait) for the initial process and
132 any cloned processes with a single call to waitpid, we have to use
133 the WNOHANG flag and call waitpid in a loop. To optimize
134 things a bit we use `sigsuspend' to wake us up when a process has
135 something to report (it will send us a SIGCHLD if it has). To make
136 this work we have to juggle with the signal mask. We save the
137 original signal mask such that we can restore it before creating a
138 new process in order to avoid blocking certain signals in the
139 inferior. We then block SIGCHLD during the waitpid/sigsuspend
142 /* Original signal mask. */
143 static sigset_t normal_mask
;
145 /* Signal mask for use with sigsuspend in lin_lwp_wait, initialized in
146 _initialize_lin_lwp. */
147 static sigset_t suspend_mask
;
149 /* Signals to block to make that sigsuspend work. */
150 static sigset_t blocked_mask
;
153 /* Prototypes for local functions. */
154 static int stop_wait_callback (struct lwp_info
*lp
, void *data
);
157 /* Initialize the list of LWPs. Note that this module, contrary to
158 what GDB's generic threads layer does for its thread list,
159 re-initializes the LWP lists whenever we mourn or detach (which
160 doesn't involve mourning) the inferior. */
165 struct lwp_info
*lp
, *lpnext
;
167 for (lp
= lwp_list
; lp
; lp
= lpnext
)
178 /* Add the LWP specified by PID to the list. If this causes the
179 number of LWPs to become larger than one, go into "threaded" mode.
180 Return a pointer to the structure describing the new LWP. */
182 static struct lwp_info
*
183 add_lwp (ptid_t ptid
)
187 gdb_assert (is_lwp (ptid
));
189 lp
= (struct lwp_info
*) xmalloc (sizeof (struct lwp_info
));
191 memset (lp
, 0, sizeof (struct lwp_info
));
203 /* Remove the LWP specified by PID from the list. */
206 delete_lwp (ptid_t ptid
)
208 struct lwp_info
*lp
, *lpprev
;
212 for (lp
= lwp_list
; lp
; lpprev
= lp
, lp
= lp
->next
)
213 if (ptid_equal (lp
->ptid
, ptid
))
219 /* We don't go back to "non-threaded" mode if the number of threads
220 becomes less than two. */
224 lpprev
->next
= lp
->next
;
231 /* Return a pointer to the structure describing the LWP corresponding
232 to PID. If no corresponding LWP could be found, return NULL. */
234 static struct lwp_info
*
235 find_lwp_pid (ptid_t ptid
)
241 lwp
= GET_LWP (ptid
);
243 lwp
= GET_PID (ptid
);
245 for (lp
= lwp_list
; lp
; lp
= lp
->next
)
246 if (lwp
== GET_LWP (lp
->ptid
))
252 /* Call CALLBACK with its second argument set to DATA for every LWP in
253 the list. If CALLBACK returns 1 for a particular LWP, return a
254 pointer to the structure describing that LWP immediately.
255 Otherwise return NULL. */
258 iterate_over_lwps (int (*callback
) (struct lwp_info
*, void *), void *data
)
260 struct lwp_info
*lp
, *lpnext
;
262 for (lp
= lwp_list
; lp
; lp
= lpnext
)
265 if ((*callback
) (lp
, data
))
273 /* Implementation of the PREPARE_TO_PROCEED hook for the Linux LWP
276 Note that this implementation is potentially redundant now that
277 default_prepare_to_proceed() has been added.
279 FIXME This may not support switching threads after Ctrl-C
280 correctly. The default implementation does support this. */
283 lin_lwp_prepare_to_proceed (void)
285 if (! ptid_equal (trap_ptid
, null_ptid
)
286 && ! ptid_equal (inferior_ptid
, trap_ptid
))
288 /* Switched over from TRAP_PID. */
289 CORE_ADDR stop_pc
= read_pc ();
292 /* Avoid switching where it wouldn't do any good, i.e. if both
293 threads are at the same breakpoint. */
294 trap_pc
= read_pc_pid (trap_ptid
);
295 if (trap_pc
!= stop_pc
&& breakpoint_here_p (trap_pc
))
297 /* User hasn't deleted the breakpoint. Return non-zero, and
298 switch back to TRAP_PID. */
299 inferior_ptid
= trap_ptid
;
301 /* FIXME: Is this stuff really necessary? */
302 flush_cached_frames ();
303 registers_changed ();
315 lin_lwp_open (char *args
, int from_tty
)
317 push_target (&lin_lwp_ops
);
321 /* Attach to the LWP specified by PID. If VERBOSE is non-zero, print
322 a message telling the user that a new LWP has been added to the
326 lin_lwp_attach_lwp (ptid_t ptid
, int verbose
)
330 gdb_assert (is_lwp (ptid
));
333 printf_filtered ("[New %s]\n", target_pid_to_str (ptid
));
335 /* We assume that we're already tracing the initial process. */
336 if (is_cloned (ptid
) && ptrace (PTRACE_ATTACH
, GET_LWP (ptid
), 0, 0) < 0)
337 error ("Can't attach %s: %s", target_pid_to_str (ptid
), strerror (errno
));
339 lp
= find_lwp_pid (ptid
);
343 if (is_cloned (ptid
))
346 stop_wait_callback (lp
, NULL
);
351 lin_lwp_attach (char *args
, int from_tty
)
355 /* FIXME: We should probably accept a list of process id's, and
356 attach all of them. */
357 child_ops
.to_attach (args
, from_tty
);
359 /* Add the initial process as the first LWP to the list. */
360 lp
= add_lwp (BUILD_LWP (PIDGET (inferior_ptid
), PIDGET (inferior_ptid
)));
362 /* Make sure the initial process is stopped. The user-level threads
363 layer might want to poke around in the inferior, and that won't
364 work if things haven't stabilized yet. */
366 stop_wait_callback (lp
, NULL
);
367 gdb_assert (lp
->status
== 0);
369 /* Fake the SIGSTOP that core GDB expects. */
370 lp
->status
= W_STOPCODE (SIGSTOP
);
375 detach_callback (struct lwp_info
*lp
, void *data
)
377 gdb_assert (lp
->status
== 0 || WIFSTOPPED (lp
->status
));
379 if (debug_lin_lwp
&& lp
->status
)
380 fprintf_unfiltered (gdb_stdlog
, "Pending %s for LWP %ld on detach.\n",
381 strsignal (WSTOPSIG (lp
->status
)), GET_LWP (lp
->ptid
));
383 while (lp
->signalled
&& lp
->stopped
)
385 if (ptrace (PTRACE_CONT
, GET_LWP (lp
->ptid
), 0,
386 WSTOPSIG (lp
->status
)) < 0)
387 error ("Can't continue %s: %s", target_pid_to_str (lp
->ptid
),
393 stop_wait_callback (lp
, NULL
);
395 gdb_assert (lp
->status
== 0 || WIFSTOPPED (lp
->status
));
398 if (is_cloned (lp
->ptid
))
400 if (ptrace (PTRACE_DETACH
, GET_LWP (lp
->ptid
), 0,
401 WSTOPSIG (lp
->status
)) < 0)
402 error ("Can't detach %s: %s", target_pid_to_str (lp
->ptid
),
405 delete_lwp (lp
->ptid
);
412 lin_lwp_detach (char *args
, int from_tty
)
414 iterate_over_lwps (detach_callback
, NULL
);
416 /* Only the initial (uncloned) process should be left right now. */
417 gdb_assert (num_lwps
== 1);
419 trap_ptid
= null_ptid
;
421 /* Destroy LWP info; it's no longer valid. */
424 /* Restore the original signal mask. */
425 sigprocmask (SIG_SETMASK
, &normal_mask
, NULL
);
426 sigemptyset (&blocked_mask
);
428 inferior_ptid
= pid_to_ptid (GET_PID (inferior_ptid
));
429 child_ops
.to_detach (args
, from_tty
);
433 struct private_thread_info
438 /* Return non-zero if TP corresponds to the LWP specified by DATA
439 (which is assumed to be a pointer to a `struct lwp_info'. */
442 find_lwp_callback (struct thread_info
*tp
, void *data
)
444 struct lwp_info
*lp
= data
;
446 if (tp
->private->lwpid
== GET_LWP (lp
->ptid
))
455 resume_callback (struct lwp_info
*lp
, void *data
)
457 if (lp
->stopped
&& lp
->status
== 0)
459 struct thread_info
*tp
;
462 /* FIXME: kettenis/2000-08-26: This should really be handled
463 properly by core GDB. */
465 tp
= find_thread_pid (lp
->ptid
);
467 tp
= iterate_over_threads (find_lwp_callback
, lp
);
470 /* If we were previously stepping the thread, and now continue
471 the thread we must invalidate the stepping range. However,
472 if there is a step_resume breakpoint for this thread, we must
473 preserve the stepping range to make it possible to continue
474 stepping once we hit it. */
475 if (tp
->step_range_end
&& tp
->step_resume_breakpoint
== NULL
)
477 gdb_assert (lp
->step
);
478 tp
->step_range_start
= tp
->step_range_end
= 0;
482 child_resume (pid_to_ptid (GET_LWP (lp
->ptid
)), 0, TARGET_SIGNAL_0
);
491 resume_clear_callback (struct lwp_info
*lp
, void *data
)
498 resume_set_callback (struct lwp_info
*lp
, void *data
)
505 lin_lwp_resume (ptid_t ptid
, int step
, enum target_signal signo
)
510 /* Apparently the interpretation of PID is dependent on STEP: If
511 STEP is non-zero, a specific PID means `step only this process
512 id'. But if STEP is zero, then PID means `continue *all*
513 processes, but give the signal only to this one'. */
514 resume_all
= (PIDGET (ptid
) == -1) || !step
;
517 iterate_over_lwps (resume_set_callback
, NULL
);
519 iterate_over_lwps (resume_clear_callback
, NULL
);
521 /* If PID is -1, it's the current inferior that should be
522 handled specially. */
523 if (PIDGET (ptid
) == -1)
524 ptid
= inferior_ptid
;
526 lp
= find_lwp_pid (ptid
);
529 ptid
= pid_to_ptid (GET_LWP (lp
->ptid
));
531 /* Remember if we're stepping. */
534 /* Mark this LWP as resumed. */
537 /* If we have a pending wait status for this thread, there is no
538 point in resuming the process. */
541 /* FIXME: What should we do if we are supposed to continue
542 this thread with a signal? */
543 gdb_assert (signo
== TARGET_SIGNAL_0
);
547 /* Mark LWP as not stopped to prevent it from being continued by
553 iterate_over_lwps (resume_callback
, NULL
);
555 child_resume (ptid
, step
, signo
);
559 /* Send a SIGSTOP to LP. */
562 stop_callback (struct lwp_info
*lp
, void *data
)
564 if (! lp
->stopped
&& ! lp
->signalled
)
568 ret
= kill (GET_LWP (lp
->ptid
), SIGSTOP
);
569 gdb_assert (ret
== 0);
572 gdb_assert (lp
->status
== 0);
578 /* Wait until LP is stopped. */
581 stop_wait_callback (struct lwp_info
*lp
, void *data
)
583 if (! lp
->stopped
&& lp
->signalled
)
589 gdb_assert (lp
->status
== 0);
591 pid
= waitpid (GET_LWP (lp
->ptid
), &status
,
592 is_cloned (lp
->ptid
) ? __WCLONE
: 0);
593 if (pid
== -1 && errno
== ECHILD
)
594 /* OK, the proccess has disappeared. We'll catch the actual
595 exit event in lin_lwp_wait. */
598 gdb_assert (pid
== GET_LWP (lp
->ptid
));
600 if (WIFEXITED (status
) || WIFSIGNALED (status
))
602 gdb_assert (num_lwps
> 1);
604 if (in_thread_list (lp
->ptid
))
606 /* Core GDB cannot deal with us deleting the current
608 if (!ptid_equal (lp
->ptid
, inferior_ptid
))
609 delete_thread (lp
->ptid
);
610 printf_unfiltered ("[%s exited]\n",
611 target_pid_to_str (lp
->ptid
));
614 fprintf_unfiltered (gdb_stdlog
,
615 "%s exited.\n", target_pid_to_str (lp
->ptid
));
617 delete_lwp (lp
->ptid
);
621 gdb_assert (WIFSTOPPED (status
));
624 if (WSTOPSIG (status
) != SIGSTOP
)
626 if (WSTOPSIG (status
) == SIGTRAP
627 && breakpoint_inserted_here_p (read_pc_pid (pid_to_ptid (pid
))
628 - DECR_PC_AFTER_BREAK
))
630 /* If a LWP other than the LWP that we're reporting an
631 event for has hit a GDB breakpoint (as opposed to
632 some random trap signal), then just arrange for it to
633 hit it again later. We don't keep the SIGTRAP status
634 and don't forward the SIGTRAP signal to the LWP. We
635 will handle the current event, eventually we will
636 resume all LWPs, and this one will get its breakpoint
639 If we do not do this, then we run the risk that the
640 user will delete or disable the breakpoint, but the
641 thread will have already tripped on it. */
644 fprintf_unfiltered (gdb_stdlog
,
645 "Tripped breakpoint at %lx in LWP %d"
646 " while waiting for SIGSTOP.\n",
647 (long) read_pc_pid (lp
->ptid
), pid
);
649 /* Set the PC to before the trap. */
650 if (DECR_PC_AFTER_BREAK
)
651 write_pc_pid (read_pc_pid (pid_to_ptid (pid
))
652 - DECR_PC_AFTER_BREAK
,
655 /* Now resume this LWP and get the SIGSTOP event. */
656 ptrace (PTRACE_CONT
, GET_LWP (lp
->ptid
), 0, 0);
657 goto get_another_event
;
659 else if (WSTOPSIG (status
) == SIGINT
&&
660 signal_pass_state (SIGINT
) == 0)
662 /* Since SIGINT gets forwarded to the entire process group
663 (in the case where ^C/BREAK is typed at the tty/console),
664 just ignore all SIGINT events from all lwp's except for
665 the one that was caught by lin_lwp_wait. */
667 /* Now resume this LWP and get the SIGSTP event. */
668 ptrace (PTRACE_CONT
, GET_LWP (lp
->ptid
), 0, 0);
669 goto get_another_event
;
674 fprintf_unfiltered (gdb_stdlog
,
675 "Received %s in LWP %d while waiting for SIGSTOP.\n",
676 strsignal (WSTOPSIG (status
)), pid
);
678 /* The thread was stopped with a signal other than
679 SIGSTOP, and didn't accidentally trip a breakpoint.
680 Record the wait status. */
686 /* We caught the SIGSTOP that we intended to catch, so
687 there's no SIGSTOP pending. */
695 /* Return non-zero if LP has a wait status pending. */
698 status_callback (struct lwp_info
*lp
, void *data
)
700 /* Only report a pending wait status if we pretend that this has
701 indeed been resumed. */
702 return (lp
->status
!= 0 && lp
->resumed
);
705 /* Return non-zero if LP isn't stopped. */
708 running_callback (struct lwp_info
*lp
, void *data
)
710 return (lp
->stopped
== 0);
713 /* Return non-zero if LP has been resumed. */
716 resumed_callback (struct lwp_info
*lp
, void *data
)
722 lin_lwp_wait (ptid_t ptid
, struct target_waitstatus
*ourstatus
)
724 struct lwp_info
*lp
= NULL
;
727 pid_t pid
= PIDGET (ptid
);
729 /* Make sure SIGCHLD is blocked. */
730 if (! sigismember (&blocked_mask
, SIGCHLD
))
732 sigaddset (&blocked_mask
, SIGCHLD
);
733 sigprocmask (SIG_BLOCK
, &blocked_mask
, NULL
);
738 /* Make sure there is at least one thread that has been resumed. */
739 gdb_assert (iterate_over_lwps (resumed_callback
, NULL
));
741 /* First check if there is a LWP with a wait status pending. */
744 /* Any LWP will do. */
745 lp
= iterate_over_lwps (status_callback
, NULL
);
749 fprintf_unfiltered (gdb_stdlog
,
750 "Using pending wait status for LWP %ld.\n",
757 /* But if we don't fine one, we'll have to wait, and check both
758 cloned and uncloned processes. We start with the cloned
760 options
= __WCLONE
| WNOHANG
;
762 else if (is_lwp (ptid
))
765 fprintf_unfiltered (gdb_stdlog
,
766 "Waiting for specific LWP %ld.\n",
769 /* We have a specific LWP to check. */
770 lp
= find_lwp_pid (ptid
);
777 fprintf_unfiltered (gdb_stdlog
,
778 "Using pending wait status for LWP %ld.\n",
781 /* If we have to wait, take into account whether PID is a cloned
782 process or not. And we have to convert it to something that
783 the layer beneath us can understand. */
784 options
= is_cloned (lp
->ptid
) ? __WCLONE
: 0;
785 pid
= GET_LWP (ptid
);
788 if (status
&& lp
->signalled
)
790 /* A pending SIGSTOP may interfere with the normal stream of
791 events. In a typical case where interference is a problem,
792 we have a SIGSTOP signal pending for LWP A while
793 single-stepping it, encounter an event in LWP B, and take the
794 pending SIGSTOP while trying to stop LWP A. After processing
795 the event in LWP B, LWP A is continued, and we'll never see
796 the SIGTRAP associated with the last time we were
797 single-stepping LWP A. */
799 /* Resume the thread. It should halt immediately returning the
801 child_resume (pid_to_ptid (GET_LWP (lp
->ptid
)), lp
->step
,
804 gdb_assert (lp
->resumed
);
806 /* This should catch the pending SIGSTOP. */
807 stop_wait_callback (lp
, NULL
);
810 set_sigint_trap (); /* Causes SIGINT to be passed on to the
818 lwpid
= waitpid (pid
, &status
, options
);
821 gdb_assert (pid
== -1 || lwpid
== pid
);
823 lp
= find_lwp_pid (pid_to_ptid (lwpid
));
826 lp
= add_lwp (BUILD_LWP (lwpid
, GET_PID (inferior_ptid
)));
829 gdb_assert (WIFSTOPPED (status
)
830 && WSTOPSIG (status
) == SIGSTOP
);
833 if (! in_thread_list (inferior_ptid
))
835 inferior_ptid
= BUILD_LWP (GET_PID (inferior_ptid
),
836 GET_PID (inferior_ptid
));
837 add_thread (inferior_ptid
);
840 add_thread (lp
->ptid
);
841 printf_unfiltered ("[New %s]\n",
842 target_pid_to_str (lp
->ptid
));
846 /* Make sure we don't report a TARGET_WAITKIND_EXITED or
847 TARGET_WAITKIND_SIGNALLED event if there are still LWP's
848 left in the process. */
849 if ((WIFEXITED (status
) || WIFSIGNALED (status
)) && num_lwps
> 1)
851 if (in_thread_list (lp
->ptid
))
853 /* Core GDB cannot deal with us deleting the current
855 if (! ptid_equal (lp
->ptid
, inferior_ptid
))
856 delete_thread (lp
->ptid
);
857 printf_unfiltered ("[%s exited]\n",
858 target_pid_to_str (lp
->ptid
));
861 fprintf_unfiltered (gdb_stdlog
,
863 target_pid_to_str (lp
->ptid
));
865 delete_lwp (lp
->ptid
);
867 /* Make sure there is at least one thread running. */
868 gdb_assert (iterate_over_lwps (running_callback
, NULL
));
870 /* Discard the event. */
875 /* Make sure we don't report a SIGSTOP that we sent
876 ourselves in an attempt to stop an LWP. */
877 if (lp
->signalled
&& WIFSTOPPED (status
)
878 && WSTOPSIG (status
) == SIGSTOP
)
881 fprintf_unfiltered (gdb_stdlog
,
882 "Delayed SIGSTOP caught for %s.\n",
883 target_pid_to_str (lp
->ptid
));
885 /* This is a delayed SIGSTOP. */
888 child_resume (pid_to_ptid (GET_LWP (lp
->ptid
)), lp
->step
,
891 gdb_assert (lp
->resumed
);
893 /* Discard the event. */
903 /* Alternate between checking cloned and uncloned processes. */
906 /* And suspend every time we have checked both. */
907 if (options
& __WCLONE
)
908 sigsuspend (&suspend_mask
);
911 /* We shouldn't end up here unless we want to try again. */
912 gdb_assert (status
== 0);
916 clear_sigint_trap ();
920 /* Don't report signals that GDB isn't interested in, such as
921 signals that are neither printed nor stopped upon. Stopping all
922 threads can be a bit time-consuming so if we want decent
923 performance with heavily multi-threaded programs, especially when
924 they're using a high frequency timer, we'd better avoid it if we
927 if (WIFSTOPPED (status
))
929 int signo
= target_signal_from_host (WSTOPSIG (status
));
931 if (signal_stop_state (signo
) == 0
932 && signal_print_state (signo
) == 0
933 && signal_pass_state (signo
) == 1)
935 /* FIMXE: kettenis/2001-06-06: Should we resume all threads
936 here? It is not clear we should. GDB may not expect
937 other threads to run. On the other hand, not resuming
938 newly attached threads may cause an unwanted delay in
939 getting them running. */
940 child_resume (pid_to_ptid (GET_LWP (lp
->ptid
)), lp
->step
, signo
);
947 /* This LWP is stopped now. */
950 /* Now stop all other LWP's ... */
951 iterate_over_lwps (stop_callback
, NULL
);
953 /* ... and wait until all of them have reported back that they're no
955 iterate_over_lwps (stop_wait_callback
, NULL
);
957 /* If we're not running in "threaded" mode, we'll report the bare
960 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
)
961 trap_ptid
= (threaded
? lp
->ptid
: pid_to_ptid (GET_LWP (lp
->ptid
)));
963 trap_ptid
= null_ptid
;
965 store_waitstatus (ourstatus
, status
);
966 return (threaded
? lp
->ptid
: pid_to_ptid (GET_LWP (lp
->ptid
)));
970 kill_callback (struct lwp_info
*lp
, void *data
)
972 ptrace (PTRACE_KILL
, GET_LWP (lp
->ptid
), 0, 0);
977 kill_wait_callback (struct lwp_info
*lp
, void *data
)
981 /* We must make sure that there are no pending events (delayed
982 SIGSTOPs, pending SIGTRAPs, etc.) to make sure the current
983 program doesn't interfere with any following debugging session. */
985 /* For cloned processes we must check both with __WCLONE and
986 without, since the exit status of a cloned process isn't reported
988 if (is_cloned (lp
->ptid
))
992 pid
= waitpid (GET_LWP (lp
->ptid
), NULL
, __WCLONE
);
994 while (pid
== GET_LWP (lp
->ptid
));
996 gdb_assert (pid
== -1 && errno
== ECHILD
);
1001 pid
= waitpid (GET_LWP (lp
->ptid
), NULL
, 0);
1003 while (pid
== GET_LWP (lp
->ptid
));
1005 gdb_assert (pid
== -1 && errno
== ECHILD
);
1012 /* Kill all LWP's ... */
1013 iterate_over_lwps (kill_callback
, NULL
);
1015 /* ... and wait until we've flushed all events. */
1016 iterate_over_lwps (kill_wait_callback
, NULL
);
1018 target_mourn_inferior ();
1022 lin_lwp_create_inferior (char *exec_file
, char *allargs
, char **env
)
1024 child_ops
.to_create_inferior (exec_file
, allargs
, env
);
1028 lin_lwp_mourn_inferior (void)
1030 trap_ptid
= null_ptid
;
1032 /* Destroy LWP info; it's no longer valid. */
1035 /* Restore the original signal mask. */
1036 sigprocmask (SIG_SETMASK
, &normal_mask
, NULL
);
1037 sigemptyset (&blocked_mask
);
1039 child_ops
.to_mourn_inferior ();
1043 lin_lwp_fetch_registers (int regno
)
1045 struct cleanup
*old_chain
= save_inferior_ptid ();
1047 if (is_lwp (inferior_ptid
))
1048 inferior_ptid
= pid_to_ptid (GET_LWP (inferior_ptid
));
1050 fetch_inferior_registers (regno
);
1052 do_cleanups (old_chain
);
1056 lin_lwp_store_registers (int regno
)
1058 struct cleanup
*old_chain
= save_inferior_ptid ();
1060 if (is_lwp (inferior_ptid
))
1061 inferior_ptid
= pid_to_ptid (GET_LWP (inferior_ptid
));
1063 store_inferior_registers (regno
);
1065 do_cleanups (old_chain
);
1069 lin_lwp_xfer_memory (CORE_ADDR memaddr
, char *myaddr
, int len
, int write
,
1070 struct mem_attrib
*attrib
,
1071 struct target_ops
*target
)
1073 struct cleanup
*old_chain
= save_inferior_ptid ();
1076 if (is_lwp (inferior_ptid
))
1077 inferior_ptid
= pid_to_ptid (GET_LWP (inferior_ptid
));
1079 xfer
= child_xfer_memory (memaddr
, myaddr
, len
, write
, attrib
, target
);
1081 do_cleanups (old_chain
);
1086 lin_lwp_thread_alive (ptid_t ptid
)
1088 gdb_assert (is_lwp (ptid
));
1091 ptrace (PTRACE_PEEKUSER
, GET_LWP (ptid
), 0, 0);
1099 lin_lwp_pid_to_str (ptid_t ptid
)
1101 static char buf
[64];
1105 snprintf (buf
, sizeof (buf
), "LWP %ld", GET_LWP (ptid
));
1109 return normal_pid_to_str (ptid
);
1113 init_lin_lwp_ops (void)
1116 lin_lwp_ops
.to_open
= lin_lwp_open
;
1118 lin_lwp_ops
.to_shortname
= "lwp-layer";
1119 lin_lwp_ops
.to_longname
= "lwp-layer";
1120 lin_lwp_ops
.to_doc
= "Low level threads support (LWP layer)";
1121 lin_lwp_ops
.to_attach
= lin_lwp_attach
;
1122 lin_lwp_ops
.to_detach
= lin_lwp_detach
;
1123 lin_lwp_ops
.to_resume
= lin_lwp_resume
;
1124 lin_lwp_ops
.to_wait
= lin_lwp_wait
;
1125 lin_lwp_ops
.to_fetch_registers
= lin_lwp_fetch_registers
;
1126 lin_lwp_ops
.to_store_registers
= lin_lwp_store_registers
;
1127 lin_lwp_ops
.to_xfer_memory
= lin_lwp_xfer_memory
;
1128 lin_lwp_ops
.to_kill
= lin_lwp_kill
;
1129 lin_lwp_ops
.to_create_inferior
= lin_lwp_create_inferior
;
1130 lin_lwp_ops
.to_mourn_inferior
= lin_lwp_mourn_inferior
;
1131 lin_lwp_ops
.to_thread_alive
= lin_lwp_thread_alive
;
1132 lin_lwp_ops
.to_pid_to_str
= lin_lwp_pid_to_str
;
1133 lin_lwp_ops
.to_stratum
= thread_stratum
;
1134 lin_lwp_ops
.to_has_thread_control
= tc_schedlock
;
1135 lin_lwp_ops
.to_magic
= OPS_MAGIC
;
1139 sigchld_handler (int signo
)
1141 /* Do nothing. The only reason for this handler is that it allows
1142 us to use sigsuspend in lin_lwp_wait above to wait for the
1143 arrival of a SIGCHLD. */
1147 _initialize_lin_lwp (void)
1149 struct sigaction action
;
1151 extern void thread_db_init (struct target_ops
*);
1153 init_lin_lwp_ops ();
1154 add_target (&lin_lwp_ops
);
1155 thread_db_init (&lin_lwp_ops
);
1157 /* Save the original signal mask. */
1158 sigprocmask (SIG_SETMASK
, NULL
, &normal_mask
);
1160 action
.sa_handler
= sigchld_handler
;
1161 sigemptyset (&action
.sa_mask
);
1162 action
.sa_flags
= 0;
1163 sigaction (SIGCHLD
, &action
, NULL
);
1165 /* Make sure we don't block SIGCHLD during a sigsuspend. */
1166 sigprocmask (SIG_SETMASK
, NULL
, &suspend_mask
);
1167 sigdelset (&suspend_mask
, SIGCHLD
);
1169 sigemptyset (&blocked_mask
);
1171 add_show_from_set (add_set_cmd ("lin-lwp", no_class
, var_zinteger
,
1172 (char *) &debug_lin_lwp
,
1173 "Set debugging of linux lwp module.\n\
1174 Enables printf debugging output.\n",
1180 /* FIXME: kettenis/2000-08-26: The stuff on this page is specific to
1181 the LinuxThreads library and therefore doesn't really belong here. */
1183 /* Read variable NAME in the target and return its value if found.
1184 Otherwise return zero. It is assumed that the type of the variable
1188 get_signo (const char *name
)
1190 struct minimal_symbol
*ms
;
1193 ms
= lookup_minimal_symbol (name
, NULL
, NULL
);
1197 if (target_read_memory (SYMBOL_VALUE_ADDRESS (ms
), (char *) &signo
,
1198 sizeof (signo
)) != 0)
1204 /* Return the set of signals used by the threads library in *SET. */
1207 lin_thread_get_thread_signals (sigset_t
*set
)
1209 struct sigaction action
;
1210 int restart
, cancel
;
1214 restart
= get_signo ("__pthread_sig_restart");
1218 cancel
= get_signo ("__pthread_sig_cancel");
1222 sigaddset (set
, restart
);
1223 sigaddset (set
, cancel
);
1225 /* The LinuxThreads library makes terminating threads send a special
1226 "cancel" signal instead of SIGCHLD. Make sure we catch those (to
1227 prevent them from terminating GDB itself, which is likely to be
1228 their default action) and treat them the same way as SIGCHLD. */
1230 action
.sa_handler
= sigchld_handler
;
1231 sigemptyset (&action
.sa_mask
);
1232 action
.sa_flags
= 0;
1233 sigaction (cancel
, &action
, NULL
);
1235 /* We block the "cancel" signal throughout this code ... */
1236 sigaddset (&blocked_mask
, cancel
);
1237 sigprocmask (SIG_BLOCK
, &blocked_mask
, NULL
);
1239 /* ... except during a sigsuspend. */
1240 sigdelset (&suspend_mask
, cancel
);
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