1 /* GNU/Linux native-dependent code common to multiple platforms.
3 Copyright (C) 2001-2020 Free Software Foundation, Inc.
5 This file is part of GDB.
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>. */
24 #include "nat/linux-nat.h"
25 #include "nat/linux-waitpid.h"
26 #include "gdbsupport/gdb_wait.h"
28 #include <sys/syscall.h>
29 #include "nat/gdb_ptrace.h"
30 #include "linux-nat.h"
31 #include "nat/linux-ptrace.h"
32 #include "nat/linux-procfs.h"
33 #include "nat/linux-personality.h"
34 #include "linux-fork.h"
35 #include "gdbthread.h"
39 #include "inf-child.h"
40 #include "inf-ptrace.h"
42 #include <sys/procfs.h> /* for elf_gregset etc. */
43 #include "elf-bfd.h" /* for elfcore_write_* */
44 #include "gregset.h" /* for gregset */
45 #include "gdbcore.h" /* for get_exec_file */
46 #include <ctype.h> /* for isdigit */
47 #include <sys/stat.h> /* for struct stat */
48 #include <fcntl.h> /* for O_RDONLY */
50 #include "gdbsupport/event-loop.h"
51 #include "event-top.h"
53 #include <sys/types.h>
55 #include "xml-support.h"
58 #include "nat/linux-osdata.h"
59 #include "linux-tdep.h"
61 #include "gdbsupport/agent.h"
62 #include "tracepoint.h"
63 #include "gdbsupport/buffer.h"
64 #include "target-descriptions.h"
65 #include "gdbsupport/filestuff.h"
67 #include "nat/linux-namespaces.h"
68 #include "gdbsupport/fileio.h"
69 #include "gdbsupport/scope-exit.h"
70 #include "gdbsupport/gdb-sigmask.h"
72 /* This comment documents high-level logic of this file.
74 Waiting for events in sync mode
75 ===============================
77 When waiting for an event in a specific thread, we just use waitpid,
78 passing the specific pid, and not passing WNOHANG.
80 When waiting for an event in all threads, waitpid is not quite good:
82 - If the thread group leader exits while other threads in the thread
83 group still exist, waitpid(TGID, ...) hangs. That waitpid won't
84 return an exit status until the other threads in the group are
87 - When a non-leader thread execs, that thread just vanishes without
88 reporting an exit (so we'd hang if we waited for it explicitly in
89 that case). The exec event is instead reported to the TGID pid.
91 The solution is to always use -1 and WNOHANG, together with
94 First, we use non-blocking waitpid to check for events. If nothing is
95 found, we use sigsuspend to wait for SIGCHLD. When SIGCHLD arrives,
96 it means something happened to a child process. As soon as we know
97 there's an event, we get back to calling nonblocking waitpid.
99 Note that SIGCHLD should be blocked between waitpid and sigsuspend
100 calls, so that we don't miss a signal. If SIGCHLD arrives in between,
101 when it's blocked, the signal becomes pending and sigsuspend
102 immediately notices it and returns.
104 Waiting for events in async mode (TARGET_WNOHANG)
105 =================================================
107 In async mode, GDB should always be ready to handle both user input
108 and target events, so neither blocking waitpid nor sigsuspend are
109 viable options. Instead, we should asynchronously notify the GDB main
110 event loop whenever there's an unprocessed event from the target. We
111 detect asynchronous target events by handling SIGCHLD signals. To
112 notify the event loop about target events, the self-pipe trick is used
113 --- a pipe is registered as waitable event source in the event loop,
114 the event loop select/poll's on the read end of this pipe (as well on
115 other event sources, e.g., stdin), and the SIGCHLD handler writes a
116 byte to this pipe. This is more portable than relying on
117 pselect/ppoll, since on kernels that lack those syscalls, libc
118 emulates them with select/poll+sigprocmask, and that is racy
119 (a.k.a. plain broken).
121 Obviously, if we fail to notify the event loop if there's a target
122 event, it's bad. OTOH, if we notify the event loop when there's no
123 event from the target, linux_nat_wait will detect that there's no real
124 event to report, and return event of type TARGET_WAITKIND_IGNORE.
125 This is mostly harmless, but it will waste time and is better avoided.
127 The main design point is that every time GDB is outside linux-nat.c,
128 we have a SIGCHLD handler installed that is called when something
129 happens to the target and notifies the GDB event loop. Whenever GDB
130 core decides to handle the event, and calls into linux-nat.c, we
131 process things as in sync mode, except that the we never block in
134 While processing an event, we may end up momentarily blocked in
135 waitpid calls. Those waitpid calls, while blocking, are guarantied to
136 return quickly. E.g., in all-stop mode, before reporting to the core
137 that an LWP hit a breakpoint, all LWPs are stopped by sending them
138 SIGSTOP, and synchronously waiting for the SIGSTOP to be reported.
139 Note that this is different from blocking indefinitely waiting for the
140 next event --- here, we're already handling an event.
145 We stop threads by sending a SIGSTOP. The use of SIGSTOP instead of another
146 signal is not entirely significant; we just need for a signal to be delivered,
147 so that we can intercept it. SIGSTOP's advantage is that it can not be
148 blocked. A disadvantage is that it is not a real-time signal, so it can only
149 be queued once; we do not keep track of other sources of SIGSTOP.
151 Two other signals that can't be blocked are SIGCONT and SIGKILL. But we can't
152 use them, because they have special behavior when the signal is generated -
153 not when it is delivered. SIGCONT resumes the entire thread group and SIGKILL
154 kills the entire thread group.
156 A delivered SIGSTOP would stop the entire thread group, not just the thread we
157 tkill'd. But we never let the SIGSTOP be delivered; we always intercept and
158 cancel it (by PTRACE_CONT without passing SIGSTOP).
160 We could use a real-time signal instead. This would solve those problems; we
161 could use PTRACE_GETSIGINFO to locate the specific stop signals sent by GDB.
162 But we would still have to have some support for SIGSTOP, since PTRACE_ATTACH
163 generates it, and there are races with trying to find a signal that is not
169 The case of a thread group (process) with 3 or more threads, and a
170 thread other than the leader execs is worth detailing:
172 On an exec, the Linux kernel destroys all threads except the execing
173 one in the thread group, and resets the execing thread's tid to the
174 tgid. No exit notification is sent for the execing thread -- from the
175 ptracer's perspective, it appears as though the execing thread just
176 vanishes. Until we reap all other threads except the leader and the
177 execing thread, the leader will be zombie, and the execing thread will
178 be in `D (disc sleep)' state. As soon as all other threads are
179 reaped, the execing thread changes its tid to the tgid, and the
180 previous (zombie) leader vanishes, giving place to the "new"
184 #define O_LARGEFILE 0
187 struct linux_nat_target
*linux_target
;
189 /* Does the current host support PTRACE_GETREGSET? */
190 enum tribool have_ptrace_getregset
= TRIBOOL_UNKNOWN
;
192 static unsigned int debug_linux_nat
;
194 show_debug_linux_nat (struct ui_file
*file
, int from_tty
,
195 struct cmd_list_element
*c
, const char *value
)
197 fprintf_filtered (file
, _("Debugging of GNU/Linux lwp module is %s.\n"),
201 struct simple_pid_list
205 struct simple_pid_list
*next
;
207 struct simple_pid_list
*stopped_pids
;
209 /* Whether target_thread_events is in effect. */
210 static int report_thread_events
;
212 /* Async mode support. */
214 /* The read/write ends of the pipe registered as waitable file in the
216 static int linux_nat_event_pipe
[2] = { -1, -1 };
218 /* True if we're currently in async mode. */
219 #define linux_is_async_p() (linux_nat_event_pipe[0] != -1)
221 /* Flush the event pipe. */
224 async_file_flush (void)
231 ret
= read (linux_nat_event_pipe
[0], &buf
, 1);
233 while (ret
>= 0 || (ret
== -1 && errno
== EINTR
));
236 /* Put something (anything, doesn't matter what, or how much) in event
237 pipe, so that the select/poll in the event-loop realizes we have
238 something to process. */
241 async_file_mark (void)
245 /* It doesn't really matter what the pipe contains, as long we end
246 up with something in it. Might as well flush the previous
252 ret
= write (linux_nat_event_pipe
[1], "+", 1);
254 while (ret
== -1 && errno
== EINTR
);
256 /* Ignore EAGAIN. If the pipe is full, the event loop will already
257 be awakened anyway. */
260 static int kill_lwp (int lwpid
, int signo
);
262 static int stop_callback (struct lwp_info
*lp
);
264 static void block_child_signals (sigset_t
*prev_mask
);
265 static void restore_child_signals_mask (sigset_t
*prev_mask
);
268 static struct lwp_info
*add_lwp (ptid_t ptid
);
269 static void purge_lwp_list (int pid
);
270 static void delete_lwp (ptid_t ptid
);
271 static struct lwp_info
*find_lwp_pid (ptid_t ptid
);
273 static int lwp_status_pending_p (struct lwp_info
*lp
);
275 static void save_stop_reason (struct lwp_info
*lp
);
280 /* See nat/linux-nat.h. */
283 ptid_of_lwp (struct lwp_info
*lwp
)
288 /* See nat/linux-nat.h. */
291 lwp_set_arch_private_info (struct lwp_info
*lwp
,
292 struct arch_lwp_info
*info
)
294 lwp
->arch_private
= info
;
297 /* See nat/linux-nat.h. */
299 struct arch_lwp_info
*
300 lwp_arch_private_info (struct lwp_info
*lwp
)
302 return lwp
->arch_private
;
305 /* See nat/linux-nat.h. */
308 lwp_is_stopped (struct lwp_info
*lwp
)
313 /* See nat/linux-nat.h. */
315 enum target_stop_reason
316 lwp_stop_reason (struct lwp_info
*lwp
)
318 return lwp
->stop_reason
;
321 /* See nat/linux-nat.h. */
324 lwp_is_stepping (struct lwp_info
*lwp
)
330 /* Trivial list manipulation functions to keep track of a list of
331 new stopped processes. */
333 add_to_pid_list (struct simple_pid_list
**listp
, int pid
, int status
)
335 struct simple_pid_list
*new_pid
= XNEW (struct simple_pid_list
);
338 new_pid
->status
= status
;
339 new_pid
->next
= *listp
;
344 pull_pid_from_list (struct simple_pid_list
**listp
, int pid
, int *statusp
)
346 struct simple_pid_list
**p
;
348 for (p
= listp
; *p
!= NULL
; p
= &(*p
)->next
)
349 if ((*p
)->pid
== pid
)
351 struct simple_pid_list
*next
= (*p
)->next
;
353 *statusp
= (*p
)->status
;
361 /* Return the ptrace options that we want to try to enable. */
364 linux_nat_ptrace_options (int attached
)
369 options
|= PTRACE_O_EXITKILL
;
371 options
|= (PTRACE_O_TRACESYSGOOD
372 | PTRACE_O_TRACEVFORKDONE
373 | PTRACE_O_TRACEVFORK
375 | PTRACE_O_TRACEEXEC
);
380 /* Initialize ptrace and procfs warnings and check for supported
381 ptrace features given PID.
383 ATTACHED should be nonzero iff we attached to the inferior. */
386 linux_init_ptrace_procfs (pid_t pid
, int attached
)
388 int options
= linux_nat_ptrace_options (attached
);
390 linux_enable_event_reporting (pid
, options
);
391 linux_ptrace_init_warnings ();
392 linux_proc_init_warnings ();
395 linux_nat_target::~linux_nat_target ()
399 linux_nat_target::post_attach (int pid
)
401 linux_init_ptrace_procfs (pid
, 1);
405 linux_nat_target::post_startup_inferior (ptid_t ptid
)
407 linux_init_ptrace_procfs (ptid
.pid (), 0);
410 /* Return the number of known LWPs in the tgid given by PID. */
418 for (lp
= lwp_list
; lp
; lp
= lp
->next
)
419 if (lp
->ptid
.pid () == pid
)
425 /* Deleter for lwp_info unique_ptr specialisation. */
429 void operator() (struct lwp_info
*lwp
) const
431 delete_lwp (lwp
->ptid
);
435 /* A unique_ptr specialisation for lwp_info. */
437 typedef std::unique_ptr
<struct lwp_info
, lwp_deleter
> lwp_info_up
;
439 /* Target hook for follow_fork. On entry inferior_ptid must be the
440 ptid of the followed inferior. At return, inferior_ptid will be
444 linux_nat_target::follow_fork (bool follow_child
, bool detach_fork
)
448 struct lwp_info
*child_lp
= NULL
;
450 ptid_t parent_ptid
, child_ptid
;
451 int parent_pid
, child_pid
;
453 has_vforked
= (inferior_thread ()->pending_follow
.kind
454 == TARGET_WAITKIND_VFORKED
);
455 parent_ptid
= inferior_ptid
;
456 child_ptid
= inferior_thread ()->pending_follow
.value
.related_pid
;
457 parent_pid
= parent_ptid
.lwp ();
458 child_pid
= child_ptid
.lwp ();
460 /* We're already attached to the parent, by default. */
461 child_lp
= add_lwp (child_ptid
);
462 child_lp
->stopped
= 1;
463 child_lp
->last_resume_kind
= resume_stop
;
465 /* Detach new forked process? */
468 int child_stop_signal
= 0;
469 bool detach_child
= true;
471 /* Move CHILD_LP into a unique_ptr and clear the source pointer
472 to prevent us doing anything stupid with it. */
473 lwp_info_up
child_lp_ptr (child_lp
);
476 linux_target
->low_prepare_to_resume (child_lp_ptr
.get ());
478 /* When debugging an inferior in an architecture that supports
479 hardware single stepping on a kernel without commit
480 6580807da14c423f0d0a708108e6df6ebc8bc83d, the vfork child
481 process starts with the TIF_SINGLESTEP/X86_EFLAGS_TF bits
482 set if the parent process had them set.
483 To work around this, single step the child process
484 once before detaching to clear the flags. */
486 /* Note that we consult the parent's architecture instead of
487 the child's because there's no inferior for the child at
489 if (!gdbarch_software_single_step_p (target_thread_architecture
494 linux_disable_event_reporting (child_pid
);
495 if (ptrace (PTRACE_SINGLESTEP
, child_pid
, 0, 0) < 0)
496 perror_with_name (_("Couldn't do single step"));
497 if (my_waitpid (child_pid
, &status
, 0) < 0)
498 perror_with_name (_("Couldn't wait vfork process"));
501 detach_child
= WIFSTOPPED (status
);
502 child_stop_signal
= WSTOPSIG (status
);
508 int signo
= child_stop_signal
;
511 && !signal_pass_state (gdb_signal_from_host (signo
)))
513 ptrace (PTRACE_DETACH
, child_pid
, 0, signo
);
518 /* Switching inferior_ptid is not enough, because then
519 inferior_thread () would crash by not finding the thread
520 in the current inferior. */
521 scoped_restore_current_thread restore_current_thread
;
522 thread_info
*child
= find_thread_ptid (this, child_ptid
);
523 switch_to_thread (child
);
525 /* Let the thread_db layer learn about this new process. */
526 check_for_thread_db ();
531 struct lwp_info
*parent_lp
;
533 parent_lp
= find_lwp_pid (parent_ptid
);
534 gdb_assert (linux_supports_tracefork () >= 0);
536 if (linux_supports_tracevforkdone ())
539 fprintf_unfiltered (gdb_stdlog
,
540 "LCFF: waiting for VFORK_DONE on %d\n",
542 parent_lp
->stopped
= 1;
544 /* We'll handle the VFORK_DONE event like any other
545 event, in target_wait. */
549 /* We can't insert breakpoints until the child has
550 finished with the shared memory region. We need to
551 wait until that happens. Ideal would be to just
553 - ptrace (PTRACE_SYSCALL, parent_pid, 0, 0);
554 - waitpid (parent_pid, &status, __WALL);
555 However, most architectures can't handle a syscall
556 being traced on the way out if it wasn't traced on
559 We might also think to loop, continuing the child
560 until it exits or gets a SIGTRAP. One problem is
561 that the child might call ptrace with PTRACE_TRACEME.
563 There's no simple and reliable way to figure out when
564 the vforked child will be done with its copy of the
565 shared memory. We could step it out of the syscall,
566 two instructions, let it go, and then single-step the
567 parent once. When we have hardware single-step, this
568 would work; with software single-step it could still
569 be made to work but we'd have to be able to insert
570 single-step breakpoints in the child, and we'd have
571 to insert -just- the single-step breakpoint in the
572 parent. Very awkward.
574 In the end, the best we can do is to make sure it
575 runs for a little while. Hopefully it will be out of
576 range of any breakpoints we reinsert. Usually this
577 is only the single-step breakpoint at vfork's return
581 fprintf_unfiltered (gdb_stdlog
,
582 "LCFF: no VFORK_DONE "
583 "support, sleeping a bit\n");
587 /* Pretend we've seen a PTRACE_EVENT_VFORK_DONE event,
588 and leave it pending. The next linux_nat_resume call
589 will notice a pending event, and bypasses actually
590 resuming the inferior. */
591 parent_lp
->status
= 0;
592 parent_lp
->waitstatus
.kind
= TARGET_WAITKIND_VFORK_DONE
;
593 parent_lp
->stopped
= 1;
595 /* If we're in async mode, need to tell the event loop
596 there's something here to process. */
597 if (target_is_async_p ())
604 struct lwp_info
*child_lp
;
606 child_lp
= add_lwp (inferior_ptid
);
607 child_lp
->stopped
= 1;
608 child_lp
->last_resume_kind
= resume_stop
;
610 /* Let the thread_db layer learn about this new process. */
611 check_for_thread_db ();
619 linux_nat_target::insert_fork_catchpoint (int pid
)
621 return !linux_supports_tracefork ();
625 linux_nat_target::remove_fork_catchpoint (int pid
)
631 linux_nat_target::insert_vfork_catchpoint (int pid
)
633 return !linux_supports_tracefork ();
637 linux_nat_target::remove_vfork_catchpoint (int pid
)
643 linux_nat_target::insert_exec_catchpoint (int pid
)
645 return !linux_supports_tracefork ();
649 linux_nat_target::remove_exec_catchpoint (int pid
)
655 linux_nat_target::set_syscall_catchpoint (int pid
, bool needed
, int any_count
,
656 gdb::array_view
<const int> syscall_counts
)
658 if (!linux_supports_tracesysgood ())
661 /* On GNU/Linux, we ignore the arguments. It means that we only
662 enable the syscall catchpoints, but do not disable them.
664 Also, we do not use the `syscall_counts' information because we do not
665 filter system calls here. We let GDB do the logic for us. */
669 /* List of known LWPs, keyed by LWP PID. This speeds up the common
670 case of mapping a PID returned from the kernel to our corresponding
671 lwp_info data structure. */
672 static htab_t lwp_lwpid_htab
;
674 /* Calculate a hash from a lwp_info's LWP PID. */
677 lwp_info_hash (const void *ap
)
679 const struct lwp_info
*lp
= (struct lwp_info
*) ap
;
680 pid_t pid
= lp
->ptid
.lwp ();
682 return iterative_hash_object (pid
, 0);
685 /* Equality function for the lwp_info hash table. Compares the LWP's
689 lwp_lwpid_htab_eq (const void *a
, const void *b
)
691 const struct lwp_info
*entry
= (const struct lwp_info
*) a
;
692 const struct lwp_info
*element
= (const struct lwp_info
*) b
;
694 return entry
->ptid
.lwp () == element
->ptid
.lwp ();
697 /* Create the lwp_lwpid_htab hash table. */
700 lwp_lwpid_htab_create (void)
702 lwp_lwpid_htab
= htab_create (100, lwp_info_hash
, lwp_lwpid_htab_eq
, NULL
);
705 /* Add LP to the hash table. */
708 lwp_lwpid_htab_add_lwp (struct lwp_info
*lp
)
712 slot
= htab_find_slot (lwp_lwpid_htab
, lp
, INSERT
);
713 gdb_assert (slot
!= NULL
&& *slot
== NULL
);
717 /* Head of doubly-linked list of known LWPs. Sorted by reverse
718 creation order. This order is assumed in some cases. E.g.,
719 reaping status after killing alls lwps of a process: the leader LWP
720 must be reaped last. */
721 struct lwp_info
*lwp_list
;
723 /* Add LP to sorted-by-reverse-creation-order doubly-linked list. */
726 lwp_list_add (struct lwp_info
*lp
)
729 if (lwp_list
!= NULL
)
734 /* Remove LP from sorted-by-reverse-creation-order doubly-linked
738 lwp_list_remove (struct lwp_info
*lp
)
740 /* Remove from sorted-by-creation-order list. */
741 if (lp
->next
!= NULL
)
742 lp
->next
->prev
= lp
->prev
;
743 if (lp
->prev
!= NULL
)
744 lp
->prev
->next
= lp
->next
;
751 /* Signal mask for use with sigsuspend in linux_nat_wait, initialized in
752 _initialize_linux_nat. */
753 static sigset_t suspend_mask
;
755 /* Signals to block to make that sigsuspend work. */
756 static sigset_t blocked_mask
;
758 /* SIGCHLD action. */
759 struct sigaction sigchld_action
;
761 /* Block child signals (SIGCHLD and linux threads signals), and store
762 the previous mask in PREV_MASK. */
765 block_child_signals (sigset_t
*prev_mask
)
767 /* Make sure SIGCHLD is blocked. */
768 if (!sigismember (&blocked_mask
, SIGCHLD
))
769 sigaddset (&blocked_mask
, SIGCHLD
);
771 gdb_sigmask (SIG_BLOCK
, &blocked_mask
, prev_mask
);
774 /* Restore child signals mask, previously returned by
775 block_child_signals. */
778 restore_child_signals_mask (sigset_t
*prev_mask
)
780 gdb_sigmask (SIG_SETMASK
, prev_mask
, NULL
);
783 /* Mask of signals to pass directly to the inferior. */
784 static sigset_t pass_mask
;
786 /* Update signals to pass to the inferior. */
788 linux_nat_target::pass_signals
789 (gdb::array_view
<const unsigned char> pass_signals
)
793 sigemptyset (&pass_mask
);
795 for (signo
= 1; signo
< NSIG
; signo
++)
797 int target_signo
= gdb_signal_from_host (signo
);
798 if (target_signo
< pass_signals
.size () && pass_signals
[target_signo
])
799 sigaddset (&pass_mask
, signo
);
805 /* Prototypes for local functions. */
806 static int stop_wait_callback (struct lwp_info
*lp
);
807 static int resume_stopped_resumed_lwps (struct lwp_info
*lp
, const ptid_t wait_ptid
);
808 static int check_ptrace_stopped_lwp_gone (struct lwp_info
*lp
);
812 /* Destroy and free LP. */
815 lwp_free (struct lwp_info
*lp
)
817 /* Let the arch specific bits release arch_lwp_info. */
818 linux_target
->low_delete_thread (lp
->arch_private
);
823 /* Traversal function for purge_lwp_list. */
826 lwp_lwpid_htab_remove_pid (void **slot
, void *info
)
828 struct lwp_info
*lp
= (struct lwp_info
*) *slot
;
829 int pid
= *(int *) info
;
831 if (lp
->ptid
.pid () == pid
)
833 htab_clear_slot (lwp_lwpid_htab
, slot
);
834 lwp_list_remove (lp
);
841 /* Remove all LWPs belong to PID from the lwp list. */
844 purge_lwp_list (int pid
)
846 htab_traverse_noresize (lwp_lwpid_htab
, lwp_lwpid_htab_remove_pid
, &pid
);
849 /* Add the LWP specified by PTID to the list. PTID is the first LWP
850 in the process. Return a pointer to the structure describing the
853 This differs from add_lwp in that we don't let the arch specific
854 bits know about this new thread. Current clients of this callback
855 take the opportunity to install watchpoints in the new thread, and
856 we shouldn't do that for the first thread. If we're spawning a
857 child ("run"), the thread executes the shell wrapper first, and we
858 shouldn't touch it until it execs the program we want to debug.
859 For "attach", it'd be okay to call the callback, but it's not
860 necessary, because watchpoints can't yet have been inserted into
863 static struct lwp_info
*
864 add_initial_lwp (ptid_t ptid
)
868 gdb_assert (ptid
.lwp_p ());
870 lp
= XNEW (struct lwp_info
);
872 memset (lp
, 0, sizeof (struct lwp_info
));
874 lp
->last_resume_kind
= resume_continue
;
875 lp
->waitstatus
.kind
= TARGET_WAITKIND_IGNORE
;
880 /* Add to sorted-by-reverse-creation-order list. */
883 /* Add to keyed-by-pid htab. */
884 lwp_lwpid_htab_add_lwp (lp
);
889 /* Add the LWP specified by PID to the list. Return a pointer to the
890 structure describing the new LWP. The LWP should already be
893 static struct lwp_info
*
894 add_lwp (ptid_t ptid
)
898 lp
= add_initial_lwp (ptid
);
900 /* Let the arch specific bits know about this new thread. Current
901 clients of this callback take the opportunity to install
902 watchpoints in the new thread. We don't do this for the first
903 thread though. See add_initial_lwp. */
904 linux_target
->low_new_thread (lp
);
909 /* Remove the LWP specified by PID from the list. */
912 delete_lwp (ptid_t ptid
)
916 struct lwp_info dummy
;
919 slot
= htab_find_slot (lwp_lwpid_htab
, &dummy
, NO_INSERT
);
923 lp
= *(struct lwp_info
**) slot
;
924 gdb_assert (lp
!= NULL
);
926 htab_clear_slot (lwp_lwpid_htab
, slot
);
928 /* Remove from sorted-by-creation-order list. */
929 lwp_list_remove (lp
);
935 /* Return a pointer to the structure describing the LWP corresponding
936 to PID. If no corresponding LWP could be found, return NULL. */
938 static struct lwp_info
*
939 find_lwp_pid (ptid_t ptid
)
943 struct lwp_info dummy
;
950 dummy
.ptid
= ptid_t (0, lwp
, 0);
951 lp
= (struct lwp_info
*) htab_find (lwp_lwpid_htab
, &dummy
);
955 /* See nat/linux-nat.h. */
958 iterate_over_lwps (ptid_t filter
,
959 gdb::function_view
<iterate_over_lwps_ftype
> callback
)
961 struct lwp_info
*lp
, *lpnext
;
963 for (lp
= lwp_list
; lp
; lp
= lpnext
)
967 if (lp
->ptid
.matches (filter
))
969 if (callback (lp
) != 0)
977 /* Update our internal state when changing from one checkpoint to
978 another indicated by NEW_PTID. We can only switch single-threaded
979 applications, so we only create one new LWP, and the previous list
983 linux_nat_switch_fork (ptid_t new_ptid
)
987 purge_lwp_list (inferior_ptid
.pid ());
989 lp
= add_lwp (new_ptid
);
992 /* This changes the thread's ptid while preserving the gdb thread
993 num. Also changes the inferior pid, while preserving the
995 thread_change_ptid (linux_target
, inferior_ptid
, new_ptid
);
997 /* We've just told GDB core that the thread changed target id, but,
998 in fact, it really is a different thread, with different register
1000 registers_changed ();
1003 /* Handle the exit of a single thread LP. */
1006 exit_lwp (struct lwp_info
*lp
)
1008 struct thread_info
*th
= find_thread_ptid (linux_target
, lp
->ptid
);
1012 if (print_thread_events
)
1013 printf_unfiltered (_("[%s exited]\n"),
1014 target_pid_to_str (lp
->ptid
).c_str ());
1019 delete_lwp (lp
->ptid
);
1022 /* Wait for the LWP specified by LP, which we have just attached to.
1023 Returns a wait status for that LWP, to cache. */
1026 linux_nat_post_attach_wait (ptid_t ptid
, int *signalled
)
1028 pid_t new_pid
, pid
= ptid
.lwp ();
1031 if (linux_proc_pid_is_stopped (pid
))
1033 if (debug_linux_nat
)
1034 fprintf_unfiltered (gdb_stdlog
,
1035 "LNPAW: Attaching to a stopped process\n");
1037 /* The process is definitely stopped. It is in a job control
1038 stop, unless the kernel predates the TASK_STOPPED /
1039 TASK_TRACED distinction, in which case it might be in a
1040 ptrace stop. Make sure it is in a ptrace stop; from there we
1041 can kill it, signal it, et cetera.
1043 First make sure there is a pending SIGSTOP. Since we are
1044 already attached, the process can not transition from stopped
1045 to running without a PTRACE_CONT; so we know this signal will
1046 go into the queue. The SIGSTOP generated by PTRACE_ATTACH is
1047 probably already in the queue (unless this kernel is old
1048 enough to use TASK_STOPPED for ptrace stops); but since SIGSTOP
1049 is not an RT signal, it can only be queued once. */
1050 kill_lwp (pid
, SIGSTOP
);
1052 /* Finally, resume the stopped process. This will deliver the SIGSTOP
1053 (or a higher priority signal, just like normal PTRACE_ATTACH). */
1054 ptrace (PTRACE_CONT
, pid
, 0, 0);
1057 /* Make sure the initial process is stopped. The user-level threads
1058 layer might want to poke around in the inferior, and that won't
1059 work if things haven't stabilized yet. */
1060 new_pid
= my_waitpid (pid
, &status
, __WALL
);
1061 gdb_assert (pid
== new_pid
);
1063 if (!WIFSTOPPED (status
))
1065 /* The pid we tried to attach has apparently just exited. */
1066 if (debug_linux_nat
)
1067 fprintf_unfiltered (gdb_stdlog
, "LNPAW: Failed to stop %d: %s",
1068 pid
, status_to_str (status
));
1072 if (WSTOPSIG (status
) != SIGSTOP
)
1075 if (debug_linux_nat
)
1076 fprintf_unfiltered (gdb_stdlog
,
1077 "LNPAW: Received %s after attaching\n",
1078 status_to_str (status
));
1085 linux_nat_target::create_inferior (const char *exec_file
,
1086 const std::string
&allargs
,
1087 char **env
, int from_tty
)
1089 maybe_disable_address_space_randomization restore_personality
1090 (disable_randomization
);
1092 /* The fork_child mechanism is synchronous and calls target_wait, so
1093 we have to mask the async mode. */
1095 /* Make sure we report all signals during startup. */
1098 inf_ptrace_target::create_inferior (exec_file
, allargs
, env
, from_tty
);
1101 /* Callback for linux_proc_attach_tgid_threads. Attach to PTID if not
1102 already attached. Returns true if a new LWP is found, false
1106 attach_proc_task_lwp_callback (ptid_t ptid
)
1108 struct lwp_info
*lp
;
1110 /* Ignore LWPs we're already attached to. */
1111 lp
= find_lwp_pid (ptid
);
1114 int lwpid
= ptid
.lwp ();
1116 if (ptrace (PTRACE_ATTACH
, lwpid
, 0, 0) < 0)
1120 /* Be quiet if we simply raced with the thread exiting.
1121 EPERM is returned if the thread's task still exists, and
1122 is marked as exited or zombie, as well as other
1123 conditions, so in that case, confirm the status in
1124 /proc/PID/status. */
1126 || (err
== EPERM
&& linux_proc_pid_is_gone (lwpid
)))
1128 if (debug_linux_nat
)
1130 fprintf_unfiltered (gdb_stdlog
,
1131 "Cannot attach to lwp %d: "
1132 "thread is gone (%d: %s)\n",
1133 lwpid
, err
, safe_strerror (err
));
1139 = linux_ptrace_attach_fail_reason_string (ptid
, err
);
1141 warning (_("Cannot attach to lwp %d: %s"),
1142 lwpid
, reason
.c_str ());
1147 if (debug_linux_nat
)
1148 fprintf_unfiltered (gdb_stdlog
,
1149 "PTRACE_ATTACH %s, 0, 0 (OK)\n",
1150 target_pid_to_str (ptid
).c_str ());
1152 lp
= add_lwp (ptid
);
1154 /* The next time we wait for this LWP we'll see a SIGSTOP as
1155 PTRACE_ATTACH brings it to a halt. */
1158 /* We need to wait for a stop before being able to make the
1159 next ptrace call on this LWP. */
1160 lp
->must_set_ptrace_flags
= 1;
1162 /* So that wait collects the SIGSTOP. */
1165 /* Also add the LWP to gdb's thread list, in case a
1166 matching libthread_db is not found (or the process uses
1168 add_thread (linux_target
, lp
->ptid
);
1169 set_running (linux_target
, lp
->ptid
, true);
1170 set_executing (linux_target
, lp
->ptid
, true);
1179 linux_nat_target::attach (const char *args
, int from_tty
)
1181 struct lwp_info
*lp
;
1185 /* Make sure we report all signals during attach. */
1190 inf_ptrace_target::attach (args
, from_tty
);
1192 catch (const gdb_exception_error
&ex
)
1194 pid_t pid
= parse_pid_to_attach (args
);
1195 std::string reason
= linux_ptrace_attach_fail_reason (pid
);
1197 if (!reason
.empty ())
1198 throw_error (ex
.error
, "warning: %s\n%s", reason
.c_str (),
1201 throw_error (ex
.error
, "%s", ex
.what ());
1204 /* The ptrace base target adds the main thread with (pid,0,0)
1205 format. Decorate it with lwp info. */
1206 ptid
= ptid_t (inferior_ptid
.pid (),
1207 inferior_ptid
.pid (),
1209 thread_change_ptid (linux_target
, inferior_ptid
, ptid
);
1211 /* Add the initial process as the first LWP to the list. */
1212 lp
= add_initial_lwp (ptid
);
1214 status
= linux_nat_post_attach_wait (lp
->ptid
, &lp
->signalled
);
1215 if (!WIFSTOPPED (status
))
1217 if (WIFEXITED (status
))
1219 int exit_code
= WEXITSTATUS (status
);
1221 target_terminal::ours ();
1222 target_mourn_inferior (inferior_ptid
);
1224 error (_("Unable to attach: program exited normally."));
1226 error (_("Unable to attach: program exited with code %d."),
1229 else if (WIFSIGNALED (status
))
1231 enum gdb_signal signo
;
1233 target_terminal::ours ();
1234 target_mourn_inferior (inferior_ptid
);
1236 signo
= gdb_signal_from_host (WTERMSIG (status
));
1237 error (_("Unable to attach: program terminated with signal "
1239 gdb_signal_to_name (signo
),
1240 gdb_signal_to_string (signo
));
1243 internal_error (__FILE__
, __LINE__
,
1244 _("unexpected status %d for PID %ld"),
1245 status
, (long) ptid
.lwp ());
1250 /* Save the wait status to report later. */
1252 if (debug_linux_nat
)
1253 fprintf_unfiltered (gdb_stdlog
,
1254 "LNA: waitpid %ld, saving status %s\n",
1255 (long) lp
->ptid
.pid (), status_to_str (status
));
1257 lp
->status
= status
;
1259 /* We must attach to every LWP. If /proc is mounted, use that to
1260 find them now. The inferior may be using raw clone instead of
1261 using pthreads. But even if it is using pthreads, thread_db
1262 walks structures in the inferior's address space to find the list
1263 of threads/LWPs, and those structures may well be corrupted.
1264 Note that once thread_db is loaded, we'll still use it to list
1265 threads and associate pthread info with each LWP. */
1266 linux_proc_attach_tgid_threads (lp
->ptid
.pid (),
1267 attach_proc_task_lwp_callback
);
1269 if (target_can_async_p ())
1273 /* Get pending signal of THREAD as a host signal number, for detaching
1274 purposes. This is the signal the thread last stopped for, which we
1275 need to deliver to the thread when detaching, otherwise, it'd be
1279 get_detach_signal (struct lwp_info
*lp
)
1281 enum gdb_signal signo
= GDB_SIGNAL_0
;
1283 /* If we paused threads momentarily, we may have stored pending
1284 events in lp->status or lp->waitstatus (see stop_wait_callback),
1285 and GDB core hasn't seen any signal for those threads.
1286 Otherwise, the last signal reported to the core is found in the
1287 thread object's stop_signal.
1289 There's a corner case that isn't handled here at present. Only
1290 if the thread stopped with a TARGET_WAITKIND_STOPPED does
1291 stop_signal make sense as a real signal to pass to the inferior.
1292 Some catchpoint related events, like
1293 TARGET_WAITKIND_(V)FORK|EXEC|SYSCALL, have their stop_signal set
1294 to GDB_SIGNAL_SIGTRAP when the catchpoint triggers. But,
1295 those traps are debug API (ptrace in our case) related and
1296 induced; the inferior wouldn't see them if it wasn't being
1297 traced. Hence, we should never pass them to the inferior, even
1298 when set to pass state. Since this corner case isn't handled by
1299 infrun.c when proceeding with a signal, for consistency, neither
1300 do we handle it here (or elsewhere in the file we check for
1301 signal pass state). Normally SIGTRAP isn't set to pass state, so
1302 this is really a corner case. */
1304 if (lp
->waitstatus
.kind
!= TARGET_WAITKIND_IGNORE
)
1305 signo
= GDB_SIGNAL_0
; /* a pending ptrace event, not a real signal. */
1306 else if (lp
->status
)
1307 signo
= gdb_signal_from_host (WSTOPSIG (lp
->status
));
1310 struct thread_info
*tp
= find_thread_ptid (linux_target
, lp
->ptid
);
1312 if (target_is_non_stop_p () && !tp
->executing
)
1314 if (tp
->suspend
.waitstatus_pending_p
)
1315 signo
= tp
->suspend
.waitstatus
.value
.sig
;
1317 signo
= tp
->suspend
.stop_signal
;
1319 else if (!target_is_non_stop_p ())
1322 process_stratum_target
*last_target
;
1324 get_last_target_status (&last_target
, &last_ptid
, nullptr);
1326 if (last_target
== linux_target
1327 && lp
->ptid
.lwp () == last_ptid
.lwp ())
1328 signo
= tp
->suspend
.stop_signal
;
1332 if (signo
== GDB_SIGNAL_0
)
1334 if (debug_linux_nat
)
1335 fprintf_unfiltered (gdb_stdlog
,
1336 "GPT: lwp %s has no pending signal\n",
1337 target_pid_to_str (lp
->ptid
).c_str ());
1339 else if (!signal_pass_state (signo
))
1341 if (debug_linux_nat
)
1342 fprintf_unfiltered (gdb_stdlog
,
1343 "GPT: lwp %s had signal %s, "
1344 "but it is in no pass state\n",
1345 target_pid_to_str (lp
->ptid
).c_str (),
1346 gdb_signal_to_string (signo
));
1350 if (debug_linux_nat
)
1351 fprintf_unfiltered (gdb_stdlog
,
1352 "GPT: lwp %s has pending signal %s\n",
1353 target_pid_to_str (lp
->ptid
).c_str (),
1354 gdb_signal_to_string (signo
));
1356 return gdb_signal_to_host (signo
);
1362 /* Detach from LP. If SIGNO_P is non-NULL, then it points to the
1363 signal number that should be passed to the LWP when detaching.
1364 Otherwise pass any pending signal the LWP may have, if any. */
1367 detach_one_lwp (struct lwp_info
*lp
, int *signo_p
)
1369 int lwpid
= lp
->ptid
.lwp ();
1372 gdb_assert (lp
->status
== 0 || WIFSTOPPED (lp
->status
));
1374 if (debug_linux_nat
&& lp
->status
)
1375 fprintf_unfiltered (gdb_stdlog
, "DC: Pending %s for %s on detach.\n",
1376 strsignal (WSTOPSIG (lp
->status
)),
1377 target_pid_to_str (lp
->ptid
).c_str ());
1379 /* If there is a pending SIGSTOP, get rid of it. */
1382 if (debug_linux_nat
)
1383 fprintf_unfiltered (gdb_stdlog
,
1384 "DC: Sending SIGCONT to %s\n",
1385 target_pid_to_str (lp
->ptid
).c_str ());
1387 kill_lwp (lwpid
, SIGCONT
);
1391 if (signo_p
== NULL
)
1393 /* Pass on any pending signal for this LWP. */
1394 signo
= get_detach_signal (lp
);
1399 /* Preparing to resume may try to write registers, and fail if the
1400 lwp is zombie. If that happens, ignore the error. We'll handle
1401 it below, when detach fails with ESRCH. */
1404 linux_target
->low_prepare_to_resume (lp
);
1406 catch (const gdb_exception_error
&ex
)
1408 if (!check_ptrace_stopped_lwp_gone (lp
))
1412 if (ptrace (PTRACE_DETACH
, lwpid
, 0, signo
) < 0)
1414 int save_errno
= errno
;
1416 /* We know the thread exists, so ESRCH must mean the lwp is
1417 zombie. This can happen if one of the already-detached
1418 threads exits the whole thread group. In that case we're
1419 still attached, and must reap the lwp. */
1420 if (save_errno
== ESRCH
)
1424 ret
= my_waitpid (lwpid
, &status
, __WALL
);
1427 warning (_("Couldn't reap LWP %d while detaching: %s"),
1428 lwpid
, safe_strerror (errno
));
1430 else if (!WIFEXITED (status
) && !WIFSIGNALED (status
))
1432 warning (_("Reaping LWP %d while detaching "
1433 "returned unexpected status 0x%x"),
1439 error (_("Can't detach %s: %s"),
1440 target_pid_to_str (lp
->ptid
).c_str (),
1441 safe_strerror (save_errno
));
1444 else if (debug_linux_nat
)
1446 fprintf_unfiltered (gdb_stdlog
,
1447 "PTRACE_DETACH (%s, %s, 0) (OK)\n",
1448 target_pid_to_str (lp
->ptid
).c_str (),
1452 delete_lwp (lp
->ptid
);
1456 detach_callback (struct lwp_info
*lp
)
1458 /* We don't actually detach from the thread group leader just yet.
1459 If the thread group exits, we must reap the zombie clone lwps
1460 before we're able to reap the leader. */
1461 if (lp
->ptid
.lwp () != lp
->ptid
.pid ())
1462 detach_one_lwp (lp
, NULL
);
1467 linux_nat_target::detach (inferior
*inf
, int from_tty
)
1469 struct lwp_info
*main_lwp
;
1472 /* Don't unregister from the event loop, as there may be other
1473 inferiors running. */
1475 /* Stop all threads before detaching. ptrace requires that the
1476 thread is stopped to successfully detach. */
1477 iterate_over_lwps (ptid_t (pid
), stop_callback
);
1478 /* ... and wait until all of them have reported back that
1479 they're no longer running. */
1480 iterate_over_lwps (ptid_t (pid
), stop_wait_callback
);
1482 iterate_over_lwps (ptid_t (pid
), detach_callback
);
1484 /* Only the initial process should be left right now. */
1485 gdb_assert (num_lwps (pid
) == 1);
1487 main_lwp
= find_lwp_pid (ptid_t (pid
));
1489 if (forks_exist_p ())
1491 /* Multi-fork case. The current inferior_ptid is being detached
1492 from, but there are other viable forks to debug. Detach from
1493 the current fork, and context-switch to the first
1495 linux_fork_detach (from_tty
);
1499 target_announce_detach (from_tty
);
1501 /* Pass on any pending signal for the last LWP. */
1502 int signo
= get_detach_signal (main_lwp
);
1504 detach_one_lwp (main_lwp
, &signo
);
1506 detach_success (inf
);
1510 /* Resume execution of the inferior process. If STEP is nonzero,
1511 single-step it. If SIGNAL is nonzero, give it that signal. */
1514 linux_resume_one_lwp_throw (struct lwp_info
*lp
, int step
,
1515 enum gdb_signal signo
)
1519 /* stop_pc doubles as the PC the LWP had when it was last resumed.
1520 We only presently need that if the LWP is stepped though (to
1521 handle the case of stepping a breakpoint instruction). */
1524 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
1526 lp
->stop_pc
= regcache_read_pc (regcache
);
1531 linux_target
->low_prepare_to_resume (lp
);
1532 linux_target
->low_resume (lp
->ptid
, step
, signo
);
1534 /* Successfully resumed. Clear state that no longer makes sense,
1535 and mark the LWP as running. Must not do this before resuming
1536 otherwise if that fails other code will be confused. E.g., we'd
1537 later try to stop the LWP and hang forever waiting for a stop
1538 status. Note that we must not throw after this is cleared,
1539 otherwise handle_zombie_lwp_error would get confused. */
1542 lp
->stop_reason
= TARGET_STOPPED_BY_NO_REASON
;
1543 registers_changed_ptid (linux_target
, lp
->ptid
);
1546 /* Called when we try to resume a stopped LWP and that errors out. If
1547 the LWP is no longer in ptrace-stopped state (meaning it's zombie,
1548 or about to become), discard the error, clear any pending status
1549 the LWP may have, and return true (we'll collect the exit status
1550 soon enough). Otherwise, return false. */
1553 check_ptrace_stopped_lwp_gone (struct lwp_info
*lp
)
1555 /* If we get an error after resuming the LWP successfully, we'd
1556 confuse !T state for the LWP being gone. */
1557 gdb_assert (lp
->stopped
);
1559 /* We can't just check whether the LWP is in 'Z (Zombie)' state,
1560 because even if ptrace failed with ESRCH, the tracee may be "not
1561 yet fully dead", but already refusing ptrace requests. In that
1562 case the tracee has 'R (Running)' state for a little bit
1563 (observed in Linux 3.18). See also the note on ESRCH in the
1564 ptrace(2) man page. Instead, check whether the LWP has any state
1565 other than ptrace-stopped. */
1567 /* Don't assume anything if /proc/PID/status can't be read. */
1568 if (linux_proc_pid_is_trace_stopped_nowarn (lp
->ptid
.lwp ()) == 0)
1570 lp
->stop_reason
= TARGET_STOPPED_BY_NO_REASON
;
1572 lp
->waitstatus
.kind
= TARGET_WAITKIND_IGNORE
;
1578 /* Like linux_resume_one_lwp_throw, but no error is thrown if the LWP
1579 disappears while we try to resume it. */
1582 linux_resume_one_lwp (struct lwp_info
*lp
, int step
, enum gdb_signal signo
)
1586 linux_resume_one_lwp_throw (lp
, step
, signo
);
1588 catch (const gdb_exception_error
&ex
)
1590 if (!check_ptrace_stopped_lwp_gone (lp
))
1598 resume_lwp (struct lwp_info
*lp
, int step
, enum gdb_signal signo
)
1602 struct inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
1604 if (inf
->vfork_child
!= NULL
)
1606 if (debug_linux_nat
)
1607 fprintf_unfiltered (gdb_stdlog
,
1608 "RC: Not resuming %s (vfork parent)\n",
1609 target_pid_to_str (lp
->ptid
).c_str ());
1611 else if (!lwp_status_pending_p (lp
))
1613 if (debug_linux_nat
)
1614 fprintf_unfiltered (gdb_stdlog
,
1615 "RC: Resuming sibling %s, %s, %s\n",
1616 target_pid_to_str (lp
->ptid
).c_str (),
1617 (signo
!= GDB_SIGNAL_0
1618 ? strsignal (gdb_signal_to_host (signo
))
1620 step
? "step" : "resume");
1622 linux_resume_one_lwp (lp
, step
, signo
);
1626 if (debug_linux_nat
)
1627 fprintf_unfiltered (gdb_stdlog
,
1628 "RC: Not resuming sibling %s (has pending)\n",
1629 target_pid_to_str (lp
->ptid
).c_str ());
1634 if (debug_linux_nat
)
1635 fprintf_unfiltered (gdb_stdlog
,
1636 "RC: Not resuming sibling %s (not stopped)\n",
1637 target_pid_to_str (lp
->ptid
).c_str ());
1641 /* Callback for iterate_over_lwps. If LWP is EXCEPT, do nothing.
1642 Resume LWP with the last stop signal, if it is in pass state. */
1645 linux_nat_resume_callback (struct lwp_info
*lp
, struct lwp_info
*except
)
1647 enum gdb_signal signo
= GDB_SIGNAL_0
;
1654 struct thread_info
*thread
;
1656 thread
= find_thread_ptid (linux_target
, lp
->ptid
);
1659 signo
= thread
->suspend
.stop_signal
;
1660 thread
->suspend
.stop_signal
= GDB_SIGNAL_0
;
1664 resume_lwp (lp
, 0, signo
);
1669 resume_clear_callback (struct lwp_info
*lp
)
1672 lp
->last_resume_kind
= resume_stop
;
1677 resume_set_callback (struct lwp_info
*lp
)
1680 lp
->last_resume_kind
= resume_continue
;
1685 linux_nat_target::resume (ptid_t ptid
, int step
, enum gdb_signal signo
)
1687 struct lwp_info
*lp
;
1690 if (debug_linux_nat
)
1691 fprintf_unfiltered (gdb_stdlog
,
1692 "LLR: Preparing to %s %s, %s, inferior_ptid %s\n",
1693 step
? "step" : "resume",
1694 target_pid_to_str (ptid
).c_str (),
1695 (signo
!= GDB_SIGNAL_0
1696 ? strsignal (gdb_signal_to_host (signo
)) : "0"),
1697 target_pid_to_str (inferior_ptid
).c_str ());
1699 /* A specific PTID means `step only this process id'. */
1700 resume_many
= (minus_one_ptid
== ptid
1703 /* Mark the lwps we're resuming as resumed and update their
1704 last_resume_kind to resume_continue. */
1705 iterate_over_lwps (ptid
, resume_set_callback
);
1707 /* See if it's the current inferior that should be handled
1710 lp
= find_lwp_pid (inferior_ptid
);
1712 lp
= find_lwp_pid (ptid
);
1713 gdb_assert (lp
!= NULL
);
1715 /* Remember if we're stepping. */
1716 lp
->last_resume_kind
= step
? resume_step
: resume_continue
;
1718 /* If we have a pending wait status for this thread, there is no
1719 point in resuming the process. But first make sure that
1720 linux_nat_wait won't preemptively handle the event - we
1721 should never take this short-circuit if we are going to
1722 leave LP running, since we have skipped resuming all the
1723 other threads. This bit of code needs to be synchronized
1724 with linux_nat_wait. */
1726 if (lp
->status
&& WIFSTOPPED (lp
->status
))
1729 && WSTOPSIG (lp
->status
)
1730 && sigismember (&pass_mask
, WSTOPSIG (lp
->status
)))
1732 if (debug_linux_nat
)
1733 fprintf_unfiltered (gdb_stdlog
,
1734 "LLR: Not short circuiting for ignored "
1735 "status 0x%x\n", lp
->status
);
1737 /* FIXME: What should we do if we are supposed to continue
1738 this thread with a signal? */
1739 gdb_assert (signo
== GDB_SIGNAL_0
);
1740 signo
= gdb_signal_from_host (WSTOPSIG (lp
->status
));
1745 if (lwp_status_pending_p (lp
))
1747 /* FIXME: What should we do if we are supposed to continue
1748 this thread with a signal? */
1749 gdb_assert (signo
== GDB_SIGNAL_0
);
1751 if (debug_linux_nat
)
1752 fprintf_unfiltered (gdb_stdlog
,
1753 "LLR: Short circuiting for status 0x%x\n",
1756 if (target_can_async_p ())
1759 /* Tell the event loop we have something to process. */
1766 iterate_over_lwps (ptid
, [=] (struct lwp_info
*info
)
1768 return linux_nat_resume_callback (info
, lp
);
1771 if (debug_linux_nat
)
1772 fprintf_unfiltered (gdb_stdlog
,
1773 "LLR: %s %s, %s (resume event thread)\n",
1774 step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
1775 target_pid_to_str (lp
->ptid
).c_str (),
1776 (signo
!= GDB_SIGNAL_0
1777 ? strsignal (gdb_signal_to_host (signo
)) : "0"));
1779 linux_resume_one_lwp (lp
, step
, signo
);
1781 if (target_can_async_p ())
1785 /* Send a signal to an LWP. */
1788 kill_lwp (int lwpid
, int signo
)
1793 ret
= syscall (__NR_tkill
, lwpid
, signo
);
1794 if (errno
== ENOSYS
)
1796 /* If tkill fails, then we are not using nptl threads, a
1797 configuration we no longer support. */
1798 perror_with_name (("tkill"));
1803 /* Handle a GNU/Linux syscall trap wait response. If we see a syscall
1804 event, check if the core is interested in it: if not, ignore the
1805 event, and keep waiting; otherwise, we need to toggle the LWP's
1806 syscall entry/exit status, since the ptrace event itself doesn't
1807 indicate it, and report the trap to higher layers. */
1810 linux_handle_syscall_trap (struct lwp_info
*lp
, int stopping
)
1812 struct target_waitstatus
*ourstatus
= &lp
->waitstatus
;
1813 struct gdbarch
*gdbarch
= target_thread_architecture (lp
->ptid
);
1814 thread_info
*thread
= find_thread_ptid (linux_target
, lp
->ptid
);
1815 int syscall_number
= (int) gdbarch_get_syscall_number (gdbarch
, thread
);
1819 /* If we're stopping threads, there's a SIGSTOP pending, which
1820 makes it so that the LWP reports an immediate syscall return,
1821 followed by the SIGSTOP. Skip seeing that "return" using
1822 PTRACE_CONT directly, and let stop_wait_callback collect the
1823 SIGSTOP. Later when the thread is resumed, a new syscall
1824 entry event. If we didn't do this (and returned 0), we'd
1825 leave a syscall entry pending, and our caller, by using
1826 PTRACE_CONT to collect the SIGSTOP, skips the syscall return
1827 itself. Later, when the user re-resumes this LWP, we'd see
1828 another syscall entry event and we'd mistake it for a return.
1830 If stop_wait_callback didn't force the SIGSTOP out of the LWP
1831 (leaving immediately with LWP->signalled set, without issuing
1832 a PTRACE_CONT), it would still be problematic to leave this
1833 syscall enter pending, as later when the thread is resumed,
1834 it would then see the same syscall exit mentioned above,
1835 followed by the delayed SIGSTOP, while the syscall didn't
1836 actually get to execute. It seems it would be even more
1837 confusing to the user. */
1839 if (debug_linux_nat
)
1840 fprintf_unfiltered (gdb_stdlog
,
1841 "LHST: ignoring syscall %d "
1842 "for LWP %ld (stopping threads), "
1843 "resuming with PTRACE_CONT for SIGSTOP\n",
1847 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
1848 ptrace (PTRACE_CONT
, lp
->ptid
.lwp (), 0, 0);
1853 /* Always update the entry/return state, even if this particular
1854 syscall isn't interesting to the core now. In async mode,
1855 the user could install a new catchpoint for this syscall
1856 between syscall enter/return, and we'll need to know to
1857 report a syscall return if that happens. */
1858 lp
->syscall_state
= (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1859 ? TARGET_WAITKIND_SYSCALL_RETURN
1860 : TARGET_WAITKIND_SYSCALL_ENTRY
);
1862 if (catch_syscall_enabled ())
1864 if (catching_syscall_number (syscall_number
))
1866 /* Alright, an event to report. */
1867 ourstatus
->kind
= lp
->syscall_state
;
1868 ourstatus
->value
.syscall_number
= syscall_number
;
1870 if (debug_linux_nat
)
1871 fprintf_unfiltered (gdb_stdlog
,
1872 "LHST: stopping for %s of syscall %d"
1875 == TARGET_WAITKIND_SYSCALL_ENTRY
1876 ? "entry" : "return",
1882 if (debug_linux_nat
)
1883 fprintf_unfiltered (gdb_stdlog
,
1884 "LHST: ignoring %s of syscall %d "
1886 lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1887 ? "entry" : "return",
1893 /* If we had been syscall tracing, and hence used PT_SYSCALL
1894 before on this LWP, it could happen that the user removes all
1895 syscall catchpoints before we get to process this event.
1896 There are two noteworthy issues here:
1898 - When stopped at a syscall entry event, resuming with
1899 PT_STEP still resumes executing the syscall and reports a
1902 - Only PT_SYSCALL catches syscall enters. If we last
1903 single-stepped this thread, then this event can't be a
1904 syscall enter. If we last single-stepped this thread, this
1905 has to be a syscall exit.
1907 The points above mean that the next resume, be it PT_STEP or
1908 PT_CONTINUE, can not trigger a syscall trace event. */
1909 if (debug_linux_nat
)
1910 fprintf_unfiltered (gdb_stdlog
,
1911 "LHST: caught syscall event "
1912 "with no syscall catchpoints."
1913 " %d for LWP %ld, ignoring\n",
1916 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
1919 /* The core isn't interested in this event. For efficiency, avoid
1920 stopping all threads only to have the core resume them all again.
1921 Since we're not stopping threads, if we're still syscall tracing
1922 and not stepping, we can't use PTRACE_CONT here, as we'd miss any
1923 subsequent syscall. Simply resume using the inf-ptrace layer,
1924 which knows when to use PT_SYSCALL or PT_CONTINUE. */
1926 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
1930 /* Handle a GNU/Linux extended wait response. If we see a clone
1931 event, we need to add the new LWP to our list (and not report the
1932 trap to higher layers). This function returns non-zero if the
1933 event should be ignored and we should wait again. If STOPPING is
1934 true, the new LWP remains stopped, otherwise it is continued. */
1937 linux_handle_extended_wait (struct lwp_info
*lp
, int status
)
1939 int pid
= lp
->ptid
.lwp ();
1940 struct target_waitstatus
*ourstatus
= &lp
->waitstatus
;
1941 int event
= linux_ptrace_get_extended_event (status
);
1943 /* All extended events we currently use are mid-syscall. Only
1944 PTRACE_EVENT_STOP is delivered more like a signal-stop, but
1945 you have to be using PTRACE_SEIZE to get that. */
1946 lp
->syscall_state
= TARGET_WAITKIND_SYSCALL_ENTRY
;
1948 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
1949 || event
== PTRACE_EVENT_CLONE
)
1951 unsigned long new_pid
;
1954 ptrace (PTRACE_GETEVENTMSG
, pid
, 0, &new_pid
);
1956 /* If we haven't already seen the new PID stop, wait for it now. */
1957 if (! pull_pid_from_list (&stopped_pids
, new_pid
, &status
))
1959 /* The new child has a pending SIGSTOP. We can't affect it until it
1960 hits the SIGSTOP, but we're already attached. */
1961 ret
= my_waitpid (new_pid
, &status
, __WALL
);
1963 perror_with_name (_("waiting for new child"));
1964 else if (ret
!= new_pid
)
1965 internal_error (__FILE__
, __LINE__
,
1966 _("wait returned unexpected PID %d"), ret
);
1967 else if (!WIFSTOPPED (status
))
1968 internal_error (__FILE__
, __LINE__
,
1969 _("wait returned unexpected status 0x%x"), status
);
1972 ourstatus
->value
.related_pid
= ptid_t (new_pid
, new_pid
, 0);
1974 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
)
1976 /* The arch-specific native code may need to know about new
1977 forks even if those end up never mapped to an
1979 linux_target
->low_new_fork (lp
, new_pid
);
1981 else if (event
== PTRACE_EVENT_CLONE
)
1983 linux_target
->low_new_clone (lp
, new_pid
);
1986 if (event
== PTRACE_EVENT_FORK
1987 && linux_fork_checkpointing_p (lp
->ptid
.pid ()))
1989 /* Handle checkpointing by linux-fork.c here as a special
1990 case. We don't want the follow-fork-mode or 'catch fork'
1991 to interfere with this. */
1993 /* This won't actually modify the breakpoint list, but will
1994 physically remove the breakpoints from the child. */
1995 detach_breakpoints (ptid_t (new_pid
, new_pid
, 0));
1997 /* Retain child fork in ptrace (stopped) state. */
1998 if (!find_fork_pid (new_pid
))
2001 /* Report as spurious, so that infrun doesn't want to follow
2002 this fork. We're actually doing an infcall in
2004 ourstatus
->kind
= TARGET_WAITKIND_SPURIOUS
;
2006 /* Report the stop to the core. */
2010 if (event
== PTRACE_EVENT_FORK
)
2011 ourstatus
->kind
= TARGET_WAITKIND_FORKED
;
2012 else if (event
== PTRACE_EVENT_VFORK
)
2013 ourstatus
->kind
= TARGET_WAITKIND_VFORKED
;
2014 else if (event
== PTRACE_EVENT_CLONE
)
2016 struct lwp_info
*new_lp
;
2018 ourstatus
->kind
= TARGET_WAITKIND_IGNORE
;
2020 if (debug_linux_nat
)
2021 fprintf_unfiltered (gdb_stdlog
,
2022 "LHEW: Got clone event "
2023 "from LWP %d, new child is LWP %ld\n",
2026 new_lp
= add_lwp (ptid_t (lp
->ptid
.pid (), new_pid
, 0));
2027 new_lp
->stopped
= 1;
2028 new_lp
->resumed
= 1;
2030 /* If the thread_db layer is active, let it record the user
2031 level thread id and status, and add the thread to GDB's
2033 if (!thread_db_notice_clone (lp
->ptid
, new_lp
->ptid
))
2035 /* The process is not using thread_db. Add the LWP to
2037 target_post_attach (new_lp
->ptid
.lwp ());
2038 add_thread (linux_target
, new_lp
->ptid
);
2041 /* Even if we're stopping the thread for some reason
2042 internal to this module, from the perspective of infrun
2043 and the user/frontend, this new thread is running until
2044 it next reports a stop. */
2045 set_running (linux_target
, new_lp
->ptid
, true);
2046 set_executing (linux_target
, new_lp
->ptid
, true);
2048 if (WSTOPSIG (status
) != SIGSTOP
)
2050 /* This can happen if someone starts sending signals to
2051 the new thread before it gets a chance to run, which
2052 have a lower number than SIGSTOP (e.g. SIGUSR1).
2053 This is an unlikely case, and harder to handle for
2054 fork / vfork than for clone, so we do not try - but
2055 we handle it for clone events here. */
2057 new_lp
->signalled
= 1;
2059 /* We created NEW_LP so it cannot yet contain STATUS. */
2060 gdb_assert (new_lp
->status
== 0);
2062 /* Save the wait status to report later. */
2063 if (debug_linux_nat
)
2064 fprintf_unfiltered (gdb_stdlog
,
2065 "LHEW: waitpid of new LWP %ld, "
2066 "saving status %s\n",
2067 (long) new_lp
->ptid
.lwp (),
2068 status_to_str (status
));
2069 new_lp
->status
= status
;
2071 else if (report_thread_events
)
2073 new_lp
->waitstatus
.kind
= TARGET_WAITKIND_THREAD_CREATED
;
2074 new_lp
->status
= status
;
2083 if (event
== PTRACE_EVENT_EXEC
)
2085 if (debug_linux_nat
)
2086 fprintf_unfiltered (gdb_stdlog
,
2087 "LHEW: Got exec event from LWP %ld\n",
2090 ourstatus
->kind
= TARGET_WAITKIND_EXECD
;
2091 ourstatus
->value
.execd_pathname
2092 = xstrdup (linux_proc_pid_to_exec_file (pid
));
2094 /* The thread that execed must have been resumed, but, when a
2095 thread execs, it changes its tid to the tgid, and the old
2096 tgid thread might have not been resumed. */
2101 if (event
== PTRACE_EVENT_VFORK_DONE
)
2103 if (current_inferior ()->waiting_for_vfork_done
)
2105 if (debug_linux_nat
)
2106 fprintf_unfiltered (gdb_stdlog
,
2107 "LHEW: Got expected PTRACE_EVENT_"
2108 "VFORK_DONE from LWP %ld: stopping\n",
2111 ourstatus
->kind
= TARGET_WAITKIND_VFORK_DONE
;
2115 if (debug_linux_nat
)
2116 fprintf_unfiltered (gdb_stdlog
,
2117 "LHEW: Got PTRACE_EVENT_VFORK_DONE "
2118 "from LWP %ld: ignoring\n",
2123 internal_error (__FILE__
, __LINE__
,
2124 _("unknown ptrace event %d"), event
);
2127 /* Suspend waiting for a signal. We're mostly interested in
2133 if (debug_linux_nat
)
2134 fprintf_unfiltered (gdb_stdlog
, "linux-nat: about to sigsuspend\n");
2135 sigsuspend (&suspend_mask
);
2137 /* If the quit flag is set, it means that the user pressed Ctrl-C
2138 and we're debugging a process that is running on a separate
2139 terminal, so we must forward the Ctrl-C to the inferior. (If the
2140 inferior is sharing GDB's terminal, then the Ctrl-C reaches the
2141 inferior directly.) We must do this here because functions that
2142 need to block waiting for a signal loop forever until there's an
2143 event to report before returning back to the event loop. */
2144 if (!target_terminal::is_ours ())
2146 if (check_quit_flag ())
2147 target_pass_ctrlc ();
2151 /* Wait for LP to stop. Returns the wait status, or 0 if the LWP has
2155 wait_lwp (struct lwp_info
*lp
)
2159 int thread_dead
= 0;
2162 gdb_assert (!lp
->stopped
);
2163 gdb_assert (lp
->status
== 0);
2165 /* Make sure SIGCHLD is blocked for sigsuspend avoiding a race below. */
2166 block_child_signals (&prev_mask
);
2170 pid
= my_waitpid (lp
->ptid
.lwp (), &status
, __WALL
| WNOHANG
);
2171 if (pid
== -1 && errno
== ECHILD
)
2173 /* The thread has previously exited. We need to delete it
2174 now because if this was a non-leader thread execing, we
2175 won't get an exit event. See comments on exec events at
2176 the top of the file. */
2178 if (debug_linux_nat
)
2179 fprintf_unfiltered (gdb_stdlog
, "WL: %s vanished.\n",
2180 target_pid_to_str (lp
->ptid
).c_str ());
2185 /* Bugs 10970, 12702.
2186 Thread group leader may have exited in which case we'll lock up in
2187 waitpid if there are other threads, even if they are all zombies too.
2188 Basically, we're not supposed to use waitpid this way.
2189 tkill(pid,0) cannot be used here as it gets ESRCH for both
2190 for zombie and running processes.
2192 As a workaround, check if we're waiting for the thread group leader and
2193 if it's a zombie, and avoid calling waitpid if it is.
2195 This is racy, what if the tgl becomes a zombie right after we check?
2196 Therefore always use WNOHANG with sigsuspend - it is equivalent to
2197 waiting waitpid but linux_proc_pid_is_zombie is safe this way. */
2199 if (lp
->ptid
.pid () == lp
->ptid
.lwp ()
2200 && linux_proc_pid_is_zombie (lp
->ptid
.lwp ()))
2203 if (debug_linux_nat
)
2204 fprintf_unfiltered (gdb_stdlog
,
2205 "WL: Thread group leader %s vanished.\n",
2206 target_pid_to_str (lp
->ptid
).c_str ());
2210 /* Wait for next SIGCHLD and try again. This may let SIGCHLD handlers
2211 get invoked despite our caller had them intentionally blocked by
2212 block_child_signals. This is sensitive only to the loop of
2213 linux_nat_wait_1 and there if we get called my_waitpid gets called
2214 again before it gets to sigsuspend so we can safely let the handlers
2215 get executed here. */
2219 restore_child_signals_mask (&prev_mask
);
2223 gdb_assert (pid
== lp
->ptid
.lwp ());
2225 if (debug_linux_nat
)
2227 fprintf_unfiltered (gdb_stdlog
,
2228 "WL: waitpid %s received %s\n",
2229 target_pid_to_str (lp
->ptid
).c_str (),
2230 status_to_str (status
));
2233 /* Check if the thread has exited. */
2234 if (WIFEXITED (status
) || WIFSIGNALED (status
))
2236 if (report_thread_events
2237 || lp
->ptid
.pid () == lp
->ptid
.lwp ())
2239 if (debug_linux_nat
)
2240 fprintf_unfiltered (gdb_stdlog
, "WL: LWP %d exited.\n",
2243 /* If this is the leader exiting, it means the whole
2244 process is gone. Store the status to report to the
2245 core. Store it in lp->waitstatus, because lp->status
2246 would be ambiguous (W_EXITCODE(0,0) == 0). */
2247 store_waitstatus (&lp
->waitstatus
, status
);
2252 if (debug_linux_nat
)
2253 fprintf_unfiltered (gdb_stdlog
, "WL: %s exited.\n",
2254 target_pid_to_str (lp
->ptid
).c_str ());
2264 gdb_assert (WIFSTOPPED (status
));
2267 if (lp
->must_set_ptrace_flags
)
2269 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2270 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
2272 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
2273 lp
->must_set_ptrace_flags
= 0;
2276 /* Handle GNU/Linux's syscall SIGTRAPs. */
2277 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
2279 /* No longer need the sysgood bit. The ptrace event ends up
2280 recorded in lp->waitstatus if we care for it. We can carry
2281 on handling the event like a regular SIGTRAP from here
2283 status
= W_STOPCODE (SIGTRAP
);
2284 if (linux_handle_syscall_trap (lp
, 1))
2285 return wait_lwp (lp
);
2289 /* Almost all other ptrace-stops are known to be outside of system
2290 calls, with further exceptions in linux_handle_extended_wait. */
2291 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
2294 /* Handle GNU/Linux's extended waitstatus for trace events. */
2295 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
2296 && linux_is_extended_waitstatus (status
))
2298 if (debug_linux_nat
)
2299 fprintf_unfiltered (gdb_stdlog
,
2300 "WL: Handling extended status 0x%06x\n",
2302 linux_handle_extended_wait (lp
, status
);
2309 /* Send a SIGSTOP to LP. */
2312 stop_callback (struct lwp_info
*lp
)
2314 if (!lp
->stopped
&& !lp
->signalled
)
2318 if (debug_linux_nat
)
2320 fprintf_unfiltered (gdb_stdlog
,
2321 "SC: kill %s **<SIGSTOP>**\n",
2322 target_pid_to_str (lp
->ptid
).c_str ());
2325 ret
= kill_lwp (lp
->ptid
.lwp (), SIGSTOP
);
2326 if (debug_linux_nat
)
2328 fprintf_unfiltered (gdb_stdlog
,
2329 "SC: lwp kill %d %s\n",
2331 errno
? safe_strerror (errno
) : "ERRNO-OK");
2335 gdb_assert (lp
->status
== 0);
2341 /* Request a stop on LWP. */
2344 linux_stop_lwp (struct lwp_info
*lwp
)
2346 stop_callback (lwp
);
2349 /* See linux-nat.h */
2352 linux_stop_and_wait_all_lwps (void)
2354 /* Stop all LWP's ... */
2355 iterate_over_lwps (minus_one_ptid
, stop_callback
);
2357 /* ... and wait until all of them have reported back that
2358 they're no longer running. */
2359 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
2362 /* See linux-nat.h */
2365 linux_unstop_all_lwps (void)
2367 iterate_over_lwps (minus_one_ptid
,
2368 [] (struct lwp_info
*info
)
2370 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
2374 /* Return non-zero if LWP PID has a pending SIGINT. */
2377 linux_nat_has_pending_sigint (int pid
)
2379 sigset_t pending
, blocked
, ignored
;
2381 linux_proc_pending_signals (pid
, &pending
, &blocked
, &ignored
);
2383 if (sigismember (&pending
, SIGINT
)
2384 && !sigismember (&ignored
, SIGINT
))
2390 /* Set a flag in LP indicating that we should ignore its next SIGINT. */
2393 set_ignore_sigint (struct lwp_info
*lp
)
2395 /* If a thread has a pending SIGINT, consume it; otherwise, set a
2396 flag to consume the next one. */
2397 if (lp
->stopped
&& lp
->status
!= 0 && WIFSTOPPED (lp
->status
)
2398 && WSTOPSIG (lp
->status
) == SIGINT
)
2401 lp
->ignore_sigint
= 1;
2406 /* If LP does not have a SIGINT pending, then clear the ignore_sigint flag.
2407 This function is called after we know the LWP has stopped; if the LWP
2408 stopped before the expected SIGINT was delivered, then it will never have
2409 arrived. Also, if the signal was delivered to a shared queue and consumed
2410 by a different thread, it will never be delivered to this LWP. */
2413 maybe_clear_ignore_sigint (struct lwp_info
*lp
)
2415 if (!lp
->ignore_sigint
)
2418 if (!linux_nat_has_pending_sigint (lp
->ptid
.lwp ()))
2420 if (debug_linux_nat
)
2421 fprintf_unfiltered (gdb_stdlog
,
2422 "MCIS: Clearing bogus flag for %s\n",
2423 target_pid_to_str (lp
->ptid
).c_str ());
2424 lp
->ignore_sigint
= 0;
2428 /* Fetch the possible triggered data watchpoint info and store it in
2431 On some archs, like x86, that use debug registers to set
2432 watchpoints, it's possible that the way to know which watched
2433 address trapped, is to check the register that is used to select
2434 which address to watch. Problem is, between setting the watchpoint
2435 and reading back which data address trapped, the user may change
2436 the set of watchpoints, and, as a consequence, GDB changes the
2437 debug registers in the inferior. To avoid reading back a stale
2438 stopped-data-address when that happens, we cache in LP the fact
2439 that a watchpoint trapped, and the corresponding data address, as
2440 soon as we see LP stop with a SIGTRAP. If GDB changes the debug
2441 registers meanwhile, we have the cached data we can rely on. */
2444 check_stopped_by_watchpoint (struct lwp_info
*lp
)
2446 scoped_restore save_inferior_ptid
= make_scoped_restore (&inferior_ptid
);
2447 inferior_ptid
= lp
->ptid
;
2449 if (linux_target
->low_stopped_by_watchpoint ())
2451 lp
->stop_reason
= TARGET_STOPPED_BY_WATCHPOINT
;
2452 lp
->stopped_data_address_p
2453 = linux_target
->low_stopped_data_address (&lp
->stopped_data_address
);
2456 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2459 /* Returns true if the LWP had stopped for a watchpoint. */
2462 linux_nat_target::stopped_by_watchpoint ()
2464 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2466 gdb_assert (lp
!= NULL
);
2468 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2472 linux_nat_target::stopped_data_address (CORE_ADDR
*addr_p
)
2474 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2476 gdb_assert (lp
!= NULL
);
2478 *addr_p
= lp
->stopped_data_address
;
2480 return lp
->stopped_data_address_p
;
2483 /* Commonly any breakpoint / watchpoint generate only SIGTRAP. */
2486 linux_nat_target::low_status_is_event (int status
)
2488 return WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
;
2491 /* Wait until LP is stopped. */
2494 stop_wait_callback (struct lwp_info
*lp
)
2496 inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
2498 /* If this is a vfork parent, bail out, it is not going to report
2499 any SIGSTOP until the vfork is done with. */
2500 if (inf
->vfork_child
!= NULL
)
2507 status
= wait_lwp (lp
);
2511 if (lp
->ignore_sigint
&& WIFSTOPPED (status
)
2512 && WSTOPSIG (status
) == SIGINT
)
2514 lp
->ignore_sigint
= 0;
2517 ptrace (PTRACE_CONT
, lp
->ptid
.lwp (), 0, 0);
2519 if (debug_linux_nat
)
2520 fprintf_unfiltered (gdb_stdlog
,
2521 "PTRACE_CONT %s, 0, 0 (%s) "
2522 "(discarding SIGINT)\n",
2523 target_pid_to_str (lp
->ptid
).c_str (),
2524 errno
? safe_strerror (errno
) : "OK");
2526 return stop_wait_callback (lp
);
2529 maybe_clear_ignore_sigint (lp
);
2531 if (WSTOPSIG (status
) != SIGSTOP
)
2533 /* The thread was stopped with a signal other than SIGSTOP. */
2535 if (debug_linux_nat
)
2536 fprintf_unfiltered (gdb_stdlog
,
2537 "SWC: Pending event %s in %s\n",
2538 status_to_str ((int) status
),
2539 target_pid_to_str (lp
->ptid
).c_str ());
2541 /* Save the sigtrap event. */
2542 lp
->status
= status
;
2543 gdb_assert (lp
->signalled
);
2544 save_stop_reason (lp
);
2548 /* We caught the SIGSTOP that we intended to catch. */
2550 if (debug_linux_nat
)
2551 fprintf_unfiltered (gdb_stdlog
,
2552 "SWC: Expected SIGSTOP caught for %s.\n",
2553 target_pid_to_str (lp
->ptid
).c_str ());
2557 /* If we are waiting for this stop so we can report the thread
2558 stopped then we need to record this status. Otherwise, we can
2559 now discard this stop event. */
2560 if (lp
->last_resume_kind
== resume_stop
)
2562 lp
->status
= status
;
2563 save_stop_reason (lp
);
2571 /* Return non-zero if LP has a wait status pending. Discard the
2572 pending event and resume the LWP if the event that originally
2573 caused the stop became uninteresting. */
2576 status_callback (struct lwp_info
*lp
)
2578 /* Only report a pending wait status if we pretend that this has
2579 indeed been resumed. */
2583 if (!lwp_status_pending_p (lp
))
2586 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
2587 || lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2589 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2593 pc
= regcache_read_pc (regcache
);
2595 if (pc
!= lp
->stop_pc
)
2597 if (debug_linux_nat
)
2598 fprintf_unfiltered (gdb_stdlog
,
2599 "SC: PC of %s changed. was=%s, now=%s\n",
2600 target_pid_to_str (lp
->ptid
).c_str (),
2601 paddress (target_gdbarch (), lp
->stop_pc
),
2602 paddress (target_gdbarch (), pc
));
2606 #if !USE_SIGTRAP_SIGINFO
2607 else if (!breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2609 if (debug_linux_nat
)
2610 fprintf_unfiltered (gdb_stdlog
,
2611 "SC: previous breakpoint of %s, at %s gone\n",
2612 target_pid_to_str (lp
->ptid
).c_str (),
2613 paddress (target_gdbarch (), lp
->stop_pc
));
2621 if (debug_linux_nat
)
2622 fprintf_unfiltered (gdb_stdlog
,
2623 "SC: pending event of %s cancelled.\n",
2624 target_pid_to_str (lp
->ptid
).c_str ());
2627 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2635 /* Count the LWP's that have had events. */
2638 count_events_callback (struct lwp_info
*lp
, int *count
)
2640 gdb_assert (count
!= NULL
);
2642 /* Select only resumed LWPs that have an event pending. */
2643 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2649 /* Select the LWP (if any) that is currently being single-stepped. */
2652 select_singlestep_lwp_callback (struct lwp_info
*lp
)
2654 if (lp
->last_resume_kind
== resume_step
2661 /* Returns true if LP has a status pending. */
2664 lwp_status_pending_p (struct lwp_info
*lp
)
2666 /* We check for lp->waitstatus in addition to lp->status, because we
2667 can have pending process exits recorded in lp->status and
2668 W_EXITCODE(0,0) happens to be 0. */
2669 return lp
->status
!= 0 || lp
->waitstatus
.kind
!= TARGET_WAITKIND_IGNORE
;
2672 /* Select the Nth LWP that has had an event. */
2675 select_event_lwp_callback (struct lwp_info
*lp
, int *selector
)
2677 gdb_assert (selector
!= NULL
);
2679 /* Select only resumed LWPs that have an event pending. */
2680 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2681 if ((*selector
)-- == 0)
2687 /* Called when the LWP stopped for a signal/trap. If it stopped for a
2688 trap check what caused it (breakpoint, watchpoint, trace, etc.),
2689 and save the result in the LWP's stop_reason field. If it stopped
2690 for a breakpoint, decrement the PC if necessary on the lwp's
2694 save_stop_reason (struct lwp_info
*lp
)
2696 struct regcache
*regcache
;
2697 struct gdbarch
*gdbarch
;
2700 #if USE_SIGTRAP_SIGINFO
2704 gdb_assert (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
);
2705 gdb_assert (lp
->status
!= 0);
2707 if (!linux_target
->low_status_is_event (lp
->status
))
2710 regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2711 gdbarch
= regcache
->arch ();
2713 pc
= regcache_read_pc (regcache
);
2714 sw_bp_pc
= pc
- gdbarch_decr_pc_after_break (gdbarch
);
2716 #if USE_SIGTRAP_SIGINFO
2717 if (linux_nat_get_siginfo (lp
->ptid
, &siginfo
))
2719 if (siginfo
.si_signo
== SIGTRAP
)
2721 if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
)
2722 && GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2724 /* The si_code is ambiguous on this arch -- check debug
2726 if (!check_stopped_by_watchpoint (lp
))
2727 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2729 else if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
))
2731 /* If we determine the LWP stopped for a SW breakpoint,
2732 trust it. Particularly don't check watchpoint
2733 registers, because, at least on s390, we'd find
2734 stopped-by-watchpoint as long as there's a watchpoint
2736 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2738 else if (GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2740 /* This can indicate either a hardware breakpoint or
2741 hardware watchpoint. Check debug registers. */
2742 if (!check_stopped_by_watchpoint (lp
))
2743 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2745 else if (siginfo
.si_code
== TRAP_TRACE
)
2747 if (debug_linux_nat
)
2748 fprintf_unfiltered (gdb_stdlog
,
2749 "CSBB: %s stopped by trace\n",
2750 target_pid_to_str (lp
->ptid
).c_str ());
2752 /* We may have single stepped an instruction that
2753 triggered a watchpoint. In that case, on some
2754 architectures (such as x86), instead of TRAP_HWBKPT,
2755 si_code indicates TRAP_TRACE, and we need to check
2756 the debug registers separately. */
2757 check_stopped_by_watchpoint (lp
);
2762 if ((!lp
->step
|| lp
->stop_pc
== sw_bp_pc
)
2763 && software_breakpoint_inserted_here_p (regcache
->aspace (),
2766 /* The LWP was either continued, or stepped a software
2767 breakpoint instruction. */
2768 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2771 if (hardware_breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2772 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2774 if (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
)
2775 check_stopped_by_watchpoint (lp
);
2778 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
)
2780 if (debug_linux_nat
)
2781 fprintf_unfiltered (gdb_stdlog
,
2782 "CSBB: %s stopped by software breakpoint\n",
2783 target_pid_to_str (lp
->ptid
).c_str ());
2785 /* Back up the PC if necessary. */
2787 regcache_write_pc (regcache
, sw_bp_pc
);
2789 /* Update this so we record the correct stop PC below. */
2792 else if (lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2794 if (debug_linux_nat
)
2795 fprintf_unfiltered (gdb_stdlog
,
2796 "CSBB: %s stopped by hardware breakpoint\n",
2797 target_pid_to_str (lp
->ptid
).c_str ());
2799 else if (lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
)
2801 if (debug_linux_nat
)
2802 fprintf_unfiltered (gdb_stdlog
,
2803 "CSBB: %s stopped by hardware watchpoint\n",
2804 target_pid_to_str (lp
->ptid
).c_str ());
2811 /* Returns true if the LWP had stopped for a software breakpoint. */
2814 linux_nat_target::stopped_by_sw_breakpoint ()
2816 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2818 gdb_assert (lp
!= NULL
);
2820 return lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
;
2823 /* Implement the supports_stopped_by_sw_breakpoint method. */
2826 linux_nat_target::supports_stopped_by_sw_breakpoint ()
2828 return USE_SIGTRAP_SIGINFO
;
2831 /* Returns true if the LWP had stopped for a hardware
2832 breakpoint/watchpoint. */
2835 linux_nat_target::stopped_by_hw_breakpoint ()
2837 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2839 gdb_assert (lp
!= NULL
);
2841 return lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
;
2844 /* Implement the supports_stopped_by_hw_breakpoint method. */
2847 linux_nat_target::supports_stopped_by_hw_breakpoint ()
2849 return USE_SIGTRAP_SIGINFO
;
2852 /* Select one LWP out of those that have events pending. */
2855 select_event_lwp (ptid_t filter
, struct lwp_info
**orig_lp
, int *status
)
2858 int random_selector
;
2859 struct lwp_info
*event_lp
= NULL
;
2861 /* Record the wait status for the original LWP. */
2862 (*orig_lp
)->status
= *status
;
2864 /* In all-stop, give preference to the LWP that is being
2865 single-stepped. There will be at most one, and it will be the
2866 LWP that the core is most interested in. If we didn't do this,
2867 then we'd have to handle pending step SIGTRAPs somehow in case
2868 the core later continues the previously-stepped thread, as
2869 otherwise we'd report the pending SIGTRAP then, and the core, not
2870 having stepped the thread, wouldn't understand what the trap was
2871 for, and therefore would report it to the user as a random
2873 if (!target_is_non_stop_p ())
2875 event_lp
= iterate_over_lwps (filter
, select_singlestep_lwp_callback
);
2876 if (event_lp
!= NULL
)
2878 if (debug_linux_nat
)
2879 fprintf_unfiltered (gdb_stdlog
,
2880 "SEL: Select single-step %s\n",
2881 target_pid_to_str (event_lp
->ptid
).c_str ());
2885 if (event_lp
== NULL
)
2887 /* Pick one at random, out of those which have had events. */
2889 /* First see how many events we have. */
2890 iterate_over_lwps (filter
,
2891 [&] (struct lwp_info
*info
)
2893 return count_events_callback (info
, &num_events
);
2895 gdb_assert (num_events
> 0);
2897 /* Now randomly pick a LWP out of those that have had
2899 random_selector
= (int)
2900 ((num_events
* (double) rand ()) / (RAND_MAX
+ 1.0));
2902 if (debug_linux_nat
&& num_events
> 1)
2903 fprintf_unfiltered (gdb_stdlog
,
2904 "SEL: Found %d events, selecting #%d\n",
2905 num_events
, random_selector
);
2908 = (iterate_over_lwps
2910 [&] (struct lwp_info
*info
)
2912 return select_event_lwp_callback (info
,
2917 if (event_lp
!= NULL
)
2919 /* Switch the event LWP. */
2920 *orig_lp
= event_lp
;
2921 *status
= event_lp
->status
;
2924 /* Flush the wait status for the event LWP. */
2925 (*orig_lp
)->status
= 0;
2928 /* Return non-zero if LP has been resumed. */
2931 resumed_callback (struct lwp_info
*lp
)
2936 /* Check if we should go on and pass this event to common code.
2937 Return the affected lwp if we should, or NULL otherwise. */
2939 static struct lwp_info
*
2940 linux_nat_filter_event (int lwpid
, int status
)
2942 struct lwp_info
*lp
;
2943 int event
= linux_ptrace_get_extended_event (status
);
2945 lp
= find_lwp_pid (ptid_t (lwpid
));
2947 /* Check for stop events reported by a process we didn't already
2948 know about - anything not already in our LWP list.
2950 If we're expecting to receive stopped processes after
2951 fork, vfork, and clone events, then we'll just add the
2952 new one to our list and go back to waiting for the event
2953 to be reported - the stopped process might be returned
2954 from waitpid before or after the event is.
2956 But note the case of a non-leader thread exec'ing after the
2957 leader having exited, and gone from our lists. The non-leader
2958 thread changes its tid to the tgid. */
2960 if (WIFSTOPPED (status
) && lp
== NULL
2961 && (WSTOPSIG (status
) == SIGTRAP
&& event
== PTRACE_EVENT_EXEC
))
2963 /* A multi-thread exec after we had seen the leader exiting. */
2964 if (debug_linux_nat
)
2965 fprintf_unfiltered (gdb_stdlog
,
2966 "LLW: Re-adding thread group leader LWP %d.\n",
2969 lp
= add_lwp (ptid_t (lwpid
, lwpid
, 0));
2972 add_thread (linux_target
, lp
->ptid
);
2975 if (WIFSTOPPED (status
) && !lp
)
2977 if (debug_linux_nat
)
2978 fprintf_unfiltered (gdb_stdlog
,
2979 "LHEW: saving LWP %ld status %s in stopped_pids list\n",
2980 (long) lwpid
, status_to_str (status
));
2981 add_to_pid_list (&stopped_pids
, lwpid
, status
);
2985 /* Make sure we don't report an event for the exit of an LWP not in
2986 our list, i.e. not part of the current process. This can happen
2987 if we detach from a program we originally forked and then it
2989 if (!WIFSTOPPED (status
) && !lp
)
2992 /* This LWP is stopped now. (And if dead, this prevents it from
2993 ever being continued.) */
2996 if (WIFSTOPPED (status
) && lp
->must_set_ptrace_flags
)
2998 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2999 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
3001 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
3002 lp
->must_set_ptrace_flags
= 0;
3005 /* Handle GNU/Linux's syscall SIGTRAPs. */
3006 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
3008 /* No longer need the sysgood bit. The ptrace event ends up
3009 recorded in lp->waitstatus if we care for it. We can carry
3010 on handling the event like a regular SIGTRAP from here
3012 status
= W_STOPCODE (SIGTRAP
);
3013 if (linux_handle_syscall_trap (lp
, 0))
3018 /* Almost all other ptrace-stops are known to be outside of system
3019 calls, with further exceptions in linux_handle_extended_wait. */
3020 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
3023 /* Handle GNU/Linux's extended waitstatus for trace events. */
3024 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
3025 && linux_is_extended_waitstatus (status
))
3027 if (debug_linux_nat
)
3028 fprintf_unfiltered (gdb_stdlog
,
3029 "LLW: Handling extended status 0x%06x\n",
3031 if (linux_handle_extended_wait (lp
, status
))
3035 /* Check if the thread has exited. */
3036 if (WIFEXITED (status
) || WIFSIGNALED (status
))
3038 if (!report_thread_events
3039 && num_lwps (lp
->ptid
.pid ()) > 1)
3041 if (debug_linux_nat
)
3042 fprintf_unfiltered (gdb_stdlog
,
3043 "LLW: %s exited.\n",
3044 target_pid_to_str (lp
->ptid
).c_str ());
3046 /* If there is at least one more LWP, then the exit signal
3047 was not the end of the debugged application and should be
3053 /* Note that even if the leader was ptrace-stopped, it can still
3054 exit, if e.g., some other thread brings down the whole
3055 process (calls `exit'). So don't assert that the lwp is
3057 if (debug_linux_nat
)
3058 fprintf_unfiltered (gdb_stdlog
,
3059 "LWP %ld exited (resumed=%d)\n",
3060 lp
->ptid
.lwp (), lp
->resumed
);
3062 /* Dead LWP's aren't expected to reported a pending sigstop. */
3065 /* Store the pending event in the waitstatus, because
3066 W_EXITCODE(0,0) == 0. */
3067 store_waitstatus (&lp
->waitstatus
, status
);
3071 /* Make sure we don't report a SIGSTOP that we sent ourselves in
3072 an attempt to stop an LWP. */
3074 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGSTOP
)
3078 if (lp
->last_resume_kind
== resume_stop
)
3080 if (debug_linux_nat
)
3081 fprintf_unfiltered (gdb_stdlog
,
3082 "LLW: resume_stop SIGSTOP caught for %s.\n",
3083 target_pid_to_str (lp
->ptid
).c_str ());
3087 /* This is a delayed SIGSTOP. Filter out the event. */
3089 if (debug_linux_nat
)
3090 fprintf_unfiltered (gdb_stdlog
,
3091 "LLW: %s %s, 0, 0 (discard delayed SIGSTOP)\n",
3093 "PTRACE_SINGLESTEP" : "PTRACE_CONT",
3094 target_pid_to_str (lp
->ptid
).c_str ());
3096 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
3097 gdb_assert (lp
->resumed
);
3102 /* Make sure we don't report a SIGINT that we have already displayed
3103 for another thread. */
3104 if (lp
->ignore_sigint
3105 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGINT
)
3107 if (debug_linux_nat
)
3108 fprintf_unfiltered (gdb_stdlog
,
3109 "LLW: Delayed SIGINT caught for %s.\n",
3110 target_pid_to_str (lp
->ptid
).c_str ());
3112 /* This is a delayed SIGINT. */
3113 lp
->ignore_sigint
= 0;
3115 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
3116 if (debug_linux_nat
)
3117 fprintf_unfiltered (gdb_stdlog
,
3118 "LLW: %s %s, 0, 0 (discard SIGINT)\n",
3120 "PTRACE_SINGLESTEP" : "PTRACE_CONT",
3121 target_pid_to_str (lp
->ptid
).c_str ());
3122 gdb_assert (lp
->resumed
);
3124 /* Discard the event. */
3128 /* Don't report signals that GDB isn't interested in, such as
3129 signals that are neither printed nor stopped upon. Stopping all
3130 threads can be a bit time-consuming, so if we want decent
3131 performance with heavily multi-threaded programs, especially when
3132 they're using a high frequency timer, we'd better avoid it if we
3134 if (WIFSTOPPED (status
))
3136 enum gdb_signal signo
= gdb_signal_from_host (WSTOPSIG (status
));
3138 if (!target_is_non_stop_p ())
3140 /* Only do the below in all-stop, as we currently use SIGSTOP
3141 to implement target_stop (see linux_nat_stop) in
3143 if (signo
== GDB_SIGNAL_INT
&& signal_pass_state (signo
) == 0)
3145 /* If ^C/BREAK is typed at the tty/console, SIGINT gets
3146 forwarded to the entire process group, that is, all LWPs
3147 will receive it - unless they're using CLONE_THREAD to
3148 share signals. Since we only want to report it once, we
3149 mark it as ignored for all LWPs except this one. */
3150 iterate_over_lwps (ptid_t (lp
->ptid
.pid ()), set_ignore_sigint
);
3151 lp
->ignore_sigint
= 0;
3154 maybe_clear_ignore_sigint (lp
);
3157 /* When using hardware single-step, we need to report every signal.
3158 Otherwise, signals in pass_mask may be short-circuited
3159 except signals that might be caused by a breakpoint, or SIGSTOP
3160 if we sent the SIGSTOP and are waiting for it to arrive. */
3162 && WSTOPSIG (status
) && sigismember (&pass_mask
, WSTOPSIG (status
))
3163 && (WSTOPSIG (status
) != SIGSTOP
3164 || !find_thread_ptid (linux_target
, lp
->ptid
)->stop_requested
)
3165 && !linux_wstatus_maybe_breakpoint (status
))
3167 linux_resume_one_lwp (lp
, lp
->step
, signo
);
3168 if (debug_linux_nat
)
3169 fprintf_unfiltered (gdb_stdlog
,
3170 "LLW: %s %s, %s (preempt 'handle')\n",
3172 "PTRACE_SINGLESTEP" : "PTRACE_CONT",
3173 target_pid_to_str (lp
->ptid
).c_str (),
3174 (signo
!= GDB_SIGNAL_0
3175 ? strsignal (gdb_signal_to_host (signo
))
3181 /* An interesting event. */
3183 lp
->status
= status
;
3184 save_stop_reason (lp
);
3188 /* Detect zombie thread group leaders, and "exit" them. We can't reap
3189 their exits until all other threads in the group have exited. */
3192 check_zombie_leaders (void)
3194 for (inferior
*inf
: all_inferiors ())
3196 struct lwp_info
*leader_lp
;
3201 leader_lp
= find_lwp_pid (ptid_t (inf
->pid
));
3202 if (leader_lp
!= NULL
3203 /* Check if there are other threads in the group, as we may
3204 have raced with the inferior simply exiting. */
3205 && num_lwps (inf
->pid
) > 1
3206 && linux_proc_pid_is_zombie (inf
->pid
))
3208 if (debug_linux_nat
)
3209 fprintf_unfiltered (gdb_stdlog
,
3210 "CZL: Thread group leader %d zombie "
3211 "(it exited, or another thread execd).\n",
3214 /* A leader zombie can mean one of two things:
3216 - It exited, and there's an exit status pending
3217 available, or only the leader exited (not the whole
3218 program). In the latter case, we can't waitpid the
3219 leader's exit status until all other threads are gone.
3221 - There are 3 or more threads in the group, and a thread
3222 other than the leader exec'd. See comments on exec
3223 events at the top of the file. We could try
3224 distinguishing the exit and exec cases, by waiting once
3225 more, and seeing if something comes out, but it doesn't
3226 sound useful. The previous leader _does_ go away, and
3227 we'll re-add the new one once we see the exec event
3228 (which is just the same as what would happen if the
3229 previous leader did exit voluntarily before some other
3232 if (debug_linux_nat
)
3233 fprintf_unfiltered (gdb_stdlog
,
3234 "CZL: Thread group leader %d vanished.\n",
3236 exit_lwp (leader_lp
);
3241 /* Convenience function that is called when the kernel reports an exit
3242 event. This decides whether to report the event to GDB as a
3243 process exit event, a thread exit event, or to suppress the
3247 filter_exit_event (struct lwp_info
*event_child
,
3248 struct target_waitstatus
*ourstatus
)
3250 ptid_t ptid
= event_child
->ptid
;
3252 if (num_lwps (ptid
.pid ()) > 1)
3254 if (report_thread_events
)
3255 ourstatus
->kind
= TARGET_WAITKIND_THREAD_EXITED
;
3257 ourstatus
->kind
= TARGET_WAITKIND_IGNORE
;
3259 exit_lwp (event_child
);
3266 linux_nat_wait_1 (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3270 enum resume_kind last_resume_kind
;
3271 struct lwp_info
*lp
;
3274 if (debug_linux_nat
)
3275 fprintf_unfiltered (gdb_stdlog
, "LLW: enter\n");
3277 /* The first time we get here after starting a new inferior, we may
3278 not have added it to the LWP list yet - this is the earliest
3279 moment at which we know its PID. */
3280 if (inferior_ptid
.is_pid ())
3282 /* Upgrade the main thread's ptid. */
3283 thread_change_ptid (linux_target
, inferior_ptid
,
3284 ptid_t (inferior_ptid
.pid (),
3285 inferior_ptid
.pid (), 0));
3287 lp
= add_initial_lwp (inferior_ptid
);
3291 /* Make sure SIGCHLD is blocked until the sigsuspend below. */
3292 block_child_signals (&prev_mask
);
3294 /* First check if there is a LWP with a wait status pending. */
3295 lp
= iterate_over_lwps (ptid
, status_callback
);
3298 if (debug_linux_nat
)
3299 fprintf_unfiltered (gdb_stdlog
,
3300 "LLW: Using pending wait status %s for %s.\n",
3301 status_to_str (lp
->status
),
3302 target_pid_to_str (lp
->ptid
).c_str ());
3305 /* But if we don't find a pending event, we'll have to wait. Always
3306 pull all events out of the kernel. We'll randomly select an
3307 event LWP out of all that have events, to prevent starvation. */
3313 /* Always use -1 and WNOHANG, due to couple of a kernel/ptrace
3316 - If the thread group leader exits while other threads in the
3317 thread group still exist, waitpid(TGID, ...) hangs. That
3318 waitpid won't return an exit status until the other threads
3319 in the group are reaped.
3321 - When a non-leader thread execs, that thread just vanishes
3322 without reporting an exit (so we'd hang if we waited for it
3323 explicitly in that case). The exec event is reported to
3327 lwpid
= my_waitpid (-1, &status
, __WALL
| WNOHANG
);
3329 if (debug_linux_nat
)
3330 fprintf_unfiltered (gdb_stdlog
,
3331 "LNW: waitpid(-1, ...) returned %d, %s\n",
3332 lwpid
, errno
? safe_strerror (errno
) : "ERRNO-OK");
3336 if (debug_linux_nat
)
3338 fprintf_unfiltered (gdb_stdlog
,
3339 "LLW: waitpid %ld received %s\n",
3340 (long) lwpid
, status_to_str (status
));
3343 linux_nat_filter_event (lwpid
, status
);
3344 /* Retry until nothing comes out of waitpid. A single
3345 SIGCHLD can indicate more than one child stopped. */
3349 /* Now that we've pulled all events out of the kernel, resume
3350 LWPs that don't have an interesting event to report. */
3351 iterate_over_lwps (minus_one_ptid
,
3352 [] (struct lwp_info
*info
)
3354 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
3357 /* ... and find an LWP with a status to report to the core, if
3359 lp
= iterate_over_lwps (ptid
, status_callback
);
3363 /* Check for zombie thread group leaders. Those can't be reaped
3364 until all other threads in the thread group are. */
3365 check_zombie_leaders ();
3367 /* If there are no resumed children left, bail. We'd be stuck
3368 forever in the sigsuspend call below otherwise. */
3369 if (iterate_over_lwps (ptid
, resumed_callback
) == NULL
)
3371 if (debug_linux_nat
)
3372 fprintf_unfiltered (gdb_stdlog
, "LLW: exit (no resumed LWP)\n");
3374 ourstatus
->kind
= TARGET_WAITKIND_NO_RESUMED
;
3376 restore_child_signals_mask (&prev_mask
);
3377 return minus_one_ptid
;
3380 /* No interesting event to report to the core. */
3382 if (target_options
& TARGET_WNOHANG
)
3384 if (debug_linux_nat
)
3385 fprintf_unfiltered (gdb_stdlog
, "LLW: exit (ignore)\n");
3387 ourstatus
->kind
= TARGET_WAITKIND_IGNORE
;
3388 restore_child_signals_mask (&prev_mask
);
3389 return minus_one_ptid
;
3392 /* We shouldn't end up here unless we want to try again. */
3393 gdb_assert (lp
== NULL
);
3395 /* Block until we get an event reported with SIGCHLD. */
3401 status
= lp
->status
;
3404 if (!target_is_non_stop_p ())
3406 /* Now stop all other LWP's ... */
3407 iterate_over_lwps (minus_one_ptid
, stop_callback
);
3409 /* ... and wait until all of them have reported back that
3410 they're no longer running. */
3411 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
3414 /* If we're not waiting for a specific LWP, choose an event LWP from
3415 among those that have had events. Giving equal priority to all
3416 LWPs that have had events helps prevent starvation. */
3417 if (ptid
== minus_one_ptid
|| ptid
.is_pid ())
3418 select_event_lwp (ptid
, &lp
, &status
);
3420 gdb_assert (lp
!= NULL
);
3422 /* Now that we've selected our final event LWP, un-adjust its PC if
3423 it was a software breakpoint, and we can't reliably support the
3424 "stopped by software breakpoint" stop reason. */
3425 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
3426 && !USE_SIGTRAP_SIGINFO
)
3428 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3429 struct gdbarch
*gdbarch
= regcache
->arch ();
3430 int decr_pc
= gdbarch_decr_pc_after_break (gdbarch
);
3436 pc
= regcache_read_pc (regcache
);
3437 regcache_write_pc (regcache
, pc
+ decr_pc
);
3441 /* We'll need this to determine whether to report a SIGSTOP as
3442 GDB_SIGNAL_0. Need to take a copy because resume_clear_callback
3444 last_resume_kind
= lp
->last_resume_kind
;
3446 if (!target_is_non_stop_p ())
3448 /* In all-stop, from the core's perspective, all LWPs are now
3449 stopped until a new resume action is sent over. */
3450 iterate_over_lwps (minus_one_ptid
, resume_clear_callback
);
3454 resume_clear_callback (lp
);
3457 if (linux_target
->low_status_is_event (status
))
3459 if (debug_linux_nat
)
3460 fprintf_unfiltered (gdb_stdlog
,
3461 "LLW: trap ptid is %s.\n",
3462 target_pid_to_str (lp
->ptid
).c_str ());
3465 if (lp
->waitstatus
.kind
!= TARGET_WAITKIND_IGNORE
)
3467 *ourstatus
= lp
->waitstatus
;
3468 lp
->waitstatus
.kind
= TARGET_WAITKIND_IGNORE
;
3471 store_waitstatus (ourstatus
, status
);
3473 if (debug_linux_nat
)
3474 fprintf_unfiltered (gdb_stdlog
, "LLW: exit\n");
3476 restore_child_signals_mask (&prev_mask
);
3478 if (last_resume_kind
== resume_stop
3479 && ourstatus
->kind
== TARGET_WAITKIND_STOPPED
3480 && WSTOPSIG (status
) == SIGSTOP
)
3482 /* A thread that has been requested to stop by GDB with
3483 target_stop, and it stopped cleanly, so report as SIG0. The
3484 use of SIGSTOP is an implementation detail. */
3485 ourstatus
->value
.sig
= GDB_SIGNAL_0
;
3488 if (ourstatus
->kind
== TARGET_WAITKIND_EXITED
3489 || ourstatus
->kind
== TARGET_WAITKIND_SIGNALLED
)
3492 lp
->core
= linux_common_core_of_thread (lp
->ptid
);
3494 if (ourstatus
->kind
== TARGET_WAITKIND_EXITED
)
3495 return filter_exit_event (lp
, ourstatus
);
3500 /* Resume LWPs that are currently stopped without any pending status
3501 to report, but are resumed from the core's perspective. */
3504 resume_stopped_resumed_lwps (struct lwp_info
*lp
, const ptid_t wait_ptid
)
3508 if (debug_linux_nat
)
3509 fprintf_unfiltered (gdb_stdlog
,
3510 "RSRL: NOT resuming LWP %s, not stopped\n",
3511 target_pid_to_str (lp
->ptid
).c_str ());
3513 else if (!lp
->resumed
)
3515 if (debug_linux_nat
)
3516 fprintf_unfiltered (gdb_stdlog
,
3517 "RSRL: NOT resuming LWP %s, not resumed\n",
3518 target_pid_to_str (lp
->ptid
).c_str ());
3520 else if (lwp_status_pending_p (lp
))
3522 if (debug_linux_nat
)
3523 fprintf_unfiltered (gdb_stdlog
,
3524 "RSRL: NOT resuming LWP %s, has pending status\n",
3525 target_pid_to_str (lp
->ptid
).c_str ());
3529 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3530 struct gdbarch
*gdbarch
= regcache
->arch ();
3534 CORE_ADDR pc
= regcache_read_pc (regcache
);
3535 int leave_stopped
= 0;
3537 /* Don't bother if there's a breakpoint at PC that we'd hit
3538 immediately, and we're not waiting for this LWP. */
3539 if (!lp
->ptid
.matches (wait_ptid
))
3541 if (breakpoint_inserted_here_p (regcache
->aspace (), pc
))
3547 if (debug_linux_nat
)
3548 fprintf_unfiltered (gdb_stdlog
,
3549 "RSRL: resuming stopped-resumed LWP %s at "
3551 target_pid_to_str (lp
->ptid
).c_str (),
3552 paddress (gdbarch
, pc
),
3555 linux_resume_one_lwp_throw (lp
, lp
->step
, GDB_SIGNAL_0
);
3558 catch (const gdb_exception_error
&ex
)
3560 if (!check_ptrace_stopped_lwp_gone (lp
))
3569 linux_nat_target::wait (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3574 if (debug_linux_nat
)
3576 std::string options_string
= target_options_to_string (target_options
);
3577 fprintf_unfiltered (gdb_stdlog
,
3578 "linux_nat_wait: [%s], [%s]\n",
3579 target_pid_to_str (ptid
).c_str (),
3580 options_string
.c_str ());
3583 /* Flush the async file first. */
3584 if (target_is_async_p ())
3585 async_file_flush ();
3587 /* Resume LWPs that are currently stopped without any pending status
3588 to report, but are resumed from the core's perspective. LWPs get
3589 in this state if we find them stopping at a time we're not
3590 interested in reporting the event (target_wait on a
3591 specific_process, for example, see linux_nat_wait_1), and
3592 meanwhile the event became uninteresting. Don't bother resuming
3593 LWPs we're not going to wait for if they'd stop immediately. */
3594 if (target_is_non_stop_p ())
3595 iterate_over_lwps (minus_one_ptid
,
3596 [=] (struct lwp_info
*info
)
3598 return resume_stopped_resumed_lwps (info
, ptid
);
3601 event_ptid
= linux_nat_wait_1 (ptid
, ourstatus
, target_options
);
3603 /* If we requested any event, and something came out, assume there
3604 may be more. If we requested a specific lwp or process, also
3605 assume there may be more. */
3606 if (target_is_async_p ()
3607 && ((ourstatus
->kind
!= TARGET_WAITKIND_IGNORE
3608 && ourstatus
->kind
!= TARGET_WAITKIND_NO_RESUMED
)
3609 || ptid
!= minus_one_ptid
))
3618 kill_one_lwp (pid_t pid
)
3620 /* PTRACE_KILL may resume the inferior. Send SIGKILL first. */
3623 kill_lwp (pid
, SIGKILL
);
3624 if (debug_linux_nat
)
3626 int save_errno
= errno
;
3628 fprintf_unfiltered (gdb_stdlog
,
3629 "KC: kill (SIGKILL) %ld, 0, 0 (%s)\n", (long) pid
,
3630 save_errno
? safe_strerror (save_errno
) : "OK");
3633 /* Some kernels ignore even SIGKILL for processes under ptrace. */
3636 ptrace (PTRACE_KILL
, pid
, 0, 0);
3637 if (debug_linux_nat
)
3639 int save_errno
= errno
;
3641 fprintf_unfiltered (gdb_stdlog
,
3642 "KC: PTRACE_KILL %ld, 0, 0 (%s)\n", (long) pid
,
3643 save_errno
? safe_strerror (save_errno
) : "OK");
3647 /* Wait for an LWP to die. */
3650 kill_wait_one_lwp (pid_t pid
)
3654 /* We must make sure that there are no pending events (delayed
3655 SIGSTOPs, pending SIGTRAPs, etc.) to make sure the current
3656 program doesn't interfere with any following debugging session. */
3660 res
= my_waitpid (pid
, NULL
, __WALL
);
3661 if (res
!= (pid_t
) -1)
3663 if (debug_linux_nat
)
3664 fprintf_unfiltered (gdb_stdlog
,
3665 "KWC: wait %ld received unknown.\n",
3667 /* The Linux kernel sometimes fails to kill a thread
3668 completely after PTRACE_KILL; that goes from the stop
3669 point in do_fork out to the one in get_signal_to_deliver
3670 and waits again. So kill it again. */
3676 gdb_assert (res
== -1 && errno
== ECHILD
);
3679 /* Callback for iterate_over_lwps. */
3682 kill_callback (struct lwp_info
*lp
)
3684 kill_one_lwp (lp
->ptid
.lwp ());
3688 /* Callback for iterate_over_lwps. */
3691 kill_wait_callback (struct lwp_info
*lp
)
3693 kill_wait_one_lwp (lp
->ptid
.lwp ());
3697 /* Kill the fork children of any threads of inferior INF that are
3698 stopped at a fork event. */
3701 kill_unfollowed_fork_children (struct inferior
*inf
)
3703 for (thread_info
*thread
: inf
->non_exited_threads ())
3705 struct target_waitstatus
*ws
= &thread
->pending_follow
;
3707 if (ws
->kind
== TARGET_WAITKIND_FORKED
3708 || ws
->kind
== TARGET_WAITKIND_VFORKED
)
3710 ptid_t child_ptid
= ws
->value
.related_pid
;
3711 int child_pid
= child_ptid
.pid ();
3712 int child_lwp
= child_ptid
.lwp ();
3714 kill_one_lwp (child_lwp
);
3715 kill_wait_one_lwp (child_lwp
);
3717 /* Let the arch-specific native code know this process is
3719 linux_target
->low_forget_process (child_pid
);
3725 linux_nat_target::kill ()
3727 /* If we're stopped while forking and we haven't followed yet,
3728 kill the other task. We need to do this first because the
3729 parent will be sleeping if this is a vfork. */
3730 kill_unfollowed_fork_children (current_inferior ());
3732 if (forks_exist_p ())
3733 linux_fork_killall ();
3736 ptid_t ptid
= ptid_t (inferior_ptid
.pid ());
3738 /* Stop all threads before killing them, since ptrace requires
3739 that the thread is stopped to successfully PTRACE_KILL. */
3740 iterate_over_lwps (ptid
, stop_callback
);
3741 /* ... and wait until all of them have reported back that
3742 they're no longer running. */
3743 iterate_over_lwps (ptid
, stop_wait_callback
);
3745 /* Kill all LWP's ... */
3746 iterate_over_lwps (ptid
, kill_callback
);
3748 /* ... and wait until we've flushed all events. */
3749 iterate_over_lwps (ptid
, kill_wait_callback
);
3752 target_mourn_inferior (inferior_ptid
);
3756 linux_nat_target::mourn_inferior ()
3758 int pid
= inferior_ptid
.pid ();
3760 purge_lwp_list (pid
);
3762 if (! forks_exist_p ())
3763 /* Normal case, no other forks available. */
3764 inf_ptrace_target::mourn_inferior ();
3766 /* Multi-fork case. The current inferior_ptid has exited, but
3767 there are other viable forks to debug. Delete the exiting
3768 one and context-switch to the first available. */
3769 linux_fork_mourn_inferior ();
3771 /* Let the arch-specific native code know this process is gone. */
3772 linux_target
->low_forget_process (pid
);
3775 /* Convert a native/host siginfo object, into/from the siginfo in the
3776 layout of the inferiors' architecture. */
3779 siginfo_fixup (siginfo_t
*siginfo
, gdb_byte
*inf_siginfo
, int direction
)
3781 /* If the low target didn't do anything, then just do a straight
3783 if (!linux_target
->low_siginfo_fixup (siginfo
, inf_siginfo
, direction
))
3786 memcpy (siginfo
, inf_siginfo
, sizeof (siginfo_t
));
3788 memcpy (inf_siginfo
, siginfo
, sizeof (siginfo_t
));
3792 static enum target_xfer_status
3793 linux_xfer_siginfo (enum target_object object
,
3794 const char *annex
, gdb_byte
*readbuf
,
3795 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3796 ULONGEST
*xfered_len
)
3800 gdb_byte inf_siginfo
[sizeof (siginfo_t
)];
3802 gdb_assert (object
== TARGET_OBJECT_SIGNAL_INFO
);
3803 gdb_assert (readbuf
|| writebuf
);
3805 pid
= inferior_ptid
.lwp ();
3807 pid
= inferior_ptid
.pid ();
3809 if (offset
> sizeof (siginfo
))
3810 return TARGET_XFER_E_IO
;
3813 ptrace (PTRACE_GETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, &siginfo
);
3815 return TARGET_XFER_E_IO
;
3817 /* When GDB is built as a 64-bit application, ptrace writes into
3818 SIGINFO an object with 64-bit layout. Since debugging a 32-bit
3819 inferior with a 64-bit GDB should look the same as debugging it
3820 with a 32-bit GDB, we need to convert it. GDB core always sees
3821 the converted layout, so any read/write will have to be done
3823 siginfo_fixup (&siginfo
, inf_siginfo
, 0);
3825 if (offset
+ len
> sizeof (siginfo
))
3826 len
= sizeof (siginfo
) - offset
;
3828 if (readbuf
!= NULL
)
3829 memcpy (readbuf
, inf_siginfo
+ offset
, len
);
3832 memcpy (inf_siginfo
+ offset
, writebuf
, len
);
3834 /* Convert back to ptrace layout before flushing it out. */
3835 siginfo_fixup (&siginfo
, inf_siginfo
, 1);
3838 ptrace (PTRACE_SETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, &siginfo
);
3840 return TARGET_XFER_E_IO
;
3844 return TARGET_XFER_OK
;
3847 static enum target_xfer_status
3848 linux_nat_xfer_osdata (enum target_object object
,
3849 const char *annex
, gdb_byte
*readbuf
,
3850 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3851 ULONGEST
*xfered_len
);
3853 static enum target_xfer_status
3854 linux_proc_xfer_partial (enum target_object object
,
3855 const char *annex
, gdb_byte
*readbuf
,
3856 const gdb_byte
*writebuf
,
3857 ULONGEST offset
, LONGEST len
, ULONGEST
*xfered_len
);
3859 enum target_xfer_status
3860 linux_nat_target::xfer_partial (enum target_object object
,
3861 const char *annex
, gdb_byte
*readbuf
,
3862 const gdb_byte
*writebuf
,
3863 ULONGEST offset
, ULONGEST len
, ULONGEST
*xfered_len
)
3865 enum target_xfer_status xfer
;
3867 if (object
== TARGET_OBJECT_SIGNAL_INFO
)
3868 return linux_xfer_siginfo (object
, annex
, readbuf
, writebuf
,
3869 offset
, len
, xfered_len
);
3871 /* The target is connected but no live inferior is selected. Pass
3872 this request down to a lower stratum (e.g., the executable
3874 if (object
== TARGET_OBJECT_MEMORY
&& inferior_ptid
== null_ptid
)
3875 return TARGET_XFER_EOF
;
3877 if (object
== TARGET_OBJECT_AUXV
)
3878 return memory_xfer_auxv (this, object
, annex
, readbuf
, writebuf
,
3879 offset
, len
, xfered_len
);
3881 if (object
== TARGET_OBJECT_OSDATA
)
3882 return linux_nat_xfer_osdata (object
, annex
, readbuf
, writebuf
,
3883 offset
, len
, xfered_len
);
3885 /* GDB calculates all addresses in the largest possible address
3887 The address width must be masked before its final use - either by
3888 linux_proc_xfer_partial or inf_ptrace_target::xfer_partial.
3890 Compare ADDR_BIT first to avoid a compiler warning on shift overflow. */
3892 if (object
== TARGET_OBJECT_MEMORY
)
3894 int addr_bit
= gdbarch_addr_bit (target_gdbarch ());
3896 if (addr_bit
< (sizeof (ULONGEST
) * HOST_CHAR_BIT
))
3897 offset
&= ((ULONGEST
) 1 << addr_bit
) - 1;
3900 xfer
= linux_proc_xfer_partial (object
, annex
, readbuf
, writebuf
,
3901 offset
, len
, xfered_len
);
3902 if (xfer
!= TARGET_XFER_EOF
)
3905 return inf_ptrace_target::xfer_partial (object
, annex
, readbuf
, writebuf
,
3906 offset
, len
, xfered_len
);
3910 linux_nat_target::thread_alive (ptid_t ptid
)
3912 /* As long as a PTID is in lwp list, consider it alive. */
3913 return find_lwp_pid (ptid
) != NULL
;
3916 /* Implement the to_update_thread_list target method for this
3920 linux_nat_target::update_thread_list ()
3922 struct lwp_info
*lwp
;
3924 /* We add/delete threads from the list as clone/exit events are
3925 processed, so just try deleting exited threads still in the
3927 delete_exited_threads ();
3929 /* Update the processor core that each lwp/thread was last seen
3933 /* Avoid accessing /proc if the thread hasn't run since we last
3934 time we fetched the thread's core. Accessing /proc becomes
3935 noticeably expensive when we have thousands of LWPs. */
3936 if (lwp
->core
== -1)
3937 lwp
->core
= linux_common_core_of_thread (lwp
->ptid
);
3942 linux_nat_target::pid_to_str (ptid_t ptid
)
3945 && (ptid
.pid () != ptid
.lwp ()
3946 || num_lwps (ptid
.pid ()) > 1))
3947 return string_printf ("LWP %ld", ptid
.lwp ());
3949 return normal_pid_to_str (ptid
);
3953 linux_nat_target::thread_name (struct thread_info
*thr
)
3955 return linux_proc_tid_get_name (thr
->ptid
);
3958 /* Accepts an integer PID; Returns a string representing a file that
3959 can be opened to get the symbols for the child process. */
3962 linux_nat_target::pid_to_exec_file (int pid
)
3964 return linux_proc_pid_to_exec_file (pid
);
3967 /* Implement the to_xfer_partial target method using /proc/<pid>/mem.
3968 Because we can use a single read/write call, this can be much more
3969 efficient than banging away at PTRACE_PEEKTEXT. */
3971 static enum target_xfer_status
3972 linux_proc_xfer_partial (enum target_object object
,
3973 const char *annex
, gdb_byte
*readbuf
,
3974 const gdb_byte
*writebuf
,
3975 ULONGEST offset
, LONGEST len
, ULONGEST
*xfered_len
)
3981 if (object
!= TARGET_OBJECT_MEMORY
)
3982 return TARGET_XFER_EOF
;
3984 /* Don't bother for one word. */
3985 if (len
< 3 * sizeof (long))
3986 return TARGET_XFER_EOF
;
3988 /* We could keep this file open and cache it - possibly one per
3989 thread. That requires some juggling, but is even faster. */
3990 xsnprintf (filename
, sizeof filename
, "/proc/%ld/mem",
3991 inferior_ptid
.lwp ());
3992 fd
= gdb_open_cloexec (filename
, ((readbuf
? O_RDONLY
: O_WRONLY
)
3995 return TARGET_XFER_EOF
;
3997 /* Use pread64/pwrite64 if available, since they save a syscall and can
3998 handle 64-bit offsets even on 32-bit platforms (for instance, SPARC
3999 debugging a SPARC64 application). */
4001 ret
= (readbuf
? pread64 (fd
, readbuf
, len
, offset
)
4002 : pwrite64 (fd
, writebuf
, len
, offset
));
4004 ret
= lseek (fd
, offset
, SEEK_SET
);
4006 ret
= (readbuf
? read (fd
, readbuf
, len
)
4007 : write (fd
, writebuf
, len
));
4012 if (ret
== -1 || ret
== 0)
4013 return TARGET_XFER_EOF
;
4017 return TARGET_XFER_OK
;
4022 /* Parse LINE as a signal set and add its set bits to SIGS. */
4025 add_line_to_sigset (const char *line
, sigset_t
*sigs
)
4027 int len
= strlen (line
) - 1;
4031 if (line
[len
] != '\n')
4032 error (_("Could not parse signal set: %s"), line
);
4040 if (*p
>= '0' && *p
<= '9')
4042 else if (*p
>= 'a' && *p
<= 'f')
4043 digit
= *p
- 'a' + 10;
4045 error (_("Could not parse signal set: %s"), line
);
4050 sigaddset (sigs
, signum
+ 1);
4052 sigaddset (sigs
, signum
+ 2);
4054 sigaddset (sigs
, signum
+ 3);
4056 sigaddset (sigs
, signum
+ 4);
4062 /* Find process PID's pending signals from /proc/pid/status and set
4066 linux_proc_pending_signals (int pid
, sigset_t
*pending
,
4067 sigset_t
*blocked
, sigset_t
*ignored
)
4069 char buffer
[PATH_MAX
], fname
[PATH_MAX
];
4071 sigemptyset (pending
);
4072 sigemptyset (blocked
);
4073 sigemptyset (ignored
);
4074 xsnprintf (fname
, sizeof fname
, "/proc/%d/status", pid
);
4075 gdb_file_up procfile
= gdb_fopen_cloexec (fname
, "r");
4076 if (procfile
== NULL
)
4077 error (_("Could not open %s"), fname
);
4079 while (fgets (buffer
, PATH_MAX
, procfile
.get ()) != NULL
)
4081 /* Normal queued signals are on the SigPnd line in the status
4082 file. However, 2.6 kernels also have a "shared" pending
4083 queue for delivering signals to a thread group, so check for
4086 Unfortunately some Red Hat kernels include the shared pending
4087 queue but not the ShdPnd status field. */
4089 if (startswith (buffer
, "SigPnd:\t"))
4090 add_line_to_sigset (buffer
+ 8, pending
);
4091 else if (startswith (buffer
, "ShdPnd:\t"))
4092 add_line_to_sigset (buffer
+ 8, pending
);
4093 else if (startswith (buffer
, "SigBlk:\t"))
4094 add_line_to_sigset (buffer
+ 8, blocked
);
4095 else if (startswith (buffer
, "SigIgn:\t"))
4096 add_line_to_sigset (buffer
+ 8, ignored
);
4100 static enum target_xfer_status
4101 linux_nat_xfer_osdata (enum target_object object
,
4102 const char *annex
, gdb_byte
*readbuf
,
4103 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
4104 ULONGEST
*xfered_len
)
4106 gdb_assert (object
== TARGET_OBJECT_OSDATA
);
4108 *xfered_len
= linux_common_xfer_osdata (annex
, readbuf
, offset
, len
);
4109 if (*xfered_len
== 0)
4110 return TARGET_XFER_EOF
;
4112 return TARGET_XFER_OK
;
4115 std::vector
<static_tracepoint_marker
>
4116 linux_nat_target::static_tracepoint_markers_by_strid (const char *strid
)
4118 char s
[IPA_CMD_BUF_SIZE
];
4119 int pid
= inferior_ptid
.pid ();
4120 std::vector
<static_tracepoint_marker
> markers
;
4122 ptid_t ptid
= ptid_t (pid
, 0, 0);
4123 static_tracepoint_marker marker
;
4128 memcpy (s
, "qTfSTM", sizeof ("qTfSTM"));
4129 s
[sizeof ("qTfSTM")] = 0;
4131 agent_run_command (pid
, s
, strlen (s
) + 1);
4134 SCOPE_EXIT
{ target_continue_no_signal (ptid
); };
4140 parse_static_tracepoint_marker_definition (p
, &p
, &marker
);
4142 if (strid
== NULL
|| marker
.str_id
== strid
)
4143 markers
.push_back (std::move (marker
));
4145 while (*p
++ == ','); /* comma-separated list */
4147 memcpy (s
, "qTsSTM", sizeof ("qTsSTM"));
4148 s
[sizeof ("qTsSTM")] = 0;
4149 agent_run_command (pid
, s
, strlen (s
) + 1);
4156 /* target_is_async_p implementation. */
4159 linux_nat_target::is_async_p ()
4161 return linux_is_async_p ();
4164 /* target_can_async_p implementation. */
4167 linux_nat_target::can_async_p ()
4169 /* We're always async, unless the user explicitly prevented it with the
4170 "maint set target-async" command. */
4171 return target_async_permitted
;
4175 linux_nat_target::supports_non_stop ()
4180 /* to_always_non_stop_p implementation. */
4183 linux_nat_target::always_non_stop_p ()
4188 /* True if we want to support multi-process. To be removed when GDB
4189 supports multi-exec. */
4191 int linux_multi_process
= 1;
4194 linux_nat_target::supports_multi_process ()
4196 return linux_multi_process
;
4200 linux_nat_target::supports_disable_randomization ()
4202 #ifdef HAVE_PERSONALITY
4209 /* SIGCHLD handler that serves two purposes: In non-stop/async mode,
4210 so we notice when any child changes state, and notify the
4211 event-loop; it allows us to use sigsuspend in linux_nat_wait_1
4212 above to wait for the arrival of a SIGCHLD. */
4215 sigchld_handler (int signo
)
4217 int old_errno
= errno
;
4219 if (debug_linux_nat
)
4220 gdb_stdlog
->write_async_safe ("sigchld\n", sizeof ("sigchld\n") - 1);
4222 if (signo
== SIGCHLD
4223 && linux_nat_event_pipe
[0] != -1)
4224 async_file_mark (); /* Let the event loop know that there are
4225 events to handle. */
4230 /* Callback registered with the target events file descriptor. */
4233 handle_target_event (int error
, gdb_client_data client_data
)
4235 inferior_event_handler (INF_REG_EVENT
, NULL
);
4238 /* Create/destroy the target events pipe. Returns previous state. */
4241 linux_async_pipe (int enable
)
4243 int previous
= linux_is_async_p ();
4245 if (previous
!= enable
)
4249 /* Block child signals while we create/destroy the pipe, as
4250 their handler writes to it. */
4251 block_child_signals (&prev_mask
);
4255 if (gdb_pipe_cloexec (linux_nat_event_pipe
) == -1)
4256 internal_error (__FILE__
, __LINE__
,
4257 "creating event pipe failed.");
4259 fcntl (linux_nat_event_pipe
[0], F_SETFL
, O_NONBLOCK
);
4260 fcntl (linux_nat_event_pipe
[1], F_SETFL
, O_NONBLOCK
);
4264 close (linux_nat_event_pipe
[0]);
4265 close (linux_nat_event_pipe
[1]);
4266 linux_nat_event_pipe
[0] = -1;
4267 linux_nat_event_pipe
[1] = -1;
4270 restore_child_signals_mask (&prev_mask
);
4277 linux_nat_target::async_wait_fd ()
4279 return linux_nat_event_pipe
[0];
4282 /* target_async implementation. */
4285 linux_nat_target::async (int enable
)
4289 if (!linux_async_pipe (1))
4291 add_file_handler (linux_nat_event_pipe
[0],
4292 handle_target_event
, NULL
);
4293 /* There may be pending events to handle. Tell the event loop
4300 delete_file_handler (linux_nat_event_pipe
[0]);
4301 linux_async_pipe (0);
4306 /* Stop an LWP, and push a GDB_SIGNAL_0 stop status if no other
4310 linux_nat_stop_lwp (struct lwp_info
*lwp
)
4314 if (debug_linux_nat
)
4315 fprintf_unfiltered (gdb_stdlog
,
4316 "LNSL: running -> suspending %s\n",
4317 target_pid_to_str (lwp
->ptid
).c_str ());
4320 if (lwp
->last_resume_kind
== resume_stop
)
4322 if (debug_linux_nat
)
4323 fprintf_unfiltered (gdb_stdlog
,
4324 "linux-nat: already stopping LWP %ld at "
4330 stop_callback (lwp
);
4331 lwp
->last_resume_kind
= resume_stop
;
4335 /* Already known to be stopped; do nothing. */
4337 if (debug_linux_nat
)
4339 if (find_thread_ptid (linux_target
, lwp
->ptid
)->stop_requested
)
4340 fprintf_unfiltered (gdb_stdlog
,
4341 "LNSL: already stopped/stop_requested %s\n",
4342 target_pid_to_str (lwp
->ptid
).c_str ());
4344 fprintf_unfiltered (gdb_stdlog
,
4345 "LNSL: already stopped/no "
4346 "stop_requested yet %s\n",
4347 target_pid_to_str (lwp
->ptid
).c_str ());
4354 linux_nat_target::stop (ptid_t ptid
)
4356 iterate_over_lwps (ptid
, linux_nat_stop_lwp
);
4360 linux_nat_target::close ()
4362 /* Unregister from the event loop. */
4366 inf_ptrace_target::close ();
4369 /* When requests are passed down from the linux-nat layer to the
4370 single threaded inf-ptrace layer, ptids of (lwpid,0,0) form are
4371 used. The address space pointer is stored in the inferior object,
4372 but the common code that is passed such ptid can't tell whether
4373 lwpid is a "main" process id or not (it assumes so). We reverse
4374 look up the "main" process id from the lwp here. */
4376 struct address_space
*
4377 linux_nat_target::thread_address_space (ptid_t ptid
)
4379 struct lwp_info
*lwp
;
4380 struct inferior
*inf
;
4383 if (ptid
.lwp () == 0)
4385 /* An (lwpid,0,0) ptid. Look up the lwp object to get at the
4387 lwp
= find_lwp_pid (ptid
);
4388 pid
= lwp
->ptid
.pid ();
4392 /* A (pid,lwpid,0) ptid. */
4396 inf
= find_inferior_pid (this, pid
);
4397 gdb_assert (inf
!= NULL
);
4401 /* Return the cached value of the processor core for thread PTID. */
4404 linux_nat_target::core_of_thread (ptid_t ptid
)
4406 struct lwp_info
*info
= find_lwp_pid (ptid
);
4413 /* Implementation of to_filesystem_is_local. */
4416 linux_nat_target::filesystem_is_local ()
4418 struct inferior
*inf
= current_inferior ();
4420 if (inf
->fake_pid_p
|| inf
->pid
== 0)
4423 return linux_ns_same (inf
->pid
, LINUX_NS_MNT
);
4426 /* Convert the INF argument passed to a to_fileio_* method
4427 to a process ID suitable for passing to its corresponding
4428 linux_mntns_* function. If INF is non-NULL then the
4429 caller is requesting the filesystem seen by INF. If INF
4430 is NULL then the caller is requesting the filesystem seen
4431 by the GDB. We fall back to GDB's filesystem in the case
4432 that INF is non-NULL but its PID is unknown. */
4435 linux_nat_fileio_pid_of (struct inferior
*inf
)
4437 if (inf
== NULL
|| inf
->fake_pid_p
|| inf
->pid
== 0)
4443 /* Implementation of to_fileio_open. */
4446 linux_nat_target::fileio_open (struct inferior
*inf
, const char *filename
,
4447 int flags
, int mode
, int warn_if_slow
,
4454 if (fileio_to_host_openflags (flags
, &nat_flags
) == -1
4455 || fileio_to_host_mode (mode
, &nat_mode
) == -1)
4457 *target_errno
= FILEIO_EINVAL
;
4461 fd
= linux_mntns_open_cloexec (linux_nat_fileio_pid_of (inf
),
4462 filename
, nat_flags
, nat_mode
);
4464 *target_errno
= host_to_fileio_error (errno
);
4469 /* Implementation of to_fileio_readlink. */
4471 gdb::optional
<std::string
>
4472 linux_nat_target::fileio_readlink (struct inferior
*inf
, const char *filename
,
4478 len
= linux_mntns_readlink (linux_nat_fileio_pid_of (inf
),
4479 filename
, buf
, sizeof (buf
));
4482 *target_errno
= host_to_fileio_error (errno
);
4486 return std::string (buf
, len
);
4489 /* Implementation of to_fileio_unlink. */
4492 linux_nat_target::fileio_unlink (struct inferior
*inf
, const char *filename
,
4497 ret
= linux_mntns_unlink (linux_nat_fileio_pid_of (inf
),
4500 *target_errno
= host_to_fileio_error (errno
);
4505 /* Implementation of the to_thread_events method. */
4508 linux_nat_target::thread_events (int enable
)
4510 report_thread_events
= enable
;
4513 linux_nat_target::linux_nat_target ()
4515 /* We don't change the stratum; this target will sit at
4516 process_stratum and thread_db will set at thread_stratum. This
4517 is a little strange, since this is a multi-threaded-capable
4518 target, but we want to be on the stack below thread_db, and we
4519 also want to be used for single-threaded processes. */
4522 /* See linux-nat.h. */
4525 linux_nat_get_siginfo (ptid_t ptid
, siginfo_t
*siginfo
)
4534 ptrace (PTRACE_GETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, siginfo
);
4537 memset (siginfo
, 0, sizeof (*siginfo
));
4543 /* See nat/linux-nat.h. */
4546 current_lwp_ptid (void)
4548 gdb_assert (inferior_ptid
.lwp_p ());
4549 return inferior_ptid
;
4552 void _initialize_linux_nat ();
4554 _initialize_linux_nat ()
4556 add_setshow_zuinteger_cmd ("lin-lwp", class_maintenance
,
4557 &debug_linux_nat
, _("\
4558 Set debugging of GNU/Linux lwp module."), _("\
4559 Show debugging of GNU/Linux lwp module."), _("\
4560 Enables printf debugging output."),
4562 show_debug_linux_nat
,
4563 &setdebuglist
, &showdebuglist
);
4565 add_setshow_boolean_cmd ("linux-namespaces", class_maintenance
,
4566 &debug_linux_namespaces
, _("\
4567 Set debugging of GNU/Linux namespaces module."), _("\
4568 Show debugging of GNU/Linux namespaces module."), _("\
4569 Enables printf debugging output."),
4572 &setdebuglist
, &showdebuglist
);
4574 /* Install a SIGCHLD handler. */
4575 sigchld_action
.sa_handler
= sigchld_handler
;
4576 sigemptyset (&sigchld_action
.sa_mask
);
4577 sigchld_action
.sa_flags
= SA_RESTART
;
4579 /* Make it the default. */
4580 sigaction (SIGCHLD
, &sigchld_action
, NULL
);
4582 /* Make sure we don't block SIGCHLD during a sigsuspend. */
4583 gdb_sigmask (SIG_SETMASK
, NULL
, &suspend_mask
);
4584 sigdelset (&suspend_mask
, SIGCHLD
);
4586 sigemptyset (&blocked_mask
);
4588 lwp_lwpid_htab_create ();
4592 /* FIXME: kettenis/2000-08-26: The stuff on this page is specific to
4593 the GNU/Linux Threads library and therefore doesn't really belong
4596 /* Return the set of signals used by the threads library in *SET. */
4599 lin_thread_get_thread_signals (sigset_t
*set
)
4603 /* NPTL reserves the first two RT signals, but does not provide any
4604 way for the debugger to query the signal numbers - fortunately
4605 they don't change. */
4606 sigaddset (set
, __SIGRTMIN
);
4607 sigaddset (set
, __SIGRTMIN
+ 1);