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 "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 (int follow_child
, int 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
);
1982 if (event
== PTRACE_EVENT_FORK
1983 && linux_fork_checkpointing_p (lp
->ptid
.pid ()))
1985 /* Handle checkpointing by linux-fork.c here as a special
1986 case. We don't want the follow-fork-mode or 'catch fork'
1987 to interfere with this. */
1989 /* This won't actually modify the breakpoint list, but will
1990 physically remove the breakpoints from the child. */
1991 detach_breakpoints (ptid_t (new_pid
, new_pid
, 0));
1993 /* Retain child fork in ptrace (stopped) state. */
1994 if (!find_fork_pid (new_pid
))
1997 /* Report as spurious, so that infrun doesn't want to follow
1998 this fork. We're actually doing an infcall in
2000 ourstatus
->kind
= TARGET_WAITKIND_SPURIOUS
;
2002 /* Report the stop to the core. */
2006 if (event
== PTRACE_EVENT_FORK
)
2007 ourstatus
->kind
= TARGET_WAITKIND_FORKED
;
2008 else if (event
== PTRACE_EVENT_VFORK
)
2009 ourstatus
->kind
= TARGET_WAITKIND_VFORKED
;
2010 else if (event
== PTRACE_EVENT_CLONE
)
2012 struct lwp_info
*new_lp
;
2014 ourstatus
->kind
= TARGET_WAITKIND_IGNORE
;
2016 if (debug_linux_nat
)
2017 fprintf_unfiltered (gdb_stdlog
,
2018 "LHEW: Got clone event "
2019 "from LWP %d, new child is LWP %ld\n",
2022 new_lp
= add_lwp (ptid_t (lp
->ptid
.pid (), new_pid
, 0));
2023 new_lp
->stopped
= 1;
2024 new_lp
->resumed
= 1;
2026 /* If the thread_db layer is active, let it record the user
2027 level thread id and status, and add the thread to GDB's
2029 if (!thread_db_notice_clone (lp
->ptid
, new_lp
->ptid
))
2031 /* The process is not using thread_db. Add the LWP to
2033 target_post_attach (new_lp
->ptid
.lwp ());
2034 add_thread (linux_target
, new_lp
->ptid
);
2037 /* Even if we're stopping the thread for some reason
2038 internal to this module, from the perspective of infrun
2039 and the user/frontend, this new thread is running until
2040 it next reports a stop. */
2041 set_running (linux_target
, new_lp
->ptid
, true);
2042 set_executing (linux_target
, new_lp
->ptid
, true);
2044 if (WSTOPSIG (status
) != SIGSTOP
)
2046 /* This can happen if someone starts sending signals to
2047 the new thread before it gets a chance to run, which
2048 have a lower number than SIGSTOP (e.g. SIGUSR1).
2049 This is an unlikely case, and harder to handle for
2050 fork / vfork than for clone, so we do not try - but
2051 we handle it for clone events here. */
2053 new_lp
->signalled
= 1;
2055 /* We created NEW_LP so it cannot yet contain STATUS. */
2056 gdb_assert (new_lp
->status
== 0);
2058 /* Save the wait status to report later. */
2059 if (debug_linux_nat
)
2060 fprintf_unfiltered (gdb_stdlog
,
2061 "LHEW: waitpid of new LWP %ld, "
2062 "saving status %s\n",
2063 (long) new_lp
->ptid
.lwp (),
2064 status_to_str (status
));
2065 new_lp
->status
= status
;
2067 else if (report_thread_events
)
2069 new_lp
->waitstatus
.kind
= TARGET_WAITKIND_THREAD_CREATED
;
2070 new_lp
->status
= status
;
2079 if (event
== PTRACE_EVENT_EXEC
)
2081 if (debug_linux_nat
)
2082 fprintf_unfiltered (gdb_stdlog
,
2083 "LHEW: Got exec event from LWP %ld\n",
2086 ourstatus
->kind
= TARGET_WAITKIND_EXECD
;
2087 ourstatus
->value
.execd_pathname
2088 = xstrdup (linux_proc_pid_to_exec_file (pid
));
2090 /* The thread that execed must have been resumed, but, when a
2091 thread execs, it changes its tid to the tgid, and the old
2092 tgid thread might have not been resumed. */
2097 if (event
== PTRACE_EVENT_VFORK_DONE
)
2099 if (current_inferior ()->waiting_for_vfork_done
)
2101 if (debug_linux_nat
)
2102 fprintf_unfiltered (gdb_stdlog
,
2103 "LHEW: Got expected PTRACE_EVENT_"
2104 "VFORK_DONE from LWP %ld: stopping\n",
2107 ourstatus
->kind
= TARGET_WAITKIND_VFORK_DONE
;
2111 if (debug_linux_nat
)
2112 fprintf_unfiltered (gdb_stdlog
,
2113 "LHEW: Got PTRACE_EVENT_VFORK_DONE "
2114 "from LWP %ld: ignoring\n",
2119 internal_error (__FILE__
, __LINE__
,
2120 _("unknown ptrace event %d"), event
);
2123 /* Suspend waiting for a signal. We're mostly interested in
2129 if (debug_linux_nat
)
2130 fprintf_unfiltered (gdb_stdlog
, "linux-nat: about to sigsuspend\n");
2131 sigsuspend (&suspend_mask
);
2133 /* If the quit flag is set, it means that the user pressed Ctrl-C
2134 and we're debugging a process that is running on a separate
2135 terminal, so we must forward the Ctrl-C to the inferior. (If the
2136 inferior is sharing GDB's terminal, then the Ctrl-C reaches the
2137 inferior directly.) We must do this here because functions that
2138 need to block waiting for a signal loop forever until there's an
2139 event to report before returning back to the event loop. */
2140 if (!target_terminal::is_ours ())
2142 if (check_quit_flag ())
2143 target_pass_ctrlc ();
2147 /* Wait for LP to stop. Returns the wait status, or 0 if the LWP has
2151 wait_lwp (struct lwp_info
*lp
)
2155 int thread_dead
= 0;
2158 gdb_assert (!lp
->stopped
);
2159 gdb_assert (lp
->status
== 0);
2161 /* Make sure SIGCHLD is blocked for sigsuspend avoiding a race below. */
2162 block_child_signals (&prev_mask
);
2166 pid
= my_waitpid (lp
->ptid
.lwp (), &status
, __WALL
| WNOHANG
);
2167 if (pid
== -1 && errno
== ECHILD
)
2169 /* The thread has previously exited. We need to delete it
2170 now because if this was a non-leader thread execing, we
2171 won't get an exit event. See comments on exec events at
2172 the top of the file. */
2174 if (debug_linux_nat
)
2175 fprintf_unfiltered (gdb_stdlog
, "WL: %s vanished.\n",
2176 target_pid_to_str (lp
->ptid
).c_str ());
2181 /* Bugs 10970, 12702.
2182 Thread group leader may have exited in which case we'll lock up in
2183 waitpid if there are other threads, even if they are all zombies too.
2184 Basically, we're not supposed to use waitpid this way.
2185 tkill(pid,0) cannot be used here as it gets ESRCH for both
2186 for zombie and running processes.
2188 As a workaround, check if we're waiting for the thread group leader and
2189 if it's a zombie, and avoid calling waitpid if it is.
2191 This is racy, what if the tgl becomes a zombie right after we check?
2192 Therefore always use WNOHANG with sigsuspend - it is equivalent to
2193 waiting waitpid but linux_proc_pid_is_zombie is safe this way. */
2195 if (lp
->ptid
.pid () == lp
->ptid
.lwp ()
2196 && linux_proc_pid_is_zombie (lp
->ptid
.lwp ()))
2199 if (debug_linux_nat
)
2200 fprintf_unfiltered (gdb_stdlog
,
2201 "WL: Thread group leader %s vanished.\n",
2202 target_pid_to_str (lp
->ptid
).c_str ());
2206 /* Wait for next SIGCHLD and try again. This may let SIGCHLD handlers
2207 get invoked despite our caller had them intentionally blocked by
2208 block_child_signals. This is sensitive only to the loop of
2209 linux_nat_wait_1 and there if we get called my_waitpid gets called
2210 again before it gets to sigsuspend so we can safely let the handlers
2211 get executed here. */
2215 restore_child_signals_mask (&prev_mask
);
2219 gdb_assert (pid
== lp
->ptid
.lwp ());
2221 if (debug_linux_nat
)
2223 fprintf_unfiltered (gdb_stdlog
,
2224 "WL: waitpid %s received %s\n",
2225 target_pid_to_str (lp
->ptid
).c_str (),
2226 status_to_str (status
));
2229 /* Check if the thread has exited. */
2230 if (WIFEXITED (status
) || WIFSIGNALED (status
))
2232 if (report_thread_events
2233 || lp
->ptid
.pid () == lp
->ptid
.lwp ())
2235 if (debug_linux_nat
)
2236 fprintf_unfiltered (gdb_stdlog
, "WL: LWP %d exited.\n",
2239 /* If this is the leader exiting, it means the whole
2240 process is gone. Store the status to report to the
2241 core. Store it in lp->waitstatus, because lp->status
2242 would be ambiguous (W_EXITCODE(0,0) == 0). */
2243 store_waitstatus (&lp
->waitstatus
, status
);
2248 if (debug_linux_nat
)
2249 fprintf_unfiltered (gdb_stdlog
, "WL: %s exited.\n",
2250 target_pid_to_str (lp
->ptid
).c_str ());
2260 gdb_assert (WIFSTOPPED (status
));
2263 if (lp
->must_set_ptrace_flags
)
2265 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2266 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
2268 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
2269 lp
->must_set_ptrace_flags
= 0;
2272 /* Handle GNU/Linux's syscall SIGTRAPs. */
2273 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
2275 /* No longer need the sysgood bit. The ptrace event ends up
2276 recorded in lp->waitstatus if we care for it. We can carry
2277 on handling the event like a regular SIGTRAP from here
2279 status
= W_STOPCODE (SIGTRAP
);
2280 if (linux_handle_syscall_trap (lp
, 1))
2281 return wait_lwp (lp
);
2285 /* Almost all other ptrace-stops are known to be outside of system
2286 calls, with further exceptions in linux_handle_extended_wait. */
2287 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
2290 /* Handle GNU/Linux's extended waitstatus for trace events. */
2291 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
2292 && linux_is_extended_waitstatus (status
))
2294 if (debug_linux_nat
)
2295 fprintf_unfiltered (gdb_stdlog
,
2296 "WL: Handling extended status 0x%06x\n",
2298 linux_handle_extended_wait (lp
, status
);
2305 /* Send a SIGSTOP to LP. */
2308 stop_callback (struct lwp_info
*lp
)
2310 if (!lp
->stopped
&& !lp
->signalled
)
2314 if (debug_linux_nat
)
2316 fprintf_unfiltered (gdb_stdlog
,
2317 "SC: kill %s **<SIGSTOP>**\n",
2318 target_pid_to_str (lp
->ptid
).c_str ());
2321 ret
= kill_lwp (lp
->ptid
.lwp (), SIGSTOP
);
2322 if (debug_linux_nat
)
2324 fprintf_unfiltered (gdb_stdlog
,
2325 "SC: lwp kill %d %s\n",
2327 errno
? safe_strerror (errno
) : "ERRNO-OK");
2331 gdb_assert (lp
->status
== 0);
2337 /* Request a stop on LWP. */
2340 linux_stop_lwp (struct lwp_info
*lwp
)
2342 stop_callback (lwp
);
2345 /* See linux-nat.h */
2348 linux_stop_and_wait_all_lwps (void)
2350 /* Stop all LWP's ... */
2351 iterate_over_lwps (minus_one_ptid
, stop_callback
);
2353 /* ... and wait until all of them have reported back that
2354 they're no longer running. */
2355 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
2358 /* See linux-nat.h */
2361 linux_unstop_all_lwps (void)
2363 iterate_over_lwps (minus_one_ptid
,
2364 [] (struct lwp_info
*info
)
2366 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
2370 /* Return non-zero if LWP PID has a pending SIGINT. */
2373 linux_nat_has_pending_sigint (int pid
)
2375 sigset_t pending
, blocked
, ignored
;
2377 linux_proc_pending_signals (pid
, &pending
, &blocked
, &ignored
);
2379 if (sigismember (&pending
, SIGINT
)
2380 && !sigismember (&ignored
, SIGINT
))
2386 /* Set a flag in LP indicating that we should ignore its next SIGINT. */
2389 set_ignore_sigint (struct lwp_info
*lp
)
2391 /* If a thread has a pending SIGINT, consume it; otherwise, set a
2392 flag to consume the next one. */
2393 if (lp
->stopped
&& lp
->status
!= 0 && WIFSTOPPED (lp
->status
)
2394 && WSTOPSIG (lp
->status
) == SIGINT
)
2397 lp
->ignore_sigint
= 1;
2402 /* If LP does not have a SIGINT pending, then clear the ignore_sigint flag.
2403 This function is called after we know the LWP has stopped; if the LWP
2404 stopped before the expected SIGINT was delivered, then it will never have
2405 arrived. Also, if the signal was delivered to a shared queue and consumed
2406 by a different thread, it will never be delivered to this LWP. */
2409 maybe_clear_ignore_sigint (struct lwp_info
*lp
)
2411 if (!lp
->ignore_sigint
)
2414 if (!linux_nat_has_pending_sigint (lp
->ptid
.lwp ()))
2416 if (debug_linux_nat
)
2417 fprintf_unfiltered (gdb_stdlog
,
2418 "MCIS: Clearing bogus flag for %s\n",
2419 target_pid_to_str (lp
->ptid
).c_str ());
2420 lp
->ignore_sigint
= 0;
2424 /* Fetch the possible triggered data watchpoint info and store it in
2427 On some archs, like x86, that use debug registers to set
2428 watchpoints, it's possible that the way to know which watched
2429 address trapped, is to check the register that is used to select
2430 which address to watch. Problem is, between setting the watchpoint
2431 and reading back which data address trapped, the user may change
2432 the set of watchpoints, and, as a consequence, GDB changes the
2433 debug registers in the inferior. To avoid reading back a stale
2434 stopped-data-address when that happens, we cache in LP the fact
2435 that a watchpoint trapped, and the corresponding data address, as
2436 soon as we see LP stop with a SIGTRAP. If GDB changes the debug
2437 registers meanwhile, we have the cached data we can rely on. */
2440 check_stopped_by_watchpoint (struct lwp_info
*lp
)
2442 scoped_restore save_inferior_ptid
= make_scoped_restore (&inferior_ptid
);
2443 inferior_ptid
= lp
->ptid
;
2445 if (linux_target
->low_stopped_by_watchpoint ())
2447 lp
->stop_reason
= TARGET_STOPPED_BY_WATCHPOINT
;
2448 lp
->stopped_data_address_p
2449 = linux_target
->low_stopped_data_address (&lp
->stopped_data_address
);
2452 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2455 /* Returns true if the LWP had stopped for a watchpoint. */
2458 linux_nat_target::stopped_by_watchpoint ()
2460 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2462 gdb_assert (lp
!= NULL
);
2464 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2468 linux_nat_target::stopped_data_address (CORE_ADDR
*addr_p
)
2470 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2472 gdb_assert (lp
!= NULL
);
2474 *addr_p
= lp
->stopped_data_address
;
2476 return lp
->stopped_data_address_p
;
2479 /* Commonly any breakpoint / watchpoint generate only SIGTRAP. */
2482 linux_nat_target::low_status_is_event (int status
)
2484 return WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
;
2487 /* Wait until LP is stopped. */
2490 stop_wait_callback (struct lwp_info
*lp
)
2492 inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
2494 /* If this is a vfork parent, bail out, it is not going to report
2495 any SIGSTOP until the vfork is done with. */
2496 if (inf
->vfork_child
!= NULL
)
2503 status
= wait_lwp (lp
);
2507 if (lp
->ignore_sigint
&& WIFSTOPPED (status
)
2508 && WSTOPSIG (status
) == SIGINT
)
2510 lp
->ignore_sigint
= 0;
2513 ptrace (PTRACE_CONT
, lp
->ptid
.lwp (), 0, 0);
2515 if (debug_linux_nat
)
2516 fprintf_unfiltered (gdb_stdlog
,
2517 "PTRACE_CONT %s, 0, 0 (%s) "
2518 "(discarding SIGINT)\n",
2519 target_pid_to_str (lp
->ptid
).c_str (),
2520 errno
? safe_strerror (errno
) : "OK");
2522 return stop_wait_callback (lp
);
2525 maybe_clear_ignore_sigint (lp
);
2527 if (WSTOPSIG (status
) != SIGSTOP
)
2529 /* The thread was stopped with a signal other than SIGSTOP. */
2531 if (debug_linux_nat
)
2532 fprintf_unfiltered (gdb_stdlog
,
2533 "SWC: Pending event %s in %s\n",
2534 status_to_str ((int) status
),
2535 target_pid_to_str (lp
->ptid
).c_str ());
2537 /* Save the sigtrap event. */
2538 lp
->status
= status
;
2539 gdb_assert (lp
->signalled
);
2540 save_stop_reason (lp
);
2544 /* We caught the SIGSTOP that we intended to catch. */
2546 if (debug_linux_nat
)
2547 fprintf_unfiltered (gdb_stdlog
,
2548 "SWC: Expected SIGSTOP caught for %s.\n",
2549 target_pid_to_str (lp
->ptid
).c_str ());
2553 /* If we are waiting for this stop so we can report the thread
2554 stopped then we need to record this status. Otherwise, we can
2555 now discard this stop event. */
2556 if (lp
->last_resume_kind
== resume_stop
)
2558 lp
->status
= status
;
2559 save_stop_reason (lp
);
2567 /* Return non-zero if LP has a wait status pending. Discard the
2568 pending event and resume the LWP if the event that originally
2569 caused the stop became uninteresting. */
2572 status_callback (struct lwp_info
*lp
)
2574 /* Only report a pending wait status if we pretend that this has
2575 indeed been resumed. */
2579 if (!lwp_status_pending_p (lp
))
2582 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
2583 || lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2585 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2589 pc
= regcache_read_pc (regcache
);
2591 if (pc
!= lp
->stop_pc
)
2593 if (debug_linux_nat
)
2594 fprintf_unfiltered (gdb_stdlog
,
2595 "SC: PC of %s changed. was=%s, now=%s\n",
2596 target_pid_to_str (lp
->ptid
).c_str (),
2597 paddress (target_gdbarch (), lp
->stop_pc
),
2598 paddress (target_gdbarch (), pc
));
2602 #if !USE_SIGTRAP_SIGINFO
2603 else if (!breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2605 if (debug_linux_nat
)
2606 fprintf_unfiltered (gdb_stdlog
,
2607 "SC: previous breakpoint of %s, at %s gone\n",
2608 target_pid_to_str (lp
->ptid
).c_str (),
2609 paddress (target_gdbarch (), lp
->stop_pc
));
2617 if (debug_linux_nat
)
2618 fprintf_unfiltered (gdb_stdlog
,
2619 "SC: pending event of %s cancelled.\n",
2620 target_pid_to_str (lp
->ptid
).c_str ());
2623 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2631 /* Count the LWP's that have had events. */
2634 count_events_callback (struct lwp_info
*lp
, int *count
)
2636 gdb_assert (count
!= NULL
);
2638 /* Select only resumed LWPs that have an event pending. */
2639 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2645 /* Select the LWP (if any) that is currently being single-stepped. */
2648 select_singlestep_lwp_callback (struct lwp_info
*lp
)
2650 if (lp
->last_resume_kind
== resume_step
2657 /* Returns true if LP has a status pending. */
2660 lwp_status_pending_p (struct lwp_info
*lp
)
2662 /* We check for lp->waitstatus in addition to lp->status, because we
2663 can have pending process exits recorded in lp->status and
2664 W_EXITCODE(0,0) happens to be 0. */
2665 return lp
->status
!= 0 || lp
->waitstatus
.kind
!= TARGET_WAITKIND_IGNORE
;
2668 /* Select the Nth LWP that has had an event. */
2671 select_event_lwp_callback (struct lwp_info
*lp
, int *selector
)
2673 gdb_assert (selector
!= NULL
);
2675 /* Select only resumed LWPs that have an event pending. */
2676 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2677 if ((*selector
)-- == 0)
2683 /* Called when the LWP stopped for a signal/trap. If it stopped for a
2684 trap check what caused it (breakpoint, watchpoint, trace, etc.),
2685 and save the result in the LWP's stop_reason field. If it stopped
2686 for a breakpoint, decrement the PC if necessary on the lwp's
2690 save_stop_reason (struct lwp_info
*lp
)
2692 struct regcache
*regcache
;
2693 struct gdbarch
*gdbarch
;
2696 #if USE_SIGTRAP_SIGINFO
2700 gdb_assert (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
);
2701 gdb_assert (lp
->status
!= 0);
2703 if (!linux_target
->low_status_is_event (lp
->status
))
2706 regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2707 gdbarch
= regcache
->arch ();
2709 pc
= regcache_read_pc (regcache
);
2710 sw_bp_pc
= pc
- gdbarch_decr_pc_after_break (gdbarch
);
2712 #if USE_SIGTRAP_SIGINFO
2713 if (linux_nat_get_siginfo (lp
->ptid
, &siginfo
))
2715 if (siginfo
.si_signo
== SIGTRAP
)
2717 if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
)
2718 && GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2720 /* The si_code is ambiguous on this arch -- check debug
2722 if (!check_stopped_by_watchpoint (lp
))
2723 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2725 else if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
))
2727 /* If we determine the LWP stopped for a SW breakpoint,
2728 trust it. Particularly don't check watchpoint
2729 registers, because, at least on s390, we'd find
2730 stopped-by-watchpoint as long as there's a watchpoint
2732 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2734 else if (GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2736 /* This can indicate either a hardware breakpoint or
2737 hardware watchpoint. Check debug registers. */
2738 if (!check_stopped_by_watchpoint (lp
))
2739 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2741 else if (siginfo
.si_code
== TRAP_TRACE
)
2743 if (debug_linux_nat
)
2744 fprintf_unfiltered (gdb_stdlog
,
2745 "CSBB: %s stopped by trace\n",
2746 target_pid_to_str (lp
->ptid
).c_str ());
2748 /* We may have single stepped an instruction that
2749 triggered a watchpoint. In that case, on some
2750 architectures (such as x86), instead of TRAP_HWBKPT,
2751 si_code indicates TRAP_TRACE, and we need to check
2752 the debug registers separately. */
2753 check_stopped_by_watchpoint (lp
);
2758 if ((!lp
->step
|| lp
->stop_pc
== sw_bp_pc
)
2759 && software_breakpoint_inserted_here_p (regcache
->aspace (),
2762 /* The LWP was either continued, or stepped a software
2763 breakpoint instruction. */
2764 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2767 if (hardware_breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2768 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2770 if (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
)
2771 check_stopped_by_watchpoint (lp
);
2774 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
)
2776 if (debug_linux_nat
)
2777 fprintf_unfiltered (gdb_stdlog
,
2778 "CSBB: %s stopped by software breakpoint\n",
2779 target_pid_to_str (lp
->ptid
).c_str ());
2781 /* Back up the PC if necessary. */
2783 regcache_write_pc (regcache
, sw_bp_pc
);
2785 /* Update this so we record the correct stop PC below. */
2788 else if (lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2790 if (debug_linux_nat
)
2791 fprintf_unfiltered (gdb_stdlog
,
2792 "CSBB: %s stopped by hardware breakpoint\n",
2793 target_pid_to_str (lp
->ptid
).c_str ());
2795 else if (lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
)
2797 if (debug_linux_nat
)
2798 fprintf_unfiltered (gdb_stdlog
,
2799 "CSBB: %s stopped by hardware watchpoint\n",
2800 target_pid_to_str (lp
->ptid
).c_str ());
2807 /* Returns true if the LWP had stopped for a software breakpoint. */
2810 linux_nat_target::stopped_by_sw_breakpoint ()
2812 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2814 gdb_assert (lp
!= NULL
);
2816 return lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
;
2819 /* Implement the supports_stopped_by_sw_breakpoint method. */
2822 linux_nat_target::supports_stopped_by_sw_breakpoint ()
2824 return USE_SIGTRAP_SIGINFO
;
2827 /* Returns true if the LWP had stopped for a hardware
2828 breakpoint/watchpoint. */
2831 linux_nat_target::stopped_by_hw_breakpoint ()
2833 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2835 gdb_assert (lp
!= NULL
);
2837 return lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
;
2840 /* Implement the supports_stopped_by_hw_breakpoint method. */
2843 linux_nat_target::supports_stopped_by_hw_breakpoint ()
2845 return USE_SIGTRAP_SIGINFO
;
2848 /* Select one LWP out of those that have events pending. */
2851 select_event_lwp (ptid_t filter
, struct lwp_info
**orig_lp
, int *status
)
2854 int random_selector
;
2855 struct lwp_info
*event_lp
= NULL
;
2857 /* Record the wait status for the original LWP. */
2858 (*orig_lp
)->status
= *status
;
2860 /* In all-stop, give preference to the LWP that is being
2861 single-stepped. There will be at most one, and it will be the
2862 LWP that the core is most interested in. If we didn't do this,
2863 then we'd have to handle pending step SIGTRAPs somehow in case
2864 the core later continues the previously-stepped thread, as
2865 otherwise we'd report the pending SIGTRAP then, and the core, not
2866 having stepped the thread, wouldn't understand what the trap was
2867 for, and therefore would report it to the user as a random
2869 if (!target_is_non_stop_p ())
2871 event_lp
= iterate_over_lwps (filter
, select_singlestep_lwp_callback
);
2872 if (event_lp
!= NULL
)
2874 if (debug_linux_nat
)
2875 fprintf_unfiltered (gdb_stdlog
,
2876 "SEL: Select single-step %s\n",
2877 target_pid_to_str (event_lp
->ptid
).c_str ());
2881 if (event_lp
== NULL
)
2883 /* Pick one at random, out of those which have had events. */
2885 /* First see how many events we have. */
2886 iterate_over_lwps (filter
,
2887 [&] (struct lwp_info
*info
)
2889 return count_events_callback (info
, &num_events
);
2891 gdb_assert (num_events
> 0);
2893 /* Now randomly pick a LWP out of those that have had
2895 random_selector
= (int)
2896 ((num_events
* (double) rand ()) / (RAND_MAX
+ 1.0));
2898 if (debug_linux_nat
&& num_events
> 1)
2899 fprintf_unfiltered (gdb_stdlog
,
2900 "SEL: Found %d events, selecting #%d\n",
2901 num_events
, random_selector
);
2904 = (iterate_over_lwps
2906 [&] (struct lwp_info
*info
)
2908 return select_event_lwp_callback (info
,
2913 if (event_lp
!= NULL
)
2915 /* Switch the event LWP. */
2916 *orig_lp
= event_lp
;
2917 *status
= event_lp
->status
;
2920 /* Flush the wait status for the event LWP. */
2921 (*orig_lp
)->status
= 0;
2924 /* Return non-zero if LP has been resumed. */
2927 resumed_callback (struct lwp_info
*lp
)
2932 /* Check if we should go on and pass this event to common code.
2933 Return the affected lwp if we should, or NULL otherwise. */
2935 static struct lwp_info
*
2936 linux_nat_filter_event (int lwpid
, int status
)
2938 struct lwp_info
*lp
;
2939 int event
= linux_ptrace_get_extended_event (status
);
2941 lp
= find_lwp_pid (ptid_t (lwpid
));
2943 /* Check for stop events reported by a process we didn't already
2944 know about - anything not already in our LWP list.
2946 If we're expecting to receive stopped processes after
2947 fork, vfork, and clone events, then we'll just add the
2948 new one to our list and go back to waiting for the event
2949 to be reported - the stopped process might be returned
2950 from waitpid before or after the event is.
2952 But note the case of a non-leader thread exec'ing after the
2953 leader having exited, and gone from our lists. The non-leader
2954 thread changes its tid to the tgid. */
2956 if (WIFSTOPPED (status
) && lp
== NULL
2957 && (WSTOPSIG (status
) == SIGTRAP
&& event
== PTRACE_EVENT_EXEC
))
2959 /* A multi-thread exec after we had seen the leader exiting. */
2960 if (debug_linux_nat
)
2961 fprintf_unfiltered (gdb_stdlog
,
2962 "LLW: Re-adding thread group leader LWP %d.\n",
2965 lp
= add_lwp (ptid_t (lwpid
, lwpid
, 0));
2968 add_thread (linux_target
, lp
->ptid
);
2971 if (WIFSTOPPED (status
) && !lp
)
2973 if (debug_linux_nat
)
2974 fprintf_unfiltered (gdb_stdlog
,
2975 "LHEW: saving LWP %ld status %s in stopped_pids list\n",
2976 (long) lwpid
, status_to_str (status
));
2977 add_to_pid_list (&stopped_pids
, lwpid
, status
);
2981 /* Make sure we don't report an event for the exit of an LWP not in
2982 our list, i.e. not part of the current process. This can happen
2983 if we detach from a program we originally forked and then it
2985 if (!WIFSTOPPED (status
) && !lp
)
2988 /* This LWP is stopped now. (And if dead, this prevents it from
2989 ever being continued.) */
2992 if (WIFSTOPPED (status
) && lp
->must_set_ptrace_flags
)
2994 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2995 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
2997 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
2998 lp
->must_set_ptrace_flags
= 0;
3001 /* Handle GNU/Linux's syscall SIGTRAPs. */
3002 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
3004 /* No longer need the sysgood bit. The ptrace event ends up
3005 recorded in lp->waitstatus if we care for it. We can carry
3006 on handling the event like a regular SIGTRAP from here
3008 status
= W_STOPCODE (SIGTRAP
);
3009 if (linux_handle_syscall_trap (lp
, 0))
3014 /* Almost all other ptrace-stops are known to be outside of system
3015 calls, with further exceptions in linux_handle_extended_wait. */
3016 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
3019 /* Handle GNU/Linux's extended waitstatus for trace events. */
3020 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
3021 && linux_is_extended_waitstatus (status
))
3023 if (debug_linux_nat
)
3024 fprintf_unfiltered (gdb_stdlog
,
3025 "LLW: Handling extended status 0x%06x\n",
3027 if (linux_handle_extended_wait (lp
, status
))
3031 /* Check if the thread has exited. */
3032 if (WIFEXITED (status
) || WIFSIGNALED (status
))
3034 if (!report_thread_events
3035 && num_lwps (lp
->ptid
.pid ()) > 1)
3037 if (debug_linux_nat
)
3038 fprintf_unfiltered (gdb_stdlog
,
3039 "LLW: %s exited.\n",
3040 target_pid_to_str (lp
->ptid
).c_str ());
3042 /* If there is at least one more LWP, then the exit signal
3043 was not the end of the debugged application and should be
3049 /* Note that even if the leader was ptrace-stopped, it can still
3050 exit, if e.g., some other thread brings down the whole
3051 process (calls `exit'). So don't assert that the lwp is
3053 if (debug_linux_nat
)
3054 fprintf_unfiltered (gdb_stdlog
,
3055 "LWP %ld exited (resumed=%d)\n",
3056 lp
->ptid
.lwp (), lp
->resumed
);
3058 /* Dead LWP's aren't expected to reported a pending sigstop. */
3061 /* Store the pending event in the waitstatus, because
3062 W_EXITCODE(0,0) == 0. */
3063 store_waitstatus (&lp
->waitstatus
, status
);
3067 /* Make sure we don't report a SIGSTOP that we sent ourselves in
3068 an attempt to stop an LWP. */
3070 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGSTOP
)
3074 if (lp
->last_resume_kind
== resume_stop
)
3076 if (debug_linux_nat
)
3077 fprintf_unfiltered (gdb_stdlog
,
3078 "LLW: resume_stop SIGSTOP caught for %s.\n",
3079 target_pid_to_str (lp
->ptid
).c_str ());
3083 /* This is a delayed SIGSTOP. Filter out the event. */
3085 if (debug_linux_nat
)
3086 fprintf_unfiltered (gdb_stdlog
,
3087 "LLW: %s %s, 0, 0 (discard delayed SIGSTOP)\n",
3089 "PTRACE_SINGLESTEP" : "PTRACE_CONT",
3090 target_pid_to_str (lp
->ptid
).c_str ());
3092 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
3093 gdb_assert (lp
->resumed
);
3098 /* Make sure we don't report a SIGINT that we have already displayed
3099 for another thread. */
3100 if (lp
->ignore_sigint
3101 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGINT
)
3103 if (debug_linux_nat
)
3104 fprintf_unfiltered (gdb_stdlog
,
3105 "LLW: Delayed SIGINT caught for %s.\n",
3106 target_pid_to_str (lp
->ptid
).c_str ());
3108 /* This is a delayed SIGINT. */
3109 lp
->ignore_sigint
= 0;
3111 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
3112 if (debug_linux_nat
)
3113 fprintf_unfiltered (gdb_stdlog
,
3114 "LLW: %s %s, 0, 0 (discard SIGINT)\n",
3116 "PTRACE_SINGLESTEP" : "PTRACE_CONT",
3117 target_pid_to_str (lp
->ptid
).c_str ());
3118 gdb_assert (lp
->resumed
);
3120 /* Discard the event. */
3124 /* Don't report signals that GDB isn't interested in, such as
3125 signals that are neither printed nor stopped upon. Stopping all
3126 threads can be a bit time-consuming, so if we want decent
3127 performance with heavily multi-threaded programs, especially when
3128 they're using a high frequency timer, we'd better avoid it if we
3130 if (WIFSTOPPED (status
))
3132 enum gdb_signal signo
= gdb_signal_from_host (WSTOPSIG (status
));
3134 if (!target_is_non_stop_p ())
3136 /* Only do the below in all-stop, as we currently use SIGSTOP
3137 to implement target_stop (see linux_nat_stop) in
3139 if (signo
== GDB_SIGNAL_INT
&& signal_pass_state (signo
) == 0)
3141 /* If ^C/BREAK is typed at the tty/console, SIGINT gets
3142 forwarded to the entire process group, that is, all LWPs
3143 will receive it - unless they're using CLONE_THREAD to
3144 share signals. Since we only want to report it once, we
3145 mark it as ignored for all LWPs except this one. */
3146 iterate_over_lwps (ptid_t (lp
->ptid
.pid ()), set_ignore_sigint
);
3147 lp
->ignore_sigint
= 0;
3150 maybe_clear_ignore_sigint (lp
);
3153 /* When using hardware single-step, we need to report every signal.
3154 Otherwise, signals in pass_mask may be short-circuited
3155 except signals that might be caused by a breakpoint, or SIGSTOP
3156 if we sent the SIGSTOP and are waiting for it to arrive. */
3158 && WSTOPSIG (status
) && sigismember (&pass_mask
, WSTOPSIG (status
))
3159 && (WSTOPSIG (status
) != SIGSTOP
3160 || !find_thread_ptid (linux_target
, lp
->ptid
)->stop_requested
)
3161 && !linux_wstatus_maybe_breakpoint (status
))
3163 linux_resume_one_lwp (lp
, lp
->step
, signo
);
3164 if (debug_linux_nat
)
3165 fprintf_unfiltered (gdb_stdlog
,
3166 "LLW: %s %s, %s (preempt 'handle')\n",
3168 "PTRACE_SINGLESTEP" : "PTRACE_CONT",
3169 target_pid_to_str (lp
->ptid
).c_str (),
3170 (signo
!= GDB_SIGNAL_0
3171 ? strsignal (gdb_signal_to_host (signo
))
3177 /* An interesting event. */
3179 lp
->status
= status
;
3180 save_stop_reason (lp
);
3184 /* Detect zombie thread group leaders, and "exit" them. We can't reap
3185 their exits until all other threads in the group have exited. */
3188 check_zombie_leaders (void)
3190 for (inferior
*inf
: all_inferiors ())
3192 struct lwp_info
*leader_lp
;
3197 leader_lp
= find_lwp_pid (ptid_t (inf
->pid
));
3198 if (leader_lp
!= NULL
3199 /* Check if there are other threads in the group, as we may
3200 have raced with the inferior simply exiting. */
3201 && num_lwps (inf
->pid
) > 1
3202 && linux_proc_pid_is_zombie (inf
->pid
))
3204 if (debug_linux_nat
)
3205 fprintf_unfiltered (gdb_stdlog
,
3206 "CZL: Thread group leader %d zombie "
3207 "(it exited, or another thread execd).\n",
3210 /* A leader zombie can mean one of two things:
3212 - It exited, and there's an exit status pending
3213 available, or only the leader exited (not the whole
3214 program). In the latter case, we can't waitpid the
3215 leader's exit status until all other threads are gone.
3217 - There are 3 or more threads in the group, and a thread
3218 other than the leader exec'd. See comments on exec
3219 events at the top of the file. We could try
3220 distinguishing the exit and exec cases, by waiting once
3221 more, and seeing if something comes out, but it doesn't
3222 sound useful. The previous leader _does_ go away, and
3223 we'll re-add the new one once we see the exec event
3224 (which is just the same as what would happen if the
3225 previous leader did exit voluntarily before some other
3228 if (debug_linux_nat
)
3229 fprintf_unfiltered (gdb_stdlog
,
3230 "CZL: Thread group leader %d vanished.\n",
3232 exit_lwp (leader_lp
);
3237 /* Convenience function that is called when the kernel reports an exit
3238 event. This decides whether to report the event to GDB as a
3239 process exit event, a thread exit event, or to suppress the
3243 filter_exit_event (struct lwp_info
*event_child
,
3244 struct target_waitstatus
*ourstatus
)
3246 ptid_t ptid
= event_child
->ptid
;
3248 if (num_lwps (ptid
.pid ()) > 1)
3250 if (report_thread_events
)
3251 ourstatus
->kind
= TARGET_WAITKIND_THREAD_EXITED
;
3253 ourstatus
->kind
= TARGET_WAITKIND_IGNORE
;
3255 exit_lwp (event_child
);
3262 linux_nat_wait_1 (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3266 enum resume_kind last_resume_kind
;
3267 struct lwp_info
*lp
;
3270 if (debug_linux_nat
)
3271 fprintf_unfiltered (gdb_stdlog
, "LLW: enter\n");
3273 /* The first time we get here after starting a new inferior, we may
3274 not have added it to the LWP list yet - this is the earliest
3275 moment at which we know its PID. */
3276 if (inferior_ptid
.is_pid ())
3278 /* Upgrade the main thread's ptid. */
3279 thread_change_ptid (linux_target
, inferior_ptid
,
3280 ptid_t (inferior_ptid
.pid (),
3281 inferior_ptid
.pid (), 0));
3283 lp
= add_initial_lwp (inferior_ptid
);
3287 /* Make sure SIGCHLD is blocked until the sigsuspend below. */
3288 block_child_signals (&prev_mask
);
3290 /* First check if there is a LWP with a wait status pending. */
3291 lp
= iterate_over_lwps (ptid
, status_callback
);
3294 if (debug_linux_nat
)
3295 fprintf_unfiltered (gdb_stdlog
,
3296 "LLW: Using pending wait status %s for %s.\n",
3297 status_to_str (lp
->status
),
3298 target_pid_to_str (lp
->ptid
).c_str ());
3301 /* But if we don't find a pending event, we'll have to wait. Always
3302 pull all events out of the kernel. We'll randomly select an
3303 event LWP out of all that have events, to prevent starvation. */
3309 /* Always use -1 and WNOHANG, due to couple of a kernel/ptrace
3312 - If the thread group leader exits while other threads in the
3313 thread group still exist, waitpid(TGID, ...) hangs. That
3314 waitpid won't return an exit status until the other threads
3315 in the group are reaped.
3317 - When a non-leader thread execs, that thread just vanishes
3318 without reporting an exit (so we'd hang if we waited for it
3319 explicitly in that case). The exec event is reported to
3323 lwpid
= my_waitpid (-1, &status
, __WALL
| WNOHANG
);
3325 if (debug_linux_nat
)
3326 fprintf_unfiltered (gdb_stdlog
,
3327 "LNW: waitpid(-1, ...) returned %d, %s\n",
3328 lwpid
, errno
? safe_strerror (errno
) : "ERRNO-OK");
3332 if (debug_linux_nat
)
3334 fprintf_unfiltered (gdb_stdlog
,
3335 "LLW: waitpid %ld received %s\n",
3336 (long) lwpid
, status_to_str (status
));
3339 linux_nat_filter_event (lwpid
, status
);
3340 /* Retry until nothing comes out of waitpid. A single
3341 SIGCHLD can indicate more than one child stopped. */
3345 /* Now that we've pulled all events out of the kernel, resume
3346 LWPs that don't have an interesting event to report. */
3347 iterate_over_lwps (minus_one_ptid
,
3348 [] (struct lwp_info
*info
)
3350 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
3353 /* ... and find an LWP with a status to report to the core, if
3355 lp
= iterate_over_lwps (ptid
, status_callback
);
3359 /* Check for zombie thread group leaders. Those can't be reaped
3360 until all other threads in the thread group are. */
3361 check_zombie_leaders ();
3363 /* If there are no resumed children left, bail. We'd be stuck
3364 forever in the sigsuspend call below otherwise. */
3365 if (iterate_over_lwps (ptid
, resumed_callback
) == NULL
)
3367 if (debug_linux_nat
)
3368 fprintf_unfiltered (gdb_stdlog
, "LLW: exit (no resumed LWP)\n");
3370 ourstatus
->kind
= TARGET_WAITKIND_NO_RESUMED
;
3372 restore_child_signals_mask (&prev_mask
);
3373 return minus_one_ptid
;
3376 /* No interesting event to report to the core. */
3378 if (target_options
& TARGET_WNOHANG
)
3380 if (debug_linux_nat
)
3381 fprintf_unfiltered (gdb_stdlog
, "LLW: exit (ignore)\n");
3383 ourstatus
->kind
= TARGET_WAITKIND_IGNORE
;
3384 restore_child_signals_mask (&prev_mask
);
3385 return minus_one_ptid
;
3388 /* We shouldn't end up here unless we want to try again. */
3389 gdb_assert (lp
== NULL
);
3391 /* Block until we get an event reported with SIGCHLD. */
3397 status
= lp
->status
;
3400 if (!target_is_non_stop_p ())
3402 /* Now stop all other LWP's ... */
3403 iterate_over_lwps (minus_one_ptid
, stop_callback
);
3405 /* ... and wait until all of them have reported back that
3406 they're no longer running. */
3407 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
3410 /* If we're not waiting for a specific LWP, choose an event LWP from
3411 among those that have had events. Giving equal priority to all
3412 LWPs that have had events helps prevent starvation. */
3413 if (ptid
== minus_one_ptid
|| ptid
.is_pid ())
3414 select_event_lwp (ptid
, &lp
, &status
);
3416 gdb_assert (lp
!= NULL
);
3418 /* Now that we've selected our final event LWP, un-adjust its PC if
3419 it was a software breakpoint, and we can't reliably support the
3420 "stopped by software breakpoint" stop reason. */
3421 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
3422 && !USE_SIGTRAP_SIGINFO
)
3424 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3425 struct gdbarch
*gdbarch
= regcache
->arch ();
3426 int decr_pc
= gdbarch_decr_pc_after_break (gdbarch
);
3432 pc
= regcache_read_pc (regcache
);
3433 regcache_write_pc (regcache
, pc
+ decr_pc
);
3437 /* We'll need this to determine whether to report a SIGSTOP as
3438 GDB_SIGNAL_0. Need to take a copy because resume_clear_callback
3440 last_resume_kind
= lp
->last_resume_kind
;
3442 if (!target_is_non_stop_p ())
3444 /* In all-stop, from the core's perspective, all LWPs are now
3445 stopped until a new resume action is sent over. */
3446 iterate_over_lwps (minus_one_ptid
, resume_clear_callback
);
3450 resume_clear_callback (lp
);
3453 if (linux_target
->low_status_is_event (status
))
3455 if (debug_linux_nat
)
3456 fprintf_unfiltered (gdb_stdlog
,
3457 "LLW: trap ptid is %s.\n",
3458 target_pid_to_str (lp
->ptid
).c_str ());
3461 if (lp
->waitstatus
.kind
!= TARGET_WAITKIND_IGNORE
)
3463 *ourstatus
= lp
->waitstatus
;
3464 lp
->waitstatus
.kind
= TARGET_WAITKIND_IGNORE
;
3467 store_waitstatus (ourstatus
, status
);
3469 if (debug_linux_nat
)
3470 fprintf_unfiltered (gdb_stdlog
, "LLW: exit\n");
3472 restore_child_signals_mask (&prev_mask
);
3474 if (last_resume_kind
== resume_stop
3475 && ourstatus
->kind
== TARGET_WAITKIND_STOPPED
3476 && WSTOPSIG (status
) == SIGSTOP
)
3478 /* A thread that has been requested to stop by GDB with
3479 target_stop, and it stopped cleanly, so report as SIG0. The
3480 use of SIGSTOP is an implementation detail. */
3481 ourstatus
->value
.sig
= GDB_SIGNAL_0
;
3484 if (ourstatus
->kind
== TARGET_WAITKIND_EXITED
3485 || ourstatus
->kind
== TARGET_WAITKIND_SIGNALLED
)
3488 lp
->core
= linux_common_core_of_thread (lp
->ptid
);
3490 if (ourstatus
->kind
== TARGET_WAITKIND_EXITED
)
3491 return filter_exit_event (lp
, ourstatus
);
3496 /* Resume LWPs that are currently stopped without any pending status
3497 to report, but are resumed from the core's perspective. */
3500 resume_stopped_resumed_lwps (struct lwp_info
*lp
, const ptid_t wait_ptid
)
3504 if (debug_linux_nat
)
3505 fprintf_unfiltered (gdb_stdlog
,
3506 "RSRL: NOT resuming LWP %s, not stopped\n",
3507 target_pid_to_str (lp
->ptid
).c_str ());
3509 else if (!lp
->resumed
)
3511 if (debug_linux_nat
)
3512 fprintf_unfiltered (gdb_stdlog
,
3513 "RSRL: NOT resuming LWP %s, not resumed\n",
3514 target_pid_to_str (lp
->ptid
).c_str ());
3516 else if (lwp_status_pending_p (lp
))
3518 if (debug_linux_nat
)
3519 fprintf_unfiltered (gdb_stdlog
,
3520 "RSRL: NOT resuming LWP %s, has pending status\n",
3521 target_pid_to_str (lp
->ptid
).c_str ());
3525 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3526 struct gdbarch
*gdbarch
= regcache
->arch ();
3530 CORE_ADDR pc
= regcache_read_pc (regcache
);
3531 int leave_stopped
= 0;
3533 /* Don't bother if there's a breakpoint at PC that we'd hit
3534 immediately, and we're not waiting for this LWP. */
3535 if (!lp
->ptid
.matches (wait_ptid
))
3537 if (breakpoint_inserted_here_p (regcache
->aspace (), pc
))
3543 if (debug_linux_nat
)
3544 fprintf_unfiltered (gdb_stdlog
,
3545 "RSRL: resuming stopped-resumed LWP %s at "
3547 target_pid_to_str (lp
->ptid
).c_str (),
3548 paddress (gdbarch
, pc
),
3551 linux_resume_one_lwp_throw (lp
, lp
->step
, GDB_SIGNAL_0
);
3554 catch (const gdb_exception_error
&ex
)
3556 if (!check_ptrace_stopped_lwp_gone (lp
))
3565 linux_nat_target::wait (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3570 if (debug_linux_nat
)
3572 std::string options_string
= target_options_to_string (target_options
);
3573 fprintf_unfiltered (gdb_stdlog
,
3574 "linux_nat_wait: [%s], [%s]\n",
3575 target_pid_to_str (ptid
).c_str (),
3576 options_string
.c_str ());
3579 /* Flush the async file first. */
3580 if (target_is_async_p ())
3581 async_file_flush ();
3583 /* Resume LWPs that are currently stopped without any pending status
3584 to report, but are resumed from the core's perspective. LWPs get
3585 in this state if we find them stopping at a time we're not
3586 interested in reporting the event (target_wait on a
3587 specific_process, for example, see linux_nat_wait_1), and
3588 meanwhile the event became uninteresting. Don't bother resuming
3589 LWPs we're not going to wait for if they'd stop immediately. */
3590 if (target_is_non_stop_p ())
3591 iterate_over_lwps (minus_one_ptid
,
3592 [=] (struct lwp_info
*info
)
3594 return resume_stopped_resumed_lwps (info
, ptid
);
3597 event_ptid
= linux_nat_wait_1 (ptid
, ourstatus
, target_options
);
3599 /* If we requested any event, and something came out, assume there
3600 may be more. If we requested a specific lwp or process, also
3601 assume there may be more. */
3602 if (target_is_async_p ()
3603 && ((ourstatus
->kind
!= TARGET_WAITKIND_IGNORE
3604 && ourstatus
->kind
!= TARGET_WAITKIND_NO_RESUMED
)
3605 || ptid
!= minus_one_ptid
))
3614 kill_one_lwp (pid_t pid
)
3616 /* PTRACE_KILL may resume the inferior. Send SIGKILL first. */
3619 kill_lwp (pid
, SIGKILL
);
3620 if (debug_linux_nat
)
3622 int save_errno
= errno
;
3624 fprintf_unfiltered (gdb_stdlog
,
3625 "KC: kill (SIGKILL) %ld, 0, 0 (%s)\n", (long) pid
,
3626 save_errno
? safe_strerror (save_errno
) : "OK");
3629 /* Some kernels ignore even SIGKILL for processes under ptrace. */
3632 ptrace (PTRACE_KILL
, pid
, 0, 0);
3633 if (debug_linux_nat
)
3635 int save_errno
= errno
;
3637 fprintf_unfiltered (gdb_stdlog
,
3638 "KC: PTRACE_KILL %ld, 0, 0 (%s)\n", (long) pid
,
3639 save_errno
? safe_strerror (save_errno
) : "OK");
3643 /* Wait for an LWP to die. */
3646 kill_wait_one_lwp (pid_t pid
)
3650 /* We must make sure that there are no pending events (delayed
3651 SIGSTOPs, pending SIGTRAPs, etc.) to make sure the current
3652 program doesn't interfere with any following debugging session. */
3656 res
= my_waitpid (pid
, NULL
, __WALL
);
3657 if (res
!= (pid_t
) -1)
3659 if (debug_linux_nat
)
3660 fprintf_unfiltered (gdb_stdlog
,
3661 "KWC: wait %ld received unknown.\n",
3663 /* The Linux kernel sometimes fails to kill a thread
3664 completely after PTRACE_KILL; that goes from the stop
3665 point in do_fork out to the one in get_signal_to_deliver
3666 and waits again. So kill it again. */
3672 gdb_assert (res
== -1 && errno
== ECHILD
);
3675 /* Callback for iterate_over_lwps. */
3678 kill_callback (struct lwp_info
*lp
)
3680 kill_one_lwp (lp
->ptid
.lwp ());
3684 /* Callback for iterate_over_lwps. */
3687 kill_wait_callback (struct lwp_info
*lp
)
3689 kill_wait_one_lwp (lp
->ptid
.lwp ());
3693 /* Kill the fork children of any threads of inferior INF that are
3694 stopped at a fork event. */
3697 kill_unfollowed_fork_children (struct inferior
*inf
)
3699 for (thread_info
*thread
: inf
->non_exited_threads ())
3701 struct target_waitstatus
*ws
= &thread
->pending_follow
;
3703 if (ws
->kind
== TARGET_WAITKIND_FORKED
3704 || ws
->kind
== TARGET_WAITKIND_VFORKED
)
3706 ptid_t child_ptid
= ws
->value
.related_pid
;
3707 int child_pid
= child_ptid
.pid ();
3708 int child_lwp
= child_ptid
.lwp ();
3710 kill_one_lwp (child_lwp
);
3711 kill_wait_one_lwp (child_lwp
);
3713 /* Let the arch-specific native code know this process is
3715 linux_target
->low_forget_process (child_pid
);
3721 linux_nat_target::kill ()
3723 /* If we're stopped while forking and we haven't followed yet,
3724 kill the other task. We need to do this first because the
3725 parent will be sleeping if this is a vfork. */
3726 kill_unfollowed_fork_children (current_inferior ());
3728 if (forks_exist_p ())
3729 linux_fork_killall ();
3732 ptid_t ptid
= ptid_t (inferior_ptid
.pid ());
3734 /* Stop all threads before killing them, since ptrace requires
3735 that the thread is stopped to successfully PTRACE_KILL. */
3736 iterate_over_lwps (ptid
, stop_callback
);
3737 /* ... and wait until all of them have reported back that
3738 they're no longer running. */
3739 iterate_over_lwps (ptid
, stop_wait_callback
);
3741 /* Kill all LWP's ... */
3742 iterate_over_lwps (ptid
, kill_callback
);
3744 /* ... and wait until we've flushed all events. */
3745 iterate_over_lwps (ptid
, kill_wait_callback
);
3748 target_mourn_inferior (inferior_ptid
);
3752 linux_nat_target::mourn_inferior ()
3754 int pid
= inferior_ptid
.pid ();
3756 purge_lwp_list (pid
);
3758 if (! forks_exist_p ())
3759 /* Normal case, no other forks available. */
3760 inf_ptrace_target::mourn_inferior ();
3762 /* Multi-fork case. The current inferior_ptid has exited, but
3763 there are other viable forks to debug. Delete the exiting
3764 one and context-switch to the first available. */
3765 linux_fork_mourn_inferior ();
3767 /* Let the arch-specific native code know this process is gone. */
3768 linux_target
->low_forget_process (pid
);
3771 /* Convert a native/host siginfo object, into/from the siginfo in the
3772 layout of the inferiors' architecture. */
3775 siginfo_fixup (siginfo_t
*siginfo
, gdb_byte
*inf_siginfo
, int direction
)
3777 /* If the low target didn't do anything, then just do a straight
3779 if (!linux_target
->low_siginfo_fixup (siginfo
, inf_siginfo
, direction
))
3782 memcpy (siginfo
, inf_siginfo
, sizeof (siginfo_t
));
3784 memcpy (inf_siginfo
, siginfo
, sizeof (siginfo_t
));
3788 static enum target_xfer_status
3789 linux_xfer_siginfo (enum target_object object
,
3790 const char *annex
, gdb_byte
*readbuf
,
3791 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3792 ULONGEST
*xfered_len
)
3796 gdb_byte inf_siginfo
[sizeof (siginfo_t
)];
3798 gdb_assert (object
== TARGET_OBJECT_SIGNAL_INFO
);
3799 gdb_assert (readbuf
|| writebuf
);
3801 pid
= inferior_ptid
.lwp ();
3803 pid
= inferior_ptid
.pid ();
3805 if (offset
> sizeof (siginfo
))
3806 return TARGET_XFER_E_IO
;
3809 ptrace (PTRACE_GETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, &siginfo
);
3811 return TARGET_XFER_E_IO
;
3813 /* When GDB is built as a 64-bit application, ptrace writes into
3814 SIGINFO an object with 64-bit layout. Since debugging a 32-bit
3815 inferior with a 64-bit GDB should look the same as debugging it
3816 with a 32-bit GDB, we need to convert it. GDB core always sees
3817 the converted layout, so any read/write will have to be done
3819 siginfo_fixup (&siginfo
, inf_siginfo
, 0);
3821 if (offset
+ len
> sizeof (siginfo
))
3822 len
= sizeof (siginfo
) - offset
;
3824 if (readbuf
!= NULL
)
3825 memcpy (readbuf
, inf_siginfo
+ offset
, len
);
3828 memcpy (inf_siginfo
+ offset
, writebuf
, len
);
3830 /* Convert back to ptrace layout before flushing it out. */
3831 siginfo_fixup (&siginfo
, inf_siginfo
, 1);
3834 ptrace (PTRACE_SETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, &siginfo
);
3836 return TARGET_XFER_E_IO
;
3840 return TARGET_XFER_OK
;
3843 static enum target_xfer_status
3844 linux_nat_xfer_osdata (enum target_object object
,
3845 const char *annex
, gdb_byte
*readbuf
,
3846 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3847 ULONGEST
*xfered_len
);
3849 static enum target_xfer_status
3850 linux_proc_xfer_partial (enum target_object object
,
3851 const char *annex
, gdb_byte
*readbuf
,
3852 const gdb_byte
*writebuf
,
3853 ULONGEST offset
, LONGEST len
, ULONGEST
*xfered_len
);
3855 enum target_xfer_status
3856 linux_nat_target::xfer_partial (enum target_object object
,
3857 const char *annex
, gdb_byte
*readbuf
,
3858 const gdb_byte
*writebuf
,
3859 ULONGEST offset
, ULONGEST len
, ULONGEST
*xfered_len
)
3861 enum target_xfer_status xfer
;
3863 if (object
== TARGET_OBJECT_SIGNAL_INFO
)
3864 return linux_xfer_siginfo (object
, annex
, readbuf
, writebuf
,
3865 offset
, len
, xfered_len
);
3867 /* The target is connected but no live inferior is selected. Pass
3868 this request down to a lower stratum (e.g., the executable
3870 if (object
== TARGET_OBJECT_MEMORY
&& inferior_ptid
== null_ptid
)
3871 return TARGET_XFER_EOF
;
3873 if (object
== TARGET_OBJECT_AUXV
)
3874 return memory_xfer_auxv (this, object
, annex
, readbuf
, writebuf
,
3875 offset
, len
, xfered_len
);
3877 if (object
== TARGET_OBJECT_OSDATA
)
3878 return linux_nat_xfer_osdata (object
, annex
, readbuf
, writebuf
,
3879 offset
, len
, xfered_len
);
3881 /* GDB calculates all addresses in the largest possible address
3883 The address width must be masked before its final use - either by
3884 linux_proc_xfer_partial or inf_ptrace_target::xfer_partial.
3886 Compare ADDR_BIT first to avoid a compiler warning on shift overflow. */
3888 if (object
== TARGET_OBJECT_MEMORY
)
3890 int addr_bit
= gdbarch_addr_bit (target_gdbarch ());
3892 if (addr_bit
< (sizeof (ULONGEST
) * HOST_CHAR_BIT
))
3893 offset
&= ((ULONGEST
) 1 << addr_bit
) - 1;
3896 xfer
= linux_proc_xfer_partial (object
, annex
, readbuf
, writebuf
,
3897 offset
, len
, xfered_len
);
3898 if (xfer
!= TARGET_XFER_EOF
)
3901 return inf_ptrace_target::xfer_partial (object
, annex
, readbuf
, writebuf
,
3902 offset
, len
, xfered_len
);
3906 linux_nat_target::thread_alive (ptid_t ptid
)
3908 /* As long as a PTID is in lwp list, consider it alive. */
3909 return find_lwp_pid (ptid
) != NULL
;
3912 /* Implement the to_update_thread_list target method for this
3916 linux_nat_target::update_thread_list ()
3918 struct lwp_info
*lwp
;
3920 /* We add/delete threads from the list as clone/exit events are
3921 processed, so just try deleting exited threads still in the
3923 delete_exited_threads ();
3925 /* Update the processor core that each lwp/thread was last seen
3929 /* Avoid accessing /proc if the thread hasn't run since we last
3930 time we fetched the thread's core. Accessing /proc becomes
3931 noticeably expensive when we have thousands of LWPs. */
3932 if (lwp
->core
== -1)
3933 lwp
->core
= linux_common_core_of_thread (lwp
->ptid
);
3938 linux_nat_target::pid_to_str (ptid_t ptid
)
3941 && (ptid
.pid () != ptid
.lwp ()
3942 || num_lwps (ptid
.pid ()) > 1))
3943 return string_printf ("LWP %ld", ptid
.lwp ());
3945 return normal_pid_to_str (ptid
);
3949 linux_nat_target::thread_name (struct thread_info
*thr
)
3951 return linux_proc_tid_get_name (thr
->ptid
);
3954 /* Accepts an integer PID; Returns a string representing a file that
3955 can be opened to get the symbols for the child process. */
3958 linux_nat_target::pid_to_exec_file (int pid
)
3960 return linux_proc_pid_to_exec_file (pid
);
3963 /* Implement the to_xfer_partial target method using /proc/<pid>/mem.
3964 Because we can use a single read/write call, this can be much more
3965 efficient than banging away at PTRACE_PEEKTEXT. */
3967 static enum target_xfer_status
3968 linux_proc_xfer_partial (enum target_object object
,
3969 const char *annex
, gdb_byte
*readbuf
,
3970 const gdb_byte
*writebuf
,
3971 ULONGEST offset
, LONGEST len
, ULONGEST
*xfered_len
)
3977 if (object
!= TARGET_OBJECT_MEMORY
)
3978 return TARGET_XFER_EOF
;
3980 /* Don't bother for one word. */
3981 if (len
< 3 * sizeof (long))
3982 return TARGET_XFER_EOF
;
3984 /* We could keep this file open and cache it - possibly one per
3985 thread. That requires some juggling, but is even faster. */
3986 xsnprintf (filename
, sizeof filename
, "/proc/%ld/mem",
3987 inferior_ptid
.lwp ());
3988 fd
= gdb_open_cloexec (filename
, ((readbuf
? O_RDONLY
: O_WRONLY
)
3991 return TARGET_XFER_EOF
;
3993 /* Use pread64/pwrite64 if available, since they save a syscall and can
3994 handle 64-bit offsets even on 32-bit platforms (for instance, SPARC
3995 debugging a SPARC64 application). */
3997 ret
= (readbuf
? pread64 (fd
, readbuf
, len
, offset
)
3998 : pwrite64 (fd
, writebuf
, len
, offset
));
4000 ret
= lseek (fd
, offset
, SEEK_SET
);
4002 ret
= (readbuf
? read (fd
, readbuf
, len
)
4003 : write (fd
, writebuf
, len
));
4008 if (ret
== -1 || ret
== 0)
4009 return TARGET_XFER_EOF
;
4013 return TARGET_XFER_OK
;
4018 /* Parse LINE as a signal set and add its set bits to SIGS. */
4021 add_line_to_sigset (const char *line
, sigset_t
*sigs
)
4023 int len
= strlen (line
) - 1;
4027 if (line
[len
] != '\n')
4028 error (_("Could not parse signal set: %s"), line
);
4036 if (*p
>= '0' && *p
<= '9')
4038 else if (*p
>= 'a' && *p
<= 'f')
4039 digit
= *p
- 'a' + 10;
4041 error (_("Could not parse signal set: %s"), line
);
4046 sigaddset (sigs
, signum
+ 1);
4048 sigaddset (sigs
, signum
+ 2);
4050 sigaddset (sigs
, signum
+ 3);
4052 sigaddset (sigs
, signum
+ 4);
4058 /* Find process PID's pending signals from /proc/pid/status and set
4062 linux_proc_pending_signals (int pid
, sigset_t
*pending
,
4063 sigset_t
*blocked
, sigset_t
*ignored
)
4065 char buffer
[PATH_MAX
], fname
[PATH_MAX
];
4067 sigemptyset (pending
);
4068 sigemptyset (blocked
);
4069 sigemptyset (ignored
);
4070 xsnprintf (fname
, sizeof fname
, "/proc/%d/status", pid
);
4071 gdb_file_up procfile
= gdb_fopen_cloexec (fname
, "r");
4072 if (procfile
== NULL
)
4073 error (_("Could not open %s"), fname
);
4075 while (fgets (buffer
, PATH_MAX
, procfile
.get ()) != NULL
)
4077 /* Normal queued signals are on the SigPnd line in the status
4078 file. However, 2.6 kernels also have a "shared" pending
4079 queue for delivering signals to a thread group, so check for
4082 Unfortunately some Red Hat kernels include the shared pending
4083 queue but not the ShdPnd status field. */
4085 if (startswith (buffer
, "SigPnd:\t"))
4086 add_line_to_sigset (buffer
+ 8, pending
);
4087 else if (startswith (buffer
, "ShdPnd:\t"))
4088 add_line_to_sigset (buffer
+ 8, pending
);
4089 else if (startswith (buffer
, "SigBlk:\t"))
4090 add_line_to_sigset (buffer
+ 8, blocked
);
4091 else if (startswith (buffer
, "SigIgn:\t"))
4092 add_line_to_sigset (buffer
+ 8, ignored
);
4096 static enum target_xfer_status
4097 linux_nat_xfer_osdata (enum target_object object
,
4098 const char *annex
, gdb_byte
*readbuf
,
4099 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
4100 ULONGEST
*xfered_len
)
4102 gdb_assert (object
== TARGET_OBJECT_OSDATA
);
4104 *xfered_len
= linux_common_xfer_osdata (annex
, readbuf
, offset
, len
);
4105 if (*xfered_len
== 0)
4106 return TARGET_XFER_EOF
;
4108 return TARGET_XFER_OK
;
4111 std::vector
<static_tracepoint_marker
>
4112 linux_nat_target::static_tracepoint_markers_by_strid (const char *strid
)
4114 char s
[IPA_CMD_BUF_SIZE
];
4115 int pid
= inferior_ptid
.pid ();
4116 std::vector
<static_tracepoint_marker
> markers
;
4118 ptid_t ptid
= ptid_t (pid
, 0, 0);
4119 static_tracepoint_marker marker
;
4124 memcpy (s
, "qTfSTM", sizeof ("qTfSTM"));
4125 s
[sizeof ("qTfSTM")] = 0;
4127 agent_run_command (pid
, s
, strlen (s
) + 1);
4130 SCOPE_EXIT
{ target_continue_no_signal (ptid
); };
4136 parse_static_tracepoint_marker_definition (p
, &p
, &marker
);
4138 if (strid
== NULL
|| marker
.str_id
== strid
)
4139 markers
.push_back (std::move (marker
));
4141 while (*p
++ == ','); /* comma-separated list */
4143 memcpy (s
, "qTsSTM", sizeof ("qTsSTM"));
4144 s
[sizeof ("qTsSTM")] = 0;
4145 agent_run_command (pid
, s
, strlen (s
) + 1);
4152 /* target_is_async_p implementation. */
4155 linux_nat_target::is_async_p ()
4157 return linux_is_async_p ();
4160 /* target_can_async_p implementation. */
4163 linux_nat_target::can_async_p ()
4165 /* We're always async, unless the user explicitly prevented it with the
4166 "maint set target-async" command. */
4167 return target_async_permitted
;
4171 linux_nat_target::supports_non_stop ()
4176 /* to_always_non_stop_p implementation. */
4179 linux_nat_target::always_non_stop_p ()
4184 /* True if we want to support multi-process. To be removed when GDB
4185 supports multi-exec. */
4187 int linux_multi_process
= 1;
4190 linux_nat_target::supports_multi_process ()
4192 return linux_multi_process
;
4196 linux_nat_target::supports_disable_randomization ()
4198 #ifdef HAVE_PERSONALITY
4205 /* SIGCHLD handler that serves two purposes: In non-stop/async mode,
4206 so we notice when any child changes state, and notify the
4207 event-loop; it allows us to use sigsuspend in linux_nat_wait_1
4208 above to wait for the arrival of a SIGCHLD. */
4211 sigchld_handler (int signo
)
4213 int old_errno
= errno
;
4215 if (debug_linux_nat
)
4216 ui_file_write_async_safe (gdb_stdlog
,
4217 "sigchld\n", sizeof ("sigchld\n") - 1);
4219 if (signo
== SIGCHLD
4220 && linux_nat_event_pipe
[0] != -1)
4221 async_file_mark (); /* Let the event loop know that there are
4222 events to handle. */
4227 /* Callback registered with the target events file descriptor. */
4230 handle_target_event (int error
, gdb_client_data client_data
)
4232 inferior_event_handler (INF_REG_EVENT
, NULL
);
4235 /* Create/destroy the target events pipe. Returns previous state. */
4238 linux_async_pipe (int enable
)
4240 int previous
= linux_is_async_p ();
4242 if (previous
!= enable
)
4246 /* Block child signals while we create/destroy the pipe, as
4247 their handler writes to it. */
4248 block_child_signals (&prev_mask
);
4252 if (gdb_pipe_cloexec (linux_nat_event_pipe
) == -1)
4253 internal_error (__FILE__
, __LINE__
,
4254 "creating event pipe failed.");
4256 fcntl (linux_nat_event_pipe
[0], F_SETFL
, O_NONBLOCK
);
4257 fcntl (linux_nat_event_pipe
[1], F_SETFL
, O_NONBLOCK
);
4261 close (linux_nat_event_pipe
[0]);
4262 close (linux_nat_event_pipe
[1]);
4263 linux_nat_event_pipe
[0] = -1;
4264 linux_nat_event_pipe
[1] = -1;
4267 restore_child_signals_mask (&prev_mask
);
4274 linux_nat_target::async_wait_fd ()
4276 return linux_nat_event_pipe
[0];
4279 /* target_async implementation. */
4282 linux_nat_target::async (int enable
)
4286 if (!linux_async_pipe (1))
4288 add_file_handler (linux_nat_event_pipe
[0],
4289 handle_target_event
, NULL
);
4290 /* There may be pending events to handle. Tell the event loop
4297 delete_file_handler (linux_nat_event_pipe
[0]);
4298 linux_async_pipe (0);
4303 /* Stop an LWP, and push a GDB_SIGNAL_0 stop status if no other
4307 linux_nat_stop_lwp (struct lwp_info
*lwp
)
4311 if (debug_linux_nat
)
4312 fprintf_unfiltered (gdb_stdlog
,
4313 "LNSL: running -> suspending %s\n",
4314 target_pid_to_str (lwp
->ptid
).c_str ());
4317 if (lwp
->last_resume_kind
== resume_stop
)
4319 if (debug_linux_nat
)
4320 fprintf_unfiltered (gdb_stdlog
,
4321 "linux-nat: already stopping LWP %ld at "
4327 stop_callback (lwp
);
4328 lwp
->last_resume_kind
= resume_stop
;
4332 /* Already known to be stopped; do nothing. */
4334 if (debug_linux_nat
)
4336 if (find_thread_ptid (linux_target
, lwp
->ptid
)->stop_requested
)
4337 fprintf_unfiltered (gdb_stdlog
,
4338 "LNSL: already stopped/stop_requested %s\n",
4339 target_pid_to_str (lwp
->ptid
).c_str ());
4341 fprintf_unfiltered (gdb_stdlog
,
4342 "LNSL: already stopped/no "
4343 "stop_requested yet %s\n",
4344 target_pid_to_str (lwp
->ptid
).c_str ());
4351 linux_nat_target::stop (ptid_t ptid
)
4353 iterate_over_lwps (ptid
, linux_nat_stop_lwp
);
4357 linux_nat_target::close ()
4359 /* Unregister from the event loop. */
4363 inf_ptrace_target::close ();
4366 /* When requests are passed down from the linux-nat layer to the
4367 single threaded inf-ptrace layer, ptids of (lwpid,0,0) form are
4368 used. The address space pointer is stored in the inferior object,
4369 but the common code that is passed such ptid can't tell whether
4370 lwpid is a "main" process id or not (it assumes so). We reverse
4371 look up the "main" process id from the lwp here. */
4373 struct address_space
*
4374 linux_nat_target::thread_address_space (ptid_t ptid
)
4376 struct lwp_info
*lwp
;
4377 struct inferior
*inf
;
4380 if (ptid
.lwp () == 0)
4382 /* An (lwpid,0,0) ptid. Look up the lwp object to get at the
4384 lwp
= find_lwp_pid (ptid
);
4385 pid
= lwp
->ptid
.pid ();
4389 /* A (pid,lwpid,0) ptid. */
4393 inf
= find_inferior_pid (this, pid
);
4394 gdb_assert (inf
!= NULL
);
4398 /* Return the cached value of the processor core for thread PTID. */
4401 linux_nat_target::core_of_thread (ptid_t ptid
)
4403 struct lwp_info
*info
= find_lwp_pid (ptid
);
4410 /* Implementation of to_filesystem_is_local. */
4413 linux_nat_target::filesystem_is_local ()
4415 struct inferior
*inf
= current_inferior ();
4417 if (inf
->fake_pid_p
|| inf
->pid
== 0)
4420 return linux_ns_same (inf
->pid
, LINUX_NS_MNT
);
4423 /* Convert the INF argument passed to a to_fileio_* method
4424 to a process ID suitable for passing to its corresponding
4425 linux_mntns_* function. If INF is non-NULL then the
4426 caller is requesting the filesystem seen by INF. If INF
4427 is NULL then the caller is requesting the filesystem seen
4428 by the GDB. We fall back to GDB's filesystem in the case
4429 that INF is non-NULL but its PID is unknown. */
4432 linux_nat_fileio_pid_of (struct inferior
*inf
)
4434 if (inf
== NULL
|| inf
->fake_pid_p
|| inf
->pid
== 0)
4440 /* Implementation of to_fileio_open. */
4443 linux_nat_target::fileio_open (struct inferior
*inf
, const char *filename
,
4444 int flags
, int mode
, int warn_if_slow
,
4451 if (fileio_to_host_openflags (flags
, &nat_flags
) == -1
4452 || fileio_to_host_mode (mode
, &nat_mode
) == -1)
4454 *target_errno
= FILEIO_EINVAL
;
4458 fd
= linux_mntns_open_cloexec (linux_nat_fileio_pid_of (inf
),
4459 filename
, nat_flags
, nat_mode
);
4461 *target_errno
= host_to_fileio_error (errno
);
4466 /* Implementation of to_fileio_readlink. */
4468 gdb::optional
<std::string
>
4469 linux_nat_target::fileio_readlink (struct inferior
*inf
, const char *filename
,
4475 len
= linux_mntns_readlink (linux_nat_fileio_pid_of (inf
),
4476 filename
, buf
, sizeof (buf
));
4479 *target_errno
= host_to_fileio_error (errno
);
4483 return std::string (buf
, len
);
4486 /* Implementation of to_fileio_unlink. */
4489 linux_nat_target::fileio_unlink (struct inferior
*inf
, const char *filename
,
4494 ret
= linux_mntns_unlink (linux_nat_fileio_pid_of (inf
),
4497 *target_errno
= host_to_fileio_error (errno
);
4502 /* Implementation of the to_thread_events method. */
4505 linux_nat_target::thread_events (int enable
)
4507 report_thread_events
= enable
;
4510 linux_nat_target::linux_nat_target ()
4512 /* We don't change the stratum; this target will sit at
4513 process_stratum and thread_db will set at thread_stratum. This
4514 is a little strange, since this is a multi-threaded-capable
4515 target, but we want to be on the stack below thread_db, and we
4516 also want to be used for single-threaded processes. */
4519 /* See linux-nat.h. */
4522 linux_nat_get_siginfo (ptid_t ptid
, siginfo_t
*siginfo
)
4531 ptrace (PTRACE_GETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, siginfo
);
4534 memset (siginfo
, 0, sizeof (*siginfo
));
4540 /* See nat/linux-nat.h. */
4543 current_lwp_ptid (void)
4545 gdb_assert (inferior_ptid
.lwp_p ());
4546 return inferior_ptid
;
4549 void _initialize_linux_nat ();
4551 _initialize_linux_nat ()
4553 add_setshow_zuinteger_cmd ("lin-lwp", class_maintenance
,
4554 &debug_linux_nat
, _("\
4555 Set debugging of GNU/Linux lwp module."), _("\
4556 Show debugging of GNU/Linux lwp module."), _("\
4557 Enables printf debugging output."),
4559 show_debug_linux_nat
,
4560 &setdebuglist
, &showdebuglist
);
4562 add_setshow_boolean_cmd ("linux-namespaces", class_maintenance
,
4563 &debug_linux_namespaces
, _("\
4564 Set debugging of GNU/Linux namespaces module."), _("\
4565 Show debugging of GNU/Linux namespaces module."), _("\
4566 Enables printf debugging output."),
4569 &setdebuglist
, &showdebuglist
);
4571 /* Install a SIGCHLD handler. */
4572 sigchld_action
.sa_handler
= sigchld_handler
;
4573 sigemptyset (&sigchld_action
.sa_mask
);
4574 sigchld_action
.sa_flags
= SA_RESTART
;
4576 /* Make it the default. */
4577 sigaction (SIGCHLD
, &sigchld_action
, NULL
);
4579 /* Make sure we don't block SIGCHLD during a sigsuspend. */
4580 gdb_sigmask (SIG_SETMASK
, NULL
, &suspend_mask
);
4581 sigdelset (&suspend_mask
, SIGCHLD
);
4583 sigemptyset (&blocked_mask
);
4585 lwp_lwpid_htab_create ();
4589 /* FIXME: kettenis/2000-08-26: The stuff on this page is specific to
4590 the GNU/Linux Threads library and therefore doesn't really belong
4593 /* Return the set of signals used by the threads library in *SET. */
4596 lin_thread_get_thread_signals (sigset_t
*set
)
4600 /* NPTL reserves the first two RT signals, but does not provide any
4601 way for the debugger to query the signal numbers - fortunately
4602 they don't change. */
4603 sigaddset (set
, __SIGRTMIN
);
4604 sigaddset (set
, __SIGRTMIN
+ 1);