1 /* GNU/Linux native-dependent code common to multiple platforms.
3 Copyright (C) 2001-2021 Free Software Foundation, Inc.
5 This file is part of GDB.
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>. */
24 #include "nat/linux-nat.h"
25 #include "nat/linux-waitpid.h"
26 #include "gdbsupport/gdb_wait.h"
28 #include <sys/syscall.h>
29 #include "nat/gdb_ptrace.h"
30 #include "linux-nat.h"
31 #include "nat/linux-ptrace.h"
32 #include "nat/linux-procfs.h"
33 #include "nat/linux-personality.h"
34 #include "linux-fork.h"
35 #include "gdbthread.h"
39 #include "inf-child.h"
40 #include "inf-ptrace.h"
42 #include <sys/procfs.h> /* for elf_gregset etc. */
43 #include "elf-bfd.h" /* for elfcore_write_* */
44 #include "gregset.h" /* for gregset */
45 #include "gdbcore.h" /* for get_exec_file */
46 #include <ctype.h> /* for isdigit */
47 #include <sys/stat.h> /* for struct stat */
48 #include <fcntl.h> /* for O_RDONLY */
50 #include "gdbsupport/event-loop.h"
51 #include "event-top.h"
53 #include <sys/types.h>
55 #include "xml-support.h"
58 #include "nat/linux-osdata.h"
59 #include "linux-tdep.h"
61 #include "gdbsupport/agent.h"
62 #include "tracepoint.h"
63 #include "gdbsupport/buffer.h"
64 #include "target-descriptions.h"
65 #include "gdbsupport/filestuff.h"
67 #include "nat/linux-namespaces.h"
68 #include "gdbsupport/fileio.h"
69 #include "gdbsupport/scope-exit.h"
70 #include "gdbsupport/gdb-sigmask.h"
71 #include "gdbsupport/common-debug.h"
73 /* This comment documents high-level logic of this file.
75 Waiting for events in sync mode
76 ===============================
78 When waiting for an event in a specific thread, we just use waitpid,
79 passing the specific pid, and not passing WNOHANG.
81 When waiting for an event in all threads, waitpid is not quite good:
83 - If the thread group leader exits while other threads in the thread
84 group still exist, waitpid(TGID, ...) hangs. That waitpid won't
85 return an exit status until the other threads in the group are
88 - When a non-leader thread execs, that thread just vanishes without
89 reporting an exit (so we'd hang if we waited for it explicitly in
90 that case). The exec event is instead reported to the TGID pid.
92 The solution is to always use -1 and WNOHANG, together with
95 First, we use non-blocking waitpid to check for events. If nothing is
96 found, we use sigsuspend to wait for SIGCHLD. When SIGCHLD arrives,
97 it means something happened to a child process. As soon as we know
98 there's an event, we get back to calling nonblocking waitpid.
100 Note that SIGCHLD should be blocked between waitpid and sigsuspend
101 calls, so that we don't miss a signal. If SIGCHLD arrives in between,
102 when it's blocked, the signal becomes pending and sigsuspend
103 immediately notices it and returns.
105 Waiting for events in async mode (TARGET_WNOHANG)
106 =================================================
108 In async mode, GDB should always be ready to handle both user input
109 and target events, so neither blocking waitpid nor sigsuspend are
110 viable options. Instead, we should asynchronously notify the GDB main
111 event loop whenever there's an unprocessed event from the target. We
112 detect asynchronous target events by handling SIGCHLD signals. To
113 notify the event loop about target events, the self-pipe trick is used
114 --- a pipe is registered as waitable event source in the event loop,
115 the event loop select/poll's on the read end of this pipe (as well on
116 other event sources, e.g., stdin), and the SIGCHLD handler writes a
117 byte to this pipe. This is more portable than relying on
118 pselect/ppoll, since on kernels that lack those syscalls, libc
119 emulates them with select/poll+sigprocmask, and that is racy
120 (a.k.a. plain broken).
122 Obviously, if we fail to notify the event loop if there's a target
123 event, it's bad. OTOH, if we notify the event loop when there's no
124 event from the target, linux_nat_wait will detect that there's no real
125 event to report, and return event of type TARGET_WAITKIND_IGNORE.
126 This is mostly harmless, but it will waste time and is better avoided.
128 The main design point is that every time GDB is outside linux-nat.c,
129 we have a SIGCHLD handler installed that is called when something
130 happens to the target and notifies the GDB event loop. Whenever GDB
131 core decides to handle the event, and calls into linux-nat.c, we
132 process things as in sync mode, except that the we never block in
135 While processing an event, we may end up momentarily blocked in
136 waitpid calls. Those waitpid calls, while blocking, are guarantied to
137 return quickly. E.g., in all-stop mode, before reporting to the core
138 that an LWP hit a breakpoint, all LWPs are stopped by sending them
139 SIGSTOP, and synchronously waiting for the SIGSTOP to be reported.
140 Note that this is different from blocking indefinitely waiting for the
141 next event --- here, we're already handling an event.
146 We stop threads by sending a SIGSTOP. The use of SIGSTOP instead of another
147 signal is not entirely significant; we just need for a signal to be delivered,
148 so that we can intercept it. SIGSTOP's advantage is that it can not be
149 blocked. A disadvantage is that it is not a real-time signal, so it can only
150 be queued once; we do not keep track of other sources of SIGSTOP.
152 Two other signals that can't be blocked are SIGCONT and SIGKILL. But we can't
153 use them, because they have special behavior when the signal is generated -
154 not when it is delivered. SIGCONT resumes the entire thread group and SIGKILL
155 kills the entire thread group.
157 A delivered SIGSTOP would stop the entire thread group, not just the thread we
158 tkill'd. But we never let the SIGSTOP be delivered; we always intercept and
159 cancel it (by PTRACE_CONT without passing SIGSTOP).
161 We could use a real-time signal instead. This would solve those problems; we
162 could use PTRACE_GETSIGINFO to locate the specific stop signals sent by GDB.
163 But we would still have to have some support for SIGSTOP, since PTRACE_ATTACH
164 generates it, and there are races with trying to find a signal that is not
170 The case of a thread group (process) with 3 or more threads, and a
171 thread other than the leader execs is worth detailing:
173 On an exec, the Linux kernel destroys all threads except the execing
174 one in the thread group, and resets the execing thread's tid to the
175 tgid. No exit notification is sent for the execing thread -- from the
176 ptracer's perspective, it appears as though the execing thread just
177 vanishes. Until we reap all other threads except the leader and the
178 execing thread, the leader will be zombie, and the execing thread will
179 be in `D (disc sleep)' state. As soon as all other threads are
180 reaped, the execing thread changes its tid to the tgid, and the
181 previous (zombie) leader vanishes, giving place to the "new"
185 #define O_LARGEFILE 0
188 struct linux_nat_target
*linux_target
;
190 /* Does the current host support PTRACE_GETREGSET? */
191 enum tribool have_ptrace_getregset
= TRIBOOL_UNKNOWN
;
193 static unsigned int debug_linux_nat
;
195 show_debug_linux_nat (struct ui_file
*file
, int from_tty
,
196 struct cmd_list_element
*c
, const char *value
)
198 fprintf_filtered (file
, _("Debugging of GNU/Linux lwp module is %s.\n"),
202 /* Print a linux-nat debug statement. */
204 #define linux_nat_debug_printf(fmt, ...) \
205 debug_prefixed_printf_cond (debug_linux_nat, "linux-nat", fmt, ##__VA_ARGS__)
207 struct simple_pid_list
211 struct simple_pid_list
*next
;
213 static struct simple_pid_list
*stopped_pids
;
215 /* Whether target_thread_events is in effect. */
216 static int report_thread_events
;
218 /* Async mode support. */
220 /* The read/write ends of the pipe registered as waitable file in the
222 static int linux_nat_event_pipe
[2] = { -1, -1 };
224 /* True if we're currently in async mode. */
225 #define linux_is_async_p() (linux_nat_event_pipe[0] != -1)
227 /* Flush the event pipe. */
230 async_file_flush (void)
237 ret
= read (linux_nat_event_pipe
[0], &buf
, 1);
239 while (ret
>= 0 || (ret
== -1 && errno
== EINTR
));
242 /* Put something (anything, doesn't matter what, or how much) in event
243 pipe, so that the select/poll in the event-loop realizes we have
244 something to process. */
247 async_file_mark (void)
251 /* It doesn't really matter what the pipe contains, as long we end
252 up with something in it. Might as well flush the previous
258 ret
= write (linux_nat_event_pipe
[1], "+", 1);
260 while (ret
== -1 && errno
== EINTR
);
262 /* Ignore EAGAIN. If the pipe is full, the event loop will already
263 be awakened anyway. */
266 static int kill_lwp (int lwpid
, int signo
);
268 static int stop_callback (struct lwp_info
*lp
);
270 static void block_child_signals (sigset_t
*prev_mask
);
271 static void restore_child_signals_mask (sigset_t
*prev_mask
);
274 static struct lwp_info
*add_lwp (ptid_t ptid
);
275 static void purge_lwp_list (int pid
);
276 static void delete_lwp (ptid_t ptid
);
277 static struct lwp_info
*find_lwp_pid (ptid_t ptid
);
279 static int lwp_status_pending_p (struct lwp_info
*lp
);
281 static void save_stop_reason (struct lwp_info
*lp
);
283 static void maybe_close_proc_mem_file (pid_t pid
);
288 /* See nat/linux-nat.h. */
291 ptid_of_lwp (struct lwp_info
*lwp
)
296 /* See nat/linux-nat.h. */
299 lwp_set_arch_private_info (struct lwp_info
*lwp
,
300 struct arch_lwp_info
*info
)
302 lwp
->arch_private
= info
;
305 /* See nat/linux-nat.h. */
307 struct arch_lwp_info
*
308 lwp_arch_private_info (struct lwp_info
*lwp
)
310 return lwp
->arch_private
;
313 /* See nat/linux-nat.h. */
316 lwp_is_stopped (struct lwp_info
*lwp
)
321 /* See nat/linux-nat.h. */
323 enum target_stop_reason
324 lwp_stop_reason (struct lwp_info
*lwp
)
326 return lwp
->stop_reason
;
329 /* See nat/linux-nat.h. */
332 lwp_is_stepping (struct lwp_info
*lwp
)
338 /* Trivial list manipulation functions to keep track of a list of
339 new stopped processes. */
341 add_to_pid_list (struct simple_pid_list
**listp
, int pid
, int status
)
343 struct simple_pid_list
*new_pid
= XNEW (struct simple_pid_list
);
346 new_pid
->status
= status
;
347 new_pid
->next
= *listp
;
352 pull_pid_from_list (struct simple_pid_list
**listp
, int pid
, int *statusp
)
354 struct simple_pid_list
**p
;
356 for (p
= listp
; *p
!= NULL
; p
= &(*p
)->next
)
357 if ((*p
)->pid
== pid
)
359 struct simple_pid_list
*next
= (*p
)->next
;
361 *statusp
= (*p
)->status
;
369 /* Return the ptrace options that we want to try to enable. */
372 linux_nat_ptrace_options (int attached
)
377 options
|= PTRACE_O_EXITKILL
;
379 options
|= (PTRACE_O_TRACESYSGOOD
380 | PTRACE_O_TRACEVFORKDONE
381 | PTRACE_O_TRACEVFORK
383 | PTRACE_O_TRACEEXEC
);
388 /* Initialize ptrace and procfs warnings and check for supported
389 ptrace features given PID.
391 ATTACHED should be nonzero iff we attached to the inferior. */
394 linux_init_ptrace_procfs (pid_t pid
, int attached
)
396 int options
= linux_nat_ptrace_options (attached
);
398 linux_enable_event_reporting (pid
, options
);
399 linux_ptrace_init_warnings ();
400 linux_proc_init_warnings ();
403 linux_nat_target::~linux_nat_target ()
407 linux_nat_target::post_attach (int pid
)
409 linux_init_ptrace_procfs (pid
, 1);
413 linux_nat_target::post_startup_inferior (ptid_t ptid
)
415 linux_init_ptrace_procfs (ptid
.pid (), 0);
418 /* Return the number of known LWPs in the tgid given by PID. */
426 for (lp
= lwp_list
; lp
; lp
= lp
->next
)
427 if (lp
->ptid
.pid () == pid
)
433 /* Deleter for lwp_info unique_ptr specialisation. */
437 void operator() (struct lwp_info
*lwp
) const
439 delete_lwp (lwp
->ptid
);
443 /* A unique_ptr specialisation for lwp_info. */
445 typedef std::unique_ptr
<struct lwp_info
, lwp_deleter
> lwp_info_up
;
447 /* Target hook for follow_fork. On entry inferior_ptid must be the
448 ptid of the followed inferior. At return, inferior_ptid will be
452 linux_nat_target::follow_fork (bool follow_child
, bool detach_fork
)
456 struct lwp_info
*child_lp
= NULL
;
458 ptid_t parent_ptid
, child_ptid
;
459 int parent_pid
, child_pid
;
461 has_vforked
= (inferior_thread ()->pending_follow
.kind
462 == TARGET_WAITKIND_VFORKED
);
463 parent_ptid
= inferior_ptid
;
464 child_ptid
= inferior_thread ()->pending_follow
.value
.related_pid
;
465 parent_pid
= parent_ptid
.lwp ();
466 child_pid
= child_ptid
.lwp ();
468 /* We're already attached to the parent, by default. */
469 child_lp
= add_lwp (child_ptid
);
470 child_lp
->stopped
= 1;
471 child_lp
->last_resume_kind
= resume_stop
;
473 /* Detach new forked process? */
476 int child_stop_signal
= 0;
477 bool detach_child
= true;
479 /* Move CHILD_LP into a unique_ptr and clear the source pointer
480 to prevent us doing anything stupid with it. */
481 lwp_info_up
child_lp_ptr (child_lp
);
484 linux_target
->low_prepare_to_resume (child_lp_ptr
.get ());
486 /* When debugging an inferior in an architecture that supports
487 hardware single stepping on a kernel without commit
488 6580807da14c423f0d0a708108e6df6ebc8bc83d, the vfork child
489 process starts with the TIF_SINGLESTEP/X86_EFLAGS_TF bits
490 set if the parent process had them set.
491 To work around this, single step the child process
492 once before detaching to clear the flags. */
494 /* Note that we consult the parent's architecture instead of
495 the child's because there's no inferior for the child at
497 if (!gdbarch_software_single_step_p (target_thread_architecture
502 linux_disable_event_reporting (child_pid
);
503 if (ptrace (PTRACE_SINGLESTEP
, child_pid
, 0, 0) < 0)
504 perror_with_name (_("Couldn't do single step"));
505 if (my_waitpid (child_pid
, &status
, 0) < 0)
506 perror_with_name (_("Couldn't wait vfork process"));
509 detach_child
= WIFSTOPPED (status
);
510 child_stop_signal
= WSTOPSIG (status
);
516 int signo
= child_stop_signal
;
519 && !signal_pass_state (gdb_signal_from_host (signo
)))
521 ptrace (PTRACE_DETACH
, child_pid
, 0, signo
);
526 /* Switching inferior_ptid is not enough, because then
527 inferior_thread () would crash by not finding the thread
528 in the current inferior. */
529 scoped_restore_current_thread restore_current_thread
;
530 thread_info
*child
= find_thread_ptid (this, child_ptid
);
531 switch_to_thread (child
);
533 /* Let the thread_db layer learn about this new process. */
534 check_for_thread_db ();
539 struct lwp_info
*parent_lp
;
541 parent_lp
= find_lwp_pid (parent_ptid
);
542 gdb_assert (linux_supports_tracefork () >= 0);
544 if (linux_supports_tracevforkdone ())
546 linux_nat_debug_printf ("waiting for VFORK_DONE on %d",
548 parent_lp
->stopped
= 1;
550 /* We'll handle the VFORK_DONE event like any other
551 event, in target_wait. */
555 /* We can't insert breakpoints until the child has
556 finished with the shared memory region. We need to
557 wait until that happens. Ideal would be to just
559 - ptrace (PTRACE_SYSCALL, parent_pid, 0, 0);
560 - waitpid (parent_pid, &status, __WALL);
561 However, most architectures can't handle a syscall
562 being traced on the way out if it wasn't traced on
565 We might also think to loop, continuing the child
566 until it exits or gets a SIGTRAP. One problem is
567 that the child might call ptrace with PTRACE_TRACEME.
569 There's no simple and reliable way to figure out when
570 the vforked child will be done with its copy of the
571 shared memory. We could step it out of the syscall,
572 two instructions, let it go, and then single-step the
573 parent once. When we have hardware single-step, this
574 would work; with software single-step it could still
575 be made to work but we'd have to be able to insert
576 single-step breakpoints in the child, and we'd have
577 to insert -just- the single-step breakpoint in the
578 parent. Very awkward.
580 In the end, the best we can do is to make sure it
581 runs for a little while. Hopefully it will be out of
582 range of any breakpoints we reinsert. Usually this
583 is only the single-step breakpoint at vfork's return
586 linux_nat_debug_printf ("no VFORK_DONE support, sleeping a bit");
590 /* Pretend we've seen a PTRACE_EVENT_VFORK_DONE event,
591 and leave it pending. The next linux_nat_resume call
592 will notice a pending event, and bypasses actually
593 resuming the inferior. */
594 parent_lp
->status
= 0;
595 parent_lp
->waitstatus
.kind
= TARGET_WAITKIND_VFORK_DONE
;
596 parent_lp
->stopped
= 1;
598 /* If we're in async mode, need to tell the event loop
599 there's something here to process. */
600 if (target_is_async_p ())
607 struct lwp_info
*child_lp
;
609 child_lp
= add_lwp (inferior_ptid
);
610 child_lp
->stopped
= 1;
611 child_lp
->last_resume_kind
= resume_stop
;
613 /* Let the thread_db layer learn about this new process. */
614 check_for_thread_db ();
620 linux_nat_target::insert_fork_catchpoint (int pid
)
622 return !linux_supports_tracefork ();
626 linux_nat_target::remove_fork_catchpoint (int pid
)
632 linux_nat_target::insert_vfork_catchpoint (int pid
)
634 return !linux_supports_tracefork ();
638 linux_nat_target::remove_vfork_catchpoint (int pid
)
644 linux_nat_target::insert_exec_catchpoint (int pid
)
646 return !linux_supports_tracefork ();
650 linux_nat_target::remove_exec_catchpoint (int pid
)
656 linux_nat_target::set_syscall_catchpoint (int pid
, bool needed
, int any_count
,
657 gdb::array_view
<const int> syscall_counts
)
659 if (!linux_supports_tracesysgood ())
662 /* On GNU/Linux, we ignore the arguments. It means that we only
663 enable the syscall catchpoints, but do not disable them.
665 Also, we do not use the `syscall_counts' information because we do not
666 filter system calls here. We let GDB do the logic for us. */
670 /* List of known LWPs, keyed by LWP PID. This speeds up the common
671 case of mapping a PID returned from the kernel to our corresponding
672 lwp_info data structure. */
673 static htab_t lwp_lwpid_htab
;
675 /* Calculate a hash from a lwp_info's LWP PID. */
678 lwp_info_hash (const void *ap
)
680 const struct lwp_info
*lp
= (struct lwp_info
*) ap
;
681 pid_t pid
= lp
->ptid
.lwp ();
683 return iterative_hash_object (pid
, 0);
686 /* Equality function for the lwp_info hash table. Compares the LWP's
690 lwp_lwpid_htab_eq (const void *a
, const void *b
)
692 const struct lwp_info
*entry
= (const struct lwp_info
*) a
;
693 const struct lwp_info
*element
= (const struct lwp_info
*) b
;
695 return entry
->ptid
.lwp () == element
->ptid
.lwp ();
698 /* Create the lwp_lwpid_htab hash table. */
701 lwp_lwpid_htab_create (void)
703 lwp_lwpid_htab
= htab_create (100, lwp_info_hash
, lwp_lwpid_htab_eq
, NULL
);
706 /* Add LP to the hash table. */
709 lwp_lwpid_htab_add_lwp (struct lwp_info
*lp
)
713 slot
= htab_find_slot (lwp_lwpid_htab
, lp
, INSERT
);
714 gdb_assert (slot
!= NULL
&& *slot
== NULL
);
718 /* Head of doubly-linked list of known LWPs. Sorted by reverse
719 creation order. This order is assumed in some cases. E.g.,
720 reaping status after killing alls lwps of a process: the leader LWP
721 must be reaped last. */
722 struct lwp_info
*lwp_list
;
724 /* Add LP to sorted-by-reverse-creation-order doubly-linked list. */
727 lwp_list_add (struct lwp_info
*lp
)
730 if (lwp_list
!= NULL
)
735 /* Remove LP from sorted-by-reverse-creation-order doubly-linked
739 lwp_list_remove (struct lwp_info
*lp
)
741 /* Remove from sorted-by-creation-order list. */
742 if (lp
->next
!= NULL
)
743 lp
->next
->prev
= lp
->prev
;
744 if (lp
->prev
!= NULL
)
745 lp
->prev
->next
= lp
->next
;
752 /* Signal mask for use with sigsuspend in linux_nat_wait, initialized in
753 _initialize_linux_nat. */
754 static sigset_t suspend_mask
;
756 /* Signals to block to make that sigsuspend work. */
757 static sigset_t blocked_mask
;
759 /* SIGCHLD action. */
760 static struct sigaction sigchld_action
;
762 /* Block child signals (SIGCHLD and linux threads signals), and store
763 the previous mask in PREV_MASK. */
766 block_child_signals (sigset_t
*prev_mask
)
768 /* Make sure SIGCHLD is blocked. */
769 if (!sigismember (&blocked_mask
, SIGCHLD
))
770 sigaddset (&blocked_mask
, SIGCHLD
);
772 gdb_sigmask (SIG_BLOCK
, &blocked_mask
, prev_mask
);
775 /* Restore child signals mask, previously returned by
776 block_child_signals. */
779 restore_child_signals_mask (sigset_t
*prev_mask
)
781 gdb_sigmask (SIG_SETMASK
, prev_mask
, NULL
);
784 /* Mask of signals to pass directly to the inferior. */
785 static sigset_t pass_mask
;
787 /* Update signals to pass to the inferior. */
789 linux_nat_target::pass_signals
790 (gdb::array_view
<const unsigned char> pass_signals
)
794 sigemptyset (&pass_mask
);
796 for (signo
= 1; signo
< NSIG
; signo
++)
798 int target_signo
= gdb_signal_from_host (signo
);
799 if (target_signo
< pass_signals
.size () && pass_signals
[target_signo
])
800 sigaddset (&pass_mask
, signo
);
806 /* Prototypes for local functions. */
807 static int stop_wait_callback (struct lwp_info
*lp
);
808 static int resume_stopped_resumed_lwps (struct lwp_info
*lp
, const ptid_t wait_ptid
);
809 static int check_ptrace_stopped_lwp_gone (struct lwp_info
*lp
);
813 /* Destroy and free LP. */
816 lwp_free (struct lwp_info
*lp
)
818 /* Let the arch specific bits release arch_lwp_info. */
819 linux_target
->low_delete_thread (lp
->arch_private
);
824 /* Traversal function for purge_lwp_list. */
827 lwp_lwpid_htab_remove_pid (void **slot
, void *info
)
829 struct lwp_info
*lp
= (struct lwp_info
*) *slot
;
830 int pid
= *(int *) info
;
832 if (lp
->ptid
.pid () == pid
)
834 htab_clear_slot (lwp_lwpid_htab
, slot
);
835 lwp_list_remove (lp
);
842 /* Remove all LWPs belong to PID from the lwp list. */
845 purge_lwp_list (int pid
)
847 htab_traverse_noresize (lwp_lwpid_htab
, lwp_lwpid_htab_remove_pid
, &pid
);
850 /* Add the LWP specified by PTID to the list. PTID is the first LWP
851 in the process. Return a pointer to the structure describing the
854 This differs from add_lwp in that we don't let the arch specific
855 bits know about this new thread. Current clients of this callback
856 take the opportunity to install watchpoints in the new thread, and
857 we shouldn't do that for the first thread. If we're spawning a
858 child ("run"), the thread executes the shell wrapper first, and we
859 shouldn't touch it until it execs the program we want to debug.
860 For "attach", it'd be okay to call the callback, but it's not
861 necessary, because watchpoints can't yet have been inserted into
864 static struct lwp_info
*
865 add_initial_lwp (ptid_t ptid
)
869 gdb_assert (ptid
.lwp_p ());
871 lp
= XNEW (struct lwp_info
);
873 memset (lp
, 0, sizeof (struct lwp_info
));
875 lp
->last_resume_kind
= resume_continue
;
876 lp
->waitstatus
.kind
= TARGET_WAITKIND_IGNORE
;
881 /* Add to sorted-by-reverse-creation-order list. */
884 /* Add to keyed-by-pid htab. */
885 lwp_lwpid_htab_add_lwp (lp
);
890 /* Add the LWP specified by PID to the list. Return a pointer to the
891 structure describing the new LWP. The LWP should already be
894 static struct lwp_info
*
895 add_lwp (ptid_t ptid
)
899 lp
= add_initial_lwp (ptid
);
901 /* Let the arch specific bits know about this new thread. Current
902 clients of this callback take the opportunity to install
903 watchpoints in the new thread. We don't do this for the first
904 thread though. See add_initial_lwp. */
905 linux_target
->low_new_thread (lp
);
910 /* Remove the LWP specified by PID from the list. */
913 delete_lwp (ptid_t ptid
)
917 struct lwp_info dummy
;
920 slot
= htab_find_slot (lwp_lwpid_htab
, &dummy
, NO_INSERT
);
924 lp
= *(struct lwp_info
**) slot
;
925 gdb_assert (lp
!= NULL
);
927 htab_clear_slot (lwp_lwpid_htab
, slot
);
929 /* Remove from sorted-by-creation-order list. */
930 lwp_list_remove (lp
);
936 /* Return a pointer to the structure describing the LWP corresponding
937 to PID. If no corresponding LWP could be found, return NULL. */
939 static struct lwp_info
*
940 find_lwp_pid (ptid_t ptid
)
944 struct lwp_info dummy
;
951 dummy
.ptid
= ptid_t (0, lwp
, 0);
952 lp
= (struct lwp_info
*) htab_find (lwp_lwpid_htab
, &dummy
);
956 /* See nat/linux-nat.h. */
959 iterate_over_lwps (ptid_t filter
,
960 gdb::function_view
<iterate_over_lwps_ftype
> callback
)
962 struct lwp_info
*lp
, *lpnext
;
964 for (lp
= lwp_list
; lp
; lp
= lpnext
)
968 if (lp
->ptid
.matches (filter
))
970 if (callback (lp
) != 0)
978 /* Update our internal state when changing from one checkpoint to
979 another indicated by NEW_PTID. We can only switch single-threaded
980 applications, so we only create one new LWP, and the previous list
984 linux_nat_switch_fork (ptid_t new_ptid
)
988 purge_lwp_list (inferior_ptid
.pid ());
990 lp
= add_lwp (new_ptid
);
993 /* This changes the thread's ptid while preserving the gdb thread
994 num. Also changes the inferior pid, while preserving the
996 thread_change_ptid (linux_target
, inferior_ptid
, new_ptid
);
998 /* We've just told GDB core that the thread changed target id, but,
999 in fact, it really is a different thread, with different register
1001 registers_changed ();
1004 /* Handle the exit of a single thread LP. */
1007 exit_lwp (struct lwp_info
*lp
)
1009 struct thread_info
*th
= find_thread_ptid (linux_target
, lp
->ptid
);
1013 if (print_thread_events
)
1014 printf_unfiltered (_("[%s exited]\n"),
1015 target_pid_to_str (lp
->ptid
).c_str ());
1020 delete_lwp (lp
->ptid
);
1023 /* Wait for the LWP specified by LP, which we have just attached to.
1024 Returns a wait status for that LWP, to cache. */
1027 linux_nat_post_attach_wait (ptid_t ptid
, int *signalled
)
1029 pid_t new_pid
, pid
= ptid
.lwp ();
1032 if (linux_proc_pid_is_stopped (pid
))
1034 linux_nat_debug_printf ("Attaching to a stopped process");
1036 /* The process is definitely stopped. It is in a job control
1037 stop, unless the kernel predates the TASK_STOPPED /
1038 TASK_TRACED distinction, in which case it might be in a
1039 ptrace stop. Make sure it is in a ptrace stop; from there we
1040 can kill it, signal it, et cetera.
1042 First make sure there is a pending SIGSTOP. Since we are
1043 already attached, the process can not transition from stopped
1044 to running without a PTRACE_CONT; so we know this signal will
1045 go into the queue. The SIGSTOP generated by PTRACE_ATTACH is
1046 probably already in the queue (unless this kernel is old
1047 enough to use TASK_STOPPED for ptrace stops); but since SIGSTOP
1048 is not an RT signal, it can only be queued once. */
1049 kill_lwp (pid
, SIGSTOP
);
1051 /* Finally, resume the stopped process. This will deliver the SIGSTOP
1052 (or a higher priority signal, just like normal PTRACE_ATTACH). */
1053 ptrace (PTRACE_CONT
, pid
, 0, 0);
1056 /* Make sure the initial process is stopped. The user-level threads
1057 layer might want to poke around in the inferior, and that won't
1058 work if things haven't stabilized yet. */
1059 new_pid
= my_waitpid (pid
, &status
, __WALL
);
1060 gdb_assert (pid
== new_pid
);
1062 if (!WIFSTOPPED (status
))
1064 /* The pid we tried to attach has apparently just exited. */
1065 linux_nat_debug_printf ("Failed to stop %d: %s", pid
,
1066 status_to_str (status
).c_str ());
1070 if (WSTOPSIG (status
) != SIGSTOP
)
1073 linux_nat_debug_printf ("Received %s after attaching",
1074 status_to_str (status
).c_str ());
1081 linux_nat_target::create_inferior (const char *exec_file
,
1082 const std::string
&allargs
,
1083 char **env
, int from_tty
)
1085 maybe_disable_address_space_randomization restore_personality
1086 (disable_randomization
);
1088 /* The fork_child mechanism is synchronous and calls target_wait, so
1089 we have to mask the async mode. */
1091 /* Make sure we report all signals during startup. */
1094 inf_ptrace_target::create_inferior (exec_file
, allargs
, env
, from_tty
);
1097 /* Callback for linux_proc_attach_tgid_threads. Attach to PTID if not
1098 already attached. Returns true if a new LWP is found, false
1102 attach_proc_task_lwp_callback (ptid_t ptid
)
1104 struct lwp_info
*lp
;
1106 /* Ignore LWPs we're already attached to. */
1107 lp
= find_lwp_pid (ptid
);
1110 int lwpid
= ptid
.lwp ();
1112 if (ptrace (PTRACE_ATTACH
, lwpid
, 0, 0) < 0)
1116 /* Be quiet if we simply raced with the thread exiting.
1117 EPERM is returned if the thread's task still exists, and
1118 is marked as exited or zombie, as well as other
1119 conditions, so in that case, confirm the status in
1120 /proc/PID/status. */
1122 || (err
== EPERM
&& linux_proc_pid_is_gone (lwpid
)))
1124 linux_nat_debug_printf
1125 ("Cannot attach to lwp %d: thread is gone (%d: %s)",
1126 lwpid
, err
, safe_strerror (err
));
1132 = linux_ptrace_attach_fail_reason_string (ptid
, err
);
1134 warning (_("Cannot attach to lwp %d: %s"),
1135 lwpid
, reason
.c_str ());
1140 linux_nat_debug_printf ("PTRACE_ATTACH %s, 0, 0 (OK)",
1141 target_pid_to_str (ptid
).c_str ());
1143 lp
= add_lwp (ptid
);
1145 /* The next time we wait for this LWP we'll see a SIGSTOP as
1146 PTRACE_ATTACH brings it to a halt. */
1149 /* We need to wait for a stop before being able to make the
1150 next ptrace call on this LWP. */
1151 lp
->must_set_ptrace_flags
= 1;
1153 /* So that wait collects the SIGSTOP. */
1156 /* Also add the LWP to gdb's thread list, in case a
1157 matching libthread_db is not found (or the process uses
1159 add_thread (linux_target
, lp
->ptid
);
1160 set_running (linux_target
, lp
->ptid
, true);
1161 set_executing (linux_target
, lp
->ptid
, true);
1170 linux_nat_target::attach (const char *args
, int from_tty
)
1172 struct lwp_info
*lp
;
1176 /* Make sure we report all signals during attach. */
1181 inf_ptrace_target::attach (args
, from_tty
);
1183 catch (const gdb_exception_error
&ex
)
1185 pid_t pid
= parse_pid_to_attach (args
);
1186 std::string reason
= linux_ptrace_attach_fail_reason (pid
);
1188 if (!reason
.empty ())
1189 throw_error (ex
.error
, "warning: %s\n%s", reason
.c_str (),
1192 throw_error (ex
.error
, "%s", ex
.what ());
1195 /* The ptrace base target adds the main thread with (pid,0,0)
1196 format. Decorate it with lwp info. */
1197 ptid
= ptid_t (inferior_ptid
.pid (),
1198 inferior_ptid
.pid (),
1200 thread_change_ptid (linux_target
, inferior_ptid
, ptid
);
1202 /* Add the initial process as the first LWP to the list. */
1203 lp
= add_initial_lwp (ptid
);
1205 status
= linux_nat_post_attach_wait (lp
->ptid
, &lp
->signalled
);
1206 if (!WIFSTOPPED (status
))
1208 if (WIFEXITED (status
))
1210 int exit_code
= WEXITSTATUS (status
);
1212 target_terminal::ours ();
1213 target_mourn_inferior (inferior_ptid
);
1215 error (_("Unable to attach: program exited normally."));
1217 error (_("Unable to attach: program exited with code %d."),
1220 else if (WIFSIGNALED (status
))
1222 enum gdb_signal signo
;
1224 target_terminal::ours ();
1225 target_mourn_inferior (inferior_ptid
);
1227 signo
= gdb_signal_from_host (WTERMSIG (status
));
1228 error (_("Unable to attach: program terminated with signal "
1230 gdb_signal_to_name (signo
),
1231 gdb_signal_to_string (signo
));
1234 internal_error (__FILE__
, __LINE__
,
1235 _("unexpected status %d for PID %ld"),
1236 status
, (long) ptid
.lwp ());
1241 /* Save the wait status to report later. */
1243 linux_nat_debug_printf ("waitpid %ld, saving status %s",
1244 (long) lp
->ptid
.pid (),
1245 status_to_str (status
).c_str ());
1247 lp
->status
= status
;
1249 /* We must attach to every LWP. If /proc is mounted, use that to
1250 find them now. The inferior may be using raw clone instead of
1251 using pthreads. But even if it is using pthreads, thread_db
1252 walks structures in the inferior's address space to find the list
1253 of threads/LWPs, and those structures may well be corrupted.
1254 Note that once thread_db is loaded, we'll still use it to list
1255 threads and associate pthread info with each LWP. */
1256 linux_proc_attach_tgid_threads (lp
->ptid
.pid (),
1257 attach_proc_task_lwp_callback
);
1259 if (target_can_async_p ())
1263 /* Get pending signal of THREAD as a host signal number, for detaching
1264 purposes. This is the signal the thread last stopped for, which we
1265 need to deliver to the thread when detaching, otherwise, it'd be
1269 get_detach_signal (struct lwp_info
*lp
)
1271 enum gdb_signal signo
= GDB_SIGNAL_0
;
1273 /* If we paused threads momentarily, we may have stored pending
1274 events in lp->status or lp->waitstatus (see stop_wait_callback),
1275 and GDB core hasn't seen any signal for those threads.
1276 Otherwise, the last signal reported to the core is found in the
1277 thread object's stop_signal.
1279 There's a corner case that isn't handled here at present. Only
1280 if the thread stopped with a TARGET_WAITKIND_STOPPED does
1281 stop_signal make sense as a real signal to pass to the inferior.
1282 Some catchpoint related events, like
1283 TARGET_WAITKIND_(V)FORK|EXEC|SYSCALL, have their stop_signal set
1284 to GDB_SIGNAL_SIGTRAP when the catchpoint triggers. But,
1285 those traps are debug API (ptrace in our case) related and
1286 induced; the inferior wouldn't see them if it wasn't being
1287 traced. Hence, we should never pass them to the inferior, even
1288 when set to pass state. Since this corner case isn't handled by
1289 infrun.c when proceeding with a signal, for consistency, neither
1290 do we handle it here (or elsewhere in the file we check for
1291 signal pass state). Normally SIGTRAP isn't set to pass state, so
1292 this is really a corner case. */
1294 if (lp
->waitstatus
.kind
!= TARGET_WAITKIND_IGNORE
)
1295 signo
= GDB_SIGNAL_0
; /* a pending ptrace event, not a real signal. */
1296 else if (lp
->status
)
1297 signo
= gdb_signal_from_host (WSTOPSIG (lp
->status
));
1300 struct thread_info
*tp
= find_thread_ptid (linux_target
, lp
->ptid
);
1302 if (target_is_non_stop_p () && !tp
->executing
)
1304 if (tp
->suspend
.waitstatus_pending_p
)
1305 signo
= tp
->suspend
.waitstatus
.value
.sig
;
1307 signo
= tp
->suspend
.stop_signal
;
1309 else if (!target_is_non_stop_p ())
1312 process_stratum_target
*last_target
;
1314 get_last_target_status (&last_target
, &last_ptid
, nullptr);
1316 if (last_target
== linux_target
1317 && lp
->ptid
.lwp () == last_ptid
.lwp ())
1318 signo
= tp
->suspend
.stop_signal
;
1322 if (signo
== GDB_SIGNAL_0
)
1324 linux_nat_debug_printf ("lwp %s has no pending signal",
1325 target_pid_to_str (lp
->ptid
).c_str ());
1327 else if (!signal_pass_state (signo
))
1329 linux_nat_debug_printf
1330 ("lwp %s had signal %s but it is in no pass state",
1331 target_pid_to_str (lp
->ptid
).c_str (), gdb_signal_to_string (signo
));
1335 linux_nat_debug_printf ("lwp %s has pending signal %s",
1336 target_pid_to_str (lp
->ptid
).c_str (),
1337 gdb_signal_to_string (signo
));
1339 return gdb_signal_to_host (signo
);
1345 /* Detach from LP. If SIGNO_P is non-NULL, then it points to the
1346 signal number that should be passed to the LWP when detaching.
1347 Otherwise pass any pending signal the LWP may have, if any. */
1350 detach_one_lwp (struct lwp_info
*lp
, int *signo_p
)
1352 int lwpid
= lp
->ptid
.lwp ();
1355 gdb_assert (lp
->status
== 0 || WIFSTOPPED (lp
->status
));
1357 if (lp
->status
!= 0)
1358 linux_nat_debug_printf ("Pending %s for %s on detach.",
1359 strsignal (WSTOPSIG (lp
->status
)),
1360 target_pid_to_str (lp
->ptid
).c_str ());
1362 /* If there is a pending SIGSTOP, get rid of it. */
1365 linux_nat_debug_printf ("Sending SIGCONT to %s",
1366 target_pid_to_str (lp
->ptid
).c_str ());
1368 kill_lwp (lwpid
, SIGCONT
);
1372 if (signo_p
== NULL
)
1374 /* Pass on any pending signal for this LWP. */
1375 signo
= get_detach_signal (lp
);
1380 /* Preparing to resume may try to write registers, and fail if the
1381 lwp is zombie. If that happens, ignore the error. We'll handle
1382 it below, when detach fails with ESRCH. */
1385 linux_target
->low_prepare_to_resume (lp
);
1387 catch (const gdb_exception_error
&ex
)
1389 if (!check_ptrace_stopped_lwp_gone (lp
))
1393 if (ptrace (PTRACE_DETACH
, lwpid
, 0, signo
) < 0)
1395 int save_errno
= errno
;
1397 /* We know the thread exists, so ESRCH must mean the lwp is
1398 zombie. This can happen if one of the already-detached
1399 threads exits the whole thread group. In that case we're
1400 still attached, and must reap the lwp. */
1401 if (save_errno
== ESRCH
)
1405 ret
= my_waitpid (lwpid
, &status
, __WALL
);
1408 warning (_("Couldn't reap LWP %d while detaching: %s"),
1409 lwpid
, safe_strerror (errno
));
1411 else if (!WIFEXITED (status
) && !WIFSIGNALED (status
))
1413 warning (_("Reaping LWP %d while detaching "
1414 "returned unexpected status 0x%x"),
1420 error (_("Can't detach %s: %s"),
1421 target_pid_to_str (lp
->ptid
).c_str (),
1422 safe_strerror (save_errno
));
1426 linux_nat_debug_printf ("PTRACE_DETACH (%s, %s, 0) (OK)",
1427 target_pid_to_str (lp
->ptid
).c_str (),
1430 delete_lwp (lp
->ptid
);
1434 detach_callback (struct lwp_info
*lp
)
1436 /* We don't actually detach from the thread group leader just yet.
1437 If the thread group exits, we must reap the zombie clone lwps
1438 before we're able to reap the leader. */
1439 if (lp
->ptid
.lwp () != lp
->ptid
.pid ())
1440 detach_one_lwp (lp
, NULL
);
1445 linux_nat_target::detach (inferior
*inf
, int from_tty
)
1447 struct lwp_info
*main_lwp
;
1450 /* Don't unregister from the event loop, as there may be other
1451 inferiors running. */
1453 /* Stop all threads before detaching. ptrace requires that the
1454 thread is stopped to successfully detach. */
1455 iterate_over_lwps (ptid_t (pid
), stop_callback
);
1456 /* ... and wait until all of them have reported back that
1457 they're no longer running. */
1458 iterate_over_lwps (ptid_t (pid
), stop_wait_callback
);
1460 /* We can now safely remove breakpoints. We don't this in earlier
1461 in common code because this target doesn't currently support
1462 writing memory while the inferior is running. */
1463 remove_breakpoints_inf (current_inferior ());
1465 iterate_over_lwps (ptid_t (pid
), detach_callback
);
1467 /* Only the initial process should be left right now. */
1468 gdb_assert (num_lwps (pid
) == 1);
1470 main_lwp
= find_lwp_pid (ptid_t (pid
));
1472 if (forks_exist_p ())
1474 /* Multi-fork case. The current inferior_ptid is being detached
1475 from, but there are other viable forks to debug. Detach from
1476 the current fork, and context-switch to the first
1478 linux_fork_detach (from_tty
);
1482 target_announce_detach (from_tty
);
1484 /* Pass on any pending signal for the last LWP. */
1485 int signo
= get_detach_signal (main_lwp
);
1487 detach_one_lwp (main_lwp
, &signo
);
1489 detach_success (inf
);
1492 maybe_close_proc_mem_file (pid
);
1495 /* Resume execution of the inferior process. If STEP is nonzero,
1496 single-step it. If SIGNAL is nonzero, give it that signal. */
1499 linux_resume_one_lwp_throw (struct lwp_info
*lp
, int step
,
1500 enum gdb_signal signo
)
1504 /* stop_pc doubles as the PC the LWP had when it was last resumed.
1505 We only presently need that if the LWP is stepped though (to
1506 handle the case of stepping a breakpoint instruction). */
1509 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
1511 lp
->stop_pc
= regcache_read_pc (regcache
);
1516 linux_target
->low_prepare_to_resume (lp
);
1517 linux_target
->low_resume (lp
->ptid
, step
, signo
);
1519 /* Successfully resumed. Clear state that no longer makes sense,
1520 and mark the LWP as running. Must not do this before resuming
1521 otherwise if that fails other code will be confused. E.g., we'd
1522 later try to stop the LWP and hang forever waiting for a stop
1523 status. Note that we must not throw after this is cleared,
1524 otherwise handle_zombie_lwp_error would get confused. */
1527 lp
->stop_reason
= TARGET_STOPPED_BY_NO_REASON
;
1528 registers_changed_ptid (linux_target
, lp
->ptid
);
1531 /* Called when we try to resume a stopped LWP and that errors out. If
1532 the LWP is no longer in ptrace-stopped state (meaning it's zombie,
1533 or about to become), discard the error, clear any pending status
1534 the LWP may have, and return true (we'll collect the exit status
1535 soon enough). Otherwise, return false. */
1538 check_ptrace_stopped_lwp_gone (struct lwp_info
*lp
)
1540 /* If we get an error after resuming the LWP successfully, we'd
1541 confuse !T state for the LWP being gone. */
1542 gdb_assert (lp
->stopped
);
1544 /* We can't just check whether the LWP is in 'Z (Zombie)' state,
1545 because even if ptrace failed with ESRCH, the tracee may be "not
1546 yet fully dead", but already refusing ptrace requests. In that
1547 case the tracee has 'R (Running)' state for a little bit
1548 (observed in Linux 3.18). See also the note on ESRCH in the
1549 ptrace(2) man page. Instead, check whether the LWP has any state
1550 other than ptrace-stopped. */
1552 /* Don't assume anything if /proc/PID/status can't be read. */
1553 if (linux_proc_pid_is_trace_stopped_nowarn (lp
->ptid
.lwp ()) == 0)
1555 lp
->stop_reason
= TARGET_STOPPED_BY_NO_REASON
;
1557 lp
->waitstatus
.kind
= TARGET_WAITKIND_IGNORE
;
1563 /* Like linux_resume_one_lwp_throw, but no error is thrown if the LWP
1564 disappears while we try to resume it. */
1567 linux_resume_one_lwp (struct lwp_info
*lp
, int step
, enum gdb_signal signo
)
1571 linux_resume_one_lwp_throw (lp
, step
, signo
);
1573 catch (const gdb_exception_error
&ex
)
1575 if (!check_ptrace_stopped_lwp_gone (lp
))
1583 resume_lwp (struct lwp_info
*lp
, int step
, enum gdb_signal signo
)
1587 struct inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
1589 if (inf
->vfork_child
!= NULL
)
1591 linux_nat_debug_printf ("Not resuming %s (vfork parent)",
1592 target_pid_to_str (lp
->ptid
).c_str ());
1594 else if (!lwp_status_pending_p (lp
))
1596 linux_nat_debug_printf ("Resuming sibling %s, %s, %s",
1597 target_pid_to_str (lp
->ptid
).c_str (),
1598 (signo
!= GDB_SIGNAL_0
1599 ? strsignal (gdb_signal_to_host (signo
))
1601 step
? "step" : "resume");
1603 linux_resume_one_lwp (lp
, step
, signo
);
1607 linux_nat_debug_printf ("Not resuming sibling %s (has pending)",
1608 target_pid_to_str (lp
->ptid
).c_str ());
1612 linux_nat_debug_printf ("Not resuming sibling %s (not stopped)",
1613 target_pid_to_str (lp
->ptid
).c_str ());
1616 /* Callback for iterate_over_lwps. If LWP is EXCEPT, do nothing.
1617 Resume LWP with the last stop signal, if it is in pass state. */
1620 linux_nat_resume_callback (struct lwp_info
*lp
, struct lwp_info
*except
)
1622 enum gdb_signal signo
= GDB_SIGNAL_0
;
1629 struct thread_info
*thread
;
1631 thread
= find_thread_ptid (linux_target
, lp
->ptid
);
1634 signo
= thread
->suspend
.stop_signal
;
1635 thread
->suspend
.stop_signal
= GDB_SIGNAL_0
;
1639 resume_lwp (lp
, 0, signo
);
1644 resume_clear_callback (struct lwp_info
*lp
)
1647 lp
->last_resume_kind
= resume_stop
;
1652 resume_set_callback (struct lwp_info
*lp
)
1655 lp
->last_resume_kind
= resume_continue
;
1660 linux_nat_target::resume (ptid_t ptid
, int step
, enum gdb_signal signo
)
1662 struct lwp_info
*lp
;
1665 linux_nat_debug_printf ("Preparing to %s %s, %s, inferior_ptid %s",
1666 step
? "step" : "resume",
1667 target_pid_to_str (ptid
).c_str (),
1668 (signo
!= GDB_SIGNAL_0
1669 ? strsignal (gdb_signal_to_host (signo
)) : "0"),
1670 target_pid_to_str (inferior_ptid
).c_str ());
1672 /* A specific PTID means `step only this process id'. */
1673 resume_many
= (minus_one_ptid
== ptid
1676 /* Mark the lwps we're resuming as resumed and update their
1677 last_resume_kind to resume_continue. */
1678 iterate_over_lwps (ptid
, resume_set_callback
);
1680 /* See if it's the current inferior that should be handled
1683 lp
= find_lwp_pid (inferior_ptid
);
1685 lp
= find_lwp_pid (ptid
);
1686 gdb_assert (lp
!= NULL
);
1688 /* Remember if we're stepping. */
1689 lp
->last_resume_kind
= step
? resume_step
: resume_continue
;
1691 /* If we have a pending wait status for this thread, there is no
1692 point in resuming the process. But first make sure that
1693 linux_nat_wait won't preemptively handle the event - we
1694 should never take this short-circuit if we are going to
1695 leave LP running, since we have skipped resuming all the
1696 other threads. This bit of code needs to be synchronized
1697 with linux_nat_wait. */
1699 if (lp
->status
&& WIFSTOPPED (lp
->status
))
1702 && WSTOPSIG (lp
->status
)
1703 && sigismember (&pass_mask
, WSTOPSIG (lp
->status
)))
1705 linux_nat_debug_printf
1706 ("Not short circuiting for ignored status 0x%x", lp
->status
);
1708 /* FIXME: What should we do if we are supposed to continue
1709 this thread with a signal? */
1710 gdb_assert (signo
== GDB_SIGNAL_0
);
1711 signo
= gdb_signal_from_host (WSTOPSIG (lp
->status
));
1716 if (lwp_status_pending_p (lp
))
1718 /* FIXME: What should we do if we are supposed to continue
1719 this thread with a signal? */
1720 gdb_assert (signo
== GDB_SIGNAL_0
);
1722 linux_nat_debug_printf ("Short circuiting for status 0x%x",
1725 if (target_can_async_p ())
1728 /* Tell the event loop we have something to process. */
1735 iterate_over_lwps (ptid
, [=] (struct lwp_info
*info
)
1737 return linux_nat_resume_callback (info
, lp
);
1740 linux_nat_debug_printf ("%s %s, %s (resume event thread)",
1741 step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
1742 target_pid_to_str (lp
->ptid
).c_str (),
1743 (signo
!= GDB_SIGNAL_0
1744 ? strsignal (gdb_signal_to_host (signo
)) : "0"));
1746 linux_resume_one_lwp (lp
, step
, signo
);
1748 if (target_can_async_p ())
1752 /* Send a signal to an LWP. */
1755 kill_lwp (int lwpid
, int signo
)
1760 ret
= syscall (__NR_tkill
, lwpid
, signo
);
1761 if (errno
== ENOSYS
)
1763 /* If tkill fails, then we are not using nptl threads, a
1764 configuration we no longer support. */
1765 perror_with_name (("tkill"));
1770 /* Handle a GNU/Linux syscall trap wait response. If we see a syscall
1771 event, check if the core is interested in it: if not, ignore the
1772 event, and keep waiting; otherwise, we need to toggle the LWP's
1773 syscall entry/exit status, since the ptrace event itself doesn't
1774 indicate it, and report the trap to higher layers. */
1777 linux_handle_syscall_trap (struct lwp_info
*lp
, int stopping
)
1779 struct target_waitstatus
*ourstatus
= &lp
->waitstatus
;
1780 struct gdbarch
*gdbarch
= target_thread_architecture (lp
->ptid
);
1781 thread_info
*thread
= find_thread_ptid (linux_target
, lp
->ptid
);
1782 int syscall_number
= (int) gdbarch_get_syscall_number (gdbarch
, thread
);
1786 /* If we're stopping threads, there's a SIGSTOP pending, which
1787 makes it so that the LWP reports an immediate syscall return,
1788 followed by the SIGSTOP. Skip seeing that "return" using
1789 PTRACE_CONT directly, and let stop_wait_callback collect the
1790 SIGSTOP. Later when the thread is resumed, a new syscall
1791 entry event. If we didn't do this (and returned 0), we'd
1792 leave a syscall entry pending, and our caller, by using
1793 PTRACE_CONT to collect the SIGSTOP, skips the syscall return
1794 itself. Later, when the user re-resumes this LWP, we'd see
1795 another syscall entry event and we'd mistake it for a return.
1797 If stop_wait_callback didn't force the SIGSTOP out of the LWP
1798 (leaving immediately with LWP->signalled set, without issuing
1799 a PTRACE_CONT), it would still be problematic to leave this
1800 syscall enter pending, as later when the thread is resumed,
1801 it would then see the same syscall exit mentioned above,
1802 followed by the delayed SIGSTOP, while the syscall didn't
1803 actually get to execute. It seems it would be even more
1804 confusing to the user. */
1806 linux_nat_debug_printf
1807 ("ignoring syscall %d for LWP %ld (stopping threads), resuming with "
1808 "PTRACE_CONT for SIGSTOP", syscall_number
, lp
->ptid
.lwp ());
1810 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
1811 ptrace (PTRACE_CONT
, lp
->ptid
.lwp (), 0, 0);
1816 /* Always update the entry/return state, even if this particular
1817 syscall isn't interesting to the core now. In async mode,
1818 the user could install a new catchpoint for this syscall
1819 between syscall enter/return, and we'll need to know to
1820 report a syscall return if that happens. */
1821 lp
->syscall_state
= (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1822 ? TARGET_WAITKIND_SYSCALL_RETURN
1823 : TARGET_WAITKIND_SYSCALL_ENTRY
);
1825 if (catch_syscall_enabled ())
1827 if (catching_syscall_number (syscall_number
))
1829 /* Alright, an event to report. */
1830 ourstatus
->kind
= lp
->syscall_state
;
1831 ourstatus
->value
.syscall_number
= syscall_number
;
1833 linux_nat_debug_printf
1834 ("stopping for %s of syscall %d for LWP %ld",
1835 (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1836 ? "entry" : "return"), syscall_number
, lp
->ptid
.lwp ());
1841 linux_nat_debug_printf
1842 ("ignoring %s of syscall %d for LWP %ld",
1843 (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1844 ? "entry" : "return"), syscall_number
, lp
->ptid
.lwp ());
1848 /* If we had been syscall tracing, and hence used PT_SYSCALL
1849 before on this LWP, it could happen that the user removes all
1850 syscall catchpoints before we get to process this event.
1851 There are two noteworthy issues here:
1853 - When stopped at a syscall entry event, resuming with
1854 PT_STEP still resumes executing the syscall and reports a
1857 - Only PT_SYSCALL catches syscall enters. If we last
1858 single-stepped this thread, then this event can't be a
1859 syscall enter. If we last single-stepped this thread, this
1860 has to be a syscall exit.
1862 The points above mean that the next resume, be it PT_STEP or
1863 PT_CONTINUE, can not trigger a syscall trace event. */
1864 linux_nat_debug_printf
1865 ("caught syscall event with no syscall catchpoints. %d for LWP %ld, "
1866 "ignoring", syscall_number
, lp
->ptid
.lwp ());
1867 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
1870 /* The core isn't interested in this event. For efficiency, avoid
1871 stopping all threads only to have the core resume them all again.
1872 Since we're not stopping threads, if we're still syscall tracing
1873 and not stepping, we can't use PTRACE_CONT here, as we'd miss any
1874 subsequent syscall. Simply resume using the inf-ptrace layer,
1875 which knows when to use PT_SYSCALL or PT_CONTINUE. */
1877 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
1881 /* Handle a GNU/Linux extended wait response. If we see a clone
1882 event, we need to add the new LWP to our list (and not report the
1883 trap to higher layers). This function returns non-zero if the
1884 event should be ignored and we should wait again. If STOPPING is
1885 true, the new LWP remains stopped, otherwise it is continued. */
1888 linux_handle_extended_wait (struct lwp_info
*lp
, int status
)
1890 int pid
= lp
->ptid
.lwp ();
1891 struct target_waitstatus
*ourstatus
= &lp
->waitstatus
;
1892 int event
= linux_ptrace_get_extended_event (status
);
1894 /* All extended events we currently use are mid-syscall. Only
1895 PTRACE_EVENT_STOP is delivered more like a signal-stop, but
1896 you have to be using PTRACE_SEIZE to get that. */
1897 lp
->syscall_state
= TARGET_WAITKIND_SYSCALL_ENTRY
;
1899 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
1900 || event
== PTRACE_EVENT_CLONE
)
1902 unsigned long new_pid
;
1905 ptrace (PTRACE_GETEVENTMSG
, pid
, 0, &new_pid
);
1907 /* If we haven't already seen the new PID stop, wait for it now. */
1908 if (! pull_pid_from_list (&stopped_pids
, new_pid
, &status
))
1910 /* The new child has a pending SIGSTOP. We can't affect it until it
1911 hits the SIGSTOP, but we're already attached. */
1912 ret
= my_waitpid (new_pid
, &status
, __WALL
);
1914 perror_with_name (_("waiting for new child"));
1915 else if (ret
!= new_pid
)
1916 internal_error (__FILE__
, __LINE__
,
1917 _("wait returned unexpected PID %d"), ret
);
1918 else if (!WIFSTOPPED (status
))
1919 internal_error (__FILE__
, __LINE__
,
1920 _("wait returned unexpected status 0x%x"), status
);
1923 ourstatus
->value
.related_pid
= ptid_t (new_pid
, new_pid
, 0);
1925 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
)
1927 /* The arch-specific native code may need to know about new
1928 forks even if those end up never mapped to an
1930 linux_target
->low_new_fork (lp
, new_pid
);
1932 else if (event
== PTRACE_EVENT_CLONE
)
1934 linux_target
->low_new_clone (lp
, new_pid
);
1937 if (event
== PTRACE_EVENT_FORK
1938 && linux_fork_checkpointing_p (lp
->ptid
.pid ()))
1940 /* Handle checkpointing by linux-fork.c here as a special
1941 case. We don't want the follow-fork-mode or 'catch fork'
1942 to interfere with this. */
1944 /* This won't actually modify the breakpoint list, but will
1945 physically remove the breakpoints from the child. */
1946 detach_breakpoints (ptid_t (new_pid
, new_pid
, 0));
1948 /* Retain child fork in ptrace (stopped) state. */
1949 if (!find_fork_pid (new_pid
))
1952 /* Report as spurious, so that infrun doesn't want to follow
1953 this fork. We're actually doing an infcall in
1955 ourstatus
->kind
= TARGET_WAITKIND_SPURIOUS
;
1957 /* Report the stop to the core. */
1961 if (event
== PTRACE_EVENT_FORK
)
1962 ourstatus
->kind
= TARGET_WAITKIND_FORKED
;
1963 else if (event
== PTRACE_EVENT_VFORK
)
1964 ourstatus
->kind
= TARGET_WAITKIND_VFORKED
;
1965 else if (event
== PTRACE_EVENT_CLONE
)
1967 struct lwp_info
*new_lp
;
1969 ourstatus
->kind
= TARGET_WAITKIND_IGNORE
;
1971 linux_nat_debug_printf
1972 ("Got clone event from LWP %d, new child is LWP %ld", pid
, new_pid
);
1974 new_lp
= add_lwp (ptid_t (lp
->ptid
.pid (), new_pid
, 0));
1975 new_lp
->stopped
= 1;
1976 new_lp
->resumed
= 1;
1978 /* If the thread_db layer is active, let it record the user
1979 level thread id and status, and add the thread to GDB's
1981 if (!thread_db_notice_clone (lp
->ptid
, new_lp
->ptid
))
1983 /* The process is not using thread_db. Add the LWP to
1985 target_post_attach (new_lp
->ptid
.lwp ());
1986 add_thread (linux_target
, new_lp
->ptid
);
1989 /* Even if we're stopping the thread for some reason
1990 internal to this module, from the perspective of infrun
1991 and the user/frontend, this new thread is running until
1992 it next reports a stop. */
1993 set_running (linux_target
, new_lp
->ptid
, true);
1994 set_executing (linux_target
, new_lp
->ptid
, true);
1996 if (WSTOPSIG (status
) != SIGSTOP
)
1998 /* This can happen if someone starts sending signals to
1999 the new thread before it gets a chance to run, which
2000 have a lower number than SIGSTOP (e.g. SIGUSR1).
2001 This is an unlikely case, and harder to handle for
2002 fork / vfork than for clone, so we do not try - but
2003 we handle it for clone events here. */
2005 new_lp
->signalled
= 1;
2007 /* We created NEW_LP so it cannot yet contain STATUS. */
2008 gdb_assert (new_lp
->status
== 0);
2010 /* Save the wait status to report later. */
2011 linux_nat_debug_printf
2012 ("waitpid of new LWP %ld, saving status %s",
2013 (long) new_lp
->ptid
.lwp (), status_to_str (status
).c_str ());
2014 new_lp
->status
= status
;
2016 else if (report_thread_events
)
2018 new_lp
->waitstatus
.kind
= TARGET_WAITKIND_THREAD_CREATED
;
2019 new_lp
->status
= status
;
2028 if (event
== PTRACE_EVENT_EXEC
)
2030 linux_nat_debug_printf ("Got exec event from LWP %ld", lp
->ptid
.lwp ());
2032 /* Close the /proc/<pid>/mem file if it was open for this
2034 maybe_close_proc_mem_file (lp
->ptid
.pid ());
2036 ourstatus
->kind
= TARGET_WAITKIND_EXECD
;
2037 ourstatus
->value
.execd_pathname
2038 = xstrdup (linux_proc_pid_to_exec_file (pid
));
2040 /* The thread that execed must have been resumed, but, when a
2041 thread execs, it changes its tid to the tgid, and the old
2042 tgid thread might have not been resumed. */
2047 if (event
== PTRACE_EVENT_VFORK_DONE
)
2049 if (current_inferior ()->waiting_for_vfork_done
)
2051 linux_nat_debug_printf
2052 ("Got expected PTRACE_EVENT_VFORK_DONE from LWP %ld: stopping",
2055 ourstatus
->kind
= TARGET_WAITKIND_VFORK_DONE
;
2059 linux_nat_debug_printf
2060 ("Got PTRACE_EVENT_VFORK_DONE from LWP %ld: ignoring", lp
->ptid
.lwp ());
2065 internal_error (__FILE__
, __LINE__
,
2066 _("unknown ptrace event %d"), event
);
2069 /* Suspend waiting for a signal. We're mostly interested in
2075 linux_nat_debug_printf ("about to sigsuspend");
2076 sigsuspend (&suspend_mask
);
2078 /* If the quit flag is set, it means that the user pressed Ctrl-C
2079 and we're debugging a process that is running on a separate
2080 terminal, so we must forward the Ctrl-C to the inferior. (If the
2081 inferior is sharing GDB's terminal, then the Ctrl-C reaches the
2082 inferior directly.) We must do this here because functions that
2083 need to block waiting for a signal loop forever until there's an
2084 event to report before returning back to the event loop. */
2085 if (!target_terminal::is_ours ())
2087 if (check_quit_flag ())
2088 target_pass_ctrlc ();
2092 /* Wait for LP to stop. Returns the wait status, or 0 if the LWP has
2096 wait_lwp (struct lwp_info
*lp
)
2100 int thread_dead
= 0;
2103 gdb_assert (!lp
->stopped
);
2104 gdb_assert (lp
->status
== 0);
2106 /* Make sure SIGCHLD is blocked for sigsuspend avoiding a race below. */
2107 block_child_signals (&prev_mask
);
2111 pid
= my_waitpid (lp
->ptid
.lwp (), &status
, __WALL
| WNOHANG
);
2112 if (pid
== -1 && errno
== ECHILD
)
2114 /* The thread has previously exited. We need to delete it
2115 now because if this was a non-leader thread execing, we
2116 won't get an exit event. See comments on exec events at
2117 the top of the file. */
2119 linux_nat_debug_printf ("%s vanished.",
2120 target_pid_to_str (lp
->ptid
).c_str ());
2125 /* Bugs 10970, 12702.
2126 Thread group leader may have exited in which case we'll lock up in
2127 waitpid if there are other threads, even if they are all zombies too.
2128 Basically, we're not supposed to use waitpid this way.
2129 tkill(pid,0) cannot be used here as it gets ESRCH for both
2130 for zombie and running processes.
2132 As a workaround, check if we're waiting for the thread group leader and
2133 if it's a zombie, and avoid calling waitpid if it is.
2135 This is racy, what if the tgl becomes a zombie right after we check?
2136 Therefore always use WNOHANG with sigsuspend - it is equivalent to
2137 waiting waitpid but linux_proc_pid_is_zombie is safe this way. */
2139 if (lp
->ptid
.pid () == lp
->ptid
.lwp ()
2140 && linux_proc_pid_is_zombie (lp
->ptid
.lwp ()))
2143 linux_nat_debug_printf ("Thread group leader %s vanished.",
2144 target_pid_to_str (lp
->ptid
).c_str ());
2148 /* Wait for next SIGCHLD and try again. This may let SIGCHLD handlers
2149 get invoked despite our caller had them intentionally blocked by
2150 block_child_signals. This is sensitive only to the loop of
2151 linux_nat_wait_1 and there if we get called my_waitpid gets called
2152 again before it gets to sigsuspend so we can safely let the handlers
2153 get executed here. */
2157 restore_child_signals_mask (&prev_mask
);
2161 gdb_assert (pid
== lp
->ptid
.lwp ());
2163 linux_nat_debug_printf ("waitpid %s received %s",
2164 target_pid_to_str (lp
->ptid
).c_str (),
2165 status_to_str (status
).c_str ());
2167 /* Check if the thread has exited. */
2168 if (WIFEXITED (status
) || WIFSIGNALED (status
))
2170 if (report_thread_events
2171 || lp
->ptid
.pid () == lp
->ptid
.lwp ())
2173 linux_nat_debug_printf ("LWP %d exited.", lp
->ptid
.pid ());
2175 /* If this is the leader exiting, it means the whole
2176 process is gone. Store the status to report to the
2177 core. Store it in lp->waitstatus, because lp->status
2178 would be ambiguous (W_EXITCODE(0,0) == 0). */
2179 store_waitstatus (&lp
->waitstatus
, status
);
2184 linux_nat_debug_printf ("%s exited.",
2185 target_pid_to_str (lp
->ptid
).c_str ());
2195 gdb_assert (WIFSTOPPED (status
));
2198 if (lp
->must_set_ptrace_flags
)
2200 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2201 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
2203 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
2204 lp
->must_set_ptrace_flags
= 0;
2207 /* Handle GNU/Linux's syscall SIGTRAPs. */
2208 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
2210 /* No longer need the sysgood bit. The ptrace event ends up
2211 recorded in lp->waitstatus if we care for it. We can carry
2212 on handling the event like a regular SIGTRAP from here
2214 status
= W_STOPCODE (SIGTRAP
);
2215 if (linux_handle_syscall_trap (lp
, 1))
2216 return wait_lwp (lp
);
2220 /* Almost all other ptrace-stops are known to be outside of system
2221 calls, with further exceptions in linux_handle_extended_wait. */
2222 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
2225 /* Handle GNU/Linux's extended waitstatus for trace events. */
2226 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
2227 && linux_is_extended_waitstatus (status
))
2229 linux_nat_debug_printf ("Handling extended status 0x%06x", status
);
2230 linux_handle_extended_wait (lp
, status
);
2237 /* Send a SIGSTOP to LP. */
2240 stop_callback (struct lwp_info
*lp
)
2242 if (!lp
->stopped
&& !lp
->signalled
)
2246 linux_nat_debug_printf ("kill %s **<SIGSTOP>**",
2247 target_pid_to_str (lp
->ptid
).c_str ());
2250 ret
= kill_lwp (lp
->ptid
.lwp (), SIGSTOP
);
2251 linux_nat_debug_printf ("lwp kill %d %s", ret
,
2252 errno
? safe_strerror (errno
) : "ERRNO-OK");
2255 gdb_assert (lp
->status
== 0);
2261 /* Request a stop on LWP. */
2264 linux_stop_lwp (struct lwp_info
*lwp
)
2266 stop_callback (lwp
);
2269 /* See linux-nat.h */
2272 linux_stop_and_wait_all_lwps (void)
2274 /* Stop all LWP's ... */
2275 iterate_over_lwps (minus_one_ptid
, stop_callback
);
2277 /* ... and wait until all of them have reported back that
2278 they're no longer running. */
2279 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
2282 /* See linux-nat.h */
2285 linux_unstop_all_lwps (void)
2287 iterate_over_lwps (minus_one_ptid
,
2288 [] (struct lwp_info
*info
)
2290 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
2294 /* Return non-zero if LWP PID has a pending SIGINT. */
2297 linux_nat_has_pending_sigint (int pid
)
2299 sigset_t pending
, blocked
, ignored
;
2301 linux_proc_pending_signals (pid
, &pending
, &blocked
, &ignored
);
2303 if (sigismember (&pending
, SIGINT
)
2304 && !sigismember (&ignored
, SIGINT
))
2310 /* Set a flag in LP indicating that we should ignore its next SIGINT. */
2313 set_ignore_sigint (struct lwp_info
*lp
)
2315 /* If a thread has a pending SIGINT, consume it; otherwise, set a
2316 flag to consume the next one. */
2317 if (lp
->stopped
&& lp
->status
!= 0 && WIFSTOPPED (lp
->status
)
2318 && WSTOPSIG (lp
->status
) == SIGINT
)
2321 lp
->ignore_sigint
= 1;
2326 /* If LP does not have a SIGINT pending, then clear the ignore_sigint flag.
2327 This function is called after we know the LWP has stopped; if the LWP
2328 stopped before the expected SIGINT was delivered, then it will never have
2329 arrived. Also, if the signal was delivered to a shared queue and consumed
2330 by a different thread, it will never be delivered to this LWP. */
2333 maybe_clear_ignore_sigint (struct lwp_info
*lp
)
2335 if (!lp
->ignore_sigint
)
2338 if (!linux_nat_has_pending_sigint (lp
->ptid
.lwp ()))
2340 linux_nat_debug_printf ("Clearing bogus flag for %s",
2341 target_pid_to_str (lp
->ptid
).c_str ());
2342 lp
->ignore_sigint
= 0;
2346 /* Fetch the possible triggered data watchpoint info and store it in
2349 On some archs, like x86, that use debug registers to set
2350 watchpoints, it's possible that the way to know which watched
2351 address trapped, is to check the register that is used to select
2352 which address to watch. Problem is, between setting the watchpoint
2353 and reading back which data address trapped, the user may change
2354 the set of watchpoints, and, as a consequence, GDB changes the
2355 debug registers in the inferior. To avoid reading back a stale
2356 stopped-data-address when that happens, we cache in LP the fact
2357 that a watchpoint trapped, and the corresponding data address, as
2358 soon as we see LP stop with a SIGTRAP. If GDB changes the debug
2359 registers meanwhile, we have the cached data we can rely on. */
2362 check_stopped_by_watchpoint (struct lwp_info
*lp
)
2364 scoped_restore save_inferior_ptid
= make_scoped_restore (&inferior_ptid
);
2365 inferior_ptid
= lp
->ptid
;
2367 if (linux_target
->low_stopped_by_watchpoint ())
2369 lp
->stop_reason
= TARGET_STOPPED_BY_WATCHPOINT
;
2370 lp
->stopped_data_address_p
2371 = linux_target
->low_stopped_data_address (&lp
->stopped_data_address
);
2374 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2377 /* Returns true if the LWP had stopped for a watchpoint. */
2380 linux_nat_target::stopped_by_watchpoint ()
2382 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2384 gdb_assert (lp
!= NULL
);
2386 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2390 linux_nat_target::stopped_data_address (CORE_ADDR
*addr_p
)
2392 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2394 gdb_assert (lp
!= NULL
);
2396 *addr_p
= lp
->stopped_data_address
;
2398 return lp
->stopped_data_address_p
;
2401 /* Commonly any breakpoint / watchpoint generate only SIGTRAP. */
2404 linux_nat_target::low_status_is_event (int status
)
2406 return WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
;
2409 /* Wait until LP is stopped. */
2412 stop_wait_callback (struct lwp_info
*lp
)
2414 inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
2416 /* If this is a vfork parent, bail out, it is not going to report
2417 any SIGSTOP until the vfork is done with. */
2418 if (inf
->vfork_child
!= NULL
)
2425 status
= wait_lwp (lp
);
2429 if (lp
->ignore_sigint
&& WIFSTOPPED (status
)
2430 && WSTOPSIG (status
) == SIGINT
)
2432 lp
->ignore_sigint
= 0;
2435 ptrace (PTRACE_CONT
, lp
->ptid
.lwp (), 0, 0);
2437 linux_nat_debug_printf
2438 ("PTRACE_CONT %s, 0, 0 (%s) (discarding SIGINT)",
2439 target_pid_to_str (lp
->ptid
).c_str (),
2440 errno
? safe_strerror (errno
) : "OK");
2442 return stop_wait_callback (lp
);
2445 maybe_clear_ignore_sigint (lp
);
2447 if (WSTOPSIG (status
) != SIGSTOP
)
2449 /* The thread was stopped with a signal other than SIGSTOP. */
2451 linux_nat_debug_printf ("Pending event %s in %s",
2452 status_to_str ((int) status
).c_str (),
2453 target_pid_to_str (lp
->ptid
).c_str ());
2455 /* Save the sigtrap event. */
2456 lp
->status
= status
;
2457 gdb_assert (lp
->signalled
);
2458 save_stop_reason (lp
);
2462 /* We caught the SIGSTOP that we intended to catch. */
2464 linux_nat_debug_printf ("Expected SIGSTOP caught for %s.",
2465 target_pid_to_str (lp
->ptid
).c_str ());
2469 /* If we are waiting for this stop so we can report the thread
2470 stopped then we need to record this status. Otherwise, we can
2471 now discard this stop event. */
2472 if (lp
->last_resume_kind
== resume_stop
)
2474 lp
->status
= status
;
2475 save_stop_reason (lp
);
2483 /* Return non-zero if LP has a wait status pending. Discard the
2484 pending event and resume the LWP if the event that originally
2485 caused the stop became uninteresting. */
2488 status_callback (struct lwp_info
*lp
)
2490 /* Only report a pending wait status if we pretend that this has
2491 indeed been resumed. */
2495 if (!lwp_status_pending_p (lp
))
2498 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
2499 || lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2501 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2505 pc
= regcache_read_pc (regcache
);
2507 if (pc
!= lp
->stop_pc
)
2509 linux_nat_debug_printf ("PC of %s changed. was=%s, now=%s",
2510 target_pid_to_str (lp
->ptid
).c_str (),
2511 paddress (target_gdbarch (), lp
->stop_pc
),
2512 paddress (target_gdbarch (), pc
));
2516 #if !USE_SIGTRAP_SIGINFO
2517 else if (!breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2519 linux_nat_debug_printf ("previous breakpoint of %s, at %s gone",
2520 target_pid_to_str (lp
->ptid
).c_str (),
2521 paddress (target_gdbarch (), lp
->stop_pc
));
2529 linux_nat_debug_printf ("pending event of %s cancelled.",
2530 target_pid_to_str (lp
->ptid
).c_str ());
2533 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2541 /* Count the LWP's that have had events. */
2544 count_events_callback (struct lwp_info
*lp
, int *count
)
2546 gdb_assert (count
!= NULL
);
2548 /* Select only resumed LWPs that have an event pending. */
2549 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2555 /* Select the LWP (if any) that is currently being single-stepped. */
2558 select_singlestep_lwp_callback (struct lwp_info
*lp
)
2560 if (lp
->last_resume_kind
== resume_step
2567 /* Returns true if LP has a status pending. */
2570 lwp_status_pending_p (struct lwp_info
*lp
)
2572 /* We check for lp->waitstatus in addition to lp->status, because we
2573 can have pending process exits recorded in lp->status and
2574 W_EXITCODE(0,0) happens to be 0. */
2575 return lp
->status
!= 0 || lp
->waitstatus
.kind
!= TARGET_WAITKIND_IGNORE
;
2578 /* Select the Nth LWP that has had an event. */
2581 select_event_lwp_callback (struct lwp_info
*lp
, int *selector
)
2583 gdb_assert (selector
!= NULL
);
2585 /* Select only resumed LWPs that have an event pending. */
2586 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2587 if ((*selector
)-- == 0)
2593 /* Called when the LWP stopped for a signal/trap. If it stopped for a
2594 trap check what caused it (breakpoint, watchpoint, trace, etc.),
2595 and save the result in the LWP's stop_reason field. If it stopped
2596 for a breakpoint, decrement the PC if necessary on the lwp's
2600 save_stop_reason (struct lwp_info
*lp
)
2602 struct regcache
*regcache
;
2603 struct gdbarch
*gdbarch
;
2606 #if USE_SIGTRAP_SIGINFO
2610 gdb_assert (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
);
2611 gdb_assert (lp
->status
!= 0);
2613 if (!linux_target
->low_status_is_event (lp
->status
))
2616 regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2617 gdbarch
= regcache
->arch ();
2619 pc
= regcache_read_pc (regcache
);
2620 sw_bp_pc
= pc
- gdbarch_decr_pc_after_break (gdbarch
);
2622 #if USE_SIGTRAP_SIGINFO
2623 if (linux_nat_get_siginfo (lp
->ptid
, &siginfo
))
2625 if (siginfo
.si_signo
== SIGTRAP
)
2627 if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
)
2628 && GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2630 /* The si_code is ambiguous on this arch -- check debug
2632 if (!check_stopped_by_watchpoint (lp
))
2633 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2635 else if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
))
2637 /* If we determine the LWP stopped for a SW breakpoint,
2638 trust it. Particularly don't check watchpoint
2639 registers, because, at least on s390, we'd find
2640 stopped-by-watchpoint as long as there's a watchpoint
2642 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2644 else if (GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2646 /* This can indicate either a hardware breakpoint or
2647 hardware watchpoint. Check debug registers. */
2648 if (!check_stopped_by_watchpoint (lp
))
2649 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2651 else if (siginfo
.si_code
== TRAP_TRACE
)
2653 linux_nat_debug_printf ("%s stopped by trace",
2654 target_pid_to_str (lp
->ptid
).c_str ());
2656 /* We may have single stepped an instruction that
2657 triggered a watchpoint. In that case, on some
2658 architectures (such as x86), instead of TRAP_HWBKPT,
2659 si_code indicates TRAP_TRACE, and we need to check
2660 the debug registers separately. */
2661 check_stopped_by_watchpoint (lp
);
2666 if ((!lp
->step
|| lp
->stop_pc
== sw_bp_pc
)
2667 && software_breakpoint_inserted_here_p (regcache
->aspace (),
2670 /* The LWP was either continued, or stepped a software
2671 breakpoint instruction. */
2672 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2675 if (hardware_breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2676 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2678 if (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
)
2679 check_stopped_by_watchpoint (lp
);
2682 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
)
2684 linux_nat_debug_printf ("%s stopped by software breakpoint",
2685 target_pid_to_str (lp
->ptid
).c_str ());
2687 /* Back up the PC if necessary. */
2689 regcache_write_pc (regcache
, sw_bp_pc
);
2691 /* Update this so we record the correct stop PC below. */
2694 else if (lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2696 linux_nat_debug_printf ("%s stopped by hardware breakpoint",
2697 target_pid_to_str (lp
->ptid
).c_str ());
2699 else if (lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
)
2701 linux_nat_debug_printf ("%s stopped by hardware watchpoint",
2702 target_pid_to_str (lp
->ptid
).c_str ());
2709 /* Returns true if the LWP had stopped for a software breakpoint. */
2712 linux_nat_target::stopped_by_sw_breakpoint ()
2714 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2716 gdb_assert (lp
!= NULL
);
2718 return lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
;
2721 /* Implement the supports_stopped_by_sw_breakpoint method. */
2724 linux_nat_target::supports_stopped_by_sw_breakpoint ()
2726 return USE_SIGTRAP_SIGINFO
;
2729 /* Returns true if the LWP had stopped for a hardware
2730 breakpoint/watchpoint. */
2733 linux_nat_target::stopped_by_hw_breakpoint ()
2735 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2737 gdb_assert (lp
!= NULL
);
2739 return lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
;
2742 /* Implement the supports_stopped_by_hw_breakpoint method. */
2745 linux_nat_target::supports_stopped_by_hw_breakpoint ()
2747 return USE_SIGTRAP_SIGINFO
;
2750 /* Select one LWP out of those that have events pending. */
2753 select_event_lwp (ptid_t filter
, struct lwp_info
**orig_lp
, int *status
)
2756 int random_selector
;
2757 struct lwp_info
*event_lp
= NULL
;
2759 /* Record the wait status for the original LWP. */
2760 (*orig_lp
)->status
= *status
;
2762 /* In all-stop, give preference to the LWP that is being
2763 single-stepped. There will be at most one, and it will be the
2764 LWP that the core is most interested in. If we didn't do this,
2765 then we'd have to handle pending step SIGTRAPs somehow in case
2766 the core later continues the previously-stepped thread, as
2767 otherwise we'd report the pending SIGTRAP then, and the core, not
2768 having stepped the thread, wouldn't understand what the trap was
2769 for, and therefore would report it to the user as a random
2771 if (!target_is_non_stop_p ())
2773 event_lp
= iterate_over_lwps (filter
, select_singlestep_lwp_callback
);
2774 if (event_lp
!= NULL
)
2776 linux_nat_debug_printf ("Select single-step %s",
2777 target_pid_to_str (event_lp
->ptid
).c_str ());
2781 if (event_lp
== NULL
)
2783 /* Pick one at random, out of those which have had events. */
2785 /* First see how many events we have. */
2786 iterate_over_lwps (filter
,
2787 [&] (struct lwp_info
*info
)
2789 return count_events_callback (info
, &num_events
);
2791 gdb_assert (num_events
> 0);
2793 /* Now randomly pick a LWP out of those that have had
2795 random_selector
= (int)
2796 ((num_events
* (double) rand ()) / (RAND_MAX
+ 1.0));
2799 linux_nat_debug_printf ("Found %d events, selecting #%d",
2800 num_events
, random_selector
);
2803 = (iterate_over_lwps
2805 [&] (struct lwp_info
*info
)
2807 return select_event_lwp_callback (info
,
2812 if (event_lp
!= NULL
)
2814 /* Switch the event LWP. */
2815 *orig_lp
= event_lp
;
2816 *status
= event_lp
->status
;
2819 /* Flush the wait status for the event LWP. */
2820 (*orig_lp
)->status
= 0;
2823 /* Return non-zero if LP has been resumed. */
2826 resumed_callback (struct lwp_info
*lp
)
2831 /* Check if we should go on and pass this event to common code.
2833 If so, save the status to the lwp_info structure associated to LWPID. */
2836 linux_nat_filter_event (int lwpid
, int status
)
2838 struct lwp_info
*lp
;
2839 int event
= linux_ptrace_get_extended_event (status
);
2841 lp
= find_lwp_pid (ptid_t (lwpid
));
2843 /* Check for stop events reported by a process we didn't already
2844 know about - anything not already in our LWP list.
2846 If we're expecting to receive stopped processes after
2847 fork, vfork, and clone events, then we'll just add the
2848 new one to our list and go back to waiting for the event
2849 to be reported - the stopped process might be returned
2850 from waitpid before or after the event is.
2852 But note the case of a non-leader thread exec'ing after the
2853 leader having exited, and gone from our lists. The non-leader
2854 thread changes its tid to the tgid. */
2856 if (WIFSTOPPED (status
) && lp
== NULL
2857 && (WSTOPSIG (status
) == SIGTRAP
&& event
== PTRACE_EVENT_EXEC
))
2859 /* A multi-thread exec after we had seen the leader exiting. */
2860 linux_nat_debug_printf ("Re-adding thread group leader LWP %d.", lwpid
);
2862 lp
= add_lwp (ptid_t (lwpid
, lwpid
, 0));
2865 add_thread (linux_target
, lp
->ptid
);
2868 if (WIFSTOPPED (status
) && !lp
)
2870 linux_nat_debug_printf ("saving LWP %ld status %s in stopped_pids list",
2871 (long) lwpid
, status_to_str (status
).c_str ());
2872 add_to_pid_list (&stopped_pids
, lwpid
, status
);
2876 /* Make sure we don't report an event for the exit of an LWP not in
2877 our list, i.e. not part of the current process. This can happen
2878 if we detach from a program we originally forked and then it
2880 if (!WIFSTOPPED (status
) && !lp
)
2883 /* This LWP is stopped now. (And if dead, this prevents it from
2884 ever being continued.) */
2887 if (WIFSTOPPED (status
) && lp
->must_set_ptrace_flags
)
2889 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2890 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
2892 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
2893 lp
->must_set_ptrace_flags
= 0;
2896 /* Handle GNU/Linux's syscall SIGTRAPs. */
2897 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
2899 /* No longer need the sysgood bit. The ptrace event ends up
2900 recorded in lp->waitstatus if we care for it. We can carry
2901 on handling the event like a regular SIGTRAP from here
2903 status
= W_STOPCODE (SIGTRAP
);
2904 if (linux_handle_syscall_trap (lp
, 0))
2909 /* Almost all other ptrace-stops are known to be outside of system
2910 calls, with further exceptions in linux_handle_extended_wait. */
2911 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
2914 /* Handle GNU/Linux's extended waitstatus for trace events. */
2915 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
2916 && linux_is_extended_waitstatus (status
))
2918 linux_nat_debug_printf ("Handling extended status 0x%06x", status
);
2920 if (linux_handle_extended_wait (lp
, status
))
2924 /* Check if the thread has exited. */
2925 if (WIFEXITED (status
) || WIFSIGNALED (status
))
2927 if (!report_thread_events
2928 && num_lwps (lp
->ptid
.pid ()) > 1)
2930 linux_nat_debug_printf ("%s exited.",
2931 target_pid_to_str (lp
->ptid
).c_str ());
2933 /* If there is at least one more LWP, then the exit signal
2934 was not the end of the debugged application and should be
2940 /* Note that even if the leader was ptrace-stopped, it can still
2941 exit, if e.g., some other thread brings down the whole
2942 process (calls `exit'). So don't assert that the lwp is
2944 linux_nat_debug_printf ("LWP %ld exited (resumed=%d)",
2945 lp
->ptid
.lwp (), lp
->resumed
);
2947 /* Dead LWP's aren't expected to reported a pending sigstop. */
2950 /* Store the pending event in the waitstatus, because
2951 W_EXITCODE(0,0) == 0. */
2952 store_waitstatus (&lp
->waitstatus
, status
);
2956 /* Make sure we don't report a SIGSTOP that we sent ourselves in
2957 an attempt to stop an LWP. */
2959 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGSTOP
)
2963 if (lp
->last_resume_kind
== resume_stop
)
2965 linux_nat_debug_printf ("resume_stop SIGSTOP caught for %s.",
2966 target_pid_to_str (lp
->ptid
).c_str ());
2970 /* This is a delayed SIGSTOP. Filter out the event. */
2972 linux_nat_debug_printf
2973 ("%s %s, 0, 0 (discard delayed SIGSTOP)",
2974 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
2975 target_pid_to_str (lp
->ptid
).c_str ());
2977 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2978 gdb_assert (lp
->resumed
);
2983 /* Make sure we don't report a SIGINT that we have already displayed
2984 for another thread. */
2985 if (lp
->ignore_sigint
2986 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGINT
)
2988 linux_nat_debug_printf ("Delayed SIGINT caught for %s.",
2989 target_pid_to_str (lp
->ptid
).c_str ());
2991 /* This is a delayed SIGINT. */
2992 lp
->ignore_sigint
= 0;
2994 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2995 linux_nat_debug_printf ("%s %s, 0, 0 (discard SIGINT)",
2996 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
2997 target_pid_to_str (lp
->ptid
).c_str ());
2998 gdb_assert (lp
->resumed
);
3000 /* Discard the event. */
3004 /* Don't report signals that GDB isn't interested in, such as
3005 signals that are neither printed nor stopped upon. Stopping all
3006 threads can be a bit time-consuming, so if we want decent
3007 performance with heavily multi-threaded programs, especially when
3008 they're using a high frequency timer, we'd better avoid it if we
3010 if (WIFSTOPPED (status
))
3012 enum gdb_signal signo
= gdb_signal_from_host (WSTOPSIG (status
));
3014 if (!target_is_non_stop_p ())
3016 /* Only do the below in all-stop, as we currently use SIGSTOP
3017 to implement target_stop (see linux_nat_stop) in
3019 if (signo
== GDB_SIGNAL_INT
&& signal_pass_state (signo
) == 0)
3021 /* If ^C/BREAK is typed at the tty/console, SIGINT gets
3022 forwarded to the entire process group, that is, all LWPs
3023 will receive it - unless they're using CLONE_THREAD to
3024 share signals. Since we only want to report it once, we
3025 mark it as ignored for all LWPs except this one. */
3026 iterate_over_lwps (ptid_t (lp
->ptid
.pid ()), set_ignore_sigint
);
3027 lp
->ignore_sigint
= 0;
3030 maybe_clear_ignore_sigint (lp
);
3033 /* When using hardware single-step, we need to report every signal.
3034 Otherwise, signals in pass_mask may be short-circuited
3035 except signals that might be caused by a breakpoint, or SIGSTOP
3036 if we sent the SIGSTOP and are waiting for it to arrive. */
3038 && WSTOPSIG (status
) && sigismember (&pass_mask
, WSTOPSIG (status
))
3039 && (WSTOPSIG (status
) != SIGSTOP
3040 || !find_thread_ptid (linux_target
, lp
->ptid
)->stop_requested
)
3041 && !linux_wstatus_maybe_breakpoint (status
))
3043 linux_resume_one_lwp (lp
, lp
->step
, signo
);
3044 linux_nat_debug_printf
3045 ("%s %s, %s (preempt 'handle')",
3046 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
3047 target_pid_to_str (lp
->ptid
).c_str (),
3048 (signo
!= GDB_SIGNAL_0
3049 ? strsignal (gdb_signal_to_host (signo
)) : "0"));
3054 /* An interesting event. */
3056 lp
->status
= status
;
3057 save_stop_reason (lp
);
3060 /* Detect zombie thread group leaders, and "exit" them. We can't reap
3061 their exits until all other threads in the group have exited. */
3064 check_zombie_leaders (void)
3066 for (inferior
*inf
: all_inferiors ())
3068 struct lwp_info
*leader_lp
;
3073 leader_lp
= find_lwp_pid (ptid_t (inf
->pid
));
3074 if (leader_lp
!= NULL
3075 /* Check if there are other threads in the group, as we may
3076 have raced with the inferior simply exiting. */
3077 && num_lwps (inf
->pid
) > 1
3078 && linux_proc_pid_is_zombie (inf
->pid
))
3080 linux_nat_debug_printf ("Thread group leader %d zombie "
3081 "(it exited, or another thread execd).",
3084 /* A leader zombie can mean one of two things:
3086 - It exited, and there's an exit status pending
3087 available, or only the leader exited (not the whole
3088 program). In the latter case, we can't waitpid the
3089 leader's exit status until all other threads are gone.
3091 - There are 3 or more threads in the group, and a thread
3092 other than the leader exec'd. See comments on exec
3093 events at the top of the file. We could try
3094 distinguishing the exit and exec cases, by waiting once
3095 more, and seeing if something comes out, but it doesn't
3096 sound useful. The previous leader _does_ go away, and
3097 we'll re-add the new one once we see the exec event
3098 (which is just the same as what would happen if the
3099 previous leader did exit voluntarily before some other
3102 linux_nat_debug_printf ("Thread group leader %d vanished.", inf
->pid
);
3103 exit_lwp (leader_lp
);
3108 /* Convenience function that is called when the kernel reports an exit
3109 event. This decides whether to report the event to GDB as a
3110 process exit event, a thread exit event, or to suppress the
3114 filter_exit_event (struct lwp_info
*event_child
,
3115 struct target_waitstatus
*ourstatus
)
3117 ptid_t ptid
= event_child
->ptid
;
3119 if (num_lwps (ptid
.pid ()) > 1)
3121 if (report_thread_events
)
3122 ourstatus
->kind
= TARGET_WAITKIND_THREAD_EXITED
;
3124 ourstatus
->kind
= TARGET_WAITKIND_IGNORE
;
3126 exit_lwp (event_child
);
3133 linux_nat_wait_1 (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3134 target_wait_flags target_options
)
3137 enum resume_kind last_resume_kind
;
3138 struct lwp_info
*lp
;
3141 linux_nat_debug_printf ("enter");
3143 /* The first time we get here after starting a new inferior, we may
3144 not have added it to the LWP list yet - this is the earliest
3145 moment at which we know its PID. */
3146 if (ptid
.is_pid () && find_lwp_pid (ptid
) == nullptr)
3148 ptid_t
lwp_ptid (ptid
.pid (), ptid
.pid ());
3150 /* Upgrade the main thread's ptid. */
3151 thread_change_ptid (linux_target
, ptid
, lwp_ptid
);
3152 lp
= add_initial_lwp (lwp_ptid
);
3156 /* Make sure SIGCHLD is blocked until the sigsuspend below. */
3157 block_child_signals (&prev_mask
);
3159 /* First check if there is a LWP with a wait status pending. */
3160 lp
= iterate_over_lwps (ptid
, status_callback
);
3163 linux_nat_debug_printf ("Using pending wait status %s for %s.",
3164 status_to_str (lp
->status
).c_str (),
3165 target_pid_to_str (lp
->ptid
).c_str ());
3168 /* But if we don't find a pending event, we'll have to wait. Always
3169 pull all events out of the kernel. We'll randomly select an
3170 event LWP out of all that have events, to prevent starvation. */
3176 /* Always use -1 and WNOHANG, due to couple of a kernel/ptrace
3179 - If the thread group leader exits while other threads in the
3180 thread group still exist, waitpid(TGID, ...) hangs. That
3181 waitpid won't return an exit status until the other threads
3182 in the group are reaped.
3184 - When a non-leader thread execs, that thread just vanishes
3185 without reporting an exit (so we'd hang if we waited for it
3186 explicitly in that case). The exec event is reported to
3190 lwpid
= my_waitpid (-1, &status
, __WALL
| WNOHANG
);
3192 linux_nat_debug_printf ("waitpid(-1, ...) returned %d, %s",
3194 errno
? safe_strerror (errno
) : "ERRNO-OK");
3198 linux_nat_debug_printf ("waitpid %ld received %s",
3200 status_to_str (status
).c_str ());
3202 linux_nat_filter_event (lwpid
, status
);
3203 /* Retry until nothing comes out of waitpid. A single
3204 SIGCHLD can indicate more than one child stopped. */
3208 /* Now that we've pulled all events out of the kernel, resume
3209 LWPs that don't have an interesting event to report. */
3210 iterate_over_lwps (minus_one_ptid
,
3211 [] (struct lwp_info
*info
)
3213 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
3216 /* ... and find an LWP with a status to report to the core, if
3218 lp
= iterate_over_lwps (ptid
, status_callback
);
3222 /* Check for zombie thread group leaders. Those can't be reaped
3223 until all other threads in the thread group are. */
3224 check_zombie_leaders ();
3226 /* If there are no resumed children left, bail. We'd be stuck
3227 forever in the sigsuspend call below otherwise. */
3228 if (iterate_over_lwps (ptid
, resumed_callback
) == NULL
)
3230 linux_nat_debug_printf ("exit (no resumed LWP)");
3232 ourstatus
->kind
= TARGET_WAITKIND_NO_RESUMED
;
3234 restore_child_signals_mask (&prev_mask
);
3235 return minus_one_ptid
;
3238 /* No interesting event to report to the core. */
3240 if (target_options
& TARGET_WNOHANG
)
3242 linux_nat_debug_printf ("exit (ignore)");
3244 ourstatus
->kind
= TARGET_WAITKIND_IGNORE
;
3245 restore_child_signals_mask (&prev_mask
);
3246 return minus_one_ptid
;
3249 /* We shouldn't end up here unless we want to try again. */
3250 gdb_assert (lp
== NULL
);
3252 /* Block until we get an event reported with SIGCHLD. */
3258 status
= lp
->status
;
3261 if (!target_is_non_stop_p ())
3263 /* Now stop all other LWP's ... */
3264 iterate_over_lwps (minus_one_ptid
, stop_callback
);
3266 /* ... and wait until all of them have reported back that
3267 they're no longer running. */
3268 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
3271 /* If we're not waiting for a specific LWP, choose an event LWP from
3272 among those that have had events. Giving equal priority to all
3273 LWPs that have had events helps prevent starvation. */
3274 if (ptid
== minus_one_ptid
|| ptid
.is_pid ())
3275 select_event_lwp (ptid
, &lp
, &status
);
3277 gdb_assert (lp
!= NULL
);
3279 /* Now that we've selected our final event LWP, un-adjust its PC if
3280 it was a software breakpoint, and we can't reliably support the
3281 "stopped by software breakpoint" stop reason. */
3282 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
3283 && !USE_SIGTRAP_SIGINFO
)
3285 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3286 struct gdbarch
*gdbarch
= regcache
->arch ();
3287 int decr_pc
= gdbarch_decr_pc_after_break (gdbarch
);
3293 pc
= regcache_read_pc (regcache
);
3294 regcache_write_pc (regcache
, pc
+ decr_pc
);
3298 /* We'll need this to determine whether to report a SIGSTOP as
3299 GDB_SIGNAL_0. Need to take a copy because resume_clear_callback
3301 last_resume_kind
= lp
->last_resume_kind
;
3303 if (!target_is_non_stop_p ())
3305 /* In all-stop, from the core's perspective, all LWPs are now
3306 stopped until a new resume action is sent over. */
3307 iterate_over_lwps (minus_one_ptid
, resume_clear_callback
);
3311 resume_clear_callback (lp
);
3314 if (linux_target
->low_status_is_event (status
))
3316 linux_nat_debug_printf ("trap ptid is %s.",
3317 target_pid_to_str (lp
->ptid
).c_str ());
3320 if (lp
->waitstatus
.kind
!= TARGET_WAITKIND_IGNORE
)
3322 *ourstatus
= lp
->waitstatus
;
3323 lp
->waitstatus
.kind
= TARGET_WAITKIND_IGNORE
;
3326 store_waitstatus (ourstatus
, status
);
3328 linux_nat_debug_printf ("exit");
3330 restore_child_signals_mask (&prev_mask
);
3332 if (last_resume_kind
== resume_stop
3333 && ourstatus
->kind
== TARGET_WAITKIND_STOPPED
3334 && WSTOPSIG (status
) == SIGSTOP
)
3336 /* A thread that has been requested to stop by GDB with
3337 target_stop, and it stopped cleanly, so report as SIG0. The
3338 use of SIGSTOP is an implementation detail. */
3339 ourstatus
->value
.sig
= GDB_SIGNAL_0
;
3342 if (ourstatus
->kind
== TARGET_WAITKIND_EXITED
3343 || ourstatus
->kind
== TARGET_WAITKIND_SIGNALLED
)
3346 lp
->core
= linux_common_core_of_thread (lp
->ptid
);
3348 if (ourstatus
->kind
== TARGET_WAITKIND_EXITED
)
3349 return filter_exit_event (lp
, ourstatus
);
3354 /* Resume LWPs that are currently stopped without any pending status
3355 to report, but are resumed from the core's perspective. */
3358 resume_stopped_resumed_lwps (struct lwp_info
*lp
, const ptid_t wait_ptid
)
3362 linux_nat_debug_printf ("NOT resuming LWP %s, not stopped",
3363 target_pid_to_str (lp
->ptid
).c_str ());
3365 else if (!lp
->resumed
)
3367 linux_nat_debug_printf ("NOT resuming LWP %s, not resumed",
3368 target_pid_to_str (lp
->ptid
).c_str ());
3370 else if (lwp_status_pending_p (lp
))
3372 linux_nat_debug_printf ("NOT resuming LWP %s, has pending status",
3373 target_pid_to_str (lp
->ptid
).c_str ());
3377 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3378 struct gdbarch
*gdbarch
= regcache
->arch ();
3382 CORE_ADDR pc
= regcache_read_pc (regcache
);
3383 int leave_stopped
= 0;
3385 /* Don't bother if there's a breakpoint at PC that we'd hit
3386 immediately, and we're not waiting for this LWP. */
3387 if (!lp
->ptid
.matches (wait_ptid
))
3389 if (breakpoint_inserted_here_p (regcache
->aspace (), pc
))
3395 linux_nat_debug_printf
3396 ("resuming stopped-resumed LWP %s at %s: step=%d",
3397 target_pid_to_str (lp
->ptid
).c_str (), paddress (gdbarch
, pc
),
3400 linux_resume_one_lwp_throw (lp
, lp
->step
, GDB_SIGNAL_0
);
3403 catch (const gdb_exception_error
&ex
)
3405 if (!check_ptrace_stopped_lwp_gone (lp
))
3414 linux_nat_target::wait (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3415 target_wait_flags target_options
)
3419 linux_nat_debug_printf ("[%s], [%s]", target_pid_to_str (ptid
).c_str (),
3420 target_options_to_string (target_options
).c_str ());
3422 /* Flush the async file first. */
3423 if (target_is_async_p ())
3424 async_file_flush ();
3426 /* Resume LWPs that are currently stopped without any pending status
3427 to report, but are resumed from the core's perspective. LWPs get
3428 in this state if we find them stopping at a time we're not
3429 interested in reporting the event (target_wait on a
3430 specific_process, for example, see linux_nat_wait_1), and
3431 meanwhile the event became uninteresting. Don't bother resuming
3432 LWPs we're not going to wait for if they'd stop immediately. */
3433 if (target_is_non_stop_p ())
3434 iterate_over_lwps (minus_one_ptid
,
3435 [=] (struct lwp_info
*info
)
3437 return resume_stopped_resumed_lwps (info
, ptid
);
3440 event_ptid
= linux_nat_wait_1 (ptid
, ourstatus
, target_options
);
3442 /* If we requested any event, and something came out, assume there
3443 may be more. If we requested a specific lwp or process, also
3444 assume there may be more. */
3445 if (target_is_async_p ()
3446 && ((ourstatus
->kind
!= TARGET_WAITKIND_IGNORE
3447 && ourstatus
->kind
!= TARGET_WAITKIND_NO_RESUMED
)
3448 || ptid
!= minus_one_ptid
))
3457 kill_one_lwp (pid_t pid
)
3459 /* PTRACE_KILL may resume the inferior. Send SIGKILL first. */
3462 kill_lwp (pid
, SIGKILL
);
3464 if (debug_linux_nat
)
3466 int save_errno
= errno
;
3468 linux_nat_debug_printf
3469 ("kill (SIGKILL) %ld, 0, 0 (%s)", (long) pid
,
3470 save_errno
!= 0 ? safe_strerror (save_errno
) : "OK");
3473 /* Some kernels ignore even SIGKILL for processes under ptrace. */
3476 ptrace (PTRACE_KILL
, pid
, 0, 0);
3477 if (debug_linux_nat
)
3479 int save_errno
= errno
;
3481 linux_nat_debug_printf
3482 ("PTRACE_KILL %ld, 0, 0 (%s)", (long) pid
,
3483 save_errno
? safe_strerror (save_errno
) : "OK");
3487 /* Wait for an LWP to die. */
3490 kill_wait_one_lwp (pid_t pid
)
3494 /* We must make sure that there are no pending events (delayed
3495 SIGSTOPs, pending SIGTRAPs, etc.) to make sure the current
3496 program doesn't interfere with any following debugging session. */
3500 res
= my_waitpid (pid
, NULL
, __WALL
);
3501 if (res
!= (pid_t
) -1)
3503 linux_nat_debug_printf ("wait %ld received unknown.", (long) pid
);
3505 /* The Linux kernel sometimes fails to kill a thread
3506 completely after PTRACE_KILL; that goes from the stop
3507 point in do_fork out to the one in get_signal_to_deliver
3508 and waits again. So kill it again. */
3514 gdb_assert (res
== -1 && errno
== ECHILD
);
3517 /* Callback for iterate_over_lwps. */
3520 kill_callback (struct lwp_info
*lp
)
3522 kill_one_lwp (lp
->ptid
.lwp ());
3526 /* Callback for iterate_over_lwps. */
3529 kill_wait_callback (struct lwp_info
*lp
)
3531 kill_wait_one_lwp (lp
->ptid
.lwp ());
3535 /* Kill the fork children of any threads of inferior INF that are
3536 stopped at a fork event. */
3539 kill_unfollowed_fork_children (struct inferior
*inf
)
3541 for (thread_info
*thread
: inf
->non_exited_threads ())
3543 struct target_waitstatus
*ws
= &thread
->pending_follow
;
3545 if (ws
->kind
== TARGET_WAITKIND_FORKED
3546 || ws
->kind
== TARGET_WAITKIND_VFORKED
)
3548 ptid_t child_ptid
= ws
->value
.related_pid
;
3549 int child_pid
= child_ptid
.pid ();
3550 int child_lwp
= child_ptid
.lwp ();
3552 kill_one_lwp (child_lwp
);
3553 kill_wait_one_lwp (child_lwp
);
3555 /* Let the arch-specific native code know this process is
3557 linux_target
->low_forget_process (child_pid
);
3563 linux_nat_target::kill ()
3565 /* If we're stopped while forking and we haven't followed yet,
3566 kill the other task. We need to do this first because the
3567 parent will be sleeping if this is a vfork. */
3568 kill_unfollowed_fork_children (current_inferior ());
3570 if (forks_exist_p ())
3571 linux_fork_killall ();
3574 ptid_t ptid
= ptid_t (inferior_ptid
.pid ());
3576 /* Stop all threads before killing them, since ptrace requires
3577 that the thread is stopped to successfully PTRACE_KILL. */
3578 iterate_over_lwps (ptid
, stop_callback
);
3579 /* ... and wait until all of them have reported back that
3580 they're no longer running. */
3581 iterate_over_lwps (ptid
, stop_wait_callback
);
3583 /* Kill all LWP's ... */
3584 iterate_over_lwps (ptid
, kill_callback
);
3586 /* ... and wait until we've flushed all events. */
3587 iterate_over_lwps (ptid
, kill_wait_callback
);
3590 target_mourn_inferior (inferior_ptid
);
3594 linux_nat_target::mourn_inferior ()
3596 int pid
= inferior_ptid
.pid ();
3598 purge_lwp_list (pid
);
3600 /* Close the /proc/<pid>/mem file if it was open for this
3602 maybe_close_proc_mem_file (pid
);
3604 if (! forks_exist_p ())
3605 /* Normal case, no other forks available. */
3606 inf_ptrace_target::mourn_inferior ();
3608 /* Multi-fork case. The current inferior_ptid has exited, but
3609 there are other viable forks to debug. Delete the exiting
3610 one and context-switch to the first available. */
3611 linux_fork_mourn_inferior ();
3613 /* Let the arch-specific native code know this process is gone. */
3614 linux_target
->low_forget_process (pid
);
3617 /* Convert a native/host siginfo object, into/from the siginfo in the
3618 layout of the inferiors' architecture. */
3621 siginfo_fixup (siginfo_t
*siginfo
, gdb_byte
*inf_siginfo
, int direction
)
3623 /* If the low target didn't do anything, then just do a straight
3625 if (!linux_target
->low_siginfo_fixup (siginfo
, inf_siginfo
, direction
))
3628 memcpy (siginfo
, inf_siginfo
, sizeof (siginfo_t
));
3630 memcpy (inf_siginfo
, siginfo
, sizeof (siginfo_t
));
3634 static enum target_xfer_status
3635 linux_xfer_siginfo (enum target_object object
,
3636 const char *annex
, gdb_byte
*readbuf
,
3637 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3638 ULONGEST
*xfered_len
)
3642 gdb_byte inf_siginfo
[sizeof (siginfo_t
)];
3644 gdb_assert (object
== TARGET_OBJECT_SIGNAL_INFO
);
3645 gdb_assert (readbuf
|| writebuf
);
3647 pid
= inferior_ptid
.lwp ();
3649 pid
= inferior_ptid
.pid ();
3651 if (offset
> sizeof (siginfo
))
3652 return TARGET_XFER_E_IO
;
3655 ptrace (PTRACE_GETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, &siginfo
);
3657 return TARGET_XFER_E_IO
;
3659 /* When GDB is built as a 64-bit application, ptrace writes into
3660 SIGINFO an object with 64-bit layout. Since debugging a 32-bit
3661 inferior with a 64-bit GDB should look the same as debugging it
3662 with a 32-bit GDB, we need to convert it. GDB core always sees
3663 the converted layout, so any read/write will have to be done
3665 siginfo_fixup (&siginfo
, inf_siginfo
, 0);
3667 if (offset
+ len
> sizeof (siginfo
))
3668 len
= sizeof (siginfo
) - offset
;
3670 if (readbuf
!= NULL
)
3671 memcpy (readbuf
, inf_siginfo
+ offset
, len
);
3674 memcpy (inf_siginfo
+ offset
, writebuf
, len
);
3676 /* Convert back to ptrace layout before flushing it out. */
3677 siginfo_fixup (&siginfo
, inf_siginfo
, 1);
3680 ptrace (PTRACE_SETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, &siginfo
);
3682 return TARGET_XFER_E_IO
;
3686 return TARGET_XFER_OK
;
3689 static enum target_xfer_status
3690 linux_nat_xfer_osdata (enum target_object object
,
3691 const char *annex
, gdb_byte
*readbuf
,
3692 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3693 ULONGEST
*xfered_len
);
3695 static enum target_xfer_status
3696 linux_proc_xfer_memory_partial (gdb_byte
*readbuf
, const gdb_byte
*writebuf
,
3697 ULONGEST offset
, LONGEST len
, ULONGEST
*xfered_len
);
3699 enum target_xfer_status
3700 linux_nat_target::xfer_partial (enum target_object object
,
3701 const char *annex
, gdb_byte
*readbuf
,
3702 const gdb_byte
*writebuf
,
3703 ULONGEST offset
, ULONGEST len
, ULONGEST
*xfered_len
)
3705 if (object
== TARGET_OBJECT_SIGNAL_INFO
)
3706 return linux_xfer_siginfo (object
, annex
, readbuf
, writebuf
,
3707 offset
, len
, xfered_len
);
3709 /* The target is connected but no live inferior is selected. Pass
3710 this request down to a lower stratum (e.g., the executable
3712 if (object
== TARGET_OBJECT_MEMORY
&& inferior_ptid
== null_ptid
)
3713 return TARGET_XFER_EOF
;
3715 if (object
== TARGET_OBJECT_AUXV
)
3716 return memory_xfer_auxv (this, object
, annex
, readbuf
, writebuf
,
3717 offset
, len
, xfered_len
);
3719 if (object
== TARGET_OBJECT_OSDATA
)
3720 return linux_nat_xfer_osdata (object
, annex
, readbuf
, writebuf
,
3721 offset
, len
, xfered_len
);
3723 if (object
== TARGET_OBJECT_MEMORY
)
3725 /* GDB calculates all addresses in the largest possible address
3726 width. The address width must be masked before its final use
3727 by linux_proc_xfer_partial.
3729 Compare ADDR_BIT first to avoid a compiler warning on shift overflow. */
3730 int addr_bit
= gdbarch_addr_bit (target_gdbarch ());
3732 if (addr_bit
< (sizeof (ULONGEST
) * HOST_CHAR_BIT
))
3733 offset
&= ((ULONGEST
) 1 << addr_bit
) - 1;
3735 return linux_proc_xfer_memory_partial (readbuf
, writebuf
,
3736 offset
, len
, xfered_len
);
3739 return inf_ptrace_target::xfer_partial (object
, annex
, readbuf
, writebuf
,
3740 offset
, len
, xfered_len
);
3744 linux_nat_target::thread_alive (ptid_t ptid
)
3746 /* As long as a PTID is in lwp list, consider it alive. */
3747 return find_lwp_pid (ptid
) != NULL
;
3750 /* Implement the to_update_thread_list target method for this
3754 linux_nat_target::update_thread_list ()
3756 struct lwp_info
*lwp
;
3758 /* We add/delete threads from the list as clone/exit events are
3759 processed, so just try deleting exited threads still in the
3761 delete_exited_threads ();
3763 /* Update the processor core that each lwp/thread was last seen
3767 /* Avoid accessing /proc if the thread hasn't run since we last
3768 time we fetched the thread's core. Accessing /proc becomes
3769 noticeably expensive when we have thousands of LWPs. */
3770 if (lwp
->core
== -1)
3771 lwp
->core
= linux_common_core_of_thread (lwp
->ptid
);
3776 linux_nat_target::pid_to_str (ptid_t ptid
)
3779 && (ptid
.pid () != ptid
.lwp ()
3780 || num_lwps (ptid
.pid ()) > 1))
3781 return string_printf ("LWP %ld", ptid
.lwp ());
3783 return normal_pid_to_str (ptid
);
3787 linux_nat_target::thread_name (struct thread_info
*thr
)
3789 return linux_proc_tid_get_name (thr
->ptid
);
3792 /* Accepts an integer PID; Returns a string representing a file that
3793 can be opened to get the symbols for the child process. */
3796 linux_nat_target::pid_to_exec_file (int pid
)
3798 return linux_proc_pid_to_exec_file (pid
);
3801 /* Keep the /proc/<pid>/mem file open between memory accesses, as a
3802 cache to avoid constantly closing/opening the file in the common
3803 case of multiple memory reads/writes from/to the same inferior.
3804 Note we don't keep a file open per inferior to avoid keeping too
3805 many file descriptors open, which can run into resource limits. */
3808 /* The LWP this open file is for. Note that after opening the file,
3809 even if the thread subsequently exits, the open file is still
3810 usable for accessing memory. It's only when the whole process
3811 exits or execs that the file becomes invalid (at which point
3812 reads/writes return EOF). */
3815 /* The file descriptor. -1 if file is not open. */
3818 /* Close FD and clear it to -1. */
3821 linux_nat_debug_printf ("closing fd %d for /proc/%d/task/%ld/mem\n",
3822 fd
, ptid
.pid (), ptid
.lwp ());
3826 } last_proc_mem_file
;
3828 /* Close the /proc/<pid>/mem file if its LWP matches PTID. */
3831 maybe_close_proc_mem_file (pid_t pid
)
3833 if (last_proc_mem_file
.ptid
.pid () == pid
)
3834 last_proc_mem_file
.close ();
3837 /* Helper for linux_proc_xfer_memory_partial. Accesses /proc via
3838 PTID. Returns -1 on error, with errno set. Returns number of
3839 read/written bytes otherwise. Returns 0 on EOF, which indicates
3840 the address space is gone (because the process exited or
3844 linux_proc_xfer_memory_partial_pid (ptid_t ptid
,
3845 gdb_byte
*readbuf
, const gdb_byte
*writebuf
,
3846 ULONGEST offset
, LONGEST len
)
3850 /* As long as we're hitting the same inferior, the previously open
3851 file is good, even if the thread it was open for exits. */
3852 if (last_proc_mem_file
.fd
!= -1
3853 && last_proc_mem_file
.ptid
.pid () != ptid
.pid ())
3854 last_proc_mem_file
.close ();
3856 if (last_proc_mem_file
.fd
== -1)
3858 /* Actually use /proc/<pid>/task/<lwp>/mem instead of
3859 /proc/<lwp>/mem to avoid PID-reuse races, as we may be trying
3860 to read memory via a thread which we've already reaped.
3861 /proc/<lwp>/mem could open a file for the wrong process. If
3862 the LWPID is reused for the same process it's OK, we can read
3863 memory through it just fine. If the LWPID is reused for a
3864 different process, then the open will fail because the path
3867 xsnprintf (filename
, sizeof filename
,
3868 "/proc/%d/task/%ld/mem", ptid
.pid (), ptid
.lwp ());
3870 last_proc_mem_file
.fd
3871 = gdb_open_cloexec (filename
, O_RDWR
| O_LARGEFILE
, 0);
3873 if (last_proc_mem_file
.fd
== -1)
3875 linux_nat_debug_printf ("opening %s failed: %s (%d)\n",
3876 filename
, safe_strerror (errno
), errno
);
3879 last_proc_mem_file
.ptid
= ptid
;
3881 linux_nat_debug_printf ("opened fd %d for %s\n",
3882 last_proc_mem_file
.fd
, filename
);
3885 int fd
= last_proc_mem_file
.fd
;
3887 /* Use pread64/pwrite64 if available, since they save a syscall and can
3888 handle 64-bit offsets even on 32-bit platforms (for instance, SPARC
3889 debugging a SPARC64 application). */
3891 ret
= (readbuf
? pread64 (fd
, readbuf
, len
, offset
)
3892 : pwrite64 (fd
, writebuf
, len
, offset
));
3894 ret
= lseek (fd
, offset
, SEEK_SET
);
3896 ret
= (readbuf
? read (fd
, readbuf
, len
)
3897 : write (fd
, writebuf
, len
));
3902 linux_nat_debug_printf ("accessing fd %d for pid %ld failed: %s (%d)\n",
3904 safe_strerror (errno
), errno
);
3908 linux_nat_debug_printf ("accessing fd %d for pid %ld got EOF\n",
3915 /* Implement the to_xfer_partial target method using /proc/<pid>/mem.
3916 Because we can use a single read/write call, this can be much more
3917 efficient than banging away at PTRACE_PEEKTEXT. Also, unlike
3918 PTRACE_PEEKTEXT/PTRACE_POKETEXT, this works with running
3921 static enum target_xfer_status
3922 linux_proc_xfer_memory_partial (gdb_byte
*readbuf
, const gdb_byte
*writebuf
,
3923 ULONGEST offset
, LONGEST len
,
3924 ULONGEST
*xfered_len
)
3926 /* Unlike PTRACE_PEEKTEXT/PTRACE_POKETEXT, reading/writing from/to
3927 /proc/<pid>/mem works with running threads, and even exited
3928 threads if the file was already open. If we need to open or
3929 reopen the /proc file though, we may get an EACCES error
3930 ("Permission denied"), meaning the thread is gone but its exit
3931 status isn't reaped yet, or ENOENT if the thread is gone and
3932 already reaped. In that case, just try opening the file for
3933 another thread in the process. If all threads fail, then it must
3934 mean the whole process exited, in which case there's nothing else
3935 to do and we just fail the memory access.
3937 Note we don't simply always access via the leader thread because
3938 the leader may exit without exiting the whole process. See
3939 gdb.threads/leader-exit.exp, for example. */
3941 /* It's frequently the case that the selected thread is stopped, and
3942 is thus not likely to exit (unless something kills the process
3943 outside our control, with e.g., SIGKILL). Give that one a try
3946 Also, inferior_ptid may actually point at an LWP not in lwp_list.
3947 This happens when we're detaching from a fork child that we don't
3948 want to debug ("set detach-on-fork on"), and the breakpoints
3949 module uninstalls breakpoints from the fork child. Which process
3950 to access is given by inferior_ptid. */
3951 int res
= linux_proc_xfer_memory_partial_pid (inferior_ptid
,
3956 /* EOF means the address space is gone, the whole
3957 process exited or execed. */
3958 return TARGET_XFER_EOF
;
3963 return TARGET_XFER_OK
;
3967 /* If we simply raced with the thread exiting (EACCES), or the
3968 current thread is THREAD_EXITED (ENOENT), try some other
3969 thread. It's easier to handle an ENOENT failure than check
3970 for THREAD_EXIT upfront because this function is called
3971 before a thread for inferior_ptid is added to the thread
3973 if (errno
!= EACCES
&& errno
!= ENOENT
)
3974 return TARGET_XFER_EOF
;
3977 int cur_pid
= current_inferior ()->pid
;
3979 if (inferior_ptid
.pid () != cur_pid
)
3981 /* We're accessing a fork child, and the access above failed.
3982 Don't bother iterating the LWP list, since there's no other
3983 LWP for this process. */
3984 return TARGET_XFER_EOF
;
3987 /* Iterate over LWPs of the current inferior, trying to access
3988 memory through one of them. */
3989 for (lwp_info
*lp
= lwp_list
; lp
!= nullptr; lp
= lp
->next
)
3991 if (lp
->ptid
.pid () != cur_pid
)
3994 res
= linux_proc_xfer_memory_partial_pid (lp
->ptid
,
4000 /* EOF means the address space is gone, the whole process
4001 exited or execed. */
4002 return TARGET_XFER_EOF
;
4006 if (errno
== EACCES
)
4008 /* This LWP is gone, try another one. */
4012 return TARGET_XFER_EOF
;
4016 return TARGET_XFER_OK
;
4020 return TARGET_XFER_EOF
;
4023 /* Parse LINE as a signal set and add its set bits to SIGS. */
4026 add_line_to_sigset (const char *line
, sigset_t
*sigs
)
4028 int len
= strlen (line
) - 1;
4032 if (line
[len
] != '\n')
4033 error (_("Could not parse signal set: %s"), line
);
4041 if (*p
>= '0' && *p
<= '9')
4043 else if (*p
>= 'a' && *p
<= 'f')
4044 digit
= *p
- 'a' + 10;
4046 error (_("Could not parse signal set: %s"), line
);
4051 sigaddset (sigs
, signum
+ 1);
4053 sigaddset (sigs
, signum
+ 2);
4055 sigaddset (sigs
, signum
+ 3);
4057 sigaddset (sigs
, signum
+ 4);
4063 /* Find process PID's pending signals from /proc/pid/status and set
4067 linux_proc_pending_signals (int pid
, sigset_t
*pending
,
4068 sigset_t
*blocked
, sigset_t
*ignored
)
4070 char buffer
[PATH_MAX
], fname
[PATH_MAX
];
4072 sigemptyset (pending
);
4073 sigemptyset (blocked
);
4074 sigemptyset (ignored
);
4075 xsnprintf (fname
, sizeof fname
, "/proc/%d/status", pid
);
4076 gdb_file_up procfile
= gdb_fopen_cloexec (fname
, "r");
4077 if (procfile
== NULL
)
4078 error (_("Could not open %s"), fname
);
4080 while (fgets (buffer
, PATH_MAX
, procfile
.get ()) != NULL
)
4082 /* Normal queued signals are on the SigPnd line in the status
4083 file. However, 2.6 kernels also have a "shared" pending
4084 queue for delivering signals to a thread group, so check for
4087 Unfortunately some Red Hat kernels include the shared pending
4088 queue but not the ShdPnd status field. */
4090 if (startswith (buffer
, "SigPnd:\t"))
4091 add_line_to_sigset (buffer
+ 8, pending
);
4092 else if (startswith (buffer
, "ShdPnd:\t"))
4093 add_line_to_sigset (buffer
+ 8, pending
);
4094 else if (startswith (buffer
, "SigBlk:\t"))
4095 add_line_to_sigset (buffer
+ 8, blocked
);
4096 else if (startswith (buffer
, "SigIgn:\t"))
4097 add_line_to_sigset (buffer
+ 8, ignored
);
4101 static enum target_xfer_status
4102 linux_nat_xfer_osdata (enum target_object object
,
4103 const char *annex
, gdb_byte
*readbuf
,
4104 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
4105 ULONGEST
*xfered_len
)
4107 gdb_assert (object
== TARGET_OBJECT_OSDATA
);
4109 *xfered_len
= linux_common_xfer_osdata (annex
, readbuf
, offset
, len
);
4110 if (*xfered_len
== 0)
4111 return TARGET_XFER_EOF
;
4113 return TARGET_XFER_OK
;
4116 std::vector
<static_tracepoint_marker
>
4117 linux_nat_target::static_tracepoint_markers_by_strid (const char *strid
)
4119 char s
[IPA_CMD_BUF_SIZE
];
4120 int pid
= inferior_ptid
.pid ();
4121 std::vector
<static_tracepoint_marker
> markers
;
4123 ptid_t ptid
= ptid_t (pid
, 0, 0);
4124 static_tracepoint_marker marker
;
4129 memcpy (s
, "qTfSTM", sizeof ("qTfSTM"));
4130 s
[sizeof ("qTfSTM")] = 0;
4132 agent_run_command (pid
, s
, strlen (s
) + 1);
4135 SCOPE_EXIT
{ target_continue_no_signal (ptid
); };
4141 parse_static_tracepoint_marker_definition (p
, &p
, &marker
);
4143 if (strid
== NULL
|| marker
.str_id
== strid
)
4144 markers
.push_back (std::move (marker
));
4146 while (*p
++ == ','); /* comma-separated list */
4148 memcpy (s
, "qTsSTM", sizeof ("qTsSTM"));
4149 s
[sizeof ("qTsSTM")] = 0;
4150 agent_run_command (pid
, s
, strlen (s
) + 1);
4157 /* target_is_async_p implementation. */
4160 linux_nat_target::is_async_p ()
4162 return linux_is_async_p ();
4165 /* target_can_async_p implementation. */
4168 linux_nat_target::can_async_p ()
4170 /* We're always async, unless the user explicitly prevented it with the
4171 "maint set target-async" command. */
4172 return target_async_permitted
;
4176 linux_nat_target::supports_non_stop ()
4181 /* to_always_non_stop_p implementation. */
4184 linux_nat_target::always_non_stop_p ()
4190 linux_nat_target::supports_multi_process ()
4196 linux_nat_target::supports_disable_randomization ()
4201 /* SIGCHLD handler that serves two purposes: In non-stop/async mode,
4202 so we notice when any child changes state, and notify the
4203 event-loop; it allows us to use sigsuspend in linux_nat_wait_1
4204 above to wait for the arrival of a SIGCHLD. */
4207 sigchld_handler (int signo
)
4209 int old_errno
= errno
;
4211 if (debug_linux_nat
)
4212 gdb_stdlog
->write_async_safe ("sigchld\n", sizeof ("sigchld\n") - 1);
4214 if (signo
== SIGCHLD
4215 && linux_nat_event_pipe
[0] != -1)
4216 async_file_mark (); /* Let the event loop know that there are
4217 events to handle. */
4222 /* Callback registered with the target events file descriptor. */
4225 handle_target_event (int error
, gdb_client_data client_data
)
4227 inferior_event_handler (INF_REG_EVENT
);
4230 /* Create/destroy the target events pipe. Returns previous state. */
4233 linux_async_pipe (int enable
)
4235 int previous
= linux_is_async_p ();
4237 if (previous
!= enable
)
4241 /* Block child signals while we create/destroy the pipe, as
4242 their handler writes to it. */
4243 block_child_signals (&prev_mask
);
4247 if (gdb_pipe_cloexec (linux_nat_event_pipe
) == -1)
4248 internal_error (__FILE__
, __LINE__
,
4249 "creating event pipe failed.");
4251 fcntl (linux_nat_event_pipe
[0], F_SETFL
, O_NONBLOCK
);
4252 fcntl (linux_nat_event_pipe
[1], F_SETFL
, O_NONBLOCK
);
4256 close (linux_nat_event_pipe
[0]);
4257 close (linux_nat_event_pipe
[1]);
4258 linux_nat_event_pipe
[0] = -1;
4259 linux_nat_event_pipe
[1] = -1;
4262 restore_child_signals_mask (&prev_mask
);
4269 linux_nat_target::async_wait_fd ()
4271 return linux_nat_event_pipe
[0];
4274 /* target_async implementation. */
4277 linux_nat_target::async (int enable
)
4281 if (!linux_async_pipe (1))
4283 add_file_handler (linux_nat_event_pipe
[0],
4284 handle_target_event
, NULL
,
4286 /* There may be pending events to handle. Tell the event loop
4293 delete_file_handler (linux_nat_event_pipe
[0]);
4294 linux_async_pipe (0);
4299 /* Stop an LWP, and push a GDB_SIGNAL_0 stop status if no other
4303 linux_nat_stop_lwp (struct lwp_info
*lwp
)
4307 linux_nat_debug_printf ("running -> suspending %s",
4308 target_pid_to_str (lwp
->ptid
).c_str ());
4311 if (lwp
->last_resume_kind
== resume_stop
)
4313 linux_nat_debug_printf ("already stopping LWP %ld at GDB's request",
4318 stop_callback (lwp
);
4319 lwp
->last_resume_kind
= resume_stop
;
4323 /* Already known to be stopped; do nothing. */
4325 if (debug_linux_nat
)
4327 if (find_thread_ptid (linux_target
, lwp
->ptid
)->stop_requested
)
4328 linux_nat_debug_printf ("already stopped/stop_requested %s",
4329 target_pid_to_str (lwp
->ptid
).c_str ());
4331 linux_nat_debug_printf ("already stopped/no stop_requested yet %s",
4332 target_pid_to_str (lwp
->ptid
).c_str ());
4339 linux_nat_target::stop (ptid_t ptid
)
4341 iterate_over_lwps (ptid
, linux_nat_stop_lwp
);
4345 linux_nat_target::close ()
4347 /* Unregister from the event loop. */
4351 inf_ptrace_target::close ();
4354 /* When requests are passed down from the linux-nat layer to the
4355 single threaded inf-ptrace layer, ptids of (lwpid,0,0) form are
4356 used. The address space pointer is stored in the inferior object,
4357 but the common code that is passed such ptid can't tell whether
4358 lwpid is a "main" process id or not (it assumes so). We reverse
4359 look up the "main" process id from the lwp here. */
4361 struct address_space
*
4362 linux_nat_target::thread_address_space (ptid_t ptid
)
4364 struct lwp_info
*lwp
;
4365 struct inferior
*inf
;
4368 if (ptid
.lwp () == 0)
4370 /* An (lwpid,0,0) ptid. Look up the lwp object to get at the
4372 lwp
= find_lwp_pid (ptid
);
4373 pid
= lwp
->ptid
.pid ();
4377 /* A (pid,lwpid,0) ptid. */
4381 inf
= find_inferior_pid (this, pid
);
4382 gdb_assert (inf
!= NULL
);
4386 /* Return the cached value of the processor core for thread PTID. */
4389 linux_nat_target::core_of_thread (ptid_t ptid
)
4391 struct lwp_info
*info
= find_lwp_pid (ptid
);
4398 /* Implementation of to_filesystem_is_local. */
4401 linux_nat_target::filesystem_is_local ()
4403 struct inferior
*inf
= current_inferior ();
4405 if (inf
->fake_pid_p
|| inf
->pid
== 0)
4408 return linux_ns_same (inf
->pid
, LINUX_NS_MNT
);
4411 /* Convert the INF argument passed to a to_fileio_* method
4412 to a process ID suitable for passing to its corresponding
4413 linux_mntns_* function. If INF is non-NULL then the
4414 caller is requesting the filesystem seen by INF. If INF
4415 is NULL then the caller is requesting the filesystem seen
4416 by the GDB. We fall back to GDB's filesystem in the case
4417 that INF is non-NULL but its PID is unknown. */
4420 linux_nat_fileio_pid_of (struct inferior
*inf
)
4422 if (inf
== NULL
|| inf
->fake_pid_p
|| inf
->pid
== 0)
4428 /* Implementation of to_fileio_open. */
4431 linux_nat_target::fileio_open (struct inferior
*inf
, const char *filename
,
4432 int flags
, int mode
, int warn_if_slow
,
4439 if (fileio_to_host_openflags (flags
, &nat_flags
) == -1
4440 || fileio_to_host_mode (mode
, &nat_mode
) == -1)
4442 *target_errno
= FILEIO_EINVAL
;
4446 fd
= linux_mntns_open_cloexec (linux_nat_fileio_pid_of (inf
),
4447 filename
, nat_flags
, nat_mode
);
4449 *target_errno
= host_to_fileio_error (errno
);
4454 /* Implementation of to_fileio_readlink. */
4456 gdb::optional
<std::string
>
4457 linux_nat_target::fileio_readlink (struct inferior
*inf
, const char *filename
,
4463 len
= linux_mntns_readlink (linux_nat_fileio_pid_of (inf
),
4464 filename
, buf
, sizeof (buf
));
4467 *target_errno
= host_to_fileio_error (errno
);
4471 return std::string (buf
, len
);
4474 /* Implementation of to_fileio_unlink. */
4477 linux_nat_target::fileio_unlink (struct inferior
*inf
, const char *filename
,
4482 ret
= linux_mntns_unlink (linux_nat_fileio_pid_of (inf
),
4485 *target_errno
= host_to_fileio_error (errno
);
4490 /* Implementation of the to_thread_events method. */
4493 linux_nat_target::thread_events (int enable
)
4495 report_thread_events
= enable
;
4498 linux_nat_target::linux_nat_target ()
4500 /* We don't change the stratum; this target will sit at
4501 process_stratum and thread_db will set at thread_stratum. This
4502 is a little strange, since this is a multi-threaded-capable
4503 target, but we want to be on the stack below thread_db, and we
4504 also want to be used for single-threaded processes. */
4507 /* See linux-nat.h. */
4510 linux_nat_get_siginfo (ptid_t ptid
, siginfo_t
*siginfo
)
4519 ptrace (PTRACE_GETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, siginfo
);
4522 memset (siginfo
, 0, sizeof (*siginfo
));
4528 /* See nat/linux-nat.h. */
4531 current_lwp_ptid (void)
4533 gdb_assert (inferior_ptid
.lwp_p ());
4534 return inferior_ptid
;
4537 void _initialize_linux_nat ();
4539 _initialize_linux_nat ()
4541 add_setshow_zuinteger_cmd ("lin-lwp", class_maintenance
,
4542 &debug_linux_nat
, _("\
4543 Set debugging of GNU/Linux lwp module."), _("\
4544 Show debugging of GNU/Linux lwp module."), _("\
4545 Enables printf debugging output."),
4547 show_debug_linux_nat
,
4548 &setdebuglist
, &showdebuglist
);
4550 add_setshow_boolean_cmd ("linux-namespaces", class_maintenance
,
4551 &debug_linux_namespaces
, _("\
4552 Set debugging of GNU/Linux namespaces module."), _("\
4553 Show debugging of GNU/Linux namespaces module."), _("\
4554 Enables printf debugging output."),
4557 &setdebuglist
, &showdebuglist
);
4559 /* Install a SIGCHLD handler. */
4560 sigchld_action
.sa_handler
= sigchld_handler
;
4561 sigemptyset (&sigchld_action
.sa_mask
);
4562 sigchld_action
.sa_flags
= SA_RESTART
;
4564 /* Make it the default. */
4565 sigaction (SIGCHLD
, &sigchld_action
, NULL
);
4567 /* Make sure we don't block SIGCHLD during a sigsuspend. */
4568 gdb_sigmask (SIG_SETMASK
, NULL
, &suspend_mask
);
4569 sigdelset (&suspend_mask
, SIGCHLD
);
4571 sigemptyset (&blocked_mask
);
4573 lwp_lwpid_htab_create ();
4577 /* FIXME: kettenis/2000-08-26: The stuff on this page is specific to
4578 the GNU/Linux Threads library and therefore doesn't really belong
4581 /* NPTL reserves the first two RT signals, but does not provide any
4582 way for the debugger to query the signal numbers - fortunately
4583 they don't change. */
4584 static int lin_thread_signals
[] = { __SIGRTMIN
, __SIGRTMIN
+ 1 };
4586 /* See linux-nat.h. */
4589 lin_thread_get_thread_signal_num (void)
4591 return sizeof (lin_thread_signals
) / sizeof (lin_thread_signals
[0]);
4594 /* See linux-nat.h. */
4597 lin_thread_get_thread_signal (unsigned int i
)
4599 gdb_assert (i
< lin_thread_get_thread_signal_num ());
4600 return lin_thread_signals
[i
];