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
)
1306 /* If the thread has a pending event, and it was stopped with a
1307 signal, use that signal to resume it. If it has a pending
1308 event of another kind, it was not stopped with a signal, so
1309 resume it without a signal. */
1310 if (tp
->suspend
.waitstatus
.kind
== TARGET_WAITKIND_STOPPED
)
1311 signo
= tp
->suspend
.waitstatus
.value
.sig
;
1313 signo
= GDB_SIGNAL_0
;
1316 signo
= tp
->suspend
.stop_signal
;
1318 else if (!target_is_non_stop_p ())
1321 process_stratum_target
*last_target
;
1323 get_last_target_status (&last_target
, &last_ptid
, nullptr);
1325 if (last_target
== linux_target
1326 && lp
->ptid
.lwp () == last_ptid
.lwp ())
1327 signo
= tp
->suspend
.stop_signal
;
1331 if (signo
== GDB_SIGNAL_0
)
1333 linux_nat_debug_printf ("lwp %s has no pending signal",
1334 target_pid_to_str (lp
->ptid
).c_str ());
1336 else if (!signal_pass_state (signo
))
1338 linux_nat_debug_printf
1339 ("lwp %s had signal %s but it is in no pass state",
1340 target_pid_to_str (lp
->ptid
).c_str (), gdb_signal_to_string (signo
));
1344 linux_nat_debug_printf ("lwp %s has pending signal %s",
1345 target_pid_to_str (lp
->ptid
).c_str (),
1346 gdb_signal_to_string (signo
));
1348 return gdb_signal_to_host (signo
);
1354 /* Detach from LP. If SIGNO_P is non-NULL, then it points to the
1355 signal number that should be passed to the LWP when detaching.
1356 Otherwise pass any pending signal the LWP may have, if any. */
1359 detach_one_lwp (struct lwp_info
*lp
, int *signo_p
)
1361 int lwpid
= lp
->ptid
.lwp ();
1364 gdb_assert (lp
->status
== 0 || WIFSTOPPED (lp
->status
));
1366 /* If the lwp/thread we are about to detach has a pending fork event,
1367 there is a process GDB is attached to that the core of GDB doesn't know
1368 about. Detach from it. */
1370 /* Check for a pending fork event stored in the lwp_info structure
1371 (not reported to the core). */
1372 if (WIFSTOPPED (lp
->status
) && linux_is_extended_waitstatus (lp
->status
))
1374 int event
= linux_ptrace_get_extended_event (lp
->status
);
1376 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
)
1378 unsigned long child_pid
;
1379 int ret
= ptrace (PTRACE_GETEVENTMSG
, lp
->ptid
.lwp (), 0, &child_pid
);
1381 ptrace (PTRACE_DETACH
, child_pid
, 0, 0);
1383 perror_warning_with_name (_("Failed to detach fork child"));
1387 /* Check for a pending fork event stored in the thread_info structure
1388 (reported to the core). */
1389 thread_info
*thread
= find_thread_ptid (linux_target
, lp
->ptid
);
1390 gdb_assert (thread
!= nullptr);
1391 if (thread
->suspend
.waitstatus_pending_p
)
1393 const target_waitstatus
&ws
= thread
->suspend
.waitstatus
;
1395 if (ws
.kind
== TARGET_WAITKIND_FORKED
1396 || ws
.kind
== TARGET_WAITKIND_VFORKED
)
1398 /* We have not created an lwp for this process. */
1399 gdb_assert (find_lwp_pid (ws
.value
.related_pid
) == nullptr);
1401 ptrace (PTRACE_DETACH
, ws
.value
.related_pid
.pid (), 0, 0);
1406 if (lp
->status
!= 0)
1407 linux_nat_debug_printf ("Pending %s for %s on detach.",
1408 strsignal (WSTOPSIG (lp
->status
)),
1409 target_pid_to_str (lp
->ptid
).c_str ());
1411 /* If there is a pending SIGSTOP, get rid of it. */
1414 linux_nat_debug_printf ("Sending SIGCONT to %s",
1415 target_pid_to_str (lp
->ptid
).c_str ());
1417 kill_lwp (lwpid
, SIGCONT
);
1421 if (signo_p
== NULL
)
1423 /* Pass on any pending signal for this LWP. */
1424 signo
= get_detach_signal (lp
);
1429 /* Preparing to resume may try to write registers, and fail if the
1430 lwp is zombie. If that happens, ignore the error. We'll handle
1431 it below, when detach fails with ESRCH. */
1434 linux_target
->low_prepare_to_resume (lp
);
1436 catch (const gdb_exception_error
&ex
)
1438 if (!check_ptrace_stopped_lwp_gone (lp
))
1442 if (ptrace (PTRACE_DETACH
, lwpid
, 0, signo
) < 0)
1444 int save_errno
= errno
;
1446 /* We know the thread exists, so ESRCH must mean the lwp is
1447 zombie. This can happen if one of the already-detached
1448 threads exits the whole thread group. In that case we're
1449 still attached, and must reap the lwp. */
1450 if (save_errno
== ESRCH
)
1454 ret
= my_waitpid (lwpid
, &status
, __WALL
);
1457 warning (_("Couldn't reap LWP %d while detaching: %s"),
1458 lwpid
, safe_strerror (errno
));
1460 else if (!WIFEXITED (status
) && !WIFSIGNALED (status
))
1462 warning (_("Reaping LWP %d while detaching "
1463 "returned unexpected status 0x%x"),
1469 error (_("Can't detach %s: %s"),
1470 target_pid_to_str (lp
->ptid
).c_str (),
1471 safe_strerror (save_errno
));
1475 linux_nat_debug_printf ("PTRACE_DETACH (%s, %s, 0) (OK)",
1476 target_pid_to_str (lp
->ptid
).c_str (),
1479 delete_lwp (lp
->ptid
);
1483 detach_callback (struct lwp_info
*lp
)
1485 /* We don't actually detach from the thread group leader just yet.
1486 If the thread group exits, we must reap the zombie clone lwps
1487 before we're able to reap the leader. */
1488 if (lp
->ptid
.lwp () != lp
->ptid
.pid ())
1489 detach_one_lwp (lp
, NULL
);
1494 linux_nat_target::detach (inferior
*inf
, int from_tty
)
1496 struct lwp_info
*main_lwp
;
1499 /* Don't unregister from the event loop, as there may be other
1500 inferiors running. */
1502 /* Stop all threads before detaching. ptrace requires that the
1503 thread is stopped to successfully detach. */
1504 iterate_over_lwps (ptid_t (pid
), stop_callback
);
1505 /* ... and wait until all of them have reported back that
1506 they're no longer running. */
1507 iterate_over_lwps (ptid_t (pid
), stop_wait_callback
);
1509 /* We can now safely remove breakpoints. We don't this in earlier
1510 in common code because this target doesn't currently support
1511 writing memory while the inferior is running. */
1512 remove_breakpoints_inf (current_inferior ());
1514 iterate_over_lwps (ptid_t (pid
), detach_callback
);
1516 /* Only the initial process should be left right now. */
1517 gdb_assert (num_lwps (pid
) == 1);
1519 main_lwp
= find_lwp_pid (ptid_t (pid
));
1521 if (forks_exist_p ())
1523 /* Multi-fork case. The current inferior_ptid is being detached
1524 from, but there are other viable forks to debug. Detach from
1525 the current fork, and context-switch to the first
1527 linux_fork_detach (from_tty
);
1531 target_announce_detach (from_tty
);
1533 /* Pass on any pending signal for the last LWP. */
1534 int signo
= get_detach_signal (main_lwp
);
1536 detach_one_lwp (main_lwp
, &signo
);
1538 detach_success (inf
);
1541 maybe_close_proc_mem_file (pid
);
1544 /* Resume execution of the inferior process. If STEP is nonzero,
1545 single-step it. If SIGNAL is nonzero, give it that signal. */
1548 linux_resume_one_lwp_throw (struct lwp_info
*lp
, int step
,
1549 enum gdb_signal signo
)
1553 /* stop_pc doubles as the PC the LWP had when it was last resumed.
1554 We only presently need that if the LWP is stepped though (to
1555 handle the case of stepping a breakpoint instruction). */
1558 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
1560 lp
->stop_pc
= regcache_read_pc (regcache
);
1565 linux_target
->low_prepare_to_resume (lp
);
1566 linux_target
->low_resume (lp
->ptid
, step
, signo
);
1568 /* Successfully resumed. Clear state that no longer makes sense,
1569 and mark the LWP as running. Must not do this before resuming
1570 otherwise if that fails other code will be confused. E.g., we'd
1571 later try to stop the LWP and hang forever waiting for a stop
1572 status. Note that we must not throw after this is cleared,
1573 otherwise handle_zombie_lwp_error would get confused. */
1576 lp
->stop_reason
= TARGET_STOPPED_BY_NO_REASON
;
1577 registers_changed_ptid (linux_target
, lp
->ptid
);
1580 /* Called when we try to resume a stopped LWP and that errors out. If
1581 the LWP is no longer in ptrace-stopped state (meaning it's zombie,
1582 or about to become), discard the error, clear any pending status
1583 the LWP may have, and return true (we'll collect the exit status
1584 soon enough). Otherwise, return false. */
1587 check_ptrace_stopped_lwp_gone (struct lwp_info
*lp
)
1589 /* If we get an error after resuming the LWP successfully, we'd
1590 confuse !T state for the LWP being gone. */
1591 gdb_assert (lp
->stopped
);
1593 /* We can't just check whether the LWP is in 'Z (Zombie)' state,
1594 because even if ptrace failed with ESRCH, the tracee may be "not
1595 yet fully dead", but already refusing ptrace requests. In that
1596 case the tracee has 'R (Running)' state for a little bit
1597 (observed in Linux 3.18). See also the note on ESRCH in the
1598 ptrace(2) man page. Instead, check whether the LWP has any state
1599 other than ptrace-stopped. */
1601 /* Don't assume anything if /proc/PID/status can't be read. */
1602 if (linux_proc_pid_is_trace_stopped_nowarn (lp
->ptid
.lwp ()) == 0)
1604 lp
->stop_reason
= TARGET_STOPPED_BY_NO_REASON
;
1606 lp
->waitstatus
.kind
= TARGET_WAITKIND_IGNORE
;
1612 /* Like linux_resume_one_lwp_throw, but no error is thrown if the LWP
1613 disappears while we try to resume it. */
1616 linux_resume_one_lwp (struct lwp_info
*lp
, int step
, enum gdb_signal signo
)
1620 linux_resume_one_lwp_throw (lp
, step
, signo
);
1622 catch (const gdb_exception_error
&ex
)
1624 if (!check_ptrace_stopped_lwp_gone (lp
))
1632 resume_lwp (struct lwp_info
*lp
, int step
, enum gdb_signal signo
)
1636 struct inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
1638 if (inf
->vfork_child
!= NULL
)
1640 linux_nat_debug_printf ("Not resuming %s (vfork parent)",
1641 target_pid_to_str (lp
->ptid
).c_str ());
1643 else if (!lwp_status_pending_p (lp
))
1645 linux_nat_debug_printf ("Resuming sibling %s, %s, %s",
1646 target_pid_to_str (lp
->ptid
).c_str (),
1647 (signo
!= GDB_SIGNAL_0
1648 ? strsignal (gdb_signal_to_host (signo
))
1650 step
? "step" : "resume");
1652 linux_resume_one_lwp (lp
, step
, signo
);
1656 linux_nat_debug_printf ("Not resuming sibling %s (has pending)",
1657 target_pid_to_str (lp
->ptid
).c_str ());
1661 linux_nat_debug_printf ("Not resuming sibling %s (not stopped)",
1662 target_pid_to_str (lp
->ptid
).c_str ());
1665 /* Callback for iterate_over_lwps. If LWP is EXCEPT, do nothing.
1666 Resume LWP with the last stop signal, if it is in pass state. */
1669 linux_nat_resume_callback (struct lwp_info
*lp
, struct lwp_info
*except
)
1671 enum gdb_signal signo
= GDB_SIGNAL_0
;
1678 struct thread_info
*thread
;
1680 thread
= find_thread_ptid (linux_target
, lp
->ptid
);
1683 signo
= thread
->suspend
.stop_signal
;
1684 thread
->suspend
.stop_signal
= GDB_SIGNAL_0
;
1688 resume_lwp (lp
, 0, signo
);
1693 resume_clear_callback (struct lwp_info
*lp
)
1696 lp
->last_resume_kind
= resume_stop
;
1701 resume_set_callback (struct lwp_info
*lp
)
1704 lp
->last_resume_kind
= resume_continue
;
1709 linux_nat_target::resume (ptid_t ptid
, int step
, enum gdb_signal signo
)
1711 struct lwp_info
*lp
;
1714 linux_nat_debug_printf ("Preparing to %s %s, %s, inferior_ptid %s",
1715 step
? "step" : "resume",
1716 target_pid_to_str (ptid
).c_str (),
1717 (signo
!= GDB_SIGNAL_0
1718 ? strsignal (gdb_signal_to_host (signo
)) : "0"),
1719 target_pid_to_str (inferior_ptid
).c_str ());
1721 /* A specific PTID means `step only this process id'. */
1722 resume_many
= (minus_one_ptid
== ptid
1725 /* Mark the lwps we're resuming as resumed and update their
1726 last_resume_kind to resume_continue. */
1727 iterate_over_lwps (ptid
, resume_set_callback
);
1729 /* See if it's the current inferior that should be handled
1732 lp
= find_lwp_pid (inferior_ptid
);
1734 lp
= find_lwp_pid (ptid
);
1735 gdb_assert (lp
!= NULL
);
1737 /* Remember if we're stepping. */
1738 lp
->last_resume_kind
= step
? resume_step
: resume_continue
;
1740 /* If we have a pending wait status for this thread, there is no
1741 point in resuming the process. But first make sure that
1742 linux_nat_wait won't preemptively handle the event - we
1743 should never take this short-circuit if we are going to
1744 leave LP running, since we have skipped resuming all the
1745 other threads. This bit of code needs to be synchronized
1746 with linux_nat_wait. */
1748 if (lp
->status
&& WIFSTOPPED (lp
->status
))
1751 && WSTOPSIG (lp
->status
)
1752 && sigismember (&pass_mask
, WSTOPSIG (lp
->status
)))
1754 linux_nat_debug_printf
1755 ("Not short circuiting for ignored status 0x%x", lp
->status
);
1757 /* FIXME: What should we do if we are supposed to continue
1758 this thread with a signal? */
1759 gdb_assert (signo
== GDB_SIGNAL_0
);
1760 signo
= gdb_signal_from_host (WSTOPSIG (lp
->status
));
1765 if (lwp_status_pending_p (lp
))
1767 /* FIXME: What should we do if we are supposed to continue
1768 this thread with a signal? */
1769 gdb_assert (signo
== GDB_SIGNAL_0
);
1771 linux_nat_debug_printf ("Short circuiting for status 0x%x",
1774 if (target_can_async_p ())
1777 /* Tell the event loop we have something to process. */
1784 iterate_over_lwps (ptid
, [=] (struct lwp_info
*info
)
1786 return linux_nat_resume_callback (info
, lp
);
1789 linux_nat_debug_printf ("%s %s, %s (resume event thread)",
1790 step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
1791 target_pid_to_str (lp
->ptid
).c_str (),
1792 (signo
!= GDB_SIGNAL_0
1793 ? strsignal (gdb_signal_to_host (signo
)) : "0"));
1795 linux_resume_one_lwp (lp
, step
, signo
);
1797 if (target_can_async_p ())
1801 /* Send a signal to an LWP. */
1804 kill_lwp (int lwpid
, int signo
)
1809 ret
= syscall (__NR_tkill
, lwpid
, signo
);
1810 if (errno
== ENOSYS
)
1812 /* If tkill fails, then we are not using nptl threads, a
1813 configuration we no longer support. */
1814 perror_with_name (("tkill"));
1819 /* Handle a GNU/Linux syscall trap wait response. If we see a syscall
1820 event, check if the core is interested in it: if not, ignore the
1821 event, and keep waiting; otherwise, we need to toggle the LWP's
1822 syscall entry/exit status, since the ptrace event itself doesn't
1823 indicate it, and report the trap to higher layers. */
1826 linux_handle_syscall_trap (struct lwp_info
*lp
, int stopping
)
1828 struct target_waitstatus
*ourstatus
= &lp
->waitstatus
;
1829 struct gdbarch
*gdbarch
= target_thread_architecture (lp
->ptid
);
1830 thread_info
*thread
= find_thread_ptid (linux_target
, lp
->ptid
);
1831 int syscall_number
= (int) gdbarch_get_syscall_number (gdbarch
, thread
);
1835 /* If we're stopping threads, there's a SIGSTOP pending, which
1836 makes it so that the LWP reports an immediate syscall return,
1837 followed by the SIGSTOP. Skip seeing that "return" using
1838 PTRACE_CONT directly, and let stop_wait_callback collect the
1839 SIGSTOP. Later when the thread is resumed, a new syscall
1840 entry event. If we didn't do this (and returned 0), we'd
1841 leave a syscall entry pending, and our caller, by using
1842 PTRACE_CONT to collect the SIGSTOP, skips the syscall return
1843 itself. Later, when the user re-resumes this LWP, we'd see
1844 another syscall entry event and we'd mistake it for a return.
1846 If stop_wait_callback didn't force the SIGSTOP out of the LWP
1847 (leaving immediately with LWP->signalled set, without issuing
1848 a PTRACE_CONT), it would still be problematic to leave this
1849 syscall enter pending, as later when the thread is resumed,
1850 it would then see the same syscall exit mentioned above,
1851 followed by the delayed SIGSTOP, while the syscall didn't
1852 actually get to execute. It seems it would be even more
1853 confusing to the user. */
1855 linux_nat_debug_printf
1856 ("ignoring syscall %d for LWP %ld (stopping threads), resuming with "
1857 "PTRACE_CONT for SIGSTOP", syscall_number
, lp
->ptid
.lwp ());
1859 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
1860 ptrace (PTRACE_CONT
, lp
->ptid
.lwp (), 0, 0);
1865 /* Always update the entry/return state, even if this particular
1866 syscall isn't interesting to the core now. In async mode,
1867 the user could install a new catchpoint for this syscall
1868 between syscall enter/return, and we'll need to know to
1869 report a syscall return if that happens. */
1870 lp
->syscall_state
= (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1871 ? TARGET_WAITKIND_SYSCALL_RETURN
1872 : TARGET_WAITKIND_SYSCALL_ENTRY
);
1874 if (catch_syscall_enabled ())
1876 if (catching_syscall_number (syscall_number
))
1878 /* Alright, an event to report. */
1879 ourstatus
->kind
= lp
->syscall_state
;
1880 ourstatus
->value
.syscall_number
= syscall_number
;
1882 linux_nat_debug_printf
1883 ("stopping for %s of syscall %d for LWP %ld",
1884 (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1885 ? "entry" : "return"), syscall_number
, lp
->ptid
.lwp ());
1890 linux_nat_debug_printf
1891 ("ignoring %s of syscall %d for LWP %ld",
1892 (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1893 ? "entry" : "return"), syscall_number
, lp
->ptid
.lwp ());
1897 /* If we had been syscall tracing, and hence used PT_SYSCALL
1898 before on this LWP, it could happen that the user removes all
1899 syscall catchpoints before we get to process this event.
1900 There are two noteworthy issues here:
1902 - When stopped at a syscall entry event, resuming with
1903 PT_STEP still resumes executing the syscall and reports a
1906 - Only PT_SYSCALL catches syscall enters. If we last
1907 single-stepped this thread, then this event can't be a
1908 syscall enter. If we last single-stepped this thread, this
1909 has to be a syscall exit.
1911 The points above mean that the next resume, be it PT_STEP or
1912 PT_CONTINUE, can not trigger a syscall trace event. */
1913 linux_nat_debug_printf
1914 ("caught syscall event with no syscall catchpoints. %d for LWP %ld, "
1915 "ignoring", syscall_number
, lp
->ptid
.lwp ());
1916 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
1919 /* The core isn't interested in this event. For efficiency, avoid
1920 stopping all threads only to have the core resume them all again.
1921 Since we're not stopping threads, if we're still syscall tracing
1922 and not stepping, we can't use PTRACE_CONT here, as we'd miss any
1923 subsequent syscall. Simply resume using the inf-ptrace layer,
1924 which knows when to use PT_SYSCALL or PT_CONTINUE. */
1926 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
1930 /* Handle a GNU/Linux extended wait response. If we see a clone
1931 event, we need to add the new LWP to our list (and not report the
1932 trap to higher layers). This function returns non-zero if the
1933 event should be ignored and we should wait again. If STOPPING is
1934 true, the new LWP remains stopped, otherwise it is continued. */
1937 linux_handle_extended_wait (struct lwp_info
*lp
, int status
)
1939 int pid
= lp
->ptid
.lwp ();
1940 struct target_waitstatus
*ourstatus
= &lp
->waitstatus
;
1941 int event
= linux_ptrace_get_extended_event (status
);
1943 /* All extended events we currently use are mid-syscall. Only
1944 PTRACE_EVENT_STOP is delivered more like a signal-stop, but
1945 you have to be using PTRACE_SEIZE to get that. */
1946 lp
->syscall_state
= TARGET_WAITKIND_SYSCALL_ENTRY
;
1948 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
1949 || event
== PTRACE_EVENT_CLONE
)
1951 unsigned long new_pid
;
1954 ptrace (PTRACE_GETEVENTMSG
, pid
, 0, &new_pid
);
1956 /* If we haven't already seen the new PID stop, wait for it now. */
1957 if (! pull_pid_from_list (&stopped_pids
, new_pid
, &status
))
1959 /* The new child has a pending SIGSTOP. We can't affect it until it
1960 hits the SIGSTOP, but we're already attached. */
1961 ret
= my_waitpid (new_pid
, &status
, __WALL
);
1963 perror_with_name (_("waiting for new child"));
1964 else if (ret
!= new_pid
)
1965 internal_error (__FILE__
, __LINE__
,
1966 _("wait returned unexpected PID %d"), ret
);
1967 else if (!WIFSTOPPED (status
))
1968 internal_error (__FILE__
, __LINE__
,
1969 _("wait returned unexpected status 0x%x"), status
);
1972 ourstatus
->value
.related_pid
= ptid_t (new_pid
, new_pid
, 0);
1974 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
)
1976 /* The arch-specific native code may need to know about new
1977 forks even if those end up never mapped to an
1979 linux_target
->low_new_fork (lp
, new_pid
);
1981 else if (event
== PTRACE_EVENT_CLONE
)
1983 linux_target
->low_new_clone (lp
, new_pid
);
1986 if (event
== PTRACE_EVENT_FORK
1987 && linux_fork_checkpointing_p (lp
->ptid
.pid ()))
1989 /* Handle checkpointing by linux-fork.c here as a special
1990 case. We don't want the follow-fork-mode or 'catch fork'
1991 to interfere with this. */
1993 /* This won't actually modify the breakpoint list, but will
1994 physically remove the breakpoints from the child. */
1995 detach_breakpoints (ptid_t (new_pid
, new_pid
, 0));
1997 /* Retain child fork in ptrace (stopped) state. */
1998 if (!find_fork_pid (new_pid
))
2001 /* Report as spurious, so that infrun doesn't want to follow
2002 this fork. We're actually doing an infcall in
2004 ourstatus
->kind
= TARGET_WAITKIND_SPURIOUS
;
2006 /* Report the stop to the core. */
2010 if (event
== PTRACE_EVENT_FORK
)
2011 ourstatus
->kind
= TARGET_WAITKIND_FORKED
;
2012 else if (event
== PTRACE_EVENT_VFORK
)
2013 ourstatus
->kind
= TARGET_WAITKIND_VFORKED
;
2014 else if (event
== PTRACE_EVENT_CLONE
)
2016 struct lwp_info
*new_lp
;
2018 ourstatus
->kind
= TARGET_WAITKIND_IGNORE
;
2020 linux_nat_debug_printf
2021 ("Got clone event from LWP %d, new child is LWP %ld", pid
, new_pid
);
2023 new_lp
= add_lwp (ptid_t (lp
->ptid
.pid (), new_pid
, 0));
2024 new_lp
->stopped
= 1;
2025 new_lp
->resumed
= 1;
2027 /* If the thread_db layer is active, let it record the user
2028 level thread id and status, and add the thread to GDB's
2030 if (!thread_db_notice_clone (lp
->ptid
, new_lp
->ptid
))
2032 /* The process is not using thread_db. Add the LWP to
2034 target_post_attach (new_lp
->ptid
.lwp ());
2035 add_thread (linux_target
, new_lp
->ptid
);
2038 /* Even if we're stopping the thread for some reason
2039 internal to this module, from the perspective of infrun
2040 and the user/frontend, this new thread is running until
2041 it next reports a stop. */
2042 set_running (linux_target
, new_lp
->ptid
, true);
2043 set_executing (linux_target
, new_lp
->ptid
, true);
2045 if (WSTOPSIG (status
) != SIGSTOP
)
2047 /* This can happen if someone starts sending signals to
2048 the new thread before it gets a chance to run, which
2049 have a lower number than SIGSTOP (e.g. SIGUSR1).
2050 This is an unlikely case, and harder to handle for
2051 fork / vfork than for clone, so we do not try - but
2052 we handle it for clone events here. */
2054 new_lp
->signalled
= 1;
2056 /* We created NEW_LP so it cannot yet contain STATUS. */
2057 gdb_assert (new_lp
->status
== 0);
2059 /* Save the wait status to report later. */
2060 linux_nat_debug_printf
2061 ("waitpid of new LWP %ld, saving status %s",
2062 (long) new_lp
->ptid
.lwp (), status_to_str (status
).c_str ());
2063 new_lp
->status
= status
;
2065 else if (report_thread_events
)
2067 new_lp
->waitstatus
.kind
= TARGET_WAITKIND_THREAD_CREATED
;
2068 new_lp
->status
= status
;
2077 if (event
== PTRACE_EVENT_EXEC
)
2079 linux_nat_debug_printf ("Got exec event from LWP %ld", lp
->ptid
.lwp ());
2081 /* Close the /proc/<pid>/mem file if it was open for this
2083 maybe_close_proc_mem_file (lp
->ptid
.pid ());
2085 ourstatus
->kind
= TARGET_WAITKIND_EXECD
;
2086 ourstatus
->value
.execd_pathname
2087 = xstrdup (linux_proc_pid_to_exec_file (pid
));
2089 /* The thread that execed must have been resumed, but, when a
2090 thread execs, it changes its tid to the tgid, and the old
2091 tgid thread might have not been resumed. */
2096 if (event
== PTRACE_EVENT_VFORK_DONE
)
2098 if (current_inferior ()->waiting_for_vfork_done
)
2100 linux_nat_debug_printf
2101 ("Got expected PTRACE_EVENT_VFORK_DONE from LWP %ld: stopping",
2104 ourstatus
->kind
= TARGET_WAITKIND_VFORK_DONE
;
2108 linux_nat_debug_printf
2109 ("Got PTRACE_EVENT_VFORK_DONE from LWP %ld: ignoring", lp
->ptid
.lwp ());
2114 internal_error (__FILE__
, __LINE__
,
2115 _("unknown ptrace event %d"), event
);
2118 /* Suspend waiting for a signal. We're mostly interested in
2124 linux_nat_debug_printf ("about to sigsuspend");
2125 sigsuspend (&suspend_mask
);
2127 /* If the quit flag is set, it means that the user pressed Ctrl-C
2128 and we're debugging a process that is running on a separate
2129 terminal, so we must forward the Ctrl-C to the inferior. (If the
2130 inferior is sharing GDB's terminal, then the Ctrl-C reaches the
2131 inferior directly.) We must do this here because functions that
2132 need to block waiting for a signal loop forever until there's an
2133 event to report before returning back to the event loop. */
2134 if (!target_terminal::is_ours ())
2136 if (check_quit_flag ())
2137 target_pass_ctrlc ();
2141 /* Wait for LP to stop. Returns the wait status, or 0 if the LWP has
2145 wait_lwp (struct lwp_info
*lp
)
2149 int thread_dead
= 0;
2152 gdb_assert (!lp
->stopped
);
2153 gdb_assert (lp
->status
== 0);
2155 /* Make sure SIGCHLD is blocked for sigsuspend avoiding a race below. */
2156 block_child_signals (&prev_mask
);
2160 pid
= my_waitpid (lp
->ptid
.lwp (), &status
, __WALL
| WNOHANG
);
2161 if (pid
== -1 && errno
== ECHILD
)
2163 /* The thread has previously exited. We need to delete it
2164 now because if this was a non-leader thread execing, we
2165 won't get an exit event. See comments on exec events at
2166 the top of the file. */
2168 linux_nat_debug_printf ("%s vanished.",
2169 target_pid_to_str (lp
->ptid
).c_str ());
2174 /* Bugs 10970, 12702.
2175 Thread group leader may have exited in which case we'll lock up in
2176 waitpid if there are other threads, even if they are all zombies too.
2177 Basically, we're not supposed to use waitpid this way.
2178 tkill(pid,0) cannot be used here as it gets ESRCH for both
2179 for zombie and running processes.
2181 As a workaround, check if we're waiting for the thread group leader and
2182 if it's a zombie, and avoid calling waitpid if it is.
2184 This is racy, what if the tgl becomes a zombie right after we check?
2185 Therefore always use WNOHANG with sigsuspend - it is equivalent to
2186 waiting waitpid but linux_proc_pid_is_zombie is safe this way. */
2188 if (lp
->ptid
.pid () == lp
->ptid
.lwp ()
2189 && linux_proc_pid_is_zombie (lp
->ptid
.lwp ()))
2192 linux_nat_debug_printf ("Thread group leader %s vanished.",
2193 target_pid_to_str (lp
->ptid
).c_str ());
2197 /* Wait for next SIGCHLD and try again. This may let SIGCHLD handlers
2198 get invoked despite our caller had them intentionally blocked by
2199 block_child_signals. This is sensitive only to the loop of
2200 linux_nat_wait_1 and there if we get called my_waitpid gets called
2201 again before it gets to sigsuspend so we can safely let the handlers
2202 get executed here. */
2206 restore_child_signals_mask (&prev_mask
);
2210 gdb_assert (pid
== lp
->ptid
.lwp ());
2212 linux_nat_debug_printf ("waitpid %s received %s",
2213 target_pid_to_str (lp
->ptid
).c_str (),
2214 status_to_str (status
).c_str ());
2216 /* Check if the thread has exited. */
2217 if (WIFEXITED (status
) || WIFSIGNALED (status
))
2219 if (report_thread_events
2220 || lp
->ptid
.pid () == lp
->ptid
.lwp ())
2222 linux_nat_debug_printf ("LWP %d exited.", lp
->ptid
.pid ());
2224 /* If this is the leader exiting, it means the whole
2225 process is gone. Store the status to report to the
2226 core. Store it in lp->waitstatus, because lp->status
2227 would be ambiguous (W_EXITCODE(0,0) == 0). */
2228 store_waitstatus (&lp
->waitstatus
, status
);
2233 linux_nat_debug_printf ("%s exited.",
2234 target_pid_to_str (lp
->ptid
).c_str ());
2244 gdb_assert (WIFSTOPPED (status
));
2247 if (lp
->must_set_ptrace_flags
)
2249 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2250 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
2252 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
2253 lp
->must_set_ptrace_flags
= 0;
2256 /* Handle GNU/Linux's syscall SIGTRAPs. */
2257 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
2259 /* No longer need the sysgood bit. The ptrace event ends up
2260 recorded in lp->waitstatus if we care for it. We can carry
2261 on handling the event like a regular SIGTRAP from here
2263 status
= W_STOPCODE (SIGTRAP
);
2264 if (linux_handle_syscall_trap (lp
, 1))
2265 return wait_lwp (lp
);
2269 /* Almost all other ptrace-stops are known to be outside of system
2270 calls, with further exceptions in linux_handle_extended_wait. */
2271 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
2274 /* Handle GNU/Linux's extended waitstatus for trace events. */
2275 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
2276 && linux_is_extended_waitstatus (status
))
2278 linux_nat_debug_printf ("Handling extended status 0x%06x", status
);
2279 linux_handle_extended_wait (lp
, status
);
2286 /* Send a SIGSTOP to LP. */
2289 stop_callback (struct lwp_info
*lp
)
2291 if (!lp
->stopped
&& !lp
->signalled
)
2295 linux_nat_debug_printf ("kill %s **<SIGSTOP>**",
2296 target_pid_to_str (lp
->ptid
).c_str ());
2299 ret
= kill_lwp (lp
->ptid
.lwp (), SIGSTOP
);
2300 linux_nat_debug_printf ("lwp kill %d %s", ret
,
2301 errno
? safe_strerror (errno
) : "ERRNO-OK");
2304 gdb_assert (lp
->status
== 0);
2310 /* Request a stop on LWP. */
2313 linux_stop_lwp (struct lwp_info
*lwp
)
2315 stop_callback (lwp
);
2318 /* See linux-nat.h */
2321 linux_stop_and_wait_all_lwps (void)
2323 /* Stop all LWP's ... */
2324 iterate_over_lwps (minus_one_ptid
, stop_callback
);
2326 /* ... and wait until all of them have reported back that
2327 they're no longer running. */
2328 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
2331 /* See linux-nat.h */
2334 linux_unstop_all_lwps (void)
2336 iterate_over_lwps (minus_one_ptid
,
2337 [] (struct lwp_info
*info
)
2339 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
2343 /* Return non-zero if LWP PID has a pending SIGINT. */
2346 linux_nat_has_pending_sigint (int pid
)
2348 sigset_t pending
, blocked
, ignored
;
2350 linux_proc_pending_signals (pid
, &pending
, &blocked
, &ignored
);
2352 if (sigismember (&pending
, SIGINT
)
2353 && !sigismember (&ignored
, SIGINT
))
2359 /* Set a flag in LP indicating that we should ignore its next SIGINT. */
2362 set_ignore_sigint (struct lwp_info
*lp
)
2364 /* If a thread has a pending SIGINT, consume it; otherwise, set a
2365 flag to consume the next one. */
2366 if (lp
->stopped
&& lp
->status
!= 0 && WIFSTOPPED (lp
->status
)
2367 && WSTOPSIG (lp
->status
) == SIGINT
)
2370 lp
->ignore_sigint
= 1;
2375 /* If LP does not have a SIGINT pending, then clear the ignore_sigint flag.
2376 This function is called after we know the LWP has stopped; if the LWP
2377 stopped before the expected SIGINT was delivered, then it will never have
2378 arrived. Also, if the signal was delivered to a shared queue and consumed
2379 by a different thread, it will never be delivered to this LWP. */
2382 maybe_clear_ignore_sigint (struct lwp_info
*lp
)
2384 if (!lp
->ignore_sigint
)
2387 if (!linux_nat_has_pending_sigint (lp
->ptid
.lwp ()))
2389 linux_nat_debug_printf ("Clearing bogus flag for %s",
2390 target_pid_to_str (lp
->ptid
).c_str ());
2391 lp
->ignore_sigint
= 0;
2395 /* Fetch the possible triggered data watchpoint info and store it in
2398 On some archs, like x86, that use debug registers to set
2399 watchpoints, it's possible that the way to know which watched
2400 address trapped, is to check the register that is used to select
2401 which address to watch. Problem is, between setting the watchpoint
2402 and reading back which data address trapped, the user may change
2403 the set of watchpoints, and, as a consequence, GDB changes the
2404 debug registers in the inferior. To avoid reading back a stale
2405 stopped-data-address when that happens, we cache in LP the fact
2406 that a watchpoint trapped, and the corresponding data address, as
2407 soon as we see LP stop with a SIGTRAP. If GDB changes the debug
2408 registers meanwhile, we have the cached data we can rely on. */
2411 check_stopped_by_watchpoint (struct lwp_info
*lp
)
2413 scoped_restore save_inferior_ptid
= make_scoped_restore (&inferior_ptid
);
2414 inferior_ptid
= lp
->ptid
;
2416 if (linux_target
->low_stopped_by_watchpoint ())
2418 lp
->stop_reason
= TARGET_STOPPED_BY_WATCHPOINT
;
2419 lp
->stopped_data_address_p
2420 = linux_target
->low_stopped_data_address (&lp
->stopped_data_address
);
2423 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2426 /* Returns true if the LWP had stopped for a watchpoint. */
2429 linux_nat_target::stopped_by_watchpoint ()
2431 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2433 gdb_assert (lp
!= NULL
);
2435 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2439 linux_nat_target::stopped_data_address (CORE_ADDR
*addr_p
)
2441 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2443 gdb_assert (lp
!= NULL
);
2445 *addr_p
= lp
->stopped_data_address
;
2447 return lp
->stopped_data_address_p
;
2450 /* Commonly any breakpoint / watchpoint generate only SIGTRAP. */
2453 linux_nat_target::low_status_is_event (int status
)
2455 return WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
;
2458 /* Wait until LP is stopped. */
2461 stop_wait_callback (struct lwp_info
*lp
)
2463 inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
2465 /* If this is a vfork parent, bail out, it is not going to report
2466 any SIGSTOP until the vfork is done with. */
2467 if (inf
->vfork_child
!= NULL
)
2474 status
= wait_lwp (lp
);
2478 if (lp
->ignore_sigint
&& WIFSTOPPED (status
)
2479 && WSTOPSIG (status
) == SIGINT
)
2481 lp
->ignore_sigint
= 0;
2484 ptrace (PTRACE_CONT
, lp
->ptid
.lwp (), 0, 0);
2486 linux_nat_debug_printf
2487 ("PTRACE_CONT %s, 0, 0 (%s) (discarding SIGINT)",
2488 target_pid_to_str (lp
->ptid
).c_str (),
2489 errno
? safe_strerror (errno
) : "OK");
2491 return stop_wait_callback (lp
);
2494 maybe_clear_ignore_sigint (lp
);
2496 if (WSTOPSIG (status
) != SIGSTOP
)
2498 /* The thread was stopped with a signal other than SIGSTOP. */
2500 linux_nat_debug_printf ("Pending event %s in %s",
2501 status_to_str ((int) status
).c_str (),
2502 target_pid_to_str (lp
->ptid
).c_str ());
2504 /* Save the sigtrap event. */
2505 lp
->status
= status
;
2506 gdb_assert (lp
->signalled
);
2507 save_stop_reason (lp
);
2511 /* We caught the SIGSTOP that we intended to catch. */
2513 linux_nat_debug_printf ("Expected SIGSTOP caught for %s.",
2514 target_pid_to_str (lp
->ptid
).c_str ());
2518 /* If we are waiting for this stop so we can report the thread
2519 stopped then we need to record this status. Otherwise, we can
2520 now discard this stop event. */
2521 if (lp
->last_resume_kind
== resume_stop
)
2523 lp
->status
= status
;
2524 save_stop_reason (lp
);
2532 /* Return non-zero if LP has a wait status pending. Discard the
2533 pending event and resume the LWP if the event that originally
2534 caused the stop became uninteresting. */
2537 status_callback (struct lwp_info
*lp
)
2539 /* Only report a pending wait status if we pretend that this has
2540 indeed been resumed. */
2544 if (!lwp_status_pending_p (lp
))
2547 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
2548 || lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2550 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2554 pc
= regcache_read_pc (regcache
);
2556 if (pc
!= lp
->stop_pc
)
2558 linux_nat_debug_printf ("PC of %s changed. was=%s, now=%s",
2559 target_pid_to_str (lp
->ptid
).c_str (),
2560 paddress (target_gdbarch (), lp
->stop_pc
),
2561 paddress (target_gdbarch (), pc
));
2565 #if !USE_SIGTRAP_SIGINFO
2566 else if (!breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2568 linux_nat_debug_printf ("previous breakpoint of %s, at %s gone",
2569 target_pid_to_str (lp
->ptid
).c_str (),
2570 paddress (target_gdbarch (), lp
->stop_pc
));
2578 linux_nat_debug_printf ("pending event of %s cancelled.",
2579 target_pid_to_str (lp
->ptid
).c_str ());
2582 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2590 /* Count the LWP's that have had events. */
2593 count_events_callback (struct lwp_info
*lp
, int *count
)
2595 gdb_assert (count
!= NULL
);
2597 /* Select only resumed LWPs that have an event pending. */
2598 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2604 /* Select the LWP (if any) that is currently being single-stepped. */
2607 select_singlestep_lwp_callback (struct lwp_info
*lp
)
2609 if (lp
->last_resume_kind
== resume_step
2616 /* Returns true if LP has a status pending. */
2619 lwp_status_pending_p (struct lwp_info
*lp
)
2621 /* We check for lp->waitstatus in addition to lp->status, because we
2622 can have pending process exits recorded in lp->status and
2623 W_EXITCODE(0,0) happens to be 0. */
2624 return lp
->status
!= 0 || lp
->waitstatus
.kind
!= TARGET_WAITKIND_IGNORE
;
2627 /* Select the Nth LWP that has had an event. */
2630 select_event_lwp_callback (struct lwp_info
*lp
, int *selector
)
2632 gdb_assert (selector
!= NULL
);
2634 /* Select only resumed LWPs that have an event pending. */
2635 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2636 if ((*selector
)-- == 0)
2642 /* Called when the LWP stopped for a signal/trap. If it stopped for a
2643 trap check what caused it (breakpoint, watchpoint, trace, etc.),
2644 and save the result in the LWP's stop_reason field. If it stopped
2645 for a breakpoint, decrement the PC if necessary on the lwp's
2649 save_stop_reason (struct lwp_info
*lp
)
2651 struct regcache
*regcache
;
2652 struct gdbarch
*gdbarch
;
2655 #if USE_SIGTRAP_SIGINFO
2659 gdb_assert (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
);
2660 gdb_assert (lp
->status
!= 0);
2662 if (!linux_target
->low_status_is_event (lp
->status
))
2665 regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2666 gdbarch
= regcache
->arch ();
2668 pc
= regcache_read_pc (regcache
);
2669 sw_bp_pc
= pc
- gdbarch_decr_pc_after_break (gdbarch
);
2671 #if USE_SIGTRAP_SIGINFO
2672 if (linux_nat_get_siginfo (lp
->ptid
, &siginfo
))
2674 if (siginfo
.si_signo
== SIGTRAP
)
2676 if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
)
2677 && GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2679 /* The si_code is ambiguous on this arch -- check debug
2681 if (!check_stopped_by_watchpoint (lp
))
2682 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2684 else if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
))
2686 /* If we determine the LWP stopped for a SW breakpoint,
2687 trust it. Particularly don't check watchpoint
2688 registers, because, at least on s390, we'd find
2689 stopped-by-watchpoint as long as there's a watchpoint
2691 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2693 else if (GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2695 /* This can indicate either a hardware breakpoint or
2696 hardware watchpoint. Check debug registers. */
2697 if (!check_stopped_by_watchpoint (lp
))
2698 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2700 else if (siginfo
.si_code
== TRAP_TRACE
)
2702 linux_nat_debug_printf ("%s stopped by trace",
2703 target_pid_to_str (lp
->ptid
).c_str ());
2705 /* We may have single stepped an instruction that
2706 triggered a watchpoint. In that case, on some
2707 architectures (such as x86), instead of TRAP_HWBKPT,
2708 si_code indicates TRAP_TRACE, and we need to check
2709 the debug registers separately. */
2710 check_stopped_by_watchpoint (lp
);
2715 if ((!lp
->step
|| lp
->stop_pc
== sw_bp_pc
)
2716 && software_breakpoint_inserted_here_p (regcache
->aspace (),
2719 /* The LWP was either continued, or stepped a software
2720 breakpoint instruction. */
2721 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2724 if (hardware_breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2725 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2727 if (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
)
2728 check_stopped_by_watchpoint (lp
);
2731 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
)
2733 linux_nat_debug_printf ("%s stopped by software breakpoint",
2734 target_pid_to_str (lp
->ptid
).c_str ());
2736 /* Back up the PC if necessary. */
2738 regcache_write_pc (regcache
, sw_bp_pc
);
2740 /* Update this so we record the correct stop PC below. */
2743 else if (lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2745 linux_nat_debug_printf ("%s stopped by hardware breakpoint",
2746 target_pid_to_str (lp
->ptid
).c_str ());
2748 else if (lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
)
2750 linux_nat_debug_printf ("%s stopped by hardware watchpoint",
2751 target_pid_to_str (lp
->ptid
).c_str ());
2758 /* Returns true if the LWP had stopped for a software breakpoint. */
2761 linux_nat_target::stopped_by_sw_breakpoint ()
2763 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2765 gdb_assert (lp
!= NULL
);
2767 return lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
;
2770 /* Implement the supports_stopped_by_sw_breakpoint method. */
2773 linux_nat_target::supports_stopped_by_sw_breakpoint ()
2775 return USE_SIGTRAP_SIGINFO
;
2778 /* Returns true if the LWP had stopped for a hardware
2779 breakpoint/watchpoint. */
2782 linux_nat_target::stopped_by_hw_breakpoint ()
2784 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2786 gdb_assert (lp
!= NULL
);
2788 return lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
;
2791 /* Implement the supports_stopped_by_hw_breakpoint method. */
2794 linux_nat_target::supports_stopped_by_hw_breakpoint ()
2796 return USE_SIGTRAP_SIGINFO
;
2799 /* Select one LWP out of those that have events pending. */
2802 select_event_lwp (ptid_t filter
, struct lwp_info
**orig_lp
, int *status
)
2805 int random_selector
;
2806 struct lwp_info
*event_lp
= NULL
;
2808 /* Record the wait status for the original LWP. */
2809 (*orig_lp
)->status
= *status
;
2811 /* In all-stop, give preference to the LWP that is being
2812 single-stepped. There will be at most one, and it will be the
2813 LWP that the core is most interested in. If we didn't do this,
2814 then we'd have to handle pending step SIGTRAPs somehow in case
2815 the core later continues the previously-stepped thread, as
2816 otherwise we'd report the pending SIGTRAP then, and the core, not
2817 having stepped the thread, wouldn't understand what the trap was
2818 for, and therefore would report it to the user as a random
2820 if (!target_is_non_stop_p ())
2822 event_lp
= iterate_over_lwps (filter
, select_singlestep_lwp_callback
);
2823 if (event_lp
!= NULL
)
2825 linux_nat_debug_printf ("Select single-step %s",
2826 target_pid_to_str (event_lp
->ptid
).c_str ());
2830 if (event_lp
== NULL
)
2832 /* Pick one at random, out of those which have had events. */
2834 /* First see how many events we have. */
2835 iterate_over_lwps (filter
,
2836 [&] (struct lwp_info
*info
)
2838 return count_events_callback (info
, &num_events
);
2840 gdb_assert (num_events
> 0);
2842 /* Now randomly pick a LWP out of those that have had
2844 random_selector
= (int)
2845 ((num_events
* (double) rand ()) / (RAND_MAX
+ 1.0));
2848 linux_nat_debug_printf ("Found %d events, selecting #%d",
2849 num_events
, random_selector
);
2852 = (iterate_over_lwps
2854 [&] (struct lwp_info
*info
)
2856 return select_event_lwp_callback (info
,
2861 if (event_lp
!= NULL
)
2863 /* Switch the event LWP. */
2864 *orig_lp
= event_lp
;
2865 *status
= event_lp
->status
;
2868 /* Flush the wait status for the event LWP. */
2869 (*orig_lp
)->status
= 0;
2872 /* Return non-zero if LP has been resumed. */
2875 resumed_callback (struct lwp_info
*lp
)
2880 /* Check if we should go on and pass this event to common code.
2882 If so, save the status to the lwp_info structure associated to LWPID. */
2885 linux_nat_filter_event (int lwpid
, int status
)
2887 struct lwp_info
*lp
;
2888 int event
= linux_ptrace_get_extended_event (status
);
2890 lp
= find_lwp_pid (ptid_t (lwpid
));
2892 /* Check for stop events reported by a process we didn't already
2893 know about - anything not already in our LWP list.
2895 If we're expecting to receive stopped processes after
2896 fork, vfork, and clone events, then we'll just add the
2897 new one to our list and go back to waiting for the event
2898 to be reported - the stopped process might be returned
2899 from waitpid before or after the event is.
2901 But note the case of a non-leader thread exec'ing after the
2902 leader having exited, and gone from our lists. The non-leader
2903 thread changes its tid to the tgid. */
2905 if (WIFSTOPPED (status
) && lp
== NULL
2906 && (WSTOPSIG (status
) == SIGTRAP
&& event
== PTRACE_EVENT_EXEC
))
2908 /* A multi-thread exec after we had seen the leader exiting. */
2909 linux_nat_debug_printf ("Re-adding thread group leader LWP %d.", lwpid
);
2911 lp
= add_lwp (ptid_t (lwpid
, lwpid
, 0));
2914 add_thread (linux_target
, lp
->ptid
);
2917 if (WIFSTOPPED (status
) && !lp
)
2919 linux_nat_debug_printf ("saving LWP %ld status %s in stopped_pids list",
2920 (long) lwpid
, status_to_str (status
).c_str ());
2921 add_to_pid_list (&stopped_pids
, lwpid
, status
);
2925 /* Make sure we don't report an event for the exit of an LWP not in
2926 our list, i.e. not part of the current process. This can happen
2927 if we detach from a program we originally forked and then it
2929 if (!WIFSTOPPED (status
) && !lp
)
2932 /* This LWP is stopped now. (And if dead, this prevents it from
2933 ever being continued.) */
2936 if (WIFSTOPPED (status
) && lp
->must_set_ptrace_flags
)
2938 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2939 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
2941 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
2942 lp
->must_set_ptrace_flags
= 0;
2945 /* Handle GNU/Linux's syscall SIGTRAPs. */
2946 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
2948 /* No longer need the sysgood bit. The ptrace event ends up
2949 recorded in lp->waitstatus if we care for it. We can carry
2950 on handling the event like a regular SIGTRAP from here
2952 status
= W_STOPCODE (SIGTRAP
);
2953 if (linux_handle_syscall_trap (lp
, 0))
2958 /* Almost all other ptrace-stops are known to be outside of system
2959 calls, with further exceptions in linux_handle_extended_wait. */
2960 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
2963 /* Handle GNU/Linux's extended waitstatus for trace events. */
2964 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
2965 && linux_is_extended_waitstatus (status
))
2967 linux_nat_debug_printf ("Handling extended status 0x%06x", status
);
2969 if (linux_handle_extended_wait (lp
, status
))
2973 /* Check if the thread has exited. */
2974 if (WIFEXITED (status
) || WIFSIGNALED (status
))
2976 if (!report_thread_events
2977 && num_lwps (lp
->ptid
.pid ()) > 1)
2979 linux_nat_debug_printf ("%s exited.",
2980 target_pid_to_str (lp
->ptid
).c_str ());
2982 /* If there is at least one more LWP, then the exit signal
2983 was not the end of the debugged application and should be
2989 /* Note that even if the leader was ptrace-stopped, it can still
2990 exit, if e.g., some other thread brings down the whole
2991 process (calls `exit'). So don't assert that the lwp is
2993 linux_nat_debug_printf ("LWP %ld exited (resumed=%d)",
2994 lp
->ptid
.lwp (), lp
->resumed
);
2996 /* Dead LWP's aren't expected to reported a pending sigstop. */
2999 /* Store the pending event in the waitstatus, because
3000 W_EXITCODE(0,0) == 0. */
3001 store_waitstatus (&lp
->waitstatus
, status
);
3005 /* Make sure we don't report a SIGSTOP that we sent ourselves in
3006 an attempt to stop an LWP. */
3008 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGSTOP
)
3012 if (lp
->last_resume_kind
== resume_stop
)
3014 linux_nat_debug_printf ("resume_stop SIGSTOP caught for %s.",
3015 target_pid_to_str (lp
->ptid
).c_str ());
3019 /* This is a delayed SIGSTOP. Filter out the event. */
3021 linux_nat_debug_printf
3022 ("%s %s, 0, 0 (discard delayed SIGSTOP)",
3023 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
3024 target_pid_to_str (lp
->ptid
).c_str ());
3026 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
3027 gdb_assert (lp
->resumed
);
3032 /* Make sure we don't report a SIGINT that we have already displayed
3033 for another thread. */
3034 if (lp
->ignore_sigint
3035 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGINT
)
3037 linux_nat_debug_printf ("Delayed SIGINT caught for %s.",
3038 target_pid_to_str (lp
->ptid
).c_str ());
3040 /* This is a delayed SIGINT. */
3041 lp
->ignore_sigint
= 0;
3043 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
3044 linux_nat_debug_printf ("%s %s, 0, 0 (discard SIGINT)",
3045 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
3046 target_pid_to_str (lp
->ptid
).c_str ());
3047 gdb_assert (lp
->resumed
);
3049 /* Discard the event. */
3053 /* Don't report signals that GDB isn't interested in, such as
3054 signals that are neither printed nor stopped upon. Stopping all
3055 threads can be a bit time-consuming, so if we want decent
3056 performance with heavily multi-threaded programs, especially when
3057 they're using a high frequency timer, we'd better avoid it if we
3059 if (WIFSTOPPED (status
))
3061 enum gdb_signal signo
= gdb_signal_from_host (WSTOPSIG (status
));
3063 if (!target_is_non_stop_p ())
3065 /* Only do the below in all-stop, as we currently use SIGSTOP
3066 to implement target_stop (see linux_nat_stop) in
3068 if (signo
== GDB_SIGNAL_INT
&& signal_pass_state (signo
) == 0)
3070 /* If ^C/BREAK is typed at the tty/console, SIGINT gets
3071 forwarded to the entire process group, that is, all LWPs
3072 will receive it - unless they're using CLONE_THREAD to
3073 share signals. Since we only want to report it once, we
3074 mark it as ignored for all LWPs except this one. */
3075 iterate_over_lwps (ptid_t (lp
->ptid
.pid ()), set_ignore_sigint
);
3076 lp
->ignore_sigint
= 0;
3079 maybe_clear_ignore_sigint (lp
);
3082 /* When using hardware single-step, we need to report every signal.
3083 Otherwise, signals in pass_mask may be short-circuited
3084 except signals that might be caused by a breakpoint, or SIGSTOP
3085 if we sent the SIGSTOP and are waiting for it to arrive. */
3087 && WSTOPSIG (status
) && sigismember (&pass_mask
, WSTOPSIG (status
))
3088 && (WSTOPSIG (status
) != SIGSTOP
3089 || !find_thread_ptid (linux_target
, lp
->ptid
)->stop_requested
)
3090 && !linux_wstatus_maybe_breakpoint (status
))
3092 linux_resume_one_lwp (lp
, lp
->step
, signo
);
3093 linux_nat_debug_printf
3094 ("%s %s, %s (preempt 'handle')",
3095 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
3096 target_pid_to_str (lp
->ptid
).c_str (),
3097 (signo
!= GDB_SIGNAL_0
3098 ? strsignal (gdb_signal_to_host (signo
)) : "0"));
3103 /* An interesting event. */
3105 lp
->status
= status
;
3106 save_stop_reason (lp
);
3109 /* Detect zombie thread group leaders, and "exit" them. We can't reap
3110 their exits until all other threads in the group have exited. */
3113 check_zombie_leaders (void)
3115 for (inferior
*inf
: all_inferiors ())
3117 struct lwp_info
*leader_lp
;
3122 leader_lp
= find_lwp_pid (ptid_t (inf
->pid
));
3123 if (leader_lp
!= NULL
3124 /* Check if there are other threads in the group, as we may
3125 have raced with the inferior simply exiting. */
3126 && num_lwps (inf
->pid
) > 1
3127 && linux_proc_pid_is_zombie (inf
->pid
))
3129 linux_nat_debug_printf ("Thread group leader %d zombie "
3130 "(it exited, or another thread execd).",
3133 /* A leader zombie can mean one of two things:
3135 - It exited, and there's an exit status pending
3136 available, or only the leader exited (not the whole
3137 program). In the latter case, we can't waitpid the
3138 leader's exit status until all other threads are gone.
3140 - There are 3 or more threads in the group, and a thread
3141 other than the leader exec'd. See comments on exec
3142 events at the top of the file. We could try
3143 distinguishing the exit and exec cases, by waiting once
3144 more, and seeing if something comes out, but it doesn't
3145 sound useful. The previous leader _does_ go away, and
3146 we'll re-add the new one once we see the exec event
3147 (which is just the same as what would happen if the
3148 previous leader did exit voluntarily before some other
3151 linux_nat_debug_printf ("Thread group leader %d vanished.", inf
->pid
);
3152 exit_lwp (leader_lp
);
3157 /* Convenience function that is called when the kernel reports an exit
3158 event. This decides whether to report the event to GDB as a
3159 process exit event, a thread exit event, or to suppress the
3163 filter_exit_event (struct lwp_info
*event_child
,
3164 struct target_waitstatus
*ourstatus
)
3166 ptid_t ptid
= event_child
->ptid
;
3168 if (num_lwps (ptid
.pid ()) > 1)
3170 if (report_thread_events
)
3171 ourstatus
->kind
= TARGET_WAITKIND_THREAD_EXITED
;
3173 ourstatus
->kind
= TARGET_WAITKIND_IGNORE
;
3175 exit_lwp (event_child
);
3182 linux_nat_wait_1 (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3183 target_wait_flags target_options
)
3186 enum resume_kind last_resume_kind
;
3187 struct lwp_info
*lp
;
3190 linux_nat_debug_printf ("enter");
3192 /* The first time we get here after starting a new inferior, we may
3193 not have added it to the LWP list yet - this is the earliest
3194 moment at which we know its PID. */
3195 if (ptid
.is_pid () && find_lwp_pid (ptid
) == nullptr)
3197 ptid_t
lwp_ptid (ptid
.pid (), ptid
.pid ());
3199 /* Upgrade the main thread's ptid. */
3200 thread_change_ptid (linux_target
, ptid
, lwp_ptid
);
3201 lp
= add_initial_lwp (lwp_ptid
);
3205 /* Make sure SIGCHLD is blocked until the sigsuspend below. */
3206 block_child_signals (&prev_mask
);
3208 /* First check if there is a LWP with a wait status pending. */
3209 lp
= iterate_over_lwps (ptid
, status_callback
);
3212 linux_nat_debug_printf ("Using pending wait status %s for %s.",
3213 status_to_str (lp
->status
).c_str (),
3214 target_pid_to_str (lp
->ptid
).c_str ());
3217 /* But if we don't find a pending event, we'll have to wait. Always
3218 pull all events out of the kernel. We'll randomly select an
3219 event LWP out of all that have events, to prevent starvation. */
3225 /* Always use -1 and WNOHANG, due to couple of a kernel/ptrace
3228 - If the thread group leader exits while other threads in the
3229 thread group still exist, waitpid(TGID, ...) hangs. That
3230 waitpid won't return an exit status until the other threads
3231 in the group are reaped.
3233 - When a non-leader thread execs, that thread just vanishes
3234 without reporting an exit (so we'd hang if we waited for it
3235 explicitly in that case). The exec event is reported to
3239 lwpid
= my_waitpid (-1, &status
, __WALL
| WNOHANG
);
3241 linux_nat_debug_printf ("waitpid(-1, ...) returned %d, %s",
3243 errno
? safe_strerror (errno
) : "ERRNO-OK");
3247 linux_nat_debug_printf ("waitpid %ld received %s",
3249 status_to_str (status
).c_str ());
3251 linux_nat_filter_event (lwpid
, status
);
3252 /* Retry until nothing comes out of waitpid. A single
3253 SIGCHLD can indicate more than one child stopped. */
3257 /* Now that we've pulled all events out of the kernel, resume
3258 LWPs that don't have an interesting event to report. */
3259 iterate_over_lwps (minus_one_ptid
,
3260 [] (struct lwp_info
*info
)
3262 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
3265 /* ... and find an LWP with a status to report to the core, if
3267 lp
= iterate_over_lwps (ptid
, status_callback
);
3271 /* Check for zombie thread group leaders. Those can't be reaped
3272 until all other threads in the thread group are. */
3273 check_zombie_leaders ();
3275 /* If there are no resumed children left, bail. We'd be stuck
3276 forever in the sigsuspend call below otherwise. */
3277 if (iterate_over_lwps (ptid
, resumed_callback
) == NULL
)
3279 linux_nat_debug_printf ("exit (no resumed LWP)");
3281 ourstatus
->kind
= TARGET_WAITKIND_NO_RESUMED
;
3283 restore_child_signals_mask (&prev_mask
);
3284 return minus_one_ptid
;
3287 /* No interesting event to report to the core. */
3289 if (target_options
& TARGET_WNOHANG
)
3291 linux_nat_debug_printf ("exit (ignore)");
3293 ourstatus
->kind
= TARGET_WAITKIND_IGNORE
;
3294 restore_child_signals_mask (&prev_mask
);
3295 return minus_one_ptid
;
3298 /* We shouldn't end up here unless we want to try again. */
3299 gdb_assert (lp
== NULL
);
3301 /* Block until we get an event reported with SIGCHLD. */
3307 status
= lp
->status
;
3310 if (!target_is_non_stop_p ())
3312 /* Now stop all other LWP's ... */
3313 iterate_over_lwps (minus_one_ptid
, stop_callback
);
3315 /* ... and wait until all of them have reported back that
3316 they're no longer running. */
3317 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
3320 /* If we're not waiting for a specific LWP, choose an event LWP from
3321 among those that have had events. Giving equal priority to all
3322 LWPs that have had events helps prevent starvation. */
3323 if (ptid
== minus_one_ptid
|| ptid
.is_pid ())
3324 select_event_lwp (ptid
, &lp
, &status
);
3326 gdb_assert (lp
!= NULL
);
3328 /* Now that we've selected our final event LWP, un-adjust its PC if
3329 it was a software breakpoint, and we can't reliably support the
3330 "stopped by software breakpoint" stop reason. */
3331 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
3332 && !USE_SIGTRAP_SIGINFO
)
3334 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3335 struct gdbarch
*gdbarch
= regcache
->arch ();
3336 int decr_pc
= gdbarch_decr_pc_after_break (gdbarch
);
3342 pc
= regcache_read_pc (regcache
);
3343 regcache_write_pc (regcache
, pc
+ decr_pc
);
3347 /* We'll need this to determine whether to report a SIGSTOP as
3348 GDB_SIGNAL_0. Need to take a copy because resume_clear_callback
3350 last_resume_kind
= lp
->last_resume_kind
;
3352 if (!target_is_non_stop_p ())
3354 /* In all-stop, from the core's perspective, all LWPs are now
3355 stopped until a new resume action is sent over. */
3356 iterate_over_lwps (minus_one_ptid
, resume_clear_callback
);
3360 resume_clear_callback (lp
);
3363 if (linux_target
->low_status_is_event (status
))
3365 linux_nat_debug_printf ("trap ptid is %s.",
3366 target_pid_to_str (lp
->ptid
).c_str ());
3369 if (lp
->waitstatus
.kind
!= TARGET_WAITKIND_IGNORE
)
3371 *ourstatus
= lp
->waitstatus
;
3372 lp
->waitstatus
.kind
= TARGET_WAITKIND_IGNORE
;
3375 store_waitstatus (ourstatus
, status
);
3377 linux_nat_debug_printf ("exit");
3379 restore_child_signals_mask (&prev_mask
);
3381 if (last_resume_kind
== resume_stop
3382 && ourstatus
->kind
== TARGET_WAITKIND_STOPPED
3383 && WSTOPSIG (status
) == SIGSTOP
)
3385 /* A thread that has been requested to stop by GDB with
3386 target_stop, and it stopped cleanly, so report as SIG0. The
3387 use of SIGSTOP is an implementation detail. */
3388 ourstatus
->value
.sig
= GDB_SIGNAL_0
;
3391 if (ourstatus
->kind
== TARGET_WAITKIND_EXITED
3392 || ourstatus
->kind
== TARGET_WAITKIND_SIGNALLED
)
3395 lp
->core
= linux_common_core_of_thread (lp
->ptid
);
3397 if (ourstatus
->kind
== TARGET_WAITKIND_EXITED
)
3398 return filter_exit_event (lp
, ourstatus
);
3403 /* Resume LWPs that are currently stopped without any pending status
3404 to report, but are resumed from the core's perspective. */
3407 resume_stopped_resumed_lwps (struct lwp_info
*lp
, const ptid_t wait_ptid
)
3411 linux_nat_debug_printf ("NOT resuming LWP %s, not stopped",
3412 target_pid_to_str (lp
->ptid
).c_str ());
3414 else if (!lp
->resumed
)
3416 linux_nat_debug_printf ("NOT resuming LWP %s, not resumed",
3417 target_pid_to_str (lp
->ptid
).c_str ());
3419 else if (lwp_status_pending_p (lp
))
3421 linux_nat_debug_printf ("NOT resuming LWP %s, has pending status",
3422 target_pid_to_str (lp
->ptid
).c_str ());
3426 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3427 struct gdbarch
*gdbarch
= regcache
->arch ();
3431 CORE_ADDR pc
= regcache_read_pc (regcache
);
3432 int leave_stopped
= 0;
3434 /* Don't bother if there's a breakpoint at PC that we'd hit
3435 immediately, and we're not waiting for this LWP. */
3436 if (!lp
->ptid
.matches (wait_ptid
))
3438 if (breakpoint_inserted_here_p (regcache
->aspace (), pc
))
3444 linux_nat_debug_printf
3445 ("resuming stopped-resumed LWP %s at %s: step=%d",
3446 target_pid_to_str (lp
->ptid
).c_str (), paddress (gdbarch
, pc
),
3449 linux_resume_one_lwp_throw (lp
, lp
->step
, GDB_SIGNAL_0
);
3452 catch (const gdb_exception_error
&ex
)
3454 if (!check_ptrace_stopped_lwp_gone (lp
))
3463 linux_nat_target::wait (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3464 target_wait_flags target_options
)
3468 linux_nat_debug_printf ("[%s], [%s]", target_pid_to_str (ptid
).c_str (),
3469 target_options_to_string (target_options
).c_str ());
3471 /* Flush the async file first. */
3472 if (target_is_async_p ())
3473 async_file_flush ();
3475 /* Resume LWPs that are currently stopped without any pending status
3476 to report, but are resumed from the core's perspective. LWPs get
3477 in this state if we find them stopping at a time we're not
3478 interested in reporting the event (target_wait on a
3479 specific_process, for example, see linux_nat_wait_1), and
3480 meanwhile the event became uninteresting. Don't bother resuming
3481 LWPs we're not going to wait for if they'd stop immediately. */
3482 if (target_is_non_stop_p ())
3483 iterate_over_lwps (minus_one_ptid
,
3484 [=] (struct lwp_info
*info
)
3486 return resume_stopped_resumed_lwps (info
, ptid
);
3489 event_ptid
= linux_nat_wait_1 (ptid
, ourstatus
, target_options
);
3491 /* If we requested any event, and something came out, assume there
3492 may be more. If we requested a specific lwp or process, also
3493 assume there may be more. */
3494 if (target_is_async_p ()
3495 && ((ourstatus
->kind
!= TARGET_WAITKIND_IGNORE
3496 && ourstatus
->kind
!= TARGET_WAITKIND_NO_RESUMED
)
3497 || ptid
!= minus_one_ptid
))
3506 kill_one_lwp (pid_t pid
)
3508 /* PTRACE_KILL may resume the inferior. Send SIGKILL first. */
3511 kill_lwp (pid
, SIGKILL
);
3513 if (debug_linux_nat
)
3515 int save_errno
= errno
;
3517 linux_nat_debug_printf
3518 ("kill (SIGKILL) %ld, 0, 0 (%s)", (long) pid
,
3519 save_errno
!= 0 ? safe_strerror (save_errno
) : "OK");
3522 /* Some kernels ignore even SIGKILL for processes under ptrace. */
3525 ptrace (PTRACE_KILL
, pid
, 0, 0);
3526 if (debug_linux_nat
)
3528 int save_errno
= errno
;
3530 linux_nat_debug_printf
3531 ("PTRACE_KILL %ld, 0, 0 (%s)", (long) pid
,
3532 save_errno
? safe_strerror (save_errno
) : "OK");
3536 /* Wait for an LWP to die. */
3539 kill_wait_one_lwp (pid_t pid
)
3543 /* We must make sure that there are no pending events (delayed
3544 SIGSTOPs, pending SIGTRAPs, etc.) to make sure the current
3545 program doesn't interfere with any following debugging session. */
3549 res
= my_waitpid (pid
, NULL
, __WALL
);
3550 if (res
!= (pid_t
) -1)
3552 linux_nat_debug_printf ("wait %ld received unknown.", (long) pid
);
3554 /* The Linux kernel sometimes fails to kill a thread
3555 completely after PTRACE_KILL; that goes from the stop
3556 point in do_fork out to the one in get_signal_to_deliver
3557 and waits again. So kill it again. */
3563 gdb_assert (res
== -1 && errno
== ECHILD
);
3566 /* Callback for iterate_over_lwps. */
3569 kill_callback (struct lwp_info
*lp
)
3571 kill_one_lwp (lp
->ptid
.lwp ());
3575 /* Callback for iterate_over_lwps. */
3578 kill_wait_callback (struct lwp_info
*lp
)
3580 kill_wait_one_lwp (lp
->ptid
.lwp ());
3584 /* Kill the fork children of any threads of inferior INF that are
3585 stopped at a fork event. */
3588 kill_unfollowed_fork_children (struct inferior
*inf
)
3590 for (thread_info
*thread
: inf
->non_exited_threads ())
3592 struct target_waitstatus
*ws
= &thread
->pending_follow
;
3594 if (ws
->kind
== TARGET_WAITKIND_FORKED
3595 || ws
->kind
== TARGET_WAITKIND_VFORKED
)
3597 ptid_t child_ptid
= ws
->value
.related_pid
;
3598 int child_pid
= child_ptid
.pid ();
3599 int child_lwp
= child_ptid
.lwp ();
3601 kill_one_lwp (child_lwp
);
3602 kill_wait_one_lwp (child_lwp
);
3604 /* Let the arch-specific native code know this process is
3606 linux_target
->low_forget_process (child_pid
);
3612 linux_nat_target::kill ()
3614 /* If we're stopped while forking and we haven't followed yet,
3615 kill the other task. We need to do this first because the
3616 parent will be sleeping if this is a vfork. */
3617 kill_unfollowed_fork_children (current_inferior ());
3619 if (forks_exist_p ())
3620 linux_fork_killall ();
3623 ptid_t ptid
= ptid_t (inferior_ptid
.pid ());
3625 /* Stop all threads before killing them, since ptrace requires
3626 that the thread is stopped to successfully PTRACE_KILL. */
3627 iterate_over_lwps (ptid
, stop_callback
);
3628 /* ... and wait until all of them have reported back that
3629 they're no longer running. */
3630 iterate_over_lwps (ptid
, stop_wait_callback
);
3632 /* Kill all LWP's ... */
3633 iterate_over_lwps (ptid
, kill_callback
);
3635 /* ... and wait until we've flushed all events. */
3636 iterate_over_lwps (ptid
, kill_wait_callback
);
3639 target_mourn_inferior (inferior_ptid
);
3643 linux_nat_target::mourn_inferior ()
3645 int pid
= inferior_ptid
.pid ();
3647 purge_lwp_list (pid
);
3649 /* Close the /proc/<pid>/mem file if it was open for this
3651 maybe_close_proc_mem_file (pid
);
3653 if (! forks_exist_p ())
3654 /* Normal case, no other forks available. */
3655 inf_ptrace_target::mourn_inferior ();
3657 /* Multi-fork case. The current inferior_ptid has exited, but
3658 there are other viable forks to debug. Delete the exiting
3659 one and context-switch to the first available. */
3660 linux_fork_mourn_inferior ();
3662 /* Let the arch-specific native code know this process is gone. */
3663 linux_target
->low_forget_process (pid
);
3666 /* Convert a native/host siginfo object, into/from the siginfo in the
3667 layout of the inferiors' architecture. */
3670 siginfo_fixup (siginfo_t
*siginfo
, gdb_byte
*inf_siginfo
, int direction
)
3672 /* If the low target didn't do anything, then just do a straight
3674 if (!linux_target
->low_siginfo_fixup (siginfo
, inf_siginfo
, direction
))
3677 memcpy (siginfo
, inf_siginfo
, sizeof (siginfo_t
));
3679 memcpy (inf_siginfo
, siginfo
, sizeof (siginfo_t
));
3683 static enum target_xfer_status
3684 linux_xfer_siginfo (enum target_object object
,
3685 const char *annex
, gdb_byte
*readbuf
,
3686 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3687 ULONGEST
*xfered_len
)
3691 gdb_byte inf_siginfo
[sizeof (siginfo_t
)];
3693 gdb_assert (object
== TARGET_OBJECT_SIGNAL_INFO
);
3694 gdb_assert (readbuf
|| writebuf
);
3696 pid
= inferior_ptid
.lwp ();
3698 pid
= inferior_ptid
.pid ();
3700 if (offset
> sizeof (siginfo
))
3701 return TARGET_XFER_E_IO
;
3704 ptrace (PTRACE_GETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, &siginfo
);
3706 return TARGET_XFER_E_IO
;
3708 /* When GDB is built as a 64-bit application, ptrace writes into
3709 SIGINFO an object with 64-bit layout. Since debugging a 32-bit
3710 inferior with a 64-bit GDB should look the same as debugging it
3711 with a 32-bit GDB, we need to convert it. GDB core always sees
3712 the converted layout, so any read/write will have to be done
3714 siginfo_fixup (&siginfo
, inf_siginfo
, 0);
3716 if (offset
+ len
> sizeof (siginfo
))
3717 len
= sizeof (siginfo
) - offset
;
3719 if (readbuf
!= NULL
)
3720 memcpy (readbuf
, inf_siginfo
+ offset
, len
);
3723 memcpy (inf_siginfo
+ offset
, writebuf
, len
);
3725 /* Convert back to ptrace layout before flushing it out. */
3726 siginfo_fixup (&siginfo
, inf_siginfo
, 1);
3729 ptrace (PTRACE_SETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, &siginfo
);
3731 return TARGET_XFER_E_IO
;
3735 return TARGET_XFER_OK
;
3738 static enum target_xfer_status
3739 linux_nat_xfer_osdata (enum target_object object
,
3740 const char *annex
, gdb_byte
*readbuf
,
3741 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3742 ULONGEST
*xfered_len
);
3744 static enum target_xfer_status
3745 linux_proc_xfer_memory_partial (gdb_byte
*readbuf
, const gdb_byte
*writebuf
,
3746 ULONGEST offset
, LONGEST len
, ULONGEST
*xfered_len
);
3748 enum target_xfer_status
3749 linux_nat_target::xfer_partial (enum target_object object
,
3750 const char *annex
, gdb_byte
*readbuf
,
3751 const gdb_byte
*writebuf
,
3752 ULONGEST offset
, ULONGEST len
, ULONGEST
*xfered_len
)
3754 if (object
== TARGET_OBJECT_SIGNAL_INFO
)
3755 return linux_xfer_siginfo (object
, annex
, readbuf
, writebuf
,
3756 offset
, len
, xfered_len
);
3758 /* The target is connected but no live inferior is selected. Pass
3759 this request down to a lower stratum (e.g., the executable
3761 if (object
== TARGET_OBJECT_MEMORY
&& inferior_ptid
== null_ptid
)
3762 return TARGET_XFER_EOF
;
3764 if (object
== TARGET_OBJECT_AUXV
)
3765 return memory_xfer_auxv (this, object
, annex
, readbuf
, writebuf
,
3766 offset
, len
, xfered_len
);
3768 if (object
== TARGET_OBJECT_OSDATA
)
3769 return linux_nat_xfer_osdata (object
, annex
, readbuf
, writebuf
,
3770 offset
, len
, xfered_len
);
3772 if (object
== TARGET_OBJECT_MEMORY
)
3774 /* GDB calculates all addresses in the largest possible address
3775 width. The address width must be masked before its final use
3776 by linux_proc_xfer_partial.
3778 Compare ADDR_BIT first to avoid a compiler warning on shift overflow. */
3779 int addr_bit
= gdbarch_addr_bit (target_gdbarch ());
3781 if (addr_bit
< (sizeof (ULONGEST
) * HOST_CHAR_BIT
))
3782 offset
&= ((ULONGEST
) 1 << addr_bit
) - 1;
3784 return linux_proc_xfer_memory_partial (readbuf
, writebuf
,
3785 offset
, len
, xfered_len
);
3788 return inf_ptrace_target::xfer_partial (object
, annex
, readbuf
, writebuf
,
3789 offset
, len
, xfered_len
);
3793 linux_nat_target::thread_alive (ptid_t ptid
)
3795 /* As long as a PTID is in lwp list, consider it alive. */
3796 return find_lwp_pid (ptid
) != NULL
;
3799 /* Implement the to_update_thread_list target method for this
3803 linux_nat_target::update_thread_list ()
3805 struct lwp_info
*lwp
;
3807 /* We add/delete threads from the list as clone/exit events are
3808 processed, so just try deleting exited threads still in the
3810 delete_exited_threads ();
3812 /* Update the processor core that each lwp/thread was last seen
3816 /* Avoid accessing /proc if the thread hasn't run since we last
3817 time we fetched the thread's core. Accessing /proc becomes
3818 noticeably expensive when we have thousands of LWPs. */
3819 if (lwp
->core
== -1)
3820 lwp
->core
= linux_common_core_of_thread (lwp
->ptid
);
3825 linux_nat_target::pid_to_str (ptid_t ptid
)
3828 && (ptid
.pid () != ptid
.lwp ()
3829 || num_lwps (ptid
.pid ()) > 1))
3830 return string_printf ("LWP %ld", ptid
.lwp ());
3832 return normal_pid_to_str (ptid
);
3836 linux_nat_target::thread_name (struct thread_info
*thr
)
3838 return linux_proc_tid_get_name (thr
->ptid
);
3841 /* Accepts an integer PID; Returns a string representing a file that
3842 can be opened to get the symbols for the child process. */
3845 linux_nat_target::pid_to_exec_file (int pid
)
3847 return linux_proc_pid_to_exec_file (pid
);
3850 /* Keep the /proc/<pid>/mem file open between memory accesses, as a
3851 cache to avoid constantly closing/opening the file in the common
3852 case of multiple memory reads/writes from/to the same inferior.
3853 Note we don't keep a file open per inferior to avoid keeping too
3854 many file descriptors open, which can run into resource limits. */
3857 /* The LWP this open file is for. Note that after opening the file,
3858 even if the thread subsequently exits, the open file is still
3859 usable for accessing memory. It's only when the whole process
3860 exits or execs that the file becomes invalid (at which point
3861 reads/writes return EOF). */
3864 /* The file descriptor. -1 if file is not open. */
3867 /* Close FD and clear it to -1. */
3870 linux_nat_debug_printf ("closing fd %d for /proc/%d/task/%ld/mem\n",
3871 fd
, ptid
.pid (), ptid
.lwp ());
3875 } last_proc_mem_file
;
3877 /* Close the /proc/<pid>/mem file if its LWP matches PTID. */
3880 maybe_close_proc_mem_file (pid_t pid
)
3882 if (last_proc_mem_file
.ptid
.pid () == pid
)
3883 last_proc_mem_file
.close ();
3886 /* Helper for linux_proc_xfer_memory_partial. Accesses /proc via
3887 PTID. Returns -1 on error, with errno set. Returns number of
3888 read/written bytes otherwise. Returns 0 on EOF, which indicates
3889 the address space is gone (because the process exited or
3893 linux_proc_xfer_memory_partial_pid (ptid_t ptid
,
3894 gdb_byte
*readbuf
, const gdb_byte
*writebuf
,
3895 ULONGEST offset
, LONGEST len
)
3899 /* As long as we're hitting the same inferior, the previously open
3900 file is good, even if the thread it was open for exits. */
3901 if (last_proc_mem_file
.fd
!= -1
3902 && last_proc_mem_file
.ptid
.pid () != ptid
.pid ())
3903 last_proc_mem_file
.close ();
3905 if (last_proc_mem_file
.fd
== -1)
3907 /* Actually use /proc/<pid>/task/<lwp>/mem instead of
3908 /proc/<lwp>/mem to avoid PID-reuse races, as we may be trying
3909 to read memory via a thread which we've already reaped.
3910 /proc/<lwp>/mem could open a file for the wrong process. If
3911 the LWPID is reused for the same process it's OK, we can read
3912 memory through it just fine. If the LWPID is reused for a
3913 different process, then the open will fail because the path
3916 xsnprintf (filename
, sizeof filename
,
3917 "/proc/%d/task/%ld/mem", ptid
.pid (), ptid
.lwp ());
3919 last_proc_mem_file
.fd
3920 = gdb_open_cloexec (filename
, O_RDWR
| O_LARGEFILE
, 0);
3922 if (last_proc_mem_file
.fd
== -1)
3924 linux_nat_debug_printf ("opening %s failed: %s (%d)\n",
3925 filename
, safe_strerror (errno
), errno
);
3928 last_proc_mem_file
.ptid
= ptid
;
3930 linux_nat_debug_printf ("opened fd %d for %s\n",
3931 last_proc_mem_file
.fd
, filename
);
3934 int fd
= last_proc_mem_file
.fd
;
3936 /* Use pread64/pwrite64 if available, since they save a syscall and can
3937 handle 64-bit offsets even on 32-bit platforms (for instance, SPARC
3938 debugging a SPARC64 application). */
3940 ret
= (readbuf
? pread64 (fd
, readbuf
, len
, offset
)
3941 : pwrite64 (fd
, writebuf
, len
, offset
));
3943 ret
= lseek (fd
, offset
, SEEK_SET
);
3945 ret
= (readbuf
? read (fd
, readbuf
, len
)
3946 : write (fd
, writebuf
, len
));
3951 linux_nat_debug_printf ("accessing fd %d for pid %ld failed: %s (%d)\n",
3953 safe_strerror (errno
), errno
);
3957 linux_nat_debug_printf ("accessing fd %d for pid %ld got EOF\n",
3964 /* Implement the to_xfer_partial target method using /proc/<pid>/mem.
3965 Because we can use a single read/write call, this can be much more
3966 efficient than banging away at PTRACE_PEEKTEXT. Also, unlike
3967 PTRACE_PEEKTEXT/PTRACE_POKETEXT, this works with running
3970 static enum target_xfer_status
3971 linux_proc_xfer_memory_partial (gdb_byte
*readbuf
, const gdb_byte
*writebuf
,
3972 ULONGEST offset
, LONGEST len
,
3973 ULONGEST
*xfered_len
)
3975 /* Unlike PTRACE_PEEKTEXT/PTRACE_POKETEXT, reading/writing from/to
3976 /proc/<pid>/mem works with running threads, and even exited
3977 threads if the file was already open. If we need to open or
3978 reopen the /proc file though, we may get an EACCES error
3979 ("Permission denied"), meaning the thread is gone but its exit
3980 status isn't reaped yet, or ENOENT if the thread is gone and
3981 already reaped. In that case, just try opening the file for
3982 another thread in the process. If all threads fail, then it must
3983 mean the whole process exited, in which case there's nothing else
3984 to do and we just fail the memory access.
3986 Note we don't simply always access via the leader thread because
3987 the leader may exit without exiting the whole process. See
3988 gdb.threads/leader-exit.exp, for example. */
3990 /* It's frequently the case that the selected thread is stopped, and
3991 is thus not likely to exit (unless something kills the process
3992 outside our control, with e.g., SIGKILL). Give that one a try
3995 Also, inferior_ptid may actually point at an LWP not in lwp_list.
3996 This happens when we're detaching from a fork child that we don't
3997 want to debug ("set detach-on-fork on"), and the breakpoints
3998 module uninstalls breakpoints from the fork child. Which process
3999 to access is given by inferior_ptid. */
4000 int res
= linux_proc_xfer_memory_partial_pid (inferior_ptid
,
4005 /* EOF means the address space is gone, the whole
4006 process exited or execed. */
4007 return TARGET_XFER_EOF
;
4012 return TARGET_XFER_OK
;
4016 /* If we simply raced with the thread exiting (EACCES), or the
4017 current thread is THREAD_EXITED (ENOENT), try some other
4018 thread. It's easier to handle an ENOENT failure than check
4019 for THREAD_EXIT upfront because this function is called
4020 before a thread for inferior_ptid is added to the thread
4022 if (errno
!= EACCES
&& errno
!= ENOENT
)
4023 return TARGET_XFER_EOF
;
4026 int cur_pid
= current_inferior ()->pid
;
4028 if (inferior_ptid
.pid () != cur_pid
)
4030 /* We're accessing a fork child, and the access above failed.
4031 Don't bother iterating the LWP list, since there's no other
4032 LWP for this process. */
4033 return TARGET_XFER_EOF
;
4036 /* Iterate over LWPs of the current inferior, trying to access
4037 memory through one of them. */
4038 for (lwp_info
*lp
= lwp_list
; lp
!= nullptr; lp
= lp
->next
)
4040 if (lp
->ptid
.pid () != cur_pid
)
4043 res
= linux_proc_xfer_memory_partial_pid (lp
->ptid
,
4049 /* EOF means the address space is gone, the whole process
4050 exited or execed. */
4051 return TARGET_XFER_EOF
;
4055 if (errno
== EACCES
)
4057 /* This LWP is gone, try another one. */
4061 return TARGET_XFER_EOF
;
4065 return TARGET_XFER_OK
;
4069 return TARGET_XFER_EOF
;
4072 /* Parse LINE as a signal set and add its set bits to SIGS. */
4075 add_line_to_sigset (const char *line
, sigset_t
*sigs
)
4077 int len
= strlen (line
) - 1;
4081 if (line
[len
] != '\n')
4082 error (_("Could not parse signal set: %s"), line
);
4090 if (*p
>= '0' && *p
<= '9')
4092 else if (*p
>= 'a' && *p
<= 'f')
4093 digit
= *p
- 'a' + 10;
4095 error (_("Could not parse signal set: %s"), line
);
4100 sigaddset (sigs
, signum
+ 1);
4102 sigaddset (sigs
, signum
+ 2);
4104 sigaddset (sigs
, signum
+ 3);
4106 sigaddset (sigs
, signum
+ 4);
4112 /* Find process PID's pending signals from /proc/pid/status and set
4116 linux_proc_pending_signals (int pid
, sigset_t
*pending
,
4117 sigset_t
*blocked
, sigset_t
*ignored
)
4119 char buffer
[PATH_MAX
], fname
[PATH_MAX
];
4121 sigemptyset (pending
);
4122 sigemptyset (blocked
);
4123 sigemptyset (ignored
);
4124 xsnprintf (fname
, sizeof fname
, "/proc/%d/status", pid
);
4125 gdb_file_up procfile
= gdb_fopen_cloexec (fname
, "r");
4126 if (procfile
== NULL
)
4127 error (_("Could not open %s"), fname
);
4129 while (fgets (buffer
, PATH_MAX
, procfile
.get ()) != NULL
)
4131 /* Normal queued signals are on the SigPnd line in the status
4132 file. However, 2.6 kernels also have a "shared" pending
4133 queue for delivering signals to a thread group, so check for
4136 Unfortunately some Red Hat kernels include the shared pending
4137 queue but not the ShdPnd status field. */
4139 if (startswith (buffer
, "SigPnd:\t"))
4140 add_line_to_sigset (buffer
+ 8, pending
);
4141 else if (startswith (buffer
, "ShdPnd:\t"))
4142 add_line_to_sigset (buffer
+ 8, pending
);
4143 else if (startswith (buffer
, "SigBlk:\t"))
4144 add_line_to_sigset (buffer
+ 8, blocked
);
4145 else if (startswith (buffer
, "SigIgn:\t"))
4146 add_line_to_sigset (buffer
+ 8, ignored
);
4150 static enum target_xfer_status
4151 linux_nat_xfer_osdata (enum target_object object
,
4152 const char *annex
, gdb_byte
*readbuf
,
4153 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
4154 ULONGEST
*xfered_len
)
4156 gdb_assert (object
== TARGET_OBJECT_OSDATA
);
4158 *xfered_len
= linux_common_xfer_osdata (annex
, readbuf
, offset
, len
);
4159 if (*xfered_len
== 0)
4160 return TARGET_XFER_EOF
;
4162 return TARGET_XFER_OK
;
4165 std::vector
<static_tracepoint_marker
>
4166 linux_nat_target::static_tracepoint_markers_by_strid (const char *strid
)
4168 char s
[IPA_CMD_BUF_SIZE
];
4169 int pid
= inferior_ptid
.pid ();
4170 std::vector
<static_tracepoint_marker
> markers
;
4172 ptid_t ptid
= ptid_t (pid
, 0, 0);
4173 static_tracepoint_marker marker
;
4178 memcpy (s
, "qTfSTM", sizeof ("qTfSTM"));
4179 s
[sizeof ("qTfSTM")] = 0;
4181 agent_run_command (pid
, s
, strlen (s
) + 1);
4184 SCOPE_EXIT
{ target_continue_no_signal (ptid
); };
4190 parse_static_tracepoint_marker_definition (p
, &p
, &marker
);
4192 if (strid
== NULL
|| marker
.str_id
== strid
)
4193 markers
.push_back (std::move (marker
));
4195 while (*p
++ == ','); /* comma-separated list */
4197 memcpy (s
, "qTsSTM", sizeof ("qTsSTM"));
4198 s
[sizeof ("qTsSTM")] = 0;
4199 agent_run_command (pid
, s
, strlen (s
) + 1);
4206 /* target_is_async_p implementation. */
4209 linux_nat_target::is_async_p ()
4211 return linux_is_async_p ();
4214 /* target_can_async_p implementation. */
4217 linux_nat_target::can_async_p ()
4219 /* We're always async, unless the user explicitly prevented it with the
4220 "maint set target-async" command. */
4221 return target_async_permitted
;
4225 linux_nat_target::supports_non_stop ()
4230 /* to_always_non_stop_p implementation. */
4233 linux_nat_target::always_non_stop_p ()
4239 linux_nat_target::supports_multi_process ()
4245 linux_nat_target::supports_disable_randomization ()
4250 /* SIGCHLD handler that serves two purposes: In non-stop/async mode,
4251 so we notice when any child changes state, and notify the
4252 event-loop; it allows us to use sigsuspend in linux_nat_wait_1
4253 above to wait for the arrival of a SIGCHLD. */
4256 sigchld_handler (int signo
)
4258 int old_errno
= errno
;
4260 if (debug_linux_nat
)
4261 gdb_stdlog
->write_async_safe ("sigchld\n", sizeof ("sigchld\n") - 1);
4263 if (signo
== SIGCHLD
4264 && linux_nat_event_pipe
[0] != -1)
4265 async_file_mark (); /* Let the event loop know that there are
4266 events to handle. */
4271 /* Callback registered with the target events file descriptor. */
4274 handle_target_event (int error
, gdb_client_data client_data
)
4276 inferior_event_handler (INF_REG_EVENT
);
4279 /* Create/destroy the target events pipe. Returns previous state. */
4282 linux_async_pipe (int enable
)
4284 int previous
= linux_is_async_p ();
4286 if (previous
!= enable
)
4290 /* Block child signals while we create/destroy the pipe, as
4291 their handler writes to it. */
4292 block_child_signals (&prev_mask
);
4296 if (gdb_pipe_cloexec (linux_nat_event_pipe
) == -1)
4297 internal_error (__FILE__
, __LINE__
,
4298 "creating event pipe failed.");
4300 fcntl (linux_nat_event_pipe
[0], F_SETFL
, O_NONBLOCK
);
4301 fcntl (linux_nat_event_pipe
[1], F_SETFL
, O_NONBLOCK
);
4305 close (linux_nat_event_pipe
[0]);
4306 close (linux_nat_event_pipe
[1]);
4307 linux_nat_event_pipe
[0] = -1;
4308 linux_nat_event_pipe
[1] = -1;
4311 restore_child_signals_mask (&prev_mask
);
4318 linux_nat_target::async_wait_fd ()
4320 return linux_nat_event_pipe
[0];
4323 /* target_async implementation. */
4326 linux_nat_target::async (int enable
)
4330 if (!linux_async_pipe (1))
4332 add_file_handler (linux_nat_event_pipe
[0],
4333 handle_target_event
, NULL
,
4335 /* There may be pending events to handle. Tell the event loop
4342 delete_file_handler (linux_nat_event_pipe
[0]);
4343 linux_async_pipe (0);
4348 /* Stop an LWP, and push a GDB_SIGNAL_0 stop status if no other
4352 linux_nat_stop_lwp (struct lwp_info
*lwp
)
4356 linux_nat_debug_printf ("running -> suspending %s",
4357 target_pid_to_str (lwp
->ptid
).c_str ());
4360 if (lwp
->last_resume_kind
== resume_stop
)
4362 linux_nat_debug_printf ("already stopping LWP %ld at GDB's request",
4367 stop_callback (lwp
);
4368 lwp
->last_resume_kind
= resume_stop
;
4372 /* Already known to be stopped; do nothing. */
4374 if (debug_linux_nat
)
4376 if (find_thread_ptid (linux_target
, lwp
->ptid
)->stop_requested
)
4377 linux_nat_debug_printf ("already stopped/stop_requested %s",
4378 target_pid_to_str (lwp
->ptid
).c_str ());
4380 linux_nat_debug_printf ("already stopped/no stop_requested yet %s",
4381 target_pid_to_str (lwp
->ptid
).c_str ());
4388 linux_nat_target::stop (ptid_t ptid
)
4390 iterate_over_lwps (ptid
, linux_nat_stop_lwp
);
4394 linux_nat_target::close ()
4396 /* Unregister from the event loop. */
4400 inf_ptrace_target::close ();
4403 /* When requests are passed down from the linux-nat layer to the
4404 single threaded inf-ptrace layer, ptids of (lwpid,0,0) form are
4405 used. The address space pointer is stored in the inferior object,
4406 but the common code that is passed such ptid can't tell whether
4407 lwpid is a "main" process id or not (it assumes so). We reverse
4408 look up the "main" process id from the lwp here. */
4410 struct address_space
*
4411 linux_nat_target::thread_address_space (ptid_t ptid
)
4413 struct lwp_info
*lwp
;
4414 struct inferior
*inf
;
4417 if (ptid
.lwp () == 0)
4419 /* An (lwpid,0,0) ptid. Look up the lwp object to get at the
4421 lwp
= find_lwp_pid (ptid
);
4422 pid
= lwp
->ptid
.pid ();
4426 /* A (pid,lwpid,0) ptid. */
4430 inf
= find_inferior_pid (this, pid
);
4431 gdb_assert (inf
!= NULL
);
4435 /* Return the cached value of the processor core for thread PTID. */
4438 linux_nat_target::core_of_thread (ptid_t ptid
)
4440 struct lwp_info
*info
= find_lwp_pid (ptid
);
4447 /* Implementation of to_filesystem_is_local. */
4450 linux_nat_target::filesystem_is_local ()
4452 struct inferior
*inf
= current_inferior ();
4454 if (inf
->fake_pid_p
|| inf
->pid
== 0)
4457 return linux_ns_same (inf
->pid
, LINUX_NS_MNT
);
4460 /* Convert the INF argument passed to a to_fileio_* method
4461 to a process ID suitable for passing to its corresponding
4462 linux_mntns_* function. If INF is non-NULL then the
4463 caller is requesting the filesystem seen by INF. If INF
4464 is NULL then the caller is requesting the filesystem seen
4465 by the GDB. We fall back to GDB's filesystem in the case
4466 that INF is non-NULL but its PID is unknown. */
4469 linux_nat_fileio_pid_of (struct inferior
*inf
)
4471 if (inf
== NULL
|| inf
->fake_pid_p
|| inf
->pid
== 0)
4477 /* Implementation of to_fileio_open. */
4480 linux_nat_target::fileio_open (struct inferior
*inf
, const char *filename
,
4481 int flags
, int mode
, int warn_if_slow
,
4488 if (fileio_to_host_openflags (flags
, &nat_flags
) == -1
4489 || fileio_to_host_mode (mode
, &nat_mode
) == -1)
4491 *target_errno
= FILEIO_EINVAL
;
4495 fd
= linux_mntns_open_cloexec (linux_nat_fileio_pid_of (inf
),
4496 filename
, nat_flags
, nat_mode
);
4498 *target_errno
= host_to_fileio_error (errno
);
4503 /* Implementation of to_fileio_readlink. */
4505 gdb::optional
<std::string
>
4506 linux_nat_target::fileio_readlink (struct inferior
*inf
, const char *filename
,
4512 len
= linux_mntns_readlink (linux_nat_fileio_pid_of (inf
),
4513 filename
, buf
, sizeof (buf
));
4516 *target_errno
= host_to_fileio_error (errno
);
4520 return std::string (buf
, len
);
4523 /* Implementation of to_fileio_unlink. */
4526 linux_nat_target::fileio_unlink (struct inferior
*inf
, const char *filename
,
4531 ret
= linux_mntns_unlink (linux_nat_fileio_pid_of (inf
),
4534 *target_errno
= host_to_fileio_error (errno
);
4539 /* Implementation of the to_thread_events method. */
4542 linux_nat_target::thread_events (int enable
)
4544 report_thread_events
= enable
;
4547 linux_nat_target::linux_nat_target ()
4549 /* We don't change the stratum; this target will sit at
4550 process_stratum and thread_db will set at thread_stratum. This
4551 is a little strange, since this is a multi-threaded-capable
4552 target, but we want to be on the stack below thread_db, and we
4553 also want to be used for single-threaded processes. */
4556 /* See linux-nat.h. */
4559 linux_nat_get_siginfo (ptid_t ptid
, siginfo_t
*siginfo
)
4568 ptrace (PTRACE_GETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, siginfo
);
4571 memset (siginfo
, 0, sizeof (*siginfo
));
4577 /* See nat/linux-nat.h. */
4580 current_lwp_ptid (void)
4582 gdb_assert (inferior_ptid
.lwp_p ());
4583 return inferior_ptid
;
4586 void _initialize_linux_nat ();
4588 _initialize_linux_nat ()
4590 add_setshow_zuinteger_cmd ("lin-lwp", class_maintenance
,
4591 &debug_linux_nat
, _("\
4592 Set debugging of GNU/Linux lwp module."), _("\
4593 Show debugging of GNU/Linux lwp module."), _("\
4594 Enables printf debugging output."),
4596 show_debug_linux_nat
,
4597 &setdebuglist
, &showdebuglist
);
4599 add_setshow_boolean_cmd ("linux-namespaces", class_maintenance
,
4600 &debug_linux_namespaces
, _("\
4601 Set debugging of GNU/Linux namespaces module."), _("\
4602 Show debugging of GNU/Linux namespaces module."), _("\
4603 Enables printf debugging output."),
4606 &setdebuglist
, &showdebuglist
);
4608 /* Install a SIGCHLD handler. */
4609 sigchld_action
.sa_handler
= sigchld_handler
;
4610 sigemptyset (&sigchld_action
.sa_mask
);
4611 sigchld_action
.sa_flags
= SA_RESTART
;
4613 /* Make it the default. */
4614 sigaction (SIGCHLD
, &sigchld_action
, NULL
);
4616 /* Make sure we don't block SIGCHLD during a sigsuspend. */
4617 gdb_sigmask (SIG_SETMASK
, NULL
, &suspend_mask
);
4618 sigdelset (&suspend_mask
, SIGCHLD
);
4620 sigemptyset (&blocked_mask
);
4622 lwp_lwpid_htab_create ();
4626 /* FIXME: kettenis/2000-08-26: The stuff on this page is specific to
4627 the GNU/Linux Threads library and therefore doesn't really belong
4630 /* NPTL reserves the first two RT signals, but does not provide any
4631 way for the debugger to query the signal numbers - fortunately
4632 they don't change. */
4633 static int lin_thread_signals
[] = { __SIGRTMIN
, __SIGRTMIN
+ 1 };
4635 /* See linux-nat.h. */
4638 lin_thread_get_thread_signal_num (void)
4640 return sizeof (lin_thread_signals
) / sizeof (lin_thread_signals
[0]);
4643 /* See linux-nat.h. */
4646 lin_thread_get_thread_signal (unsigned int i
)
4648 gdb_assert (i
< lin_thread_get_thread_signal_num ());
4649 return lin_thread_signals
[i
];