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
)
1703 inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
1704 gdb_assert (inf
!= nullptr);
1706 ///* When we are waiting for a detached vfork child to exec or exit,
1707 // breakpoints are removed, so only let the */
1709 //if (inf->thread_waiting_for_vfork_done != nullptr
1710 // && inf->thread_waiting_for_vfork_done->ptid != lp->ptid)
1713 //if (inf->pending_detach)
1717 lp
->last_resume_kind
= resume_continue
;
1723 linux_nat_target::resume (ptid_t ptid
, int step
, enum gdb_signal signo
)
1725 struct lwp_info
*lp
;
1728 linux_nat_debug_printf ("Preparing to %s %s, %s, inferior_ptid %s",
1729 step
? "step" : "resume",
1730 target_pid_to_str (ptid
).c_str (),
1731 (signo
!= GDB_SIGNAL_0
1732 ? strsignal (gdb_signal_to_host (signo
)) : "0"),
1733 target_pid_to_str (inferior_ptid
).c_str ());
1735 /* A specific PTID means `step only this process id'. */
1736 resume_many
= (minus_one_ptid
== ptid
1739 /* Mark the lwps we're resuming as resumed and update their
1740 last_resume_kind to resume_continue. */
1741 iterate_over_lwps (ptid
, resume_set_callback
);
1743 /* See if it's the current inferior that should be handled
1746 lp
= find_lwp_pid (inferior_ptid
);
1748 lp
= find_lwp_pid (ptid
);
1749 gdb_assert (lp
!= NULL
);
1751 /* Remember if we're stepping. */
1752 lp
->last_resume_kind
= step
? resume_step
: resume_continue
;
1754 /* If we have a pending wait status for this thread, there is no
1755 point in resuming the process. But first make sure that
1756 linux_nat_wait won't preemptively handle the event - we
1757 should never take this short-circuit if we are going to
1758 leave LP running, since we have skipped resuming all the
1759 other threads. This bit of code needs to be synchronized
1760 with linux_nat_wait. */
1762 if (lp
->status
&& WIFSTOPPED (lp
->status
))
1765 && WSTOPSIG (lp
->status
)
1766 && sigismember (&pass_mask
, WSTOPSIG (lp
->status
)))
1768 linux_nat_debug_printf
1769 ("Not short circuiting for ignored status 0x%x", lp
->status
);
1771 /* FIXME: What should we do if we are supposed to continue
1772 this thread with a signal? */
1773 gdb_assert (signo
== GDB_SIGNAL_0
);
1774 signo
= gdb_signal_from_host (WSTOPSIG (lp
->status
));
1779 if (lwp_status_pending_p (lp
))
1781 /* FIXME: What should we do if we are supposed to continue
1782 this thread with a signal? */
1783 gdb_assert (signo
== GDB_SIGNAL_0
);
1785 linux_nat_debug_printf ("Short circuiting for status 0x%x",
1788 if (target_can_async_p ())
1791 /* Tell the event loop we have something to process. */
1798 iterate_over_lwps (ptid
, [=] (struct lwp_info
*info
)
1800 return linux_nat_resume_callback (info
, lp
);
1803 linux_nat_debug_printf ("%s %s, %s (resume event thread)",
1804 step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
1805 target_pid_to_str (lp
->ptid
).c_str (),
1806 (signo
!= GDB_SIGNAL_0
1807 ? strsignal (gdb_signal_to_host (signo
)) : "0"));
1809 linux_resume_one_lwp (lp
, step
, signo
);
1811 if (target_can_async_p ())
1815 /* Send a signal to an LWP. */
1818 kill_lwp (int lwpid
, int signo
)
1823 ret
= syscall (__NR_tkill
, lwpid
, signo
);
1824 if (errno
== ENOSYS
)
1826 /* If tkill fails, then we are not using nptl threads, a
1827 configuration we no longer support. */
1828 perror_with_name (("tkill"));
1833 /* Handle a GNU/Linux syscall trap wait response. If we see a syscall
1834 event, check if the core is interested in it: if not, ignore the
1835 event, and keep waiting; otherwise, we need to toggle the LWP's
1836 syscall entry/exit status, since the ptrace event itself doesn't
1837 indicate it, and report the trap to higher layers. */
1840 linux_handle_syscall_trap (struct lwp_info
*lp
, int stopping
)
1842 struct target_waitstatus
*ourstatus
= &lp
->waitstatus
;
1843 struct gdbarch
*gdbarch
= target_thread_architecture (lp
->ptid
);
1844 thread_info
*thread
= find_thread_ptid (linux_target
, lp
->ptid
);
1845 int syscall_number
= (int) gdbarch_get_syscall_number (gdbarch
, thread
);
1849 /* If we're stopping threads, there's a SIGSTOP pending, which
1850 makes it so that the LWP reports an immediate syscall return,
1851 followed by the SIGSTOP. Skip seeing that "return" using
1852 PTRACE_CONT directly, and let stop_wait_callback collect the
1853 SIGSTOP. Later when the thread is resumed, a new syscall
1854 entry event. If we didn't do this (and returned 0), we'd
1855 leave a syscall entry pending, and our caller, by using
1856 PTRACE_CONT to collect the SIGSTOP, skips the syscall return
1857 itself. Later, when the user re-resumes this LWP, we'd see
1858 another syscall entry event and we'd mistake it for a return.
1860 If stop_wait_callback didn't force the SIGSTOP out of the LWP
1861 (leaving immediately with LWP->signalled set, without issuing
1862 a PTRACE_CONT), it would still be problematic to leave this
1863 syscall enter pending, as later when the thread is resumed,
1864 it would then see the same syscall exit mentioned above,
1865 followed by the delayed SIGSTOP, while the syscall didn't
1866 actually get to execute. It seems it would be even more
1867 confusing to the user. */
1869 linux_nat_debug_printf
1870 ("ignoring syscall %d for LWP %ld (stopping threads), resuming with "
1871 "PTRACE_CONT for SIGSTOP", syscall_number
, lp
->ptid
.lwp ());
1873 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
1874 ptrace (PTRACE_CONT
, lp
->ptid
.lwp (), 0, 0);
1879 /* Always update the entry/return state, even if this particular
1880 syscall isn't interesting to the core now. In async mode,
1881 the user could install a new catchpoint for this syscall
1882 between syscall enter/return, and we'll need to know to
1883 report a syscall return if that happens. */
1884 lp
->syscall_state
= (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1885 ? TARGET_WAITKIND_SYSCALL_RETURN
1886 : TARGET_WAITKIND_SYSCALL_ENTRY
);
1888 if (catch_syscall_enabled ())
1890 if (catching_syscall_number (syscall_number
))
1892 /* Alright, an event to report. */
1893 ourstatus
->kind
= lp
->syscall_state
;
1894 ourstatus
->value
.syscall_number
= syscall_number
;
1896 linux_nat_debug_printf
1897 ("stopping for %s of syscall %d for LWP %ld",
1898 (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1899 ? "entry" : "return"), syscall_number
, lp
->ptid
.lwp ());
1904 linux_nat_debug_printf
1905 ("ignoring %s of syscall %d for LWP %ld",
1906 (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1907 ? "entry" : "return"), syscall_number
, lp
->ptid
.lwp ());
1911 /* If we had been syscall tracing, and hence used PT_SYSCALL
1912 before on this LWP, it could happen that the user removes all
1913 syscall catchpoints before we get to process this event.
1914 There are two noteworthy issues here:
1916 - When stopped at a syscall entry event, resuming with
1917 PT_STEP still resumes executing the syscall and reports a
1920 - Only PT_SYSCALL catches syscall enters. If we last
1921 single-stepped this thread, then this event can't be a
1922 syscall enter. If we last single-stepped this thread, this
1923 has to be a syscall exit.
1925 The points above mean that the next resume, be it PT_STEP or
1926 PT_CONTINUE, can not trigger a syscall trace event. */
1927 linux_nat_debug_printf
1928 ("caught syscall event with no syscall catchpoints. %d for LWP %ld, "
1929 "ignoring", syscall_number
, lp
->ptid
.lwp ());
1930 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
1933 /* The core isn't interested in this event. For efficiency, avoid
1934 stopping all threads only to have the core resume them all again.
1935 Since we're not stopping threads, if we're still syscall tracing
1936 and not stepping, we can't use PTRACE_CONT here, as we'd miss any
1937 subsequent syscall. Simply resume using the inf-ptrace layer,
1938 which knows when to use PT_SYSCALL or PT_CONTINUE. */
1940 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
1944 /* Handle a GNU/Linux extended wait response. If we see a clone
1945 event, we need to add the new LWP to our list (and not report the
1946 trap to higher layers). This function returns non-zero if the
1947 event should be ignored and we should wait again. If STOPPING is
1948 true, the new LWP remains stopped, otherwise it is continued. */
1951 linux_handle_extended_wait (struct lwp_info
*lp
, int status
)
1953 int pid
= lp
->ptid
.lwp ();
1954 struct target_waitstatus
*ourstatus
= &lp
->waitstatus
;
1955 int event
= linux_ptrace_get_extended_event (status
);
1957 /* All extended events we currently use are mid-syscall. Only
1958 PTRACE_EVENT_STOP is delivered more like a signal-stop, but
1959 you have to be using PTRACE_SEIZE to get that. */
1960 lp
->syscall_state
= TARGET_WAITKIND_SYSCALL_ENTRY
;
1962 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
1963 || event
== PTRACE_EVENT_CLONE
)
1965 unsigned long new_pid
;
1968 ptrace (PTRACE_GETEVENTMSG
, pid
, 0, &new_pid
);
1970 /* If we haven't already seen the new PID stop, wait for it now. */
1971 if (! pull_pid_from_list (&stopped_pids
, new_pid
, &status
))
1973 /* The new child has a pending SIGSTOP. We can't affect it until it
1974 hits the SIGSTOP, but we're already attached. */
1975 ret
= my_waitpid (new_pid
, &status
, __WALL
);
1977 perror_with_name (_("waiting for new child"));
1978 else if (ret
!= new_pid
)
1979 internal_error (__FILE__
, __LINE__
,
1980 _("wait returned unexpected PID %d"), ret
);
1981 else if (!WIFSTOPPED (status
))
1982 internal_error (__FILE__
, __LINE__
,
1983 _("wait returned unexpected status 0x%x"), status
);
1986 ourstatus
->value
.related_pid
= ptid_t (new_pid
, new_pid
, 0);
1988 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
)
1990 /* The arch-specific native code may need to know about new
1991 forks even if those end up never mapped to an
1993 linux_target
->low_new_fork (lp
, new_pid
);
1995 else if (event
== PTRACE_EVENT_CLONE
)
1997 linux_target
->low_new_clone (lp
, new_pid
);
2000 if (event
== PTRACE_EVENT_FORK
2001 && linux_fork_checkpointing_p (lp
->ptid
.pid ()))
2003 /* Handle checkpointing by linux-fork.c here as a special
2004 case. We don't want the follow-fork-mode or 'catch fork'
2005 to interfere with this. */
2007 /* This won't actually modify the breakpoint list, but will
2008 physically remove the breakpoints from the child. */
2009 detach_breakpoints (ptid_t (new_pid
, new_pid
, 0));
2011 /* Retain child fork in ptrace (stopped) state. */
2012 if (!find_fork_pid (new_pid
))
2015 /* Report as spurious, so that infrun doesn't want to follow
2016 this fork. We're actually doing an infcall in
2018 ourstatus
->kind
= TARGET_WAITKIND_SPURIOUS
;
2020 /* Report the stop to the core. */
2024 if (event
== PTRACE_EVENT_FORK
)
2025 ourstatus
->kind
= TARGET_WAITKIND_FORKED
;
2026 else if (event
== PTRACE_EVENT_VFORK
)
2027 ourstatus
->kind
= TARGET_WAITKIND_VFORKED
;
2028 else if (event
== PTRACE_EVENT_CLONE
)
2030 struct lwp_info
*new_lp
;
2032 ourstatus
->kind
= TARGET_WAITKIND_IGNORE
;
2034 linux_nat_debug_printf
2035 ("Got clone event from LWP %d, new child is LWP %ld", pid
, new_pid
);
2037 new_lp
= add_lwp (ptid_t (lp
->ptid
.pid (), new_pid
, 0));
2038 new_lp
->stopped
= 1;
2039 new_lp
->resumed
= 1;
2041 /* If the thread_db layer is active, let it record the user
2042 level thread id and status, and add the thread to GDB's
2044 if (!thread_db_notice_clone (lp
->ptid
, new_lp
->ptid
))
2046 /* The process is not using thread_db. Add the LWP to
2048 target_post_attach (new_lp
->ptid
.lwp ());
2049 add_thread (linux_target
, new_lp
->ptid
);
2052 /* Even if we're stopping the thread for some reason
2053 internal to this module, from the perspective of infrun
2054 and the user/frontend, this new thread is running until
2055 it next reports a stop. */
2056 set_running (linux_target
, new_lp
->ptid
, true);
2057 set_executing (linux_target
, new_lp
->ptid
, true);
2059 if (WSTOPSIG (status
) != SIGSTOP
)
2061 /* This can happen if someone starts sending signals to
2062 the new thread before it gets a chance to run, which
2063 have a lower number than SIGSTOP (e.g. SIGUSR1).
2064 This is an unlikely case, and harder to handle for
2065 fork / vfork than for clone, so we do not try - but
2066 we handle it for clone events here. */
2068 new_lp
->signalled
= 1;
2070 /* We created NEW_LP so it cannot yet contain STATUS. */
2071 gdb_assert (new_lp
->status
== 0);
2073 /* Save the wait status to report later. */
2074 linux_nat_debug_printf
2075 ("waitpid of new LWP %ld, saving status %s",
2076 (long) new_lp
->ptid
.lwp (), status_to_str (status
).c_str ());
2077 new_lp
->status
= status
;
2079 else if (report_thread_events
)
2081 new_lp
->waitstatus
.kind
= TARGET_WAITKIND_THREAD_CREATED
;
2082 new_lp
->status
= status
;
2091 if (event
== PTRACE_EVENT_EXEC
)
2093 linux_nat_debug_printf ("Got exec event from LWP %ld", lp
->ptid
.lwp ());
2095 /* Close the /proc/<pid>/mem file if it was open for this
2097 maybe_close_proc_mem_file (lp
->ptid
.pid ());
2099 ourstatus
->kind
= TARGET_WAITKIND_EXECD
;
2100 ourstatus
->value
.execd_pathname
2101 = xstrdup (linux_proc_pid_to_exec_file (pid
));
2103 /* The thread that execed must have been resumed, but, when a
2104 thread execs, it changes its tid to the tgid, and the old
2105 tgid thread might have not been resumed. */
2110 if (event
== PTRACE_EVENT_VFORK_DONE
)
2112 linux_nat_debug_printf
2113 ("Got PTRACE_EVENT_VFORK_DONE from LWP %ld: stopping", lp
->ptid
.lwp ());
2114 ourstatus
->kind
= TARGET_WAITKIND_VFORK_DONE
;
2118 internal_error (__FILE__
, __LINE__
,
2119 _("unknown ptrace event %d"), event
);
2122 /* Suspend waiting for a signal. We're mostly interested in
2128 linux_nat_debug_printf ("about to sigsuspend");
2129 sigsuspend (&suspend_mask
);
2131 /* If the quit flag is set, it means that the user pressed Ctrl-C
2132 and we're debugging a process that is running on a separate
2133 terminal, so we must forward the Ctrl-C to the inferior. (If the
2134 inferior is sharing GDB's terminal, then the Ctrl-C reaches the
2135 inferior directly.) We must do this here because functions that
2136 need to block waiting for a signal loop forever until there's an
2137 event to report before returning back to the event loop. */
2138 if (!target_terminal::is_ours ())
2140 if (check_quit_flag ())
2141 target_pass_ctrlc ();
2145 /* Wait for LP to stop. Returns the wait status, or 0 if the LWP has
2149 wait_lwp (struct lwp_info
*lp
)
2153 int thread_dead
= 0;
2156 gdb_assert (!lp
->stopped
);
2157 gdb_assert (lp
->status
== 0);
2159 /* Make sure SIGCHLD is blocked for sigsuspend avoiding a race below. */
2160 block_child_signals (&prev_mask
);
2164 pid
= my_waitpid (lp
->ptid
.lwp (), &status
, __WALL
| WNOHANG
);
2165 if (pid
== -1 && errno
== ECHILD
)
2167 /* The thread has previously exited. We need to delete it
2168 now because if this was a non-leader thread execing, we
2169 won't get an exit event. See comments on exec events at
2170 the top of the file. */
2172 linux_nat_debug_printf ("%s vanished.",
2173 target_pid_to_str (lp
->ptid
).c_str ());
2178 /* Bugs 10970, 12702.
2179 Thread group leader may have exited in which case we'll lock up in
2180 waitpid if there are other threads, even if they are all zombies too.
2181 Basically, we're not supposed to use waitpid this way.
2182 tkill(pid,0) cannot be used here as it gets ESRCH for both
2183 for zombie and running processes.
2185 As a workaround, check if we're waiting for the thread group leader and
2186 if it's a zombie, and avoid calling waitpid if it is.
2188 This is racy, what if the tgl becomes a zombie right after we check?
2189 Therefore always use WNOHANG with sigsuspend - it is equivalent to
2190 waiting waitpid but linux_proc_pid_is_zombie is safe this way. */
2192 if (lp
->ptid
.pid () == lp
->ptid
.lwp ()
2193 && linux_proc_pid_is_zombie (lp
->ptid
.lwp ()))
2196 linux_nat_debug_printf ("Thread group leader %s vanished.",
2197 target_pid_to_str (lp
->ptid
).c_str ());
2201 /* Wait for next SIGCHLD and try again. This may let SIGCHLD handlers
2202 get invoked despite our caller had them intentionally blocked by
2203 block_child_signals. This is sensitive only to the loop of
2204 linux_nat_wait_1 and there if we get called my_waitpid gets called
2205 again before it gets to sigsuspend so we can safely let the handlers
2206 get executed here. */
2210 restore_child_signals_mask (&prev_mask
);
2214 gdb_assert (pid
== lp
->ptid
.lwp ());
2216 linux_nat_debug_printf ("waitpid %s received %s",
2217 target_pid_to_str (lp
->ptid
).c_str (),
2218 status_to_str (status
).c_str ());
2220 /* Check if the thread has exited. */
2221 if (WIFEXITED (status
) || WIFSIGNALED (status
))
2223 if (report_thread_events
2224 || lp
->ptid
.pid () == lp
->ptid
.lwp ())
2226 linux_nat_debug_printf ("LWP %d exited.", lp
->ptid
.pid ());
2228 /* If this is the leader exiting, it means the whole
2229 process is gone. Store the status to report to the
2230 core. Store it in lp->waitstatus, because lp->status
2231 would be ambiguous (W_EXITCODE(0,0) == 0). */
2232 store_waitstatus (&lp
->waitstatus
, status
);
2237 linux_nat_debug_printf ("%s exited.",
2238 target_pid_to_str (lp
->ptid
).c_str ());
2248 gdb_assert (WIFSTOPPED (status
));
2251 if (lp
->must_set_ptrace_flags
)
2253 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2254 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
2256 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
2257 lp
->must_set_ptrace_flags
= 0;
2260 /* Handle GNU/Linux's syscall SIGTRAPs. */
2261 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
2263 /* No longer need the sysgood bit. The ptrace event ends up
2264 recorded in lp->waitstatus if we care for it. We can carry
2265 on handling the event like a regular SIGTRAP from here
2267 status
= W_STOPCODE (SIGTRAP
);
2268 if (linux_handle_syscall_trap (lp
, 1))
2269 return wait_lwp (lp
);
2273 /* Almost all other ptrace-stops are known to be outside of system
2274 calls, with further exceptions in linux_handle_extended_wait. */
2275 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
2278 /* Handle GNU/Linux's extended waitstatus for trace events. */
2279 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
2280 && linux_is_extended_waitstatus (status
))
2282 linux_nat_debug_printf ("Handling extended status 0x%06x", status
);
2283 linux_handle_extended_wait (lp
, status
);
2290 /* Send a SIGSTOP to LP. */
2293 stop_callback (struct lwp_info
*lp
)
2295 if (!lp
->stopped
&& !lp
->signalled
)
2299 linux_nat_debug_printf ("kill %s **<SIGSTOP>**",
2300 target_pid_to_str (lp
->ptid
).c_str ());
2303 ret
= kill_lwp (lp
->ptid
.lwp (), SIGSTOP
);
2304 linux_nat_debug_printf ("lwp kill %d %s", ret
,
2305 errno
? safe_strerror (errno
) : "ERRNO-OK");
2308 gdb_assert (lp
->status
== 0);
2314 /* Request a stop on LWP. */
2317 linux_stop_lwp (struct lwp_info
*lwp
)
2319 stop_callback (lwp
);
2322 /* See linux-nat.h */
2325 linux_stop_and_wait_all_lwps (void)
2327 /* Stop all LWP's ... */
2328 iterate_over_lwps (minus_one_ptid
, stop_callback
);
2330 /* ... and wait until all of them have reported back that
2331 they're no longer running. */
2332 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
2335 /* See linux-nat.h */
2338 linux_unstop_all_lwps (void)
2340 iterate_over_lwps (minus_one_ptid
,
2341 [] (struct lwp_info
*info
)
2343 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
2347 /* Return non-zero if LWP PID has a pending SIGINT. */
2350 linux_nat_has_pending_sigint (int pid
)
2352 sigset_t pending
, blocked
, ignored
;
2354 linux_proc_pending_signals (pid
, &pending
, &blocked
, &ignored
);
2356 if (sigismember (&pending
, SIGINT
)
2357 && !sigismember (&ignored
, SIGINT
))
2363 /* Set a flag in LP indicating that we should ignore its next SIGINT. */
2366 set_ignore_sigint (struct lwp_info
*lp
)
2368 /* If a thread has a pending SIGINT, consume it; otherwise, set a
2369 flag to consume the next one. */
2370 if (lp
->stopped
&& lp
->status
!= 0 && WIFSTOPPED (lp
->status
)
2371 && WSTOPSIG (lp
->status
) == SIGINT
)
2374 lp
->ignore_sigint
= 1;
2379 /* If LP does not have a SIGINT pending, then clear the ignore_sigint flag.
2380 This function is called after we know the LWP has stopped; if the LWP
2381 stopped before the expected SIGINT was delivered, then it will never have
2382 arrived. Also, if the signal was delivered to a shared queue and consumed
2383 by a different thread, it will never be delivered to this LWP. */
2386 maybe_clear_ignore_sigint (struct lwp_info
*lp
)
2388 if (!lp
->ignore_sigint
)
2391 if (!linux_nat_has_pending_sigint (lp
->ptid
.lwp ()))
2393 linux_nat_debug_printf ("Clearing bogus flag for %s",
2394 target_pid_to_str (lp
->ptid
).c_str ());
2395 lp
->ignore_sigint
= 0;
2399 /* Fetch the possible triggered data watchpoint info and store it in
2402 On some archs, like x86, that use debug registers to set
2403 watchpoints, it's possible that the way to know which watched
2404 address trapped, is to check the register that is used to select
2405 which address to watch. Problem is, between setting the watchpoint
2406 and reading back which data address trapped, the user may change
2407 the set of watchpoints, and, as a consequence, GDB changes the
2408 debug registers in the inferior. To avoid reading back a stale
2409 stopped-data-address when that happens, we cache in LP the fact
2410 that a watchpoint trapped, and the corresponding data address, as
2411 soon as we see LP stop with a SIGTRAP. If GDB changes the debug
2412 registers meanwhile, we have the cached data we can rely on. */
2415 check_stopped_by_watchpoint (struct lwp_info
*lp
)
2417 scoped_restore save_inferior_ptid
= make_scoped_restore (&inferior_ptid
);
2418 inferior_ptid
= lp
->ptid
;
2420 if (linux_target
->low_stopped_by_watchpoint ())
2422 lp
->stop_reason
= TARGET_STOPPED_BY_WATCHPOINT
;
2423 lp
->stopped_data_address_p
2424 = linux_target
->low_stopped_data_address (&lp
->stopped_data_address
);
2427 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2430 /* Returns true if the LWP had stopped for a watchpoint. */
2433 linux_nat_target::stopped_by_watchpoint ()
2435 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2437 gdb_assert (lp
!= NULL
);
2439 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2443 linux_nat_target::stopped_data_address (CORE_ADDR
*addr_p
)
2445 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2447 gdb_assert (lp
!= NULL
);
2449 *addr_p
= lp
->stopped_data_address
;
2451 return lp
->stopped_data_address_p
;
2454 /* Commonly any breakpoint / watchpoint generate only SIGTRAP. */
2457 linux_nat_target::low_status_is_event (int status
)
2459 return WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
;
2462 /* Wait until LP is stopped. */
2465 stop_wait_callback (struct lwp_info
*lp
)
2467 inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
2469 /* If this is a vfork parent, bail out, it is not going to report
2470 any SIGSTOP until the vfork is done with. */
2471 if (inf
->vfork_child
!= NULL
)
2478 status
= wait_lwp (lp
);
2482 if (lp
->ignore_sigint
&& WIFSTOPPED (status
)
2483 && WSTOPSIG (status
) == SIGINT
)
2485 lp
->ignore_sigint
= 0;
2488 ptrace (PTRACE_CONT
, lp
->ptid
.lwp (), 0, 0);
2490 linux_nat_debug_printf
2491 ("PTRACE_CONT %s, 0, 0 (%s) (discarding SIGINT)",
2492 target_pid_to_str (lp
->ptid
).c_str (),
2493 errno
? safe_strerror (errno
) : "OK");
2495 return stop_wait_callback (lp
);
2498 maybe_clear_ignore_sigint (lp
);
2500 if (WSTOPSIG (status
) != SIGSTOP
)
2502 /* The thread was stopped with a signal other than SIGSTOP. */
2504 linux_nat_debug_printf ("Pending event %s in %s",
2505 status_to_str ((int) status
).c_str (),
2506 target_pid_to_str (lp
->ptid
).c_str ());
2508 /* Save the sigtrap event. */
2509 lp
->status
= status
;
2510 gdb_assert (lp
->signalled
);
2511 save_stop_reason (lp
);
2515 /* We caught the SIGSTOP that we intended to catch. */
2517 linux_nat_debug_printf ("Expected SIGSTOP caught for %s.",
2518 target_pid_to_str (lp
->ptid
).c_str ());
2522 /* If we are waiting for this stop so we can report the thread
2523 stopped then we need to record this status. Otherwise, we can
2524 now discard this stop event. */
2525 if (lp
->last_resume_kind
== resume_stop
)
2527 lp
->status
= status
;
2528 save_stop_reason (lp
);
2536 /* Return non-zero if LP has a wait status pending. Discard the
2537 pending event and resume the LWP if the event that originally
2538 caused the stop became uninteresting. */
2541 status_callback (struct lwp_info
*lp
)
2543 /* Only report a pending wait status if we pretend that this has
2544 indeed been resumed. */
2548 if (!lwp_status_pending_p (lp
))
2551 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
2552 || lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2554 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2558 pc
= regcache_read_pc (regcache
);
2560 if (pc
!= lp
->stop_pc
)
2562 linux_nat_debug_printf ("PC of %s changed. was=%s, now=%s",
2563 target_pid_to_str (lp
->ptid
).c_str (),
2564 paddress (target_gdbarch (), lp
->stop_pc
),
2565 paddress (target_gdbarch (), pc
));
2569 #if !USE_SIGTRAP_SIGINFO
2570 else if (!breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2572 linux_nat_debug_printf ("previous breakpoint of %s, at %s gone",
2573 target_pid_to_str (lp
->ptid
).c_str (),
2574 paddress (target_gdbarch (), lp
->stop_pc
));
2582 linux_nat_debug_printf ("pending event of %s cancelled.",
2583 target_pid_to_str (lp
->ptid
).c_str ());
2586 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2594 /* Count the LWP's that have had events. */
2597 count_events_callback (struct lwp_info
*lp
, int *count
)
2599 gdb_assert (count
!= NULL
);
2601 /* Select only resumed LWPs that have an event pending. */
2602 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2608 /* Select the LWP (if any) that is currently being single-stepped. */
2611 select_singlestep_lwp_callback (struct lwp_info
*lp
)
2613 if (lp
->last_resume_kind
== resume_step
2620 /* Returns true if LP has a status pending. */
2623 lwp_status_pending_p (struct lwp_info
*lp
)
2625 /* We check for lp->waitstatus in addition to lp->status, because we
2626 can have pending process exits recorded in lp->status and
2627 W_EXITCODE(0,0) happens to be 0. */
2628 return lp
->status
!= 0 || lp
->waitstatus
.kind
!= TARGET_WAITKIND_IGNORE
;
2631 /* Select the Nth LWP that has had an event. */
2634 select_event_lwp_callback (struct lwp_info
*lp
, int *selector
)
2636 gdb_assert (selector
!= NULL
);
2638 /* Select only resumed LWPs that have an event pending. */
2639 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2640 if ((*selector
)-- == 0)
2646 /* Called when the LWP stopped for a signal/trap. If it stopped for a
2647 trap check what caused it (breakpoint, watchpoint, trace, etc.),
2648 and save the result in the LWP's stop_reason field. If it stopped
2649 for a breakpoint, decrement the PC if necessary on the lwp's
2653 save_stop_reason (struct lwp_info
*lp
)
2655 struct regcache
*regcache
;
2656 struct gdbarch
*gdbarch
;
2659 #if USE_SIGTRAP_SIGINFO
2663 gdb_assert (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
);
2664 gdb_assert (lp
->status
!= 0);
2666 if (!linux_target
->low_status_is_event (lp
->status
))
2669 regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2670 gdbarch
= regcache
->arch ();
2672 pc
= regcache_read_pc (regcache
);
2673 sw_bp_pc
= pc
- gdbarch_decr_pc_after_break (gdbarch
);
2675 #if USE_SIGTRAP_SIGINFO
2676 if (linux_nat_get_siginfo (lp
->ptid
, &siginfo
))
2678 if (siginfo
.si_signo
== SIGTRAP
)
2680 if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
)
2681 && GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2683 /* The si_code is ambiguous on this arch -- check debug
2685 if (!check_stopped_by_watchpoint (lp
))
2686 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2688 else if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
))
2690 /* If we determine the LWP stopped for a SW breakpoint,
2691 trust it. Particularly don't check watchpoint
2692 registers, because, at least on s390, we'd find
2693 stopped-by-watchpoint as long as there's a watchpoint
2695 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2697 else if (GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2699 /* This can indicate either a hardware breakpoint or
2700 hardware watchpoint. Check debug registers. */
2701 if (!check_stopped_by_watchpoint (lp
))
2702 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2704 else if (siginfo
.si_code
== TRAP_TRACE
)
2706 linux_nat_debug_printf ("%s stopped by trace",
2707 target_pid_to_str (lp
->ptid
).c_str ());
2709 /* We may have single stepped an instruction that
2710 triggered a watchpoint. In that case, on some
2711 architectures (such as x86), instead of TRAP_HWBKPT,
2712 si_code indicates TRAP_TRACE, and we need to check
2713 the debug registers separately. */
2714 check_stopped_by_watchpoint (lp
);
2719 if ((!lp
->step
|| lp
->stop_pc
== sw_bp_pc
)
2720 && software_breakpoint_inserted_here_p (regcache
->aspace (),
2723 /* The LWP was either continued, or stepped a software
2724 breakpoint instruction. */
2725 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2728 if (hardware_breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2729 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2731 if (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
)
2732 check_stopped_by_watchpoint (lp
);
2735 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
)
2737 linux_nat_debug_printf ("%s stopped by software breakpoint",
2738 target_pid_to_str (lp
->ptid
).c_str ());
2740 /* Back up the PC if necessary. */
2742 regcache_write_pc (regcache
, sw_bp_pc
);
2744 /* Update this so we record the correct stop PC below. */
2747 else if (lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2749 linux_nat_debug_printf ("%s stopped by hardware breakpoint",
2750 target_pid_to_str (lp
->ptid
).c_str ());
2752 else if (lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
)
2754 linux_nat_debug_printf ("%s stopped by hardware watchpoint",
2755 target_pid_to_str (lp
->ptid
).c_str ());
2762 /* Returns true if the LWP had stopped for a software breakpoint. */
2765 linux_nat_target::stopped_by_sw_breakpoint ()
2767 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2769 gdb_assert (lp
!= NULL
);
2771 return lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
;
2774 /* Implement the supports_stopped_by_sw_breakpoint method. */
2777 linux_nat_target::supports_stopped_by_sw_breakpoint ()
2779 return USE_SIGTRAP_SIGINFO
;
2782 /* Returns true if the LWP had stopped for a hardware
2783 breakpoint/watchpoint. */
2786 linux_nat_target::stopped_by_hw_breakpoint ()
2788 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2790 gdb_assert (lp
!= NULL
);
2792 return lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
;
2795 /* Implement the supports_stopped_by_hw_breakpoint method. */
2798 linux_nat_target::supports_stopped_by_hw_breakpoint ()
2800 return USE_SIGTRAP_SIGINFO
;
2803 /* Select one LWP out of those that have events pending. */
2806 select_event_lwp (ptid_t filter
, struct lwp_info
**orig_lp
, int *status
)
2809 int random_selector
;
2810 struct lwp_info
*event_lp
= NULL
;
2812 /* Record the wait status for the original LWP. */
2813 (*orig_lp
)->status
= *status
;
2815 /* In all-stop, give preference to the LWP that is being
2816 single-stepped. There will be at most one, and it will be the
2817 LWP that the core is most interested in. If we didn't do this,
2818 then we'd have to handle pending step SIGTRAPs somehow in case
2819 the core later continues the previously-stepped thread, as
2820 otherwise we'd report the pending SIGTRAP then, and the core, not
2821 having stepped the thread, wouldn't understand what the trap was
2822 for, and therefore would report it to the user as a random
2824 if (!target_is_non_stop_p ())
2826 event_lp
= iterate_over_lwps (filter
, select_singlestep_lwp_callback
);
2827 if (event_lp
!= NULL
)
2829 linux_nat_debug_printf ("Select single-step %s",
2830 target_pid_to_str (event_lp
->ptid
).c_str ());
2834 if (event_lp
== NULL
)
2836 /* Pick one at random, out of those which have had events. */
2838 /* First see how many events we have. */
2839 iterate_over_lwps (filter
,
2840 [&] (struct lwp_info
*info
)
2842 return count_events_callback (info
, &num_events
);
2844 gdb_assert (num_events
> 0);
2846 /* Now randomly pick a LWP out of those that have had
2848 random_selector
= (int)
2849 ((num_events
* (double) rand ()) / (RAND_MAX
+ 1.0));
2852 linux_nat_debug_printf ("Found %d events, selecting #%d",
2853 num_events
, random_selector
);
2856 = (iterate_over_lwps
2858 [&] (struct lwp_info
*info
)
2860 return select_event_lwp_callback (info
,
2865 if (event_lp
!= NULL
)
2867 /* Switch the event LWP. */
2868 *orig_lp
= event_lp
;
2869 *status
= event_lp
->status
;
2872 /* Flush the wait status for the event LWP. */
2873 (*orig_lp
)->status
= 0;
2876 /* Return non-zero if LP has been resumed. */
2879 resumed_callback (struct lwp_info
*lp
)
2884 /* Check if we should go on and pass this event to common code.
2886 If so, save the status to the lwp_info structure associated to LWPID. */
2889 linux_nat_filter_event (int lwpid
, int status
)
2891 struct lwp_info
*lp
;
2892 int event
= linux_ptrace_get_extended_event (status
);
2894 lp
= find_lwp_pid (ptid_t (lwpid
));
2896 /* Check for stop events reported by a process we didn't already
2897 know about - anything not already in our LWP list.
2899 If we're expecting to receive stopped processes after
2900 fork, vfork, and clone events, then we'll just add the
2901 new one to our list and go back to waiting for the event
2902 to be reported - the stopped process might be returned
2903 from waitpid before or after the event is.
2905 But note the case of a non-leader thread exec'ing after the
2906 leader having exited, and gone from our lists. The non-leader
2907 thread changes its tid to the tgid. */
2909 if (WIFSTOPPED (status
) && lp
== NULL
2910 && (WSTOPSIG (status
) == SIGTRAP
&& event
== PTRACE_EVENT_EXEC
))
2912 /* A multi-thread exec after we had seen the leader exiting. */
2913 linux_nat_debug_printf ("Re-adding thread group leader LWP %d.", lwpid
);
2915 lp
= add_lwp (ptid_t (lwpid
, lwpid
, 0));
2918 add_thread (linux_target
, lp
->ptid
);
2921 if (WIFSTOPPED (status
) && !lp
)
2923 linux_nat_debug_printf ("saving LWP %ld status %s in stopped_pids list",
2924 (long) lwpid
, status_to_str (status
).c_str ());
2925 add_to_pid_list (&stopped_pids
, lwpid
, status
);
2929 /* Make sure we don't report an event for the exit of an LWP not in
2930 our list, i.e. not part of the current process. This can happen
2931 if we detach from a program we originally forked and then it
2933 if (!WIFSTOPPED (status
) && !lp
)
2936 /* This LWP is stopped now. (And if dead, this prevents it from
2937 ever being continued.) */
2940 if (WIFSTOPPED (status
) && lp
->must_set_ptrace_flags
)
2942 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2943 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
2945 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
2946 lp
->must_set_ptrace_flags
= 0;
2949 /* Handle GNU/Linux's syscall SIGTRAPs. */
2950 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
2952 /* No longer need the sysgood bit. The ptrace event ends up
2953 recorded in lp->waitstatus if we care for it. We can carry
2954 on handling the event like a regular SIGTRAP from here
2956 status
= W_STOPCODE (SIGTRAP
);
2957 if (linux_handle_syscall_trap (lp
, 0))
2962 /* Almost all other ptrace-stops are known to be outside of system
2963 calls, with further exceptions in linux_handle_extended_wait. */
2964 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
2967 /* Handle GNU/Linux's extended waitstatus for trace events. */
2968 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
2969 && linux_is_extended_waitstatus (status
))
2971 linux_nat_debug_printf ("Handling extended status 0x%06x", status
);
2973 if (linux_handle_extended_wait (lp
, status
))
2977 /* Check if the thread has exited. */
2978 if (WIFEXITED (status
) || WIFSIGNALED (status
))
2980 if (!report_thread_events
2981 && num_lwps (lp
->ptid
.pid ()) > 1)
2983 linux_nat_debug_printf ("%s exited.",
2984 target_pid_to_str (lp
->ptid
).c_str ());
2986 /* If there is at least one more LWP, then the exit signal
2987 was not the end of the debugged application and should be
2993 /* Note that even if the leader was ptrace-stopped, it can still
2994 exit, if e.g., some other thread brings down the whole
2995 process (calls `exit'). So don't assert that the lwp is
2997 linux_nat_debug_printf ("LWP %ld exited (resumed=%d)",
2998 lp
->ptid
.lwp (), lp
->resumed
);
3000 /* Dead LWP's aren't expected to reported a pending sigstop. */
3003 /* Store the pending event in the waitstatus, because
3004 W_EXITCODE(0,0) == 0. */
3005 store_waitstatus (&lp
->waitstatus
, status
);
3009 /* Make sure we don't report a SIGSTOP that we sent ourselves in
3010 an attempt to stop an LWP. */
3012 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGSTOP
)
3016 if (lp
->last_resume_kind
== resume_stop
)
3018 linux_nat_debug_printf ("resume_stop SIGSTOP caught for %s.",
3019 target_pid_to_str (lp
->ptid
).c_str ());
3023 /* This is a delayed SIGSTOP. Filter out the event. */
3025 linux_nat_debug_printf
3026 ("%s %s, 0, 0 (discard delayed SIGSTOP)",
3027 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
3028 target_pid_to_str (lp
->ptid
).c_str ());
3030 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
3031 gdb_assert (lp
->resumed
);
3036 /* Make sure we don't report a SIGINT that we have already displayed
3037 for another thread. */
3038 if (lp
->ignore_sigint
3039 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGINT
)
3041 linux_nat_debug_printf ("Delayed SIGINT caught for %s.",
3042 target_pid_to_str (lp
->ptid
).c_str ());
3044 /* This is a delayed SIGINT. */
3045 lp
->ignore_sigint
= 0;
3047 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
3048 linux_nat_debug_printf ("%s %s, 0, 0 (discard SIGINT)",
3049 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
3050 target_pid_to_str (lp
->ptid
).c_str ());
3051 gdb_assert (lp
->resumed
);
3053 /* Discard the event. */
3057 /* Don't report signals that GDB isn't interested in, such as
3058 signals that are neither printed nor stopped upon. Stopping all
3059 threads can be a bit time-consuming, so if we want decent
3060 performance with heavily multi-threaded programs, especially when
3061 they're using a high frequency timer, we'd better avoid it if we
3063 if (WIFSTOPPED (status
))
3065 enum gdb_signal signo
= gdb_signal_from_host (WSTOPSIG (status
));
3067 if (!target_is_non_stop_p ())
3069 /* Only do the below in all-stop, as we currently use SIGSTOP
3070 to implement target_stop (see linux_nat_stop) in
3072 if (signo
== GDB_SIGNAL_INT
&& signal_pass_state (signo
) == 0)
3074 /* If ^C/BREAK is typed at the tty/console, SIGINT gets
3075 forwarded to the entire process group, that is, all LWPs
3076 will receive it - unless they're using CLONE_THREAD to
3077 share signals. Since we only want to report it once, we
3078 mark it as ignored for all LWPs except this one. */
3079 iterate_over_lwps (ptid_t (lp
->ptid
.pid ()), set_ignore_sigint
);
3080 lp
->ignore_sigint
= 0;
3083 maybe_clear_ignore_sigint (lp
);
3086 /* When using hardware single-step, we need to report every signal.
3087 Otherwise, signals in pass_mask may be short-circuited
3088 except signals that might be caused by a breakpoint, or SIGSTOP
3089 if we sent the SIGSTOP and are waiting for it to arrive. */
3091 && WSTOPSIG (status
) && sigismember (&pass_mask
, WSTOPSIG (status
))
3092 && (WSTOPSIG (status
) != SIGSTOP
3093 || !find_thread_ptid (linux_target
, lp
->ptid
)->stop_requested
)
3094 && !linux_wstatus_maybe_breakpoint (status
))
3096 linux_resume_one_lwp (lp
, lp
->step
, signo
);
3097 linux_nat_debug_printf
3098 ("%s %s, %s (preempt 'handle')",
3099 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
3100 target_pid_to_str (lp
->ptid
).c_str (),
3101 (signo
!= GDB_SIGNAL_0
3102 ? strsignal (gdb_signal_to_host (signo
)) : "0"));
3107 /* An interesting event. */
3109 lp
->status
= status
;
3110 save_stop_reason (lp
);
3113 /* Detect zombie thread group leaders, and "exit" them. We can't reap
3114 their exits until all other threads in the group have exited. */
3117 check_zombie_leaders (void)
3119 for (inferior
*inf
: all_inferiors ())
3121 struct lwp_info
*leader_lp
;
3126 leader_lp
= find_lwp_pid (ptid_t (inf
->pid
));
3127 if (leader_lp
!= NULL
3128 /* Check if there are other threads in the group, as we may
3129 have raced with the inferior simply exiting. */
3130 && num_lwps (inf
->pid
) > 1
3131 && linux_proc_pid_is_zombie (inf
->pid
))
3133 linux_nat_debug_printf ("Thread group leader %d zombie "
3134 "(it exited, or another thread execd).",
3137 /* A leader zombie can mean one of two things:
3139 - It exited, and there's an exit status pending
3140 available, or only the leader exited (not the whole
3141 program). In the latter case, we can't waitpid the
3142 leader's exit status until all other threads are gone.
3144 - There are 3 or more threads in the group, and a thread
3145 other than the leader exec'd. See comments on exec
3146 events at the top of the file. We could try
3147 distinguishing the exit and exec cases, by waiting once
3148 more, and seeing if something comes out, but it doesn't
3149 sound useful. The previous leader _does_ go away, and
3150 we'll re-add the new one once we see the exec event
3151 (which is just the same as what would happen if the
3152 previous leader did exit voluntarily before some other
3155 linux_nat_debug_printf ("Thread group leader %d vanished.", inf
->pid
);
3156 exit_lwp (leader_lp
);
3161 /* Convenience function that is called when the kernel reports an exit
3162 event. This decides whether to report the event to GDB as a
3163 process exit event, a thread exit event, or to suppress the
3167 filter_exit_event (struct lwp_info
*event_child
,
3168 struct target_waitstatus
*ourstatus
)
3170 ptid_t ptid
= event_child
->ptid
;
3172 if (num_lwps (ptid
.pid ()) > 1)
3174 if (report_thread_events
)
3175 ourstatus
->kind
= TARGET_WAITKIND_THREAD_EXITED
;
3177 ourstatus
->kind
= TARGET_WAITKIND_IGNORE
;
3179 exit_lwp (event_child
);
3186 linux_nat_wait_1 (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3187 target_wait_flags target_options
)
3190 enum resume_kind last_resume_kind
;
3191 struct lwp_info
*lp
;
3194 linux_nat_debug_printf ("enter");
3196 /* The first time we get here after starting a new inferior, we may
3197 not have added it to the LWP list yet - this is the earliest
3198 moment at which we know its PID. */
3199 if (ptid
.is_pid () && find_lwp_pid (ptid
) == nullptr)
3201 ptid_t
lwp_ptid (ptid
.pid (), ptid
.pid ());
3203 /* Upgrade the main thread's ptid. */
3204 thread_change_ptid (linux_target
, ptid
, lwp_ptid
);
3205 lp
= add_initial_lwp (lwp_ptid
);
3209 /* Make sure SIGCHLD is blocked until the sigsuspend below. */
3210 block_child_signals (&prev_mask
);
3212 /* First check if there is a LWP with a wait status pending. */
3213 lp
= iterate_over_lwps (ptid
, status_callback
);
3216 linux_nat_debug_printf ("Using pending wait status %s for %s.",
3217 status_to_str (lp
->status
).c_str (),
3218 target_pid_to_str (lp
->ptid
).c_str ());
3221 /* But if we don't find a pending event, we'll have to wait. Always
3222 pull all events out of the kernel. We'll randomly select an
3223 event LWP out of all that have events, to prevent starvation. */
3229 /* Always use -1 and WNOHANG, due to couple of a kernel/ptrace
3232 - If the thread group leader exits while other threads in the
3233 thread group still exist, waitpid(TGID, ...) hangs. That
3234 waitpid won't return an exit status until the other threads
3235 in the group are reaped.
3237 - When a non-leader thread execs, that thread just vanishes
3238 without reporting an exit (so we'd hang if we waited for it
3239 explicitly in that case). The exec event is reported to
3243 lwpid
= my_waitpid (-1, &status
, __WALL
| WNOHANG
);
3245 linux_nat_debug_printf ("waitpid(-1, ...) returned %d, %s",
3247 errno
? safe_strerror (errno
) : "ERRNO-OK");
3251 linux_nat_debug_printf ("waitpid %ld received %s",
3253 status_to_str (status
).c_str ());
3255 linux_nat_filter_event (lwpid
, status
);
3256 /* Retry until nothing comes out of waitpid. A single
3257 SIGCHLD can indicate more than one child stopped. */
3261 /* Now that we've pulled all events out of the kernel, resume
3262 LWPs that don't have an interesting event to report. */
3263 iterate_over_lwps (minus_one_ptid
,
3264 [] (struct lwp_info
*info
)
3266 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
3269 /* ... and find an LWP with a status to report to the core, if
3271 lp
= iterate_over_lwps (ptid
, status_callback
);
3275 /* Check for zombie thread group leaders. Those can't be reaped
3276 until all other threads in the thread group are. */
3277 check_zombie_leaders ();
3279 /* If there are no resumed children left, bail. We'd be stuck
3280 forever in the sigsuspend call below otherwise. */
3281 if (iterate_over_lwps (ptid
, resumed_callback
) == NULL
)
3283 linux_nat_debug_printf ("exit (no resumed LWP)");
3285 ourstatus
->kind
= TARGET_WAITKIND_NO_RESUMED
;
3287 restore_child_signals_mask (&prev_mask
);
3288 return minus_one_ptid
;
3291 /* No interesting event to report to the core. */
3293 if (target_options
& TARGET_WNOHANG
)
3295 linux_nat_debug_printf ("exit (ignore)");
3297 ourstatus
->kind
= TARGET_WAITKIND_IGNORE
;
3298 restore_child_signals_mask (&prev_mask
);
3299 return minus_one_ptid
;
3302 /* We shouldn't end up here unless we want to try again. */
3303 gdb_assert (lp
== NULL
);
3305 /* Block until we get an event reported with SIGCHLD. */
3311 status
= lp
->status
;
3314 if (!target_is_non_stop_p ())
3316 /* Now stop all other LWP's ... */
3317 iterate_over_lwps (minus_one_ptid
, stop_callback
);
3319 /* ... and wait until all of them have reported back that
3320 they're no longer running. */
3321 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
3324 /* If we're not waiting for a specific LWP, choose an event LWP from
3325 among those that have had events. Giving equal priority to all
3326 LWPs that have had events helps prevent starvation. */
3327 if (ptid
== minus_one_ptid
|| ptid
.is_pid ())
3328 select_event_lwp (ptid
, &lp
, &status
);
3330 gdb_assert (lp
!= NULL
);
3332 /* Now that we've selected our final event LWP, un-adjust its PC if
3333 it was a software breakpoint, and we can't reliably support the
3334 "stopped by software breakpoint" stop reason. */
3335 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
3336 && !USE_SIGTRAP_SIGINFO
)
3338 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3339 struct gdbarch
*gdbarch
= regcache
->arch ();
3340 int decr_pc
= gdbarch_decr_pc_after_break (gdbarch
);
3346 pc
= regcache_read_pc (regcache
);
3347 regcache_write_pc (regcache
, pc
+ decr_pc
);
3351 /* We'll need this to determine whether to report a SIGSTOP as
3352 GDB_SIGNAL_0. Need to take a copy because resume_clear_callback
3354 last_resume_kind
= lp
->last_resume_kind
;
3356 if (!target_is_non_stop_p ())
3358 /* In all-stop, from the core's perspective, all LWPs are now
3359 stopped until a new resume action is sent over. */
3360 iterate_over_lwps (minus_one_ptid
, resume_clear_callback
);
3364 resume_clear_callback (lp
);
3367 if (linux_target
->low_status_is_event (status
))
3369 linux_nat_debug_printf ("trap ptid is %s.",
3370 target_pid_to_str (lp
->ptid
).c_str ());
3373 if (lp
->waitstatus
.kind
!= TARGET_WAITKIND_IGNORE
)
3375 *ourstatus
= lp
->waitstatus
;
3376 lp
->waitstatus
.kind
= TARGET_WAITKIND_IGNORE
;
3379 store_waitstatus (ourstatus
, status
);
3381 linux_nat_debug_printf ("exit");
3383 restore_child_signals_mask (&prev_mask
);
3385 if (last_resume_kind
== resume_stop
3386 && ourstatus
->kind
== TARGET_WAITKIND_STOPPED
3387 && WSTOPSIG (status
) == SIGSTOP
)
3389 /* A thread that has been requested to stop by GDB with
3390 target_stop, and it stopped cleanly, so report as SIG0. The
3391 use of SIGSTOP is an implementation detail. */
3392 ourstatus
->value
.sig
= GDB_SIGNAL_0
;
3395 if (ourstatus
->kind
== TARGET_WAITKIND_EXITED
3396 || ourstatus
->kind
== TARGET_WAITKIND_SIGNALLED
)
3399 lp
->core
= linux_common_core_of_thread (lp
->ptid
);
3401 if (ourstatus
->kind
== TARGET_WAITKIND_EXITED
)
3402 return filter_exit_event (lp
, ourstatus
);
3407 /* Resume LWPs that are currently stopped without any pending status
3408 to report, but are resumed from the core's perspective. */
3411 resume_stopped_resumed_lwps (struct lwp_info
*lp
, const ptid_t wait_ptid
)
3415 linux_nat_debug_printf ("NOT resuming LWP %s, not stopped",
3416 target_pid_to_str (lp
->ptid
).c_str ());
3418 else if (!lp
->resumed
)
3420 linux_nat_debug_printf ("NOT resuming LWP %s, not resumed",
3421 target_pid_to_str (lp
->ptid
).c_str ());
3423 else if (lwp_status_pending_p (lp
))
3425 linux_nat_debug_printf ("NOT resuming LWP %s, has pending status",
3426 target_pid_to_str (lp
->ptid
).c_str ());
3430 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3431 struct gdbarch
*gdbarch
= regcache
->arch ();
3435 CORE_ADDR pc
= regcache_read_pc (regcache
);
3436 int leave_stopped
= 0;
3438 /* Don't bother if there's a breakpoint at PC that we'd hit
3439 immediately, and we're not waiting for this LWP. */
3440 if (!lp
->ptid
.matches (wait_ptid
))
3442 if (breakpoint_inserted_here_p (regcache
->aspace (), pc
))
3448 linux_nat_debug_printf
3449 ("resuming stopped-resumed LWP %s at %s: step=%d",
3450 target_pid_to_str (lp
->ptid
).c_str (), paddress (gdbarch
, pc
),
3453 linux_resume_one_lwp_throw (lp
, lp
->step
, GDB_SIGNAL_0
);
3456 catch (const gdb_exception_error
&ex
)
3458 if (!check_ptrace_stopped_lwp_gone (lp
))
3467 linux_nat_target::wait (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3468 target_wait_flags target_options
)
3472 linux_nat_debug_printf ("[%s], [%s]", target_pid_to_str (ptid
).c_str (),
3473 target_options_to_string (target_options
).c_str ());
3475 /* Flush the async file first. */
3476 if (target_is_async_p ())
3477 async_file_flush ();
3479 /* Resume LWPs that are currently stopped without any pending status
3480 to report, but are resumed from the core's perspective. LWPs get
3481 in this state if we find them stopping at a time we're not
3482 interested in reporting the event (target_wait on a
3483 specific_process, for example, see linux_nat_wait_1), and
3484 meanwhile the event became uninteresting. Don't bother resuming
3485 LWPs we're not going to wait for if they'd stop immediately. */
3486 if (target_is_non_stop_p ())
3487 iterate_over_lwps (minus_one_ptid
,
3488 [=] (struct lwp_info
*info
)
3490 return resume_stopped_resumed_lwps (info
, ptid
);
3493 event_ptid
= linux_nat_wait_1 (ptid
, ourstatus
, target_options
);
3495 /* If we requested any event, and something came out, assume there
3496 may be more. If we requested a specific lwp or process, also
3497 assume there may be more. */
3498 if (target_is_async_p ()
3499 && ((ourstatus
->kind
!= TARGET_WAITKIND_IGNORE
3500 && ourstatus
->kind
!= TARGET_WAITKIND_NO_RESUMED
)
3501 || ptid
!= minus_one_ptid
))
3510 kill_one_lwp (pid_t pid
)
3512 /* PTRACE_KILL may resume the inferior. Send SIGKILL first. */
3515 kill_lwp (pid
, SIGKILL
);
3517 if (debug_linux_nat
)
3519 int save_errno
= errno
;
3521 linux_nat_debug_printf
3522 ("kill (SIGKILL) %ld, 0, 0 (%s)", (long) pid
,
3523 save_errno
!= 0 ? safe_strerror (save_errno
) : "OK");
3526 /* Some kernels ignore even SIGKILL for processes under ptrace. */
3529 ptrace (PTRACE_KILL
, pid
, 0, 0);
3530 if (debug_linux_nat
)
3532 int save_errno
= errno
;
3534 linux_nat_debug_printf
3535 ("PTRACE_KILL %ld, 0, 0 (%s)", (long) pid
,
3536 save_errno
? safe_strerror (save_errno
) : "OK");
3540 /* Wait for an LWP to die. */
3543 kill_wait_one_lwp (pid_t pid
)
3547 /* We must make sure that there are no pending events (delayed
3548 SIGSTOPs, pending SIGTRAPs, etc.) to make sure the current
3549 program doesn't interfere with any following debugging session. */
3553 res
= my_waitpid (pid
, NULL
, __WALL
);
3554 if (res
!= (pid_t
) -1)
3556 linux_nat_debug_printf ("wait %ld received unknown.", (long) pid
);
3558 /* The Linux kernel sometimes fails to kill a thread
3559 completely after PTRACE_KILL; that goes from the stop
3560 point in do_fork out to the one in get_signal_to_deliver
3561 and waits again. So kill it again. */
3567 gdb_assert (res
== -1 && errno
== ECHILD
);
3570 /* Callback for iterate_over_lwps. */
3573 kill_callback (struct lwp_info
*lp
)
3575 kill_one_lwp (lp
->ptid
.lwp ());
3579 /* Callback for iterate_over_lwps. */
3582 kill_wait_callback (struct lwp_info
*lp
)
3584 kill_wait_one_lwp (lp
->ptid
.lwp ());
3588 /* Kill the fork children of any threads of inferior INF that are
3589 stopped at a fork event. */
3592 kill_unfollowed_fork_children (struct inferior
*inf
)
3594 for (thread_info
*thread
: inf
->non_exited_threads ())
3596 struct target_waitstatus
*ws
= &thread
->pending_follow
;
3598 if (ws
->kind
== TARGET_WAITKIND_FORKED
3599 || ws
->kind
== TARGET_WAITKIND_VFORKED
)
3601 ptid_t child_ptid
= ws
->value
.related_pid
;
3602 int child_pid
= child_ptid
.pid ();
3603 int child_lwp
= child_ptid
.lwp ();
3605 kill_one_lwp (child_lwp
);
3606 kill_wait_one_lwp (child_lwp
);
3608 /* Let the arch-specific native code know this process is
3610 linux_target
->low_forget_process (child_pid
);
3616 linux_nat_target::kill ()
3618 /* If we're stopped while forking and we haven't followed yet,
3619 kill the other task. We need to do this first because the
3620 parent will be sleeping if this is a vfork. */
3621 kill_unfollowed_fork_children (current_inferior ());
3623 if (forks_exist_p ())
3624 linux_fork_killall ();
3627 ptid_t ptid
= ptid_t (inferior_ptid
.pid ());
3629 /* Stop all threads before killing them, since ptrace requires
3630 that the thread is stopped to successfully PTRACE_KILL. */
3631 iterate_over_lwps (ptid
, stop_callback
);
3632 /* ... and wait until all of them have reported back that
3633 they're no longer running. */
3634 iterate_over_lwps (ptid
, stop_wait_callback
);
3636 /* Kill all LWP's ... */
3637 iterate_over_lwps (ptid
, kill_callback
);
3639 /* ... and wait until we've flushed all events. */
3640 iterate_over_lwps (ptid
, kill_wait_callback
);
3643 target_mourn_inferior (inferior_ptid
);
3647 linux_nat_target::mourn_inferior ()
3649 int pid
= inferior_ptid
.pid ();
3651 purge_lwp_list (pid
);
3653 /* Close the /proc/<pid>/mem file if it was open for this
3655 maybe_close_proc_mem_file (pid
);
3657 if (! forks_exist_p ())
3658 /* Normal case, no other forks available. */
3659 inf_ptrace_target::mourn_inferior ();
3661 /* Multi-fork case. The current inferior_ptid has exited, but
3662 there are other viable forks to debug. Delete the exiting
3663 one and context-switch to the first available. */
3664 linux_fork_mourn_inferior ();
3666 /* Let the arch-specific native code know this process is gone. */
3667 linux_target
->low_forget_process (pid
);
3670 /* Convert a native/host siginfo object, into/from the siginfo in the
3671 layout of the inferiors' architecture. */
3674 siginfo_fixup (siginfo_t
*siginfo
, gdb_byte
*inf_siginfo
, int direction
)
3676 /* If the low target didn't do anything, then just do a straight
3678 if (!linux_target
->low_siginfo_fixup (siginfo
, inf_siginfo
, direction
))
3681 memcpy (siginfo
, inf_siginfo
, sizeof (siginfo_t
));
3683 memcpy (inf_siginfo
, siginfo
, sizeof (siginfo_t
));
3687 static enum target_xfer_status
3688 linux_xfer_siginfo (enum target_object object
,
3689 const char *annex
, gdb_byte
*readbuf
,
3690 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3691 ULONGEST
*xfered_len
)
3695 gdb_byte inf_siginfo
[sizeof (siginfo_t
)];
3697 gdb_assert (object
== TARGET_OBJECT_SIGNAL_INFO
);
3698 gdb_assert (readbuf
|| writebuf
);
3700 pid
= inferior_ptid
.lwp ();
3702 pid
= inferior_ptid
.pid ();
3704 if (offset
> sizeof (siginfo
))
3705 return TARGET_XFER_E_IO
;
3708 ptrace (PTRACE_GETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, &siginfo
);
3710 return TARGET_XFER_E_IO
;
3712 /* When GDB is built as a 64-bit application, ptrace writes into
3713 SIGINFO an object with 64-bit layout. Since debugging a 32-bit
3714 inferior with a 64-bit GDB should look the same as debugging it
3715 with a 32-bit GDB, we need to convert it. GDB core always sees
3716 the converted layout, so any read/write will have to be done
3718 siginfo_fixup (&siginfo
, inf_siginfo
, 0);
3720 if (offset
+ len
> sizeof (siginfo
))
3721 len
= sizeof (siginfo
) - offset
;
3723 if (readbuf
!= NULL
)
3724 memcpy (readbuf
, inf_siginfo
+ offset
, len
);
3727 memcpy (inf_siginfo
+ offset
, writebuf
, len
);
3729 /* Convert back to ptrace layout before flushing it out. */
3730 siginfo_fixup (&siginfo
, inf_siginfo
, 1);
3733 ptrace (PTRACE_SETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, &siginfo
);
3735 return TARGET_XFER_E_IO
;
3739 return TARGET_XFER_OK
;
3742 static enum target_xfer_status
3743 linux_nat_xfer_osdata (enum target_object object
,
3744 const char *annex
, gdb_byte
*readbuf
,
3745 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3746 ULONGEST
*xfered_len
);
3748 static enum target_xfer_status
3749 linux_proc_xfer_memory_partial (gdb_byte
*readbuf
, const gdb_byte
*writebuf
,
3750 ULONGEST offset
, LONGEST len
, ULONGEST
*xfered_len
);
3752 enum target_xfer_status
3753 linux_nat_target::xfer_partial (enum target_object object
,
3754 const char *annex
, gdb_byte
*readbuf
,
3755 const gdb_byte
*writebuf
,
3756 ULONGEST offset
, ULONGEST len
, ULONGEST
*xfered_len
)
3758 if (object
== TARGET_OBJECT_SIGNAL_INFO
)
3759 return linux_xfer_siginfo (object
, annex
, readbuf
, writebuf
,
3760 offset
, len
, xfered_len
);
3762 /* The target is connected but no live inferior is selected. Pass
3763 this request down to a lower stratum (e.g., the executable
3765 if (object
== TARGET_OBJECT_MEMORY
&& inferior_ptid
== null_ptid
)
3766 return TARGET_XFER_EOF
;
3768 if (object
== TARGET_OBJECT_AUXV
)
3769 return memory_xfer_auxv (this, object
, annex
, readbuf
, writebuf
,
3770 offset
, len
, xfered_len
);
3772 if (object
== TARGET_OBJECT_OSDATA
)
3773 return linux_nat_xfer_osdata (object
, annex
, readbuf
, writebuf
,
3774 offset
, len
, xfered_len
);
3776 if (object
== TARGET_OBJECT_MEMORY
)
3778 /* GDB calculates all addresses in the largest possible address
3779 width. The address width must be masked before its final use
3780 by linux_proc_xfer_partial.
3782 Compare ADDR_BIT first to avoid a compiler warning on shift overflow. */
3783 int addr_bit
= gdbarch_addr_bit (target_gdbarch ());
3785 if (addr_bit
< (sizeof (ULONGEST
) * HOST_CHAR_BIT
))
3786 offset
&= ((ULONGEST
) 1 << addr_bit
) - 1;
3788 return linux_proc_xfer_memory_partial (readbuf
, writebuf
,
3789 offset
, len
, xfered_len
);
3792 return inf_ptrace_target::xfer_partial (object
, annex
, readbuf
, writebuf
,
3793 offset
, len
, xfered_len
);
3797 linux_nat_target::thread_alive (ptid_t ptid
)
3799 /* As long as a PTID is in lwp list, consider it alive. */
3800 return find_lwp_pid (ptid
) != NULL
;
3803 /* Implement the to_update_thread_list target method for this
3807 linux_nat_target::update_thread_list ()
3809 struct lwp_info
*lwp
;
3811 /* We add/delete threads from the list as clone/exit events are
3812 processed, so just try deleting exited threads still in the
3814 delete_exited_threads ();
3816 /* Update the processor core that each lwp/thread was last seen
3820 /* Avoid accessing /proc if the thread hasn't run since we last
3821 time we fetched the thread's core. Accessing /proc becomes
3822 noticeably expensive when we have thousands of LWPs. */
3823 if (lwp
->core
== -1)
3824 lwp
->core
= linux_common_core_of_thread (lwp
->ptid
);
3829 linux_nat_target::pid_to_str (ptid_t ptid
)
3832 && (ptid
.pid () != ptid
.lwp ()
3833 || num_lwps (ptid
.pid ()) > 1))
3834 return string_printf ("LWP %ld", ptid
.lwp ());
3836 return normal_pid_to_str (ptid
);
3840 linux_nat_target::thread_name (struct thread_info
*thr
)
3842 return linux_proc_tid_get_name (thr
->ptid
);
3845 /* Accepts an integer PID; Returns a string representing a file that
3846 can be opened to get the symbols for the child process. */
3849 linux_nat_target::pid_to_exec_file (int pid
)
3851 return linux_proc_pid_to_exec_file (pid
);
3854 /* Keep the /proc/<pid>/mem file open between memory accesses, as a
3855 cache to avoid constantly closing/opening the file in the common
3856 case of multiple memory reads/writes from/to the same inferior.
3857 Note we don't keep a file open per inferior to avoid keeping too
3858 many file descriptors open, which can run into resource limits. */
3861 /* The LWP this open file is for. Note that after opening the file,
3862 even if the thread subsequently exits, the open file is still
3863 usable for accessing memory. It's only when the whole process
3864 exits or execs that the file becomes invalid (at which point
3865 reads/writes return EOF). */
3868 /* The file descriptor. -1 if file is not open. */
3871 /* Close FD and clear it to -1. */
3874 linux_nat_debug_printf ("closing fd %d for /proc/%d/task/%ld/mem\n",
3875 fd
, ptid
.pid (), ptid
.lwp ());
3879 } last_proc_mem_file
;
3881 /* Close the /proc/<pid>/mem file if its LWP matches PTID. */
3884 maybe_close_proc_mem_file (pid_t pid
)
3886 if (last_proc_mem_file
.ptid
.pid () == pid
)
3887 last_proc_mem_file
.close ();
3890 /* Helper for linux_proc_xfer_memory_partial. Accesses /proc via
3891 PTID. Returns -1 on error, with errno set. Returns number of
3892 read/written bytes otherwise. Returns 0 on EOF, which indicates
3893 the address space is gone (because the process exited or
3897 linux_proc_xfer_memory_partial_pid (ptid_t ptid
,
3898 gdb_byte
*readbuf
, const gdb_byte
*writebuf
,
3899 ULONGEST offset
, LONGEST len
)
3903 /* As long as we're hitting the same inferior, the previously open
3904 file is good, even if the thread it was open for exits. */
3905 if (last_proc_mem_file
.fd
!= -1
3906 && last_proc_mem_file
.ptid
.pid () != ptid
.pid ())
3907 last_proc_mem_file
.close ();
3909 if (last_proc_mem_file
.fd
== -1)
3911 /* Actually use /proc/<pid>/task/<lwp>/mem instead of
3912 /proc/<lwp>/mem to avoid PID-reuse races, as we may be trying
3913 to read memory via a thread which we've already reaped.
3914 /proc/<lwp>/mem could open a file for the wrong process. If
3915 the LWPID is reused for the same process it's OK, we can read
3916 memory through it just fine. If the LWPID is reused for a
3917 different process, then the open will fail because the path
3920 xsnprintf (filename
, sizeof filename
,
3921 "/proc/%d/task/%ld/mem", ptid
.pid (), ptid
.lwp ());
3923 last_proc_mem_file
.fd
3924 = gdb_open_cloexec (filename
, O_RDWR
| O_LARGEFILE
, 0);
3926 if (last_proc_mem_file
.fd
== -1)
3928 linux_nat_debug_printf ("opening %s failed: %s (%d)\n",
3929 filename
, safe_strerror (errno
), errno
);
3932 last_proc_mem_file
.ptid
= ptid
;
3934 linux_nat_debug_printf ("opened fd %d for %s\n",
3935 last_proc_mem_file
.fd
, filename
);
3938 int fd
= last_proc_mem_file
.fd
;
3940 /* Use pread64/pwrite64 if available, since they save a syscall and can
3941 handle 64-bit offsets even on 32-bit platforms (for instance, SPARC
3942 debugging a SPARC64 application). */
3944 ret
= (readbuf
? pread64 (fd
, readbuf
, len
, offset
)
3945 : pwrite64 (fd
, writebuf
, len
, offset
));
3947 ret
= lseek (fd
, offset
, SEEK_SET
);
3949 ret
= (readbuf
? read (fd
, readbuf
, len
)
3950 : write (fd
, writebuf
, len
));
3955 linux_nat_debug_printf ("accessing fd %d for pid %ld failed: %s (%d)\n",
3957 safe_strerror (errno
), errno
);
3961 linux_nat_debug_printf ("accessing fd %d for pid %ld got EOF\n",
3968 /* Implement the to_xfer_partial target method using /proc/<pid>/mem.
3969 Because we can use a single read/write call, this can be much more
3970 efficient than banging away at PTRACE_PEEKTEXT. Also, unlike
3971 PTRACE_PEEKTEXT/PTRACE_POKETEXT, this works with running
3974 static enum target_xfer_status
3975 linux_proc_xfer_memory_partial (gdb_byte
*readbuf
, const gdb_byte
*writebuf
,
3976 ULONGEST offset
, LONGEST len
,
3977 ULONGEST
*xfered_len
)
3979 /* Unlike PTRACE_PEEKTEXT/PTRACE_POKETEXT, reading/writing from/to
3980 /proc/<pid>/mem works with running threads, and even exited
3981 threads if the file was already open. If we need to open or
3982 reopen the /proc file though, we may get an EACCES error
3983 ("Permission denied"), meaning the thread is gone but its exit
3984 status isn't reaped yet, or ENOENT if the thread is gone and
3985 already reaped. In that case, just try opening the file for
3986 another thread in the process. If all threads fail, then it must
3987 mean the whole process exited, in which case there's nothing else
3988 to do and we just fail the memory access.
3990 Note we don't simply always access via the leader thread because
3991 the leader may exit without exiting the whole process. See
3992 gdb.threads/leader-exit.exp, for example. */
3994 /* It's frequently the case that the selected thread is stopped, and
3995 is thus not likely to exit (unless something kills the process
3996 outside our control, with e.g., SIGKILL). Give that one a try
3999 Also, inferior_ptid may actually point at an LWP not in lwp_list.
4000 This happens when we're detaching from a fork child that we don't
4001 want to debug ("set detach-on-fork on"), and the breakpoints
4002 module uninstalls breakpoints from the fork child. Which process
4003 to access is given by inferior_ptid. */
4004 int res
= linux_proc_xfer_memory_partial_pid (inferior_ptid
,
4009 /* EOF means the address space is gone, the whole
4010 process exited or execed. */
4011 return TARGET_XFER_EOF
;
4016 return TARGET_XFER_OK
;
4020 /* If we simply raced with the thread exiting (EACCES), or the
4021 current thread is THREAD_EXITED (ENOENT), try some other
4022 thread. It's easier to handle an ENOENT failure than check
4023 for THREAD_EXIT upfront because this function is called
4024 before a thread for inferior_ptid is added to the thread
4026 if (errno
!= EACCES
&& errno
!= ENOENT
)
4027 return TARGET_XFER_EOF
;
4030 int cur_pid
= current_inferior ()->pid
;
4032 if (inferior_ptid
.pid () != cur_pid
)
4034 /* We're accessing a fork child, and the access above failed.
4035 Don't bother iterating the LWP list, since there's no other
4036 LWP for this process. */
4037 return TARGET_XFER_EOF
;
4040 /* Iterate over LWPs of the current inferior, trying to access
4041 memory through one of them. */
4042 for (lwp_info
*lp
= lwp_list
; lp
!= nullptr; lp
= lp
->next
)
4044 if (lp
->ptid
.pid () != cur_pid
)
4047 res
= linux_proc_xfer_memory_partial_pid (lp
->ptid
,
4053 /* EOF means the address space is gone, the whole process
4054 exited or execed. */
4055 return TARGET_XFER_EOF
;
4059 if (errno
== EACCES
)
4061 /* This LWP is gone, try another one. */
4065 return TARGET_XFER_EOF
;
4069 return TARGET_XFER_OK
;
4073 return TARGET_XFER_EOF
;
4076 /* Parse LINE as a signal set and add its set bits to SIGS. */
4079 add_line_to_sigset (const char *line
, sigset_t
*sigs
)
4081 int len
= strlen (line
) - 1;
4085 if (line
[len
] != '\n')
4086 error (_("Could not parse signal set: %s"), line
);
4094 if (*p
>= '0' && *p
<= '9')
4096 else if (*p
>= 'a' && *p
<= 'f')
4097 digit
= *p
- 'a' + 10;
4099 error (_("Could not parse signal set: %s"), line
);
4104 sigaddset (sigs
, signum
+ 1);
4106 sigaddset (sigs
, signum
+ 2);
4108 sigaddset (sigs
, signum
+ 3);
4110 sigaddset (sigs
, signum
+ 4);
4116 /* Find process PID's pending signals from /proc/pid/status and set
4120 linux_proc_pending_signals (int pid
, sigset_t
*pending
,
4121 sigset_t
*blocked
, sigset_t
*ignored
)
4123 char buffer
[PATH_MAX
], fname
[PATH_MAX
];
4125 sigemptyset (pending
);
4126 sigemptyset (blocked
);
4127 sigemptyset (ignored
);
4128 xsnprintf (fname
, sizeof fname
, "/proc/%d/status", pid
);
4129 gdb_file_up procfile
= gdb_fopen_cloexec (fname
, "r");
4130 if (procfile
== NULL
)
4131 error (_("Could not open %s"), fname
);
4133 while (fgets (buffer
, PATH_MAX
, procfile
.get ()) != NULL
)
4135 /* Normal queued signals are on the SigPnd line in the status
4136 file. However, 2.6 kernels also have a "shared" pending
4137 queue for delivering signals to a thread group, so check for
4140 Unfortunately some Red Hat kernels include the shared pending
4141 queue but not the ShdPnd status field. */
4143 if (startswith (buffer
, "SigPnd:\t"))
4144 add_line_to_sigset (buffer
+ 8, pending
);
4145 else if (startswith (buffer
, "ShdPnd:\t"))
4146 add_line_to_sigset (buffer
+ 8, pending
);
4147 else if (startswith (buffer
, "SigBlk:\t"))
4148 add_line_to_sigset (buffer
+ 8, blocked
);
4149 else if (startswith (buffer
, "SigIgn:\t"))
4150 add_line_to_sigset (buffer
+ 8, ignored
);
4154 static enum target_xfer_status
4155 linux_nat_xfer_osdata (enum target_object object
,
4156 const char *annex
, gdb_byte
*readbuf
,
4157 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
4158 ULONGEST
*xfered_len
)
4160 gdb_assert (object
== TARGET_OBJECT_OSDATA
);
4162 *xfered_len
= linux_common_xfer_osdata (annex
, readbuf
, offset
, len
);
4163 if (*xfered_len
== 0)
4164 return TARGET_XFER_EOF
;
4166 return TARGET_XFER_OK
;
4169 std::vector
<static_tracepoint_marker
>
4170 linux_nat_target::static_tracepoint_markers_by_strid (const char *strid
)
4172 char s
[IPA_CMD_BUF_SIZE
];
4173 int pid
= inferior_ptid
.pid ();
4174 std::vector
<static_tracepoint_marker
> markers
;
4176 ptid_t ptid
= ptid_t (pid
, 0, 0);
4177 static_tracepoint_marker marker
;
4182 memcpy (s
, "qTfSTM", sizeof ("qTfSTM"));
4183 s
[sizeof ("qTfSTM")] = 0;
4185 agent_run_command (pid
, s
, strlen (s
) + 1);
4188 SCOPE_EXIT
{ target_continue_no_signal (ptid
); };
4194 parse_static_tracepoint_marker_definition (p
, &p
, &marker
);
4196 if (strid
== NULL
|| marker
.str_id
== strid
)
4197 markers
.push_back (std::move (marker
));
4199 while (*p
++ == ','); /* comma-separated list */
4201 memcpy (s
, "qTsSTM", sizeof ("qTsSTM"));
4202 s
[sizeof ("qTsSTM")] = 0;
4203 agent_run_command (pid
, s
, strlen (s
) + 1);
4210 /* target_is_async_p implementation. */
4213 linux_nat_target::is_async_p ()
4215 return linux_is_async_p ();
4218 /* target_can_async_p implementation. */
4221 linux_nat_target::can_async_p ()
4223 /* We're always async, unless the user explicitly prevented it with the
4224 "maint set target-async" command. */
4225 return target_async_permitted
;
4229 linux_nat_target::supports_non_stop ()
4234 /* to_always_non_stop_p implementation. */
4237 linux_nat_target::always_non_stop_p ()
4243 linux_nat_target::supports_multi_process ()
4249 linux_nat_target::supports_disable_randomization ()
4254 /* SIGCHLD handler that serves two purposes: In non-stop/async mode,
4255 so we notice when any child changes state, and notify the
4256 event-loop; it allows us to use sigsuspend in linux_nat_wait_1
4257 above to wait for the arrival of a SIGCHLD. */
4260 sigchld_handler (int signo
)
4262 int old_errno
= errno
;
4264 if (debug_linux_nat
)
4265 gdb_stdlog
->write_async_safe ("sigchld\n", sizeof ("sigchld\n") - 1);
4267 if (signo
== SIGCHLD
4268 && linux_nat_event_pipe
[0] != -1)
4269 async_file_mark (); /* Let the event loop know that there are
4270 events to handle. */
4275 /* Callback registered with the target events file descriptor. */
4278 handle_target_event (int error
, gdb_client_data client_data
)
4280 inferior_event_handler (INF_REG_EVENT
);
4283 /* Create/destroy the target events pipe. Returns previous state. */
4286 linux_async_pipe (int enable
)
4288 int previous
= linux_is_async_p ();
4290 if (previous
!= enable
)
4294 /* Block child signals while we create/destroy the pipe, as
4295 their handler writes to it. */
4296 block_child_signals (&prev_mask
);
4300 if (gdb_pipe_cloexec (linux_nat_event_pipe
) == -1)
4301 internal_error (__FILE__
, __LINE__
,
4302 "creating event pipe failed.");
4304 fcntl (linux_nat_event_pipe
[0], F_SETFL
, O_NONBLOCK
);
4305 fcntl (linux_nat_event_pipe
[1], F_SETFL
, O_NONBLOCK
);
4309 close (linux_nat_event_pipe
[0]);
4310 close (linux_nat_event_pipe
[1]);
4311 linux_nat_event_pipe
[0] = -1;
4312 linux_nat_event_pipe
[1] = -1;
4315 restore_child_signals_mask (&prev_mask
);
4322 linux_nat_target::async_wait_fd ()
4324 return linux_nat_event_pipe
[0];
4327 /* target_async implementation. */
4330 linux_nat_target::async (int enable
)
4334 if (!linux_async_pipe (1))
4336 add_file_handler (linux_nat_event_pipe
[0],
4337 handle_target_event
, NULL
,
4339 /* There may be pending events to handle. Tell the event loop
4346 delete_file_handler (linux_nat_event_pipe
[0]);
4347 linux_async_pipe (0);
4352 /* Stop an LWP, and push a GDB_SIGNAL_0 stop status if no other
4356 linux_nat_stop_lwp (struct lwp_info
*lwp
)
4360 linux_nat_debug_printf ("running -> suspending %s",
4361 target_pid_to_str (lwp
->ptid
).c_str ());
4364 if (lwp
->last_resume_kind
== resume_stop
)
4366 linux_nat_debug_printf ("already stopping LWP %ld at GDB's request",
4371 stop_callback (lwp
);
4372 lwp
->last_resume_kind
= resume_stop
;
4376 /* Already known to be stopped; do nothing. */
4378 if (debug_linux_nat
)
4380 if (find_thread_ptid (linux_target
, lwp
->ptid
)->stop_requested
)
4381 linux_nat_debug_printf ("already stopped/stop_requested %s",
4382 target_pid_to_str (lwp
->ptid
).c_str ());
4384 linux_nat_debug_printf ("already stopped/no stop_requested yet %s",
4385 target_pid_to_str (lwp
->ptid
).c_str ());
4392 linux_nat_target::stop (ptid_t ptid
)
4394 iterate_over_lwps (ptid
, linux_nat_stop_lwp
);
4398 linux_nat_target::close ()
4400 /* Unregister from the event loop. */
4404 inf_ptrace_target::close ();
4407 /* When requests are passed down from the linux-nat layer to the
4408 single threaded inf-ptrace layer, ptids of (lwpid,0,0) form are
4409 used. The address space pointer is stored in the inferior object,
4410 but the common code that is passed such ptid can't tell whether
4411 lwpid is a "main" process id or not (it assumes so). We reverse
4412 look up the "main" process id from the lwp here. */
4414 struct address_space
*
4415 linux_nat_target::thread_address_space (ptid_t ptid
)
4417 struct lwp_info
*lwp
;
4418 struct inferior
*inf
;
4421 if (ptid
.lwp () == 0)
4423 /* An (lwpid,0,0) ptid. Look up the lwp object to get at the
4425 lwp
= find_lwp_pid (ptid
);
4426 pid
= lwp
->ptid
.pid ();
4430 /* A (pid,lwpid,0) ptid. */
4434 inf
= find_inferior_pid (this, pid
);
4435 gdb_assert (inf
!= NULL
);
4439 /* Return the cached value of the processor core for thread PTID. */
4442 linux_nat_target::core_of_thread (ptid_t ptid
)
4444 struct lwp_info
*info
= find_lwp_pid (ptid
);
4451 /* Implementation of to_filesystem_is_local. */
4454 linux_nat_target::filesystem_is_local ()
4456 struct inferior
*inf
= current_inferior ();
4458 if (inf
->fake_pid_p
|| inf
->pid
== 0)
4461 return linux_ns_same (inf
->pid
, LINUX_NS_MNT
);
4464 /* Convert the INF argument passed to a to_fileio_* method
4465 to a process ID suitable for passing to its corresponding
4466 linux_mntns_* function. If INF is non-NULL then the
4467 caller is requesting the filesystem seen by INF. If INF
4468 is NULL then the caller is requesting the filesystem seen
4469 by the GDB. We fall back to GDB's filesystem in the case
4470 that INF is non-NULL but its PID is unknown. */
4473 linux_nat_fileio_pid_of (struct inferior
*inf
)
4475 if (inf
== NULL
|| inf
->fake_pid_p
|| inf
->pid
== 0)
4481 /* Implementation of to_fileio_open. */
4484 linux_nat_target::fileio_open (struct inferior
*inf
, const char *filename
,
4485 int flags
, int mode
, int warn_if_slow
,
4492 if (fileio_to_host_openflags (flags
, &nat_flags
) == -1
4493 || fileio_to_host_mode (mode
, &nat_mode
) == -1)
4495 *target_errno
= FILEIO_EINVAL
;
4499 fd
= linux_mntns_open_cloexec (linux_nat_fileio_pid_of (inf
),
4500 filename
, nat_flags
, nat_mode
);
4502 *target_errno
= host_to_fileio_error (errno
);
4507 /* Implementation of to_fileio_readlink. */
4509 gdb::optional
<std::string
>
4510 linux_nat_target::fileio_readlink (struct inferior
*inf
, const char *filename
,
4516 len
= linux_mntns_readlink (linux_nat_fileio_pid_of (inf
),
4517 filename
, buf
, sizeof (buf
));
4520 *target_errno
= host_to_fileio_error (errno
);
4524 return std::string (buf
, len
);
4527 /* Implementation of to_fileio_unlink. */
4530 linux_nat_target::fileio_unlink (struct inferior
*inf
, const char *filename
,
4535 ret
= linux_mntns_unlink (linux_nat_fileio_pid_of (inf
),
4538 *target_errno
= host_to_fileio_error (errno
);
4543 /* Implementation of the to_thread_events method. */
4546 linux_nat_target::thread_events (int enable
)
4548 report_thread_events
= enable
;
4551 linux_nat_target::linux_nat_target ()
4553 /* We don't change the stratum; this target will sit at
4554 process_stratum and thread_db will set at thread_stratum. This
4555 is a little strange, since this is a multi-threaded-capable
4556 target, but we want to be on the stack below thread_db, and we
4557 also want to be used for single-threaded processes. */
4560 /* See linux-nat.h. */
4563 linux_nat_get_siginfo (ptid_t ptid
, siginfo_t
*siginfo
)
4572 ptrace (PTRACE_GETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, siginfo
);
4575 memset (siginfo
, 0, sizeof (*siginfo
));
4581 /* See nat/linux-nat.h. */
4584 current_lwp_ptid (void)
4586 gdb_assert (inferior_ptid
.lwp_p ());
4587 return inferior_ptid
;
4590 void _initialize_linux_nat ();
4592 _initialize_linux_nat ()
4594 add_setshow_zuinteger_cmd ("lin-lwp", class_maintenance
,
4595 &debug_linux_nat
, _("\
4596 Set debugging of GNU/Linux lwp module."), _("\
4597 Show debugging of GNU/Linux lwp module."), _("\
4598 Enables printf debugging output."),
4600 show_debug_linux_nat
,
4601 &setdebuglist
, &showdebuglist
);
4603 add_setshow_boolean_cmd ("linux-namespaces", class_maintenance
,
4604 &debug_linux_namespaces
, _("\
4605 Set debugging of GNU/Linux namespaces module."), _("\
4606 Show debugging of GNU/Linux namespaces module."), _("\
4607 Enables printf debugging output."),
4610 &setdebuglist
, &showdebuglist
);
4612 /* Install a SIGCHLD handler. */
4613 sigchld_action
.sa_handler
= sigchld_handler
;
4614 sigemptyset (&sigchld_action
.sa_mask
);
4615 sigchld_action
.sa_flags
= SA_RESTART
;
4617 /* Make it the default. */
4618 sigaction (SIGCHLD
, &sigchld_action
, NULL
);
4620 /* Make sure we don't block SIGCHLD during a sigsuspend. */
4621 gdb_sigmask (SIG_SETMASK
, NULL
, &suspend_mask
);
4622 sigdelset (&suspend_mask
, SIGCHLD
);
4624 sigemptyset (&blocked_mask
);
4626 lwp_lwpid_htab_create ();
4630 /* FIXME: kettenis/2000-08-26: The stuff on this page is specific to
4631 the GNU/Linux Threads library and therefore doesn't really belong
4634 /* NPTL reserves the first two RT signals, but does not provide any
4635 way for the debugger to query the signal numbers - fortunately
4636 they don't change. */
4637 static int lin_thread_signals
[] = { __SIGRTMIN
, __SIGRTMIN
+ 1 };
4639 /* See linux-nat.h. */
4642 lin_thread_get_thread_signal_num (void)
4644 return sizeof (lin_thread_signals
) / sizeof (lin_thread_signals
[0]);
4647 /* See linux-nat.h. */
4650 lin_thread_get_thread_signal (unsigned int i
)
4652 gdb_assert (i
< lin_thread_get_thread_signal_num ());
4653 return lin_thread_signals
[i
];