1 /* GNU/Linux native-dependent code common to multiple platforms.
3 Copyright (C) 2001-2020 Free Software Foundation, Inc.
5 This file is part of GDB.
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>. */
24 #include "nat/linux-nat.h"
25 #include "nat/linux-waitpid.h"
26 #include "gdbsupport/gdb_wait.h"
28 #include <sys/syscall.h>
29 #include "nat/gdb_ptrace.h"
30 #include "linux-nat.h"
31 #include "nat/linux-ptrace.h"
32 #include "nat/linux-procfs.h"
33 #include "nat/linux-personality.h"
34 #include "linux-fork.h"
35 #include "gdbthread.h"
39 #include "inf-child.h"
40 #include "inf-ptrace.h"
42 #include <sys/procfs.h> /* for elf_gregset etc. */
43 #include "elf-bfd.h" /* for elfcore_write_* */
44 #include "gregset.h" /* for gregset */
45 #include "gdbcore.h" /* for get_exec_file */
46 #include <ctype.h> /* for isdigit */
47 #include <sys/stat.h> /* for struct stat */
48 #include <fcntl.h> /* for O_RDONLY */
50 #include "gdbsupport/event-loop.h"
51 #include "event-top.h"
53 #include <sys/types.h>
55 #include "xml-support.h"
58 #include "nat/linux-osdata.h"
59 #include "linux-tdep.h"
61 #include "gdbsupport/agent.h"
62 #include "tracepoint.h"
63 #include "gdbsupport/buffer.h"
64 #include "target-descriptions.h"
65 #include "gdbsupport/filestuff.h"
67 #include "nat/linux-namespaces.h"
68 #include "gdbsupport/fileio.h"
69 #include "gdbsupport/scope-exit.h"
70 #include "gdbsupport/gdb-sigmask.h"
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 debug statement. Should be used through linux_nat_debug_printf. */
204 static void ATTRIBUTE_PRINTF (2, 3)
205 linux_nat_debug_printf_1 (const char *func_name
, const char *fmt
, ...)
209 debug_prefixed_vprintf ("linux-nat", func_name
, fmt
, ap
);
213 #define linux_nat_debug_printf(fmt, ...) \
216 if (debug_linux_nat) \
217 linux_nat_debug_printf_1 (__func__, fmt, ##__VA_ARGS__); \
221 struct simple_pid_list
225 struct simple_pid_list
*next
;
227 static struct simple_pid_list
*stopped_pids
;
229 /* Whether target_thread_events is in effect. */
230 static int report_thread_events
;
232 /* Async mode support. */
234 /* The read/write ends of the pipe registered as waitable file in the
236 static int linux_nat_event_pipe
[2] = { -1, -1 };
238 /* True if we're currently in async mode. */
239 #define linux_is_async_p() (linux_nat_event_pipe[0] != -1)
241 /* Flush the event pipe. */
244 async_file_flush (void)
251 ret
= read (linux_nat_event_pipe
[0], &buf
, 1);
253 while (ret
>= 0 || (ret
== -1 && errno
== EINTR
));
256 /* Put something (anything, doesn't matter what, or how much) in event
257 pipe, so that the select/poll in the event-loop realizes we have
258 something to process. */
261 async_file_mark (void)
265 /* It doesn't really matter what the pipe contains, as long we end
266 up with something in it. Might as well flush the previous
272 ret
= write (linux_nat_event_pipe
[1], "+", 1);
274 while (ret
== -1 && errno
== EINTR
);
276 /* Ignore EAGAIN. If the pipe is full, the event loop will already
277 be awakened anyway. */
280 static int kill_lwp (int lwpid
, int signo
);
282 static int stop_callback (struct lwp_info
*lp
);
284 static void block_child_signals (sigset_t
*prev_mask
);
285 static void restore_child_signals_mask (sigset_t
*prev_mask
);
288 static struct lwp_info
*add_lwp (ptid_t ptid
);
289 static void purge_lwp_list (int pid
);
290 static void delete_lwp (ptid_t ptid
);
291 static struct lwp_info
*find_lwp_pid (ptid_t ptid
);
293 static int lwp_status_pending_p (struct lwp_info
*lp
);
295 static void save_stop_reason (struct lwp_info
*lp
);
300 /* See nat/linux-nat.h. */
303 ptid_of_lwp (struct lwp_info
*lwp
)
308 /* See nat/linux-nat.h. */
311 lwp_set_arch_private_info (struct lwp_info
*lwp
,
312 struct arch_lwp_info
*info
)
314 lwp
->arch_private
= info
;
317 /* See nat/linux-nat.h. */
319 struct arch_lwp_info
*
320 lwp_arch_private_info (struct lwp_info
*lwp
)
322 return lwp
->arch_private
;
325 /* See nat/linux-nat.h. */
328 lwp_is_stopped (struct lwp_info
*lwp
)
333 /* See nat/linux-nat.h. */
335 enum target_stop_reason
336 lwp_stop_reason (struct lwp_info
*lwp
)
338 return lwp
->stop_reason
;
341 /* See nat/linux-nat.h. */
344 lwp_is_stepping (struct lwp_info
*lwp
)
350 /* Trivial list manipulation functions to keep track of a list of
351 new stopped processes. */
353 add_to_pid_list (struct simple_pid_list
**listp
, int pid
, int status
)
355 struct simple_pid_list
*new_pid
= XNEW (struct simple_pid_list
);
358 new_pid
->status
= status
;
359 new_pid
->next
= *listp
;
364 pull_pid_from_list (struct simple_pid_list
**listp
, int pid
, int *statusp
)
366 struct simple_pid_list
**p
;
368 for (p
= listp
; *p
!= NULL
; p
= &(*p
)->next
)
369 if ((*p
)->pid
== pid
)
371 struct simple_pid_list
*next
= (*p
)->next
;
373 *statusp
= (*p
)->status
;
381 /* Return the ptrace options that we want to try to enable. */
384 linux_nat_ptrace_options (int attached
)
389 options
|= PTRACE_O_EXITKILL
;
391 options
|= (PTRACE_O_TRACESYSGOOD
392 | PTRACE_O_TRACEVFORKDONE
393 | PTRACE_O_TRACEVFORK
395 | PTRACE_O_TRACEEXEC
);
400 /* Initialize ptrace and procfs warnings and check for supported
401 ptrace features given PID.
403 ATTACHED should be nonzero iff we attached to the inferior. */
406 linux_init_ptrace_procfs (pid_t pid
, int attached
)
408 int options
= linux_nat_ptrace_options (attached
);
410 linux_enable_event_reporting (pid
, options
);
411 linux_ptrace_init_warnings ();
412 linux_proc_init_warnings ();
415 linux_nat_target::~linux_nat_target ()
419 linux_nat_target::post_attach (int pid
)
421 linux_init_ptrace_procfs (pid
, 1);
425 linux_nat_target::post_startup_inferior (ptid_t ptid
)
427 linux_init_ptrace_procfs (ptid
.pid (), 0);
430 /* Return the number of known LWPs in the tgid given by PID. */
438 for (lp
= lwp_list
; lp
; lp
= lp
->next
)
439 if (lp
->ptid
.pid () == pid
)
445 /* Deleter for lwp_info unique_ptr specialisation. */
449 void operator() (struct lwp_info
*lwp
) const
451 delete_lwp (lwp
->ptid
);
455 /* A unique_ptr specialisation for lwp_info. */
457 typedef std::unique_ptr
<struct lwp_info
, lwp_deleter
> lwp_info_up
;
459 /* Target hook for follow_fork. On entry inferior_ptid must be the
460 ptid of the followed inferior. At return, inferior_ptid will be
464 linux_nat_target::follow_fork (bool follow_child
, bool detach_fork
)
468 struct lwp_info
*child_lp
= NULL
;
470 ptid_t parent_ptid
, child_ptid
;
471 int parent_pid
, child_pid
;
473 has_vforked
= (inferior_thread ()->pending_follow
.kind
474 == TARGET_WAITKIND_VFORKED
);
475 parent_ptid
= inferior_ptid
;
476 child_ptid
= inferior_thread ()->pending_follow
.value
.related_pid
;
477 parent_pid
= parent_ptid
.lwp ();
478 child_pid
= child_ptid
.lwp ();
480 /* We're already attached to the parent, by default. */
481 child_lp
= add_lwp (child_ptid
);
482 child_lp
->stopped
= 1;
483 child_lp
->last_resume_kind
= resume_stop
;
485 /* Detach new forked process? */
488 int child_stop_signal
= 0;
489 bool detach_child
= true;
491 /* Move CHILD_LP into a unique_ptr and clear the source pointer
492 to prevent us doing anything stupid with it. */
493 lwp_info_up
child_lp_ptr (child_lp
);
496 linux_target
->low_prepare_to_resume (child_lp_ptr
.get ());
498 /* When debugging an inferior in an architecture that supports
499 hardware single stepping on a kernel without commit
500 6580807da14c423f0d0a708108e6df6ebc8bc83d, the vfork child
501 process starts with the TIF_SINGLESTEP/X86_EFLAGS_TF bits
502 set if the parent process had them set.
503 To work around this, single step the child process
504 once before detaching to clear the flags. */
506 /* Note that we consult the parent's architecture instead of
507 the child's because there's no inferior for the child at
509 if (!gdbarch_software_single_step_p (target_thread_architecture
514 linux_disable_event_reporting (child_pid
);
515 if (ptrace (PTRACE_SINGLESTEP
, child_pid
, 0, 0) < 0)
516 perror_with_name (_("Couldn't do single step"));
517 if (my_waitpid (child_pid
, &status
, 0) < 0)
518 perror_with_name (_("Couldn't wait vfork process"));
521 detach_child
= WIFSTOPPED (status
);
522 child_stop_signal
= WSTOPSIG (status
);
528 int signo
= child_stop_signal
;
531 && !signal_pass_state (gdb_signal_from_host (signo
)))
533 ptrace (PTRACE_DETACH
, child_pid
, 0, signo
);
538 /* Switching inferior_ptid is not enough, because then
539 inferior_thread () would crash by not finding the thread
540 in the current inferior. */
541 scoped_restore_current_thread restore_current_thread
;
542 thread_info
*child
= find_thread_ptid (this, child_ptid
);
543 switch_to_thread (child
);
545 /* Let the thread_db layer learn about this new process. */
546 check_for_thread_db ();
551 struct lwp_info
*parent_lp
;
553 parent_lp
= find_lwp_pid (parent_ptid
);
554 gdb_assert (linux_supports_tracefork () >= 0);
556 if (linux_supports_tracevforkdone ())
558 linux_nat_debug_printf ("waiting for VFORK_DONE on %d",
560 parent_lp
->stopped
= 1;
562 /* We'll handle the VFORK_DONE event like any other
563 event, in target_wait. */
567 /* We can't insert breakpoints until the child has
568 finished with the shared memory region. We need to
569 wait until that happens. Ideal would be to just
571 - ptrace (PTRACE_SYSCALL, parent_pid, 0, 0);
572 - waitpid (parent_pid, &status, __WALL);
573 However, most architectures can't handle a syscall
574 being traced on the way out if it wasn't traced on
577 We might also think to loop, continuing the child
578 until it exits or gets a SIGTRAP. One problem is
579 that the child might call ptrace with PTRACE_TRACEME.
581 There's no simple and reliable way to figure out when
582 the vforked child will be done with its copy of the
583 shared memory. We could step it out of the syscall,
584 two instructions, let it go, and then single-step the
585 parent once. When we have hardware single-step, this
586 would work; with software single-step it could still
587 be made to work but we'd have to be able to insert
588 single-step breakpoints in the child, and we'd have
589 to insert -just- the single-step breakpoint in the
590 parent. Very awkward.
592 In the end, the best we can do is to make sure it
593 runs for a little while. Hopefully it will be out of
594 range of any breakpoints we reinsert. Usually this
595 is only the single-step breakpoint at vfork's return
598 linux_nat_debug_printf ("no VFORK_DONE support, sleeping a bit");
602 /* Pretend we've seen a PTRACE_EVENT_VFORK_DONE event,
603 and leave it pending. The next linux_nat_resume call
604 will notice a pending event, and bypasses actually
605 resuming the inferior. */
606 parent_lp
->status
= 0;
607 parent_lp
->waitstatus
.kind
= TARGET_WAITKIND_VFORK_DONE
;
608 parent_lp
->stopped
= 1;
610 /* If we're in async mode, need to tell the event loop
611 there's something here to process. */
612 if (target_is_async_p ())
619 struct lwp_info
*child_lp
;
621 child_lp
= add_lwp (inferior_ptid
);
622 child_lp
->stopped
= 1;
623 child_lp
->last_resume_kind
= resume_stop
;
625 /* Let the thread_db layer learn about this new process. */
626 check_for_thread_db ();
634 linux_nat_target::insert_fork_catchpoint (int pid
)
636 return !linux_supports_tracefork ();
640 linux_nat_target::remove_fork_catchpoint (int pid
)
646 linux_nat_target::insert_vfork_catchpoint (int pid
)
648 return !linux_supports_tracefork ();
652 linux_nat_target::remove_vfork_catchpoint (int pid
)
658 linux_nat_target::insert_exec_catchpoint (int pid
)
660 return !linux_supports_tracefork ();
664 linux_nat_target::remove_exec_catchpoint (int pid
)
670 linux_nat_target::set_syscall_catchpoint (int pid
, bool needed
, int any_count
,
671 gdb::array_view
<const int> syscall_counts
)
673 if (!linux_supports_tracesysgood ())
676 /* On GNU/Linux, we ignore the arguments. It means that we only
677 enable the syscall catchpoints, but do not disable them.
679 Also, we do not use the `syscall_counts' information because we do not
680 filter system calls here. We let GDB do the logic for us. */
684 /* List of known LWPs, keyed by LWP PID. This speeds up the common
685 case of mapping a PID returned from the kernel to our corresponding
686 lwp_info data structure. */
687 static htab_t lwp_lwpid_htab
;
689 /* Calculate a hash from a lwp_info's LWP PID. */
692 lwp_info_hash (const void *ap
)
694 const struct lwp_info
*lp
= (struct lwp_info
*) ap
;
695 pid_t pid
= lp
->ptid
.lwp ();
697 return iterative_hash_object (pid
, 0);
700 /* Equality function for the lwp_info hash table. Compares the LWP's
704 lwp_lwpid_htab_eq (const void *a
, const void *b
)
706 const struct lwp_info
*entry
= (const struct lwp_info
*) a
;
707 const struct lwp_info
*element
= (const struct lwp_info
*) b
;
709 return entry
->ptid
.lwp () == element
->ptid
.lwp ();
712 /* Create the lwp_lwpid_htab hash table. */
715 lwp_lwpid_htab_create (void)
717 lwp_lwpid_htab
= htab_create (100, lwp_info_hash
, lwp_lwpid_htab_eq
, NULL
);
720 /* Add LP to the hash table. */
723 lwp_lwpid_htab_add_lwp (struct lwp_info
*lp
)
727 slot
= htab_find_slot (lwp_lwpid_htab
, lp
, INSERT
);
728 gdb_assert (slot
!= NULL
&& *slot
== NULL
);
732 /* Head of doubly-linked list of known LWPs. Sorted by reverse
733 creation order. This order is assumed in some cases. E.g.,
734 reaping status after killing alls lwps of a process: the leader LWP
735 must be reaped last. */
736 struct lwp_info
*lwp_list
;
738 /* Add LP to sorted-by-reverse-creation-order doubly-linked list. */
741 lwp_list_add (struct lwp_info
*lp
)
744 if (lwp_list
!= NULL
)
749 /* Remove LP from sorted-by-reverse-creation-order doubly-linked
753 lwp_list_remove (struct lwp_info
*lp
)
755 /* Remove from sorted-by-creation-order list. */
756 if (lp
->next
!= NULL
)
757 lp
->next
->prev
= lp
->prev
;
758 if (lp
->prev
!= NULL
)
759 lp
->prev
->next
= lp
->next
;
766 /* Signal mask for use with sigsuspend in linux_nat_wait, initialized in
767 _initialize_linux_nat. */
768 static sigset_t suspend_mask
;
770 /* Signals to block to make that sigsuspend work. */
771 static sigset_t blocked_mask
;
773 /* SIGCHLD action. */
774 struct sigaction sigchld_action
;
776 /* Block child signals (SIGCHLD and linux threads signals), and store
777 the previous mask in PREV_MASK. */
780 block_child_signals (sigset_t
*prev_mask
)
782 /* Make sure SIGCHLD is blocked. */
783 if (!sigismember (&blocked_mask
, SIGCHLD
))
784 sigaddset (&blocked_mask
, SIGCHLD
);
786 gdb_sigmask (SIG_BLOCK
, &blocked_mask
, prev_mask
);
789 /* Restore child signals mask, previously returned by
790 block_child_signals. */
793 restore_child_signals_mask (sigset_t
*prev_mask
)
795 gdb_sigmask (SIG_SETMASK
, prev_mask
, NULL
);
798 /* Mask of signals to pass directly to the inferior. */
799 static sigset_t pass_mask
;
801 /* Update signals to pass to the inferior. */
803 linux_nat_target::pass_signals
804 (gdb::array_view
<const unsigned char> pass_signals
)
808 sigemptyset (&pass_mask
);
810 for (signo
= 1; signo
< NSIG
; signo
++)
812 int target_signo
= gdb_signal_from_host (signo
);
813 if (target_signo
< pass_signals
.size () && pass_signals
[target_signo
])
814 sigaddset (&pass_mask
, signo
);
820 /* Prototypes for local functions. */
821 static int stop_wait_callback (struct lwp_info
*lp
);
822 static int resume_stopped_resumed_lwps (struct lwp_info
*lp
, const ptid_t wait_ptid
);
823 static int check_ptrace_stopped_lwp_gone (struct lwp_info
*lp
);
827 /* Destroy and free LP. */
830 lwp_free (struct lwp_info
*lp
)
832 /* Let the arch specific bits release arch_lwp_info. */
833 linux_target
->low_delete_thread (lp
->arch_private
);
838 /* Traversal function for purge_lwp_list. */
841 lwp_lwpid_htab_remove_pid (void **slot
, void *info
)
843 struct lwp_info
*lp
= (struct lwp_info
*) *slot
;
844 int pid
= *(int *) info
;
846 if (lp
->ptid
.pid () == pid
)
848 htab_clear_slot (lwp_lwpid_htab
, slot
);
849 lwp_list_remove (lp
);
856 /* Remove all LWPs belong to PID from the lwp list. */
859 purge_lwp_list (int pid
)
861 htab_traverse_noresize (lwp_lwpid_htab
, lwp_lwpid_htab_remove_pid
, &pid
);
864 /* Add the LWP specified by PTID to the list. PTID is the first LWP
865 in the process. Return a pointer to the structure describing the
868 This differs from add_lwp in that we don't let the arch specific
869 bits know about this new thread. Current clients of this callback
870 take the opportunity to install watchpoints in the new thread, and
871 we shouldn't do that for the first thread. If we're spawning a
872 child ("run"), the thread executes the shell wrapper first, and we
873 shouldn't touch it until it execs the program we want to debug.
874 For "attach", it'd be okay to call the callback, but it's not
875 necessary, because watchpoints can't yet have been inserted into
878 static struct lwp_info
*
879 add_initial_lwp (ptid_t ptid
)
883 gdb_assert (ptid
.lwp_p ());
885 lp
= XNEW (struct lwp_info
);
887 memset (lp
, 0, sizeof (struct lwp_info
));
889 lp
->last_resume_kind
= resume_continue
;
890 lp
->waitstatus
.kind
= TARGET_WAITKIND_IGNORE
;
895 /* Add to sorted-by-reverse-creation-order list. */
898 /* Add to keyed-by-pid htab. */
899 lwp_lwpid_htab_add_lwp (lp
);
904 /* Add the LWP specified by PID to the list. Return a pointer to the
905 structure describing the new LWP. The LWP should already be
908 static struct lwp_info
*
909 add_lwp (ptid_t ptid
)
913 lp
= add_initial_lwp (ptid
);
915 /* Let the arch specific bits know about this new thread. Current
916 clients of this callback take the opportunity to install
917 watchpoints in the new thread. We don't do this for the first
918 thread though. See add_initial_lwp. */
919 linux_target
->low_new_thread (lp
);
924 /* Remove the LWP specified by PID from the list. */
927 delete_lwp (ptid_t ptid
)
931 struct lwp_info dummy
;
934 slot
= htab_find_slot (lwp_lwpid_htab
, &dummy
, NO_INSERT
);
938 lp
= *(struct lwp_info
**) slot
;
939 gdb_assert (lp
!= NULL
);
941 htab_clear_slot (lwp_lwpid_htab
, slot
);
943 /* Remove from sorted-by-creation-order list. */
944 lwp_list_remove (lp
);
950 /* Return a pointer to the structure describing the LWP corresponding
951 to PID. If no corresponding LWP could be found, return NULL. */
953 static struct lwp_info
*
954 find_lwp_pid (ptid_t ptid
)
958 struct lwp_info dummy
;
965 dummy
.ptid
= ptid_t (0, lwp
, 0);
966 lp
= (struct lwp_info
*) htab_find (lwp_lwpid_htab
, &dummy
);
970 /* See nat/linux-nat.h. */
973 iterate_over_lwps (ptid_t filter
,
974 gdb::function_view
<iterate_over_lwps_ftype
> callback
)
976 struct lwp_info
*lp
, *lpnext
;
978 for (lp
= lwp_list
; lp
; lp
= lpnext
)
982 if (lp
->ptid
.matches (filter
))
984 if (callback (lp
) != 0)
992 /* Update our internal state when changing from one checkpoint to
993 another indicated by NEW_PTID. We can only switch single-threaded
994 applications, so we only create one new LWP, and the previous list
998 linux_nat_switch_fork (ptid_t new_ptid
)
1000 struct lwp_info
*lp
;
1002 purge_lwp_list (inferior_ptid
.pid ());
1004 lp
= add_lwp (new_ptid
);
1007 /* This changes the thread's ptid while preserving the gdb thread
1008 num. Also changes the inferior pid, while preserving the
1010 thread_change_ptid (linux_target
, inferior_ptid
, new_ptid
);
1012 /* We've just told GDB core that the thread changed target id, but,
1013 in fact, it really is a different thread, with different register
1015 registers_changed ();
1018 /* Handle the exit of a single thread LP. */
1021 exit_lwp (struct lwp_info
*lp
)
1023 struct thread_info
*th
= find_thread_ptid (linux_target
, lp
->ptid
);
1027 if (print_thread_events
)
1028 printf_unfiltered (_("[%s exited]\n"),
1029 target_pid_to_str (lp
->ptid
).c_str ());
1034 delete_lwp (lp
->ptid
);
1037 /* Wait for the LWP specified by LP, which we have just attached to.
1038 Returns a wait status for that LWP, to cache. */
1041 linux_nat_post_attach_wait (ptid_t ptid
, int *signalled
)
1043 pid_t new_pid
, pid
= ptid
.lwp ();
1046 if (linux_proc_pid_is_stopped (pid
))
1048 linux_nat_debug_printf ("Attaching to a stopped process");
1050 /* The process is definitely stopped. It is in a job control
1051 stop, unless the kernel predates the TASK_STOPPED /
1052 TASK_TRACED distinction, in which case it might be in a
1053 ptrace stop. Make sure it is in a ptrace stop; from there we
1054 can kill it, signal it, et cetera.
1056 First make sure there is a pending SIGSTOP. Since we are
1057 already attached, the process can not transition from stopped
1058 to running without a PTRACE_CONT; so we know this signal will
1059 go into the queue. The SIGSTOP generated by PTRACE_ATTACH is
1060 probably already in the queue (unless this kernel is old
1061 enough to use TASK_STOPPED for ptrace stops); but since SIGSTOP
1062 is not an RT signal, it can only be queued once. */
1063 kill_lwp (pid
, SIGSTOP
);
1065 /* Finally, resume the stopped process. This will deliver the SIGSTOP
1066 (or a higher priority signal, just like normal PTRACE_ATTACH). */
1067 ptrace (PTRACE_CONT
, pid
, 0, 0);
1070 /* Make sure the initial process is stopped. The user-level threads
1071 layer might want to poke around in the inferior, and that won't
1072 work if things haven't stabilized yet. */
1073 new_pid
= my_waitpid (pid
, &status
, __WALL
);
1074 gdb_assert (pid
== new_pid
);
1076 if (!WIFSTOPPED (status
))
1078 /* The pid we tried to attach has apparently just exited. */
1079 linux_nat_debug_printf ("Failed to stop %d: %s", pid
,
1080 status_to_str (status
));
1084 if (WSTOPSIG (status
) != SIGSTOP
)
1087 linux_nat_debug_printf ("Received %s after attaching",
1088 status_to_str (status
));
1095 linux_nat_target::create_inferior (const char *exec_file
,
1096 const std::string
&allargs
,
1097 char **env
, int from_tty
)
1099 maybe_disable_address_space_randomization restore_personality
1100 (disable_randomization
);
1102 /* The fork_child mechanism is synchronous and calls target_wait, so
1103 we have to mask the async mode. */
1105 /* Make sure we report all signals during startup. */
1108 inf_ptrace_target::create_inferior (exec_file
, allargs
, env
, from_tty
);
1111 /* Callback for linux_proc_attach_tgid_threads. Attach to PTID if not
1112 already attached. Returns true if a new LWP is found, false
1116 attach_proc_task_lwp_callback (ptid_t ptid
)
1118 struct lwp_info
*lp
;
1120 /* Ignore LWPs we're already attached to. */
1121 lp
= find_lwp_pid (ptid
);
1124 int lwpid
= ptid
.lwp ();
1126 if (ptrace (PTRACE_ATTACH
, lwpid
, 0, 0) < 0)
1130 /* Be quiet if we simply raced with the thread exiting.
1131 EPERM is returned if the thread's task still exists, and
1132 is marked as exited or zombie, as well as other
1133 conditions, so in that case, confirm the status in
1134 /proc/PID/status. */
1136 || (err
== EPERM
&& linux_proc_pid_is_gone (lwpid
)))
1138 linux_nat_debug_printf
1139 ("Cannot attach to lwp %d: thread is gone (%d: %s)",
1140 lwpid
, err
, safe_strerror (err
));
1146 = linux_ptrace_attach_fail_reason_string (ptid
, err
);
1148 warning (_("Cannot attach to lwp %d: %s"),
1149 lwpid
, reason
.c_str ());
1154 linux_nat_debug_printf ("PTRACE_ATTACH %s, 0, 0 (OK)",
1155 target_pid_to_str (ptid
).c_str ());
1157 lp
= add_lwp (ptid
);
1159 /* The next time we wait for this LWP we'll see a SIGSTOP as
1160 PTRACE_ATTACH brings it to a halt. */
1163 /* We need to wait for a stop before being able to make the
1164 next ptrace call on this LWP. */
1165 lp
->must_set_ptrace_flags
= 1;
1167 /* So that wait collects the SIGSTOP. */
1170 /* Also add the LWP to gdb's thread list, in case a
1171 matching libthread_db is not found (or the process uses
1173 add_thread (linux_target
, lp
->ptid
);
1174 set_running (linux_target
, lp
->ptid
, true);
1175 set_executing (linux_target
, lp
->ptid
, true);
1184 linux_nat_target::attach (const char *args
, int from_tty
)
1186 struct lwp_info
*lp
;
1190 /* Make sure we report all signals during attach. */
1195 inf_ptrace_target::attach (args
, from_tty
);
1197 catch (const gdb_exception_error
&ex
)
1199 pid_t pid
= parse_pid_to_attach (args
);
1200 std::string reason
= linux_ptrace_attach_fail_reason (pid
);
1202 if (!reason
.empty ())
1203 throw_error (ex
.error
, "warning: %s\n%s", reason
.c_str (),
1206 throw_error (ex
.error
, "%s", ex
.what ());
1209 /* The ptrace base target adds the main thread with (pid,0,0)
1210 format. Decorate it with lwp info. */
1211 ptid
= ptid_t (inferior_ptid
.pid (),
1212 inferior_ptid
.pid (),
1214 thread_change_ptid (linux_target
, inferior_ptid
, ptid
);
1216 /* Add the initial process as the first LWP to the list. */
1217 lp
= add_initial_lwp (ptid
);
1219 status
= linux_nat_post_attach_wait (lp
->ptid
, &lp
->signalled
);
1220 if (!WIFSTOPPED (status
))
1222 if (WIFEXITED (status
))
1224 int exit_code
= WEXITSTATUS (status
);
1226 target_terminal::ours ();
1227 target_mourn_inferior (inferior_ptid
);
1229 error (_("Unable to attach: program exited normally."));
1231 error (_("Unable to attach: program exited with code %d."),
1234 else if (WIFSIGNALED (status
))
1236 enum gdb_signal signo
;
1238 target_terminal::ours ();
1239 target_mourn_inferior (inferior_ptid
);
1241 signo
= gdb_signal_from_host (WTERMSIG (status
));
1242 error (_("Unable to attach: program terminated with signal "
1244 gdb_signal_to_name (signo
),
1245 gdb_signal_to_string (signo
));
1248 internal_error (__FILE__
, __LINE__
,
1249 _("unexpected status %d for PID %ld"),
1250 status
, (long) ptid
.lwp ());
1255 /* Save the wait status to report later. */
1257 linux_nat_debug_printf ("waitpid %ld, saving status %s",
1258 (long) lp
->ptid
.pid (), status_to_str (status
));
1260 lp
->status
= status
;
1262 /* We must attach to every LWP. If /proc is mounted, use that to
1263 find them now. The inferior may be using raw clone instead of
1264 using pthreads. But even if it is using pthreads, thread_db
1265 walks structures in the inferior's address space to find the list
1266 of threads/LWPs, and those structures may well be corrupted.
1267 Note that once thread_db is loaded, we'll still use it to list
1268 threads and associate pthread info with each LWP. */
1269 linux_proc_attach_tgid_threads (lp
->ptid
.pid (),
1270 attach_proc_task_lwp_callback
);
1272 if (target_can_async_p ())
1276 /* Get pending signal of THREAD as a host signal number, for detaching
1277 purposes. This is the signal the thread last stopped for, which we
1278 need to deliver to the thread when detaching, otherwise, it'd be
1282 get_detach_signal (struct lwp_info
*lp
)
1284 enum gdb_signal signo
= GDB_SIGNAL_0
;
1286 /* If we paused threads momentarily, we may have stored pending
1287 events in lp->status or lp->waitstatus (see stop_wait_callback),
1288 and GDB core hasn't seen any signal for those threads.
1289 Otherwise, the last signal reported to the core is found in the
1290 thread object's stop_signal.
1292 There's a corner case that isn't handled here at present. Only
1293 if the thread stopped with a TARGET_WAITKIND_STOPPED does
1294 stop_signal make sense as a real signal to pass to the inferior.
1295 Some catchpoint related events, like
1296 TARGET_WAITKIND_(V)FORK|EXEC|SYSCALL, have their stop_signal set
1297 to GDB_SIGNAL_SIGTRAP when the catchpoint triggers. But,
1298 those traps are debug API (ptrace in our case) related and
1299 induced; the inferior wouldn't see them if it wasn't being
1300 traced. Hence, we should never pass them to the inferior, even
1301 when set to pass state. Since this corner case isn't handled by
1302 infrun.c when proceeding with a signal, for consistency, neither
1303 do we handle it here (or elsewhere in the file we check for
1304 signal pass state). Normally SIGTRAP isn't set to pass state, so
1305 this is really a corner case. */
1307 if (lp
->waitstatus
.kind
!= TARGET_WAITKIND_IGNORE
)
1308 signo
= GDB_SIGNAL_0
; /* a pending ptrace event, not a real signal. */
1309 else if (lp
->status
)
1310 signo
= gdb_signal_from_host (WSTOPSIG (lp
->status
));
1313 struct thread_info
*tp
= find_thread_ptid (linux_target
, lp
->ptid
);
1315 if (target_is_non_stop_p () && !tp
->executing
)
1317 if (tp
->suspend
.waitstatus_pending_p
)
1318 signo
= tp
->suspend
.waitstatus
.value
.sig
;
1320 signo
= tp
->suspend
.stop_signal
;
1322 else if (!target_is_non_stop_p ())
1325 process_stratum_target
*last_target
;
1327 get_last_target_status (&last_target
, &last_ptid
, nullptr);
1329 if (last_target
== linux_target
1330 && lp
->ptid
.lwp () == last_ptid
.lwp ())
1331 signo
= tp
->suspend
.stop_signal
;
1335 if (signo
== GDB_SIGNAL_0
)
1337 linux_nat_debug_printf ("lwp %s has no pending signal",
1338 target_pid_to_str (lp
->ptid
).c_str ());
1340 else if (!signal_pass_state (signo
))
1342 linux_nat_debug_printf
1343 ("lwp %s had signal %s but it is in no pass state",
1344 target_pid_to_str (lp
->ptid
).c_str (), gdb_signal_to_string (signo
));
1348 linux_nat_debug_printf ("lwp %s has pending signal %s",
1349 target_pid_to_str (lp
->ptid
).c_str (),
1350 gdb_signal_to_string (signo
));
1352 return gdb_signal_to_host (signo
);
1358 /* Detach from LP. If SIGNO_P is non-NULL, then it points to the
1359 signal number that should be passed to the LWP when detaching.
1360 Otherwise pass any pending signal the LWP may have, if any. */
1363 detach_one_lwp (struct lwp_info
*lp
, int *signo_p
)
1365 int lwpid
= lp
->ptid
.lwp ();
1368 gdb_assert (lp
->status
== 0 || WIFSTOPPED (lp
->status
));
1370 if (lp
->status
!= 0)
1371 linux_nat_debug_printf ("Pending %s for %s on detach.",
1372 strsignal (WSTOPSIG (lp
->status
)),
1373 target_pid_to_str (lp
->ptid
).c_str ());
1375 /* If there is a pending SIGSTOP, get rid of it. */
1378 linux_nat_debug_printf ("Sending SIGCONT to %s",
1379 target_pid_to_str (lp
->ptid
).c_str ());
1381 kill_lwp (lwpid
, SIGCONT
);
1385 if (signo_p
== NULL
)
1387 /* Pass on any pending signal for this LWP. */
1388 signo
= get_detach_signal (lp
);
1393 /* Preparing to resume may try to write registers, and fail if the
1394 lwp is zombie. If that happens, ignore the error. We'll handle
1395 it below, when detach fails with ESRCH. */
1398 linux_target
->low_prepare_to_resume (lp
);
1400 catch (const gdb_exception_error
&ex
)
1402 if (!check_ptrace_stopped_lwp_gone (lp
))
1406 if (ptrace (PTRACE_DETACH
, lwpid
, 0, signo
) < 0)
1408 int save_errno
= errno
;
1410 /* We know the thread exists, so ESRCH must mean the lwp is
1411 zombie. This can happen if one of the already-detached
1412 threads exits the whole thread group. In that case we're
1413 still attached, and must reap the lwp. */
1414 if (save_errno
== ESRCH
)
1418 ret
= my_waitpid (lwpid
, &status
, __WALL
);
1421 warning (_("Couldn't reap LWP %d while detaching: %s"),
1422 lwpid
, safe_strerror (errno
));
1424 else if (!WIFEXITED (status
) && !WIFSIGNALED (status
))
1426 warning (_("Reaping LWP %d while detaching "
1427 "returned unexpected status 0x%x"),
1433 error (_("Can't detach %s: %s"),
1434 target_pid_to_str (lp
->ptid
).c_str (),
1435 safe_strerror (save_errno
));
1439 linux_nat_debug_printf ("PTRACE_DETACH (%s, %s, 0) (OK)",
1440 target_pid_to_str (lp
->ptid
).c_str (),
1443 delete_lwp (lp
->ptid
);
1447 detach_callback (struct lwp_info
*lp
)
1449 /* We don't actually detach from the thread group leader just yet.
1450 If the thread group exits, we must reap the zombie clone lwps
1451 before we're able to reap the leader. */
1452 if (lp
->ptid
.lwp () != lp
->ptid
.pid ())
1453 detach_one_lwp (lp
, NULL
);
1458 linux_nat_target::detach (inferior
*inf
, int from_tty
)
1460 struct lwp_info
*main_lwp
;
1463 /* Don't unregister from the event loop, as there may be other
1464 inferiors running. */
1466 /* Stop all threads before detaching. ptrace requires that the
1467 thread is stopped to successfully detach. */
1468 iterate_over_lwps (ptid_t (pid
), stop_callback
);
1469 /* ... and wait until all of them have reported back that
1470 they're no longer running. */
1471 iterate_over_lwps (ptid_t (pid
), stop_wait_callback
);
1473 iterate_over_lwps (ptid_t (pid
), detach_callback
);
1475 /* Only the initial process should be left right now. */
1476 gdb_assert (num_lwps (pid
) == 1);
1478 main_lwp
= find_lwp_pid (ptid_t (pid
));
1480 if (forks_exist_p ())
1482 /* Multi-fork case. The current inferior_ptid is being detached
1483 from, but there are other viable forks to debug. Detach from
1484 the current fork, and context-switch to the first
1486 linux_fork_detach (from_tty
);
1490 target_announce_detach (from_tty
);
1492 /* Pass on any pending signal for the last LWP. */
1493 int signo
= get_detach_signal (main_lwp
);
1495 detach_one_lwp (main_lwp
, &signo
);
1497 detach_success (inf
);
1501 /* Resume execution of the inferior process. If STEP is nonzero,
1502 single-step it. If SIGNAL is nonzero, give it that signal. */
1505 linux_resume_one_lwp_throw (struct lwp_info
*lp
, int step
,
1506 enum gdb_signal signo
)
1510 /* stop_pc doubles as the PC the LWP had when it was last resumed.
1511 We only presently need that if the LWP is stepped though (to
1512 handle the case of stepping a breakpoint instruction). */
1515 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
1517 lp
->stop_pc
= regcache_read_pc (regcache
);
1522 linux_target
->low_prepare_to_resume (lp
);
1523 linux_target
->low_resume (lp
->ptid
, step
, signo
);
1525 /* Successfully resumed. Clear state that no longer makes sense,
1526 and mark the LWP as running. Must not do this before resuming
1527 otherwise if that fails other code will be confused. E.g., we'd
1528 later try to stop the LWP and hang forever waiting for a stop
1529 status. Note that we must not throw after this is cleared,
1530 otherwise handle_zombie_lwp_error would get confused. */
1533 lp
->stop_reason
= TARGET_STOPPED_BY_NO_REASON
;
1534 registers_changed_ptid (linux_target
, lp
->ptid
);
1537 /* Called when we try to resume a stopped LWP and that errors out. If
1538 the LWP is no longer in ptrace-stopped state (meaning it's zombie,
1539 or about to become), discard the error, clear any pending status
1540 the LWP may have, and return true (we'll collect the exit status
1541 soon enough). Otherwise, return false. */
1544 check_ptrace_stopped_lwp_gone (struct lwp_info
*lp
)
1546 /* If we get an error after resuming the LWP successfully, we'd
1547 confuse !T state for the LWP being gone. */
1548 gdb_assert (lp
->stopped
);
1550 /* We can't just check whether the LWP is in 'Z (Zombie)' state,
1551 because even if ptrace failed with ESRCH, the tracee may be "not
1552 yet fully dead", but already refusing ptrace requests. In that
1553 case the tracee has 'R (Running)' state for a little bit
1554 (observed in Linux 3.18). See also the note on ESRCH in the
1555 ptrace(2) man page. Instead, check whether the LWP has any state
1556 other than ptrace-stopped. */
1558 /* Don't assume anything if /proc/PID/status can't be read. */
1559 if (linux_proc_pid_is_trace_stopped_nowarn (lp
->ptid
.lwp ()) == 0)
1561 lp
->stop_reason
= TARGET_STOPPED_BY_NO_REASON
;
1563 lp
->waitstatus
.kind
= TARGET_WAITKIND_IGNORE
;
1569 /* Like linux_resume_one_lwp_throw, but no error is thrown if the LWP
1570 disappears while we try to resume it. */
1573 linux_resume_one_lwp (struct lwp_info
*lp
, int step
, enum gdb_signal signo
)
1577 linux_resume_one_lwp_throw (lp
, step
, signo
);
1579 catch (const gdb_exception_error
&ex
)
1581 if (!check_ptrace_stopped_lwp_gone (lp
))
1589 resume_lwp (struct lwp_info
*lp
, int step
, enum gdb_signal signo
)
1593 struct inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
1595 if (inf
->vfork_child
!= NULL
)
1597 linux_nat_debug_printf ("Not resuming %s (vfork parent)",
1598 target_pid_to_str (lp
->ptid
).c_str ());
1600 else if (!lwp_status_pending_p (lp
))
1602 linux_nat_debug_printf ("Resuming sibling %s, %s, %s",
1603 target_pid_to_str (lp
->ptid
).c_str (),
1604 (signo
!= GDB_SIGNAL_0
1605 ? strsignal (gdb_signal_to_host (signo
))
1607 step
? "step" : "resume");
1609 linux_resume_one_lwp (lp
, step
, signo
);
1613 linux_nat_debug_printf ("Not resuming sibling %s (has pending)",
1614 target_pid_to_str (lp
->ptid
).c_str ());
1618 linux_nat_debug_printf ("Not resuming sibling %s (not stopped)",
1619 target_pid_to_str (lp
->ptid
).c_str ());
1622 /* Callback for iterate_over_lwps. If LWP is EXCEPT, do nothing.
1623 Resume LWP with the last stop signal, if it is in pass state. */
1626 linux_nat_resume_callback (struct lwp_info
*lp
, struct lwp_info
*except
)
1628 enum gdb_signal signo
= GDB_SIGNAL_0
;
1635 struct thread_info
*thread
;
1637 thread
= find_thread_ptid (linux_target
, lp
->ptid
);
1640 signo
= thread
->suspend
.stop_signal
;
1641 thread
->suspend
.stop_signal
= GDB_SIGNAL_0
;
1645 resume_lwp (lp
, 0, signo
);
1650 resume_clear_callback (struct lwp_info
*lp
)
1653 lp
->last_resume_kind
= resume_stop
;
1658 resume_set_callback (struct lwp_info
*lp
)
1661 lp
->last_resume_kind
= resume_continue
;
1666 linux_nat_target::resume (ptid_t ptid
, int step
, enum gdb_signal signo
)
1668 struct lwp_info
*lp
;
1671 linux_nat_debug_printf ("Preparing to %s %s, %s, inferior_ptid %s",
1672 step
? "step" : "resume",
1673 target_pid_to_str (ptid
).c_str (),
1674 (signo
!= GDB_SIGNAL_0
1675 ? strsignal (gdb_signal_to_host (signo
)) : "0"),
1676 target_pid_to_str (inferior_ptid
).c_str ());
1678 /* A specific PTID means `step only this process id'. */
1679 resume_many
= (minus_one_ptid
== ptid
1682 /* Mark the lwps we're resuming as resumed and update their
1683 last_resume_kind to resume_continue. */
1684 iterate_over_lwps (ptid
, resume_set_callback
);
1686 /* See if it's the current inferior that should be handled
1689 lp
= find_lwp_pid (inferior_ptid
);
1691 lp
= find_lwp_pid (ptid
);
1692 gdb_assert (lp
!= NULL
);
1694 /* Remember if we're stepping. */
1695 lp
->last_resume_kind
= step
? resume_step
: resume_continue
;
1697 /* If we have a pending wait status for this thread, there is no
1698 point in resuming the process. But first make sure that
1699 linux_nat_wait won't preemptively handle the event - we
1700 should never take this short-circuit if we are going to
1701 leave LP running, since we have skipped resuming all the
1702 other threads. This bit of code needs to be synchronized
1703 with linux_nat_wait. */
1705 if (lp
->status
&& WIFSTOPPED (lp
->status
))
1708 && WSTOPSIG (lp
->status
)
1709 && sigismember (&pass_mask
, WSTOPSIG (lp
->status
)))
1711 linux_nat_debug_printf
1712 ("Not short circuiting for ignored status 0x%x", lp
->status
);
1714 /* FIXME: What should we do if we are supposed to continue
1715 this thread with a signal? */
1716 gdb_assert (signo
== GDB_SIGNAL_0
);
1717 signo
= gdb_signal_from_host (WSTOPSIG (lp
->status
));
1722 if (lwp_status_pending_p (lp
))
1724 /* FIXME: What should we do if we are supposed to continue
1725 this thread with a signal? */
1726 gdb_assert (signo
== GDB_SIGNAL_0
);
1728 linux_nat_debug_printf ("Short circuiting for status 0x%x",
1731 if (target_can_async_p ())
1734 /* Tell the event loop we have something to process. */
1741 iterate_over_lwps (ptid
, [=] (struct lwp_info
*info
)
1743 return linux_nat_resume_callback (info
, lp
);
1746 linux_nat_debug_printf ("%s %s, %s (resume event thread)",
1747 step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
1748 target_pid_to_str (lp
->ptid
).c_str (),
1749 (signo
!= GDB_SIGNAL_0
1750 ? strsignal (gdb_signal_to_host (signo
)) : "0"));
1752 linux_resume_one_lwp (lp
, step
, signo
);
1754 if (target_can_async_p ())
1758 /* Send a signal to an LWP. */
1761 kill_lwp (int lwpid
, int signo
)
1766 ret
= syscall (__NR_tkill
, lwpid
, signo
);
1767 if (errno
== ENOSYS
)
1769 /* If tkill fails, then we are not using nptl threads, a
1770 configuration we no longer support. */
1771 perror_with_name (("tkill"));
1776 /* Handle a GNU/Linux syscall trap wait response. If we see a syscall
1777 event, check if the core is interested in it: if not, ignore the
1778 event, and keep waiting; otherwise, we need to toggle the LWP's
1779 syscall entry/exit status, since the ptrace event itself doesn't
1780 indicate it, and report the trap to higher layers. */
1783 linux_handle_syscall_trap (struct lwp_info
*lp
, int stopping
)
1785 struct target_waitstatus
*ourstatus
= &lp
->waitstatus
;
1786 struct gdbarch
*gdbarch
= target_thread_architecture (lp
->ptid
);
1787 thread_info
*thread
= find_thread_ptid (linux_target
, lp
->ptid
);
1788 int syscall_number
= (int) gdbarch_get_syscall_number (gdbarch
, thread
);
1792 /* If we're stopping threads, there's a SIGSTOP pending, which
1793 makes it so that the LWP reports an immediate syscall return,
1794 followed by the SIGSTOP. Skip seeing that "return" using
1795 PTRACE_CONT directly, and let stop_wait_callback collect the
1796 SIGSTOP. Later when the thread is resumed, a new syscall
1797 entry event. If we didn't do this (and returned 0), we'd
1798 leave a syscall entry pending, and our caller, by using
1799 PTRACE_CONT to collect the SIGSTOP, skips the syscall return
1800 itself. Later, when the user re-resumes this LWP, we'd see
1801 another syscall entry event and we'd mistake it for a return.
1803 If stop_wait_callback didn't force the SIGSTOP out of the LWP
1804 (leaving immediately with LWP->signalled set, without issuing
1805 a PTRACE_CONT), it would still be problematic to leave this
1806 syscall enter pending, as later when the thread is resumed,
1807 it would then see the same syscall exit mentioned above,
1808 followed by the delayed SIGSTOP, while the syscall didn't
1809 actually get to execute. It seems it would be even more
1810 confusing to the user. */
1812 linux_nat_debug_printf
1813 ("ignoring syscall %d for LWP %ld (stopping threads), resuming with "
1814 "PTRACE_CONT for SIGSTOP", syscall_number
, lp
->ptid
.lwp ());
1816 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
1817 ptrace (PTRACE_CONT
, lp
->ptid
.lwp (), 0, 0);
1822 /* Always update the entry/return state, even if this particular
1823 syscall isn't interesting to the core now. In async mode,
1824 the user could install a new catchpoint for this syscall
1825 between syscall enter/return, and we'll need to know to
1826 report a syscall return if that happens. */
1827 lp
->syscall_state
= (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1828 ? TARGET_WAITKIND_SYSCALL_RETURN
1829 : TARGET_WAITKIND_SYSCALL_ENTRY
);
1831 if (catch_syscall_enabled ())
1833 if (catching_syscall_number (syscall_number
))
1835 /* Alright, an event to report. */
1836 ourstatus
->kind
= lp
->syscall_state
;
1837 ourstatus
->value
.syscall_number
= syscall_number
;
1839 linux_nat_debug_printf
1840 ("stopping for %s of syscall %d for LWP %ld",
1841 (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1842 ? "entry" : "return"), syscall_number
, lp
->ptid
.lwp ());
1847 linux_nat_debug_printf
1848 ("ignoring %s of syscall %d for LWP %ld",
1849 (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1850 ? "entry" : "return"), syscall_number
, lp
->ptid
.lwp ());
1854 /* If we had been syscall tracing, and hence used PT_SYSCALL
1855 before on this LWP, it could happen that the user removes all
1856 syscall catchpoints before we get to process this event.
1857 There are two noteworthy issues here:
1859 - When stopped at a syscall entry event, resuming with
1860 PT_STEP still resumes executing the syscall and reports a
1863 - Only PT_SYSCALL catches syscall enters. If we last
1864 single-stepped this thread, then this event can't be a
1865 syscall enter. If we last single-stepped this thread, this
1866 has to be a syscall exit.
1868 The points above mean that the next resume, be it PT_STEP or
1869 PT_CONTINUE, can not trigger a syscall trace event. */
1870 linux_nat_debug_printf
1871 ("caught syscall event with no syscall catchpoints. %d for LWP %ld, "
1872 "ignoring", syscall_number
, lp
->ptid
.lwp ());
1873 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
1876 /* The core isn't interested in this event. For efficiency, avoid
1877 stopping all threads only to have the core resume them all again.
1878 Since we're not stopping threads, if we're still syscall tracing
1879 and not stepping, we can't use PTRACE_CONT here, as we'd miss any
1880 subsequent syscall. Simply resume using the inf-ptrace layer,
1881 which knows when to use PT_SYSCALL or PT_CONTINUE. */
1883 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
1887 /* Handle a GNU/Linux extended wait response. If we see a clone
1888 event, we need to add the new LWP to our list (and not report the
1889 trap to higher layers). This function returns non-zero if the
1890 event should be ignored and we should wait again. If STOPPING is
1891 true, the new LWP remains stopped, otherwise it is continued. */
1894 linux_handle_extended_wait (struct lwp_info
*lp
, int status
)
1896 int pid
= lp
->ptid
.lwp ();
1897 struct target_waitstatus
*ourstatus
= &lp
->waitstatus
;
1898 int event
= linux_ptrace_get_extended_event (status
);
1900 /* All extended events we currently use are mid-syscall. Only
1901 PTRACE_EVENT_STOP is delivered more like a signal-stop, but
1902 you have to be using PTRACE_SEIZE to get that. */
1903 lp
->syscall_state
= TARGET_WAITKIND_SYSCALL_ENTRY
;
1905 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
1906 || event
== PTRACE_EVENT_CLONE
)
1908 unsigned long new_pid
;
1911 ptrace (PTRACE_GETEVENTMSG
, pid
, 0, &new_pid
);
1913 /* If we haven't already seen the new PID stop, wait for it now. */
1914 if (! pull_pid_from_list (&stopped_pids
, new_pid
, &status
))
1916 /* The new child has a pending SIGSTOP. We can't affect it until it
1917 hits the SIGSTOP, but we're already attached. */
1918 ret
= my_waitpid (new_pid
, &status
, __WALL
);
1920 perror_with_name (_("waiting for new child"));
1921 else if (ret
!= new_pid
)
1922 internal_error (__FILE__
, __LINE__
,
1923 _("wait returned unexpected PID %d"), ret
);
1924 else if (!WIFSTOPPED (status
))
1925 internal_error (__FILE__
, __LINE__
,
1926 _("wait returned unexpected status 0x%x"), status
);
1929 ourstatus
->value
.related_pid
= ptid_t (new_pid
, new_pid
, 0);
1931 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
)
1933 /* The arch-specific native code may need to know about new
1934 forks even if those end up never mapped to an
1936 linux_target
->low_new_fork (lp
, new_pid
);
1938 else if (event
== PTRACE_EVENT_CLONE
)
1940 linux_target
->low_new_clone (lp
, new_pid
);
1943 if (event
== PTRACE_EVENT_FORK
1944 && linux_fork_checkpointing_p (lp
->ptid
.pid ()))
1946 /* Handle checkpointing by linux-fork.c here as a special
1947 case. We don't want the follow-fork-mode or 'catch fork'
1948 to interfere with this. */
1950 /* This won't actually modify the breakpoint list, but will
1951 physically remove the breakpoints from the child. */
1952 detach_breakpoints (ptid_t (new_pid
, new_pid
, 0));
1954 /* Retain child fork in ptrace (stopped) state. */
1955 if (!find_fork_pid (new_pid
))
1958 /* Report as spurious, so that infrun doesn't want to follow
1959 this fork. We're actually doing an infcall in
1961 ourstatus
->kind
= TARGET_WAITKIND_SPURIOUS
;
1963 /* Report the stop to the core. */
1967 if (event
== PTRACE_EVENT_FORK
)
1968 ourstatus
->kind
= TARGET_WAITKIND_FORKED
;
1969 else if (event
== PTRACE_EVENT_VFORK
)
1970 ourstatus
->kind
= TARGET_WAITKIND_VFORKED
;
1971 else if (event
== PTRACE_EVENT_CLONE
)
1973 struct lwp_info
*new_lp
;
1975 ourstatus
->kind
= TARGET_WAITKIND_IGNORE
;
1977 linux_nat_debug_printf
1978 ("Got clone event from LWP %d, new child is LWP %ld", pid
, new_pid
);
1980 new_lp
= add_lwp (ptid_t (lp
->ptid
.pid (), new_pid
, 0));
1981 new_lp
->stopped
= 1;
1982 new_lp
->resumed
= 1;
1984 /* If the thread_db layer is active, let it record the user
1985 level thread id and status, and add the thread to GDB's
1987 if (!thread_db_notice_clone (lp
->ptid
, new_lp
->ptid
))
1989 /* The process is not using thread_db. Add the LWP to
1991 target_post_attach (new_lp
->ptid
.lwp ());
1992 add_thread (linux_target
, new_lp
->ptid
);
1995 /* Even if we're stopping the thread for some reason
1996 internal to this module, from the perspective of infrun
1997 and the user/frontend, this new thread is running until
1998 it next reports a stop. */
1999 set_running (linux_target
, new_lp
->ptid
, true);
2000 set_executing (linux_target
, new_lp
->ptid
, true);
2002 if (WSTOPSIG (status
) != SIGSTOP
)
2004 /* This can happen if someone starts sending signals to
2005 the new thread before it gets a chance to run, which
2006 have a lower number than SIGSTOP (e.g. SIGUSR1).
2007 This is an unlikely case, and harder to handle for
2008 fork / vfork than for clone, so we do not try - but
2009 we handle it for clone events here. */
2011 new_lp
->signalled
= 1;
2013 /* We created NEW_LP so it cannot yet contain STATUS. */
2014 gdb_assert (new_lp
->status
== 0);
2016 /* Save the wait status to report later. */
2017 linux_nat_debug_printf
2018 ("waitpid of new LWP %ld, saving status %s",
2019 (long) new_lp
->ptid
.lwp (), status_to_str (status
));
2020 new_lp
->status
= status
;
2022 else if (report_thread_events
)
2024 new_lp
->waitstatus
.kind
= TARGET_WAITKIND_THREAD_CREATED
;
2025 new_lp
->status
= status
;
2034 if (event
== PTRACE_EVENT_EXEC
)
2036 linux_nat_debug_printf ("Got exec event from LWP %ld", lp
->ptid
.lwp ());
2038 ourstatus
->kind
= TARGET_WAITKIND_EXECD
;
2039 ourstatus
->value
.execd_pathname
2040 = xstrdup (linux_proc_pid_to_exec_file (pid
));
2042 /* The thread that execed must have been resumed, but, when a
2043 thread execs, it changes its tid to the tgid, and the old
2044 tgid thread might have not been resumed. */
2049 if (event
== PTRACE_EVENT_VFORK_DONE
)
2051 if (current_inferior ()->waiting_for_vfork_done
)
2053 linux_nat_debug_printf
2054 ("Got expected PTRACE_EVENT_VFORK_DONE from LWP %ld: stopping",
2057 ourstatus
->kind
= TARGET_WAITKIND_VFORK_DONE
;
2061 linux_nat_debug_printf
2062 ("Got PTRACE_EVENT_VFORK_DONE from LWP %ld: ignoring", lp
->ptid
.lwp ());
2067 internal_error (__FILE__
, __LINE__
,
2068 _("unknown ptrace event %d"), event
);
2071 /* Suspend waiting for a signal. We're mostly interested in
2077 linux_nat_debug_printf ("about to sigsuspend");
2078 sigsuspend (&suspend_mask
);
2080 /* If the quit flag is set, it means that the user pressed Ctrl-C
2081 and we're debugging a process that is running on a separate
2082 terminal, so we must forward the Ctrl-C to the inferior. (If the
2083 inferior is sharing GDB's terminal, then the Ctrl-C reaches the
2084 inferior directly.) We must do this here because functions that
2085 need to block waiting for a signal loop forever until there's an
2086 event to report before returning back to the event loop. */
2087 if (!target_terminal::is_ours ())
2089 if (check_quit_flag ())
2090 target_pass_ctrlc ();
2094 /* Wait for LP to stop. Returns the wait status, or 0 if the LWP has
2098 wait_lwp (struct lwp_info
*lp
)
2102 int thread_dead
= 0;
2105 gdb_assert (!lp
->stopped
);
2106 gdb_assert (lp
->status
== 0);
2108 /* Make sure SIGCHLD is blocked for sigsuspend avoiding a race below. */
2109 block_child_signals (&prev_mask
);
2113 pid
= my_waitpid (lp
->ptid
.lwp (), &status
, __WALL
| WNOHANG
);
2114 if (pid
== -1 && errno
== ECHILD
)
2116 /* The thread has previously exited. We need to delete it
2117 now because if this was a non-leader thread execing, we
2118 won't get an exit event. See comments on exec events at
2119 the top of the file. */
2121 linux_nat_debug_printf ("%s vanished.",
2122 target_pid_to_str (lp
->ptid
).c_str ());
2127 /* Bugs 10970, 12702.
2128 Thread group leader may have exited in which case we'll lock up in
2129 waitpid if there are other threads, even if they are all zombies too.
2130 Basically, we're not supposed to use waitpid this way.
2131 tkill(pid,0) cannot be used here as it gets ESRCH for both
2132 for zombie and running processes.
2134 As a workaround, check if we're waiting for the thread group leader and
2135 if it's a zombie, and avoid calling waitpid if it is.
2137 This is racy, what if the tgl becomes a zombie right after we check?
2138 Therefore always use WNOHANG with sigsuspend - it is equivalent to
2139 waiting waitpid but linux_proc_pid_is_zombie is safe this way. */
2141 if (lp
->ptid
.pid () == lp
->ptid
.lwp ()
2142 && linux_proc_pid_is_zombie (lp
->ptid
.lwp ()))
2145 linux_nat_debug_printf ("Thread group leader %s vanished.",
2146 target_pid_to_str (lp
->ptid
).c_str ());
2150 /* Wait for next SIGCHLD and try again. This may let SIGCHLD handlers
2151 get invoked despite our caller had them intentionally blocked by
2152 block_child_signals. This is sensitive only to the loop of
2153 linux_nat_wait_1 and there if we get called my_waitpid gets called
2154 again before it gets to sigsuspend so we can safely let the handlers
2155 get executed here. */
2159 restore_child_signals_mask (&prev_mask
);
2163 gdb_assert (pid
== lp
->ptid
.lwp ());
2165 linux_nat_debug_printf ("waitpid %s received %s",
2166 target_pid_to_str (lp
->ptid
).c_str (),
2167 status_to_str (status
));
2169 /* Check if the thread has exited. */
2170 if (WIFEXITED (status
) || WIFSIGNALED (status
))
2172 if (report_thread_events
2173 || lp
->ptid
.pid () == lp
->ptid
.lwp ())
2175 linux_nat_debug_printf ("LWP %d exited.", lp
->ptid
.pid ());
2177 /* If this is the leader exiting, it means the whole
2178 process is gone. Store the status to report to the
2179 core. Store it in lp->waitstatus, because lp->status
2180 would be ambiguous (W_EXITCODE(0,0) == 0). */
2181 store_waitstatus (&lp
->waitstatus
, status
);
2186 linux_nat_debug_printf ("%s exited.",
2187 target_pid_to_str (lp
->ptid
).c_str ());
2197 gdb_assert (WIFSTOPPED (status
));
2200 if (lp
->must_set_ptrace_flags
)
2202 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2203 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
2205 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
2206 lp
->must_set_ptrace_flags
= 0;
2209 /* Handle GNU/Linux's syscall SIGTRAPs. */
2210 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
2212 /* No longer need the sysgood bit. The ptrace event ends up
2213 recorded in lp->waitstatus if we care for it. We can carry
2214 on handling the event like a regular SIGTRAP from here
2216 status
= W_STOPCODE (SIGTRAP
);
2217 if (linux_handle_syscall_trap (lp
, 1))
2218 return wait_lwp (lp
);
2222 /* Almost all other ptrace-stops are known to be outside of system
2223 calls, with further exceptions in linux_handle_extended_wait. */
2224 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
2227 /* Handle GNU/Linux's extended waitstatus for trace events. */
2228 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
2229 && linux_is_extended_waitstatus (status
))
2231 linux_nat_debug_printf ("Handling extended status 0x%06x", status
);
2232 linux_handle_extended_wait (lp
, status
);
2239 /* Send a SIGSTOP to LP. */
2242 stop_callback (struct lwp_info
*lp
)
2244 if (!lp
->stopped
&& !lp
->signalled
)
2248 linux_nat_debug_printf ("kill %s **<SIGSTOP>**",
2249 target_pid_to_str (lp
->ptid
).c_str ());
2252 ret
= kill_lwp (lp
->ptid
.lwp (), SIGSTOP
);
2253 linux_nat_debug_printf ("lwp kill %d %s", ret
,
2254 errno
? safe_strerror (errno
) : "ERRNO-OK");
2257 gdb_assert (lp
->status
== 0);
2263 /* Request a stop on LWP. */
2266 linux_stop_lwp (struct lwp_info
*lwp
)
2268 stop_callback (lwp
);
2271 /* See linux-nat.h */
2274 linux_stop_and_wait_all_lwps (void)
2276 /* Stop all LWP's ... */
2277 iterate_over_lwps (minus_one_ptid
, stop_callback
);
2279 /* ... and wait until all of them have reported back that
2280 they're no longer running. */
2281 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
2284 /* See linux-nat.h */
2287 linux_unstop_all_lwps (void)
2289 iterate_over_lwps (minus_one_ptid
,
2290 [] (struct lwp_info
*info
)
2292 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
2296 /* Return non-zero if LWP PID has a pending SIGINT. */
2299 linux_nat_has_pending_sigint (int pid
)
2301 sigset_t pending
, blocked
, ignored
;
2303 linux_proc_pending_signals (pid
, &pending
, &blocked
, &ignored
);
2305 if (sigismember (&pending
, SIGINT
)
2306 && !sigismember (&ignored
, SIGINT
))
2312 /* Set a flag in LP indicating that we should ignore its next SIGINT. */
2315 set_ignore_sigint (struct lwp_info
*lp
)
2317 /* If a thread has a pending SIGINT, consume it; otherwise, set a
2318 flag to consume the next one. */
2319 if (lp
->stopped
&& lp
->status
!= 0 && WIFSTOPPED (lp
->status
)
2320 && WSTOPSIG (lp
->status
) == SIGINT
)
2323 lp
->ignore_sigint
= 1;
2328 /* If LP does not have a SIGINT pending, then clear the ignore_sigint flag.
2329 This function is called after we know the LWP has stopped; if the LWP
2330 stopped before the expected SIGINT was delivered, then it will never have
2331 arrived. Also, if the signal was delivered to a shared queue and consumed
2332 by a different thread, it will never be delivered to this LWP. */
2335 maybe_clear_ignore_sigint (struct lwp_info
*lp
)
2337 if (!lp
->ignore_sigint
)
2340 if (!linux_nat_has_pending_sigint (lp
->ptid
.lwp ()))
2342 linux_nat_debug_printf ("Clearing bogus flag for %s",
2343 target_pid_to_str (lp
->ptid
).c_str ());
2344 lp
->ignore_sigint
= 0;
2348 /* Fetch the possible triggered data watchpoint info and store it in
2351 On some archs, like x86, that use debug registers to set
2352 watchpoints, it's possible that the way to know which watched
2353 address trapped, is to check the register that is used to select
2354 which address to watch. Problem is, between setting the watchpoint
2355 and reading back which data address trapped, the user may change
2356 the set of watchpoints, and, as a consequence, GDB changes the
2357 debug registers in the inferior. To avoid reading back a stale
2358 stopped-data-address when that happens, we cache in LP the fact
2359 that a watchpoint trapped, and the corresponding data address, as
2360 soon as we see LP stop with a SIGTRAP. If GDB changes the debug
2361 registers meanwhile, we have the cached data we can rely on. */
2364 check_stopped_by_watchpoint (struct lwp_info
*lp
)
2366 scoped_restore save_inferior_ptid
= make_scoped_restore (&inferior_ptid
);
2367 inferior_ptid
= lp
->ptid
;
2369 if (linux_target
->low_stopped_by_watchpoint ())
2371 lp
->stop_reason
= TARGET_STOPPED_BY_WATCHPOINT
;
2372 lp
->stopped_data_address_p
2373 = linux_target
->low_stopped_data_address (&lp
->stopped_data_address
);
2376 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2379 /* Returns true if the LWP had stopped for a watchpoint. */
2382 linux_nat_target::stopped_by_watchpoint ()
2384 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2386 gdb_assert (lp
!= NULL
);
2388 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2392 linux_nat_target::stopped_data_address (CORE_ADDR
*addr_p
)
2394 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2396 gdb_assert (lp
!= NULL
);
2398 *addr_p
= lp
->stopped_data_address
;
2400 return lp
->stopped_data_address_p
;
2403 /* Commonly any breakpoint / watchpoint generate only SIGTRAP. */
2406 linux_nat_target::low_status_is_event (int status
)
2408 return WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
;
2411 /* Wait until LP is stopped. */
2414 stop_wait_callback (struct lwp_info
*lp
)
2416 inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
2418 /* If this is a vfork parent, bail out, it is not going to report
2419 any SIGSTOP until the vfork is done with. */
2420 if (inf
->vfork_child
!= NULL
)
2427 status
= wait_lwp (lp
);
2431 if (lp
->ignore_sigint
&& WIFSTOPPED (status
)
2432 && WSTOPSIG (status
) == SIGINT
)
2434 lp
->ignore_sigint
= 0;
2437 ptrace (PTRACE_CONT
, lp
->ptid
.lwp (), 0, 0);
2439 linux_nat_debug_printf
2440 ("PTRACE_CONT %s, 0, 0 (%s) (discarding SIGINT)",
2441 target_pid_to_str (lp
->ptid
).c_str (),
2442 errno
? safe_strerror (errno
) : "OK");
2444 return stop_wait_callback (lp
);
2447 maybe_clear_ignore_sigint (lp
);
2449 if (WSTOPSIG (status
) != SIGSTOP
)
2451 /* The thread was stopped with a signal other than SIGSTOP. */
2453 linux_nat_debug_printf ("Pending event %s in %s",
2454 status_to_str ((int) status
),
2455 target_pid_to_str (lp
->ptid
).c_str ());
2457 /* Save the sigtrap event. */
2458 lp
->status
= status
;
2459 gdb_assert (lp
->signalled
);
2460 save_stop_reason (lp
);
2464 /* We caught the SIGSTOP that we intended to catch. */
2466 linux_nat_debug_printf ("Expected SIGSTOP caught for %s.",
2467 target_pid_to_str (lp
->ptid
).c_str ());
2471 /* If we are waiting for this stop so we can report the thread
2472 stopped then we need to record this status. Otherwise, we can
2473 now discard this stop event. */
2474 if (lp
->last_resume_kind
== resume_stop
)
2476 lp
->status
= status
;
2477 save_stop_reason (lp
);
2485 /* Return non-zero if LP has a wait status pending. Discard the
2486 pending event and resume the LWP if the event that originally
2487 caused the stop became uninteresting. */
2490 status_callback (struct lwp_info
*lp
)
2492 /* Only report a pending wait status if we pretend that this has
2493 indeed been resumed. */
2497 if (!lwp_status_pending_p (lp
))
2500 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
2501 || lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2503 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2507 pc
= regcache_read_pc (regcache
);
2509 if (pc
!= lp
->stop_pc
)
2511 linux_nat_debug_printf ("PC of %s changed. was=%s, now=%s",
2512 target_pid_to_str (lp
->ptid
).c_str (),
2513 paddress (target_gdbarch (), lp
->stop_pc
),
2514 paddress (target_gdbarch (), pc
));
2518 #if !USE_SIGTRAP_SIGINFO
2519 else if (!breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2521 linux_nat_debug_printf ("previous breakpoint of %s, at %s gone",
2522 target_pid_to_str (lp
->ptid
).c_str (),
2523 paddress (target_gdbarch (), lp
->stop_pc
));
2531 linux_nat_debug_printf ("pending event of %s cancelled.",
2532 target_pid_to_str (lp
->ptid
).c_str ());
2535 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2543 /* Count the LWP's that have had events. */
2546 count_events_callback (struct lwp_info
*lp
, int *count
)
2548 gdb_assert (count
!= NULL
);
2550 /* Select only resumed LWPs that have an event pending. */
2551 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2557 /* Select the LWP (if any) that is currently being single-stepped. */
2560 select_singlestep_lwp_callback (struct lwp_info
*lp
)
2562 if (lp
->last_resume_kind
== resume_step
2569 /* Returns true if LP has a status pending. */
2572 lwp_status_pending_p (struct lwp_info
*lp
)
2574 /* We check for lp->waitstatus in addition to lp->status, because we
2575 can have pending process exits recorded in lp->status and
2576 W_EXITCODE(0,0) happens to be 0. */
2577 return lp
->status
!= 0 || lp
->waitstatus
.kind
!= TARGET_WAITKIND_IGNORE
;
2580 /* Select the Nth LWP that has had an event. */
2583 select_event_lwp_callback (struct lwp_info
*lp
, int *selector
)
2585 gdb_assert (selector
!= NULL
);
2587 /* Select only resumed LWPs that have an event pending. */
2588 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2589 if ((*selector
)-- == 0)
2595 /* Called when the LWP stopped for a signal/trap. If it stopped for a
2596 trap check what caused it (breakpoint, watchpoint, trace, etc.),
2597 and save the result in the LWP's stop_reason field. If it stopped
2598 for a breakpoint, decrement the PC if necessary on the lwp's
2602 save_stop_reason (struct lwp_info
*lp
)
2604 struct regcache
*regcache
;
2605 struct gdbarch
*gdbarch
;
2608 #if USE_SIGTRAP_SIGINFO
2612 gdb_assert (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
);
2613 gdb_assert (lp
->status
!= 0);
2615 if (!linux_target
->low_status_is_event (lp
->status
))
2618 regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2619 gdbarch
= regcache
->arch ();
2621 pc
= regcache_read_pc (regcache
);
2622 sw_bp_pc
= pc
- gdbarch_decr_pc_after_break (gdbarch
);
2624 #if USE_SIGTRAP_SIGINFO
2625 if (linux_nat_get_siginfo (lp
->ptid
, &siginfo
))
2627 if (siginfo
.si_signo
== SIGTRAP
)
2629 if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
)
2630 && GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2632 /* The si_code is ambiguous on this arch -- check debug
2634 if (!check_stopped_by_watchpoint (lp
))
2635 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2637 else if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
))
2639 /* If we determine the LWP stopped for a SW breakpoint,
2640 trust it. Particularly don't check watchpoint
2641 registers, because, at least on s390, we'd find
2642 stopped-by-watchpoint as long as there's a watchpoint
2644 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2646 else if (GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2648 /* This can indicate either a hardware breakpoint or
2649 hardware watchpoint. Check debug registers. */
2650 if (!check_stopped_by_watchpoint (lp
))
2651 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2653 else if (siginfo
.si_code
== TRAP_TRACE
)
2655 linux_nat_debug_printf ("%s stopped by trace",
2656 target_pid_to_str (lp
->ptid
).c_str ());
2658 /* We may have single stepped an instruction that
2659 triggered a watchpoint. In that case, on some
2660 architectures (such as x86), instead of TRAP_HWBKPT,
2661 si_code indicates TRAP_TRACE, and we need to check
2662 the debug registers separately. */
2663 check_stopped_by_watchpoint (lp
);
2668 if ((!lp
->step
|| lp
->stop_pc
== sw_bp_pc
)
2669 && software_breakpoint_inserted_here_p (regcache
->aspace (),
2672 /* The LWP was either continued, or stepped a software
2673 breakpoint instruction. */
2674 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2677 if (hardware_breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2678 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2680 if (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
)
2681 check_stopped_by_watchpoint (lp
);
2684 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
)
2686 linux_nat_debug_printf ("%s stopped by software breakpoint",
2687 target_pid_to_str (lp
->ptid
).c_str ());
2689 /* Back up the PC if necessary. */
2691 regcache_write_pc (regcache
, sw_bp_pc
);
2693 /* Update this so we record the correct stop PC below. */
2696 else if (lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2698 linux_nat_debug_printf ("%s stopped by hardware breakpoint",
2699 target_pid_to_str (lp
->ptid
).c_str ());
2701 else if (lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
)
2703 linux_nat_debug_printf ("%s stopped by hardware watchpoint",
2704 target_pid_to_str (lp
->ptid
).c_str ());
2711 /* Returns true if the LWP had stopped for a software breakpoint. */
2714 linux_nat_target::stopped_by_sw_breakpoint ()
2716 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2718 gdb_assert (lp
!= NULL
);
2720 return lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
;
2723 /* Implement the supports_stopped_by_sw_breakpoint method. */
2726 linux_nat_target::supports_stopped_by_sw_breakpoint ()
2728 return USE_SIGTRAP_SIGINFO
;
2731 /* Returns true if the LWP had stopped for a hardware
2732 breakpoint/watchpoint. */
2735 linux_nat_target::stopped_by_hw_breakpoint ()
2737 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2739 gdb_assert (lp
!= NULL
);
2741 return lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
;
2744 /* Implement the supports_stopped_by_hw_breakpoint method. */
2747 linux_nat_target::supports_stopped_by_hw_breakpoint ()
2749 return USE_SIGTRAP_SIGINFO
;
2752 /* Select one LWP out of those that have events pending. */
2755 select_event_lwp (ptid_t filter
, struct lwp_info
**orig_lp
, int *status
)
2758 int random_selector
;
2759 struct lwp_info
*event_lp
= NULL
;
2761 /* Record the wait status for the original LWP. */
2762 (*orig_lp
)->status
= *status
;
2764 /* In all-stop, give preference to the LWP that is being
2765 single-stepped. There will be at most one, and it will be the
2766 LWP that the core is most interested in. If we didn't do this,
2767 then we'd have to handle pending step SIGTRAPs somehow in case
2768 the core later continues the previously-stepped thread, as
2769 otherwise we'd report the pending SIGTRAP then, and the core, not
2770 having stepped the thread, wouldn't understand what the trap was
2771 for, and therefore would report it to the user as a random
2773 if (!target_is_non_stop_p ())
2775 event_lp
= iterate_over_lwps (filter
, select_singlestep_lwp_callback
);
2776 if (event_lp
!= NULL
)
2778 linux_nat_debug_printf ("Select single-step %s",
2779 target_pid_to_str (event_lp
->ptid
).c_str ());
2783 if (event_lp
== NULL
)
2785 /* Pick one at random, out of those which have had events. */
2787 /* First see how many events we have. */
2788 iterate_over_lwps (filter
,
2789 [&] (struct lwp_info
*info
)
2791 return count_events_callback (info
, &num_events
);
2793 gdb_assert (num_events
> 0);
2795 /* Now randomly pick a LWP out of those that have had
2797 random_selector
= (int)
2798 ((num_events
* (double) rand ()) / (RAND_MAX
+ 1.0));
2801 linux_nat_debug_printf ("Found %d events, selecting #%d",
2802 num_events
, random_selector
);
2805 = (iterate_over_lwps
2807 [&] (struct lwp_info
*info
)
2809 return select_event_lwp_callback (info
,
2814 if (event_lp
!= NULL
)
2816 /* Switch the event LWP. */
2817 *orig_lp
= event_lp
;
2818 *status
= event_lp
->status
;
2821 /* Flush the wait status for the event LWP. */
2822 (*orig_lp
)->status
= 0;
2825 /* Return non-zero if LP has been resumed. */
2828 resumed_callback (struct lwp_info
*lp
)
2833 /* Check if we should go on and pass this event to common code.
2834 Return the affected lwp if we should, or NULL otherwise. */
2836 static struct lwp_info
*
2837 linux_nat_filter_event (int lwpid
, int status
)
2839 struct lwp_info
*lp
;
2840 int event
= linux_ptrace_get_extended_event (status
);
2842 lp
= find_lwp_pid (ptid_t (lwpid
));
2844 /* Check for stop events reported by a process we didn't already
2845 know about - anything not already in our LWP list.
2847 If we're expecting to receive stopped processes after
2848 fork, vfork, and clone events, then we'll just add the
2849 new one to our list and go back to waiting for the event
2850 to be reported - the stopped process might be returned
2851 from waitpid before or after the event is.
2853 But note the case of a non-leader thread exec'ing after the
2854 leader having exited, and gone from our lists. The non-leader
2855 thread changes its tid to the tgid. */
2857 if (WIFSTOPPED (status
) && lp
== NULL
2858 && (WSTOPSIG (status
) == SIGTRAP
&& event
== PTRACE_EVENT_EXEC
))
2860 /* A multi-thread exec after we had seen the leader exiting. */
2861 linux_nat_debug_printf ("Re-adding thread group leader LWP %d.", lwpid
);
2863 lp
= add_lwp (ptid_t (lwpid
, lwpid
, 0));
2866 add_thread (linux_target
, lp
->ptid
);
2869 if (WIFSTOPPED (status
) && !lp
)
2871 linux_nat_debug_printf ("saving LWP %ld status %s in stopped_pids list",
2872 (long) lwpid
, status_to_str (status
));
2873 add_to_pid_list (&stopped_pids
, lwpid
, status
);
2877 /* Make sure we don't report an event for the exit of an LWP not in
2878 our list, i.e. not part of the current process. This can happen
2879 if we detach from a program we originally forked and then it
2881 if (!WIFSTOPPED (status
) && !lp
)
2884 /* This LWP is stopped now. (And if dead, this prevents it from
2885 ever being continued.) */
2888 if (WIFSTOPPED (status
) && lp
->must_set_ptrace_flags
)
2890 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2891 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
2893 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
2894 lp
->must_set_ptrace_flags
= 0;
2897 /* Handle GNU/Linux's syscall SIGTRAPs. */
2898 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
2900 /* No longer need the sysgood bit. The ptrace event ends up
2901 recorded in lp->waitstatus if we care for it. We can carry
2902 on handling the event like a regular SIGTRAP from here
2904 status
= W_STOPCODE (SIGTRAP
);
2905 if (linux_handle_syscall_trap (lp
, 0))
2910 /* Almost all other ptrace-stops are known to be outside of system
2911 calls, with further exceptions in linux_handle_extended_wait. */
2912 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
2915 /* Handle GNU/Linux's extended waitstatus for trace events. */
2916 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
2917 && linux_is_extended_waitstatus (status
))
2919 linux_nat_debug_printf ("Handling extended status 0x%06x", status
);
2921 if (linux_handle_extended_wait (lp
, status
))
2925 /* Check if the thread has exited. */
2926 if (WIFEXITED (status
) || WIFSIGNALED (status
))
2928 if (!report_thread_events
2929 && num_lwps (lp
->ptid
.pid ()) > 1)
2931 linux_nat_debug_printf ("%s exited.",
2932 target_pid_to_str (lp
->ptid
).c_str ());
2934 /* If there is at least one more LWP, then the exit signal
2935 was not the end of the debugged application and should be
2941 /* Note that even if the leader was ptrace-stopped, it can still
2942 exit, if e.g., some other thread brings down the whole
2943 process (calls `exit'). So don't assert that the lwp is
2945 linux_nat_debug_printf ("LWP %ld exited (resumed=%d)",
2946 lp
->ptid
.lwp (), lp
->resumed
);
2948 /* Dead LWP's aren't expected to reported a pending sigstop. */
2951 /* Store the pending event in the waitstatus, because
2952 W_EXITCODE(0,0) == 0. */
2953 store_waitstatus (&lp
->waitstatus
, status
);
2957 /* Make sure we don't report a SIGSTOP that we sent ourselves in
2958 an attempt to stop an LWP. */
2960 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGSTOP
)
2964 if (lp
->last_resume_kind
== resume_stop
)
2966 linux_nat_debug_printf ("resume_stop SIGSTOP caught for %s.",
2967 target_pid_to_str (lp
->ptid
).c_str ());
2971 /* This is a delayed SIGSTOP. Filter out the event. */
2973 linux_nat_debug_printf
2974 ("%s %s, 0, 0 (discard delayed SIGSTOP)",
2975 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
2976 target_pid_to_str (lp
->ptid
).c_str ());
2978 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2979 gdb_assert (lp
->resumed
);
2984 /* Make sure we don't report a SIGINT that we have already displayed
2985 for another thread. */
2986 if (lp
->ignore_sigint
2987 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGINT
)
2989 linux_nat_debug_printf ("Delayed SIGINT caught for %s.",
2990 target_pid_to_str (lp
->ptid
).c_str ());
2992 /* This is a delayed SIGINT. */
2993 lp
->ignore_sigint
= 0;
2995 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2996 linux_nat_debug_printf ("%s %s, 0, 0 (discard SIGINT)",
2997 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
2998 target_pid_to_str (lp
->ptid
).c_str ());
2999 gdb_assert (lp
->resumed
);
3001 /* Discard the event. */
3005 /* Don't report signals that GDB isn't interested in, such as
3006 signals that are neither printed nor stopped upon. Stopping all
3007 threads can be a bit time-consuming, so if we want decent
3008 performance with heavily multi-threaded programs, especially when
3009 they're using a high frequency timer, we'd better avoid it if we
3011 if (WIFSTOPPED (status
))
3013 enum gdb_signal signo
= gdb_signal_from_host (WSTOPSIG (status
));
3015 if (!target_is_non_stop_p ())
3017 /* Only do the below in all-stop, as we currently use SIGSTOP
3018 to implement target_stop (see linux_nat_stop) in
3020 if (signo
== GDB_SIGNAL_INT
&& signal_pass_state (signo
) == 0)
3022 /* If ^C/BREAK is typed at the tty/console, SIGINT gets
3023 forwarded to the entire process group, that is, all LWPs
3024 will receive it - unless they're using CLONE_THREAD to
3025 share signals. Since we only want to report it once, we
3026 mark it as ignored for all LWPs except this one. */
3027 iterate_over_lwps (ptid_t (lp
->ptid
.pid ()), set_ignore_sigint
);
3028 lp
->ignore_sigint
= 0;
3031 maybe_clear_ignore_sigint (lp
);
3034 /* When using hardware single-step, we need to report every signal.
3035 Otherwise, signals in pass_mask may be short-circuited
3036 except signals that might be caused by a breakpoint, or SIGSTOP
3037 if we sent the SIGSTOP and are waiting for it to arrive. */
3039 && WSTOPSIG (status
) && sigismember (&pass_mask
, WSTOPSIG (status
))
3040 && (WSTOPSIG (status
) != SIGSTOP
3041 || !find_thread_ptid (linux_target
, lp
->ptid
)->stop_requested
)
3042 && !linux_wstatus_maybe_breakpoint (status
))
3044 linux_resume_one_lwp (lp
, lp
->step
, signo
);
3045 linux_nat_debug_printf
3046 ("%s %s, %s (preempt 'handle')",
3047 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
3048 target_pid_to_str (lp
->ptid
).c_str (),
3049 (signo
!= GDB_SIGNAL_0
3050 ? strsignal (gdb_signal_to_host (signo
)) : "0"));
3055 /* An interesting event. */
3057 lp
->status
= status
;
3058 save_stop_reason (lp
);
3062 /* Detect zombie thread group leaders, and "exit" them. We can't reap
3063 their exits until all other threads in the group have exited. */
3066 check_zombie_leaders (void)
3068 for (inferior
*inf
: all_inferiors ())
3070 struct lwp_info
*leader_lp
;
3075 leader_lp
= find_lwp_pid (ptid_t (inf
->pid
));
3076 if (leader_lp
!= NULL
3077 /* Check if there are other threads in the group, as we may
3078 have raced with the inferior simply exiting. */
3079 && num_lwps (inf
->pid
) > 1
3080 && linux_proc_pid_is_zombie (inf
->pid
))
3082 linux_nat_debug_printf ("Thread group leader %d zombie "
3083 "(it exited, or another thread execd).",
3086 /* A leader zombie can mean one of two things:
3088 - It exited, and there's an exit status pending
3089 available, or only the leader exited (not the whole
3090 program). In the latter case, we can't waitpid the
3091 leader's exit status until all other threads are gone.
3093 - There are 3 or more threads in the group, and a thread
3094 other than the leader exec'd. See comments on exec
3095 events at the top of the file. We could try
3096 distinguishing the exit and exec cases, by waiting once
3097 more, and seeing if something comes out, but it doesn't
3098 sound useful. The previous leader _does_ go away, and
3099 we'll re-add the new one once we see the exec event
3100 (which is just the same as what would happen if the
3101 previous leader did exit voluntarily before some other
3104 linux_nat_debug_printf ("Thread group leader %d vanished.", inf
->pid
);
3105 exit_lwp (leader_lp
);
3110 /* Convenience function that is called when the kernel reports an exit
3111 event. This decides whether to report the event to GDB as a
3112 process exit event, a thread exit event, or to suppress the
3116 filter_exit_event (struct lwp_info
*event_child
,
3117 struct target_waitstatus
*ourstatus
)
3119 ptid_t ptid
= event_child
->ptid
;
3121 if (num_lwps (ptid
.pid ()) > 1)
3123 if (report_thread_events
)
3124 ourstatus
->kind
= TARGET_WAITKIND_THREAD_EXITED
;
3126 ourstatus
->kind
= TARGET_WAITKIND_IGNORE
;
3128 exit_lwp (event_child
);
3135 linux_nat_wait_1 (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3136 target_wait_flags target_options
)
3139 enum resume_kind last_resume_kind
;
3140 struct lwp_info
*lp
;
3143 linux_nat_debug_printf ("enter");
3145 /* The first time we get here after starting a new inferior, we may
3146 not have added it to the LWP list yet - this is the earliest
3147 moment at which we know its PID. */
3148 if (ptid
.is_pid () && find_lwp_pid (ptid
) == nullptr)
3150 ptid_t
lwp_ptid (ptid
.pid (), ptid
.pid ());
3152 /* Upgrade the main thread's ptid. */
3153 thread_change_ptid (linux_target
, ptid
, lwp_ptid
);
3154 lp
= add_initial_lwp (lwp_ptid
);
3158 /* Make sure SIGCHLD is blocked until the sigsuspend below. */
3159 block_child_signals (&prev_mask
);
3161 /* First check if there is a LWP with a wait status pending. */
3162 lp
= iterate_over_lwps (ptid
, status_callback
);
3165 linux_nat_debug_printf ("Using pending wait status %s for %s.",
3166 status_to_str (lp
->status
),
3167 target_pid_to_str (lp
->ptid
).c_str ());
3170 /* But if we don't find a pending event, we'll have to wait. Always
3171 pull all events out of the kernel. We'll randomly select an
3172 event LWP out of all that have events, to prevent starvation. */
3178 /* Always use -1 and WNOHANG, due to couple of a kernel/ptrace
3181 - If the thread group leader exits while other threads in the
3182 thread group still exist, waitpid(TGID, ...) hangs. That
3183 waitpid won't return an exit status until the other threads
3184 in the group are reaped.
3186 - When a non-leader thread execs, that thread just vanishes
3187 without reporting an exit (so we'd hang if we waited for it
3188 explicitly in that case). The exec event is reported to
3192 lwpid
= my_waitpid (-1, &status
, __WALL
| WNOHANG
);
3194 linux_nat_debug_printf ("waitpid(-1, ...) returned %d, %s",
3196 errno
? safe_strerror (errno
) : "ERRNO-OK");
3200 linux_nat_debug_printf ("waitpid %ld received %s",
3201 (long) lwpid
, status_to_str (status
));
3203 linux_nat_filter_event (lwpid
, status
);
3204 /* Retry until nothing comes out of waitpid. A single
3205 SIGCHLD can indicate more than one child stopped. */
3209 /* Now that we've pulled all events out of the kernel, resume
3210 LWPs that don't have an interesting event to report. */
3211 iterate_over_lwps (minus_one_ptid
,
3212 [] (struct lwp_info
*info
)
3214 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
3217 /* ... and find an LWP with a status to report to the core, if
3219 lp
= iterate_over_lwps (ptid
, status_callback
);
3223 /* Check for zombie thread group leaders. Those can't be reaped
3224 until all other threads in the thread group are. */
3225 check_zombie_leaders ();
3227 /* If there are no resumed children left, bail. We'd be stuck
3228 forever in the sigsuspend call below otherwise. */
3229 if (iterate_over_lwps (ptid
, resumed_callback
) == NULL
)
3231 linux_nat_debug_printf ("exit (no resumed LWP)");
3233 ourstatus
->kind
= TARGET_WAITKIND_NO_RESUMED
;
3235 restore_child_signals_mask (&prev_mask
);
3236 return minus_one_ptid
;
3239 /* No interesting event to report to the core. */
3241 if (target_options
& TARGET_WNOHANG
)
3243 linux_nat_debug_printf ("exit (ignore)");
3245 ourstatus
->kind
= TARGET_WAITKIND_IGNORE
;
3246 restore_child_signals_mask (&prev_mask
);
3247 return minus_one_ptid
;
3250 /* We shouldn't end up here unless we want to try again. */
3251 gdb_assert (lp
== NULL
);
3253 /* Block until we get an event reported with SIGCHLD. */
3259 status
= lp
->status
;
3262 if (!target_is_non_stop_p ())
3264 /* Now stop all other LWP's ... */
3265 iterate_over_lwps (minus_one_ptid
, stop_callback
);
3267 /* ... and wait until all of them have reported back that
3268 they're no longer running. */
3269 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
3272 /* If we're not waiting for a specific LWP, choose an event LWP from
3273 among those that have had events. Giving equal priority to all
3274 LWPs that have had events helps prevent starvation. */
3275 if (ptid
== minus_one_ptid
|| ptid
.is_pid ())
3276 select_event_lwp (ptid
, &lp
, &status
);
3278 gdb_assert (lp
!= NULL
);
3280 /* Now that we've selected our final event LWP, un-adjust its PC if
3281 it was a software breakpoint, and we can't reliably support the
3282 "stopped by software breakpoint" stop reason. */
3283 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
3284 && !USE_SIGTRAP_SIGINFO
)
3286 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3287 struct gdbarch
*gdbarch
= regcache
->arch ();
3288 int decr_pc
= gdbarch_decr_pc_after_break (gdbarch
);
3294 pc
= regcache_read_pc (regcache
);
3295 regcache_write_pc (regcache
, pc
+ decr_pc
);
3299 /* We'll need this to determine whether to report a SIGSTOP as
3300 GDB_SIGNAL_0. Need to take a copy because resume_clear_callback
3302 last_resume_kind
= lp
->last_resume_kind
;
3304 if (!target_is_non_stop_p ())
3306 /* In all-stop, from the core's perspective, all LWPs are now
3307 stopped until a new resume action is sent over. */
3308 iterate_over_lwps (minus_one_ptid
, resume_clear_callback
);
3312 resume_clear_callback (lp
);
3315 if (linux_target
->low_status_is_event (status
))
3317 linux_nat_debug_printf ("trap ptid is %s.",
3318 target_pid_to_str (lp
->ptid
).c_str ());
3321 if (lp
->waitstatus
.kind
!= TARGET_WAITKIND_IGNORE
)
3323 *ourstatus
= lp
->waitstatus
;
3324 lp
->waitstatus
.kind
= TARGET_WAITKIND_IGNORE
;
3327 store_waitstatus (ourstatus
, status
);
3329 linux_nat_debug_printf ("exit");
3331 restore_child_signals_mask (&prev_mask
);
3333 if (last_resume_kind
== resume_stop
3334 && ourstatus
->kind
== TARGET_WAITKIND_STOPPED
3335 && WSTOPSIG (status
) == SIGSTOP
)
3337 /* A thread that has been requested to stop by GDB with
3338 target_stop, and it stopped cleanly, so report as SIG0. The
3339 use of SIGSTOP is an implementation detail. */
3340 ourstatus
->value
.sig
= GDB_SIGNAL_0
;
3343 if (ourstatus
->kind
== TARGET_WAITKIND_EXITED
3344 || ourstatus
->kind
== TARGET_WAITKIND_SIGNALLED
)
3347 lp
->core
= linux_common_core_of_thread (lp
->ptid
);
3349 if (ourstatus
->kind
== TARGET_WAITKIND_EXITED
)
3350 return filter_exit_event (lp
, ourstatus
);
3355 /* Resume LWPs that are currently stopped without any pending status
3356 to report, but are resumed from the core's perspective. */
3359 resume_stopped_resumed_lwps (struct lwp_info
*lp
, const ptid_t wait_ptid
)
3363 linux_nat_debug_printf ("NOT resuming LWP %s, not stopped",
3364 target_pid_to_str (lp
->ptid
).c_str ());
3366 else if (!lp
->resumed
)
3368 linux_nat_debug_printf ("NOT resuming LWP %s, not resumed",
3369 target_pid_to_str (lp
->ptid
).c_str ());
3371 else if (lwp_status_pending_p (lp
))
3373 linux_nat_debug_printf ("NOT resuming LWP %s, has pending status",
3374 target_pid_to_str (lp
->ptid
).c_str ());
3378 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3379 struct gdbarch
*gdbarch
= regcache
->arch ();
3383 CORE_ADDR pc
= regcache_read_pc (regcache
);
3384 int leave_stopped
= 0;
3386 /* Don't bother if there's a breakpoint at PC that we'd hit
3387 immediately, and we're not waiting for this LWP. */
3388 if (!lp
->ptid
.matches (wait_ptid
))
3390 if (breakpoint_inserted_here_p (regcache
->aspace (), pc
))
3396 linux_nat_debug_printf
3397 ("resuming stopped-resumed LWP %s at %s: step=%d",
3398 target_pid_to_str (lp
->ptid
).c_str (), paddress (gdbarch
, pc
),
3401 linux_resume_one_lwp_throw (lp
, lp
->step
, GDB_SIGNAL_0
);
3404 catch (const gdb_exception_error
&ex
)
3406 if (!check_ptrace_stopped_lwp_gone (lp
))
3415 linux_nat_target::wait (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3416 target_wait_flags target_options
)
3420 linux_nat_debug_printf ("[%s], [%s]", target_pid_to_str (ptid
).c_str (),
3421 target_options_to_string (target_options
).c_str ());
3423 /* Flush the async file first. */
3424 if (target_is_async_p ())
3425 async_file_flush ();
3427 /* Resume LWPs that are currently stopped without any pending status
3428 to report, but are resumed from the core's perspective. LWPs get
3429 in this state if we find them stopping at a time we're not
3430 interested in reporting the event (target_wait on a
3431 specific_process, for example, see linux_nat_wait_1), and
3432 meanwhile the event became uninteresting. Don't bother resuming
3433 LWPs we're not going to wait for if they'd stop immediately. */
3434 if (target_is_non_stop_p ())
3435 iterate_over_lwps (minus_one_ptid
,
3436 [=] (struct lwp_info
*info
)
3438 return resume_stopped_resumed_lwps (info
, ptid
);
3441 event_ptid
= linux_nat_wait_1 (ptid
, ourstatus
, target_options
);
3443 /* If we requested any event, and something came out, assume there
3444 may be more. If we requested a specific lwp or process, also
3445 assume there may be more. */
3446 if (target_is_async_p ()
3447 && ((ourstatus
->kind
!= TARGET_WAITKIND_IGNORE
3448 && ourstatus
->kind
!= TARGET_WAITKIND_NO_RESUMED
)
3449 || ptid
!= minus_one_ptid
))
3458 kill_one_lwp (pid_t pid
)
3460 /* PTRACE_KILL may resume the inferior. Send SIGKILL first. */
3463 kill_lwp (pid
, SIGKILL
);
3465 if (debug_linux_nat
)
3467 int save_errno
= errno
;
3469 linux_nat_debug_printf
3470 ("kill (SIGKILL) %ld, 0, 0 (%s)", (long) pid
,
3471 save_errno
!= 0 ? safe_strerror (save_errno
) : "OK");
3474 /* Some kernels ignore even SIGKILL for processes under ptrace. */
3477 ptrace (PTRACE_KILL
, pid
, 0, 0);
3478 if (debug_linux_nat
)
3480 int save_errno
= errno
;
3482 linux_nat_debug_printf
3483 ("PTRACE_KILL %ld, 0, 0 (%s)", (long) pid
,
3484 save_errno
? safe_strerror (save_errno
) : "OK");
3488 /* Wait for an LWP to die. */
3491 kill_wait_one_lwp (pid_t pid
)
3495 /* We must make sure that there are no pending events (delayed
3496 SIGSTOPs, pending SIGTRAPs, etc.) to make sure the current
3497 program doesn't interfere with any following debugging session. */
3501 res
= my_waitpid (pid
, NULL
, __WALL
);
3502 if (res
!= (pid_t
) -1)
3504 linux_nat_debug_printf ("wait %ld received unknown.", (long) pid
);
3506 /* The Linux kernel sometimes fails to kill a thread
3507 completely after PTRACE_KILL; that goes from the stop
3508 point in do_fork out to the one in get_signal_to_deliver
3509 and waits again. So kill it again. */
3515 gdb_assert (res
== -1 && errno
== ECHILD
);
3518 /* Callback for iterate_over_lwps. */
3521 kill_callback (struct lwp_info
*lp
)
3523 kill_one_lwp (lp
->ptid
.lwp ());
3527 /* Callback for iterate_over_lwps. */
3530 kill_wait_callback (struct lwp_info
*lp
)
3532 kill_wait_one_lwp (lp
->ptid
.lwp ());
3536 /* Kill the fork children of any threads of inferior INF that are
3537 stopped at a fork event. */
3540 kill_unfollowed_fork_children (struct inferior
*inf
)
3542 for (thread_info
*thread
: inf
->non_exited_threads ())
3544 struct target_waitstatus
*ws
= &thread
->pending_follow
;
3546 if (ws
->kind
== TARGET_WAITKIND_FORKED
3547 || ws
->kind
== TARGET_WAITKIND_VFORKED
)
3549 ptid_t child_ptid
= ws
->value
.related_pid
;
3550 int child_pid
= child_ptid
.pid ();
3551 int child_lwp
= child_ptid
.lwp ();
3553 kill_one_lwp (child_lwp
);
3554 kill_wait_one_lwp (child_lwp
);
3556 /* Let the arch-specific native code know this process is
3558 linux_target
->low_forget_process (child_pid
);
3564 linux_nat_target::kill ()
3566 /* If we're stopped while forking and we haven't followed yet,
3567 kill the other task. We need to do this first because the
3568 parent will be sleeping if this is a vfork. */
3569 kill_unfollowed_fork_children (current_inferior ());
3571 if (forks_exist_p ())
3572 linux_fork_killall ();
3575 ptid_t ptid
= ptid_t (inferior_ptid
.pid ());
3577 /* Stop all threads before killing them, since ptrace requires
3578 that the thread is stopped to successfully PTRACE_KILL. */
3579 iterate_over_lwps (ptid
, stop_callback
);
3580 /* ... and wait until all of them have reported back that
3581 they're no longer running. */
3582 iterate_over_lwps (ptid
, stop_wait_callback
);
3584 /* Kill all LWP's ... */
3585 iterate_over_lwps (ptid
, kill_callback
);
3587 /* ... and wait until we've flushed all events. */
3588 iterate_over_lwps (ptid
, kill_wait_callback
);
3591 target_mourn_inferior (inferior_ptid
);
3595 linux_nat_target::mourn_inferior ()
3597 int pid
= inferior_ptid
.pid ();
3599 purge_lwp_list (pid
);
3601 if (! forks_exist_p ())
3602 /* Normal case, no other forks available. */
3603 inf_ptrace_target::mourn_inferior ();
3605 /* Multi-fork case. The current inferior_ptid has exited, but
3606 there are other viable forks to debug. Delete the exiting
3607 one and context-switch to the first available. */
3608 linux_fork_mourn_inferior ();
3610 /* Let the arch-specific native code know this process is gone. */
3611 linux_target
->low_forget_process (pid
);
3614 /* Convert a native/host siginfo object, into/from the siginfo in the
3615 layout of the inferiors' architecture. */
3618 siginfo_fixup (siginfo_t
*siginfo
, gdb_byte
*inf_siginfo
, int direction
)
3620 /* If the low target didn't do anything, then just do a straight
3622 if (!linux_target
->low_siginfo_fixup (siginfo
, inf_siginfo
, direction
))
3625 memcpy (siginfo
, inf_siginfo
, sizeof (siginfo_t
));
3627 memcpy (inf_siginfo
, siginfo
, sizeof (siginfo_t
));
3631 static enum target_xfer_status
3632 linux_xfer_siginfo (enum target_object object
,
3633 const char *annex
, gdb_byte
*readbuf
,
3634 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3635 ULONGEST
*xfered_len
)
3639 gdb_byte inf_siginfo
[sizeof (siginfo_t
)];
3641 gdb_assert (object
== TARGET_OBJECT_SIGNAL_INFO
);
3642 gdb_assert (readbuf
|| writebuf
);
3644 pid
= inferior_ptid
.lwp ();
3646 pid
= inferior_ptid
.pid ();
3648 if (offset
> sizeof (siginfo
))
3649 return TARGET_XFER_E_IO
;
3652 ptrace (PTRACE_GETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, &siginfo
);
3654 return TARGET_XFER_E_IO
;
3656 /* When GDB is built as a 64-bit application, ptrace writes into
3657 SIGINFO an object with 64-bit layout. Since debugging a 32-bit
3658 inferior with a 64-bit GDB should look the same as debugging it
3659 with a 32-bit GDB, we need to convert it. GDB core always sees
3660 the converted layout, so any read/write will have to be done
3662 siginfo_fixup (&siginfo
, inf_siginfo
, 0);
3664 if (offset
+ len
> sizeof (siginfo
))
3665 len
= sizeof (siginfo
) - offset
;
3667 if (readbuf
!= NULL
)
3668 memcpy (readbuf
, inf_siginfo
+ offset
, len
);
3671 memcpy (inf_siginfo
+ offset
, writebuf
, len
);
3673 /* Convert back to ptrace layout before flushing it out. */
3674 siginfo_fixup (&siginfo
, inf_siginfo
, 1);
3677 ptrace (PTRACE_SETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, &siginfo
);
3679 return TARGET_XFER_E_IO
;
3683 return TARGET_XFER_OK
;
3686 static enum target_xfer_status
3687 linux_nat_xfer_osdata (enum target_object object
,
3688 const char *annex
, gdb_byte
*readbuf
,
3689 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3690 ULONGEST
*xfered_len
);
3692 static enum target_xfer_status
3693 linux_proc_xfer_partial (enum target_object object
,
3694 const char *annex
, gdb_byte
*readbuf
,
3695 const gdb_byte
*writebuf
,
3696 ULONGEST offset
, LONGEST len
, ULONGEST
*xfered_len
);
3698 enum target_xfer_status
3699 linux_nat_target::xfer_partial (enum target_object object
,
3700 const char *annex
, gdb_byte
*readbuf
,
3701 const gdb_byte
*writebuf
,
3702 ULONGEST offset
, ULONGEST len
, ULONGEST
*xfered_len
)
3704 enum target_xfer_status xfer
;
3706 if (object
== TARGET_OBJECT_SIGNAL_INFO
)
3707 return linux_xfer_siginfo (object
, annex
, readbuf
, writebuf
,
3708 offset
, len
, xfered_len
);
3710 /* The target is connected but no live inferior is selected. Pass
3711 this request down to a lower stratum (e.g., the executable
3713 if (object
== TARGET_OBJECT_MEMORY
&& inferior_ptid
== null_ptid
)
3714 return TARGET_XFER_EOF
;
3716 if (object
== TARGET_OBJECT_AUXV
)
3717 return memory_xfer_auxv (this, object
, annex
, readbuf
, writebuf
,
3718 offset
, len
, xfered_len
);
3720 if (object
== TARGET_OBJECT_OSDATA
)
3721 return linux_nat_xfer_osdata (object
, annex
, readbuf
, writebuf
,
3722 offset
, len
, xfered_len
);
3724 /* GDB calculates all addresses in the largest possible address
3726 The address width must be masked before its final use - either by
3727 linux_proc_xfer_partial or inf_ptrace_target::xfer_partial.
3729 Compare ADDR_BIT first to avoid a compiler warning on shift overflow. */
3731 if (object
== TARGET_OBJECT_MEMORY
)
3733 int addr_bit
= gdbarch_addr_bit (target_gdbarch ());
3735 if (addr_bit
< (sizeof (ULONGEST
) * HOST_CHAR_BIT
))
3736 offset
&= ((ULONGEST
) 1 << addr_bit
) - 1;
3739 xfer
= linux_proc_xfer_partial (object
, annex
, readbuf
, writebuf
,
3740 offset
, len
, xfered_len
);
3741 if (xfer
!= TARGET_XFER_EOF
)
3744 return inf_ptrace_target::xfer_partial (object
, annex
, readbuf
, writebuf
,
3745 offset
, len
, xfered_len
);
3749 linux_nat_target::thread_alive (ptid_t ptid
)
3751 /* As long as a PTID is in lwp list, consider it alive. */
3752 return find_lwp_pid (ptid
) != NULL
;
3755 /* Implement the to_update_thread_list target method for this
3759 linux_nat_target::update_thread_list ()
3761 struct lwp_info
*lwp
;
3763 /* We add/delete threads from the list as clone/exit events are
3764 processed, so just try deleting exited threads still in the
3766 delete_exited_threads ();
3768 /* Update the processor core that each lwp/thread was last seen
3772 /* Avoid accessing /proc if the thread hasn't run since we last
3773 time we fetched the thread's core. Accessing /proc becomes
3774 noticeably expensive when we have thousands of LWPs. */
3775 if (lwp
->core
== -1)
3776 lwp
->core
= linux_common_core_of_thread (lwp
->ptid
);
3781 linux_nat_target::pid_to_str (ptid_t ptid
)
3784 && (ptid
.pid () != ptid
.lwp ()
3785 || num_lwps (ptid
.pid ()) > 1))
3786 return string_printf ("LWP %ld", ptid
.lwp ());
3788 return normal_pid_to_str (ptid
);
3792 linux_nat_target::thread_name (struct thread_info
*thr
)
3794 return linux_proc_tid_get_name (thr
->ptid
);
3797 /* Accepts an integer PID; Returns a string representing a file that
3798 can be opened to get the symbols for the child process. */
3801 linux_nat_target::pid_to_exec_file (int pid
)
3803 return linux_proc_pid_to_exec_file (pid
);
3806 /* Implement the to_xfer_partial target method using /proc/<pid>/mem.
3807 Because we can use a single read/write call, this can be much more
3808 efficient than banging away at PTRACE_PEEKTEXT. */
3810 static enum target_xfer_status
3811 linux_proc_xfer_partial (enum target_object object
,
3812 const char *annex
, gdb_byte
*readbuf
,
3813 const gdb_byte
*writebuf
,
3814 ULONGEST offset
, LONGEST len
, ULONGEST
*xfered_len
)
3820 if (object
!= TARGET_OBJECT_MEMORY
)
3821 return TARGET_XFER_EOF
;
3823 /* Don't bother for one word. */
3824 if (len
< 3 * sizeof (long))
3825 return TARGET_XFER_EOF
;
3827 /* We could keep this file open and cache it - possibly one per
3828 thread. That requires some juggling, but is even faster. */
3829 xsnprintf (filename
, sizeof filename
, "/proc/%ld/mem",
3830 inferior_ptid
.lwp ());
3831 fd
= gdb_open_cloexec (filename
, ((readbuf
? O_RDONLY
: O_WRONLY
)
3834 return TARGET_XFER_EOF
;
3836 /* Use pread64/pwrite64 if available, since they save a syscall and can
3837 handle 64-bit offsets even on 32-bit platforms (for instance, SPARC
3838 debugging a SPARC64 application). */
3840 ret
= (readbuf
? pread64 (fd
, readbuf
, len
, offset
)
3841 : pwrite64 (fd
, writebuf
, len
, offset
));
3843 ret
= lseek (fd
, offset
, SEEK_SET
);
3845 ret
= (readbuf
? read (fd
, readbuf
, len
)
3846 : write (fd
, writebuf
, len
));
3851 if (ret
== -1 || ret
== 0)
3852 return TARGET_XFER_EOF
;
3856 return TARGET_XFER_OK
;
3861 /* Parse LINE as a signal set and add its set bits to SIGS. */
3864 add_line_to_sigset (const char *line
, sigset_t
*sigs
)
3866 int len
= strlen (line
) - 1;
3870 if (line
[len
] != '\n')
3871 error (_("Could not parse signal set: %s"), line
);
3879 if (*p
>= '0' && *p
<= '9')
3881 else if (*p
>= 'a' && *p
<= 'f')
3882 digit
= *p
- 'a' + 10;
3884 error (_("Could not parse signal set: %s"), line
);
3889 sigaddset (sigs
, signum
+ 1);
3891 sigaddset (sigs
, signum
+ 2);
3893 sigaddset (sigs
, signum
+ 3);
3895 sigaddset (sigs
, signum
+ 4);
3901 /* Find process PID's pending signals from /proc/pid/status and set
3905 linux_proc_pending_signals (int pid
, sigset_t
*pending
,
3906 sigset_t
*blocked
, sigset_t
*ignored
)
3908 char buffer
[PATH_MAX
], fname
[PATH_MAX
];
3910 sigemptyset (pending
);
3911 sigemptyset (blocked
);
3912 sigemptyset (ignored
);
3913 xsnprintf (fname
, sizeof fname
, "/proc/%d/status", pid
);
3914 gdb_file_up procfile
= gdb_fopen_cloexec (fname
, "r");
3915 if (procfile
== NULL
)
3916 error (_("Could not open %s"), fname
);
3918 while (fgets (buffer
, PATH_MAX
, procfile
.get ()) != NULL
)
3920 /* Normal queued signals are on the SigPnd line in the status
3921 file. However, 2.6 kernels also have a "shared" pending
3922 queue for delivering signals to a thread group, so check for
3925 Unfortunately some Red Hat kernels include the shared pending
3926 queue but not the ShdPnd status field. */
3928 if (startswith (buffer
, "SigPnd:\t"))
3929 add_line_to_sigset (buffer
+ 8, pending
);
3930 else if (startswith (buffer
, "ShdPnd:\t"))
3931 add_line_to_sigset (buffer
+ 8, pending
);
3932 else if (startswith (buffer
, "SigBlk:\t"))
3933 add_line_to_sigset (buffer
+ 8, blocked
);
3934 else if (startswith (buffer
, "SigIgn:\t"))
3935 add_line_to_sigset (buffer
+ 8, ignored
);
3939 static enum target_xfer_status
3940 linux_nat_xfer_osdata (enum target_object object
,
3941 const char *annex
, gdb_byte
*readbuf
,
3942 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3943 ULONGEST
*xfered_len
)
3945 gdb_assert (object
== TARGET_OBJECT_OSDATA
);
3947 *xfered_len
= linux_common_xfer_osdata (annex
, readbuf
, offset
, len
);
3948 if (*xfered_len
== 0)
3949 return TARGET_XFER_EOF
;
3951 return TARGET_XFER_OK
;
3954 std::vector
<static_tracepoint_marker
>
3955 linux_nat_target::static_tracepoint_markers_by_strid (const char *strid
)
3957 char s
[IPA_CMD_BUF_SIZE
];
3958 int pid
= inferior_ptid
.pid ();
3959 std::vector
<static_tracepoint_marker
> markers
;
3961 ptid_t ptid
= ptid_t (pid
, 0, 0);
3962 static_tracepoint_marker marker
;
3967 memcpy (s
, "qTfSTM", sizeof ("qTfSTM"));
3968 s
[sizeof ("qTfSTM")] = 0;
3970 agent_run_command (pid
, s
, strlen (s
) + 1);
3973 SCOPE_EXIT
{ target_continue_no_signal (ptid
); };
3979 parse_static_tracepoint_marker_definition (p
, &p
, &marker
);
3981 if (strid
== NULL
|| marker
.str_id
== strid
)
3982 markers
.push_back (std::move (marker
));
3984 while (*p
++ == ','); /* comma-separated list */
3986 memcpy (s
, "qTsSTM", sizeof ("qTsSTM"));
3987 s
[sizeof ("qTsSTM")] = 0;
3988 agent_run_command (pid
, s
, strlen (s
) + 1);
3995 /* target_is_async_p implementation. */
3998 linux_nat_target::is_async_p ()
4000 return linux_is_async_p ();
4003 /* target_can_async_p implementation. */
4006 linux_nat_target::can_async_p ()
4008 /* We're always async, unless the user explicitly prevented it with the
4009 "maint set target-async" command. */
4010 return target_async_permitted
;
4014 linux_nat_target::supports_non_stop ()
4019 /* to_always_non_stop_p implementation. */
4022 linux_nat_target::always_non_stop_p ()
4028 linux_nat_target::supports_multi_process ()
4034 linux_nat_target::supports_disable_randomization ()
4036 #ifdef HAVE_PERSONALITY
4043 /* SIGCHLD handler that serves two purposes: In non-stop/async mode,
4044 so we notice when any child changes state, and notify the
4045 event-loop; it allows us to use sigsuspend in linux_nat_wait_1
4046 above to wait for the arrival of a SIGCHLD. */
4049 sigchld_handler (int signo
)
4051 int old_errno
= errno
;
4053 if (debug_linux_nat
)
4054 gdb_stdlog
->write_async_safe ("sigchld\n", sizeof ("sigchld\n") - 1);
4056 if (signo
== SIGCHLD
4057 && linux_nat_event_pipe
[0] != -1)
4058 async_file_mark (); /* Let the event loop know that there are
4059 events to handle. */
4064 /* Callback registered with the target events file descriptor. */
4067 handle_target_event (int error
, gdb_client_data client_data
)
4069 inferior_event_handler (INF_REG_EVENT
);
4072 /* Create/destroy the target events pipe. Returns previous state. */
4075 linux_async_pipe (int enable
)
4077 int previous
= linux_is_async_p ();
4079 if (previous
!= enable
)
4083 /* Block child signals while we create/destroy the pipe, as
4084 their handler writes to it. */
4085 block_child_signals (&prev_mask
);
4089 if (gdb_pipe_cloexec (linux_nat_event_pipe
) == -1)
4090 internal_error (__FILE__
, __LINE__
,
4091 "creating event pipe failed.");
4093 fcntl (linux_nat_event_pipe
[0], F_SETFL
, O_NONBLOCK
);
4094 fcntl (linux_nat_event_pipe
[1], F_SETFL
, O_NONBLOCK
);
4098 close (linux_nat_event_pipe
[0]);
4099 close (linux_nat_event_pipe
[1]);
4100 linux_nat_event_pipe
[0] = -1;
4101 linux_nat_event_pipe
[1] = -1;
4104 restore_child_signals_mask (&prev_mask
);
4111 linux_nat_target::async_wait_fd ()
4113 return linux_nat_event_pipe
[0];
4116 /* target_async implementation. */
4119 linux_nat_target::async (int enable
)
4123 if (!linux_async_pipe (1))
4125 add_file_handler (linux_nat_event_pipe
[0],
4126 handle_target_event
, NULL
);
4127 /* There may be pending events to handle. Tell the event loop
4134 delete_file_handler (linux_nat_event_pipe
[0]);
4135 linux_async_pipe (0);
4140 /* Stop an LWP, and push a GDB_SIGNAL_0 stop status if no other
4144 linux_nat_stop_lwp (struct lwp_info
*lwp
)
4148 linux_nat_debug_printf ("running -> suspending %s",
4149 target_pid_to_str (lwp
->ptid
).c_str ());
4152 if (lwp
->last_resume_kind
== resume_stop
)
4154 linux_nat_debug_printf ("already stopping LWP %ld at GDB's request",
4159 stop_callback (lwp
);
4160 lwp
->last_resume_kind
= resume_stop
;
4164 /* Already known to be stopped; do nothing. */
4166 if (debug_linux_nat
)
4168 if (find_thread_ptid (linux_target
, lwp
->ptid
)->stop_requested
)
4169 linux_nat_debug_printf ("already stopped/stop_requested %s",
4170 target_pid_to_str (lwp
->ptid
).c_str ());
4172 linux_nat_debug_printf ("already stopped/no stop_requested yet %s",
4173 target_pid_to_str (lwp
->ptid
).c_str ());
4180 linux_nat_target::stop (ptid_t ptid
)
4182 iterate_over_lwps (ptid
, linux_nat_stop_lwp
);
4186 linux_nat_target::close ()
4188 /* Unregister from the event loop. */
4192 inf_ptrace_target::close ();
4195 /* When requests are passed down from the linux-nat layer to the
4196 single threaded inf-ptrace layer, ptids of (lwpid,0,0) form are
4197 used. The address space pointer is stored in the inferior object,
4198 but the common code that is passed such ptid can't tell whether
4199 lwpid is a "main" process id or not (it assumes so). We reverse
4200 look up the "main" process id from the lwp here. */
4202 struct address_space
*
4203 linux_nat_target::thread_address_space (ptid_t ptid
)
4205 struct lwp_info
*lwp
;
4206 struct inferior
*inf
;
4209 if (ptid
.lwp () == 0)
4211 /* An (lwpid,0,0) ptid. Look up the lwp object to get at the
4213 lwp
= find_lwp_pid (ptid
);
4214 pid
= lwp
->ptid
.pid ();
4218 /* A (pid,lwpid,0) ptid. */
4222 inf
= find_inferior_pid (this, pid
);
4223 gdb_assert (inf
!= NULL
);
4227 /* Return the cached value of the processor core for thread PTID. */
4230 linux_nat_target::core_of_thread (ptid_t ptid
)
4232 struct lwp_info
*info
= find_lwp_pid (ptid
);
4239 /* Implementation of to_filesystem_is_local. */
4242 linux_nat_target::filesystem_is_local ()
4244 struct inferior
*inf
= current_inferior ();
4246 if (inf
->fake_pid_p
|| inf
->pid
== 0)
4249 return linux_ns_same (inf
->pid
, LINUX_NS_MNT
);
4252 /* Convert the INF argument passed to a to_fileio_* method
4253 to a process ID suitable for passing to its corresponding
4254 linux_mntns_* function. If INF is non-NULL then the
4255 caller is requesting the filesystem seen by INF. If INF
4256 is NULL then the caller is requesting the filesystem seen
4257 by the GDB. We fall back to GDB's filesystem in the case
4258 that INF is non-NULL but its PID is unknown. */
4261 linux_nat_fileio_pid_of (struct inferior
*inf
)
4263 if (inf
== NULL
|| inf
->fake_pid_p
|| inf
->pid
== 0)
4269 /* Implementation of to_fileio_open. */
4272 linux_nat_target::fileio_open (struct inferior
*inf
, const char *filename
,
4273 int flags
, int mode
, int warn_if_slow
,
4280 if (fileio_to_host_openflags (flags
, &nat_flags
) == -1
4281 || fileio_to_host_mode (mode
, &nat_mode
) == -1)
4283 *target_errno
= FILEIO_EINVAL
;
4287 fd
= linux_mntns_open_cloexec (linux_nat_fileio_pid_of (inf
),
4288 filename
, nat_flags
, nat_mode
);
4290 *target_errno
= host_to_fileio_error (errno
);
4295 /* Implementation of to_fileio_readlink. */
4297 gdb::optional
<std::string
>
4298 linux_nat_target::fileio_readlink (struct inferior
*inf
, const char *filename
,
4304 len
= linux_mntns_readlink (linux_nat_fileio_pid_of (inf
),
4305 filename
, buf
, sizeof (buf
));
4308 *target_errno
= host_to_fileio_error (errno
);
4312 return std::string (buf
, len
);
4315 /* Implementation of to_fileio_unlink. */
4318 linux_nat_target::fileio_unlink (struct inferior
*inf
, const char *filename
,
4323 ret
= linux_mntns_unlink (linux_nat_fileio_pid_of (inf
),
4326 *target_errno
= host_to_fileio_error (errno
);
4331 /* Implementation of the to_thread_events method. */
4334 linux_nat_target::thread_events (int enable
)
4336 report_thread_events
= enable
;
4339 linux_nat_target::linux_nat_target ()
4341 /* We don't change the stratum; this target will sit at
4342 process_stratum and thread_db will set at thread_stratum. This
4343 is a little strange, since this is a multi-threaded-capable
4344 target, but we want to be on the stack below thread_db, and we
4345 also want to be used for single-threaded processes. */
4348 /* See linux-nat.h. */
4351 linux_nat_get_siginfo (ptid_t ptid
, siginfo_t
*siginfo
)
4360 ptrace (PTRACE_GETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, siginfo
);
4363 memset (siginfo
, 0, sizeof (*siginfo
));
4369 /* See nat/linux-nat.h. */
4372 current_lwp_ptid (void)
4374 gdb_assert (inferior_ptid
.lwp_p ());
4375 return inferior_ptid
;
4378 void _initialize_linux_nat ();
4380 _initialize_linux_nat ()
4382 add_setshow_zuinteger_cmd ("lin-lwp", class_maintenance
,
4383 &debug_linux_nat
, _("\
4384 Set debugging of GNU/Linux lwp module."), _("\
4385 Show debugging of GNU/Linux lwp module."), _("\
4386 Enables printf debugging output."),
4388 show_debug_linux_nat
,
4389 &setdebuglist
, &showdebuglist
);
4391 add_setshow_boolean_cmd ("linux-namespaces", class_maintenance
,
4392 &debug_linux_namespaces
, _("\
4393 Set debugging of GNU/Linux namespaces module."), _("\
4394 Show debugging of GNU/Linux namespaces module."), _("\
4395 Enables printf debugging output."),
4398 &setdebuglist
, &showdebuglist
);
4400 /* Install a SIGCHLD handler. */
4401 sigchld_action
.sa_handler
= sigchld_handler
;
4402 sigemptyset (&sigchld_action
.sa_mask
);
4403 sigchld_action
.sa_flags
= SA_RESTART
;
4405 /* Make it the default. */
4406 sigaction (SIGCHLD
, &sigchld_action
, NULL
);
4408 /* Make sure we don't block SIGCHLD during a sigsuspend. */
4409 gdb_sigmask (SIG_SETMASK
, NULL
, &suspend_mask
);
4410 sigdelset (&suspend_mask
, SIGCHLD
);
4412 sigemptyset (&blocked_mask
);
4414 lwp_lwpid_htab_create ();
4418 /* FIXME: kettenis/2000-08-26: The stuff on this page is specific to
4419 the GNU/Linux Threads library and therefore doesn't really belong
4422 /* Return the set of signals used by the threads library in *SET. */
4425 lin_thread_get_thread_signals (sigset_t
*set
)
4429 /* NPTL reserves the first two RT signals, but does not provide any
4430 way for the debugger to query the signal numbers - fortunately
4431 they don't change. */
4432 sigaddset (set
, __SIGRTMIN
);
4433 sigaddset (set
, __SIGRTMIN
+ 1);