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"
72 /* This comment documents high-level logic of this file.
74 Waiting for events in sync mode
75 ===============================
77 When waiting for an event in a specific thread, we just use waitpid,
78 passing the specific pid, and not passing WNOHANG.
80 When waiting for an event in all threads, waitpid is not quite good:
82 - If the thread group leader exits while other threads in the thread
83 group still exist, waitpid(TGID, ...) hangs. That waitpid won't
84 return an exit status until the other threads in the group are
87 - When a non-leader thread execs, that thread just vanishes without
88 reporting an exit (so we'd hang if we waited for it explicitly in
89 that case). The exec event is instead reported to the TGID pid.
91 The solution is to always use -1 and WNOHANG, together with
94 First, we use non-blocking waitpid to check for events. If nothing is
95 found, we use sigsuspend to wait for SIGCHLD. When SIGCHLD arrives,
96 it means something happened to a child process. As soon as we know
97 there's an event, we get back to calling nonblocking waitpid.
99 Note that SIGCHLD should be blocked between waitpid and sigsuspend
100 calls, so that we don't miss a signal. If SIGCHLD arrives in between,
101 when it's blocked, the signal becomes pending and sigsuspend
102 immediately notices it and returns.
104 Waiting for events in async mode (TARGET_WNOHANG)
105 =================================================
107 In async mode, GDB should always be ready to handle both user input
108 and target events, so neither blocking waitpid nor sigsuspend are
109 viable options. Instead, we should asynchronously notify the GDB main
110 event loop whenever there's an unprocessed event from the target. We
111 detect asynchronous target events by handling SIGCHLD signals. To
112 notify the event loop about target events, the self-pipe trick is used
113 --- a pipe is registered as waitable event source in the event loop,
114 the event loop select/poll's on the read end of this pipe (as well on
115 other event sources, e.g., stdin), and the SIGCHLD handler writes a
116 byte to this pipe. This is more portable than relying on
117 pselect/ppoll, since on kernels that lack those syscalls, libc
118 emulates them with select/poll+sigprocmask, and that is racy
119 (a.k.a. plain broken).
121 Obviously, if we fail to notify the event loop if there's a target
122 event, it's bad. OTOH, if we notify the event loop when there's no
123 event from the target, linux_nat_wait will detect that there's no real
124 event to report, and return event of type TARGET_WAITKIND_IGNORE.
125 This is mostly harmless, but it will waste time and is better avoided.
127 The main design point is that every time GDB is outside linux-nat.c,
128 we have a SIGCHLD handler installed that is called when something
129 happens to the target and notifies the GDB event loop. Whenever GDB
130 core decides to handle the event, and calls into linux-nat.c, we
131 process things as in sync mode, except that the we never block in
134 While processing an event, we may end up momentarily blocked in
135 waitpid calls. Those waitpid calls, while blocking, are guarantied to
136 return quickly. E.g., in all-stop mode, before reporting to the core
137 that an LWP hit a breakpoint, all LWPs are stopped by sending them
138 SIGSTOP, and synchronously waiting for the SIGSTOP to be reported.
139 Note that this is different from blocking indefinitely waiting for the
140 next event --- here, we're already handling an event.
145 We stop threads by sending a SIGSTOP. The use of SIGSTOP instead of another
146 signal is not entirely significant; we just need for a signal to be delivered,
147 so that we can intercept it. SIGSTOP's advantage is that it can not be
148 blocked. A disadvantage is that it is not a real-time signal, so it can only
149 be queued once; we do not keep track of other sources of SIGSTOP.
151 Two other signals that can't be blocked are SIGCONT and SIGKILL. But we can't
152 use them, because they have special behavior when the signal is generated -
153 not when it is delivered. SIGCONT resumes the entire thread group and SIGKILL
154 kills the entire thread group.
156 A delivered SIGSTOP would stop the entire thread group, not just the thread we
157 tkill'd. But we never let the SIGSTOP be delivered; we always intercept and
158 cancel it (by PTRACE_CONT without passing SIGSTOP).
160 We could use a real-time signal instead. This would solve those problems; we
161 could use PTRACE_GETSIGINFO to locate the specific stop signals sent by GDB.
162 But we would still have to have some support for SIGSTOP, since PTRACE_ATTACH
163 generates it, and there are races with trying to find a signal that is not
169 The case of a thread group (process) with 3 or more threads, and a
170 thread other than the leader execs is worth detailing:
172 On an exec, the Linux kernel destroys all threads except the execing
173 one in the thread group, and resets the execing thread's tid to the
174 tgid. No exit notification is sent for the execing thread -- from the
175 ptracer's perspective, it appears as though the execing thread just
176 vanishes. Until we reap all other threads except the leader and the
177 execing thread, the leader will be zombie, and the execing thread will
178 be in `D (disc sleep)' state. As soon as all other threads are
179 reaped, the execing thread changes its tid to the tgid, and the
180 previous (zombie) leader vanishes, giving place to the "new"
184 #define O_LARGEFILE 0
187 struct linux_nat_target
*linux_target
;
189 /* Does the current host support PTRACE_GETREGSET? */
190 enum tribool have_ptrace_getregset
= TRIBOOL_UNKNOWN
;
192 static unsigned int debug_linux_nat
;
194 show_debug_linux_nat (struct ui_file
*file
, int from_tty
,
195 struct cmd_list_element
*c
, const char *value
)
197 fprintf_filtered (file
, _("Debugging of GNU/Linux lwp module is %s.\n"),
201 /* Print a debug statement. Should be used through linux_nat_debug_printf. */
203 static void ATTRIBUTE_PRINTF (2, 3)
204 linux_nat_debug_printf_1 (const char *func_name
, const char *fmt
, ...)
206 debug_printf ("[linux-nat] %s: ", func_name
);
210 debug_vprintf (fmt
, ap
);
216 #define linux_nat_debug_printf(fmt, ...) \
218 if (debug_linux_nat) \
219 linux_nat_debug_printf_1 (__func__, fmt, ##__VA_ARGS__); \
222 struct simple_pid_list
226 struct simple_pid_list
*next
;
228 static struct simple_pid_list
*stopped_pids
;
230 /* Whether target_thread_events is in effect. */
231 static int report_thread_events
;
233 /* Async mode support. */
235 /* The read/write ends of the pipe registered as waitable file in the
237 static int linux_nat_event_pipe
[2] = { -1, -1 };
239 /* True if we're currently in async mode. */
240 #define linux_is_async_p() (linux_nat_event_pipe[0] != -1)
242 /* Flush the event pipe. */
245 async_file_flush (void)
252 ret
= read (linux_nat_event_pipe
[0], &buf
, 1);
254 while (ret
>= 0 || (ret
== -1 && errno
== EINTR
));
257 /* Put something (anything, doesn't matter what, or how much) in event
258 pipe, so that the select/poll in the event-loop realizes we have
259 something to process. */
262 async_file_mark (void)
266 /* It doesn't really matter what the pipe contains, as long we end
267 up with something in it. Might as well flush the previous
273 ret
= write (linux_nat_event_pipe
[1], "+", 1);
275 while (ret
== -1 && errno
== EINTR
);
277 /* Ignore EAGAIN. If the pipe is full, the event loop will already
278 be awakened anyway. */
281 static int kill_lwp (int lwpid
, int signo
);
283 static int stop_callback (struct lwp_info
*lp
);
285 static void block_child_signals (sigset_t
*prev_mask
);
286 static void restore_child_signals_mask (sigset_t
*prev_mask
);
289 static struct lwp_info
*add_lwp (ptid_t ptid
);
290 static void purge_lwp_list (int pid
);
291 static void delete_lwp (ptid_t ptid
);
292 static struct lwp_info
*find_lwp_pid (ptid_t ptid
);
294 static int lwp_status_pending_p (struct lwp_info
*lp
);
296 static void save_stop_reason (struct lwp_info
*lp
);
301 /* See nat/linux-nat.h. */
304 ptid_of_lwp (struct lwp_info
*lwp
)
309 /* See nat/linux-nat.h. */
312 lwp_set_arch_private_info (struct lwp_info
*lwp
,
313 struct arch_lwp_info
*info
)
315 lwp
->arch_private
= info
;
318 /* See nat/linux-nat.h. */
320 struct arch_lwp_info
*
321 lwp_arch_private_info (struct lwp_info
*lwp
)
323 return lwp
->arch_private
;
326 /* See nat/linux-nat.h. */
329 lwp_is_stopped (struct lwp_info
*lwp
)
334 /* See nat/linux-nat.h. */
336 enum target_stop_reason
337 lwp_stop_reason (struct lwp_info
*lwp
)
339 return lwp
->stop_reason
;
342 /* See nat/linux-nat.h. */
345 lwp_is_stepping (struct lwp_info
*lwp
)
351 /* Trivial list manipulation functions to keep track of a list of
352 new stopped processes. */
354 add_to_pid_list (struct simple_pid_list
**listp
, int pid
, int status
)
356 struct simple_pid_list
*new_pid
= XNEW (struct simple_pid_list
);
359 new_pid
->status
= status
;
360 new_pid
->next
= *listp
;
365 pull_pid_from_list (struct simple_pid_list
**listp
, int pid
, int *statusp
)
367 struct simple_pid_list
**p
;
369 for (p
= listp
; *p
!= NULL
; p
= &(*p
)->next
)
370 if ((*p
)->pid
== pid
)
372 struct simple_pid_list
*next
= (*p
)->next
;
374 *statusp
= (*p
)->status
;
382 /* Return the ptrace options that we want to try to enable. */
385 linux_nat_ptrace_options (int attached
)
390 options
|= PTRACE_O_EXITKILL
;
392 options
|= (PTRACE_O_TRACESYSGOOD
393 | PTRACE_O_TRACEVFORKDONE
394 | PTRACE_O_TRACEVFORK
396 | PTRACE_O_TRACEEXEC
);
401 /* Initialize ptrace and procfs warnings and check for supported
402 ptrace features given PID.
404 ATTACHED should be nonzero iff we attached to the inferior. */
407 linux_init_ptrace_procfs (pid_t pid
, int attached
)
409 int options
= linux_nat_ptrace_options (attached
);
411 linux_enable_event_reporting (pid
, options
);
412 linux_ptrace_init_warnings ();
413 linux_proc_init_warnings ();
416 linux_nat_target::~linux_nat_target ()
420 linux_nat_target::post_attach (int pid
)
422 linux_init_ptrace_procfs (pid
, 1);
426 linux_nat_target::post_startup_inferior (ptid_t ptid
)
428 linux_init_ptrace_procfs (ptid
.pid (), 0);
431 /* Return the number of known LWPs in the tgid given by PID. */
439 for (lp
= lwp_list
; lp
; lp
= lp
->next
)
440 if (lp
->ptid
.pid () == pid
)
446 /* Deleter for lwp_info unique_ptr specialisation. */
450 void operator() (struct lwp_info
*lwp
) const
452 delete_lwp (lwp
->ptid
);
456 /* A unique_ptr specialisation for lwp_info. */
458 typedef std::unique_ptr
<struct lwp_info
, lwp_deleter
> lwp_info_up
;
460 /* Target hook for follow_fork. On entry inferior_ptid must be the
461 ptid of the followed inferior. At return, inferior_ptid will be
465 linux_nat_target::follow_fork (bool follow_child
, bool detach_fork
)
469 struct lwp_info
*child_lp
= NULL
;
471 ptid_t parent_ptid
, child_ptid
;
472 int parent_pid
, child_pid
;
474 has_vforked
= (inferior_thread ()->pending_follow
.kind
475 == TARGET_WAITKIND_VFORKED
);
476 parent_ptid
= inferior_ptid
;
477 child_ptid
= inferior_thread ()->pending_follow
.value
.related_pid
;
478 parent_pid
= parent_ptid
.lwp ();
479 child_pid
= child_ptid
.lwp ();
481 /* We're already attached to the parent, by default. */
482 child_lp
= add_lwp (child_ptid
);
483 child_lp
->stopped
= 1;
484 child_lp
->last_resume_kind
= resume_stop
;
486 /* Detach new forked process? */
489 int child_stop_signal
= 0;
490 bool detach_child
= true;
492 /* Move CHILD_LP into a unique_ptr and clear the source pointer
493 to prevent us doing anything stupid with it. */
494 lwp_info_up
child_lp_ptr (child_lp
);
497 linux_target
->low_prepare_to_resume (child_lp_ptr
.get ());
499 /* When debugging an inferior in an architecture that supports
500 hardware single stepping on a kernel without commit
501 6580807da14c423f0d0a708108e6df6ebc8bc83d, the vfork child
502 process starts with the TIF_SINGLESTEP/X86_EFLAGS_TF bits
503 set if the parent process had them set.
504 To work around this, single step the child process
505 once before detaching to clear the flags. */
507 /* Note that we consult the parent's architecture instead of
508 the child's because there's no inferior for the child at
510 if (!gdbarch_software_single_step_p (target_thread_architecture
515 linux_disable_event_reporting (child_pid
);
516 if (ptrace (PTRACE_SINGLESTEP
, child_pid
, 0, 0) < 0)
517 perror_with_name (_("Couldn't do single step"));
518 if (my_waitpid (child_pid
, &status
, 0) < 0)
519 perror_with_name (_("Couldn't wait vfork process"));
522 detach_child
= WIFSTOPPED (status
);
523 child_stop_signal
= WSTOPSIG (status
);
529 int signo
= child_stop_signal
;
532 && !signal_pass_state (gdb_signal_from_host (signo
)))
534 ptrace (PTRACE_DETACH
, child_pid
, 0, signo
);
539 /* Switching inferior_ptid is not enough, because then
540 inferior_thread () would crash by not finding the thread
541 in the current inferior. */
542 scoped_restore_current_thread restore_current_thread
;
543 thread_info
*child
= find_thread_ptid (this, child_ptid
);
544 switch_to_thread (child
);
546 /* Let the thread_db layer learn about this new process. */
547 check_for_thread_db ();
552 struct lwp_info
*parent_lp
;
554 parent_lp
= find_lwp_pid (parent_ptid
);
555 gdb_assert (linux_supports_tracefork () >= 0);
557 if (linux_supports_tracevforkdone ())
559 linux_nat_debug_printf ("waiting for VFORK_DONE on %d",
561 parent_lp
->stopped
= 1;
563 /* We'll handle the VFORK_DONE event like any other
564 event, in target_wait. */
568 /* We can't insert breakpoints until the child has
569 finished with the shared memory region. We need to
570 wait until that happens. Ideal would be to just
572 - ptrace (PTRACE_SYSCALL, parent_pid, 0, 0);
573 - waitpid (parent_pid, &status, __WALL);
574 However, most architectures can't handle a syscall
575 being traced on the way out if it wasn't traced on
578 We might also think to loop, continuing the child
579 until it exits or gets a SIGTRAP. One problem is
580 that the child might call ptrace with PTRACE_TRACEME.
582 There's no simple and reliable way to figure out when
583 the vforked child will be done with its copy of the
584 shared memory. We could step it out of the syscall,
585 two instructions, let it go, and then single-step the
586 parent once. When we have hardware single-step, this
587 would work; with software single-step it could still
588 be made to work but we'd have to be able to insert
589 single-step breakpoints in the child, and we'd have
590 to insert -just- the single-step breakpoint in the
591 parent. Very awkward.
593 In the end, the best we can do is to make sure it
594 runs for a little while. Hopefully it will be out of
595 range of any breakpoints we reinsert. Usually this
596 is only the single-step breakpoint at vfork's return
599 linux_nat_debug_printf ("no VFORK_DONE support, sleeping a bit");
603 /* Pretend we've seen a PTRACE_EVENT_VFORK_DONE event,
604 and leave it pending. The next linux_nat_resume call
605 will notice a pending event, and bypasses actually
606 resuming the inferior. */
607 parent_lp
->status
= 0;
608 parent_lp
->waitstatus
.kind
= TARGET_WAITKIND_VFORK_DONE
;
609 parent_lp
->stopped
= 1;
611 /* If we're in async mode, need to tell the event loop
612 there's something here to process. */
613 if (target_is_async_p ())
620 struct lwp_info
*child_lp
;
622 child_lp
= add_lwp (inferior_ptid
);
623 child_lp
->stopped
= 1;
624 child_lp
->last_resume_kind
= resume_stop
;
626 /* Let the thread_db layer learn about this new process. */
627 check_for_thread_db ();
635 linux_nat_target::insert_fork_catchpoint (int pid
)
637 return !linux_supports_tracefork ();
641 linux_nat_target::remove_fork_catchpoint (int pid
)
647 linux_nat_target::insert_vfork_catchpoint (int pid
)
649 return !linux_supports_tracefork ();
653 linux_nat_target::remove_vfork_catchpoint (int pid
)
659 linux_nat_target::insert_exec_catchpoint (int pid
)
661 return !linux_supports_tracefork ();
665 linux_nat_target::remove_exec_catchpoint (int pid
)
671 linux_nat_target::set_syscall_catchpoint (int pid
, bool needed
, int any_count
,
672 gdb::array_view
<const int> syscall_counts
)
674 if (!linux_supports_tracesysgood ())
677 /* On GNU/Linux, we ignore the arguments. It means that we only
678 enable the syscall catchpoints, but do not disable them.
680 Also, we do not use the `syscall_counts' information because we do not
681 filter system calls here. We let GDB do the logic for us. */
685 /* List of known LWPs, keyed by LWP PID. This speeds up the common
686 case of mapping a PID returned from the kernel to our corresponding
687 lwp_info data structure. */
688 static htab_t lwp_lwpid_htab
;
690 /* Calculate a hash from a lwp_info's LWP PID. */
693 lwp_info_hash (const void *ap
)
695 const struct lwp_info
*lp
= (struct lwp_info
*) ap
;
696 pid_t pid
= lp
->ptid
.lwp ();
698 return iterative_hash_object (pid
, 0);
701 /* Equality function for the lwp_info hash table. Compares the LWP's
705 lwp_lwpid_htab_eq (const void *a
, const void *b
)
707 const struct lwp_info
*entry
= (const struct lwp_info
*) a
;
708 const struct lwp_info
*element
= (const struct lwp_info
*) b
;
710 return entry
->ptid
.lwp () == element
->ptid
.lwp ();
713 /* Create the lwp_lwpid_htab hash table. */
716 lwp_lwpid_htab_create (void)
718 lwp_lwpid_htab
= htab_create (100, lwp_info_hash
, lwp_lwpid_htab_eq
, NULL
);
721 /* Add LP to the hash table. */
724 lwp_lwpid_htab_add_lwp (struct lwp_info
*lp
)
728 slot
= htab_find_slot (lwp_lwpid_htab
, lp
, INSERT
);
729 gdb_assert (slot
!= NULL
&& *slot
== NULL
);
733 /* Head of doubly-linked list of known LWPs. Sorted by reverse
734 creation order. This order is assumed in some cases. E.g.,
735 reaping status after killing alls lwps of a process: the leader LWP
736 must be reaped last. */
737 struct lwp_info
*lwp_list
;
739 /* Add LP to sorted-by-reverse-creation-order doubly-linked list. */
742 lwp_list_add (struct lwp_info
*lp
)
745 if (lwp_list
!= NULL
)
750 /* Remove LP from sorted-by-reverse-creation-order doubly-linked
754 lwp_list_remove (struct lwp_info
*lp
)
756 /* Remove from sorted-by-creation-order list. */
757 if (lp
->next
!= NULL
)
758 lp
->next
->prev
= lp
->prev
;
759 if (lp
->prev
!= NULL
)
760 lp
->prev
->next
= lp
->next
;
767 /* Signal mask for use with sigsuspend in linux_nat_wait, initialized in
768 _initialize_linux_nat. */
769 static sigset_t suspend_mask
;
771 /* Signals to block to make that sigsuspend work. */
772 static sigset_t blocked_mask
;
774 /* SIGCHLD action. */
775 struct sigaction sigchld_action
;
777 /* Block child signals (SIGCHLD and linux threads signals), and store
778 the previous mask in PREV_MASK. */
781 block_child_signals (sigset_t
*prev_mask
)
783 /* Make sure SIGCHLD is blocked. */
784 if (!sigismember (&blocked_mask
, SIGCHLD
))
785 sigaddset (&blocked_mask
, SIGCHLD
);
787 gdb_sigmask (SIG_BLOCK
, &blocked_mask
, prev_mask
);
790 /* Restore child signals mask, previously returned by
791 block_child_signals. */
794 restore_child_signals_mask (sigset_t
*prev_mask
)
796 gdb_sigmask (SIG_SETMASK
, prev_mask
, NULL
);
799 /* Mask of signals to pass directly to the inferior. */
800 static sigset_t pass_mask
;
802 /* Update signals to pass to the inferior. */
804 linux_nat_target::pass_signals
805 (gdb::array_view
<const unsigned char> pass_signals
)
809 sigemptyset (&pass_mask
);
811 for (signo
= 1; signo
< NSIG
; signo
++)
813 int target_signo
= gdb_signal_from_host (signo
);
814 if (target_signo
< pass_signals
.size () && pass_signals
[target_signo
])
815 sigaddset (&pass_mask
, signo
);
821 /* Prototypes for local functions. */
822 static int stop_wait_callback (struct lwp_info
*lp
);
823 static int resume_stopped_resumed_lwps (struct lwp_info
*lp
, const ptid_t wait_ptid
);
824 static int check_ptrace_stopped_lwp_gone (struct lwp_info
*lp
);
828 /* Destroy and free LP. */
831 lwp_free (struct lwp_info
*lp
)
833 /* Let the arch specific bits release arch_lwp_info. */
834 linux_target
->low_delete_thread (lp
->arch_private
);
839 /* Traversal function for purge_lwp_list. */
842 lwp_lwpid_htab_remove_pid (void **slot
, void *info
)
844 struct lwp_info
*lp
= (struct lwp_info
*) *slot
;
845 int pid
= *(int *) info
;
847 if (lp
->ptid
.pid () == pid
)
849 htab_clear_slot (lwp_lwpid_htab
, slot
);
850 lwp_list_remove (lp
);
857 /* Remove all LWPs belong to PID from the lwp list. */
860 purge_lwp_list (int pid
)
862 htab_traverse_noresize (lwp_lwpid_htab
, lwp_lwpid_htab_remove_pid
, &pid
);
865 /* Add the LWP specified by PTID to the list. PTID is the first LWP
866 in the process. Return a pointer to the structure describing the
869 This differs from add_lwp in that we don't let the arch specific
870 bits know about this new thread. Current clients of this callback
871 take the opportunity to install watchpoints in the new thread, and
872 we shouldn't do that for the first thread. If we're spawning a
873 child ("run"), the thread executes the shell wrapper first, and we
874 shouldn't touch it until it execs the program we want to debug.
875 For "attach", it'd be okay to call the callback, but it's not
876 necessary, because watchpoints can't yet have been inserted into
879 static struct lwp_info
*
880 add_initial_lwp (ptid_t ptid
)
884 gdb_assert (ptid
.lwp_p ());
886 lp
= XNEW (struct lwp_info
);
888 memset (lp
, 0, sizeof (struct lwp_info
));
890 lp
->last_resume_kind
= resume_continue
;
891 lp
->waitstatus
.kind
= TARGET_WAITKIND_IGNORE
;
896 /* Add to sorted-by-reverse-creation-order list. */
899 /* Add to keyed-by-pid htab. */
900 lwp_lwpid_htab_add_lwp (lp
);
905 /* Add the LWP specified by PID to the list. Return a pointer to the
906 structure describing the new LWP. The LWP should already be
909 static struct lwp_info
*
910 add_lwp (ptid_t ptid
)
914 lp
= add_initial_lwp (ptid
);
916 /* Let the arch specific bits know about this new thread. Current
917 clients of this callback take the opportunity to install
918 watchpoints in the new thread. We don't do this for the first
919 thread though. See add_initial_lwp. */
920 linux_target
->low_new_thread (lp
);
925 /* Remove the LWP specified by PID from the list. */
928 delete_lwp (ptid_t ptid
)
932 struct lwp_info dummy
;
935 slot
= htab_find_slot (lwp_lwpid_htab
, &dummy
, NO_INSERT
);
939 lp
= *(struct lwp_info
**) slot
;
940 gdb_assert (lp
!= NULL
);
942 htab_clear_slot (lwp_lwpid_htab
, slot
);
944 /* Remove from sorted-by-creation-order list. */
945 lwp_list_remove (lp
);
951 /* Return a pointer to the structure describing the LWP corresponding
952 to PID. If no corresponding LWP could be found, return NULL. */
954 static struct lwp_info
*
955 find_lwp_pid (ptid_t ptid
)
959 struct lwp_info dummy
;
966 dummy
.ptid
= ptid_t (0, lwp
, 0);
967 lp
= (struct lwp_info
*) htab_find (lwp_lwpid_htab
, &dummy
);
971 /* See nat/linux-nat.h. */
974 iterate_over_lwps (ptid_t filter
,
975 gdb::function_view
<iterate_over_lwps_ftype
> callback
)
977 struct lwp_info
*lp
, *lpnext
;
979 for (lp
= lwp_list
; lp
; lp
= lpnext
)
983 if (lp
->ptid
.matches (filter
))
985 if (callback (lp
) != 0)
993 /* Update our internal state when changing from one checkpoint to
994 another indicated by NEW_PTID. We can only switch single-threaded
995 applications, so we only create one new LWP, and the previous list
999 linux_nat_switch_fork (ptid_t new_ptid
)
1001 struct lwp_info
*lp
;
1003 purge_lwp_list (inferior_ptid
.pid ());
1005 lp
= add_lwp (new_ptid
);
1008 /* This changes the thread's ptid while preserving the gdb thread
1009 num. Also changes the inferior pid, while preserving the
1011 thread_change_ptid (linux_target
, inferior_ptid
, new_ptid
);
1013 /* We've just told GDB core that the thread changed target id, but,
1014 in fact, it really is a different thread, with different register
1016 registers_changed ();
1019 /* Handle the exit of a single thread LP. */
1022 exit_lwp (struct lwp_info
*lp
)
1024 struct thread_info
*th
= find_thread_ptid (linux_target
, lp
->ptid
);
1028 if (print_thread_events
)
1029 printf_unfiltered (_("[%s exited]\n"),
1030 target_pid_to_str (lp
->ptid
).c_str ());
1035 delete_lwp (lp
->ptid
);
1038 /* Wait for the LWP specified by LP, which we have just attached to.
1039 Returns a wait status for that LWP, to cache. */
1042 linux_nat_post_attach_wait (ptid_t ptid
, int *signalled
)
1044 pid_t new_pid
, pid
= ptid
.lwp ();
1047 if (linux_proc_pid_is_stopped (pid
))
1049 linux_nat_debug_printf ("Attaching to a stopped process");
1051 /* The process is definitely stopped. It is in a job control
1052 stop, unless the kernel predates the TASK_STOPPED /
1053 TASK_TRACED distinction, in which case it might be in a
1054 ptrace stop. Make sure it is in a ptrace stop; from there we
1055 can kill it, signal it, et cetera.
1057 First make sure there is a pending SIGSTOP. Since we are
1058 already attached, the process can not transition from stopped
1059 to running without a PTRACE_CONT; so we know this signal will
1060 go into the queue. The SIGSTOP generated by PTRACE_ATTACH is
1061 probably already in the queue (unless this kernel is old
1062 enough to use TASK_STOPPED for ptrace stops); but since SIGSTOP
1063 is not an RT signal, it can only be queued once. */
1064 kill_lwp (pid
, SIGSTOP
);
1066 /* Finally, resume the stopped process. This will deliver the SIGSTOP
1067 (or a higher priority signal, just like normal PTRACE_ATTACH). */
1068 ptrace (PTRACE_CONT
, pid
, 0, 0);
1071 /* Make sure the initial process is stopped. The user-level threads
1072 layer might want to poke around in the inferior, and that won't
1073 work if things haven't stabilized yet. */
1074 new_pid
= my_waitpid (pid
, &status
, __WALL
);
1075 gdb_assert (pid
== new_pid
);
1077 if (!WIFSTOPPED (status
))
1079 /* The pid we tried to attach has apparently just exited. */
1080 linux_nat_debug_printf ("Failed to stop %d: %s", pid
,
1081 status_to_str (status
));
1085 if (WSTOPSIG (status
) != SIGSTOP
)
1088 linux_nat_debug_printf ("Received %s after attaching",
1089 status_to_str (status
));
1096 linux_nat_target::create_inferior (const char *exec_file
,
1097 const std::string
&allargs
,
1098 char **env
, int from_tty
)
1100 maybe_disable_address_space_randomization restore_personality
1101 (disable_randomization
);
1103 /* The fork_child mechanism is synchronous and calls target_wait, so
1104 we have to mask the async mode. */
1106 /* Make sure we report all signals during startup. */
1109 inf_ptrace_target::create_inferior (exec_file
, allargs
, env
, from_tty
);
1112 /* Callback for linux_proc_attach_tgid_threads. Attach to PTID if not
1113 already attached. Returns true if a new LWP is found, false
1117 attach_proc_task_lwp_callback (ptid_t ptid
)
1119 struct lwp_info
*lp
;
1121 /* Ignore LWPs we're already attached to. */
1122 lp
= find_lwp_pid (ptid
);
1125 int lwpid
= ptid
.lwp ();
1127 if (ptrace (PTRACE_ATTACH
, lwpid
, 0, 0) < 0)
1131 /* Be quiet if we simply raced with the thread exiting.
1132 EPERM is returned if the thread's task still exists, and
1133 is marked as exited or zombie, as well as other
1134 conditions, so in that case, confirm the status in
1135 /proc/PID/status. */
1137 || (err
== EPERM
&& linux_proc_pid_is_gone (lwpid
)))
1139 linux_nat_debug_printf
1140 ("Cannot attach to lwp %d: thread is gone (%d: %s)",
1141 lwpid
, err
, safe_strerror (err
));
1147 = linux_ptrace_attach_fail_reason_string (ptid
, err
);
1149 warning (_("Cannot attach to lwp %d: %s"),
1150 lwpid
, reason
.c_str ());
1155 linux_nat_debug_printf ("PTRACE_ATTACH %s, 0, 0 (OK)",
1156 target_pid_to_str (ptid
).c_str ());
1158 lp
= add_lwp (ptid
);
1160 /* The next time we wait for this LWP we'll see a SIGSTOP as
1161 PTRACE_ATTACH brings it to a halt. */
1164 /* We need to wait for a stop before being able to make the
1165 next ptrace call on this LWP. */
1166 lp
->must_set_ptrace_flags
= 1;
1168 /* So that wait collects the SIGSTOP. */
1171 /* Also add the LWP to gdb's thread list, in case a
1172 matching libthread_db is not found (or the process uses
1174 add_thread (linux_target
, lp
->ptid
);
1175 set_running (linux_target
, lp
->ptid
, true);
1176 set_executing (linux_target
, lp
->ptid
, true);
1185 linux_nat_target::attach (const char *args
, int from_tty
)
1187 struct lwp_info
*lp
;
1191 /* Make sure we report all signals during attach. */
1196 inf_ptrace_target::attach (args
, from_tty
);
1198 catch (const gdb_exception_error
&ex
)
1200 pid_t pid
= parse_pid_to_attach (args
);
1201 std::string reason
= linux_ptrace_attach_fail_reason (pid
);
1203 if (!reason
.empty ())
1204 throw_error (ex
.error
, "warning: %s\n%s", reason
.c_str (),
1207 throw_error (ex
.error
, "%s", ex
.what ());
1210 /* The ptrace base target adds the main thread with (pid,0,0)
1211 format. Decorate it with lwp info. */
1212 ptid
= ptid_t (inferior_ptid
.pid (),
1213 inferior_ptid
.pid (),
1215 thread_change_ptid (linux_target
, inferior_ptid
, ptid
);
1217 /* Add the initial process as the first LWP to the list. */
1218 lp
= add_initial_lwp (ptid
);
1220 status
= linux_nat_post_attach_wait (lp
->ptid
, &lp
->signalled
);
1221 if (!WIFSTOPPED (status
))
1223 if (WIFEXITED (status
))
1225 int exit_code
= WEXITSTATUS (status
);
1227 target_terminal::ours ();
1228 target_mourn_inferior (inferior_ptid
);
1230 error (_("Unable to attach: program exited normally."));
1232 error (_("Unable to attach: program exited with code %d."),
1235 else if (WIFSIGNALED (status
))
1237 enum gdb_signal signo
;
1239 target_terminal::ours ();
1240 target_mourn_inferior (inferior_ptid
);
1242 signo
= gdb_signal_from_host (WTERMSIG (status
));
1243 error (_("Unable to attach: program terminated with signal "
1245 gdb_signal_to_name (signo
),
1246 gdb_signal_to_string (signo
));
1249 internal_error (__FILE__
, __LINE__
,
1250 _("unexpected status %d for PID %ld"),
1251 status
, (long) ptid
.lwp ());
1256 /* Save the wait status to report later. */
1258 linux_nat_debug_printf ("waitpid %ld, saving status %s",
1259 (long) lp
->ptid
.pid (), status_to_str (status
));
1261 lp
->status
= status
;
1263 /* We must attach to every LWP. If /proc is mounted, use that to
1264 find them now. The inferior may be using raw clone instead of
1265 using pthreads. But even if it is using pthreads, thread_db
1266 walks structures in the inferior's address space to find the list
1267 of threads/LWPs, and those structures may well be corrupted.
1268 Note that once thread_db is loaded, we'll still use it to list
1269 threads and associate pthread info with each LWP. */
1270 linux_proc_attach_tgid_threads (lp
->ptid
.pid (),
1271 attach_proc_task_lwp_callback
);
1273 if (target_can_async_p ())
1277 /* Get pending signal of THREAD as a host signal number, for detaching
1278 purposes. This is the signal the thread last stopped for, which we
1279 need to deliver to the thread when detaching, otherwise, it'd be
1283 get_detach_signal (struct lwp_info
*lp
)
1285 enum gdb_signal signo
= GDB_SIGNAL_0
;
1287 /* If we paused threads momentarily, we may have stored pending
1288 events in lp->status or lp->waitstatus (see stop_wait_callback),
1289 and GDB core hasn't seen any signal for those threads.
1290 Otherwise, the last signal reported to the core is found in the
1291 thread object's stop_signal.
1293 There's a corner case that isn't handled here at present. Only
1294 if the thread stopped with a TARGET_WAITKIND_STOPPED does
1295 stop_signal make sense as a real signal to pass to the inferior.
1296 Some catchpoint related events, like
1297 TARGET_WAITKIND_(V)FORK|EXEC|SYSCALL, have their stop_signal set
1298 to GDB_SIGNAL_SIGTRAP when the catchpoint triggers. But,
1299 those traps are debug API (ptrace in our case) related and
1300 induced; the inferior wouldn't see them if it wasn't being
1301 traced. Hence, we should never pass them to the inferior, even
1302 when set to pass state. Since this corner case isn't handled by
1303 infrun.c when proceeding with a signal, for consistency, neither
1304 do we handle it here (or elsewhere in the file we check for
1305 signal pass state). Normally SIGTRAP isn't set to pass state, so
1306 this is really a corner case. */
1308 if (lp
->waitstatus
.kind
!= TARGET_WAITKIND_IGNORE
)
1309 signo
= GDB_SIGNAL_0
; /* a pending ptrace event, not a real signal. */
1310 else if (lp
->status
)
1311 signo
= gdb_signal_from_host (WSTOPSIG (lp
->status
));
1314 struct thread_info
*tp
= find_thread_ptid (linux_target
, lp
->ptid
);
1316 if (target_is_non_stop_p () && !tp
->executing
)
1318 if (tp
->suspend
.waitstatus_pending_p
)
1319 signo
= tp
->suspend
.waitstatus
.value
.sig
;
1321 signo
= tp
->suspend
.stop_signal
;
1323 else if (!target_is_non_stop_p ())
1326 process_stratum_target
*last_target
;
1328 get_last_target_status (&last_target
, &last_ptid
, nullptr);
1330 if (last_target
== linux_target
1331 && lp
->ptid
.lwp () == last_ptid
.lwp ())
1332 signo
= tp
->suspend
.stop_signal
;
1336 if (signo
== GDB_SIGNAL_0
)
1338 linux_nat_debug_printf ("lwp %s has no pending signal",
1339 target_pid_to_str (lp
->ptid
).c_str ());
1341 else if (!signal_pass_state (signo
))
1343 linux_nat_debug_printf
1344 ("lwp %s had signal %s but it is in no pass state",
1345 target_pid_to_str (lp
->ptid
).c_str (), gdb_signal_to_string (signo
));
1349 linux_nat_debug_printf ("lwp %s has pending signal %s",
1350 target_pid_to_str (lp
->ptid
).c_str (),
1351 gdb_signal_to_string (signo
));
1353 return gdb_signal_to_host (signo
);
1359 /* Detach from LP. If SIGNO_P is non-NULL, then it points to the
1360 signal number that should be passed to the LWP when detaching.
1361 Otherwise pass any pending signal the LWP may have, if any. */
1364 detach_one_lwp (struct lwp_info
*lp
, int *signo_p
)
1366 int lwpid
= lp
->ptid
.lwp ();
1369 gdb_assert (lp
->status
== 0 || WIFSTOPPED (lp
->status
));
1371 if (lp
->status
!= 0)
1372 linux_nat_debug_printf ("Pending %s for %s on detach.",
1373 strsignal (WSTOPSIG (lp
->status
)),
1374 target_pid_to_str (lp
->ptid
).c_str ());
1376 /* If there is a pending SIGSTOP, get rid of it. */
1379 linux_nat_debug_printf ("Sending SIGCONT to %s",
1380 target_pid_to_str (lp
->ptid
).c_str ());
1382 kill_lwp (lwpid
, SIGCONT
);
1386 if (signo_p
== NULL
)
1388 /* Pass on any pending signal for this LWP. */
1389 signo
= get_detach_signal (lp
);
1394 /* Preparing to resume may try to write registers, and fail if the
1395 lwp is zombie. If that happens, ignore the error. We'll handle
1396 it below, when detach fails with ESRCH. */
1399 linux_target
->low_prepare_to_resume (lp
);
1401 catch (const gdb_exception_error
&ex
)
1403 if (!check_ptrace_stopped_lwp_gone (lp
))
1407 if (ptrace (PTRACE_DETACH
, lwpid
, 0, signo
) < 0)
1409 int save_errno
= errno
;
1411 /* We know the thread exists, so ESRCH must mean the lwp is
1412 zombie. This can happen if one of the already-detached
1413 threads exits the whole thread group. In that case we're
1414 still attached, and must reap the lwp. */
1415 if (save_errno
== ESRCH
)
1419 ret
= my_waitpid (lwpid
, &status
, __WALL
);
1422 warning (_("Couldn't reap LWP %d while detaching: %s"),
1423 lwpid
, safe_strerror (errno
));
1425 else if (!WIFEXITED (status
) && !WIFSIGNALED (status
))
1427 warning (_("Reaping LWP %d while detaching "
1428 "returned unexpected status 0x%x"),
1434 error (_("Can't detach %s: %s"),
1435 target_pid_to_str (lp
->ptid
).c_str (),
1436 safe_strerror (save_errno
));
1440 linux_nat_debug_printf ("PTRACE_DETACH (%s, %s, 0) (OK)",
1441 target_pid_to_str (lp
->ptid
).c_str (),
1444 delete_lwp (lp
->ptid
);
1448 detach_callback (struct lwp_info
*lp
)
1450 /* We don't actually detach from the thread group leader just yet.
1451 If the thread group exits, we must reap the zombie clone lwps
1452 before we're able to reap the leader. */
1453 if (lp
->ptid
.lwp () != lp
->ptid
.pid ())
1454 detach_one_lwp (lp
, NULL
);
1459 linux_nat_target::detach (inferior
*inf
, int from_tty
)
1461 struct lwp_info
*main_lwp
;
1464 /* Don't unregister from the event loop, as there may be other
1465 inferiors running. */
1467 /* Stop all threads before detaching. ptrace requires that the
1468 thread is stopped to successfully detach. */
1469 iterate_over_lwps (ptid_t (pid
), stop_callback
);
1470 /* ... and wait until all of them have reported back that
1471 they're no longer running. */
1472 iterate_over_lwps (ptid_t (pid
), stop_wait_callback
);
1474 iterate_over_lwps (ptid_t (pid
), detach_callback
);
1476 /* Only the initial process should be left right now. */
1477 gdb_assert (num_lwps (pid
) == 1);
1479 main_lwp
= find_lwp_pid (ptid_t (pid
));
1481 if (forks_exist_p ())
1483 /* Multi-fork case. The current inferior_ptid is being detached
1484 from, but there are other viable forks to debug. Detach from
1485 the current fork, and context-switch to the first
1487 linux_fork_detach (from_tty
);
1491 target_announce_detach (from_tty
);
1493 /* Pass on any pending signal for the last LWP. */
1494 int signo
= get_detach_signal (main_lwp
);
1496 detach_one_lwp (main_lwp
, &signo
);
1498 detach_success (inf
);
1502 /* Resume execution of the inferior process. If STEP is nonzero,
1503 single-step it. If SIGNAL is nonzero, give it that signal. */
1506 linux_resume_one_lwp_throw (struct lwp_info
*lp
, int step
,
1507 enum gdb_signal signo
)
1511 /* stop_pc doubles as the PC the LWP had when it was last resumed.
1512 We only presently need that if the LWP is stepped though (to
1513 handle the case of stepping a breakpoint instruction). */
1516 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
1518 lp
->stop_pc
= regcache_read_pc (regcache
);
1523 linux_target
->low_prepare_to_resume (lp
);
1524 linux_target
->low_resume (lp
->ptid
, step
, signo
);
1526 /* Successfully resumed. Clear state that no longer makes sense,
1527 and mark the LWP as running. Must not do this before resuming
1528 otherwise if that fails other code will be confused. E.g., we'd
1529 later try to stop the LWP and hang forever waiting for a stop
1530 status. Note that we must not throw after this is cleared,
1531 otherwise handle_zombie_lwp_error would get confused. */
1534 lp
->stop_reason
= TARGET_STOPPED_BY_NO_REASON
;
1535 registers_changed_ptid (linux_target
, lp
->ptid
);
1538 /* Called when we try to resume a stopped LWP and that errors out. If
1539 the LWP is no longer in ptrace-stopped state (meaning it's zombie,
1540 or about to become), discard the error, clear any pending status
1541 the LWP may have, and return true (we'll collect the exit status
1542 soon enough). Otherwise, return false. */
1545 check_ptrace_stopped_lwp_gone (struct lwp_info
*lp
)
1547 /* If we get an error after resuming the LWP successfully, we'd
1548 confuse !T state for the LWP being gone. */
1549 gdb_assert (lp
->stopped
);
1551 /* We can't just check whether the LWP is in 'Z (Zombie)' state,
1552 because even if ptrace failed with ESRCH, the tracee may be "not
1553 yet fully dead", but already refusing ptrace requests. In that
1554 case the tracee has 'R (Running)' state for a little bit
1555 (observed in Linux 3.18). See also the note on ESRCH in the
1556 ptrace(2) man page. Instead, check whether the LWP has any state
1557 other than ptrace-stopped. */
1559 /* Don't assume anything if /proc/PID/status can't be read. */
1560 if (linux_proc_pid_is_trace_stopped_nowarn (lp
->ptid
.lwp ()) == 0)
1562 lp
->stop_reason
= TARGET_STOPPED_BY_NO_REASON
;
1564 lp
->waitstatus
.kind
= TARGET_WAITKIND_IGNORE
;
1570 /* Like linux_resume_one_lwp_throw, but no error is thrown if the LWP
1571 disappears while we try to resume it. */
1574 linux_resume_one_lwp (struct lwp_info
*lp
, int step
, enum gdb_signal signo
)
1578 linux_resume_one_lwp_throw (lp
, step
, signo
);
1580 catch (const gdb_exception_error
&ex
)
1582 if (!check_ptrace_stopped_lwp_gone (lp
))
1590 resume_lwp (struct lwp_info
*lp
, int step
, enum gdb_signal signo
)
1594 struct inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
1596 if (inf
->vfork_child
!= NULL
)
1598 linux_nat_debug_printf ("Not resuming %s (vfork parent)",
1599 target_pid_to_str (lp
->ptid
).c_str ());
1601 else if (!lwp_status_pending_p (lp
))
1603 linux_nat_debug_printf ("Resuming sibling %s, %s, %s",
1604 target_pid_to_str (lp
->ptid
).c_str (),
1605 (signo
!= GDB_SIGNAL_0
1606 ? strsignal (gdb_signal_to_host (signo
))
1608 step
? "step" : "resume");
1610 linux_resume_one_lwp (lp
, step
, signo
);
1614 linux_nat_debug_printf ("Not resuming sibling %s (has pending)",
1615 target_pid_to_str (lp
->ptid
).c_str ());
1619 linux_nat_debug_printf ("Not resuming sibling %s (not stopped)",
1620 target_pid_to_str (lp
->ptid
).c_str ());
1623 /* Callback for iterate_over_lwps. If LWP is EXCEPT, do nothing.
1624 Resume LWP with the last stop signal, if it is in pass state. */
1627 linux_nat_resume_callback (struct lwp_info
*lp
, struct lwp_info
*except
)
1629 enum gdb_signal signo
= GDB_SIGNAL_0
;
1636 struct thread_info
*thread
;
1638 thread
= find_thread_ptid (linux_target
, lp
->ptid
);
1641 signo
= thread
->suspend
.stop_signal
;
1642 thread
->suspend
.stop_signal
= GDB_SIGNAL_0
;
1646 resume_lwp (lp
, 0, signo
);
1651 resume_clear_callback (struct lwp_info
*lp
)
1654 lp
->last_resume_kind
= resume_stop
;
1659 resume_set_callback (struct lwp_info
*lp
)
1662 lp
->last_resume_kind
= resume_continue
;
1667 linux_nat_target::resume (ptid_t ptid
, int step
, enum gdb_signal signo
)
1669 struct lwp_info
*lp
;
1672 linux_nat_debug_printf ("Preparing to %s %s, %s, inferior_ptid %s",
1673 step
? "step" : "resume",
1674 target_pid_to_str (ptid
).c_str (),
1675 (signo
!= GDB_SIGNAL_0
1676 ? strsignal (gdb_signal_to_host (signo
)) : "0"),
1677 target_pid_to_str (inferior_ptid
).c_str ());
1679 /* A specific PTID means `step only this process id'. */
1680 resume_many
= (minus_one_ptid
== ptid
1683 /* Mark the lwps we're resuming as resumed and update their
1684 last_resume_kind to resume_continue. */
1685 iterate_over_lwps (ptid
, resume_set_callback
);
1687 /* See if it's the current inferior that should be handled
1690 lp
= find_lwp_pid (inferior_ptid
);
1692 lp
= find_lwp_pid (ptid
);
1693 gdb_assert (lp
!= NULL
);
1695 /* Remember if we're stepping. */
1696 lp
->last_resume_kind
= step
? resume_step
: resume_continue
;
1698 /* If we have a pending wait status for this thread, there is no
1699 point in resuming the process. But first make sure that
1700 linux_nat_wait won't preemptively handle the event - we
1701 should never take this short-circuit if we are going to
1702 leave LP running, since we have skipped resuming all the
1703 other threads. This bit of code needs to be synchronized
1704 with linux_nat_wait. */
1706 if (lp
->status
&& WIFSTOPPED (lp
->status
))
1709 && WSTOPSIG (lp
->status
)
1710 && sigismember (&pass_mask
, WSTOPSIG (lp
->status
)))
1712 linux_nat_debug_printf
1713 ("Not short circuiting for ignored status 0x%x", lp
->status
);
1715 /* FIXME: What should we do if we are supposed to continue
1716 this thread with a signal? */
1717 gdb_assert (signo
== GDB_SIGNAL_0
);
1718 signo
= gdb_signal_from_host (WSTOPSIG (lp
->status
));
1723 if (lwp_status_pending_p (lp
))
1725 /* FIXME: What should we do if we are supposed to continue
1726 this thread with a signal? */
1727 gdb_assert (signo
== GDB_SIGNAL_0
);
1729 linux_nat_debug_printf ("Short circuiting for status 0x%x",
1732 if (target_can_async_p ())
1735 /* Tell the event loop we have something to process. */
1742 iterate_over_lwps (ptid
, [=] (struct lwp_info
*info
)
1744 return linux_nat_resume_callback (info
, lp
);
1747 linux_nat_debug_printf ("%s %s, %s (resume event thread)",
1748 step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
1749 target_pid_to_str (lp
->ptid
).c_str (),
1750 (signo
!= GDB_SIGNAL_0
1751 ? strsignal (gdb_signal_to_host (signo
)) : "0"));
1753 linux_resume_one_lwp (lp
, step
, signo
);
1755 if (target_can_async_p ())
1759 /* Send a signal to an LWP. */
1762 kill_lwp (int lwpid
, int signo
)
1767 ret
= syscall (__NR_tkill
, lwpid
, signo
);
1768 if (errno
== ENOSYS
)
1770 /* If tkill fails, then we are not using nptl threads, a
1771 configuration we no longer support. */
1772 perror_with_name (("tkill"));
1777 /* Handle a GNU/Linux syscall trap wait response. If we see a syscall
1778 event, check if the core is interested in it: if not, ignore the
1779 event, and keep waiting; otherwise, we need to toggle the LWP's
1780 syscall entry/exit status, since the ptrace event itself doesn't
1781 indicate it, and report the trap to higher layers. */
1784 linux_handle_syscall_trap (struct lwp_info
*lp
, int stopping
)
1786 struct target_waitstatus
*ourstatus
= &lp
->waitstatus
;
1787 struct gdbarch
*gdbarch
= target_thread_architecture (lp
->ptid
);
1788 thread_info
*thread
= find_thread_ptid (linux_target
, lp
->ptid
);
1789 int syscall_number
= (int) gdbarch_get_syscall_number (gdbarch
, thread
);
1793 /* If we're stopping threads, there's a SIGSTOP pending, which
1794 makes it so that the LWP reports an immediate syscall return,
1795 followed by the SIGSTOP. Skip seeing that "return" using
1796 PTRACE_CONT directly, and let stop_wait_callback collect the
1797 SIGSTOP. Later when the thread is resumed, a new syscall
1798 entry event. If we didn't do this (and returned 0), we'd
1799 leave a syscall entry pending, and our caller, by using
1800 PTRACE_CONT to collect the SIGSTOP, skips the syscall return
1801 itself. Later, when the user re-resumes this LWP, we'd see
1802 another syscall entry event and we'd mistake it for a return.
1804 If stop_wait_callback didn't force the SIGSTOP out of the LWP
1805 (leaving immediately with LWP->signalled set, without issuing
1806 a PTRACE_CONT), it would still be problematic to leave this
1807 syscall enter pending, as later when the thread is resumed,
1808 it would then see the same syscall exit mentioned above,
1809 followed by the delayed SIGSTOP, while the syscall didn't
1810 actually get to execute. It seems it would be even more
1811 confusing to the user. */
1813 linux_nat_debug_printf
1814 ("ignoring syscall %d for LWP %ld (stopping threads), resuming with "
1815 "PTRACE_CONT for SIGSTOP", syscall_number
, lp
->ptid
.lwp ());
1817 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
1818 ptrace (PTRACE_CONT
, lp
->ptid
.lwp (), 0, 0);
1823 /* Always update the entry/return state, even if this particular
1824 syscall isn't interesting to the core now. In async mode,
1825 the user could install a new catchpoint for this syscall
1826 between syscall enter/return, and we'll need to know to
1827 report a syscall return if that happens. */
1828 lp
->syscall_state
= (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1829 ? TARGET_WAITKIND_SYSCALL_RETURN
1830 : TARGET_WAITKIND_SYSCALL_ENTRY
);
1832 if (catch_syscall_enabled ())
1834 if (catching_syscall_number (syscall_number
))
1836 /* Alright, an event to report. */
1837 ourstatus
->kind
= lp
->syscall_state
;
1838 ourstatus
->value
.syscall_number
= syscall_number
;
1840 linux_nat_debug_printf
1841 ("stopping for %s of syscall %d for LWP %ld",
1842 (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1843 ? "entry" : "return"), syscall_number
, lp
->ptid
.lwp ());
1848 linux_nat_debug_printf
1849 ("ignoring %s of syscall %d for LWP %ld",
1850 (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1851 ? "entry" : "return"), syscall_number
, lp
->ptid
.lwp ());
1855 /* If we had been syscall tracing, and hence used PT_SYSCALL
1856 before on this LWP, it could happen that the user removes all
1857 syscall catchpoints before we get to process this event.
1858 There are two noteworthy issues here:
1860 - When stopped at a syscall entry event, resuming with
1861 PT_STEP still resumes executing the syscall and reports a
1864 - Only PT_SYSCALL catches syscall enters. If we last
1865 single-stepped this thread, then this event can't be a
1866 syscall enter. If we last single-stepped this thread, this
1867 has to be a syscall exit.
1869 The points above mean that the next resume, be it PT_STEP or
1870 PT_CONTINUE, can not trigger a syscall trace event. */
1871 linux_nat_debug_printf
1872 ("caught syscall event with no syscall catchpoints. %d for LWP %ld, "
1873 "ignoring", syscall_number
, lp
->ptid
.lwp ());
1874 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
1877 /* The core isn't interested in this event. For efficiency, avoid
1878 stopping all threads only to have the core resume them all again.
1879 Since we're not stopping threads, if we're still syscall tracing
1880 and not stepping, we can't use PTRACE_CONT here, as we'd miss any
1881 subsequent syscall. Simply resume using the inf-ptrace layer,
1882 which knows when to use PT_SYSCALL or PT_CONTINUE. */
1884 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
1888 /* Handle a GNU/Linux extended wait response. If we see a clone
1889 event, we need to add the new LWP to our list (and not report the
1890 trap to higher layers). This function returns non-zero if the
1891 event should be ignored and we should wait again. If STOPPING is
1892 true, the new LWP remains stopped, otherwise it is continued. */
1895 linux_handle_extended_wait (struct lwp_info
*lp
, int status
)
1897 int pid
= lp
->ptid
.lwp ();
1898 struct target_waitstatus
*ourstatus
= &lp
->waitstatus
;
1899 int event
= linux_ptrace_get_extended_event (status
);
1901 /* All extended events we currently use are mid-syscall. Only
1902 PTRACE_EVENT_STOP is delivered more like a signal-stop, but
1903 you have to be using PTRACE_SEIZE to get that. */
1904 lp
->syscall_state
= TARGET_WAITKIND_SYSCALL_ENTRY
;
1906 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
1907 || event
== PTRACE_EVENT_CLONE
)
1909 unsigned long new_pid
;
1912 ptrace (PTRACE_GETEVENTMSG
, pid
, 0, &new_pid
);
1914 /* If we haven't already seen the new PID stop, wait for it now. */
1915 if (! pull_pid_from_list (&stopped_pids
, new_pid
, &status
))
1917 /* The new child has a pending SIGSTOP. We can't affect it until it
1918 hits the SIGSTOP, but we're already attached. */
1919 ret
= my_waitpid (new_pid
, &status
, __WALL
);
1921 perror_with_name (_("waiting for new child"));
1922 else if (ret
!= new_pid
)
1923 internal_error (__FILE__
, __LINE__
,
1924 _("wait returned unexpected PID %d"), ret
);
1925 else if (!WIFSTOPPED (status
))
1926 internal_error (__FILE__
, __LINE__
,
1927 _("wait returned unexpected status 0x%x"), status
);
1930 ourstatus
->value
.related_pid
= ptid_t (new_pid
, new_pid
, 0);
1932 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
)
1934 /* The arch-specific native code may need to know about new
1935 forks even if those end up never mapped to an
1937 linux_target
->low_new_fork (lp
, new_pid
);
1939 else if (event
== PTRACE_EVENT_CLONE
)
1941 linux_target
->low_new_clone (lp
, new_pid
);
1944 if (event
== PTRACE_EVENT_FORK
1945 && linux_fork_checkpointing_p (lp
->ptid
.pid ()))
1947 /* Handle checkpointing by linux-fork.c here as a special
1948 case. We don't want the follow-fork-mode or 'catch fork'
1949 to interfere with this. */
1951 /* This won't actually modify the breakpoint list, but will
1952 physically remove the breakpoints from the child. */
1953 detach_breakpoints (ptid_t (new_pid
, new_pid
, 0));
1955 /* Retain child fork in ptrace (stopped) state. */
1956 if (!find_fork_pid (new_pid
))
1959 /* Report as spurious, so that infrun doesn't want to follow
1960 this fork. We're actually doing an infcall in
1962 ourstatus
->kind
= TARGET_WAITKIND_SPURIOUS
;
1964 /* Report the stop to the core. */
1968 if (event
== PTRACE_EVENT_FORK
)
1969 ourstatus
->kind
= TARGET_WAITKIND_FORKED
;
1970 else if (event
== PTRACE_EVENT_VFORK
)
1971 ourstatus
->kind
= TARGET_WAITKIND_VFORKED
;
1972 else if (event
== PTRACE_EVENT_CLONE
)
1974 struct lwp_info
*new_lp
;
1976 ourstatus
->kind
= TARGET_WAITKIND_IGNORE
;
1978 linux_nat_debug_printf
1979 ("Got clone event from LWP %d, new child is LWP %ld", pid
, new_pid
);
1981 new_lp
= add_lwp (ptid_t (lp
->ptid
.pid (), new_pid
, 0));
1982 new_lp
->stopped
= 1;
1983 new_lp
->resumed
= 1;
1985 /* If the thread_db layer is active, let it record the user
1986 level thread id and status, and add the thread to GDB's
1988 if (!thread_db_notice_clone (lp
->ptid
, new_lp
->ptid
))
1990 /* The process is not using thread_db. Add the LWP to
1992 target_post_attach (new_lp
->ptid
.lwp ());
1993 add_thread (linux_target
, new_lp
->ptid
);
1996 /* Even if we're stopping the thread for some reason
1997 internal to this module, from the perspective of infrun
1998 and the user/frontend, this new thread is running until
1999 it next reports a stop. */
2000 set_running (linux_target
, new_lp
->ptid
, true);
2001 set_executing (linux_target
, new_lp
->ptid
, true);
2003 if (WSTOPSIG (status
) != SIGSTOP
)
2005 /* This can happen if someone starts sending signals to
2006 the new thread before it gets a chance to run, which
2007 have a lower number than SIGSTOP (e.g. SIGUSR1).
2008 This is an unlikely case, and harder to handle for
2009 fork / vfork than for clone, so we do not try - but
2010 we handle it for clone events here. */
2012 new_lp
->signalled
= 1;
2014 /* We created NEW_LP so it cannot yet contain STATUS. */
2015 gdb_assert (new_lp
->status
== 0);
2017 /* Save the wait status to report later. */
2018 linux_nat_debug_printf
2019 ("waitpid of new LWP %ld, saving status %s",
2020 (long) new_lp
->ptid
.lwp (), status_to_str (status
));
2021 new_lp
->status
= status
;
2023 else if (report_thread_events
)
2025 new_lp
->waitstatus
.kind
= TARGET_WAITKIND_THREAD_CREATED
;
2026 new_lp
->status
= status
;
2035 if (event
== PTRACE_EVENT_EXEC
)
2037 linux_nat_debug_printf ("Got exec event from LWP %ld", lp
->ptid
.lwp ());
2039 ourstatus
->kind
= TARGET_WAITKIND_EXECD
;
2040 ourstatus
->value
.execd_pathname
2041 = xstrdup (linux_proc_pid_to_exec_file (pid
));
2043 /* The thread that execed must have been resumed, but, when a
2044 thread execs, it changes its tid to the tgid, and the old
2045 tgid thread might have not been resumed. */
2050 if (event
== PTRACE_EVENT_VFORK_DONE
)
2052 if (current_inferior ()->waiting_for_vfork_done
)
2054 linux_nat_debug_printf
2055 ("Got expected PTRACE_EVENT_VFORK_DONE from LWP %ld: stopping",
2058 ourstatus
->kind
= TARGET_WAITKIND_VFORK_DONE
;
2062 linux_nat_debug_printf
2063 ("Got PTRACE_EVENT_VFORK_DONE from LWP %ld: ignoring", lp
->ptid
.lwp ());
2068 internal_error (__FILE__
, __LINE__
,
2069 _("unknown ptrace event %d"), event
);
2072 /* Suspend waiting for a signal. We're mostly interested in
2078 linux_nat_debug_printf ("about to sigsuspend");
2079 sigsuspend (&suspend_mask
);
2081 /* If the quit flag is set, it means that the user pressed Ctrl-C
2082 and we're debugging a process that is running on a separate
2083 terminal, so we must forward the Ctrl-C to the inferior. (If the
2084 inferior is sharing GDB's terminal, then the Ctrl-C reaches the
2085 inferior directly.) We must do this here because functions that
2086 need to block waiting for a signal loop forever until there's an
2087 event to report before returning back to the event loop. */
2088 if (!target_terminal::is_ours ())
2090 if (check_quit_flag ())
2091 target_pass_ctrlc ();
2095 /* Wait for LP to stop. Returns the wait status, or 0 if the LWP has
2099 wait_lwp (struct lwp_info
*lp
)
2103 int thread_dead
= 0;
2106 gdb_assert (!lp
->stopped
);
2107 gdb_assert (lp
->status
== 0);
2109 /* Make sure SIGCHLD is blocked for sigsuspend avoiding a race below. */
2110 block_child_signals (&prev_mask
);
2114 pid
= my_waitpid (lp
->ptid
.lwp (), &status
, __WALL
| WNOHANG
);
2115 if (pid
== -1 && errno
== ECHILD
)
2117 /* The thread has previously exited. We need to delete it
2118 now because if this was a non-leader thread execing, we
2119 won't get an exit event. See comments on exec events at
2120 the top of the file. */
2122 linux_nat_debug_printf ("%s vanished.",
2123 target_pid_to_str (lp
->ptid
).c_str ());
2128 /* Bugs 10970, 12702.
2129 Thread group leader may have exited in which case we'll lock up in
2130 waitpid if there are other threads, even if they are all zombies too.
2131 Basically, we're not supposed to use waitpid this way.
2132 tkill(pid,0) cannot be used here as it gets ESRCH for both
2133 for zombie and running processes.
2135 As a workaround, check if we're waiting for the thread group leader and
2136 if it's a zombie, and avoid calling waitpid if it is.
2138 This is racy, what if the tgl becomes a zombie right after we check?
2139 Therefore always use WNOHANG with sigsuspend - it is equivalent to
2140 waiting waitpid but linux_proc_pid_is_zombie is safe this way. */
2142 if (lp
->ptid
.pid () == lp
->ptid
.lwp ()
2143 && linux_proc_pid_is_zombie (lp
->ptid
.lwp ()))
2146 linux_nat_debug_printf ("Thread group leader %s vanished.",
2147 target_pid_to_str (lp
->ptid
).c_str ());
2151 /* Wait for next SIGCHLD and try again. This may let SIGCHLD handlers
2152 get invoked despite our caller had them intentionally blocked by
2153 block_child_signals. This is sensitive only to the loop of
2154 linux_nat_wait_1 and there if we get called my_waitpid gets called
2155 again before it gets to sigsuspend so we can safely let the handlers
2156 get executed here. */
2160 restore_child_signals_mask (&prev_mask
);
2164 gdb_assert (pid
== lp
->ptid
.lwp ());
2166 linux_nat_debug_printf ("waitpid %s received %s",
2167 target_pid_to_str (lp
->ptid
).c_str (),
2168 status_to_str (status
));
2170 /* Check if the thread has exited. */
2171 if (WIFEXITED (status
) || WIFSIGNALED (status
))
2173 if (report_thread_events
2174 || lp
->ptid
.pid () == lp
->ptid
.lwp ())
2176 linux_nat_debug_printf ("LWP %d exited.", lp
->ptid
.pid ());
2178 /* If this is the leader exiting, it means the whole
2179 process is gone. Store the status to report to the
2180 core. Store it in lp->waitstatus, because lp->status
2181 would be ambiguous (W_EXITCODE(0,0) == 0). */
2182 store_waitstatus (&lp
->waitstatus
, status
);
2187 linux_nat_debug_printf ("%s exited.",
2188 target_pid_to_str (lp
->ptid
).c_str ());
2198 gdb_assert (WIFSTOPPED (status
));
2201 if (lp
->must_set_ptrace_flags
)
2203 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2204 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
2206 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
2207 lp
->must_set_ptrace_flags
= 0;
2210 /* Handle GNU/Linux's syscall SIGTRAPs. */
2211 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
2213 /* No longer need the sysgood bit. The ptrace event ends up
2214 recorded in lp->waitstatus if we care for it. We can carry
2215 on handling the event like a regular SIGTRAP from here
2217 status
= W_STOPCODE (SIGTRAP
);
2218 if (linux_handle_syscall_trap (lp
, 1))
2219 return wait_lwp (lp
);
2223 /* Almost all other ptrace-stops are known to be outside of system
2224 calls, with further exceptions in linux_handle_extended_wait. */
2225 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
2228 /* Handle GNU/Linux's extended waitstatus for trace events. */
2229 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
2230 && linux_is_extended_waitstatus (status
))
2232 linux_nat_debug_printf ("Handling extended status 0x%06x", status
);
2233 linux_handle_extended_wait (lp
, status
);
2240 /* Send a SIGSTOP to LP. */
2243 stop_callback (struct lwp_info
*lp
)
2245 if (!lp
->stopped
&& !lp
->signalled
)
2249 linux_nat_debug_printf ("kill %s **<SIGSTOP>**",
2250 target_pid_to_str (lp
->ptid
).c_str ());
2253 ret
= kill_lwp (lp
->ptid
.lwp (), SIGSTOP
);
2254 linux_nat_debug_printf ("lwp kill %d %s", ret
,
2255 errno
? safe_strerror (errno
) : "ERRNO-OK");
2258 gdb_assert (lp
->status
== 0);
2264 /* Request a stop on LWP. */
2267 linux_stop_lwp (struct lwp_info
*lwp
)
2269 stop_callback (lwp
);
2272 /* See linux-nat.h */
2275 linux_stop_and_wait_all_lwps (void)
2277 /* Stop all LWP's ... */
2278 iterate_over_lwps (minus_one_ptid
, stop_callback
);
2280 /* ... and wait until all of them have reported back that
2281 they're no longer running. */
2282 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
2285 /* See linux-nat.h */
2288 linux_unstop_all_lwps (void)
2290 iterate_over_lwps (minus_one_ptid
,
2291 [] (struct lwp_info
*info
)
2293 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
2297 /* Return non-zero if LWP PID has a pending SIGINT. */
2300 linux_nat_has_pending_sigint (int pid
)
2302 sigset_t pending
, blocked
, ignored
;
2304 linux_proc_pending_signals (pid
, &pending
, &blocked
, &ignored
);
2306 if (sigismember (&pending
, SIGINT
)
2307 && !sigismember (&ignored
, SIGINT
))
2313 /* Set a flag in LP indicating that we should ignore its next SIGINT. */
2316 set_ignore_sigint (struct lwp_info
*lp
)
2318 /* If a thread has a pending SIGINT, consume it; otherwise, set a
2319 flag to consume the next one. */
2320 if (lp
->stopped
&& lp
->status
!= 0 && WIFSTOPPED (lp
->status
)
2321 && WSTOPSIG (lp
->status
) == SIGINT
)
2324 lp
->ignore_sigint
= 1;
2329 /* If LP does not have a SIGINT pending, then clear the ignore_sigint flag.
2330 This function is called after we know the LWP has stopped; if the LWP
2331 stopped before the expected SIGINT was delivered, then it will never have
2332 arrived. Also, if the signal was delivered to a shared queue and consumed
2333 by a different thread, it will never be delivered to this LWP. */
2336 maybe_clear_ignore_sigint (struct lwp_info
*lp
)
2338 if (!lp
->ignore_sigint
)
2341 if (!linux_nat_has_pending_sigint (lp
->ptid
.lwp ()))
2343 linux_nat_debug_printf ("Clearing bogus flag for %s",
2344 target_pid_to_str (lp
->ptid
).c_str ());
2345 lp
->ignore_sigint
= 0;
2349 /* Fetch the possible triggered data watchpoint info and store it in
2352 On some archs, like x86, that use debug registers to set
2353 watchpoints, it's possible that the way to know which watched
2354 address trapped, is to check the register that is used to select
2355 which address to watch. Problem is, between setting the watchpoint
2356 and reading back which data address trapped, the user may change
2357 the set of watchpoints, and, as a consequence, GDB changes the
2358 debug registers in the inferior. To avoid reading back a stale
2359 stopped-data-address when that happens, we cache in LP the fact
2360 that a watchpoint trapped, and the corresponding data address, as
2361 soon as we see LP stop with a SIGTRAP. If GDB changes the debug
2362 registers meanwhile, we have the cached data we can rely on. */
2365 check_stopped_by_watchpoint (struct lwp_info
*lp
)
2367 scoped_restore save_inferior_ptid
= make_scoped_restore (&inferior_ptid
);
2368 inferior_ptid
= lp
->ptid
;
2370 if (linux_target
->low_stopped_by_watchpoint ())
2372 lp
->stop_reason
= TARGET_STOPPED_BY_WATCHPOINT
;
2373 lp
->stopped_data_address_p
2374 = linux_target
->low_stopped_data_address (&lp
->stopped_data_address
);
2377 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2380 /* Returns true if the LWP had stopped for a watchpoint. */
2383 linux_nat_target::stopped_by_watchpoint ()
2385 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2387 gdb_assert (lp
!= NULL
);
2389 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2393 linux_nat_target::stopped_data_address (CORE_ADDR
*addr_p
)
2395 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2397 gdb_assert (lp
!= NULL
);
2399 *addr_p
= lp
->stopped_data_address
;
2401 return lp
->stopped_data_address_p
;
2404 /* Commonly any breakpoint / watchpoint generate only SIGTRAP. */
2407 linux_nat_target::low_status_is_event (int status
)
2409 return WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
;
2412 /* Wait until LP is stopped. */
2415 stop_wait_callback (struct lwp_info
*lp
)
2417 inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
2419 /* If this is a vfork parent, bail out, it is not going to report
2420 any SIGSTOP until the vfork is done with. */
2421 if (inf
->vfork_child
!= NULL
)
2428 status
= wait_lwp (lp
);
2432 if (lp
->ignore_sigint
&& WIFSTOPPED (status
)
2433 && WSTOPSIG (status
) == SIGINT
)
2435 lp
->ignore_sigint
= 0;
2438 ptrace (PTRACE_CONT
, lp
->ptid
.lwp (), 0, 0);
2440 linux_nat_debug_printf
2441 ("PTRACE_CONT %s, 0, 0 (%s) (discarding SIGINT)",
2442 target_pid_to_str (lp
->ptid
).c_str (),
2443 errno
? safe_strerror (errno
) : "OK");
2445 return stop_wait_callback (lp
);
2448 maybe_clear_ignore_sigint (lp
);
2450 if (WSTOPSIG (status
) != SIGSTOP
)
2452 /* The thread was stopped with a signal other than SIGSTOP. */
2454 linux_nat_debug_printf ("Pending event %s in %s",
2455 status_to_str ((int) status
),
2456 target_pid_to_str (lp
->ptid
).c_str ());
2458 /* Save the sigtrap event. */
2459 lp
->status
= status
;
2460 gdb_assert (lp
->signalled
);
2461 save_stop_reason (lp
);
2465 /* We caught the SIGSTOP that we intended to catch. */
2467 linux_nat_debug_printf ("Expected SIGSTOP caught for %s.",
2468 target_pid_to_str (lp
->ptid
).c_str ());
2472 /* If we are waiting for this stop so we can report the thread
2473 stopped then we need to record this status. Otherwise, we can
2474 now discard this stop event. */
2475 if (lp
->last_resume_kind
== resume_stop
)
2477 lp
->status
= status
;
2478 save_stop_reason (lp
);
2486 /* Return non-zero if LP has a wait status pending. Discard the
2487 pending event and resume the LWP if the event that originally
2488 caused the stop became uninteresting. */
2491 status_callback (struct lwp_info
*lp
)
2493 /* Only report a pending wait status if we pretend that this has
2494 indeed been resumed. */
2498 if (!lwp_status_pending_p (lp
))
2501 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
2502 || lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2504 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2508 pc
= regcache_read_pc (regcache
);
2510 if (pc
!= lp
->stop_pc
)
2512 linux_nat_debug_printf ("PC of %s changed. was=%s, now=%s",
2513 target_pid_to_str (lp
->ptid
).c_str (),
2514 paddress (target_gdbarch (), lp
->stop_pc
),
2515 paddress (target_gdbarch (), pc
));
2519 #if !USE_SIGTRAP_SIGINFO
2520 else if (!breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2522 linux_nat_debug_printf ("previous breakpoint of %s, at %s gone",
2523 target_pid_to_str (lp
->ptid
).c_str (),
2524 paddress (target_gdbarch (), lp
->stop_pc
));
2532 linux_nat_debug_printf ("pending event of %s cancelled.",
2533 target_pid_to_str (lp
->ptid
).c_str ());
2536 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2544 /* Count the LWP's that have had events. */
2547 count_events_callback (struct lwp_info
*lp
, int *count
)
2549 gdb_assert (count
!= NULL
);
2551 /* Select only resumed LWPs that have an event pending. */
2552 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2558 /* Select the LWP (if any) that is currently being single-stepped. */
2561 select_singlestep_lwp_callback (struct lwp_info
*lp
)
2563 if (lp
->last_resume_kind
== resume_step
2570 /* Returns true if LP has a status pending. */
2573 lwp_status_pending_p (struct lwp_info
*lp
)
2575 /* We check for lp->waitstatus in addition to lp->status, because we
2576 can have pending process exits recorded in lp->status and
2577 W_EXITCODE(0,0) happens to be 0. */
2578 return lp
->status
!= 0 || lp
->waitstatus
.kind
!= TARGET_WAITKIND_IGNORE
;
2581 /* Select the Nth LWP that has had an event. */
2584 select_event_lwp_callback (struct lwp_info
*lp
, int *selector
)
2586 gdb_assert (selector
!= NULL
);
2588 /* Select only resumed LWPs that have an event pending. */
2589 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2590 if ((*selector
)-- == 0)
2596 /* Called when the LWP stopped for a signal/trap. If it stopped for a
2597 trap check what caused it (breakpoint, watchpoint, trace, etc.),
2598 and save the result in the LWP's stop_reason field. If it stopped
2599 for a breakpoint, decrement the PC if necessary on the lwp's
2603 save_stop_reason (struct lwp_info
*lp
)
2605 struct regcache
*regcache
;
2606 struct gdbarch
*gdbarch
;
2609 #if USE_SIGTRAP_SIGINFO
2613 gdb_assert (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
);
2614 gdb_assert (lp
->status
!= 0);
2616 if (!linux_target
->low_status_is_event (lp
->status
))
2619 regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2620 gdbarch
= regcache
->arch ();
2622 pc
= regcache_read_pc (regcache
);
2623 sw_bp_pc
= pc
- gdbarch_decr_pc_after_break (gdbarch
);
2625 #if USE_SIGTRAP_SIGINFO
2626 if (linux_nat_get_siginfo (lp
->ptid
, &siginfo
))
2628 if (siginfo
.si_signo
== SIGTRAP
)
2630 if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
)
2631 && GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2633 /* The si_code is ambiguous on this arch -- check debug
2635 if (!check_stopped_by_watchpoint (lp
))
2636 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2638 else if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
))
2640 /* If we determine the LWP stopped for a SW breakpoint,
2641 trust it. Particularly don't check watchpoint
2642 registers, because, at least on s390, we'd find
2643 stopped-by-watchpoint as long as there's a watchpoint
2645 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2647 else if (GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2649 /* This can indicate either a hardware breakpoint or
2650 hardware watchpoint. Check debug registers. */
2651 if (!check_stopped_by_watchpoint (lp
))
2652 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2654 else if (siginfo
.si_code
== TRAP_TRACE
)
2656 linux_nat_debug_printf ("%s stopped by trace",
2657 target_pid_to_str (lp
->ptid
).c_str ());
2659 /* We may have single stepped an instruction that
2660 triggered a watchpoint. In that case, on some
2661 architectures (such as x86), instead of TRAP_HWBKPT,
2662 si_code indicates TRAP_TRACE, and we need to check
2663 the debug registers separately. */
2664 check_stopped_by_watchpoint (lp
);
2669 if ((!lp
->step
|| lp
->stop_pc
== sw_bp_pc
)
2670 && software_breakpoint_inserted_here_p (regcache
->aspace (),
2673 /* The LWP was either continued, or stepped a software
2674 breakpoint instruction. */
2675 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2678 if (hardware_breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2679 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2681 if (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
)
2682 check_stopped_by_watchpoint (lp
);
2685 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
)
2687 linux_nat_debug_printf ("%s stopped by software breakpoint",
2688 target_pid_to_str (lp
->ptid
).c_str ());
2690 /* Back up the PC if necessary. */
2692 regcache_write_pc (regcache
, sw_bp_pc
);
2694 /* Update this so we record the correct stop PC below. */
2697 else if (lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2699 linux_nat_debug_printf ("%s stopped by hardware breakpoint",
2700 target_pid_to_str (lp
->ptid
).c_str ());
2702 else if (lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
)
2704 linux_nat_debug_printf ("%s stopped by hardware watchpoint",
2705 target_pid_to_str (lp
->ptid
).c_str ());
2712 /* Returns true if the LWP had stopped for a software breakpoint. */
2715 linux_nat_target::stopped_by_sw_breakpoint ()
2717 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2719 gdb_assert (lp
!= NULL
);
2721 return lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
;
2724 /* Implement the supports_stopped_by_sw_breakpoint method. */
2727 linux_nat_target::supports_stopped_by_sw_breakpoint ()
2729 return USE_SIGTRAP_SIGINFO
;
2732 /* Returns true if the LWP had stopped for a hardware
2733 breakpoint/watchpoint. */
2736 linux_nat_target::stopped_by_hw_breakpoint ()
2738 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2740 gdb_assert (lp
!= NULL
);
2742 return lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
;
2745 /* Implement the supports_stopped_by_hw_breakpoint method. */
2748 linux_nat_target::supports_stopped_by_hw_breakpoint ()
2750 return USE_SIGTRAP_SIGINFO
;
2753 /* Select one LWP out of those that have events pending. */
2756 select_event_lwp (ptid_t filter
, struct lwp_info
**orig_lp
, int *status
)
2759 int random_selector
;
2760 struct lwp_info
*event_lp
= NULL
;
2762 /* Record the wait status for the original LWP. */
2763 (*orig_lp
)->status
= *status
;
2765 /* In all-stop, give preference to the LWP that is being
2766 single-stepped. There will be at most one, and it will be the
2767 LWP that the core is most interested in. If we didn't do this,
2768 then we'd have to handle pending step SIGTRAPs somehow in case
2769 the core later continues the previously-stepped thread, as
2770 otherwise we'd report the pending SIGTRAP then, and the core, not
2771 having stepped the thread, wouldn't understand what the trap was
2772 for, and therefore would report it to the user as a random
2774 if (!target_is_non_stop_p ())
2776 event_lp
= iterate_over_lwps (filter
, select_singlestep_lwp_callback
);
2777 if (event_lp
!= NULL
)
2779 linux_nat_debug_printf ("Select single-step %s",
2780 target_pid_to_str (event_lp
->ptid
).c_str ());
2784 if (event_lp
== NULL
)
2786 /* Pick one at random, out of those which have had events. */
2788 /* First see how many events we have. */
2789 iterate_over_lwps (filter
,
2790 [&] (struct lwp_info
*info
)
2792 return count_events_callback (info
, &num_events
);
2794 gdb_assert (num_events
> 0);
2796 /* Now randomly pick a LWP out of those that have had
2798 random_selector
= (int)
2799 ((num_events
* (double) rand ()) / (RAND_MAX
+ 1.0));
2802 linux_nat_debug_printf ("Found %d events, selecting #%d",
2803 num_events
, random_selector
);
2806 = (iterate_over_lwps
2808 [&] (struct lwp_info
*info
)
2810 return select_event_lwp_callback (info
,
2815 if (event_lp
!= NULL
)
2817 /* Switch the event LWP. */
2818 *orig_lp
= event_lp
;
2819 *status
= event_lp
->status
;
2822 /* Flush the wait status for the event LWP. */
2823 (*orig_lp
)->status
= 0;
2826 /* Return non-zero if LP has been resumed. */
2829 resumed_callback (struct lwp_info
*lp
)
2834 /* Check if we should go on and pass this event to common code.
2835 Return the affected lwp if we should, or NULL otherwise. */
2837 static struct lwp_info
*
2838 linux_nat_filter_event (int lwpid
, int status
)
2840 struct lwp_info
*lp
;
2841 int event
= linux_ptrace_get_extended_event (status
);
2843 lp
= find_lwp_pid (ptid_t (lwpid
));
2845 /* Check for stop events reported by a process we didn't already
2846 know about - anything not already in our LWP list.
2848 If we're expecting to receive stopped processes after
2849 fork, vfork, and clone events, then we'll just add the
2850 new one to our list and go back to waiting for the event
2851 to be reported - the stopped process might be returned
2852 from waitpid before or after the event is.
2854 But note the case of a non-leader thread exec'ing after the
2855 leader having exited, and gone from our lists. The non-leader
2856 thread changes its tid to the tgid. */
2858 if (WIFSTOPPED (status
) && lp
== NULL
2859 && (WSTOPSIG (status
) == SIGTRAP
&& event
== PTRACE_EVENT_EXEC
))
2861 /* A multi-thread exec after we had seen the leader exiting. */
2862 linux_nat_debug_printf ("Re-adding thread group leader LWP %d.", lwpid
);
2864 lp
= add_lwp (ptid_t (lwpid
, lwpid
, 0));
2867 add_thread (linux_target
, lp
->ptid
);
2870 if (WIFSTOPPED (status
) && !lp
)
2872 linux_nat_debug_printf ("saving LWP %ld status %s in stopped_pids list",
2873 (long) lwpid
, status_to_str (status
));
2874 add_to_pid_list (&stopped_pids
, lwpid
, status
);
2878 /* Make sure we don't report an event for the exit of an LWP not in
2879 our list, i.e. not part of the current process. This can happen
2880 if we detach from a program we originally forked and then it
2882 if (!WIFSTOPPED (status
) && !lp
)
2885 /* This LWP is stopped now. (And if dead, this prevents it from
2886 ever being continued.) */
2889 if (WIFSTOPPED (status
) && lp
->must_set_ptrace_flags
)
2891 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2892 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
2894 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
2895 lp
->must_set_ptrace_flags
= 0;
2898 /* Handle GNU/Linux's syscall SIGTRAPs. */
2899 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
2901 /* No longer need the sysgood bit. The ptrace event ends up
2902 recorded in lp->waitstatus if we care for it. We can carry
2903 on handling the event like a regular SIGTRAP from here
2905 status
= W_STOPCODE (SIGTRAP
);
2906 if (linux_handle_syscall_trap (lp
, 0))
2911 /* Almost all other ptrace-stops are known to be outside of system
2912 calls, with further exceptions in linux_handle_extended_wait. */
2913 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
2916 /* Handle GNU/Linux's extended waitstatus for trace events. */
2917 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
2918 && linux_is_extended_waitstatus (status
))
2920 linux_nat_debug_printf ("Handling extended status 0x%06x", status
);
2922 if (linux_handle_extended_wait (lp
, status
))
2926 /* Check if the thread has exited. */
2927 if (WIFEXITED (status
) || WIFSIGNALED (status
))
2929 if (!report_thread_events
2930 && num_lwps (lp
->ptid
.pid ()) > 1)
2932 linux_nat_debug_printf ("%s exited.",
2933 target_pid_to_str (lp
->ptid
).c_str ());
2935 /* If there is at least one more LWP, then the exit signal
2936 was not the end of the debugged application and should be
2942 /* Note that even if the leader was ptrace-stopped, it can still
2943 exit, if e.g., some other thread brings down the whole
2944 process (calls `exit'). So don't assert that the lwp is
2946 linux_nat_debug_printf ("LWP %ld exited (resumed=%d)",
2947 lp
->ptid
.lwp (), lp
->resumed
);
2949 /* Dead LWP's aren't expected to reported a pending sigstop. */
2952 /* Store the pending event in the waitstatus, because
2953 W_EXITCODE(0,0) == 0. */
2954 store_waitstatus (&lp
->waitstatus
, status
);
2958 /* Make sure we don't report a SIGSTOP that we sent ourselves in
2959 an attempt to stop an LWP. */
2961 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGSTOP
)
2965 if (lp
->last_resume_kind
== resume_stop
)
2967 linux_nat_debug_printf ("resume_stop SIGSTOP caught for %s.",
2968 target_pid_to_str (lp
->ptid
).c_str ());
2972 /* This is a delayed SIGSTOP. Filter out the event. */
2974 linux_nat_debug_printf
2975 ("%s %s, 0, 0 (discard delayed SIGSTOP)",
2976 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
2977 target_pid_to_str (lp
->ptid
).c_str ());
2979 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2980 gdb_assert (lp
->resumed
);
2985 /* Make sure we don't report a SIGINT that we have already displayed
2986 for another thread. */
2987 if (lp
->ignore_sigint
2988 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGINT
)
2990 linux_nat_debug_printf ("Delayed SIGINT caught for %s.",
2991 target_pid_to_str (lp
->ptid
).c_str ());
2993 /* This is a delayed SIGINT. */
2994 lp
->ignore_sigint
= 0;
2996 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2997 linux_nat_debug_printf ("%s %s, 0, 0 (discard SIGINT)",
2998 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
2999 target_pid_to_str (lp
->ptid
).c_str ());
3000 gdb_assert (lp
->resumed
);
3002 /* Discard the event. */
3006 /* Don't report signals that GDB isn't interested in, such as
3007 signals that are neither printed nor stopped upon. Stopping all
3008 threads can be a bit time-consuming, so if we want decent
3009 performance with heavily multi-threaded programs, especially when
3010 they're using a high frequency timer, we'd better avoid it if we
3012 if (WIFSTOPPED (status
))
3014 enum gdb_signal signo
= gdb_signal_from_host (WSTOPSIG (status
));
3016 if (!target_is_non_stop_p ())
3018 /* Only do the below in all-stop, as we currently use SIGSTOP
3019 to implement target_stop (see linux_nat_stop) in
3021 if (signo
== GDB_SIGNAL_INT
&& signal_pass_state (signo
) == 0)
3023 /* If ^C/BREAK is typed at the tty/console, SIGINT gets
3024 forwarded to the entire process group, that is, all LWPs
3025 will receive it - unless they're using CLONE_THREAD to
3026 share signals. Since we only want to report it once, we
3027 mark it as ignored for all LWPs except this one. */
3028 iterate_over_lwps (ptid_t (lp
->ptid
.pid ()), set_ignore_sigint
);
3029 lp
->ignore_sigint
= 0;
3032 maybe_clear_ignore_sigint (lp
);
3035 /* When using hardware single-step, we need to report every signal.
3036 Otherwise, signals in pass_mask may be short-circuited
3037 except signals that might be caused by a breakpoint, or SIGSTOP
3038 if we sent the SIGSTOP and are waiting for it to arrive. */
3040 && WSTOPSIG (status
) && sigismember (&pass_mask
, WSTOPSIG (status
))
3041 && (WSTOPSIG (status
) != SIGSTOP
3042 || !find_thread_ptid (linux_target
, lp
->ptid
)->stop_requested
)
3043 && !linux_wstatus_maybe_breakpoint (status
))
3045 linux_resume_one_lwp (lp
, lp
->step
, signo
);
3046 linux_nat_debug_printf
3047 ("%s %s, %s (preempt 'handle')",
3048 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
3049 target_pid_to_str (lp
->ptid
).c_str (),
3050 (signo
!= GDB_SIGNAL_0
3051 ? strsignal (gdb_signal_to_host (signo
)) : "0"));
3056 /* An interesting event. */
3058 lp
->status
= status
;
3059 save_stop_reason (lp
);
3063 /* Detect zombie thread group leaders, and "exit" them. We can't reap
3064 their exits until all other threads in the group have exited. */
3067 check_zombie_leaders (void)
3069 for (inferior
*inf
: all_inferiors ())
3071 struct lwp_info
*leader_lp
;
3076 leader_lp
= find_lwp_pid (ptid_t (inf
->pid
));
3077 if (leader_lp
!= NULL
3078 /* Check if there are other threads in the group, as we may
3079 have raced with the inferior simply exiting. */
3080 && num_lwps (inf
->pid
) > 1
3081 && linux_proc_pid_is_zombie (inf
->pid
))
3083 linux_nat_debug_printf ("Thread group leader %d zombie "
3084 "(it exited, or another thread execd).",
3087 /* A leader zombie can mean one of two things:
3089 - It exited, and there's an exit status pending
3090 available, or only the leader exited (not the whole
3091 program). In the latter case, we can't waitpid the
3092 leader's exit status until all other threads are gone.
3094 - There are 3 or more threads in the group, and a thread
3095 other than the leader exec'd. See comments on exec
3096 events at the top of the file. We could try
3097 distinguishing the exit and exec cases, by waiting once
3098 more, and seeing if something comes out, but it doesn't
3099 sound useful. The previous leader _does_ go away, and
3100 we'll re-add the new one once we see the exec event
3101 (which is just the same as what would happen if the
3102 previous leader did exit voluntarily before some other
3105 linux_nat_debug_printf ("Thread group leader %d vanished.", inf
->pid
);
3106 exit_lwp (leader_lp
);
3111 /* Convenience function that is called when the kernel reports an exit
3112 event. This decides whether to report the event to GDB as a
3113 process exit event, a thread exit event, or to suppress the
3117 filter_exit_event (struct lwp_info
*event_child
,
3118 struct target_waitstatus
*ourstatus
)
3120 ptid_t ptid
= event_child
->ptid
;
3122 if (num_lwps (ptid
.pid ()) > 1)
3124 if (report_thread_events
)
3125 ourstatus
->kind
= TARGET_WAITKIND_THREAD_EXITED
;
3127 ourstatus
->kind
= TARGET_WAITKIND_IGNORE
;
3129 exit_lwp (event_child
);
3136 linux_nat_wait_1 (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3140 enum resume_kind last_resume_kind
;
3141 struct lwp_info
*lp
;
3144 linux_nat_debug_printf ("enter");
3146 /* The first time we get here after starting a new inferior, we may
3147 not have added it to the LWP list yet - this is the earliest
3148 moment at which we know its PID. */
3149 if (inferior_ptid
.is_pid ())
3151 /* Upgrade the main thread's ptid. */
3152 thread_change_ptid (linux_target
, inferior_ptid
,
3153 ptid_t (inferior_ptid
.pid (),
3154 inferior_ptid
.pid (), 0));
3156 lp
= add_initial_lwp (inferior_ptid
);
3160 /* Make sure SIGCHLD is blocked until the sigsuspend below. */
3161 block_child_signals (&prev_mask
);
3163 /* First check if there is a LWP with a wait status pending. */
3164 lp
= iterate_over_lwps (ptid
, status_callback
);
3167 linux_nat_debug_printf ("Using pending wait status %s for %s.",
3168 status_to_str (lp
->status
),
3169 target_pid_to_str (lp
->ptid
).c_str ());
3172 /* But if we don't find a pending event, we'll have to wait. Always
3173 pull all events out of the kernel. We'll randomly select an
3174 event LWP out of all that have events, to prevent starvation. */
3180 /* Always use -1 and WNOHANG, due to couple of a kernel/ptrace
3183 - If the thread group leader exits while other threads in the
3184 thread group still exist, waitpid(TGID, ...) hangs. That
3185 waitpid won't return an exit status until the other threads
3186 in the group are reaped.
3188 - When a non-leader thread execs, that thread just vanishes
3189 without reporting an exit (so we'd hang if we waited for it
3190 explicitly in that case). The exec event is reported to
3194 lwpid
= my_waitpid (-1, &status
, __WALL
| WNOHANG
);
3196 linux_nat_debug_printf ("waitpid(-1, ...) returned %d, %s",
3198 errno
? safe_strerror (errno
) : "ERRNO-OK");
3202 linux_nat_debug_printf ("waitpid %ld received %s",
3203 (long) lwpid
, status_to_str (status
));
3205 linux_nat_filter_event (lwpid
, status
);
3206 /* Retry until nothing comes out of waitpid. A single
3207 SIGCHLD can indicate more than one child stopped. */
3211 /* Now that we've pulled all events out of the kernel, resume
3212 LWPs that don't have an interesting event to report. */
3213 iterate_over_lwps (minus_one_ptid
,
3214 [] (struct lwp_info
*info
)
3216 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
3219 /* ... and find an LWP with a status to report to the core, if
3221 lp
= iterate_over_lwps (ptid
, status_callback
);
3225 /* Check for zombie thread group leaders. Those can't be reaped
3226 until all other threads in the thread group are. */
3227 check_zombie_leaders ();
3229 /* If there are no resumed children left, bail. We'd be stuck
3230 forever in the sigsuspend call below otherwise. */
3231 if (iterate_over_lwps (ptid
, resumed_callback
) == NULL
)
3233 linux_nat_debug_printf ("exit (no resumed LWP)");
3235 ourstatus
->kind
= TARGET_WAITKIND_NO_RESUMED
;
3237 restore_child_signals_mask (&prev_mask
);
3238 return minus_one_ptid
;
3241 /* No interesting event to report to the core. */
3243 if (target_options
& TARGET_WNOHANG
)
3245 linux_nat_debug_printf ("exit (ignore)");
3247 ourstatus
->kind
= TARGET_WAITKIND_IGNORE
;
3248 restore_child_signals_mask (&prev_mask
);
3249 return minus_one_ptid
;
3252 /* We shouldn't end up here unless we want to try again. */
3253 gdb_assert (lp
== NULL
);
3255 /* Block until we get an event reported with SIGCHLD. */
3261 status
= lp
->status
;
3264 if (!target_is_non_stop_p ())
3266 /* Now stop all other LWP's ... */
3267 iterate_over_lwps (minus_one_ptid
, stop_callback
);
3269 /* ... and wait until all of them have reported back that
3270 they're no longer running. */
3271 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
3274 /* If we're not waiting for a specific LWP, choose an event LWP from
3275 among those that have had events. Giving equal priority to all
3276 LWPs that have had events helps prevent starvation. */
3277 if (ptid
== minus_one_ptid
|| ptid
.is_pid ())
3278 select_event_lwp (ptid
, &lp
, &status
);
3280 gdb_assert (lp
!= NULL
);
3282 /* Now that we've selected our final event LWP, un-adjust its PC if
3283 it was a software breakpoint, and we can't reliably support the
3284 "stopped by software breakpoint" stop reason. */
3285 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
3286 && !USE_SIGTRAP_SIGINFO
)
3288 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3289 struct gdbarch
*gdbarch
= regcache
->arch ();
3290 int decr_pc
= gdbarch_decr_pc_after_break (gdbarch
);
3296 pc
= regcache_read_pc (regcache
);
3297 regcache_write_pc (regcache
, pc
+ decr_pc
);
3301 /* We'll need this to determine whether to report a SIGSTOP as
3302 GDB_SIGNAL_0. Need to take a copy because resume_clear_callback
3304 last_resume_kind
= lp
->last_resume_kind
;
3306 if (!target_is_non_stop_p ())
3308 /* In all-stop, from the core's perspective, all LWPs are now
3309 stopped until a new resume action is sent over. */
3310 iterate_over_lwps (minus_one_ptid
, resume_clear_callback
);
3314 resume_clear_callback (lp
);
3317 if (linux_target
->low_status_is_event (status
))
3319 linux_nat_debug_printf ("trap ptid is %s.",
3320 target_pid_to_str (lp
->ptid
).c_str ());
3323 if (lp
->waitstatus
.kind
!= TARGET_WAITKIND_IGNORE
)
3325 *ourstatus
= lp
->waitstatus
;
3326 lp
->waitstatus
.kind
= TARGET_WAITKIND_IGNORE
;
3329 store_waitstatus (ourstatus
, status
);
3331 linux_nat_debug_printf ("exit");
3333 restore_child_signals_mask (&prev_mask
);
3335 if (last_resume_kind
== resume_stop
3336 && ourstatus
->kind
== TARGET_WAITKIND_STOPPED
3337 && WSTOPSIG (status
) == SIGSTOP
)
3339 /* A thread that has been requested to stop by GDB with
3340 target_stop, and it stopped cleanly, so report as SIG0. The
3341 use of SIGSTOP is an implementation detail. */
3342 ourstatus
->value
.sig
= GDB_SIGNAL_0
;
3345 if (ourstatus
->kind
== TARGET_WAITKIND_EXITED
3346 || ourstatus
->kind
== TARGET_WAITKIND_SIGNALLED
)
3349 lp
->core
= linux_common_core_of_thread (lp
->ptid
);
3351 if (ourstatus
->kind
== TARGET_WAITKIND_EXITED
)
3352 return filter_exit_event (lp
, ourstatus
);
3357 /* Resume LWPs that are currently stopped without any pending status
3358 to report, but are resumed from the core's perspective. */
3361 resume_stopped_resumed_lwps (struct lwp_info
*lp
, const ptid_t wait_ptid
)
3365 linux_nat_debug_printf ("NOT resuming LWP %s, not stopped",
3366 target_pid_to_str (lp
->ptid
).c_str ());
3368 else if (!lp
->resumed
)
3370 linux_nat_debug_printf ("NOT resuming LWP %s, not resumed",
3371 target_pid_to_str (lp
->ptid
).c_str ());
3373 else if (lwp_status_pending_p (lp
))
3375 linux_nat_debug_printf ("NOT resuming LWP %s, has pending status",
3376 target_pid_to_str (lp
->ptid
).c_str ());
3380 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3381 struct gdbarch
*gdbarch
= regcache
->arch ();
3385 CORE_ADDR pc
= regcache_read_pc (regcache
);
3386 int leave_stopped
= 0;
3388 /* Don't bother if there's a breakpoint at PC that we'd hit
3389 immediately, and we're not waiting for this LWP. */
3390 if (!lp
->ptid
.matches (wait_ptid
))
3392 if (breakpoint_inserted_here_p (regcache
->aspace (), pc
))
3398 linux_nat_debug_printf
3399 ("resuming stopped-resumed LWP %s at %s: step=%d",
3400 target_pid_to_str (lp
->ptid
).c_str (), paddress (gdbarch
, pc
),
3403 linux_resume_one_lwp_throw (lp
, lp
->step
, GDB_SIGNAL_0
);
3406 catch (const gdb_exception_error
&ex
)
3408 if (!check_ptrace_stopped_lwp_gone (lp
))
3417 linux_nat_target::wait (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3422 linux_nat_debug_printf ("[%s], [%s]", target_pid_to_str (ptid
).c_str (),
3423 target_options_to_string (target_options
).c_str ());
3425 /* Flush the async file first. */
3426 if (target_is_async_p ())
3427 async_file_flush ();
3429 /* Resume LWPs that are currently stopped without any pending status
3430 to report, but are resumed from the core's perspective. LWPs get
3431 in this state if we find them stopping at a time we're not
3432 interested in reporting the event (target_wait on a
3433 specific_process, for example, see linux_nat_wait_1), and
3434 meanwhile the event became uninteresting. Don't bother resuming
3435 LWPs we're not going to wait for if they'd stop immediately. */
3436 if (target_is_non_stop_p ())
3437 iterate_over_lwps (minus_one_ptid
,
3438 [=] (struct lwp_info
*info
)
3440 return resume_stopped_resumed_lwps (info
, ptid
);
3443 event_ptid
= linux_nat_wait_1 (ptid
, ourstatus
, target_options
);
3445 /* If we requested any event, and something came out, assume there
3446 may be more. If we requested a specific lwp or process, also
3447 assume there may be more. */
3448 if (target_is_async_p ()
3449 && ((ourstatus
->kind
!= TARGET_WAITKIND_IGNORE
3450 && ourstatus
->kind
!= TARGET_WAITKIND_NO_RESUMED
)
3451 || ptid
!= minus_one_ptid
))
3460 kill_one_lwp (pid_t pid
)
3462 /* PTRACE_KILL may resume the inferior. Send SIGKILL first. */
3465 kill_lwp (pid
, SIGKILL
);
3467 if (debug_linux_nat
)
3469 int save_errno
= errno
;
3471 linux_nat_debug_printf
3472 ("kill (SIGKILL) %ld, 0, 0 (%s)", (long) pid
,
3473 save_errno
!= 0 ? safe_strerror (save_errno
) : "OK");
3476 /* Some kernels ignore even SIGKILL for processes under ptrace. */
3479 ptrace (PTRACE_KILL
, pid
, 0, 0);
3480 if (debug_linux_nat
)
3482 int save_errno
= errno
;
3484 linux_nat_debug_printf
3485 ("PTRACE_KILL %ld, 0, 0 (%s)", (long) pid
,
3486 save_errno
? safe_strerror (save_errno
) : "OK");
3490 /* Wait for an LWP to die. */
3493 kill_wait_one_lwp (pid_t pid
)
3497 /* We must make sure that there are no pending events (delayed
3498 SIGSTOPs, pending SIGTRAPs, etc.) to make sure the current
3499 program doesn't interfere with any following debugging session. */
3503 res
= my_waitpid (pid
, NULL
, __WALL
);
3504 if (res
!= (pid_t
) -1)
3506 linux_nat_debug_printf ("wait %ld received unknown.", (long) pid
);
3508 /* The Linux kernel sometimes fails to kill a thread
3509 completely after PTRACE_KILL; that goes from the stop
3510 point in do_fork out to the one in get_signal_to_deliver
3511 and waits again. So kill it again. */
3517 gdb_assert (res
== -1 && errno
== ECHILD
);
3520 /* Callback for iterate_over_lwps. */
3523 kill_callback (struct lwp_info
*lp
)
3525 kill_one_lwp (lp
->ptid
.lwp ());
3529 /* Callback for iterate_over_lwps. */
3532 kill_wait_callback (struct lwp_info
*lp
)
3534 kill_wait_one_lwp (lp
->ptid
.lwp ());
3538 /* Kill the fork children of any threads of inferior INF that are
3539 stopped at a fork event. */
3542 kill_unfollowed_fork_children (struct inferior
*inf
)
3544 for (thread_info
*thread
: inf
->non_exited_threads ())
3546 struct target_waitstatus
*ws
= &thread
->pending_follow
;
3548 if (ws
->kind
== TARGET_WAITKIND_FORKED
3549 || ws
->kind
== TARGET_WAITKIND_VFORKED
)
3551 ptid_t child_ptid
= ws
->value
.related_pid
;
3552 int child_pid
= child_ptid
.pid ();
3553 int child_lwp
= child_ptid
.lwp ();
3555 kill_one_lwp (child_lwp
);
3556 kill_wait_one_lwp (child_lwp
);
3558 /* Let the arch-specific native code know this process is
3560 linux_target
->low_forget_process (child_pid
);
3566 linux_nat_target::kill ()
3568 /* If we're stopped while forking and we haven't followed yet,
3569 kill the other task. We need to do this first because the
3570 parent will be sleeping if this is a vfork. */
3571 kill_unfollowed_fork_children (current_inferior ());
3573 if (forks_exist_p ())
3574 linux_fork_killall ();
3577 ptid_t ptid
= ptid_t (inferior_ptid
.pid ());
3579 /* Stop all threads before killing them, since ptrace requires
3580 that the thread is stopped to successfully PTRACE_KILL. */
3581 iterate_over_lwps (ptid
, stop_callback
);
3582 /* ... and wait until all of them have reported back that
3583 they're no longer running. */
3584 iterate_over_lwps (ptid
, stop_wait_callback
);
3586 /* Kill all LWP's ... */
3587 iterate_over_lwps (ptid
, kill_callback
);
3589 /* ... and wait until we've flushed all events. */
3590 iterate_over_lwps (ptid
, kill_wait_callback
);
3593 target_mourn_inferior (inferior_ptid
);
3597 linux_nat_target::mourn_inferior ()
3599 int pid
= inferior_ptid
.pid ();
3601 purge_lwp_list (pid
);
3603 if (! forks_exist_p ())
3604 /* Normal case, no other forks available. */
3605 inf_ptrace_target::mourn_inferior ();
3607 /* Multi-fork case. The current inferior_ptid has exited, but
3608 there are other viable forks to debug. Delete the exiting
3609 one and context-switch to the first available. */
3610 linux_fork_mourn_inferior ();
3612 /* Let the arch-specific native code know this process is gone. */
3613 linux_target
->low_forget_process (pid
);
3616 /* Convert a native/host siginfo object, into/from the siginfo in the
3617 layout of the inferiors' architecture. */
3620 siginfo_fixup (siginfo_t
*siginfo
, gdb_byte
*inf_siginfo
, int direction
)
3622 /* If the low target didn't do anything, then just do a straight
3624 if (!linux_target
->low_siginfo_fixup (siginfo
, inf_siginfo
, direction
))
3627 memcpy (siginfo
, inf_siginfo
, sizeof (siginfo_t
));
3629 memcpy (inf_siginfo
, siginfo
, sizeof (siginfo_t
));
3633 static enum target_xfer_status
3634 linux_xfer_siginfo (enum target_object object
,
3635 const char *annex
, gdb_byte
*readbuf
,
3636 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3637 ULONGEST
*xfered_len
)
3641 gdb_byte inf_siginfo
[sizeof (siginfo_t
)];
3643 gdb_assert (object
== TARGET_OBJECT_SIGNAL_INFO
);
3644 gdb_assert (readbuf
|| writebuf
);
3646 pid
= inferior_ptid
.lwp ();
3648 pid
= inferior_ptid
.pid ();
3650 if (offset
> sizeof (siginfo
))
3651 return TARGET_XFER_E_IO
;
3654 ptrace (PTRACE_GETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, &siginfo
);
3656 return TARGET_XFER_E_IO
;
3658 /* When GDB is built as a 64-bit application, ptrace writes into
3659 SIGINFO an object with 64-bit layout. Since debugging a 32-bit
3660 inferior with a 64-bit GDB should look the same as debugging it
3661 with a 32-bit GDB, we need to convert it. GDB core always sees
3662 the converted layout, so any read/write will have to be done
3664 siginfo_fixup (&siginfo
, inf_siginfo
, 0);
3666 if (offset
+ len
> sizeof (siginfo
))
3667 len
= sizeof (siginfo
) - offset
;
3669 if (readbuf
!= NULL
)
3670 memcpy (readbuf
, inf_siginfo
+ offset
, len
);
3673 memcpy (inf_siginfo
+ offset
, writebuf
, len
);
3675 /* Convert back to ptrace layout before flushing it out. */
3676 siginfo_fixup (&siginfo
, inf_siginfo
, 1);
3679 ptrace (PTRACE_SETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, &siginfo
);
3681 return TARGET_XFER_E_IO
;
3685 return TARGET_XFER_OK
;
3688 static enum target_xfer_status
3689 linux_nat_xfer_osdata (enum target_object object
,
3690 const char *annex
, gdb_byte
*readbuf
,
3691 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3692 ULONGEST
*xfered_len
);
3694 static enum target_xfer_status
3695 linux_proc_xfer_partial (enum target_object object
,
3696 const char *annex
, gdb_byte
*readbuf
,
3697 const gdb_byte
*writebuf
,
3698 ULONGEST offset
, LONGEST len
, ULONGEST
*xfered_len
);
3700 enum target_xfer_status
3701 linux_nat_target::xfer_partial (enum target_object object
,
3702 const char *annex
, gdb_byte
*readbuf
,
3703 const gdb_byte
*writebuf
,
3704 ULONGEST offset
, ULONGEST len
, ULONGEST
*xfered_len
)
3706 enum target_xfer_status xfer
;
3708 if (object
== TARGET_OBJECT_SIGNAL_INFO
)
3709 return linux_xfer_siginfo (object
, annex
, readbuf
, writebuf
,
3710 offset
, len
, xfered_len
);
3712 /* The target is connected but no live inferior is selected. Pass
3713 this request down to a lower stratum (e.g., the executable
3715 if (object
== TARGET_OBJECT_MEMORY
&& inferior_ptid
== null_ptid
)
3716 return TARGET_XFER_EOF
;
3718 if (object
== TARGET_OBJECT_AUXV
)
3719 return memory_xfer_auxv (this, object
, annex
, readbuf
, writebuf
,
3720 offset
, len
, xfered_len
);
3722 if (object
== TARGET_OBJECT_OSDATA
)
3723 return linux_nat_xfer_osdata (object
, annex
, readbuf
, writebuf
,
3724 offset
, len
, xfered_len
);
3726 /* GDB calculates all addresses in the largest possible address
3728 The address width must be masked before its final use - either by
3729 linux_proc_xfer_partial or inf_ptrace_target::xfer_partial.
3731 Compare ADDR_BIT first to avoid a compiler warning on shift overflow. */
3733 if (object
== TARGET_OBJECT_MEMORY
)
3735 int addr_bit
= gdbarch_addr_bit (target_gdbarch ());
3737 if (addr_bit
< (sizeof (ULONGEST
) * HOST_CHAR_BIT
))
3738 offset
&= ((ULONGEST
) 1 << addr_bit
) - 1;
3741 xfer
= linux_proc_xfer_partial (object
, annex
, readbuf
, writebuf
,
3742 offset
, len
, xfered_len
);
3743 if (xfer
!= TARGET_XFER_EOF
)
3746 return inf_ptrace_target::xfer_partial (object
, annex
, readbuf
, writebuf
,
3747 offset
, len
, xfered_len
);
3751 linux_nat_target::thread_alive (ptid_t ptid
)
3753 /* As long as a PTID is in lwp list, consider it alive. */
3754 return find_lwp_pid (ptid
) != NULL
;
3757 /* Implement the to_update_thread_list target method for this
3761 linux_nat_target::update_thread_list ()
3763 struct lwp_info
*lwp
;
3765 /* We add/delete threads from the list as clone/exit events are
3766 processed, so just try deleting exited threads still in the
3768 delete_exited_threads ();
3770 /* Update the processor core that each lwp/thread was last seen
3774 /* Avoid accessing /proc if the thread hasn't run since we last
3775 time we fetched the thread's core. Accessing /proc becomes
3776 noticeably expensive when we have thousands of LWPs. */
3777 if (lwp
->core
== -1)
3778 lwp
->core
= linux_common_core_of_thread (lwp
->ptid
);
3783 linux_nat_target::pid_to_str (ptid_t ptid
)
3786 && (ptid
.pid () != ptid
.lwp ()
3787 || num_lwps (ptid
.pid ()) > 1))
3788 return string_printf ("LWP %ld", ptid
.lwp ());
3790 return normal_pid_to_str (ptid
);
3794 linux_nat_target::thread_name (struct thread_info
*thr
)
3796 return linux_proc_tid_get_name (thr
->ptid
);
3799 /* Accepts an integer PID; Returns a string representing a file that
3800 can be opened to get the symbols for the child process. */
3803 linux_nat_target::pid_to_exec_file (int pid
)
3805 return linux_proc_pid_to_exec_file (pid
);
3808 /* Implement the to_xfer_partial target method using /proc/<pid>/mem.
3809 Because we can use a single read/write call, this can be much more
3810 efficient than banging away at PTRACE_PEEKTEXT. */
3812 static enum target_xfer_status
3813 linux_proc_xfer_partial (enum target_object object
,
3814 const char *annex
, gdb_byte
*readbuf
,
3815 const gdb_byte
*writebuf
,
3816 ULONGEST offset
, LONGEST len
, ULONGEST
*xfered_len
)
3822 if (object
!= TARGET_OBJECT_MEMORY
)
3823 return TARGET_XFER_EOF
;
3825 /* Don't bother for one word. */
3826 if (len
< 3 * sizeof (long))
3827 return TARGET_XFER_EOF
;
3829 /* We could keep this file open and cache it - possibly one per
3830 thread. That requires some juggling, but is even faster. */
3831 xsnprintf (filename
, sizeof filename
, "/proc/%ld/mem",
3832 inferior_ptid
.lwp ());
3833 fd
= gdb_open_cloexec (filename
, ((readbuf
? O_RDONLY
: O_WRONLY
)
3836 return TARGET_XFER_EOF
;
3838 /* Use pread64/pwrite64 if available, since they save a syscall and can
3839 handle 64-bit offsets even on 32-bit platforms (for instance, SPARC
3840 debugging a SPARC64 application). */
3842 ret
= (readbuf
? pread64 (fd
, readbuf
, len
, offset
)
3843 : pwrite64 (fd
, writebuf
, len
, offset
));
3845 ret
= lseek (fd
, offset
, SEEK_SET
);
3847 ret
= (readbuf
? read (fd
, readbuf
, len
)
3848 : write (fd
, writebuf
, len
));
3853 if (ret
== -1 || ret
== 0)
3854 return TARGET_XFER_EOF
;
3858 return TARGET_XFER_OK
;
3863 /* Parse LINE as a signal set and add its set bits to SIGS. */
3866 add_line_to_sigset (const char *line
, sigset_t
*sigs
)
3868 int len
= strlen (line
) - 1;
3872 if (line
[len
] != '\n')
3873 error (_("Could not parse signal set: %s"), line
);
3881 if (*p
>= '0' && *p
<= '9')
3883 else if (*p
>= 'a' && *p
<= 'f')
3884 digit
= *p
- 'a' + 10;
3886 error (_("Could not parse signal set: %s"), line
);
3891 sigaddset (sigs
, signum
+ 1);
3893 sigaddset (sigs
, signum
+ 2);
3895 sigaddset (sigs
, signum
+ 3);
3897 sigaddset (sigs
, signum
+ 4);
3903 /* Find process PID's pending signals from /proc/pid/status and set
3907 linux_proc_pending_signals (int pid
, sigset_t
*pending
,
3908 sigset_t
*blocked
, sigset_t
*ignored
)
3910 char buffer
[PATH_MAX
], fname
[PATH_MAX
];
3912 sigemptyset (pending
);
3913 sigemptyset (blocked
);
3914 sigemptyset (ignored
);
3915 xsnprintf (fname
, sizeof fname
, "/proc/%d/status", pid
);
3916 gdb_file_up procfile
= gdb_fopen_cloexec (fname
, "r");
3917 if (procfile
== NULL
)
3918 error (_("Could not open %s"), fname
);
3920 while (fgets (buffer
, PATH_MAX
, procfile
.get ()) != NULL
)
3922 /* Normal queued signals are on the SigPnd line in the status
3923 file. However, 2.6 kernels also have a "shared" pending
3924 queue for delivering signals to a thread group, so check for
3927 Unfortunately some Red Hat kernels include the shared pending
3928 queue but not the ShdPnd status field. */
3930 if (startswith (buffer
, "SigPnd:\t"))
3931 add_line_to_sigset (buffer
+ 8, pending
);
3932 else if (startswith (buffer
, "ShdPnd:\t"))
3933 add_line_to_sigset (buffer
+ 8, pending
);
3934 else if (startswith (buffer
, "SigBlk:\t"))
3935 add_line_to_sigset (buffer
+ 8, blocked
);
3936 else if (startswith (buffer
, "SigIgn:\t"))
3937 add_line_to_sigset (buffer
+ 8, ignored
);
3941 static enum target_xfer_status
3942 linux_nat_xfer_osdata (enum target_object object
,
3943 const char *annex
, gdb_byte
*readbuf
,
3944 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3945 ULONGEST
*xfered_len
)
3947 gdb_assert (object
== TARGET_OBJECT_OSDATA
);
3949 *xfered_len
= linux_common_xfer_osdata (annex
, readbuf
, offset
, len
);
3950 if (*xfered_len
== 0)
3951 return TARGET_XFER_EOF
;
3953 return TARGET_XFER_OK
;
3956 std::vector
<static_tracepoint_marker
>
3957 linux_nat_target::static_tracepoint_markers_by_strid (const char *strid
)
3959 char s
[IPA_CMD_BUF_SIZE
];
3960 int pid
= inferior_ptid
.pid ();
3961 std::vector
<static_tracepoint_marker
> markers
;
3963 ptid_t ptid
= ptid_t (pid
, 0, 0);
3964 static_tracepoint_marker marker
;
3969 memcpy (s
, "qTfSTM", sizeof ("qTfSTM"));
3970 s
[sizeof ("qTfSTM")] = 0;
3972 agent_run_command (pid
, s
, strlen (s
) + 1);
3975 SCOPE_EXIT
{ target_continue_no_signal (ptid
); };
3981 parse_static_tracepoint_marker_definition (p
, &p
, &marker
);
3983 if (strid
== NULL
|| marker
.str_id
== strid
)
3984 markers
.push_back (std::move (marker
));
3986 while (*p
++ == ','); /* comma-separated list */
3988 memcpy (s
, "qTsSTM", sizeof ("qTsSTM"));
3989 s
[sizeof ("qTsSTM")] = 0;
3990 agent_run_command (pid
, s
, strlen (s
) + 1);
3997 /* target_is_async_p implementation. */
4000 linux_nat_target::is_async_p ()
4002 return linux_is_async_p ();
4005 /* target_can_async_p implementation. */
4008 linux_nat_target::can_async_p ()
4010 /* We're always async, unless the user explicitly prevented it with the
4011 "maint set target-async" command. */
4012 return target_async_permitted
;
4016 linux_nat_target::supports_non_stop ()
4021 /* to_always_non_stop_p implementation. */
4024 linux_nat_target::always_non_stop_p ()
4030 linux_nat_target::supports_multi_process ()
4036 linux_nat_target::supports_disable_randomization ()
4038 #ifdef HAVE_PERSONALITY
4045 /* SIGCHLD handler that serves two purposes: In non-stop/async mode,
4046 so we notice when any child changes state, and notify the
4047 event-loop; it allows us to use sigsuspend in linux_nat_wait_1
4048 above to wait for the arrival of a SIGCHLD. */
4051 sigchld_handler (int signo
)
4053 int old_errno
= errno
;
4055 if (debug_linux_nat
)
4056 gdb_stdlog
->write_async_safe ("sigchld\n", sizeof ("sigchld\n") - 1);
4058 if (signo
== SIGCHLD
4059 && linux_nat_event_pipe
[0] != -1)
4060 async_file_mark (); /* Let the event loop know that there are
4061 events to handle. */
4066 /* Callback registered with the target events file descriptor. */
4069 handle_target_event (int error
, gdb_client_data client_data
)
4071 inferior_event_handler (INF_REG_EVENT
);
4074 /* Create/destroy the target events pipe. Returns previous state. */
4077 linux_async_pipe (int enable
)
4079 int previous
= linux_is_async_p ();
4081 if (previous
!= enable
)
4085 /* Block child signals while we create/destroy the pipe, as
4086 their handler writes to it. */
4087 block_child_signals (&prev_mask
);
4091 if (gdb_pipe_cloexec (linux_nat_event_pipe
) == -1)
4092 internal_error (__FILE__
, __LINE__
,
4093 "creating event pipe failed.");
4095 fcntl (linux_nat_event_pipe
[0], F_SETFL
, O_NONBLOCK
);
4096 fcntl (linux_nat_event_pipe
[1], F_SETFL
, O_NONBLOCK
);
4100 close (linux_nat_event_pipe
[0]);
4101 close (linux_nat_event_pipe
[1]);
4102 linux_nat_event_pipe
[0] = -1;
4103 linux_nat_event_pipe
[1] = -1;
4106 restore_child_signals_mask (&prev_mask
);
4113 linux_nat_target::async_wait_fd ()
4115 return linux_nat_event_pipe
[0];
4118 /* target_async implementation. */
4121 linux_nat_target::async (int enable
)
4125 if (!linux_async_pipe (1))
4127 add_file_handler (linux_nat_event_pipe
[0],
4128 handle_target_event
, NULL
);
4129 /* There may be pending events to handle. Tell the event loop
4136 delete_file_handler (linux_nat_event_pipe
[0]);
4137 linux_async_pipe (0);
4142 /* Stop an LWP, and push a GDB_SIGNAL_0 stop status if no other
4146 linux_nat_stop_lwp (struct lwp_info
*lwp
)
4150 linux_nat_debug_printf ("running -> suspending %s",
4151 target_pid_to_str (lwp
->ptid
).c_str ());
4154 if (lwp
->last_resume_kind
== resume_stop
)
4156 linux_nat_debug_printf ("already stopping LWP %ld at GDB's request",
4161 stop_callback (lwp
);
4162 lwp
->last_resume_kind
= resume_stop
;
4166 /* Already known to be stopped; do nothing. */
4168 if (debug_linux_nat
)
4170 if (find_thread_ptid (linux_target
, lwp
->ptid
)->stop_requested
)
4171 linux_nat_debug_printf ("already stopped/stop_requested %s",
4172 target_pid_to_str (lwp
->ptid
).c_str ());
4174 linux_nat_debug_printf ("already stopped/no stop_requested yet %s",
4175 target_pid_to_str (lwp
->ptid
).c_str ());
4182 linux_nat_target::stop (ptid_t ptid
)
4184 iterate_over_lwps (ptid
, linux_nat_stop_lwp
);
4188 linux_nat_target::close ()
4190 /* Unregister from the event loop. */
4194 inf_ptrace_target::close ();
4197 /* When requests are passed down from the linux-nat layer to the
4198 single threaded inf-ptrace layer, ptids of (lwpid,0,0) form are
4199 used. The address space pointer is stored in the inferior object,
4200 but the common code that is passed such ptid can't tell whether
4201 lwpid is a "main" process id or not (it assumes so). We reverse
4202 look up the "main" process id from the lwp here. */
4204 struct address_space
*
4205 linux_nat_target::thread_address_space (ptid_t ptid
)
4207 struct lwp_info
*lwp
;
4208 struct inferior
*inf
;
4211 if (ptid
.lwp () == 0)
4213 /* An (lwpid,0,0) ptid. Look up the lwp object to get at the
4215 lwp
= find_lwp_pid (ptid
);
4216 pid
= lwp
->ptid
.pid ();
4220 /* A (pid,lwpid,0) ptid. */
4224 inf
= find_inferior_pid (this, pid
);
4225 gdb_assert (inf
!= NULL
);
4229 /* Return the cached value of the processor core for thread PTID. */
4232 linux_nat_target::core_of_thread (ptid_t ptid
)
4234 struct lwp_info
*info
= find_lwp_pid (ptid
);
4241 /* Implementation of to_filesystem_is_local. */
4244 linux_nat_target::filesystem_is_local ()
4246 struct inferior
*inf
= current_inferior ();
4248 if (inf
->fake_pid_p
|| inf
->pid
== 0)
4251 return linux_ns_same (inf
->pid
, LINUX_NS_MNT
);
4254 /* Convert the INF argument passed to a to_fileio_* method
4255 to a process ID suitable for passing to its corresponding
4256 linux_mntns_* function. If INF is non-NULL then the
4257 caller is requesting the filesystem seen by INF. If INF
4258 is NULL then the caller is requesting the filesystem seen
4259 by the GDB. We fall back to GDB's filesystem in the case
4260 that INF is non-NULL but its PID is unknown. */
4263 linux_nat_fileio_pid_of (struct inferior
*inf
)
4265 if (inf
== NULL
|| inf
->fake_pid_p
|| inf
->pid
== 0)
4271 /* Implementation of to_fileio_open. */
4274 linux_nat_target::fileio_open (struct inferior
*inf
, const char *filename
,
4275 int flags
, int mode
, int warn_if_slow
,
4282 if (fileio_to_host_openflags (flags
, &nat_flags
) == -1
4283 || fileio_to_host_mode (mode
, &nat_mode
) == -1)
4285 *target_errno
= FILEIO_EINVAL
;
4289 fd
= linux_mntns_open_cloexec (linux_nat_fileio_pid_of (inf
),
4290 filename
, nat_flags
, nat_mode
);
4292 *target_errno
= host_to_fileio_error (errno
);
4297 /* Implementation of to_fileio_readlink. */
4299 gdb::optional
<std::string
>
4300 linux_nat_target::fileio_readlink (struct inferior
*inf
, const char *filename
,
4306 len
= linux_mntns_readlink (linux_nat_fileio_pid_of (inf
),
4307 filename
, buf
, sizeof (buf
));
4310 *target_errno
= host_to_fileio_error (errno
);
4314 return std::string (buf
, len
);
4317 /* Implementation of to_fileio_unlink. */
4320 linux_nat_target::fileio_unlink (struct inferior
*inf
, const char *filename
,
4325 ret
= linux_mntns_unlink (linux_nat_fileio_pid_of (inf
),
4328 *target_errno
= host_to_fileio_error (errno
);
4333 /* Implementation of the to_thread_events method. */
4336 linux_nat_target::thread_events (int enable
)
4338 report_thread_events
= enable
;
4341 linux_nat_target::linux_nat_target ()
4343 /* We don't change the stratum; this target will sit at
4344 process_stratum and thread_db will set at thread_stratum. This
4345 is a little strange, since this is a multi-threaded-capable
4346 target, but we want to be on the stack below thread_db, and we
4347 also want to be used for single-threaded processes. */
4350 /* See linux-nat.h. */
4353 linux_nat_get_siginfo (ptid_t ptid
, siginfo_t
*siginfo
)
4362 ptrace (PTRACE_GETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, siginfo
);
4365 memset (siginfo
, 0, sizeof (*siginfo
));
4371 /* See nat/linux-nat.h. */
4374 current_lwp_ptid (void)
4376 gdb_assert (inferior_ptid
.lwp_p ());
4377 return inferior_ptid
;
4380 void _initialize_linux_nat ();
4382 _initialize_linux_nat ()
4384 add_setshow_zuinteger_cmd ("lin-lwp", class_maintenance
,
4385 &debug_linux_nat
, _("\
4386 Set debugging of GNU/Linux lwp module."), _("\
4387 Show debugging of GNU/Linux lwp module."), _("\
4388 Enables printf debugging output."),
4390 show_debug_linux_nat
,
4391 &setdebuglist
, &showdebuglist
);
4393 add_setshow_boolean_cmd ("linux-namespaces", class_maintenance
,
4394 &debug_linux_namespaces
, _("\
4395 Set debugging of GNU/Linux namespaces module."), _("\
4396 Show debugging of GNU/Linux namespaces module."), _("\
4397 Enables printf debugging output."),
4400 &setdebuglist
, &showdebuglist
);
4402 /* Install a SIGCHLD handler. */
4403 sigchld_action
.sa_handler
= sigchld_handler
;
4404 sigemptyset (&sigchld_action
.sa_mask
);
4405 sigchld_action
.sa_flags
= SA_RESTART
;
4407 /* Make it the default. */
4408 sigaction (SIGCHLD
, &sigchld_action
, NULL
);
4410 /* Make sure we don't block SIGCHLD during a sigsuspend. */
4411 gdb_sigmask (SIG_SETMASK
, NULL
, &suspend_mask
);
4412 sigdelset (&suspend_mask
, SIGCHLD
);
4414 sigemptyset (&blocked_mask
);
4416 lwp_lwpid_htab_create ();
4420 /* FIXME: kettenis/2000-08-26: The stuff on this page is specific to
4421 the GNU/Linux Threads library and therefore doesn't really belong
4424 /* Return the set of signals used by the threads library in *SET. */
4427 lin_thread_get_thread_signals (sigset_t
*set
)
4431 /* NPTL reserves the first two RT signals, but does not provide any
4432 way for the debugger to query the signal numbers - fortunately
4433 they don't change. */
4434 sigaddset (set
, __SIGRTMIN
);
4435 sigaddset (set
, __SIGRTMIN
+ 1);