1 /* GNU/Linux native-dependent code common to multiple platforms.
3 Copyright (C) 2001-2023 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>
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 "target-descriptions.h"
64 #include "gdbsupport/filestuff.h"
66 #include "nat/linux-namespaces.h"
67 #include "gdbsupport/block-signals.h"
68 #include "gdbsupport/fileio.h"
69 #include "gdbsupport/scope-exit.h"
70 #include "gdbsupport/gdb-sigmask.h"
71 #include "gdbsupport/common-debug.h"
72 #include <unordered_map>
74 /* This comment documents high-level logic of this file.
76 Waiting for events in sync mode
77 ===============================
79 When waiting for an event in a specific thread, we just use waitpid,
80 passing the specific pid, and not passing WNOHANG.
82 When waiting for an event in all threads, waitpid is not quite good:
84 - If the thread group leader exits while other threads in the thread
85 group still exist, waitpid(TGID, ...) hangs. That waitpid won't
86 return an exit status until the other threads in the group are
89 - When a non-leader thread execs, that thread just vanishes without
90 reporting an exit (so we'd hang if we waited for it explicitly in
91 that case). The exec event is instead reported to the TGID pid.
93 The solution is to always use -1 and WNOHANG, together with
96 First, we use non-blocking waitpid to check for events. If nothing is
97 found, we use sigsuspend to wait for SIGCHLD. When SIGCHLD arrives,
98 it means something happened to a child process. As soon as we know
99 there's an event, we get back to calling nonblocking waitpid.
101 Note that SIGCHLD should be blocked between waitpid and sigsuspend
102 calls, so that we don't miss a signal. If SIGCHLD arrives in between,
103 when it's blocked, the signal becomes pending and sigsuspend
104 immediately notices it and returns.
106 Waiting for events in async mode (TARGET_WNOHANG)
107 =================================================
109 In async mode, GDB should always be ready to handle both user input
110 and target events, so neither blocking waitpid nor sigsuspend are
111 viable options. Instead, we should asynchronously notify the GDB main
112 event loop whenever there's an unprocessed event from the target. We
113 detect asynchronous target events by handling SIGCHLD signals. To
114 notify the event loop about target events, an event pipe is used
115 --- the pipe is registered as waitable event source in the event loop,
116 the event loop select/poll's on the read end of this pipe (as well on
117 other event sources, e.g., stdin), and the SIGCHLD handler marks the
118 event pipe to raise an event. This is more portable than relying on
119 pselect/ppoll, since on kernels that lack those syscalls, libc
120 emulates them with select/poll+sigprocmask, and that is racy
121 (a.k.a. plain broken).
123 Obviously, if we fail to notify the event loop if there's a target
124 event, it's bad. OTOH, if we notify the event loop when there's no
125 event from the target, linux_nat_wait will detect that there's no real
126 event to report, and return event of type TARGET_WAITKIND_IGNORE.
127 This is mostly harmless, but it will waste time and is better avoided.
129 The main design point is that every time GDB is outside linux-nat.c,
130 we have a SIGCHLD handler installed that is called when something
131 happens to the target and notifies the GDB event loop. Whenever GDB
132 core decides to handle the event, and calls into linux-nat.c, we
133 process things as in sync mode, except that the we never block in
136 While processing an event, we may end up momentarily blocked in
137 waitpid calls. Those waitpid calls, while blocking, are guarantied to
138 return quickly. E.g., in all-stop mode, before reporting to the core
139 that an LWP hit a breakpoint, all LWPs are stopped by sending them
140 SIGSTOP, and synchronously waiting for the SIGSTOP to be reported.
141 Note that this is different from blocking indefinitely waiting for the
142 next event --- here, we're already handling an event.
147 We stop threads by sending a SIGSTOP. The use of SIGSTOP instead of another
148 signal is not entirely significant; we just need for a signal to be delivered,
149 so that we can intercept it. SIGSTOP's advantage is that it can not be
150 blocked. A disadvantage is that it is not a real-time signal, so it can only
151 be queued once; we do not keep track of other sources of SIGSTOP.
153 Two other signals that can't be blocked are SIGCONT and SIGKILL. But we can't
154 use them, because they have special behavior when the signal is generated -
155 not when it is delivered. SIGCONT resumes the entire thread group and SIGKILL
156 kills the entire thread group.
158 A delivered SIGSTOP would stop the entire thread group, not just the thread we
159 tkill'd. But we never let the SIGSTOP be delivered; we always intercept and
160 cancel it (by PTRACE_CONT without passing SIGSTOP).
162 We could use a real-time signal instead. This would solve those problems; we
163 could use PTRACE_GETSIGINFO to locate the specific stop signals sent by GDB.
164 But we would still have to have some support for SIGSTOP, since PTRACE_ATTACH
165 generates it, and there are races with trying to find a signal that is not
171 The case of a thread group (process) with 3 or more threads, and a
172 thread other than the leader execs is worth detailing:
174 On an exec, the Linux kernel destroys all threads except the execing
175 one in the thread group, and resets the execing thread's tid to the
176 tgid. No exit notification is sent for the execing thread -- from the
177 ptracer's perspective, it appears as though the execing thread just
178 vanishes. Until we reap all other threads except the leader and the
179 execing thread, the leader will be zombie, and the execing thread will
180 be in `D (disc sleep)' state. As soon as all other threads are
181 reaped, the execing thread changes its tid to the tgid, and the
182 previous (zombie) leader vanishes, giving place to the "new"
186 #define O_LARGEFILE 0
189 struct linux_nat_target
*linux_target
;
191 /* Does the current host support PTRACE_GETREGSET? */
192 enum tribool have_ptrace_getregset
= TRIBOOL_UNKNOWN
;
194 /* When true, print debug messages relating to the linux native target. */
196 static bool debug_linux_nat
;
198 /* Implement 'show debug linux-nat'. */
201 show_debug_linux_nat (struct ui_file
*file
, int from_tty
,
202 struct cmd_list_element
*c
, const char *value
)
204 gdb_printf (file
, _("Debugging of GNU/Linux native targets is %s.\n"),
208 /* Print a linux-nat debug statement. */
210 #define linux_nat_debug_printf(fmt, ...) \
211 debug_prefixed_printf_cond (debug_linux_nat, "linux-nat", fmt, ##__VA_ARGS__)
213 /* Print "linux-nat" enter/exit debug statements. */
215 #define LINUX_NAT_SCOPED_DEBUG_ENTER_EXIT \
216 scoped_debug_enter_exit (debug_linux_nat, "linux-nat")
218 struct simple_pid_list
222 struct simple_pid_list
*next
;
224 static struct simple_pid_list
*stopped_pids
;
226 /* Whether target_thread_events is in effect. */
227 static int report_thread_events
;
229 static int kill_lwp (int lwpid
, int signo
);
231 static int stop_callback (struct lwp_info
*lp
);
233 static void block_child_signals (sigset_t
*prev_mask
);
234 static void restore_child_signals_mask (sigset_t
*prev_mask
);
237 static struct lwp_info
*add_lwp (ptid_t ptid
);
238 static void purge_lwp_list (int pid
);
239 static void delete_lwp (ptid_t ptid
);
240 static struct lwp_info
*find_lwp_pid (ptid_t ptid
);
242 static int lwp_status_pending_p (struct lwp_info
*lp
);
244 static void save_stop_reason (struct lwp_info
*lp
);
246 static bool proc_mem_file_is_writable ();
247 static void close_proc_mem_file (pid_t pid
);
248 static void open_proc_mem_file (ptid_t ptid
);
250 /* Return TRUE if LWP is the leader thread of the process. */
253 is_leader (lwp_info
*lp
)
255 return lp
->ptid
.pid () == lp
->ptid
.lwp ();
258 /* Convert an LWP's pending status to a std::string. */
261 pending_status_str (lwp_info
*lp
)
263 gdb_assert (lwp_status_pending_p (lp
));
265 if (lp
->waitstatus
.kind () != TARGET_WAITKIND_IGNORE
)
266 return lp
->waitstatus
.to_string ();
268 return status_to_str (lp
->status
);
274 /* See nat/linux-nat.h. */
277 ptid_of_lwp (struct lwp_info
*lwp
)
282 /* See nat/linux-nat.h. */
285 lwp_set_arch_private_info (struct lwp_info
*lwp
,
286 struct arch_lwp_info
*info
)
288 lwp
->arch_private
= info
;
291 /* See nat/linux-nat.h. */
293 struct arch_lwp_info
*
294 lwp_arch_private_info (struct lwp_info
*lwp
)
296 return lwp
->arch_private
;
299 /* See nat/linux-nat.h. */
302 lwp_is_stopped (struct lwp_info
*lwp
)
307 /* See nat/linux-nat.h. */
309 enum target_stop_reason
310 lwp_stop_reason (struct lwp_info
*lwp
)
312 return lwp
->stop_reason
;
315 /* See nat/linux-nat.h. */
318 lwp_is_stepping (struct lwp_info
*lwp
)
324 /* Trivial list manipulation functions to keep track of a list of
325 new stopped processes. */
327 add_to_pid_list (struct simple_pid_list
**listp
, int pid
, int status
)
329 struct simple_pid_list
*new_pid
= XNEW (struct simple_pid_list
);
332 new_pid
->status
= status
;
333 new_pid
->next
= *listp
;
338 pull_pid_from_list (struct simple_pid_list
**listp
, int pid
, int *statusp
)
340 struct simple_pid_list
**p
;
342 for (p
= listp
; *p
!= NULL
; p
= &(*p
)->next
)
343 if ((*p
)->pid
== pid
)
345 struct simple_pid_list
*next
= (*p
)->next
;
347 *statusp
= (*p
)->status
;
355 /* Return the ptrace options that we want to try to enable. */
358 linux_nat_ptrace_options (int attached
)
363 options
|= PTRACE_O_EXITKILL
;
365 options
|= (PTRACE_O_TRACESYSGOOD
366 | PTRACE_O_TRACEVFORKDONE
367 | PTRACE_O_TRACEVFORK
369 | PTRACE_O_TRACEEXEC
);
374 /* Initialize ptrace and procfs warnings and check for supported
375 ptrace features given PID.
377 ATTACHED should be nonzero iff we attached to the inferior. */
380 linux_init_ptrace_procfs (pid_t pid
, int attached
)
382 int options
= linux_nat_ptrace_options (attached
);
384 linux_enable_event_reporting (pid
, options
);
385 linux_ptrace_init_warnings ();
386 linux_proc_init_warnings ();
387 proc_mem_file_is_writable ();
390 linux_nat_target::~linux_nat_target ()
394 linux_nat_target::post_attach (int pid
)
396 linux_init_ptrace_procfs (pid
, 1);
399 /* Implement the virtual inf_ptrace_target::post_startup_inferior method. */
402 linux_nat_target::post_startup_inferior (ptid_t ptid
)
404 linux_init_ptrace_procfs (ptid
.pid (), 0);
407 /* Return the number of known LWPs in the tgid given by PID. */
414 for (const lwp_info
*lp ATTRIBUTE_UNUSED
: all_lwps ())
415 if (lp
->ptid
.pid () == pid
)
421 /* Deleter for lwp_info unique_ptr specialisation. */
425 void operator() (struct lwp_info
*lwp
) const
427 delete_lwp (lwp
->ptid
);
431 /* A unique_ptr specialisation for lwp_info. */
433 typedef std::unique_ptr
<struct lwp_info
, lwp_deleter
> lwp_info_up
;
435 /* Target hook for follow_fork. */
438 linux_nat_target::follow_fork (inferior
*child_inf
, ptid_t child_ptid
,
439 target_waitkind fork_kind
, bool follow_child
,
442 inf_ptrace_target::follow_fork (child_inf
, child_ptid
, fork_kind
,
443 follow_child
, detach_fork
);
447 bool has_vforked
= fork_kind
== TARGET_WAITKIND_VFORKED
;
448 ptid_t parent_ptid
= inferior_ptid
;
449 int parent_pid
= parent_ptid
.lwp ();
450 int child_pid
= child_ptid
.lwp ();
452 /* We're already attached to the parent, by default. */
453 lwp_info
*child_lp
= add_lwp (child_ptid
);
454 child_lp
->stopped
= 1;
455 child_lp
->last_resume_kind
= resume_stop
;
457 /* Detach new forked process? */
460 int child_stop_signal
= 0;
461 bool detach_child
= true;
463 /* Move CHILD_LP into a unique_ptr and clear the source pointer
464 to prevent us doing anything stupid with it. */
465 lwp_info_up
child_lp_ptr (child_lp
);
468 linux_target
->low_prepare_to_resume (child_lp_ptr
.get ());
470 /* When debugging an inferior in an architecture that supports
471 hardware single stepping on a kernel without commit
472 6580807da14c423f0d0a708108e6df6ebc8bc83d, the vfork child
473 process starts with the TIF_SINGLESTEP/X86_EFLAGS_TF bits
474 set if the parent process had them set.
475 To work around this, single step the child process
476 once before detaching to clear the flags. */
478 /* Note that we consult the parent's architecture instead of
479 the child's because there's no inferior for the child at
481 if (!gdbarch_software_single_step_p (target_thread_architecture
486 linux_disable_event_reporting (child_pid
);
487 if (ptrace (PTRACE_SINGLESTEP
, child_pid
, 0, 0) < 0)
488 perror_with_name (_("Couldn't do single step"));
489 if (my_waitpid (child_pid
, &status
, 0) < 0)
490 perror_with_name (_("Couldn't wait vfork process"));
493 detach_child
= WIFSTOPPED (status
);
494 child_stop_signal
= WSTOPSIG (status
);
500 int signo
= child_stop_signal
;
503 && !signal_pass_state (gdb_signal_from_host (signo
)))
505 ptrace (PTRACE_DETACH
, child_pid
, 0, signo
);
507 close_proc_mem_file (child_pid
);
513 lwp_info
*parent_lp
= find_lwp_pid (parent_ptid
);
514 linux_nat_debug_printf ("waiting for VFORK_DONE on %d", parent_pid
);
515 parent_lp
->stopped
= 1;
517 /* We'll handle the VFORK_DONE event like any other
518 event, in target_wait. */
523 struct lwp_info
*child_lp
;
525 child_lp
= add_lwp (child_ptid
);
526 child_lp
->stopped
= 1;
527 child_lp
->last_resume_kind
= resume_stop
;
533 linux_nat_target::insert_fork_catchpoint (int pid
)
539 linux_nat_target::remove_fork_catchpoint (int pid
)
545 linux_nat_target::insert_vfork_catchpoint (int pid
)
551 linux_nat_target::remove_vfork_catchpoint (int pid
)
557 linux_nat_target::insert_exec_catchpoint (int pid
)
563 linux_nat_target::remove_exec_catchpoint (int pid
)
569 linux_nat_target::set_syscall_catchpoint (int pid
, bool needed
, int any_count
,
570 gdb::array_view
<const int> syscall_counts
)
572 /* On GNU/Linux, we ignore the arguments. It means that we only
573 enable the syscall catchpoints, but do not disable them.
575 Also, we do not use the `syscall_counts' information because we do not
576 filter system calls here. We let GDB do the logic for us. */
580 /* List of known LWPs, keyed by LWP PID. This speeds up the common
581 case of mapping a PID returned from the kernel to our corresponding
582 lwp_info data structure. */
583 static htab_t lwp_lwpid_htab
;
585 /* Calculate a hash from a lwp_info's LWP PID. */
588 lwp_info_hash (const void *ap
)
590 const struct lwp_info
*lp
= (struct lwp_info
*) ap
;
591 pid_t pid
= lp
->ptid
.lwp ();
593 return iterative_hash_object (pid
, 0);
596 /* Equality function for the lwp_info hash table. Compares the LWP's
600 lwp_lwpid_htab_eq (const void *a
, const void *b
)
602 const struct lwp_info
*entry
= (const struct lwp_info
*) a
;
603 const struct lwp_info
*element
= (const struct lwp_info
*) b
;
605 return entry
->ptid
.lwp () == element
->ptid
.lwp ();
608 /* Create the lwp_lwpid_htab hash table. */
611 lwp_lwpid_htab_create (void)
613 lwp_lwpid_htab
= htab_create (100, lwp_info_hash
, lwp_lwpid_htab_eq
, NULL
);
616 /* Add LP to the hash table. */
619 lwp_lwpid_htab_add_lwp (struct lwp_info
*lp
)
623 slot
= htab_find_slot (lwp_lwpid_htab
, lp
, INSERT
);
624 gdb_assert (slot
!= NULL
&& *slot
== NULL
);
628 /* Head of doubly-linked list of known LWPs. Sorted by reverse
629 creation order. This order is assumed in some cases. E.g.,
630 reaping status after killing alls lwps of a process: the leader LWP
631 must be reaped last. */
633 static intrusive_list
<lwp_info
> lwp_list
;
635 /* See linux-nat.h. */
640 return lwp_info_range (lwp_list
.begin ());
643 /* See linux-nat.h. */
648 return lwp_info_safe_range (lwp_list
.begin ());
651 /* Add LP to sorted-by-reverse-creation-order doubly-linked list. */
654 lwp_list_add (struct lwp_info
*lp
)
656 lwp_list
.push_front (*lp
);
659 /* Remove LP from sorted-by-reverse-creation-order doubly-linked
663 lwp_list_remove (struct lwp_info
*lp
)
665 /* Remove from sorted-by-creation-order list. */
666 lwp_list
.erase (lwp_list
.iterator_to (*lp
));
671 /* Signal mask for use with sigsuspend in linux_nat_wait, initialized in
672 _initialize_linux_nat. */
673 static sigset_t suspend_mask
;
675 /* Signals to block to make that sigsuspend work. */
676 static sigset_t blocked_mask
;
678 /* SIGCHLD action. */
679 static struct sigaction sigchld_action
;
681 /* Block child signals (SIGCHLD and linux threads signals), and store
682 the previous mask in PREV_MASK. */
685 block_child_signals (sigset_t
*prev_mask
)
687 /* Make sure SIGCHLD is blocked. */
688 if (!sigismember (&blocked_mask
, SIGCHLD
))
689 sigaddset (&blocked_mask
, SIGCHLD
);
691 gdb_sigmask (SIG_BLOCK
, &blocked_mask
, prev_mask
);
694 /* Restore child signals mask, previously returned by
695 block_child_signals. */
698 restore_child_signals_mask (sigset_t
*prev_mask
)
700 gdb_sigmask (SIG_SETMASK
, prev_mask
, NULL
);
703 /* Mask of signals to pass directly to the inferior. */
704 static sigset_t pass_mask
;
706 /* Update signals to pass to the inferior. */
708 linux_nat_target::pass_signals
709 (gdb::array_view
<const unsigned char> pass_signals
)
713 sigemptyset (&pass_mask
);
715 for (signo
= 1; signo
< NSIG
; signo
++)
717 int target_signo
= gdb_signal_from_host (signo
);
718 if (target_signo
< pass_signals
.size () && pass_signals
[target_signo
])
719 sigaddset (&pass_mask
, signo
);
725 /* Prototypes for local functions. */
726 static int stop_wait_callback (struct lwp_info
*lp
);
727 static int resume_stopped_resumed_lwps (struct lwp_info
*lp
, const ptid_t wait_ptid
);
728 static int check_ptrace_stopped_lwp_gone (struct lwp_info
*lp
);
732 /* Destroy and free LP. */
734 lwp_info::~lwp_info ()
736 /* Let the arch specific bits release arch_lwp_info. */
737 linux_target
->low_delete_thread (this->arch_private
);
740 /* Traversal function for purge_lwp_list. */
743 lwp_lwpid_htab_remove_pid (void **slot
, void *info
)
745 struct lwp_info
*lp
= (struct lwp_info
*) *slot
;
746 int pid
= *(int *) info
;
748 if (lp
->ptid
.pid () == pid
)
750 htab_clear_slot (lwp_lwpid_htab
, slot
);
751 lwp_list_remove (lp
);
758 /* Remove all LWPs belong to PID from the lwp list. */
761 purge_lwp_list (int pid
)
763 htab_traverse_noresize (lwp_lwpid_htab
, lwp_lwpid_htab_remove_pid
, &pid
);
766 /* Add the LWP specified by PTID to the list. PTID is the first LWP
767 in the process. Return a pointer to the structure describing the
770 This differs from add_lwp in that we don't let the arch specific
771 bits know about this new thread. Current clients of this callback
772 take the opportunity to install watchpoints in the new thread, and
773 we shouldn't do that for the first thread. If we're spawning a
774 child ("run"), the thread executes the shell wrapper first, and we
775 shouldn't touch it until it execs the program we want to debug.
776 For "attach", it'd be okay to call the callback, but it's not
777 necessary, because watchpoints can't yet have been inserted into
780 static struct lwp_info
*
781 add_initial_lwp (ptid_t ptid
)
783 gdb_assert (ptid
.lwp_p ());
785 lwp_info
*lp
= new lwp_info (ptid
);
788 /* Add to sorted-by-reverse-creation-order list. */
791 /* Add to keyed-by-pid htab. */
792 lwp_lwpid_htab_add_lwp (lp
);
797 /* Add the LWP specified by PID to the list. Return a pointer to the
798 structure describing the new LWP. The LWP should already be
801 static struct lwp_info
*
802 add_lwp (ptid_t ptid
)
806 lp
= add_initial_lwp (ptid
);
808 /* Let the arch specific bits know about this new thread. Current
809 clients of this callback take the opportunity to install
810 watchpoints in the new thread. We don't do this for the first
811 thread though. See add_initial_lwp. */
812 linux_target
->low_new_thread (lp
);
817 /* Remove the LWP specified by PID from the list. */
820 delete_lwp (ptid_t ptid
)
822 lwp_info
dummy (ptid
);
824 void **slot
= htab_find_slot (lwp_lwpid_htab
, &dummy
, NO_INSERT
);
828 lwp_info
*lp
= *(struct lwp_info
**) slot
;
829 gdb_assert (lp
!= NULL
);
831 htab_clear_slot (lwp_lwpid_htab
, slot
);
833 /* Remove from sorted-by-creation-order list. */
834 lwp_list_remove (lp
);
840 /* Return a pointer to the structure describing the LWP corresponding
841 to PID. If no corresponding LWP could be found, return NULL. */
843 static struct lwp_info
*
844 find_lwp_pid (ptid_t ptid
)
853 lwp_info
dummy (ptid_t (0, lwp
));
854 return (struct lwp_info
*) htab_find (lwp_lwpid_htab
, &dummy
);
857 /* See nat/linux-nat.h. */
860 iterate_over_lwps (ptid_t filter
,
861 gdb::function_view
<iterate_over_lwps_ftype
> callback
)
863 for (lwp_info
*lp
: all_lwps_safe ())
865 if (lp
->ptid
.matches (filter
))
867 if (callback (lp
) != 0)
875 /* Update our internal state when changing from one checkpoint to
876 another indicated by NEW_PTID. We can only switch single-threaded
877 applications, so we only create one new LWP, and the previous list
881 linux_nat_switch_fork (ptid_t new_ptid
)
885 purge_lwp_list (inferior_ptid
.pid ());
887 lp
= add_lwp (new_ptid
);
890 /* This changes the thread's ptid while preserving the gdb thread
891 num. Also changes the inferior pid, while preserving the
893 thread_change_ptid (linux_target
, inferior_ptid
, new_ptid
);
895 /* We've just told GDB core that the thread changed target id, but,
896 in fact, it really is a different thread, with different register
898 registers_changed ();
901 /* Handle the exit of a single thread LP. */
904 exit_lwp (struct lwp_info
*lp
)
906 struct thread_info
*th
= linux_target
->find_thread (lp
->ptid
);
911 delete_lwp (lp
->ptid
);
914 /* Wait for the LWP specified by LP, which we have just attached to.
915 Returns a wait status for that LWP, to cache. */
918 linux_nat_post_attach_wait (ptid_t ptid
, int *signalled
)
920 pid_t new_pid
, pid
= ptid
.lwp ();
923 if (linux_proc_pid_is_stopped (pid
))
925 linux_nat_debug_printf ("Attaching to a stopped process");
927 /* The process is definitely stopped. It is in a job control
928 stop, unless the kernel predates the TASK_STOPPED /
929 TASK_TRACED distinction, in which case it might be in a
930 ptrace stop. Make sure it is in a ptrace stop; from there we
931 can kill it, signal it, et cetera.
933 First make sure there is a pending SIGSTOP. Since we are
934 already attached, the process can not transition from stopped
935 to running without a PTRACE_CONT; so we know this signal will
936 go into the queue. The SIGSTOP generated by PTRACE_ATTACH is
937 probably already in the queue (unless this kernel is old
938 enough to use TASK_STOPPED for ptrace stops); but since SIGSTOP
939 is not an RT signal, it can only be queued once. */
940 kill_lwp (pid
, SIGSTOP
);
942 /* Finally, resume the stopped process. This will deliver the SIGSTOP
943 (or a higher priority signal, just like normal PTRACE_ATTACH). */
944 ptrace (PTRACE_CONT
, pid
, 0, 0);
947 /* Make sure the initial process is stopped. The user-level threads
948 layer might want to poke around in the inferior, and that won't
949 work if things haven't stabilized yet. */
950 new_pid
= my_waitpid (pid
, &status
, __WALL
);
951 gdb_assert (pid
== new_pid
);
953 if (!WIFSTOPPED (status
))
955 /* The pid we tried to attach has apparently just exited. */
956 linux_nat_debug_printf ("Failed to stop %d: %s", pid
,
957 status_to_str (status
).c_str ());
961 if (WSTOPSIG (status
) != SIGSTOP
)
964 linux_nat_debug_printf ("Received %s after attaching",
965 status_to_str (status
).c_str ());
972 linux_nat_target::create_inferior (const char *exec_file
,
973 const std::string
&allargs
,
974 char **env
, int from_tty
)
976 maybe_disable_address_space_randomization restore_personality
977 (disable_randomization
);
979 /* The fork_child mechanism is synchronous and calls target_wait, so
980 we have to mask the async mode. */
982 /* Make sure we report all signals during startup. */
985 inf_ptrace_target::create_inferior (exec_file
, allargs
, env
, from_tty
);
987 open_proc_mem_file (inferior_ptid
);
990 /* Callback for linux_proc_attach_tgid_threads. Attach to PTID if not
991 already attached. Returns true if a new LWP is found, false
995 attach_proc_task_lwp_callback (ptid_t ptid
)
999 /* Ignore LWPs we're already attached to. */
1000 lp
= find_lwp_pid (ptid
);
1003 int lwpid
= ptid
.lwp ();
1005 if (ptrace (PTRACE_ATTACH
, lwpid
, 0, 0) < 0)
1009 /* Be quiet if we simply raced with the thread exiting.
1010 EPERM is returned if the thread's task still exists, and
1011 is marked as exited or zombie, as well as other
1012 conditions, so in that case, confirm the status in
1013 /proc/PID/status. */
1015 || (err
== EPERM
&& linux_proc_pid_is_gone (lwpid
)))
1017 linux_nat_debug_printf
1018 ("Cannot attach to lwp %d: thread is gone (%d: %s)",
1019 lwpid
, err
, safe_strerror (err
));
1025 = linux_ptrace_attach_fail_reason_string (ptid
, err
);
1027 warning (_("Cannot attach to lwp %d: %s"),
1028 lwpid
, reason
.c_str ());
1033 linux_nat_debug_printf ("PTRACE_ATTACH %s, 0, 0 (OK)",
1034 ptid
.to_string ().c_str ());
1036 lp
= add_lwp (ptid
);
1038 /* The next time we wait for this LWP we'll see a SIGSTOP as
1039 PTRACE_ATTACH brings it to a halt. */
1042 /* We need to wait for a stop before being able to make the
1043 next ptrace call on this LWP. */
1044 lp
->must_set_ptrace_flags
= 1;
1046 /* So that wait collects the SIGSTOP. */
1049 /* Also add the LWP to gdb's thread list, in case a
1050 matching libthread_db is not found (or the process uses
1052 add_thread (linux_target
, lp
->ptid
);
1053 set_running (linux_target
, lp
->ptid
, true);
1054 set_executing (linux_target
, lp
->ptid
, true);
1063 linux_nat_target::attach (const char *args
, int from_tty
)
1065 struct lwp_info
*lp
;
1069 /* Make sure we report all signals during attach. */
1074 inf_ptrace_target::attach (args
, from_tty
);
1076 catch (const gdb_exception_error
&ex
)
1078 pid_t pid
= parse_pid_to_attach (args
);
1079 std::string reason
= linux_ptrace_attach_fail_reason (pid
);
1081 if (!reason
.empty ())
1082 throw_error (ex
.error
, "warning: %s\n%s", reason
.c_str (),
1085 throw_error (ex
.error
, "%s", ex
.what ());
1088 /* The ptrace base target adds the main thread with (pid,0,0)
1089 format. Decorate it with lwp info. */
1090 ptid
= ptid_t (inferior_ptid
.pid (),
1091 inferior_ptid
.pid ());
1092 thread_change_ptid (linux_target
, inferior_ptid
, ptid
);
1094 /* Add the initial process as the first LWP to the list. */
1095 lp
= add_initial_lwp (ptid
);
1097 status
= linux_nat_post_attach_wait (lp
->ptid
, &lp
->signalled
);
1098 if (!WIFSTOPPED (status
))
1100 if (WIFEXITED (status
))
1102 int exit_code
= WEXITSTATUS (status
);
1104 target_terminal::ours ();
1105 target_mourn_inferior (inferior_ptid
);
1107 error (_("Unable to attach: program exited normally."));
1109 error (_("Unable to attach: program exited with code %d."),
1112 else if (WIFSIGNALED (status
))
1114 enum gdb_signal signo
;
1116 target_terminal::ours ();
1117 target_mourn_inferior (inferior_ptid
);
1119 signo
= gdb_signal_from_host (WTERMSIG (status
));
1120 error (_("Unable to attach: program terminated with signal "
1122 gdb_signal_to_name (signo
),
1123 gdb_signal_to_string (signo
));
1126 internal_error (_("unexpected status %d for PID %ld"),
1127 status
, (long) ptid
.lwp ());
1132 open_proc_mem_file (lp
->ptid
);
1134 /* Save the wait status to report later. */
1136 linux_nat_debug_printf ("waitpid %ld, saving status %s",
1137 (long) lp
->ptid
.pid (),
1138 status_to_str (status
).c_str ());
1140 lp
->status
= status
;
1142 /* We must attach to every LWP. If /proc is mounted, use that to
1143 find them now. The inferior may be using raw clone instead of
1144 using pthreads. But even if it is using pthreads, thread_db
1145 walks structures in the inferior's address space to find the list
1146 of threads/LWPs, and those structures may well be corrupted.
1147 Note that once thread_db is loaded, we'll still use it to list
1148 threads and associate pthread info with each LWP. */
1149 linux_proc_attach_tgid_threads (lp
->ptid
.pid (),
1150 attach_proc_task_lwp_callback
);
1153 /* Ptrace-detach the thread with pid PID. */
1156 detach_one_pid (int pid
, int signo
)
1158 if (ptrace (PTRACE_DETACH
, pid
, 0, signo
) < 0)
1160 int save_errno
= errno
;
1162 /* We know the thread exists, so ESRCH must mean the lwp is
1163 zombie. This can happen if one of the already-detached
1164 threads exits the whole thread group. In that case we're
1165 still attached, and must reap the lwp. */
1166 if (save_errno
== ESRCH
)
1170 ret
= my_waitpid (pid
, &status
, __WALL
);
1173 warning (_("Couldn't reap LWP %d while detaching: %s"),
1174 pid
, safe_strerror (errno
));
1176 else if (!WIFEXITED (status
) && !WIFSIGNALED (status
))
1178 warning (_("Reaping LWP %d while detaching "
1179 "returned unexpected status 0x%x"),
1184 error (_("Can't detach %d: %s"),
1185 pid
, safe_strerror (save_errno
));
1188 linux_nat_debug_printf ("PTRACE_DETACH (%d, %s, 0) (OK)",
1189 pid
, strsignal (signo
));
1192 /* Get pending signal of THREAD as a host signal number, for detaching
1193 purposes. This is the signal the thread last stopped for, which we
1194 need to deliver to the thread when detaching, otherwise, it'd be
1198 get_detach_signal (struct lwp_info
*lp
)
1200 enum gdb_signal signo
= GDB_SIGNAL_0
;
1202 /* If we paused threads momentarily, we may have stored pending
1203 events in lp->status or lp->waitstatus (see stop_wait_callback),
1204 and GDB core hasn't seen any signal for those threads.
1205 Otherwise, the last signal reported to the core is found in the
1206 thread object's stop_signal.
1208 There's a corner case that isn't handled here at present. Only
1209 if the thread stopped with a TARGET_WAITKIND_STOPPED does
1210 stop_signal make sense as a real signal to pass to the inferior.
1211 Some catchpoint related events, like
1212 TARGET_WAITKIND_(V)FORK|EXEC|SYSCALL, have their stop_signal set
1213 to GDB_SIGNAL_SIGTRAP when the catchpoint triggers. But,
1214 those traps are debug API (ptrace in our case) related and
1215 induced; the inferior wouldn't see them if it wasn't being
1216 traced. Hence, we should never pass them to the inferior, even
1217 when set to pass state. Since this corner case isn't handled by
1218 infrun.c when proceeding with a signal, for consistency, neither
1219 do we handle it here (or elsewhere in the file we check for
1220 signal pass state). Normally SIGTRAP isn't set to pass state, so
1221 this is really a corner case. */
1223 if (lp
->waitstatus
.kind () != TARGET_WAITKIND_IGNORE
)
1224 signo
= GDB_SIGNAL_0
; /* a pending ptrace event, not a real signal. */
1225 else if (lp
->status
)
1226 signo
= gdb_signal_from_host (WSTOPSIG (lp
->status
));
1229 thread_info
*tp
= linux_target
->find_thread (lp
->ptid
);
1231 if (target_is_non_stop_p () && !tp
->executing ())
1233 if (tp
->has_pending_waitstatus ())
1235 /* If the thread has a pending event, and it was stopped with a
1236 signal, use that signal to resume it. If it has a pending
1237 event of another kind, it was not stopped with a signal, so
1238 resume it without a signal. */
1239 if (tp
->pending_waitstatus ().kind () == TARGET_WAITKIND_STOPPED
)
1240 signo
= tp
->pending_waitstatus ().sig ();
1242 signo
= GDB_SIGNAL_0
;
1245 signo
= tp
->stop_signal ();
1247 else if (!target_is_non_stop_p ())
1250 process_stratum_target
*last_target
;
1252 get_last_target_status (&last_target
, &last_ptid
, nullptr);
1254 if (last_target
== linux_target
1255 && lp
->ptid
.lwp () == last_ptid
.lwp ())
1256 signo
= tp
->stop_signal ();
1260 if (signo
== GDB_SIGNAL_0
)
1262 linux_nat_debug_printf ("lwp %s has no pending signal",
1263 lp
->ptid
.to_string ().c_str ());
1265 else if (!signal_pass_state (signo
))
1267 linux_nat_debug_printf
1268 ("lwp %s had signal %s but it is in no pass state",
1269 lp
->ptid
.to_string ().c_str (), gdb_signal_to_string (signo
));
1273 linux_nat_debug_printf ("lwp %s has pending signal %s",
1274 lp
->ptid
.to_string ().c_str (),
1275 gdb_signal_to_string (signo
));
1277 return gdb_signal_to_host (signo
);
1283 /* Detach from LP. If SIGNO_P is non-NULL, then it points to the
1284 signal number that should be passed to the LWP when detaching.
1285 Otherwise pass any pending signal the LWP may have, if any. */
1288 detach_one_lwp (struct lwp_info
*lp
, int *signo_p
)
1290 LINUX_NAT_SCOPED_DEBUG_ENTER_EXIT
;
1292 linux_nat_debug_printf ("lwp %s (stopped = %d)",
1293 lp
->ptid
.to_string ().c_str (), lp
->stopped
);
1295 int lwpid
= lp
->ptid
.lwp ();
1298 gdb_assert (lp
->status
== 0 || WIFSTOPPED (lp
->status
));
1300 /* If the lwp/thread we are about to detach has a pending fork event,
1301 there is a process GDB is attached to that the core of GDB doesn't know
1302 about. Detach from it. */
1304 /* Check in lwp_info::status. */
1305 if (WIFSTOPPED (lp
->status
) && linux_is_extended_waitstatus (lp
->status
))
1307 int event
= linux_ptrace_get_extended_event (lp
->status
);
1309 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
)
1311 unsigned long child_pid
;
1312 int ret
= ptrace (PTRACE_GETEVENTMSG
, lp
->ptid
.lwp (), 0, &child_pid
);
1314 detach_one_pid (child_pid
, 0);
1316 perror_warning_with_name (_("Failed to detach fork child"));
1320 /* Check in lwp_info::waitstatus. */
1321 if (lp
->waitstatus
.kind () == TARGET_WAITKIND_VFORKED
1322 || lp
->waitstatus
.kind () == TARGET_WAITKIND_FORKED
)
1323 detach_one_pid (lp
->waitstatus
.child_ptid ().pid (), 0);
1326 /* Check in thread_info::pending_waitstatus. */
1327 thread_info
*tp
= linux_target
->find_thread (lp
->ptid
);
1328 if (tp
->has_pending_waitstatus ())
1330 const target_waitstatus
&ws
= tp
->pending_waitstatus ();
1332 if (ws
.kind () == TARGET_WAITKIND_VFORKED
1333 || ws
.kind () == TARGET_WAITKIND_FORKED
)
1334 detach_one_pid (ws
.child_ptid ().pid (), 0);
1337 /* Check in thread_info::pending_follow. */
1338 if (tp
->pending_follow
.kind () == TARGET_WAITKIND_VFORKED
1339 || tp
->pending_follow
.kind () == TARGET_WAITKIND_FORKED
)
1340 detach_one_pid (tp
->pending_follow
.child_ptid ().pid (), 0);
1342 if (lp
->status
!= 0)
1343 linux_nat_debug_printf ("Pending %s for %s on detach.",
1344 strsignal (WSTOPSIG (lp
->status
)),
1345 lp
->ptid
.to_string ().c_str ());
1347 /* If there is a pending SIGSTOP, get rid of it. */
1350 linux_nat_debug_printf ("Sending SIGCONT to %s",
1351 lp
->ptid
.to_string ().c_str ());
1353 kill_lwp (lwpid
, SIGCONT
);
1357 if (signo_p
== NULL
)
1359 /* Pass on any pending signal for this LWP. */
1360 signo
= get_detach_signal (lp
);
1365 linux_nat_debug_printf ("preparing to resume lwp %s (stopped = %d)",
1366 lp
->ptid
.to_string ().c_str (),
1369 /* Preparing to resume may try to write registers, and fail if the
1370 lwp is zombie. If that happens, ignore the error. We'll handle
1371 it below, when detach fails with ESRCH. */
1374 linux_target
->low_prepare_to_resume (lp
);
1376 catch (const gdb_exception_error
&ex
)
1378 if (!check_ptrace_stopped_lwp_gone (lp
))
1382 detach_one_pid (lwpid
, signo
);
1384 delete_lwp (lp
->ptid
);
1388 detach_callback (struct lwp_info
*lp
)
1390 /* We don't actually detach from the thread group leader just yet.
1391 If the thread group exits, we must reap the zombie clone lwps
1392 before we're able to reap the leader. */
1393 if (lp
->ptid
.lwp () != lp
->ptid
.pid ())
1394 detach_one_lwp (lp
, NULL
);
1399 linux_nat_target::detach (inferior
*inf
, int from_tty
)
1401 LINUX_NAT_SCOPED_DEBUG_ENTER_EXIT
;
1403 struct lwp_info
*main_lwp
;
1406 /* Don't unregister from the event loop, as there may be other
1407 inferiors running. */
1409 /* Stop all threads before detaching. ptrace requires that the
1410 thread is stopped to successfully detach. */
1411 iterate_over_lwps (ptid_t (pid
), stop_callback
);
1412 /* ... and wait until all of them have reported back that
1413 they're no longer running. */
1414 iterate_over_lwps (ptid_t (pid
), stop_wait_callback
);
1416 /* We can now safely remove breakpoints. We don't this in earlier
1417 in common code because this target doesn't currently support
1418 writing memory while the inferior is running. */
1419 remove_breakpoints_inf (current_inferior ());
1421 iterate_over_lwps (ptid_t (pid
), detach_callback
);
1423 /* We have detached from everything except the main thread now, so
1424 should only have one thread left. However, in non-stop mode the
1425 main thread might have exited, in which case we'll have no threads
1427 gdb_assert (num_lwps (pid
) == 1
1428 || (target_is_non_stop_p () && num_lwps (pid
) == 0));
1430 if (forks_exist_p ())
1432 /* Multi-fork case. The current inferior_ptid is being detached
1433 from, but there are other viable forks to debug. Detach from
1434 the current fork, and context-switch to the first
1436 linux_fork_detach (from_tty
);
1440 target_announce_detach (from_tty
);
1442 /* In non-stop mode it is possible that the main thread has exited,
1443 in which case we don't try to detach. */
1444 main_lwp
= find_lwp_pid (ptid_t (pid
));
1445 if (main_lwp
!= nullptr)
1447 /* Pass on any pending signal for the last LWP. */
1448 int signo
= get_detach_signal (main_lwp
);
1450 detach_one_lwp (main_lwp
, &signo
);
1453 gdb_assert (target_is_non_stop_p ());
1455 detach_success (inf
);
1458 close_proc_mem_file (pid
);
1461 /* Resume execution of the inferior process. If STEP is nonzero,
1462 single-step it. If SIGNAL is nonzero, give it that signal. */
1465 linux_resume_one_lwp_throw (struct lwp_info
*lp
, int step
,
1466 enum gdb_signal signo
)
1470 /* stop_pc doubles as the PC the LWP had when it was last resumed.
1471 We only presently need that if the LWP is stepped though (to
1472 handle the case of stepping a breakpoint instruction). */
1475 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
1477 lp
->stop_pc
= regcache_read_pc (regcache
);
1482 linux_target
->low_prepare_to_resume (lp
);
1483 linux_target
->low_resume (lp
->ptid
, step
, signo
);
1485 /* Successfully resumed. Clear state that no longer makes sense,
1486 and mark the LWP as running. Must not do this before resuming
1487 otherwise if that fails other code will be confused. E.g., we'd
1488 later try to stop the LWP and hang forever waiting for a stop
1489 status. Note that we must not throw after this is cleared,
1490 otherwise handle_zombie_lwp_error would get confused. */
1493 lp
->stop_reason
= TARGET_STOPPED_BY_NO_REASON
;
1494 registers_changed_ptid (linux_target
, lp
->ptid
);
1497 /* Called when we try to resume a stopped LWP and that errors out. If
1498 the LWP is no longer in ptrace-stopped state (meaning it's zombie,
1499 or about to become), discard the error, clear any pending status
1500 the LWP may have, and return true (we'll collect the exit status
1501 soon enough). Otherwise, return false. */
1504 check_ptrace_stopped_lwp_gone (struct lwp_info
*lp
)
1506 /* If we get an error after resuming the LWP successfully, we'd
1507 confuse !T state for the LWP being gone. */
1508 gdb_assert (lp
->stopped
);
1510 /* We can't just check whether the LWP is in 'Z (Zombie)' state,
1511 because even if ptrace failed with ESRCH, the tracee may be "not
1512 yet fully dead", but already refusing ptrace requests. In that
1513 case the tracee has 'R (Running)' state for a little bit
1514 (observed in Linux 3.18). See also the note on ESRCH in the
1515 ptrace(2) man page. Instead, check whether the LWP has any state
1516 other than ptrace-stopped. */
1518 /* Don't assume anything if /proc/PID/status can't be read. */
1519 if (linux_proc_pid_is_trace_stopped_nowarn (lp
->ptid
.lwp ()) == 0)
1521 lp
->stop_reason
= TARGET_STOPPED_BY_NO_REASON
;
1523 lp
->waitstatus
.set_ignore ();
1529 /* Like linux_resume_one_lwp_throw, but no error is thrown if the LWP
1530 disappears while we try to resume it. */
1533 linux_resume_one_lwp (struct lwp_info
*lp
, int step
, enum gdb_signal signo
)
1537 linux_resume_one_lwp_throw (lp
, step
, signo
);
1539 catch (const gdb_exception_error
&ex
)
1541 if (!check_ptrace_stopped_lwp_gone (lp
))
1549 resume_lwp (struct lwp_info
*lp
, int step
, enum gdb_signal signo
)
1553 struct inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
1555 if (inf
->vfork_child
!= NULL
)
1557 linux_nat_debug_printf ("Not resuming sibling %s (vfork parent)",
1558 lp
->ptid
.to_string ().c_str ());
1560 else if (!lwp_status_pending_p (lp
))
1562 linux_nat_debug_printf ("Resuming sibling %s, %s, %s",
1563 lp
->ptid
.to_string ().c_str (),
1564 (signo
!= GDB_SIGNAL_0
1565 ? strsignal (gdb_signal_to_host (signo
))
1567 step
? "step" : "resume");
1569 linux_resume_one_lwp (lp
, step
, signo
);
1573 linux_nat_debug_printf ("Not resuming sibling %s (has pending)",
1574 lp
->ptid
.to_string ().c_str ());
1578 linux_nat_debug_printf ("Not resuming sibling %s (not stopped)",
1579 lp
->ptid
.to_string ().c_str ());
1582 /* Callback for iterate_over_lwps. If LWP is EXCEPT, do nothing.
1583 Resume LWP with the last stop signal, if it is in pass state. */
1586 linux_nat_resume_callback (struct lwp_info
*lp
, struct lwp_info
*except
)
1588 enum gdb_signal signo
= GDB_SIGNAL_0
;
1595 struct thread_info
*thread
;
1597 thread
= linux_target
->find_thread (lp
->ptid
);
1600 signo
= thread
->stop_signal ();
1601 thread
->set_stop_signal (GDB_SIGNAL_0
);
1605 resume_lwp (lp
, 0, signo
);
1610 resume_clear_callback (struct lwp_info
*lp
)
1613 lp
->last_resume_kind
= resume_stop
;
1618 resume_set_callback (struct lwp_info
*lp
)
1621 lp
->last_resume_kind
= resume_continue
;
1626 linux_nat_target::resume (ptid_t scope_ptid
, int step
, enum gdb_signal signo
)
1628 struct lwp_info
*lp
;
1630 linux_nat_debug_printf ("Preparing to %s %s, %s, inferior_ptid %s",
1631 step
? "step" : "resume",
1632 scope_ptid
.to_string ().c_str (),
1633 (signo
!= GDB_SIGNAL_0
1634 ? strsignal (gdb_signal_to_host (signo
)) : "0"),
1635 inferior_ptid
.to_string ().c_str ());
1637 /* Mark the lwps we're resuming as resumed and update their
1638 last_resume_kind to resume_continue. */
1639 iterate_over_lwps (scope_ptid
, resume_set_callback
);
1641 lp
= find_lwp_pid (inferior_ptid
);
1642 gdb_assert (lp
!= NULL
);
1644 /* Remember if we're stepping. */
1645 lp
->last_resume_kind
= step
? resume_step
: resume_continue
;
1647 /* If we have a pending wait status for this thread, there is no
1648 point in resuming the process. But first make sure that
1649 linux_nat_wait won't preemptively handle the event - we
1650 should never take this short-circuit if we are going to
1651 leave LP running, since we have skipped resuming all the
1652 other threads. This bit of code needs to be synchronized
1653 with linux_nat_wait. */
1655 if (lp
->status
&& WIFSTOPPED (lp
->status
))
1658 && WSTOPSIG (lp
->status
)
1659 && sigismember (&pass_mask
, WSTOPSIG (lp
->status
)))
1661 linux_nat_debug_printf
1662 ("Not short circuiting for ignored status 0x%x", lp
->status
);
1664 /* FIXME: What should we do if we are supposed to continue
1665 this thread with a signal? */
1666 gdb_assert (signo
== GDB_SIGNAL_0
);
1667 signo
= gdb_signal_from_host (WSTOPSIG (lp
->status
));
1672 if (lwp_status_pending_p (lp
))
1674 /* FIXME: What should we do if we are supposed to continue
1675 this thread with a signal? */
1676 gdb_assert (signo
== GDB_SIGNAL_0
);
1678 linux_nat_debug_printf ("Short circuiting for status %s",
1679 pending_status_str (lp
).c_str ());
1681 if (target_can_async_p ())
1683 target_async (true);
1684 /* Tell the event loop we have something to process. */
1690 /* No use iterating unless we're resuming other threads. */
1691 if (scope_ptid
!= lp
->ptid
)
1692 iterate_over_lwps (scope_ptid
, [=] (struct lwp_info
*info
)
1694 return linux_nat_resume_callback (info
, lp
);
1697 linux_nat_debug_printf ("%s %s, %s (resume event thread)",
1698 step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
1699 lp
->ptid
.to_string ().c_str (),
1700 (signo
!= GDB_SIGNAL_0
1701 ? strsignal (gdb_signal_to_host (signo
)) : "0"));
1703 linux_resume_one_lwp (lp
, step
, signo
);
1706 /* Send a signal to an LWP. */
1709 kill_lwp (int lwpid
, int signo
)
1714 ret
= syscall (__NR_tkill
, lwpid
, signo
);
1715 if (errno
== ENOSYS
)
1717 /* If tkill fails, then we are not using nptl threads, a
1718 configuration we no longer support. */
1719 perror_with_name (("tkill"));
1724 /* Handle a GNU/Linux syscall trap wait response. If we see a syscall
1725 event, check if the core is interested in it: if not, ignore the
1726 event, and keep waiting; otherwise, we need to toggle the LWP's
1727 syscall entry/exit status, since the ptrace event itself doesn't
1728 indicate it, and report the trap to higher layers. */
1731 linux_handle_syscall_trap (struct lwp_info
*lp
, int stopping
)
1733 struct target_waitstatus
*ourstatus
= &lp
->waitstatus
;
1734 struct gdbarch
*gdbarch
= target_thread_architecture (lp
->ptid
);
1735 thread_info
*thread
= linux_target
->find_thread (lp
->ptid
);
1736 int syscall_number
= (int) gdbarch_get_syscall_number (gdbarch
, thread
);
1740 /* If we're stopping threads, there's a SIGSTOP pending, which
1741 makes it so that the LWP reports an immediate syscall return,
1742 followed by the SIGSTOP. Skip seeing that "return" using
1743 PTRACE_CONT directly, and let stop_wait_callback collect the
1744 SIGSTOP. Later when the thread is resumed, a new syscall
1745 entry event. If we didn't do this (and returned 0), we'd
1746 leave a syscall entry pending, and our caller, by using
1747 PTRACE_CONT to collect the SIGSTOP, skips the syscall return
1748 itself. Later, when the user re-resumes this LWP, we'd see
1749 another syscall entry event and we'd mistake it for a return.
1751 If stop_wait_callback didn't force the SIGSTOP out of the LWP
1752 (leaving immediately with LWP->signalled set, without issuing
1753 a PTRACE_CONT), it would still be problematic to leave this
1754 syscall enter pending, as later when the thread is resumed,
1755 it would then see the same syscall exit mentioned above,
1756 followed by the delayed SIGSTOP, while the syscall didn't
1757 actually get to execute. It seems it would be even more
1758 confusing to the user. */
1760 linux_nat_debug_printf
1761 ("ignoring syscall %d for LWP %ld (stopping threads), resuming with "
1762 "PTRACE_CONT for SIGSTOP", syscall_number
, lp
->ptid
.lwp ());
1764 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
1765 ptrace (PTRACE_CONT
, lp
->ptid
.lwp (), 0, 0);
1770 /* Always update the entry/return state, even if this particular
1771 syscall isn't interesting to the core now. In async mode,
1772 the user could install a new catchpoint for this syscall
1773 between syscall enter/return, and we'll need to know to
1774 report a syscall return if that happens. */
1775 lp
->syscall_state
= (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1776 ? TARGET_WAITKIND_SYSCALL_RETURN
1777 : TARGET_WAITKIND_SYSCALL_ENTRY
);
1779 if (catch_syscall_enabled ())
1781 if (catching_syscall_number (syscall_number
))
1783 /* Alright, an event to report. */
1784 if (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
)
1785 ourstatus
->set_syscall_entry (syscall_number
);
1786 else if (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_RETURN
)
1787 ourstatus
->set_syscall_return (syscall_number
);
1789 gdb_assert_not_reached ("unexpected syscall state");
1791 linux_nat_debug_printf
1792 ("stopping for %s of syscall %d for LWP %ld",
1793 (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1794 ? "entry" : "return"), syscall_number
, lp
->ptid
.lwp ());
1799 linux_nat_debug_printf
1800 ("ignoring %s of syscall %d for LWP %ld",
1801 (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1802 ? "entry" : "return"), syscall_number
, lp
->ptid
.lwp ());
1806 /* If we had been syscall tracing, and hence used PT_SYSCALL
1807 before on this LWP, it could happen that the user removes all
1808 syscall catchpoints before we get to process this event.
1809 There are two noteworthy issues here:
1811 - When stopped at a syscall entry event, resuming with
1812 PT_STEP still resumes executing the syscall and reports a
1815 - Only PT_SYSCALL catches syscall enters. If we last
1816 single-stepped this thread, then this event can't be a
1817 syscall enter. If we last single-stepped this thread, this
1818 has to be a syscall exit.
1820 The points above mean that the next resume, be it PT_STEP or
1821 PT_CONTINUE, can not trigger a syscall trace event. */
1822 linux_nat_debug_printf
1823 ("caught syscall event with no syscall catchpoints. %d for LWP %ld, "
1824 "ignoring", syscall_number
, lp
->ptid
.lwp ());
1825 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
1828 /* The core isn't interested in this event. For efficiency, avoid
1829 stopping all threads only to have the core resume them all again.
1830 Since we're not stopping threads, if we're still syscall tracing
1831 and not stepping, we can't use PTRACE_CONT here, as we'd miss any
1832 subsequent syscall. Simply resume using the inf-ptrace layer,
1833 which knows when to use PT_SYSCALL or PT_CONTINUE. */
1835 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
1839 /* Handle a GNU/Linux extended wait response. If we see a clone
1840 event, we need to add the new LWP to our list (and not report the
1841 trap to higher layers). This function returns non-zero if the
1842 event should be ignored and we should wait again. If STOPPING is
1843 true, the new LWP remains stopped, otherwise it is continued. */
1846 linux_handle_extended_wait (struct lwp_info
*lp
, int status
)
1848 int pid
= lp
->ptid
.lwp ();
1849 struct target_waitstatus
*ourstatus
= &lp
->waitstatus
;
1850 int event
= linux_ptrace_get_extended_event (status
);
1852 /* All extended events we currently use are mid-syscall. Only
1853 PTRACE_EVENT_STOP is delivered more like a signal-stop, but
1854 you have to be using PTRACE_SEIZE to get that. */
1855 lp
->syscall_state
= TARGET_WAITKIND_SYSCALL_ENTRY
;
1857 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
1858 || event
== PTRACE_EVENT_CLONE
)
1860 unsigned long new_pid
;
1863 ptrace (PTRACE_GETEVENTMSG
, pid
, 0, &new_pid
);
1865 /* If we haven't already seen the new PID stop, wait for it now. */
1866 if (! pull_pid_from_list (&stopped_pids
, new_pid
, &status
))
1868 /* The new child has a pending SIGSTOP. We can't affect it until it
1869 hits the SIGSTOP, but we're already attached. */
1870 ret
= my_waitpid (new_pid
, &status
, __WALL
);
1872 perror_with_name (_("waiting for new child"));
1873 else if (ret
!= new_pid
)
1874 internal_error (_("wait returned unexpected PID %d"), ret
);
1875 else if (!WIFSTOPPED (status
))
1876 internal_error (_("wait returned unexpected status 0x%x"), status
);
1879 ptid_t
child_ptid (new_pid
, new_pid
);
1881 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
)
1883 open_proc_mem_file (child_ptid
);
1885 /* The arch-specific native code may need to know about new
1886 forks even if those end up never mapped to an
1888 linux_target
->low_new_fork (lp
, new_pid
);
1890 else if (event
== PTRACE_EVENT_CLONE
)
1892 linux_target
->low_new_clone (lp
, new_pid
);
1895 if (event
== PTRACE_EVENT_FORK
1896 && linux_fork_checkpointing_p (lp
->ptid
.pid ()))
1898 /* Handle checkpointing by linux-fork.c here as a special
1899 case. We don't want the follow-fork-mode or 'catch fork'
1900 to interfere with this. */
1902 /* This won't actually modify the breakpoint list, but will
1903 physically remove the breakpoints from the child. */
1904 detach_breakpoints (ptid_t (new_pid
, new_pid
));
1906 /* Retain child fork in ptrace (stopped) state. */
1907 if (!find_fork_pid (new_pid
))
1910 /* Report as spurious, so that infrun doesn't want to follow
1911 this fork. We're actually doing an infcall in
1913 ourstatus
->set_spurious ();
1915 /* Report the stop to the core. */
1919 if (event
== PTRACE_EVENT_FORK
)
1920 ourstatus
->set_forked (child_ptid
);
1921 else if (event
== PTRACE_EVENT_VFORK
)
1922 ourstatus
->set_vforked (child_ptid
);
1923 else if (event
== PTRACE_EVENT_CLONE
)
1925 struct lwp_info
*new_lp
;
1927 ourstatus
->set_ignore ();
1929 linux_nat_debug_printf
1930 ("Got clone event from LWP %d, new child is LWP %ld", pid
, new_pid
);
1932 new_lp
= add_lwp (ptid_t (lp
->ptid
.pid (), new_pid
));
1933 new_lp
->stopped
= 1;
1934 new_lp
->resumed
= 1;
1936 /* If the thread_db layer is active, let it record the user
1937 level thread id and status, and add the thread to GDB's
1939 if (!thread_db_notice_clone (lp
->ptid
, new_lp
->ptid
))
1941 /* The process is not using thread_db. Add the LWP to
1943 add_thread (linux_target
, new_lp
->ptid
);
1946 /* Even if we're stopping the thread for some reason
1947 internal to this module, from the perspective of infrun
1948 and the user/frontend, this new thread is running until
1949 it next reports a stop. */
1950 set_running (linux_target
, new_lp
->ptid
, true);
1951 set_executing (linux_target
, new_lp
->ptid
, true);
1953 if (WSTOPSIG (status
) != SIGSTOP
)
1955 /* This can happen if someone starts sending signals to
1956 the new thread before it gets a chance to run, which
1957 have a lower number than SIGSTOP (e.g. SIGUSR1).
1958 This is an unlikely case, and harder to handle for
1959 fork / vfork than for clone, so we do not try - but
1960 we handle it for clone events here. */
1962 new_lp
->signalled
= 1;
1964 /* We created NEW_LP so it cannot yet contain STATUS. */
1965 gdb_assert (new_lp
->status
== 0);
1967 /* Save the wait status to report later. */
1968 linux_nat_debug_printf
1969 ("waitpid of new LWP %ld, saving status %s",
1970 (long) new_lp
->ptid
.lwp (), status_to_str (status
).c_str ());
1971 new_lp
->status
= status
;
1973 else if (report_thread_events
)
1975 new_lp
->waitstatus
.set_thread_created ();
1976 new_lp
->status
= status
;
1985 if (event
== PTRACE_EVENT_EXEC
)
1987 linux_nat_debug_printf ("Got exec event from LWP %ld", lp
->ptid
.lwp ());
1989 /* Close the previous /proc/PID/mem file for this inferior,
1990 which was using the address space which is now gone.
1991 Reading/writing from this file would return 0/EOF. */
1992 close_proc_mem_file (lp
->ptid
.pid ());
1994 /* Open a new file for the new address space. */
1995 open_proc_mem_file (lp
->ptid
);
1997 ourstatus
->set_execd
1998 (make_unique_xstrdup (linux_proc_pid_to_exec_file (pid
)));
2000 /* The thread that execed must have been resumed, but, when a
2001 thread execs, it changes its tid to the tgid, and the old
2002 tgid thread might have not been resumed. */
2007 if (event
== PTRACE_EVENT_VFORK_DONE
)
2009 linux_nat_debug_printf
2010 ("Got PTRACE_EVENT_VFORK_DONE from LWP %ld",
2012 ourstatus
->set_vfork_done ();
2016 internal_error (_("unknown ptrace event %d"), event
);
2019 /* Suspend waiting for a signal. We're mostly interested in
2025 linux_nat_debug_printf ("about to sigsuspend");
2026 sigsuspend (&suspend_mask
);
2028 /* If the quit flag is set, it means that the user pressed Ctrl-C
2029 and we're debugging a process that is running on a separate
2030 terminal, so we must forward the Ctrl-C to the inferior. (If the
2031 inferior is sharing GDB's terminal, then the Ctrl-C reaches the
2032 inferior directly.) We must do this here because functions that
2033 need to block waiting for a signal loop forever until there's an
2034 event to report before returning back to the event loop. */
2035 if (!target_terminal::is_ours ())
2037 if (check_quit_flag ())
2038 target_pass_ctrlc ();
2042 /* Wait for LP to stop. Returns the wait status, or 0 if the LWP has
2046 wait_lwp (struct lwp_info
*lp
)
2050 int thread_dead
= 0;
2053 gdb_assert (!lp
->stopped
);
2054 gdb_assert (lp
->status
== 0);
2056 /* Make sure SIGCHLD is blocked for sigsuspend avoiding a race below. */
2057 block_child_signals (&prev_mask
);
2061 pid
= my_waitpid (lp
->ptid
.lwp (), &status
, __WALL
| WNOHANG
);
2062 if (pid
== -1 && errno
== ECHILD
)
2064 /* The thread has previously exited. We need to delete it
2065 now because if this was a non-leader thread execing, we
2066 won't get an exit event. See comments on exec events at
2067 the top of the file. */
2069 linux_nat_debug_printf ("%s vanished.",
2070 lp
->ptid
.to_string ().c_str ());
2075 /* Bugs 10970, 12702.
2076 Thread group leader may have exited in which case we'll lock up in
2077 waitpid if there are other threads, even if they are all zombies too.
2078 Basically, we're not supposed to use waitpid this way.
2079 tkill(pid,0) cannot be used here as it gets ESRCH for both
2080 for zombie and running processes.
2082 As a workaround, check if we're waiting for the thread group leader and
2083 if it's a zombie, and avoid calling waitpid if it is.
2085 This is racy, what if the tgl becomes a zombie right after we check?
2086 Therefore always use WNOHANG with sigsuspend - it is equivalent to
2087 waiting waitpid but linux_proc_pid_is_zombie is safe this way. */
2089 if (lp
->ptid
.pid () == lp
->ptid
.lwp ()
2090 && linux_proc_pid_is_zombie (lp
->ptid
.lwp ()))
2093 linux_nat_debug_printf ("Thread group leader %s vanished.",
2094 lp
->ptid
.to_string ().c_str ());
2098 /* Wait for next SIGCHLD and try again. This may let SIGCHLD handlers
2099 get invoked despite our caller had them intentionally blocked by
2100 block_child_signals. This is sensitive only to the loop of
2101 linux_nat_wait_1 and there if we get called my_waitpid gets called
2102 again before it gets to sigsuspend so we can safely let the handlers
2103 get executed here. */
2107 restore_child_signals_mask (&prev_mask
);
2111 gdb_assert (pid
== lp
->ptid
.lwp ());
2113 linux_nat_debug_printf ("waitpid %s received %s",
2114 lp
->ptid
.to_string ().c_str (),
2115 status_to_str (status
).c_str ());
2117 /* Check if the thread has exited. */
2118 if (WIFEXITED (status
) || WIFSIGNALED (status
))
2120 if (report_thread_events
2121 || lp
->ptid
.pid () == lp
->ptid
.lwp ())
2123 linux_nat_debug_printf ("LWP %d exited.", lp
->ptid
.pid ());
2125 /* If this is the leader exiting, it means the whole
2126 process is gone. Store the status to report to the
2127 core. Store it in lp->waitstatus, because lp->status
2128 would be ambiguous (W_EXITCODE(0,0) == 0). */
2129 lp
->waitstatus
= host_status_to_waitstatus (status
);
2134 linux_nat_debug_printf ("%s exited.",
2135 lp
->ptid
.to_string ().c_str ());
2145 gdb_assert (WIFSTOPPED (status
));
2148 if (lp
->must_set_ptrace_flags
)
2150 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2151 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
2153 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
2154 lp
->must_set_ptrace_flags
= 0;
2157 /* Handle GNU/Linux's syscall SIGTRAPs. */
2158 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
2160 /* No longer need the sysgood bit. The ptrace event ends up
2161 recorded in lp->waitstatus if we care for it. We can carry
2162 on handling the event like a regular SIGTRAP from here
2164 status
= W_STOPCODE (SIGTRAP
);
2165 if (linux_handle_syscall_trap (lp
, 1))
2166 return wait_lwp (lp
);
2170 /* Almost all other ptrace-stops are known to be outside of system
2171 calls, with further exceptions in linux_handle_extended_wait. */
2172 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
2175 /* Handle GNU/Linux's extended waitstatus for trace events. */
2176 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
2177 && linux_is_extended_waitstatus (status
))
2179 linux_nat_debug_printf ("Handling extended status 0x%06x", status
);
2180 linux_handle_extended_wait (lp
, status
);
2187 /* Send a SIGSTOP to LP. */
2190 stop_callback (struct lwp_info
*lp
)
2192 if (!lp
->stopped
&& !lp
->signalled
)
2196 linux_nat_debug_printf ("kill %s **<SIGSTOP>**",
2197 lp
->ptid
.to_string ().c_str ());
2200 ret
= kill_lwp (lp
->ptid
.lwp (), SIGSTOP
);
2201 linux_nat_debug_printf ("lwp kill %d %s", ret
,
2202 errno
? safe_strerror (errno
) : "ERRNO-OK");
2205 gdb_assert (lp
->status
== 0);
2211 /* Request a stop on LWP. */
2214 linux_stop_lwp (struct lwp_info
*lwp
)
2216 stop_callback (lwp
);
2219 /* See linux-nat.h */
2222 linux_stop_and_wait_all_lwps (void)
2224 /* Stop all LWP's ... */
2225 iterate_over_lwps (minus_one_ptid
, stop_callback
);
2227 /* ... and wait until all of them have reported back that
2228 they're no longer running. */
2229 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
2232 /* See linux-nat.h */
2235 linux_unstop_all_lwps (void)
2237 iterate_over_lwps (minus_one_ptid
,
2238 [] (struct lwp_info
*info
)
2240 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
2244 /* Return non-zero if LWP PID has a pending SIGINT. */
2247 linux_nat_has_pending_sigint (int pid
)
2249 sigset_t pending
, blocked
, ignored
;
2251 linux_proc_pending_signals (pid
, &pending
, &blocked
, &ignored
);
2253 if (sigismember (&pending
, SIGINT
)
2254 && !sigismember (&ignored
, SIGINT
))
2260 /* Set a flag in LP indicating that we should ignore its next SIGINT. */
2263 set_ignore_sigint (struct lwp_info
*lp
)
2265 /* If a thread has a pending SIGINT, consume it; otherwise, set a
2266 flag to consume the next one. */
2267 if (lp
->stopped
&& lp
->status
!= 0 && WIFSTOPPED (lp
->status
)
2268 && WSTOPSIG (lp
->status
) == SIGINT
)
2271 lp
->ignore_sigint
= 1;
2276 /* If LP does not have a SIGINT pending, then clear the ignore_sigint flag.
2277 This function is called after we know the LWP has stopped; if the LWP
2278 stopped before the expected SIGINT was delivered, then it will never have
2279 arrived. Also, if the signal was delivered to a shared queue and consumed
2280 by a different thread, it will never be delivered to this LWP. */
2283 maybe_clear_ignore_sigint (struct lwp_info
*lp
)
2285 if (!lp
->ignore_sigint
)
2288 if (!linux_nat_has_pending_sigint (lp
->ptid
.lwp ()))
2290 linux_nat_debug_printf ("Clearing bogus flag for %s",
2291 lp
->ptid
.to_string ().c_str ());
2292 lp
->ignore_sigint
= 0;
2296 /* Fetch the possible triggered data watchpoint info and store it in
2299 On some archs, like x86, that use debug registers to set
2300 watchpoints, it's possible that the way to know which watched
2301 address trapped, is to check the register that is used to select
2302 which address to watch. Problem is, between setting the watchpoint
2303 and reading back which data address trapped, the user may change
2304 the set of watchpoints, and, as a consequence, GDB changes the
2305 debug registers in the inferior. To avoid reading back a stale
2306 stopped-data-address when that happens, we cache in LP the fact
2307 that a watchpoint trapped, and the corresponding data address, as
2308 soon as we see LP stop with a SIGTRAP. If GDB changes the debug
2309 registers meanwhile, we have the cached data we can rely on. */
2312 check_stopped_by_watchpoint (struct lwp_info
*lp
)
2314 scoped_restore save_inferior_ptid
= make_scoped_restore (&inferior_ptid
);
2315 inferior_ptid
= lp
->ptid
;
2317 if (linux_target
->low_stopped_by_watchpoint ())
2319 lp
->stop_reason
= TARGET_STOPPED_BY_WATCHPOINT
;
2320 lp
->stopped_data_address_p
2321 = linux_target
->low_stopped_data_address (&lp
->stopped_data_address
);
2324 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2327 /* Returns true if the LWP had stopped for a watchpoint. */
2330 linux_nat_target::stopped_by_watchpoint ()
2332 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2334 gdb_assert (lp
!= NULL
);
2336 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2340 linux_nat_target::stopped_data_address (CORE_ADDR
*addr_p
)
2342 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2344 gdb_assert (lp
!= NULL
);
2346 *addr_p
= lp
->stopped_data_address
;
2348 return lp
->stopped_data_address_p
;
2351 /* Commonly any breakpoint / watchpoint generate only SIGTRAP. */
2354 linux_nat_target::low_status_is_event (int status
)
2356 return WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
;
2359 /* Wait until LP is stopped. */
2362 stop_wait_callback (struct lwp_info
*lp
)
2364 inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
2366 /* If this is a vfork parent, bail out, it is not going to report
2367 any SIGSTOP until the vfork is done with. */
2368 if (inf
->vfork_child
!= NULL
)
2375 status
= wait_lwp (lp
);
2379 if (lp
->ignore_sigint
&& WIFSTOPPED (status
)
2380 && WSTOPSIG (status
) == SIGINT
)
2382 lp
->ignore_sigint
= 0;
2385 ptrace (PTRACE_CONT
, lp
->ptid
.lwp (), 0, 0);
2387 linux_nat_debug_printf
2388 ("PTRACE_CONT %s, 0, 0 (%s) (discarding SIGINT)",
2389 lp
->ptid
.to_string ().c_str (),
2390 errno
? safe_strerror (errno
) : "OK");
2392 return stop_wait_callback (lp
);
2395 maybe_clear_ignore_sigint (lp
);
2397 if (WSTOPSIG (status
) != SIGSTOP
)
2399 /* The thread was stopped with a signal other than SIGSTOP. */
2401 linux_nat_debug_printf ("Pending event %s in %s",
2402 status_to_str ((int) status
).c_str (),
2403 lp
->ptid
.to_string ().c_str ());
2405 /* Save the sigtrap event. */
2406 lp
->status
= status
;
2407 gdb_assert (lp
->signalled
);
2408 save_stop_reason (lp
);
2412 /* We caught the SIGSTOP that we intended to catch. */
2414 linux_nat_debug_printf ("Expected SIGSTOP caught for %s.",
2415 lp
->ptid
.to_string ().c_str ());
2419 /* If we are waiting for this stop so we can report the thread
2420 stopped then we need to record this status. Otherwise, we can
2421 now discard this stop event. */
2422 if (lp
->last_resume_kind
== resume_stop
)
2424 lp
->status
= status
;
2425 save_stop_reason (lp
);
2433 /* Return non-zero if LP has a wait status pending. Discard the
2434 pending event and resume the LWP if the event that originally
2435 caused the stop became uninteresting. */
2438 status_callback (struct lwp_info
*lp
)
2440 /* Only report a pending wait status if we pretend that this has
2441 indeed been resumed. */
2445 if (!lwp_status_pending_p (lp
))
2448 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
2449 || lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2451 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2455 pc
= regcache_read_pc (regcache
);
2457 if (pc
!= lp
->stop_pc
)
2459 linux_nat_debug_printf ("PC of %s changed. was=%s, now=%s",
2460 lp
->ptid
.to_string ().c_str (),
2461 paddress (current_inferior ()->arch (),
2463 paddress (current_inferior ()->arch (), pc
));
2467 #if !USE_SIGTRAP_SIGINFO
2468 else if (!breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2470 linux_nat_debug_printf ("previous breakpoint of %s, at %s gone",
2471 lp
->ptid
.to_string ().c_str (),
2472 paddress (current_inferior ()->arch (),
2481 linux_nat_debug_printf ("pending event of %s cancelled.",
2482 lp
->ptid
.to_string ().c_str ());
2485 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2493 /* Count the LWP's that have had events. */
2496 count_events_callback (struct lwp_info
*lp
, int *count
)
2498 gdb_assert (count
!= NULL
);
2500 /* Select only resumed LWPs that have an event pending. */
2501 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2507 /* Select the LWP (if any) that is currently being single-stepped. */
2510 select_singlestep_lwp_callback (struct lwp_info
*lp
)
2512 if (lp
->last_resume_kind
== resume_step
2519 /* Returns true if LP has a status pending. */
2522 lwp_status_pending_p (struct lwp_info
*lp
)
2524 /* We check for lp->waitstatus in addition to lp->status, because we
2525 can have pending process exits recorded in lp->status and
2526 W_EXITCODE(0,0) happens to be 0. */
2527 return lp
->status
!= 0 || lp
->waitstatus
.kind () != TARGET_WAITKIND_IGNORE
;
2530 /* Select the Nth LWP that has had an event. */
2533 select_event_lwp_callback (struct lwp_info
*lp
, int *selector
)
2535 gdb_assert (selector
!= NULL
);
2537 /* Select only resumed LWPs that have an event pending. */
2538 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2539 if ((*selector
)-- == 0)
2545 /* Called when the LWP stopped for a signal/trap. If it stopped for a
2546 trap check what caused it (breakpoint, watchpoint, trace, etc.),
2547 and save the result in the LWP's stop_reason field. If it stopped
2548 for a breakpoint, decrement the PC if necessary on the lwp's
2552 save_stop_reason (struct lwp_info
*lp
)
2554 struct regcache
*regcache
;
2555 struct gdbarch
*gdbarch
;
2558 #if USE_SIGTRAP_SIGINFO
2562 gdb_assert (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
);
2563 gdb_assert (lp
->status
!= 0);
2565 if (!linux_target
->low_status_is_event (lp
->status
))
2568 inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
2569 if (inf
->starting_up
)
2572 regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2573 gdbarch
= regcache
->arch ();
2575 pc
= regcache_read_pc (regcache
);
2576 sw_bp_pc
= pc
- gdbarch_decr_pc_after_break (gdbarch
);
2578 #if USE_SIGTRAP_SIGINFO
2579 if (linux_nat_get_siginfo (lp
->ptid
, &siginfo
))
2581 if (siginfo
.si_signo
== SIGTRAP
)
2583 if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
)
2584 && GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2586 /* The si_code is ambiguous on this arch -- check debug
2588 if (!check_stopped_by_watchpoint (lp
))
2589 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2591 else if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
))
2593 /* If we determine the LWP stopped for a SW breakpoint,
2594 trust it. Particularly don't check watchpoint
2595 registers, because, at least on s390, we'd find
2596 stopped-by-watchpoint as long as there's a watchpoint
2598 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2600 else if (GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2602 /* This can indicate either a hardware breakpoint or
2603 hardware watchpoint. Check debug registers. */
2604 if (!check_stopped_by_watchpoint (lp
))
2605 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2607 else if (siginfo
.si_code
== TRAP_TRACE
)
2609 linux_nat_debug_printf ("%s stopped by trace",
2610 lp
->ptid
.to_string ().c_str ());
2612 /* We may have single stepped an instruction that
2613 triggered a watchpoint. In that case, on some
2614 architectures (such as x86), instead of TRAP_HWBKPT,
2615 si_code indicates TRAP_TRACE, and we need to check
2616 the debug registers separately. */
2617 check_stopped_by_watchpoint (lp
);
2622 if ((!lp
->step
|| lp
->stop_pc
== sw_bp_pc
)
2623 && software_breakpoint_inserted_here_p (regcache
->aspace (),
2626 /* The LWP was either continued, or stepped a software
2627 breakpoint instruction. */
2628 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2631 if (hardware_breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2632 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2634 if (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
)
2635 check_stopped_by_watchpoint (lp
);
2638 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
)
2640 linux_nat_debug_printf ("%s stopped by software breakpoint",
2641 lp
->ptid
.to_string ().c_str ());
2643 /* Back up the PC if necessary. */
2645 regcache_write_pc (regcache
, sw_bp_pc
);
2647 /* Update this so we record the correct stop PC below. */
2650 else if (lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2652 linux_nat_debug_printf ("%s stopped by hardware breakpoint",
2653 lp
->ptid
.to_string ().c_str ());
2655 else if (lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
)
2657 linux_nat_debug_printf ("%s stopped by hardware watchpoint",
2658 lp
->ptid
.to_string ().c_str ());
2665 /* Returns true if the LWP had stopped for a software breakpoint. */
2668 linux_nat_target::stopped_by_sw_breakpoint ()
2670 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2672 gdb_assert (lp
!= NULL
);
2674 return lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
;
2677 /* Implement the supports_stopped_by_sw_breakpoint method. */
2680 linux_nat_target::supports_stopped_by_sw_breakpoint ()
2682 return USE_SIGTRAP_SIGINFO
;
2685 /* Returns true if the LWP had stopped for a hardware
2686 breakpoint/watchpoint. */
2689 linux_nat_target::stopped_by_hw_breakpoint ()
2691 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2693 gdb_assert (lp
!= NULL
);
2695 return lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
;
2698 /* Implement the supports_stopped_by_hw_breakpoint method. */
2701 linux_nat_target::supports_stopped_by_hw_breakpoint ()
2703 return USE_SIGTRAP_SIGINFO
;
2706 /* Select one LWP out of those that have events pending. */
2709 select_event_lwp (ptid_t filter
, struct lwp_info
**orig_lp
, int *status
)
2712 int random_selector
;
2713 struct lwp_info
*event_lp
= NULL
;
2715 /* Record the wait status for the original LWP. */
2716 (*orig_lp
)->status
= *status
;
2718 /* In all-stop, give preference to the LWP that is being
2719 single-stepped. There will be at most one, and it will be the
2720 LWP that the core is most interested in. If we didn't do this,
2721 then we'd have to handle pending step SIGTRAPs somehow in case
2722 the core later continues the previously-stepped thread, as
2723 otherwise we'd report the pending SIGTRAP then, and the core, not
2724 having stepped the thread, wouldn't understand what the trap was
2725 for, and therefore would report it to the user as a random
2727 if (!target_is_non_stop_p ())
2729 event_lp
= iterate_over_lwps (filter
, select_singlestep_lwp_callback
);
2730 if (event_lp
!= NULL
)
2732 linux_nat_debug_printf ("Select single-step %s",
2733 event_lp
->ptid
.to_string ().c_str ());
2737 if (event_lp
== NULL
)
2739 /* Pick one at random, out of those which have had events. */
2741 /* First see how many events we have. */
2742 iterate_over_lwps (filter
,
2743 [&] (struct lwp_info
*info
)
2745 return count_events_callback (info
, &num_events
);
2747 gdb_assert (num_events
> 0);
2749 /* Now randomly pick a LWP out of those that have had
2751 random_selector
= (int)
2752 ((num_events
* (double) rand ()) / (RAND_MAX
+ 1.0));
2755 linux_nat_debug_printf ("Found %d events, selecting #%d",
2756 num_events
, random_selector
);
2759 = (iterate_over_lwps
2761 [&] (struct lwp_info
*info
)
2763 return select_event_lwp_callback (info
,
2768 if (event_lp
!= NULL
)
2770 /* Switch the event LWP. */
2771 *orig_lp
= event_lp
;
2772 *status
= event_lp
->status
;
2775 /* Flush the wait status for the event LWP. */
2776 (*orig_lp
)->status
= 0;
2779 /* Return non-zero if LP has been resumed. */
2782 resumed_callback (struct lwp_info
*lp
)
2787 /* Check if we should go on and pass this event to common code.
2789 If so, save the status to the lwp_info structure associated to LWPID. */
2792 linux_nat_filter_event (int lwpid
, int status
)
2794 struct lwp_info
*lp
;
2795 int event
= linux_ptrace_get_extended_event (status
);
2797 lp
= find_lwp_pid (ptid_t (lwpid
));
2799 /* Check for events reported by anything not in our LWP list. */
2802 if (WIFSTOPPED (status
))
2804 if (WSTOPSIG (status
) == SIGTRAP
&& event
== PTRACE_EVENT_EXEC
)
2806 /* A non-leader thread exec'ed after we've seen the
2807 leader zombie, and removed it from our lists (in
2808 check_zombie_leaders). The non-leader thread changes
2809 its tid to the tgid. */
2810 linux_nat_debug_printf
2811 ("Re-adding thread group leader LWP %d after exec.",
2814 lp
= add_lwp (ptid_t (lwpid
, lwpid
));
2817 add_thread (linux_target
, lp
->ptid
);
2821 /* A process we are controlling has forked and the new
2822 child's stop was reported to us by the kernel. Save
2823 its PID and go back to waiting for the fork event to
2824 be reported - the stopped process might be returned
2825 from waitpid before or after the fork event is. */
2826 linux_nat_debug_printf
2827 ("Saving LWP %d status %s in stopped_pids list",
2828 lwpid
, status_to_str (status
).c_str ());
2829 add_to_pid_list (&stopped_pids
, lwpid
, status
);
2834 /* Don't report an event for the exit of an LWP not in our
2835 list, i.e. not part of any inferior we're debugging.
2836 This can happen if we detach from a program we originally
2837 forked and then it exits. However, note that we may have
2838 earlier deleted a leader of an inferior we're debugging,
2839 in check_zombie_leaders. Re-add it back here if so. */
2840 for (inferior
*inf
: all_inferiors (linux_target
))
2842 if (inf
->pid
== lwpid
)
2844 linux_nat_debug_printf
2845 ("Re-adding thread group leader LWP %d after exit.",
2848 lp
= add_lwp (ptid_t (lwpid
, lwpid
));
2850 add_thread (linux_target
, lp
->ptid
);
2860 /* This LWP is stopped now. (And if dead, this prevents it from
2861 ever being continued.) */
2864 if (WIFSTOPPED (status
) && lp
->must_set_ptrace_flags
)
2866 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2867 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
2869 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
2870 lp
->must_set_ptrace_flags
= 0;
2873 /* Handle GNU/Linux's syscall SIGTRAPs. */
2874 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
2876 /* No longer need the sysgood bit. The ptrace event ends up
2877 recorded in lp->waitstatus if we care for it. We can carry
2878 on handling the event like a regular SIGTRAP from here
2880 status
= W_STOPCODE (SIGTRAP
);
2881 if (linux_handle_syscall_trap (lp
, 0))
2886 /* Almost all other ptrace-stops are known to be outside of system
2887 calls, with further exceptions in linux_handle_extended_wait. */
2888 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
2891 /* Handle GNU/Linux's extended waitstatus for trace events. */
2892 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
2893 && linux_is_extended_waitstatus (status
))
2895 linux_nat_debug_printf ("Handling extended status 0x%06x", status
);
2897 if (linux_handle_extended_wait (lp
, status
))
2901 /* Check if the thread has exited. */
2902 if (WIFEXITED (status
) || WIFSIGNALED (status
))
2904 if (!report_thread_events
&& !is_leader (lp
))
2906 linux_nat_debug_printf ("%s exited.",
2907 lp
->ptid
.to_string ().c_str ());
2909 /* If this was not the leader exiting, then the exit signal
2910 was not the end of the debugged application and should be
2916 /* Note that even if the leader was ptrace-stopped, it can still
2917 exit, if e.g., some other thread brings down the whole
2918 process (calls `exit'). So don't assert that the lwp is
2920 linux_nat_debug_printf ("LWP %ld exited (resumed=%d)",
2921 lp
->ptid
.lwp (), lp
->resumed
);
2923 /* Dead LWP's aren't expected to reported a pending sigstop. */
2926 /* Store the pending event in the waitstatus, because
2927 W_EXITCODE(0,0) == 0. */
2928 lp
->waitstatus
= host_status_to_waitstatus (status
);
2932 /* Make sure we don't report a SIGSTOP that we sent ourselves in
2933 an attempt to stop an LWP. */
2935 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGSTOP
)
2939 if (lp
->last_resume_kind
== resume_stop
)
2941 linux_nat_debug_printf ("resume_stop SIGSTOP caught for %s.",
2942 lp
->ptid
.to_string ().c_str ());
2946 /* This is a delayed SIGSTOP. Filter out the event. */
2948 linux_nat_debug_printf
2949 ("%s %s, 0, 0 (discard delayed SIGSTOP)",
2950 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
2951 lp
->ptid
.to_string ().c_str ());
2953 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2954 gdb_assert (lp
->resumed
);
2959 /* Make sure we don't report a SIGINT that we have already displayed
2960 for another thread. */
2961 if (lp
->ignore_sigint
2962 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGINT
)
2964 linux_nat_debug_printf ("Delayed SIGINT caught for %s.",
2965 lp
->ptid
.to_string ().c_str ());
2967 /* This is a delayed SIGINT. */
2968 lp
->ignore_sigint
= 0;
2970 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2971 linux_nat_debug_printf ("%s %s, 0, 0 (discard SIGINT)",
2972 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
2973 lp
->ptid
.to_string ().c_str ());
2974 gdb_assert (lp
->resumed
);
2976 /* Discard the event. */
2980 /* Don't report signals that GDB isn't interested in, such as
2981 signals that are neither printed nor stopped upon. Stopping all
2982 threads can be a bit time-consuming, so if we want decent
2983 performance with heavily multi-threaded programs, especially when
2984 they're using a high frequency timer, we'd better avoid it if we
2986 if (WIFSTOPPED (status
))
2988 enum gdb_signal signo
= gdb_signal_from_host (WSTOPSIG (status
));
2990 if (!target_is_non_stop_p ())
2992 /* Only do the below in all-stop, as we currently use SIGSTOP
2993 to implement target_stop (see linux_nat_stop) in
2995 if (signo
== GDB_SIGNAL_INT
&& signal_pass_state (signo
) == 0)
2997 /* If ^C/BREAK is typed at the tty/console, SIGINT gets
2998 forwarded to the entire process group, that is, all LWPs
2999 will receive it - unless they're using CLONE_THREAD to
3000 share signals. Since we only want to report it once, we
3001 mark it as ignored for all LWPs except this one. */
3002 iterate_over_lwps (ptid_t (lp
->ptid
.pid ()), set_ignore_sigint
);
3003 lp
->ignore_sigint
= 0;
3006 maybe_clear_ignore_sigint (lp
);
3009 /* When using hardware single-step, we need to report every signal.
3010 Otherwise, signals in pass_mask may be short-circuited
3011 except signals that might be caused by a breakpoint, or SIGSTOP
3012 if we sent the SIGSTOP and are waiting for it to arrive. */
3014 && WSTOPSIG (status
) && sigismember (&pass_mask
, WSTOPSIG (status
))
3015 && (WSTOPSIG (status
) != SIGSTOP
3016 || !linux_target
->find_thread (lp
->ptid
)->stop_requested
)
3017 && !linux_wstatus_maybe_breakpoint (status
))
3019 linux_resume_one_lwp (lp
, lp
->step
, signo
);
3020 linux_nat_debug_printf
3021 ("%s %s, %s (preempt 'handle')",
3022 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
3023 lp
->ptid
.to_string ().c_str (),
3024 (signo
!= GDB_SIGNAL_0
3025 ? strsignal (gdb_signal_to_host (signo
)) : "0"));
3030 /* An interesting event. */
3032 lp
->status
= status
;
3033 save_stop_reason (lp
);
3036 /* Detect zombie thread group leaders, and "exit" them. We can't reap
3037 their exits until all other threads in the group have exited. */
3040 check_zombie_leaders (void)
3042 for (inferior
*inf
: all_inferiors ())
3044 struct lwp_info
*leader_lp
;
3049 leader_lp
= find_lwp_pid (ptid_t (inf
->pid
));
3050 if (leader_lp
!= NULL
3051 /* Check if there are other threads in the group, as we may
3052 have raced with the inferior simply exiting. Note this
3053 isn't a watertight check. If the inferior is
3054 multi-threaded and is exiting, it may be we see the
3055 leader as zombie before we reap all the non-leader
3056 threads. See comments below. */
3057 && num_lwps (inf
->pid
) > 1
3058 && linux_proc_pid_is_zombie (inf
->pid
))
3060 /* A zombie leader in a multi-threaded program can mean one
3063 #1 - Only the leader exited, not the whole program, e.g.,
3064 with pthread_exit. Since we can't reap the leader's exit
3065 status until all other threads are gone and reaped too,
3066 we want to delete the zombie leader right away, as it
3067 can't be debugged, we can't read its registers, etc.
3068 This is the main reason we check for zombie leaders
3071 #2 - The whole thread-group/process exited (a group exit,
3072 via e.g. exit(3), and there is (or will be shortly) an
3073 exit reported for each thread in the process, and then
3074 finally an exit for the leader once the non-leaders are
3077 #3 - There are 3 or more threads in the group, and a
3078 thread other than the leader exec'd. See comments on
3079 exec events at the top of the file.
3081 Ideally we would never delete the leader for case #2.
3082 Instead, we want to collect the exit status of each
3083 non-leader thread, and then finally collect the exit
3084 status of the leader as normal and use its exit code as
3085 whole-process exit code. Unfortunately, there's no
3086 race-free way to distinguish cases #1 and #2. We can't
3087 assume the exit events for the non-leaders threads are
3088 already pending in the kernel, nor can we assume the
3089 non-leader threads are in zombie state already. Between
3090 the leader becoming zombie and the non-leaders exiting
3091 and becoming zombie themselves, there's a small time
3092 window, so such a check would be racy. Temporarily
3093 pausing all threads and checking to see if all threads
3094 exit or not before re-resuming them would work in the
3095 case that all threads are running right now, but it
3096 wouldn't work if some thread is currently already
3097 ptrace-stopped, e.g., due to scheduler-locking.
3099 So what we do is we delete the leader anyhow, and then
3100 later on when we see its exit status, we re-add it back.
3101 We also make sure that we only report a whole-process
3102 exit when we see the leader exiting, as opposed to when
3103 the last LWP in the LWP list exits, which can be a
3104 non-leader if we deleted the leader here. */
3105 linux_nat_debug_printf ("Thread group leader %d zombie "
3106 "(it exited, or another thread execd), "
3109 exit_lwp (leader_lp
);
3114 /* Convenience function that is called when the kernel reports an exit
3115 event. This decides whether to report the event to GDB as a
3116 process exit event, a thread exit event, or to suppress the
3120 filter_exit_event (struct lwp_info
*event_child
,
3121 struct target_waitstatus
*ourstatus
)
3123 ptid_t ptid
= event_child
->ptid
;
3125 if (!is_leader (event_child
))
3127 if (report_thread_events
)
3128 ourstatus
->set_thread_exited (0);
3130 ourstatus
->set_ignore ();
3132 exit_lwp (event_child
);
3139 linux_nat_wait_1 (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3140 target_wait_flags target_options
)
3142 LINUX_NAT_SCOPED_DEBUG_ENTER_EXIT
;
3145 enum resume_kind last_resume_kind
;
3146 struct lwp_info
*lp
;
3149 /* The first time we get here after starting a new inferior, we may
3150 not have added it to the LWP list yet - this is the earliest
3151 moment at which we know its PID. */
3152 if (ptid
.is_pid () && find_lwp_pid (ptid
) == nullptr)
3154 ptid_t
lwp_ptid (ptid
.pid (), ptid
.pid ());
3156 /* Upgrade the main thread's ptid. */
3157 thread_change_ptid (linux_target
, ptid
, lwp_ptid
);
3158 lp
= add_initial_lwp (lwp_ptid
);
3162 /* Make sure SIGCHLD is blocked until the sigsuspend below. */
3163 block_child_signals (&prev_mask
);
3165 /* First check if there is a LWP with a wait status pending. */
3166 lp
= iterate_over_lwps (ptid
, status_callback
);
3169 linux_nat_debug_printf ("Using pending wait status %s for %s.",
3170 pending_status_str (lp
).c_str (),
3171 lp
->ptid
.to_string ().c_str ());
3174 /* But if we don't find a pending event, we'll have to wait. Always
3175 pull all events out of the kernel. We'll randomly select an
3176 event LWP out of all that have events, to prevent starvation. */
3182 /* Always use -1 and WNOHANG, due to couple of a kernel/ptrace
3185 - If the thread group leader exits while other threads in the
3186 thread group still exist, waitpid(TGID, ...) hangs. That
3187 waitpid won't return an exit status until the other threads
3188 in the group are reaped.
3190 - When a non-leader thread execs, that thread just vanishes
3191 without reporting an exit (so we'd hang if we waited for it
3192 explicitly in that case). The exec event is reported to
3196 lwpid
= my_waitpid (-1, &status
, __WALL
| WNOHANG
);
3198 linux_nat_debug_printf ("waitpid(-1, ...) returned %d, %s",
3200 errno
? safe_strerror (errno
) : "ERRNO-OK");
3204 linux_nat_debug_printf ("waitpid %ld received %s",
3206 status_to_str (status
).c_str ());
3208 linux_nat_filter_event (lwpid
, status
);
3209 /* Retry until nothing comes out of waitpid. A single
3210 SIGCHLD can indicate more than one child stopped. */
3214 /* Now that we've pulled all events out of the kernel, resume
3215 LWPs that don't have an interesting event to report. */
3216 iterate_over_lwps (minus_one_ptid
,
3217 [] (struct lwp_info
*info
)
3219 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
3222 /* ... and find an LWP with a status to report to the core, if
3224 lp
= iterate_over_lwps (ptid
, status_callback
);
3228 /* Check for zombie thread group leaders. Those can't be reaped
3229 until all other threads in the thread group are. */
3230 check_zombie_leaders ();
3232 /* If there are no resumed children left, bail. We'd be stuck
3233 forever in the sigsuspend call below otherwise. */
3234 if (iterate_over_lwps (ptid
, resumed_callback
) == NULL
)
3236 linux_nat_debug_printf ("exit (no resumed LWP)");
3238 ourstatus
->set_no_resumed ();
3240 restore_child_signals_mask (&prev_mask
);
3241 return minus_one_ptid
;
3244 /* No interesting event to report to the core. */
3246 if (target_options
& TARGET_WNOHANG
)
3248 linux_nat_debug_printf ("no interesting events found");
3250 ourstatus
->set_ignore ();
3251 restore_child_signals_mask (&prev_mask
);
3252 return minus_one_ptid
;
3255 /* We shouldn't end up here unless we want to try again. */
3256 gdb_assert (lp
== NULL
);
3258 /* Block until we get an event reported with SIGCHLD. */
3264 status
= lp
->status
;
3267 if (!target_is_non_stop_p ())
3269 /* Now stop all other LWP's ... */
3270 iterate_over_lwps (minus_one_ptid
, stop_callback
);
3272 /* ... and wait until all of them have reported back that
3273 they're no longer running. */
3274 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
3277 /* If we're not waiting for a specific LWP, choose an event LWP from
3278 among those that have had events. Giving equal priority to all
3279 LWPs that have had events helps prevent starvation. */
3280 if (ptid
== minus_one_ptid
|| ptid
.is_pid ())
3281 select_event_lwp (ptid
, &lp
, &status
);
3283 gdb_assert (lp
!= NULL
);
3285 /* Now that we've selected our final event LWP, un-adjust its PC if
3286 it was a software breakpoint, and we can't reliably support the
3287 "stopped by software breakpoint" stop reason. */
3288 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
3289 && !USE_SIGTRAP_SIGINFO
)
3291 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3292 struct gdbarch
*gdbarch
= regcache
->arch ();
3293 int decr_pc
= gdbarch_decr_pc_after_break (gdbarch
);
3299 pc
= regcache_read_pc (regcache
);
3300 regcache_write_pc (regcache
, pc
+ decr_pc
);
3304 /* We'll need this to determine whether to report a SIGSTOP as
3305 GDB_SIGNAL_0. Need to take a copy because resume_clear_callback
3307 last_resume_kind
= lp
->last_resume_kind
;
3309 if (!target_is_non_stop_p ())
3311 /* In all-stop, from the core's perspective, all LWPs are now
3312 stopped until a new resume action is sent over. */
3313 iterate_over_lwps (minus_one_ptid
, resume_clear_callback
);
3317 resume_clear_callback (lp
);
3320 if (linux_target
->low_status_is_event (status
))
3322 linux_nat_debug_printf ("trap ptid is %s.",
3323 lp
->ptid
.to_string ().c_str ());
3326 if (lp
->waitstatus
.kind () != TARGET_WAITKIND_IGNORE
)
3328 *ourstatus
= lp
->waitstatus
;
3329 lp
->waitstatus
.set_ignore ();
3332 *ourstatus
= host_status_to_waitstatus (status
);
3334 linux_nat_debug_printf ("event found");
3336 restore_child_signals_mask (&prev_mask
);
3338 if (last_resume_kind
== resume_stop
3339 && ourstatus
->kind () == TARGET_WAITKIND_STOPPED
3340 && WSTOPSIG (status
) == SIGSTOP
)
3342 /* A thread that has been requested to stop by GDB with
3343 target_stop, and it stopped cleanly, so report as SIG0. The
3344 use of SIGSTOP is an implementation detail. */
3345 ourstatus
->set_stopped (GDB_SIGNAL_0
);
3348 if (ourstatus
->kind () == TARGET_WAITKIND_EXITED
3349 || ourstatus
->kind () == TARGET_WAITKIND_SIGNALLED
)
3352 lp
->core
= linux_common_core_of_thread (lp
->ptid
);
3354 if (ourstatus
->kind () == TARGET_WAITKIND_EXITED
)
3355 return filter_exit_event (lp
, ourstatus
);
3360 /* Resume LWPs that are currently stopped without any pending status
3361 to report, but are resumed from the core's perspective. */
3364 resume_stopped_resumed_lwps (struct lwp_info
*lp
, const ptid_t wait_ptid
)
3366 inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
3370 linux_nat_debug_printf ("NOT resuming LWP %s, not stopped",
3371 lp
->ptid
.to_string ().c_str ());
3373 else if (!lp
->resumed
)
3375 linux_nat_debug_printf ("NOT resuming LWP %s, not resumed",
3376 lp
->ptid
.to_string ().c_str ());
3378 else if (lwp_status_pending_p (lp
))
3380 linux_nat_debug_printf ("NOT resuming LWP %s, has pending status",
3381 lp
->ptid
.to_string ().c_str ());
3383 else if (inf
->vfork_child
!= nullptr)
3385 linux_nat_debug_printf ("NOT resuming LWP %s (vfork parent)",
3386 lp
->ptid
.to_string ().c_str ());
3390 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3391 struct gdbarch
*gdbarch
= regcache
->arch ();
3395 CORE_ADDR pc
= regcache_read_pc (regcache
);
3396 int leave_stopped
= 0;
3398 /* Don't bother if there's a breakpoint at PC that we'd hit
3399 immediately, and we're not waiting for this LWP. */
3400 if (!lp
->ptid
.matches (wait_ptid
))
3402 if (breakpoint_inserted_here_p (regcache
->aspace (), pc
))
3408 linux_nat_debug_printf
3409 ("resuming stopped-resumed LWP %s at %s: step=%d",
3410 lp
->ptid
.to_string ().c_str (), paddress (gdbarch
, pc
),
3413 linux_resume_one_lwp_throw (lp
, lp
->step
, GDB_SIGNAL_0
);
3416 catch (const gdb_exception_error
&ex
)
3418 if (!check_ptrace_stopped_lwp_gone (lp
))
3427 linux_nat_target::wait (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3428 target_wait_flags target_options
)
3430 LINUX_NAT_SCOPED_DEBUG_ENTER_EXIT
;
3434 linux_nat_debug_printf ("[%s], [%s]", ptid
.to_string ().c_str (),
3435 target_options_to_string (target_options
).c_str ());
3437 /* Flush the async file first. */
3438 if (target_is_async_p ())
3439 async_file_flush ();
3441 /* Resume LWPs that are currently stopped without any pending status
3442 to report, but are resumed from the core's perspective. LWPs get
3443 in this state if we find them stopping at a time we're not
3444 interested in reporting the event (target_wait on a
3445 specific_process, for example, see linux_nat_wait_1), and
3446 meanwhile the event became uninteresting. Don't bother resuming
3447 LWPs we're not going to wait for if they'd stop immediately. */
3448 if (target_is_non_stop_p ())
3449 iterate_over_lwps (minus_one_ptid
,
3450 [=] (struct lwp_info
*info
)
3452 return resume_stopped_resumed_lwps (info
, ptid
);
3455 event_ptid
= linux_nat_wait_1 (ptid
, ourstatus
, target_options
);
3457 /* If we requested any event, and something came out, assume there
3458 may be more. If we requested a specific lwp or process, also
3459 assume there may be more. */
3460 if (target_is_async_p ()
3461 && ((ourstatus
->kind () != TARGET_WAITKIND_IGNORE
3462 && ourstatus
->kind () != TARGET_WAITKIND_NO_RESUMED
)
3463 || ptid
!= minus_one_ptid
))
3472 kill_one_lwp (pid_t pid
)
3474 /* PTRACE_KILL may resume the inferior. Send SIGKILL first. */
3477 kill_lwp (pid
, SIGKILL
);
3479 if (debug_linux_nat
)
3481 int save_errno
= errno
;
3483 linux_nat_debug_printf
3484 ("kill (SIGKILL) %ld, 0, 0 (%s)", (long) pid
,
3485 save_errno
!= 0 ? safe_strerror (save_errno
) : "OK");
3488 /* Some kernels ignore even SIGKILL for processes under ptrace. */
3491 ptrace (PTRACE_KILL
, pid
, 0, 0);
3492 if (debug_linux_nat
)
3494 int save_errno
= errno
;
3496 linux_nat_debug_printf
3497 ("PTRACE_KILL %ld, 0, 0 (%s)", (long) pid
,
3498 save_errno
? safe_strerror (save_errno
) : "OK");
3502 /* Wait for an LWP to die. */
3505 kill_wait_one_lwp (pid_t pid
)
3509 /* We must make sure that there are no pending events (delayed
3510 SIGSTOPs, pending SIGTRAPs, etc.) to make sure the current
3511 program doesn't interfere with any following debugging session. */
3515 res
= my_waitpid (pid
, NULL
, __WALL
);
3516 if (res
!= (pid_t
) -1)
3518 linux_nat_debug_printf ("wait %ld received unknown.", (long) pid
);
3520 /* The Linux kernel sometimes fails to kill a thread
3521 completely after PTRACE_KILL; that goes from the stop
3522 point in do_fork out to the one in get_signal_to_deliver
3523 and waits again. So kill it again. */
3529 gdb_assert (res
== -1 && errno
== ECHILD
);
3532 /* Callback for iterate_over_lwps. */
3535 kill_callback (struct lwp_info
*lp
)
3537 kill_one_lwp (lp
->ptid
.lwp ());
3541 /* Callback for iterate_over_lwps. */
3544 kill_wait_callback (struct lwp_info
*lp
)
3546 kill_wait_one_lwp (lp
->ptid
.lwp ());
3550 /* Kill the fork children of any threads of inferior INF that are
3551 stopped at a fork event. */
3554 kill_unfollowed_fork_children (struct inferior
*inf
)
3556 for (thread_info
*thread
: inf
->non_exited_threads ())
3558 struct target_waitstatus
*ws
= &thread
->pending_follow
;
3560 if (ws
->kind () == TARGET_WAITKIND_FORKED
3561 || ws
->kind () == TARGET_WAITKIND_VFORKED
)
3563 ptid_t child_ptid
= ws
->child_ptid ();
3564 int child_pid
= child_ptid
.pid ();
3565 int child_lwp
= child_ptid
.lwp ();
3567 kill_one_lwp (child_lwp
);
3568 kill_wait_one_lwp (child_lwp
);
3570 /* Let the arch-specific native code know this process is
3572 linux_target
->low_forget_process (child_pid
);
3578 linux_nat_target::kill ()
3580 /* If we're stopped while forking and we haven't followed yet,
3581 kill the other task. We need to do this first because the
3582 parent will be sleeping if this is a vfork. */
3583 kill_unfollowed_fork_children (current_inferior ());
3585 if (forks_exist_p ())
3586 linux_fork_killall ();
3589 ptid_t ptid
= ptid_t (inferior_ptid
.pid ());
3591 /* Stop all threads before killing them, since ptrace requires
3592 that the thread is stopped to successfully PTRACE_KILL. */
3593 iterate_over_lwps (ptid
, stop_callback
);
3594 /* ... and wait until all of them have reported back that
3595 they're no longer running. */
3596 iterate_over_lwps (ptid
, stop_wait_callback
);
3598 /* Kill all LWP's ... */
3599 iterate_over_lwps (ptid
, kill_callback
);
3601 /* ... and wait until we've flushed all events. */
3602 iterate_over_lwps (ptid
, kill_wait_callback
);
3605 target_mourn_inferior (inferior_ptid
);
3609 linux_nat_target::mourn_inferior ()
3611 LINUX_NAT_SCOPED_DEBUG_ENTER_EXIT
;
3613 int pid
= inferior_ptid
.pid ();
3615 purge_lwp_list (pid
);
3617 close_proc_mem_file (pid
);
3619 if (! forks_exist_p ())
3620 /* Normal case, no other forks available. */
3621 inf_ptrace_target::mourn_inferior ();
3623 /* Multi-fork case. The current inferior_ptid has exited, but
3624 there are other viable forks to debug. Delete the exiting
3625 one and context-switch to the first available. */
3626 linux_fork_mourn_inferior ();
3628 /* Let the arch-specific native code know this process is gone. */
3629 linux_target
->low_forget_process (pid
);
3632 /* Convert a native/host siginfo object, into/from the siginfo in the
3633 layout of the inferiors' architecture. */
3636 siginfo_fixup (siginfo_t
*siginfo
, gdb_byte
*inf_siginfo
, int direction
)
3638 /* If the low target didn't do anything, then just do a straight
3640 if (!linux_target
->low_siginfo_fixup (siginfo
, inf_siginfo
, direction
))
3643 memcpy (siginfo
, inf_siginfo
, sizeof (siginfo_t
));
3645 memcpy (inf_siginfo
, siginfo
, sizeof (siginfo_t
));
3649 static enum target_xfer_status
3650 linux_xfer_siginfo (ptid_t ptid
, enum target_object object
,
3651 const char *annex
, gdb_byte
*readbuf
,
3652 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3653 ULONGEST
*xfered_len
)
3656 gdb_byte inf_siginfo
[sizeof (siginfo_t
)];
3658 gdb_assert (object
== TARGET_OBJECT_SIGNAL_INFO
);
3659 gdb_assert (readbuf
|| writebuf
);
3661 if (offset
> sizeof (siginfo
))
3662 return TARGET_XFER_E_IO
;
3664 if (!linux_nat_get_siginfo (ptid
, &siginfo
))
3665 return TARGET_XFER_E_IO
;
3667 /* When GDB is built as a 64-bit application, ptrace writes into
3668 SIGINFO an object with 64-bit layout. Since debugging a 32-bit
3669 inferior with a 64-bit GDB should look the same as debugging it
3670 with a 32-bit GDB, we need to convert it. GDB core always sees
3671 the converted layout, so any read/write will have to be done
3673 siginfo_fixup (&siginfo
, inf_siginfo
, 0);
3675 if (offset
+ len
> sizeof (siginfo
))
3676 len
= sizeof (siginfo
) - offset
;
3678 if (readbuf
!= NULL
)
3679 memcpy (readbuf
, inf_siginfo
+ offset
, len
);
3682 memcpy (inf_siginfo
+ offset
, writebuf
, len
);
3684 /* Convert back to ptrace layout before flushing it out. */
3685 siginfo_fixup (&siginfo
, inf_siginfo
, 1);
3687 int pid
= get_ptrace_pid (ptid
);
3689 ptrace (PTRACE_SETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, &siginfo
);
3691 return TARGET_XFER_E_IO
;
3695 return TARGET_XFER_OK
;
3698 static enum target_xfer_status
3699 linux_nat_xfer_osdata (enum target_object object
,
3700 const char *annex
, gdb_byte
*readbuf
,
3701 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3702 ULONGEST
*xfered_len
);
3704 static enum target_xfer_status
3705 linux_proc_xfer_memory_partial (int pid
, gdb_byte
*readbuf
,
3706 const gdb_byte
*writebuf
, ULONGEST offset
,
3707 LONGEST len
, ULONGEST
*xfered_len
);
3709 enum target_xfer_status
3710 linux_nat_target::xfer_partial (enum target_object object
,
3711 const char *annex
, gdb_byte
*readbuf
,
3712 const gdb_byte
*writebuf
,
3713 ULONGEST offset
, ULONGEST len
, ULONGEST
*xfered_len
)
3715 if (object
== TARGET_OBJECT_SIGNAL_INFO
)
3716 return linux_xfer_siginfo (inferior_ptid
, object
, annex
, readbuf
, writebuf
,
3717 offset
, len
, xfered_len
);
3719 /* The target is connected but no live inferior is selected. Pass
3720 this request down to a lower stratum (e.g., the executable
3722 if (object
== TARGET_OBJECT_MEMORY
&& inferior_ptid
== null_ptid
)
3723 return TARGET_XFER_EOF
;
3725 if (object
== TARGET_OBJECT_AUXV
)
3726 return memory_xfer_auxv (this, object
, annex
, readbuf
, writebuf
,
3727 offset
, len
, xfered_len
);
3729 if (object
== TARGET_OBJECT_OSDATA
)
3730 return linux_nat_xfer_osdata (object
, annex
, readbuf
, writebuf
,
3731 offset
, len
, xfered_len
);
3733 if (object
== TARGET_OBJECT_MEMORY
)
3735 /* GDB calculates all addresses in the largest possible address
3736 width. The address width must be masked before its final use
3737 by linux_proc_xfer_partial.
3739 Compare ADDR_BIT first to avoid a compiler warning on shift overflow. */
3740 int addr_bit
= gdbarch_addr_bit (current_inferior ()->arch ());
3742 if (addr_bit
< (sizeof (ULONGEST
) * HOST_CHAR_BIT
))
3743 offset
&= ((ULONGEST
) 1 << addr_bit
) - 1;
3745 /* If /proc/pid/mem is writable, don't fallback to ptrace. If
3746 the write via /proc/pid/mem fails because the inferior execed
3747 (and we haven't seen the exec event yet), a subsequent ptrace
3748 poke would incorrectly write memory to the post-exec address
3749 space, while the core was trying to write to the pre-exec
3751 if (proc_mem_file_is_writable ())
3752 return linux_proc_xfer_memory_partial (inferior_ptid
.pid (), readbuf
,
3753 writebuf
, offset
, len
,
3757 return inf_ptrace_target::xfer_partial (object
, annex
, readbuf
, writebuf
,
3758 offset
, len
, xfered_len
);
3762 linux_nat_target::thread_alive (ptid_t ptid
)
3764 /* As long as a PTID is in lwp list, consider it alive. */
3765 return find_lwp_pid (ptid
) != NULL
;
3768 /* Implement the to_update_thread_list target method for this
3772 linux_nat_target::update_thread_list ()
3774 /* We add/delete threads from the list as clone/exit events are
3775 processed, so just try deleting exited threads still in the
3777 delete_exited_threads ();
3779 /* Update the processor core that each lwp/thread was last seen
3781 for (lwp_info
*lwp
: all_lwps ())
3783 /* Avoid accessing /proc if the thread hasn't run since we last
3784 time we fetched the thread's core. Accessing /proc becomes
3785 noticeably expensive when we have thousands of LWPs. */
3786 if (lwp
->core
== -1)
3787 lwp
->core
= linux_common_core_of_thread (lwp
->ptid
);
3792 linux_nat_target::pid_to_str (ptid_t ptid
)
3795 && (ptid
.pid () != ptid
.lwp ()
3796 || num_lwps (ptid
.pid ()) > 1))
3797 return string_printf ("LWP %ld", ptid
.lwp ());
3799 return normal_pid_to_str (ptid
);
3803 linux_nat_target::thread_name (struct thread_info
*thr
)
3805 return linux_proc_tid_get_name (thr
->ptid
);
3808 /* Accepts an integer PID; Returns a string representing a file that
3809 can be opened to get the symbols for the child process. */
3812 linux_nat_target::pid_to_exec_file (int pid
)
3814 return linux_proc_pid_to_exec_file (pid
);
3817 /* Object representing an /proc/PID/mem open file. We keep one such
3818 file open per inferior.
3820 It might be tempting to think about only ever opening one file at
3821 most for all inferiors, closing/reopening the file as we access
3822 memory of different inferiors, to minimize number of file
3823 descriptors open, which can otherwise run into resource limits.
3824 However, that does not work correctly -- if the inferior execs and
3825 we haven't processed the exec event yet, and, we opened a
3826 /proc/PID/mem file, we will get a mem file accessing the post-exec
3827 address space, thinking we're opening it for the pre-exec address
3828 space. That is dangerous as we can poke memory (e.g. clearing
3829 breakpoints) in the post-exec memory by mistake, corrupting the
3830 inferior. For that reason, we open the mem file as early as
3831 possible, right after spawning, forking or attaching to the
3832 inferior, when the inferior is stopped and thus before it has a
3835 Note that after opening the file, even if the thread we opened it
3836 for subsequently exits, the open file is still usable for accessing
3837 memory. It's only when the whole process exits or execs that the
3838 file becomes invalid, at which point reads/writes return EOF. */
3843 proc_mem_file (ptid_t ptid
, int fd
)
3844 : m_ptid (ptid
), m_fd (fd
)
3846 gdb_assert (m_fd
!= -1);
3851 linux_nat_debug_printf ("closing fd %d for /proc/%d/task/%ld/mem",
3852 m_fd
, m_ptid
.pid (), m_ptid
.lwp ());
3856 DISABLE_COPY_AND_ASSIGN (proc_mem_file
);
3864 /* The LWP this file was opened for. Just for debugging
3868 /* The file descriptor. */
3872 /* The map between an inferior process id, and the open /proc/PID/mem
3873 file. This is stored in a map instead of in a per-inferior
3874 structure because we need to be able to access memory of processes
3875 which don't have a corresponding struct inferior object. E.g.,
3876 with "detach-on-fork on" (the default), and "follow-fork parent"
3877 (also default), we don't create an inferior for the fork child, but
3878 we still need to remove breakpoints from the fork child's
3880 static std::unordered_map
<int, proc_mem_file
> proc_mem_file_map
;
3882 /* Close the /proc/PID/mem file for PID. */
3885 close_proc_mem_file (pid_t pid
)
3887 proc_mem_file_map
.erase (pid
);
3890 /* Open the /proc/PID/mem file for the process (thread group) of PTID.
3891 We actually open /proc/PID/task/LWP/mem, as that's the LWP we know
3892 exists and is stopped right now. We prefer the
3893 /proc/PID/task/LWP/mem form over /proc/LWP/mem to avoid tid-reuse
3894 races, just in case this is ever called on an already-waited
3898 open_proc_mem_file (ptid_t ptid
)
3900 auto iter
= proc_mem_file_map
.find (ptid
.pid ());
3901 gdb_assert (iter
== proc_mem_file_map
.end ());
3904 xsnprintf (filename
, sizeof filename
,
3905 "/proc/%d/task/%ld/mem", ptid
.pid (), ptid
.lwp ());
3907 int fd
= gdb_open_cloexec (filename
, O_RDWR
| O_LARGEFILE
, 0).release ();
3911 warning (_("opening /proc/PID/mem file for lwp %d.%ld failed: %s (%d)"),
3912 ptid
.pid (), ptid
.lwp (),
3913 safe_strerror (errno
), errno
);
3917 proc_mem_file_map
.emplace (std::piecewise_construct
,
3918 std::forward_as_tuple (ptid
.pid ()),
3919 std::forward_as_tuple (ptid
, fd
));
3921 linux_nat_debug_printf ("opened fd %d for lwp %d.%ld",
3922 fd
, ptid
.pid (), ptid
.lwp ());
3925 /* Helper for linux_proc_xfer_memory_partial and
3926 proc_mem_file_is_writable. FD is the already opened /proc/pid/mem
3927 file, and PID is the pid of the corresponding process. The rest of
3928 the arguments are like linux_proc_xfer_memory_partial's. */
3930 static enum target_xfer_status
3931 linux_proc_xfer_memory_partial_fd (int fd
, int pid
,
3932 gdb_byte
*readbuf
, const gdb_byte
*writebuf
,
3933 ULONGEST offset
, LONGEST len
,
3934 ULONGEST
*xfered_len
)
3938 gdb_assert (fd
!= -1);
3940 /* Use pread64/pwrite64 if available, since they save a syscall and
3941 can handle 64-bit offsets even on 32-bit platforms (for instance,
3942 SPARC debugging a SPARC64 application). But only use them if the
3943 offset isn't so high that when cast to off_t it'd be negative, as
3944 seen on SPARC64. pread64/pwrite64 outright reject such offsets.
3947 if ((off_t
) offset
>= 0)
3948 ret
= (readbuf
!= nullptr
3949 ? pread64 (fd
, readbuf
, len
, offset
)
3950 : pwrite64 (fd
, writebuf
, len
, offset
));
3954 ret
= lseek (fd
, offset
, SEEK_SET
);
3956 ret
= (readbuf
!= nullptr
3957 ? read (fd
, readbuf
, len
)
3958 : write (fd
, writebuf
, len
));
3963 linux_nat_debug_printf ("accessing fd %d for pid %d failed: %s (%d)",
3964 fd
, pid
, safe_strerror (errno
), errno
);
3965 return TARGET_XFER_E_IO
;
3969 /* EOF means the address space is gone, the whole process exited
3971 linux_nat_debug_printf ("accessing fd %d for pid %d got EOF",
3973 return TARGET_XFER_EOF
;
3978 return TARGET_XFER_OK
;
3982 /* Implement the to_xfer_partial target method using /proc/PID/mem.
3983 Because we can use a single read/write call, this can be much more
3984 efficient than banging away at PTRACE_PEEKTEXT. Also, unlike
3985 PTRACE_PEEKTEXT/PTRACE_POKETEXT, this works with running
3988 static enum target_xfer_status
3989 linux_proc_xfer_memory_partial (int pid
, gdb_byte
*readbuf
,
3990 const gdb_byte
*writebuf
, ULONGEST offset
,
3991 LONGEST len
, ULONGEST
*xfered_len
)
3993 auto iter
= proc_mem_file_map
.find (pid
);
3994 if (iter
== proc_mem_file_map
.end ())
3995 return TARGET_XFER_EOF
;
3997 int fd
= iter
->second
.fd ();
3999 return linux_proc_xfer_memory_partial_fd (fd
, pid
, readbuf
, writebuf
, offset
,
4003 /* Check whether /proc/pid/mem is writable in the current kernel, and
4004 return true if so. It wasn't writable before Linux 2.6.39, but
4005 there's no way to know whether the feature was backported to older
4006 kernels. So we check to see if it works. The result is cached,
4007 and this is guaranteed to be called once early during inferior
4008 startup, so that any warning is printed out consistently between
4009 GDB invocations. Note we don't call it during GDB startup instead
4010 though, because then we might warn with e.g. just "gdb --version"
4011 on sandboxed systems. See PR gdb/29907. */
4014 proc_mem_file_is_writable ()
4016 static gdb::optional
<bool> writable
;
4018 if (writable
.has_value ())
4021 writable
.emplace (false);
4023 /* We check whether /proc/pid/mem is writable by trying to write to
4024 one of our variables via /proc/self/mem. */
4026 int fd
= gdb_open_cloexec ("/proc/self/mem", O_RDWR
| O_LARGEFILE
, 0).release ();
4030 warning (_("opening /proc/self/mem file failed: %s (%d)"),
4031 safe_strerror (errno
), errno
);
4035 SCOPE_EXIT
{ close (fd
); };
4037 /* This is the variable we try to write to. Note OFFSET below. */
4038 volatile gdb_byte test_var
= 0;
4040 gdb_byte writebuf
[] = {0x55};
4041 ULONGEST offset
= (uintptr_t) &test_var
;
4042 ULONGEST xfered_len
;
4044 enum target_xfer_status res
4045 = linux_proc_xfer_memory_partial_fd (fd
, getpid (), nullptr, writebuf
,
4046 offset
, 1, &xfered_len
);
4048 if (res
== TARGET_XFER_OK
)
4050 gdb_assert (xfered_len
== 1);
4051 gdb_assert (test_var
== 0x55);
4059 /* Parse LINE as a signal set and add its set bits to SIGS. */
4062 add_line_to_sigset (const char *line
, sigset_t
*sigs
)
4064 int len
= strlen (line
) - 1;
4068 if (line
[len
] != '\n')
4069 error (_("Could not parse signal set: %s"), line
);
4077 if (*p
>= '0' && *p
<= '9')
4079 else if (*p
>= 'a' && *p
<= 'f')
4080 digit
= *p
- 'a' + 10;
4082 error (_("Could not parse signal set: %s"), line
);
4087 sigaddset (sigs
, signum
+ 1);
4089 sigaddset (sigs
, signum
+ 2);
4091 sigaddset (sigs
, signum
+ 3);
4093 sigaddset (sigs
, signum
+ 4);
4099 /* Find process PID's pending signals from /proc/pid/status and set
4103 linux_proc_pending_signals (int pid
, sigset_t
*pending
,
4104 sigset_t
*blocked
, sigset_t
*ignored
)
4106 char buffer
[PATH_MAX
], fname
[PATH_MAX
];
4108 sigemptyset (pending
);
4109 sigemptyset (blocked
);
4110 sigemptyset (ignored
);
4111 xsnprintf (fname
, sizeof fname
, "/proc/%d/status", pid
);
4112 gdb_file_up procfile
= gdb_fopen_cloexec (fname
, "r");
4113 if (procfile
== NULL
)
4114 error (_("Could not open %s"), fname
);
4116 while (fgets (buffer
, PATH_MAX
, procfile
.get ()) != NULL
)
4118 /* Normal queued signals are on the SigPnd line in the status
4119 file. However, 2.6 kernels also have a "shared" pending
4120 queue for delivering signals to a thread group, so check for
4123 Unfortunately some Red Hat kernels include the shared pending
4124 queue but not the ShdPnd status field. */
4126 if (startswith (buffer
, "SigPnd:\t"))
4127 add_line_to_sigset (buffer
+ 8, pending
);
4128 else if (startswith (buffer
, "ShdPnd:\t"))
4129 add_line_to_sigset (buffer
+ 8, pending
);
4130 else if (startswith (buffer
, "SigBlk:\t"))
4131 add_line_to_sigset (buffer
+ 8, blocked
);
4132 else if (startswith (buffer
, "SigIgn:\t"))
4133 add_line_to_sigset (buffer
+ 8, ignored
);
4137 static enum target_xfer_status
4138 linux_nat_xfer_osdata (enum target_object object
,
4139 const char *annex
, gdb_byte
*readbuf
,
4140 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
4141 ULONGEST
*xfered_len
)
4143 gdb_assert (object
== TARGET_OBJECT_OSDATA
);
4145 *xfered_len
= linux_common_xfer_osdata (annex
, readbuf
, offset
, len
);
4146 if (*xfered_len
== 0)
4147 return TARGET_XFER_EOF
;
4149 return TARGET_XFER_OK
;
4152 std::vector
<static_tracepoint_marker
>
4153 linux_nat_target::static_tracepoint_markers_by_strid (const char *strid
)
4155 char s
[IPA_CMD_BUF_SIZE
];
4156 int pid
= inferior_ptid
.pid ();
4157 std::vector
<static_tracepoint_marker
> markers
;
4159 ptid_t ptid
= ptid_t (pid
, 0);
4160 static_tracepoint_marker marker
;
4165 strcpy (s
, "qTfSTM");
4166 agent_run_command (pid
, s
, strlen (s
) + 1);
4169 SCOPE_EXIT
{ target_continue_no_signal (ptid
); };
4175 parse_static_tracepoint_marker_definition (p
, &p
, &marker
);
4177 if (strid
== NULL
|| marker
.str_id
== strid
)
4178 markers
.push_back (std::move (marker
));
4180 while (*p
++ == ','); /* comma-separated list */
4182 strcpy (s
, "qTsSTM");
4183 agent_run_command (pid
, s
, strlen (s
) + 1);
4190 /* target_can_async_p implementation. */
4193 linux_nat_target::can_async_p ()
4195 /* This flag should be checked in the common target.c code. */
4196 gdb_assert (target_async_permitted
);
4198 /* Otherwise, this targets is always able to support async mode. */
4203 linux_nat_target::supports_non_stop ()
4208 /* to_always_non_stop_p implementation. */
4211 linux_nat_target::always_non_stop_p ()
4217 linux_nat_target::supports_multi_process ()
4223 linux_nat_target::supports_disable_randomization ()
4228 /* SIGCHLD handler that serves two purposes: In non-stop/async mode,
4229 so we notice when any child changes state, and notify the
4230 event-loop; it allows us to use sigsuspend in linux_nat_wait_1
4231 above to wait for the arrival of a SIGCHLD. */
4234 sigchld_handler (int signo
)
4236 int old_errno
= errno
;
4238 if (debug_linux_nat
)
4239 gdb_stdlog
->write_async_safe ("sigchld\n", sizeof ("sigchld\n") - 1);
4241 if (signo
== SIGCHLD
)
4243 /* Let the event loop know that there are events to handle. */
4244 linux_nat_target::async_file_mark_if_open ();
4250 /* Callback registered with the target events file descriptor. */
4253 handle_target_event (int error
, gdb_client_data client_data
)
4255 inferior_event_handler (INF_REG_EVENT
);
4258 /* target_async implementation. */
4261 linux_nat_target::async (bool enable
)
4263 if (enable
== is_async_p ())
4266 /* Block child signals while we create/destroy the pipe, as their
4267 handler writes to it. */
4268 gdb::block_signals blocker
;
4272 if (!async_file_open ())
4273 internal_error ("creating event pipe failed.");
4275 add_file_handler (async_wait_fd (), handle_target_event
, NULL
,
4278 /* There may be pending events to handle. Tell the event loop
4284 delete_file_handler (async_wait_fd ());
4285 async_file_close ();
4289 /* Stop an LWP, and push a GDB_SIGNAL_0 stop status if no other
4293 linux_nat_stop_lwp (struct lwp_info
*lwp
)
4297 linux_nat_debug_printf ("running -> suspending %s",
4298 lwp
->ptid
.to_string ().c_str ());
4301 if (lwp
->last_resume_kind
== resume_stop
)
4303 linux_nat_debug_printf ("already stopping LWP %ld at GDB's request",
4308 stop_callback (lwp
);
4309 lwp
->last_resume_kind
= resume_stop
;
4313 /* Already known to be stopped; do nothing. */
4315 if (debug_linux_nat
)
4317 if (linux_target
->find_thread (lwp
->ptid
)->stop_requested
)
4318 linux_nat_debug_printf ("already stopped/stop_requested %s",
4319 lwp
->ptid
.to_string ().c_str ());
4321 linux_nat_debug_printf ("already stopped/no stop_requested yet %s",
4322 lwp
->ptid
.to_string ().c_str ());
4329 linux_nat_target::stop (ptid_t ptid
)
4331 LINUX_NAT_SCOPED_DEBUG_ENTER_EXIT
;
4332 iterate_over_lwps (ptid
, linux_nat_stop_lwp
);
4335 /* When requests are passed down from the linux-nat layer to the
4336 single threaded inf-ptrace layer, ptids of (lwpid,0,0) form are
4337 used. The address space pointer is stored in the inferior object,
4338 but the common code that is passed such ptid can't tell whether
4339 lwpid is a "main" process id or not (it assumes so). We reverse
4340 look up the "main" process id from the lwp here. */
4342 struct address_space
*
4343 linux_nat_target::thread_address_space (ptid_t ptid
)
4345 struct lwp_info
*lwp
;
4346 struct inferior
*inf
;
4349 if (ptid
.lwp () == 0)
4351 /* An (lwpid,0,0) ptid. Look up the lwp object to get at the
4353 lwp
= find_lwp_pid (ptid
);
4354 pid
= lwp
->ptid
.pid ();
4358 /* A (pid,lwpid,0) ptid. */
4362 inf
= find_inferior_pid (this, pid
);
4363 gdb_assert (inf
!= NULL
);
4367 /* Return the cached value of the processor core for thread PTID. */
4370 linux_nat_target::core_of_thread (ptid_t ptid
)
4372 struct lwp_info
*info
= find_lwp_pid (ptid
);
4379 /* Implementation of to_filesystem_is_local. */
4382 linux_nat_target::filesystem_is_local ()
4384 struct inferior
*inf
= current_inferior ();
4386 if (inf
->fake_pid_p
|| inf
->pid
== 0)
4389 return linux_ns_same (inf
->pid
, LINUX_NS_MNT
);
4392 /* Convert the INF argument passed to a to_fileio_* method
4393 to a process ID suitable for passing to its corresponding
4394 linux_mntns_* function. If INF is non-NULL then the
4395 caller is requesting the filesystem seen by INF. If INF
4396 is NULL then the caller is requesting the filesystem seen
4397 by the GDB. We fall back to GDB's filesystem in the case
4398 that INF is non-NULL but its PID is unknown. */
4401 linux_nat_fileio_pid_of (struct inferior
*inf
)
4403 if (inf
== NULL
|| inf
->fake_pid_p
|| inf
->pid
== 0)
4409 /* Implementation of to_fileio_open. */
4412 linux_nat_target::fileio_open (struct inferior
*inf
, const char *filename
,
4413 int flags
, int mode
, int warn_if_slow
,
4414 fileio_error
*target_errno
)
4420 if (fileio_to_host_openflags (flags
, &nat_flags
) == -1
4421 || fileio_to_host_mode (mode
, &nat_mode
) == -1)
4423 *target_errno
= FILEIO_EINVAL
;
4427 fd
= linux_mntns_open_cloexec (linux_nat_fileio_pid_of (inf
),
4428 filename
, nat_flags
, nat_mode
);
4430 *target_errno
= host_to_fileio_error (errno
);
4435 /* Implementation of to_fileio_readlink. */
4437 gdb::optional
<std::string
>
4438 linux_nat_target::fileio_readlink (struct inferior
*inf
, const char *filename
,
4439 fileio_error
*target_errno
)
4444 len
= linux_mntns_readlink (linux_nat_fileio_pid_of (inf
),
4445 filename
, buf
, sizeof (buf
));
4448 *target_errno
= host_to_fileio_error (errno
);
4452 return std::string (buf
, len
);
4455 /* Implementation of to_fileio_unlink. */
4458 linux_nat_target::fileio_unlink (struct inferior
*inf
, const char *filename
,
4459 fileio_error
*target_errno
)
4463 ret
= linux_mntns_unlink (linux_nat_fileio_pid_of (inf
),
4466 *target_errno
= host_to_fileio_error (errno
);
4471 /* Implementation of the to_thread_events method. */
4474 linux_nat_target::thread_events (int enable
)
4476 report_thread_events
= enable
;
4479 linux_nat_target::linux_nat_target ()
4481 /* We don't change the stratum; this target will sit at
4482 process_stratum and thread_db will set at thread_stratum. This
4483 is a little strange, since this is a multi-threaded-capable
4484 target, but we want to be on the stack below thread_db, and we
4485 also want to be used for single-threaded processes. */
4488 /* See linux-nat.h. */
4491 linux_nat_get_siginfo (ptid_t ptid
, siginfo_t
*siginfo
)
4493 int pid
= get_ptrace_pid (ptid
);
4494 return ptrace (PTRACE_GETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, siginfo
) == 0;
4497 /* See nat/linux-nat.h. */
4500 current_lwp_ptid (void)
4502 gdb_assert (inferior_ptid
.lwp_p ());
4503 return inferior_ptid
;
4506 /* Implement 'maintenance info linux-lwps'. Displays some basic
4507 information about all the current lwp_info objects. */
4510 maintenance_info_lwps (const char *arg
, int from_tty
)
4512 if (all_lwps ().size () == 0)
4514 gdb_printf ("No Linux LWPs\n");
4518 /* Start the width at 8 to match the column heading below, then
4519 figure out the widest ptid string. We'll use this to build our
4520 output table below. */
4521 size_t ptid_width
= 8;
4522 for (lwp_info
*lp
: all_lwps ())
4523 ptid_width
= std::max (ptid_width
, lp
->ptid
.to_string ().size ());
4525 /* Setup the table headers. */
4526 struct ui_out
*uiout
= current_uiout
;
4527 ui_out_emit_table
table_emitter (uiout
, 2, -1, "linux-lwps");
4528 uiout
->table_header (ptid_width
, ui_left
, "lwp-ptid", _("LWP Ptid"));
4529 uiout
->table_header (9, ui_left
, "thread-info", _("Thread ID"));
4530 uiout
->table_body ();
4532 /* Display one table row for each lwp_info. */
4533 for (lwp_info
*lp
: all_lwps ())
4535 ui_out_emit_tuple
tuple_emitter (uiout
, "lwp-entry");
4537 thread_info
*th
= linux_target
->find_thread (lp
->ptid
);
4539 uiout
->field_string ("lwp-ptid", lp
->ptid
.to_string ().c_str ());
4541 uiout
->field_string ("thread-info", "None");
4543 uiout
->field_string ("thread-info", print_full_thread_id (th
));
4545 uiout
->message ("\n");
4549 void _initialize_linux_nat ();
4551 _initialize_linux_nat ()
4553 add_setshow_boolean_cmd ("linux-nat", class_maintenance
,
4554 &debug_linux_nat
, _("\
4555 Set debugging of GNU/Linux native target."), _(" \
4556 Show debugging of GNU/Linux native target."), _(" \
4557 When on, print debug messages relating to the GNU/Linux native target."),
4559 show_debug_linux_nat
,
4560 &setdebuglist
, &showdebuglist
);
4562 add_setshow_boolean_cmd ("linux-namespaces", class_maintenance
,
4563 &debug_linux_namespaces
, _("\
4564 Set debugging of GNU/Linux namespaces module."), _("\
4565 Show debugging of GNU/Linux namespaces module."), _("\
4566 Enables printf debugging output."),
4569 &setdebuglist
, &showdebuglist
);
4571 /* Install a SIGCHLD handler. */
4572 sigchld_action
.sa_handler
= sigchld_handler
;
4573 sigemptyset (&sigchld_action
.sa_mask
);
4574 sigchld_action
.sa_flags
= SA_RESTART
;
4576 /* Make it the default. */
4577 sigaction (SIGCHLD
, &sigchld_action
, NULL
);
4579 /* Make sure we don't block SIGCHLD during a sigsuspend. */
4580 gdb_sigmask (SIG_SETMASK
, NULL
, &suspend_mask
);
4581 sigdelset (&suspend_mask
, SIGCHLD
);
4583 sigemptyset (&blocked_mask
);
4585 lwp_lwpid_htab_create ();
4587 add_cmd ("linux-lwps", class_maintenance
, maintenance_info_lwps
,
4588 _("List the Linux LWPS."), &maintenanceinfolist
);
4592 /* FIXME: kettenis/2000-08-26: The stuff on this page is specific to
4593 the GNU/Linux Threads library and therefore doesn't really belong
4596 /* NPTL reserves the first two RT signals, but does not provide any
4597 way for the debugger to query the signal numbers - fortunately
4598 they don't change. */
4599 static int lin_thread_signals
[] = { __SIGRTMIN
, __SIGRTMIN
+ 1 };
4601 /* See linux-nat.h. */
4604 lin_thread_get_thread_signal_num (void)
4606 return sizeof (lin_thread_signals
) / sizeof (lin_thread_signals
[0]);
4609 /* See linux-nat.h. */
4612 lin_thread_get_thread_signal (unsigned int i
)
4614 gdb_assert (i
< lin_thread_get_thread_signal_num ());
4615 return lin_thread_signals
[i
];