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. */
2005 /* All other LWPs are gone now. We'll have received a thread
2006 exit notification for all threads other the execing one.
2007 That one, if it wasn't the leader, just silently changes its
2008 tid to the tgid, and the previous leader vanishes. Since
2009 Linux 3.0, the former thread ID can be retrieved with
2010 PTRACE_GETEVENTMSG, but since we support older kernels, don't
2011 bother with it, and just walk the LWP list. Even with
2012 PTRACE_GETEVENTMSG, we'd still need to lookup the
2013 corresponding LWP object, and it would be an extra ptrace
2014 syscall, so this way may even be more efficient. */
2015 for (lwp_info
*other_lp
: all_lwps_safe ())
2016 if (other_lp
!= lp
&& other_lp
->ptid
.pid () == lp
->ptid
.pid ())
2017 exit_lwp (other_lp
);
2022 if (event
== PTRACE_EVENT_VFORK_DONE
)
2024 linux_nat_debug_printf
2025 ("Got PTRACE_EVENT_VFORK_DONE from LWP %ld",
2027 ourstatus
->set_vfork_done ();
2031 internal_error (_("unknown ptrace event %d"), event
);
2034 /* Suspend waiting for a signal. We're mostly interested in
2040 linux_nat_debug_printf ("about to sigsuspend");
2041 sigsuspend (&suspend_mask
);
2043 /* If the quit flag is set, it means that the user pressed Ctrl-C
2044 and we're debugging a process that is running on a separate
2045 terminal, so we must forward the Ctrl-C to the inferior. (If the
2046 inferior is sharing GDB's terminal, then the Ctrl-C reaches the
2047 inferior directly.) We must do this here because functions that
2048 need to block waiting for a signal loop forever until there's an
2049 event to report before returning back to the event loop. */
2050 if (!target_terminal::is_ours ())
2052 if (check_quit_flag ())
2053 target_pass_ctrlc ();
2057 /* Wait for LP to stop. Returns the wait status, or 0 if the LWP has
2061 wait_lwp (struct lwp_info
*lp
)
2065 int thread_dead
= 0;
2068 gdb_assert (!lp
->stopped
);
2069 gdb_assert (lp
->status
== 0);
2071 /* Make sure SIGCHLD is blocked for sigsuspend avoiding a race below. */
2072 block_child_signals (&prev_mask
);
2076 pid
= my_waitpid (lp
->ptid
.lwp (), &status
, __WALL
| WNOHANG
);
2077 if (pid
== -1 && errno
== ECHILD
)
2079 /* The thread has previously exited. We need to delete it
2080 now because if this was a non-leader thread execing, we
2081 won't get an exit event. See comments on exec events at
2082 the top of the file. */
2084 linux_nat_debug_printf ("%s vanished.",
2085 lp
->ptid
.to_string ().c_str ());
2090 /* Bugs 10970, 12702.
2091 Thread group leader may have exited in which case we'll lock up in
2092 waitpid if there are other threads, even if they are all zombies too.
2093 Basically, we're not supposed to use waitpid this way.
2094 tkill(pid,0) cannot be used here as it gets ESRCH for both
2095 for zombie and running processes.
2097 As a workaround, check if we're waiting for the thread group leader and
2098 if it's a zombie, and avoid calling waitpid if it is.
2100 This is racy, what if the tgl becomes a zombie right after we check?
2101 Therefore always use WNOHANG with sigsuspend - it is equivalent to
2102 waiting waitpid but linux_proc_pid_is_zombie is safe this way. */
2104 if (lp
->ptid
.pid () == lp
->ptid
.lwp ()
2105 && linux_proc_pid_is_zombie (lp
->ptid
.lwp ()))
2108 linux_nat_debug_printf ("Thread group leader %s vanished.",
2109 lp
->ptid
.to_string ().c_str ());
2113 /* Wait for next SIGCHLD and try again. This may let SIGCHLD handlers
2114 get invoked despite our caller had them intentionally blocked by
2115 block_child_signals. This is sensitive only to the loop of
2116 linux_nat_wait_1 and there if we get called my_waitpid gets called
2117 again before it gets to sigsuspend so we can safely let the handlers
2118 get executed here. */
2122 restore_child_signals_mask (&prev_mask
);
2126 gdb_assert (pid
== lp
->ptid
.lwp ());
2128 linux_nat_debug_printf ("waitpid %s received %s",
2129 lp
->ptid
.to_string ().c_str (),
2130 status_to_str (status
).c_str ());
2132 /* Check if the thread has exited. */
2133 if (WIFEXITED (status
) || WIFSIGNALED (status
))
2135 if (report_thread_events
2136 || lp
->ptid
.pid () == lp
->ptid
.lwp ())
2138 linux_nat_debug_printf ("LWP %d exited.", lp
->ptid
.pid ());
2140 /* If this is the leader exiting, it means the whole
2141 process is gone. Store the status to report to the
2142 core. Store it in lp->waitstatus, because lp->status
2143 would be ambiguous (W_EXITCODE(0,0) == 0). */
2144 lp
->waitstatus
= host_status_to_waitstatus (status
);
2149 linux_nat_debug_printf ("%s exited.",
2150 lp
->ptid
.to_string ().c_str ());
2160 gdb_assert (WIFSTOPPED (status
));
2163 if (lp
->must_set_ptrace_flags
)
2165 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2166 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
2168 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
2169 lp
->must_set_ptrace_flags
= 0;
2172 /* Handle GNU/Linux's syscall SIGTRAPs. */
2173 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
2175 /* No longer need the sysgood bit. The ptrace event ends up
2176 recorded in lp->waitstatus if we care for it. We can carry
2177 on handling the event like a regular SIGTRAP from here
2179 status
= W_STOPCODE (SIGTRAP
);
2180 if (linux_handle_syscall_trap (lp
, 1))
2181 return wait_lwp (lp
);
2185 /* Almost all other ptrace-stops are known to be outside of system
2186 calls, with further exceptions in linux_handle_extended_wait. */
2187 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
2190 /* Handle GNU/Linux's extended waitstatus for trace events. */
2191 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
2192 && linux_is_extended_waitstatus (status
))
2194 linux_nat_debug_printf ("Handling extended status 0x%06x", status
);
2195 linux_handle_extended_wait (lp
, status
);
2202 /* Send a SIGSTOP to LP. */
2205 stop_callback (struct lwp_info
*lp
)
2207 if (!lp
->stopped
&& !lp
->signalled
)
2211 linux_nat_debug_printf ("kill %s **<SIGSTOP>**",
2212 lp
->ptid
.to_string ().c_str ());
2215 ret
= kill_lwp (lp
->ptid
.lwp (), SIGSTOP
);
2216 linux_nat_debug_printf ("lwp kill %d %s", ret
,
2217 errno
? safe_strerror (errno
) : "ERRNO-OK");
2220 gdb_assert (lp
->status
== 0);
2226 /* Request a stop on LWP. */
2229 linux_stop_lwp (struct lwp_info
*lwp
)
2231 stop_callback (lwp
);
2234 /* See linux-nat.h */
2237 linux_stop_and_wait_all_lwps (void)
2239 /* Stop all LWP's ... */
2240 iterate_over_lwps (minus_one_ptid
, stop_callback
);
2242 /* ... and wait until all of them have reported back that
2243 they're no longer running. */
2244 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
2247 /* See linux-nat.h */
2250 linux_unstop_all_lwps (void)
2252 iterate_over_lwps (minus_one_ptid
,
2253 [] (struct lwp_info
*info
)
2255 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
2259 /* Return non-zero if LWP PID has a pending SIGINT. */
2262 linux_nat_has_pending_sigint (int pid
)
2264 sigset_t pending
, blocked
, ignored
;
2266 linux_proc_pending_signals (pid
, &pending
, &blocked
, &ignored
);
2268 if (sigismember (&pending
, SIGINT
)
2269 && !sigismember (&ignored
, SIGINT
))
2275 /* Set a flag in LP indicating that we should ignore its next SIGINT. */
2278 set_ignore_sigint (struct lwp_info
*lp
)
2280 /* If a thread has a pending SIGINT, consume it; otherwise, set a
2281 flag to consume the next one. */
2282 if (lp
->stopped
&& lp
->status
!= 0 && WIFSTOPPED (lp
->status
)
2283 && WSTOPSIG (lp
->status
) == SIGINT
)
2286 lp
->ignore_sigint
= 1;
2291 /* If LP does not have a SIGINT pending, then clear the ignore_sigint flag.
2292 This function is called after we know the LWP has stopped; if the LWP
2293 stopped before the expected SIGINT was delivered, then it will never have
2294 arrived. Also, if the signal was delivered to a shared queue and consumed
2295 by a different thread, it will never be delivered to this LWP. */
2298 maybe_clear_ignore_sigint (struct lwp_info
*lp
)
2300 if (!lp
->ignore_sigint
)
2303 if (!linux_nat_has_pending_sigint (lp
->ptid
.lwp ()))
2305 linux_nat_debug_printf ("Clearing bogus flag for %s",
2306 lp
->ptid
.to_string ().c_str ());
2307 lp
->ignore_sigint
= 0;
2311 /* Fetch the possible triggered data watchpoint info and store it in
2314 On some archs, like x86, that use debug registers to set
2315 watchpoints, it's possible that the way to know which watched
2316 address trapped, is to check the register that is used to select
2317 which address to watch. Problem is, between setting the watchpoint
2318 and reading back which data address trapped, the user may change
2319 the set of watchpoints, and, as a consequence, GDB changes the
2320 debug registers in the inferior. To avoid reading back a stale
2321 stopped-data-address when that happens, we cache in LP the fact
2322 that a watchpoint trapped, and the corresponding data address, as
2323 soon as we see LP stop with a SIGTRAP. If GDB changes the debug
2324 registers meanwhile, we have the cached data we can rely on. */
2327 check_stopped_by_watchpoint (struct lwp_info
*lp
)
2329 scoped_restore save_inferior_ptid
= make_scoped_restore (&inferior_ptid
);
2330 inferior_ptid
= lp
->ptid
;
2332 if (linux_target
->low_stopped_by_watchpoint ())
2334 lp
->stop_reason
= TARGET_STOPPED_BY_WATCHPOINT
;
2335 lp
->stopped_data_address_p
2336 = linux_target
->low_stopped_data_address (&lp
->stopped_data_address
);
2339 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2342 /* Returns true if the LWP had stopped for a watchpoint. */
2345 linux_nat_target::stopped_by_watchpoint ()
2347 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2349 gdb_assert (lp
!= NULL
);
2351 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2355 linux_nat_target::stopped_data_address (CORE_ADDR
*addr_p
)
2357 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2359 gdb_assert (lp
!= NULL
);
2361 *addr_p
= lp
->stopped_data_address
;
2363 return lp
->stopped_data_address_p
;
2366 /* Commonly any breakpoint / watchpoint generate only SIGTRAP. */
2369 linux_nat_target::low_status_is_event (int status
)
2371 return WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
;
2374 /* Wait until LP is stopped. */
2377 stop_wait_callback (struct lwp_info
*lp
)
2379 inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
2381 /* If this is a vfork parent, bail out, it is not going to report
2382 any SIGSTOP until the vfork is done with. */
2383 if (inf
->vfork_child
!= NULL
)
2390 status
= wait_lwp (lp
);
2394 if (lp
->ignore_sigint
&& WIFSTOPPED (status
)
2395 && WSTOPSIG (status
) == SIGINT
)
2397 lp
->ignore_sigint
= 0;
2400 ptrace (PTRACE_CONT
, lp
->ptid
.lwp (), 0, 0);
2402 linux_nat_debug_printf
2403 ("PTRACE_CONT %s, 0, 0 (%s) (discarding SIGINT)",
2404 lp
->ptid
.to_string ().c_str (),
2405 errno
? safe_strerror (errno
) : "OK");
2407 return stop_wait_callback (lp
);
2410 maybe_clear_ignore_sigint (lp
);
2412 if (WSTOPSIG (status
) != SIGSTOP
)
2414 /* The thread was stopped with a signal other than SIGSTOP. */
2416 linux_nat_debug_printf ("Pending event %s in %s",
2417 status_to_str ((int) status
).c_str (),
2418 lp
->ptid
.to_string ().c_str ());
2420 /* Save the sigtrap event. */
2421 lp
->status
= status
;
2422 gdb_assert (lp
->signalled
);
2423 save_stop_reason (lp
);
2427 /* We caught the SIGSTOP that we intended to catch. */
2429 linux_nat_debug_printf ("Expected SIGSTOP caught for %s.",
2430 lp
->ptid
.to_string ().c_str ());
2434 /* If we are waiting for this stop so we can report the thread
2435 stopped then we need to record this status. Otherwise, we can
2436 now discard this stop event. */
2437 if (lp
->last_resume_kind
== resume_stop
)
2439 lp
->status
= status
;
2440 save_stop_reason (lp
);
2448 /* Return non-zero if LP has a wait status pending. Discard the
2449 pending event and resume the LWP if the event that originally
2450 caused the stop became uninteresting. */
2453 status_callback (struct lwp_info
*lp
)
2455 /* Only report a pending wait status if we pretend that this has
2456 indeed been resumed. */
2460 if (!lwp_status_pending_p (lp
))
2463 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
2464 || lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2466 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2470 pc
= regcache_read_pc (regcache
);
2472 if (pc
!= lp
->stop_pc
)
2474 linux_nat_debug_printf ("PC of %s changed. was=%s, now=%s",
2475 lp
->ptid
.to_string ().c_str (),
2476 paddress (current_inferior ()->arch (),
2478 paddress (current_inferior ()->arch (), pc
));
2482 #if !USE_SIGTRAP_SIGINFO
2483 else if (!breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2485 linux_nat_debug_printf ("previous breakpoint of %s, at %s gone",
2486 lp
->ptid
.to_string ().c_str (),
2487 paddress (current_inferior ()->arch (),
2496 linux_nat_debug_printf ("pending event of %s cancelled.",
2497 lp
->ptid
.to_string ().c_str ());
2500 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2508 /* Count the LWP's that have had events. */
2511 count_events_callback (struct lwp_info
*lp
, int *count
)
2513 gdb_assert (count
!= NULL
);
2515 /* Select only resumed LWPs that have an event pending. */
2516 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2522 /* Select the LWP (if any) that is currently being single-stepped. */
2525 select_singlestep_lwp_callback (struct lwp_info
*lp
)
2527 if (lp
->last_resume_kind
== resume_step
2534 /* Returns true if LP has a status pending. */
2537 lwp_status_pending_p (struct lwp_info
*lp
)
2539 /* We check for lp->waitstatus in addition to lp->status, because we
2540 can have pending process exits recorded in lp->status and
2541 W_EXITCODE(0,0) happens to be 0. */
2542 return lp
->status
!= 0 || lp
->waitstatus
.kind () != TARGET_WAITKIND_IGNORE
;
2545 /* Select the Nth LWP that has had an event. */
2548 select_event_lwp_callback (struct lwp_info
*lp
, int *selector
)
2550 gdb_assert (selector
!= NULL
);
2552 /* Select only resumed LWPs that have an event pending. */
2553 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2554 if ((*selector
)-- == 0)
2560 /* Called when the LWP stopped for a signal/trap. If it stopped for a
2561 trap check what caused it (breakpoint, watchpoint, trace, etc.),
2562 and save the result in the LWP's stop_reason field. If it stopped
2563 for a breakpoint, decrement the PC if necessary on the lwp's
2567 save_stop_reason (struct lwp_info
*lp
)
2569 struct regcache
*regcache
;
2570 struct gdbarch
*gdbarch
;
2573 #if USE_SIGTRAP_SIGINFO
2577 gdb_assert (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
);
2578 gdb_assert (lp
->status
!= 0);
2580 if (!linux_target
->low_status_is_event (lp
->status
))
2583 inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
2584 if (inf
->starting_up
)
2587 regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2588 gdbarch
= regcache
->arch ();
2590 pc
= regcache_read_pc (regcache
);
2591 sw_bp_pc
= pc
- gdbarch_decr_pc_after_break (gdbarch
);
2593 #if USE_SIGTRAP_SIGINFO
2594 if (linux_nat_get_siginfo (lp
->ptid
, &siginfo
))
2596 if (siginfo
.si_signo
== SIGTRAP
)
2598 if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
)
2599 && GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2601 /* The si_code is ambiguous on this arch -- check debug
2603 if (!check_stopped_by_watchpoint (lp
))
2604 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2606 else if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
))
2608 /* If we determine the LWP stopped for a SW breakpoint,
2609 trust it. Particularly don't check watchpoint
2610 registers, because, at least on s390, we'd find
2611 stopped-by-watchpoint as long as there's a watchpoint
2613 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2615 else if (GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2617 /* This can indicate either a hardware breakpoint or
2618 hardware watchpoint. Check debug registers. */
2619 if (!check_stopped_by_watchpoint (lp
))
2620 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2622 else if (siginfo
.si_code
== TRAP_TRACE
)
2624 linux_nat_debug_printf ("%s stopped by trace",
2625 lp
->ptid
.to_string ().c_str ());
2627 /* We may have single stepped an instruction that
2628 triggered a watchpoint. In that case, on some
2629 architectures (such as x86), instead of TRAP_HWBKPT,
2630 si_code indicates TRAP_TRACE, and we need to check
2631 the debug registers separately. */
2632 check_stopped_by_watchpoint (lp
);
2637 if ((!lp
->step
|| lp
->stop_pc
== sw_bp_pc
)
2638 && software_breakpoint_inserted_here_p (regcache
->aspace (),
2641 /* The LWP was either continued, or stepped a software
2642 breakpoint instruction. */
2643 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2646 if (hardware_breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2647 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2649 if (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
)
2650 check_stopped_by_watchpoint (lp
);
2653 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
)
2655 linux_nat_debug_printf ("%s stopped by software breakpoint",
2656 lp
->ptid
.to_string ().c_str ());
2658 /* Back up the PC if necessary. */
2660 regcache_write_pc (regcache
, sw_bp_pc
);
2662 /* Update this so we record the correct stop PC below. */
2665 else if (lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2667 linux_nat_debug_printf ("%s stopped by hardware breakpoint",
2668 lp
->ptid
.to_string ().c_str ());
2670 else if (lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
)
2672 linux_nat_debug_printf ("%s stopped by hardware watchpoint",
2673 lp
->ptid
.to_string ().c_str ());
2680 /* Returns true if the LWP had stopped for a software breakpoint. */
2683 linux_nat_target::stopped_by_sw_breakpoint ()
2685 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2687 gdb_assert (lp
!= NULL
);
2689 return lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
;
2692 /* Implement the supports_stopped_by_sw_breakpoint method. */
2695 linux_nat_target::supports_stopped_by_sw_breakpoint ()
2697 return USE_SIGTRAP_SIGINFO
;
2700 /* Returns true if the LWP had stopped for a hardware
2701 breakpoint/watchpoint. */
2704 linux_nat_target::stopped_by_hw_breakpoint ()
2706 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2708 gdb_assert (lp
!= NULL
);
2710 return lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
;
2713 /* Implement the supports_stopped_by_hw_breakpoint method. */
2716 linux_nat_target::supports_stopped_by_hw_breakpoint ()
2718 return USE_SIGTRAP_SIGINFO
;
2721 /* Select one LWP out of those that have events pending. */
2724 select_event_lwp (ptid_t filter
, struct lwp_info
**orig_lp
, int *status
)
2727 int random_selector
;
2728 struct lwp_info
*event_lp
= NULL
;
2730 /* Record the wait status for the original LWP. */
2731 (*orig_lp
)->status
= *status
;
2733 /* In all-stop, give preference to the LWP that is being
2734 single-stepped. There will be at most one, and it will be the
2735 LWP that the core is most interested in. If we didn't do this,
2736 then we'd have to handle pending step SIGTRAPs somehow in case
2737 the core later continues the previously-stepped thread, as
2738 otherwise we'd report the pending SIGTRAP then, and the core, not
2739 having stepped the thread, wouldn't understand what the trap was
2740 for, and therefore would report it to the user as a random
2742 if (!target_is_non_stop_p ())
2744 event_lp
= iterate_over_lwps (filter
, select_singlestep_lwp_callback
);
2745 if (event_lp
!= NULL
)
2747 linux_nat_debug_printf ("Select single-step %s",
2748 event_lp
->ptid
.to_string ().c_str ());
2752 if (event_lp
== NULL
)
2754 /* Pick one at random, out of those which have had events. */
2756 /* First see how many events we have. */
2757 iterate_over_lwps (filter
,
2758 [&] (struct lwp_info
*info
)
2760 return count_events_callback (info
, &num_events
);
2762 gdb_assert (num_events
> 0);
2764 /* Now randomly pick a LWP out of those that have had
2766 random_selector
= (int)
2767 ((num_events
* (double) rand ()) / (RAND_MAX
+ 1.0));
2770 linux_nat_debug_printf ("Found %d events, selecting #%d",
2771 num_events
, random_selector
);
2774 = (iterate_over_lwps
2776 [&] (struct lwp_info
*info
)
2778 return select_event_lwp_callback (info
,
2783 if (event_lp
!= NULL
)
2785 /* Switch the event LWP. */
2786 *orig_lp
= event_lp
;
2787 *status
= event_lp
->status
;
2790 /* Flush the wait status for the event LWP. */
2791 (*orig_lp
)->status
= 0;
2794 /* Return non-zero if LP has been resumed. */
2797 resumed_callback (struct lwp_info
*lp
)
2802 /* Check if we should go on and pass this event to common code.
2804 If so, save the status to the lwp_info structure associated to LWPID. */
2807 linux_nat_filter_event (int lwpid
, int status
)
2809 struct lwp_info
*lp
;
2810 int event
= linux_ptrace_get_extended_event (status
);
2812 lp
= find_lwp_pid (ptid_t (lwpid
));
2814 /* Check for events reported by anything not in our LWP list. */
2817 if (WIFSTOPPED (status
))
2819 if (WSTOPSIG (status
) == SIGTRAP
&& event
== PTRACE_EVENT_EXEC
)
2821 /* A non-leader thread exec'ed after we've seen the
2822 leader zombie, and removed it from our lists (in
2823 check_zombie_leaders). The non-leader thread changes
2824 its tid to the tgid. */
2825 linux_nat_debug_printf
2826 ("Re-adding thread group leader LWP %d after exec.",
2829 lp
= add_lwp (ptid_t (lwpid
, lwpid
));
2832 add_thread (linux_target
, lp
->ptid
);
2836 /* A process we are controlling has forked and the new
2837 child's stop was reported to us by the kernel. Save
2838 its PID and go back to waiting for the fork event to
2839 be reported - the stopped process might be returned
2840 from waitpid before or after the fork event is. */
2841 linux_nat_debug_printf
2842 ("Saving LWP %d status %s in stopped_pids list",
2843 lwpid
, status_to_str (status
).c_str ());
2844 add_to_pid_list (&stopped_pids
, lwpid
, status
);
2849 /* Don't report an event for the exit of an LWP not in our
2850 list, i.e. not part of any inferior we're debugging.
2851 This can happen if we detach from a program we originally
2852 forked and then it exits. However, note that we may have
2853 earlier deleted a leader of an inferior we're debugging,
2854 in check_zombie_leaders. Re-add it back here if so. */
2855 for (inferior
*inf
: all_inferiors (linux_target
))
2857 if (inf
->pid
== lwpid
)
2859 linux_nat_debug_printf
2860 ("Re-adding thread group leader LWP %d after exit.",
2863 lp
= add_lwp (ptid_t (lwpid
, lwpid
));
2865 add_thread (linux_target
, lp
->ptid
);
2875 /* This LWP is stopped now. (And if dead, this prevents it from
2876 ever being continued.) */
2879 if (WIFSTOPPED (status
) && lp
->must_set_ptrace_flags
)
2881 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2882 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
2884 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
2885 lp
->must_set_ptrace_flags
= 0;
2888 /* Handle GNU/Linux's syscall SIGTRAPs. */
2889 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
2891 /* No longer need the sysgood bit. The ptrace event ends up
2892 recorded in lp->waitstatus if we care for it. We can carry
2893 on handling the event like a regular SIGTRAP from here
2895 status
= W_STOPCODE (SIGTRAP
);
2896 if (linux_handle_syscall_trap (lp
, 0))
2901 /* Almost all other ptrace-stops are known to be outside of system
2902 calls, with further exceptions in linux_handle_extended_wait. */
2903 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
2906 /* Handle GNU/Linux's extended waitstatus for trace events. */
2907 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
2908 && linux_is_extended_waitstatus (status
))
2910 linux_nat_debug_printf ("Handling extended status 0x%06x", status
);
2912 if (linux_handle_extended_wait (lp
, status
))
2916 /* Check if the thread has exited. */
2917 if (WIFEXITED (status
) || WIFSIGNALED (status
))
2919 if (!report_thread_events
&& !is_leader (lp
))
2921 linux_nat_debug_printf ("%s exited.",
2922 lp
->ptid
.to_string ().c_str ());
2924 /* If this was not the leader exiting, then the exit signal
2925 was not the end of the debugged application and should be
2931 /* Note that even if the leader was ptrace-stopped, it can still
2932 exit, if e.g., some other thread brings down the whole
2933 process (calls `exit'). So don't assert that the lwp is
2935 linux_nat_debug_printf ("LWP %ld exited (resumed=%d)",
2936 lp
->ptid
.lwp (), lp
->resumed
);
2938 /* Dead LWP's aren't expected to reported a pending sigstop. */
2941 /* Store the pending event in the waitstatus, because
2942 W_EXITCODE(0,0) == 0. */
2943 lp
->waitstatus
= host_status_to_waitstatus (status
);
2947 /* Make sure we don't report a SIGSTOP that we sent ourselves in
2948 an attempt to stop an LWP. */
2950 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGSTOP
)
2954 if (lp
->last_resume_kind
== resume_stop
)
2956 linux_nat_debug_printf ("resume_stop SIGSTOP caught for %s.",
2957 lp
->ptid
.to_string ().c_str ());
2961 /* This is a delayed SIGSTOP. Filter out the event. */
2963 linux_nat_debug_printf
2964 ("%s %s, 0, 0 (discard delayed SIGSTOP)",
2965 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
2966 lp
->ptid
.to_string ().c_str ());
2968 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2969 gdb_assert (lp
->resumed
);
2974 /* Make sure we don't report a SIGINT that we have already displayed
2975 for another thread. */
2976 if (lp
->ignore_sigint
2977 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGINT
)
2979 linux_nat_debug_printf ("Delayed SIGINT caught for %s.",
2980 lp
->ptid
.to_string ().c_str ());
2982 /* This is a delayed SIGINT. */
2983 lp
->ignore_sigint
= 0;
2985 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2986 linux_nat_debug_printf ("%s %s, 0, 0 (discard SIGINT)",
2987 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
2988 lp
->ptid
.to_string ().c_str ());
2989 gdb_assert (lp
->resumed
);
2991 /* Discard the event. */
2995 /* Don't report signals that GDB isn't interested in, such as
2996 signals that are neither printed nor stopped upon. Stopping all
2997 threads can be a bit time-consuming, so if we want decent
2998 performance with heavily multi-threaded programs, especially when
2999 they're using a high frequency timer, we'd better avoid it if we
3001 if (WIFSTOPPED (status
))
3003 enum gdb_signal signo
= gdb_signal_from_host (WSTOPSIG (status
));
3005 if (!target_is_non_stop_p ())
3007 /* Only do the below in all-stop, as we currently use SIGSTOP
3008 to implement target_stop (see linux_nat_stop) in
3010 if (signo
== GDB_SIGNAL_INT
&& signal_pass_state (signo
) == 0)
3012 /* If ^C/BREAK is typed at the tty/console, SIGINT gets
3013 forwarded to the entire process group, that is, all LWPs
3014 will receive it - unless they're using CLONE_THREAD to
3015 share signals. Since we only want to report it once, we
3016 mark it as ignored for all LWPs except this one. */
3017 iterate_over_lwps (ptid_t (lp
->ptid
.pid ()), set_ignore_sigint
);
3018 lp
->ignore_sigint
= 0;
3021 maybe_clear_ignore_sigint (lp
);
3024 /* When using hardware single-step, we need to report every signal.
3025 Otherwise, signals in pass_mask may be short-circuited
3026 except signals that might be caused by a breakpoint, or SIGSTOP
3027 if we sent the SIGSTOP and are waiting for it to arrive. */
3029 && WSTOPSIG (status
) && sigismember (&pass_mask
, WSTOPSIG (status
))
3030 && (WSTOPSIG (status
) != SIGSTOP
3031 || !linux_target
->find_thread (lp
->ptid
)->stop_requested
)
3032 && !linux_wstatus_maybe_breakpoint (status
))
3034 linux_resume_one_lwp (lp
, lp
->step
, signo
);
3035 linux_nat_debug_printf
3036 ("%s %s, %s (preempt 'handle')",
3037 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
3038 lp
->ptid
.to_string ().c_str (),
3039 (signo
!= GDB_SIGNAL_0
3040 ? strsignal (gdb_signal_to_host (signo
)) : "0"));
3045 /* An interesting event. */
3047 lp
->status
= status
;
3048 save_stop_reason (lp
);
3051 /* Detect zombie thread group leaders, and "exit" them. We can't reap
3052 their exits until all other threads in the group have exited. */
3055 check_zombie_leaders (void)
3057 for (inferior
*inf
: all_inferiors ())
3059 struct lwp_info
*leader_lp
;
3064 leader_lp
= find_lwp_pid (ptid_t (inf
->pid
));
3065 if (leader_lp
!= NULL
3066 /* Check if there are other threads in the group, as we may
3067 have raced with the inferior simply exiting. Note this
3068 isn't a watertight check. If the inferior is
3069 multi-threaded and is exiting, it may be we see the
3070 leader as zombie before we reap all the non-leader
3071 threads. See comments below. */
3072 && num_lwps (inf
->pid
) > 1
3073 && linux_proc_pid_is_zombie (inf
->pid
))
3075 /* A zombie leader in a multi-threaded program can mean one
3078 #1 - Only the leader exited, not the whole program, e.g.,
3079 with pthread_exit. Since we can't reap the leader's exit
3080 status until all other threads are gone and reaped too,
3081 we want to delete the zombie leader right away, as it
3082 can't be debugged, we can't read its registers, etc.
3083 This is the main reason we check for zombie leaders
3086 #2 - The whole thread-group/process exited (a group exit,
3087 via e.g. exit(3), and there is (or will be shortly) an
3088 exit reported for each thread in the process, and then
3089 finally an exit for the leader once the non-leaders are
3092 #3 - There are 3 or more threads in the group, and a
3093 thread other than the leader exec'd. See comments on
3094 exec events at the top of the file.
3096 Ideally we would never delete the leader for case #2.
3097 Instead, we want to collect the exit status of each
3098 non-leader thread, and then finally collect the exit
3099 status of the leader as normal and use its exit code as
3100 whole-process exit code. Unfortunately, there's no
3101 race-free way to distinguish cases #1 and #2. We can't
3102 assume the exit events for the non-leaders threads are
3103 already pending in the kernel, nor can we assume the
3104 non-leader threads are in zombie state already. Between
3105 the leader becoming zombie and the non-leaders exiting
3106 and becoming zombie themselves, there's a small time
3107 window, so such a check would be racy. Temporarily
3108 pausing all threads and checking to see if all threads
3109 exit or not before re-resuming them would work in the
3110 case that all threads are running right now, but it
3111 wouldn't work if some thread is currently already
3112 ptrace-stopped, e.g., due to scheduler-locking.
3114 So what we do is we delete the leader anyhow, and then
3115 later on when we see its exit status, we re-add it back.
3116 We also make sure that we only report a whole-process
3117 exit when we see the leader exiting, as opposed to when
3118 the last LWP in the LWP list exits, which can be a
3119 non-leader if we deleted the leader here. */
3120 linux_nat_debug_printf ("Thread group leader %d zombie "
3121 "(it exited, or another thread execd), "
3124 exit_lwp (leader_lp
);
3129 /* Convenience function that is called when the kernel reports an exit
3130 event. This decides whether to report the event to GDB as a
3131 process exit event, a thread exit event, or to suppress the
3135 filter_exit_event (struct lwp_info
*event_child
,
3136 struct target_waitstatus
*ourstatus
)
3138 ptid_t ptid
= event_child
->ptid
;
3140 if (!is_leader (event_child
))
3142 if (report_thread_events
)
3143 ourstatus
->set_thread_exited (0);
3145 ourstatus
->set_ignore ();
3147 exit_lwp (event_child
);
3154 linux_nat_wait_1 (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3155 target_wait_flags target_options
)
3157 LINUX_NAT_SCOPED_DEBUG_ENTER_EXIT
;
3160 enum resume_kind last_resume_kind
;
3161 struct lwp_info
*lp
;
3164 /* The first time we get here after starting a new inferior, we may
3165 not have added it to the LWP list yet - this is the earliest
3166 moment at which we know its PID. */
3167 if (ptid
.is_pid () && find_lwp_pid (ptid
) == nullptr)
3169 ptid_t
lwp_ptid (ptid
.pid (), ptid
.pid ());
3171 /* Upgrade the main thread's ptid. */
3172 thread_change_ptid (linux_target
, ptid
, lwp_ptid
);
3173 lp
= add_initial_lwp (lwp_ptid
);
3177 /* Make sure SIGCHLD is blocked until the sigsuspend below. */
3178 block_child_signals (&prev_mask
);
3180 /* First check if there is a LWP with a wait status pending. */
3181 lp
= iterate_over_lwps (ptid
, status_callback
);
3184 linux_nat_debug_printf ("Using pending wait status %s for %s.",
3185 pending_status_str (lp
).c_str (),
3186 lp
->ptid
.to_string ().c_str ());
3189 /* But if we don't find a pending event, we'll have to wait. Always
3190 pull all events out of the kernel. We'll randomly select an
3191 event LWP out of all that have events, to prevent starvation. */
3197 /* Always use -1 and WNOHANG, due to couple of a kernel/ptrace
3200 - If the thread group leader exits while other threads in the
3201 thread group still exist, waitpid(TGID, ...) hangs. That
3202 waitpid won't return an exit status until the other threads
3203 in the group are reaped.
3205 - When a non-leader thread execs, that thread just vanishes
3206 without reporting an exit (so we'd hang if we waited for it
3207 explicitly in that case). The exec event is reported to
3211 lwpid
= my_waitpid (-1, &status
, __WALL
| WNOHANG
);
3213 linux_nat_debug_printf ("waitpid(-1, ...) returned %d, %s",
3215 errno
? safe_strerror (errno
) : "ERRNO-OK");
3219 linux_nat_debug_printf ("waitpid %ld received %s",
3221 status_to_str (status
).c_str ());
3223 linux_nat_filter_event (lwpid
, status
);
3224 /* Retry until nothing comes out of waitpid. A single
3225 SIGCHLD can indicate more than one child stopped. */
3229 /* Now that we've pulled all events out of the kernel, resume
3230 LWPs that don't have an interesting event to report. */
3231 iterate_over_lwps (minus_one_ptid
,
3232 [] (struct lwp_info
*info
)
3234 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
3237 /* ... and find an LWP with a status to report to the core, if
3239 lp
= iterate_over_lwps (ptid
, status_callback
);
3243 /* Check for zombie thread group leaders. Those can't be reaped
3244 until all other threads in the thread group are. */
3245 check_zombie_leaders ();
3247 /* If there are no resumed children left, bail. We'd be stuck
3248 forever in the sigsuspend call below otherwise. */
3249 if (iterate_over_lwps (ptid
, resumed_callback
) == NULL
)
3251 linux_nat_debug_printf ("exit (no resumed LWP)");
3253 ourstatus
->set_no_resumed ();
3255 restore_child_signals_mask (&prev_mask
);
3256 return minus_one_ptid
;
3259 /* No interesting event to report to the core. */
3261 if (target_options
& TARGET_WNOHANG
)
3263 linux_nat_debug_printf ("no interesting events found");
3265 ourstatus
->set_ignore ();
3266 restore_child_signals_mask (&prev_mask
);
3267 return minus_one_ptid
;
3270 /* We shouldn't end up here unless we want to try again. */
3271 gdb_assert (lp
== NULL
);
3273 /* Block until we get an event reported with SIGCHLD. */
3279 status
= lp
->status
;
3282 if (!target_is_non_stop_p ())
3284 /* Now stop all other LWP's ... */
3285 iterate_over_lwps (minus_one_ptid
, stop_callback
);
3287 /* ... and wait until all of them have reported back that
3288 they're no longer running. */
3289 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
3292 /* If we're not waiting for a specific LWP, choose an event LWP from
3293 among those that have had events. Giving equal priority to all
3294 LWPs that have had events helps prevent starvation. */
3295 if (ptid
== minus_one_ptid
|| ptid
.is_pid ())
3296 select_event_lwp (ptid
, &lp
, &status
);
3298 gdb_assert (lp
!= NULL
);
3300 /* Now that we've selected our final event LWP, un-adjust its PC if
3301 it was a software breakpoint, and we can't reliably support the
3302 "stopped by software breakpoint" stop reason. */
3303 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
3304 && !USE_SIGTRAP_SIGINFO
)
3306 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3307 struct gdbarch
*gdbarch
= regcache
->arch ();
3308 int decr_pc
= gdbarch_decr_pc_after_break (gdbarch
);
3314 pc
= regcache_read_pc (regcache
);
3315 regcache_write_pc (regcache
, pc
+ decr_pc
);
3319 /* We'll need this to determine whether to report a SIGSTOP as
3320 GDB_SIGNAL_0. Need to take a copy because resume_clear_callback
3322 last_resume_kind
= lp
->last_resume_kind
;
3324 if (!target_is_non_stop_p ())
3326 /* In all-stop, from the core's perspective, all LWPs are now
3327 stopped until a new resume action is sent over. */
3328 iterate_over_lwps (minus_one_ptid
, resume_clear_callback
);
3332 resume_clear_callback (lp
);
3335 if (linux_target
->low_status_is_event (status
))
3337 linux_nat_debug_printf ("trap ptid is %s.",
3338 lp
->ptid
.to_string ().c_str ());
3341 if (lp
->waitstatus
.kind () != TARGET_WAITKIND_IGNORE
)
3343 *ourstatus
= lp
->waitstatus
;
3344 lp
->waitstatus
.set_ignore ();
3347 *ourstatus
= host_status_to_waitstatus (status
);
3349 linux_nat_debug_printf ("event found");
3351 restore_child_signals_mask (&prev_mask
);
3353 if (last_resume_kind
== resume_stop
3354 && ourstatus
->kind () == TARGET_WAITKIND_STOPPED
3355 && WSTOPSIG (status
) == SIGSTOP
)
3357 /* A thread that has been requested to stop by GDB with
3358 target_stop, and it stopped cleanly, so report as SIG0. The
3359 use of SIGSTOP is an implementation detail. */
3360 ourstatus
->set_stopped (GDB_SIGNAL_0
);
3363 if (ourstatus
->kind () == TARGET_WAITKIND_EXITED
3364 || ourstatus
->kind () == TARGET_WAITKIND_SIGNALLED
)
3367 lp
->core
= linux_common_core_of_thread (lp
->ptid
);
3369 if (ourstatus
->kind () == TARGET_WAITKIND_EXITED
)
3370 return filter_exit_event (lp
, ourstatus
);
3375 /* Resume LWPs that are currently stopped without any pending status
3376 to report, but are resumed from the core's perspective. */
3379 resume_stopped_resumed_lwps (struct lwp_info
*lp
, const ptid_t wait_ptid
)
3381 inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
3385 linux_nat_debug_printf ("NOT resuming LWP %s, not stopped",
3386 lp
->ptid
.to_string ().c_str ());
3388 else if (!lp
->resumed
)
3390 linux_nat_debug_printf ("NOT resuming LWP %s, not resumed",
3391 lp
->ptid
.to_string ().c_str ());
3393 else if (lwp_status_pending_p (lp
))
3395 linux_nat_debug_printf ("NOT resuming LWP %s, has pending status",
3396 lp
->ptid
.to_string ().c_str ());
3398 else if (inf
->vfork_child
!= nullptr)
3400 linux_nat_debug_printf ("NOT resuming LWP %s (vfork parent)",
3401 lp
->ptid
.to_string ().c_str ());
3405 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3406 struct gdbarch
*gdbarch
= regcache
->arch ();
3410 CORE_ADDR pc
= regcache_read_pc (regcache
);
3411 int leave_stopped
= 0;
3413 /* Don't bother if there's a breakpoint at PC that we'd hit
3414 immediately, and we're not waiting for this LWP. */
3415 if (!lp
->ptid
.matches (wait_ptid
))
3417 if (breakpoint_inserted_here_p (regcache
->aspace (), pc
))
3423 linux_nat_debug_printf
3424 ("resuming stopped-resumed LWP %s at %s: step=%d",
3425 lp
->ptid
.to_string ().c_str (), paddress (gdbarch
, pc
),
3428 linux_resume_one_lwp_throw (lp
, lp
->step
, GDB_SIGNAL_0
);
3431 catch (const gdb_exception_error
&ex
)
3433 if (!check_ptrace_stopped_lwp_gone (lp
))
3442 linux_nat_target::wait (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3443 target_wait_flags target_options
)
3445 LINUX_NAT_SCOPED_DEBUG_ENTER_EXIT
;
3449 linux_nat_debug_printf ("[%s], [%s]", ptid
.to_string ().c_str (),
3450 target_options_to_string (target_options
).c_str ());
3452 /* Flush the async file first. */
3453 if (target_is_async_p ())
3454 async_file_flush ();
3456 /* Resume LWPs that are currently stopped without any pending status
3457 to report, but are resumed from the core's perspective. LWPs get
3458 in this state if we find them stopping at a time we're not
3459 interested in reporting the event (target_wait on a
3460 specific_process, for example, see linux_nat_wait_1), and
3461 meanwhile the event became uninteresting. Don't bother resuming
3462 LWPs we're not going to wait for if they'd stop immediately. */
3463 if (target_is_non_stop_p ())
3464 iterate_over_lwps (minus_one_ptid
,
3465 [=] (struct lwp_info
*info
)
3467 return resume_stopped_resumed_lwps (info
, ptid
);
3470 event_ptid
= linux_nat_wait_1 (ptid
, ourstatus
, target_options
);
3472 /* If we requested any event, and something came out, assume there
3473 may be more. If we requested a specific lwp or process, also
3474 assume there may be more. */
3475 if (target_is_async_p ()
3476 && ((ourstatus
->kind () != TARGET_WAITKIND_IGNORE
3477 && ourstatus
->kind () != TARGET_WAITKIND_NO_RESUMED
)
3478 || ptid
!= minus_one_ptid
))
3487 kill_one_lwp (pid_t pid
)
3489 /* PTRACE_KILL may resume the inferior. Send SIGKILL first. */
3492 kill_lwp (pid
, SIGKILL
);
3494 if (debug_linux_nat
)
3496 int save_errno
= errno
;
3498 linux_nat_debug_printf
3499 ("kill (SIGKILL) %ld, 0, 0 (%s)", (long) pid
,
3500 save_errno
!= 0 ? safe_strerror (save_errno
) : "OK");
3503 /* Some kernels ignore even SIGKILL for processes under ptrace. */
3506 ptrace (PTRACE_KILL
, pid
, 0, 0);
3507 if (debug_linux_nat
)
3509 int save_errno
= errno
;
3511 linux_nat_debug_printf
3512 ("PTRACE_KILL %ld, 0, 0 (%s)", (long) pid
,
3513 save_errno
? safe_strerror (save_errno
) : "OK");
3517 /* Wait for an LWP to die. */
3520 kill_wait_one_lwp (pid_t pid
)
3524 /* We must make sure that there are no pending events (delayed
3525 SIGSTOPs, pending SIGTRAPs, etc.) to make sure the current
3526 program doesn't interfere with any following debugging session. */
3530 res
= my_waitpid (pid
, NULL
, __WALL
);
3531 if (res
!= (pid_t
) -1)
3533 linux_nat_debug_printf ("wait %ld received unknown.", (long) pid
);
3535 /* The Linux kernel sometimes fails to kill a thread
3536 completely after PTRACE_KILL; that goes from the stop
3537 point in do_fork out to the one in get_signal_to_deliver
3538 and waits again. So kill it again. */
3544 gdb_assert (res
== -1 && errno
== ECHILD
);
3547 /* Callback for iterate_over_lwps. */
3550 kill_callback (struct lwp_info
*lp
)
3552 kill_one_lwp (lp
->ptid
.lwp ());
3556 /* Callback for iterate_over_lwps. */
3559 kill_wait_callback (struct lwp_info
*lp
)
3561 kill_wait_one_lwp (lp
->ptid
.lwp ());
3565 /* Kill the fork children of any threads of inferior INF that are
3566 stopped at a fork event. */
3569 kill_unfollowed_fork_children (struct inferior
*inf
)
3571 for (thread_info
*thread
: inf
->non_exited_threads ())
3573 struct target_waitstatus
*ws
= &thread
->pending_follow
;
3575 if (ws
->kind () == TARGET_WAITKIND_FORKED
3576 || ws
->kind () == TARGET_WAITKIND_VFORKED
)
3578 ptid_t child_ptid
= ws
->child_ptid ();
3579 int child_pid
= child_ptid
.pid ();
3580 int child_lwp
= child_ptid
.lwp ();
3582 kill_one_lwp (child_lwp
);
3583 kill_wait_one_lwp (child_lwp
);
3585 /* Let the arch-specific native code know this process is
3587 linux_target
->low_forget_process (child_pid
);
3593 linux_nat_target::kill ()
3595 /* If we're stopped while forking and we haven't followed yet,
3596 kill the other task. We need to do this first because the
3597 parent will be sleeping if this is a vfork. */
3598 kill_unfollowed_fork_children (current_inferior ());
3600 if (forks_exist_p ())
3601 linux_fork_killall ();
3604 ptid_t ptid
= ptid_t (inferior_ptid
.pid ());
3606 /* Stop all threads before killing them, since ptrace requires
3607 that the thread is stopped to successfully PTRACE_KILL. */
3608 iterate_over_lwps (ptid
, stop_callback
);
3609 /* ... and wait until all of them have reported back that
3610 they're no longer running. */
3611 iterate_over_lwps (ptid
, stop_wait_callback
);
3613 /* Kill all LWP's ... */
3614 iterate_over_lwps (ptid
, kill_callback
);
3616 /* ... and wait until we've flushed all events. */
3617 iterate_over_lwps (ptid
, kill_wait_callback
);
3620 target_mourn_inferior (inferior_ptid
);
3624 linux_nat_target::mourn_inferior ()
3626 LINUX_NAT_SCOPED_DEBUG_ENTER_EXIT
;
3628 int pid
= inferior_ptid
.pid ();
3630 purge_lwp_list (pid
);
3632 close_proc_mem_file (pid
);
3634 if (! forks_exist_p ())
3635 /* Normal case, no other forks available. */
3636 inf_ptrace_target::mourn_inferior ();
3638 /* Multi-fork case. The current inferior_ptid has exited, but
3639 there are other viable forks to debug. Delete the exiting
3640 one and context-switch to the first available. */
3641 linux_fork_mourn_inferior ();
3643 /* Let the arch-specific native code know this process is gone. */
3644 linux_target
->low_forget_process (pid
);
3647 /* Convert a native/host siginfo object, into/from the siginfo in the
3648 layout of the inferiors' architecture. */
3651 siginfo_fixup (siginfo_t
*siginfo
, gdb_byte
*inf_siginfo
, int direction
)
3653 /* If the low target didn't do anything, then just do a straight
3655 if (!linux_target
->low_siginfo_fixup (siginfo
, inf_siginfo
, direction
))
3658 memcpy (siginfo
, inf_siginfo
, sizeof (siginfo_t
));
3660 memcpy (inf_siginfo
, siginfo
, sizeof (siginfo_t
));
3664 static enum target_xfer_status
3665 linux_xfer_siginfo (ptid_t ptid
, enum target_object object
,
3666 const char *annex
, gdb_byte
*readbuf
,
3667 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3668 ULONGEST
*xfered_len
)
3671 gdb_byte inf_siginfo
[sizeof (siginfo_t
)];
3673 gdb_assert (object
== TARGET_OBJECT_SIGNAL_INFO
);
3674 gdb_assert (readbuf
|| writebuf
);
3676 if (offset
> sizeof (siginfo
))
3677 return TARGET_XFER_E_IO
;
3679 if (!linux_nat_get_siginfo (ptid
, &siginfo
))
3680 return TARGET_XFER_E_IO
;
3682 /* When GDB is built as a 64-bit application, ptrace writes into
3683 SIGINFO an object with 64-bit layout. Since debugging a 32-bit
3684 inferior with a 64-bit GDB should look the same as debugging it
3685 with a 32-bit GDB, we need to convert it. GDB core always sees
3686 the converted layout, so any read/write will have to be done
3688 siginfo_fixup (&siginfo
, inf_siginfo
, 0);
3690 if (offset
+ len
> sizeof (siginfo
))
3691 len
= sizeof (siginfo
) - offset
;
3693 if (readbuf
!= NULL
)
3694 memcpy (readbuf
, inf_siginfo
+ offset
, len
);
3697 memcpy (inf_siginfo
+ offset
, writebuf
, len
);
3699 /* Convert back to ptrace layout before flushing it out. */
3700 siginfo_fixup (&siginfo
, inf_siginfo
, 1);
3702 int pid
= get_ptrace_pid (ptid
);
3704 ptrace (PTRACE_SETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, &siginfo
);
3706 return TARGET_XFER_E_IO
;
3710 return TARGET_XFER_OK
;
3713 static enum target_xfer_status
3714 linux_nat_xfer_osdata (enum target_object object
,
3715 const char *annex
, gdb_byte
*readbuf
,
3716 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3717 ULONGEST
*xfered_len
);
3719 static enum target_xfer_status
3720 linux_proc_xfer_memory_partial (int pid
, gdb_byte
*readbuf
,
3721 const gdb_byte
*writebuf
, ULONGEST offset
,
3722 LONGEST len
, ULONGEST
*xfered_len
);
3724 enum target_xfer_status
3725 linux_nat_target::xfer_partial (enum target_object object
,
3726 const char *annex
, gdb_byte
*readbuf
,
3727 const gdb_byte
*writebuf
,
3728 ULONGEST offset
, ULONGEST len
, ULONGEST
*xfered_len
)
3730 if (object
== TARGET_OBJECT_SIGNAL_INFO
)
3731 return linux_xfer_siginfo (inferior_ptid
, object
, annex
, readbuf
, writebuf
,
3732 offset
, len
, xfered_len
);
3734 /* The target is connected but no live inferior is selected. Pass
3735 this request down to a lower stratum (e.g., the executable
3737 if (object
== TARGET_OBJECT_MEMORY
&& inferior_ptid
== null_ptid
)
3738 return TARGET_XFER_EOF
;
3740 if (object
== TARGET_OBJECT_AUXV
)
3741 return memory_xfer_auxv (this, object
, annex
, readbuf
, writebuf
,
3742 offset
, len
, xfered_len
);
3744 if (object
== TARGET_OBJECT_OSDATA
)
3745 return linux_nat_xfer_osdata (object
, annex
, readbuf
, writebuf
,
3746 offset
, len
, xfered_len
);
3748 if (object
== TARGET_OBJECT_MEMORY
)
3750 /* GDB calculates all addresses in the largest possible address
3751 width. The address width must be masked before its final use
3752 by linux_proc_xfer_partial.
3754 Compare ADDR_BIT first to avoid a compiler warning on shift overflow. */
3755 int addr_bit
= gdbarch_addr_bit (current_inferior ()->arch ());
3757 if (addr_bit
< (sizeof (ULONGEST
) * HOST_CHAR_BIT
))
3758 offset
&= ((ULONGEST
) 1 << addr_bit
) - 1;
3760 /* If /proc/pid/mem is writable, don't fallback to ptrace. If
3761 the write via /proc/pid/mem fails because the inferior execed
3762 (and we haven't seen the exec event yet), a subsequent ptrace
3763 poke would incorrectly write memory to the post-exec address
3764 space, while the core was trying to write to the pre-exec
3766 if (proc_mem_file_is_writable ())
3767 return linux_proc_xfer_memory_partial (inferior_ptid
.pid (), readbuf
,
3768 writebuf
, offset
, len
,
3772 return inf_ptrace_target::xfer_partial (object
, annex
, readbuf
, writebuf
,
3773 offset
, len
, xfered_len
);
3777 linux_nat_target::thread_alive (ptid_t ptid
)
3779 /* As long as a PTID is in lwp list, consider it alive. */
3780 return find_lwp_pid (ptid
) != NULL
;
3783 /* Implement the to_update_thread_list target method for this
3787 linux_nat_target::update_thread_list ()
3789 /* We add/delete threads from the list as clone/exit events are
3790 processed, so just try deleting exited threads still in the
3792 delete_exited_threads ();
3794 /* Update the processor core that each lwp/thread was last seen
3796 for (lwp_info
*lwp
: all_lwps ())
3798 /* Avoid accessing /proc if the thread hasn't run since we last
3799 time we fetched the thread's core. Accessing /proc becomes
3800 noticeably expensive when we have thousands of LWPs. */
3801 if (lwp
->core
== -1)
3802 lwp
->core
= linux_common_core_of_thread (lwp
->ptid
);
3807 linux_nat_target::pid_to_str (ptid_t ptid
)
3810 && (ptid
.pid () != ptid
.lwp ()
3811 || num_lwps (ptid
.pid ()) > 1))
3812 return string_printf ("LWP %ld", ptid
.lwp ());
3814 return normal_pid_to_str (ptid
);
3818 linux_nat_target::thread_name (struct thread_info
*thr
)
3820 return linux_proc_tid_get_name (thr
->ptid
);
3823 /* Accepts an integer PID; Returns a string representing a file that
3824 can be opened to get the symbols for the child process. */
3827 linux_nat_target::pid_to_exec_file (int pid
)
3829 return linux_proc_pid_to_exec_file (pid
);
3832 /* Object representing an /proc/PID/mem open file. We keep one such
3833 file open per inferior.
3835 It might be tempting to think about only ever opening one file at
3836 most for all inferiors, closing/reopening the file as we access
3837 memory of different inferiors, to minimize number of file
3838 descriptors open, which can otherwise run into resource limits.
3839 However, that does not work correctly -- if the inferior execs and
3840 we haven't processed the exec event yet, and, we opened a
3841 /proc/PID/mem file, we will get a mem file accessing the post-exec
3842 address space, thinking we're opening it for the pre-exec address
3843 space. That is dangerous as we can poke memory (e.g. clearing
3844 breakpoints) in the post-exec memory by mistake, corrupting the
3845 inferior. For that reason, we open the mem file as early as
3846 possible, right after spawning, forking or attaching to the
3847 inferior, when the inferior is stopped and thus before it has a
3850 Note that after opening the file, even if the thread we opened it
3851 for subsequently exits, the open file is still usable for accessing
3852 memory. It's only when the whole process exits or execs that the
3853 file becomes invalid, at which point reads/writes return EOF. */
3858 proc_mem_file (ptid_t ptid
, int fd
)
3859 : m_ptid (ptid
), m_fd (fd
)
3861 gdb_assert (m_fd
!= -1);
3866 linux_nat_debug_printf ("closing fd %d for /proc/%d/task/%ld/mem",
3867 m_fd
, m_ptid
.pid (), m_ptid
.lwp ());
3871 DISABLE_COPY_AND_ASSIGN (proc_mem_file
);
3879 /* The LWP this file was opened for. Just for debugging
3883 /* The file descriptor. */
3887 /* The map between an inferior process id, and the open /proc/PID/mem
3888 file. This is stored in a map instead of in a per-inferior
3889 structure because we need to be able to access memory of processes
3890 which don't have a corresponding struct inferior object. E.g.,
3891 with "detach-on-fork on" (the default), and "follow-fork parent"
3892 (also default), we don't create an inferior for the fork child, but
3893 we still need to remove breakpoints from the fork child's
3895 static std::unordered_map
<int, proc_mem_file
> proc_mem_file_map
;
3897 /* Close the /proc/PID/mem file for PID. */
3900 close_proc_mem_file (pid_t pid
)
3902 proc_mem_file_map
.erase (pid
);
3905 /* Open the /proc/PID/mem file for the process (thread group) of PTID.
3906 We actually open /proc/PID/task/LWP/mem, as that's the LWP we know
3907 exists and is stopped right now. We prefer the
3908 /proc/PID/task/LWP/mem form over /proc/LWP/mem to avoid tid-reuse
3909 races, just in case this is ever called on an already-waited
3913 open_proc_mem_file (ptid_t ptid
)
3915 auto iter
= proc_mem_file_map
.find (ptid
.pid ());
3916 gdb_assert (iter
== proc_mem_file_map
.end ());
3919 xsnprintf (filename
, sizeof filename
,
3920 "/proc/%d/task/%ld/mem", ptid
.pid (), ptid
.lwp ());
3922 int fd
= gdb_open_cloexec (filename
, O_RDWR
| O_LARGEFILE
, 0).release ();
3926 warning (_("opening /proc/PID/mem file for lwp %d.%ld failed: %s (%d)"),
3927 ptid
.pid (), ptid
.lwp (),
3928 safe_strerror (errno
), errno
);
3932 proc_mem_file_map
.emplace (std::piecewise_construct
,
3933 std::forward_as_tuple (ptid
.pid ()),
3934 std::forward_as_tuple (ptid
, fd
));
3936 linux_nat_debug_printf ("opened fd %d for lwp %d.%ld",
3937 fd
, ptid
.pid (), ptid
.lwp ());
3940 /* Helper for linux_proc_xfer_memory_partial and
3941 proc_mem_file_is_writable. FD is the already opened /proc/pid/mem
3942 file, and PID is the pid of the corresponding process. The rest of
3943 the arguments are like linux_proc_xfer_memory_partial's. */
3945 static enum target_xfer_status
3946 linux_proc_xfer_memory_partial_fd (int fd
, int pid
,
3947 gdb_byte
*readbuf
, const gdb_byte
*writebuf
,
3948 ULONGEST offset
, LONGEST len
,
3949 ULONGEST
*xfered_len
)
3953 gdb_assert (fd
!= -1);
3955 /* Use pread64/pwrite64 if available, since they save a syscall and
3956 can handle 64-bit offsets even on 32-bit platforms (for instance,
3957 SPARC debugging a SPARC64 application). But only use them if the
3958 offset isn't so high that when cast to off_t it'd be negative, as
3959 seen on SPARC64. pread64/pwrite64 outright reject such offsets.
3962 if ((off_t
) offset
>= 0)
3963 ret
= (readbuf
!= nullptr
3964 ? pread64 (fd
, readbuf
, len
, offset
)
3965 : pwrite64 (fd
, writebuf
, len
, offset
));
3969 ret
= lseek (fd
, offset
, SEEK_SET
);
3971 ret
= (readbuf
!= nullptr
3972 ? read (fd
, readbuf
, len
)
3973 : write (fd
, writebuf
, len
));
3978 linux_nat_debug_printf ("accessing fd %d for pid %d failed: %s (%d)",
3979 fd
, pid
, safe_strerror (errno
), errno
);
3980 return TARGET_XFER_E_IO
;
3984 /* EOF means the address space is gone, the whole process exited
3986 linux_nat_debug_printf ("accessing fd %d for pid %d got EOF",
3988 return TARGET_XFER_EOF
;
3993 return TARGET_XFER_OK
;
3997 /* Implement the to_xfer_partial target method using /proc/PID/mem.
3998 Because we can use a single read/write call, this can be much more
3999 efficient than banging away at PTRACE_PEEKTEXT. Also, unlike
4000 PTRACE_PEEKTEXT/PTRACE_POKETEXT, this works with running
4003 static enum target_xfer_status
4004 linux_proc_xfer_memory_partial (int pid
, gdb_byte
*readbuf
,
4005 const gdb_byte
*writebuf
, ULONGEST offset
,
4006 LONGEST len
, ULONGEST
*xfered_len
)
4008 auto iter
= proc_mem_file_map
.find (pid
);
4009 if (iter
== proc_mem_file_map
.end ())
4010 return TARGET_XFER_EOF
;
4012 int fd
= iter
->second
.fd ();
4014 return linux_proc_xfer_memory_partial_fd (fd
, pid
, readbuf
, writebuf
, offset
,
4018 /* Check whether /proc/pid/mem is writable in the current kernel, and
4019 return true if so. It wasn't writable before Linux 2.6.39, but
4020 there's no way to know whether the feature was backported to older
4021 kernels. So we check to see if it works. The result is cached,
4022 and this is guaranteed to be called once early during inferior
4023 startup, so that any warning is printed out consistently between
4024 GDB invocations. Note we don't call it during GDB startup instead
4025 though, because then we might warn with e.g. just "gdb --version"
4026 on sandboxed systems. See PR gdb/29907. */
4029 proc_mem_file_is_writable ()
4031 static gdb::optional
<bool> writable
;
4033 if (writable
.has_value ())
4036 writable
.emplace (false);
4038 /* We check whether /proc/pid/mem is writable by trying to write to
4039 one of our variables via /proc/self/mem. */
4041 int fd
= gdb_open_cloexec ("/proc/self/mem", O_RDWR
| O_LARGEFILE
, 0).release ();
4045 warning (_("opening /proc/self/mem file failed: %s (%d)"),
4046 safe_strerror (errno
), errno
);
4050 SCOPE_EXIT
{ close (fd
); };
4052 /* This is the variable we try to write to. Note OFFSET below. */
4053 volatile gdb_byte test_var
= 0;
4055 gdb_byte writebuf
[] = {0x55};
4056 ULONGEST offset
= (uintptr_t) &test_var
;
4057 ULONGEST xfered_len
;
4059 enum target_xfer_status res
4060 = linux_proc_xfer_memory_partial_fd (fd
, getpid (), nullptr, writebuf
,
4061 offset
, 1, &xfered_len
);
4063 if (res
== TARGET_XFER_OK
)
4065 gdb_assert (xfered_len
== 1);
4066 gdb_assert (test_var
== 0x55);
4074 /* Parse LINE as a signal set and add its set bits to SIGS. */
4077 add_line_to_sigset (const char *line
, sigset_t
*sigs
)
4079 int len
= strlen (line
) - 1;
4083 if (line
[len
] != '\n')
4084 error (_("Could not parse signal set: %s"), line
);
4092 if (*p
>= '0' && *p
<= '9')
4094 else if (*p
>= 'a' && *p
<= 'f')
4095 digit
= *p
- 'a' + 10;
4097 error (_("Could not parse signal set: %s"), line
);
4102 sigaddset (sigs
, signum
+ 1);
4104 sigaddset (sigs
, signum
+ 2);
4106 sigaddset (sigs
, signum
+ 3);
4108 sigaddset (sigs
, signum
+ 4);
4114 /* Find process PID's pending signals from /proc/pid/status and set
4118 linux_proc_pending_signals (int pid
, sigset_t
*pending
,
4119 sigset_t
*blocked
, sigset_t
*ignored
)
4121 char buffer
[PATH_MAX
], fname
[PATH_MAX
];
4123 sigemptyset (pending
);
4124 sigemptyset (blocked
);
4125 sigemptyset (ignored
);
4126 xsnprintf (fname
, sizeof fname
, "/proc/%d/status", pid
);
4127 gdb_file_up procfile
= gdb_fopen_cloexec (fname
, "r");
4128 if (procfile
== NULL
)
4129 error (_("Could not open %s"), fname
);
4131 while (fgets (buffer
, PATH_MAX
, procfile
.get ()) != NULL
)
4133 /* Normal queued signals are on the SigPnd line in the status
4134 file. However, 2.6 kernels also have a "shared" pending
4135 queue for delivering signals to a thread group, so check for
4138 Unfortunately some Red Hat kernels include the shared pending
4139 queue but not the ShdPnd status field. */
4141 if (startswith (buffer
, "SigPnd:\t"))
4142 add_line_to_sigset (buffer
+ 8, pending
);
4143 else if (startswith (buffer
, "ShdPnd:\t"))
4144 add_line_to_sigset (buffer
+ 8, pending
);
4145 else if (startswith (buffer
, "SigBlk:\t"))
4146 add_line_to_sigset (buffer
+ 8, blocked
);
4147 else if (startswith (buffer
, "SigIgn:\t"))
4148 add_line_to_sigset (buffer
+ 8, ignored
);
4152 static enum target_xfer_status
4153 linux_nat_xfer_osdata (enum target_object object
,
4154 const char *annex
, gdb_byte
*readbuf
,
4155 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
4156 ULONGEST
*xfered_len
)
4158 gdb_assert (object
== TARGET_OBJECT_OSDATA
);
4160 *xfered_len
= linux_common_xfer_osdata (annex
, readbuf
, offset
, len
);
4161 if (*xfered_len
== 0)
4162 return TARGET_XFER_EOF
;
4164 return TARGET_XFER_OK
;
4167 std::vector
<static_tracepoint_marker
>
4168 linux_nat_target::static_tracepoint_markers_by_strid (const char *strid
)
4170 char s
[IPA_CMD_BUF_SIZE
];
4171 int pid
= inferior_ptid
.pid ();
4172 std::vector
<static_tracepoint_marker
> markers
;
4174 ptid_t ptid
= ptid_t (pid
, 0);
4175 static_tracepoint_marker marker
;
4180 strcpy (s
, "qTfSTM");
4181 agent_run_command (pid
, s
, strlen (s
) + 1);
4184 SCOPE_EXIT
{ target_continue_no_signal (ptid
); };
4190 parse_static_tracepoint_marker_definition (p
, &p
, &marker
);
4192 if (strid
== NULL
|| marker
.str_id
== strid
)
4193 markers
.push_back (std::move (marker
));
4195 while (*p
++ == ','); /* comma-separated list */
4197 strcpy (s
, "qTsSTM");
4198 agent_run_command (pid
, s
, strlen (s
) + 1);
4205 /* target_can_async_p implementation. */
4208 linux_nat_target::can_async_p ()
4210 /* This flag should be checked in the common target.c code. */
4211 gdb_assert (target_async_permitted
);
4213 /* Otherwise, this targets is always able to support async mode. */
4218 linux_nat_target::supports_non_stop ()
4223 /* to_always_non_stop_p implementation. */
4226 linux_nat_target::always_non_stop_p ()
4232 linux_nat_target::supports_multi_process ()
4238 linux_nat_target::supports_disable_randomization ()
4243 /* SIGCHLD handler that serves two purposes: In non-stop/async mode,
4244 so we notice when any child changes state, and notify the
4245 event-loop; it allows us to use sigsuspend in linux_nat_wait_1
4246 above to wait for the arrival of a SIGCHLD. */
4249 sigchld_handler (int signo
)
4251 int old_errno
= errno
;
4253 if (debug_linux_nat
)
4254 gdb_stdlog
->write_async_safe ("sigchld\n", sizeof ("sigchld\n") - 1);
4256 if (signo
== SIGCHLD
)
4258 /* Let the event loop know that there are events to handle. */
4259 linux_nat_target::async_file_mark_if_open ();
4265 /* Callback registered with the target events file descriptor. */
4268 handle_target_event (int error
, gdb_client_data client_data
)
4270 inferior_event_handler (INF_REG_EVENT
);
4273 /* target_async implementation. */
4276 linux_nat_target::async (bool enable
)
4278 if (enable
== is_async_p ())
4281 /* Block child signals while we create/destroy the pipe, as their
4282 handler writes to it. */
4283 gdb::block_signals blocker
;
4287 if (!async_file_open ())
4288 internal_error ("creating event pipe failed.");
4290 add_file_handler (async_wait_fd (), handle_target_event
, NULL
,
4293 /* There may be pending events to handle. Tell the event loop
4299 delete_file_handler (async_wait_fd ());
4300 async_file_close ();
4304 /* Stop an LWP, and push a GDB_SIGNAL_0 stop status if no other
4308 linux_nat_stop_lwp (struct lwp_info
*lwp
)
4312 linux_nat_debug_printf ("running -> suspending %s",
4313 lwp
->ptid
.to_string ().c_str ());
4316 if (lwp
->last_resume_kind
== resume_stop
)
4318 linux_nat_debug_printf ("already stopping LWP %ld at GDB's request",
4323 stop_callback (lwp
);
4324 lwp
->last_resume_kind
= resume_stop
;
4328 /* Already known to be stopped; do nothing. */
4330 if (debug_linux_nat
)
4332 if (linux_target
->find_thread (lwp
->ptid
)->stop_requested
)
4333 linux_nat_debug_printf ("already stopped/stop_requested %s",
4334 lwp
->ptid
.to_string ().c_str ());
4336 linux_nat_debug_printf ("already stopped/no stop_requested yet %s",
4337 lwp
->ptid
.to_string ().c_str ());
4344 linux_nat_target::stop (ptid_t ptid
)
4346 LINUX_NAT_SCOPED_DEBUG_ENTER_EXIT
;
4347 iterate_over_lwps (ptid
, linux_nat_stop_lwp
);
4350 /* When requests are passed down from the linux-nat layer to the
4351 single threaded inf-ptrace layer, ptids of (lwpid,0,0) form are
4352 used. The address space pointer is stored in the inferior object,
4353 but the common code that is passed such ptid can't tell whether
4354 lwpid is a "main" process id or not (it assumes so). We reverse
4355 look up the "main" process id from the lwp here. */
4357 struct address_space
*
4358 linux_nat_target::thread_address_space (ptid_t ptid
)
4360 struct lwp_info
*lwp
;
4361 struct inferior
*inf
;
4364 if (ptid
.lwp () == 0)
4366 /* An (lwpid,0,0) ptid. Look up the lwp object to get at the
4368 lwp
= find_lwp_pid (ptid
);
4369 pid
= lwp
->ptid
.pid ();
4373 /* A (pid,lwpid,0) ptid. */
4377 inf
= find_inferior_pid (this, pid
);
4378 gdb_assert (inf
!= NULL
);
4382 /* Return the cached value of the processor core for thread PTID. */
4385 linux_nat_target::core_of_thread (ptid_t ptid
)
4387 struct lwp_info
*info
= find_lwp_pid (ptid
);
4394 /* Implementation of to_filesystem_is_local. */
4397 linux_nat_target::filesystem_is_local ()
4399 struct inferior
*inf
= current_inferior ();
4401 if (inf
->fake_pid_p
|| inf
->pid
== 0)
4404 return linux_ns_same (inf
->pid
, LINUX_NS_MNT
);
4407 /* Convert the INF argument passed to a to_fileio_* method
4408 to a process ID suitable for passing to its corresponding
4409 linux_mntns_* function. If INF is non-NULL then the
4410 caller is requesting the filesystem seen by INF. If INF
4411 is NULL then the caller is requesting the filesystem seen
4412 by the GDB. We fall back to GDB's filesystem in the case
4413 that INF is non-NULL but its PID is unknown. */
4416 linux_nat_fileio_pid_of (struct inferior
*inf
)
4418 if (inf
== NULL
|| inf
->fake_pid_p
|| inf
->pid
== 0)
4424 /* Implementation of to_fileio_open. */
4427 linux_nat_target::fileio_open (struct inferior
*inf
, const char *filename
,
4428 int flags
, int mode
, int warn_if_slow
,
4429 fileio_error
*target_errno
)
4435 if (fileio_to_host_openflags (flags
, &nat_flags
) == -1
4436 || fileio_to_host_mode (mode
, &nat_mode
) == -1)
4438 *target_errno
= FILEIO_EINVAL
;
4442 fd
= linux_mntns_open_cloexec (linux_nat_fileio_pid_of (inf
),
4443 filename
, nat_flags
, nat_mode
);
4445 *target_errno
= host_to_fileio_error (errno
);
4450 /* Implementation of to_fileio_readlink. */
4452 gdb::optional
<std::string
>
4453 linux_nat_target::fileio_readlink (struct inferior
*inf
, const char *filename
,
4454 fileio_error
*target_errno
)
4459 len
= linux_mntns_readlink (linux_nat_fileio_pid_of (inf
),
4460 filename
, buf
, sizeof (buf
));
4463 *target_errno
= host_to_fileio_error (errno
);
4467 return std::string (buf
, len
);
4470 /* Implementation of to_fileio_unlink. */
4473 linux_nat_target::fileio_unlink (struct inferior
*inf
, const char *filename
,
4474 fileio_error
*target_errno
)
4478 ret
= linux_mntns_unlink (linux_nat_fileio_pid_of (inf
),
4481 *target_errno
= host_to_fileio_error (errno
);
4486 /* Implementation of the to_thread_events method. */
4489 linux_nat_target::thread_events (int enable
)
4491 report_thread_events
= enable
;
4494 linux_nat_target::linux_nat_target ()
4496 /* We don't change the stratum; this target will sit at
4497 process_stratum and thread_db will set at thread_stratum. This
4498 is a little strange, since this is a multi-threaded-capable
4499 target, but we want to be on the stack below thread_db, and we
4500 also want to be used for single-threaded processes. */
4503 /* See linux-nat.h. */
4506 linux_nat_get_siginfo (ptid_t ptid
, siginfo_t
*siginfo
)
4508 int pid
= get_ptrace_pid (ptid
);
4509 return ptrace (PTRACE_GETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, siginfo
) == 0;
4512 /* See nat/linux-nat.h. */
4515 current_lwp_ptid (void)
4517 gdb_assert (inferior_ptid
.lwp_p ());
4518 return inferior_ptid
;
4521 /* Implement 'maintenance info linux-lwps'. Displays some basic
4522 information about all the current lwp_info objects. */
4525 maintenance_info_lwps (const char *arg
, int from_tty
)
4527 if (all_lwps ().size () == 0)
4529 gdb_printf ("No Linux LWPs\n");
4533 /* Start the width at 8 to match the column heading below, then
4534 figure out the widest ptid string. We'll use this to build our
4535 output table below. */
4536 size_t ptid_width
= 8;
4537 for (lwp_info
*lp
: all_lwps ())
4538 ptid_width
= std::max (ptid_width
, lp
->ptid
.to_string ().size ());
4540 /* Setup the table headers. */
4541 struct ui_out
*uiout
= current_uiout
;
4542 ui_out_emit_table
table_emitter (uiout
, 2, -1, "linux-lwps");
4543 uiout
->table_header (ptid_width
, ui_left
, "lwp-ptid", _("LWP Ptid"));
4544 uiout
->table_header (9, ui_left
, "thread-info", _("Thread ID"));
4545 uiout
->table_body ();
4547 /* Display one table row for each lwp_info. */
4548 for (lwp_info
*lp
: all_lwps ())
4550 ui_out_emit_tuple
tuple_emitter (uiout
, "lwp-entry");
4552 thread_info
*th
= linux_target
->find_thread (lp
->ptid
);
4554 uiout
->field_string ("lwp-ptid", lp
->ptid
.to_string ().c_str ());
4556 uiout
->field_string ("thread-info", "None");
4558 uiout
->field_string ("thread-info", print_full_thread_id (th
));
4560 uiout
->message ("\n");
4564 void _initialize_linux_nat ();
4566 _initialize_linux_nat ()
4568 add_setshow_boolean_cmd ("linux-nat", class_maintenance
,
4569 &debug_linux_nat
, _("\
4570 Set debugging of GNU/Linux native target."), _(" \
4571 Show debugging of GNU/Linux native target."), _(" \
4572 When on, print debug messages relating to the GNU/Linux native target."),
4574 show_debug_linux_nat
,
4575 &setdebuglist
, &showdebuglist
);
4577 add_setshow_boolean_cmd ("linux-namespaces", class_maintenance
,
4578 &debug_linux_namespaces
, _("\
4579 Set debugging of GNU/Linux namespaces module."), _("\
4580 Show debugging of GNU/Linux namespaces module."), _("\
4581 Enables printf debugging output."),
4584 &setdebuglist
, &showdebuglist
);
4586 /* Install a SIGCHLD handler. */
4587 sigchld_action
.sa_handler
= sigchld_handler
;
4588 sigemptyset (&sigchld_action
.sa_mask
);
4589 sigchld_action
.sa_flags
= SA_RESTART
;
4591 /* Make it the default. */
4592 sigaction (SIGCHLD
, &sigchld_action
, NULL
);
4594 /* Make sure we don't block SIGCHLD during a sigsuspend. */
4595 gdb_sigmask (SIG_SETMASK
, NULL
, &suspend_mask
);
4596 sigdelset (&suspend_mask
, SIGCHLD
);
4598 sigemptyset (&blocked_mask
);
4600 lwp_lwpid_htab_create ();
4602 add_cmd ("linux-lwps", class_maintenance
, maintenance_info_lwps
,
4603 _("List the Linux LWPS."), &maintenanceinfolist
);
4607 /* FIXME: kettenis/2000-08-26: The stuff on this page is specific to
4608 the GNU/Linux Threads library and therefore doesn't really belong
4611 /* NPTL reserves the first two RT signals, but does not provide any
4612 way for the debugger to query the signal numbers - fortunately
4613 they don't change. */
4614 static int lin_thread_signals
[] = { __SIGRTMIN
, __SIGRTMIN
+ 1 };
4616 /* See linux-nat.h. */
4619 lin_thread_get_thread_signal_num (void)
4621 return sizeof (lin_thread_signals
) / sizeof (lin_thread_signals
[0]);
4624 /* See linux-nat.h. */
4627 lin_thread_get_thread_signal (unsigned int i
)
4629 gdb_assert (i
< lin_thread_get_thread_signal_num ());
4630 return lin_thread_signals
[i
];