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 /* If LP has a pending fork/vfork/clone status, return it. */
1285 static gdb::optional
<target_waitstatus
>
1286 get_pending_child_status (lwp_info
*lp
)
1288 LINUX_NAT_SCOPED_DEBUG_ENTER_EXIT
;
1290 linux_nat_debug_printf ("lwp %s (stopped = %d)",
1291 lp
->ptid
.to_string ().c_str (), lp
->stopped
);
1293 /* Check in lwp_info::status. */
1294 if (WIFSTOPPED (lp
->status
) && linux_is_extended_waitstatus (lp
->status
))
1296 int event
= linux_ptrace_get_extended_event (lp
->status
);
1298 if (event
== PTRACE_EVENT_FORK
1299 || event
== PTRACE_EVENT_VFORK
1300 || event
== PTRACE_EVENT_CLONE
)
1302 unsigned long child_pid
;
1303 int ret
= ptrace (PTRACE_GETEVENTMSG
, lp
->ptid
.lwp (), 0, &child_pid
);
1306 target_waitstatus ws
;
1308 if (event
== PTRACE_EVENT_FORK
)
1309 ws
.set_forked (ptid_t (child_pid
, child_pid
));
1310 else if (event
== PTRACE_EVENT_VFORK
)
1311 ws
.set_vforked (ptid_t (child_pid
, child_pid
));
1312 else if (event
== PTRACE_EVENT_CLONE
)
1313 ws
.set_thread_cloned (ptid_t (lp
->ptid
.pid (), child_pid
));
1315 gdb_assert_not_reached ("unhandled");
1321 perror_warning_with_name (_("Failed to retrieve event msg"));
1327 /* Check in lwp_info::waitstatus. */
1328 if (is_new_child_status (lp
->waitstatus
.kind ()))
1329 return lp
->waitstatus
;
1331 thread_info
*tp
= linux_target
->find_thread (lp
->ptid
);
1333 /* Check in thread_info::pending_waitstatus. */
1334 if (tp
->has_pending_waitstatus ()
1335 && is_new_child_status (tp
->pending_waitstatus ().kind ()))
1336 return tp
->pending_waitstatus ();
1338 /* Check in thread_info::pending_follow. */
1339 if (is_new_child_status (tp
->pending_follow
.kind ()))
1340 return tp
->pending_follow
;
1345 /* Detach from LP. If SIGNO_P is non-NULL, then it points to the
1346 signal number that should be passed to the LWP when detaching.
1347 Otherwise pass any pending signal the LWP may have, if any. */
1350 detach_one_lwp (struct lwp_info
*lp
, int *signo_p
)
1352 int lwpid
= lp
->ptid
.lwp ();
1355 /* If the lwp/thread we are about to detach has a pending fork/clone
1356 event, there is a process/thread GDB is attached to that the core
1357 of GDB doesn't know about. Detach from it. */
1359 gdb::optional
<target_waitstatus
> ws
= get_pending_child_status (lp
);
1360 if (ws
.has_value ())
1361 detach_one_pid (ws
->child_ptid ().lwp (), 0);
1363 /* If there is a pending SIGSTOP, get rid of it. */
1366 linux_nat_debug_printf ("Sending SIGCONT to %s",
1367 lp
->ptid
.to_string ().c_str ());
1369 kill_lwp (lwpid
, SIGCONT
);
1373 if (signo_p
== NULL
)
1375 /* Pass on any pending signal for this LWP. */
1376 signo
= get_detach_signal (lp
);
1381 linux_nat_debug_printf ("preparing to resume lwp %s (stopped = %d)",
1382 lp
->ptid
.to_string ().c_str (),
1385 /* Preparing to resume may try to write registers, and fail if the
1386 lwp is zombie. If that happens, ignore the error. We'll handle
1387 it below, when detach fails with ESRCH. */
1390 linux_target
->low_prepare_to_resume (lp
);
1392 catch (const gdb_exception_error
&ex
)
1394 if (!check_ptrace_stopped_lwp_gone (lp
))
1398 detach_one_pid (lwpid
, signo
);
1400 delete_lwp (lp
->ptid
);
1404 detach_callback (struct lwp_info
*lp
)
1406 /* We don't actually detach from the thread group leader just yet.
1407 If the thread group exits, we must reap the zombie clone lwps
1408 before we're able to reap the leader. */
1409 if (lp
->ptid
.lwp () != lp
->ptid
.pid ())
1410 detach_one_lwp (lp
, NULL
);
1415 linux_nat_target::detach (inferior
*inf
, int from_tty
)
1417 LINUX_NAT_SCOPED_DEBUG_ENTER_EXIT
;
1419 struct lwp_info
*main_lwp
;
1422 /* Don't unregister from the event loop, as there may be other
1423 inferiors running. */
1425 /* Stop all threads before detaching. ptrace requires that the
1426 thread is stopped to successfully detach. */
1427 iterate_over_lwps (ptid_t (pid
), stop_callback
);
1428 /* ... and wait until all of them have reported back that
1429 they're no longer running. */
1430 iterate_over_lwps (ptid_t (pid
), stop_wait_callback
);
1432 /* We can now safely remove breakpoints. We don't this in earlier
1433 in common code because this target doesn't currently support
1434 writing memory while the inferior is running. */
1435 remove_breakpoints_inf (current_inferior ());
1437 iterate_over_lwps (ptid_t (pid
), detach_callback
);
1439 /* We have detached from everything except the main thread now, so
1440 should only have one thread left. However, in non-stop mode the
1441 main thread might have exited, in which case we'll have no threads
1443 gdb_assert (num_lwps (pid
) == 1
1444 || (target_is_non_stop_p () && num_lwps (pid
) == 0));
1446 if (forks_exist_p ())
1448 /* Multi-fork case. The current inferior_ptid is being detached
1449 from, but there are other viable forks to debug. Detach from
1450 the current fork, and context-switch to the first
1452 linux_fork_detach (from_tty
);
1456 target_announce_detach (from_tty
);
1458 /* In non-stop mode it is possible that the main thread has exited,
1459 in which case we don't try to detach. */
1460 main_lwp
= find_lwp_pid (ptid_t (pid
));
1461 if (main_lwp
!= nullptr)
1463 /* Pass on any pending signal for the last LWP. */
1464 int signo
= get_detach_signal (main_lwp
);
1466 detach_one_lwp (main_lwp
, &signo
);
1469 gdb_assert (target_is_non_stop_p ());
1471 detach_success (inf
);
1474 close_proc_mem_file (pid
);
1477 /* Resume execution of the inferior process. If STEP is nonzero,
1478 single-step it. If SIGNAL is nonzero, give it that signal. */
1481 linux_resume_one_lwp_throw (struct lwp_info
*lp
, int step
,
1482 enum gdb_signal signo
)
1486 /* stop_pc doubles as the PC the LWP had when it was last resumed.
1487 We only presently need that if the LWP is stepped though (to
1488 handle the case of stepping a breakpoint instruction). */
1491 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
1493 lp
->stop_pc
= regcache_read_pc (regcache
);
1498 linux_target
->low_prepare_to_resume (lp
);
1499 linux_target
->low_resume (lp
->ptid
, step
, signo
);
1501 /* Successfully resumed. Clear state that no longer makes sense,
1502 and mark the LWP as running. Must not do this before resuming
1503 otherwise if that fails other code will be confused. E.g., we'd
1504 later try to stop the LWP and hang forever waiting for a stop
1505 status. Note that we must not throw after this is cleared,
1506 otherwise handle_zombie_lwp_error would get confused. */
1509 lp
->stop_reason
= TARGET_STOPPED_BY_NO_REASON
;
1510 registers_changed_ptid (linux_target
, lp
->ptid
);
1513 /* Called when we try to resume a stopped LWP and that errors out. If
1514 the LWP is no longer in ptrace-stopped state (meaning it's zombie,
1515 or about to become), discard the error, clear any pending status
1516 the LWP may have, and return true (we'll collect the exit status
1517 soon enough). Otherwise, return false. */
1520 check_ptrace_stopped_lwp_gone (struct lwp_info
*lp
)
1522 /* If we get an error after resuming the LWP successfully, we'd
1523 confuse !T state for the LWP being gone. */
1524 gdb_assert (lp
->stopped
);
1526 /* We can't just check whether the LWP is in 'Z (Zombie)' state,
1527 because even if ptrace failed with ESRCH, the tracee may be "not
1528 yet fully dead", but already refusing ptrace requests. In that
1529 case the tracee has 'R (Running)' state for a little bit
1530 (observed in Linux 3.18). See also the note on ESRCH in the
1531 ptrace(2) man page. Instead, check whether the LWP has any state
1532 other than ptrace-stopped. */
1534 /* Don't assume anything if /proc/PID/status can't be read. */
1535 if (linux_proc_pid_is_trace_stopped_nowarn (lp
->ptid
.lwp ()) == 0)
1537 lp
->stop_reason
= TARGET_STOPPED_BY_NO_REASON
;
1539 lp
->waitstatus
.set_ignore ();
1545 /* Like linux_resume_one_lwp_throw, but no error is thrown if the LWP
1546 disappears while we try to resume it. */
1549 linux_resume_one_lwp (struct lwp_info
*lp
, int step
, enum gdb_signal signo
)
1553 linux_resume_one_lwp_throw (lp
, step
, signo
);
1555 catch (const gdb_exception_error
&ex
)
1557 if (!check_ptrace_stopped_lwp_gone (lp
))
1565 resume_lwp (struct lwp_info
*lp
, int step
, enum gdb_signal signo
)
1569 struct inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
1571 if (inf
->vfork_child
!= NULL
)
1573 linux_nat_debug_printf ("Not resuming sibling %s (vfork parent)",
1574 lp
->ptid
.to_string ().c_str ());
1576 else if (!lwp_status_pending_p (lp
))
1578 linux_nat_debug_printf ("Resuming sibling %s, %s, %s",
1579 lp
->ptid
.to_string ().c_str (),
1580 (signo
!= GDB_SIGNAL_0
1581 ? strsignal (gdb_signal_to_host (signo
))
1583 step
? "step" : "resume");
1585 linux_resume_one_lwp (lp
, step
, signo
);
1589 linux_nat_debug_printf ("Not resuming sibling %s (has pending)",
1590 lp
->ptid
.to_string ().c_str ());
1594 linux_nat_debug_printf ("Not resuming sibling %s (not stopped)",
1595 lp
->ptid
.to_string ().c_str ());
1598 /* Callback for iterate_over_lwps. If LWP is EXCEPT, do nothing.
1599 Resume LWP with the last stop signal, if it is in pass state. */
1602 linux_nat_resume_callback (struct lwp_info
*lp
, struct lwp_info
*except
)
1604 enum gdb_signal signo
= GDB_SIGNAL_0
;
1611 struct thread_info
*thread
;
1613 thread
= linux_target
->find_thread (lp
->ptid
);
1616 signo
= thread
->stop_signal ();
1617 thread
->set_stop_signal (GDB_SIGNAL_0
);
1621 resume_lwp (lp
, 0, signo
);
1626 resume_clear_callback (struct lwp_info
*lp
)
1629 lp
->last_resume_kind
= resume_stop
;
1634 resume_set_callback (struct lwp_info
*lp
)
1637 lp
->last_resume_kind
= resume_continue
;
1642 linux_nat_target::resume (ptid_t scope_ptid
, int step
, enum gdb_signal signo
)
1644 struct lwp_info
*lp
;
1646 linux_nat_debug_printf ("Preparing to %s %s, %s, inferior_ptid %s",
1647 step
? "step" : "resume",
1648 scope_ptid
.to_string ().c_str (),
1649 (signo
!= GDB_SIGNAL_0
1650 ? strsignal (gdb_signal_to_host (signo
)) : "0"),
1651 inferior_ptid
.to_string ().c_str ());
1653 /* Mark the lwps we're resuming as resumed and update their
1654 last_resume_kind to resume_continue. */
1655 iterate_over_lwps (scope_ptid
, resume_set_callback
);
1657 lp
= find_lwp_pid (inferior_ptid
);
1658 gdb_assert (lp
!= NULL
);
1660 /* Remember if we're stepping. */
1661 lp
->last_resume_kind
= step
? resume_step
: resume_continue
;
1663 /* If we have a pending wait status for this thread, there is no
1664 point in resuming the process. But first make sure that
1665 linux_nat_wait won't preemptively handle the event - we
1666 should never take this short-circuit if we are going to
1667 leave LP running, since we have skipped resuming all the
1668 other threads. This bit of code needs to be synchronized
1669 with linux_nat_wait. */
1671 if (lp
->status
&& WIFSTOPPED (lp
->status
))
1674 && WSTOPSIG (lp
->status
)
1675 && sigismember (&pass_mask
, WSTOPSIG (lp
->status
)))
1677 linux_nat_debug_printf
1678 ("Not short circuiting for ignored status 0x%x", lp
->status
);
1680 /* FIXME: What should we do if we are supposed to continue
1681 this thread with a signal? */
1682 gdb_assert (signo
== GDB_SIGNAL_0
);
1683 signo
= gdb_signal_from_host (WSTOPSIG (lp
->status
));
1688 if (lwp_status_pending_p (lp
))
1690 /* FIXME: What should we do if we are supposed to continue
1691 this thread with a signal? */
1692 gdb_assert (signo
== GDB_SIGNAL_0
);
1694 linux_nat_debug_printf ("Short circuiting for status %s",
1695 pending_status_str (lp
).c_str ());
1697 if (target_can_async_p ())
1699 target_async (true);
1700 /* Tell the event loop we have something to process. */
1706 /* No use iterating unless we're resuming other threads. */
1707 if (scope_ptid
!= lp
->ptid
)
1708 iterate_over_lwps (scope_ptid
, [=] (struct lwp_info
*info
)
1710 return linux_nat_resume_callback (info
, lp
);
1713 linux_nat_debug_printf ("%s %s, %s (resume event thread)",
1714 step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
1715 lp
->ptid
.to_string ().c_str (),
1716 (signo
!= GDB_SIGNAL_0
1717 ? strsignal (gdb_signal_to_host (signo
)) : "0"));
1719 linux_resume_one_lwp (lp
, step
, signo
);
1722 /* Send a signal to an LWP. */
1725 kill_lwp (int lwpid
, int signo
)
1730 ret
= syscall (__NR_tkill
, lwpid
, signo
);
1731 if (errno
== ENOSYS
)
1733 /* If tkill fails, then we are not using nptl threads, a
1734 configuration we no longer support. */
1735 perror_with_name (("tkill"));
1740 /* Handle a GNU/Linux syscall trap wait response. If we see a syscall
1741 event, check if the core is interested in it: if not, ignore the
1742 event, and keep waiting; otherwise, we need to toggle the LWP's
1743 syscall entry/exit status, since the ptrace event itself doesn't
1744 indicate it, and report the trap to higher layers. */
1747 linux_handle_syscall_trap (struct lwp_info
*lp
, int stopping
)
1749 struct target_waitstatus
*ourstatus
= &lp
->waitstatus
;
1750 struct gdbarch
*gdbarch
= target_thread_architecture (lp
->ptid
);
1751 thread_info
*thread
= linux_target
->find_thread (lp
->ptid
);
1752 int syscall_number
= (int) gdbarch_get_syscall_number (gdbarch
, thread
);
1756 /* If we're stopping threads, there's a SIGSTOP pending, which
1757 makes it so that the LWP reports an immediate syscall return,
1758 followed by the SIGSTOP. Skip seeing that "return" using
1759 PTRACE_CONT directly, and let stop_wait_callback collect the
1760 SIGSTOP. Later when the thread is resumed, a new syscall
1761 entry event. If we didn't do this (and returned 0), we'd
1762 leave a syscall entry pending, and our caller, by using
1763 PTRACE_CONT to collect the SIGSTOP, skips the syscall return
1764 itself. Later, when the user re-resumes this LWP, we'd see
1765 another syscall entry event and we'd mistake it for a return.
1767 If stop_wait_callback didn't force the SIGSTOP out of the LWP
1768 (leaving immediately with LWP->signalled set, without issuing
1769 a PTRACE_CONT), it would still be problematic to leave this
1770 syscall enter pending, as later when the thread is resumed,
1771 it would then see the same syscall exit mentioned above,
1772 followed by the delayed SIGSTOP, while the syscall didn't
1773 actually get to execute. It seems it would be even more
1774 confusing to the user. */
1776 linux_nat_debug_printf
1777 ("ignoring syscall %d for LWP %ld (stopping threads), resuming with "
1778 "PTRACE_CONT for SIGSTOP", syscall_number
, lp
->ptid
.lwp ());
1780 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
1781 ptrace (PTRACE_CONT
, lp
->ptid
.lwp (), 0, 0);
1786 /* Always update the entry/return state, even if this particular
1787 syscall isn't interesting to the core now. In async mode,
1788 the user could install a new catchpoint for this syscall
1789 between syscall enter/return, and we'll need to know to
1790 report a syscall return if that happens. */
1791 lp
->syscall_state
= (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1792 ? TARGET_WAITKIND_SYSCALL_RETURN
1793 : TARGET_WAITKIND_SYSCALL_ENTRY
);
1795 if (catch_syscall_enabled ())
1797 if (catching_syscall_number (syscall_number
))
1799 /* Alright, an event to report. */
1800 if (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
)
1801 ourstatus
->set_syscall_entry (syscall_number
);
1802 else if (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_RETURN
)
1803 ourstatus
->set_syscall_return (syscall_number
);
1805 gdb_assert_not_reached ("unexpected syscall state");
1807 linux_nat_debug_printf
1808 ("stopping for %s of syscall %d for LWP %ld",
1809 (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1810 ? "entry" : "return"), syscall_number
, lp
->ptid
.lwp ());
1815 linux_nat_debug_printf
1816 ("ignoring %s of syscall %d for LWP %ld",
1817 (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1818 ? "entry" : "return"), syscall_number
, lp
->ptid
.lwp ());
1822 /* If we had been syscall tracing, and hence used PT_SYSCALL
1823 before on this LWP, it could happen that the user removes all
1824 syscall catchpoints before we get to process this event.
1825 There are two noteworthy issues here:
1827 - When stopped at a syscall entry event, resuming with
1828 PT_STEP still resumes executing the syscall and reports a
1831 - Only PT_SYSCALL catches syscall enters. If we last
1832 single-stepped this thread, then this event can't be a
1833 syscall enter. If we last single-stepped this thread, this
1834 has to be a syscall exit.
1836 The points above mean that the next resume, be it PT_STEP or
1837 PT_CONTINUE, can not trigger a syscall trace event. */
1838 linux_nat_debug_printf
1839 ("caught syscall event with no syscall catchpoints. %d for LWP %ld, "
1840 "ignoring", syscall_number
, lp
->ptid
.lwp ());
1841 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
1844 /* The core isn't interested in this event. For efficiency, avoid
1845 stopping all threads only to have the core resume them all again.
1846 Since we're not stopping threads, if we're still syscall tracing
1847 and not stepping, we can't use PTRACE_CONT here, as we'd miss any
1848 subsequent syscall. Simply resume using the inf-ptrace layer,
1849 which knows when to use PT_SYSCALL or PT_CONTINUE. */
1851 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
1858 linux_nat_target::follow_clone (ptid_t child_ptid
)
1860 lwp_info
*new_lp
= add_lwp (child_ptid
);
1861 new_lp
->stopped
= 1;
1863 /* If the thread_db layer is active, let it record the user
1864 level thread id and status, and add the thread to GDB's
1866 if (!thread_db_notice_clone (inferior_ptid
, new_lp
->ptid
))
1868 /* The process is not using thread_db. Add the LWP to
1870 add_thread (linux_target
, new_lp
->ptid
);
1873 /* We just created NEW_LP so it cannot yet contain STATUS. */
1874 gdb_assert (new_lp
->status
== 0);
1876 if (!pull_pid_from_list (&stopped_pids
, child_ptid
.lwp (), &new_lp
->status
))
1877 internal_error (_("no saved status for clone lwp"));
1879 if (WSTOPSIG (new_lp
->status
) != SIGSTOP
)
1881 /* This can happen if someone starts sending signals to
1882 the new thread before it gets a chance to run, which
1883 have a lower number than SIGSTOP (e.g. SIGUSR1).
1884 This is an unlikely case, and harder to handle for
1885 fork / vfork than for clone, so we do not try - but
1886 we handle it for clone events here. */
1888 new_lp
->signalled
= 1;
1890 /* Save the wait status to report later. */
1891 linux_nat_debug_printf
1892 ("waitpid of new LWP %ld, saving status %s",
1893 (long) new_lp
->ptid
.lwp (), status_to_str (new_lp
->status
).c_str ());
1899 if (report_thread_events
)
1900 new_lp
->waitstatus
.set_thread_created ();
1904 /* Handle a GNU/Linux extended wait response. If we see a clone
1905 event, we need to add the new LWP to our list (and not report the
1906 trap to higher layers). This function returns non-zero if the
1907 event should be ignored and we should wait again. If STOPPING is
1908 true, the new LWP remains stopped, otherwise it is continued. */
1911 linux_handle_extended_wait (struct lwp_info
*lp
, int status
)
1913 int pid
= lp
->ptid
.lwp ();
1914 struct target_waitstatus
*ourstatus
= &lp
->waitstatus
;
1915 int event
= linux_ptrace_get_extended_event (status
);
1917 /* All extended events we currently use are mid-syscall. Only
1918 PTRACE_EVENT_STOP is delivered more like a signal-stop, but
1919 you have to be using PTRACE_SEIZE to get that. */
1920 lp
->syscall_state
= TARGET_WAITKIND_SYSCALL_ENTRY
;
1922 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
1923 || event
== PTRACE_EVENT_CLONE
)
1925 unsigned long new_pid
;
1928 ptrace (PTRACE_GETEVENTMSG
, pid
, 0, &new_pid
);
1930 /* If we haven't already seen the new PID stop, wait for it now. */
1931 if (! pull_pid_from_list (&stopped_pids
, new_pid
, &status
))
1933 /* The new child has a pending SIGSTOP. We can't affect it until it
1934 hits the SIGSTOP, but we're already attached. */
1935 ret
= my_waitpid (new_pid
, &status
, __WALL
);
1937 perror_with_name (_("waiting for new child"));
1938 else if (ret
!= new_pid
)
1939 internal_error (_("wait returned unexpected PID %d"), ret
);
1940 else if (!WIFSTOPPED (status
))
1941 internal_error (_("wait returned unexpected status 0x%x"), status
);
1944 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
)
1946 open_proc_mem_file (ptid_t (new_pid
, new_pid
));
1948 /* The arch-specific native code may need to know about new
1949 forks even if those end up never mapped to an
1951 linux_target
->low_new_fork (lp
, new_pid
);
1953 else if (event
== PTRACE_EVENT_CLONE
)
1955 linux_target
->low_new_clone (lp
, new_pid
);
1958 if (event
== PTRACE_EVENT_FORK
1959 && linux_fork_checkpointing_p (lp
->ptid
.pid ()))
1961 /* Handle checkpointing by linux-fork.c here as a special
1962 case. We don't want the follow-fork-mode or 'catch fork'
1963 to interfere with this. */
1965 /* This won't actually modify the breakpoint list, but will
1966 physically remove the breakpoints from the child. */
1967 detach_breakpoints (ptid_t (new_pid
, new_pid
));
1969 /* Retain child fork in ptrace (stopped) state. */
1970 if (!find_fork_pid (new_pid
))
1973 /* Report as spurious, so that infrun doesn't want to follow
1974 this fork. We're actually doing an infcall in
1976 ourstatus
->set_spurious ();
1978 /* Report the stop to the core. */
1982 if (event
== PTRACE_EVENT_FORK
)
1983 ourstatus
->set_forked (ptid_t (new_pid
, new_pid
));
1984 else if (event
== PTRACE_EVENT_VFORK
)
1985 ourstatus
->set_vforked (ptid_t (new_pid
, new_pid
));
1986 else if (event
== PTRACE_EVENT_CLONE
)
1988 linux_nat_debug_printf
1989 ("Got clone event from LWP %d, new child is LWP %ld", pid
, new_pid
);
1991 /* Save the status again, we'll use it in follow_clone. */
1992 add_to_pid_list (&stopped_pids
, new_pid
, status
);
1994 ourstatus
->set_thread_cloned (ptid_t (lp
->ptid
.pid (), new_pid
));
2000 if (event
== PTRACE_EVENT_EXEC
)
2002 linux_nat_debug_printf ("Got exec event from LWP %ld", lp
->ptid
.lwp ());
2004 /* Close the previous /proc/PID/mem file for this inferior,
2005 which was using the address space which is now gone.
2006 Reading/writing from this file would return 0/EOF. */
2007 close_proc_mem_file (lp
->ptid
.pid ());
2009 /* Open a new file for the new address space. */
2010 open_proc_mem_file (lp
->ptid
);
2012 ourstatus
->set_execd
2013 (make_unique_xstrdup (linux_proc_pid_to_exec_file (pid
)));
2015 /* The thread that execed must have been resumed, but, when a
2016 thread execs, it changes its tid to the tgid, and the old
2017 tgid thread might have not been resumed. */
2020 /* All other LWPs are gone now. We'll have received a thread
2021 exit notification for all threads other the execing one.
2022 That one, if it wasn't the leader, just silently changes its
2023 tid to the tgid, and the previous leader vanishes. Since
2024 Linux 3.0, the former thread ID can be retrieved with
2025 PTRACE_GETEVENTMSG, but since we support older kernels, don't
2026 bother with it, and just walk the LWP list. Even with
2027 PTRACE_GETEVENTMSG, we'd still need to lookup the
2028 corresponding LWP object, and it would be an extra ptrace
2029 syscall, so this way may even be more efficient. */
2030 for (lwp_info
*other_lp
: all_lwps_safe ())
2031 if (other_lp
!= lp
&& other_lp
->ptid
.pid () == lp
->ptid
.pid ())
2032 exit_lwp (other_lp
);
2037 if (event
== PTRACE_EVENT_VFORK_DONE
)
2039 linux_nat_debug_printf
2040 ("Got PTRACE_EVENT_VFORK_DONE from LWP %ld",
2042 ourstatus
->set_vfork_done ();
2046 internal_error (_("unknown ptrace event %d"), event
);
2049 /* Suspend waiting for a signal. We're mostly interested in
2055 linux_nat_debug_printf ("about to sigsuspend");
2056 sigsuspend (&suspend_mask
);
2058 /* If the quit flag is set, it means that the user pressed Ctrl-C
2059 and we're debugging a process that is running on a separate
2060 terminal, so we must forward the Ctrl-C to the inferior. (If the
2061 inferior is sharing GDB's terminal, then the Ctrl-C reaches the
2062 inferior directly.) We must do this here because functions that
2063 need to block waiting for a signal loop forever until there's an
2064 event to report before returning back to the event loop. */
2065 if (!target_terminal::is_ours ())
2067 if (check_quit_flag ())
2068 target_pass_ctrlc ();
2072 /* Wait for LP to stop. Returns the wait status, or 0 if the LWP has
2076 wait_lwp (struct lwp_info
*lp
)
2080 int thread_dead
= 0;
2083 gdb_assert (!lp
->stopped
);
2084 gdb_assert (lp
->status
== 0);
2086 /* Make sure SIGCHLD is blocked for sigsuspend avoiding a race below. */
2087 block_child_signals (&prev_mask
);
2091 pid
= my_waitpid (lp
->ptid
.lwp (), &status
, __WALL
| WNOHANG
);
2092 if (pid
== -1 && errno
== ECHILD
)
2094 /* The thread has previously exited. We need to delete it
2095 now because if this was a non-leader thread execing, we
2096 won't get an exit event. See comments on exec events at
2097 the top of the file. */
2099 linux_nat_debug_printf ("%s vanished.",
2100 lp
->ptid
.to_string ().c_str ());
2105 /* Bugs 10970, 12702.
2106 Thread group leader may have exited in which case we'll lock up in
2107 waitpid if there are other threads, even if they are all zombies too.
2108 Basically, we're not supposed to use waitpid this way.
2109 tkill(pid,0) cannot be used here as it gets ESRCH for both
2110 for zombie and running processes.
2112 As a workaround, check if we're waiting for the thread group leader and
2113 if it's a zombie, and avoid calling waitpid if it is.
2115 This is racy, what if the tgl becomes a zombie right after we check?
2116 Therefore always use WNOHANG with sigsuspend - it is equivalent to
2117 waiting waitpid but linux_proc_pid_is_zombie is safe this way. */
2119 if (lp
->ptid
.pid () == lp
->ptid
.lwp ()
2120 && linux_proc_pid_is_zombie (lp
->ptid
.lwp ()))
2123 linux_nat_debug_printf ("Thread group leader %s vanished.",
2124 lp
->ptid
.to_string ().c_str ());
2128 /* Wait for next SIGCHLD and try again. This may let SIGCHLD handlers
2129 get invoked despite our caller had them intentionally blocked by
2130 block_child_signals. This is sensitive only to the loop of
2131 linux_nat_wait_1 and there if we get called my_waitpid gets called
2132 again before it gets to sigsuspend so we can safely let the handlers
2133 get executed here. */
2137 restore_child_signals_mask (&prev_mask
);
2141 gdb_assert (pid
== lp
->ptid
.lwp ());
2143 linux_nat_debug_printf ("waitpid %s received %s",
2144 lp
->ptid
.to_string ().c_str (),
2145 status_to_str (status
).c_str ());
2147 /* Check if the thread has exited. */
2148 if (WIFEXITED (status
) || WIFSIGNALED (status
))
2150 if (report_thread_events
2151 || lp
->ptid
.pid () == lp
->ptid
.lwp ())
2153 linux_nat_debug_printf ("LWP %d exited.", lp
->ptid
.pid ());
2155 /* If this is the leader exiting, it means the whole
2156 process is gone. Store the status to report to the
2157 core. Store it in lp->waitstatus, because lp->status
2158 would be ambiguous (W_EXITCODE(0,0) == 0). */
2159 lp
->waitstatus
= host_status_to_waitstatus (status
);
2164 linux_nat_debug_printf ("%s exited.",
2165 lp
->ptid
.to_string ().c_str ());
2175 gdb_assert (WIFSTOPPED (status
));
2178 if (lp
->must_set_ptrace_flags
)
2180 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2181 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
2183 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
2184 lp
->must_set_ptrace_flags
= 0;
2187 /* Handle GNU/Linux's syscall SIGTRAPs. */
2188 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
2190 /* No longer need the sysgood bit. The ptrace event ends up
2191 recorded in lp->waitstatus if we care for it. We can carry
2192 on handling the event like a regular SIGTRAP from here
2194 status
= W_STOPCODE (SIGTRAP
);
2195 if (linux_handle_syscall_trap (lp
, 1))
2196 return wait_lwp (lp
);
2200 /* Almost all other ptrace-stops are known to be outside of system
2201 calls, with further exceptions in linux_handle_extended_wait. */
2202 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
2205 /* Handle GNU/Linux's extended waitstatus for trace events. */
2206 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
2207 && linux_is_extended_waitstatus (status
))
2209 linux_nat_debug_printf ("Handling extended status 0x%06x", status
);
2210 linux_handle_extended_wait (lp
, status
);
2217 /* Send a SIGSTOP to LP. */
2220 stop_callback (struct lwp_info
*lp
)
2222 if (!lp
->stopped
&& !lp
->signalled
)
2226 linux_nat_debug_printf ("kill %s **<SIGSTOP>**",
2227 lp
->ptid
.to_string ().c_str ());
2230 ret
= kill_lwp (lp
->ptid
.lwp (), SIGSTOP
);
2231 linux_nat_debug_printf ("lwp kill %d %s", ret
,
2232 errno
? safe_strerror (errno
) : "ERRNO-OK");
2235 gdb_assert (lp
->status
== 0);
2241 /* Request a stop on LWP. */
2244 linux_stop_lwp (struct lwp_info
*lwp
)
2246 stop_callback (lwp
);
2249 /* See linux-nat.h */
2252 linux_stop_and_wait_all_lwps (void)
2254 /* Stop all LWP's ... */
2255 iterate_over_lwps (minus_one_ptid
, stop_callback
);
2257 /* ... and wait until all of them have reported back that
2258 they're no longer running. */
2259 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
2262 /* See linux-nat.h */
2265 linux_unstop_all_lwps (void)
2267 iterate_over_lwps (minus_one_ptid
,
2268 [] (struct lwp_info
*info
)
2270 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
2274 /* Return non-zero if LWP PID has a pending SIGINT. */
2277 linux_nat_has_pending_sigint (int pid
)
2279 sigset_t pending
, blocked
, ignored
;
2281 linux_proc_pending_signals (pid
, &pending
, &blocked
, &ignored
);
2283 if (sigismember (&pending
, SIGINT
)
2284 && !sigismember (&ignored
, SIGINT
))
2290 /* Set a flag in LP indicating that we should ignore its next SIGINT. */
2293 set_ignore_sigint (struct lwp_info
*lp
)
2295 /* If a thread has a pending SIGINT, consume it; otherwise, set a
2296 flag to consume the next one. */
2297 if (lp
->stopped
&& lp
->status
!= 0 && WIFSTOPPED (lp
->status
)
2298 && WSTOPSIG (lp
->status
) == SIGINT
)
2301 lp
->ignore_sigint
= 1;
2306 /* If LP does not have a SIGINT pending, then clear the ignore_sigint flag.
2307 This function is called after we know the LWP has stopped; if the LWP
2308 stopped before the expected SIGINT was delivered, then it will never have
2309 arrived. Also, if the signal was delivered to a shared queue and consumed
2310 by a different thread, it will never be delivered to this LWP. */
2313 maybe_clear_ignore_sigint (struct lwp_info
*lp
)
2315 if (!lp
->ignore_sigint
)
2318 if (!linux_nat_has_pending_sigint (lp
->ptid
.lwp ()))
2320 linux_nat_debug_printf ("Clearing bogus flag for %s",
2321 lp
->ptid
.to_string ().c_str ());
2322 lp
->ignore_sigint
= 0;
2326 /* Fetch the possible triggered data watchpoint info and store it in
2329 On some archs, like x86, that use debug registers to set
2330 watchpoints, it's possible that the way to know which watched
2331 address trapped, is to check the register that is used to select
2332 which address to watch. Problem is, between setting the watchpoint
2333 and reading back which data address trapped, the user may change
2334 the set of watchpoints, and, as a consequence, GDB changes the
2335 debug registers in the inferior. To avoid reading back a stale
2336 stopped-data-address when that happens, we cache in LP the fact
2337 that a watchpoint trapped, and the corresponding data address, as
2338 soon as we see LP stop with a SIGTRAP. If GDB changes the debug
2339 registers meanwhile, we have the cached data we can rely on. */
2342 check_stopped_by_watchpoint (struct lwp_info
*lp
)
2344 scoped_restore save_inferior_ptid
= make_scoped_restore (&inferior_ptid
);
2345 inferior_ptid
= lp
->ptid
;
2347 if (linux_target
->low_stopped_by_watchpoint ())
2349 lp
->stop_reason
= TARGET_STOPPED_BY_WATCHPOINT
;
2350 lp
->stopped_data_address_p
2351 = linux_target
->low_stopped_data_address (&lp
->stopped_data_address
);
2354 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2357 /* Returns true if the LWP had stopped for a watchpoint. */
2360 linux_nat_target::stopped_by_watchpoint ()
2362 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2364 gdb_assert (lp
!= NULL
);
2366 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2370 linux_nat_target::stopped_data_address (CORE_ADDR
*addr_p
)
2372 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2374 gdb_assert (lp
!= NULL
);
2376 *addr_p
= lp
->stopped_data_address
;
2378 return lp
->stopped_data_address_p
;
2381 /* Commonly any breakpoint / watchpoint generate only SIGTRAP. */
2384 linux_nat_target::low_status_is_event (int status
)
2386 return WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
;
2389 /* Wait until LP is stopped. */
2392 stop_wait_callback (struct lwp_info
*lp
)
2394 inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
2396 /* If this is a vfork parent, bail out, it is not going to report
2397 any SIGSTOP until the vfork is done with. */
2398 if (inf
->vfork_child
!= NULL
)
2405 status
= wait_lwp (lp
);
2409 if (lp
->ignore_sigint
&& WIFSTOPPED (status
)
2410 && WSTOPSIG (status
) == SIGINT
)
2412 lp
->ignore_sigint
= 0;
2415 ptrace (PTRACE_CONT
, lp
->ptid
.lwp (), 0, 0);
2417 linux_nat_debug_printf
2418 ("PTRACE_CONT %s, 0, 0 (%s) (discarding SIGINT)",
2419 lp
->ptid
.to_string ().c_str (),
2420 errno
? safe_strerror (errno
) : "OK");
2422 return stop_wait_callback (lp
);
2425 maybe_clear_ignore_sigint (lp
);
2427 if (WSTOPSIG (status
) != SIGSTOP
)
2429 /* The thread was stopped with a signal other than SIGSTOP. */
2431 linux_nat_debug_printf ("Pending event %s in %s",
2432 status_to_str ((int) status
).c_str (),
2433 lp
->ptid
.to_string ().c_str ());
2435 /* Save the sigtrap event. */
2436 lp
->status
= status
;
2437 gdb_assert (lp
->signalled
);
2438 save_stop_reason (lp
);
2442 /* We caught the SIGSTOP that we intended to catch. */
2444 linux_nat_debug_printf ("Expected SIGSTOP caught for %s.",
2445 lp
->ptid
.to_string ().c_str ());
2449 /* If we are waiting for this stop so we can report the thread
2450 stopped then we need to record this status. Otherwise, we can
2451 now discard this stop event. */
2452 if (lp
->last_resume_kind
== resume_stop
)
2454 lp
->status
= status
;
2455 save_stop_reason (lp
);
2463 /* Return non-zero if LP has a wait status pending. Discard the
2464 pending event and resume the LWP if the event that originally
2465 caused the stop became uninteresting. */
2468 status_callback (struct lwp_info
*lp
)
2470 /* Only report a pending wait status if we pretend that this has
2471 indeed been resumed. */
2475 if (!lwp_status_pending_p (lp
))
2478 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
2479 || lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2481 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2485 pc
= regcache_read_pc (regcache
);
2487 if (pc
!= lp
->stop_pc
)
2489 linux_nat_debug_printf ("PC of %s changed. was=%s, now=%s",
2490 lp
->ptid
.to_string ().c_str (),
2491 paddress (current_inferior ()->arch (),
2493 paddress (current_inferior ()->arch (), pc
));
2497 #if !USE_SIGTRAP_SIGINFO
2498 else if (!breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2500 linux_nat_debug_printf ("previous breakpoint of %s, at %s gone",
2501 lp
->ptid
.to_string ().c_str (),
2502 paddress (current_inferior ()->arch (),
2511 linux_nat_debug_printf ("pending event of %s cancelled.",
2512 lp
->ptid
.to_string ().c_str ());
2515 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2523 /* Count the LWP's that have had events. */
2526 count_events_callback (struct lwp_info
*lp
, int *count
)
2528 gdb_assert (count
!= NULL
);
2530 /* Select only resumed LWPs that have an event pending. */
2531 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2537 /* Select the LWP (if any) that is currently being single-stepped. */
2540 select_singlestep_lwp_callback (struct lwp_info
*lp
)
2542 if (lp
->last_resume_kind
== resume_step
2549 /* Returns true if LP has a status pending. */
2552 lwp_status_pending_p (struct lwp_info
*lp
)
2554 /* We check for lp->waitstatus in addition to lp->status, because we
2555 can have pending process exits recorded in lp->status and
2556 W_EXITCODE(0,0) happens to be 0. */
2557 return lp
->status
!= 0 || lp
->waitstatus
.kind () != TARGET_WAITKIND_IGNORE
;
2560 /* Select the Nth LWP that has had an event. */
2563 select_event_lwp_callback (struct lwp_info
*lp
, int *selector
)
2565 gdb_assert (selector
!= NULL
);
2567 /* Select only resumed LWPs that have an event pending. */
2568 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2569 if ((*selector
)-- == 0)
2575 /* Called when the LWP stopped for a signal/trap. If it stopped for a
2576 trap check what caused it (breakpoint, watchpoint, trace, etc.),
2577 and save the result in the LWP's stop_reason field. If it stopped
2578 for a breakpoint, decrement the PC if necessary on the lwp's
2582 save_stop_reason (struct lwp_info
*lp
)
2584 struct regcache
*regcache
;
2585 struct gdbarch
*gdbarch
;
2588 #if USE_SIGTRAP_SIGINFO
2592 gdb_assert (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
);
2593 gdb_assert (lp
->status
!= 0);
2595 if (!linux_target
->low_status_is_event (lp
->status
))
2598 inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
2599 if (inf
->starting_up
)
2602 regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2603 gdbarch
= regcache
->arch ();
2605 pc
= regcache_read_pc (regcache
);
2606 sw_bp_pc
= pc
- gdbarch_decr_pc_after_break (gdbarch
);
2608 #if USE_SIGTRAP_SIGINFO
2609 if (linux_nat_get_siginfo (lp
->ptid
, &siginfo
))
2611 if (siginfo
.si_signo
== SIGTRAP
)
2613 if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
)
2614 && GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2616 /* The si_code is ambiguous on this arch -- check debug
2618 if (!check_stopped_by_watchpoint (lp
))
2619 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2621 else if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
))
2623 /* If we determine the LWP stopped for a SW breakpoint,
2624 trust it. Particularly don't check watchpoint
2625 registers, because, at least on s390, we'd find
2626 stopped-by-watchpoint as long as there's a watchpoint
2628 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2630 else if (GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2632 /* This can indicate either a hardware breakpoint or
2633 hardware watchpoint. Check debug registers. */
2634 if (!check_stopped_by_watchpoint (lp
))
2635 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2637 else if (siginfo
.si_code
== TRAP_TRACE
)
2639 linux_nat_debug_printf ("%s stopped by trace",
2640 lp
->ptid
.to_string ().c_str ());
2642 /* We may have single stepped an instruction that
2643 triggered a watchpoint. In that case, on some
2644 architectures (such as x86), instead of TRAP_HWBKPT,
2645 si_code indicates TRAP_TRACE, and we need to check
2646 the debug registers separately. */
2647 check_stopped_by_watchpoint (lp
);
2652 if ((!lp
->step
|| lp
->stop_pc
== sw_bp_pc
)
2653 && software_breakpoint_inserted_here_p (regcache
->aspace (),
2656 /* The LWP was either continued, or stepped a software
2657 breakpoint instruction. */
2658 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2661 if (hardware_breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2662 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2664 if (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
)
2665 check_stopped_by_watchpoint (lp
);
2668 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
)
2670 linux_nat_debug_printf ("%s stopped by software breakpoint",
2671 lp
->ptid
.to_string ().c_str ());
2673 /* Back up the PC if necessary. */
2675 regcache_write_pc (regcache
, sw_bp_pc
);
2677 /* Update this so we record the correct stop PC below. */
2680 else if (lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2682 linux_nat_debug_printf ("%s stopped by hardware breakpoint",
2683 lp
->ptid
.to_string ().c_str ());
2685 else if (lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
)
2687 linux_nat_debug_printf ("%s stopped by hardware watchpoint",
2688 lp
->ptid
.to_string ().c_str ());
2695 /* Returns true if the LWP had stopped for a software breakpoint. */
2698 linux_nat_target::stopped_by_sw_breakpoint ()
2700 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2702 gdb_assert (lp
!= NULL
);
2704 return lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
;
2707 /* Implement the supports_stopped_by_sw_breakpoint method. */
2710 linux_nat_target::supports_stopped_by_sw_breakpoint ()
2712 return USE_SIGTRAP_SIGINFO
;
2715 /* Returns true if the LWP had stopped for a hardware
2716 breakpoint/watchpoint. */
2719 linux_nat_target::stopped_by_hw_breakpoint ()
2721 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2723 gdb_assert (lp
!= NULL
);
2725 return lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
;
2728 /* Implement the supports_stopped_by_hw_breakpoint method. */
2731 linux_nat_target::supports_stopped_by_hw_breakpoint ()
2733 return USE_SIGTRAP_SIGINFO
;
2736 /* Select one LWP out of those that have events pending. */
2739 select_event_lwp (ptid_t filter
, struct lwp_info
**orig_lp
, int *status
)
2742 int random_selector
;
2743 struct lwp_info
*event_lp
= NULL
;
2745 /* Record the wait status for the original LWP. */
2746 (*orig_lp
)->status
= *status
;
2748 /* In all-stop, give preference to the LWP that is being
2749 single-stepped. There will be at most one, and it will be the
2750 LWP that the core is most interested in. If we didn't do this,
2751 then we'd have to handle pending step SIGTRAPs somehow in case
2752 the core later continues the previously-stepped thread, as
2753 otherwise we'd report the pending SIGTRAP then, and the core, not
2754 having stepped the thread, wouldn't understand what the trap was
2755 for, and therefore would report it to the user as a random
2757 if (!target_is_non_stop_p ())
2759 event_lp
= iterate_over_lwps (filter
, select_singlestep_lwp_callback
);
2760 if (event_lp
!= NULL
)
2762 linux_nat_debug_printf ("Select single-step %s",
2763 event_lp
->ptid
.to_string ().c_str ());
2767 if (event_lp
== NULL
)
2769 /* Pick one at random, out of those which have had events. */
2771 /* First see how many events we have. */
2772 iterate_over_lwps (filter
,
2773 [&] (struct lwp_info
*info
)
2775 return count_events_callback (info
, &num_events
);
2777 gdb_assert (num_events
> 0);
2779 /* Now randomly pick a LWP out of those that have had
2781 random_selector
= (int)
2782 ((num_events
* (double) rand ()) / (RAND_MAX
+ 1.0));
2785 linux_nat_debug_printf ("Found %d events, selecting #%d",
2786 num_events
, random_selector
);
2789 = (iterate_over_lwps
2791 [&] (struct lwp_info
*info
)
2793 return select_event_lwp_callback (info
,
2798 if (event_lp
!= NULL
)
2800 /* Switch the event LWP. */
2801 *orig_lp
= event_lp
;
2802 *status
= event_lp
->status
;
2805 /* Flush the wait status for the event LWP. */
2806 (*orig_lp
)->status
= 0;
2809 /* Return non-zero if LP has been resumed. */
2812 resumed_callback (struct lwp_info
*lp
)
2817 /* Check if we should go on and pass this event to common code.
2819 If so, save the status to the lwp_info structure associated to LWPID. */
2822 linux_nat_filter_event (int lwpid
, int status
)
2824 struct lwp_info
*lp
;
2825 int event
= linux_ptrace_get_extended_event (status
);
2827 lp
= find_lwp_pid (ptid_t (lwpid
));
2829 /* Check for events reported by anything not in our LWP list. */
2832 if (WIFSTOPPED (status
))
2834 if (WSTOPSIG (status
) == SIGTRAP
&& event
== PTRACE_EVENT_EXEC
)
2836 /* A non-leader thread exec'ed after we've seen the
2837 leader zombie, and removed it from our lists (in
2838 check_zombie_leaders). The non-leader thread changes
2839 its tid to the tgid. */
2840 linux_nat_debug_printf
2841 ("Re-adding thread group leader LWP %d after exec.",
2844 lp
= add_lwp (ptid_t (lwpid
, lwpid
));
2847 add_thread (linux_target
, lp
->ptid
);
2851 /* A process we are controlling has forked and the new
2852 child's stop was reported to us by the kernel. Save
2853 its PID and go back to waiting for the fork event to
2854 be reported - the stopped process might be returned
2855 from waitpid before or after the fork event is. */
2856 linux_nat_debug_printf
2857 ("Saving LWP %d status %s in stopped_pids list",
2858 lwpid
, status_to_str (status
).c_str ());
2859 add_to_pid_list (&stopped_pids
, lwpid
, status
);
2864 /* Don't report an event for the exit of an LWP not in our
2865 list, i.e. not part of any inferior we're debugging.
2866 This can happen if we detach from a program we originally
2867 forked and then it exits. However, note that we may have
2868 earlier deleted a leader of an inferior we're debugging,
2869 in check_zombie_leaders. Re-add it back here if so. */
2870 for (inferior
*inf
: all_inferiors (linux_target
))
2872 if (inf
->pid
== lwpid
)
2874 linux_nat_debug_printf
2875 ("Re-adding thread group leader LWP %d after exit.",
2878 lp
= add_lwp (ptid_t (lwpid
, lwpid
));
2880 add_thread (linux_target
, lp
->ptid
);
2890 /* This LWP is stopped now. (And if dead, this prevents it from
2891 ever being continued.) */
2894 if (WIFSTOPPED (status
) && lp
->must_set_ptrace_flags
)
2896 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2897 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
2899 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
2900 lp
->must_set_ptrace_flags
= 0;
2903 /* Handle GNU/Linux's syscall SIGTRAPs. */
2904 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
2906 /* No longer need the sysgood bit. The ptrace event ends up
2907 recorded in lp->waitstatus if we care for it. We can carry
2908 on handling the event like a regular SIGTRAP from here
2910 status
= W_STOPCODE (SIGTRAP
);
2911 if (linux_handle_syscall_trap (lp
, 0))
2916 /* Almost all other ptrace-stops are known to be outside of system
2917 calls, with further exceptions in linux_handle_extended_wait. */
2918 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
2921 /* Handle GNU/Linux's extended waitstatus for trace events. */
2922 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
2923 && linux_is_extended_waitstatus (status
))
2925 linux_nat_debug_printf ("Handling extended status 0x%06x", status
);
2927 if (linux_handle_extended_wait (lp
, status
))
2931 /* Check if the thread has exited. */
2932 if (WIFEXITED (status
) || WIFSIGNALED (status
))
2934 if (!report_thread_events
&& !is_leader (lp
))
2936 linux_nat_debug_printf ("%s exited.",
2937 lp
->ptid
.to_string ().c_str ());
2939 /* If this was not the leader exiting, then the exit signal
2940 was not the end of the debugged application and should be
2946 /* Note that even if the leader was ptrace-stopped, it can still
2947 exit, if e.g., some other thread brings down the whole
2948 process (calls `exit'). So don't assert that the lwp is
2950 linux_nat_debug_printf ("LWP %ld exited (resumed=%d)",
2951 lp
->ptid
.lwp (), lp
->resumed
);
2953 /* Dead LWP's aren't expected to reported a pending sigstop. */
2956 /* Store the pending event in the waitstatus, because
2957 W_EXITCODE(0,0) == 0. */
2958 lp
->waitstatus
= host_status_to_waitstatus (status
);
2962 /* Make sure we don't report a SIGSTOP that we sent ourselves in
2963 an attempt to stop an LWP. */
2965 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGSTOP
)
2969 if (lp
->last_resume_kind
== resume_stop
)
2971 linux_nat_debug_printf ("resume_stop SIGSTOP caught for %s.",
2972 lp
->ptid
.to_string ().c_str ());
2976 /* This is a delayed SIGSTOP. Filter out the event. */
2978 linux_nat_debug_printf
2979 ("%s %s, 0, 0 (discard delayed SIGSTOP)",
2980 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
2981 lp
->ptid
.to_string ().c_str ());
2983 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2984 gdb_assert (lp
->resumed
);
2989 /* Make sure we don't report a SIGINT that we have already displayed
2990 for another thread. */
2991 if (lp
->ignore_sigint
2992 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGINT
)
2994 linux_nat_debug_printf ("Delayed SIGINT caught for %s.",
2995 lp
->ptid
.to_string ().c_str ());
2997 /* This is a delayed SIGINT. */
2998 lp
->ignore_sigint
= 0;
3000 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
3001 linux_nat_debug_printf ("%s %s, 0, 0 (discard SIGINT)",
3002 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
3003 lp
->ptid
.to_string ().c_str ());
3004 gdb_assert (lp
->resumed
);
3006 /* Discard the event. */
3010 /* Don't report signals that GDB isn't interested in, such as
3011 signals that are neither printed nor stopped upon. Stopping all
3012 threads can be a bit time-consuming, so if we want decent
3013 performance with heavily multi-threaded programs, especially when
3014 they're using a high frequency timer, we'd better avoid it if we
3016 if (WIFSTOPPED (status
))
3018 enum gdb_signal signo
= gdb_signal_from_host (WSTOPSIG (status
));
3020 if (!target_is_non_stop_p ())
3022 /* Only do the below in all-stop, as we currently use SIGSTOP
3023 to implement target_stop (see linux_nat_stop) in
3025 if (signo
== GDB_SIGNAL_INT
&& signal_pass_state (signo
) == 0)
3027 /* If ^C/BREAK is typed at the tty/console, SIGINT gets
3028 forwarded to the entire process group, that is, all LWPs
3029 will receive it - unless they're using CLONE_THREAD to
3030 share signals. Since we only want to report it once, we
3031 mark it as ignored for all LWPs except this one. */
3032 iterate_over_lwps (ptid_t (lp
->ptid
.pid ()), set_ignore_sigint
);
3033 lp
->ignore_sigint
= 0;
3036 maybe_clear_ignore_sigint (lp
);
3039 /* When using hardware single-step, we need to report every signal.
3040 Otherwise, signals in pass_mask may be short-circuited
3041 except signals that might be caused by a breakpoint, or SIGSTOP
3042 if we sent the SIGSTOP and are waiting for it to arrive. */
3044 && WSTOPSIG (status
) && sigismember (&pass_mask
, WSTOPSIG (status
))
3045 && (WSTOPSIG (status
) != SIGSTOP
3046 || !linux_target
->find_thread (lp
->ptid
)->stop_requested
)
3047 && !linux_wstatus_maybe_breakpoint (status
))
3049 linux_resume_one_lwp (lp
, lp
->step
, signo
);
3050 linux_nat_debug_printf
3051 ("%s %s, %s (preempt 'handle')",
3052 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
3053 lp
->ptid
.to_string ().c_str (),
3054 (signo
!= GDB_SIGNAL_0
3055 ? strsignal (gdb_signal_to_host (signo
)) : "0"));
3060 /* An interesting event. */
3062 lp
->status
= status
;
3063 save_stop_reason (lp
);
3066 /* Detect zombie thread group leaders, and "exit" them. We can't reap
3067 their exits until all other threads in the group have exited. */
3070 check_zombie_leaders (void)
3072 for (inferior
*inf
: all_inferiors ())
3074 struct lwp_info
*leader_lp
;
3079 leader_lp
= find_lwp_pid (ptid_t (inf
->pid
));
3080 if (leader_lp
!= NULL
3081 /* Check if there are other threads in the group, as we may
3082 have raced with the inferior simply exiting. Note this
3083 isn't a watertight check. If the inferior is
3084 multi-threaded and is exiting, it may be we see the
3085 leader as zombie before we reap all the non-leader
3086 threads. See comments below. */
3087 && num_lwps (inf
->pid
) > 1
3088 && linux_proc_pid_is_zombie (inf
->pid
))
3090 /* A zombie leader in a multi-threaded program can mean one
3093 #1 - Only the leader exited, not the whole program, e.g.,
3094 with pthread_exit. Since we can't reap the leader's exit
3095 status until all other threads are gone and reaped too,
3096 we want to delete the zombie leader right away, as it
3097 can't be debugged, we can't read its registers, etc.
3098 This is the main reason we check for zombie leaders
3101 #2 - The whole thread-group/process exited (a group exit,
3102 via e.g. exit(3), and there is (or will be shortly) an
3103 exit reported for each thread in the process, and then
3104 finally an exit for the leader once the non-leaders are
3107 #3 - There are 3 or more threads in the group, and a
3108 thread other than the leader exec'd. See comments on
3109 exec events at the top of the file.
3111 Ideally we would never delete the leader for case #2.
3112 Instead, we want to collect the exit status of each
3113 non-leader thread, and then finally collect the exit
3114 status of the leader as normal and use its exit code as
3115 whole-process exit code. Unfortunately, there's no
3116 race-free way to distinguish cases #1 and #2. We can't
3117 assume the exit events for the non-leaders threads are
3118 already pending in the kernel, nor can we assume the
3119 non-leader threads are in zombie state already. Between
3120 the leader becoming zombie and the non-leaders exiting
3121 and becoming zombie themselves, there's a small time
3122 window, so such a check would be racy. Temporarily
3123 pausing all threads and checking to see if all threads
3124 exit or not before re-resuming them would work in the
3125 case that all threads are running right now, but it
3126 wouldn't work if some thread is currently already
3127 ptrace-stopped, e.g., due to scheduler-locking.
3129 So what we do is we delete the leader anyhow, and then
3130 later on when we see its exit status, we re-add it back.
3131 We also make sure that we only report a whole-process
3132 exit when we see the leader exiting, as opposed to when
3133 the last LWP in the LWP list exits, which can be a
3134 non-leader if we deleted the leader here. */
3135 linux_nat_debug_printf ("Thread group leader %d zombie "
3136 "(it exited, or another thread execd), "
3139 exit_lwp (leader_lp
);
3144 /* Convenience function that is called when the kernel reports an exit
3145 event. This decides whether to report the event to GDB as a
3146 process exit event, a thread exit event, or to suppress the
3150 filter_exit_event (struct lwp_info
*event_child
,
3151 struct target_waitstatus
*ourstatus
)
3153 ptid_t ptid
= event_child
->ptid
;
3155 if (!is_leader (event_child
))
3157 if (report_thread_events
)
3158 ourstatus
->set_thread_exited (0);
3160 ourstatus
->set_ignore ();
3162 exit_lwp (event_child
);
3169 linux_nat_wait_1 (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3170 target_wait_flags target_options
)
3172 LINUX_NAT_SCOPED_DEBUG_ENTER_EXIT
;
3175 enum resume_kind last_resume_kind
;
3176 struct lwp_info
*lp
;
3179 /* The first time we get here after starting a new inferior, we may
3180 not have added it to the LWP list yet - this is the earliest
3181 moment at which we know its PID. */
3182 if (ptid
.is_pid () && find_lwp_pid (ptid
) == nullptr)
3184 ptid_t
lwp_ptid (ptid
.pid (), ptid
.pid ());
3186 /* Upgrade the main thread's ptid. */
3187 thread_change_ptid (linux_target
, ptid
, lwp_ptid
);
3188 lp
= add_initial_lwp (lwp_ptid
);
3192 /* Make sure SIGCHLD is blocked until the sigsuspend below. */
3193 block_child_signals (&prev_mask
);
3195 /* First check if there is a LWP with a wait status pending. */
3196 lp
= iterate_over_lwps (ptid
, status_callback
);
3199 linux_nat_debug_printf ("Using pending wait status %s for %s.",
3200 pending_status_str (lp
).c_str (),
3201 lp
->ptid
.to_string ().c_str ());
3204 /* But if we don't find a pending event, we'll have to wait. Always
3205 pull all events out of the kernel. We'll randomly select an
3206 event LWP out of all that have events, to prevent starvation. */
3212 /* Always use -1 and WNOHANG, due to couple of a kernel/ptrace
3215 - If the thread group leader exits while other threads in the
3216 thread group still exist, waitpid(TGID, ...) hangs. That
3217 waitpid won't return an exit status until the other threads
3218 in the group are reaped.
3220 - When a non-leader thread execs, that thread just vanishes
3221 without reporting an exit (so we'd hang if we waited for it
3222 explicitly in that case). The exec event is reported to
3226 lwpid
= my_waitpid (-1, &status
, __WALL
| WNOHANG
);
3228 linux_nat_debug_printf ("waitpid(-1, ...) returned %d, %s",
3230 errno
? safe_strerror (errno
) : "ERRNO-OK");
3234 linux_nat_debug_printf ("waitpid %ld received %s",
3236 status_to_str (status
).c_str ());
3238 linux_nat_filter_event (lwpid
, status
);
3239 /* Retry until nothing comes out of waitpid. A single
3240 SIGCHLD can indicate more than one child stopped. */
3244 /* Now that we've pulled all events out of the kernel, resume
3245 LWPs that don't have an interesting event to report. */
3246 iterate_over_lwps (minus_one_ptid
,
3247 [] (struct lwp_info
*info
)
3249 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
3252 /* ... and find an LWP with a status to report to the core, if
3254 lp
= iterate_over_lwps (ptid
, status_callback
);
3258 /* Check for zombie thread group leaders. Those can't be reaped
3259 until all other threads in the thread group are. */
3260 check_zombie_leaders ();
3262 /* If there are no resumed children left, bail. We'd be stuck
3263 forever in the sigsuspend call below otherwise. */
3264 if (iterate_over_lwps (ptid
, resumed_callback
) == NULL
)
3266 linux_nat_debug_printf ("exit (no resumed LWP)");
3268 ourstatus
->set_no_resumed ();
3270 restore_child_signals_mask (&prev_mask
);
3271 return minus_one_ptid
;
3274 /* No interesting event to report to the core. */
3276 if (target_options
& TARGET_WNOHANG
)
3278 linux_nat_debug_printf ("no interesting events found");
3280 ourstatus
->set_ignore ();
3281 restore_child_signals_mask (&prev_mask
);
3282 return minus_one_ptid
;
3285 /* We shouldn't end up here unless we want to try again. */
3286 gdb_assert (lp
== NULL
);
3288 /* Block until we get an event reported with SIGCHLD. */
3294 status
= lp
->status
;
3297 if (!target_is_non_stop_p ())
3299 /* Now stop all other LWP's ... */
3300 iterate_over_lwps (minus_one_ptid
, stop_callback
);
3302 /* ... and wait until all of them have reported back that
3303 they're no longer running. */
3304 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
3307 /* If we're not waiting for a specific LWP, choose an event LWP from
3308 among those that have had events. Giving equal priority to all
3309 LWPs that have had events helps prevent starvation. */
3310 if (ptid
== minus_one_ptid
|| ptid
.is_pid ())
3311 select_event_lwp (ptid
, &lp
, &status
);
3313 gdb_assert (lp
!= NULL
);
3315 /* Now that we've selected our final event LWP, un-adjust its PC if
3316 it was a software breakpoint, and we can't reliably support the
3317 "stopped by software breakpoint" stop reason. */
3318 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
3319 && !USE_SIGTRAP_SIGINFO
)
3321 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3322 struct gdbarch
*gdbarch
= regcache
->arch ();
3323 int decr_pc
= gdbarch_decr_pc_after_break (gdbarch
);
3329 pc
= regcache_read_pc (regcache
);
3330 regcache_write_pc (regcache
, pc
+ decr_pc
);
3334 /* We'll need this to determine whether to report a SIGSTOP as
3335 GDB_SIGNAL_0. Need to take a copy because resume_clear_callback
3337 last_resume_kind
= lp
->last_resume_kind
;
3339 if (!target_is_non_stop_p ())
3341 /* In all-stop, from the core's perspective, all LWPs are now
3342 stopped until a new resume action is sent over. */
3343 iterate_over_lwps (minus_one_ptid
, resume_clear_callback
);
3347 resume_clear_callback (lp
);
3350 if (linux_target
->low_status_is_event (status
))
3352 linux_nat_debug_printf ("trap ptid is %s.",
3353 lp
->ptid
.to_string ().c_str ());
3356 if (lp
->waitstatus
.kind () != TARGET_WAITKIND_IGNORE
)
3358 *ourstatus
= lp
->waitstatus
;
3359 lp
->waitstatus
.set_ignore ();
3362 *ourstatus
= host_status_to_waitstatus (status
);
3364 linux_nat_debug_printf ("event found");
3366 restore_child_signals_mask (&prev_mask
);
3368 if (last_resume_kind
== resume_stop
3369 && ourstatus
->kind () == TARGET_WAITKIND_STOPPED
3370 && WSTOPSIG (status
) == SIGSTOP
)
3372 /* A thread that has been requested to stop by GDB with
3373 target_stop, and it stopped cleanly, so report as SIG0. The
3374 use of SIGSTOP is an implementation detail. */
3375 ourstatus
->set_stopped (GDB_SIGNAL_0
);
3378 if (ourstatus
->kind () == TARGET_WAITKIND_EXITED
3379 || ourstatus
->kind () == TARGET_WAITKIND_SIGNALLED
)
3382 lp
->core
= linux_common_core_of_thread (lp
->ptid
);
3384 if (ourstatus
->kind () == TARGET_WAITKIND_EXITED
)
3385 return filter_exit_event (lp
, ourstatus
);
3390 /* Resume LWPs that are currently stopped without any pending status
3391 to report, but are resumed from the core's perspective. */
3394 resume_stopped_resumed_lwps (struct lwp_info
*lp
, const ptid_t wait_ptid
)
3396 inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
3400 linux_nat_debug_printf ("NOT resuming LWP %s, not stopped",
3401 lp
->ptid
.to_string ().c_str ());
3403 else if (!lp
->resumed
)
3405 linux_nat_debug_printf ("NOT resuming LWP %s, not resumed",
3406 lp
->ptid
.to_string ().c_str ());
3408 else if (lwp_status_pending_p (lp
))
3410 linux_nat_debug_printf ("NOT resuming LWP %s, has pending status",
3411 lp
->ptid
.to_string ().c_str ());
3413 else if (inf
->vfork_child
!= nullptr)
3415 linux_nat_debug_printf ("NOT resuming LWP %s (vfork parent)",
3416 lp
->ptid
.to_string ().c_str ());
3420 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3421 struct gdbarch
*gdbarch
= regcache
->arch ();
3425 CORE_ADDR pc
= regcache_read_pc (regcache
);
3426 int leave_stopped
= 0;
3428 /* Don't bother if there's a breakpoint at PC that we'd hit
3429 immediately, and we're not waiting for this LWP. */
3430 if (!lp
->ptid
.matches (wait_ptid
))
3432 if (breakpoint_inserted_here_p (regcache
->aspace (), pc
))
3438 linux_nat_debug_printf
3439 ("resuming stopped-resumed LWP %s at %s: step=%d",
3440 lp
->ptid
.to_string ().c_str (), paddress (gdbarch
, pc
),
3443 linux_resume_one_lwp_throw (lp
, lp
->step
, GDB_SIGNAL_0
);
3446 catch (const gdb_exception_error
&ex
)
3448 if (!check_ptrace_stopped_lwp_gone (lp
))
3457 linux_nat_target::wait (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3458 target_wait_flags target_options
)
3460 LINUX_NAT_SCOPED_DEBUG_ENTER_EXIT
;
3464 linux_nat_debug_printf ("[%s], [%s]", ptid
.to_string ().c_str (),
3465 target_options_to_string (target_options
).c_str ());
3467 /* Flush the async file first. */
3468 if (target_is_async_p ())
3469 async_file_flush ();
3471 /* Resume LWPs that are currently stopped without any pending status
3472 to report, but are resumed from the core's perspective. LWPs get
3473 in this state if we find them stopping at a time we're not
3474 interested in reporting the event (target_wait on a
3475 specific_process, for example, see linux_nat_wait_1), and
3476 meanwhile the event became uninteresting. Don't bother resuming
3477 LWPs we're not going to wait for if they'd stop immediately. */
3478 if (target_is_non_stop_p ())
3479 iterate_over_lwps (minus_one_ptid
,
3480 [=] (struct lwp_info
*info
)
3482 return resume_stopped_resumed_lwps (info
, ptid
);
3485 event_ptid
= linux_nat_wait_1 (ptid
, ourstatus
, target_options
);
3487 /* If we requested any event, and something came out, assume there
3488 may be more. If we requested a specific lwp or process, also
3489 assume there may be more. */
3490 if (target_is_async_p ()
3491 && ((ourstatus
->kind () != TARGET_WAITKIND_IGNORE
3492 && ourstatus
->kind () != TARGET_WAITKIND_NO_RESUMED
)
3493 || ptid
!= minus_one_ptid
))
3502 kill_one_lwp (pid_t pid
)
3504 /* PTRACE_KILL may resume the inferior. Send SIGKILL first. */
3507 kill_lwp (pid
, SIGKILL
);
3509 if (debug_linux_nat
)
3511 int save_errno
= errno
;
3513 linux_nat_debug_printf
3514 ("kill (SIGKILL) %ld, 0, 0 (%s)", (long) pid
,
3515 save_errno
!= 0 ? safe_strerror (save_errno
) : "OK");
3518 /* Some kernels ignore even SIGKILL for processes under ptrace. */
3521 ptrace (PTRACE_KILL
, pid
, 0, 0);
3522 if (debug_linux_nat
)
3524 int save_errno
= errno
;
3526 linux_nat_debug_printf
3527 ("PTRACE_KILL %ld, 0, 0 (%s)", (long) pid
,
3528 save_errno
? safe_strerror (save_errno
) : "OK");
3532 /* Wait for an LWP to die. */
3535 kill_wait_one_lwp (pid_t pid
)
3539 /* We must make sure that there are no pending events (delayed
3540 SIGSTOPs, pending SIGTRAPs, etc.) to make sure the current
3541 program doesn't interfere with any following debugging session. */
3545 res
= my_waitpid (pid
, NULL
, __WALL
);
3546 if (res
!= (pid_t
) -1)
3548 linux_nat_debug_printf ("wait %ld received unknown.", (long) pid
);
3550 /* The Linux kernel sometimes fails to kill a thread
3551 completely after PTRACE_KILL; that goes from the stop
3552 point in do_fork out to the one in get_signal_to_deliver
3553 and waits again. So kill it again. */
3559 gdb_assert (res
== -1 && errno
== ECHILD
);
3562 /* Callback for iterate_over_lwps. */
3565 kill_callback (struct lwp_info
*lp
)
3567 kill_one_lwp (lp
->ptid
.lwp ());
3571 /* Callback for iterate_over_lwps. */
3574 kill_wait_callback (struct lwp_info
*lp
)
3576 kill_wait_one_lwp (lp
->ptid
.lwp ());
3580 /* Kill the fork/clone child of LP if it has an unfollowed child. */
3583 kill_unfollowed_child_callback (lwp_info
*lp
)
3585 gdb::optional
<target_waitstatus
> ws
= get_pending_child_status (lp
);
3586 if (ws
.has_value ())
3588 ptid_t child_ptid
= ws
->child_ptid ();
3589 int child_pid
= child_ptid
.pid ();
3590 int child_lwp
= child_ptid
.lwp ();
3592 kill_one_lwp (child_lwp
);
3593 kill_wait_one_lwp (child_lwp
);
3595 /* Let the arch-specific native code know this process is
3597 if (ws
->kind () != TARGET_WAITKIND_THREAD_CLONED
)
3598 linux_target
->low_forget_process (child_pid
);
3605 linux_nat_target::kill ()
3607 ptid_t
pid_ptid (inferior_ptid
.pid ());
3609 /* If we're stopped while forking/cloning and we haven't followed
3610 yet, kill the child task. We need to do this first because the
3611 parent will be sleeping if this is a vfork. */
3612 iterate_over_lwps (pid_ptid
, kill_unfollowed_child_callback
);
3614 if (forks_exist_p ())
3615 linux_fork_killall ();
3618 /* Stop all threads before killing them, since ptrace requires
3619 that the thread is stopped to successfully PTRACE_KILL. */
3620 iterate_over_lwps (pid_ptid
, stop_callback
);
3621 /* ... and wait until all of them have reported back that
3622 they're no longer running. */
3623 iterate_over_lwps (pid_ptid
, stop_wait_callback
);
3625 /* Kill all LWP's ... */
3626 iterate_over_lwps (pid_ptid
, kill_callback
);
3628 /* ... and wait until we've flushed all events. */
3629 iterate_over_lwps (pid_ptid
, kill_wait_callback
);
3632 target_mourn_inferior (inferior_ptid
);
3636 linux_nat_target::mourn_inferior ()
3638 LINUX_NAT_SCOPED_DEBUG_ENTER_EXIT
;
3640 int pid
= inferior_ptid
.pid ();
3642 purge_lwp_list (pid
);
3644 close_proc_mem_file (pid
);
3646 if (! forks_exist_p ())
3647 /* Normal case, no other forks available. */
3648 inf_ptrace_target::mourn_inferior ();
3650 /* Multi-fork case. The current inferior_ptid has exited, but
3651 there are other viable forks to debug. Delete the exiting
3652 one and context-switch to the first available. */
3653 linux_fork_mourn_inferior ();
3655 /* Let the arch-specific native code know this process is gone. */
3656 linux_target
->low_forget_process (pid
);
3659 /* Convert a native/host siginfo object, into/from the siginfo in the
3660 layout of the inferiors' architecture. */
3663 siginfo_fixup (siginfo_t
*siginfo
, gdb_byte
*inf_siginfo
, int direction
)
3665 /* If the low target didn't do anything, then just do a straight
3667 if (!linux_target
->low_siginfo_fixup (siginfo
, inf_siginfo
, direction
))
3670 memcpy (siginfo
, inf_siginfo
, sizeof (siginfo_t
));
3672 memcpy (inf_siginfo
, siginfo
, sizeof (siginfo_t
));
3676 static enum target_xfer_status
3677 linux_xfer_siginfo (ptid_t ptid
, enum target_object object
,
3678 const char *annex
, gdb_byte
*readbuf
,
3679 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3680 ULONGEST
*xfered_len
)
3683 gdb_byte inf_siginfo
[sizeof (siginfo_t
)];
3685 gdb_assert (object
== TARGET_OBJECT_SIGNAL_INFO
);
3686 gdb_assert (readbuf
|| writebuf
);
3688 if (offset
> sizeof (siginfo
))
3689 return TARGET_XFER_E_IO
;
3691 if (!linux_nat_get_siginfo (ptid
, &siginfo
))
3692 return TARGET_XFER_E_IO
;
3694 /* When GDB is built as a 64-bit application, ptrace writes into
3695 SIGINFO an object with 64-bit layout. Since debugging a 32-bit
3696 inferior with a 64-bit GDB should look the same as debugging it
3697 with a 32-bit GDB, we need to convert it. GDB core always sees
3698 the converted layout, so any read/write will have to be done
3700 siginfo_fixup (&siginfo
, inf_siginfo
, 0);
3702 if (offset
+ len
> sizeof (siginfo
))
3703 len
= sizeof (siginfo
) - offset
;
3705 if (readbuf
!= NULL
)
3706 memcpy (readbuf
, inf_siginfo
+ offset
, len
);
3709 memcpy (inf_siginfo
+ offset
, writebuf
, len
);
3711 /* Convert back to ptrace layout before flushing it out. */
3712 siginfo_fixup (&siginfo
, inf_siginfo
, 1);
3714 int pid
= get_ptrace_pid (ptid
);
3716 ptrace (PTRACE_SETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, &siginfo
);
3718 return TARGET_XFER_E_IO
;
3722 return TARGET_XFER_OK
;
3725 static enum target_xfer_status
3726 linux_nat_xfer_osdata (enum target_object object
,
3727 const char *annex
, gdb_byte
*readbuf
,
3728 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3729 ULONGEST
*xfered_len
);
3731 static enum target_xfer_status
3732 linux_proc_xfer_memory_partial (int pid
, gdb_byte
*readbuf
,
3733 const gdb_byte
*writebuf
, ULONGEST offset
,
3734 LONGEST len
, ULONGEST
*xfered_len
);
3736 enum target_xfer_status
3737 linux_nat_target::xfer_partial (enum target_object object
,
3738 const char *annex
, gdb_byte
*readbuf
,
3739 const gdb_byte
*writebuf
,
3740 ULONGEST offset
, ULONGEST len
, ULONGEST
*xfered_len
)
3742 if (object
== TARGET_OBJECT_SIGNAL_INFO
)
3743 return linux_xfer_siginfo (inferior_ptid
, object
, annex
, readbuf
, writebuf
,
3744 offset
, len
, xfered_len
);
3746 /* The target is connected but no live inferior is selected. Pass
3747 this request down to a lower stratum (e.g., the executable
3749 if (object
== TARGET_OBJECT_MEMORY
&& inferior_ptid
== null_ptid
)
3750 return TARGET_XFER_EOF
;
3752 if (object
== TARGET_OBJECT_AUXV
)
3753 return memory_xfer_auxv (this, object
, annex
, readbuf
, writebuf
,
3754 offset
, len
, xfered_len
);
3756 if (object
== TARGET_OBJECT_OSDATA
)
3757 return linux_nat_xfer_osdata (object
, annex
, readbuf
, writebuf
,
3758 offset
, len
, xfered_len
);
3760 if (object
== TARGET_OBJECT_MEMORY
)
3762 /* GDB calculates all addresses in the largest possible address
3763 width. The address width must be masked before its final use
3764 by linux_proc_xfer_partial.
3766 Compare ADDR_BIT first to avoid a compiler warning on shift overflow. */
3767 int addr_bit
= gdbarch_addr_bit (current_inferior ()->arch ());
3769 if (addr_bit
< (sizeof (ULONGEST
) * HOST_CHAR_BIT
))
3770 offset
&= ((ULONGEST
) 1 << addr_bit
) - 1;
3772 /* If /proc/pid/mem is writable, don't fallback to ptrace. If
3773 the write via /proc/pid/mem fails because the inferior execed
3774 (and we haven't seen the exec event yet), a subsequent ptrace
3775 poke would incorrectly write memory to the post-exec address
3776 space, while the core was trying to write to the pre-exec
3778 if (proc_mem_file_is_writable ())
3779 return linux_proc_xfer_memory_partial (inferior_ptid
.pid (), readbuf
,
3780 writebuf
, offset
, len
,
3784 return inf_ptrace_target::xfer_partial (object
, annex
, readbuf
, writebuf
,
3785 offset
, len
, xfered_len
);
3789 linux_nat_target::thread_alive (ptid_t ptid
)
3791 /* As long as a PTID is in lwp list, consider it alive. */
3792 return find_lwp_pid (ptid
) != NULL
;
3795 /* Implement the to_update_thread_list target method for this
3799 linux_nat_target::update_thread_list ()
3801 /* We add/delete threads from the list as clone/exit events are
3802 processed, so just try deleting exited threads still in the
3804 delete_exited_threads ();
3806 /* Update the processor core that each lwp/thread was last seen
3808 for (lwp_info
*lwp
: all_lwps ())
3810 /* Avoid accessing /proc if the thread hasn't run since we last
3811 time we fetched the thread's core. Accessing /proc becomes
3812 noticeably expensive when we have thousands of LWPs. */
3813 if (lwp
->core
== -1)
3814 lwp
->core
= linux_common_core_of_thread (lwp
->ptid
);
3819 linux_nat_target::pid_to_str (ptid_t ptid
)
3822 && (ptid
.pid () != ptid
.lwp ()
3823 || num_lwps (ptid
.pid ()) > 1))
3824 return string_printf ("LWP %ld", ptid
.lwp ());
3826 return normal_pid_to_str (ptid
);
3830 linux_nat_target::thread_name (struct thread_info
*thr
)
3832 return linux_proc_tid_get_name (thr
->ptid
);
3835 /* Accepts an integer PID; Returns a string representing a file that
3836 can be opened to get the symbols for the child process. */
3839 linux_nat_target::pid_to_exec_file (int pid
)
3841 return linux_proc_pid_to_exec_file (pid
);
3844 /* Object representing an /proc/PID/mem open file. We keep one such
3845 file open per inferior.
3847 It might be tempting to think about only ever opening one file at
3848 most for all inferiors, closing/reopening the file as we access
3849 memory of different inferiors, to minimize number of file
3850 descriptors open, which can otherwise run into resource limits.
3851 However, that does not work correctly -- if the inferior execs and
3852 we haven't processed the exec event yet, and, we opened a
3853 /proc/PID/mem file, we will get a mem file accessing the post-exec
3854 address space, thinking we're opening it for the pre-exec address
3855 space. That is dangerous as we can poke memory (e.g. clearing
3856 breakpoints) in the post-exec memory by mistake, corrupting the
3857 inferior. For that reason, we open the mem file as early as
3858 possible, right after spawning, forking or attaching to the
3859 inferior, when the inferior is stopped and thus before it has a
3862 Note that after opening the file, even if the thread we opened it
3863 for subsequently exits, the open file is still usable for accessing
3864 memory. It's only when the whole process exits or execs that the
3865 file becomes invalid, at which point reads/writes return EOF. */
3870 proc_mem_file (ptid_t ptid
, int fd
)
3871 : m_ptid (ptid
), m_fd (fd
)
3873 gdb_assert (m_fd
!= -1);
3878 linux_nat_debug_printf ("closing fd %d for /proc/%d/task/%ld/mem",
3879 m_fd
, m_ptid
.pid (), m_ptid
.lwp ());
3883 DISABLE_COPY_AND_ASSIGN (proc_mem_file
);
3891 /* The LWP this file was opened for. Just for debugging
3895 /* The file descriptor. */
3899 /* The map between an inferior process id, and the open /proc/PID/mem
3900 file. This is stored in a map instead of in a per-inferior
3901 structure because we need to be able to access memory of processes
3902 which don't have a corresponding struct inferior object. E.g.,
3903 with "detach-on-fork on" (the default), and "follow-fork parent"
3904 (also default), we don't create an inferior for the fork child, but
3905 we still need to remove breakpoints from the fork child's
3907 static std::unordered_map
<int, proc_mem_file
> proc_mem_file_map
;
3909 /* Close the /proc/PID/mem file for PID. */
3912 close_proc_mem_file (pid_t pid
)
3914 proc_mem_file_map
.erase (pid
);
3917 /* Open the /proc/PID/mem file for the process (thread group) of PTID.
3918 We actually open /proc/PID/task/LWP/mem, as that's the LWP we know
3919 exists and is stopped right now. We prefer the
3920 /proc/PID/task/LWP/mem form over /proc/LWP/mem to avoid tid-reuse
3921 races, just in case this is ever called on an already-waited
3925 open_proc_mem_file (ptid_t ptid
)
3927 auto iter
= proc_mem_file_map
.find (ptid
.pid ());
3928 gdb_assert (iter
== proc_mem_file_map
.end ());
3931 xsnprintf (filename
, sizeof filename
,
3932 "/proc/%d/task/%ld/mem", ptid
.pid (), ptid
.lwp ());
3934 int fd
= gdb_open_cloexec (filename
, O_RDWR
| O_LARGEFILE
, 0).release ();
3938 warning (_("opening /proc/PID/mem file for lwp %d.%ld failed: %s (%d)"),
3939 ptid
.pid (), ptid
.lwp (),
3940 safe_strerror (errno
), errno
);
3944 proc_mem_file_map
.emplace (std::piecewise_construct
,
3945 std::forward_as_tuple (ptid
.pid ()),
3946 std::forward_as_tuple (ptid
, fd
));
3948 linux_nat_debug_printf ("opened fd %d for lwp %d.%ld",
3949 fd
, ptid
.pid (), ptid
.lwp ());
3952 /* Helper for linux_proc_xfer_memory_partial and
3953 proc_mem_file_is_writable. FD is the already opened /proc/pid/mem
3954 file, and PID is the pid of the corresponding process. The rest of
3955 the arguments are like linux_proc_xfer_memory_partial's. */
3957 static enum target_xfer_status
3958 linux_proc_xfer_memory_partial_fd (int fd
, int pid
,
3959 gdb_byte
*readbuf
, const gdb_byte
*writebuf
,
3960 ULONGEST offset
, LONGEST len
,
3961 ULONGEST
*xfered_len
)
3965 gdb_assert (fd
!= -1);
3967 /* Use pread64/pwrite64 if available, since they save a syscall and
3968 can handle 64-bit offsets even on 32-bit platforms (for instance,
3969 SPARC debugging a SPARC64 application). But only use them if the
3970 offset isn't so high that when cast to off_t it'd be negative, as
3971 seen on SPARC64. pread64/pwrite64 outright reject such offsets.
3974 if ((off_t
) offset
>= 0)
3975 ret
= (readbuf
!= nullptr
3976 ? pread64 (fd
, readbuf
, len
, offset
)
3977 : pwrite64 (fd
, writebuf
, len
, offset
));
3981 ret
= lseek (fd
, offset
, SEEK_SET
);
3983 ret
= (readbuf
!= nullptr
3984 ? read (fd
, readbuf
, len
)
3985 : write (fd
, writebuf
, len
));
3990 linux_nat_debug_printf ("accessing fd %d for pid %d failed: %s (%d)",
3991 fd
, pid
, safe_strerror (errno
), errno
);
3992 return TARGET_XFER_E_IO
;
3996 /* EOF means the address space is gone, the whole process exited
3998 linux_nat_debug_printf ("accessing fd %d for pid %d got EOF",
4000 return TARGET_XFER_EOF
;
4005 return TARGET_XFER_OK
;
4009 /* Implement the to_xfer_partial target method using /proc/PID/mem.
4010 Because we can use a single read/write call, this can be much more
4011 efficient than banging away at PTRACE_PEEKTEXT. Also, unlike
4012 PTRACE_PEEKTEXT/PTRACE_POKETEXT, this works with running
4015 static enum target_xfer_status
4016 linux_proc_xfer_memory_partial (int pid
, gdb_byte
*readbuf
,
4017 const gdb_byte
*writebuf
, ULONGEST offset
,
4018 LONGEST len
, ULONGEST
*xfered_len
)
4020 auto iter
= proc_mem_file_map
.find (pid
);
4021 if (iter
== proc_mem_file_map
.end ())
4022 return TARGET_XFER_EOF
;
4024 int fd
= iter
->second
.fd ();
4026 return linux_proc_xfer_memory_partial_fd (fd
, pid
, readbuf
, writebuf
, offset
,
4030 /* Check whether /proc/pid/mem is writable in the current kernel, and
4031 return true if so. It wasn't writable before Linux 2.6.39, but
4032 there's no way to know whether the feature was backported to older
4033 kernels. So we check to see if it works. The result is cached,
4034 and this is guaranteed to be called once early during inferior
4035 startup, so that any warning is printed out consistently between
4036 GDB invocations. Note we don't call it during GDB startup instead
4037 though, because then we might warn with e.g. just "gdb --version"
4038 on sandboxed systems. See PR gdb/29907. */
4041 proc_mem_file_is_writable ()
4043 static gdb::optional
<bool> writable
;
4045 if (writable
.has_value ())
4048 writable
.emplace (false);
4050 /* We check whether /proc/pid/mem is writable by trying to write to
4051 one of our variables via /proc/self/mem. */
4053 int fd
= gdb_open_cloexec ("/proc/self/mem", O_RDWR
| O_LARGEFILE
, 0).release ();
4057 warning (_("opening /proc/self/mem file failed: %s (%d)"),
4058 safe_strerror (errno
), errno
);
4062 SCOPE_EXIT
{ close (fd
); };
4064 /* This is the variable we try to write to. Note OFFSET below. */
4065 volatile gdb_byte test_var
= 0;
4067 gdb_byte writebuf
[] = {0x55};
4068 ULONGEST offset
= (uintptr_t) &test_var
;
4069 ULONGEST xfered_len
;
4071 enum target_xfer_status res
4072 = linux_proc_xfer_memory_partial_fd (fd
, getpid (), nullptr, writebuf
,
4073 offset
, 1, &xfered_len
);
4075 if (res
== TARGET_XFER_OK
)
4077 gdb_assert (xfered_len
== 1);
4078 gdb_assert (test_var
== 0x55);
4086 /* Parse LINE as a signal set and add its set bits to SIGS. */
4089 add_line_to_sigset (const char *line
, sigset_t
*sigs
)
4091 int len
= strlen (line
) - 1;
4095 if (line
[len
] != '\n')
4096 error (_("Could not parse signal set: %s"), line
);
4104 if (*p
>= '0' && *p
<= '9')
4106 else if (*p
>= 'a' && *p
<= 'f')
4107 digit
= *p
- 'a' + 10;
4109 error (_("Could not parse signal set: %s"), line
);
4114 sigaddset (sigs
, signum
+ 1);
4116 sigaddset (sigs
, signum
+ 2);
4118 sigaddset (sigs
, signum
+ 3);
4120 sigaddset (sigs
, signum
+ 4);
4126 /* Find process PID's pending signals from /proc/pid/status and set
4130 linux_proc_pending_signals (int pid
, sigset_t
*pending
,
4131 sigset_t
*blocked
, sigset_t
*ignored
)
4133 char buffer
[PATH_MAX
], fname
[PATH_MAX
];
4135 sigemptyset (pending
);
4136 sigemptyset (blocked
);
4137 sigemptyset (ignored
);
4138 xsnprintf (fname
, sizeof fname
, "/proc/%d/status", pid
);
4139 gdb_file_up procfile
= gdb_fopen_cloexec (fname
, "r");
4140 if (procfile
== NULL
)
4141 error (_("Could not open %s"), fname
);
4143 while (fgets (buffer
, PATH_MAX
, procfile
.get ()) != NULL
)
4145 /* Normal queued signals are on the SigPnd line in the status
4146 file. However, 2.6 kernels also have a "shared" pending
4147 queue for delivering signals to a thread group, so check for
4150 Unfortunately some Red Hat kernels include the shared pending
4151 queue but not the ShdPnd status field. */
4153 if (startswith (buffer
, "SigPnd:\t"))
4154 add_line_to_sigset (buffer
+ 8, pending
);
4155 else if (startswith (buffer
, "ShdPnd:\t"))
4156 add_line_to_sigset (buffer
+ 8, pending
);
4157 else if (startswith (buffer
, "SigBlk:\t"))
4158 add_line_to_sigset (buffer
+ 8, blocked
);
4159 else if (startswith (buffer
, "SigIgn:\t"))
4160 add_line_to_sigset (buffer
+ 8, ignored
);
4164 static enum target_xfer_status
4165 linux_nat_xfer_osdata (enum target_object object
,
4166 const char *annex
, gdb_byte
*readbuf
,
4167 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
4168 ULONGEST
*xfered_len
)
4170 gdb_assert (object
== TARGET_OBJECT_OSDATA
);
4172 *xfered_len
= linux_common_xfer_osdata (annex
, readbuf
, offset
, len
);
4173 if (*xfered_len
== 0)
4174 return TARGET_XFER_EOF
;
4176 return TARGET_XFER_OK
;
4179 std::vector
<static_tracepoint_marker
>
4180 linux_nat_target::static_tracepoint_markers_by_strid (const char *strid
)
4182 char s
[IPA_CMD_BUF_SIZE
];
4183 int pid
= inferior_ptid
.pid ();
4184 std::vector
<static_tracepoint_marker
> markers
;
4186 ptid_t ptid
= ptid_t (pid
, 0);
4187 static_tracepoint_marker marker
;
4192 strcpy (s
, "qTfSTM");
4193 agent_run_command (pid
, s
, strlen (s
) + 1);
4196 SCOPE_EXIT
{ target_continue_no_signal (ptid
); };
4202 parse_static_tracepoint_marker_definition (p
, &p
, &marker
);
4204 if (strid
== NULL
|| marker
.str_id
== strid
)
4205 markers
.push_back (std::move (marker
));
4207 while (*p
++ == ','); /* comma-separated list */
4209 strcpy (s
, "qTsSTM");
4210 agent_run_command (pid
, s
, strlen (s
) + 1);
4217 /* target_can_async_p implementation. */
4220 linux_nat_target::can_async_p ()
4222 /* This flag should be checked in the common target.c code. */
4223 gdb_assert (target_async_permitted
);
4225 /* Otherwise, this targets is always able to support async mode. */
4230 linux_nat_target::supports_non_stop ()
4235 /* to_always_non_stop_p implementation. */
4238 linux_nat_target::always_non_stop_p ()
4244 linux_nat_target::supports_multi_process ()
4250 linux_nat_target::supports_disable_randomization ()
4255 /* SIGCHLD handler that serves two purposes: In non-stop/async mode,
4256 so we notice when any child changes state, and notify the
4257 event-loop; it allows us to use sigsuspend in linux_nat_wait_1
4258 above to wait for the arrival of a SIGCHLD. */
4261 sigchld_handler (int signo
)
4263 int old_errno
= errno
;
4265 if (debug_linux_nat
)
4266 gdb_stdlog
->write_async_safe ("sigchld\n", sizeof ("sigchld\n") - 1);
4268 if (signo
== SIGCHLD
)
4270 /* Let the event loop know that there are events to handle. */
4271 linux_nat_target::async_file_mark_if_open ();
4277 /* Callback registered with the target events file descriptor. */
4280 handle_target_event (int error
, gdb_client_data client_data
)
4282 inferior_event_handler (INF_REG_EVENT
);
4285 /* target_async implementation. */
4288 linux_nat_target::async (bool enable
)
4290 if (enable
== is_async_p ())
4293 /* Block child signals while we create/destroy the pipe, as their
4294 handler writes to it. */
4295 gdb::block_signals blocker
;
4299 if (!async_file_open ())
4300 internal_error ("creating event pipe failed.");
4302 add_file_handler (async_wait_fd (), handle_target_event
, NULL
,
4305 /* There may be pending events to handle. Tell the event loop
4311 delete_file_handler (async_wait_fd ());
4312 async_file_close ();
4316 /* Stop an LWP, and push a GDB_SIGNAL_0 stop status if no other
4320 linux_nat_stop_lwp (struct lwp_info
*lwp
)
4324 linux_nat_debug_printf ("running -> suspending %s",
4325 lwp
->ptid
.to_string ().c_str ());
4328 if (lwp
->last_resume_kind
== resume_stop
)
4330 linux_nat_debug_printf ("already stopping LWP %ld at GDB's request",
4335 stop_callback (lwp
);
4336 lwp
->last_resume_kind
= resume_stop
;
4340 /* Already known to be stopped; do nothing. */
4342 if (debug_linux_nat
)
4344 if (linux_target
->find_thread (lwp
->ptid
)->stop_requested
)
4345 linux_nat_debug_printf ("already stopped/stop_requested %s",
4346 lwp
->ptid
.to_string ().c_str ());
4348 linux_nat_debug_printf ("already stopped/no stop_requested yet %s",
4349 lwp
->ptid
.to_string ().c_str ());
4356 linux_nat_target::stop (ptid_t ptid
)
4358 LINUX_NAT_SCOPED_DEBUG_ENTER_EXIT
;
4359 iterate_over_lwps (ptid
, linux_nat_stop_lwp
);
4362 /* When requests are passed down from the linux-nat layer to the
4363 single threaded inf-ptrace layer, ptids of (lwpid,0,0) form are
4364 used. The address space pointer is stored in the inferior object,
4365 but the common code that is passed such ptid can't tell whether
4366 lwpid is a "main" process id or not (it assumes so). We reverse
4367 look up the "main" process id from the lwp here. */
4369 struct address_space
*
4370 linux_nat_target::thread_address_space (ptid_t ptid
)
4372 struct lwp_info
*lwp
;
4373 struct inferior
*inf
;
4376 if (ptid
.lwp () == 0)
4378 /* An (lwpid,0,0) ptid. Look up the lwp object to get at the
4380 lwp
= find_lwp_pid (ptid
);
4381 pid
= lwp
->ptid
.pid ();
4385 /* A (pid,lwpid,0) ptid. */
4389 inf
= find_inferior_pid (this, pid
);
4390 gdb_assert (inf
!= NULL
);
4394 /* Return the cached value of the processor core for thread PTID. */
4397 linux_nat_target::core_of_thread (ptid_t ptid
)
4399 struct lwp_info
*info
= find_lwp_pid (ptid
);
4406 /* Implementation of to_filesystem_is_local. */
4409 linux_nat_target::filesystem_is_local ()
4411 struct inferior
*inf
= current_inferior ();
4413 if (inf
->fake_pid_p
|| inf
->pid
== 0)
4416 return linux_ns_same (inf
->pid
, LINUX_NS_MNT
);
4419 /* Convert the INF argument passed to a to_fileio_* method
4420 to a process ID suitable for passing to its corresponding
4421 linux_mntns_* function. If INF is non-NULL then the
4422 caller is requesting the filesystem seen by INF. If INF
4423 is NULL then the caller is requesting the filesystem seen
4424 by the GDB. We fall back to GDB's filesystem in the case
4425 that INF is non-NULL but its PID is unknown. */
4428 linux_nat_fileio_pid_of (struct inferior
*inf
)
4430 if (inf
== NULL
|| inf
->fake_pid_p
|| inf
->pid
== 0)
4436 /* Implementation of to_fileio_open. */
4439 linux_nat_target::fileio_open (struct inferior
*inf
, const char *filename
,
4440 int flags
, int mode
, int warn_if_slow
,
4441 fileio_error
*target_errno
)
4447 if (fileio_to_host_openflags (flags
, &nat_flags
) == -1
4448 || fileio_to_host_mode (mode
, &nat_mode
) == -1)
4450 *target_errno
= FILEIO_EINVAL
;
4454 fd
= linux_mntns_open_cloexec (linux_nat_fileio_pid_of (inf
),
4455 filename
, nat_flags
, nat_mode
);
4457 *target_errno
= host_to_fileio_error (errno
);
4462 /* Implementation of to_fileio_readlink. */
4464 gdb::optional
<std::string
>
4465 linux_nat_target::fileio_readlink (struct inferior
*inf
, const char *filename
,
4466 fileio_error
*target_errno
)
4471 len
= linux_mntns_readlink (linux_nat_fileio_pid_of (inf
),
4472 filename
, buf
, sizeof (buf
));
4475 *target_errno
= host_to_fileio_error (errno
);
4479 return std::string (buf
, len
);
4482 /* Implementation of to_fileio_unlink. */
4485 linux_nat_target::fileio_unlink (struct inferior
*inf
, const char *filename
,
4486 fileio_error
*target_errno
)
4490 ret
= linux_mntns_unlink (linux_nat_fileio_pid_of (inf
),
4493 *target_errno
= host_to_fileio_error (errno
);
4498 /* Implementation of the to_thread_events method. */
4501 linux_nat_target::thread_events (int enable
)
4503 report_thread_events
= enable
;
4506 linux_nat_target::linux_nat_target ()
4508 /* We don't change the stratum; this target will sit at
4509 process_stratum and thread_db will set at thread_stratum. This
4510 is a little strange, since this is a multi-threaded-capable
4511 target, but we want to be on the stack below thread_db, and we
4512 also want to be used for single-threaded processes. */
4515 /* See linux-nat.h. */
4518 linux_nat_get_siginfo (ptid_t ptid
, siginfo_t
*siginfo
)
4520 int pid
= get_ptrace_pid (ptid
);
4521 return ptrace (PTRACE_GETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, siginfo
) == 0;
4524 /* See nat/linux-nat.h. */
4527 current_lwp_ptid (void)
4529 gdb_assert (inferior_ptid
.lwp_p ());
4530 return inferior_ptid
;
4533 /* Implement 'maintenance info linux-lwps'. Displays some basic
4534 information about all the current lwp_info objects. */
4537 maintenance_info_lwps (const char *arg
, int from_tty
)
4539 if (all_lwps ().size () == 0)
4541 gdb_printf ("No Linux LWPs\n");
4545 /* Start the width at 8 to match the column heading below, then
4546 figure out the widest ptid string. We'll use this to build our
4547 output table below. */
4548 size_t ptid_width
= 8;
4549 for (lwp_info
*lp
: all_lwps ())
4550 ptid_width
= std::max (ptid_width
, lp
->ptid
.to_string ().size ());
4552 /* Setup the table headers. */
4553 struct ui_out
*uiout
= current_uiout
;
4554 ui_out_emit_table
table_emitter (uiout
, 2, -1, "linux-lwps");
4555 uiout
->table_header (ptid_width
, ui_left
, "lwp-ptid", _("LWP Ptid"));
4556 uiout
->table_header (9, ui_left
, "thread-info", _("Thread ID"));
4557 uiout
->table_body ();
4559 /* Display one table row for each lwp_info. */
4560 for (lwp_info
*lp
: all_lwps ())
4562 ui_out_emit_tuple
tuple_emitter (uiout
, "lwp-entry");
4564 thread_info
*th
= linux_target
->find_thread (lp
->ptid
);
4566 uiout
->field_string ("lwp-ptid", lp
->ptid
.to_string ().c_str ());
4568 uiout
->field_string ("thread-info", "None");
4570 uiout
->field_string ("thread-info", print_full_thread_id (th
));
4572 uiout
->message ("\n");
4576 void _initialize_linux_nat ();
4578 _initialize_linux_nat ()
4580 add_setshow_boolean_cmd ("linux-nat", class_maintenance
,
4581 &debug_linux_nat
, _("\
4582 Set debugging of GNU/Linux native target."), _(" \
4583 Show debugging of GNU/Linux native target."), _(" \
4584 When on, print debug messages relating to the GNU/Linux native target."),
4586 show_debug_linux_nat
,
4587 &setdebuglist
, &showdebuglist
);
4589 add_setshow_boolean_cmd ("linux-namespaces", class_maintenance
,
4590 &debug_linux_namespaces
, _("\
4591 Set debugging of GNU/Linux namespaces module."), _("\
4592 Show debugging of GNU/Linux namespaces module."), _("\
4593 Enables printf debugging output."),
4596 &setdebuglist
, &showdebuglist
);
4598 /* Install a SIGCHLD handler. */
4599 sigchld_action
.sa_handler
= sigchld_handler
;
4600 sigemptyset (&sigchld_action
.sa_mask
);
4601 sigchld_action
.sa_flags
= SA_RESTART
;
4603 /* Make it the default. */
4604 sigaction (SIGCHLD
, &sigchld_action
, NULL
);
4606 /* Make sure we don't block SIGCHLD during a sigsuspend. */
4607 gdb_sigmask (SIG_SETMASK
, NULL
, &suspend_mask
);
4608 sigdelset (&suspend_mask
, SIGCHLD
);
4610 sigemptyset (&blocked_mask
);
4612 lwp_lwpid_htab_create ();
4614 add_cmd ("linux-lwps", class_maintenance
, maintenance_info_lwps
,
4615 _("List the Linux LWPS."), &maintenanceinfolist
);
4619 /* FIXME: kettenis/2000-08-26: The stuff on this page is specific to
4620 the GNU/Linux Threads library and therefore doesn't really belong
4623 /* NPTL reserves the first two RT signals, but does not provide any
4624 way for the debugger to query the signal numbers - fortunately
4625 they don't change. */
4626 static int lin_thread_signals
[] = { __SIGRTMIN
, __SIGRTMIN
+ 1 };
4628 /* See linux-nat.h. */
4631 lin_thread_get_thread_signal_num (void)
4633 return sizeof (lin_thread_signals
) / sizeof (lin_thread_signals
[0]);
4636 /* See linux-nat.h. */
4639 lin_thread_get_thread_signal (unsigned int i
)
4641 gdb_assert (i
< lin_thread_get_thread_signal_num ());
4642 return lin_thread_signals
[i
];