1 /* GNU/Linux native-dependent code common to multiple platforms.
3 Copyright (C) 2001-2022 Free Software Foundation, Inc.
5 This file is part of GDB.
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>. */
24 #include "nat/linux-nat.h"
25 #include "nat/linux-waitpid.h"
26 #include "gdbsupport/gdb_wait.h"
28 #include <sys/syscall.h>
29 #include "nat/gdb_ptrace.h"
30 #include "linux-nat.h"
31 #include "nat/linux-ptrace.h"
32 #include "nat/linux-procfs.h"
33 #include "nat/linux-personality.h"
34 #include "linux-fork.h"
35 #include "gdbthread.h"
39 #include "inf-child.h"
40 #include "inf-ptrace.h"
42 #include <sys/procfs.h> /* for elf_gregset etc. */
43 #include "elf-bfd.h" /* for elfcore_write_* */
44 #include "gregset.h" /* for gregset */
45 #include "gdbcore.h" /* for get_exec_file */
46 #include <ctype.h> /* for isdigit */
47 #include <sys/stat.h> /* for struct stat */
48 #include <fcntl.h> /* for O_RDONLY */
50 #include "gdbsupport/event-loop.h"
51 #include "event-top.h"
53 #include <sys/types.h>
55 #include "xml-support.h"
58 #include "nat/linux-osdata.h"
59 #include "linux-tdep.h"
61 #include "gdbsupport/agent.h"
62 #include "tracepoint.h"
63 #include "gdbsupport/buffer.h"
64 #include "target-descriptions.h"
65 #include "gdbsupport/filestuff.h"
67 #include "nat/linux-namespaces.h"
68 #include "gdbsupport/block-signals.h"
69 #include "gdbsupport/fileio.h"
70 #include "gdbsupport/scope-exit.h"
71 #include "gdbsupport/gdb-sigmask.h"
72 #include "gdbsupport/common-debug.h"
73 #include <unordered_map>
75 /* This comment documents high-level logic of this file.
77 Waiting for events in sync mode
78 ===============================
80 When waiting for an event in a specific thread, we just use waitpid,
81 passing the specific pid, and not passing WNOHANG.
83 When waiting for an event in all threads, waitpid is not quite good:
85 - If the thread group leader exits while other threads in the thread
86 group still exist, waitpid(TGID, ...) hangs. That waitpid won't
87 return an exit status until the other threads in the group are
90 - When a non-leader thread execs, that thread just vanishes without
91 reporting an exit (so we'd hang if we waited for it explicitly in
92 that case). The exec event is instead reported to the TGID pid.
94 The solution is to always use -1 and WNOHANG, together with
97 First, we use non-blocking waitpid to check for events. If nothing is
98 found, we use sigsuspend to wait for SIGCHLD. When SIGCHLD arrives,
99 it means something happened to a child process. As soon as we know
100 there's an event, we get back to calling nonblocking waitpid.
102 Note that SIGCHLD should be blocked between waitpid and sigsuspend
103 calls, so that we don't miss a signal. If SIGCHLD arrives in between,
104 when it's blocked, the signal becomes pending and sigsuspend
105 immediately notices it and returns.
107 Waiting for events in async mode (TARGET_WNOHANG)
108 =================================================
110 In async mode, GDB should always be ready to handle both user input
111 and target events, so neither blocking waitpid nor sigsuspend are
112 viable options. Instead, we should asynchronously notify the GDB main
113 event loop whenever there's an unprocessed event from the target. We
114 detect asynchronous target events by handling SIGCHLD signals. To
115 notify the event loop about target events, an event pipe is used
116 --- the pipe is registered as waitable event source in the event loop,
117 the event loop select/poll's on the read end of this pipe (as well on
118 other event sources, e.g., stdin), and the SIGCHLD handler marks the
119 event pipe to raise an event. This is more portable than relying on
120 pselect/ppoll, since on kernels that lack those syscalls, libc
121 emulates them with select/poll+sigprocmask, and that is racy
122 (a.k.a. plain broken).
124 Obviously, if we fail to notify the event loop if there's a target
125 event, it's bad. OTOH, if we notify the event loop when there's no
126 event from the target, linux_nat_wait will detect that there's no real
127 event to report, and return event of type TARGET_WAITKIND_IGNORE.
128 This is mostly harmless, but it will waste time and is better avoided.
130 The main design point is that every time GDB is outside linux-nat.c,
131 we have a SIGCHLD handler installed that is called when something
132 happens to the target and notifies the GDB event loop. Whenever GDB
133 core decides to handle the event, and calls into linux-nat.c, we
134 process things as in sync mode, except that the we never block in
137 While processing an event, we may end up momentarily blocked in
138 waitpid calls. Those waitpid calls, while blocking, are guarantied to
139 return quickly. E.g., in all-stop mode, before reporting to the core
140 that an LWP hit a breakpoint, all LWPs are stopped by sending them
141 SIGSTOP, and synchronously waiting for the SIGSTOP to be reported.
142 Note that this is different from blocking indefinitely waiting for the
143 next event --- here, we're already handling an event.
148 We stop threads by sending a SIGSTOP. The use of SIGSTOP instead of another
149 signal is not entirely significant; we just need for a signal to be delivered,
150 so that we can intercept it. SIGSTOP's advantage is that it can not be
151 blocked. A disadvantage is that it is not a real-time signal, so it can only
152 be queued once; we do not keep track of other sources of SIGSTOP.
154 Two other signals that can't be blocked are SIGCONT and SIGKILL. But we can't
155 use them, because they have special behavior when the signal is generated -
156 not when it is delivered. SIGCONT resumes the entire thread group and SIGKILL
157 kills the entire thread group.
159 A delivered SIGSTOP would stop the entire thread group, not just the thread we
160 tkill'd. But we never let the SIGSTOP be delivered; we always intercept and
161 cancel it (by PTRACE_CONT without passing SIGSTOP).
163 We could use a real-time signal instead. This would solve those problems; we
164 could use PTRACE_GETSIGINFO to locate the specific stop signals sent by GDB.
165 But we would still have to have some support for SIGSTOP, since PTRACE_ATTACH
166 generates it, and there are races with trying to find a signal that is not
172 The case of a thread group (process) with 3 or more threads, and a
173 thread other than the leader execs is worth detailing:
175 On an exec, the Linux kernel destroys all threads except the execing
176 one in the thread group, and resets the execing thread's tid to the
177 tgid. No exit notification is sent for the execing thread -- from the
178 ptracer's perspective, it appears as though the execing thread just
179 vanishes. Until we reap all other threads except the leader and the
180 execing thread, the leader will be zombie, and the execing thread will
181 be in `D (disc sleep)' state. As soon as all other threads are
182 reaped, the execing thread changes its tid to the tgid, and the
183 previous (zombie) leader vanishes, giving place to the "new"
187 #define O_LARGEFILE 0
190 struct linux_nat_target
*linux_target
;
192 /* Does the current host support PTRACE_GETREGSET? */
193 enum tribool have_ptrace_getregset
= TRIBOOL_UNKNOWN
;
195 /* When true, print debug messages relating to the linux native target. */
197 static bool debug_linux_nat
;
199 /* Implement 'show debug linux-nat'. */
202 show_debug_linux_nat (struct ui_file
*file
, int from_tty
,
203 struct cmd_list_element
*c
, const char *value
)
205 gdb_printf (file
, _("Debugging of GNU/Linux native targets is %s.\n"),
209 /* Print a linux-nat debug statement. */
211 #define linux_nat_debug_printf(fmt, ...) \
212 debug_prefixed_printf_cond (debug_linux_nat, "linux-nat", fmt, ##__VA_ARGS__)
214 /* Print "linux-nat" enter/exit debug statements. */
216 #define LINUX_NAT_SCOPED_DEBUG_ENTER_EXIT \
217 scoped_debug_enter_exit (debug_linux_nat, "linux-nat")
219 struct simple_pid_list
223 struct simple_pid_list
*next
;
225 static struct simple_pid_list
*stopped_pids
;
227 /* Whether target_thread_events is in effect. */
228 static int report_thread_events
;
230 static int kill_lwp (int lwpid
, int signo
);
232 static int stop_callback (struct lwp_info
*lp
);
234 static void block_child_signals (sigset_t
*prev_mask
);
235 static void restore_child_signals_mask (sigset_t
*prev_mask
);
238 static struct lwp_info
*add_lwp (ptid_t ptid
);
239 static void purge_lwp_list (int pid
);
240 static void delete_lwp (ptid_t ptid
);
241 static struct lwp_info
*find_lwp_pid (ptid_t ptid
);
243 static int lwp_status_pending_p (struct lwp_info
*lp
);
245 static void save_stop_reason (struct lwp_info
*lp
);
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 ();
261 /* See nat/linux-nat.h. */
264 ptid_of_lwp (struct lwp_info
*lwp
)
269 /* See nat/linux-nat.h. */
272 lwp_set_arch_private_info (struct lwp_info
*lwp
,
273 struct arch_lwp_info
*info
)
275 lwp
->arch_private
= info
;
278 /* See nat/linux-nat.h. */
280 struct arch_lwp_info
*
281 lwp_arch_private_info (struct lwp_info
*lwp
)
283 return lwp
->arch_private
;
286 /* See nat/linux-nat.h. */
289 lwp_is_stopped (struct lwp_info
*lwp
)
294 /* See nat/linux-nat.h. */
296 enum target_stop_reason
297 lwp_stop_reason (struct lwp_info
*lwp
)
299 return lwp
->stop_reason
;
302 /* See nat/linux-nat.h. */
305 lwp_is_stepping (struct lwp_info
*lwp
)
311 /* Trivial list manipulation functions to keep track of a list of
312 new stopped processes. */
314 add_to_pid_list (struct simple_pid_list
**listp
, int pid
, int status
)
316 struct simple_pid_list
*new_pid
= XNEW (struct simple_pid_list
);
319 new_pid
->status
= status
;
320 new_pid
->next
= *listp
;
325 pull_pid_from_list (struct simple_pid_list
**listp
, int pid
, int *statusp
)
327 struct simple_pid_list
**p
;
329 for (p
= listp
; *p
!= NULL
; p
= &(*p
)->next
)
330 if ((*p
)->pid
== pid
)
332 struct simple_pid_list
*next
= (*p
)->next
;
334 *statusp
= (*p
)->status
;
342 /* Return the ptrace options that we want to try to enable. */
345 linux_nat_ptrace_options (int attached
)
350 options
|= PTRACE_O_EXITKILL
;
352 options
|= (PTRACE_O_TRACESYSGOOD
353 | PTRACE_O_TRACEVFORKDONE
354 | PTRACE_O_TRACEVFORK
356 | PTRACE_O_TRACEEXEC
);
361 /* Initialize ptrace and procfs warnings and check for supported
362 ptrace features given PID.
364 ATTACHED should be nonzero iff we attached to the inferior. */
367 linux_init_ptrace_procfs (pid_t pid
, int attached
)
369 int options
= linux_nat_ptrace_options (attached
);
371 linux_enable_event_reporting (pid
, options
);
372 linux_ptrace_init_warnings ();
373 linux_proc_init_warnings ();
376 linux_nat_target::~linux_nat_target ()
380 linux_nat_target::post_attach (int pid
)
382 linux_init_ptrace_procfs (pid
, 1);
385 /* Implement the virtual inf_ptrace_target::post_startup_inferior method. */
388 linux_nat_target::post_startup_inferior (ptid_t ptid
)
390 linux_init_ptrace_procfs (ptid
.pid (), 0);
393 /* Return the number of known LWPs in the tgid given by PID. */
400 for (const lwp_info
*lp ATTRIBUTE_UNUSED
: all_lwps ())
401 if (lp
->ptid
.pid () == pid
)
407 /* Deleter for lwp_info unique_ptr specialisation. */
411 void operator() (struct lwp_info
*lwp
) const
413 delete_lwp (lwp
->ptid
);
417 /* A unique_ptr specialisation for lwp_info. */
419 typedef std::unique_ptr
<struct lwp_info
, lwp_deleter
> lwp_info_up
;
421 /* Target hook for follow_fork. */
424 linux_nat_target::follow_fork (inferior
*child_inf
, ptid_t child_ptid
,
425 target_waitkind fork_kind
, bool follow_child
,
428 inf_ptrace_target::follow_fork (child_inf
, child_ptid
, fork_kind
,
429 follow_child
, detach_fork
);
433 bool has_vforked
= fork_kind
== TARGET_WAITKIND_VFORKED
;
434 ptid_t parent_ptid
= inferior_ptid
;
435 int parent_pid
= parent_ptid
.lwp ();
436 int child_pid
= child_ptid
.lwp ();
438 /* We're already attached to the parent, by default. */
439 lwp_info
*child_lp
= add_lwp (child_ptid
);
440 child_lp
->stopped
= 1;
441 child_lp
->last_resume_kind
= resume_stop
;
443 /* Detach new forked process? */
446 int child_stop_signal
= 0;
447 bool detach_child
= true;
449 /* Move CHILD_LP into a unique_ptr and clear the source pointer
450 to prevent us doing anything stupid with it. */
451 lwp_info_up
child_lp_ptr (child_lp
);
454 linux_target
->low_prepare_to_resume (child_lp_ptr
.get ());
456 /* When debugging an inferior in an architecture that supports
457 hardware single stepping on a kernel without commit
458 6580807da14c423f0d0a708108e6df6ebc8bc83d, the vfork child
459 process starts with the TIF_SINGLESTEP/X86_EFLAGS_TF bits
460 set if the parent process had them set.
461 To work around this, single step the child process
462 once before detaching to clear the flags. */
464 /* Note that we consult the parent's architecture instead of
465 the child's because there's no inferior for the child at
467 if (!gdbarch_software_single_step_p (target_thread_architecture
472 linux_disable_event_reporting (child_pid
);
473 if (ptrace (PTRACE_SINGLESTEP
, child_pid
, 0, 0) < 0)
474 perror_with_name (_("Couldn't do single step"));
475 if (my_waitpid (child_pid
, &status
, 0) < 0)
476 perror_with_name (_("Couldn't wait vfork process"));
479 detach_child
= WIFSTOPPED (status
);
480 child_stop_signal
= WSTOPSIG (status
);
486 int signo
= child_stop_signal
;
489 && !signal_pass_state (gdb_signal_from_host (signo
)))
491 ptrace (PTRACE_DETACH
, child_pid
, 0, signo
);
493 close_proc_mem_file (child_pid
);
499 lwp_info
*parent_lp
= find_lwp_pid (parent_ptid
);
500 linux_nat_debug_printf ("waiting for VFORK_DONE on %d", parent_pid
);
501 parent_lp
->stopped
= 1;
503 /* We'll handle the VFORK_DONE event like any other
504 event, in target_wait. */
509 struct lwp_info
*child_lp
;
511 child_lp
= add_lwp (child_ptid
);
512 child_lp
->stopped
= 1;
513 child_lp
->last_resume_kind
= resume_stop
;
519 linux_nat_target::insert_fork_catchpoint (int pid
)
525 linux_nat_target::remove_fork_catchpoint (int pid
)
531 linux_nat_target::insert_vfork_catchpoint (int pid
)
537 linux_nat_target::remove_vfork_catchpoint (int pid
)
543 linux_nat_target::insert_exec_catchpoint (int pid
)
549 linux_nat_target::remove_exec_catchpoint (int pid
)
555 linux_nat_target::set_syscall_catchpoint (int pid
, bool needed
, int any_count
,
556 gdb::array_view
<const int> syscall_counts
)
558 /* On GNU/Linux, we ignore the arguments. It means that we only
559 enable the syscall catchpoints, but do not disable them.
561 Also, we do not use the `syscall_counts' information because we do not
562 filter system calls here. We let GDB do the logic for us. */
566 /* List of known LWPs, keyed by LWP PID. This speeds up the common
567 case of mapping a PID returned from the kernel to our corresponding
568 lwp_info data structure. */
569 static htab_t lwp_lwpid_htab
;
571 /* Calculate a hash from a lwp_info's LWP PID. */
574 lwp_info_hash (const void *ap
)
576 const struct lwp_info
*lp
= (struct lwp_info
*) ap
;
577 pid_t pid
= lp
->ptid
.lwp ();
579 return iterative_hash_object (pid
, 0);
582 /* Equality function for the lwp_info hash table. Compares the LWP's
586 lwp_lwpid_htab_eq (const void *a
, const void *b
)
588 const struct lwp_info
*entry
= (const struct lwp_info
*) a
;
589 const struct lwp_info
*element
= (const struct lwp_info
*) b
;
591 return entry
->ptid
.lwp () == element
->ptid
.lwp ();
594 /* Create the lwp_lwpid_htab hash table. */
597 lwp_lwpid_htab_create (void)
599 lwp_lwpid_htab
= htab_create (100, lwp_info_hash
, lwp_lwpid_htab_eq
, NULL
);
602 /* Add LP to the hash table. */
605 lwp_lwpid_htab_add_lwp (struct lwp_info
*lp
)
609 slot
= htab_find_slot (lwp_lwpid_htab
, lp
, INSERT
);
610 gdb_assert (slot
!= NULL
&& *slot
== NULL
);
614 /* Head of doubly-linked list of known LWPs. Sorted by reverse
615 creation order. This order is assumed in some cases. E.g.,
616 reaping status after killing alls lwps of a process: the leader LWP
617 must be reaped last. */
619 static intrusive_list
<lwp_info
> lwp_list
;
621 /* See linux-nat.h. */
626 return lwp_info_range (lwp_list
.begin ());
629 /* See linux-nat.h. */
634 return lwp_info_safe_range (lwp_list
.begin ());
637 /* Add LP to sorted-by-reverse-creation-order doubly-linked list. */
640 lwp_list_add (struct lwp_info
*lp
)
642 lwp_list
.push_front (*lp
);
645 /* Remove LP from sorted-by-reverse-creation-order doubly-linked
649 lwp_list_remove (struct lwp_info
*lp
)
651 /* Remove from sorted-by-creation-order list. */
652 lwp_list
.erase (lwp_list
.iterator_to (*lp
));
657 /* Signal mask for use with sigsuspend in linux_nat_wait, initialized in
658 _initialize_linux_nat. */
659 static sigset_t suspend_mask
;
661 /* Signals to block to make that sigsuspend work. */
662 static sigset_t blocked_mask
;
664 /* SIGCHLD action. */
665 static struct sigaction sigchld_action
;
667 /* Block child signals (SIGCHLD and linux threads signals), and store
668 the previous mask in PREV_MASK. */
671 block_child_signals (sigset_t
*prev_mask
)
673 /* Make sure SIGCHLD is blocked. */
674 if (!sigismember (&blocked_mask
, SIGCHLD
))
675 sigaddset (&blocked_mask
, SIGCHLD
);
677 gdb_sigmask (SIG_BLOCK
, &blocked_mask
, prev_mask
);
680 /* Restore child signals mask, previously returned by
681 block_child_signals. */
684 restore_child_signals_mask (sigset_t
*prev_mask
)
686 gdb_sigmask (SIG_SETMASK
, prev_mask
, NULL
);
689 /* Mask of signals to pass directly to the inferior. */
690 static sigset_t pass_mask
;
692 /* Update signals to pass to the inferior. */
694 linux_nat_target::pass_signals
695 (gdb::array_view
<const unsigned char> pass_signals
)
699 sigemptyset (&pass_mask
);
701 for (signo
= 1; signo
< NSIG
; signo
++)
703 int target_signo
= gdb_signal_from_host (signo
);
704 if (target_signo
< pass_signals
.size () && pass_signals
[target_signo
])
705 sigaddset (&pass_mask
, signo
);
711 /* Prototypes for local functions. */
712 static int stop_wait_callback (struct lwp_info
*lp
);
713 static int resume_stopped_resumed_lwps (struct lwp_info
*lp
, const ptid_t wait_ptid
);
714 static int check_ptrace_stopped_lwp_gone (struct lwp_info
*lp
);
718 /* Destroy and free LP. */
720 lwp_info::~lwp_info ()
722 /* Let the arch specific bits release arch_lwp_info. */
723 linux_target
->low_delete_thread (this->arch_private
);
726 /* Traversal function for purge_lwp_list. */
729 lwp_lwpid_htab_remove_pid (void **slot
, void *info
)
731 struct lwp_info
*lp
= (struct lwp_info
*) *slot
;
732 int pid
= *(int *) info
;
734 if (lp
->ptid
.pid () == pid
)
736 htab_clear_slot (lwp_lwpid_htab
, slot
);
737 lwp_list_remove (lp
);
744 /* Remove all LWPs belong to PID from the lwp list. */
747 purge_lwp_list (int pid
)
749 htab_traverse_noresize (lwp_lwpid_htab
, lwp_lwpid_htab_remove_pid
, &pid
);
752 /* Add the LWP specified by PTID to the list. PTID is the first LWP
753 in the process. Return a pointer to the structure describing the
756 This differs from add_lwp in that we don't let the arch specific
757 bits know about this new thread. Current clients of this callback
758 take the opportunity to install watchpoints in the new thread, and
759 we shouldn't do that for the first thread. If we're spawning a
760 child ("run"), the thread executes the shell wrapper first, and we
761 shouldn't touch it until it execs the program we want to debug.
762 For "attach", it'd be okay to call the callback, but it's not
763 necessary, because watchpoints can't yet have been inserted into
766 static struct lwp_info
*
767 add_initial_lwp (ptid_t ptid
)
769 gdb_assert (ptid
.lwp_p ());
771 lwp_info
*lp
= new lwp_info (ptid
);
774 /* Add to sorted-by-reverse-creation-order list. */
777 /* Add to keyed-by-pid htab. */
778 lwp_lwpid_htab_add_lwp (lp
);
783 /* Add the LWP specified by PID to the list. Return a pointer to the
784 structure describing the new LWP. The LWP should already be
787 static struct lwp_info
*
788 add_lwp (ptid_t ptid
)
792 lp
= add_initial_lwp (ptid
);
794 /* Let the arch specific bits know about this new thread. Current
795 clients of this callback take the opportunity to install
796 watchpoints in the new thread. We don't do this for the first
797 thread though. See add_initial_lwp. */
798 linux_target
->low_new_thread (lp
);
803 /* Remove the LWP specified by PID from the list. */
806 delete_lwp (ptid_t ptid
)
808 lwp_info
dummy (ptid
);
810 void **slot
= htab_find_slot (lwp_lwpid_htab
, &dummy
, NO_INSERT
);
814 lwp_info
*lp
= *(struct lwp_info
**) slot
;
815 gdb_assert (lp
!= NULL
);
817 htab_clear_slot (lwp_lwpid_htab
, slot
);
819 /* Remove from sorted-by-creation-order list. */
820 lwp_list_remove (lp
);
826 /* Return a pointer to the structure describing the LWP corresponding
827 to PID. If no corresponding LWP could be found, return NULL. */
829 static struct lwp_info
*
830 find_lwp_pid (ptid_t ptid
)
839 lwp_info
dummy (ptid_t (0, lwp
));
840 return (struct lwp_info
*) htab_find (lwp_lwpid_htab
, &dummy
);
843 /* See nat/linux-nat.h. */
846 iterate_over_lwps (ptid_t filter
,
847 gdb::function_view
<iterate_over_lwps_ftype
> callback
)
849 for (lwp_info
*lp
: all_lwps_safe ())
851 if (lp
->ptid
.matches (filter
))
853 if (callback (lp
) != 0)
861 /* Update our internal state when changing from one checkpoint to
862 another indicated by NEW_PTID. We can only switch single-threaded
863 applications, so we only create one new LWP, and the previous list
867 linux_nat_switch_fork (ptid_t new_ptid
)
871 purge_lwp_list (inferior_ptid
.pid ());
873 lp
= add_lwp (new_ptid
);
876 /* This changes the thread's ptid while preserving the gdb thread
877 num. Also changes the inferior pid, while preserving the
879 thread_change_ptid (linux_target
, inferior_ptid
, new_ptid
);
881 /* We've just told GDB core that the thread changed target id, but,
882 in fact, it really is a different thread, with different register
884 registers_changed ();
887 /* Handle the exit of a single thread LP. */
890 exit_lwp (struct lwp_info
*lp
)
892 struct thread_info
*th
= find_thread_ptid (linux_target
, lp
->ptid
);
896 if (print_thread_events
)
897 gdb_printf (_("[%s exited]\n"),
898 target_pid_to_str (lp
->ptid
).c_str ());
903 delete_lwp (lp
->ptid
);
906 /* Wait for the LWP specified by LP, which we have just attached to.
907 Returns a wait status for that LWP, to cache. */
910 linux_nat_post_attach_wait (ptid_t ptid
, int *signalled
)
912 pid_t new_pid
, pid
= ptid
.lwp ();
915 if (linux_proc_pid_is_stopped (pid
))
917 linux_nat_debug_printf ("Attaching to a stopped process");
919 /* The process is definitely stopped. It is in a job control
920 stop, unless the kernel predates the TASK_STOPPED /
921 TASK_TRACED distinction, in which case it might be in a
922 ptrace stop. Make sure it is in a ptrace stop; from there we
923 can kill it, signal it, et cetera.
925 First make sure there is a pending SIGSTOP. Since we are
926 already attached, the process can not transition from stopped
927 to running without a PTRACE_CONT; so we know this signal will
928 go into the queue. The SIGSTOP generated by PTRACE_ATTACH is
929 probably already in the queue (unless this kernel is old
930 enough to use TASK_STOPPED for ptrace stops); but since SIGSTOP
931 is not an RT signal, it can only be queued once. */
932 kill_lwp (pid
, SIGSTOP
);
934 /* Finally, resume the stopped process. This will deliver the SIGSTOP
935 (or a higher priority signal, just like normal PTRACE_ATTACH). */
936 ptrace (PTRACE_CONT
, pid
, 0, 0);
939 /* Make sure the initial process is stopped. The user-level threads
940 layer might want to poke around in the inferior, and that won't
941 work if things haven't stabilized yet. */
942 new_pid
= my_waitpid (pid
, &status
, __WALL
);
943 gdb_assert (pid
== new_pid
);
945 if (!WIFSTOPPED (status
))
947 /* The pid we tried to attach has apparently just exited. */
948 linux_nat_debug_printf ("Failed to stop %d: %s", pid
,
949 status_to_str (status
).c_str ());
953 if (WSTOPSIG (status
) != SIGSTOP
)
956 linux_nat_debug_printf ("Received %s after attaching",
957 status_to_str (status
).c_str ());
964 linux_nat_target::create_inferior (const char *exec_file
,
965 const std::string
&allargs
,
966 char **env
, int from_tty
)
968 maybe_disable_address_space_randomization restore_personality
969 (disable_randomization
);
971 /* The fork_child mechanism is synchronous and calls target_wait, so
972 we have to mask the async mode. */
974 /* Make sure we report all signals during startup. */
977 inf_ptrace_target::create_inferior (exec_file
, allargs
, env
, from_tty
);
979 open_proc_mem_file (inferior_ptid
);
982 /* Callback for linux_proc_attach_tgid_threads. Attach to PTID if not
983 already attached. Returns true if a new LWP is found, false
987 attach_proc_task_lwp_callback (ptid_t ptid
)
991 /* Ignore LWPs we're already attached to. */
992 lp
= find_lwp_pid (ptid
);
995 int lwpid
= ptid
.lwp ();
997 if (ptrace (PTRACE_ATTACH
, lwpid
, 0, 0) < 0)
1001 /* Be quiet if we simply raced with the thread exiting.
1002 EPERM is returned if the thread's task still exists, and
1003 is marked as exited or zombie, as well as other
1004 conditions, so in that case, confirm the status in
1005 /proc/PID/status. */
1007 || (err
== EPERM
&& linux_proc_pid_is_gone (lwpid
)))
1009 linux_nat_debug_printf
1010 ("Cannot attach to lwp %d: thread is gone (%d: %s)",
1011 lwpid
, err
, safe_strerror (err
));
1017 = linux_ptrace_attach_fail_reason_string (ptid
, err
);
1019 warning (_("Cannot attach to lwp %d: %s"),
1020 lwpid
, reason
.c_str ());
1025 linux_nat_debug_printf ("PTRACE_ATTACH %s, 0, 0 (OK)",
1026 ptid
.to_string ().c_str ());
1028 lp
= add_lwp (ptid
);
1030 /* The next time we wait for this LWP we'll see a SIGSTOP as
1031 PTRACE_ATTACH brings it to a halt. */
1034 /* We need to wait for a stop before being able to make the
1035 next ptrace call on this LWP. */
1036 lp
->must_set_ptrace_flags
= 1;
1038 /* So that wait collects the SIGSTOP. */
1041 /* Also add the LWP to gdb's thread list, in case a
1042 matching libthread_db is not found (or the process uses
1044 add_thread (linux_target
, lp
->ptid
);
1045 set_running (linux_target
, lp
->ptid
, true);
1046 set_executing (linux_target
, lp
->ptid
, true);
1055 linux_nat_target::attach (const char *args
, int from_tty
)
1057 struct lwp_info
*lp
;
1061 /* Make sure we report all signals during attach. */
1066 inf_ptrace_target::attach (args
, from_tty
);
1068 catch (const gdb_exception_error
&ex
)
1070 pid_t pid
= parse_pid_to_attach (args
);
1071 std::string reason
= linux_ptrace_attach_fail_reason (pid
);
1073 if (!reason
.empty ())
1074 throw_error (ex
.error
, "warning: %s\n%s", reason
.c_str (),
1077 throw_error (ex
.error
, "%s", ex
.what ());
1080 /* The ptrace base target adds the main thread with (pid,0,0)
1081 format. Decorate it with lwp info. */
1082 ptid
= ptid_t (inferior_ptid
.pid (),
1083 inferior_ptid
.pid ());
1084 thread_change_ptid (linux_target
, inferior_ptid
, ptid
);
1086 /* Add the initial process as the first LWP to the list. */
1087 lp
= add_initial_lwp (ptid
);
1089 status
= linux_nat_post_attach_wait (lp
->ptid
, &lp
->signalled
);
1090 if (!WIFSTOPPED (status
))
1092 if (WIFEXITED (status
))
1094 int exit_code
= WEXITSTATUS (status
);
1096 target_terminal::ours ();
1097 target_mourn_inferior (inferior_ptid
);
1099 error (_("Unable to attach: program exited normally."));
1101 error (_("Unable to attach: program exited with code %d."),
1104 else if (WIFSIGNALED (status
))
1106 enum gdb_signal signo
;
1108 target_terminal::ours ();
1109 target_mourn_inferior (inferior_ptid
);
1111 signo
= gdb_signal_from_host (WTERMSIG (status
));
1112 error (_("Unable to attach: program terminated with signal "
1114 gdb_signal_to_name (signo
),
1115 gdb_signal_to_string (signo
));
1118 internal_error (__FILE__
, __LINE__
,
1119 _("unexpected status %d for PID %ld"),
1120 status
, (long) ptid
.lwp ());
1125 open_proc_mem_file (lp
->ptid
);
1127 /* Save the wait status to report later. */
1129 linux_nat_debug_printf ("waitpid %ld, saving status %s",
1130 (long) lp
->ptid
.pid (),
1131 status_to_str (status
).c_str ());
1133 lp
->status
= status
;
1135 /* We must attach to every LWP. If /proc is mounted, use that to
1136 find them now. The inferior may be using raw clone instead of
1137 using pthreads. But even if it is using pthreads, thread_db
1138 walks structures in the inferior's address space to find the list
1139 of threads/LWPs, and those structures may well be corrupted.
1140 Note that once thread_db is loaded, we'll still use it to list
1141 threads and associate pthread info with each LWP. */
1142 linux_proc_attach_tgid_threads (lp
->ptid
.pid (),
1143 attach_proc_task_lwp_callback
);
1146 /* Ptrace-detach the thread with pid PID. */
1149 detach_one_pid (int pid
, int signo
)
1151 if (ptrace (PTRACE_DETACH
, pid
, 0, signo
) < 0)
1153 int save_errno
= errno
;
1155 /* We know the thread exists, so ESRCH must mean the lwp is
1156 zombie. This can happen if one of the already-detached
1157 threads exits the whole thread group. In that case we're
1158 still attached, and must reap the lwp. */
1159 if (save_errno
== ESRCH
)
1163 ret
= my_waitpid (pid
, &status
, __WALL
);
1166 warning (_("Couldn't reap LWP %d while detaching: %s"),
1167 pid
, safe_strerror (errno
));
1169 else if (!WIFEXITED (status
) && !WIFSIGNALED (status
))
1171 warning (_("Reaping LWP %d while detaching "
1172 "returned unexpected status 0x%x"),
1177 error (_("Can't detach %d: %s"),
1178 pid
, safe_strerror (save_errno
));
1181 linux_nat_debug_printf ("PTRACE_DETACH (%d, %s, 0) (OK)",
1182 pid
, strsignal (signo
));
1185 /* Get pending signal of THREAD as a host signal number, for detaching
1186 purposes. This is the signal the thread last stopped for, which we
1187 need to deliver to the thread when detaching, otherwise, it'd be
1191 get_detach_signal (struct lwp_info
*lp
)
1193 enum gdb_signal signo
= GDB_SIGNAL_0
;
1195 /* If we paused threads momentarily, we may have stored pending
1196 events in lp->status or lp->waitstatus (see stop_wait_callback),
1197 and GDB core hasn't seen any signal for those threads.
1198 Otherwise, the last signal reported to the core is found in the
1199 thread object's stop_signal.
1201 There's a corner case that isn't handled here at present. Only
1202 if the thread stopped with a TARGET_WAITKIND_STOPPED does
1203 stop_signal make sense as a real signal to pass to the inferior.
1204 Some catchpoint related events, like
1205 TARGET_WAITKIND_(V)FORK|EXEC|SYSCALL, have their stop_signal set
1206 to GDB_SIGNAL_SIGTRAP when the catchpoint triggers. But,
1207 those traps are debug API (ptrace in our case) related and
1208 induced; the inferior wouldn't see them if it wasn't being
1209 traced. Hence, we should never pass them to the inferior, even
1210 when set to pass state. Since this corner case isn't handled by
1211 infrun.c when proceeding with a signal, for consistency, neither
1212 do we handle it here (or elsewhere in the file we check for
1213 signal pass state). Normally SIGTRAP isn't set to pass state, so
1214 this is really a corner case. */
1216 if (lp
->waitstatus
.kind () != TARGET_WAITKIND_IGNORE
)
1217 signo
= GDB_SIGNAL_0
; /* a pending ptrace event, not a real signal. */
1218 else if (lp
->status
)
1219 signo
= gdb_signal_from_host (WSTOPSIG (lp
->status
));
1222 struct thread_info
*tp
= find_thread_ptid (linux_target
, lp
->ptid
);
1224 if (target_is_non_stop_p () && !tp
->executing ())
1226 if (tp
->has_pending_waitstatus ())
1228 /* If the thread has a pending event, and it was stopped with a
1229 signal, use that signal to resume it. If it has a pending
1230 event of another kind, it was not stopped with a signal, so
1231 resume it without a signal. */
1232 if (tp
->pending_waitstatus ().kind () == TARGET_WAITKIND_STOPPED
)
1233 signo
= tp
->pending_waitstatus ().sig ();
1235 signo
= GDB_SIGNAL_0
;
1238 signo
= tp
->stop_signal ();
1240 else if (!target_is_non_stop_p ())
1243 process_stratum_target
*last_target
;
1245 get_last_target_status (&last_target
, &last_ptid
, nullptr);
1247 if (last_target
== linux_target
1248 && lp
->ptid
.lwp () == last_ptid
.lwp ())
1249 signo
= tp
->stop_signal ();
1253 if (signo
== GDB_SIGNAL_0
)
1255 linux_nat_debug_printf ("lwp %s has no pending signal",
1256 lp
->ptid
.to_string ().c_str ());
1258 else if (!signal_pass_state (signo
))
1260 linux_nat_debug_printf
1261 ("lwp %s had signal %s but it is in no pass state",
1262 lp
->ptid
.to_string ().c_str (), gdb_signal_to_string (signo
));
1266 linux_nat_debug_printf ("lwp %s has pending signal %s",
1267 lp
->ptid
.to_string ().c_str (),
1268 gdb_signal_to_string (signo
));
1270 return gdb_signal_to_host (signo
);
1276 /* Detach from LP. If SIGNO_P is non-NULL, then it points to the
1277 signal number that should be passed to the LWP when detaching.
1278 Otherwise pass any pending signal the LWP may have, if any. */
1281 detach_one_lwp (struct lwp_info
*lp
, int *signo_p
)
1283 int lwpid
= lp
->ptid
.lwp ();
1286 gdb_assert (lp
->status
== 0 || WIFSTOPPED (lp
->status
));
1288 /* If the lwp/thread we are about to detach has a pending fork event,
1289 there is a process GDB is attached to that the core of GDB doesn't know
1290 about. Detach from it. */
1292 /* Check in lwp_info::status. */
1293 if (WIFSTOPPED (lp
->status
) && linux_is_extended_waitstatus (lp
->status
))
1295 int event
= linux_ptrace_get_extended_event (lp
->status
);
1297 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
)
1299 unsigned long child_pid
;
1300 int ret
= ptrace (PTRACE_GETEVENTMSG
, lp
->ptid
.lwp (), 0, &child_pid
);
1302 detach_one_pid (child_pid
, 0);
1304 perror_warning_with_name (_("Failed to detach fork child"));
1308 /* Check in lwp_info::waitstatus. */
1309 if (lp
->waitstatus
.kind () == TARGET_WAITKIND_VFORKED
1310 || lp
->waitstatus
.kind () == TARGET_WAITKIND_FORKED
)
1311 detach_one_pid (lp
->waitstatus
.child_ptid ().pid (), 0);
1314 /* Check in thread_info::pending_waitstatus. */
1315 thread_info
*tp
= find_thread_ptid (linux_target
, lp
->ptid
);
1316 if (tp
->has_pending_waitstatus ())
1318 const target_waitstatus
&ws
= tp
->pending_waitstatus ();
1320 if (ws
.kind () == TARGET_WAITKIND_VFORKED
1321 || ws
.kind () == TARGET_WAITKIND_FORKED
)
1322 detach_one_pid (ws
.child_ptid ().pid (), 0);
1325 /* Check in thread_info::pending_follow. */
1326 if (tp
->pending_follow
.kind () == TARGET_WAITKIND_VFORKED
1327 || tp
->pending_follow
.kind () == TARGET_WAITKIND_FORKED
)
1328 detach_one_pid (tp
->pending_follow
.child_ptid ().pid (), 0);
1330 if (lp
->status
!= 0)
1331 linux_nat_debug_printf ("Pending %s for %s on detach.",
1332 strsignal (WSTOPSIG (lp
->status
)),
1333 lp
->ptid
.to_string ().c_str ());
1335 /* If there is a pending SIGSTOP, get rid of it. */
1338 linux_nat_debug_printf ("Sending SIGCONT to %s",
1339 lp
->ptid
.to_string ().c_str ());
1341 kill_lwp (lwpid
, SIGCONT
);
1345 if (signo_p
== NULL
)
1347 /* Pass on any pending signal for this LWP. */
1348 signo
= get_detach_signal (lp
);
1353 /* Preparing to resume may try to write registers, and fail if the
1354 lwp is zombie. If that happens, ignore the error. We'll handle
1355 it below, when detach fails with ESRCH. */
1358 linux_target
->low_prepare_to_resume (lp
);
1360 catch (const gdb_exception_error
&ex
)
1362 if (!check_ptrace_stopped_lwp_gone (lp
))
1366 detach_one_pid (lwpid
, signo
);
1368 delete_lwp (lp
->ptid
);
1372 detach_callback (struct lwp_info
*lp
)
1374 /* We don't actually detach from the thread group leader just yet.
1375 If the thread group exits, we must reap the zombie clone lwps
1376 before we're able to reap the leader. */
1377 if (lp
->ptid
.lwp () != lp
->ptid
.pid ())
1378 detach_one_lwp (lp
, NULL
);
1383 linux_nat_target::detach (inferior
*inf
, int from_tty
)
1385 struct lwp_info
*main_lwp
;
1388 /* Don't unregister from the event loop, as there may be other
1389 inferiors running. */
1391 /* Stop all threads before detaching. ptrace requires that the
1392 thread is stopped to successfully detach. */
1393 iterate_over_lwps (ptid_t (pid
), stop_callback
);
1394 /* ... and wait until all of them have reported back that
1395 they're no longer running. */
1396 iterate_over_lwps (ptid_t (pid
), stop_wait_callback
);
1398 /* We can now safely remove breakpoints. We don't this in earlier
1399 in common code because this target doesn't currently support
1400 writing memory while the inferior is running. */
1401 remove_breakpoints_inf (current_inferior ());
1403 iterate_over_lwps (ptid_t (pid
), detach_callback
);
1405 /* Only the initial process should be left right now. */
1406 gdb_assert (num_lwps (pid
) == 1);
1408 main_lwp
= find_lwp_pid (ptid_t (pid
));
1410 if (forks_exist_p ())
1412 /* Multi-fork case. The current inferior_ptid is being detached
1413 from, but there are other viable forks to debug. Detach from
1414 the current fork, and context-switch to the first
1416 linux_fork_detach (from_tty
);
1420 target_announce_detach (from_tty
);
1422 /* Pass on any pending signal for the last LWP. */
1423 int signo
= get_detach_signal (main_lwp
);
1425 detach_one_lwp (main_lwp
, &signo
);
1427 detach_success (inf
);
1430 close_proc_mem_file (pid
);
1433 /* Resume execution of the inferior process. If STEP is nonzero,
1434 single-step it. If SIGNAL is nonzero, give it that signal. */
1437 linux_resume_one_lwp_throw (struct lwp_info
*lp
, int step
,
1438 enum gdb_signal signo
)
1442 /* stop_pc doubles as the PC the LWP had when it was last resumed.
1443 We only presently need that if the LWP is stepped though (to
1444 handle the case of stepping a breakpoint instruction). */
1447 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
1449 lp
->stop_pc
= regcache_read_pc (regcache
);
1454 linux_target
->low_prepare_to_resume (lp
);
1455 linux_target
->low_resume (lp
->ptid
, step
, signo
);
1457 /* Successfully resumed. Clear state that no longer makes sense,
1458 and mark the LWP as running. Must not do this before resuming
1459 otherwise if that fails other code will be confused. E.g., we'd
1460 later try to stop the LWP and hang forever waiting for a stop
1461 status. Note that we must not throw after this is cleared,
1462 otherwise handle_zombie_lwp_error would get confused. */
1465 lp
->stop_reason
= TARGET_STOPPED_BY_NO_REASON
;
1466 registers_changed_ptid (linux_target
, lp
->ptid
);
1469 /* Called when we try to resume a stopped LWP and that errors out. If
1470 the LWP is no longer in ptrace-stopped state (meaning it's zombie,
1471 or about to become), discard the error, clear any pending status
1472 the LWP may have, and return true (we'll collect the exit status
1473 soon enough). Otherwise, return false. */
1476 check_ptrace_stopped_lwp_gone (struct lwp_info
*lp
)
1478 /* If we get an error after resuming the LWP successfully, we'd
1479 confuse !T state for the LWP being gone. */
1480 gdb_assert (lp
->stopped
);
1482 /* We can't just check whether the LWP is in 'Z (Zombie)' state,
1483 because even if ptrace failed with ESRCH, the tracee may be "not
1484 yet fully dead", but already refusing ptrace requests. In that
1485 case the tracee has 'R (Running)' state for a little bit
1486 (observed in Linux 3.18). See also the note on ESRCH in the
1487 ptrace(2) man page. Instead, check whether the LWP has any state
1488 other than ptrace-stopped. */
1490 /* Don't assume anything if /proc/PID/status can't be read. */
1491 if (linux_proc_pid_is_trace_stopped_nowarn (lp
->ptid
.lwp ()) == 0)
1493 lp
->stop_reason
= TARGET_STOPPED_BY_NO_REASON
;
1495 lp
->waitstatus
.set_ignore ();
1501 /* Like linux_resume_one_lwp_throw, but no error is thrown if the LWP
1502 disappears while we try to resume it. */
1505 linux_resume_one_lwp (struct lwp_info
*lp
, int step
, enum gdb_signal signo
)
1509 linux_resume_one_lwp_throw (lp
, step
, signo
);
1511 catch (const gdb_exception_error
&ex
)
1513 if (!check_ptrace_stopped_lwp_gone (lp
))
1521 resume_lwp (struct lwp_info
*lp
, int step
, enum gdb_signal signo
)
1525 struct inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
1527 if (inf
->vfork_child
!= NULL
)
1529 linux_nat_debug_printf ("Not resuming %s (vfork parent)",
1530 lp
->ptid
.to_string ().c_str ());
1532 else if (!lwp_status_pending_p (lp
))
1534 linux_nat_debug_printf ("Resuming sibling %s, %s, %s",
1535 lp
->ptid
.to_string ().c_str (),
1536 (signo
!= GDB_SIGNAL_0
1537 ? strsignal (gdb_signal_to_host (signo
))
1539 step
? "step" : "resume");
1541 linux_resume_one_lwp (lp
, step
, signo
);
1545 linux_nat_debug_printf ("Not resuming sibling %s (has pending)",
1546 lp
->ptid
.to_string ().c_str ());
1550 linux_nat_debug_printf ("Not resuming sibling %s (not stopped)",
1551 lp
->ptid
.to_string ().c_str ());
1554 /* Callback for iterate_over_lwps. If LWP is EXCEPT, do nothing.
1555 Resume LWP with the last stop signal, if it is in pass state. */
1558 linux_nat_resume_callback (struct lwp_info
*lp
, struct lwp_info
*except
)
1560 enum gdb_signal signo
= GDB_SIGNAL_0
;
1567 struct thread_info
*thread
;
1569 thread
= find_thread_ptid (linux_target
, lp
->ptid
);
1572 signo
= thread
->stop_signal ();
1573 thread
->set_stop_signal (GDB_SIGNAL_0
);
1577 resume_lwp (lp
, 0, signo
);
1582 resume_clear_callback (struct lwp_info
*lp
)
1585 lp
->last_resume_kind
= resume_stop
;
1590 resume_set_callback (struct lwp_info
*lp
)
1593 lp
->last_resume_kind
= resume_continue
;
1598 linux_nat_target::resume (ptid_t ptid
, int step
, enum gdb_signal signo
)
1600 struct lwp_info
*lp
;
1603 linux_nat_debug_printf ("Preparing to %s %s, %s, inferior_ptid %s",
1604 step
? "step" : "resume",
1605 ptid
.to_string ().c_str (),
1606 (signo
!= GDB_SIGNAL_0
1607 ? strsignal (gdb_signal_to_host (signo
)) : "0"),
1608 inferior_ptid
.to_string ().c_str ());
1610 /* A specific PTID means `step only this process id'. */
1611 resume_many
= (minus_one_ptid
== ptid
1614 /* Mark the lwps we're resuming as resumed and update their
1615 last_resume_kind to resume_continue. */
1616 iterate_over_lwps (ptid
, resume_set_callback
);
1618 /* See if it's the current inferior that should be handled
1621 lp
= find_lwp_pid (inferior_ptid
);
1623 lp
= find_lwp_pid (ptid
);
1624 gdb_assert (lp
!= NULL
);
1626 /* Remember if we're stepping. */
1627 lp
->last_resume_kind
= step
? resume_step
: resume_continue
;
1629 /* If we have a pending wait status for this thread, there is no
1630 point in resuming the process. But first make sure that
1631 linux_nat_wait won't preemptively handle the event - we
1632 should never take this short-circuit if we are going to
1633 leave LP running, since we have skipped resuming all the
1634 other threads. This bit of code needs to be synchronized
1635 with linux_nat_wait. */
1637 if (lp
->status
&& WIFSTOPPED (lp
->status
))
1640 && WSTOPSIG (lp
->status
)
1641 && sigismember (&pass_mask
, WSTOPSIG (lp
->status
)))
1643 linux_nat_debug_printf
1644 ("Not short circuiting for ignored status 0x%x", lp
->status
);
1646 /* FIXME: What should we do if we are supposed to continue
1647 this thread with a signal? */
1648 gdb_assert (signo
== GDB_SIGNAL_0
);
1649 signo
= gdb_signal_from_host (WSTOPSIG (lp
->status
));
1654 if (lwp_status_pending_p (lp
))
1656 /* FIXME: What should we do if we are supposed to continue
1657 this thread with a signal? */
1658 gdb_assert (signo
== GDB_SIGNAL_0
);
1660 linux_nat_debug_printf ("Short circuiting for status 0x%x",
1663 if (target_can_async_p ())
1666 /* Tell the event loop we have something to process. */
1673 iterate_over_lwps (ptid
, [=] (struct lwp_info
*info
)
1675 return linux_nat_resume_callback (info
, lp
);
1678 linux_nat_debug_printf ("%s %s, %s (resume event thread)",
1679 step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
1680 lp
->ptid
.to_string ().c_str (),
1681 (signo
!= GDB_SIGNAL_0
1682 ? strsignal (gdb_signal_to_host (signo
)) : "0"));
1684 linux_resume_one_lwp (lp
, step
, signo
);
1687 /* Send a signal to an LWP. */
1690 kill_lwp (int lwpid
, int signo
)
1695 ret
= syscall (__NR_tkill
, lwpid
, signo
);
1696 if (errno
== ENOSYS
)
1698 /* If tkill fails, then we are not using nptl threads, a
1699 configuration we no longer support. */
1700 perror_with_name (("tkill"));
1705 /* Handle a GNU/Linux syscall trap wait response. If we see a syscall
1706 event, check if the core is interested in it: if not, ignore the
1707 event, and keep waiting; otherwise, we need to toggle the LWP's
1708 syscall entry/exit status, since the ptrace event itself doesn't
1709 indicate it, and report the trap to higher layers. */
1712 linux_handle_syscall_trap (struct lwp_info
*lp
, int stopping
)
1714 struct target_waitstatus
*ourstatus
= &lp
->waitstatus
;
1715 struct gdbarch
*gdbarch
= target_thread_architecture (lp
->ptid
);
1716 thread_info
*thread
= find_thread_ptid (linux_target
, lp
->ptid
);
1717 int syscall_number
= (int) gdbarch_get_syscall_number (gdbarch
, thread
);
1721 /* If we're stopping threads, there's a SIGSTOP pending, which
1722 makes it so that the LWP reports an immediate syscall return,
1723 followed by the SIGSTOP. Skip seeing that "return" using
1724 PTRACE_CONT directly, and let stop_wait_callback collect the
1725 SIGSTOP. Later when the thread is resumed, a new syscall
1726 entry event. If we didn't do this (and returned 0), we'd
1727 leave a syscall entry pending, and our caller, by using
1728 PTRACE_CONT to collect the SIGSTOP, skips the syscall return
1729 itself. Later, when the user re-resumes this LWP, we'd see
1730 another syscall entry event and we'd mistake it for a return.
1732 If stop_wait_callback didn't force the SIGSTOP out of the LWP
1733 (leaving immediately with LWP->signalled set, without issuing
1734 a PTRACE_CONT), it would still be problematic to leave this
1735 syscall enter pending, as later when the thread is resumed,
1736 it would then see the same syscall exit mentioned above,
1737 followed by the delayed SIGSTOP, while the syscall didn't
1738 actually get to execute. It seems it would be even more
1739 confusing to the user. */
1741 linux_nat_debug_printf
1742 ("ignoring syscall %d for LWP %ld (stopping threads), resuming with "
1743 "PTRACE_CONT for SIGSTOP", syscall_number
, lp
->ptid
.lwp ());
1745 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
1746 ptrace (PTRACE_CONT
, lp
->ptid
.lwp (), 0, 0);
1751 /* Always update the entry/return state, even if this particular
1752 syscall isn't interesting to the core now. In async mode,
1753 the user could install a new catchpoint for this syscall
1754 between syscall enter/return, and we'll need to know to
1755 report a syscall return if that happens. */
1756 lp
->syscall_state
= (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1757 ? TARGET_WAITKIND_SYSCALL_RETURN
1758 : TARGET_WAITKIND_SYSCALL_ENTRY
);
1760 if (catch_syscall_enabled ())
1762 if (catching_syscall_number (syscall_number
))
1764 /* Alright, an event to report. */
1765 if (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
)
1766 ourstatus
->set_syscall_entry (syscall_number
);
1767 else if (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_RETURN
)
1768 ourstatus
->set_syscall_return (syscall_number
);
1770 gdb_assert_not_reached ("unexpected syscall state");
1772 linux_nat_debug_printf
1773 ("stopping for %s of syscall %d for LWP %ld",
1774 (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1775 ? "entry" : "return"), syscall_number
, lp
->ptid
.lwp ());
1780 linux_nat_debug_printf
1781 ("ignoring %s of syscall %d for LWP %ld",
1782 (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1783 ? "entry" : "return"), syscall_number
, lp
->ptid
.lwp ());
1787 /* If we had been syscall tracing, and hence used PT_SYSCALL
1788 before on this LWP, it could happen that the user removes all
1789 syscall catchpoints before we get to process this event.
1790 There are two noteworthy issues here:
1792 - When stopped at a syscall entry event, resuming with
1793 PT_STEP still resumes executing the syscall and reports a
1796 - Only PT_SYSCALL catches syscall enters. If we last
1797 single-stepped this thread, then this event can't be a
1798 syscall enter. If we last single-stepped this thread, this
1799 has to be a syscall exit.
1801 The points above mean that the next resume, be it PT_STEP or
1802 PT_CONTINUE, can not trigger a syscall trace event. */
1803 linux_nat_debug_printf
1804 ("caught syscall event with no syscall catchpoints. %d for LWP %ld, "
1805 "ignoring", syscall_number
, lp
->ptid
.lwp ());
1806 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
1809 /* The core isn't interested in this event. For efficiency, avoid
1810 stopping all threads only to have the core resume them all again.
1811 Since we're not stopping threads, if we're still syscall tracing
1812 and not stepping, we can't use PTRACE_CONT here, as we'd miss any
1813 subsequent syscall. Simply resume using the inf-ptrace layer,
1814 which knows when to use PT_SYSCALL or PT_CONTINUE. */
1816 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
1820 /* Handle a GNU/Linux extended wait response. If we see a clone
1821 event, we need to add the new LWP to our list (and not report the
1822 trap to higher layers). This function returns non-zero if the
1823 event should be ignored and we should wait again. If STOPPING is
1824 true, the new LWP remains stopped, otherwise it is continued. */
1827 linux_handle_extended_wait (struct lwp_info
*lp
, int status
)
1829 int pid
= lp
->ptid
.lwp ();
1830 struct target_waitstatus
*ourstatus
= &lp
->waitstatus
;
1831 int event
= linux_ptrace_get_extended_event (status
);
1833 /* All extended events we currently use are mid-syscall. Only
1834 PTRACE_EVENT_STOP is delivered more like a signal-stop, but
1835 you have to be using PTRACE_SEIZE to get that. */
1836 lp
->syscall_state
= TARGET_WAITKIND_SYSCALL_ENTRY
;
1838 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
1839 || event
== PTRACE_EVENT_CLONE
)
1841 unsigned long new_pid
;
1844 ptrace (PTRACE_GETEVENTMSG
, pid
, 0, &new_pid
);
1846 /* If we haven't already seen the new PID stop, wait for it now. */
1847 if (! pull_pid_from_list (&stopped_pids
, new_pid
, &status
))
1849 /* The new child has a pending SIGSTOP. We can't affect it until it
1850 hits the SIGSTOP, but we're already attached. */
1851 ret
= my_waitpid (new_pid
, &status
, __WALL
);
1853 perror_with_name (_("waiting for new child"));
1854 else if (ret
!= new_pid
)
1855 internal_error (__FILE__
, __LINE__
,
1856 _("wait returned unexpected PID %d"), ret
);
1857 else if (!WIFSTOPPED (status
))
1858 internal_error (__FILE__
, __LINE__
,
1859 _("wait returned unexpected status 0x%x"), status
);
1862 ptid_t
child_ptid (new_pid
, new_pid
);
1864 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
)
1866 open_proc_mem_file (child_ptid
);
1868 /* The arch-specific native code may need to know about new
1869 forks even if those end up never mapped to an
1871 linux_target
->low_new_fork (lp
, new_pid
);
1873 else if (event
== PTRACE_EVENT_CLONE
)
1875 linux_target
->low_new_clone (lp
, new_pid
);
1878 if (event
== PTRACE_EVENT_FORK
1879 && linux_fork_checkpointing_p (lp
->ptid
.pid ()))
1881 /* Handle checkpointing by linux-fork.c here as a special
1882 case. We don't want the follow-fork-mode or 'catch fork'
1883 to interfere with this. */
1885 /* This won't actually modify the breakpoint list, but will
1886 physically remove the breakpoints from the child. */
1887 detach_breakpoints (ptid_t (new_pid
, new_pid
));
1889 /* Retain child fork in ptrace (stopped) state. */
1890 if (!find_fork_pid (new_pid
))
1893 /* Report as spurious, so that infrun doesn't want to follow
1894 this fork. We're actually doing an infcall in
1896 ourstatus
->set_spurious ();
1898 /* Report the stop to the core. */
1902 if (event
== PTRACE_EVENT_FORK
)
1903 ourstatus
->set_forked (child_ptid
);
1904 else if (event
== PTRACE_EVENT_VFORK
)
1905 ourstatus
->set_vforked (child_ptid
);
1906 else if (event
== PTRACE_EVENT_CLONE
)
1908 struct lwp_info
*new_lp
;
1910 ourstatus
->set_ignore ();
1912 linux_nat_debug_printf
1913 ("Got clone event from LWP %d, new child is LWP %ld", pid
, new_pid
);
1915 new_lp
= add_lwp (ptid_t (lp
->ptid
.pid (), new_pid
));
1916 new_lp
->stopped
= 1;
1917 new_lp
->resumed
= 1;
1919 /* If the thread_db layer is active, let it record the user
1920 level thread id and status, and add the thread to GDB's
1922 if (!thread_db_notice_clone (lp
->ptid
, new_lp
->ptid
))
1924 /* The process is not using thread_db. Add the LWP to
1926 target_post_attach (new_lp
->ptid
.lwp ());
1927 add_thread (linux_target
, new_lp
->ptid
);
1930 /* Even if we're stopping the thread for some reason
1931 internal to this module, from the perspective of infrun
1932 and the user/frontend, this new thread is running until
1933 it next reports a stop. */
1934 set_running (linux_target
, new_lp
->ptid
, true);
1935 set_executing (linux_target
, new_lp
->ptid
, true);
1937 if (WSTOPSIG (status
) != SIGSTOP
)
1939 /* This can happen if someone starts sending signals to
1940 the new thread before it gets a chance to run, which
1941 have a lower number than SIGSTOP (e.g. SIGUSR1).
1942 This is an unlikely case, and harder to handle for
1943 fork / vfork than for clone, so we do not try - but
1944 we handle it for clone events here. */
1946 new_lp
->signalled
= 1;
1948 /* We created NEW_LP so it cannot yet contain STATUS. */
1949 gdb_assert (new_lp
->status
== 0);
1951 /* Save the wait status to report later. */
1952 linux_nat_debug_printf
1953 ("waitpid of new LWP %ld, saving status %s",
1954 (long) new_lp
->ptid
.lwp (), status_to_str (status
).c_str ());
1955 new_lp
->status
= status
;
1957 else if (report_thread_events
)
1959 new_lp
->waitstatus
.set_thread_created ();
1960 new_lp
->status
= status
;
1969 if (event
== PTRACE_EVENT_EXEC
)
1971 linux_nat_debug_printf ("Got exec event from LWP %ld", lp
->ptid
.lwp ());
1973 /* Close the previous /proc/PID/mem file for this inferior,
1974 which was using the address space which is now gone.
1975 Reading/writing from this file would return 0/EOF. */
1976 close_proc_mem_file (lp
->ptid
.pid ());
1978 /* Open a new file for the new address space. */
1979 open_proc_mem_file (lp
->ptid
);
1981 ourstatus
->set_execd
1982 (make_unique_xstrdup (linux_proc_pid_to_exec_file (pid
)));
1984 /* The thread that execed must have been resumed, but, when a
1985 thread execs, it changes its tid to the tgid, and the old
1986 tgid thread might have not been resumed. */
1991 if (event
== PTRACE_EVENT_VFORK_DONE
)
1993 linux_nat_debug_printf
1994 ("Got PTRACE_EVENT_VFORK_DONE from LWP %ld",
1996 ourstatus
->set_vfork_done ();
2000 internal_error (__FILE__
, __LINE__
,
2001 _("unknown ptrace event %d"), event
);
2004 /* Suspend waiting for a signal. We're mostly interested in
2010 linux_nat_debug_printf ("about to sigsuspend");
2011 sigsuspend (&suspend_mask
);
2013 /* If the quit flag is set, it means that the user pressed Ctrl-C
2014 and we're debugging a process that is running on a separate
2015 terminal, so we must forward the Ctrl-C to the inferior. (If the
2016 inferior is sharing GDB's terminal, then the Ctrl-C reaches the
2017 inferior directly.) We must do this here because functions that
2018 need to block waiting for a signal loop forever until there's an
2019 event to report before returning back to the event loop. */
2020 if (!target_terminal::is_ours ())
2022 if (check_quit_flag ())
2023 target_pass_ctrlc ();
2027 /* Wait for LP to stop. Returns the wait status, or 0 if the LWP has
2031 wait_lwp (struct lwp_info
*lp
)
2035 int thread_dead
= 0;
2038 gdb_assert (!lp
->stopped
);
2039 gdb_assert (lp
->status
== 0);
2041 /* Make sure SIGCHLD is blocked for sigsuspend avoiding a race below. */
2042 block_child_signals (&prev_mask
);
2046 pid
= my_waitpid (lp
->ptid
.lwp (), &status
, __WALL
| WNOHANG
);
2047 if (pid
== -1 && errno
== ECHILD
)
2049 /* The thread has previously exited. We need to delete it
2050 now because if this was a non-leader thread execing, we
2051 won't get an exit event. See comments on exec events at
2052 the top of the file. */
2054 linux_nat_debug_printf ("%s vanished.",
2055 lp
->ptid
.to_string ().c_str ());
2060 /* Bugs 10970, 12702.
2061 Thread group leader may have exited in which case we'll lock up in
2062 waitpid if there are other threads, even if they are all zombies too.
2063 Basically, we're not supposed to use waitpid this way.
2064 tkill(pid,0) cannot be used here as it gets ESRCH for both
2065 for zombie and running processes.
2067 As a workaround, check if we're waiting for the thread group leader and
2068 if it's a zombie, and avoid calling waitpid if it is.
2070 This is racy, what if the tgl becomes a zombie right after we check?
2071 Therefore always use WNOHANG with sigsuspend - it is equivalent to
2072 waiting waitpid but linux_proc_pid_is_zombie is safe this way. */
2074 if (lp
->ptid
.pid () == lp
->ptid
.lwp ()
2075 && linux_proc_pid_is_zombie (lp
->ptid
.lwp ()))
2078 linux_nat_debug_printf ("Thread group leader %s vanished.",
2079 lp
->ptid
.to_string ().c_str ());
2083 /* Wait for next SIGCHLD and try again. This may let SIGCHLD handlers
2084 get invoked despite our caller had them intentionally blocked by
2085 block_child_signals. This is sensitive only to the loop of
2086 linux_nat_wait_1 and there if we get called my_waitpid gets called
2087 again before it gets to sigsuspend so we can safely let the handlers
2088 get executed here. */
2092 restore_child_signals_mask (&prev_mask
);
2096 gdb_assert (pid
== lp
->ptid
.lwp ());
2098 linux_nat_debug_printf ("waitpid %s received %s",
2099 lp
->ptid
.to_string ().c_str (),
2100 status_to_str (status
).c_str ());
2102 /* Check if the thread has exited. */
2103 if (WIFEXITED (status
) || WIFSIGNALED (status
))
2105 if (report_thread_events
2106 || lp
->ptid
.pid () == lp
->ptid
.lwp ())
2108 linux_nat_debug_printf ("LWP %d exited.", lp
->ptid
.pid ());
2110 /* If this is the leader exiting, it means the whole
2111 process is gone. Store the status to report to the
2112 core. Store it in lp->waitstatus, because lp->status
2113 would be ambiguous (W_EXITCODE(0,0) == 0). */
2114 lp
->waitstatus
= host_status_to_waitstatus (status
);
2119 linux_nat_debug_printf ("%s exited.",
2120 lp
->ptid
.to_string ().c_str ());
2130 gdb_assert (WIFSTOPPED (status
));
2133 if (lp
->must_set_ptrace_flags
)
2135 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2136 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
2138 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
2139 lp
->must_set_ptrace_flags
= 0;
2142 /* Handle GNU/Linux's syscall SIGTRAPs. */
2143 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
2145 /* No longer need the sysgood bit. The ptrace event ends up
2146 recorded in lp->waitstatus if we care for it. We can carry
2147 on handling the event like a regular SIGTRAP from here
2149 status
= W_STOPCODE (SIGTRAP
);
2150 if (linux_handle_syscall_trap (lp
, 1))
2151 return wait_lwp (lp
);
2155 /* Almost all other ptrace-stops are known to be outside of system
2156 calls, with further exceptions in linux_handle_extended_wait. */
2157 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
2160 /* Handle GNU/Linux's extended waitstatus for trace events. */
2161 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
2162 && linux_is_extended_waitstatus (status
))
2164 linux_nat_debug_printf ("Handling extended status 0x%06x", status
);
2165 linux_handle_extended_wait (lp
, status
);
2172 /* Send a SIGSTOP to LP. */
2175 stop_callback (struct lwp_info
*lp
)
2177 if (!lp
->stopped
&& !lp
->signalled
)
2181 linux_nat_debug_printf ("kill %s **<SIGSTOP>**",
2182 lp
->ptid
.to_string ().c_str ());
2185 ret
= kill_lwp (lp
->ptid
.lwp (), SIGSTOP
);
2186 linux_nat_debug_printf ("lwp kill %d %s", ret
,
2187 errno
? safe_strerror (errno
) : "ERRNO-OK");
2190 gdb_assert (lp
->status
== 0);
2196 /* Request a stop on LWP. */
2199 linux_stop_lwp (struct lwp_info
*lwp
)
2201 stop_callback (lwp
);
2204 /* See linux-nat.h */
2207 linux_stop_and_wait_all_lwps (void)
2209 /* Stop all LWP's ... */
2210 iterate_over_lwps (minus_one_ptid
, stop_callback
);
2212 /* ... and wait until all of them have reported back that
2213 they're no longer running. */
2214 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
2217 /* See linux-nat.h */
2220 linux_unstop_all_lwps (void)
2222 iterate_over_lwps (minus_one_ptid
,
2223 [] (struct lwp_info
*info
)
2225 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
2229 /* Return non-zero if LWP PID has a pending SIGINT. */
2232 linux_nat_has_pending_sigint (int pid
)
2234 sigset_t pending
, blocked
, ignored
;
2236 linux_proc_pending_signals (pid
, &pending
, &blocked
, &ignored
);
2238 if (sigismember (&pending
, SIGINT
)
2239 && !sigismember (&ignored
, SIGINT
))
2245 /* Set a flag in LP indicating that we should ignore its next SIGINT. */
2248 set_ignore_sigint (struct lwp_info
*lp
)
2250 /* If a thread has a pending SIGINT, consume it; otherwise, set a
2251 flag to consume the next one. */
2252 if (lp
->stopped
&& lp
->status
!= 0 && WIFSTOPPED (lp
->status
)
2253 && WSTOPSIG (lp
->status
) == SIGINT
)
2256 lp
->ignore_sigint
= 1;
2261 /* If LP does not have a SIGINT pending, then clear the ignore_sigint flag.
2262 This function is called after we know the LWP has stopped; if the LWP
2263 stopped before the expected SIGINT was delivered, then it will never have
2264 arrived. Also, if the signal was delivered to a shared queue and consumed
2265 by a different thread, it will never be delivered to this LWP. */
2268 maybe_clear_ignore_sigint (struct lwp_info
*lp
)
2270 if (!lp
->ignore_sigint
)
2273 if (!linux_nat_has_pending_sigint (lp
->ptid
.lwp ()))
2275 linux_nat_debug_printf ("Clearing bogus flag for %s",
2276 lp
->ptid
.to_string ().c_str ());
2277 lp
->ignore_sigint
= 0;
2281 /* Fetch the possible triggered data watchpoint info and store it in
2284 On some archs, like x86, that use debug registers to set
2285 watchpoints, it's possible that the way to know which watched
2286 address trapped, is to check the register that is used to select
2287 which address to watch. Problem is, between setting the watchpoint
2288 and reading back which data address trapped, the user may change
2289 the set of watchpoints, and, as a consequence, GDB changes the
2290 debug registers in the inferior. To avoid reading back a stale
2291 stopped-data-address when that happens, we cache in LP the fact
2292 that a watchpoint trapped, and the corresponding data address, as
2293 soon as we see LP stop with a SIGTRAP. If GDB changes the debug
2294 registers meanwhile, we have the cached data we can rely on. */
2297 check_stopped_by_watchpoint (struct lwp_info
*lp
)
2299 scoped_restore save_inferior_ptid
= make_scoped_restore (&inferior_ptid
);
2300 inferior_ptid
= lp
->ptid
;
2302 if (linux_target
->low_stopped_by_watchpoint ())
2304 lp
->stop_reason
= TARGET_STOPPED_BY_WATCHPOINT
;
2305 lp
->stopped_data_address_p
2306 = linux_target
->low_stopped_data_address (&lp
->stopped_data_address
);
2309 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2312 /* Returns true if the LWP had stopped for a watchpoint. */
2315 linux_nat_target::stopped_by_watchpoint ()
2317 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2319 gdb_assert (lp
!= NULL
);
2321 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2325 linux_nat_target::stopped_data_address (CORE_ADDR
*addr_p
)
2327 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2329 gdb_assert (lp
!= NULL
);
2331 *addr_p
= lp
->stopped_data_address
;
2333 return lp
->stopped_data_address_p
;
2336 /* Commonly any breakpoint / watchpoint generate only SIGTRAP. */
2339 linux_nat_target::low_status_is_event (int status
)
2341 return WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
;
2344 /* Wait until LP is stopped. */
2347 stop_wait_callback (struct lwp_info
*lp
)
2349 inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
2351 /* If this is a vfork parent, bail out, it is not going to report
2352 any SIGSTOP until the vfork is done with. */
2353 if (inf
->vfork_child
!= NULL
)
2360 status
= wait_lwp (lp
);
2364 if (lp
->ignore_sigint
&& WIFSTOPPED (status
)
2365 && WSTOPSIG (status
) == SIGINT
)
2367 lp
->ignore_sigint
= 0;
2370 ptrace (PTRACE_CONT
, lp
->ptid
.lwp (), 0, 0);
2372 linux_nat_debug_printf
2373 ("PTRACE_CONT %s, 0, 0 (%s) (discarding SIGINT)",
2374 lp
->ptid
.to_string ().c_str (),
2375 errno
? safe_strerror (errno
) : "OK");
2377 return stop_wait_callback (lp
);
2380 maybe_clear_ignore_sigint (lp
);
2382 if (WSTOPSIG (status
) != SIGSTOP
)
2384 /* The thread was stopped with a signal other than SIGSTOP. */
2386 linux_nat_debug_printf ("Pending event %s in %s",
2387 status_to_str ((int) status
).c_str (),
2388 lp
->ptid
.to_string ().c_str ());
2390 /* Save the sigtrap event. */
2391 lp
->status
= status
;
2392 gdb_assert (lp
->signalled
);
2393 save_stop_reason (lp
);
2397 /* We caught the SIGSTOP that we intended to catch. */
2399 linux_nat_debug_printf ("Expected SIGSTOP caught for %s.",
2400 lp
->ptid
.to_string ().c_str ());
2404 /* If we are waiting for this stop so we can report the thread
2405 stopped then we need to record this status. Otherwise, we can
2406 now discard this stop event. */
2407 if (lp
->last_resume_kind
== resume_stop
)
2409 lp
->status
= status
;
2410 save_stop_reason (lp
);
2418 /* Return non-zero if LP has a wait status pending. Discard the
2419 pending event and resume the LWP if the event that originally
2420 caused the stop became uninteresting. */
2423 status_callback (struct lwp_info
*lp
)
2425 /* Only report a pending wait status if we pretend that this has
2426 indeed been resumed. */
2430 if (!lwp_status_pending_p (lp
))
2433 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
2434 || lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2436 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2440 pc
= regcache_read_pc (regcache
);
2442 if (pc
!= lp
->stop_pc
)
2444 linux_nat_debug_printf ("PC of %s changed. was=%s, now=%s",
2445 lp
->ptid
.to_string ().c_str (),
2446 paddress (target_gdbarch (), lp
->stop_pc
),
2447 paddress (target_gdbarch (), pc
));
2451 #if !USE_SIGTRAP_SIGINFO
2452 else if (!breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2454 linux_nat_debug_printf ("previous breakpoint of %s, at %s gone",
2455 lp
->ptid
.to_string ().c_str (),
2456 paddress (target_gdbarch (), lp
->stop_pc
));
2464 linux_nat_debug_printf ("pending event of %s cancelled.",
2465 lp
->ptid
.to_string ().c_str ());
2468 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2476 /* Count the LWP's that have had events. */
2479 count_events_callback (struct lwp_info
*lp
, int *count
)
2481 gdb_assert (count
!= NULL
);
2483 /* Select only resumed LWPs that have an event pending. */
2484 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2490 /* Select the LWP (if any) that is currently being single-stepped. */
2493 select_singlestep_lwp_callback (struct lwp_info
*lp
)
2495 if (lp
->last_resume_kind
== resume_step
2502 /* Returns true if LP has a status pending. */
2505 lwp_status_pending_p (struct lwp_info
*lp
)
2507 /* We check for lp->waitstatus in addition to lp->status, because we
2508 can have pending process exits recorded in lp->status and
2509 W_EXITCODE(0,0) happens to be 0. */
2510 return lp
->status
!= 0 || lp
->waitstatus
.kind () != TARGET_WAITKIND_IGNORE
;
2513 /* Select the Nth LWP that has had an event. */
2516 select_event_lwp_callback (struct lwp_info
*lp
, int *selector
)
2518 gdb_assert (selector
!= NULL
);
2520 /* Select only resumed LWPs that have an event pending. */
2521 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2522 if ((*selector
)-- == 0)
2528 /* Called when the LWP stopped for a signal/trap. If it stopped for a
2529 trap check what caused it (breakpoint, watchpoint, trace, etc.),
2530 and save the result in the LWP's stop_reason field. If it stopped
2531 for a breakpoint, decrement the PC if necessary on the lwp's
2535 save_stop_reason (struct lwp_info
*lp
)
2537 struct regcache
*regcache
;
2538 struct gdbarch
*gdbarch
;
2541 #if USE_SIGTRAP_SIGINFO
2545 gdb_assert (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
);
2546 gdb_assert (lp
->status
!= 0);
2548 if (!linux_target
->low_status_is_event (lp
->status
))
2551 regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2552 gdbarch
= regcache
->arch ();
2554 pc
= regcache_read_pc (regcache
);
2555 sw_bp_pc
= pc
- gdbarch_decr_pc_after_break (gdbarch
);
2557 #if USE_SIGTRAP_SIGINFO
2558 if (linux_nat_get_siginfo (lp
->ptid
, &siginfo
))
2560 if (siginfo
.si_signo
== SIGTRAP
)
2562 if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
)
2563 && GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2565 /* The si_code is ambiguous on this arch -- check debug
2567 if (!check_stopped_by_watchpoint (lp
))
2568 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2570 else if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
))
2572 /* If we determine the LWP stopped for a SW breakpoint,
2573 trust it. Particularly don't check watchpoint
2574 registers, because, at least on s390, we'd find
2575 stopped-by-watchpoint as long as there's a watchpoint
2577 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2579 else if (GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2581 /* This can indicate either a hardware breakpoint or
2582 hardware watchpoint. Check debug registers. */
2583 if (!check_stopped_by_watchpoint (lp
))
2584 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2586 else if (siginfo
.si_code
== TRAP_TRACE
)
2588 linux_nat_debug_printf ("%s stopped by trace",
2589 lp
->ptid
.to_string ().c_str ());
2591 /* We may have single stepped an instruction that
2592 triggered a watchpoint. In that case, on some
2593 architectures (such as x86), instead of TRAP_HWBKPT,
2594 si_code indicates TRAP_TRACE, and we need to check
2595 the debug registers separately. */
2596 check_stopped_by_watchpoint (lp
);
2601 if ((!lp
->step
|| lp
->stop_pc
== sw_bp_pc
)
2602 && software_breakpoint_inserted_here_p (regcache
->aspace (),
2605 /* The LWP was either continued, or stepped a software
2606 breakpoint instruction. */
2607 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2610 if (hardware_breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2611 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2613 if (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
)
2614 check_stopped_by_watchpoint (lp
);
2617 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
)
2619 linux_nat_debug_printf ("%s stopped by software breakpoint",
2620 lp
->ptid
.to_string ().c_str ());
2622 /* Back up the PC if necessary. */
2624 regcache_write_pc (regcache
, sw_bp_pc
);
2626 /* Update this so we record the correct stop PC below. */
2629 else if (lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2631 linux_nat_debug_printf ("%s stopped by hardware breakpoint",
2632 lp
->ptid
.to_string ().c_str ());
2634 else if (lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
)
2636 linux_nat_debug_printf ("%s stopped by hardware watchpoint",
2637 lp
->ptid
.to_string ().c_str ());
2644 /* Returns true if the LWP had stopped for a software breakpoint. */
2647 linux_nat_target::stopped_by_sw_breakpoint ()
2649 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2651 gdb_assert (lp
!= NULL
);
2653 return lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
;
2656 /* Implement the supports_stopped_by_sw_breakpoint method. */
2659 linux_nat_target::supports_stopped_by_sw_breakpoint ()
2661 return USE_SIGTRAP_SIGINFO
;
2664 /* Returns true if the LWP had stopped for a hardware
2665 breakpoint/watchpoint. */
2668 linux_nat_target::stopped_by_hw_breakpoint ()
2670 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2672 gdb_assert (lp
!= NULL
);
2674 return lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
;
2677 /* Implement the supports_stopped_by_hw_breakpoint method. */
2680 linux_nat_target::supports_stopped_by_hw_breakpoint ()
2682 return USE_SIGTRAP_SIGINFO
;
2685 /* Select one LWP out of those that have events pending. */
2688 select_event_lwp (ptid_t filter
, struct lwp_info
**orig_lp
, int *status
)
2691 int random_selector
;
2692 struct lwp_info
*event_lp
= NULL
;
2694 /* Record the wait status for the original LWP. */
2695 (*orig_lp
)->status
= *status
;
2697 /* In all-stop, give preference to the LWP that is being
2698 single-stepped. There will be at most one, and it will be the
2699 LWP that the core is most interested in. If we didn't do this,
2700 then we'd have to handle pending step SIGTRAPs somehow in case
2701 the core later continues the previously-stepped thread, as
2702 otherwise we'd report the pending SIGTRAP then, and the core, not
2703 having stepped the thread, wouldn't understand what the trap was
2704 for, and therefore would report it to the user as a random
2706 if (!target_is_non_stop_p ())
2708 event_lp
= iterate_over_lwps (filter
, select_singlestep_lwp_callback
);
2709 if (event_lp
!= NULL
)
2711 linux_nat_debug_printf ("Select single-step %s",
2712 event_lp
->ptid
.to_string ().c_str ());
2716 if (event_lp
== NULL
)
2718 /* Pick one at random, out of those which have had events. */
2720 /* First see how many events we have. */
2721 iterate_over_lwps (filter
,
2722 [&] (struct lwp_info
*info
)
2724 return count_events_callback (info
, &num_events
);
2726 gdb_assert (num_events
> 0);
2728 /* Now randomly pick a LWP out of those that have had
2730 random_selector
= (int)
2731 ((num_events
* (double) rand ()) / (RAND_MAX
+ 1.0));
2734 linux_nat_debug_printf ("Found %d events, selecting #%d",
2735 num_events
, random_selector
);
2738 = (iterate_over_lwps
2740 [&] (struct lwp_info
*info
)
2742 return select_event_lwp_callback (info
,
2747 if (event_lp
!= NULL
)
2749 /* Switch the event LWP. */
2750 *orig_lp
= event_lp
;
2751 *status
= event_lp
->status
;
2754 /* Flush the wait status for the event LWP. */
2755 (*orig_lp
)->status
= 0;
2758 /* Return non-zero if LP has been resumed. */
2761 resumed_callback (struct lwp_info
*lp
)
2766 /* Check if we should go on and pass this event to common code.
2768 If so, save the status to the lwp_info structure associated to LWPID. */
2771 linux_nat_filter_event (int lwpid
, int status
)
2773 struct lwp_info
*lp
;
2774 int event
= linux_ptrace_get_extended_event (status
);
2776 lp
= find_lwp_pid (ptid_t (lwpid
));
2778 /* Check for events reported by anything not in our LWP list. */
2781 if (WIFSTOPPED (status
))
2783 if (WSTOPSIG (status
) == SIGTRAP
&& event
== PTRACE_EVENT_EXEC
)
2785 /* A non-leader thread exec'ed after we've seen the
2786 leader zombie, and removed it from our lists (in
2787 check_zombie_leaders). The non-leader thread changes
2788 its tid to the tgid. */
2789 linux_nat_debug_printf
2790 ("Re-adding thread group leader LWP %d after exec.",
2793 lp
= add_lwp (ptid_t (lwpid
, lwpid
));
2796 add_thread (linux_target
, lp
->ptid
);
2800 /* A process we are controlling has forked and the new
2801 child's stop was reported to us by the kernel. Save
2802 its PID and go back to waiting for the fork event to
2803 be reported - the stopped process might be returned
2804 from waitpid before or after the fork event is. */
2805 linux_nat_debug_printf
2806 ("Saving LWP %d status %s in stopped_pids list",
2807 lwpid
, status_to_str (status
).c_str ());
2808 add_to_pid_list (&stopped_pids
, lwpid
, status
);
2813 /* Don't report an event for the exit of an LWP not in our
2814 list, i.e. not part of any inferior we're debugging.
2815 This can happen if we detach from a program we originally
2816 forked and then it exits. However, note that we may have
2817 earlier deleted a leader of an inferior we're debugging,
2818 in check_zombie_leaders. Re-add it back here if so. */
2819 for (inferior
*inf
: all_inferiors (linux_target
))
2821 if (inf
->pid
== lwpid
)
2823 linux_nat_debug_printf
2824 ("Re-adding thread group leader LWP %d after exit.",
2827 lp
= add_lwp (ptid_t (lwpid
, lwpid
));
2829 add_thread (linux_target
, lp
->ptid
);
2839 /* This LWP is stopped now. (And if dead, this prevents it from
2840 ever being continued.) */
2843 if (WIFSTOPPED (status
) && lp
->must_set_ptrace_flags
)
2845 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2846 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
2848 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
2849 lp
->must_set_ptrace_flags
= 0;
2852 /* Handle GNU/Linux's syscall SIGTRAPs. */
2853 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
2855 /* No longer need the sysgood bit. The ptrace event ends up
2856 recorded in lp->waitstatus if we care for it. We can carry
2857 on handling the event like a regular SIGTRAP from here
2859 status
= W_STOPCODE (SIGTRAP
);
2860 if (linux_handle_syscall_trap (lp
, 0))
2865 /* Almost all other ptrace-stops are known to be outside of system
2866 calls, with further exceptions in linux_handle_extended_wait. */
2867 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
2870 /* Handle GNU/Linux's extended waitstatus for trace events. */
2871 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
2872 && linux_is_extended_waitstatus (status
))
2874 linux_nat_debug_printf ("Handling extended status 0x%06x", status
);
2876 if (linux_handle_extended_wait (lp
, status
))
2880 /* Check if the thread has exited. */
2881 if (WIFEXITED (status
) || WIFSIGNALED (status
))
2883 if (!report_thread_events
&& !is_leader (lp
))
2885 linux_nat_debug_printf ("%s exited.",
2886 lp
->ptid
.to_string ().c_str ());
2888 /* If this was not the leader exiting, then the exit signal
2889 was not the end of the debugged application and should be
2895 /* Note that even if the leader was ptrace-stopped, it can still
2896 exit, if e.g., some other thread brings down the whole
2897 process (calls `exit'). So don't assert that the lwp is
2899 linux_nat_debug_printf ("LWP %ld exited (resumed=%d)",
2900 lp
->ptid
.lwp (), lp
->resumed
);
2902 /* Dead LWP's aren't expected to reported a pending sigstop. */
2905 /* Store the pending event in the waitstatus, because
2906 W_EXITCODE(0,0) == 0. */
2907 lp
->waitstatus
= host_status_to_waitstatus (status
);
2911 /* Make sure we don't report a SIGSTOP that we sent ourselves in
2912 an attempt to stop an LWP. */
2914 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGSTOP
)
2918 if (lp
->last_resume_kind
== resume_stop
)
2920 linux_nat_debug_printf ("resume_stop SIGSTOP caught for %s.",
2921 lp
->ptid
.to_string ().c_str ());
2925 /* This is a delayed SIGSTOP. Filter out the event. */
2927 linux_nat_debug_printf
2928 ("%s %s, 0, 0 (discard delayed SIGSTOP)",
2929 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
2930 lp
->ptid
.to_string ().c_str ());
2932 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2933 gdb_assert (lp
->resumed
);
2938 /* Make sure we don't report a SIGINT that we have already displayed
2939 for another thread. */
2940 if (lp
->ignore_sigint
2941 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGINT
)
2943 linux_nat_debug_printf ("Delayed SIGINT caught for %s.",
2944 lp
->ptid
.to_string ().c_str ());
2946 /* This is a delayed SIGINT. */
2947 lp
->ignore_sigint
= 0;
2949 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2950 linux_nat_debug_printf ("%s %s, 0, 0 (discard SIGINT)",
2951 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
2952 lp
->ptid
.to_string ().c_str ());
2953 gdb_assert (lp
->resumed
);
2955 /* Discard the event. */
2959 /* Don't report signals that GDB isn't interested in, such as
2960 signals that are neither printed nor stopped upon. Stopping all
2961 threads can be a bit time-consuming, so if we want decent
2962 performance with heavily multi-threaded programs, especially when
2963 they're using a high frequency timer, we'd better avoid it if we
2965 if (WIFSTOPPED (status
))
2967 enum gdb_signal signo
= gdb_signal_from_host (WSTOPSIG (status
));
2969 if (!target_is_non_stop_p ())
2971 /* Only do the below in all-stop, as we currently use SIGSTOP
2972 to implement target_stop (see linux_nat_stop) in
2974 if (signo
== GDB_SIGNAL_INT
&& signal_pass_state (signo
) == 0)
2976 /* If ^C/BREAK is typed at the tty/console, SIGINT gets
2977 forwarded to the entire process group, that is, all LWPs
2978 will receive it - unless they're using CLONE_THREAD to
2979 share signals. Since we only want to report it once, we
2980 mark it as ignored for all LWPs except this one. */
2981 iterate_over_lwps (ptid_t (lp
->ptid
.pid ()), set_ignore_sigint
);
2982 lp
->ignore_sigint
= 0;
2985 maybe_clear_ignore_sigint (lp
);
2988 /* When using hardware single-step, we need to report every signal.
2989 Otherwise, signals in pass_mask may be short-circuited
2990 except signals that might be caused by a breakpoint, or SIGSTOP
2991 if we sent the SIGSTOP and are waiting for it to arrive. */
2993 && WSTOPSIG (status
) && sigismember (&pass_mask
, WSTOPSIG (status
))
2994 && (WSTOPSIG (status
) != SIGSTOP
2995 || !find_thread_ptid (linux_target
, lp
->ptid
)->stop_requested
)
2996 && !linux_wstatus_maybe_breakpoint (status
))
2998 linux_resume_one_lwp (lp
, lp
->step
, signo
);
2999 linux_nat_debug_printf
3000 ("%s %s, %s (preempt 'handle')",
3001 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
3002 lp
->ptid
.to_string ().c_str (),
3003 (signo
!= GDB_SIGNAL_0
3004 ? strsignal (gdb_signal_to_host (signo
)) : "0"));
3009 /* An interesting event. */
3011 lp
->status
= status
;
3012 save_stop_reason (lp
);
3015 /* Detect zombie thread group leaders, and "exit" them. We can't reap
3016 their exits until all other threads in the group have exited. */
3019 check_zombie_leaders (void)
3021 for (inferior
*inf
: all_inferiors ())
3023 struct lwp_info
*leader_lp
;
3028 leader_lp
= find_lwp_pid (ptid_t (inf
->pid
));
3029 if (leader_lp
!= NULL
3030 /* Check if there are other threads in the group, as we may
3031 have raced with the inferior simply exiting. Note this
3032 isn't a watertight check. If the inferior is
3033 multi-threaded and is exiting, it may be we see the
3034 leader as zombie before we reap all the non-leader
3035 threads. See comments below. */
3036 && num_lwps (inf
->pid
) > 1
3037 && linux_proc_pid_is_zombie (inf
->pid
))
3039 /* A zombie leader in a multi-threaded program can mean one
3042 #1 - Only the leader exited, not the whole program, e.g.,
3043 with pthread_exit. Since we can't reap the leader's exit
3044 status until all other threads are gone and reaped too,
3045 we want to delete the zombie leader right away, as it
3046 can't be debugged, we can't read its registers, etc.
3047 This is the main reason we check for zombie leaders
3050 #2 - The whole thread-group/process exited (a group exit,
3051 via e.g. exit(3), and there is (or will be shortly) an
3052 exit reported for each thread in the process, and then
3053 finally an exit for the leader once the non-leaders are
3056 #3 - There are 3 or more threads in the group, and a
3057 thread other than the leader exec'd. See comments on
3058 exec events at the top of the file.
3060 Ideally we would never delete the leader for case #2.
3061 Instead, we want to collect the exit status of each
3062 non-leader thread, and then finally collect the exit
3063 status of the leader as normal and use its exit code as
3064 whole-process exit code. Unfortunately, there's no
3065 race-free way to distinguish cases #1 and #2. We can't
3066 assume the exit events for the non-leaders threads are
3067 already pending in the kernel, nor can we assume the
3068 non-leader threads are in zombie state already. Between
3069 the leader becoming zombie and the non-leaders exiting
3070 and becoming zombie themselves, there's a small time
3071 window, so such a check would be racy. Temporarily
3072 pausing all threads and checking to see if all threads
3073 exit or not before re-resuming them would work in the
3074 case that all threads are running right now, but it
3075 wouldn't work if some thread is currently already
3076 ptrace-stopped, e.g., due to scheduler-locking.
3078 So what we do is we delete the leader anyhow, and then
3079 later on when we see its exit status, we re-add it back.
3080 We also make sure that we only report a whole-process
3081 exit when we see the leader exiting, as opposed to when
3082 the last LWP in the LWP list exits, which can be a
3083 non-leader if we deleted the leader here. */
3084 linux_nat_debug_printf ("Thread group leader %d zombie "
3085 "(it exited, or another thread execd), "
3088 exit_lwp (leader_lp
);
3093 /* Convenience function that is called when the kernel reports an exit
3094 event. This decides whether to report the event to GDB as a
3095 process exit event, a thread exit event, or to suppress the
3099 filter_exit_event (struct lwp_info
*event_child
,
3100 struct target_waitstatus
*ourstatus
)
3102 ptid_t ptid
= event_child
->ptid
;
3104 if (!is_leader (event_child
))
3106 if (report_thread_events
)
3107 ourstatus
->set_thread_exited (0);
3109 ourstatus
->set_ignore ();
3111 exit_lwp (event_child
);
3118 linux_nat_wait_1 (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3119 target_wait_flags target_options
)
3122 enum resume_kind last_resume_kind
;
3123 struct lwp_info
*lp
;
3126 linux_nat_debug_printf ("enter");
3128 /* The first time we get here after starting a new inferior, we may
3129 not have added it to the LWP list yet - this is the earliest
3130 moment at which we know its PID. */
3131 if (ptid
.is_pid () && find_lwp_pid (ptid
) == nullptr)
3133 ptid_t
lwp_ptid (ptid
.pid (), ptid
.pid ());
3135 /* Upgrade the main thread's ptid. */
3136 thread_change_ptid (linux_target
, ptid
, lwp_ptid
);
3137 lp
= add_initial_lwp (lwp_ptid
);
3141 /* Make sure SIGCHLD is blocked until the sigsuspend below. */
3142 block_child_signals (&prev_mask
);
3144 /* First check if there is a LWP with a wait status pending. */
3145 lp
= iterate_over_lwps (ptid
, status_callback
);
3148 linux_nat_debug_printf ("Using pending wait status %s for %s.",
3149 status_to_str (lp
->status
).c_str (),
3150 lp
->ptid
.to_string ().c_str ());
3153 /* But if we don't find a pending event, we'll have to wait. Always
3154 pull all events out of the kernel. We'll randomly select an
3155 event LWP out of all that have events, to prevent starvation. */
3161 /* Always use -1 and WNOHANG, due to couple of a kernel/ptrace
3164 - If the thread group leader exits while other threads in the
3165 thread group still exist, waitpid(TGID, ...) hangs. That
3166 waitpid won't return an exit status until the other threads
3167 in the group are reaped.
3169 - When a non-leader thread execs, that thread just vanishes
3170 without reporting an exit (so we'd hang if we waited for it
3171 explicitly in that case). The exec event is reported to
3175 lwpid
= my_waitpid (-1, &status
, __WALL
| WNOHANG
);
3177 linux_nat_debug_printf ("waitpid(-1, ...) returned %d, %s",
3179 errno
? safe_strerror (errno
) : "ERRNO-OK");
3183 linux_nat_debug_printf ("waitpid %ld received %s",
3185 status_to_str (status
).c_str ());
3187 linux_nat_filter_event (lwpid
, status
);
3188 /* Retry until nothing comes out of waitpid. A single
3189 SIGCHLD can indicate more than one child stopped. */
3193 /* Now that we've pulled all events out of the kernel, resume
3194 LWPs that don't have an interesting event to report. */
3195 iterate_over_lwps (minus_one_ptid
,
3196 [] (struct lwp_info
*info
)
3198 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
3201 /* ... and find an LWP with a status to report to the core, if
3203 lp
= iterate_over_lwps (ptid
, status_callback
);
3207 /* Check for zombie thread group leaders. Those can't be reaped
3208 until all other threads in the thread group are. */
3209 check_zombie_leaders ();
3211 /* If there are no resumed children left, bail. We'd be stuck
3212 forever in the sigsuspend call below otherwise. */
3213 if (iterate_over_lwps (ptid
, resumed_callback
) == NULL
)
3215 linux_nat_debug_printf ("exit (no resumed LWP)");
3217 ourstatus
->set_no_resumed ();
3219 restore_child_signals_mask (&prev_mask
);
3220 return minus_one_ptid
;
3223 /* No interesting event to report to the core. */
3225 if (target_options
& TARGET_WNOHANG
)
3227 linux_nat_debug_printf ("exit (ignore)");
3229 ourstatus
->set_ignore ();
3230 restore_child_signals_mask (&prev_mask
);
3231 return minus_one_ptid
;
3234 /* We shouldn't end up here unless we want to try again. */
3235 gdb_assert (lp
== NULL
);
3237 /* Block until we get an event reported with SIGCHLD. */
3243 status
= lp
->status
;
3246 if (!target_is_non_stop_p ())
3248 /* Now stop all other LWP's ... */
3249 iterate_over_lwps (minus_one_ptid
, stop_callback
);
3251 /* ... and wait until all of them have reported back that
3252 they're no longer running. */
3253 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
3256 /* If we're not waiting for a specific LWP, choose an event LWP from
3257 among those that have had events. Giving equal priority to all
3258 LWPs that have had events helps prevent starvation. */
3259 if (ptid
== minus_one_ptid
|| ptid
.is_pid ())
3260 select_event_lwp (ptid
, &lp
, &status
);
3262 gdb_assert (lp
!= NULL
);
3264 /* Now that we've selected our final event LWP, un-adjust its PC if
3265 it was a software breakpoint, and we can't reliably support the
3266 "stopped by software breakpoint" stop reason. */
3267 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
3268 && !USE_SIGTRAP_SIGINFO
)
3270 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3271 struct gdbarch
*gdbarch
= regcache
->arch ();
3272 int decr_pc
= gdbarch_decr_pc_after_break (gdbarch
);
3278 pc
= regcache_read_pc (regcache
);
3279 regcache_write_pc (regcache
, pc
+ decr_pc
);
3283 /* We'll need this to determine whether to report a SIGSTOP as
3284 GDB_SIGNAL_0. Need to take a copy because resume_clear_callback
3286 last_resume_kind
= lp
->last_resume_kind
;
3288 if (!target_is_non_stop_p ())
3290 /* In all-stop, from the core's perspective, all LWPs are now
3291 stopped until a new resume action is sent over. */
3292 iterate_over_lwps (minus_one_ptid
, resume_clear_callback
);
3296 resume_clear_callback (lp
);
3299 if (linux_target
->low_status_is_event (status
))
3301 linux_nat_debug_printf ("trap ptid is %s.",
3302 lp
->ptid
.to_string ().c_str ());
3305 if (lp
->waitstatus
.kind () != TARGET_WAITKIND_IGNORE
)
3307 *ourstatus
= lp
->waitstatus
;
3308 lp
->waitstatus
.set_ignore ();
3311 *ourstatus
= host_status_to_waitstatus (status
);
3313 linux_nat_debug_printf ("exit");
3315 restore_child_signals_mask (&prev_mask
);
3317 if (last_resume_kind
== resume_stop
3318 && ourstatus
->kind () == TARGET_WAITKIND_STOPPED
3319 && WSTOPSIG (status
) == SIGSTOP
)
3321 /* A thread that has been requested to stop by GDB with
3322 target_stop, and it stopped cleanly, so report as SIG0. The
3323 use of SIGSTOP is an implementation detail. */
3324 ourstatus
->set_stopped (GDB_SIGNAL_0
);
3327 if (ourstatus
->kind () == TARGET_WAITKIND_EXITED
3328 || ourstatus
->kind () == TARGET_WAITKIND_SIGNALLED
)
3331 lp
->core
= linux_common_core_of_thread (lp
->ptid
);
3333 if (ourstatus
->kind () == TARGET_WAITKIND_EXITED
)
3334 return filter_exit_event (lp
, ourstatus
);
3339 /* Resume LWPs that are currently stopped without any pending status
3340 to report, but are resumed from the core's perspective. */
3343 resume_stopped_resumed_lwps (struct lwp_info
*lp
, const ptid_t wait_ptid
)
3347 linux_nat_debug_printf ("NOT resuming LWP %s, not stopped",
3348 lp
->ptid
.to_string ().c_str ());
3350 else if (!lp
->resumed
)
3352 linux_nat_debug_printf ("NOT resuming LWP %s, not resumed",
3353 lp
->ptid
.to_string ().c_str ());
3355 else if (lwp_status_pending_p (lp
))
3357 linux_nat_debug_printf ("NOT resuming LWP %s, has pending status",
3358 lp
->ptid
.to_string ().c_str ());
3362 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3363 struct gdbarch
*gdbarch
= regcache
->arch ();
3367 CORE_ADDR pc
= regcache_read_pc (regcache
);
3368 int leave_stopped
= 0;
3370 /* Don't bother if there's a breakpoint at PC that we'd hit
3371 immediately, and we're not waiting for this LWP. */
3372 if (!lp
->ptid
.matches (wait_ptid
))
3374 if (breakpoint_inserted_here_p (regcache
->aspace (), pc
))
3380 linux_nat_debug_printf
3381 ("resuming stopped-resumed LWP %s at %s: step=%d",
3382 lp
->ptid
.to_string ().c_str (), paddress (gdbarch
, pc
),
3385 linux_resume_one_lwp_throw (lp
, lp
->step
, GDB_SIGNAL_0
);
3388 catch (const gdb_exception_error
&ex
)
3390 if (!check_ptrace_stopped_lwp_gone (lp
))
3399 linux_nat_target::wait (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3400 target_wait_flags target_options
)
3404 linux_nat_debug_printf ("[%s], [%s]", ptid
.to_string ().c_str (),
3405 target_options_to_string (target_options
).c_str ());
3407 /* Flush the async file first. */
3408 if (target_is_async_p ())
3409 async_file_flush ();
3411 /* Resume LWPs that are currently stopped without any pending status
3412 to report, but are resumed from the core's perspective. LWPs get
3413 in this state if we find them stopping at a time we're not
3414 interested in reporting the event (target_wait on a
3415 specific_process, for example, see linux_nat_wait_1), and
3416 meanwhile the event became uninteresting. Don't bother resuming
3417 LWPs we're not going to wait for if they'd stop immediately. */
3418 if (target_is_non_stop_p ())
3419 iterate_over_lwps (minus_one_ptid
,
3420 [=] (struct lwp_info
*info
)
3422 return resume_stopped_resumed_lwps (info
, ptid
);
3425 event_ptid
= linux_nat_wait_1 (ptid
, ourstatus
, target_options
);
3427 /* If we requested any event, and something came out, assume there
3428 may be more. If we requested a specific lwp or process, also
3429 assume there may be more. */
3430 if (target_is_async_p ()
3431 && ((ourstatus
->kind () != TARGET_WAITKIND_IGNORE
3432 && ourstatus
->kind () != TARGET_WAITKIND_NO_RESUMED
)
3433 || ptid
!= minus_one_ptid
))
3442 kill_one_lwp (pid_t pid
)
3444 /* PTRACE_KILL may resume the inferior. Send SIGKILL first. */
3447 kill_lwp (pid
, SIGKILL
);
3449 if (debug_linux_nat
)
3451 int save_errno
= errno
;
3453 linux_nat_debug_printf
3454 ("kill (SIGKILL) %ld, 0, 0 (%s)", (long) pid
,
3455 save_errno
!= 0 ? safe_strerror (save_errno
) : "OK");
3458 /* Some kernels ignore even SIGKILL for processes under ptrace. */
3461 ptrace (PTRACE_KILL
, pid
, 0, 0);
3462 if (debug_linux_nat
)
3464 int save_errno
= errno
;
3466 linux_nat_debug_printf
3467 ("PTRACE_KILL %ld, 0, 0 (%s)", (long) pid
,
3468 save_errno
? safe_strerror (save_errno
) : "OK");
3472 /* Wait for an LWP to die. */
3475 kill_wait_one_lwp (pid_t pid
)
3479 /* We must make sure that there are no pending events (delayed
3480 SIGSTOPs, pending SIGTRAPs, etc.) to make sure the current
3481 program doesn't interfere with any following debugging session. */
3485 res
= my_waitpid (pid
, NULL
, __WALL
);
3486 if (res
!= (pid_t
) -1)
3488 linux_nat_debug_printf ("wait %ld received unknown.", (long) pid
);
3490 /* The Linux kernel sometimes fails to kill a thread
3491 completely after PTRACE_KILL; that goes from the stop
3492 point in do_fork out to the one in get_signal_to_deliver
3493 and waits again. So kill it again. */
3499 gdb_assert (res
== -1 && errno
== ECHILD
);
3502 /* Callback for iterate_over_lwps. */
3505 kill_callback (struct lwp_info
*lp
)
3507 kill_one_lwp (lp
->ptid
.lwp ());
3511 /* Callback for iterate_over_lwps. */
3514 kill_wait_callback (struct lwp_info
*lp
)
3516 kill_wait_one_lwp (lp
->ptid
.lwp ());
3520 /* Kill the fork children of any threads of inferior INF that are
3521 stopped at a fork event. */
3524 kill_unfollowed_fork_children (struct inferior
*inf
)
3526 for (thread_info
*thread
: inf
->non_exited_threads ())
3528 struct target_waitstatus
*ws
= &thread
->pending_follow
;
3530 if (ws
->kind () == TARGET_WAITKIND_FORKED
3531 || ws
->kind () == TARGET_WAITKIND_VFORKED
)
3533 ptid_t child_ptid
= ws
->child_ptid ();
3534 int child_pid
= child_ptid
.pid ();
3535 int child_lwp
= child_ptid
.lwp ();
3537 kill_one_lwp (child_lwp
);
3538 kill_wait_one_lwp (child_lwp
);
3540 /* Let the arch-specific native code know this process is
3542 linux_target
->low_forget_process (child_pid
);
3548 linux_nat_target::kill ()
3550 /* If we're stopped while forking and we haven't followed yet,
3551 kill the other task. We need to do this first because the
3552 parent will be sleeping if this is a vfork. */
3553 kill_unfollowed_fork_children (current_inferior ());
3555 if (forks_exist_p ())
3556 linux_fork_killall ();
3559 ptid_t ptid
= ptid_t (inferior_ptid
.pid ());
3561 /* Stop all threads before killing them, since ptrace requires
3562 that the thread is stopped to successfully PTRACE_KILL. */
3563 iterate_over_lwps (ptid
, stop_callback
);
3564 /* ... and wait until all of them have reported back that
3565 they're no longer running. */
3566 iterate_over_lwps (ptid
, stop_wait_callback
);
3568 /* Kill all LWP's ... */
3569 iterate_over_lwps (ptid
, kill_callback
);
3571 /* ... and wait until we've flushed all events. */
3572 iterate_over_lwps (ptid
, kill_wait_callback
);
3575 target_mourn_inferior (inferior_ptid
);
3579 linux_nat_target::mourn_inferior ()
3581 int pid
= inferior_ptid
.pid ();
3583 purge_lwp_list (pid
);
3585 close_proc_mem_file (pid
);
3587 if (! forks_exist_p ())
3588 /* Normal case, no other forks available. */
3589 inf_ptrace_target::mourn_inferior ();
3591 /* Multi-fork case. The current inferior_ptid has exited, but
3592 there are other viable forks to debug. Delete the exiting
3593 one and context-switch to the first available. */
3594 linux_fork_mourn_inferior ();
3596 /* Let the arch-specific native code know this process is gone. */
3597 linux_target
->low_forget_process (pid
);
3600 /* Convert a native/host siginfo object, into/from the siginfo in the
3601 layout of the inferiors' architecture. */
3604 siginfo_fixup (siginfo_t
*siginfo
, gdb_byte
*inf_siginfo
, int direction
)
3606 /* If the low target didn't do anything, then just do a straight
3608 if (!linux_target
->low_siginfo_fixup (siginfo
, inf_siginfo
, direction
))
3611 memcpy (siginfo
, inf_siginfo
, sizeof (siginfo_t
));
3613 memcpy (inf_siginfo
, siginfo
, sizeof (siginfo_t
));
3617 static enum target_xfer_status
3618 linux_xfer_siginfo (enum target_object object
,
3619 const char *annex
, gdb_byte
*readbuf
,
3620 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3621 ULONGEST
*xfered_len
)
3625 gdb_byte inf_siginfo
[sizeof (siginfo_t
)];
3627 gdb_assert (object
== TARGET_OBJECT_SIGNAL_INFO
);
3628 gdb_assert (readbuf
|| writebuf
);
3630 pid
= inferior_ptid
.lwp ();
3632 pid
= inferior_ptid
.pid ();
3634 if (offset
> sizeof (siginfo
))
3635 return TARGET_XFER_E_IO
;
3638 ptrace (PTRACE_GETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, &siginfo
);
3640 return TARGET_XFER_E_IO
;
3642 /* When GDB is built as a 64-bit application, ptrace writes into
3643 SIGINFO an object with 64-bit layout. Since debugging a 32-bit
3644 inferior with a 64-bit GDB should look the same as debugging it
3645 with a 32-bit GDB, we need to convert it. GDB core always sees
3646 the converted layout, so any read/write will have to be done
3648 siginfo_fixup (&siginfo
, inf_siginfo
, 0);
3650 if (offset
+ len
> sizeof (siginfo
))
3651 len
= sizeof (siginfo
) - offset
;
3653 if (readbuf
!= NULL
)
3654 memcpy (readbuf
, inf_siginfo
+ offset
, len
);
3657 memcpy (inf_siginfo
+ offset
, writebuf
, len
);
3659 /* Convert back to ptrace layout before flushing it out. */
3660 siginfo_fixup (&siginfo
, inf_siginfo
, 1);
3663 ptrace (PTRACE_SETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, &siginfo
);
3665 return TARGET_XFER_E_IO
;
3669 return TARGET_XFER_OK
;
3672 static enum target_xfer_status
3673 linux_nat_xfer_osdata (enum target_object object
,
3674 const char *annex
, gdb_byte
*readbuf
,
3675 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3676 ULONGEST
*xfered_len
);
3678 static enum target_xfer_status
3679 linux_proc_xfer_memory_partial (gdb_byte
*readbuf
, const gdb_byte
*writebuf
,
3680 ULONGEST offset
, LONGEST len
, ULONGEST
*xfered_len
);
3682 enum target_xfer_status
3683 linux_nat_target::xfer_partial (enum target_object object
,
3684 const char *annex
, gdb_byte
*readbuf
,
3685 const gdb_byte
*writebuf
,
3686 ULONGEST offset
, ULONGEST len
, ULONGEST
*xfered_len
)
3688 if (object
== TARGET_OBJECT_SIGNAL_INFO
)
3689 return linux_xfer_siginfo (object
, annex
, readbuf
, writebuf
,
3690 offset
, len
, xfered_len
);
3692 /* The target is connected but no live inferior is selected. Pass
3693 this request down to a lower stratum (e.g., the executable
3695 if (object
== TARGET_OBJECT_MEMORY
&& inferior_ptid
== null_ptid
)
3696 return TARGET_XFER_EOF
;
3698 if (object
== TARGET_OBJECT_AUXV
)
3699 return memory_xfer_auxv (this, object
, annex
, readbuf
, writebuf
,
3700 offset
, len
, xfered_len
);
3702 if (object
== TARGET_OBJECT_OSDATA
)
3703 return linux_nat_xfer_osdata (object
, annex
, readbuf
, writebuf
,
3704 offset
, len
, xfered_len
);
3706 if (object
== TARGET_OBJECT_MEMORY
)
3708 /* GDB calculates all addresses in the largest possible address
3709 width. The address width must be masked before its final use
3710 by linux_proc_xfer_partial.
3712 Compare ADDR_BIT first to avoid a compiler warning on shift overflow. */
3713 int addr_bit
= gdbarch_addr_bit (target_gdbarch ());
3715 if (addr_bit
< (sizeof (ULONGEST
) * HOST_CHAR_BIT
))
3716 offset
&= ((ULONGEST
) 1 << addr_bit
) - 1;
3718 return linux_proc_xfer_memory_partial (readbuf
, writebuf
,
3719 offset
, len
, xfered_len
);
3722 return inf_ptrace_target::xfer_partial (object
, annex
, readbuf
, writebuf
,
3723 offset
, len
, xfered_len
);
3727 linux_nat_target::thread_alive (ptid_t ptid
)
3729 /* As long as a PTID is in lwp list, consider it alive. */
3730 return find_lwp_pid (ptid
) != NULL
;
3733 /* Implement the to_update_thread_list target method for this
3737 linux_nat_target::update_thread_list ()
3739 /* We add/delete threads from the list as clone/exit events are
3740 processed, so just try deleting exited threads still in the
3742 delete_exited_threads ();
3744 /* Update the processor core that each lwp/thread was last seen
3746 for (lwp_info
*lwp
: all_lwps ())
3748 /* Avoid accessing /proc if the thread hasn't run since we last
3749 time we fetched the thread's core. Accessing /proc becomes
3750 noticeably expensive when we have thousands of LWPs. */
3751 if (lwp
->core
== -1)
3752 lwp
->core
= linux_common_core_of_thread (lwp
->ptid
);
3757 linux_nat_target::pid_to_str (ptid_t ptid
)
3760 && (ptid
.pid () != ptid
.lwp ()
3761 || num_lwps (ptid
.pid ()) > 1))
3762 return string_printf ("LWP %ld", ptid
.lwp ());
3764 return normal_pid_to_str (ptid
);
3768 linux_nat_target::thread_name (struct thread_info
*thr
)
3770 return linux_proc_tid_get_name (thr
->ptid
);
3773 /* Accepts an integer PID; Returns a string representing a file that
3774 can be opened to get the symbols for the child process. */
3777 linux_nat_target::pid_to_exec_file (int pid
)
3779 return linux_proc_pid_to_exec_file (pid
);
3782 /* Object representing an /proc/PID/mem open file. We keep one such
3783 file open per inferior.
3785 It might be tempting to think about only ever opening one file at
3786 most for all inferiors, closing/reopening the file as we access
3787 memory of different inferiors, to minimize number of file
3788 descriptors open, which can otherwise run into resource limits.
3789 However, that does not work correctly -- if the inferior execs and
3790 we haven't processed the exec event yet, and, we opened a
3791 /proc/PID/mem file, we will get a mem file accessing the post-exec
3792 address space, thinking we're opening it for the pre-exec address
3793 space. That is dangerous as we can poke memory (e.g. clearing
3794 breakpoints) in the post-exec memory by mistake, corrupting the
3795 inferior. For that reason, we open the mem file as early as
3796 possible, right after spawning, forking or attaching to the
3797 inferior, when the inferior is stopped and thus before it has a
3800 Note that after opening the file, even if the thread we opened it
3801 for subsequently exits, the open file is still usable for accessing
3802 memory. It's only when the whole process exits or execs that the
3803 file becomes invalid, at which point reads/writes return EOF. */
3808 proc_mem_file (ptid_t ptid
, int fd
)
3809 : m_ptid (ptid
), m_fd (fd
)
3811 gdb_assert (m_fd
!= -1);
3816 linux_nat_debug_printf ("closing fd %d for /proc/%d/task/%ld/mem",
3817 m_fd
, m_ptid
.pid (), m_ptid
.lwp ());
3821 DISABLE_COPY_AND_ASSIGN (proc_mem_file
);
3829 /* The LWP this file was opened for. Just for debugging
3833 /* The file descriptor. */
3837 /* The map between an inferior process id, and the open /proc/PID/mem
3838 file. This is stored in a map instead of in a per-inferior
3839 structure because we need to be able to access memory of processes
3840 which don't have a corresponding struct inferior object. E.g.,
3841 with "detach-on-fork on" (the default), and "follow-fork parent"
3842 (also default), we don't create an inferior for the fork child, but
3843 we still need to remove breakpoints from the fork child's
3845 static std::unordered_map
<int, proc_mem_file
> proc_mem_file_map
;
3847 /* Close the /proc/PID/mem file for PID. */
3850 close_proc_mem_file (pid_t pid
)
3852 proc_mem_file_map
.erase (pid
);
3855 /* Open the /proc/PID/mem file for the process (thread group) of PTID.
3856 We actually open /proc/PID/task/LWP/mem, as that's the LWP we know
3857 exists and is stopped right now. We prefer the
3858 /proc/PID/task/LWP/mem form over /proc/LWP/mem to avoid tid-reuse
3859 races, just in case this is ever called on an already-waited
3863 open_proc_mem_file (ptid_t ptid
)
3865 auto iter
= proc_mem_file_map
.find (ptid
.pid ());
3866 gdb_assert (iter
== proc_mem_file_map
.end ());
3869 xsnprintf (filename
, sizeof filename
,
3870 "/proc/%d/task/%ld/mem", ptid
.pid (), ptid
.lwp ());
3872 int fd
= gdb_open_cloexec (filename
, O_RDWR
| O_LARGEFILE
, 0).release ();
3876 warning (_("opening /proc/PID/mem file for lwp %d.%ld failed: %s (%d)"),
3877 ptid
.pid (), ptid
.lwp (),
3878 safe_strerror (errno
), errno
);
3882 proc_mem_file_map
.emplace (std::piecewise_construct
,
3883 std::forward_as_tuple (ptid
.pid ()),
3884 std::forward_as_tuple (ptid
, fd
));
3886 linux_nat_debug_printf ("opened fd %d for lwp %d.%ld",
3887 fd
, ptid
.pid (), ptid
.lwp ());
3890 /* Implement the to_xfer_partial target method using /proc/PID/mem.
3891 Because we can use a single read/write call, this can be much more
3892 efficient than banging away at PTRACE_PEEKTEXT. Also, unlike
3893 PTRACE_PEEKTEXT/PTRACE_POKETEXT, this works with running
3896 static enum target_xfer_status
3897 linux_proc_xfer_memory_partial (gdb_byte
*readbuf
, const gdb_byte
*writebuf
,
3898 ULONGEST offset
, LONGEST len
,
3899 ULONGEST
*xfered_len
)
3903 auto iter
= proc_mem_file_map
.find (inferior_ptid
.pid ());
3904 if (iter
== proc_mem_file_map
.end ())
3905 return TARGET_XFER_EOF
;
3907 int fd
= iter
->second
.fd ();
3909 gdb_assert (fd
!= -1);
3911 /* Use pread64/pwrite64 if available, since they save a syscall and can
3912 handle 64-bit offsets even on 32-bit platforms (for instance, SPARC
3913 debugging a SPARC64 application). */
3915 ret
= (readbuf
? pread64 (fd
, readbuf
, len
, offset
)
3916 : pwrite64 (fd
, writebuf
, len
, offset
));
3918 ret
= lseek (fd
, offset
, SEEK_SET
);
3920 ret
= (readbuf
? read (fd
, readbuf
, len
)
3921 : write (fd
, writebuf
, len
));
3926 linux_nat_debug_printf ("accessing fd %d for pid %d failed: %s (%d)",
3927 fd
, inferior_ptid
.pid (),
3928 safe_strerror (errno
), errno
);
3929 return TARGET_XFER_EOF
;
3933 /* EOF means the address space is gone, the whole process exited
3935 linux_nat_debug_printf ("accessing fd %d for pid %d got EOF",
3936 fd
, inferior_ptid
.pid ());
3937 return TARGET_XFER_EOF
;
3942 return TARGET_XFER_OK
;
3946 /* Parse LINE as a signal set and add its set bits to SIGS. */
3949 add_line_to_sigset (const char *line
, sigset_t
*sigs
)
3951 int len
= strlen (line
) - 1;
3955 if (line
[len
] != '\n')
3956 error (_("Could not parse signal set: %s"), line
);
3964 if (*p
>= '0' && *p
<= '9')
3966 else if (*p
>= 'a' && *p
<= 'f')
3967 digit
= *p
- 'a' + 10;
3969 error (_("Could not parse signal set: %s"), line
);
3974 sigaddset (sigs
, signum
+ 1);
3976 sigaddset (sigs
, signum
+ 2);
3978 sigaddset (sigs
, signum
+ 3);
3980 sigaddset (sigs
, signum
+ 4);
3986 /* Find process PID's pending signals from /proc/pid/status and set
3990 linux_proc_pending_signals (int pid
, sigset_t
*pending
,
3991 sigset_t
*blocked
, sigset_t
*ignored
)
3993 char buffer
[PATH_MAX
], fname
[PATH_MAX
];
3995 sigemptyset (pending
);
3996 sigemptyset (blocked
);
3997 sigemptyset (ignored
);
3998 xsnprintf (fname
, sizeof fname
, "/proc/%d/status", pid
);
3999 gdb_file_up procfile
= gdb_fopen_cloexec (fname
, "r");
4000 if (procfile
== NULL
)
4001 error (_("Could not open %s"), fname
);
4003 while (fgets (buffer
, PATH_MAX
, procfile
.get ()) != NULL
)
4005 /* Normal queued signals are on the SigPnd line in the status
4006 file. However, 2.6 kernels also have a "shared" pending
4007 queue for delivering signals to a thread group, so check for
4010 Unfortunately some Red Hat kernels include the shared pending
4011 queue but not the ShdPnd status field. */
4013 if (startswith (buffer
, "SigPnd:\t"))
4014 add_line_to_sigset (buffer
+ 8, pending
);
4015 else if (startswith (buffer
, "ShdPnd:\t"))
4016 add_line_to_sigset (buffer
+ 8, pending
);
4017 else if (startswith (buffer
, "SigBlk:\t"))
4018 add_line_to_sigset (buffer
+ 8, blocked
);
4019 else if (startswith (buffer
, "SigIgn:\t"))
4020 add_line_to_sigset (buffer
+ 8, ignored
);
4024 static enum target_xfer_status
4025 linux_nat_xfer_osdata (enum target_object object
,
4026 const char *annex
, gdb_byte
*readbuf
,
4027 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
4028 ULONGEST
*xfered_len
)
4030 gdb_assert (object
== TARGET_OBJECT_OSDATA
);
4032 *xfered_len
= linux_common_xfer_osdata (annex
, readbuf
, offset
, len
);
4033 if (*xfered_len
== 0)
4034 return TARGET_XFER_EOF
;
4036 return TARGET_XFER_OK
;
4039 std::vector
<static_tracepoint_marker
>
4040 linux_nat_target::static_tracepoint_markers_by_strid (const char *strid
)
4042 char s
[IPA_CMD_BUF_SIZE
];
4043 int pid
= inferior_ptid
.pid ();
4044 std::vector
<static_tracepoint_marker
> markers
;
4046 ptid_t ptid
= ptid_t (pid
, 0);
4047 static_tracepoint_marker marker
;
4052 memcpy (s
, "qTfSTM", sizeof ("qTfSTM"));
4053 s
[sizeof ("qTfSTM")] = 0;
4055 agent_run_command (pid
, s
, strlen (s
) + 1);
4058 SCOPE_EXIT
{ target_continue_no_signal (ptid
); };
4064 parse_static_tracepoint_marker_definition (p
, &p
, &marker
);
4066 if (strid
== NULL
|| marker
.str_id
== strid
)
4067 markers
.push_back (std::move (marker
));
4069 while (*p
++ == ','); /* comma-separated list */
4071 memcpy (s
, "qTsSTM", sizeof ("qTsSTM"));
4072 s
[sizeof ("qTsSTM")] = 0;
4073 agent_run_command (pid
, s
, strlen (s
) + 1);
4080 /* target_can_async_p implementation. */
4083 linux_nat_target::can_async_p ()
4085 /* This flag should be checked in the common target.c code. */
4086 gdb_assert (target_async_permitted
);
4088 /* Otherwise, this targets is always able to support async mode. */
4093 linux_nat_target::supports_non_stop ()
4098 /* to_always_non_stop_p implementation. */
4101 linux_nat_target::always_non_stop_p ()
4107 linux_nat_target::supports_multi_process ()
4113 linux_nat_target::supports_disable_randomization ()
4118 /* SIGCHLD handler that serves two purposes: In non-stop/async mode,
4119 so we notice when any child changes state, and notify the
4120 event-loop; it allows us to use sigsuspend in linux_nat_wait_1
4121 above to wait for the arrival of a SIGCHLD. */
4124 sigchld_handler (int signo
)
4126 int old_errno
= errno
;
4128 if (debug_linux_nat
)
4129 gdb_stdlog
->write_async_safe ("sigchld\n", sizeof ("sigchld\n") - 1);
4131 if (signo
== SIGCHLD
)
4133 /* Let the event loop know that there are events to handle. */
4134 linux_nat_target::async_file_mark_if_open ();
4140 /* Callback registered with the target events file descriptor. */
4143 handle_target_event (int error
, gdb_client_data client_data
)
4145 inferior_event_handler (INF_REG_EVENT
);
4148 /* target_async implementation. */
4151 linux_nat_target::async (int enable
)
4153 if ((enable
!= 0) == is_async_p ())
4156 /* Block child signals while we create/destroy the pipe, as their
4157 handler writes to it. */
4158 gdb::block_signals blocker
;
4162 if (!async_file_open ())
4163 internal_error (__FILE__
, __LINE__
, "creating event pipe failed.");
4165 add_file_handler (async_wait_fd (), handle_target_event
, NULL
,
4168 /* There may be pending events to handle. Tell the event loop
4174 delete_file_handler (async_wait_fd ());
4175 async_file_close ();
4179 /* Stop an LWP, and push a GDB_SIGNAL_0 stop status if no other
4183 linux_nat_stop_lwp (struct lwp_info
*lwp
)
4187 linux_nat_debug_printf ("running -> suspending %s",
4188 lwp
->ptid
.to_string ().c_str ());
4191 if (lwp
->last_resume_kind
== resume_stop
)
4193 linux_nat_debug_printf ("already stopping LWP %ld at GDB's request",
4198 stop_callback (lwp
);
4199 lwp
->last_resume_kind
= resume_stop
;
4203 /* Already known to be stopped; do nothing. */
4205 if (debug_linux_nat
)
4207 if (find_thread_ptid (linux_target
, lwp
->ptid
)->stop_requested
)
4208 linux_nat_debug_printf ("already stopped/stop_requested %s",
4209 lwp
->ptid
.to_string ().c_str ());
4211 linux_nat_debug_printf ("already stopped/no stop_requested yet %s",
4212 lwp
->ptid
.to_string ().c_str ());
4219 linux_nat_target::stop (ptid_t ptid
)
4221 LINUX_NAT_SCOPED_DEBUG_ENTER_EXIT
;
4222 iterate_over_lwps (ptid
, linux_nat_stop_lwp
);
4225 /* When requests are passed down from the linux-nat layer to the
4226 single threaded inf-ptrace layer, ptids of (lwpid,0,0) form are
4227 used. The address space pointer is stored in the inferior object,
4228 but the common code that is passed such ptid can't tell whether
4229 lwpid is a "main" process id or not (it assumes so). We reverse
4230 look up the "main" process id from the lwp here. */
4232 struct address_space
*
4233 linux_nat_target::thread_address_space (ptid_t ptid
)
4235 struct lwp_info
*lwp
;
4236 struct inferior
*inf
;
4239 if (ptid
.lwp () == 0)
4241 /* An (lwpid,0,0) ptid. Look up the lwp object to get at the
4243 lwp
= find_lwp_pid (ptid
);
4244 pid
= lwp
->ptid
.pid ();
4248 /* A (pid,lwpid,0) ptid. */
4252 inf
= find_inferior_pid (this, pid
);
4253 gdb_assert (inf
!= NULL
);
4257 /* Return the cached value of the processor core for thread PTID. */
4260 linux_nat_target::core_of_thread (ptid_t ptid
)
4262 struct lwp_info
*info
= find_lwp_pid (ptid
);
4269 /* Implementation of to_filesystem_is_local. */
4272 linux_nat_target::filesystem_is_local ()
4274 struct inferior
*inf
= current_inferior ();
4276 if (inf
->fake_pid_p
|| inf
->pid
== 0)
4279 return linux_ns_same (inf
->pid
, LINUX_NS_MNT
);
4282 /* Convert the INF argument passed to a to_fileio_* method
4283 to a process ID suitable for passing to its corresponding
4284 linux_mntns_* function. If INF is non-NULL then the
4285 caller is requesting the filesystem seen by INF. If INF
4286 is NULL then the caller is requesting the filesystem seen
4287 by the GDB. We fall back to GDB's filesystem in the case
4288 that INF is non-NULL but its PID is unknown. */
4291 linux_nat_fileio_pid_of (struct inferior
*inf
)
4293 if (inf
== NULL
|| inf
->fake_pid_p
|| inf
->pid
== 0)
4299 /* Implementation of to_fileio_open. */
4302 linux_nat_target::fileio_open (struct inferior
*inf
, const char *filename
,
4303 int flags
, int mode
, int warn_if_slow
,
4310 if (fileio_to_host_openflags (flags
, &nat_flags
) == -1
4311 || fileio_to_host_mode (mode
, &nat_mode
) == -1)
4313 *target_errno
= FILEIO_EINVAL
;
4317 fd
= linux_mntns_open_cloexec (linux_nat_fileio_pid_of (inf
),
4318 filename
, nat_flags
, nat_mode
);
4320 *target_errno
= host_to_fileio_error (errno
);
4325 /* Implementation of to_fileio_readlink. */
4327 gdb::optional
<std::string
>
4328 linux_nat_target::fileio_readlink (struct inferior
*inf
, const char *filename
,
4334 len
= linux_mntns_readlink (linux_nat_fileio_pid_of (inf
),
4335 filename
, buf
, sizeof (buf
));
4338 *target_errno
= host_to_fileio_error (errno
);
4342 return std::string (buf
, len
);
4345 /* Implementation of to_fileio_unlink. */
4348 linux_nat_target::fileio_unlink (struct inferior
*inf
, const char *filename
,
4353 ret
= linux_mntns_unlink (linux_nat_fileio_pid_of (inf
),
4356 *target_errno
= host_to_fileio_error (errno
);
4361 /* Implementation of the to_thread_events method. */
4364 linux_nat_target::thread_events (int enable
)
4366 report_thread_events
= enable
;
4369 linux_nat_target::linux_nat_target ()
4371 /* We don't change the stratum; this target will sit at
4372 process_stratum and thread_db will set at thread_stratum. This
4373 is a little strange, since this is a multi-threaded-capable
4374 target, but we want to be on the stack below thread_db, and we
4375 also want to be used for single-threaded processes. */
4378 /* See linux-nat.h. */
4381 linux_nat_get_siginfo (ptid_t ptid
, siginfo_t
*siginfo
)
4390 ptrace (PTRACE_GETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, siginfo
);
4393 memset (siginfo
, 0, sizeof (*siginfo
));
4399 /* See nat/linux-nat.h. */
4402 current_lwp_ptid (void)
4404 gdb_assert (inferior_ptid
.lwp_p ());
4405 return inferior_ptid
;
4408 void _initialize_linux_nat ();
4410 _initialize_linux_nat ()
4412 add_setshow_boolean_cmd ("linux-nat", class_maintenance
,
4413 &debug_linux_nat
, _("\
4414 Set debugging of GNU/Linux native target."), _(" \
4415 Show debugging of GNU/Linux native target."), _(" \
4416 When on, print debug messages relating to the GNU/Linux native target."),
4418 show_debug_linux_nat
,
4419 &setdebuglist
, &showdebuglist
);
4421 add_setshow_boolean_cmd ("linux-namespaces", class_maintenance
,
4422 &debug_linux_namespaces
, _("\
4423 Set debugging of GNU/Linux namespaces module."), _("\
4424 Show debugging of GNU/Linux namespaces module."), _("\
4425 Enables printf debugging output."),
4428 &setdebuglist
, &showdebuglist
);
4430 /* Install a SIGCHLD handler. */
4431 sigchld_action
.sa_handler
= sigchld_handler
;
4432 sigemptyset (&sigchld_action
.sa_mask
);
4433 sigchld_action
.sa_flags
= SA_RESTART
;
4435 /* Make it the default. */
4436 sigaction (SIGCHLD
, &sigchld_action
, NULL
);
4438 /* Make sure we don't block SIGCHLD during a sigsuspend. */
4439 gdb_sigmask (SIG_SETMASK
, NULL
, &suspend_mask
);
4440 sigdelset (&suspend_mask
, SIGCHLD
);
4442 sigemptyset (&blocked_mask
);
4444 lwp_lwpid_htab_create ();
4448 /* FIXME: kettenis/2000-08-26: The stuff on this page is specific to
4449 the GNU/Linux Threads library and therefore doesn't really belong
4452 /* NPTL reserves the first two RT signals, but does not provide any
4453 way for the debugger to query the signal numbers - fortunately
4454 they don't change. */
4455 static int lin_thread_signals
[] = { __SIGRTMIN
, __SIGRTMIN
+ 1 };
4457 /* See linux-nat.h. */
4460 lin_thread_get_thread_signal_num (void)
4462 return sizeof (lin_thread_signals
) / sizeof (lin_thread_signals
[0]);
4465 /* See linux-nat.h. */
4468 lin_thread_get_thread_signal (unsigned int i
)
4470 gdb_assert (i
< lin_thread_get_thread_signal_num ());
4471 return lin_thread_signals
[i
];