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 scope_ptid
, int step
, enum gdb_signal signo
)
1600 struct lwp_info
*lp
;
1602 linux_nat_debug_printf ("Preparing to %s %s, %s, inferior_ptid %s",
1603 step
? "step" : "resume",
1604 scope_ptid
.to_string ().c_str (),
1605 (signo
!= GDB_SIGNAL_0
1606 ? strsignal (gdb_signal_to_host (signo
)) : "0"),
1607 inferior_ptid
.to_string ().c_str ());
1609 /* Mark the lwps we're resuming as resumed and update their
1610 last_resume_kind to resume_continue. */
1611 iterate_over_lwps (scope_ptid
, resume_set_callback
);
1613 lp
= find_lwp_pid (inferior_ptid
);
1614 gdb_assert (lp
!= NULL
);
1616 /* Remember if we're stepping. */
1617 lp
->last_resume_kind
= step
? resume_step
: resume_continue
;
1619 /* If we have a pending wait status for this thread, there is no
1620 point in resuming the process. But first make sure that
1621 linux_nat_wait won't preemptively handle the event - we
1622 should never take this short-circuit if we are going to
1623 leave LP running, since we have skipped resuming all the
1624 other threads. This bit of code needs to be synchronized
1625 with linux_nat_wait. */
1627 if (lp
->status
&& WIFSTOPPED (lp
->status
))
1630 && WSTOPSIG (lp
->status
)
1631 && sigismember (&pass_mask
, WSTOPSIG (lp
->status
)))
1633 linux_nat_debug_printf
1634 ("Not short circuiting for ignored status 0x%x", lp
->status
);
1636 /* FIXME: What should we do if we are supposed to continue
1637 this thread with a signal? */
1638 gdb_assert (signo
== GDB_SIGNAL_0
);
1639 signo
= gdb_signal_from_host (WSTOPSIG (lp
->status
));
1644 if (lwp_status_pending_p (lp
))
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
);
1650 linux_nat_debug_printf ("Short circuiting for status 0x%x",
1653 if (target_can_async_p ())
1656 /* Tell the event loop we have something to process. */
1662 /* No use iterating unless we're resuming other threads. */
1663 if (scope_ptid
!= lp
->ptid
)
1664 iterate_over_lwps (scope_ptid
, [=] (struct lwp_info
*info
)
1666 return linux_nat_resume_callback (info
, lp
);
1669 linux_nat_debug_printf ("%s %s, %s (resume event thread)",
1670 step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
1671 lp
->ptid
.to_string ().c_str (),
1672 (signo
!= GDB_SIGNAL_0
1673 ? strsignal (gdb_signal_to_host (signo
)) : "0"));
1675 linux_resume_one_lwp (lp
, step
, signo
);
1678 /* Send a signal to an LWP. */
1681 kill_lwp (int lwpid
, int signo
)
1686 ret
= syscall (__NR_tkill
, lwpid
, signo
);
1687 if (errno
== ENOSYS
)
1689 /* If tkill fails, then we are not using nptl threads, a
1690 configuration we no longer support. */
1691 perror_with_name (("tkill"));
1696 /* Handle a GNU/Linux syscall trap wait response. If we see a syscall
1697 event, check if the core is interested in it: if not, ignore the
1698 event, and keep waiting; otherwise, we need to toggle the LWP's
1699 syscall entry/exit status, since the ptrace event itself doesn't
1700 indicate it, and report the trap to higher layers. */
1703 linux_handle_syscall_trap (struct lwp_info
*lp
, int stopping
)
1705 struct target_waitstatus
*ourstatus
= &lp
->waitstatus
;
1706 struct gdbarch
*gdbarch
= target_thread_architecture (lp
->ptid
);
1707 thread_info
*thread
= find_thread_ptid (linux_target
, lp
->ptid
);
1708 int syscall_number
= (int) gdbarch_get_syscall_number (gdbarch
, thread
);
1712 /* If we're stopping threads, there's a SIGSTOP pending, which
1713 makes it so that the LWP reports an immediate syscall return,
1714 followed by the SIGSTOP. Skip seeing that "return" using
1715 PTRACE_CONT directly, and let stop_wait_callback collect the
1716 SIGSTOP. Later when the thread is resumed, a new syscall
1717 entry event. If we didn't do this (and returned 0), we'd
1718 leave a syscall entry pending, and our caller, by using
1719 PTRACE_CONT to collect the SIGSTOP, skips the syscall return
1720 itself. Later, when the user re-resumes this LWP, we'd see
1721 another syscall entry event and we'd mistake it for a return.
1723 If stop_wait_callback didn't force the SIGSTOP out of the LWP
1724 (leaving immediately with LWP->signalled set, without issuing
1725 a PTRACE_CONT), it would still be problematic to leave this
1726 syscall enter pending, as later when the thread is resumed,
1727 it would then see the same syscall exit mentioned above,
1728 followed by the delayed SIGSTOP, while the syscall didn't
1729 actually get to execute. It seems it would be even more
1730 confusing to the user. */
1732 linux_nat_debug_printf
1733 ("ignoring syscall %d for LWP %ld (stopping threads), resuming with "
1734 "PTRACE_CONT for SIGSTOP", syscall_number
, lp
->ptid
.lwp ());
1736 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
1737 ptrace (PTRACE_CONT
, lp
->ptid
.lwp (), 0, 0);
1742 /* Always update the entry/return state, even if this particular
1743 syscall isn't interesting to the core now. In async mode,
1744 the user could install a new catchpoint for this syscall
1745 between syscall enter/return, and we'll need to know to
1746 report a syscall return if that happens. */
1747 lp
->syscall_state
= (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1748 ? TARGET_WAITKIND_SYSCALL_RETURN
1749 : TARGET_WAITKIND_SYSCALL_ENTRY
);
1751 if (catch_syscall_enabled ())
1753 if (catching_syscall_number (syscall_number
))
1755 /* Alright, an event to report. */
1756 if (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
)
1757 ourstatus
->set_syscall_entry (syscall_number
);
1758 else if (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_RETURN
)
1759 ourstatus
->set_syscall_return (syscall_number
);
1761 gdb_assert_not_reached ("unexpected syscall state");
1763 linux_nat_debug_printf
1764 ("stopping for %s of syscall %d for LWP %ld",
1765 (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1766 ? "entry" : "return"), syscall_number
, lp
->ptid
.lwp ());
1771 linux_nat_debug_printf
1772 ("ignoring %s of syscall %d for LWP %ld",
1773 (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1774 ? "entry" : "return"), syscall_number
, lp
->ptid
.lwp ());
1778 /* If we had been syscall tracing, and hence used PT_SYSCALL
1779 before on this LWP, it could happen that the user removes all
1780 syscall catchpoints before we get to process this event.
1781 There are two noteworthy issues here:
1783 - When stopped at a syscall entry event, resuming with
1784 PT_STEP still resumes executing the syscall and reports a
1787 - Only PT_SYSCALL catches syscall enters. If we last
1788 single-stepped this thread, then this event can't be a
1789 syscall enter. If we last single-stepped this thread, this
1790 has to be a syscall exit.
1792 The points above mean that the next resume, be it PT_STEP or
1793 PT_CONTINUE, can not trigger a syscall trace event. */
1794 linux_nat_debug_printf
1795 ("caught syscall event with no syscall catchpoints. %d for LWP %ld, "
1796 "ignoring", syscall_number
, lp
->ptid
.lwp ());
1797 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
1800 /* The core isn't interested in this event. For efficiency, avoid
1801 stopping all threads only to have the core resume them all again.
1802 Since we're not stopping threads, if we're still syscall tracing
1803 and not stepping, we can't use PTRACE_CONT here, as we'd miss any
1804 subsequent syscall. Simply resume using the inf-ptrace layer,
1805 which knows when to use PT_SYSCALL or PT_CONTINUE. */
1807 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
1811 /* Handle a GNU/Linux extended wait response. If we see a clone
1812 event, we need to add the new LWP to our list (and not report the
1813 trap to higher layers). This function returns non-zero if the
1814 event should be ignored and we should wait again. If STOPPING is
1815 true, the new LWP remains stopped, otherwise it is continued. */
1818 linux_handle_extended_wait (struct lwp_info
*lp
, int status
)
1820 int pid
= lp
->ptid
.lwp ();
1821 struct target_waitstatus
*ourstatus
= &lp
->waitstatus
;
1822 int event
= linux_ptrace_get_extended_event (status
);
1824 /* All extended events we currently use are mid-syscall. Only
1825 PTRACE_EVENT_STOP is delivered more like a signal-stop, but
1826 you have to be using PTRACE_SEIZE to get that. */
1827 lp
->syscall_state
= TARGET_WAITKIND_SYSCALL_ENTRY
;
1829 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
1830 || event
== PTRACE_EVENT_CLONE
)
1832 unsigned long new_pid
;
1835 ptrace (PTRACE_GETEVENTMSG
, pid
, 0, &new_pid
);
1837 /* If we haven't already seen the new PID stop, wait for it now. */
1838 if (! pull_pid_from_list (&stopped_pids
, new_pid
, &status
))
1840 /* The new child has a pending SIGSTOP. We can't affect it until it
1841 hits the SIGSTOP, but we're already attached. */
1842 ret
= my_waitpid (new_pid
, &status
, __WALL
);
1844 perror_with_name (_("waiting for new child"));
1845 else if (ret
!= new_pid
)
1846 internal_error (__FILE__
, __LINE__
,
1847 _("wait returned unexpected PID %d"), ret
);
1848 else if (!WIFSTOPPED (status
))
1849 internal_error (__FILE__
, __LINE__
,
1850 _("wait returned unexpected status 0x%x"), status
);
1853 ptid_t
child_ptid (new_pid
, new_pid
);
1855 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
)
1857 open_proc_mem_file (child_ptid
);
1859 /* The arch-specific native code may need to know about new
1860 forks even if those end up never mapped to an
1862 linux_target
->low_new_fork (lp
, new_pid
);
1864 else if (event
== PTRACE_EVENT_CLONE
)
1866 linux_target
->low_new_clone (lp
, new_pid
);
1869 if (event
== PTRACE_EVENT_FORK
1870 && linux_fork_checkpointing_p (lp
->ptid
.pid ()))
1872 /* Handle checkpointing by linux-fork.c here as a special
1873 case. We don't want the follow-fork-mode or 'catch fork'
1874 to interfere with this. */
1876 /* This won't actually modify the breakpoint list, but will
1877 physically remove the breakpoints from the child. */
1878 detach_breakpoints (ptid_t (new_pid
, new_pid
));
1880 /* Retain child fork in ptrace (stopped) state. */
1881 if (!find_fork_pid (new_pid
))
1884 /* Report as spurious, so that infrun doesn't want to follow
1885 this fork. We're actually doing an infcall in
1887 ourstatus
->set_spurious ();
1889 /* Report the stop to the core. */
1893 if (event
== PTRACE_EVENT_FORK
)
1894 ourstatus
->set_forked (child_ptid
);
1895 else if (event
== PTRACE_EVENT_VFORK
)
1896 ourstatus
->set_vforked (child_ptid
);
1897 else if (event
== PTRACE_EVENT_CLONE
)
1899 struct lwp_info
*new_lp
;
1901 ourstatus
->set_ignore ();
1903 linux_nat_debug_printf
1904 ("Got clone event from LWP %d, new child is LWP %ld", pid
, new_pid
);
1906 new_lp
= add_lwp (ptid_t (lp
->ptid
.pid (), new_pid
));
1907 new_lp
->stopped
= 1;
1908 new_lp
->resumed
= 1;
1910 /* If the thread_db layer is active, let it record the user
1911 level thread id and status, and add the thread to GDB's
1913 if (!thread_db_notice_clone (lp
->ptid
, new_lp
->ptid
))
1915 /* The process is not using thread_db. Add the LWP to
1917 target_post_attach (new_lp
->ptid
.lwp ());
1918 add_thread (linux_target
, new_lp
->ptid
);
1921 /* Even if we're stopping the thread for some reason
1922 internal to this module, from the perspective of infrun
1923 and the user/frontend, this new thread is running until
1924 it next reports a stop. */
1925 set_running (linux_target
, new_lp
->ptid
, true);
1926 set_executing (linux_target
, new_lp
->ptid
, true);
1928 if (WSTOPSIG (status
) != SIGSTOP
)
1930 /* This can happen if someone starts sending signals to
1931 the new thread before it gets a chance to run, which
1932 have a lower number than SIGSTOP (e.g. SIGUSR1).
1933 This is an unlikely case, and harder to handle for
1934 fork / vfork than for clone, so we do not try - but
1935 we handle it for clone events here. */
1937 new_lp
->signalled
= 1;
1939 /* We created NEW_LP so it cannot yet contain STATUS. */
1940 gdb_assert (new_lp
->status
== 0);
1942 /* Save the wait status to report later. */
1943 linux_nat_debug_printf
1944 ("waitpid of new LWP %ld, saving status %s",
1945 (long) new_lp
->ptid
.lwp (), status_to_str (status
).c_str ());
1946 new_lp
->status
= status
;
1948 else if (report_thread_events
)
1950 new_lp
->waitstatus
.set_thread_created ();
1951 new_lp
->status
= status
;
1960 if (event
== PTRACE_EVENT_EXEC
)
1962 linux_nat_debug_printf ("Got exec event from LWP %ld", lp
->ptid
.lwp ());
1964 /* Close the previous /proc/PID/mem file for this inferior,
1965 which was using the address space which is now gone.
1966 Reading/writing from this file would return 0/EOF. */
1967 close_proc_mem_file (lp
->ptid
.pid ());
1969 /* Open a new file for the new address space. */
1970 open_proc_mem_file (lp
->ptid
);
1972 ourstatus
->set_execd
1973 (make_unique_xstrdup (linux_proc_pid_to_exec_file (pid
)));
1975 /* The thread that execed must have been resumed, but, when a
1976 thread execs, it changes its tid to the tgid, and the old
1977 tgid thread might have not been resumed. */
1982 if (event
== PTRACE_EVENT_VFORK_DONE
)
1984 linux_nat_debug_printf
1985 ("Got PTRACE_EVENT_VFORK_DONE from LWP %ld",
1987 ourstatus
->set_vfork_done ();
1991 internal_error (__FILE__
, __LINE__
,
1992 _("unknown ptrace event %d"), event
);
1995 /* Suspend waiting for a signal. We're mostly interested in
2001 linux_nat_debug_printf ("about to sigsuspend");
2002 sigsuspend (&suspend_mask
);
2004 /* If the quit flag is set, it means that the user pressed Ctrl-C
2005 and we're debugging a process that is running on a separate
2006 terminal, so we must forward the Ctrl-C to the inferior. (If the
2007 inferior is sharing GDB's terminal, then the Ctrl-C reaches the
2008 inferior directly.) We must do this here because functions that
2009 need to block waiting for a signal loop forever until there's an
2010 event to report before returning back to the event loop. */
2011 if (!target_terminal::is_ours ())
2013 if (check_quit_flag ())
2014 target_pass_ctrlc ();
2018 /* Wait for LP to stop. Returns the wait status, or 0 if the LWP has
2022 wait_lwp (struct lwp_info
*lp
)
2026 int thread_dead
= 0;
2029 gdb_assert (!lp
->stopped
);
2030 gdb_assert (lp
->status
== 0);
2032 /* Make sure SIGCHLD is blocked for sigsuspend avoiding a race below. */
2033 block_child_signals (&prev_mask
);
2037 pid
= my_waitpid (lp
->ptid
.lwp (), &status
, __WALL
| WNOHANG
);
2038 if (pid
== -1 && errno
== ECHILD
)
2040 /* The thread has previously exited. We need to delete it
2041 now because if this was a non-leader thread execing, we
2042 won't get an exit event. See comments on exec events at
2043 the top of the file. */
2045 linux_nat_debug_printf ("%s vanished.",
2046 lp
->ptid
.to_string ().c_str ());
2051 /* Bugs 10970, 12702.
2052 Thread group leader may have exited in which case we'll lock up in
2053 waitpid if there are other threads, even if they are all zombies too.
2054 Basically, we're not supposed to use waitpid this way.
2055 tkill(pid,0) cannot be used here as it gets ESRCH for both
2056 for zombie and running processes.
2058 As a workaround, check if we're waiting for the thread group leader and
2059 if it's a zombie, and avoid calling waitpid if it is.
2061 This is racy, what if the tgl becomes a zombie right after we check?
2062 Therefore always use WNOHANG with sigsuspend - it is equivalent to
2063 waiting waitpid but linux_proc_pid_is_zombie is safe this way. */
2065 if (lp
->ptid
.pid () == lp
->ptid
.lwp ()
2066 && linux_proc_pid_is_zombie (lp
->ptid
.lwp ()))
2069 linux_nat_debug_printf ("Thread group leader %s vanished.",
2070 lp
->ptid
.to_string ().c_str ());
2074 /* Wait for next SIGCHLD and try again. This may let SIGCHLD handlers
2075 get invoked despite our caller had them intentionally blocked by
2076 block_child_signals. This is sensitive only to the loop of
2077 linux_nat_wait_1 and there if we get called my_waitpid gets called
2078 again before it gets to sigsuspend so we can safely let the handlers
2079 get executed here. */
2083 restore_child_signals_mask (&prev_mask
);
2087 gdb_assert (pid
== lp
->ptid
.lwp ());
2089 linux_nat_debug_printf ("waitpid %s received %s",
2090 lp
->ptid
.to_string ().c_str (),
2091 status_to_str (status
).c_str ());
2093 /* Check if the thread has exited. */
2094 if (WIFEXITED (status
) || WIFSIGNALED (status
))
2096 if (report_thread_events
2097 || lp
->ptid
.pid () == lp
->ptid
.lwp ())
2099 linux_nat_debug_printf ("LWP %d exited.", lp
->ptid
.pid ());
2101 /* If this is the leader exiting, it means the whole
2102 process is gone. Store the status to report to the
2103 core. Store it in lp->waitstatus, because lp->status
2104 would be ambiguous (W_EXITCODE(0,0) == 0). */
2105 lp
->waitstatus
= host_status_to_waitstatus (status
);
2110 linux_nat_debug_printf ("%s exited.",
2111 lp
->ptid
.to_string ().c_str ());
2121 gdb_assert (WIFSTOPPED (status
));
2124 if (lp
->must_set_ptrace_flags
)
2126 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2127 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
2129 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
2130 lp
->must_set_ptrace_flags
= 0;
2133 /* Handle GNU/Linux's syscall SIGTRAPs. */
2134 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
2136 /* No longer need the sysgood bit. The ptrace event ends up
2137 recorded in lp->waitstatus if we care for it. We can carry
2138 on handling the event like a regular SIGTRAP from here
2140 status
= W_STOPCODE (SIGTRAP
);
2141 if (linux_handle_syscall_trap (lp
, 1))
2142 return wait_lwp (lp
);
2146 /* Almost all other ptrace-stops are known to be outside of system
2147 calls, with further exceptions in linux_handle_extended_wait. */
2148 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
2151 /* Handle GNU/Linux's extended waitstatus for trace events. */
2152 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
2153 && linux_is_extended_waitstatus (status
))
2155 linux_nat_debug_printf ("Handling extended status 0x%06x", status
);
2156 linux_handle_extended_wait (lp
, status
);
2163 /* Send a SIGSTOP to LP. */
2166 stop_callback (struct lwp_info
*lp
)
2168 if (!lp
->stopped
&& !lp
->signalled
)
2172 linux_nat_debug_printf ("kill %s **<SIGSTOP>**",
2173 lp
->ptid
.to_string ().c_str ());
2176 ret
= kill_lwp (lp
->ptid
.lwp (), SIGSTOP
);
2177 linux_nat_debug_printf ("lwp kill %d %s", ret
,
2178 errno
? safe_strerror (errno
) : "ERRNO-OK");
2181 gdb_assert (lp
->status
== 0);
2187 /* Request a stop on LWP. */
2190 linux_stop_lwp (struct lwp_info
*lwp
)
2192 stop_callback (lwp
);
2195 /* See linux-nat.h */
2198 linux_stop_and_wait_all_lwps (void)
2200 /* Stop all LWP's ... */
2201 iterate_over_lwps (minus_one_ptid
, stop_callback
);
2203 /* ... and wait until all of them have reported back that
2204 they're no longer running. */
2205 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
2208 /* See linux-nat.h */
2211 linux_unstop_all_lwps (void)
2213 iterate_over_lwps (minus_one_ptid
,
2214 [] (struct lwp_info
*info
)
2216 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
2220 /* Return non-zero if LWP PID has a pending SIGINT. */
2223 linux_nat_has_pending_sigint (int pid
)
2225 sigset_t pending
, blocked
, ignored
;
2227 linux_proc_pending_signals (pid
, &pending
, &blocked
, &ignored
);
2229 if (sigismember (&pending
, SIGINT
)
2230 && !sigismember (&ignored
, SIGINT
))
2236 /* Set a flag in LP indicating that we should ignore its next SIGINT. */
2239 set_ignore_sigint (struct lwp_info
*lp
)
2241 /* If a thread has a pending SIGINT, consume it; otherwise, set a
2242 flag to consume the next one. */
2243 if (lp
->stopped
&& lp
->status
!= 0 && WIFSTOPPED (lp
->status
)
2244 && WSTOPSIG (lp
->status
) == SIGINT
)
2247 lp
->ignore_sigint
= 1;
2252 /* If LP does not have a SIGINT pending, then clear the ignore_sigint flag.
2253 This function is called after we know the LWP has stopped; if the LWP
2254 stopped before the expected SIGINT was delivered, then it will never have
2255 arrived. Also, if the signal was delivered to a shared queue and consumed
2256 by a different thread, it will never be delivered to this LWP. */
2259 maybe_clear_ignore_sigint (struct lwp_info
*lp
)
2261 if (!lp
->ignore_sigint
)
2264 if (!linux_nat_has_pending_sigint (lp
->ptid
.lwp ()))
2266 linux_nat_debug_printf ("Clearing bogus flag for %s",
2267 lp
->ptid
.to_string ().c_str ());
2268 lp
->ignore_sigint
= 0;
2272 /* Fetch the possible triggered data watchpoint info and store it in
2275 On some archs, like x86, that use debug registers to set
2276 watchpoints, it's possible that the way to know which watched
2277 address trapped, is to check the register that is used to select
2278 which address to watch. Problem is, between setting the watchpoint
2279 and reading back which data address trapped, the user may change
2280 the set of watchpoints, and, as a consequence, GDB changes the
2281 debug registers in the inferior. To avoid reading back a stale
2282 stopped-data-address when that happens, we cache in LP the fact
2283 that a watchpoint trapped, and the corresponding data address, as
2284 soon as we see LP stop with a SIGTRAP. If GDB changes the debug
2285 registers meanwhile, we have the cached data we can rely on. */
2288 check_stopped_by_watchpoint (struct lwp_info
*lp
)
2290 scoped_restore save_inferior_ptid
= make_scoped_restore (&inferior_ptid
);
2291 inferior_ptid
= lp
->ptid
;
2293 if (linux_target
->low_stopped_by_watchpoint ())
2295 lp
->stop_reason
= TARGET_STOPPED_BY_WATCHPOINT
;
2296 lp
->stopped_data_address_p
2297 = linux_target
->low_stopped_data_address (&lp
->stopped_data_address
);
2300 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2303 /* Returns true if the LWP had stopped for a watchpoint. */
2306 linux_nat_target::stopped_by_watchpoint ()
2308 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2310 gdb_assert (lp
!= NULL
);
2312 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2316 linux_nat_target::stopped_data_address (CORE_ADDR
*addr_p
)
2318 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2320 gdb_assert (lp
!= NULL
);
2322 *addr_p
= lp
->stopped_data_address
;
2324 return lp
->stopped_data_address_p
;
2327 /* Commonly any breakpoint / watchpoint generate only SIGTRAP. */
2330 linux_nat_target::low_status_is_event (int status
)
2332 return WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
;
2335 /* Wait until LP is stopped. */
2338 stop_wait_callback (struct lwp_info
*lp
)
2340 inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
2342 /* If this is a vfork parent, bail out, it is not going to report
2343 any SIGSTOP until the vfork is done with. */
2344 if (inf
->vfork_child
!= NULL
)
2351 status
= wait_lwp (lp
);
2355 if (lp
->ignore_sigint
&& WIFSTOPPED (status
)
2356 && WSTOPSIG (status
) == SIGINT
)
2358 lp
->ignore_sigint
= 0;
2361 ptrace (PTRACE_CONT
, lp
->ptid
.lwp (), 0, 0);
2363 linux_nat_debug_printf
2364 ("PTRACE_CONT %s, 0, 0 (%s) (discarding SIGINT)",
2365 lp
->ptid
.to_string ().c_str (),
2366 errno
? safe_strerror (errno
) : "OK");
2368 return stop_wait_callback (lp
);
2371 maybe_clear_ignore_sigint (lp
);
2373 if (WSTOPSIG (status
) != SIGSTOP
)
2375 /* The thread was stopped with a signal other than SIGSTOP. */
2377 linux_nat_debug_printf ("Pending event %s in %s",
2378 status_to_str ((int) status
).c_str (),
2379 lp
->ptid
.to_string ().c_str ());
2381 /* Save the sigtrap event. */
2382 lp
->status
= status
;
2383 gdb_assert (lp
->signalled
);
2384 save_stop_reason (lp
);
2388 /* We caught the SIGSTOP that we intended to catch. */
2390 linux_nat_debug_printf ("Expected SIGSTOP caught for %s.",
2391 lp
->ptid
.to_string ().c_str ());
2395 /* If we are waiting for this stop so we can report the thread
2396 stopped then we need to record this status. Otherwise, we can
2397 now discard this stop event. */
2398 if (lp
->last_resume_kind
== resume_stop
)
2400 lp
->status
= status
;
2401 save_stop_reason (lp
);
2409 /* Return non-zero if LP has a wait status pending. Discard the
2410 pending event and resume the LWP if the event that originally
2411 caused the stop became uninteresting. */
2414 status_callback (struct lwp_info
*lp
)
2416 /* Only report a pending wait status if we pretend that this has
2417 indeed been resumed. */
2421 if (!lwp_status_pending_p (lp
))
2424 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
2425 || lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2427 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2431 pc
= regcache_read_pc (regcache
);
2433 if (pc
!= lp
->stop_pc
)
2435 linux_nat_debug_printf ("PC of %s changed. was=%s, now=%s",
2436 lp
->ptid
.to_string ().c_str (),
2437 paddress (target_gdbarch (), lp
->stop_pc
),
2438 paddress (target_gdbarch (), pc
));
2442 #if !USE_SIGTRAP_SIGINFO
2443 else if (!breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2445 linux_nat_debug_printf ("previous breakpoint of %s, at %s gone",
2446 lp
->ptid
.to_string ().c_str (),
2447 paddress (target_gdbarch (), lp
->stop_pc
));
2455 linux_nat_debug_printf ("pending event of %s cancelled.",
2456 lp
->ptid
.to_string ().c_str ());
2459 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2467 /* Count the LWP's that have had events. */
2470 count_events_callback (struct lwp_info
*lp
, int *count
)
2472 gdb_assert (count
!= NULL
);
2474 /* Select only resumed LWPs that have an event pending. */
2475 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2481 /* Select the LWP (if any) that is currently being single-stepped. */
2484 select_singlestep_lwp_callback (struct lwp_info
*lp
)
2486 if (lp
->last_resume_kind
== resume_step
2493 /* Returns true if LP has a status pending. */
2496 lwp_status_pending_p (struct lwp_info
*lp
)
2498 /* We check for lp->waitstatus in addition to lp->status, because we
2499 can have pending process exits recorded in lp->status and
2500 W_EXITCODE(0,0) happens to be 0. */
2501 return lp
->status
!= 0 || lp
->waitstatus
.kind () != TARGET_WAITKIND_IGNORE
;
2504 /* Select the Nth LWP that has had an event. */
2507 select_event_lwp_callback (struct lwp_info
*lp
, int *selector
)
2509 gdb_assert (selector
!= NULL
);
2511 /* Select only resumed LWPs that have an event pending. */
2512 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2513 if ((*selector
)-- == 0)
2519 /* Called when the LWP stopped for a signal/trap. If it stopped for a
2520 trap check what caused it (breakpoint, watchpoint, trace, etc.),
2521 and save the result in the LWP's stop_reason field. If it stopped
2522 for a breakpoint, decrement the PC if necessary on the lwp's
2526 save_stop_reason (struct lwp_info
*lp
)
2528 struct regcache
*regcache
;
2529 struct gdbarch
*gdbarch
;
2532 #if USE_SIGTRAP_SIGINFO
2536 gdb_assert (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
);
2537 gdb_assert (lp
->status
!= 0);
2539 if (!linux_target
->low_status_is_event (lp
->status
))
2542 regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2543 gdbarch
= regcache
->arch ();
2545 pc
= regcache_read_pc (regcache
);
2546 sw_bp_pc
= pc
- gdbarch_decr_pc_after_break (gdbarch
);
2548 #if USE_SIGTRAP_SIGINFO
2549 if (linux_nat_get_siginfo (lp
->ptid
, &siginfo
))
2551 if (siginfo
.si_signo
== SIGTRAP
)
2553 if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
)
2554 && GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2556 /* The si_code is ambiguous on this arch -- check debug
2558 if (!check_stopped_by_watchpoint (lp
))
2559 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2561 else if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
))
2563 /* If we determine the LWP stopped for a SW breakpoint,
2564 trust it. Particularly don't check watchpoint
2565 registers, because, at least on s390, we'd find
2566 stopped-by-watchpoint as long as there's a watchpoint
2568 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2570 else if (GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2572 /* This can indicate either a hardware breakpoint or
2573 hardware watchpoint. Check debug registers. */
2574 if (!check_stopped_by_watchpoint (lp
))
2575 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2577 else if (siginfo
.si_code
== TRAP_TRACE
)
2579 linux_nat_debug_printf ("%s stopped by trace",
2580 lp
->ptid
.to_string ().c_str ());
2582 /* We may have single stepped an instruction that
2583 triggered a watchpoint. In that case, on some
2584 architectures (such as x86), instead of TRAP_HWBKPT,
2585 si_code indicates TRAP_TRACE, and we need to check
2586 the debug registers separately. */
2587 check_stopped_by_watchpoint (lp
);
2592 if ((!lp
->step
|| lp
->stop_pc
== sw_bp_pc
)
2593 && software_breakpoint_inserted_here_p (regcache
->aspace (),
2596 /* The LWP was either continued, or stepped a software
2597 breakpoint instruction. */
2598 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2601 if (hardware_breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2602 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2604 if (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
)
2605 check_stopped_by_watchpoint (lp
);
2608 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
)
2610 linux_nat_debug_printf ("%s stopped by software breakpoint",
2611 lp
->ptid
.to_string ().c_str ());
2613 /* Back up the PC if necessary. */
2615 regcache_write_pc (regcache
, sw_bp_pc
);
2617 /* Update this so we record the correct stop PC below. */
2620 else if (lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2622 linux_nat_debug_printf ("%s stopped by hardware breakpoint",
2623 lp
->ptid
.to_string ().c_str ());
2625 else if (lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
)
2627 linux_nat_debug_printf ("%s stopped by hardware watchpoint",
2628 lp
->ptid
.to_string ().c_str ());
2635 /* Returns true if the LWP had stopped for a software breakpoint. */
2638 linux_nat_target::stopped_by_sw_breakpoint ()
2640 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2642 gdb_assert (lp
!= NULL
);
2644 return lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
;
2647 /* Implement the supports_stopped_by_sw_breakpoint method. */
2650 linux_nat_target::supports_stopped_by_sw_breakpoint ()
2652 return USE_SIGTRAP_SIGINFO
;
2655 /* Returns true if the LWP had stopped for a hardware
2656 breakpoint/watchpoint. */
2659 linux_nat_target::stopped_by_hw_breakpoint ()
2661 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2663 gdb_assert (lp
!= NULL
);
2665 return lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
;
2668 /* Implement the supports_stopped_by_hw_breakpoint method. */
2671 linux_nat_target::supports_stopped_by_hw_breakpoint ()
2673 return USE_SIGTRAP_SIGINFO
;
2676 /* Select one LWP out of those that have events pending. */
2679 select_event_lwp (ptid_t filter
, struct lwp_info
**orig_lp
, int *status
)
2682 int random_selector
;
2683 struct lwp_info
*event_lp
= NULL
;
2685 /* Record the wait status for the original LWP. */
2686 (*orig_lp
)->status
= *status
;
2688 /* In all-stop, give preference to the LWP that is being
2689 single-stepped. There will be at most one, and it will be the
2690 LWP that the core is most interested in. If we didn't do this,
2691 then we'd have to handle pending step SIGTRAPs somehow in case
2692 the core later continues the previously-stepped thread, as
2693 otherwise we'd report the pending SIGTRAP then, and the core, not
2694 having stepped the thread, wouldn't understand what the trap was
2695 for, and therefore would report it to the user as a random
2697 if (!target_is_non_stop_p ())
2699 event_lp
= iterate_over_lwps (filter
, select_singlestep_lwp_callback
);
2700 if (event_lp
!= NULL
)
2702 linux_nat_debug_printf ("Select single-step %s",
2703 event_lp
->ptid
.to_string ().c_str ());
2707 if (event_lp
== NULL
)
2709 /* Pick one at random, out of those which have had events. */
2711 /* First see how many events we have. */
2712 iterate_over_lwps (filter
,
2713 [&] (struct lwp_info
*info
)
2715 return count_events_callback (info
, &num_events
);
2717 gdb_assert (num_events
> 0);
2719 /* Now randomly pick a LWP out of those that have had
2721 random_selector
= (int)
2722 ((num_events
* (double) rand ()) / (RAND_MAX
+ 1.0));
2725 linux_nat_debug_printf ("Found %d events, selecting #%d",
2726 num_events
, random_selector
);
2729 = (iterate_over_lwps
2731 [&] (struct lwp_info
*info
)
2733 return select_event_lwp_callback (info
,
2738 if (event_lp
!= NULL
)
2740 /* Switch the event LWP. */
2741 *orig_lp
= event_lp
;
2742 *status
= event_lp
->status
;
2745 /* Flush the wait status for the event LWP. */
2746 (*orig_lp
)->status
= 0;
2749 /* Return non-zero if LP has been resumed. */
2752 resumed_callback (struct lwp_info
*lp
)
2757 /* Check if we should go on and pass this event to common code.
2759 If so, save the status to the lwp_info structure associated to LWPID. */
2762 linux_nat_filter_event (int lwpid
, int status
)
2764 struct lwp_info
*lp
;
2765 int event
= linux_ptrace_get_extended_event (status
);
2767 lp
= find_lwp_pid (ptid_t (lwpid
));
2769 /* Check for events reported by anything not in our LWP list. */
2772 if (WIFSTOPPED (status
))
2774 if (WSTOPSIG (status
) == SIGTRAP
&& event
== PTRACE_EVENT_EXEC
)
2776 /* A non-leader thread exec'ed after we've seen the
2777 leader zombie, and removed it from our lists (in
2778 check_zombie_leaders). The non-leader thread changes
2779 its tid to the tgid. */
2780 linux_nat_debug_printf
2781 ("Re-adding thread group leader LWP %d after exec.",
2784 lp
= add_lwp (ptid_t (lwpid
, lwpid
));
2787 add_thread (linux_target
, lp
->ptid
);
2791 /* A process we are controlling has forked and the new
2792 child's stop was reported to us by the kernel. Save
2793 its PID and go back to waiting for the fork event to
2794 be reported - the stopped process might be returned
2795 from waitpid before or after the fork event is. */
2796 linux_nat_debug_printf
2797 ("Saving LWP %d status %s in stopped_pids list",
2798 lwpid
, status_to_str (status
).c_str ());
2799 add_to_pid_list (&stopped_pids
, lwpid
, status
);
2804 /* Don't report an event for the exit of an LWP not in our
2805 list, i.e. not part of any inferior we're debugging.
2806 This can happen if we detach from a program we originally
2807 forked and then it exits. However, note that we may have
2808 earlier deleted a leader of an inferior we're debugging,
2809 in check_zombie_leaders. Re-add it back here if so. */
2810 for (inferior
*inf
: all_inferiors (linux_target
))
2812 if (inf
->pid
== lwpid
)
2814 linux_nat_debug_printf
2815 ("Re-adding thread group leader LWP %d after exit.",
2818 lp
= add_lwp (ptid_t (lwpid
, lwpid
));
2820 add_thread (linux_target
, lp
->ptid
);
2830 /* This LWP is stopped now. (And if dead, this prevents it from
2831 ever being continued.) */
2834 if (WIFSTOPPED (status
) && lp
->must_set_ptrace_flags
)
2836 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2837 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
2839 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
2840 lp
->must_set_ptrace_flags
= 0;
2843 /* Handle GNU/Linux's syscall SIGTRAPs. */
2844 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
2846 /* No longer need the sysgood bit. The ptrace event ends up
2847 recorded in lp->waitstatus if we care for it. We can carry
2848 on handling the event like a regular SIGTRAP from here
2850 status
= W_STOPCODE (SIGTRAP
);
2851 if (linux_handle_syscall_trap (lp
, 0))
2856 /* Almost all other ptrace-stops are known to be outside of system
2857 calls, with further exceptions in linux_handle_extended_wait. */
2858 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
2861 /* Handle GNU/Linux's extended waitstatus for trace events. */
2862 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
2863 && linux_is_extended_waitstatus (status
))
2865 linux_nat_debug_printf ("Handling extended status 0x%06x", status
);
2867 if (linux_handle_extended_wait (lp
, status
))
2871 /* Check if the thread has exited. */
2872 if (WIFEXITED (status
) || WIFSIGNALED (status
))
2874 if (!report_thread_events
&& !is_leader (lp
))
2876 linux_nat_debug_printf ("%s exited.",
2877 lp
->ptid
.to_string ().c_str ());
2879 /* If this was not the leader exiting, then the exit signal
2880 was not the end of the debugged application and should be
2886 /* Note that even if the leader was ptrace-stopped, it can still
2887 exit, if e.g., some other thread brings down the whole
2888 process (calls `exit'). So don't assert that the lwp is
2890 linux_nat_debug_printf ("LWP %ld exited (resumed=%d)",
2891 lp
->ptid
.lwp (), lp
->resumed
);
2893 /* Dead LWP's aren't expected to reported a pending sigstop. */
2896 /* Store the pending event in the waitstatus, because
2897 W_EXITCODE(0,0) == 0. */
2898 lp
->waitstatus
= host_status_to_waitstatus (status
);
2902 /* Make sure we don't report a SIGSTOP that we sent ourselves in
2903 an attempt to stop an LWP. */
2905 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGSTOP
)
2909 if (lp
->last_resume_kind
== resume_stop
)
2911 linux_nat_debug_printf ("resume_stop SIGSTOP caught for %s.",
2912 lp
->ptid
.to_string ().c_str ());
2916 /* This is a delayed SIGSTOP. Filter out the event. */
2918 linux_nat_debug_printf
2919 ("%s %s, 0, 0 (discard delayed SIGSTOP)",
2920 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
2921 lp
->ptid
.to_string ().c_str ());
2923 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2924 gdb_assert (lp
->resumed
);
2929 /* Make sure we don't report a SIGINT that we have already displayed
2930 for another thread. */
2931 if (lp
->ignore_sigint
2932 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGINT
)
2934 linux_nat_debug_printf ("Delayed SIGINT caught for %s.",
2935 lp
->ptid
.to_string ().c_str ());
2937 /* This is a delayed SIGINT. */
2938 lp
->ignore_sigint
= 0;
2940 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2941 linux_nat_debug_printf ("%s %s, 0, 0 (discard SIGINT)",
2942 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
2943 lp
->ptid
.to_string ().c_str ());
2944 gdb_assert (lp
->resumed
);
2946 /* Discard the event. */
2950 /* Don't report signals that GDB isn't interested in, such as
2951 signals that are neither printed nor stopped upon. Stopping all
2952 threads can be a bit time-consuming, so if we want decent
2953 performance with heavily multi-threaded programs, especially when
2954 they're using a high frequency timer, we'd better avoid it if we
2956 if (WIFSTOPPED (status
))
2958 enum gdb_signal signo
= gdb_signal_from_host (WSTOPSIG (status
));
2960 if (!target_is_non_stop_p ())
2962 /* Only do the below in all-stop, as we currently use SIGSTOP
2963 to implement target_stop (see linux_nat_stop) in
2965 if (signo
== GDB_SIGNAL_INT
&& signal_pass_state (signo
) == 0)
2967 /* If ^C/BREAK is typed at the tty/console, SIGINT gets
2968 forwarded to the entire process group, that is, all LWPs
2969 will receive it - unless they're using CLONE_THREAD to
2970 share signals. Since we only want to report it once, we
2971 mark it as ignored for all LWPs except this one. */
2972 iterate_over_lwps (ptid_t (lp
->ptid
.pid ()), set_ignore_sigint
);
2973 lp
->ignore_sigint
= 0;
2976 maybe_clear_ignore_sigint (lp
);
2979 /* When using hardware single-step, we need to report every signal.
2980 Otherwise, signals in pass_mask may be short-circuited
2981 except signals that might be caused by a breakpoint, or SIGSTOP
2982 if we sent the SIGSTOP and are waiting for it to arrive. */
2984 && WSTOPSIG (status
) && sigismember (&pass_mask
, WSTOPSIG (status
))
2985 && (WSTOPSIG (status
) != SIGSTOP
2986 || !find_thread_ptid (linux_target
, lp
->ptid
)->stop_requested
)
2987 && !linux_wstatus_maybe_breakpoint (status
))
2989 linux_resume_one_lwp (lp
, lp
->step
, signo
);
2990 linux_nat_debug_printf
2991 ("%s %s, %s (preempt 'handle')",
2992 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
2993 lp
->ptid
.to_string ().c_str (),
2994 (signo
!= GDB_SIGNAL_0
2995 ? strsignal (gdb_signal_to_host (signo
)) : "0"));
3000 /* An interesting event. */
3002 lp
->status
= status
;
3003 save_stop_reason (lp
);
3006 /* Detect zombie thread group leaders, and "exit" them. We can't reap
3007 their exits until all other threads in the group have exited. */
3010 check_zombie_leaders (void)
3012 for (inferior
*inf
: all_inferiors ())
3014 struct lwp_info
*leader_lp
;
3019 leader_lp
= find_lwp_pid (ptid_t (inf
->pid
));
3020 if (leader_lp
!= NULL
3021 /* Check if there are other threads in the group, as we may
3022 have raced with the inferior simply exiting. Note this
3023 isn't a watertight check. If the inferior is
3024 multi-threaded and is exiting, it may be we see the
3025 leader as zombie before we reap all the non-leader
3026 threads. See comments below. */
3027 && num_lwps (inf
->pid
) > 1
3028 && linux_proc_pid_is_zombie (inf
->pid
))
3030 /* A zombie leader in a multi-threaded program can mean one
3033 #1 - Only the leader exited, not the whole program, e.g.,
3034 with pthread_exit. Since we can't reap the leader's exit
3035 status until all other threads are gone and reaped too,
3036 we want to delete the zombie leader right away, as it
3037 can't be debugged, we can't read its registers, etc.
3038 This is the main reason we check for zombie leaders
3041 #2 - The whole thread-group/process exited (a group exit,
3042 via e.g. exit(3), and there is (or will be shortly) an
3043 exit reported for each thread in the process, and then
3044 finally an exit for the leader once the non-leaders are
3047 #3 - There are 3 or more threads in the group, and a
3048 thread other than the leader exec'd. See comments on
3049 exec events at the top of the file.
3051 Ideally we would never delete the leader for case #2.
3052 Instead, we want to collect the exit status of each
3053 non-leader thread, and then finally collect the exit
3054 status of the leader as normal and use its exit code as
3055 whole-process exit code. Unfortunately, there's no
3056 race-free way to distinguish cases #1 and #2. We can't
3057 assume the exit events for the non-leaders threads are
3058 already pending in the kernel, nor can we assume the
3059 non-leader threads are in zombie state already. Between
3060 the leader becoming zombie and the non-leaders exiting
3061 and becoming zombie themselves, there's a small time
3062 window, so such a check would be racy. Temporarily
3063 pausing all threads and checking to see if all threads
3064 exit or not before re-resuming them would work in the
3065 case that all threads are running right now, but it
3066 wouldn't work if some thread is currently already
3067 ptrace-stopped, e.g., due to scheduler-locking.
3069 So what we do is we delete the leader anyhow, and then
3070 later on when we see its exit status, we re-add it back.
3071 We also make sure that we only report a whole-process
3072 exit when we see the leader exiting, as opposed to when
3073 the last LWP in the LWP list exits, which can be a
3074 non-leader if we deleted the leader here. */
3075 linux_nat_debug_printf ("Thread group leader %d zombie "
3076 "(it exited, or another thread execd), "
3079 exit_lwp (leader_lp
);
3084 /* Convenience function that is called when the kernel reports an exit
3085 event. This decides whether to report the event to GDB as a
3086 process exit event, a thread exit event, or to suppress the
3090 filter_exit_event (struct lwp_info
*event_child
,
3091 struct target_waitstatus
*ourstatus
)
3093 ptid_t ptid
= event_child
->ptid
;
3095 if (!is_leader (event_child
))
3097 if (report_thread_events
)
3098 ourstatus
->set_thread_exited (0);
3100 ourstatus
->set_ignore ();
3102 exit_lwp (event_child
);
3109 linux_nat_wait_1 (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3110 target_wait_flags target_options
)
3113 enum resume_kind last_resume_kind
;
3114 struct lwp_info
*lp
;
3117 linux_nat_debug_printf ("enter");
3119 /* The first time we get here after starting a new inferior, we may
3120 not have added it to the LWP list yet - this is the earliest
3121 moment at which we know its PID. */
3122 if (ptid
.is_pid () && find_lwp_pid (ptid
) == nullptr)
3124 ptid_t
lwp_ptid (ptid
.pid (), ptid
.pid ());
3126 /* Upgrade the main thread's ptid. */
3127 thread_change_ptid (linux_target
, ptid
, lwp_ptid
);
3128 lp
= add_initial_lwp (lwp_ptid
);
3132 /* Make sure SIGCHLD is blocked until the sigsuspend below. */
3133 block_child_signals (&prev_mask
);
3135 /* First check if there is a LWP with a wait status pending. */
3136 lp
= iterate_over_lwps (ptid
, status_callback
);
3139 linux_nat_debug_printf ("Using pending wait status %s for %s.",
3140 status_to_str (lp
->status
).c_str (),
3141 lp
->ptid
.to_string ().c_str ());
3144 /* But if we don't find a pending event, we'll have to wait. Always
3145 pull all events out of the kernel. We'll randomly select an
3146 event LWP out of all that have events, to prevent starvation. */
3152 /* Always use -1 and WNOHANG, due to couple of a kernel/ptrace
3155 - If the thread group leader exits while other threads in the
3156 thread group still exist, waitpid(TGID, ...) hangs. That
3157 waitpid won't return an exit status until the other threads
3158 in the group are reaped.
3160 - When a non-leader thread execs, that thread just vanishes
3161 without reporting an exit (so we'd hang if we waited for it
3162 explicitly in that case). The exec event is reported to
3166 lwpid
= my_waitpid (-1, &status
, __WALL
| WNOHANG
);
3168 linux_nat_debug_printf ("waitpid(-1, ...) returned %d, %s",
3170 errno
? safe_strerror (errno
) : "ERRNO-OK");
3174 linux_nat_debug_printf ("waitpid %ld received %s",
3176 status_to_str (status
).c_str ());
3178 linux_nat_filter_event (lwpid
, status
);
3179 /* Retry until nothing comes out of waitpid. A single
3180 SIGCHLD can indicate more than one child stopped. */
3184 /* Now that we've pulled all events out of the kernel, resume
3185 LWPs that don't have an interesting event to report. */
3186 iterate_over_lwps (minus_one_ptid
,
3187 [] (struct lwp_info
*info
)
3189 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
3192 /* ... and find an LWP with a status to report to the core, if
3194 lp
= iterate_over_lwps (ptid
, status_callback
);
3198 /* Check for zombie thread group leaders. Those can't be reaped
3199 until all other threads in the thread group are. */
3200 check_zombie_leaders ();
3202 /* If there are no resumed children left, bail. We'd be stuck
3203 forever in the sigsuspend call below otherwise. */
3204 if (iterate_over_lwps (ptid
, resumed_callback
) == NULL
)
3206 linux_nat_debug_printf ("exit (no resumed LWP)");
3208 ourstatus
->set_no_resumed ();
3210 restore_child_signals_mask (&prev_mask
);
3211 return minus_one_ptid
;
3214 /* No interesting event to report to the core. */
3216 if (target_options
& TARGET_WNOHANG
)
3218 linux_nat_debug_printf ("exit (ignore)");
3220 ourstatus
->set_ignore ();
3221 restore_child_signals_mask (&prev_mask
);
3222 return minus_one_ptid
;
3225 /* We shouldn't end up here unless we want to try again. */
3226 gdb_assert (lp
== NULL
);
3228 /* Block until we get an event reported with SIGCHLD. */
3234 status
= lp
->status
;
3237 if (!target_is_non_stop_p ())
3239 /* Now stop all other LWP's ... */
3240 iterate_over_lwps (minus_one_ptid
, stop_callback
);
3242 /* ... and wait until all of them have reported back that
3243 they're no longer running. */
3244 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
3247 /* If we're not waiting for a specific LWP, choose an event LWP from
3248 among those that have had events. Giving equal priority to all
3249 LWPs that have had events helps prevent starvation. */
3250 if (ptid
== minus_one_ptid
|| ptid
.is_pid ())
3251 select_event_lwp (ptid
, &lp
, &status
);
3253 gdb_assert (lp
!= NULL
);
3255 /* Now that we've selected our final event LWP, un-adjust its PC if
3256 it was a software breakpoint, and we can't reliably support the
3257 "stopped by software breakpoint" stop reason. */
3258 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
3259 && !USE_SIGTRAP_SIGINFO
)
3261 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3262 struct gdbarch
*gdbarch
= regcache
->arch ();
3263 int decr_pc
= gdbarch_decr_pc_after_break (gdbarch
);
3269 pc
= regcache_read_pc (regcache
);
3270 regcache_write_pc (regcache
, pc
+ decr_pc
);
3274 /* We'll need this to determine whether to report a SIGSTOP as
3275 GDB_SIGNAL_0. Need to take a copy because resume_clear_callback
3277 last_resume_kind
= lp
->last_resume_kind
;
3279 if (!target_is_non_stop_p ())
3281 /* In all-stop, from the core's perspective, all LWPs are now
3282 stopped until a new resume action is sent over. */
3283 iterate_over_lwps (minus_one_ptid
, resume_clear_callback
);
3287 resume_clear_callback (lp
);
3290 if (linux_target
->low_status_is_event (status
))
3292 linux_nat_debug_printf ("trap ptid is %s.",
3293 lp
->ptid
.to_string ().c_str ());
3296 if (lp
->waitstatus
.kind () != TARGET_WAITKIND_IGNORE
)
3298 *ourstatus
= lp
->waitstatus
;
3299 lp
->waitstatus
.set_ignore ();
3302 *ourstatus
= host_status_to_waitstatus (status
);
3304 linux_nat_debug_printf ("exit");
3306 restore_child_signals_mask (&prev_mask
);
3308 if (last_resume_kind
== resume_stop
3309 && ourstatus
->kind () == TARGET_WAITKIND_STOPPED
3310 && WSTOPSIG (status
) == SIGSTOP
)
3312 /* A thread that has been requested to stop by GDB with
3313 target_stop, and it stopped cleanly, so report as SIG0. The
3314 use of SIGSTOP is an implementation detail. */
3315 ourstatus
->set_stopped (GDB_SIGNAL_0
);
3318 if (ourstatus
->kind () == TARGET_WAITKIND_EXITED
3319 || ourstatus
->kind () == TARGET_WAITKIND_SIGNALLED
)
3322 lp
->core
= linux_common_core_of_thread (lp
->ptid
);
3324 if (ourstatus
->kind () == TARGET_WAITKIND_EXITED
)
3325 return filter_exit_event (lp
, ourstatus
);
3330 /* Resume LWPs that are currently stopped without any pending status
3331 to report, but are resumed from the core's perspective. */
3334 resume_stopped_resumed_lwps (struct lwp_info
*lp
, const ptid_t wait_ptid
)
3338 linux_nat_debug_printf ("NOT resuming LWP %s, not stopped",
3339 lp
->ptid
.to_string ().c_str ());
3341 else if (!lp
->resumed
)
3343 linux_nat_debug_printf ("NOT resuming LWP %s, not resumed",
3344 lp
->ptid
.to_string ().c_str ());
3346 else if (lwp_status_pending_p (lp
))
3348 linux_nat_debug_printf ("NOT resuming LWP %s, has pending status",
3349 lp
->ptid
.to_string ().c_str ());
3353 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3354 struct gdbarch
*gdbarch
= regcache
->arch ();
3358 CORE_ADDR pc
= regcache_read_pc (regcache
);
3359 int leave_stopped
= 0;
3361 /* Don't bother if there's a breakpoint at PC that we'd hit
3362 immediately, and we're not waiting for this LWP. */
3363 if (!lp
->ptid
.matches (wait_ptid
))
3365 if (breakpoint_inserted_here_p (regcache
->aspace (), pc
))
3371 linux_nat_debug_printf
3372 ("resuming stopped-resumed LWP %s at %s: step=%d",
3373 lp
->ptid
.to_string ().c_str (), paddress (gdbarch
, pc
),
3376 linux_resume_one_lwp_throw (lp
, lp
->step
, GDB_SIGNAL_0
);
3379 catch (const gdb_exception_error
&ex
)
3381 if (!check_ptrace_stopped_lwp_gone (lp
))
3390 linux_nat_target::wait (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3391 target_wait_flags target_options
)
3395 linux_nat_debug_printf ("[%s], [%s]", ptid
.to_string ().c_str (),
3396 target_options_to_string (target_options
).c_str ());
3398 /* Flush the async file first. */
3399 if (target_is_async_p ())
3400 async_file_flush ();
3402 /* Resume LWPs that are currently stopped without any pending status
3403 to report, but are resumed from the core's perspective. LWPs get
3404 in this state if we find them stopping at a time we're not
3405 interested in reporting the event (target_wait on a
3406 specific_process, for example, see linux_nat_wait_1), and
3407 meanwhile the event became uninteresting. Don't bother resuming
3408 LWPs we're not going to wait for if they'd stop immediately. */
3409 if (target_is_non_stop_p ())
3410 iterate_over_lwps (minus_one_ptid
,
3411 [=] (struct lwp_info
*info
)
3413 return resume_stopped_resumed_lwps (info
, ptid
);
3416 event_ptid
= linux_nat_wait_1 (ptid
, ourstatus
, target_options
);
3418 /* If we requested any event, and something came out, assume there
3419 may be more. If we requested a specific lwp or process, also
3420 assume there may be more. */
3421 if (target_is_async_p ()
3422 && ((ourstatus
->kind () != TARGET_WAITKIND_IGNORE
3423 && ourstatus
->kind () != TARGET_WAITKIND_NO_RESUMED
)
3424 || ptid
!= minus_one_ptid
))
3433 kill_one_lwp (pid_t pid
)
3435 /* PTRACE_KILL may resume the inferior. Send SIGKILL first. */
3438 kill_lwp (pid
, SIGKILL
);
3440 if (debug_linux_nat
)
3442 int save_errno
= errno
;
3444 linux_nat_debug_printf
3445 ("kill (SIGKILL) %ld, 0, 0 (%s)", (long) pid
,
3446 save_errno
!= 0 ? safe_strerror (save_errno
) : "OK");
3449 /* Some kernels ignore even SIGKILL for processes under ptrace. */
3452 ptrace (PTRACE_KILL
, pid
, 0, 0);
3453 if (debug_linux_nat
)
3455 int save_errno
= errno
;
3457 linux_nat_debug_printf
3458 ("PTRACE_KILL %ld, 0, 0 (%s)", (long) pid
,
3459 save_errno
? safe_strerror (save_errno
) : "OK");
3463 /* Wait for an LWP to die. */
3466 kill_wait_one_lwp (pid_t pid
)
3470 /* We must make sure that there are no pending events (delayed
3471 SIGSTOPs, pending SIGTRAPs, etc.) to make sure the current
3472 program doesn't interfere with any following debugging session. */
3476 res
= my_waitpid (pid
, NULL
, __WALL
);
3477 if (res
!= (pid_t
) -1)
3479 linux_nat_debug_printf ("wait %ld received unknown.", (long) pid
);
3481 /* The Linux kernel sometimes fails to kill a thread
3482 completely after PTRACE_KILL; that goes from the stop
3483 point in do_fork out to the one in get_signal_to_deliver
3484 and waits again. So kill it again. */
3490 gdb_assert (res
== -1 && errno
== ECHILD
);
3493 /* Callback for iterate_over_lwps. */
3496 kill_callback (struct lwp_info
*lp
)
3498 kill_one_lwp (lp
->ptid
.lwp ());
3502 /* Callback for iterate_over_lwps. */
3505 kill_wait_callback (struct lwp_info
*lp
)
3507 kill_wait_one_lwp (lp
->ptid
.lwp ());
3511 /* Kill the fork children of any threads of inferior INF that are
3512 stopped at a fork event. */
3515 kill_unfollowed_fork_children (struct inferior
*inf
)
3517 for (thread_info
*thread
: inf
->non_exited_threads ())
3519 struct target_waitstatus
*ws
= &thread
->pending_follow
;
3521 if (ws
->kind () == TARGET_WAITKIND_FORKED
3522 || ws
->kind () == TARGET_WAITKIND_VFORKED
)
3524 ptid_t child_ptid
= ws
->child_ptid ();
3525 int child_pid
= child_ptid
.pid ();
3526 int child_lwp
= child_ptid
.lwp ();
3528 kill_one_lwp (child_lwp
);
3529 kill_wait_one_lwp (child_lwp
);
3531 /* Let the arch-specific native code know this process is
3533 linux_target
->low_forget_process (child_pid
);
3539 linux_nat_target::kill ()
3541 /* If we're stopped while forking and we haven't followed yet,
3542 kill the other task. We need to do this first because the
3543 parent will be sleeping if this is a vfork. */
3544 kill_unfollowed_fork_children (current_inferior ());
3546 if (forks_exist_p ())
3547 linux_fork_killall ();
3550 ptid_t ptid
= ptid_t (inferior_ptid
.pid ());
3552 /* Stop all threads before killing them, since ptrace requires
3553 that the thread is stopped to successfully PTRACE_KILL. */
3554 iterate_over_lwps (ptid
, stop_callback
);
3555 /* ... and wait until all of them have reported back that
3556 they're no longer running. */
3557 iterate_over_lwps (ptid
, stop_wait_callback
);
3559 /* Kill all LWP's ... */
3560 iterate_over_lwps (ptid
, kill_callback
);
3562 /* ... and wait until we've flushed all events. */
3563 iterate_over_lwps (ptid
, kill_wait_callback
);
3566 target_mourn_inferior (inferior_ptid
);
3570 linux_nat_target::mourn_inferior ()
3572 int pid
= inferior_ptid
.pid ();
3574 purge_lwp_list (pid
);
3576 close_proc_mem_file (pid
);
3578 if (! forks_exist_p ())
3579 /* Normal case, no other forks available. */
3580 inf_ptrace_target::mourn_inferior ();
3582 /* Multi-fork case. The current inferior_ptid has exited, but
3583 there are other viable forks to debug. Delete the exiting
3584 one and context-switch to the first available. */
3585 linux_fork_mourn_inferior ();
3587 /* Let the arch-specific native code know this process is gone. */
3588 linux_target
->low_forget_process (pid
);
3591 /* Convert a native/host siginfo object, into/from the siginfo in the
3592 layout of the inferiors' architecture. */
3595 siginfo_fixup (siginfo_t
*siginfo
, gdb_byte
*inf_siginfo
, int direction
)
3597 /* If the low target didn't do anything, then just do a straight
3599 if (!linux_target
->low_siginfo_fixup (siginfo
, inf_siginfo
, direction
))
3602 memcpy (siginfo
, inf_siginfo
, sizeof (siginfo_t
));
3604 memcpy (inf_siginfo
, siginfo
, sizeof (siginfo_t
));
3608 static enum target_xfer_status
3609 linux_xfer_siginfo (enum target_object object
,
3610 const char *annex
, gdb_byte
*readbuf
,
3611 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3612 ULONGEST
*xfered_len
)
3616 gdb_byte inf_siginfo
[sizeof (siginfo_t
)];
3618 gdb_assert (object
== TARGET_OBJECT_SIGNAL_INFO
);
3619 gdb_assert (readbuf
|| writebuf
);
3621 pid
= inferior_ptid
.lwp ();
3623 pid
= inferior_ptid
.pid ();
3625 if (offset
> sizeof (siginfo
))
3626 return TARGET_XFER_E_IO
;
3629 ptrace (PTRACE_GETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, &siginfo
);
3631 return TARGET_XFER_E_IO
;
3633 /* When GDB is built as a 64-bit application, ptrace writes into
3634 SIGINFO an object with 64-bit layout. Since debugging a 32-bit
3635 inferior with a 64-bit GDB should look the same as debugging it
3636 with a 32-bit GDB, we need to convert it. GDB core always sees
3637 the converted layout, so any read/write will have to be done
3639 siginfo_fixup (&siginfo
, inf_siginfo
, 0);
3641 if (offset
+ len
> sizeof (siginfo
))
3642 len
= sizeof (siginfo
) - offset
;
3644 if (readbuf
!= NULL
)
3645 memcpy (readbuf
, inf_siginfo
+ offset
, len
);
3648 memcpy (inf_siginfo
+ offset
, writebuf
, len
);
3650 /* Convert back to ptrace layout before flushing it out. */
3651 siginfo_fixup (&siginfo
, inf_siginfo
, 1);
3654 ptrace (PTRACE_SETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, &siginfo
);
3656 return TARGET_XFER_E_IO
;
3660 return TARGET_XFER_OK
;
3663 static enum target_xfer_status
3664 linux_nat_xfer_osdata (enum target_object object
,
3665 const char *annex
, gdb_byte
*readbuf
,
3666 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3667 ULONGEST
*xfered_len
);
3669 static enum target_xfer_status
3670 linux_proc_xfer_memory_partial (gdb_byte
*readbuf
, const gdb_byte
*writebuf
,
3671 ULONGEST offset
, LONGEST len
, ULONGEST
*xfered_len
);
3673 enum target_xfer_status
3674 linux_nat_target::xfer_partial (enum target_object object
,
3675 const char *annex
, gdb_byte
*readbuf
,
3676 const gdb_byte
*writebuf
,
3677 ULONGEST offset
, ULONGEST len
, ULONGEST
*xfered_len
)
3679 if (object
== TARGET_OBJECT_SIGNAL_INFO
)
3680 return linux_xfer_siginfo (object
, annex
, readbuf
, writebuf
,
3681 offset
, len
, xfered_len
);
3683 /* The target is connected but no live inferior is selected. Pass
3684 this request down to a lower stratum (e.g., the executable
3686 if (object
== TARGET_OBJECT_MEMORY
&& inferior_ptid
== null_ptid
)
3687 return TARGET_XFER_EOF
;
3689 if (object
== TARGET_OBJECT_AUXV
)
3690 return memory_xfer_auxv (this, object
, annex
, readbuf
, writebuf
,
3691 offset
, len
, xfered_len
);
3693 if (object
== TARGET_OBJECT_OSDATA
)
3694 return linux_nat_xfer_osdata (object
, annex
, readbuf
, writebuf
,
3695 offset
, len
, xfered_len
);
3697 if (object
== TARGET_OBJECT_MEMORY
)
3699 /* GDB calculates all addresses in the largest possible address
3700 width. The address width must be masked before its final use
3701 by linux_proc_xfer_partial.
3703 Compare ADDR_BIT first to avoid a compiler warning on shift overflow. */
3704 int addr_bit
= gdbarch_addr_bit (target_gdbarch ());
3706 if (addr_bit
< (sizeof (ULONGEST
) * HOST_CHAR_BIT
))
3707 offset
&= ((ULONGEST
) 1 << addr_bit
) - 1;
3709 return linux_proc_xfer_memory_partial (readbuf
, writebuf
,
3710 offset
, len
, xfered_len
);
3713 return inf_ptrace_target::xfer_partial (object
, annex
, readbuf
, writebuf
,
3714 offset
, len
, xfered_len
);
3718 linux_nat_target::thread_alive (ptid_t ptid
)
3720 /* As long as a PTID is in lwp list, consider it alive. */
3721 return find_lwp_pid (ptid
) != NULL
;
3724 /* Implement the to_update_thread_list target method for this
3728 linux_nat_target::update_thread_list ()
3730 /* We add/delete threads from the list as clone/exit events are
3731 processed, so just try deleting exited threads still in the
3733 delete_exited_threads ();
3735 /* Update the processor core that each lwp/thread was last seen
3737 for (lwp_info
*lwp
: all_lwps ())
3739 /* Avoid accessing /proc if the thread hasn't run since we last
3740 time we fetched the thread's core. Accessing /proc becomes
3741 noticeably expensive when we have thousands of LWPs. */
3742 if (lwp
->core
== -1)
3743 lwp
->core
= linux_common_core_of_thread (lwp
->ptid
);
3748 linux_nat_target::pid_to_str (ptid_t ptid
)
3751 && (ptid
.pid () != ptid
.lwp ()
3752 || num_lwps (ptid
.pid ()) > 1))
3753 return string_printf ("LWP %ld", ptid
.lwp ());
3755 return normal_pid_to_str (ptid
);
3759 linux_nat_target::thread_name (struct thread_info
*thr
)
3761 return linux_proc_tid_get_name (thr
->ptid
);
3764 /* Accepts an integer PID; Returns a string representing a file that
3765 can be opened to get the symbols for the child process. */
3768 linux_nat_target::pid_to_exec_file (int pid
)
3770 return linux_proc_pid_to_exec_file (pid
);
3773 /* Object representing an /proc/PID/mem open file. We keep one such
3774 file open per inferior.
3776 It might be tempting to think about only ever opening one file at
3777 most for all inferiors, closing/reopening the file as we access
3778 memory of different inferiors, to minimize number of file
3779 descriptors open, which can otherwise run into resource limits.
3780 However, that does not work correctly -- if the inferior execs and
3781 we haven't processed the exec event yet, and, we opened a
3782 /proc/PID/mem file, we will get a mem file accessing the post-exec
3783 address space, thinking we're opening it for the pre-exec address
3784 space. That is dangerous as we can poke memory (e.g. clearing
3785 breakpoints) in the post-exec memory by mistake, corrupting the
3786 inferior. For that reason, we open the mem file as early as
3787 possible, right after spawning, forking or attaching to the
3788 inferior, when the inferior is stopped and thus before it has a
3791 Note that after opening the file, even if the thread we opened it
3792 for subsequently exits, the open file is still usable for accessing
3793 memory. It's only when the whole process exits or execs that the
3794 file becomes invalid, at which point reads/writes return EOF. */
3799 proc_mem_file (ptid_t ptid
, int fd
)
3800 : m_ptid (ptid
), m_fd (fd
)
3802 gdb_assert (m_fd
!= -1);
3807 linux_nat_debug_printf ("closing fd %d for /proc/%d/task/%ld/mem",
3808 m_fd
, m_ptid
.pid (), m_ptid
.lwp ());
3812 DISABLE_COPY_AND_ASSIGN (proc_mem_file
);
3820 /* The LWP this file was opened for. Just for debugging
3824 /* The file descriptor. */
3828 /* The map between an inferior process id, and the open /proc/PID/mem
3829 file. This is stored in a map instead of in a per-inferior
3830 structure because we need to be able to access memory of processes
3831 which don't have a corresponding struct inferior object. E.g.,
3832 with "detach-on-fork on" (the default), and "follow-fork parent"
3833 (also default), we don't create an inferior for the fork child, but
3834 we still need to remove breakpoints from the fork child's
3836 static std::unordered_map
<int, proc_mem_file
> proc_mem_file_map
;
3838 /* Close the /proc/PID/mem file for PID. */
3841 close_proc_mem_file (pid_t pid
)
3843 proc_mem_file_map
.erase (pid
);
3846 /* Open the /proc/PID/mem file for the process (thread group) of PTID.
3847 We actually open /proc/PID/task/LWP/mem, as that's the LWP we know
3848 exists and is stopped right now. We prefer the
3849 /proc/PID/task/LWP/mem form over /proc/LWP/mem to avoid tid-reuse
3850 races, just in case this is ever called on an already-waited
3854 open_proc_mem_file (ptid_t ptid
)
3856 auto iter
= proc_mem_file_map
.find (ptid
.pid ());
3857 gdb_assert (iter
== proc_mem_file_map
.end ());
3860 xsnprintf (filename
, sizeof filename
,
3861 "/proc/%d/task/%ld/mem", ptid
.pid (), ptid
.lwp ());
3863 int fd
= gdb_open_cloexec (filename
, O_RDWR
| O_LARGEFILE
, 0).release ();
3867 warning (_("opening /proc/PID/mem file for lwp %d.%ld failed: %s (%d)"),
3868 ptid
.pid (), ptid
.lwp (),
3869 safe_strerror (errno
), errno
);
3873 proc_mem_file_map
.emplace (std::piecewise_construct
,
3874 std::forward_as_tuple (ptid
.pid ()),
3875 std::forward_as_tuple (ptid
, fd
));
3877 linux_nat_debug_printf ("opened fd %d for lwp %d.%ld",
3878 fd
, ptid
.pid (), ptid
.lwp ());
3881 /* Implement the to_xfer_partial target method using /proc/PID/mem.
3882 Because we can use a single read/write call, this can be much more
3883 efficient than banging away at PTRACE_PEEKTEXT. Also, unlike
3884 PTRACE_PEEKTEXT/PTRACE_POKETEXT, this works with running
3887 static enum target_xfer_status
3888 linux_proc_xfer_memory_partial (gdb_byte
*readbuf
, const gdb_byte
*writebuf
,
3889 ULONGEST offset
, LONGEST len
,
3890 ULONGEST
*xfered_len
)
3894 auto iter
= proc_mem_file_map
.find (inferior_ptid
.pid ());
3895 if (iter
== proc_mem_file_map
.end ())
3896 return TARGET_XFER_EOF
;
3898 int fd
= iter
->second
.fd ();
3900 gdb_assert (fd
!= -1);
3902 /* Use pread64/pwrite64 if available, since they save a syscall and can
3903 handle 64-bit offsets even on 32-bit platforms (for instance, SPARC
3904 debugging a SPARC64 application). */
3906 ret
= (readbuf
? pread64 (fd
, readbuf
, len
, offset
)
3907 : pwrite64 (fd
, writebuf
, len
, offset
));
3909 ret
= lseek (fd
, offset
, SEEK_SET
);
3911 ret
= (readbuf
? read (fd
, readbuf
, len
)
3912 : write (fd
, writebuf
, len
));
3917 linux_nat_debug_printf ("accessing fd %d for pid %d failed: %s (%d)",
3918 fd
, inferior_ptid
.pid (),
3919 safe_strerror (errno
), errno
);
3920 return TARGET_XFER_E_IO
;
3924 /* EOF means the address space is gone, the whole process exited
3926 linux_nat_debug_printf ("accessing fd %d for pid %d got EOF",
3927 fd
, inferior_ptid
.pid ());
3928 return TARGET_XFER_EOF
;
3933 return TARGET_XFER_OK
;
3937 /* Parse LINE as a signal set and add its set bits to SIGS. */
3940 add_line_to_sigset (const char *line
, sigset_t
*sigs
)
3942 int len
= strlen (line
) - 1;
3946 if (line
[len
] != '\n')
3947 error (_("Could not parse signal set: %s"), line
);
3955 if (*p
>= '0' && *p
<= '9')
3957 else if (*p
>= 'a' && *p
<= 'f')
3958 digit
= *p
- 'a' + 10;
3960 error (_("Could not parse signal set: %s"), line
);
3965 sigaddset (sigs
, signum
+ 1);
3967 sigaddset (sigs
, signum
+ 2);
3969 sigaddset (sigs
, signum
+ 3);
3971 sigaddset (sigs
, signum
+ 4);
3977 /* Find process PID's pending signals from /proc/pid/status and set
3981 linux_proc_pending_signals (int pid
, sigset_t
*pending
,
3982 sigset_t
*blocked
, sigset_t
*ignored
)
3984 char buffer
[PATH_MAX
], fname
[PATH_MAX
];
3986 sigemptyset (pending
);
3987 sigemptyset (blocked
);
3988 sigemptyset (ignored
);
3989 xsnprintf (fname
, sizeof fname
, "/proc/%d/status", pid
);
3990 gdb_file_up procfile
= gdb_fopen_cloexec (fname
, "r");
3991 if (procfile
== NULL
)
3992 error (_("Could not open %s"), fname
);
3994 while (fgets (buffer
, PATH_MAX
, procfile
.get ()) != NULL
)
3996 /* Normal queued signals are on the SigPnd line in the status
3997 file. However, 2.6 kernels also have a "shared" pending
3998 queue for delivering signals to a thread group, so check for
4001 Unfortunately some Red Hat kernels include the shared pending
4002 queue but not the ShdPnd status field. */
4004 if (startswith (buffer
, "SigPnd:\t"))
4005 add_line_to_sigset (buffer
+ 8, pending
);
4006 else if (startswith (buffer
, "ShdPnd:\t"))
4007 add_line_to_sigset (buffer
+ 8, pending
);
4008 else if (startswith (buffer
, "SigBlk:\t"))
4009 add_line_to_sigset (buffer
+ 8, blocked
);
4010 else if (startswith (buffer
, "SigIgn:\t"))
4011 add_line_to_sigset (buffer
+ 8, ignored
);
4015 static enum target_xfer_status
4016 linux_nat_xfer_osdata (enum target_object object
,
4017 const char *annex
, gdb_byte
*readbuf
,
4018 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
4019 ULONGEST
*xfered_len
)
4021 gdb_assert (object
== TARGET_OBJECT_OSDATA
);
4023 *xfered_len
= linux_common_xfer_osdata (annex
, readbuf
, offset
, len
);
4024 if (*xfered_len
== 0)
4025 return TARGET_XFER_EOF
;
4027 return TARGET_XFER_OK
;
4030 std::vector
<static_tracepoint_marker
>
4031 linux_nat_target::static_tracepoint_markers_by_strid (const char *strid
)
4033 char s
[IPA_CMD_BUF_SIZE
];
4034 int pid
= inferior_ptid
.pid ();
4035 std::vector
<static_tracepoint_marker
> markers
;
4037 ptid_t ptid
= ptid_t (pid
, 0);
4038 static_tracepoint_marker marker
;
4043 memcpy (s
, "qTfSTM", sizeof ("qTfSTM"));
4044 s
[sizeof ("qTfSTM")] = 0;
4046 agent_run_command (pid
, s
, strlen (s
) + 1);
4049 SCOPE_EXIT
{ target_continue_no_signal (ptid
); };
4055 parse_static_tracepoint_marker_definition (p
, &p
, &marker
);
4057 if (strid
== NULL
|| marker
.str_id
== strid
)
4058 markers
.push_back (std::move (marker
));
4060 while (*p
++ == ','); /* comma-separated list */
4062 memcpy (s
, "qTsSTM", sizeof ("qTsSTM"));
4063 s
[sizeof ("qTsSTM")] = 0;
4064 agent_run_command (pid
, s
, strlen (s
) + 1);
4071 /* target_can_async_p implementation. */
4074 linux_nat_target::can_async_p ()
4076 /* This flag should be checked in the common target.c code. */
4077 gdb_assert (target_async_permitted
);
4079 /* Otherwise, this targets is always able to support async mode. */
4084 linux_nat_target::supports_non_stop ()
4089 /* to_always_non_stop_p implementation. */
4092 linux_nat_target::always_non_stop_p ()
4098 linux_nat_target::supports_multi_process ()
4104 linux_nat_target::supports_disable_randomization ()
4109 /* SIGCHLD handler that serves two purposes: In non-stop/async mode,
4110 so we notice when any child changes state, and notify the
4111 event-loop; it allows us to use sigsuspend in linux_nat_wait_1
4112 above to wait for the arrival of a SIGCHLD. */
4115 sigchld_handler (int signo
)
4117 int old_errno
= errno
;
4119 if (debug_linux_nat
)
4120 gdb_stdlog
->write_async_safe ("sigchld\n", sizeof ("sigchld\n") - 1);
4122 if (signo
== SIGCHLD
)
4124 /* Let the event loop know that there are events to handle. */
4125 linux_nat_target::async_file_mark_if_open ();
4131 /* Callback registered with the target events file descriptor. */
4134 handle_target_event (int error
, gdb_client_data client_data
)
4136 inferior_event_handler (INF_REG_EVENT
);
4139 /* target_async implementation. */
4142 linux_nat_target::async (int enable
)
4144 if ((enable
!= 0) == is_async_p ())
4147 /* Block child signals while we create/destroy the pipe, as their
4148 handler writes to it. */
4149 gdb::block_signals blocker
;
4153 if (!async_file_open ())
4154 internal_error (__FILE__
, __LINE__
, "creating event pipe failed.");
4156 add_file_handler (async_wait_fd (), handle_target_event
, NULL
,
4159 /* There may be pending events to handle. Tell the event loop
4165 delete_file_handler (async_wait_fd ());
4166 async_file_close ();
4170 /* Stop an LWP, and push a GDB_SIGNAL_0 stop status if no other
4174 linux_nat_stop_lwp (struct lwp_info
*lwp
)
4178 linux_nat_debug_printf ("running -> suspending %s",
4179 lwp
->ptid
.to_string ().c_str ());
4182 if (lwp
->last_resume_kind
== resume_stop
)
4184 linux_nat_debug_printf ("already stopping LWP %ld at GDB's request",
4189 stop_callback (lwp
);
4190 lwp
->last_resume_kind
= resume_stop
;
4194 /* Already known to be stopped; do nothing. */
4196 if (debug_linux_nat
)
4198 if (find_thread_ptid (linux_target
, lwp
->ptid
)->stop_requested
)
4199 linux_nat_debug_printf ("already stopped/stop_requested %s",
4200 lwp
->ptid
.to_string ().c_str ());
4202 linux_nat_debug_printf ("already stopped/no stop_requested yet %s",
4203 lwp
->ptid
.to_string ().c_str ());
4210 linux_nat_target::stop (ptid_t ptid
)
4212 LINUX_NAT_SCOPED_DEBUG_ENTER_EXIT
;
4213 iterate_over_lwps (ptid
, linux_nat_stop_lwp
);
4216 /* When requests are passed down from the linux-nat layer to the
4217 single threaded inf-ptrace layer, ptids of (lwpid,0,0) form are
4218 used. The address space pointer is stored in the inferior object,
4219 but the common code that is passed such ptid can't tell whether
4220 lwpid is a "main" process id or not (it assumes so). We reverse
4221 look up the "main" process id from the lwp here. */
4223 struct address_space
*
4224 linux_nat_target::thread_address_space (ptid_t ptid
)
4226 struct lwp_info
*lwp
;
4227 struct inferior
*inf
;
4230 if (ptid
.lwp () == 0)
4232 /* An (lwpid,0,0) ptid. Look up the lwp object to get at the
4234 lwp
= find_lwp_pid (ptid
);
4235 pid
= lwp
->ptid
.pid ();
4239 /* A (pid,lwpid,0) ptid. */
4243 inf
= find_inferior_pid (this, pid
);
4244 gdb_assert (inf
!= NULL
);
4248 /* Return the cached value of the processor core for thread PTID. */
4251 linux_nat_target::core_of_thread (ptid_t ptid
)
4253 struct lwp_info
*info
= find_lwp_pid (ptid
);
4260 /* Implementation of to_filesystem_is_local. */
4263 linux_nat_target::filesystem_is_local ()
4265 struct inferior
*inf
= current_inferior ();
4267 if (inf
->fake_pid_p
|| inf
->pid
== 0)
4270 return linux_ns_same (inf
->pid
, LINUX_NS_MNT
);
4273 /* Convert the INF argument passed to a to_fileio_* method
4274 to a process ID suitable for passing to its corresponding
4275 linux_mntns_* function. If INF is non-NULL then the
4276 caller is requesting the filesystem seen by INF. If INF
4277 is NULL then the caller is requesting the filesystem seen
4278 by the GDB. We fall back to GDB's filesystem in the case
4279 that INF is non-NULL but its PID is unknown. */
4282 linux_nat_fileio_pid_of (struct inferior
*inf
)
4284 if (inf
== NULL
|| inf
->fake_pid_p
|| inf
->pid
== 0)
4290 /* Implementation of to_fileio_open. */
4293 linux_nat_target::fileio_open (struct inferior
*inf
, const char *filename
,
4294 int flags
, int mode
, int warn_if_slow
,
4301 if (fileio_to_host_openflags (flags
, &nat_flags
) == -1
4302 || fileio_to_host_mode (mode
, &nat_mode
) == -1)
4304 *target_errno
= FILEIO_EINVAL
;
4308 fd
= linux_mntns_open_cloexec (linux_nat_fileio_pid_of (inf
),
4309 filename
, nat_flags
, nat_mode
);
4311 *target_errno
= host_to_fileio_error (errno
);
4316 /* Implementation of to_fileio_readlink. */
4318 gdb::optional
<std::string
>
4319 linux_nat_target::fileio_readlink (struct inferior
*inf
, const char *filename
,
4325 len
= linux_mntns_readlink (linux_nat_fileio_pid_of (inf
),
4326 filename
, buf
, sizeof (buf
));
4329 *target_errno
= host_to_fileio_error (errno
);
4333 return std::string (buf
, len
);
4336 /* Implementation of to_fileio_unlink. */
4339 linux_nat_target::fileio_unlink (struct inferior
*inf
, const char *filename
,
4344 ret
= linux_mntns_unlink (linux_nat_fileio_pid_of (inf
),
4347 *target_errno
= host_to_fileio_error (errno
);
4352 /* Implementation of the to_thread_events method. */
4355 linux_nat_target::thread_events (int enable
)
4357 report_thread_events
= enable
;
4360 linux_nat_target::linux_nat_target ()
4362 /* We don't change the stratum; this target will sit at
4363 process_stratum and thread_db will set at thread_stratum. This
4364 is a little strange, since this is a multi-threaded-capable
4365 target, but we want to be on the stack below thread_db, and we
4366 also want to be used for single-threaded processes. */
4369 /* See linux-nat.h. */
4372 linux_nat_get_siginfo (ptid_t ptid
, siginfo_t
*siginfo
)
4381 ptrace (PTRACE_GETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, siginfo
);
4384 memset (siginfo
, 0, sizeof (*siginfo
));
4390 /* See nat/linux-nat.h. */
4393 current_lwp_ptid (void)
4395 gdb_assert (inferior_ptid
.lwp_p ());
4396 return inferior_ptid
;
4399 void _initialize_linux_nat ();
4401 _initialize_linux_nat ()
4403 add_setshow_boolean_cmd ("linux-nat", class_maintenance
,
4404 &debug_linux_nat
, _("\
4405 Set debugging of GNU/Linux native target."), _(" \
4406 Show debugging of GNU/Linux native target."), _(" \
4407 When on, print debug messages relating to the GNU/Linux native target."),
4409 show_debug_linux_nat
,
4410 &setdebuglist
, &showdebuglist
);
4412 add_setshow_boolean_cmd ("linux-namespaces", class_maintenance
,
4413 &debug_linux_namespaces
, _("\
4414 Set debugging of GNU/Linux namespaces module."), _("\
4415 Show debugging of GNU/Linux namespaces module."), _("\
4416 Enables printf debugging output."),
4419 &setdebuglist
, &showdebuglist
);
4421 /* Install a SIGCHLD handler. */
4422 sigchld_action
.sa_handler
= sigchld_handler
;
4423 sigemptyset (&sigchld_action
.sa_mask
);
4424 sigchld_action
.sa_flags
= SA_RESTART
;
4426 /* Make it the default. */
4427 sigaction (SIGCHLD
, &sigchld_action
, NULL
);
4429 /* Make sure we don't block SIGCHLD during a sigsuspend. */
4430 gdb_sigmask (SIG_SETMASK
, NULL
, &suspend_mask
);
4431 sigdelset (&suspend_mask
, SIGCHLD
);
4433 sigemptyset (&blocked_mask
);
4435 lwp_lwpid_htab_create ();
4439 /* FIXME: kettenis/2000-08-26: The stuff on this page is specific to
4440 the GNU/Linux Threads library and therefore doesn't really belong
4443 /* NPTL reserves the first two RT signals, but does not provide any
4444 way for the debugger to query the signal numbers - fortunately
4445 they don't change. */
4446 static int lin_thread_signals
[] = { __SIGRTMIN
, __SIGRTMIN
+ 1 };
4448 /* See linux-nat.h. */
4451 lin_thread_get_thread_signal_num (void)
4453 return sizeof (lin_thread_signals
) / sizeof (lin_thread_signals
[0]);
4456 /* See linux-nat.h. */
4459 lin_thread_get_thread_signal (unsigned int i
)
4461 gdb_assert (i
< lin_thread_get_thread_signal_num ());
4462 return lin_thread_signals
[i
];