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 bool proc_mem_file_is_writable ();
248 static void close_proc_mem_file (pid_t pid
);
249 static void open_proc_mem_file (ptid_t ptid
);
251 /* Return TRUE if LWP is the leader thread of the process. */
254 is_leader (lwp_info
*lp
)
256 return lp
->ptid
.pid () == lp
->ptid
.lwp ();
262 /* See nat/linux-nat.h. */
265 ptid_of_lwp (struct lwp_info
*lwp
)
270 /* See nat/linux-nat.h. */
273 lwp_set_arch_private_info (struct lwp_info
*lwp
,
274 struct arch_lwp_info
*info
)
276 lwp
->arch_private
= info
;
279 /* See nat/linux-nat.h. */
281 struct arch_lwp_info
*
282 lwp_arch_private_info (struct lwp_info
*lwp
)
284 return lwp
->arch_private
;
287 /* See nat/linux-nat.h. */
290 lwp_is_stopped (struct lwp_info
*lwp
)
295 /* See nat/linux-nat.h. */
297 enum target_stop_reason
298 lwp_stop_reason (struct lwp_info
*lwp
)
300 return lwp
->stop_reason
;
303 /* See nat/linux-nat.h. */
306 lwp_is_stepping (struct lwp_info
*lwp
)
312 /* Trivial list manipulation functions to keep track of a list of
313 new stopped processes. */
315 add_to_pid_list (struct simple_pid_list
**listp
, int pid
, int status
)
317 struct simple_pid_list
*new_pid
= XNEW (struct simple_pid_list
);
320 new_pid
->status
= status
;
321 new_pid
->next
= *listp
;
326 pull_pid_from_list (struct simple_pid_list
**listp
, int pid
, int *statusp
)
328 struct simple_pid_list
**p
;
330 for (p
= listp
; *p
!= NULL
; p
= &(*p
)->next
)
331 if ((*p
)->pid
== pid
)
333 struct simple_pid_list
*next
= (*p
)->next
;
335 *statusp
= (*p
)->status
;
343 /* Return the ptrace options that we want to try to enable. */
346 linux_nat_ptrace_options (int attached
)
351 options
|= PTRACE_O_EXITKILL
;
353 options
|= (PTRACE_O_TRACESYSGOOD
354 | PTRACE_O_TRACEVFORKDONE
355 | PTRACE_O_TRACEVFORK
357 | PTRACE_O_TRACEEXEC
);
362 /* Initialize ptrace and procfs warnings and check for supported
363 ptrace features given PID.
365 ATTACHED should be nonzero iff we attached to the inferior. */
368 linux_init_ptrace_procfs (pid_t pid
, int attached
)
370 int options
= linux_nat_ptrace_options (attached
);
372 linux_enable_event_reporting (pid
, options
);
373 linux_ptrace_init_warnings ();
374 linux_proc_init_warnings ();
377 linux_nat_target::~linux_nat_target ()
381 linux_nat_target::post_attach (int pid
)
383 linux_init_ptrace_procfs (pid
, 1);
386 /* Implement the virtual inf_ptrace_target::post_startup_inferior method. */
389 linux_nat_target::post_startup_inferior (ptid_t ptid
)
391 linux_init_ptrace_procfs (ptid
.pid (), 0);
394 /* Return the number of known LWPs in the tgid given by PID. */
401 for (const lwp_info
*lp ATTRIBUTE_UNUSED
: all_lwps ())
402 if (lp
->ptid
.pid () == pid
)
408 /* Deleter for lwp_info unique_ptr specialisation. */
412 void operator() (struct lwp_info
*lwp
) const
414 delete_lwp (lwp
->ptid
);
418 /* A unique_ptr specialisation for lwp_info. */
420 typedef std::unique_ptr
<struct lwp_info
, lwp_deleter
> lwp_info_up
;
422 /* Target hook for follow_fork. */
425 linux_nat_target::follow_fork (inferior
*child_inf
, ptid_t child_ptid
,
426 target_waitkind fork_kind
, bool follow_child
,
429 inf_ptrace_target::follow_fork (child_inf
, child_ptid
, fork_kind
,
430 follow_child
, detach_fork
);
434 bool has_vforked
= fork_kind
== TARGET_WAITKIND_VFORKED
;
435 ptid_t parent_ptid
= inferior_ptid
;
436 int parent_pid
= parent_ptid
.lwp ();
437 int child_pid
= child_ptid
.lwp ();
439 /* We're already attached to the parent, by default. */
440 lwp_info
*child_lp
= add_lwp (child_ptid
);
441 child_lp
->stopped
= 1;
442 child_lp
->last_resume_kind
= resume_stop
;
444 /* Detach new forked process? */
447 int child_stop_signal
= 0;
448 bool detach_child
= true;
450 /* Move CHILD_LP into a unique_ptr and clear the source pointer
451 to prevent us doing anything stupid with it. */
452 lwp_info_up
child_lp_ptr (child_lp
);
455 linux_target
->low_prepare_to_resume (child_lp_ptr
.get ());
457 /* When debugging an inferior in an architecture that supports
458 hardware single stepping on a kernel without commit
459 6580807da14c423f0d0a708108e6df6ebc8bc83d, the vfork child
460 process starts with the TIF_SINGLESTEP/X86_EFLAGS_TF bits
461 set if the parent process had them set.
462 To work around this, single step the child process
463 once before detaching to clear the flags. */
465 /* Note that we consult the parent's architecture instead of
466 the child's because there's no inferior for the child at
468 if (!gdbarch_software_single_step_p (target_thread_architecture
473 linux_disable_event_reporting (child_pid
);
474 if (ptrace (PTRACE_SINGLESTEP
, child_pid
, 0, 0) < 0)
475 perror_with_name (_("Couldn't do single step"));
476 if (my_waitpid (child_pid
, &status
, 0) < 0)
477 perror_with_name (_("Couldn't wait vfork process"));
480 detach_child
= WIFSTOPPED (status
);
481 child_stop_signal
= WSTOPSIG (status
);
487 int signo
= child_stop_signal
;
490 && !signal_pass_state (gdb_signal_from_host (signo
)))
492 ptrace (PTRACE_DETACH
, child_pid
, 0, signo
);
494 close_proc_mem_file (child_pid
);
500 lwp_info
*parent_lp
= find_lwp_pid (parent_ptid
);
501 linux_nat_debug_printf ("waiting for VFORK_DONE on %d", parent_pid
);
502 parent_lp
->stopped
= 1;
504 /* We'll handle the VFORK_DONE event like any other
505 event, in target_wait. */
510 struct lwp_info
*child_lp
;
512 child_lp
= add_lwp (child_ptid
);
513 child_lp
->stopped
= 1;
514 child_lp
->last_resume_kind
= resume_stop
;
520 linux_nat_target::insert_fork_catchpoint (int pid
)
526 linux_nat_target::remove_fork_catchpoint (int pid
)
532 linux_nat_target::insert_vfork_catchpoint (int pid
)
538 linux_nat_target::remove_vfork_catchpoint (int pid
)
544 linux_nat_target::insert_exec_catchpoint (int pid
)
550 linux_nat_target::remove_exec_catchpoint (int pid
)
556 linux_nat_target::set_syscall_catchpoint (int pid
, bool needed
, int any_count
,
557 gdb::array_view
<const int> syscall_counts
)
559 /* On GNU/Linux, we ignore the arguments. It means that we only
560 enable the syscall catchpoints, but do not disable them.
562 Also, we do not use the `syscall_counts' information because we do not
563 filter system calls here. We let GDB do the logic for us. */
567 /* List of known LWPs, keyed by LWP PID. This speeds up the common
568 case of mapping a PID returned from the kernel to our corresponding
569 lwp_info data structure. */
570 static htab_t lwp_lwpid_htab
;
572 /* Calculate a hash from a lwp_info's LWP PID. */
575 lwp_info_hash (const void *ap
)
577 const struct lwp_info
*lp
= (struct lwp_info
*) ap
;
578 pid_t pid
= lp
->ptid
.lwp ();
580 return iterative_hash_object (pid
, 0);
583 /* Equality function for the lwp_info hash table. Compares the LWP's
587 lwp_lwpid_htab_eq (const void *a
, const void *b
)
589 const struct lwp_info
*entry
= (const struct lwp_info
*) a
;
590 const struct lwp_info
*element
= (const struct lwp_info
*) b
;
592 return entry
->ptid
.lwp () == element
->ptid
.lwp ();
595 /* Create the lwp_lwpid_htab hash table. */
598 lwp_lwpid_htab_create (void)
600 lwp_lwpid_htab
= htab_create (100, lwp_info_hash
, lwp_lwpid_htab_eq
, NULL
);
603 /* Add LP to the hash table. */
606 lwp_lwpid_htab_add_lwp (struct lwp_info
*lp
)
610 slot
= htab_find_slot (lwp_lwpid_htab
, lp
, INSERT
);
611 gdb_assert (slot
!= NULL
&& *slot
== NULL
);
615 /* Head of doubly-linked list of known LWPs. Sorted by reverse
616 creation order. This order is assumed in some cases. E.g.,
617 reaping status after killing alls lwps of a process: the leader LWP
618 must be reaped last. */
620 static intrusive_list
<lwp_info
> lwp_list
;
622 /* See linux-nat.h. */
627 return lwp_info_range (lwp_list
.begin ());
630 /* See linux-nat.h. */
635 return lwp_info_safe_range (lwp_list
.begin ());
638 /* Add LP to sorted-by-reverse-creation-order doubly-linked list. */
641 lwp_list_add (struct lwp_info
*lp
)
643 lwp_list
.push_front (*lp
);
646 /* Remove LP from sorted-by-reverse-creation-order doubly-linked
650 lwp_list_remove (struct lwp_info
*lp
)
652 /* Remove from sorted-by-creation-order list. */
653 lwp_list
.erase (lwp_list
.iterator_to (*lp
));
658 /* Signal mask for use with sigsuspend in linux_nat_wait, initialized in
659 _initialize_linux_nat. */
660 static sigset_t suspend_mask
;
662 /* Signals to block to make that sigsuspend work. */
663 static sigset_t blocked_mask
;
665 /* SIGCHLD action. */
666 static struct sigaction sigchld_action
;
668 /* Block child signals (SIGCHLD and linux threads signals), and store
669 the previous mask in PREV_MASK. */
672 block_child_signals (sigset_t
*prev_mask
)
674 /* Make sure SIGCHLD is blocked. */
675 if (!sigismember (&blocked_mask
, SIGCHLD
))
676 sigaddset (&blocked_mask
, SIGCHLD
);
678 gdb_sigmask (SIG_BLOCK
, &blocked_mask
, prev_mask
);
681 /* Restore child signals mask, previously returned by
682 block_child_signals. */
685 restore_child_signals_mask (sigset_t
*prev_mask
)
687 gdb_sigmask (SIG_SETMASK
, prev_mask
, NULL
);
690 /* Mask of signals to pass directly to the inferior. */
691 static sigset_t pass_mask
;
693 /* Update signals to pass to the inferior. */
695 linux_nat_target::pass_signals
696 (gdb::array_view
<const unsigned char> pass_signals
)
700 sigemptyset (&pass_mask
);
702 for (signo
= 1; signo
< NSIG
; signo
++)
704 int target_signo
= gdb_signal_from_host (signo
);
705 if (target_signo
< pass_signals
.size () && pass_signals
[target_signo
])
706 sigaddset (&pass_mask
, signo
);
712 /* Prototypes for local functions. */
713 static int stop_wait_callback (struct lwp_info
*lp
);
714 static int resume_stopped_resumed_lwps (struct lwp_info
*lp
, const ptid_t wait_ptid
);
715 static int check_ptrace_stopped_lwp_gone (struct lwp_info
*lp
);
719 /* Destroy and free LP. */
721 lwp_info::~lwp_info ()
723 /* Let the arch specific bits release arch_lwp_info. */
724 linux_target
->low_delete_thread (this->arch_private
);
727 /* Traversal function for purge_lwp_list. */
730 lwp_lwpid_htab_remove_pid (void **slot
, void *info
)
732 struct lwp_info
*lp
= (struct lwp_info
*) *slot
;
733 int pid
= *(int *) info
;
735 if (lp
->ptid
.pid () == pid
)
737 htab_clear_slot (lwp_lwpid_htab
, slot
);
738 lwp_list_remove (lp
);
745 /* Remove all LWPs belong to PID from the lwp list. */
748 purge_lwp_list (int pid
)
750 htab_traverse_noresize (lwp_lwpid_htab
, lwp_lwpid_htab_remove_pid
, &pid
);
753 /* Add the LWP specified by PTID to the list. PTID is the first LWP
754 in the process. Return a pointer to the structure describing the
757 This differs from add_lwp in that we don't let the arch specific
758 bits know about this new thread. Current clients of this callback
759 take the opportunity to install watchpoints in the new thread, and
760 we shouldn't do that for the first thread. If we're spawning a
761 child ("run"), the thread executes the shell wrapper first, and we
762 shouldn't touch it until it execs the program we want to debug.
763 For "attach", it'd be okay to call the callback, but it's not
764 necessary, because watchpoints can't yet have been inserted into
767 static struct lwp_info
*
768 add_initial_lwp (ptid_t ptid
)
770 gdb_assert (ptid
.lwp_p ());
772 lwp_info
*lp
= new lwp_info (ptid
);
775 /* Add to sorted-by-reverse-creation-order list. */
778 /* Add to keyed-by-pid htab. */
779 lwp_lwpid_htab_add_lwp (lp
);
784 /* Add the LWP specified by PID to the list. Return a pointer to the
785 structure describing the new LWP. The LWP should already be
788 static struct lwp_info
*
789 add_lwp (ptid_t ptid
)
793 lp
= add_initial_lwp (ptid
);
795 /* Let the arch specific bits know about this new thread. Current
796 clients of this callback take the opportunity to install
797 watchpoints in the new thread. We don't do this for the first
798 thread though. See add_initial_lwp. */
799 linux_target
->low_new_thread (lp
);
804 /* Remove the LWP specified by PID from the list. */
807 delete_lwp (ptid_t ptid
)
809 lwp_info
dummy (ptid
);
811 void **slot
= htab_find_slot (lwp_lwpid_htab
, &dummy
, NO_INSERT
);
815 lwp_info
*lp
= *(struct lwp_info
**) slot
;
816 gdb_assert (lp
!= NULL
);
818 htab_clear_slot (lwp_lwpid_htab
, slot
);
820 /* Remove from sorted-by-creation-order list. */
821 lwp_list_remove (lp
);
827 /* Return a pointer to the structure describing the LWP corresponding
828 to PID. If no corresponding LWP could be found, return NULL. */
830 static struct lwp_info
*
831 find_lwp_pid (ptid_t ptid
)
840 lwp_info
dummy (ptid_t (0, lwp
));
841 return (struct lwp_info
*) htab_find (lwp_lwpid_htab
, &dummy
);
844 /* See nat/linux-nat.h. */
847 iterate_over_lwps (ptid_t filter
,
848 gdb::function_view
<iterate_over_lwps_ftype
> callback
)
850 for (lwp_info
*lp
: all_lwps_safe ())
852 if (lp
->ptid
.matches (filter
))
854 if (callback (lp
) != 0)
862 /* Update our internal state when changing from one checkpoint to
863 another indicated by NEW_PTID. We can only switch single-threaded
864 applications, so we only create one new LWP, and the previous list
868 linux_nat_switch_fork (ptid_t new_ptid
)
872 purge_lwp_list (inferior_ptid
.pid ());
874 lp
= add_lwp (new_ptid
);
877 /* This changes the thread's ptid while preserving the gdb thread
878 num. Also changes the inferior pid, while preserving the
880 thread_change_ptid (linux_target
, inferior_ptid
, new_ptid
);
882 /* We've just told GDB core that the thread changed target id, but,
883 in fact, it really is a different thread, with different register
885 registers_changed ();
888 /* Handle the exit of a single thread LP. */
891 exit_lwp (struct lwp_info
*lp
)
893 struct thread_info
*th
= find_thread_ptid (linux_target
, lp
->ptid
);
897 if (print_thread_events
)
898 gdb_printf (_("[%s exited]\n"),
899 target_pid_to_str (lp
->ptid
).c_str ());
904 delete_lwp (lp
->ptid
);
907 /* Wait for the LWP specified by LP, which we have just attached to.
908 Returns a wait status for that LWP, to cache. */
911 linux_nat_post_attach_wait (ptid_t ptid
, int *signalled
)
913 pid_t new_pid
, pid
= ptid
.lwp ();
916 if (linux_proc_pid_is_stopped (pid
))
918 linux_nat_debug_printf ("Attaching to a stopped process");
920 /* The process is definitely stopped. It is in a job control
921 stop, unless the kernel predates the TASK_STOPPED /
922 TASK_TRACED distinction, in which case it might be in a
923 ptrace stop. Make sure it is in a ptrace stop; from there we
924 can kill it, signal it, et cetera.
926 First make sure there is a pending SIGSTOP. Since we are
927 already attached, the process can not transition from stopped
928 to running without a PTRACE_CONT; so we know this signal will
929 go into the queue. The SIGSTOP generated by PTRACE_ATTACH is
930 probably already in the queue (unless this kernel is old
931 enough to use TASK_STOPPED for ptrace stops); but since SIGSTOP
932 is not an RT signal, it can only be queued once. */
933 kill_lwp (pid
, SIGSTOP
);
935 /* Finally, resume the stopped process. This will deliver the SIGSTOP
936 (or a higher priority signal, just like normal PTRACE_ATTACH). */
937 ptrace (PTRACE_CONT
, pid
, 0, 0);
940 /* Make sure the initial process is stopped. The user-level threads
941 layer might want to poke around in the inferior, and that won't
942 work if things haven't stabilized yet. */
943 new_pid
= my_waitpid (pid
, &status
, __WALL
);
944 gdb_assert (pid
== new_pid
);
946 if (!WIFSTOPPED (status
))
948 /* The pid we tried to attach has apparently just exited. */
949 linux_nat_debug_printf ("Failed to stop %d: %s", pid
,
950 status_to_str (status
).c_str ());
954 if (WSTOPSIG (status
) != SIGSTOP
)
957 linux_nat_debug_printf ("Received %s after attaching",
958 status_to_str (status
).c_str ());
965 linux_nat_target::create_inferior (const char *exec_file
,
966 const std::string
&allargs
,
967 char **env
, int from_tty
)
969 maybe_disable_address_space_randomization restore_personality
970 (disable_randomization
);
972 /* The fork_child mechanism is synchronous and calls target_wait, so
973 we have to mask the async mode. */
975 /* Make sure we report all signals during startup. */
978 inf_ptrace_target::create_inferior (exec_file
, allargs
, env
, from_tty
);
980 open_proc_mem_file (inferior_ptid
);
983 /* Callback for linux_proc_attach_tgid_threads. Attach to PTID if not
984 already attached. Returns true if a new LWP is found, false
988 attach_proc_task_lwp_callback (ptid_t ptid
)
992 /* Ignore LWPs we're already attached to. */
993 lp
= find_lwp_pid (ptid
);
996 int lwpid
= ptid
.lwp ();
998 if (ptrace (PTRACE_ATTACH
, lwpid
, 0, 0) < 0)
1002 /* Be quiet if we simply raced with the thread exiting.
1003 EPERM is returned if the thread's task still exists, and
1004 is marked as exited or zombie, as well as other
1005 conditions, so in that case, confirm the status in
1006 /proc/PID/status. */
1008 || (err
== EPERM
&& linux_proc_pid_is_gone (lwpid
)))
1010 linux_nat_debug_printf
1011 ("Cannot attach to lwp %d: thread is gone (%d: %s)",
1012 lwpid
, err
, safe_strerror (err
));
1018 = linux_ptrace_attach_fail_reason_string (ptid
, err
);
1020 warning (_("Cannot attach to lwp %d: %s"),
1021 lwpid
, reason
.c_str ());
1026 linux_nat_debug_printf ("PTRACE_ATTACH %s, 0, 0 (OK)",
1027 ptid
.to_string ().c_str ());
1029 lp
= add_lwp (ptid
);
1031 /* The next time we wait for this LWP we'll see a SIGSTOP as
1032 PTRACE_ATTACH brings it to a halt. */
1035 /* We need to wait for a stop before being able to make the
1036 next ptrace call on this LWP. */
1037 lp
->must_set_ptrace_flags
= 1;
1039 /* So that wait collects the SIGSTOP. */
1042 /* Also add the LWP to gdb's thread list, in case a
1043 matching libthread_db is not found (or the process uses
1045 add_thread (linux_target
, lp
->ptid
);
1046 set_running (linux_target
, lp
->ptid
, true);
1047 set_executing (linux_target
, lp
->ptid
, true);
1056 linux_nat_target::attach (const char *args
, int from_tty
)
1058 struct lwp_info
*lp
;
1062 /* Make sure we report all signals during attach. */
1067 inf_ptrace_target::attach (args
, from_tty
);
1069 catch (const gdb_exception_error
&ex
)
1071 pid_t pid
= parse_pid_to_attach (args
);
1072 std::string reason
= linux_ptrace_attach_fail_reason (pid
);
1074 if (!reason
.empty ())
1075 throw_error (ex
.error
, "warning: %s\n%s", reason
.c_str (),
1078 throw_error (ex
.error
, "%s", ex
.what ());
1081 /* The ptrace base target adds the main thread with (pid,0,0)
1082 format. Decorate it with lwp info. */
1083 ptid
= ptid_t (inferior_ptid
.pid (),
1084 inferior_ptid
.pid ());
1085 thread_change_ptid (linux_target
, inferior_ptid
, ptid
);
1087 /* Add the initial process as the first LWP to the list. */
1088 lp
= add_initial_lwp (ptid
);
1090 status
= linux_nat_post_attach_wait (lp
->ptid
, &lp
->signalled
);
1091 if (!WIFSTOPPED (status
))
1093 if (WIFEXITED (status
))
1095 int exit_code
= WEXITSTATUS (status
);
1097 target_terminal::ours ();
1098 target_mourn_inferior (inferior_ptid
);
1100 error (_("Unable to attach: program exited normally."));
1102 error (_("Unable to attach: program exited with code %d."),
1105 else if (WIFSIGNALED (status
))
1107 enum gdb_signal signo
;
1109 target_terminal::ours ();
1110 target_mourn_inferior (inferior_ptid
);
1112 signo
= gdb_signal_from_host (WTERMSIG (status
));
1113 error (_("Unable to attach: program terminated with signal "
1115 gdb_signal_to_name (signo
),
1116 gdb_signal_to_string (signo
));
1119 internal_error (__FILE__
, __LINE__
,
1120 _("unexpected status %d for PID %ld"),
1121 status
, (long) ptid
.lwp ());
1126 open_proc_mem_file (lp
->ptid
);
1128 /* Save the wait status to report later. */
1130 linux_nat_debug_printf ("waitpid %ld, saving status %s",
1131 (long) lp
->ptid
.pid (),
1132 status_to_str (status
).c_str ());
1134 lp
->status
= status
;
1136 /* We must attach to every LWP. If /proc is mounted, use that to
1137 find them now. The inferior may be using raw clone instead of
1138 using pthreads. But even if it is using pthreads, thread_db
1139 walks structures in the inferior's address space to find the list
1140 of threads/LWPs, and those structures may well be corrupted.
1141 Note that once thread_db is loaded, we'll still use it to list
1142 threads and associate pthread info with each LWP. */
1143 linux_proc_attach_tgid_threads (lp
->ptid
.pid (),
1144 attach_proc_task_lwp_callback
);
1147 /* Ptrace-detach the thread with pid PID. */
1150 detach_one_pid (int pid
, int signo
)
1152 if (ptrace (PTRACE_DETACH
, pid
, 0, signo
) < 0)
1154 int save_errno
= errno
;
1156 /* We know the thread exists, so ESRCH must mean the lwp is
1157 zombie. This can happen if one of the already-detached
1158 threads exits the whole thread group. In that case we're
1159 still attached, and must reap the lwp. */
1160 if (save_errno
== ESRCH
)
1164 ret
= my_waitpid (pid
, &status
, __WALL
);
1167 warning (_("Couldn't reap LWP %d while detaching: %s"),
1168 pid
, safe_strerror (errno
));
1170 else if (!WIFEXITED (status
) && !WIFSIGNALED (status
))
1172 warning (_("Reaping LWP %d while detaching "
1173 "returned unexpected status 0x%x"),
1178 error (_("Can't detach %d: %s"),
1179 pid
, safe_strerror (save_errno
));
1182 linux_nat_debug_printf ("PTRACE_DETACH (%d, %s, 0) (OK)",
1183 pid
, strsignal (signo
));
1186 /* Get pending signal of THREAD as a host signal number, for detaching
1187 purposes. This is the signal the thread last stopped for, which we
1188 need to deliver to the thread when detaching, otherwise, it'd be
1192 get_detach_signal (struct lwp_info
*lp
)
1194 enum gdb_signal signo
= GDB_SIGNAL_0
;
1196 /* If we paused threads momentarily, we may have stored pending
1197 events in lp->status or lp->waitstatus (see stop_wait_callback),
1198 and GDB core hasn't seen any signal for those threads.
1199 Otherwise, the last signal reported to the core is found in the
1200 thread object's stop_signal.
1202 There's a corner case that isn't handled here at present. Only
1203 if the thread stopped with a TARGET_WAITKIND_STOPPED does
1204 stop_signal make sense as a real signal to pass to the inferior.
1205 Some catchpoint related events, like
1206 TARGET_WAITKIND_(V)FORK|EXEC|SYSCALL, have their stop_signal set
1207 to GDB_SIGNAL_SIGTRAP when the catchpoint triggers. But,
1208 those traps are debug API (ptrace in our case) related and
1209 induced; the inferior wouldn't see them if it wasn't being
1210 traced. Hence, we should never pass them to the inferior, even
1211 when set to pass state. Since this corner case isn't handled by
1212 infrun.c when proceeding with a signal, for consistency, neither
1213 do we handle it here (or elsewhere in the file we check for
1214 signal pass state). Normally SIGTRAP isn't set to pass state, so
1215 this is really a corner case. */
1217 if (lp
->waitstatus
.kind () != TARGET_WAITKIND_IGNORE
)
1218 signo
= GDB_SIGNAL_0
; /* a pending ptrace event, not a real signal. */
1219 else if (lp
->status
)
1220 signo
= gdb_signal_from_host (WSTOPSIG (lp
->status
));
1223 struct thread_info
*tp
= find_thread_ptid (linux_target
, lp
->ptid
);
1225 if (target_is_non_stop_p () && !tp
->executing ())
1227 if (tp
->has_pending_waitstatus ())
1229 /* If the thread has a pending event, and it was stopped with a
1230 signal, use that signal to resume it. If it has a pending
1231 event of another kind, it was not stopped with a signal, so
1232 resume it without a signal. */
1233 if (tp
->pending_waitstatus ().kind () == TARGET_WAITKIND_STOPPED
)
1234 signo
= tp
->pending_waitstatus ().sig ();
1236 signo
= GDB_SIGNAL_0
;
1239 signo
= tp
->stop_signal ();
1241 else if (!target_is_non_stop_p ())
1244 process_stratum_target
*last_target
;
1246 get_last_target_status (&last_target
, &last_ptid
, nullptr);
1248 if (last_target
== linux_target
1249 && lp
->ptid
.lwp () == last_ptid
.lwp ())
1250 signo
= tp
->stop_signal ();
1254 if (signo
== GDB_SIGNAL_0
)
1256 linux_nat_debug_printf ("lwp %s has no pending signal",
1257 lp
->ptid
.to_string ().c_str ());
1259 else if (!signal_pass_state (signo
))
1261 linux_nat_debug_printf
1262 ("lwp %s had signal %s but it is in no pass state",
1263 lp
->ptid
.to_string ().c_str (), gdb_signal_to_string (signo
));
1267 linux_nat_debug_printf ("lwp %s has pending signal %s",
1268 lp
->ptid
.to_string ().c_str (),
1269 gdb_signal_to_string (signo
));
1271 return gdb_signal_to_host (signo
);
1277 /* Detach from LP. If SIGNO_P is non-NULL, then it points to the
1278 signal number that should be passed to the LWP when detaching.
1279 Otherwise pass any pending signal the LWP may have, if any. */
1282 detach_one_lwp (struct lwp_info
*lp
, int *signo_p
)
1284 int lwpid
= lp
->ptid
.lwp ();
1287 gdb_assert (lp
->status
== 0 || WIFSTOPPED (lp
->status
));
1289 /* If the lwp/thread we are about to detach has a pending fork event,
1290 there is a process GDB is attached to that the core of GDB doesn't know
1291 about. Detach from it. */
1293 /* Check in lwp_info::status. */
1294 if (WIFSTOPPED (lp
->status
) && linux_is_extended_waitstatus (lp
->status
))
1296 int event
= linux_ptrace_get_extended_event (lp
->status
);
1298 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
)
1300 unsigned long child_pid
;
1301 int ret
= ptrace (PTRACE_GETEVENTMSG
, lp
->ptid
.lwp (), 0, &child_pid
);
1303 detach_one_pid (child_pid
, 0);
1305 perror_warning_with_name (_("Failed to detach fork child"));
1309 /* Check in lwp_info::waitstatus. */
1310 if (lp
->waitstatus
.kind () == TARGET_WAITKIND_VFORKED
1311 || lp
->waitstatus
.kind () == TARGET_WAITKIND_FORKED
)
1312 detach_one_pid (lp
->waitstatus
.child_ptid ().pid (), 0);
1315 /* Check in thread_info::pending_waitstatus. */
1316 thread_info
*tp
= find_thread_ptid (linux_target
, lp
->ptid
);
1317 if (tp
->has_pending_waitstatus ())
1319 const target_waitstatus
&ws
= tp
->pending_waitstatus ();
1321 if (ws
.kind () == TARGET_WAITKIND_VFORKED
1322 || ws
.kind () == TARGET_WAITKIND_FORKED
)
1323 detach_one_pid (ws
.child_ptid ().pid (), 0);
1326 /* Check in thread_info::pending_follow. */
1327 if (tp
->pending_follow
.kind () == TARGET_WAITKIND_VFORKED
1328 || tp
->pending_follow
.kind () == TARGET_WAITKIND_FORKED
)
1329 detach_one_pid (tp
->pending_follow
.child_ptid ().pid (), 0);
1331 if (lp
->status
!= 0)
1332 linux_nat_debug_printf ("Pending %s for %s on detach.",
1333 strsignal (WSTOPSIG (lp
->status
)),
1334 lp
->ptid
.to_string ().c_str ());
1336 /* If there is a pending SIGSTOP, get rid of it. */
1339 linux_nat_debug_printf ("Sending SIGCONT to %s",
1340 lp
->ptid
.to_string ().c_str ());
1342 kill_lwp (lwpid
, SIGCONT
);
1346 if (signo_p
== NULL
)
1348 /* Pass on any pending signal for this LWP. */
1349 signo
= get_detach_signal (lp
);
1354 /* Preparing to resume may try to write registers, and fail if the
1355 lwp is zombie. If that happens, ignore the error. We'll handle
1356 it below, when detach fails with ESRCH. */
1359 linux_target
->low_prepare_to_resume (lp
);
1361 catch (const gdb_exception_error
&ex
)
1363 if (!check_ptrace_stopped_lwp_gone (lp
))
1367 detach_one_pid (lwpid
, signo
);
1369 delete_lwp (lp
->ptid
);
1373 detach_callback (struct lwp_info
*lp
)
1375 /* We don't actually detach from the thread group leader just yet.
1376 If the thread group exits, we must reap the zombie clone lwps
1377 before we're able to reap the leader. */
1378 if (lp
->ptid
.lwp () != lp
->ptid
.pid ())
1379 detach_one_lwp (lp
, NULL
);
1384 linux_nat_target::detach (inferior
*inf
, int from_tty
)
1386 struct lwp_info
*main_lwp
;
1389 /* Don't unregister from the event loop, as there may be other
1390 inferiors running. */
1392 /* Stop all threads before detaching. ptrace requires that the
1393 thread is stopped to successfully detach. */
1394 iterate_over_lwps (ptid_t (pid
), stop_callback
);
1395 /* ... and wait until all of them have reported back that
1396 they're no longer running. */
1397 iterate_over_lwps (ptid_t (pid
), stop_wait_callback
);
1399 /* We can now safely remove breakpoints. We don't this in earlier
1400 in common code because this target doesn't currently support
1401 writing memory while the inferior is running. */
1402 remove_breakpoints_inf (current_inferior ());
1404 iterate_over_lwps (ptid_t (pid
), detach_callback
);
1406 /* Only the initial process should be left right now. */
1407 gdb_assert (num_lwps (pid
) == 1);
1409 main_lwp
= find_lwp_pid (ptid_t (pid
));
1411 if (forks_exist_p ())
1413 /* Multi-fork case. The current inferior_ptid is being detached
1414 from, but there are other viable forks to debug. Detach from
1415 the current fork, and context-switch to the first
1417 linux_fork_detach (from_tty
);
1421 target_announce_detach (from_tty
);
1423 /* Pass on any pending signal for the last LWP. */
1424 int signo
= get_detach_signal (main_lwp
);
1426 detach_one_lwp (main_lwp
, &signo
);
1428 detach_success (inf
);
1431 close_proc_mem_file (pid
);
1434 /* Resume execution of the inferior process. If STEP is nonzero,
1435 single-step it. If SIGNAL is nonzero, give it that signal. */
1438 linux_resume_one_lwp_throw (struct lwp_info
*lp
, int step
,
1439 enum gdb_signal signo
)
1443 /* stop_pc doubles as the PC the LWP had when it was last resumed.
1444 We only presently need that if the LWP is stepped though (to
1445 handle the case of stepping a breakpoint instruction). */
1448 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
1450 lp
->stop_pc
= regcache_read_pc (regcache
);
1455 linux_target
->low_prepare_to_resume (lp
);
1456 linux_target
->low_resume (lp
->ptid
, step
, signo
);
1458 /* Successfully resumed. Clear state that no longer makes sense,
1459 and mark the LWP as running. Must not do this before resuming
1460 otherwise if that fails other code will be confused. E.g., we'd
1461 later try to stop the LWP and hang forever waiting for a stop
1462 status. Note that we must not throw after this is cleared,
1463 otherwise handle_zombie_lwp_error would get confused. */
1466 lp
->stop_reason
= TARGET_STOPPED_BY_NO_REASON
;
1467 registers_changed_ptid (linux_target
, lp
->ptid
);
1470 /* Called when we try to resume a stopped LWP and that errors out. If
1471 the LWP is no longer in ptrace-stopped state (meaning it's zombie,
1472 or about to become), discard the error, clear any pending status
1473 the LWP may have, and return true (we'll collect the exit status
1474 soon enough). Otherwise, return false. */
1477 check_ptrace_stopped_lwp_gone (struct lwp_info
*lp
)
1479 /* If we get an error after resuming the LWP successfully, we'd
1480 confuse !T state for the LWP being gone. */
1481 gdb_assert (lp
->stopped
);
1483 /* We can't just check whether the LWP is in 'Z (Zombie)' state,
1484 because even if ptrace failed with ESRCH, the tracee may be "not
1485 yet fully dead", but already refusing ptrace requests. In that
1486 case the tracee has 'R (Running)' state for a little bit
1487 (observed in Linux 3.18). See also the note on ESRCH in the
1488 ptrace(2) man page. Instead, check whether the LWP has any state
1489 other than ptrace-stopped. */
1491 /* Don't assume anything if /proc/PID/status can't be read. */
1492 if (linux_proc_pid_is_trace_stopped_nowarn (lp
->ptid
.lwp ()) == 0)
1494 lp
->stop_reason
= TARGET_STOPPED_BY_NO_REASON
;
1496 lp
->waitstatus
.set_ignore ();
1502 /* Like linux_resume_one_lwp_throw, but no error is thrown if the LWP
1503 disappears while we try to resume it. */
1506 linux_resume_one_lwp (struct lwp_info
*lp
, int step
, enum gdb_signal signo
)
1510 linux_resume_one_lwp_throw (lp
, step
, signo
);
1512 catch (const gdb_exception_error
&ex
)
1514 if (!check_ptrace_stopped_lwp_gone (lp
))
1522 resume_lwp (struct lwp_info
*lp
, int step
, enum gdb_signal signo
)
1526 struct inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
1528 if (inf
->vfork_child
!= NULL
)
1530 linux_nat_debug_printf ("Not resuming %s (vfork parent)",
1531 lp
->ptid
.to_string ().c_str ());
1533 else if (!lwp_status_pending_p (lp
))
1535 linux_nat_debug_printf ("Resuming sibling %s, %s, %s",
1536 lp
->ptid
.to_string ().c_str (),
1537 (signo
!= GDB_SIGNAL_0
1538 ? strsignal (gdb_signal_to_host (signo
))
1540 step
? "step" : "resume");
1542 linux_resume_one_lwp (lp
, step
, signo
);
1546 linux_nat_debug_printf ("Not resuming sibling %s (has pending)",
1547 lp
->ptid
.to_string ().c_str ());
1551 linux_nat_debug_printf ("Not resuming sibling %s (not stopped)",
1552 lp
->ptid
.to_string ().c_str ());
1555 /* Callback for iterate_over_lwps. If LWP is EXCEPT, do nothing.
1556 Resume LWP with the last stop signal, if it is in pass state. */
1559 linux_nat_resume_callback (struct lwp_info
*lp
, struct lwp_info
*except
)
1561 enum gdb_signal signo
= GDB_SIGNAL_0
;
1568 struct thread_info
*thread
;
1570 thread
= find_thread_ptid (linux_target
, lp
->ptid
);
1573 signo
= thread
->stop_signal ();
1574 thread
->set_stop_signal (GDB_SIGNAL_0
);
1578 resume_lwp (lp
, 0, signo
);
1583 resume_clear_callback (struct lwp_info
*lp
)
1586 lp
->last_resume_kind
= resume_stop
;
1591 resume_set_callback (struct lwp_info
*lp
)
1594 lp
->last_resume_kind
= resume_continue
;
1599 linux_nat_target::resume (ptid_t scope_ptid
, int step
, enum gdb_signal signo
)
1601 struct lwp_info
*lp
;
1603 linux_nat_debug_printf ("Preparing to %s %s, %s, inferior_ptid %s",
1604 step
? "step" : "resume",
1605 scope_ptid
.to_string ().c_str (),
1606 (signo
!= GDB_SIGNAL_0
1607 ? strsignal (gdb_signal_to_host (signo
)) : "0"),
1608 inferior_ptid
.to_string ().c_str ());
1610 /* Mark the lwps we're resuming as resumed and update their
1611 last_resume_kind to resume_continue. */
1612 iterate_over_lwps (scope_ptid
, resume_set_callback
);
1614 lp
= find_lwp_pid (inferior_ptid
);
1615 gdb_assert (lp
!= NULL
);
1617 /* Remember if we're stepping. */
1618 lp
->last_resume_kind
= step
? resume_step
: resume_continue
;
1620 /* If we have a pending wait status for this thread, there is no
1621 point in resuming the process. But first make sure that
1622 linux_nat_wait won't preemptively handle the event - we
1623 should never take this short-circuit if we are going to
1624 leave LP running, since we have skipped resuming all the
1625 other threads. This bit of code needs to be synchronized
1626 with linux_nat_wait. */
1628 if (lp
->status
&& WIFSTOPPED (lp
->status
))
1631 && WSTOPSIG (lp
->status
)
1632 && sigismember (&pass_mask
, WSTOPSIG (lp
->status
)))
1634 linux_nat_debug_printf
1635 ("Not short circuiting for ignored status 0x%x", lp
->status
);
1637 /* FIXME: What should we do if we are supposed to continue
1638 this thread with a signal? */
1639 gdb_assert (signo
== GDB_SIGNAL_0
);
1640 signo
= gdb_signal_from_host (WSTOPSIG (lp
->status
));
1645 if (lwp_status_pending_p (lp
))
1647 /* FIXME: What should we do if we are supposed to continue
1648 this thread with a signal? */
1649 gdb_assert (signo
== GDB_SIGNAL_0
);
1651 linux_nat_debug_printf ("Short circuiting for status 0x%x",
1654 if (target_can_async_p ())
1656 target_async (true);
1657 /* Tell the event loop we have something to process. */
1663 /* No use iterating unless we're resuming other threads. */
1664 if (scope_ptid
!= lp
->ptid
)
1665 iterate_over_lwps (scope_ptid
, [=] (struct lwp_info
*info
)
1667 return linux_nat_resume_callback (info
, lp
);
1670 linux_nat_debug_printf ("%s %s, %s (resume event thread)",
1671 step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
1672 lp
->ptid
.to_string ().c_str (),
1673 (signo
!= GDB_SIGNAL_0
1674 ? strsignal (gdb_signal_to_host (signo
)) : "0"));
1676 linux_resume_one_lwp (lp
, step
, signo
);
1679 /* Send a signal to an LWP. */
1682 kill_lwp (int lwpid
, int signo
)
1687 ret
= syscall (__NR_tkill
, lwpid
, signo
);
1688 if (errno
== ENOSYS
)
1690 /* If tkill fails, then we are not using nptl threads, a
1691 configuration we no longer support. */
1692 perror_with_name (("tkill"));
1697 /* Handle a GNU/Linux syscall trap wait response. If we see a syscall
1698 event, check if the core is interested in it: if not, ignore the
1699 event, and keep waiting; otherwise, we need to toggle the LWP's
1700 syscall entry/exit status, since the ptrace event itself doesn't
1701 indicate it, and report the trap to higher layers. */
1704 linux_handle_syscall_trap (struct lwp_info
*lp
, int stopping
)
1706 struct target_waitstatus
*ourstatus
= &lp
->waitstatus
;
1707 struct gdbarch
*gdbarch
= target_thread_architecture (lp
->ptid
);
1708 thread_info
*thread
= find_thread_ptid (linux_target
, lp
->ptid
);
1709 int syscall_number
= (int) gdbarch_get_syscall_number (gdbarch
, thread
);
1713 /* If we're stopping threads, there's a SIGSTOP pending, which
1714 makes it so that the LWP reports an immediate syscall return,
1715 followed by the SIGSTOP. Skip seeing that "return" using
1716 PTRACE_CONT directly, and let stop_wait_callback collect the
1717 SIGSTOP. Later when the thread is resumed, a new syscall
1718 entry event. If we didn't do this (and returned 0), we'd
1719 leave a syscall entry pending, and our caller, by using
1720 PTRACE_CONT to collect the SIGSTOP, skips the syscall return
1721 itself. Later, when the user re-resumes this LWP, we'd see
1722 another syscall entry event and we'd mistake it for a return.
1724 If stop_wait_callback didn't force the SIGSTOP out of the LWP
1725 (leaving immediately with LWP->signalled set, without issuing
1726 a PTRACE_CONT), it would still be problematic to leave this
1727 syscall enter pending, as later when the thread is resumed,
1728 it would then see the same syscall exit mentioned above,
1729 followed by the delayed SIGSTOP, while the syscall didn't
1730 actually get to execute. It seems it would be even more
1731 confusing to the user. */
1733 linux_nat_debug_printf
1734 ("ignoring syscall %d for LWP %ld (stopping threads), resuming with "
1735 "PTRACE_CONT for SIGSTOP", syscall_number
, lp
->ptid
.lwp ());
1737 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
1738 ptrace (PTRACE_CONT
, lp
->ptid
.lwp (), 0, 0);
1743 /* Always update the entry/return state, even if this particular
1744 syscall isn't interesting to the core now. In async mode,
1745 the user could install a new catchpoint for this syscall
1746 between syscall enter/return, and we'll need to know to
1747 report a syscall return if that happens. */
1748 lp
->syscall_state
= (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1749 ? TARGET_WAITKIND_SYSCALL_RETURN
1750 : TARGET_WAITKIND_SYSCALL_ENTRY
);
1752 if (catch_syscall_enabled ())
1754 if (catching_syscall_number (syscall_number
))
1756 /* Alright, an event to report. */
1757 if (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
)
1758 ourstatus
->set_syscall_entry (syscall_number
);
1759 else if (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_RETURN
)
1760 ourstatus
->set_syscall_return (syscall_number
);
1762 gdb_assert_not_reached ("unexpected syscall state");
1764 linux_nat_debug_printf
1765 ("stopping for %s of syscall %d for LWP %ld",
1766 (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1767 ? "entry" : "return"), syscall_number
, lp
->ptid
.lwp ());
1772 linux_nat_debug_printf
1773 ("ignoring %s of syscall %d for LWP %ld",
1774 (lp
->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
1775 ? "entry" : "return"), syscall_number
, lp
->ptid
.lwp ());
1779 /* If we had been syscall tracing, and hence used PT_SYSCALL
1780 before on this LWP, it could happen that the user removes all
1781 syscall catchpoints before we get to process this event.
1782 There are two noteworthy issues here:
1784 - When stopped at a syscall entry event, resuming with
1785 PT_STEP still resumes executing the syscall and reports a
1788 - Only PT_SYSCALL catches syscall enters. If we last
1789 single-stepped this thread, then this event can't be a
1790 syscall enter. If we last single-stepped this thread, this
1791 has to be a syscall exit.
1793 The points above mean that the next resume, be it PT_STEP or
1794 PT_CONTINUE, can not trigger a syscall trace event. */
1795 linux_nat_debug_printf
1796 ("caught syscall event with no syscall catchpoints. %d for LWP %ld, "
1797 "ignoring", syscall_number
, lp
->ptid
.lwp ());
1798 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
1801 /* The core isn't interested in this event. For efficiency, avoid
1802 stopping all threads only to have the core resume them all again.
1803 Since we're not stopping threads, if we're still syscall tracing
1804 and not stepping, we can't use PTRACE_CONT here, as we'd miss any
1805 subsequent syscall. Simply resume using the inf-ptrace layer,
1806 which knows when to use PT_SYSCALL or PT_CONTINUE. */
1808 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
1812 /* Handle a GNU/Linux extended wait response. If we see a clone
1813 event, we need to add the new LWP to our list (and not report the
1814 trap to higher layers). This function returns non-zero if the
1815 event should be ignored and we should wait again. If STOPPING is
1816 true, the new LWP remains stopped, otherwise it is continued. */
1819 linux_handle_extended_wait (struct lwp_info
*lp
, int status
)
1821 int pid
= lp
->ptid
.lwp ();
1822 struct target_waitstatus
*ourstatus
= &lp
->waitstatus
;
1823 int event
= linux_ptrace_get_extended_event (status
);
1825 /* All extended events we currently use are mid-syscall. Only
1826 PTRACE_EVENT_STOP is delivered more like a signal-stop, but
1827 you have to be using PTRACE_SEIZE to get that. */
1828 lp
->syscall_state
= TARGET_WAITKIND_SYSCALL_ENTRY
;
1830 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
1831 || event
== PTRACE_EVENT_CLONE
)
1833 unsigned long new_pid
;
1836 ptrace (PTRACE_GETEVENTMSG
, pid
, 0, &new_pid
);
1838 /* If we haven't already seen the new PID stop, wait for it now. */
1839 if (! pull_pid_from_list (&stopped_pids
, new_pid
, &status
))
1841 /* The new child has a pending SIGSTOP. We can't affect it until it
1842 hits the SIGSTOP, but we're already attached. */
1843 ret
= my_waitpid (new_pid
, &status
, __WALL
);
1845 perror_with_name (_("waiting for new child"));
1846 else if (ret
!= new_pid
)
1847 internal_error (__FILE__
, __LINE__
,
1848 _("wait returned unexpected PID %d"), ret
);
1849 else if (!WIFSTOPPED (status
))
1850 internal_error (__FILE__
, __LINE__
,
1851 _("wait returned unexpected status 0x%x"), status
);
1854 ptid_t
child_ptid (new_pid
, new_pid
);
1856 if (event
== PTRACE_EVENT_FORK
|| event
== PTRACE_EVENT_VFORK
)
1858 open_proc_mem_file (child_ptid
);
1860 /* The arch-specific native code may need to know about new
1861 forks even if those end up never mapped to an
1863 linux_target
->low_new_fork (lp
, new_pid
);
1865 else if (event
== PTRACE_EVENT_CLONE
)
1867 linux_target
->low_new_clone (lp
, new_pid
);
1870 if (event
== PTRACE_EVENT_FORK
1871 && linux_fork_checkpointing_p (lp
->ptid
.pid ()))
1873 /* Handle checkpointing by linux-fork.c here as a special
1874 case. We don't want the follow-fork-mode or 'catch fork'
1875 to interfere with this. */
1877 /* This won't actually modify the breakpoint list, but will
1878 physically remove the breakpoints from the child. */
1879 detach_breakpoints (ptid_t (new_pid
, new_pid
));
1881 /* Retain child fork in ptrace (stopped) state. */
1882 if (!find_fork_pid (new_pid
))
1885 /* Report as spurious, so that infrun doesn't want to follow
1886 this fork. We're actually doing an infcall in
1888 ourstatus
->set_spurious ();
1890 /* Report the stop to the core. */
1894 if (event
== PTRACE_EVENT_FORK
)
1895 ourstatus
->set_forked (child_ptid
);
1896 else if (event
== PTRACE_EVENT_VFORK
)
1897 ourstatus
->set_vforked (child_ptid
);
1898 else if (event
== PTRACE_EVENT_CLONE
)
1900 struct lwp_info
*new_lp
;
1902 ourstatus
->set_ignore ();
1904 linux_nat_debug_printf
1905 ("Got clone event from LWP %d, new child is LWP %ld", pid
, new_pid
);
1907 new_lp
= add_lwp (ptid_t (lp
->ptid
.pid (), new_pid
));
1908 new_lp
->stopped
= 1;
1909 new_lp
->resumed
= 1;
1911 /* If the thread_db layer is active, let it record the user
1912 level thread id and status, and add the thread to GDB's
1914 if (!thread_db_notice_clone (lp
->ptid
, new_lp
->ptid
))
1916 /* The process is not using thread_db. Add the LWP to
1918 target_post_attach (new_lp
->ptid
.lwp ());
1919 add_thread (linux_target
, new_lp
->ptid
);
1922 /* Even if we're stopping the thread for some reason
1923 internal to this module, from the perspective of infrun
1924 and the user/frontend, this new thread is running until
1925 it next reports a stop. */
1926 set_running (linux_target
, new_lp
->ptid
, true);
1927 set_executing (linux_target
, new_lp
->ptid
, true);
1929 if (WSTOPSIG (status
) != SIGSTOP
)
1931 /* This can happen if someone starts sending signals to
1932 the new thread before it gets a chance to run, which
1933 have a lower number than SIGSTOP (e.g. SIGUSR1).
1934 This is an unlikely case, and harder to handle for
1935 fork / vfork than for clone, so we do not try - but
1936 we handle it for clone events here. */
1938 new_lp
->signalled
= 1;
1940 /* We created NEW_LP so it cannot yet contain STATUS. */
1941 gdb_assert (new_lp
->status
== 0);
1943 /* Save the wait status to report later. */
1944 linux_nat_debug_printf
1945 ("waitpid of new LWP %ld, saving status %s",
1946 (long) new_lp
->ptid
.lwp (), status_to_str (status
).c_str ());
1947 new_lp
->status
= status
;
1949 else if (report_thread_events
)
1951 new_lp
->waitstatus
.set_thread_created ();
1952 new_lp
->status
= status
;
1961 if (event
== PTRACE_EVENT_EXEC
)
1963 linux_nat_debug_printf ("Got exec event from LWP %ld", lp
->ptid
.lwp ());
1965 /* Close the previous /proc/PID/mem file for this inferior,
1966 which was using the address space which is now gone.
1967 Reading/writing from this file would return 0/EOF. */
1968 close_proc_mem_file (lp
->ptid
.pid ());
1970 /* Open a new file for the new address space. */
1971 open_proc_mem_file (lp
->ptid
);
1973 ourstatus
->set_execd
1974 (make_unique_xstrdup (linux_proc_pid_to_exec_file (pid
)));
1976 /* The thread that execed must have been resumed, but, when a
1977 thread execs, it changes its tid to the tgid, and the old
1978 tgid thread might have not been resumed. */
1983 if (event
== PTRACE_EVENT_VFORK_DONE
)
1985 linux_nat_debug_printf
1986 ("Got PTRACE_EVENT_VFORK_DONE from LWP %ld",
1988 ourstatus
->set_vfork_done ();
1992 internal_error (__FILE__
, __LINE__
,
1993 _("unknown ptrace event %d"), event
);
1996 /* Suspend waiting for a signal. We're mostly interested in
2002 linux_nat_debug_printf ("about to sigsuspend");
2003 sigsuspend (&suspend_mask
);
2005 /* If the quit flag is set, it means that the user pressed Ctrl-C
2006 and we're debugging a process that is running on a separate
2007 terminal, so we must forward the Ctrl-C to the inferior. (If the
2008 inferior is sharing GDB's terminal, then the Ctrl-C reaches the
2009 inferior directly.) We must do this here because functions that
2010 need to block waiting for a signal loop forever until there's an
2011 event to report before returning back to the event loop. */
2012 if (!target_terminal::is_ours ())
2014 if (check_quit_flag ())
2015 target_pass_ctrlc ();
2019 /* Wait for LP to stop. Returns the wait status, or 0 if the LWP has
2023 wait_lwp (struct lwp_info
*lp
)
2027 int thread_dead
= 0;
2030 gdb_assert (!lp
->stopped
);
2031 gdb_assert (lp
->status
== 0);
2033 /* Make sure SIGCHLD is blocked for sigsuspend avoiding a race below. */
2034 block_child_signals (&prev_mask
);
2038 pid
= my_waitpid (lp
->ptid
.lwp (), &status
, __WALL
| WNOHANG
);
2039 if (pid
== -1 && errno
== ECHILD
)
2041 /* The thread has previously exited. We need to delete it
2042 now because if this was a non-leader thread execing, we
2043 won't get an exit event. See comments on exec events at
2044 the top of the file. */
2046 linux_nat_debug_printf ("%s vanished.",
2047 lp
->ptid
.to_string ().c_str ());
2052 /* Bugs 10970, 12702.
2053 Thread group leader may have exited in which case we'll lock up in
2054 waitpid if there are other threads, even if they are all zombies too.
2055 Basically, we're not supposed to use waitpid this way.
2056 tkill(pid,0) cannot be used here as it gets ESRCH for both
2057 for zombie and running processes.
2059 As a workaround, check if we're waiting for the thread group leader and
2060 if it's a zombie, and avoid calling waitpid if it is.
2062 This is racy, what if the tgl becomes a zombie right after we check?
2063 Therefore always use WNOHANG with sigsuspend - it is equivalent to
2064 waiting waitpid but linux_proc_pid_is_zombie is safe this way. */
2066 if (lp
->ptid
.pid () == lp
->ptid
.lwp ()
2067 && linux_proc_pid_is_zombie (lp
->ptid
.lwp ()))
2070 linux_nat_debug_printf ("Thread group leader %s vanished.",
2071 lp
->ptid
.to_string ().c_str ());
2075 /* Wait for next SIGCHLD and try again. This may let SIGCHLD handlers
2076 get invoked despite our caller had them intentionally blocked by
2077 block_child_signals. This is sensitive only to the loop of
2078 linux_nat_wait_1 and there if we get called my_waitpid gets called
2079 again before it gets to sigsuspend so we can safely let the handlers
2080 get executed here. */
2084 restore_child_signals_mask (&prev_mask
);
2088 gdb_assert (pid
== lp
->ptid
.lwp ());
2090 linux_nat_debug_printf ("waitpid %s received %s",
2091 lp
->ptid
.to_string ().c_str (),
2092 status_to_str (status
).c_str ());
2094 /* Check if the thread has exited. */
2095 if (WIFEXITED (status
) || WIFSIGNALED (status
))
2097 if (report_thread_events
2098 || lp
->ptid
.pid () == lp
->ptid
.lwp ())
2100 linux_nat_debug_printf ("LWP %d exited.", lp
->ptid
.pid ());
2102 /* If this is the leader exiting, it means the whole
2103 process is gone. Store the status to report to the
2104 core. Store it in lp->waitstatus, because lp->status
2105 would be ambiguous (W_EXITCODE(0,0) == 0). */
2106 lp
->waitstatus
= host_status_to_waitstatus (status
);
2111 linux_nat_debug_printf ("%s exited.",
2112 lp
->ptid
.to_string ().c_str ());
2122 gdb_assert (WIFSTOPPED (status
));
2125 if (lp
->must_set_ptrace_flags
)
2127 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2128 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
2130 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
2131 lp
->must_set_ptrace_flags
= 0;
2134 /* Handle GNU/Linux's syscall SIGTRAPs. */
2135 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
2137 /* No longer need the sysgood bit. The ptrace event ends up
2138 recorded in lp->waitstatus if we care for it. We can carry
2139 on handling the event like a regular SIGTRAP from here
2141 status
= W_STOPCODE (SIGTRAP
);
2142 if (linux_handle_syscall_trap (lp
, 1))
2143 return wait_lwp (lp
);
2147 /* Almost all other ptrace-stops are known to be outside of system
2148 calls, with further exceptions in linux_handle_extended_wait. */
2149 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
2152 /* Handle GNU/Linux's extended waitstatus for trace events. */
2153 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
2154 && linux_is_extended_waitstatus (status
))
2156 linux_nat_debug_printf ("Handling extended status 0x%06x", status
);
2157 linux_handle_extended_wait (lp
, status
);
2164 /* Send a SIGSTOP to LP. */
2167 stop_callback (struct lwp_info
*lp
)
2169 if (!lp
->stopped
&& !lp
->signalled
)
2173 linux_nat_debug_printf ("kill %s **<SIGSTOP>**",
2174 lp
->ptid
.to_string ().c_str ());
2177 ret
= kill_lwp (lp
->ptid
.lwp (), SIGSTOP
);
2178 linux_nat_debug_printf ("lwp kill %d %s", ret
,
2179 errno
? safe_strerror (errno
) : "ERRNO-OK");
2182 gdb_assert (lp
->status
== 0);
2188 /* Request a stop on LWP. */
2191 linux_stop_lwp (struct lwp_info
*lwp
)
2193 stop_callback (lwp
);
2196 /* See linux-nat.h */
2199 linux_stop_and_wait_all_lwps (void)
2201 /* Stop all LWP's ... */
2202 iterate_over_lwps (minus_one_ptid
, stop_callback
);
2204 /* ... and wait until all of them have reported back that
2205 they're no longer running. */
2206 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
2209 /* See linux-nat.h */
2212 linux_unstop_all_lwps (void)
2214 iterate_over_lwps (minus_one_ptid
,
2215 [] (struct lwp_info
*info
)
2217 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
2221 /* Return non-zero if LWP PID has a pending SIGINT. */
2224 linux_nat_has_pending_sigint (int pid
)
2226 sigset_t pending
, blocked
, ignored
;
2228 linux_proc_pending_signals (pid
, &pending
, &blocked
, &ignored
);
2230 if (sigismember (&pending
, SIGINT
)
2231 && !sigismember (&ignored
, SIGINT
))
2237 /* Set a flag in LP indicating that we should ignore its next SIGINT. */
2240 set_ignore_sigint (struct lwp_info
*lp
)
2242 /* If a thread has a pending SIGINT, consume it; otherwise, set a
2243 flag to consume the next one. */
2244 if (lp
->stopped
&& lp
->status
!= 0 && WIFSTOPPED (lp
->status
)
2245 && WSTOPSIG (lp
->status
) == SIGINT
)
2248 lp
->ignore_sigint
= 1;
2253 /* If LP does not have a SIGINT pending, then clear the ignore_sigint flag.
2254 This function is called after we know the LWP has stopped; if the LWP
2255 stopped before the expected SIGINT was delivered, then it will never have
2256 arrived. Also, if the signal was delivered to a shared queue and consumed
2257 by a different thread, it will never be delivered to this LWP. */
2260 maybe_clear_ignore_sigint (struct lwp_info
*lp
)
2262 if (!lp
->ignore_sigint
)
2265 if (!linux_nat_has_pending_sigint (lp
->ptid
.lwp ()))
2267 linux_nat_debug_printf ("Clearing bogus flag for %s",
2268 lp
->ptid
.to_string ().c_str ());
2269 lp
->ignore_sigint
= 0;
2273 /* Fetch the possible triggered data watchpoint info and store it in
2276 On some archs, like x86, that use debug registers to set
2277 watchpoints, it's possible that the way to know which watched
2278 address trapped, is to check the register that is used to select
2279 which address to watch. Problem is, between setting the watchpoint
2280 and reading back which data address trapped, the user may change
2281 the set of watchpoints, and, as a consequence, GDB changes the
2282 debug registers in the inferior. To avoid reading back a stale
2283 stopped-data-address when that happens, we cache in LP the fact
2284 that a watchpoint trapped, and the corresponding data address, as
2285 soon as we see LP stop with a SIGTRAP. If GDB changes the debug
2286 registers meanwhile, we have the cached data we can rely on. */
2289 check_stopped_by_watchpoint (struct lwp_info
*lp
)
2291 scoped_restore save_inferior_ptid
= make_scoped_restore (&inferior_ptid
);
2292 inferior_ptid
= lp
->ptid
;
2294 if (linux_target
->low_stopped_by_watchpoint ())
2296 lp
->stop_reason
= TARGET_STOPPED_BY_WATCHPOINT
;
2297 lp
->stopped_data_address_p
2298 = linux_target
->low_stopped_data_address (&lp
->stopped_data_address
);
2301 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2304 /* Returns true if the LWP had stopped for a watchpoint. */
2307 linux_nat_target::stopped_by_watchpoint ()
2309 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2311 gdb_assert (lp
!= NULL
);
2313 return lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
;
2317 linux_nat_target::stopped_data_address (CORE_ADDR
*addr_p
)
2319 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2321 gdb_assert (lp
!= NULL
);
2323 *addr_p
= lp
->stopped_data_address
;
2325 return lp
->stopped_data_address_p
;
2328 /* Commonly any breakpoint / watchpoint generate only SIGTRAP. */
2331 linux_nat_target::low_status_is_event (int status
)
2333 return WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
;
2336 /* Wait until LP is stopped. */
2339 stop_wait_callback (struct lwp_info
*lp
)
2341 inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
2343 /* If this is a vfork parent, bail out, it is not going to report
2344 any SIGSTOP until the vfork is done with. */
2345 if (inf
->vfork_child
!= NULL
)
2352 status
= wait_lwp (lp
);
2356 if (lp
->ignore_sigint
&& WIFSTOPPED (status
)
2357 && WSTOPSIG (status
) == SIGINT
)
2359 lp
->ignore_sigint
= 0;
2362 ptrace (PTRACE_CONT
, lp
->ptid
.lwp (), 0, 0);
2364 linux_nat_debug_printf
2365 ("PTRACE_CONT %s, 0, 0 (%s) (discarding SIGINT)",
2366 lp
->ptid
.to_string ().c_str (),
2367 errno
? safe_strerror (errno
) : "OK");
2369 return stop_wait_callback (lp
);
2372 maybe_clear_ignore_sigint (lp
);
2374 if (WSTOPSIG (status
) != SIGSTOP
)
2376 /* The thread was stopped with a signal other than SIGSTOP. */
2378 linux_nat_debug_printf ("Pending event %s in %s",
2379 status_to_str ((int) status
).c_str (),
2380 lp
->ptid
.to_string ().c_str ());
2382 /* Save the sigtrap event. */
2383 lp
->status
= status
;
2384 gdb_assert (lp
->signalled
);
2385 save_stop_reason (lp
);
2389 /* We caught the SIGSTOP that we intended to catch. */
2391 linux_nat_debug_printf ("Expected SIGSTOP caught for %s.",
2392 lp
->ptid
.to_string ().c_str ());
2396 /* If we are waiting for this stop so we can report the thread
2397 stopped then we need to record this status. Otherwise, we can
2398 now discard this stop event. */
2399 if (lp
->last_resume_kind
== resume_stop
)
2401 lp
->status
= status
;
2402 save_stop_reason (lp
);
2410 /* Return non-zero if LP has a wait status pending. Discard the
2411 pending event and resume the LWP if the event that originally
2412 caused the stop became uninteresting. */
2415 status_callback (struct lwp_info
*lp
)
2417 /* Only report a pending wait status if we pretend that this has
2418 indeed been resumed. */
2422 if (!lwp_status_pending_p (lp
))
2425 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
2426 || lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2428 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2432 pc
= regcache_read_pc (regcache
);
2434 if (pc
!= lp
->stop_pc
)
2436 linux_nat_debug_printf ("PC of %s changed. was=%s, now=%s",
2437 lp
->ptid
.to_string ().c_str (),
2438 paddress (target_gdbarch (), lp
->stop_pc
),
2439 paddress (target_gdbarch (), pc
));
2443 #if !USE_SIGTRAP_SIGINFO
2444 else if (!breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2446 linux_nat_debug_printf ("previous breakpoint of %s, at %s gone",
2447 lp
->ptid
.to_string ().c_str (),
2448 paddress (target_gdbarch (), lp
->stop_pc
));
2456 linux_nat_debug_printf ("pending event of %s cancelled.",
2457 lp
->ptid
.to_string ().c_str ());
2460 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2468 /* Count the LWP's that have had events. */
2471 count_events_callback (struct lwp_info
*lp
, int *count
)
2473 gdb_assert (count
!= NULL
);
2475 /* Select only resumed LWPs that have an event pending. */
2476 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2482 /* Select the LWP (if any) that is currently being single-stepped. */
2485 select_singlestep_lwp_callback (struct lwp_info
*lp
)
2487 if (lp
->last_resume_kind
== resume_step
2494 /* Returns true if LP has a status pending. */
2497 lwp_status_pending_p (struct lwp_info
*lp
)
2499 /* We check for lp->waitstatus in addition to lp->status, because we
2500 can have pending process exits recorded in lp->status and
2501 W_EXITCODE(0,0) happens to be 0. */
2502 return lp
->status
!= 0 || lp
->waitstatus
.kind () != TARGET_WAITKIND_IGNORE
;
2505 /* Select the Nth LWP that has had an event. */
2508 select_event_lwp_callback (struct lwp_info
*lp
, int *selector
)
2510 gdb_assert (selector
!= NULL
);
2512 /* Select only resumed LWPs that have an event pending. */
2513 if (lp
->resumed
&& lwp_status_pending_p (lp
))
2514 if ((*selector
)-- == 0)
2520 /* Called when the LWP stopped for a signal/trap. If it stopped for a
2521 trap check what caused it (breakpoint, watchpoint, trace, etc.),
2522 and save the result in the LWP's stop_reason field. If it stopped
2523 for a breakpoint, decrement the PC if necessary on the lwp's
2527 save_stop_reason (struct lwp_info
*lp
)
2529 struct regcache
*regcache
;
2530 struct gdbarch
*gdbarch
;
2533 #if USE_SIGTRAP_SIGINFO
2537 gdb_assert (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
);
2538 gdb_assert (lp
->status
!= 0);
2540 if (!linux_target
->low_status_is_event (lp
->status
))
2543 inferior
*inf
= find_inferior_ptid (linux_target
, lp
->ptid
);
2544 if (inf
->starting_up
)
2547 regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
2548 gdbarch
= regcache
->arch ();
2550 pc
= regcache_read_pc (regcache
);
2551 sw_bp_pc
= pc
- gdbarch_decr_pc_after_break (gdbarch
);
2553 #if USE_SIGTRAP_SIGINFO
2554 if (linux_nat_get_siginfo (lp
->ptid
, &siginfo
))
2556 if (siginfo
.si_signo
== SIGTRAP
)
2558 if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
)
2559 && GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2561 /* The si_code is ambiguous on this arch -- check debug
2563 if (!check_stopped_by_watchpoint (lp
))
2564 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2566 else if (GDB_ARCH_IS_TRAP_BRKPT (siginfo
.si_code
))
2568 /* If we determine the LWP stopped for a SW breakpoint,
2569 trust it. Particularly don't check watchpoint
2570 registers, because, at least on s390, we'd find
2571 stopped-by-watchpoint as long as there's a watchpoint
2573 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2575 else if (GDB_ARCH_IS_TRAP_HWBKPT (siginfo
.si_code
))
2577 /* This can indicate either a hardware breakpoint or
2578 hardware watchpoint. Check debug registers. */
2579 if (!check_stopped_by_watchpoint (lp
))
2580 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2582 else if (siginfo
.si_code
== TRAP_TRACE
)
2584 linux_nat_debug_printf ("%s stopped by trace",
2585 lp
->ptid
.to_string ().c_str ());
2587 /* We may have single stepped an instruction that
2588 triggered a watchpoint. In that case, on some
2589 architectures (such as x86), instead of TRAP_HWBKPT,
2590 si_code indicates TRAP_TRACE, and we need to check
2591 the debug registers separately. */
2592 check_stopped_by_watchpoint (lp
);
2597 if ((!lp
->step
|| lp
->stop_pc
== sw_bp_pc
)
2598 && software_breakpoint_inserted_here_p (regcache
->aspace (),
2601 /* The LWP was either continued, or stepped a software
2602 breakpoint instruction. */
2603 lp
->stop_reason
= TARGET_STOPPED_BY_SW_BREAKPOINT
;
2606 if (hardware_breakpoint_inserted_here_p (regcache
->aspace (), pc
))
2607 lp
->stop_reason
= TARGET_STOPPED_BY_HW_BREAKPOINT
;
2609 if (lp
->stop_reason
== TARGET_STOPPED_BY_NO_REASON
)
2610 check_stopped_by_watchpoint (lp
);
2613 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
)
2615 linux_nat_debug_printf ("%s stopped by software breakpoint",
2616 lp
->ptid
.to_string ().c_str ());
2618 /* Back up the PC if necessary. */
2620 regcache_write_pc (regcache
, sw_bp_pc
);
2622 /* Update this so we record the correct stop PC below. */
2625 else if (lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
)
2627 linux_nat_debug_printf ("%s stopped by hardware breakpoint",
2628 lp
->ptid
.to_string ().c_str ());
2630 else if (lp
->stop_reason
== TARGET_STOPPED_BY_WATCHPOINT
)
2632 linux_nat_debug_printf ("%s stopped by hardware watchpoint",
2633 lp
->ptid
.to_string ().c_str ());
2640 /* Returns true if the LWP had stopped for a software breakpoint. */
2643 linux_nat_target::stopped_by_sw_breakpoint ()
2645 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2647 gdb_assert (lp
!= NULL
);
2649 return lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
;
2652 /* Implement the supports_stopped_by_sw_breakpoint method. */
2655 linux_nat_target::supports_stopped_by_sw_breakpoint ()
2657 return USE_SIGTRAP_SIGINFO
;
2660 /* Returns true if the LWP had stopped for a hardware
2661 breakpoint/watchpoint. */
2664 linux_nat_target::stopped_by_hw_breakpoint ()
2666 struct lwp_info
*lp
= find_lwp_pid (inferior_ptid
);
2668 gdb_assert (lp
!= NULL
);
2670 return lp
->stop_reason
== TARGET_STOPPED_BY_HW_BREAKPOINT
;
2673 /* Implement the supports_stopped_by_hw_breakpoint method. */
2676 linux_nat_target::supports_stopped_by_hw_breakpoint ()
2678 return USE_SIGTRAP_SIGINFO
;
2681 /* Select one LWP out of those that have events pending. */
2684 select_event_lwp (ptid_t filter
, struct lwp_info
**orig_lp
, int *status
)
2687 int random_selector
;
2688 struct lwp_info
*event_lp
= NULL
;
2690 /* Record the wait status for the original LWP. */
2691 (*orig_lp
)->status
= *status
;
2693 /* In all-stop, give preference to the LWP that is being
2694 single-stepped. There will be at most one, and it will be the
2695 LWP that the core is most interested in. If we didn't do this,
2696 then we'd have to handle pending step SIGTRAPs somehow in case
2697 the core later continues the previously-stepped thread, as
2698 otherwise we'd report the pending SIGTRAP then, and the core, not
2699 having stepped the thread, wouldn't understand what the trap was
2700 for, and therefore would report it to the user as a random
2702 if (!target_is_non_stop_p ())
2704 event_lp
= iterate_over_lwps (filter
, select_singlestep_lwp_callback
);
2705 if (event_lp
!= NULL
)
2707 linux_nat_debug_printf ("Select single-step %s",
2708 event_lp
->ptid
.to_string ().c_str ());
2712 if (event_lp
== NULL
)
2714 /* Pick one at random, out of those which have had events. */
2716 /* First see how many events we have. */
2717 iterate_over_lwps (filter
,
2718 [&] (struct lwp_info
*info
)
2720 return count_events_callback (info
, &num_events
);
2722 gdb_assert (num_events
> 0);
2724 /* Now randomly pick a LWP out of those that have had
2726 random_selector
= (int)
2727 ((num_events
* (double) rand ()) / (RAND_MAX
+ 1.0));
2730 linux_nat_debug_printf ("Found %d events, selecting #%d",
2731 num_events
, random_selector
);
2734 = (iterate_over_lwps
2736 [&] (struct lwp_info
*info
)
2738 return select_event_lwp_callback (info
,
2743 if (event_lp
!= NULL
)
2745 /* Switch the event LWP. */
2746 *orig_lp
= event_lp
;
2747 *status
= event_lp
->status
;
2750 /* Flush the wait status for the event LWP. */
2751 (*orig_lp
)->status
= 0;
2754 /* Return non-zero if LP has been resumed. */
2757 resumed_callback (struct lwp_info
*lp
)
2762 /* Check if we should go on and pass this event to common code.
2764 If so, save the status to the lwp_info structure associated to LWPID. */
2767 linux_nat_filter_event (int lwpid
, int status
)
2769 struct lwp_info
*lp
;
2770 int event
= linux_ptrace_get_extended_event (status
);
2772 lp
= find_lwp_pid (ptid_t (lwpid
));
2774 /* Check for events reported by anything not in our LWP list. */
2777 if (WIFSTOPPED (status
))
2779 if (WSTOPSIG (status
) == SIGTRAP
&& event
== PTRACE_EVENT_EXEC
)
2781 /* A non-leader thread exec'ed after we've seen the
2782 leader zombie, and removed it from our lists (in
2783 check_zombie_leaders). The non-leader thread changes
2784 its tid to the tgid. */
2785 linux_nat_debug_printf
2786 ("Re-adding thread group leader LWP %d after exec.",
2789 lp
= add_lwp (ptid_t (lwpid
, lwpid
));
2792 add_thread (linux_target
, lp
->ptid
);
2796 /* A process we are controlling has forked and the new
2797 child's stop was reported to us by the kernel. Save
2798 its PID and go back to waiting for the fork event to
2799 be reported - the stopped process might be returned
2800 from waitpid before or after the fork event is. */
2801 linux_nat_debug_printf
2802 ("Saving LWP %d status %s in stopped_pids list",
2803 lwpid
, status_to_str (status
).c_str ());
2804 add_to_pid_list (&stopped_pids
, lwpid
, status
);
2809 /* Don't report an event for the exit of an LWP not in our
2810 list, i.e. not part of any inferior we're debugging.
2811 This can happen if we detach from a program we originally
2812 forked and then it exits. However, note that we may have
2813 earlier deleted a leader of an inferior we're debugging,
2814 in check_zombie_leaders. Re-add it back here if so. */
2815 for (inferior
*inf
: all_inferiors (linux_target
))
2817 if (inf
->pid
== lwpid
)
2819 linux_nat_debug_printf
2820 ("Re-adding thread group leader LWP %d after exit.",
2823 lp
= add_lwp (ptid_t (lwpid
, lwpid
));
2825 add_thread (linux_target
, lp
->ptid
);
2835 /* This LWP is stopped now. (And if dead, this prevents it from
2836 ever being continued.) */
2839 if (WIFSTOPPED (status
) && lp
->must_set_ptrace_flags
)
2841 inferior
*inf
= find_inferior_pid (linux_target
, lp
->ptid
.pid ());
2842 int options
= linux_nat_ptrace_options (inf
->attach_flag
);
2844 linux_enable_event_reporting (lp
->ptid
.lwp (), options
);
2845 lp
->must_set_ptrace_flags
= 0;
2848 /* Handle GNU/Linux's syscall SIGTRAPs. */
2849 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SYSCALL_SIGTRAP
)
2851 /* No longer need the sysgood bit. The ptrace event ends up
2852 recorded in lp->waitstatus if we care for it. We can carry
2853 on handling the event like a regular SIGTRAP from here
2855 status
= W_STOPCODE (SIGTRAP
);
2856 if (linux_handle_syscall_trap (lp
, 0))
2861 /* Almost all other ptrace-stops are known to be outside of system
2862 calls, with further exceptions in linux_handle_extended_wait. */
2863 lp
->syscall_state
= TARGET_WAITKIND_IGNORE
;
2866 /* Handle GNU/Linux's extended waitstatus for trace events. */
2867 if (WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGTRAP
2868 && linux_is_extended_waitstatus (status
))
2870 linux_nat_debug_printf ("Handling extended status 0x%06x", status
);
2872 if (linux_handle_extended_wait (lp
, status
))
2876 /* Check if the thread has exited. */
2877 if (WIFEXITED (status
) || WIFSIGNALED (status
))
2879 if (!report_thread_events
&& !is_leader (lp
))
2881 linux_nat_debug_printf ("%s exited.",
2882 lp
->ptid
.to_string ().c_str ());
2884 /* If this was not the leader exiting, then the exit signal
2885 was not the end of the debugged application and should be
2891 /* Note that even if the leader was ptrace-stopped, it can still
2892 exit, if e.g., some other thread brings down the whole
2893 process (calls `exit'). So don't assert that the lwp is
2895 linux_nat_debug_printf ("LWP %ld exited (resumed=%d)",
2896 lp
->ptid
.lwp (), lp
->resumed
);
2898 /* Dead LWP's aren't expected to reported a pending sigstop. */
2901 /* Store the pending event in the waitstatus, because
2902 W_EXITCODE(0,0) == 0. */
2903 lp
->waitstatus
= host_status_to_waitstatus (status
);
2907 /* Make sure we don't report a SIGSTOP that we sent ourselves in
2908 an attempt to stop an LWP. */
2910 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGSTOP
)
2914 if (lp
->last_resume_kind
== resume_stop
)
2916 linux_nat_debug_printf ("resume_stop SIGSTOP caught for %s.",
2917 lp
->ptid
.to_string ().c_str ());
2921 /* This is a delayed SIGSTOP. Filter out the event. */
2923 linux_nat_debug_printf
2924 ("%s %s, 0, 0 (discard delayed SIGSTOP)",
2925 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
2926 lp
->ptid
.to_string ().c_str ());
2928 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2929 gdb_assert (lp
->resumed
);
2934 /* Make sure we don't report a SIGINT that we have already displayed
2935 for another thread. */
2936 if (lp
->ignore_sigint
2937 && WIFSTOPPED (status
) && WSTOPSIG (status
) == SIGINT
)
2939 linux_nat_debug_printf ("Delayed SIGINT caught for %s.",
2940 lp
->ptid
.to_string ().c_str ());
2942 /* This is a delayed SIGINT. */
2943 lp
->ignore_sigint
= 0;
2945 linux_resume_one_lwp (lp
, lp
->step
, GDB_SIGNAL_0
);
2946 linux_nat_debug_printf ("%s %s, 0, 0 (discard SIGINT)",
2947 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
2948 lp
->ptid
.to_string ().c_str ());
2949 gdb_assert (lp
->resumed
);
2951 /* Discard the event. */
2955 /* Don't report signals that GDB isn't interested in, such as
2956 signals that are neither printed nor stopped upon. Stopping all
2957 threads can be a bit time-consuming, so if we want decent
2958 performance with heavily multi-threaded programs, especially when
2959 they're using a high frequency timer, we'd better avoid it if we
2961 if (WIFSTOPPED (status
))
2963 enum gdb_signal signo
= gdb_signal_from_host (WSTOPSIG (status
));
2965 if (!target_is_non_stop_p ())
2967 /* Only do the below in all-stop, as we currently use SIGSTOP
2968 to implement target_stop (see linux_nat_stop) in
2970 if (signo
== GDB_SIGNAL_INT
&& signal_pass_state (signo
) == 0)
2972 /* If ^C/BREAK is typed at the tty/console, SIGINT gets
2973 forwarded to the entire process group, that is, all LWPs
2974 will receive it - unless they're using CLONE_THREAD to
2975 share signals. Since we only want to report it once, we
2976 mark it as ignored for all LWPs except this one. */
2977 iterate_over_lwps (ptid_t (lp
->ptid
.pid ()), set_ignore_sigint
);
2978 lp
->ignore_sigint
= 0;
2981 maybe_clear_ignore_sigint (lp
);
2984 /* When using hardware single-step, we need to report every signal.
2985 Otherwise, signals in pass_mask may be short-circuited
2986 except signals that might be caused by a breakpoint, or SIGSTOP
2987 if we sent the SIGSTOP and are waiting for it to arrive. */
2989 && WSTOPSIG (status
) && sigismember (&pass_mask
, WSTOPSIG (status
))
2990 && (WSTOPSIG (status
) != SIGSTOP
2991 || !find_thread_ptid (linux_target
, lp
->ptid
)->stop_requested
)
2992 && !linux_wstatus_maybe_breakpoint (status
))
2994 linux_resume_one_lwp (lp
, lp
->step
, signo
);
2995 linux_nat_debug_printf
2996 ("%s %s, %s (preempt 'handle')",
2997 lp
->step
? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
2998 lp
->ptid
.to_string ().c_str (),
2999 (signo
!= GDB_SIGNAL_0
3000 ? strsignal (gdb_signal_to_host (signo
)) : "0"));
3005 /* An interesting event. */
3007 lp
->status
= status
;
3008 save_stop_reason (lp
);
3011 /* Detect zombie thread group leaders, and "exit" them. We can't reap
3012 their exits until all other threads in the group have exited. */
3015 check_zombie_leaders (void)
3017 for (inferior
*inf
: all_inferiors ())
3019 struct lwp_info
*leader_lp
;
3024 leader_lp
= find_lwp_pid (ptid_t (inf
->pid
));
3025 if (leader_lp
!= NULL
3026 /* Check if there are other threads in the group, as we may
3027 have raced with the inferior simply exiting. Note this
3028 isn't a watertight check. If the inferior is
3029 multi-threaded and is exiting, it may be we see the
3030 leader as zombie before we reap all the non-leader
3031 threads. See comments below. */
3032 && num_lwps (inf
->pid
) > 1
3033 && linux_proc_pid_is_zombie (inf
->pid
))
3035 /* A zombie leader in a multi-threaded program can mean one
3038 #1 - Only the leader exited, not the whole program, e.g.,
3039 with pthread_exit. Since we can't reap the leader's exit
3040 status until all other threads are gone and reaped too,
3041 we want to delete the zombie leader right away, as it
3042 can't be debugged, we can't read its registers, etc.
3043 This is the main reason we check for zombie leaders
3046 #2 - The whole thread-group/process exited (a group exit,
3047 via e.g. exit(3), and there is (or will be shortly) an
3048 exit reported for each thread in the process, and then
3049 finally an exit for the leader once the non-leaders are
3052 #3 - There are 3 or more threads in the group, and a
3053 thread other than the leader exec'd. See comments on
3054 exec events at the top of the file.
3056 Ideally we would never delete the leader for case #2.
3057 Instead, we want to collect the exit status of each
3058 non-leader thread, and then finally collect the exit
3059 status of the leader as normal and use its exit code as
3060 whole-process exit code. Unfortunately, there's no
3061 race-free way to distinguish cases #1 and #2. We can't
3062 assume the exit events for the non-leaders threads are
3063 already pending in the kernel, nor can we assume the
3064 non-leader threads are in zombie state already. Between
3065 the leader becoming zombie and the non-leaders exiting
3066 and becoming zombie themselves, there's a small time
3067 window, so such a check would be racy. Temporarily
3068 pausing all threads and checking to see if all threads
3069 exit or not before re-resuming them would work in the
3070 case that all threads are running right now, but it
3071 wouldn't work if some thread is currently already
3072 ptrace-stopped, e.g., due to scheduler-locking.
3074 So what we do is we delete the leader anyhow, and then
3075 later on when we see its exit status, we re-add it back.
3076 We also make sure that we only report a whole-process
3077 exit when we see the leader exiting, as opposed to when
3078 the last LWP in the LWP list exits, which can be a
3079 non-leader if we deleted the leader here. */
3080 linux_nat_debug_printf ("Thread group leader %d zombie "
3081 "(it exited, or another thread execd), "
3084 exit_lwp (leader_lp
);
3089 /* Convenience function that is called when the kernel reports an exit
3090 event. This decides whether to report the event to GDB as a
3091 process exit event, a thread exit event, or to suppress the
3095 filter_exit_event (struct lwp_info
*event_child
,
3096 struct target_waitstatus
*ourstatus
)
3098 ptid_t ptid
= event_child
->ptid
;
3100 if (!is_leader (event_child
))
3102 if (report_thread_events
)
3103 ourstatus
->set_thread_exited (0);
3105 ourstatus
->set_ignore ();
3107 exit_lwp (event_child
);
3114 linux_nat_wait_1 (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3115 target_wait_flags target_options
)
3118 enum resume_kind last_resume_kind
;
3119 struct lwp_info
*lp
;
3122 linux_nat_debug_printf ("enter");
3124 /* The first time we get here after starting a new inferior, we may
3125 not have added it to the LWP list yet - this is the earliest
3126 moment at which we know its PID. */
3127 if (ptid
.is_pid () && find_lwp_pid (ptid
) == nullptr)
3129 ptid_t
lwp_ptid (ptid
.pid (), ptid
.pid ());
3131 /* Upgrade the main thread's ptid. */
3132 thread_change_ptid (linux_target
, ptid
, lwp_ptid
);
3133 lp
= add_initial_lwp (lwp_ptid
);
3137 /* Make sure SIGCHLD is blocked until the sigsuspend below. */
3138 block_child_signals (&prev_mask
);
3140 /* First check if there is a LWP with a wait status pending. */
3141 lp
= iterate_over_lwps (ptid
, status_callback
);
3144 linux_nat_debug_printf ("Using pending wait status %s for %s.",
3145 status_to_str (lp
->status
).c_str (),
3146 lp
->ptid
.to_string ().c_str ());
3149 /* But if we don't find a pending event, we'll have to wait. Always
3150 pull all events out of the kernel. We'll randomly select an
3151 event LWP out of all that have events, to prevent starvation. */
3157 /* Always use -1 and WNOHANG, due to couple of a kernel/ptrace
3160 - If the thread group leader exits while other threads in the
3161 thread group still exist, waitpid(TGID, ...) hangs. That
3162 waitpid won't return an exit status until the other threads
3163 in the group are reaped.
3165 - When a non-leader thread execs, that thread just vanishes
3166 without reporting an exit (so we'd hang if we waited for it
3167 explicitly in that case). The exec event is reported to
3171 lwpid
= my_waitpid (-1, &status
, __WALL
| WNOHANG
);
3173 linux_nat_debug_printf ("waitpid(-1, ...) returned %d, %s",
3175 errno
? safe_strerror (errno
) : "ERRNO-OK");
3179 linux_nat_debug_printf ("waitpid %ld received %s",
3181 status_to_str (status
).c_str ());
3183 linux_nat_filter_event (lwpid
, status
);
3184 /* Retry until nothing comes out of waitpid. A single
3185 SIGCHLD can indicate more than one child stopped. */
3189 /* Now that we've pulled all events out of the kernel, resume
3190 LWPs that don't have an interesting event to report. */
3191 iterate_over_lwps (minus_one_ptid
,
3192 [] (struct lwp_info
*info
)
3194 return resume_stopped_resumed_lwps (info
, minus_one_ptid
);
3197 /* ... and find an LWP with a status to report to the core, if
3199 lp
= iterate_over_lwps (ptid
, status_callback
);
3203 /* Check for zombie thread group leaders. Those can't be reaped
3204 until all other threads in the thread group are. */
3205 check_zombie_leaders ();
3207 /* If there are no resumed children left, bail. We'd be stuck
3208 forever in the sigsuspend call below otherwise. */
3209 if (iterate_over_lwps (ptid
, resumed_callback
) == NULL
)
3211 linux_nat_debug_printf ("exit (no resumed LWP)");
3213 ourstatus
->set_no_resumed ();
3215 restore_child_signals_mask (&prev_mask
);
3216 return minus_one_ptid
;
3219 /* No interesting event to report to the core. */
3221 if (target_options
& TARGET_WNOHANG
)
3223 linux_nat_debug_printf ("exit (ignore)");
3225 ourstatus
->set_ignore ();
3226 restore_child_signals_mask (&prev_mask
);
3227 return minus_one_ptid
;
3230 /* We shouldn't end up here unless we want to try again. */
3231 gdb_assert (lp
== NULL
);
3233 /* Block until we get an event reported with SIGCHLD. */
3239 status
= lp
->status
;
3242 if (!target_is_non_stop_p ())
3244 /* Now stop all other LWP's ... */
3245 iterate_over_lwps (minus_one_ptid
, stop_callback
);
3247 /* ... and wait until all of them have reported back that
3248 they're no longer running. */
3249 iterate_over_lwps (minus_one_ptid
, stop_wait_callback
);
3252 /* If we're not waiting for a specific LWP, choose an event LWP from
3253 among those that have had events. Giving equal priority to all
3254 LWPs that have had events helps prevent starvation. */
3255 if (ptid
== minus_one_ptid
|| ptid
.is_pid ())
3256 select_event_lwp (ptid
, &lp
, &status
);
3258 gdb_assert (lp
!= NULL
);
3260 /* Now that we've selected our final event LWP, un-adjust its PC if
3261 it was a software breakpoint, and we can't reliably support the
3262 "stopped by software breakpoint" stop reason. */
3263 if (lp
->stop_reason
== TARGET_STOPPED_BY_SW_BREAKPOINT
3264 && !USE_SIGTRAP_SIGINFO
)
3266 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3267 struct gdbarch
*gdbarch
= regcache
->arch ();
3268 int decr_pc
= gdbarch_decr_pc_after_break (gdbarch
);
3274 pc
= regcache_read_pc (regcache
);
3275 regcache_write_pc (regcache
, pc
+ decr_pc
);
3279 /* We'll need this to determine whether to report a SIGSTOP as
3280 GDB_SIGNAL_0. Need to take a copy because resume_clear_callback
3282 last_resume_kind
= lp
->last_resume_kind
;
3284 if (!target_is_non_stop_p ())
3286 /* In all-stop, from the core's perspective, all LWPs are now
3287 stopped until a new resume action is sent over. */
3288 iterate_over_lwps (minus_one_ptid
, resume_clear_callback
);
3292 resume_clear_callback (lp
);
3295 if (linux_target
->low_status_is_event (status
))
3297 linux_nat_debug_printf ("trap ptid is %s.",
3298 lp
->ptid
.to_string ().c_str ());
3301 if (lp
->waitstatus
.kind () != TARGET_WAITKIND_IGNORE
)
3303 *ourstatus
= lp
->waitstatus
;
3304 lp
->waitstatus
.set_ignore ();
3307 *ourstatus
= host_status_to_waitstatus (status
);
3309 linux_nat_debug_printf ("exit");
3311 restore_child_signals_mask (&prev_mask
);
3313 if (last_resume_kind
== resume_stop
3314 && ourstatus
->kind () == TARGET_WAITKIND_STOPPED
3315 && WSTOPSIG (status
) == SIGSTOP
)
3317 /* A thread that has been requested to stop by GDB with
3318 target_stop, and it stopped cleanly, so report as SIG0. The
3319 use of SIGSTOP is an implementation detail. */
3320 ourstatus
->set_stopped (GDB_SIGNAL_0
);
3323 if (ourstatus
->kind () == TARGET_WAITKIND_EXITED
3324 || ourstatus
->kind () == TARGET_WAITKIND_SIGNALLED
)
3327 lp
->core
= linux_common_core_of_thread (lp
->ptid
);
3329 if (ourstatus
->kind () == TARGET_WAITKIND_EXITED
)
3330 return filter_exit_event (lp
, ourstatus
);
3335 /* Resume LWPs that are currently stopped without any pending status
3336 to report, but are resumed from the core's perspective. */
3339 resume_stopped_resumed_lwps (struct lwp_info
*lp
, const ptid_t wait_ptid
)
3343 linux_nat_debug_printf ("NOT resuming LWP %s, not stopped",
3344 lp
->ptid
.to_string ().c_str ());
3346 else if (!lp
->resumed
)
3348 linux_nat_debug_printf ("NOT resuming LWP %s, not resumed",
3349 lp
->ptid
.to_string ().c_str ());
3351 else if (lwp_status_pending_p (lp
))
3353 linux_nat_debug_printf ("NOT resuming LWP %s, has pending status",
3354 lp
->ptid
.to_string ().c_str ());
3358 struct regcache
*regcache
= get_thread_regcache (linux_target
, lp
->ptid
);
3359 struct gdbarch
*gdbarch
= regcache
->arch ();
3363 CORE_ADDR pc
= regcache_read_pc (regcache
);
3364 int leave_stopped
= 0;
3366 /* Don't bother if there's a breakpoint at PC that we'd hit
3367 immediately, and we're not waiting for this LWP. */
3368 if (!lp
->ptid
.matches (wait_ptid
))
3370 if (breakpoint_inserted_here_p (regcache
->aspace (), pc
))
3376 linux_nat_debug_printf
3377 ("resuming stopped-resumed LWP %s at %s: step=%d",
3378 lp
->ptid
.to_string ().c_str (), paddress (gdbarch
, pc
),
3381 linux_resume_one_lwp_throw (lp
, lp
->step
, GDB_SIGNAL_0
);
3384 catch (const gdb_exception_error
&ex
)
3386 if (!check_ptrace_stopped_lwp_gone (lp
))
3395 linux_nat_target::wait (ptid_t ptid
, struct target_waitstatus
*ourstatus
,
3396 target_wait_flags target_options
)
3400 linux_nat_debug_printf ("[%s], [%s]", ptid
.to_string ().c_str (),
3401 target_options_to_string (target_options
).c_str ());
3403 /* Flush the async file first. */
3404 if (target_is_async_p ())
3405 async_file_flush ();
3407 /* Resume LWPs that are currently stopped without any pending status
3408 to report, but are resumed from the core's perspective. LWPs get
3409 in this state if we find them stopping at a time we're not
3410 interested in reporting the event (target_wait on a
3411 specific_process, for example, see linux_nat_wait_1), and
3412 meanwhile the event became uninteresting. Don't bother resuming
3413 LWPs we're not going to wait for if they'd stop immediately. */
3414 if (target_is_non_stop_p ())
3415 iterate_over_lwps (minus_one_ptid
,
3416 [=] (struct lwp_info
*info
)
3418 return resume_stopped_resumed_lwps (info
, ptid
);
3421 event_ptid
= linux_nat_wait_1 (ptid
, ourstatus
, target_options
);
3423 /* If we requested any event, and something came out, assume there
3424 may be more. If we requested a specific lwp or process, also
3425 assume there may be more. */
3426 if (target_is_async_p ()
3427 && ((ourstatus
->kind () != TARGET_WAITKIND_IGNORE
3428 && ourstatus
->kind () != TARGET_WAITKIND_NO_RESUMED
)
3429 || ptid
!= minus_one_ptid
))
3438 kill_one_lwp (pid_t pid
)
3440 /* PTRACE_KILL may resume the inferior. Send SIGKILL first. */
3443 kill_lwp (pid
, SIGKILL
);
3445 if (debug_linux_nat
)
3447 int save_errno
= errno
;
3449 linux_nat_debug_printf
3450 ("kill (SIGKILL) %ld, 0, 0 (%s)", (long) pid
,
3451 save_errno
!= 0 ? safe_strerror (save_errno
) : "OK");
3454 /* Some kernels ignore even SIGKILL for processes under ptrace. */
3457 ptrace (PTRACE_KILL
, pid
, 0, 0);
3458 if (debug_linux_nat
)
3460 int save_errno
= errno
;
3462 linux_nat_debug_printf
3463 ("PTRACE_KILL %ld, 0, 0 (%s)", (long) pid
,
3464 save_errno
? safe_strerror (save_errno
) : "OK");
3468 /* Wait for an LWP to die. */
3471 kill_wait_one_lwp (pid_t pid
)
3475 /* We must make sure that there are no pending events (delayed
3476 SIGSTOPs, pending SIGTRAPs, etc.) to make sure the current
3477 program doesn't interfere with any following debugging session. */
3481 res
= my_waitpid (pid
, NULL
, __WALL
);
3482 if (res
!= (pid_t
) -1)
3484 linux_nat_debug_printf ("wait %ld received unknown.", (long) pid
);
3486 /* The Linux kernel sometimes fails to kill a thread
3487 completely after PTRACE_KILL; that goes from the stop
3488 point in do_fork out to the one in get_signal_to_deliver
3489 and waits again. So kill it again. */
3495 gdb_assert (res
== -1 && errno
== ECHILD
);
3498 /* Callback for iterate_over_lwps. */
3501 kill_callback (struct lwp_info
*lp
)
3503 kill_one_lwp (lp
->ptid
.lwp ());
3507 /* Callback for iterate_over_lwps. */
3510 kill_wait_callback (struct lwp_info
*lp
)
3512 kill_wait_one_lwp (lp
->ptid
.lwp ());
3516 /* Kill the fork children of any threads of inferior INF that are
3517 stopped at a fork event. */
3520 kill_unfollowed_fork_children (struct inferior
*inf
)
3522 for (thread_info
*thread
: inf
->non_exited_threads ())
3524 struct target_waitstatus
*ws
= &thread
->pending_follow
;
3526 if (ws
->kind () == TARGET_WAITKIND_FORKED
3527 || ws
->kind () == TARGET_WAITKIND_VFORKED
)
3529 ptid_t child_ptid
= ws
->child_ptid ();
3530 int child_pid
= child_ptid
.pid ();
3531 int child_lwp
= child_ptid
.lwp ();
3533 kill_one_lwp (child_lwp
);
3534 kill_wait_one_lwp (child_lwp
);
3536 /* Let the arch-specific native code know this process is
3538 linux_target
->low_forget_process (child_pid
);
3544 linux_nat_target::kill ()
3546 /* If we're stopped while forking and we haven't followed yet,
3547 kill the other task. We need to do this first because the
3548 parent will be sleeping if this is a vfork. */
3549 kill_unfollowed_fork_children (current_inferior ());
3551 if (forks_exist_p ())
3552 linux_fork_killall ();
3555 ptid_t ptid
= ptid_t (inferior_ptid
.pid ());
3557 /* Stop all threads before killing them, since ptrace requires
3558 that the thread is stopped to successfully PTRACE_KILL. */
3559 iterate_over_lwps (ptid
, stop_callback
);
3560 /* ... and wait until all of them have reported back that
3561 they're no longer running. */
3562 iterate_over_lwps (ptid
, stop_wait_callback
);
3564 /* Kill all LWP's ... */
3565 iterate_over_lwps (ptid
, kill_callback
);
3567 /* ... and wait until we've flushed all events. */
3568 iterate_over_lwps (ptid
, kill_wait_callback
);
3571 target_mourn_inferior (inferior_ptid
);
3575 linux_nat_target::mourn_inferior ()
3577 int pid
= inferior_ptid
.pid ();
3579 purge_lwp_list (pid
);
3581 close_proc_mem_file (pid
);
3583 if (! forks_exist_p ())
3584 /* Normal case, no other forks available. */
3585 inf_ptrace_target::mourn_inferior ();
3587 /* Multi-fork case. The current inferior_ptid has exited, but
3588 there are other viable forks to debug. Delete the exiting
3589 one and context-switch to the first available. */
3590 linux_fork_mourn_inferior ();
3592 /* Let the arch-specific native code know this process is gone. */
3593 linux_target
->low_forget_process (pid
);
3596 /* Convert a native/host siginfo object, into/from the siginfo in the
3597 layout of the inferiors' architecture. */
3600 siginfo_fixup (siginfo_t
*siginfo
, gdb_byte
*inf_siginfo
, int direction
)
3602 /* If the low target didn't do anything, then just do a straight
3604 if (!linux_target
->low_siginfo_fixup (siginfo
, inf_siginfo
, direction
))
3607 memcpy (siginfo
, inf_siginfo
, sizeof (siginfo_t
));
3609 memcpy (inf_siginfo
, siginfo
, sizeof (siginfo_t
));
3613 static enum target_xfer_status
3614 linux_xfer_siginfo (enum target_object object
,
3615 const char *annex
, gdb_byte
*readbuf
,
3616 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3617 ULONGEST
*xfered_len
)
3621 gdb_byte inf_siginfo
[sizeof (siginfo_t
)];
3623 gdb_assert (object
== TARGET_OBJECT_SIGNAL_INFO
);
3624 gdb_assert (readbuf
|| writebuf
);
3626 pid
= inferior_ptid
.lwp ();
3628 pid
= inferior_ptid
.pid ();
3630 if (offset
> sizeof (siginfo
))
3631 return TARGET_XFER_E_IO
;
3634 ptrace (PTRACE_GETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, &siginfo
);
3636 return TARGET_XFER_E_IO
;
3638 /* When GDB is built as a 64-bit application, ptrace writes into
3639 SIGINFO an object with 64-bit layout. Since debugging a 32-bit
3640 inferior with a 64-bit GDB should look the same as debugging it
3641 with a 32-bit GDB, we need to convert it. GDB core always sees
3642 the converted layout, so any read/write will have to be done
3644 siginfo_fixup (&siginfo
, inf_siginfo
, 0);
3646 if (offset
+ len
> sizeof (siginfo
))
3647 len
= sizeof (siginfo
) - offset
;
3649 if (readbuf
!= NULL
)
3650 memcpy (readbuf
, inf_siginfo
+ offset
, len
);
3653 memcpy (inf_siginfo
+ offset
, writebuf
, len
);
3655 /* Convert back to ptrace layout before flushing it out. */
3656 siginfo_fixup (&siginfo
, inf_siginfo
, 1);
3659 ptrace (PTRACE_SETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, &siginfo
);
3661 return TARGET_XFER_E_IO
;
3665 return TARGET_XFER_OK
;
3668 static enum target_xfer_status
3669 linux_nat_xfer_osdata (enum target_object object
,
3670 const char *annex
, gdb_byte
*readbuf
,
3671 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
3672 ULONGEST
*xfered_len
);
3674 static enum target_xfer_status
3675 linux_proc_xfer_memory_partial (gdb_byte
*readbuf
, const gdb_byte
*writebuf
,
3676 ULONGEST offset
, LONGEST len
, ULONGEST
*xfered_len
);
3678 enum target_xfer_status
3679 linux_nat_target::xfer_partial (enum target_object object
,
3680 const char *annex
, gdb_byte
*readbuf
,
3681 const gdb_byte
*writebuf
,
3682 ULONGEST offset
, ULONGEST len
, ULONGEST
*xfered_len
)
3684 if (object
== TARGET_OBJECT_SIGNAL_INFO
)
3685 return linux_xfer_siginfo (object
, annex
, readbuf
, writebuf
,
3686 offset
, len
, xfered_len
);
3688 /* The target is connected but no live inferior is selected. Pass
3689 this request down to a lower stratum (e.g., the executable
3691 if (object
== TARGET_OBJECT_MEMORY
&& inferior_ptid
== null_ptid
)
3692 return TARGET_XFER_EOF
;
3694 if (object
== TARGET_OBJECT_AUXV
)
3695 return memory_xfer_auxv (this, object
, annex
, readbuf
, writebuf
,
3696 offset
, len
, xfered_len
);
3698 if (object
== TARGET_OBJECT_OSDATA
)
3699 return linux_nat_xfer_osdata (object
, annex
, readbuf
, writebuf
,
3700 offset
, len
, xfered_len
);
3702 if (object
== TARGET_OBJECT_MEMORY
)
3704 /* GDB calculates all addresses in the largest possible address
3705 width. The address width must be masked before its final use
3706 by linux_proc_xfer_partial.
3708 Compare ADDR_BIT first to avoid a compiler warning on shift overflow. */
3709 int addr_bit
= gdbarch_addr_bit (target_gdbarch ());
3711 if (addr_bit
< (sizeof (ULONGEST
) * HOST_CHAR_BIT
))
3712 offset
&= ((ULONGEST
) 1 << addr_bit
) - 1;
3714 return linux_proc_xfer_memory_partial (readbuf
, writebuf
,
3715 offset
, len
, xfered_len
);
3718 return inf_ptrace_target::xfer_partial (object
, annex
, readbuf
, writebuf
,
3719 offset
, len
, xfered_len
);
3723 linux_nat_target::thread_alive (ptid_t ptid
)
3725 /* As long as a PTID is in lwp list, consider it alive. */
3726 return find_lwp_pid (ptid
) != NULL
;
3729 /* Implement the to_update_thread_list target method for this
3733 linux_nat_target::update_thread_list ()
3735 /* We add/delete threads from the list as clone/exit events are
3736 processed, so just try deleting exited threads still in the
3738 delete_exited_threads ();
3740 /* Update the processor core that each lwp/thread was last seen
3742 for (lwp_info
*lwp
: all_lwps ())
3744 /* Avoid accessing /proc if the thread hasn't run since we last
3745 time we fetched the thread's core. Accessing /proc becomes
3746 noticeably expensive when we have thousands of LWPs. */
3747 if (lwp
->core
== -1)
3748 lwp
->core
= linux_common_core_of_thread (lwp
->ptid
);
3753 linux_nat_target::pid_to_str (ptid_t ptid
)
3756 && (ptid
.pid () != ptid
.lwp ()
3757 || num_lwps (ptid
.pid ()) > 1))
3758 return string_printf ("LWP %ld", ptid
.lwp ());
3760 return normal_pid_to_str (ptid
);
3764 linux_nat_target::thread_name (struct thread_info
*thr
)
3766 return linux_proc_tid_get_name (thr
->ptid
);
3769 /* Accepts an integer PID; Returns a string representing a file that
3770 can be opened to get the symbols for the child process. */
3773 linux_nat_target::pid_to_exec_file (int pid
)
3775 return linux_proc_pid_to_exec_file (pid
);
3778 /* Object representing an /proc/PID/mem open file. We keep one such
3779 file open per inferior.
3781 It might be tempting to think about only ever opening one file at
3782 most for all inferiors, closing/reopening the file as we access
3783 memory of different inferiors, to minimize number of file
3784 descriptors open, which can otherwise run into resource limits.
3785 However, that does not work correctly -- if the inferior execs and
3786 we haven't processed the exec event yet, and, we opened a
3787 /proc/PID/mem file, we will get a mem file accessing the post-exec
3788 address space, thinking we're opening it for the pre-exec address
3789 space. That is dangerous as we can poke memory (e.g. clearing
3790 breakpoints) in the post-exec memory by mistake, corrupting the
3791 inferior. For that reason, we open the mem file as early as
3792 possible, right after spawning, forking or attaching to the
3793 inferior, when the inferior is stopped and thus before it has a
3796 Note that after opening the file, even if the thread we opened it
3797 for subsequently exits, the open file is still usable for accessing
3798 memory. It's only when the whole process exits or execs that the
3799 file becomes invalid, at which point reads/writes return EOF. */
3804 proc_mem_file (ptid_t ptid
, int fd
)
3805 : m_ptid (ptid
), m_fd (fd
)
3807 gdb_assert (m_fd
!= -1);
3812 linux_nat_debug_printf ("closing fd %d for /proc/%d/task/%ld/mem",
3813 m_fd
, m_ptid
.pid (), m_ptid
.lwp ());
3817 DISABLE_COPY_AND_ASSIGN (proc_mem_file
);
3825 /* The LWP this file was opened for. Just for debugging
3829 /* The file descriptor. */
3833 /* The map between an inferior process id, and the open /proc/PID/mem
3834 file. This is stored in a map instead of in a per-inferior
3835 structure because we need to be able to access memory of processes
3836 which don't have a corresponding struct inferior object. E.g.,
3837 with "detach-on-fork on" (the default), and "follow-fork parent"
3838 (also default), we don't create an inferior for the fork child, but
3839 we still need to remove breakpoints from the fork child's
3841 static std::unordered_map
<int, proc_mem_file
> proc_mem_file_map
;
3843 /* Close the /proc/PID/mem file for PID. */
3846 close_proc_mem_file (pid_t pid
)
3848 proc_mem_file_map
.erase (pid
);
3851 /* Open the /proc/PID/mem file for the process (thread group) of PTID.
3852 We actually open /proc/PID/task/LWP/mem, as that's the LWP we know
3853 exists and is stopped right now. We prefer the
3854 /proc/PID/task/LWP/mem form over /proc/LWP/mem to avoid tid-reuse
3855 races, just in case this is ever called on an already-waited
3859 open_proc_mem_file (ptid_t ptid
)
3861 auto iter
= proc_mem_file_map
.find (ptid
.pid ());
3862 gdb_assert (iter
== proc_mem_file_map
.end ());
3865 xsnprintf (filename
, sizeof filename
,
3866 "/proc/%d/task/%ld/mem", ptid
.pid (), ptid
.lwp ());
3868 int fd
= gdb_open_cloexec (filename
, O_RDWR
| O_LARGEFILE
, 0).release ();
3872 warning (_("opening /proc/PID/mem file for lwp %d.%ld failed: %s (%d)"),
3873 ptid
.pid (), ptid
.lwp (),
3874 safe_strerror (errno
), errno
);
3878 proc_mem_file_map
.emplace (std::piecewise_construct
,
3879 std::forward_as_tuple (ptid
.pid ()),
3880 std::forward_as_tuple (ptid
, fd
));
3882 linux_nat_debug_printf ("opened fd %d for lwp %d.%ld",
3883 fd
, ptid
.pid (), ptid
.lwp ());
3886 /* Helper for linux_proc_xfer_memory_partial and
3887 proc_mem_file_is_writable. FD is the already opened /proc/pid/mem
3888 file, and PID is the pid of the corresponding process. The rest of
3889 the arguments are like linux_proc_xfer_memory_partial's. */
3891 static enum target_xfer_status
3892 linux_proc_xfer_memory_partial_fd (int fd
, int pid
,
3893 gdb_byte
*readbuf
, const gdb_byte
*writebuf
,
3894 ULONGEST offset
, LONGEST len
,
3895 ULONGEST
*xfered_len
)
3899 gdb_assert (fd
!= -1);
3901 /* Use pread64/pwrite64 if available, since they save a syscall and can
3902 handle 64-bit offsets even on 32-bit platforms (for instance, SPARC
3903 debugging a SPARC64 application). */
3905 ret
= (readbuf
? pread64 (fd
, readbuf
, len
, offset
)
3906 : pwrite64 (fd
, writebuf
, len
, offset
));
3908 ret
= lseek (fd
, offset
, SEEK_SET
);
3910 ret
= (readbuf
? read (fd
, readbuf
, len
)
3911 : write (fd
, writebuf
, len
));
3916 linux_nat_debug_printf ("accessing fd %d for pid %d failed: %s (%d)",
3917 fd
, pid
, safe_strerror (errno
), errno
);
3918 return TARGET_XFER_E_IO
;
3922 /* EOF means the address space is gone, the whole process exited
3924 linux_nat_debug_printf ("accessing fd %d for pid %d got EOF",
3926 return TARGET_XFER_EOF
;
3931 return TARGET_XFER_OK
;
3935 /* Implement the to_xfer_partial target method using /proc/PID/mem.
3936 Because we can use a single read/write call, this can be much more
3937 efficient than banging away at PTRACE_PEEKTEXT. Also, unlike
3938 PTRACE_PEEKTEXT/PTRACE_POKETEXT, this works with running
3941 static enum target_xfer_status
3942 linux_proc_xfer_memory_partial (gdb_byte
*readbuf
, const gdb_byte
*writebuf
,
3943 ULONGEST offset
, LONGEST len
,
3944 ULONGEST
*xfered_len
)
3946 int pid
= inferior_ptid
.pid ();
3948 auto iter
= proc_mem_file_map
.find (pid
);
3949 if (iter
== proc_mem_file_map
.end ())
3950 return TARGET_XFER_EOF
;
3952 int fd
= iter
->second
.fd ();
3954 return linux_proc_xfer_memory_partial_fd (fd
, pid
, readbuf
, writebuf
, offset
,
3958 /* Check whether /proc/pid/mem is writable in the current kernel, and
3959 return true if so. It wasn't writable before Linux 2.6.39, but
3960 there's no way to know whether the feature was backported to older
3961 kernels. So we check to see if it works. The result is cached,
3962 and this is garanteed to be called once early at startup. */
3965 proc_mem_file_is_writable ()
3967 static gdb::optional
<bool> writable
;
3969 if (writable
.has_value ())
3972 writable
.emplace (false);
3974 /* We check whether /proc/pid/mem is writable by trying to write to
3975 one of our variables via /proc/self/mem. */
3977 int fd
= gdb_open_cloexec ("/proc/self/mem", O_RDWR
| O_LARGEFILE
, 0).release ();
3981 warning (_("opening /proc/self/mem file failed: %s (%d)"),
3982 safe_strerror (errno
), errno
);
3986 SCOPE_EXIT
{ close (fd
); };
3988 /* This is the variable we try to write to. Note OFFSET below. */
3989 volatile gdb_byte test_var
= 0;
3991 gdb_byte writebuf
[] = {0x55};
3992 ULONGEST offset
= (uintptr_t) &test_var
;
3993 ULONGEST xfered_len
;
3995 enum target_xfer_status res
3996 = linux_proc_xfer_memory_partial_fd (fd
, getpid (), nullptr, writebuf
,
3997 offset
, 1, &xfered_len
);
3999 if (res
== TARGET_XFER_OK
)
4001 gdb_assert (xfered_len
== 1);
4002 gdb_assert (test_var
== 0x55);
4010 /* Parse LINE as a signal set and add its set bits to SIGS. */
4013 add_line_to_sigset (const char *line
, sigset_t
*sigs
)
4015 int len
= strlen (line
) - 1;
4019 if (line
[len
] != '\n')
4020 error (_("Could not parse signal set: %s"), line
);
4028 if (*p
>= '0' && *p
<= '9')
4030 else if (*p
>= 'a' && *p
<= 'f')
4031 digit
= *p
- 'a' + 10;
4033 error (_("Could not parse signal set: %s"), line
);
4038 sigaddset (sigs
, signum
+ 1);
4040 sigaddset (sigs
, signum
+ 2);
4042 sigaddset (sigs
, signum
+ 3);
4044 sigaddset (sigs
, signum
+ 4);
4050 /* Find process PID's pending signals from /proc/pid/status and set
4054 linux_proc_pending_signals (int pid
, sigset_t
*pending
,
4055 sigset_t
*blocked
, sigset_t
*ignored
)
4057 char buffer
[PATH_MAX
], fname
[PATH_MAX
];
4059 sigemptyset (pending
);
4060 sigemptyset (blocked
);
4061 sigemptyset (ignored
);
4062 xsnprintf (fname
, sizeof fname
, "/proc/%d/status", pid
);
4063 gdb_file_up procfile
= gdb_fopen_cloexec (fname
, "r");
4064 if (procfile
== NULL
)
4065 error (_("Could not open %s"), fname
);
4067 while (fgets (buffer
, PATH_MAX
, procfile
.get ()) != NULL
)
4069 /* Normal queued signals are on the SigPnd line in the status
4070 file. However, 2.6 kernels also have a "shared" pending
4071 queue for delivering signals to a thread group, so check for
4074 Unfortunately some Red Hat kernels include the shared pending
4075 queue but not the ShdPnd status field. */
4077 if (startswith (buffer
, "SigPnd:\t"))
4078 add_line_to_sigset (buffer
+ 8, pending
);
4079 else if (startswith (buffer
, "ShdPnd:\t"))
4080 add_line_to_sigset (buffer
+ 8, pending
);
4081 else if (startswith (buffer
, "SigBlk:\t"))
4082 add_line_to_sigset (buffer
+ 8, blocked
);
4083 else if (startswith (buffer
, "SigIgn:\t"))
4084 add_line_to_sigset (buffer
+ 8, ignored
);
4088 static enum target_xfer_status
4089 linux_nat_xfer_osdata (enum target_object object
,
4090 const char *annex
, gdb_byte
*readbuf
,
4091 const gdb_byte
*writebuf
, ULONGEST offset
, ULONGEST len
,
4092 ULONGEST
*xfered_len
)
4094 gdb_assert (object
== TARGET_OBJECT_OSDATA
);
4096 *xfered_len
= linux_common_xfer_osdata (annex
, readbuf
, offset
, len
);
4097 if (*xfered_len
== 0)
4098 return TARGET_XFER_EOF
;
4100 return TARGET_XFER_OK
;
4103 std::vector
<static_tracepoint_marker
>
4104 linux_nat_target::static_tracepoint_markers_by_strid (const char *strid
)
4106 char s
[IPA_CMD_BUF_SIZE
];
4107 int pid
= inferior_ptid
.pid ();
4108 std::vector
<static_tracepoint_marker
> markers
;
4110 ptid_t ptid
= ptid_t (pid
, 0);
4111 static_tracepoint_marker marker
;
4116 memcpy (s
, "qTfSTM", sizeof ("qTfSTM"));
4117 s
[sizeof ("qTfSTM")] = 0;
4119 agent_run_command (pid
, s
, strlen (s
) + 1);
4122 SCOPE_EXIT
{ target_continue_no_signal (ptid
); };
4128 parse_static_tracepoint_marker_definition (p
, &p
, &marker
);
4130 if (strid
== NULL
|| marker
.str_id
== strid
)
4131 markers
.push_back (std::move (marker
));
4133 while (*p
++ == ','); /* comma-separated list */
4135 memcpy (s
, "qTsSTM", sizeof ("qTsSTM"));
4136 s
[sizeof ("qTsSTM")] = 0;
4137 agent_run_command (pid
, s
, strlen (s
) + 1);
4144 /* target_can_async_p implementation. */
4147 linux_nat_target::can_async_p ()
4149 /* This flag should be checked in the common target.c code. */
4150 gdb_assert (target_async_permitted
);
4152 /* Otherwise, this targets is always able to support async mode. */
4157 linux_nat_target::supports_non_stop ()
4162 /* to_always_non_stop_p implementation. */
4165 linux_nat_target::always_non_stop_p ()
4171 linux_nat_target::supports_multi_process ()
4177 linux_nat_target::supports_disable_randomization ()
4182 /* SIGCHLD handler that serves two purposes: In non-stop/async mode,
4183 so we notice when any child changes state, and notify the
4184 event-loop; it allows us to use sigsuspend in linux_nat_wait_1
4185 above to wait for the arrival of a SIGCHLD. */
4188 sigchld_handler (int signo
)
4190 int old_errno
= errno
;
4192 if (debug_linux_nat
)
4193 gdb_stdlog
->write_async_safe ("sigchld\n", sizeof ("sigchld\n") - 1);
4195 if (signo
== SIGCHLD
)
4197 /* Let the event loop know that there are events to handle. */
4198 linux_nat_target::async_file_mark_if_open ();
4204 /* Callback registered with the target events file descriptor. */
4207 handle_target_event (int error
, gdb_client_data client_data
)
4209 inferior_event_handler (INF_REG_EVENT
);
4212 /* target_async implementation. */
4215 linux_nat_target::async (bool enable
)
4217 if (enable
== is_async_p ())
4220 /* Block child signals while we create/destroy the pipe, as their
4221 handler writes to it. */
4222 gdb::block_signals blocker
;
4226 if (!async_file_open ())
4227 internal_error (__FILE__
, __LINE__
, "creating event pipe failed.");
4229 add_file_handler (async_wait_fd (), handle_target_event
, NULL
,
4232 /* There may be pending events to handle. Tell the event loop
4238 delete_file_handler (async_wait_fd ());
4239 async_file_close ();
4243 /* Stop an LWP, and push a GDB_SIGNAL_0 stop status if no other
4247 linux_nat_stop_lwp (struct lwp_info
*lwp
)
4251 linux_nat_debug_printf ("running -> suspending %s",
4252 lwp
->ptid
.to_string ().c_str ());
4255 if (lwp
->last_resume_kind
== resume_stop
)
4257 linux_nat_debug_printf ("already stopping LWP %ld at GDB's request",
4262 stop_callback (lwp
);
4263 lwp
->last_resume_kind
= resume_stop
;
4267 /* Already known to be stopped; do nothing. */
4269 if (debug_linux_nat
)
4271 if (find_thread_ptid (linux_target
, lwp
->ptid
)->stop_requested
)
4272 linux_nat_debug_printf ("already stopped/stop_requested %s",
4273 lwp
->ptid
.to_string ().c_str ());
4275 linux_nat_debug_printf ("already stopped/no stop_requested yet %s",
4276 lwp
->ptid
.to_string ().c_str ());
4283 linux_nat_target::stop (ptid_t ptid
)
4285 LINUX_NAT_SCOPED_DEBUG_ENTER_EXIT
;
4286 iterate_over_lwps (ptid
, linux_nat_stop_lwp
);
4289 /* When requests are passed down from the linux-nat layer to the
4290 single threaded inf-ptrace layer, ptids of (lwpid,0,0) form are
4291 used. The address space pointer is stored in the inferior object,
4292 but the common code that is passed such ptid can't tell whether
4293 lwpid is a "main" process id or not (it assumes so). We reverse
4294 look up the "main" process id from the lwp here. */
4296 struct address_space
*
4297 linux_nat_target::thread_address_space (ptid_t ptid
)
4299 struct lwp_info
*lwp
;
4300 struct inferior
*inf
;
4303 if (ptid
.lwp () == 0)
4305 /* An (lwpid,0,0) ptid. Look up the lwp object to get at the
4307 lwp
= find_lwp_pid (ptid
);
4308 pid
= lwp
->ptid
.pid ();
4312 /* A (pid,lwpid,0) ptid. */
4316 inf
= find_inferior_pid (this, pid
);
4317 gdb_assert (inf
!= NULL
);
4321 /* Return the cached value of the processor core for thread PTID. */
4324 linux_nat_target::core_of_thread (ptid_t ptid
)
4326 struct lwp_info
*info
= find_lwp_pid (ptid
);
4333 /* Implementation of to_filesystem_is_local. */
4336 linux_nat_target::filesystem_is_local ()
4338 struct inferior
*inf
= current_inferior ();
4340 if (inf
->fake_pid_p
|| inf
->pid
== 0)
4343 return linux_ns_same (inf
->pid
, LINUX_NS_MNT
);
4346 /* Convert the INF argument passed to a to_fileio_* method
4347 to a process ID suitable for passing to its corresponding
4348 linux_mntns_* function. If INF is non-NULL then the
4349 caller is requesting the filesystem seen by INF. If INF
4350 is NULL then the caller is requesting the filesystem seen
4351 by the GDB. We fall back to GDB's filesystem in the case
4352 that INF is non-NULL but its PID is unknown. */
4355 linux_nat_fileio_pid_of (struct inferior
*inf
)
4357 if (inf
== NULL
|| inf
->fake_pid_p
|| inf
->pid
== 0)
4363 /* Implementation of to_fileio_open. */
4366 linux_nat_target::fileio_open (struct inferior
*inf
, const char *filename
,
4367 int flags
, int mode
, int warn_if_slow
,
4374 if (fileio_to_host_openflags (flags
, &nat_flags
) == -1
4375 || fileio_to_host_mode (mode
, &nat_mode
) == -1)
4377 *target_errno
= FILEIO_EINVAL
;
4381 fd
= linux_mntns_open_cloexec (linux_nat_fileio_pid_of (inf
),
4382 filename
, nat_flags
, nat_mode
);
4384 *target_errno
= host_to_fileio_error (errno
);
4389 /* Implementation of to_fileio_readlink. */
4391 gdb::optional
<std::string
>
4392 linux_nat_target::fileio_readlink (struct inferior
*inf
, const char *filename
,
4398 len
= linux_mntns_readlink (linux_nat_fileio_pid_of (inf
),
4399 filename
, buf
, sizeof (buf
));
4402 *target_errno
= host_to_fileio_error (errno
);
4406 return std::string (buf
, len
);
4409 /* Implementation of to_fileio_unlink. */
4412 linux_nat_target::fileio_unlink (struct inferior
*inf
, const char *filename
,
4417 ret
= linux_mntns_unlink (linux_nat_fileio_pid_of (inf
),
4420 *target_errno
= host_to_fileio_error (errno
);
4425 /* Implementation of the to_thread_events method. */
4428 linux_nat_target::thread_events (int enable
)
4430 report_thread_events
= enable
;
4433 linux_nat_target::linux_nat_target ()
4435 /* We don't change the stratum; this target will sit at
4436 process_stratum and thread_db will set at thread_stratum. This
4437 is a little strange, since this is a multi-threaded-capable
4438 target, but we want to be on the stack below thread_db, and we
4439 also want to be used for single-threaded processes. */
4442 /* See linux-nat.h. */
4445 linux_nat_get_siginfo (ptid_t ptid
, siginfo_t
*siginfo
)
4454 ptrace (PTRACE_GETSIGINFO
, pid
, (PTRACE_TYPE_ARG3
) 0, siginfo
);
4457 memset (siginfo
, 0, sizeof (*siginfo
));
4463 /* See nat/linux-nat.h. */
4466 current_lwp_ptid (void)
4468 gdb_assert (inferior_ptid
.lwp_p ());
4469 return inferior_ptid
;
4472 void _initialize_linux_nat ();
4474 _initialize_linux_nat ()
4476 add_setshow_boolean_cmd ("linux-nat", class_maintenance
,
4477 &debug_linux_nat
, _("\
4478 Set debugging of GNU/Linux native target."), _(" \
4479 Show debugging of GNU/Linux native target."), _(" \
4480 When on, print debug messages relating to the GNU/Linux native target."),
4482 show_debug_linux_nat
,
4483 &setdebuglist
, &showdebuglist
);
4485 add_setshow_boolean_cmd ("linux-namespaces", class_maintenance
,
4486 &debug_linux_namespaces
, _("\
4487 Set debugging of GNU/Linux namespaces module."), _("\
4488 Show debugging of GNU/Linux namespaces module."), _("\
4489 Enables printf debugging output."),
4492 &setdebuglist
, &showdebuglist
);
4494 /* Install a SIGCHLD handler. */
4495 sigchld_action
.sa_handler
= sigchld_handler
;
4496 sigemptyset (&sigchld_action
.sa_mask
);
4497 sigchld_action
.sa_flags
= SA_RESTART
;
4499 /* Make it the default. */
4500 sigaction (SIGCHLD
, &sigchld_action
, NULL
);
4502 /* Make sure we don't block SIGCHLD during a sigsuspend. */
4503 gdb_sigmask (SIG_SETMASK
, NULL
, &suspend_mask
);
4504 sigdelset (&suspend_mask
, SIGCHLD
);
4506 sigemptyset (&blocked_mask
);
4508 lwp_lwpid_htab_create ();
4510 proc_mem_file_is_writable ();
4514 /* FIXME: kettenis/2000-08-26: The stuff on this page is specific to
4515 the GNU/Linux Threads library and therefore doesn't really belong
4518 /* NPTL reserves the first two RT signals, but does not provide any
4519 way for the debugger to query the signal numbers - fortunately
4520 they don't change. */
4521 static int lin_thread_signals
[] = { __SIGRTMIN
, __SIGRTMIN
+ 1 };
4523 /* See linux-nat.h. */
4526 lin_thread_get_thread_signal_num (void)
4528 return sizeof (lin_thread_signals
) / sizeof (lin_thread_signals
[0]);
4531 /* See linux-nat.h. */
4534 lin_thread_get_thread_signal (unsigned int i
)
4536 gdb_assert (i
< lin_thread_get_thread_signal_num ());
4537 return lin_thread_signals
[i
];