blob: d2a529ae6d40216237e6390fffff05ad05f7738c [file] [log] [blame]
/* GNU/Linux native-dependent code common to multiple platforms.
Copyright (C) 2001-2012 Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include "defs.h"
#include "inferior.h"
#include "target.h"
#include "gdb_string.h"
#include "gdb_wait.h"
#include "gdb_assert.h"
#ifdef HAVE_TKILL_SYSCALL
#include <unistd.h>
#include <sys/syscall.h>
#endif
#include <sys/ptrace.h>
#include "linux-nat.h"
#include "linux-ptrace.h"
#include "linux-procfs.h"
#include "linux-fork.h"
#include "gdbthread.h"
#include "gdbcmd.h"
#include "regcache.h"
#include "regset.h"
#include "inf-child.h"
#include "inf-ptrace.h"
#include "auxv.h"
#include <sys/param.h> /* for MAXPATHLEN */
#include <sys/procfs.h> /* for elf_gregset etc. */
#include "elf-bfd.h" /* for elfcore_write_* */
#include "gregset.h" /* for gregset */
#include "gdbcore.h" /* for get_exec_file */
#include <ctype.h> /* for isdigit */
#include "gdbthread.h" /* for struct thread_info etc. */
#include "gdb_stat.h" /* for struct stat */
#include <fcntl.h> /* for O_RDONLY */
#include "inf-loop.h"
#include "event-loop.h"
#include "event-top.h"
#include <pwd.h>
#include <sys/types.h>
#include "gdb_dirent.h"
#include "xml-support.h"
#include "terminal.h"
#include <sys/vfs.h>
#include "solib.h"
#include "linux-osdata.h"
#include "linux-tdep.h"
#include "symfile.h"
#include "agent.h"
#include "tracepoint.h"
#include "exceptions.h"
#include "linux-ptrace.h"
#include "buffer.h"
#ifndef SPUFS_MAGIC
#define SPUFS_MAGIC 0x23c9b64e
#endif
#ifdef HAVE_PERSONALITY
# include <sys/personality.h>
# if !HAVE_DECL_ADDR_NO_RANDOMIZE
# define ADDR_NO_RANDOMIZE 0x0040000
# endif
#endif /* HAVE_PERSONALITY */
/* This comment documents high-level logic of this file.
Waiting for events in sync mode
===============================
When waiting for an event in a specific thread, we just use waitpid, passing
the specific pid, and not passing WNOHANG.
When waiting for an event in all threads, waitpid is not quite good. Prior to
version 2.4, Linux can either wait for event in main thread, or in secondary
threads. (2.4 has the __WALL flag). So, if we use blocking waitpid, we might
miss an event. The solution is to use non-blocking waitpid, together with
sigsuspend. First, we use non-blocking waitpid to get an event in the main
process, if any. Second, we use non-blocking waitpid with the __WCLONED
flag to check for events in cloned processes. If nothing is found, we use
sigsuspend to wait for SIGCHLD. When SIGCHLD arrives, it means something
happened to a child process -- and SIGCHLD will be delivered both for events
in main debugged process and in cloned processes. As soon as we know there's
an event, we get back to calling nonblocking waitpid with and without
__WCLONED.
Note that SIGCHLD should be blocked between waitpid and sigsuspend calls,
so that we don't miss a signal. If SIGCHLD arrives in between, when it's
blocked, the signal becomes pending and sigsuspend immediately
notices it and returns.
Waiting for events in async mode
================================
In async mode, GDB should always be ready to handle both user input
and target events, so neither blocking waitpid nor sigsuspend are
viable options. Instead, we should asynchronously notify the GDB main
event loop whenever there's an unprocessed event from the target. We
detect asynchronous target events by handling SIGCHLD signals. To
notify the event loop about target events, the self-pipe trick is used
--- a pipe is registered as waitable event source in the event loop,
the event loop select/poll's on the read end of this pipe (as well on
other event sources, e.g., stdin), and the SIGCHLD handler writes a
byte to this pipe. This is more portable than relying on
pselect/ppoll, since on kernels that lack those syscalls, libc
emulates them with select/poll+sigprocmask, and that is racy
(a.k.a. plain broken).
Obviously, if we fail to notify the event loop if there's a target
event, it's bad. OTOH, if we notify the event loop when there's no
event from the target, linux_nat_wait will detect that there's no real
event to report, and return event of type TARGET_WAITKIND_IGNORE.
This is mostly harmless, but it will waste time and is better avoided.
The main design point is that every time GDB is outside linux-nat.c,
we have a SIGCHLD handler installed that is called when something
happens to the target and notifies the GDB event loop. Whenever GDB
core decides to handle the event, and calls into linux-nat.c, we
process things as in sync mode, except that the we never block in
sigsuspend.
While processing an event, we may end up momentarily blocked in
waitpid calls. Those waitpid calls, while blocking, are guarantied to
return quickly. E.g., in all-stop mode, before reporting to the core
that an LWP hit a breakpoint, all LWPs are stopped by sending them
SIGSTOP, and synchronously waiting for the SIGSTOP to be reported.
Note that this is different from blocking indefinitely waiting for the
next event --- here, we're already handling an event.
Use of signals
==============
We stop threads by sending a SIGSTOP. The use of SIGSTOP instead of another
signal is not entirely significant; we just need for a signal to be delivered,
so that we can intercept it. SIGSTOP's advantage is that it can not be
blocked. A disadvantage is that it is not a real-time signal, so it can only
be queued once; we do not keep track of other sources of SIGSTOP.
Two other signals that can't be blocked are SIGCONT and SIGKILL. But we can't
use them, because they have special behavior when the signal is generated -
not when it is delivered. SIGCONT resumes the entire thread group and SIGKILL
kills the entire thread group.
A delivered SIGSTOP would stop the entire thread group, not just the thread we
tkill'd. But we never let the SIGSTOP be delivered; we always intercept and
cancel it (by PTRACE_CONT without passing SIGSTOP).
We could use a real-time signal instead. This would solve those problems; we
could use PTRACE_GETSIGINFO to locate the specific stop signals sent by GDB.
But we would still have to have some support for SIGSTOP, since PTRACE_ATTACH
generates it, and there are races with trying to find a signal that is not
blocked. */
#ifndef O_LARGEFILE
#define O_LARGEFILE 0
#endif
/* Unlike other extended result codes, WSTOPSIG (status) on
PTRACE_O_TRACESYSGOOD syscall events doesn't return SIGTRAP, but
instead SIGTRAP with bit 7 set. */
#define SYSCALL_SIGTRAP (SIGTRAP | 0x80)
/* The single-threaded native GNU/Linux target_ops. We save a pointer for
the use of the multi-threaded target. */
static struct target_ops *linux_ops;
static struct target_ops linux_ops_saved;
/* The method to call, if any, when a new thread is attached. */
static void (*linux_nat_new_thread) (struct lwp_info *);
/* Hook to call prior to resuming a thread. */
static void (*linux_nat_prepare_to_resume) (struct lwp_info *);
/* The method to call, if any, when the siginfo object needs to be
converted between the layout returned by ptrace, and the layout in
the architecture of the inferior. */
static int (*linux_nat_siginfo_fixup) (siginfo_t *,
gdb_byte *,
int);
/* The saved to_xfer_partial method, inherited from inf-ptrace.c.
Called by our to_xfer_partial. */
static LONGEST (*super_xfer_partial) (struct target_ops *,
enum target_object,
const char *, gdb_byte *,
const gdb_byte *,
ULONGEST, LONGEST);
static int debug_linux_nat;
static void
show_debug_linux_nat (struct ui_file *file, int from_tty,
struct cmd_list_element *c, const char *value)
{
fprintf_filtered (file, _("Debugging of GNU/Linux lwp module is %s.\n"),
value);
}
struct simple_pid_list
{
int pid;
int status;
struct simple_pid_list *next;
};
struct simple_pid_list *stopped_pids;
/* This variable is a tri-state flag: -1 for unknown, 0 if PTRACE_O_TRACEFORK
can not be used, 1 if it can. */
static int linux_supports_tracefork_flag = -1;
/* This variable is a tri-state flag: -1 for unknown, 0 if
PTRACE_O_TRACESYSGOOD can not be used, 1 if it can. */
static int linux_supports_tracesysgood_flag = -1;
/* If we have PTRACE_O_TRACEFORK, this flag indicates whether we also have
PTRACE_O_TRACEVFORKDONE. */
static int linux_supports_tracevforkdone_flag = -1;
/* Stores the current used ptrace() options. */
static int current_ptrace_options = 0;
/* Async mode support. */
/* The read/write ends of the pipe registered as waitable file in the
event loop. */
static int linux_nat_event_pipe[2] = { -1, -1 };
/* Flush the event pipe. */
static void
async_file_flush (void)
{
int ret;
char buf;
do
{
ret = read (linux_nat_event_pipe[0], &buf, 1);
}
while (ret >= 0 || (ret == -1 && errno == EINTR));
}
/* Put something (anything, doesn't matter what, or how much) in event
pipe, so that the select/poll in the event-loop realizes we have
something to process. */
static void
async_file_mark (void)
{
int ret;
/* It doesn't really matter what the pipe contains, as long we end
up with something in it. Might as well flush the previous
left-overs. */
async_file_flush ();
do
{
ret = write (linux_nat_event_pipe[1], "+", 1);
}
while (ret == -1 && errno == EINTR);
/* Ignore EAGAIN. If the pipe is full, the event loop will already
be awakened anyway. */
}
static void linux_nat_async (void (*callback)
(enum inferior_event_type event_type,
void *context),
void *context);
static int kill_lwp (int lwpid, int signo);
static int stop_callback (struct lwp_info *lp, void *data);
static void block_child_signals (sigset_t *prev_mask);
static void restore_child_signals_mask (sigset_t *prev_mask);
struct lwp_info;
static struct lwp_info *add_lwp (ptid_t ptid);
static void purge_lwp_list (int pid);
static void delete_lwp (ptid_t ptid);
static struct lwp_info *find_lwp_pid (ptid_t ptid);
/* Trivial list manipulation functions to keep track of a list of
new stopped processes. */
static void
add_to_pid_list (struct simple_pid_list **listp, int pid, int status)
{
struct simple_pid_list *new_pid = xmalloc (sizeof (struct simple_pid_list));
new_pid->pid = pid;
new_pid->status = status;
new_pid->next = *listp;
*listp = new_pid;
}
static int
in_pid_list_p (struct simple_pid_list *list, int pid)
{
struct simple_pid_list *p;
for (p = list; p != NULL; p = p->next)
if (p->pid == pid)
return 1;
return 0;
}
static int
pull_pid_from_list (struct simple_pid_list **listp, int pid, int *statusp)
{
struct simple_pid_list **p;
for (p = listp; *p != NULL; p = &(*p)->next)
if ((*p)->pid == pid)
{
struct simple_pid_list *next = (*p)->next;
*statusp = (*p)->status;
xfree (*p);
*p = next;
return 1;
}
return 0;
}
/* A helper function for linux_test_for_tracefork, called after fork (). */
static void
linux_tracefork_child (void)
{
ptrace (PTRACE_TRACEME, 0, 0, 0);
kill (getpid (), SIGSTOP);
fork ();
_exit (0);
}
/* Wrapper function for waitpid which handles EINTR. */
static int
my_waitpid (int pid, int *statusp, int flags)
{
int ret;
do
{
ret = waitpid (pid, statusp, flags);
}
while (ret == -1 && errno == EINTR);
return ret;
}
/* Determine if PTRACE_O_TRACEFORK can be used to follow fork events.
First, we try to enable fork tracing on ORIGINAL_PID. If this fails,
we know that the feature is not available. This may change the tracing
options for ORIGINAL_PID, but we'll be setting them shortly anyway.
However, if it succeeds, we don't know for sure that the feature is
available; old versions of PTRACE_SETOPTIONS ignored unknown options. We
create a child process, attach to it, use PTRACE_SETOPTIONS to enable
fork tracing, and let it fork. If the process exits, we assume that we
can't use TRACEFORK; if we get the fork notification, and we can extract
the new child's PID, then we assume that we can. */
static void
linux_test_for_tracefork (int original_pid)
{
int child_pid, ret, status;
long second_pid;
sigset_t prev_mask;
/* We don't want those ptrace calls to be interrupted. */
block_child_signals (&prev_mask);
linux_supports_tracefork_flag = 0;
linux_supports_tracevforkdone_flag = 0;
ret = ptrace (PTRACE_SETOPTIONS, original_pid, 0, PTRACE_O_TRACEFORK);
if (ret != 0)
{
restore_child_signals_mask (&prev_mask);
return;
}
child_pid = fork ();
if (child_pid == -1)
perror_with_name (("fork"));
if (child_pid == 0)
linux_tracefork_child ();
ret = my_waitpid (child_pid, &status, 0);
if (ret == -1)
perror_with_name (("waitpid"));
else if (ret != child_pid)
error (_("linux_test_for_tracefork: waitpid: unexpected result %d."), ret);
if (! WIFSTOPPED (status))
error (_("linux_test_for_tracefork: waitpid: unexpected status %d."),
status);
ret = ptrace (PTRACE_SETOPTIONS, child_pid, 0, PTRACE_O_TRACEFORK);
if (ret != 0)
{
ret = ptrace (PTRACE_KILL, child_pid, 0, 0);
if (ret != 0)
{
warning (_("linux_test_for_tracefork: failed to kill child"));
restore_child_signals_mask (&prev_mask);
return;
}
ret = my_waitpid (child_pid, &status, 0);
if (ret != child_pid)
warning (_("linux_test_for_tracefork: failed "
"to wait for killed child"));
else if (!WIFSIGNALED (status))
warning (_("linux_test_for_tracefork: unexpected "
"wait status 0x%x from killed child"), status);
restore_child_signals_mask (&prev_mask);
return;
}
/* Check whether PTRACE_O_TRACEVFORKDONE is available. */
ret = ptrace (PTRACE_SETOPTIONS, child_pid, 0,
PTRACE_O_TRACEFORK | PTRACE_O_TRACEVFORKDONE);
linux_supports_tracevforkdone_flag = (ret == 0);
ret = ptrace (PTRACE_CONT, child_pid, 0, 0);
if (ret != 0)
warning (_("linux_test_for_tracefork: failed to resume child"));
ret = my_waitpid (child_pid, &status, 0);
if (ret == child_pid && WIFSTOPPED (status)
&& status >> 16 == PTRACE_EVENT_FORK)
{
second_pid = 0;
ret = ptrace (PTRACE_GETEVENTMSG, child_pid, 0, &second_pid);
if (ret == 0 && second_pid != 0)
{
int second_status;
linux_supports_tracefork_flag = 1;
my_waitpid (second_pid, &second_status, 0);
ret = ptrace (PTRACE_KILL, second_pid, 0, 0);
if (ret != 0)
warning (_("linux_test_for_tracefork: "
"failed to kill second child"));
my_waitpid (second_pid, &status, 0);
}
}
else
warning (_("linux_test_for_tracefork: unexpected result from waitpid "
"(%d, status 0x%x)"), ret, status);
ret = ptrace (PTRACE_KILL, child_pid, 0, 0);
if (ret != 0)
warning (_("linux_test_for_tracefork: failed to kill child"));
my_waitpid (child_pid, &status, 0);
restore_child_signals_mask (&prev_mask);
}
/* Determine if PTRACE_O_TRACESYSGOOD can be used to follow syscalls.
We try to enable syscall tracing on ORIGINAL_PID. If this fails,
we know that the feature is not available. This may change the tracing
options for ORIGINAL_PID, but we'll be setting them shortly anyway. */
static void
linux_test_for_tracesysgood (int original_pid)
{
int ret;
sigset_t prev_mask;
/* We don't want those ptrace calls to be interrupted. */
block_child_signals (&prev_mask);
linux_supports_tracesysgood_flag = 0;
ret = ptrace (PTRACE_SETOPTIONS, original_pid, 0, PTRACE_O_TRACESYSGOOD);
if (ret != 0)
goto out;
linux_supports_tracesysgood_flag = 1;
out:
restore_child_signals_mask (&prev_mask);
}
/* Determine wether we support PTRACE_O_TRACESYSGOOD option available.
This function also sets linux_supports_tracesysgood_flag. */
static int
linux_supports_tracesysgood (int pid)
{
if (linux_supports_tracesysgood_flag == -1)
linux_test_for_tracesysgood (pid);
return linux_supports_tracesysgood_flag;
}
/* Return non-zero iff we have tracefork functionality available.
This function also sets linux_supports_tracefork_flag. */
static int
linux_supports_tracefork (int pid)
{
if (linux_supports_tracefork_flag == -1)
linux_test_for_tracefork (pid);
return linux_supports_tracefork_flag;
}
static int
linux_supports_tracevforkdone (int pid)
{
if (linux_supports_tracefork_flag == -1)
linux_test_for_tracefork (pid);
return linux_supports_tracevforkdone_flag;
}
static void
linux_enable_tracesysgood (ptid_t ptid)
{
int pid = ptid_get_lwp (ptid);
if (pid == 0)
pid = ptid_get_pid (ptid);
if (linux_supports_tracesysgood (pid) == 0)
return;
current_ptrace_options |= PTRACE_O_TRACESYSGOOD;
ptrace (PTRACE_SETOPTIONS, pid, 0, current_ptrace_options);
}
void
linux_enable_event_reporting (ptid_t ptid)
{
int pid = ptid_get_lwp (ptid);
if (pid == 0)
pid = ptid_get_pid (ptid);
if (! linux_supports_tracefork (pid))
return;
current_ptrace_options |= PTRACE_O_TRACEFORK | PTRACE_O_TRACEVFORK
| PTRACE_O_TRACEEXEC | PTRACE_O_TRACECLONE;
if (linux_supports_tracevforkdone (pid))
current_ptrace_options |= PTRACE_O_TRACEVFORKDONE;
/* Do not enable PTRACE_O_TRACEEXIT until GDB is more prepared to support
read-only process state. */
ptrace (PTRACE_SETOPTIONS, pid, 0, current_ptrace_options);
}
static void
linux_child_post_attach (int pid)
{
linux_enable_event_reporting (pid_to_ptid (pid));
linux_enable_tracesysgood (pid_to_ptid (pid));
linux_ptrace_init_warnings ();
}
static void
linux_child_post_startup_inferior (ptid_t ptid)
{
linux_enable_event_reporting (ptid);
linux_enable_tracesysgood (ptid);
linux_ptrace_init_warnings ();
}
/* Return the number of known LWPs in the tgid given by PID. */
static int
num_lwps (int pid)
{
int count = 0;
struct lwp_info *lp;
for (lp = lwp_list; lp; lp = lp->next)
if (ptid_get_pid (lp->ptid) == pid)
count++;
return count;
}
/* Call delete_lwp with prototype compatible for make_cleanup. */
static void
delete_lwp_cleanup (void *lp_voidp)
{
struct lwp_info *lp = lp_voidp;
delete_lwp (lp->ptid);
}
static int
linux_child_follow_fork (struct target_ops *ops, int follow_child)
{
sigset_t prev_mask;
int has_vforked;
int parent_pid, child_pid;
block_child_signals (&prev_mask);
has_vforked = (inferior_thread ()->pending_follow.kind
== TARGET_WAITKIND_VFORKED);
parent_pid = ptid_get_lwp (inferior_ptid);
if (parent_pid == 0)
parent_pid = ptid_get_pid (inferior_ptid);
child_pid = PIDGET (inferior_thread ()->pending_follow.value.related_pid);
if (!detach_fork)
linux_enable_event_reporting (pid_to_ptid (child_pid));
if (has_vforked
&& !non_stop /* Non-stop always resumes both branches. */
&& (!target_is_async_p () || sync_execution)
&& !(follow_child || detach_fork || sched_multi))
{
/* The parent stays blocked inside the vfork syscall until the
child execs or exits. If we don't let the child run, then
the parent stays blocked. If we're telling the parent to run
in the foreground, the user will not be able to ctrl-c to get
back the terminal, effectively hanging the debug session. */
fprintf_filtered (gdb_stderr, _("\
Can not resume the parent process over vfork in the foreground while\n\
holding the child stopped. Try \"set detach-on-fork\" or \
\"set schedule-multiple\".\n"));
/* FIXME output string > 80 columns. */
return 1;
}
if (! follow_child)
{
struct lwp_info *child_lp = NULL;
/* We're already attached to the parent, by default. */
/* Detach new forked process? */
if (detach_fork)
{
struct cleanup *old_chain;
/* Before detaching from the child, remove all breakpoints
from it. If we forked, then this has already been taken
care of by infrun.c. If we vforked however, any
breakpoint inserted in the parent is visible in the
child, even those added while stopped in a vfork
catchpoint. This will remove the breakpoints from the
parent also, but they'll be reinserted below. */
if (has_vforked)
{
/* keep breakpoints list in sync. */
remove_breakpoints_pid (GET_PID (inferior_ptid));
}
if (info_verbose || debug_linux_nat)
{
target_terminal_ours ();
fprintf_filtered (gdb_stdlog,
"Detaching after fork from "
"child process %d.\n",
child_pid);
}
old_chain = save_inferior_ptid ();
inferior_ptid = ptid_build (child_pid, child_pid, 0);
child_lp = add_lwp (inferior_ptid);
child_lp->stopped = 1;
child_lp->last_resume_kind = resume_stop;
make_cleanup (delete_lwp_cleanup, child_lp);
/* CHILD_LP has new PID, therefore linux_nat_new_thread is not called for it.
See i386_inferior_data_get for the Linux kernel specifics.
Ensure linux_nat_prepare_to_resume will reset the hardware debug
registers. It is done by the linux_nat_new_thread call, which is
being skipped in add_lwp above for the first lwp of a pid. */
gdb_assert (num_lwps (GET_PID (child_lp->ptid)) == 1);
if (linux_nat_new_thread != NULL)
linux_nat_new_thread (child_lp);
if (linux_nat_prepare_to_resume != NULL)
linux_nat_prepare_to_resume (child_lp);
ptrace (PTRACE_DETACH, child_pid, 0, 0);
do_cleanups (old_chain);
}
else
{
struct inferior *parent_inf, *child_inf;
struct cleanup *old_chain;
/* Add process to GDB's tables. */
child_inf = add_inferior (child_pid);
parent_inf = current_inferior ();
child_inf->attach_flag = parent_inf->attach_flag;
copy_terminal_info (child_inf, parent_inf);
old_chain = save_inferior_ptid ();
save_current_program_space ();
inferior_ptid = ptid_build (child_pid, child_pid, 0);
add_thread (inferior_ptid);
child_lp = add_lwp (inferior_ptid);
child_lp->stopped = 1;
child_lp->last_resume_kind = resume_stop;
child_inf->symfile_flags = SYMFILE_NO_READ;
/* If this is a vfork child, then the address-space is
shared with the parent. */
if (has_vforked)
{
child_inf->pspace = parent_inf->pspace;
child_inf->aspace = parent_inf->aspace;
/* The parent will be frozen until the child is done
with the shared region. Keep track of the
parent. */
child_inf->vfork_parent = parent_inf;
child_inf->pending_detach = 0;
parent_inf->vfork_child = child_inf;
parent_inf->pending_detach = 0;
}
else
{
child_inf->aspace = new_address_space ();
child_inf->pspace = add_program_space (child_inf->aspace);
child_inf->removable = 1;
set_current_program_space (child_inf->pspace);
clone_program_space (child_inf->pspace, parent_inf->pspace);
/* Let the shared library layer (solib-svr4) learn about
this new process, relocate the cloned exec, pull in
shared libraries, and install the solib event
breakpoint. If a "cloned-VM" event was propagated
better throughout the core, this wouldn't be
required. */
solib_create_inferior_hook (0);
}
/* Let the thread_db layer learn about this new process. */
check_for_thread_db ();
do_cleanups (old_chain);
}
if (has_vforked)
{
struct lwp_info *parent_lp;
struct inferior *parent_inf;
parent_inf = current_inferior ();
/* If we detached from the child, then we have to be careful
to not insert breakpoints in the parent until the child
is done with the shared memory region. However, if we're
staying attached to the child, then we can and should
insert breakpoints, so that we can debug it. A
subsequent child exec or exit is enough to know when does
the child stops using the parent's address space. */
parent_inf->waiting_for_vfork_done = detach_fork;
parent_inf->pspace->breakpoints_not_allowed = detach_fork;
parent_lp = find_lwp_pid (pid_to_ptid (parent_pid));
gdb_assert (linux_supports_tracefork_flag >= 0);
if (linux_supports_tracevforkdone (0))
{
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"LCFF: waiting for VFORK_DONE on %d\n",
parent_pid);
parent_lp->stopped = 1;
/* We'll handle the VFORK_DONE event like any other
event, in target_wait. */
}
else
{
/* We can't insert breakpoints until the child has
finished with the shared memory region. We need to
wait until that happens. Ideal would be to just
call:
- ptrace (PTRACE_SYSCALL, parent_pid, 0, 0);
- waitpid (parent_pid, &status, __WALL);
However, most architectures can't handle a syscall
being traced on the way out if it wasn't traced on
the way in.
We might also think to loop, continuing the child
until it exits or gets a SIGTRAP. One problem is
that the child might call ptrace with PTRACE_TRACEME.
There's no simple and reliable way to figure out when
the vforked child will be done with its copy of the
shared memory. We could step it out of the syscall,
two instructions, let it go, and then single-step the
parent once. When we have hardware single-step, this
would work; with software single-step it could still
be made to work but we'd have to be able to insert
single-step breakpoints in the child, and we'd have
to insert -just- the single-step breakpoint in the
parent. Very awkward.
In the end, the best we can do is to make sure it
runs for a little while. Hopefully it will be out of
range of any breakpoints we reinsert. Usually this
is only the single-step breakpoint at vfork's return
point. */
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"LCFF: no VFORK_DONE "
"support, sleeping a bit\n");
usleep (10000);
/* Pretend we've seen a PTRACE_EVENT_VFORK_DONE event,
and leave it pending. The next linux_nat_resume call
will notice a pending event, and bypasses actually
resuming the inferior. */
parent_lp->status = 0;
parent_lp->waitstatus.kind = TARGET_WAITKIND_VFORK_DONE;
parent_lp->stopped = 1;
/* If we're in async mode, need to tell the event loop
there's something here to process. */
if (target_can_async_p ())
async_file_mark ();
}
}
}
else
{
struct inferior *parent_inf, *child_inf;
struct lwp_info *child_lp;
struct program_space *parent_pspace;
if (info_verbose || debug_linux_nat)
{
target_terminal_ours ();
if (has_vforked)
fprintf_filtered (gdb_stdlog,
_("Attaching after process %d "
"vfork to child process %d.\n"),
parent_pid, child_pid);
else
fprintf_filtered (gdb_stdlog,
_("Attaching after process %d "
"fork to child process %d.\n"),
parent_pid, child_pid);
}
/* Add the new inferior first, so that the target_detach below
doesn't unpush the target. */
child_inf = add_inferior (child_pid);
parent_inf = current_inferior ();
child_inf->attach_flag = parent_inf->attach_flag;
copy_terminal_info (child_inf, parent_inf);
parent_pspace = parent_inf->pspace;
/* If we're vforking, we want to hold on to the parent until the
child exits or execs. At child exec or exit time we can
remove the old breakpoints from the parent and detach or
resume debugging it. Otherwise, detach the parent now; we'll
want to reuse it's program/address spaces, but we can't set
them to the child before removing breakpoints from the
parent, otherwise, the breakpoints module could decide to
remove breakpoints from the wrong process (since they'd be
assigned to the same address space). */
if (has_vforked)
{
gdb_assert (child_inf->vfork_parent == NULL);
gdb_assert (parent_inf->vfork_child == NULL);
child_inf->vfork_parent = parent_inf;
child_inf->pending_detach = 0;
parent_inf->vfork_child = child_inf;
parent_inf->pending_detach = detach_fork;
parent_inf->waiting_for_vfork_done = 0;
}
else if (detach_fork)
target_detach (NULL, 0);
/* Note that the detach above makes PARENT_INF dangling. */
/* Add the child thread to the appropriate lists, and switch to
this new thread, before cloning the program space, and
informing the solib layer about this new process. */
inferior_ptid = ptid_build (child_pid, child_pid, 0);
add_thread (inferior_ptid);
child_lp = add_lwp (inferior_ptid);
child_lp->stopped = 1;
child_lp->last_resume_kind = resume_stop;
/* If this is a vfork child, then the address-space is shared
with the parent. If we detached from the parent, then we can
reuse the parent's program/address spaces. */
if (has_vforked || detach_fork)
{
child_inf->pspace = parent_pspace;
child_inf->aspace = child_inf->pspace->aspace;
}
else
{
child_inf->aspace = new_address_space ();
child_inf->pspace = add_program_space (child_inf->aspace);
child_inf->removable = 1;
child_inf->symfile_flags = SYMFILE_NO_READ;
set_current_program_space (child_inf->pspace);
clone_program_space (child_inf->pspace, parent_pspace);
/* Let the shared library layer (solib-svr4) learn about
this new process, relocate the cloned exec, pull in
shared libraries, and install the solib event breakpoint.
If a "cloned-VM" event was propagated better throughout
the core, this wouldn't be required. */
solib_create_inferior_hook (0);
}
/* Let the thread_db layer learn about this new process. */
check_for_thread_db ();
}
restore_child_signals_mask (&prev_mask);
return 0;
}
static int
linux_child_insert_fork_catchpoint (int pid)
{
return !linux_supports_tracefork (pid);
}
static int
linux_child_remove_fork_catchpoint (int pid)
{
return 0;
}
static int
linux_child_insert_vfork_catchpoint (int pid)
{
return !linux_supports_tracefork (pid);
}
static int
linux_child_remove_vfork_catchpoint (int pid)
{
return 0;
}
static int
linux_child_insert_exec_catchpoint (int pid)
{
return !linux_supports_tracefork (pid);
}
static int
linux_child_remove_exec_catchpoint (int pid)
{
return 0;
}
static int
linux_child_set_syscall_catchpoint (int pid, int needed, int any_count,
int table_size, int *table)
{
if (!linux_supports_tracesysgood (pid))
return 1;
/* On GNU/Linux, we ignore the arguments. It means that we only
enable the syscall catchpoints, but do not disable them.
Also, we do not use the `table' information because we do not
filter system calls here. We let GDB do the logic for us. */
return 0;
}
/* On GNU/Linux there are no real LWP's. The closest thing to LWP's
are processes sharing the same VM space. A multi-threaded process
is basically a group of such processes. However, such a grouping
is almost entirely a user-space issue; the kernel doesn't enforce
such a grouping at all (this might change in the future). In
general, we'll rely on the threads library (i.e. the GNU/Linux
Threads library) to provide such a grouping.
It is perfectly well possible to write a multi-threaded application
without the assistance of a threads library, by using the clone
system call directly. This module should be able to give some
rudimentary support for debugging such applications if developers
specify the CLONE_PTRACE flag in the clone system call, and are
using the Linux kernel 2.4 or above.
Note that there are some peculiarities in GNU/Linux that affect
this code:
- In general one should specify the __WCLONE flag to waitpid in
order to make it report events for any of the cloned processes
(and leave it out for the initial process). However, if a cloned
process has exited the exit status is only reported if the
__WCLONE flag is absent. Linux kernel 2.4 has a __WALL flag, but
we cannot use it since GDB must work on older systems too.
- When a traced, cloned process exits and is waited for by the
debugger, the kernel reassigns it to the original parent and
keeps it around as a "zombie". Somehow, the GNU/Linux Threads
library doesn't notice this, which leads to the "zombie problem":
When debugged a multi-threaded process that spawns a lot of
threads will run out of processes, even if the threads exit,
because the "zombies" stay around. */
/* List of known LWPs. */
struct lwp_info *lwp_list;
/* Original signal mask. */
static sigset_t normal_mask;
/* Signal mask for use with sigsuspend in linux_nat_wait, initialized in
_initialize_linux_nat. */
static sigset_t suspend_mask;
/* Signals to block to make that sigsuspend work. */
static sigset_t blocked_mask;
/* SIGCHLD action. */
struct sigaction sigchld_action;
/* Block child signals (SIGCHLD and linux threads signals), and store
the previous mask in PREV_MASK. */
static void
block_child_signals (sigset_t *prev_mask)
{
/* Make sure SIGCHLD is blocked. */
if (!sigismember (&blocked_mask, SIGCHLD))
sigaddset (&blocked_mask, SIGCHLD);
sigprocmask (SIG_BLOCK, &blocked_mask, prev_mask);
}
/* Restore child signals mask, previously returned by
block_child_signals. */
static void
restore_child_signals_mask (sigset_t *prev_mask)
{
sigprocmask (SIG_SETMASK, prev_mask, NULL);
}
/* Mask of signals to pass directly to the inferior. */
static sigset_t pass_mask;
/* Update signals to pass to the inferior. */
static void
linux_nat_pass_signals (int numsigs, unsigned char *pass_signals)
{
int signo;
sigemptyset (&pass_mask);
for (signo = 1; signo < NSIG; signo++)
{
int target_signo = gdb_signal_from_host (signo);
if (target_signo < numsigs && pass_signals[target_signo])
sigaddset (&pass_mask, signo);
}
}
/* Prototypes for local functions. */
static int stop_wait_callback (struct lwp_info *lp, void *data);
static int linux_thread_alive (ptid_t ptid);
static char *linux_child_pid_to_exec_file (int pid);
/* Convert wait status STATUS to a string. Used for printing debug
messages only. */
static char *
status_to_str (int status)
{
static char buf[64];
if (WIFSTOPPED (status))
{
if (WSTOPSIG (status) == SYSCALL_SIGTRAP)
snprintf (buf, sizeof (buf), "%s (stopped at syscall)",
strsignal (SIGTRAP));
else
snprintf (buf, sizeof (buf), "%s (stopped)",
strsignal (WSTOPSIG (status)));
}
else if (WIFSIGNALED (status))
snprintf (buf, sizeof (buf), "%s (terminated)",
strsignal (WTERMSIG (status)));
else
snprintf (buf, sizeof (buf), "%d (exited)", WEXITSTATUS (status));
return buf;
}
/* Destroy and free LP. */
static void
lwp_free (struct lwp_info *lp)
{
xfree (lp->arch_private);
xfree (lp);
}
/* Remove all LWPs belong to PID from the lwp list. */
static void
purge_lwp_list (int pid)
{
struct lwp_info *lp, *lpprev, *lpnext;
lpprev = NULL;
for (lp = lwp_list; lp; lp = lpnext)
{
lpnext = lp->next;
if (ptid_get_pid (lp->ptid) == pid)
{
if (lp == lwp_list)
lwp_list = lp->next;
else
lpprev->next = lp->next;
lwp_free (lp);
}
else
lpprev = lp;
}
}
/* Add the LWP specified by PID to the list. Return a pointer to the
structure describing the new LWP. The LWP should already be stopped
(with an exception for the very first LWP). */
static struct lwp_info *
add_lwp (ptid_t ptid)
{
struct lwp_info *lp;
gdb_assert (is_lwp (ptid));
lp = (struct lwp_info *) xmalloc (sizeof (struct lwp_info));
memset (lp, 0, sizeof (struct lwp_info));
lp->last_resume_kind = resume_continue;
lp->waitstatus.kind = TARGET_WAITKIND_IGNORE;
lp->ptid = ptid;
lp->core = -1;
lp->next = lwp_list;
lwp_list = lp;
/* Let the arch specific bits know about this new thread. Current
clients of this callback take the opportunity to install
watchpoints in the new thread. Don't do this for the first
thread though. If we're spawning a child ("run"), the thread
executes the shell wrapper first, and we shouldn't touch it until
it execs the program we want to debug. For "attach", it'd be
okay to call the callback, but it's not necessary, because
watchpoints can't yet have been inserted into the inferior. */
if (num_lwps (GET_PID (ptid)) > 1 && linux_nat_new_thread != NULL)
linux_nat_new_thread (lp);
return lp;
}
/* Remove the LWP specified by PID from the list. */
static void
delete_lwp (ptid_t ptid)
{
struct lwp_info *lp, *lpprev;
lpprev = NULL;
for (lp = lwp_list; lp; lpprev = lp, lp = lp->next)
if (ptid_equal (lp->ptid, ptid))
break;
if (!lp)
return;
if (lpprev)
lpprev->next = lp->next;
else
lwp_list = lp->next;
lwp_free (lp);
}
/* Return a pointer to the structure describing the LWP corresponding
to PID. If no corresponding LWP could be found, return NULL. */
static struct lwp_info *
find_lwp_pid (ptid_t ptid)
{
struct lwp_info *lp;
int lwp;
if (is_lwp (ptid))
lwp = GET_LWP (ptid);
else
lwp = GET_PID (ptid);
for (lp = lwp_list; lp; lp = lp->next)
if (lwp == GET_LWP (lp->ptid))
return lp;
return NULL;
}
/* Call CALLBACK with its second argument set to DATA for every LWP in
the list. If CALLBACK returns 1 for a particular LWP, return a
pointer to the structure describing that LWP immediately.
Otherwise return NULL. */
struct lwp_info *
iterate_over_lwps (ptid_t filter,
int (*callback) (struct lwp_info *, void *),
void *data)
{
struct lwp_info *lp, *lpnext;
for (lp = lwp_list; lp; lp = lpnext)
{
lpnext = lp->next;
if (ptid_match (lp->ptid, filter))
{
if ((*callback) (lp, data))
return lp;
}
}
return NULL;
}
/* Iterate like iterate_over_lwps does except when forking-off a child call
CALLBACK with CALLBACK_DATA specifically only for that new child PID. */
void
linux_nat_iterate_watchpoint_lwps
(linux_nat_iterate_watchpoint_lwps_ftype callback, void *callback_data)
{
int inferior_pid = ptid_get_pid (inferior_ptid);
struct inferior *inf = current_inferior ();
if (inf->pid == inferior_pid)
{
/* Iterate all the threads of the current inferior. Without specifying
INFERIOR_PID it would iterate all threads of all inferiors, which is
inappropriate for watchpoints. */
iterate_over_lwps (pid_to_ptid (inferior_pid), callback, callback_data);
}
else
{
/* Detaching a new child PID temporarily present in INFERIOR_PID. */
struct lwp_info *child_lp;
struct cleanup *old_chain;
pid_t child_pid = GET_PID (inferior_ptid);
ptid_t child_ptid = ptid_build (child_pid, child_pid, 0);
gdb_assert (!is_lwp (inferior_ptid));
gdb_assert (find_lwp_pid (child_ptid) == NULL);
child_lp = add_lwp (child_ptid);
child_lp->stopped = 1;
child_lp->last_resume_kind = resume_stop;
old_chain = make_cleanup (delete_lwp_cleanup, child_lp);
callback (child_lp, callback_data);
do_cleanups (old_chain);
}
}
/* Update our internal state when changing from one checkpoint to
another indicated by NEW_PTID. We can only switch single-threaded
applications, so we only create one new LWP, and the previous list
is discarded. */
void
linux_nat_switch_fork (ptid_t new_ptid)
{
struct lwp_info *lp;
purge_lwp_list (GET_PID (inferior_ptid));
lp = add_lwp (new_ptid);
lp->stopped = 1;
/* This changes the thread's ptid while preserving the gdb thread
num. Also changes the inferior pid, while preserving the
inferior num. */
thread_change_ptid (inferior_ptid, new_ptid);
/* We've just told GDB core that the thread changed target id, but,
in fact, it really is a different thread, with different register
contents. */
registers_changed ();
}
/* Handle the exit of a single thread LP. */
static void
exit_lwp (struct lwp_info *lp)
{
struct thread_info *th = find_thread_ptid (lp->ptid);
if (th)
{
if (print_thread_events)
printf_unfiltered (_("[%s exited]\n"), target_pid_to_str (lp->ptid));
delete_thread (lp->ptid);
}
delete_lwp (lp->ptid);
}
/* Wait for the LWP specified by LP, which we have just attached to.
Returns a wait status for that LWP, to cache. */
static int
linux_nat_post_attach_wait (ptid_t ptid, int first, int *cloned,
int *signalled)
{
pid_t new_pid, pid = GET_LWP (ptid);
int status;
if (linux_proc_pid_is_stopped (pid))
{
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"LNPAW: Attaching to a stopped process\n");
/* The process is definitely stopped. It is in a job control
stop, unless the kernel predates the TASK_STOPPED /
TASK_TRACED distinction, in which case it might be in a
ptrace stop. Make sure it is in a ptrace stop; from there we
can kill it, signal it, et cetera.
First make sure there is a pending SIGSTOP. Since we are
already attached, the process can not transition from stopped
to running without a PTRACE_CONT; so we know this signal will
go into the queue. The SIGSTOP generated by PTRACE_ATTACH is
probably already in the queue (unless this kernel is old
enough to use TASK_STOPPED for ptrace stops); but since SIGSTOP
is not an RT signal, it can only be queued once. */
kill_lwp (pid, SIGSTOP);
/* Finally, resume the stopped process. This will deliver the SIGSTOP
(or a higher priority signal, just like normal PTRACE_ATTACH). */
ptrace (PTRACE_CONT, pid, 0, 0);
}
/* Make sure the initial process is stopped. The user-level threads
layer might want to poke around in the inferior, and that won't
work if things haven't stabilized yet. */
new_pid = my_waitpid (pid, &status, 0);
if (new_pid == -1 && errno == ECHILD)
{
if (first)
warning (_("%s is a cloned process"), target_pid_to_str (ptid));
/* Try again with __WCLONE to check cloned processes. */
new_pid = my_waitpid (pid, &status, __WCLONE);
*cloned = 1;
}
gdb_assert (pid == new_pid);
if (!WIFSTOPPED (status))
{
/* The pid we tried to attach has apparently just exited. */
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog, "LNPAW: Failed to stop %d: %s",
pid, status_to_str (status));
return status;
}
if (WSTOPSIG (status) != SIGSTOP)
{
*signalled = 1;
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"LNPAW: Received %s after attaching\n",
status_to_str (status));
}
return status;
}
/* Attach to the LWP specified by PID. Return 0 if successful, -1 if
the new LWP could not be attached, or 1 if we're already auto
attached to this thread, but haven't processed the
PTRACE_EVENT_CLONE event of its parent thread, so we just ignore
its existance, without considering it an error. */
int
lin_lwp_attach_lwp (ptid_t ptid)
{
struct lwp_info *lp;
sigset_t prev_mask;
int lwpid;
gdb_assert (is_lwp (ptid));
block_child_signals (&prev_mask);
lp = find_lwp_pid (ptid);
lwpid = GET_LWP (ptid);
/* We assume that we're already attached to any LWP that has an id
equal to the overall process id, and to any LWP that is already
in our list of LWPs. If we're not seeing exit events from threads
and we've had PID wraparound since we last tried to stop all threads,
this assumption might be wrong; fortunately, this is very unlikely
to happen. */
if (lwpid != GET_PID (ptid) && lp == NULL)
{
int status, cloned = 0, signalled = 0;
if (ptrace (PTRACE_ATTACH, lwpid, 0, 0) < 0)
{
if (linux_supports_tracefork_flag)
{
/* If we haven't stopped all threads when we get here,
we may have seen a thread listed in thread_db's list,
but not processed the PTRACE_EVENT_CLONE yet. If
that's the case, ignore this new thread, and let
normal event handling discover it later. */
if (in_pid_list_p (stopped_pids, lwpid))
{
/* We've already seen this thread stop, but we
haven't seen the PTRACE_EVENT_CLONE extended
event yet. */
restore_child_signals_mask (&prev_mask);
return 0;
}
else
{
int new_pid;
int status;
/* See if we've got a stop for this new child
pending. If so, we're already attached. */
new_pid = my_waitpid (lwpid, &status, WNOHANG);
if (new_pid == -1 && errno == ECHILD)
new_pid = my_waitpid (lwpid, &status, __WCLONE | WNOHANG);
if (new_pid != -1)
{
if (WIFSTOPPED (status))
add_to_pid_list (&stopped_pids, lwpid, status);
restore_child_signals_mask (&prev_mask);
return 1;
}
}
}
/* If we fail to attach to the thread, issue a warning,
but continue. One way this can happen is if thread
creation is interrupted; as of Linux kernel 2.6.19, a
bug may place threads in the thread list and then fail
to create them. */
warning (_("Can't attach %s: %s"), target_pid_to_str (ptid),
safe_strerror (errno));
restore_child_signals_mask (&prev_mask);
return -1;
}
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"LLAL: PTRACE_ATTACH %s, 0, 0 (OK)\n",
target_pid_to_str (ptid));
status = linux_nat_post_attach_wait (ptid, 0, &cloned, &signalled);
if (!WIFSTOPPED (status))
{
restore_child_signals_mask (&prev_mask);
return 1;
}
lp = add_lwp (ptid);
lp->stopped = 1;
lp->cloned = cloned;
lp->signalled = signalled;
if (WSTOPSIG (status) != SIGSTOP)
{
lp->resumed = 1;
lp->status = status;
}
target_post_attach (GET_LWP (lp->ptid));
if (debug_linux_nat)
{
fprintf_unfiltered (gdb_stdlog,
"LLAL: waitpid %s received %s\n",
target_pid_to_str (ptid),
status_to_str (status));
}
}
else
{
/* We assume that the LWP representing the original process is
already stopped. Mark it as stopped in the data structure
that the GNU/linux ptrace layer uses to keep track of
threads. Note that this won't have already been done since
the main thread will have, we assume, been stopped by an
attach from a different layer. */
if (lp == NULL)
lp = add_lwp (ptid);
lp->stopped = 1;
}
lp->last_resume_kind = resume_stop;
restore_child_signals_mask (&prev_mask);
return 0;
}
static void
linux_nat_create_inferior (struct target_ops *ops,
char *exec_file, char *allargs, char **env,
int from_tty)
{
#ifdef HAVE_PERSONALITY
int personality_orig = 0, personality_set = 0;
#endif /* HAVE_PERSONALITY */
/* The fork_child mechanism is synchronous and calls target_wait, so
we have to mask the async mode. */
#ifdef HAVE_PERSONALITY
if (disable_randomization)
{
errno = 0;
personality_orig = personality (0xffffffff);
if (errno == 0 && !(personality_orig & ADDR_NO_RANDOMIZE))
{
personality_set = 1;
personality (personality_orig | ADDR_NO_RANDOMIZE);
}
if (errno != 0 || (personality_set
&& !(personality (0xffffffff) & ADDR_NO_RANDOMIZE)))
warning (_("Error disabling address space randomization: %s"),
safe_strerror (errno));
}
#endif /* HAVE_PERSONALITY */
/* Make sure we report all signals during startup. */
linux_nat_pass_signals (0, NULL);
linux_ops->to_create_inferior (ops, exec_file, allargs, env, from_tty);
#ifdef HAVE_PERSONALITY
if (personality_set)
{
errno = 0;
personality (personality_orig);
if (errno != 0)
warning (_("Error restoring address space randomization: %s"),
safe_strerror (errno));
}
#endif /* HAVE_PERSONALITY */
}
static void
linux_nat_attach (struct target_ops *ops, char *args, int from_tty)
{
struct lwp_info *lp;
int status;
ptid_t ptid;
volatile struct gdb_exception ex;
/* Make sure we report all signals during attach. */
linux_nat_pass_signals (0, NULL);
TRY_CATCH (ex, RETURN_MASK_ERROR)
{
linux_ops->to_attach (ops, args, from_tty);
}
if (ex.reason < 0)
{
pid_t pid = parse_pid_to_attach (args);
struct buffer buffer;
char *message, *buffer_s;
message = xstrdup (ex.message);
make_cleanup (xfree, message);
buffer_init (&buffer);
linux_ptrace_attach_warnings (pid, &buffer);
buffer_grow_str0 (&buffer, "");
buffer_s = buffer_finish (&buffer);
make_cleanup (xfree, buffer_s);
throw_error (ex.error, "%s%s", buffer_s, message);
}
/* The ptrace base target adds the main thread with (pid,0,0)
format. Decorate it with lwp info. */
ptid = BUILD_LWP (GET_PID (inferior_ptid), GET_PID (inferior_ptid));
thread_change_ptid (inferior_ptid, ptid);
/* Add the initial process as the first LWP to the list. */
lp = add_lwp (ptid);
status = linux_nat_post_attach_wait (lp->ptid, 1, &lp->cloned,
&lp->signalled);
if (!WIFSTOPPED (status))
{
if (WIFEXITED (status))
{
int exit_code = WEXITSTATUS (status);
target_terminal_ours ();
target_mourn_inferior ();
if (exit_code == 0)
error (_("Unable to attach: program exited normally."));
else
error (_("Unable to attach: program exited with code %d."),
exit_code);
}
else if (WIFSIGNALED (status))
{
enum gdb_signal signo;
target_terminal_ours ();
target_mourn_inferior ();
signo = gdb_signal_from_host (WTERMSIG (status));
error (_("Unable to attach: program terminated with signal "
"%s, %s."),
gdb_signal_to_name (signo),
gdb_signal_to_string (signo));
}
internal_error (__FILE__, __LINE__,
_("unexpected status %d for PID %ld"),
status, (long) GET_LWP (ptid));
}
lp->stopped = 1;
/* Save the wait status to report later. */
lp->resumed = 1;
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"LNA: waitpid %ld, saving status %s\n",
(long) GET_PID (lp->ptid), status_to_str (status));
lp->status = status;
if (target_can_async_p ())
target_async (inferior_event_handler, 0);
}
/* Get pending status of LP. */
static int
get_pending_status (struct lwp_info *lp, int *status)
{
enum gdb_signal signo = GDB_SIGNAL_0;
/* If we paused threads momentarily, we may have stored pending
events in lp->status or lp->waitstatus (see stop_wait_callback),
and GDB core hasn't seen any signal for those threads.
Otherwise, the last signal reported to the core is found in the
thread object's stop_signal.
There's a corner case that isn't handled here at present. Only
if the thread stopped with a TARGET_WAITKIND_STOPPED does
stop_signal make sense as a real signal to pass to the inferior.
Some catchpoint related events, like
TARGET_WAITKIND_(V)FORK|EXEC|SYSCALL, have their stop_signal set
to GDB_SIGNAL_SIGTRAP when the catchpoint triggers. But,
those traps are debug API (ptrace in our case) related and
induced; the inferior wouldn't see them if it wasn't being
traced. Hence, we should never pass them to the inferior, even
when set to pass state. Since this corner case isn't handled by
infrun.c when proceeding with a signal, for consistency, neither
do we handle it here (or elsewhere in the file we check for
signal pass state). Normally SIGTRAP isn't set to pass state, so
this is really a corner case. */
if (lp->waitstatus.kind != TARGET_WAITKIND_IGNORE)
signo = GDB_SIGNAL_0; /* a pending ptrace event, not a real signal. */
else if (lp->status)
signo = gdb_signal_from_host (WSTOPSIG (lp->status));
else if (non_stop && !is_executing (lp->ptid))
{
struct thread_info *tp = find_thread_ptid (lp->ptid);
signo = tp->suspend.stop_signal;
}
else if (!non_stop)
{
struct target_waitstatus last;
ptid_t last_ptid;
get_last_target_status (&last_ptid, &last);
if (GET_LWP (lp->ptid) == GET_LWP (last_ptid))
{
struct thread_info *tp = find_thread_ptid (lp->ptid);
signo = tp->suspend.stop_signal;
}
}
*status = 0;
if (signo == GDB_SIGNAL_0)
{
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"GPT: lwp %s has no pending signal\n",
target_pid_to_str (lp->ptid));
}
else if (!signal_pass_state (signo))
{
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"GPT: lwp %s had signal %s, "
"but it is in no pass state\n",
target_pid_to_str (lp->ptid),
gdb_signal_to_string (signo));
}
else
{
*status = W_STOPCODE (gdb_signal_to_host (signo));
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"GPT: lwp %s has pending signal %s\n",
target_pid_to_str (lp->ptid),
gdb_signal_to_string (signo));
}
return 0;
}
static int
detach_callback (struct lwp_info *lp, void *data)
{
gdb_assert (lp->status == 0 || WIFSTOPPED (lp->status));
if (debug_linux_nat && lp->status)
fprintf_unfiltered (gdb_stdlog, "DC: Pending %s for %s on detach.\n",
strsignal (WSTOPSIG (lp->status)),
target_pid_to_str (lp->ptid));
/* If there is a pending SIGSTOP, get rid of it. */
if (lp->signalled)
{
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"DC: Sending SIGCONT to %s\n",
target_pid_to_str (lp->ptid));
kill_lwp (GET_LWP (lp->ptid), SIGCONT);
lp->signalled = 0;
}
/* We don't actually detach from the LWP that has an id equal to the
overall process id just yet. */
if (GET_LWP (lp->ptid) != GET_PID (lp->ptid))
{
int status = 0;
/* Pass on any pending signal for this LWP. */
get_pending_status (lp, &status);
if (linux_nat_prepare_to_resume != NULL)
linux_nat_prepare_to_resume (lp);
errno = 0;
if (ptrace (PTRACE_DETACH, GET_LWP (lp->ptid), 0,
WSTOPSIG (status)) < 0)
error (_("Can't detach %s: %s"), target_pid_to_str (lp->ptid),
safe_strerror (errno));
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"PTRACE_DETACH (%s, %s, 0) (OK)\n",
target_pid_to_str (lp->ptid),
strsignal (WSTOPSIG (status)));
delete_lwp (lp->ptid);
}
return 0;
}
static void
linux_nat_detach (struct target_ops *ops, char *args, int from_tty)
{
int pid;
int status;
struct lwp_info *main_lwp;
pid = GET_PID (inferior_ptid);
/* Don't unregister from the event loop, as there may be other
inferiors running. */
/* Stop all threads before detaching. ptrace requires that the
thread is stopped to sucessfully detach. */
iterate_over_lwps (pid_to_ptid (pid), stop_callback, NULL);
/* ... and wait until all of them have reported back that
they're no longer running. */
iterate_over_lwps (pid_to_ptid (pid), stop_wait_callback, NULL);
iterate_over_lwps (pid_to_ptid (pid), detach_callback, NULL);
/* Only the initial process should be left right now. */
gdb_assert (num_lwps (GET_PID (inferior_ptid)) == 1);
main_lwp = find_lwp_pid (pid_to_ptid (pid));
/* Pass on any pending signal for the last LWP. */
if ((args == NULL || *args == '\0')
&& get_pending_status (main_lwp, &status) != -1
&& WIFSTOPPED (status))
{
/* Put the signal number in ARGS so that inf_ptrace_detach will
pass it along with PTRACE_DETACH. */
args = alloca (8);
sprintf (args, "%d", (int) WSTOPSIG (status));
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"LND: Sending signal %s to %s\n",
args,
target_pid_to_str (main_lwp->ptid));
}
if (linux_nat_prepare_to_resume != NULL)
linux_nat_prepare_to_resume (main_lwp);
delete_lwp (main_lwp->ptid);
if (forks_exist_p ())
{
/* Multi-fork case. The current inferior_ptid is being detached
from, but there are other viable forks to debug. Detach from
the current fork, and context-switch to the first
available. */
linux_fork_detach (args, from_tty);
}
else
linux_ops->to_detach (ops, args, from_tty);
}
/* Resume LP. */
static void
resume_lwp (struct lwp_info *lp, int step, enum gdb_signal signo)
{
if (lp->stopped)
{
struct inferior *inf = find_inferior_pid (GET_PID (lp->ptid));
if (inf->vfork_child != NULL)
{
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"RC: Not resuming %s (vfork parent)\n",
target_pid_to_str (lp->ptid));
}
else if (lp->status == 0
&& lp->waitstatus.kind == TARGET_WAITKIND_IGNORE)
{
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"RC: Resuming sibling %s, %s, %s\n",
target_pid_to_str (lp->ptid),
(signo != GDB_SIGNAL_0
? strsignal (gdb_signal_to_host (signo))
: "0"),
step ? "step" : "resume");
if (linux_nat_prepare_to_resume != NULL)
linux_nat_prepare_to_resume (lp);
linux_ops->to_resume (linux_ops,
pid_to_ptid (GET_LWP (lp->ptid)),
step, signo);
lp->stopped = 0;
lp->step = step;
lp->stopped_by_watchpoint = 0;
}
else
{
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"RC: Not resuming sibling %s (has pending)\n",
target_pid_to_str (lp->ptid));
}
}
else
{
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"RC: Not resuming sibling %s (not stopped)\n",
target_pid_to_str (lp->ptid));
}
}
/* Resume LWP, with the last stop signal, if it is in pass state. */
static int
linux_nat_resume_callback (struct lwp_info *lp, void *data)
{
enum gdb_signal signo = GDB_SIGNAL_0;
if (lp->stopped)
{
struct thread_info *thread;
thread = find_thread_ptid (lp->ptid);
if (thread != NULL)
{
if (signal_pass_state (thread->suspend.stop_signal))
signo = thread->suspend.stop_signal;
thread->suspend.stop_signal = GDB_SIGNAL_0;
}
}
resume_lwp (lp, 0, signo);
return 0;
}
static int
resume_clear_callback (struct lwp_info *lp, void *data)
{
lp->resumed = 0;
lp->last_resume_kind = resume_stop;
return 0;
}
static int
resume_set_callback (struct lwp_info *lp, void *data)
{
lp->resumed = 1;
lp->last_resume_kind = resume_continue;
return 0;
}
static void
linux_nat_resume (struct target_ops *ops,
ptid_t ptid, int step, enum gdb_signal signo)
{
sigset_t prev_mask;
struct lwp_info *lp;
int resume_many;
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"LLR: Preparing to %s %s, %s, inferior_ptid %s\n",
step ? "step" : "resume",
target_pid_to_str (ptid),
(signo != GDB_SIGNAL_0
? strsignal (gdb_signal_to_host (signo)) : "0"),
target_pid_to_str (inferior_ptid));
block_child_signals (&prev_mask);
/* A specific PTID means `step only this process id'. */
resume_many = (ptid_equal (minus_one_ptid, ptid)
|| ptid_is_pid (ptid));
/* Mark the lwps we're resuming as resumed. */
iterate_over_lwps (ptid, resume_set_callback, NULL);
/* See if it's the current inferior that should be handled
specially. */
if (resume_many)
lp = find_lwp_pid (inferior_ptid);
else
lp = find_lwp_pid (ptid);
gdb_assert (lp != NULL);
/* Remember if we're stepping. */
lp->step = step;
lp->last_resume_kind = step ? resume_step : resume_continue;
/* If we have a pending wait status for this thread, there is no
point in resuming the process. But first make sure that
linux_nat_wait won't preemptively handle the event - we
should never take this short-circuit if we are going to
leave LP running, since we have skipped resuming all the
other threads. This bit of code needs to be synchronized
with linux_nat_wait. */
if (lp->status && WIFSTOPPED (lp->status))
{
if (!lp->step
&& WSTOPSIG (lp->status)
&& sigismember (&pass_mask, WSTOPSIG (lp->status)))
{
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"LLR: Not short circuiting for ignored "
"status 0x%x\n", lp->status);
/* FIXME: What should we do if we are supposed to continue
this thread with a signal? */
gdb_assert (signo == GDB_SIGNAL_0);
signo = gdb_signal_from_host (WSTOPSIG (lp->status));
lp->status = 0;
}
}
if (lp->status || lp->waitstatus.kind != TARGET_WAITKIND_IGNORE)
{
/* FIXME: What should we do if we are supposed to continue
this thread with a signal? */
gdb_assert (signo == GDB_SIGNAL_0);
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"LLR: Short circuiting for status 0x%x\n",
lp->status);
restore_child_signals_mask (&prev_mask);
if (target_can_async_p ())
{
target_async (inferior_event_handler, 0);
/* Tell the event loop we have something to process. */
async_file_mark ();
}
return;
}
/* Mark LWP as not stopped to prevent it from being continued by
linux_nat_resume_callback. */
lp->stopped = 0;
if (resume_many)
iterate_over_lwps (ptid, linux_nat_resume_callback, NULL);
/* Convert to something the lower layer understands. */
ptid = pid_to_ptid (GET_LWP (lp->ptid));
if (linux_nat_prepare_to_resume != NULL)
linux_nat_prepare_to_resume (lp);
linux_ops->to_resume (linux_ops, ptid, step, signo);
lp->stopped_by_watchpoint = 0;
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"LLR: %s %s, %s (resume event thread)\n",
step ? "PTRACE_SINGLESTEP" : "PTRACE_CONT",
target_pid_to_str (ptid),
(signo != GDB_SIGNAL_0
? strsignal (gdb_signal_to_host (signo)) : "0"));
restore_child_signals_mask (&prev_mask);
if (target_can_async_p ())
target_async (inferior_event_handler, 0);
}
/* Send a signal to an LWP. */
static int
kill_lwp (int lwpid, int signo)
{
/* Use tkill, if possible, in case we are using nptl threads. If tkill
fails, then we are not using nptl threads and we should be using kill. */
#ifdef HAVE_TKILL_SYSCALL
{
static int tkill_failed;
if (!tkill_failed)
{
int ret;
errno = 0;
ret = syscall (__NR_tkill, lwpid, signo);
if (errno != ENOSYS)
return ret;
tkill_failed = 1;
}
}
#endif
return kill (lwpid, signo);
}
/* Handle a GNU/Linux syscall trap wait response. If we see a syscall
event, check if the core is interested in it: if not, ignore the
event, and keep waiting; otherwise, we need to toggle the LWP's
syscall entry/exit status, since the ptrace event itself doesn't
indicate it, and report the trap to higher layers. */
static int
linux_handle_syscall_trap (struct lwp_info *lp, int stopping)
{
struct target_waitstatus *ourstatus = &lp->waitstatus;
struct gdbarch *gdbarch = target_thread_architecture (lp->ptid);
int syscall_number = (int) gdbarch_get_syscall_number (gdbarch, lp->ptid);
if (stopping)
{
/* If we're stopping threads, there's a SIGSTOP pending, which
makes it so that the LWP reports an immediate syscall return,
followed by the SIGSTOP. Skip seeing that "return" using
PTRACE_CONT directly, and let stop_wait_callback collect the
SIGSTOP. Later when the thread is resumed, a new syscall
entry event. If we didn't do this (and returned 0), we'd
leave a syscall entry pending, and our caller, by using
PTRACE_CONT to collect the SIGSTOP, skips the syscall return
itself. Later, when the user re-resumes this LWP, we'd see
another syscall entry event and we'd mistake it for a return.
If stop_wait_callback didn't force the SIGSTOP out of the LWP
(leaving immediately with LWP->signalled set, without issuing
a PTRACE_CONT), it would still be problematic to leave this
syscall enter pending, as later when the thread is resumed,
it would then see the same syscall exit mentioned above,
followed by the delayed SIGSTOP, while the syscall didn't
actually get to execute. It seems it would be even more
confusing to the user. */
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"LHST: ignoring syscall %d "
"for LWP %ld (stopping threads), "
"resuming with PTRACE_CONT for SIGSTOP\n",
syscall_number,
GET_LWP (lp->ptid));
lp->syscall_state = TARGET_WAITKIND_IGNORE;
ptrace (PTRACE_CONT, GET_LWP (lp->ptid), 0, 0);
return 1;
}
if (catch_syscall_enabled ())
{
/* Always update the entry/return state, even if this particular
syscall isn't interesting to the core now. In async mode,
the user could install a new catchpoint for this syscall
between syscall enter/return, and we'll need to know to
report a syscall return if that happens. */
lp->syscall_state = (lp->syscall_state == TARGET_WAITKIND_SYSCALL_ENTRY
? TARGET_WAITKIND_SYSCALL_RETURN
: TARGET_WAITKIND_SYSCALL_ENTRY);
if (catching_syscall_number (syscall_number))
{
/* Alright, an event to report. */
ourstatus->kind = lp->syscall_state;
ourstatus->value.syscall_number = syscall_number;
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"LHST: stopping for %s of syscall %d"
" for LWP %ld\n",
lp->syscall_state
== TARGET_WAITKIND_SYSCALL_ENTRY
? "entry" : "return",
syscall_number,
GET_LWP (lp->ptid));
return 0;
}
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"LHST: ignoring %s of syscall %d "
"for LWP %ld\n",
lp->syscall_state == TARGET_WAITKIND_SYSCALL_ENTRY
? "entry" : "return",
syscall_number,
GET_LWP (lp->ptid));
}
else
{
/* If we had been syscall tracing, and hence used PT_SYSCALL
before on this LWP, it could happen that the user removes all
syscall catchpoints before we get to process this event.
There are two noteworthy issues here:
- When stopped at a syscall entry event, resuming with
PT_STEP still resumes executing the syscall and reports a
syscall return.
- Only PT_SYSCALL catches syscall enters. If we last
single-stepped this thread, then this event can't be a
syscall enter. If we last single-stepped this thread, this
has to be a syscall exit.
The points above mean that the next resume, be it PT_STEP or
PT_CONTINUE, can not trigger a syscall trace event. */
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"LHST: caught syscall event "
"with no syscall catchpoints."
" %d for LWP %ld, ignoring\n",
syscall_number,
GET_LWP (lp->ptid));
lp->syscall_state = TARGET_WAITKIND_IGNORE;
}
/* The core isn't interested in this event. For efficiency, avoid
stopping all threads only to have the core resume them all again.
Since we're not stopping threads, if we're still syscall tracing
and not stepping, we can't use PTRACE_CONT here, as we'd miss any
subsequent syscall. Simply resume using the inf-ptrace layer,
which knows when to use PT_SYSCALL or PT_CONTINUE. */
/* Note that gdbarch_get_syscall_number may access registers, hence
fill a regcache. */
registers_changed ();
if (linux_nat_prepare_to_resume != NULL)
linux_nat_prepare_to_resume (lp);
linux_ops->to_resume (linux_ops, pid_to_ptid (GET_LWP (lp->ptid)),
lp->step, GDB_SIGNAL_0);
return 1;
}
/* Handle a GNU/Linux extended wait response. If we see a clone
event, we need to add the new LWP to our list (and not report the
trap to higher layers). This function returns non-zero if the
event should be ignored and we should wait again. If STOPPING is
true, the new LWP remains stopped, otherwise it is continued. */
static int
linux_handle_extended_wait (struct lwp_info *lp, int status,
int stopping)
{
int pid = GET_LWP (lp->ptid);
struct target_waitstatus *ourstatus = &lp->waitstatus;
int event = status >> 16;
if (event == PTRACE_EVENT_FORK || event == PTRACE_EVENT_VFORK
|| event == PTRACE_EVENT_CLONE)
{
unsigned long new_pid;
int ret;
ptrace (PTRACE_GETEVENTMSG, pid, 0, &new_pid);
/* If we haven't already seen the new PID stop, wait for it now. */
if (! pull_pid_from_list (&stopped_pids, new_pid, &status))
{
/* The new child has a pending SIGSTOP. We can't affect it until it
hits the SIGSTOP, but we're already attached. */
ret = my_waitpid (new_pid, &status,
(event == PTRACE_EVENT_CLONE) ? __WCLONE : 0);
if (ret == -1)
perror_with_name (_("waiting for new child"));
else if (ret != new_pid)
internal_error (__FILE__, __LINE__,
_("wait returned unexpected PID %d"), ret);
else if (!WIFSTOPPED (status))
internal_error (__FILE__, __LINE__,
_("wait returned unexpected status 0x%x"), status);
}
ourstatus->value.related_pid = ptid_build (new_pid, new_pid, 0);
if (event == PTRACE_EVENT_FORK
&& linux_fork_checkpointing_p (GET_PID (lp->ptid)))
{
/* Handle checkpointing by linux-fork.c here as a special
case. We don't want the follow-fork-mode or 'catch fork'
to interfere with this. */
/* This won't actually modify the breakpoint list, but will
physically remove the breakpoints from the child. */
detach_breakpoints (new_pid);
/* Retain child fork in ptrace (stopped) state. */
if (!find_fork_pid (new_pid))
add_fork (new_pid);
/* Report as spurious, so that infrun doesn't want to follow
this fork. We're actually doing an infcall in
linux-fork.c. */
ourstatus->kind = TARGET_WAITKIND_SPURIOUS;
linux_enable_event_reporting (pid_to_ptid (new_pid));
/* Report the stop to the core. */
return 0;
}
if (event == PTRACE_EVENT_FORK)
ourstatus->kind = TARGET_WAITKIND_FORKED;
else if (event == PTRACE_EVENT_VFORK)
ourstatus->kind = TARGET_WAITKIND_VFORKED;
else
{
struct lwp_info *new_lp;
ourstatus->kind = TARGET_WAITKIND_IGNORE;
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"LHEW: Got clone event "
"from LWP %d, new child is LWP %ld\n",
pid, new_pid);
new_lp = add_lwp (BUILD_LWP (new_pid, GET_PID (lp->ptid)));
new_lp->cloned = 1;
new_lp->stopped = 1;
if (WSTOPSIG (status) != SIGSTOP)
{
/* This can happen if someone starts sending signals to
the new thread before it gets a chance to run, which
have a lower number than SIGSTOP (e.g. SIGUSR1).
This is an unlikely case, and harder to handle for
fork / vfork than for clone, so we do not try - but
we handle it for clone events here. We'll send
the other signal on to the thread below. */
new_lp->signalled = 1;
}
else
{
struct thread_info *tp;
/* When we stop for an event in some other thread, and
pull the thread list just as this thread has cloned,
we'll have seen the new thread in the thread_db list
before handling the CLONE event (glibc's
pthread_create adds the new thread to the thread list
before clone'ing, and has the kernel fill in the
thread's tid on the clone call with
CLONE_PARENT_SETTID). If that happened, and the core
had requested the new thread to stop, we'll have
killed it with SIGSTOP. But since SIGSTOP is not an
RT signal, it can only be queued once. We need to be
careful to not resume the LWP if we wanted it to
stop. In that case, we'll leave the SIGSTOP pending.
It will later be reported as GDB_SIGNAL_0. */
tp = find_thread_ptid (new_lp->ptid);
if (tp != NULL && tp->stop_requested)
new_lp->last_resume_kind = resume_stop;
else
status = 0;
}
if (non_stop)
{
/* Add the new thread to GDB's lists as soon as possible
so that:
1) the frontend doesn't have to wait for a stop to
display them, and,
2) we tag it with the correct running state. */
/* If the thread_db layer is active, let it know about
this new thread, and add it to GDB's list. */
if (!thread_db_attach_lwp (new_lp->ptid))
{
/* We're not using thread_db. Add it to GDB's
list. */
target_post_attach (GET_LWP (new_lp->ptid));
add_thread (new_lp->ptid);
}
if (!stopping)
{
set_running (new_lp->ptid, 1);
set_executing (new_lp->ptid, 1);
/* thread_db_attach_lwp -> lin_lwp_attach_lwp forced
resume_stop. */
new_lp->last_resume_kind = resume_continue;
}
}
if (status != 0)
{
/* We created NEW_LP so it cannot yet contain STATUS. */
gdb_assert (new_lp->status == 0);
/* Save the wait status to report later. */
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"LHEW: waitpid of new LWP %ld, "
"saving status %s\n",
(long) GET_LWP (new_lp->ptid),
status_to_str (status));
new_lp->status = status;
}
/* Note the need to use the low target ops to resume, to
handle resuming with PT_SYSCALL if we have syscall
catchpoints. */
if (!stopping)
{
new_lp->resumed = 1;
if (status == 0)
{
gdb_assert (new_lp->last_resume_kind == resume_continue);
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"LHEW: resuming new LWP %ld\n",
GET_LWP (new_lp->ptid));
if (linux_nat_prepare_to_resume != NULL)
linux_nat_prepare_to_resume (new_lp);
linux_ops->to_resume (linux_ops, pid_to_ptid (new_pid),
0, GDB_SIGNAL_0);
new_lp->stopped = 0;
}
}
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"LHEW: resuming parent LWP %d\n", pid);
if (linux_nat_prepare_to_resume != NULL)
linux_nat_prepare_to_resume (lp);
linux_ops->to_resume (linux_ops, pid_to_ptid (GET_LWP (lp->ptid)),
0, GDB_SIGNAL_0);
return 1;
}
return 0;
}
if (event == PTRACE_EVENT_EXEC)
{
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"LHEW: Got exec event from LWP %ld\n",
GET_LWP (lp->ptid));
ourstatus->kind = TARGET_WAITKIND_EXECD;
ourstatus->value.execd_pathname
= xstrdup (linux_child_pid_to_exec_file (pid));
return 0;
}
if (event == PTRACE_EVENT_VFORK_DONE)
{
if (current_inferior ()->waiting_for_vfork_done)
{
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"LHEW: Got expected PTRACE_EVENT_"
"VFORK_DONE from LWP %ld: stopping\n",
GET_LWP (lp->ptid));
ourstatus->kind = TARGET_WAITKIND_VFORK_DONE;
return 0;
}
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"LHEW: Got PTRACE_EVENT_VFORK_DONE "
"from LWP %ld: resuming\n",
GET_LWP (lp->ptid));
ptrace (PTRACE_CONT, GET_LWP (lp->ptid), 0, 0);
return 1;
}
internal_error (__FILE__, __LINE__,
_("unknown ptrace event %d"), event);
}
/* Wait for LP to stop. Returns the wait status, or 0 if the LWP has
exited. */
static int
wait_lwp (struct lwp_info *lp)
{
pid_t pid;
int status = 0;
int thread_dead = 0;
sigset_t prev_mask;
gdb_assert (!lp->stopped);
gdb_assert (lp->status == 0);
/* Make sure SIGCHLD is blocked for sigsuspend avoiding a race below. */
block_child_signals (&prev_mask);
for (;;)
{
/* If my_waitpid returns 0 it means the __WCLONE vs. non-__WCLONE kind
was right and we should just call sigsuspend. */
pid = my_waitpid (GET_LWP (lp->ptid), &status, WNOHANG);
if (pid == -1 && errno == ECHILD)
pid = my_waitpid (GET_LWP (lp->ptid), &status, __WCLONE | WNOHANG);
if (pid == -1 && errno == ECHILD)
{
/* The thread has previously exited. We need to delete it
now because, for some vendor 2.4 kernels with NPTL
support backported, there won't be an exit event unless
it is the main thread. 2.6 kernels will report an exit
event for each thread that exits, as expected. */
thread_dead = 1;
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog, "WL: %s vanished.\n",
target_pid_to_str (lp->ptid));
}
if (pid != 0)
break;
/* Bugs 10970, 12702.
Thread group leader may have exited in which case we'll lock up in
waitpid if there are other threads, even if they are all zombies too.
Basically, we're not supposed to use waitpid this way.
__WCLONE is not applicable for the leader so we can't use that.
LINUX_NAT_THREAD_ALIVE cannot be used here as it requires a STOPPED
process; it gets ESRCH both for the zombie and for running processes.
As a workaround, check if we're waiting for the thread group leader and
if it's a zombie, and avoid calling waitpid if it is.
This is racy, what if the tgl becomes a zombie right after we check?
Therefore always use WNOHANG with sigsuspend - it is equivalent to
waiting waitpid but linux_proc_pid_is_zombie is safe this way. */
if (GET_PID (lp->ptid) == GET_LWP (lp->ptid)
&& linux_proc_pid_is_zombie (GET_LWP (lp->ptid)))
{
thread_dead = 1;
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"WL: Thread group leader %s vanished.\n",
target_pid_to_str (lp->ptid));
break;
}
/* Wait for next SIGCHLD and try again. This may let SIGCHLD handlers
get invoked despite our caller had them intentionally blocked by
block_child_signals. This is sensitive only to the loop of
linux_nat_wait_1 and there if we get called my_waitpid gets called
again before it gets to sigsuspend so we can safely let the handlers
get executed here. */
sigsuspend (&suspend_mask);
}
restore_child_signals_mask (&prev_mask);
if (!thread_dead)
{
gdb_assert (pid == GET_LWP (lp->ptid));
if (debug_linux_nat)
{
fprintf_unfiltered (gdb_stdlog,
"WL: waitpid %s received %s\n",
target_pid_to_str (lp->ptid),
status_to_str (status));
}
/* Check if the thread has exited. */
if (WIFEXITED (status) || WIFSIGNALED (status))
{
thread_dead = 1;
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog, "WL: %s exited.\n",
target_pid_to_str (lp->ptid));
}
}
if (thread_dead)
{
exit_lwp (lp);
return 0;
}
gdb_assert (WIFSTOPPED (status));
/* Handle GNU/Linux's syscall SIGTRAPs. */
if (WIFSTOPPED (status) && WSTOPSIG (status) == SYSCALL_SIGTRAP)
{
/* No longer need the sysgood bit. The ptrace event ends up
recorded in lp->waitstatus if we care for it. We can carry
on handling the event like a regular SIGTRAP from here
on. */
status = W_STOPCODE (SIGTRAP);
if (linux_handle_syscall_trap (lp, 1))
return wait_lwp (lp);
}
/* Handle GNU/Linux's extended waitstatus for trace events. */
if (WIFSTOPPED (status) && WSTOPSIG (status) == SIGTRAP && status >> 16 != 0)
{
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"WL: Handling extended status 0x%06x\n",
status);
if (linux_handle_extended_wait (lp, status, 1))
return wait_lwp (lp);
}
return status;
}
/* Send a SIGSTOP to LP. */
static int
stop_callback (struct lwp_info *lp, void *data)
{
if (!lp->stopped && !lp->signalled)
{
int ret;
if (debug_linux_nat)
{
fprintf_unfiltered (gdb_stdlog,
"SC: kill %s **<SIGSTOP>**\n",
target_pid_to_str (lp->ptid));
}
errno = 0;
ret = kill_lwp (GET_LWP (lp->ptid), SIGSTOP);
if (debug_linux_nat)
{
fprintf_unfiltered (gdb_stdlog,
"SC: lwp kill %d %s\n",
ret,
errno ? safe_strerror (errno) : "ERRNO-OK");
}
lp->signalled = 1;
gdb_assert (lp->status == 0);
}
return 0;
}
/* Request a stop on LWP. */
void
linux_stop_lwp (struct lwp_info *lwp)
{
stop_callback (lwp, NULL);
}
/* Return non-zero if LWP PID has a pending SIGINT. */
static int
linux_nat_has_pending_sigint (int pid)
{
sigset_t pending, blocked, ignored;
linux_proc_pending_signals (pid, &pending, &blocked, &ignored);
if (sigismember (&pending, SIGINT)
&& !sigismember (&ignored, SIGINT))
return 1;
return 0;
}
/* Set a flag in LP indicating that we should ignore its next SIGINT. */
static int
set_ignore_sigint (struct lwp_info *lp, void *data)
{
/* If a thread has a pending SIGINT, consume it; otherwise, set a
flag to consume the next one. */
if (lp->stopped && lp->status != 0 && WIFSTOPPED (lp->status)
&& WSTOPSIG (lp->status) == SIGINT)
lp->status = 0;
else
lp->ignore_sigint = 1;
return 0;
}
/* If LP does not have a SIGINT pending, then clear the ignore_sigint flag.
This function is called after we know the LWP has stopped; if the LWP
stopped before the expected SIGINT was delivered, then it will never have
arrived. Also, if the signal was delivered to a shared queue and consumed
by a different thread, it will never be delivered to this LWP. */
static void
maybe_clear_ignore_sigint (struct lwp_info *lp)
{
if (!lp->ignore_sigint)
return;
if (!linux_nat_has_pending_sigint (GET_LWP (lp->ptid)))
{
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"MCIS: Clearing bogus flag for %s\n",
target_pid_to_str (lp->ptid));
lp->ignore_sigint = 0;
}
}
/* Fetch the possible triggered data watchpoint info and store it in
LP.
On some archs, like x86, that use debug registers to set
watchpoints, it's possible that the way to know which watched
address trapped, is to check the register that is used to select
which address to watch. Problem is, between setting the watchpoint
and reading back which data address trapped, the user may change
the set of watchpoints, and, as a consequence, GDB changes the
debug registers in the inferior. To avoid reading back a stale
stopped-data-address when that happens, we cache in LP the fact
that a watchpoint trapped, and the corresponding data address, as
soon as we see LP stop with a SIGTRAP. If GDB changes the debug
registers meanwhile, we have the cached data we can rely on. */
static void
save_sigtrap (struct lwp_info *lp)
{
struct cleanup *old_chain;
if (linux_ops->to_stopped_by_watchpoint == NULL)
{
lp->stopped_by_watchpoint = 0;
return;
}
old_chain = save_inferior_ptid ();
inferior_ptid = lp->ptid;
lp->stopped_by_watchpoint = linux_ops->to_stopped_by_watchpoint ();
if (lp->stopped_by_watchpoint)
{
if (linux_ops->to_stopped_data_address != NULL)
lp->stopped_data_address_p =
linux_ops->to_stopped_data_address (&current_target,
&lp->stopped_data_address);
else
lp->stopped_data_address_p = 0;
}
do_cleanups (old_chain);
}
/* See save_sigtrap. */
static int
linux_nat_stopped_by_watchpoint (void)
{
struct lwp_info *lp = find_lwp_pid (inferior_ptid);
gdb_assert (lp != NULL);
return lp->stopped_by_watchpoint;
}
static int
linux_nat_stopped_data_address (struct target_ops *ops, CORE_ADDR *addr_p)
{
struct lwp_info *lp = find_lwp_pid (inferior_ptid);
gdb_assert (lp != NULL);
*addr_p = lp->stopped_data_address;
return lp->stopped_data_address_p;
}
/* Commonly any breakpoint / watchpoint generate only SIGTRAP. */
static int
sigtrap_is_event (int status)
{
return WIFSTOPPED (status) && WSTOPSIG (status) == SIGTRAP;
}
/* SIGTRAP-like events recognizer. */
static int (*linux_nat_status_is_event) (int status) = sigtrap_is_event;
/* Check for SIGTRAP-like events in LP. */
static int
linux_nat_lp_status_is_event (struct lwp_info *lp)
{
/* We check for lp->waitstatus in addition to lp->status, because we can
have pending process exits recorded in lp->status
and W_EXITCODE(0,0) == 0. We should probably have an additional
lp->status_p flag. */
return (lp->waitstatus.kind == TARGET_WAITKIND_IGNORE
&& linux_nat_status_is_event (lp->status));
}
/* Set alternative SIGTRAP-like events recognizer. If
breakpoint_inserted_here_p there then gdbarch_decr_pc_after_break will be
applied. */
void
linux_nat_set_status_is_event (struct target_ops *t,
int (*status_is_event) (int status))
{
linux_nat_status_is_event = status_is_event;
}
/* Wait until LP is stopped. */
static int
stop_wait_callback (struct lwp_info *lp, void *data)
{
struct inferior *inf = find_inferior_pid (GET_PID (lp->ptid));
/* If this is a vfork parent, bail out, it is not going to report
any SIGSTOP until the vfork is done with. */
if (inf->vfork_child != NULL)
return 0;
if (!lp->stopped)
{
int status;
status = wait_lwp (lp);
if (status == 0)
return 0;
if (lp->ignore_sigint && WIFSTOPPED (status)
&& WSTOPSIG (status) == SIGINT)
{
lp->ignore_sigint = 0;
errno = 0;
ptrace (PTRACE_CONT, GET_LWP (lp->ptid), 0, 0);
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"PTRACE_CONT %s, 0, 0 (%s) "
"(discarding SIGINT)\n",
target_pid_to_str (lp->ptid),
errno ? safe_strerror (errno) : "OK");
return stop_wait_callback (lp, NULL);
}
maybe_clear_ignore_sigint (lp);
if (WSTOPSIG (status) != SIGSTOP)
{
/* The thread was stopped with a signal other than SIGSTOP. */
save_sigtrap (lp);
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"SWC: Pending event %s in %s\n",
status_to_str ((int) status),
target_pid_to_str (lp->ptid));
/* Save the sigtrap event. */
lp->status = status;
gdb_assert (!lp->stopped);
gdb_assert (lp->signalled);
lp->stopped = 1;
}
else
{
/* We caught the SIGSTOP that we intended to catch, so
there's no SIGSTOP pending. */
if (debug_linux_nat)
fprintf_unfiltered (gdb_stdlog,
"SWC: Delayed SIGSTOP caught for %s.\n",
target_pid_to_str (lp->ptid));
lp->stopped = 1;
/* Reset SIGNALLED only after the stop_wait_callback call
above as it does gdb_assert on SIGNALLED. */
lp->signalled = 0;
}
}
return 0;
}
/* Return non-zero if LP has a wait status pending. */
static int
status_callback (struct lwp_info *lp, void *data)
{
/* Only report a pending wait status if we pretend that this has
indeed been resumed. */
if (!lp->resumed)
return 0;
if (lp->waitstatus.kind != TARGET_WAITKIND_IGNORE)
{
/* A ptrace event, like PTRACE_FORK|VFORK|EXEC, syscall event,
or a pending process exit. Note that `W_EXITCODE(0,0) ==
0', so a clean process exit can not be stored pending in
lp->status, it is indistinguishable from
no-pending-status. */
return 1;
}
if (lp->status != 0)
return 1;
return 0;
}
/* Return non-zero if LP isn't stopped. */
static int
running_callback (struct lwp_info *lp, void *data)
{
return (!lp->stopped
|| ((lp->status != 0
|| lp->waitstatus.kind != TARGET_WAITKIND_IGNORE)
&& lp->resumed));
}
/* Count the LWP's that have had events. */
static int
count_events_callback (struct lwp_info *lp, void *data)
{
int *count = data;
gdb_assert (count != NULL);
/* Count only resumed LWPs that have a SIGTRAP event pending. */
if (lp->resumed && linux_nat_lp_status_is_event (lp))
(*count)++;
return 0;
}
/* Select the LWP (if any) that is currently being single-stepped. */
static int
select_singlestep_lwp_callback (struct lwp_info *lp, void *data)
{
if (lp->last_resume_kind == resume_step
&& lp->status != 0)
return 1;
else
return 0;
}
/* Select the Nth LWP that has had a SIGTRAP event. */
static int
select_event_lwp_callback (struct lwp_info *lp, void *data)
{
int *selector = data;
gdb_assert (selector != NULL);
/* Select only resumed LWPs that have a SIGTRAP event pending. */
if (lp->resumed && linux_nat_lp_status_is_event (lp))
if ((*selector)-- == 0)
return 1;
return 0;
}
static int
cancel_breakpoint (struct lwp_info *lp)
{
/* Arrange for a breakpoint to be hit again later. We don't keep
the SIGTRAP status and don't forward the SIGTRAP signal to the
LWP. We will handle the current event, eventually we will resume
this LWP, and this breakpoint will trap again.
If we do not do this, then we run the risk that the user will
delete or disable the breakpoint, but the LWP will have already
tripped on it. */
struct regcache *regcache = get_thread_regcache (lp->ptid);
struct gdbarch *gdbarch = get_regcache_arch (regcache);
CORE_ADDR pc;
pc = regcache_read_pc (regcache) - gdbarch_decr_pc_after_break (gdbarch);
if