gdb/
* Makefile.in (linux-ptrace.o): New.
* common/linux-procfs.c (linux_proc_pid_is_zombie): New,
from linux-nat.c.
* common/linux-procfs.h (linux_proc_pid_is_zombie): New declaration.
* common/linux-ptrace.c: New file.
* config/alpha/alpha-linux.mh (NATDEPFILES): Add linux-ptrace.o.
* config/arm/linux.mh: Likewise.
* config/i386/linux.mh: Likewise.
* config/i386/linux64.mh: Likewise.
* config/ia64/linux.mh: Likewise.
* config/m32r/linux.mh: Likewise.
* config/m68k/linux.mh: Likewise.
* config/mips/linux.mh: Likewise.
* config/pa/linux.mh: Likewise.
* config/powerpc/linux.mh: Likewise.
* config/powerpc/ppc64-linux.mh: Likewise.
* config/powerpc/spu-linux.mh: Likewise.
* config/s390/s390.mh: Likewise.
* config/sparc/linux.mh: Likewise.
* config/sparc/linux64.mh: Likewise.
* config/xtensa/linux.mh: Likewise.
* linux-nat.c (linux_lwp_is_zombie): Remove, move it to
common/linux-procfs.c.
(wait_lwp): Rename linux_lwp_is_zombie to linux_proc_pid_is_zombie.
gdb/gdbserver/
* Makefile.in (linux-ptrace.o): New.
* configure.srv (arm*-*-linux*, bfin-*-*linux*, crisv32-*-linux*)
(cris-*-linux*, i[34567]86-*-linux*, ia64-*-linux*, m32r*-*-linux*)
(m68*-*-linux*, m68*-*-uclinux*, mips*-*-linux*, powerpc*-*-linux*)
(s390*-*-linux*, sh*-*-linux*, sparc*-*-linux*, tic6x-*-uclinux)
(x86_64-*-linux*, xtensa*-*-linux*): Add linux-ptrace.o to SRV_TGTOBJ
of these targets.
* linux-low.c (linux_attach_lwp_1): Remove redundent else clause.
2012-03-13 16:00:37 +01:00
|
|
|
/* Linux-specific ptrace manipulation routines.
|
2015-01-01 10:32:14 +01:00
|
|
|
Copyright (C) 2012-2015 Free Software Foundation, Inc.
|
gdb/
* Makefile.in (linux-ptrace.o): New.
* common/linux-procfs.c (linux_proc_pid_is_zombie): New,
from linux-nat.c.
* common/linux-procfs.h (linux_proc_pid_is_zombie): New declaration.
* common/linux-ptrace.c: New file.
* config/alpha/alpha-linux.mh (NATDEPFILES): Add linux-ptrace.o.
* config/arm/linux.mh: Likewise.
* config/i386/linux.mh: Likewise.
* config/i386/linux64.mh: Likewise.
* config/ia64/linux.mh: Likewise.
* config/m32r/linux.mh: Likewise.
* config/m68k/linux.mh: Likewise.
* config/mips/linux.mh: Likewise.
* config/pa/linux.mh: Likewise.
* config/powerpc/linux.mh: Likewise.
* config/powerpc/ppc64-linux.mh: Likewise.
* config/powerpc/spu-linux.mh: Likewise.
* config/s390/s390.mh: Likewise.
* config/sparc/linux.mh: Likewise.
* config/sparc/linux64.mh: Likewise.
* config/xtensa/linux.mh: Likewise.
* linux-nat.c (linux_lwp_is_zombie): Remove, move it to
common/linux-procfs.c.
(wait_lwp): Rename linux_lwp_is_zombie to linux_proc_pid_is_zombie.
gdb/gdbserver/
* Makefile.in (linux-ptrace.o): New.
* configure.srv (arm*-*-linux*, bfin-*-*linux*, crisv32-*-linux*)
(cris-*-linux*, i[34567]86-*-linux*, ia64-*-linux*, m32r*-*-linux*)
(m68*-*-linux*, m68*-*-uclinux*, mips*-*-linux*, powerpc*-*-linux*)
(s390*-*-linux*, sh*-*-linux*, sparc*-*-linux*, tic6x-*-uclinux)
(x86_64-*-linux*, xtensa*-*-linux*): Add linux-ptrace.o to SRV_TGTOBJ
of these targets.
* linux-low.c (linux_attach_lwp_1): Remove redundent else clause.
2012-03-13 16:00:37 +01:00
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
|
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
|
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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|
2014-09-12 11:11:42 +02:00
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#include "common-defs.h"
|
gdb/
* Makefile.in (linux-ptrace.o): New.
* common/linux-procfs.c (linux_proc_pid_is_zombie): New,
from linux-nat.c.
* common/linux-procfs.h (linux_proc_pid_is_zombie): New declaration.
* common/linux-ptrace.c: New file.
* config/alpha/alpha-linux.mh (NATDEPFILES): Add linux-ptrace.o.
* config/arm/linux.mh: Likewise.
* config/i386/linux.mh: Likewise.
* config/i386/linux64.mh: Likewise.
* config/ia64/linux.mh: Likewise.
* config/m32r/linux.mh: Likewise.
* config/m68k/linux.mh: Likewise.
* config/mips/linux.mh: Likewise.
* config/pa/linux.mh: Likewise.
* config/powerpc/linux.mh: Likewise.
* config/powerpc/ppc64-linux.mh: Likewise.
* config/powerpc/spu-linux.mh: Likewise.
* config/s390/s390.mh: Likewise.
* config/sparc/linux.mh: Likewise.
* config/sparc/linux64.mh: Likewise.
* config/xtensa/linux.mh: Likewise.
* linux-nat.c (linux_lwp_is_zombie): Remove, move it to
common/linux-procfs.c.
(wait_lwp): Rename linux_lwp_is_zombie to linux_proc_pid_is_zombie.
gdb/gdbserver/
* Makefile.in (linux-ptrace.o): New.
* configure.srv (arm*-*-linux*, bfin-*-*linux*, crisv32-*-linux*)
(cris-*-linux*, i[34567]86-*-linux*, ia64-*-linux*, m32r*-*-linux*)
(m68*-*-linux*, m68*-*-uclinux*, mips*-*-linux*, powerpc*-*-linux*)
(s390*-*-linux*, sh*-*-linux*, sparc*-*-linux*, tic6x-*-uclinux)
(x86_64-*-linux*, xtensa*-*-linux*): Add linux-ptrace.o to SRV_TGTOBJ
of these targets.
* linux-low.c (linux_attach_lwp_1): Remove redundent else clause.
2012-03-13 16:00:37 +01:00
|
|
|
#include "linux-ptrace.h"
|
2012-03-13 16:02:25 +01:00
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#include "linux-procfs.h"
|
2014-06-19 15:46:38 +02:00
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#include "linux-waitpid.h"
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2012-03-13 16:02:25 +01:00
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#include "buffer.h"
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2012-11-15 17:12:19 +01:00
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#include "gdb_wait.h"
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2012-03-13 16:02:25 +01:00
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2013-08-28 16:09:31 +02:00
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#include <stdint.h>
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Extended-remote Linux follow fork
This patch implements basic support for follow-fork and detach-on-fork on
extended-remote Linux targets. Only 'fork' is supported in this patch;
'vfork' support is added n a subsequent patch. This patch depends on
the previous patches in the patch series.
Sufficient extended-remote functionality has been implemented here to pass
gdb.base/multi-forks.exp, as well as gdb.base/foll-fork.exp with the
catchpoint tests commented out. Some other fork tests fail with this
patch because it doesn't provide the architecture support needed for
watchpoint inheritance or fork catchpoints.
The implementation follows the same general structure as for the native
implementation as much as possible.
This implementation includes:
* enabling fork events in linux-low.c in initialize_low and
linux_enable_extended_features
* handling fork events in gdbserver/linux-low.c:handle_extended_wait
- when a fork event occurs in gdbserver, we must do the full creation
of the new process, thread, lwp, and breakpoint lists. This is
required whether or not the new child is destined to be
detached-on-fork, because GDB will make target calls that require all
the structures. In particular we need the breakpoint lists in order
to remove the breakpoints from a detaching child. If we are not
detaching the child we will need all these structures anyway.
- as part of this event handling we store the target_waitstatus in a new
member of the parent lwp_info structure, 'waitstatus'. This
is used to store extended event information for reporting to GDB.
- handle_extended_wait is given a return value, denoting whether the
handled event should be reported to GDB. Previously it had only
handled clone events, which were never reported.
* using a new predicate in gdbserver to control handling of the fork event
(and eventually all extended events) in linux_wait_1. The predicate,
extended_event_reported, checks a target_waitstatus.kind for an
extended ptrace event.
* implementing a new RSP 'T' Stop Reply Packet stop reason: "fork", in
gdbserver/remote-utils.c and remote.c.
* implementing new target and RSP support for target_follow_fork with
target extended-remote. (The RSP components were actually defined in
patch 1, but they see their first use here).
- remote target routine remote_follow_fork, which just sends the 'D;pid'
detach packet to detach the new fork child cleanly. We can't just
call target_detach because the data structures for the forked child
have not been allocated on the host side.
Tested on x64 Ubuntu Lucid, native, remote, extended-remote.
gdb/gdbserver/ChangeLog:
* linux-low.c (handle_extended_wait): Implement return value,
rename argument 'event_child' to 'event_lwp', handle
PTRACE_EVENT_FORK, call internal_error for unrecognized event.
(linux_low_ptrace_options): New function.
(linux_low_filter_event): Call linux_low_ptrace_options,
use different argument fo linux_enable_event_reporting,
use return value from handle_extended_wait.
(extended_event_reported): New function.
(linux_wait_1): Call extended_event_reported and set
status to report fork events.
(linux_write_memory): Add pid to debug message.
(reset_lwp_ptrace_options_callback): New function.
(linux_handle_new_gdb_connection): New function.
(linux_target_ops): Initialize new structure member.
* linux-low.h (struct lwp_info) <waitstatus>: New member.
* lynx-low.c: Initialize new structure member.
* remote-utils.c (prepare_resume_reply): Implement stop reason
"fork" for "T" stop message.
* server.c (handle_query): Call handle_new_gdb_connection.
* server.h (report_fork_events): Declare global flag.
* target.h (struct target_ops) <handle_new_gdb_connection>:
New member.
(target_handle_new_gdb_connection): New macro.
* win32-low.c: Initialize new structure member.
gdb/ChangeLog:
* linux-nat.c (linux_nat_ptrace_options): New function.
(linux_init_ptrace, wait_lwp, linux_nat_filter_event):
Call linux_nat_ptrace_options and use different argument to
linux_enable_event_reporting.
(_initialize_linux_nat): Delete call to
linux_ptrace_set_additional_flags.
* nat/linux-ptrace.c (current_ptrace_options): Rename to
supported_ptrace_options.
(additional_flags): Delete variable.
(linux_check_ptrace_features): Use supported_ptrace_options.
(linux_test_for_tracesysgood, linux_test_for_tracefork):
Likewise, and remove additional_flags check.
(linux_enable_event_reporting): Change 'attached' argument to
'options'. Use supported_ptrace_options.
(ptrace_supports_feature): Change comment. Use
supported_ptrace_options.
(linux_ptrace_set_additional_flags): Delete function.
* nat/linux-ptrace.h (linux_ptrace_set_additional_flags):
Delete function prototype.
* remote.c (remote_fork_event_p): New function.
(remote_detach_pid): New function.
(remote_detach_1): Call remote_detach_pid, don't mourn inferior
if doing detach-on-fork.
(remote_follow_fork): New function.
(remote_parse_stop_reply): Handle new "T" stop reason "fork".
(remote_pid_to_str): Print "process" strings for pid/0/0 ptids.
(init_extended_remote_ops): Initialize to_follow_fork.
2015-05-12 18:52:43 +02:00
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/* Stores the ptrace options supported by the running kernel.
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A value of -1 means we did not check for features yet. A value
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of 0 means there are no supported features. */
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static int supported_ptrace_options = -1;
|
2014-01-03 18:55:52 +01:00
|
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|
PR server/16255: gdbserver cannot attach to a second inferior that is multi-threaded.
On Linux, we need to explicitly ptrace attach to all lwps of a
process. Because GDB might not be connected yet when an attach is
requested, and thus it may not be possible to activate thread_db, as
that requires access to symbols (IOW, gdbserver --attach), a while ago
we make linux_attach loop over the lwps as listed by /proc/PID/task to
find the lwps to attach to.
linux_attach_lwp_1 has:
...
if (initial)
/* If lwp is the tgid, we handle adding existing threads later.
Otherwise we just add lwp without bothering about any other
threads. */
ptid = ptid_build (lwpid, lwpid, 0);
else
{
/* Note that extracting the pid from the current inferior is
safe, since we're always called in the context of the same
process as this new thread. */
int pid = pid_of (current_inferior);
ptid = ptid_build (pid, lwpid, 0);
}
That "safe" comment referred to linux_attach_lwp being called by
thread-db.c. But this was clearly missed when a new call to
linux_attach_lwp_1 was added to linux_attach. As a result,
current_inferior will be set to some random process, and non-initial
lwps of the second inferior get assigned the pid of the wrong
inferior. E.g., in the case of attaching to two inferiors, for the
second inferior (and so on), non-initial lwps of the second inferior
get assigned the pid of the first inferior. This doesn't trigger on
the first inferior, when current_inferior is NULL, add_thread switches
the current inferior to the newly added thread.
Rather than making linux_attach switch current_inferior temporarily
(thus avoiding further reliance on global state), or making
linux_attach_lwp_1 get the tgid from /proc, which add extra syscalls,
and will be wrong in case of the user having originally attached
directly to a non-tgid lwp, and then that lwp spawning new clones (the
ptid.pid field of further new clones should be the same as the
original lwp's pid, which is not the tgid), we note that callers of
linux_attach_lwp/linux_attach_lwp_1 always have the right pid handy
already, so they can pass it down along with the lwpid.
The only other reason for the "initial" parameter is to error out
instead of warn in case of attach failure, when we're first attaching
to a process. There are only three callers of
linux_attach_lwp/linux_attach_lwp_1, and each wants to print a
different warn/error string, so we can just move the error/warn out of
linux_attach_lwp_1 to the callers, thus getting rid of the "initial"
parameter.
There really nothing gdbserver-specific about attaching to two
threaded processes, so this adds a new test under gdb.multi/. The
test passes cleanly against the native GNU/Linux target, but
fails/triggers the bug against GDBserver (before the patch), with the
native-extended-remote board (as plain remote doesn't support
multi-process).
Tested on x86_64 Fedora 17, with the native-extended-gdbserver board.
gdb/gdbserver/
2014-04-25 Pedro Alves <palves@redhat.com>
PR server/16255
* linux-low.c (linux_attach_fail_reason_string): New function.
(linux_attach_lwp): Delete.
(linux_attach_lwp_1): Rename to ...
(linux_attach_lwp): ... this. Take a ptid instead of a pid as
argument. Remove "initial" parameter. Return int instead of
void. Don't error or warn here.
(linux_attach): Adjust to call linux_attach_lwp. Call error on
failure to attach to the tgid. Call warning when failing to
attach to an lwp.
* linux-low.h (linux_attach_lwp): Take a ptid instead of a pid as
argument. Remove "initial" parameter. Return int instead of
void. Don't error or warn here.
(linux_attach_fail_reason_string): New declaration.
* thread-db.c (attach_thread): Adjust to linux_attach_lwp's
interface change. Use linux_attach_fail_reason_string.
gdb/
2014-04-25 Pedro Alves <palves@redhat.com>
PR server/16255
* common/linux-ptrace.c (linux_ptrace_attach_warnings): Rename to ...
(linux_ptrace_attach_fail_reason): ... this. Remove "warning: "
and newline from built string.
* common/linux-ptrace.h (linux_ptrace_attach_warnings): Rename to ...
(linux_ptrace_attach_fail_reason): ... this.
* linux-nat.c (linux_nat_attach): Adjust to use
linux_ptrace_attach_fail_reason.
gdb/testsuite/
2014-04-25 Simon Marchi <simon.marchi@ericsson.com>
Pedro Alves <palves@redhat.com>
PR server/16255
* gdb.multi/multi-attach.c: New file.
* gdb.multi/multi-attach.exp: New file.
2014-04-25 20:07:33 +02:00
|
|
|
/* Find all possible reasons we could fail to attach PID and append
|
|
|
|
these as strings to the already initialized BUFFER. '\0'
|
|
|
|
termination of BUFFER must be done by the caller. */
|
2012-03-13 16:02:25 +01:00
|
|
|
|
|
|
|
void
|
PR server/16255: gdbserver cannot attach to a second inferior that is multi-threaded.
On Linux, we need to explicitly ptrace attach to all lwps of a
process. Because GDB might not be connected yet when an attach is
requested, and thus it may not be possible to activate thread_db, as
that requires access to symbols (IOW, gdbserver --attach), a while ago
we make linux_attach loop over the lwps as listed by /proc/PID/task to
find the lwps to attach to.
linux_attach_lwp_1 has:
...
if (initial)
/* If lwp is the tgid, we handle adding existing threads later.
Otherwise we just add lwp without bothering about any other
threads. */
ptid = ptid_build (lwpid, lwpid, 0);
else
{
/* Note that extracting the pid from the current inferior is
safe, since we're always called in the context of the same
process as this new thread. */
int pid = pid_of (current_inferior);
ptid = ptid_build (pid, lwpid, 0);
}
That "safe" comment referred to linux_attach_lwp being called by
thread-db.c. But this was clearly missed when a new call to
linux_attach_lwp_1 was added to linux_attach. As a result,
current_inferior will be set to some random process, and non-initial
lwps of the second inferior get assigned the pid of the wrong
inferior. E.g., in the case of attaching to two inferiors, for the
second inferior (and so on), non-initial lwps of the second inferior
get assigned the pid of the first inferior. This doesn't trigger on
the first inferior, when current_inferior is NULL, add_thread switches
the current inferior to the newly added thread.
Rather than making linux_attach switch current_inferior temporarily
(thus avoiding further reliance on global state), or making
linux_attach_lwp_1 get the tgid from /proc, which add extra syscalls,
and will be wrong in case of the user having originally attached
directly to a non-tgid lwp, and then that lwp spawning new clones (the
ptid.pid field of further new clones should be the same as the
original lwp's pid, which is not the tgid), we note that callers of
linux_attach_lwp/linux_attach_lwp_1 always have the right pid handy
already, so they can pass it down along with the lwpid.
The only other reason for the "initial" parameter is to error out
instead of warn in case of attach failure, when we're first attaching
to a process. There are only three callers of
linux_attach_lwp/linux_attach_lwp_1, and each wants to print a
different warn/error string, so we can just move the error/warn out of
linux_attach_lwp_1 to the callers, thus getting rid of the "initial"
parameter.
There really nothing gdbserver-specific about attaching to two
threaded processes, so this adds a new test under gdb.multi/. The
test passes cleanly against the native GNU/Linux target, but
fails/triggers the bug against GDBserver (before the patch), with the
native-extended-remote board (as plain remote doesn't support
multi-process).
Tested on x86_64 Fedora 17, with the native-extended-gdbserver board.
gdb/gdbserver/
2014-04-25 Pedro Alves <palves@redhat.com>
PR server/16255
* linux-low.c (linux_attach_fail_reason_string): New function.
(linux_attach_lwp): Delete.
(linux_attach_lwp_1): Rename to ...
(linux_attach_lwp): ... this. Take a ptid instead of a pid as
argument. Remove "initial" parameter. Return int instead of
void. Don't error or warn here.
(linux_attach): Adjust to call linux_attach_lwp. Call error on
failure to attach to the tgid. Call warning when failing to
attach to an lwp.
* linux-low.h (linux_attach_lwp): Take a ptid instead of a pid as
argument. Remove "initial" parameter. Return int instead of
void. Don't error or warn here.
(linux_attach_fail_reason_string): New declaration.
* thread-db.c (attach_thread): Adjust to linux_attach_lwp's
interface change. Use linux_attach_fail_reason_string.
gdb/
2014-04-25 Pedro Alves <palves@redhat.com>
PR server/16255
* common/linux-ptrace.c (linux_ptrace_attach_warnings): Rename to ...
(linux_ptrace_attach_fail_reason): ... this. Remove "warning: "
and newline from built string.
* common/linux-ptrace.h (linux_ptrace_attach_warnings): Rename to ...
(linux_ptrace_attach_fail_reason): ... this.
* linux-nat.c (linux_nat_attach): Adjust to use
linux_ptrace_attach_fail_reason.
gdb/testsuite/
2014-04-25 Simon Marchi <simon.marchi@ericsson.com>
Pedro Alves <palves@redhat.com>
PR server/16255
* gdb.multi/multi-attach.c: New file.
* gdb.multi/multi-attach.exp: New file.
2014-04-25 20:07:33 +02:00
|
|
|
linux_ptrace_attach_fail_reason (pid_t pid, struct buffer *buffer)
|
2012-03-13 16:02:25 +01:00
|
|
|
{
|
|
|
|
pid_t tracerpid;
|
|
|
|
|
Linux: on attach, attach to lwps listed under /proc/$pid/task/
... instead of relying on libthread_db.
I wrote a test that attaches to a program that constantly spawns
short-lived threads, which exposed several issues. This is one of
them.
On Linux, we need to attach to all threads of a process (thread group)
individually. We currently rely on libthread_db to list the threads,
but that is problematic, because libthread_db relies on reading data
structures out of the inferior (which may well be corrupted). If
threads are being created or exiting just while we try to attach, we
may trip on inconsistencies in the inferior's thread list. To work
around that, when we see a seemingly corrupt list, we currently retry
a few times:
static void
thread_db_find_new_threads_2 (ptid_t ptid, int until_no_new)
{
...
if (until_no_new)
{
/* Require 4 successive iterations which do not find any new threads.
The 4 is a heuristic: there is an inherent race here, and I have
seen that 2 iterations in a row are not always sufficient to
"capture" all threads. */
...
That heuristic may well fail, and when it does, we end up with threads
in the program that aren't under GDB's control. That's obviously bad
and results in quite mistifying failures, like e.g., the process dying
for seeminly no reason when a thread that wasn't attached trips on a
breakpoint.
There's really no reason to rely on libthread_db for this nowadays
when we have /proc mounted. In that case, which is the usual case, we
can list the LWPs from /proc/PID/task/. In fact, GDBserver is already
doing this. The patch factors out that code that knows to walk the
task/ directory out of GDBserver, and makes GDB use it too.
Like GDBserver, the patch makes GDB attach to LWPs and _not_ wait for
them to stop immediately. Instead, we just tag the LWP as having an
expected stop. Because we can only set the ptrace options when the
thread stops, we need a new flag in the lwp structure to keep track of
whether we've already set the ptrace options, just like in GDBserver.
Note that nothing issues any ptrace command to the threads between the
PTRACE_ATTACH and the stop, so this is safe (unlike one scenario
described in gdbserver's linux-low.c).
When we attach to a program that has threads exiting while we attach,
it's easy to race with a thread just exiting as we try to attach to
it, like:
#1 - get current list of threads
#2 - attach to each listed thread
#3 - ooops, attach failed, thread is already gone
As this is pretty normal, we shouldn't be issuing a scary warning in
step #3.
When #3 happens, PTRACE_ATTACH usually fails with ESRCH, but sometimes
we'll see EPERM as well. That happens when the kernel still has the
thread in its task list, but the thread is marked as dead.
Unfortunately, EPERM is ambiguous and we'll get it also on other
scenarios where the thread isn't dead, and in those cases, it's useful
to get a warning. To distiguish the cases, when we get an EPERM
failure, we open /proc/PID/status, and check the thread's state -- if
the /proc file no longer exists, or the state is "Z (Zombie)" or "X
(Dead)", we ignore the EPERM error silently; otherwise, we'll warn.
Unfortunately, there seems to be a kernel race here. Sometimes I get
EPERM, and then the /proc state still indicates "R (Running)"... If
we wait a bit and retry, we do end up seeing X or Z state, or get an
ESRCH. I thought of making GDB retry the attach a few times, but even
with a 500ms wait and 4 retries, I still see the warning sometimes. I
haven't been able to identify the kernel path that causes this yet,
but in any case, it looks like a kernel bug to me. As this just
results failure to suppress a warning that we've been printing since
about forever anyway, I'm just making the test cope with it, and issue
an XFAIL.
gdb/gdbserver/
2015-01-09 Pedro Alves <palves@redhat.com>
* linux-low.c (linux_attach_fail_reason_string): Move to
nat/linux-ptrace.c, and rename.
(linux_attach_lwp): Update comment.
(attach_proc_task_lwp_callback): New function.
(linux_attach): Adjust to rename and use
linux_proc_attach_tgid_threads.
(linux_attach_fail_reason_string): Delete declaration.
gdb/
2015-01-09 Pedro Alves <palves@redhat.com>
* linux-nat.c (attach_proc_task_lwp_callback): New function.
(linux_nat_attach): Use linux_proc_attach_tgid_threads.
(wait_lwp, linux_nat_filter_event): If not set yet, set the lwp's
ptrace option flags.
* linux-nat.h (struct lwp_info) <must_set_ptrace_flags>: New
field.
* nat/linux-procfs.c: Include <dirent.h>.
(linux_proc_get_int): New parameter "warn". Handle it.
(linux_proc_get_tgid): Adjust.
(linux_proc_get_tracerpid): Rename to ...
(linux_proc_get_tracerpid_nowarn): ... this.
(linux_proc_pid_get_state): New function, factored out from
(linux_proc_pid_has_state): ... this. Add new parameter "warn"
and handle it.
(linux_proc_pid_is_gone): New function.
(linux_proc_pid_is_stopped): Adjust.
(linux_proc_pid_is_zombie_maybe_warn)
(linux_proc_pid_is_zombie_nowarn): New functions.
(linux_proc_pid_is_zombie): Use
linux_proc_pid_is_zombie_maybe_warn.
(linux_proc_attach_tgid_threads): New function.
* nat/linux-procfs.h (linux_proc_get_tgid): Update comment.
(linux_proc_get_tracerpid): Rename to ...
(linux_proc_get_tracerpid_nowarn): ... this, and update comment.
(linux_proc_pid_is_gone): New declaration.
(linux_proc_pid_is_zombie): Update comment.
(linux_proc_pid_is_zombie_nowarn): New declaration.
(linux_proc_attach_lwp_func): New typedef.
(linux_proc_attach_tgid_threads): New declaration.
* nat/linux-ptrace.c (linux_ptrace_attach_fail_reason): Adjust to
use nowarn functions.
(linux_ptrace_attach_fail_reason_string): Move here from
gdbserver/linux-low.c and rename.
(ptrace_supports_feature): If the current ptrace options are not
known yet, check them now, instead of asserting.
* nat/linux-ptrace.h (linux_ptrace_attach_fail_reason_string):
Declare.
2014-12-16 17:12:24 +01:00
|
|
|
tracerpid = linux_proc_get_tracerpid_nowarn (pid);
|
2012-03-13 16:02:25 +01:00
|
|
|
if (tracerpid > 0)
|
PR server/16255: gdbserver cannot attach to a second inferior that is multi-threaded.
On Linux, we need to explicitly ptrace attach to all lwps of a
process. Because GDB might not be connected yet when an attach is
requested, and thus it may not be possible to activate thread_db, as
that requires access to symbols (IOW, gdbserver --attach), a while ago
we make linux_attach loop over the lwps as listed by /proc/PID/task to
find the lwps to attach to.
linux_attach_lwp_1 has:
...
if (initial)
/* If lwp is the tgid, we handle adding existing threads later.
Otherwise we just add lwp without bothering about any other
threads. */
ptid = ptid_build (lwpid, lwpid, 0);
else
{
/* Note that extracting the pid from the current inferior is
safe, since we're always called in the context of the same
process as this new thread. */
int pid = pid_of (current_inferior);
ptid = ptid_build (pid, lwpid, 0);
}
That "safe" comment referred to linux_attach_lwp being called by
thread-db.c. But this was clearly missed when a new call to
linux_attach_lwp_1 was added to linux_attach. As a result,
current_inferior will be set to some random process, and non-initial
lwps of the second inferior get assigned the pid of the wrong
inferior. E.g., in the case of attaching to two inferiors, for the
second inferior (and so on), non-initial lwps of the second inferior
get assigned the pid of the first inferior. This doesn't trigger on
the first inferior, when current_inferior is NULL, add_thread switches
the current inferior to the newly added thread.
Rather than making linux_attach switch current_inferior temporarily
(thus avoiding further reliance on global state), or making
linux_attach_lwp_1 get the tgid from /proc, which add extra syscalls,
and will be wrong in case of the user having originally attached
directly to a non-tgid lwp, and then that lwp spawning new clones (the
ptid.pid field of further new clones should be the same as the
original lwp's pid, which is not the tgid), we note that callers of
linux_attach_lwp/linux_attach_lwp_1 always have the right pid handy
already, so they can pass it down along with the lwpid.
The only other reason for the "initial" parameter is to error out
instead of warn in case of attach failure, when we're first attaching
to a process. There are only three callers of
linux_attach_lwp/linux_attach_lwp_1, and each wants to print a
different warn/error string, so we can just move the error/warn out of
linux_attach_lwp_1 to the callers, thus getting rid of the "initial"
parameter.
There really nothing gdbserver-specific about attaching to two
threaded processes, so this adds a new test under gdb.multi/. The
test passes cleanly against the native GNU/Linux target, but
fails/triggers the bug against GDBserver (before the patch), with the
native-extended-remote board (as plain remote doesn't support
multi-process).
Tested on x86_64 Fedora 17, with the native-extended-gdbserver board.
gdb/gdbserver/
2014-04-25 Pedro Alves <palves@redhat.com>
PR server/16255
* linux-low.c (linux_attach_fail_reason_string): New function.
(linux_attach_lwp): Delete.
(linux_attach_lwp_1): Rename to ...
(linux_attach_lwp): ... this. Take a ptid instead of a pid as
argument. Remove "initial" parameter. Return int instead of
void. Don't error or warn here.
(linux_attach): Adjust to call linux_attach_lwp. Call error on
failure to attach to the tgid. Call warning when failing to
attach to an lwp.
* linux-low.h (linux_attach_lwp): Take a ptid instead of a pid as
argument. Remove "initial" parameter. Return int instead of
void. Don't error or warn here.
(linux_attach_fail_reason_string): New declaration.
* thread-db.c (attach_thread): Adjust to linux_attach_lwp's
interface change. Use linux_attach_fail_reason_string.
gdb/
2014-04-25 Pedro Alves <palves@redhat.com>
PR server/16255
* common/linux-ptrace.c (linux_ptrace_attach_warnings): Rename to ...
(linux_ptrace_attach_fail_reason): ... this. Remove "warning: "
and newline from built string.
* common/linux-ptrace.h (linux_ptrace_attach_warnings): Rename to ...
(linux_ptrace_attach_fail_reason): ... this.
* linux-nat.c (linux_nat_attach): Adjust to use
linux_ptrace_attach_fail_reason.
gdb/testsuite/
2014-04-25 Simon Marchi <simon.marchi@ericsson.com>
Pedro Alves <palves@redhat.com>
PR server/16255
* gdb.multi/multi-attach.c: New file.
* gdb.multi/multi-attach.exp: New file.
2014-04-25 20:07:33 +02:00
|
|
|
buffer_xml_printf (buffer, _("process %d is already traced "
|
|
|
|
"by process %d"),
|
2012-03-13 16:02:25 +01:00
|
|
|
(int) pid, (int) tracerpid);
|
|
|
|
|
Linux: on attach, attach to lwps listed under /proc/$pid/task/
... instead of relying on libthread_db.
I wrote a test that attaches to a program that constantly spawns
short-lived threads, which exposed several issues. This is one of
them.
On Linux, we need to attach to all threads of a process (thread group)
individually. We currently rely on libthread_db to list the threads,
but that is problematic, because libthread_db relies on reading data
structures out of the inferior (which may well be corrupted). If
threads are being created or exiting just while we try to attach, we
may trip on inconsistencies in the inferior's thread list. To work
around that, when we see a seemingly corrupt list, we currently retry
a few times:
static void
thread_db_find_new_threads_2 (ptid_t ptid, int until_no_new)
{
...
if (until_no_new)
{
/* Require 4 successive iterations which do not find any new threads.
The 4 is a heuristic: there is an inherent race here, and I have
seen that 2 iterations in a row are not always sufficient to
"capture" all threads. */
...
That heuristic may well fail, and when it does, we end up with threads
in the program that aren't under GDB's control. That's obviously bad
and results in quite mistifying failures, like e.g., the process dying
for seeminly no reason when a thread that wasn't attached trips on a
breakpoint.
There's really no reason to rely on libthread_db for this nowadays
when we have /proc mounted. In that case, which is the usual case, we
can list the LWPs from /proc/PID/task/. In fact, GDBserver is already
doing this. The patch factors out that code that knows to walk the
task/ directory out of GDBserver, and makes GDB use it too.
Like GDBserver, the patch makes GDB attach to LWPs and _not_ wait for
them to stop immediately. Instead, we just tag the LWP as having an
expected stop. Because we can only set the ptrace options when the
thread stops, we need a new flag in the lwp structure to keep track of
whether we've already set the ptrace options, just like in GDBserver.
Note that nothing issues any ptrace command to the threads between the
PTRACE_ATTACH and the stop, so this is safe (unlike one scenario
described in gdbserver's linux-low.c).
When we attach to a program that has threads exiting while we attach,
it's easy to race with a thread just exiting as we try to attach to
it, like:
#1 - get current list of threads
#2 - attach to each listed thread
#3 - ooops, attach failed, thread is already gone
As this is pretty normal, we shouldn't be issuing a scary warning in
step #3.
When #3 happens, PTRACE_ATTACH usually fails with ESRCH, but sometimes
we'll see EPERM as well. That happens when the kernel still has the
thread in its task list, but the thread is marked as dead.
Unfortunately, EPERM is ambiguous and we'll get it also on other
scenarios where the thread isn't dead, and in those cases, it's useful
to get a warning. To distiguish the cases, when we get an EPERM
failure, we open /proc/PID/status, and check the thread's state -- if
the /proc file no longer exists, or the state is "Z (Zombie)" or "X
(Dead)", we ignore the EPERM error silently; otherwise, we'll warn.
Unfortunately, there seems to be a kernel race here. Sometimes I get
EPERM, and then the /proc state still indicates "R (Running)"... If
we wait a bit and retry, we do end up seeing X or Z state, or get an
ESRCH. I thought of making GDB retry the attach a few times, but even
with a 500ms wait and 4 retries, I still see the warning sometimes. I
haven't been able to identify the kernel path that causes this yet,
but in any case, it looks like a kernel bug to me. As this just
results failure to suppress a warning that we've been printing since
about forever anyway, I'm just making the test cope with it, and issue
an XFAIL.
gdb/gdbserver/
2015-01-09 Pedro Alves <palves@redhat.com>
* linux-low.c (linux_attach_fail_reason_string): Move to
nat/linux-ptrace.c, and rename.
(linux_attach_lwp): Update comment.
(attach_proc_task_lwp_callback): New function.
(linux_attach): Adjust to rename and use
linux_proc_attach_tgid_threads.
(linux_attach_fail_reason_string): Delete declaration.
gdb/
2015-01-09 Pedro Alves <palves@redhat.com>
* linux-nat.c (attach_proc_task_lwp_callback): New function.
(linux_nat_attach): Use linux_proc_attach_tgid_threads.
(wait_lwp, linux_nat_filter_event): If not set yet, set the lwp's
ptrace option flags.
* linux-nat.h (struct lwp_info) <must_set_ptrace_flags>: New
field.
* nat/linux-procfs.c: Include <dirent.h>.
(linux_proc_get_int): New parameter "warn". Handle it.
(linux_proc_get_tgid): Adjust.
(linux_proc_get_tracerpid): Rename to ...
(linux_proc_get_tracerpid_nowarn): ... this.
(linux_proc_pid_get_state): New function, factored out from
(linux_proc_pid_has_state): ... this. Add new parameter "warn"
and handle it.
(linux_proc_pid_is_gone): New function.
(linux_proc_pid_is_stopped): Adjust.
(linux_proc_pid_is_zombie_maybe_warn)
(linux_proc_pid_is_zombie_nowarn): New functions.
(linux_proc_pid_is_zombie): Use
linux_proc_pid_is_zombie_maybe_warn.
(linux_proc_attach_tgid_threads): New function.
* nat/linux-procfs.h (linux_proc_get_tgid): Update comment.
(linux_proc_get_tracerpid): Rename to ...
(linux_proc_get_tracerpid_nowarn): ... this, and update comment.
(linux_proc_pid_is_gone): New declaration.
(linux_proc_pid_is_zombie): Update comment.
(linux_proc_pid_is_zombie_nowarn): New declaration.
(linux_proc_attach_lwp_func): New typedef.
(linux_proc_attach_tgid_threads): New declaration.
* nat/linux-ptrace.c (linux_ptrace_attach_fail_reason): Adjust to
use nowarn functions.
(linux_ptrace_attach_fail_reason_string): Move here from
gdbserver/linux-low.c and rename.
(ptrace_supports_feature): If the current ptrace options are not
known yet, check them now, instead of asserting.
* nat/linux-ptrace.h (linux_ptrace_attach_fail_reason_string):
Declare.
2014-12-16 17:12:24 +01:00
|
|
|
if (linux_proc_pid_is_zombie_nowarn (pid))
|
PR server/16255: gdbserver cannot attach to a second inferior that is multi-threaded.
On Linux, we need to explicitly ptrace attach to all lwps of a
process. Because GDB might not be connected yet when an attach is
requested, and thus it may not be possible to activate thread_db, as
that requires access to symbols (IOW, gdbserver --attach), a while ago
we make linux_attach loop over the lwps as listed by /proc/PID/task to
find the lwps to attach to.
linux_attach_lwp_1 has:
...
if (initial)
/* If lwp is the tgid, we handle adding existing threads later.
Otherwise we just add lwp without bothering about any other
threads. */
ptid = ptid_build (lwpid, lwpid, 0);
else
{
/* Note that extracting the pid from the current inferior is
safe, since we're always called in the context of the same
process as this new thread. */
int pid = pid_of (current_inferior);
ptid = ptid_build (pid, lwpid, 0);
}
That "safe" comment referred to linux_attach_lwp being called by
thread-db.c. But this was clearly missed when a new call to
linux_attach_lwp_1 was added to linux_attach. As a result,
current_inferior will be set to some random process, and non-initial
lwps of the second inferior get assigned the pid of the wrong
inferior. E.g., in the case of attaching to two inferiors, for the
second inferior (and so on), non-initial lwps of the second inferior
get assigned the pid of the first inferior. This doesn't trigger on
the first inferior, when current_inferior is NULL, add_thread switches
the current inferior to the newly added thread.
Rather than making linux_attach switch current_inferior temporarily
(thus avoiding further reliance on global state), or making
linux_attach_lwp_1 get the tgid from /proc, which add extra syscalls,
and will be wrong in case of the user having originally attached
directly to a non-tgid lwp, and then that lwp spawning new clones (the
ptid.pid field of further new clones should be the same as the
original lwp's pid, which is not the tgid), we note that callers of
linux_attach_lwp/linux_attach_lwp_1 always have the right pid handy
already, so they can pass it down along with the lwpid.
The only other reason for the "initial" parameter is to error out
instead of warn in case of attach failure, when we're first attaching
to a process. There are only three callers of
linux_attach_lwp/linux_attach_lwp_1, and each wants to print a
different warn/error string, so we can just move the error/warn out of
linux_attach_lwp_1 to the callers, thus getting rid of the "initial"
parameter.
There really nothing gdbserver-specific about attaching to two
threaded processes, so this adds a new test under gdb.multi/. The
test passes cleanly against the native GNU/Linux target, but
fails/triggers the bug against GDBserver (before the patch), with the
native-extended-remote board (as plain remote doesn't support
multi-process).
Tested on x86_64 Fedora 17, with the native-extended-gdbserver board.
gdb/gdbserver/
2014-04-25 Pedro Alves <palves@redhat.com>
PR server/16255
* linux-low.c (linux_attach_fail_reason_string): New function.
(linux_attach_lwp): Delete.
(linux_attach_lwp_1): Rename to ...
(linux_attach_lwp): ... this. Take a ptid instead of a pid as
argument. Remove "initial" parameter. Return int instead of
void. Don't error or warn here.
(linux_attach): Adjust to call linux_attach_lwp. Call error on
failure to attach to the tgid. Call warning when failing to
attach to an lwp.
* linux-low.h (linux_attach_lwp): Take a ptid instead of a pid as
argument. Remove "initial" parameter. Return int instead of
void. Don't error or warn here.
(linux_attach_fail_reason_string): New declaration.
* thread-db.c (attach_thread): Adjust to linux_attach_lwp's
interface change. Use linux_attach_fail_reason_string.
gdb/
2014-04-25 Pedro Alves <palves@redhat.com>
PR server/16255
* common/linux-ptrace.c (linux_ptrace_attach_warnings): Rename to ...
(linux_ptrace_attach_fail_reason): ... this. Remove "warning: "
and newline from built string.
* common/linux-ptrace.h (linux_ptrace_attach_warnings): Rename to ...
(linux_ptrace_attach_fail_reason): ... this.
* linux-nat.c (linux_nat_attach): Adjust to use
linux_ptrace_attach_fail_reason.
gdb/testsuite/
2014-04-25 Simon Marchi <simon.marchi@ericsson.com>
Pedro Alves <palves@redhat.com>
PR server/16255
* gdb.multi/multi-attach.c: New file.
* gdb.multi/multi-attach.exp: New file.
2014-04-25 20:07:33 +02:00
|
|
|
buffer_xml_printf (buffer, _("process %d is a zombie "
|
|
|
|
"- the process has already terminated"),
|
2012-03-13 16:02:25 +01:00
|
|
|
(int) pid);
|
|
|
|
}
|
2012-07-07 14:13:57 +02:00
|
|
|
|
Linux: on attach, attach to lwps listed under /proc/$pid/task/
... instead of relying on libthread_db.
I wrote a test that attaches to a program that constantly spawns
short-lived threads, which exposed several issues. This is one of
them.
On Linux, we need to attach to all threads of a process (thread group)
individually. We currently rely on libthread_db to list the threads,
but that is problematic, because libthread_db relies on reading data
structures out of the inferior (which may well be corrupted). If
threads are being created or exiting just while we try to attach, we
may trip on inconsistencies in the inferior's thread list. To work
around that, when we see a seemingly corrupt list, we currently retry
a few times:
static void
thread_db_find_new_threads_2 (ptid_t ptid, int until_no_new)
{
...
if (until_no_new)
{
/* Require 4 successive iterations which do not find any new threads.
The 4 is a heuristic: there is an inherent race here, and I have
seen that 2 iterations in a row are not always sufficient to
"capture" all threads. */
...
That heuristic may well fail, and when it does, we end up with threads
in the program that aren't under GDB's control. That's obviously bad
and results in quite mistifying failures, like e.g., the process dying
for seeminly no reason when a thread that wasn't attached trips on a
breakpoint.
There's really no reason to rely on libthread_db for this nowadays
when we have /proc mounted. In that case, which is the usual case, we
can list the LWPs from /proc/PID/task/. In fact, GDBserver is already
doing this. The patch factors out that code that knows to walk the
task/ directory out of GDBserver, and makes GDB use it too.
Like GDBserver, the patch makes GDB attach to LWPs and _not_ wait for
them to stop immediately. Instead, we just tag the LWP as having an
expected stop. Because we can only set the ptrace options when the
thread stops, we need a new flag in the lwp structure to keep track of
whether we've already set the ptrace options, just like in GDBserver.
Note that nothing issues any ptrace command to the threads between the
PTRACE_ATTACH and the stop, so this is safe (unlike one scenario
described in gdbserver's linux-low.c).
When we attach to a program that has threads exiting while we attach,
it's easy to race with a thread just exiting as we try to attach to
it, like:
#1 - get current list of threads
#2 - attach to each listed thread
#3 - ooops, attach failed, thread is already gone
As this is pretty normal, we shouldn't be issuing a scary warning in
step #3.
When #3 happens, PTRACE_ATTACH usually fails with ESRCH, but sometimes
we'll see EPERM as well. That happens when the kernel still has the
thread in its task list, but the thread is marked as dead.
Unfortunately, EPERM is ambiguous and we'll get it also on other
scenarios where the thread isn't dead, and in those cases, it's useful
to get a warning. To distiguish the cases, when we get an EPERM
failure, we open /proc/PID/status, and check the thread's state -- if
the /proc file no longer exists, or the state is "Z (Zombie)" or "X
(Dead)", we ignore the EPERM error silently; otherwise, we'll warn.
Unfortunately, there seems to be a kernel race here. Sometimes I get
EPERM, and then the /proc state still indicates "R (Running)"... If
we wait a bit and retry, we do end up seeing X or Z state, or get an
ESRCH. I thought of making GDB retry the attach a few times, but even
with a 500ms wait and 4 retries, I still see the warning sometimes. I
haven't been able to identify the kernel path that causes this yet,
but in any case, it looks like a kernel bug to me. As this just
results failure to suppress a warning that we've been printing since
about forever anyway, I'm just making the test cope with it, and issue
an XFAIL.
gdb/gdbserver/
2015-01-09 Pedro Alves <palves@redhat.com>
* linux-low.c (linux_attach_fail_reason_string): Move to
nat/linux-ptrace.c, and rename.
(linux_attach_lwp): Update comment.
(attach_proc_task_lwp_callback): New function.
(linux_attach): Adjust to rename and use
linux_proc_attach_tgid_threads.
(linux_attach_fail_reason_string): Delete declaration.
gdb/
2015-01-09 Pedro Alves <palves@redhat.com>
* linux-nat.c (attach_proc_task_lwp_callback): New function.
(linux_nat_attach): Use linux_proc_attach_tgid_threads.
(wait_lwp, linux_nat_filter_event): If not set yet, set the lwp's
ptrace option flags.
* linux-nat.h (struct lwp_info) <must_set_ptrace_flags>: New
field.
* nat/linux-procfs.c: Include <dirent.h>.
(linux_proc_get_int): New parameter "warn". Handle it.
(linux_proc_get_tgid): Adjust.
(linux_proc_get_tracerpid): Rename to ...
(linux_proc_get_tracerpid_nowarn): ... this.
(linux_proc_pid_get_state): New function, factored out from
(linux_proc_pid_has_state): ... this. Add new parameter "warn"
and handle it.
(linux_proc_pid_is_gone): New function.
(linux_proc_pid_is_stopped): Adjust.
(linux_proc_pid_is_zombie_maybe_warn)
(linux_proc_pid_is_zombie_nowarn): New functions.
(linux_proc_pid_is_zombie): Use
linux_proc_pid_is_zombie_maybe_warn.
(linux_proc_attach_tgid_threads): New function.
* nat/linux-procfs.h (linux_proc_get_tgid): Update comment.
(linux_proc_get_tracerpid): Rename to ...
(linux_proc_get_tracerpid_nowarn): ... this, and update comment.
(linux_proc_pid_is_gone): New declaration.
(linux_proc_pid_is_zombie): Update comment.
(linux_proc_pid_is_zombie_nowarn): New declaration.
(linux_proc_attach_lwp_func): New typedef.
(linux_proc_attach_tgid_threads): New declaration.
* nat/linux-ptrace.c (linux_ptrace_attach_fail_reason): Adjust to
use nowarn functions.
(linux_ptrace_attach_fail_reason_string): Move here from
gdbserver/linux-low.c and rename.
(ptrace_supports_feature): If the current ptrace options are not
known yet, check them now, instead of asserting.
* nat/linux-ptrace.h (linux_ptrace_attach_fail_reason_string):
Declare.
2014-12-16 17:12:24 +01:00
|
|
|
/* See linux-ptrace.h. */
|
|
|
|
|
|
|
|
char *
|
|
|
|
linux_ptrace_attach_fail_reason_string (ptid_t ptid, int err)
|
|
|
|
{
|
|
|
|
static char *reason_string;
|
|
|
|
struct buffer buffer;
|
|
|
|
char *warnings;
|
|
|
|
long lwpid = ptid_get_lwp (ptid);
|
|
|
|
|
|
|
|
xfree (reason_string);
|
|
|
|
|
|
|
|
buffer_init (&buffer);
|
|
|
|
linux_ptrace_attach_fail_reason (lwpid, &buffer);
|
|
|
|
buffer_grow_str0 (&buffer, "");
|
|
|
|
warnings = buffer_finish (&buffer);
|
|
|
|
if (warnings[0] != '\0')
|
|
|
|
reason_string = xstrprintf ("%s (%d), %s",
|
2015-01-20 18:38:23 +01:00
|
|
|
safe_strerror (err), err, warnings);
|
Linux: on attach, attach to lwps listed under /proc/$pid/task/
... instead of relying on libthread_db.
I wrote a test that attaches to a program that constantly spawns
short-lived threads, which exposed several issues. This is one of
them.
On Linux, we need to attach to all threads of a process (thread group)
individually. We currently rely on libthread_db to list the threads,
but that is problematic, because libthread_db relies on reading data
structures out of the inferior (which may well be corrupted). If
threads are being created or exiting just while we try to attach, we
may trip on inconsistencies in the inferior's thread list. To work
around that, when we see a seemingly corrupt list, we currently retry
a few times:
static void
thread_db_find_new_threads_2 (ptid_t ptid, int until_no_new)
{
...
if (until_no_new)
{
/* Require 4 successive iterations which do not find any new threads.
The 4 is a heuristic: there is an inherent race here, and I have
seen that 2 iterations in a row are not always sufficient to
"capture" all threads. */
...
That heuristic may well fail, and when it does, we end up with threads
in the program that aren't under GDB's control. That's obviously bad
and results in quite mistifying failures, like e.g., the process dying
for seeminly no reason when a thread that wasn't attached trips on a
breakpoint.
There's really no reason to rely on libthread_db for this nowadays
when we have /proc mounted. In that case, which is the usual case, we
can list the LWPs from /proc/PID/task/. In fact, GDBserver is already
doing this. The patch factors out that code that knows to walk the
task/ directory out of GDBserver, and makes GDB use it too.
Like GDBserver, the patch makes GDB attach to LWPs and _not_ wait for
them to stop immediately. Instead, we just tag the LWP as having an
expected stop. Because we can only set the ptrace options when the
thread stops, we need a new flag in the lwp structure to keep track of
whether we've already set the ptrace options, just like in GDBserver.
Note that nothing issues any ptrace command to the threads between the
PTRACE_ATTACH and the stop, so this is safe (unlike one scenario
described in gdbserver's linux-low.c).
When we attach to a program that has threads exiting while we attach,
it's easy to race with a thread just exiting as we try to attach to
it, like:
#1 - get current list of threads
#2 - attach to each listed thread
#3 - ooops, attach failed, thread is already gone
As this is pretty normal, we shouldn't be issuing a scary warning in
step #3.
When #3 happens, PTRACE_ATTACH usually fails with ESRCH, but sometimes
we'll see EPERM as well. That happens when the kernel still has the
thread in its task list, but the thread is marked as dead.
Unfortunately, EPERM is ambiguous and we'll get it also on other
scenarios where the thread isn't dead, and in those cases, it's useful
to get a warning. To distiguish the cases, when we get an EPERM
failure, we open /proc/PID/status, and check the thread's state -- if
the /proc file no longer exists, or the state is "Z (Zombie)" or "X
(Dead)", we ignore the EPERM error silently; otherwise, we'll warn.
Unfortunately, there seems to be a kernel race here. Sometimes I get
EPERM, and then the /proc state still indicates "R (Running)"... If
we wait a bit and retry, we do end up seeing X or Z state, or get an
ESRCH. I thought of making GDB retry the attach a few times, but even
with a 500ms wait and 4 retries, I still see the warning sometimes. I
haven't been able to identify the kernel path that causes this yet,
but in any case, it looks like a kernel bug to me. As this just
results failure to suppress a warning that we've been printing since
about forever anyway, I'm just making the test cope with it, and issue
an XFAIL.
gdb/gdbserver/
2015-01-09 Pedro Alves <palves@redhat.com>
* linux-low.c (linux_attach_fail_reason_string): Move to
nat/linux-ptrace.c, and rename.
(linux_attach_lwp): Update comment.
(attach_proc_task_lwp_callback): New function.
(linux_attach): Adjust to rename and use
linux_proc_attach_tgid_threads.
(linux_attach_fail_reason_string): Delete declaration.
gdb/
2015-01-09 Pedro Alves <palves@redhat.com>
* linux-nat.c (attach_proc_task_lwp_callback): New function.
(linux_nat_attach): Use linux_proc_attach_tgid_threads.
(wait_lwp, linux_nat_filter_event): If not set yet, set the lwp's
ptrace option flags.
* linux-nat.h (struct lwp_info) <must_set_ptrace_flags>: New
field.
* nat/linux-procfs.c: Include <dirent.h>.
(linux_proc_get_int): New parameter "warn". Handle it.
(linux_proc_get_tgid): Adjust.
(linux_proc_get_tracerpid): Rename to ...
(linux_proc_get_tracerpid_nowarn): ... this.
(linux_proc_pid_get_state): New function, factored out from
(linux_proc_pid_has_state): ... this. Add new parameter "warn"
and handle it.
(linux_proc_pid_is_gone): New function.
(linux_proc_pid_is_stopped): Adjust.
(linux_proc_pid_is_zombie_maybe_warn)
(linux_proc_pid_is_zombie_nowarn): New functions.
(linux_proc_pid_is_zombie): Use
linux_proc_pid_is_zombie_maybe_warn.
(linux_proc_attach_tgid_threads): New function.
* nat/linux-procfs.h (linux_proc_get_tgid): Update comment.
(linux_proc_get_tracerpid): Rename to ...
(linux_proc_get_tracerpid_nowarn): ... this, and update comment.
(linux_proc_pid_is_gone): New declaration.
(linux_proc_pid_is_zombie): Update comment.
(linux_proc_pid_is_zombie_nowarn): New declaration.
(linux_proc_attach_lwp_func): New typedef.
(linux_proc_attach_tgid_threads): New declaration.
* nat/linux-ptrace.c (linux_ptrace_attach_fail_reason): Adjust to
use nowarn functions.
(linux_ptrace_attach_fail_reason_string): Move here from
gdbserver/linux-low.c and rename.
(ptrace_supports_feature): If the current ptrace options are not
known yet, check them now, instead of asserting.
* nat/linux-ptrace.h (linux_ptrace_attach_fail_reason_string):
Declare.
2014-12-16 17:12:24 +01:00
|
|
|
else
|
|
|
|
reason_string = xstrprintf ("%s (%d)",
|
2015-01-20 18:38:23 +01:00
|
|
|
safe_strerror (err), err);
|
Linux: on attach, attach to lwps listed under /proc/$pid/task/
... instead of relying on libthread_db.
I wrote a test that attaches to a program that constantly spawns
short-lived threads, which exposed several issues. This is one of
them.
On Linux, we need to attach to all threads of a process (thread group)
individually. We currently rely on libthread_db to list the threads,
but that is problematic, because libthread_db relies on reading data
structures out of the inferior (which may well be corrupted). If
threads are being created or exiting just while we try to attach, we
may trip on inconsistencies in the inferior's thread list. To work
around that, when we see a seemingly corrupt list, we currently retry
a few times:
static void
thread_db_find_new_threads_2 (ptid_t ptid, int until_no_new)
{
...
if (until_no_new)
{
/* Require 4 successive iterations which do not find any new threads.
The 4 is a heuristic: there is an inherent race here, and I have
seen that 2 iterations in a row are not always sufficient to
"capture" all threads. */
...
That heuristic may well fail, and when it does, we end up with threads
in the program that aren't under GDB's control. That's obviously bad
and results in quite mistifying failures, like e.g., the process dying
for seeminly no reason when a thread that wasn't attached trips on a
breakpoint.
There's really no reason to rely on libthread_db for this nowadays
when we have /proc mounted. In that case, which is the usual case, we
can list the LWPs from /proc/PID/task/. In fact, GDBserver is already
doing this. The patch factors out that code that knows to walk the
task/ directory out of GDBserver, and makes GDB use it too.
Like GDBserver, the patch makes GDB attach to LWPs and _not_ wait for
them to stop immediately. Instead, we just tag the LWP as having an
expected stop. Because we can only set the ptrace options when the
thread stops, we need a new flag in the lwp structure to keep track of
whether we've already set the ptrace options, just like in GDBserver.
Note that nothing issues any ptrace command to the threads between the
PTRACE_ATTACH and the stop, so this is safe (unlike one scenario
described in gdbserver's linux-low.c).
When we attach to a program that has threads exiting while we attach,
it's easy to race with a thread just exiting as we try to attach to
it, like:
#1 - get current list of threads
#2 - attach to each listed thread
#3 - ooops, attach failed, thread is already gone
As this is pretty normal, we shouldn't be issuing a scary warning in
step #3.
When #3 happens, PTRACE_ATTACH usually fails with ESRCH, but sometimes
we'll see EPERM as well. That happens when the kernel still has the
thread in its task list, but the thread is marked as dead.
Unfortunately, EPERM is ambiguous and we'll get it also on other
scenarios where the thread isn't dead, and in those cases, it's useful
to get a warning. To distiguish the cases, when we get an EPERM
failure, we open /proc/PID/status, and check the thread's state -- if
the /proc file no longer exists, or the state is "Z (Zombie)" or "X
(Dead)", we ignore the EPERM error silently; otherwise, we'll warn.
Unfortunately, there seems to be a kernel race here. Sometimes I get
EPERM, and then the /proc state still indicates "R (Running)"... If
we wait a bit and retry, we do end up seeing X or Z state, or get an
ESRCH. I thought of making GDB retry the attach a few times, but even
with a 500ms wait and 4 retries, I still see the warning sometimes. I
haven't been able to identify the kernel path that causes this yet,
but in any case, it looks like a kernel bug to me. As this just
results failure to suppress a warning that we've been printing since
about forever anyway, I'm just making the test cope with it, and issue
an XFAIL.
gdb/gdbserver/
2015-01-09 Pedro Alves <palves@redhat.com>
* linux-low.c (linux_attach_fail_reason_string): Move to
nat/linux-ptrace.c, and rename.
(linux_attach_lwp): Update comment.
(attach_proc_task_lwp_callback): New function.
(linux_attach): Adjust to rename and use
linux_proc_attach_tgid_threads.
(linux_attach_fail_reason_string): Delete declaration.
gdb/
2015-01-09 Pedro Alves <palves@redhat.com>
* linux-nat.c (attach_proc_task_lwp_callback): New function.
(linux_nat_attach): Use linux_proc_attach_tgid_threads.
(wait_lwp, linux_nat_filter_event): If not set yet, set the lwp's
ptrace option flags.
* linux-nat.h (struct lwp_info) <must_set_ptrace_flags>: New
field.
* nat/linux-procfs.c: Include <dirent.h>.
(linux_proc_get_int): New parameter "warn". Handle it.
(linux_proc_get_tgid): Adjust.
(linux_proc_get_tracerpid): Rename to ...
(linux_proc_get_tracerpid_nowarn): ... this.
(linux_proc_pid_get_state): New function, factored out from
(linux_proc_pid_has_state): ... this. Add new parameter "warn"
and handle it.
(linux_proc_pid_is_gone): New function.
(linux_proc_pid_is_stopped): Adjust.
(linux_proc_pid_is_zombie_maybe_warn)
(linux_proc_pid_is_zombie_nowarn): New functions.
(linux_proc_pid_is_zombie): Use
linux_proc_pid_is_zombie_maybe_warn.
(linux_proc_attach_tgid_threads): New function.
* nat/linux-procfs.h (linux_proc_get_tgid): Update comment.
(linux_proc_get_tracerpid): Rename to ...
(linux_proc_get_tracerpid_nowarn): ... this, and update comment.
(linux_proc_pid_is_gone): New declaration.
(linux_proc_pid_is_zombie): Update comment.
(linux_proc_pid_is_zombie_nowarn): New declaration.
(linux_proc_attach_lwp_func): New typedef.
(linux_proc_attach_tgid_threads): New declaration.
* nat/linux-ptrace.c (linux_ptrace_attach_fail_reason): Adjust to
use nowarn functions.
(linux_ptrace_attach_fail_reason_string): Move here from
gdbserver/linux-low.c and rename.
(ptrace_supports_feature): If the current ptrace options are not
known yet, check them now, instead of asserting.
* nat/linux-ptrace.h (linux_ptrace_attach_fail_reason_string):
Declare.
2014-12-16 17:12:24 +01:00
|
|
|
xfree (warnings);
|
|
|
|
return reason_string;
|
|
|
|
}
|
|
|
|
|
2012-09-17 20:27:58 +02:00
|
|
|
#if defined __i386__ || defined __x86_64__
|
2012-07-07 14:13:57 +02:00
|
|
|
|
|
|
|
/* Address of the 'ret' instruction in asm code block below. */
|
2015-02-09 15:59:08 +01:00
|
|
|
EXTERN_C void linux_ptrace_test_ret_to_nx_instr (void);
|
2012-07-07 14:13:57 +02:00
|
|
|
|
|
|
|
#include <sys/reg.h>
|
|
|
|
#include <sys/mman.h>
|
|
|
|
#include <signal.h>
|
|
|
|
|
2012-09-17 20:27:58 +02:00
|
|
|
#endif /* defined __i386__ || defined __x86_64__ */
|
2012-07-07 14:13:57 +02:00
|
|
|
|
|
|
|
/* Test broken off-trunk Linux kernel patchset for NX support on i386. It was
|
2012-09-17 20:27:58 +02:00
|
|
|
removed in Fedora kernel 88fa1f0332d188795ed73d7ac2b1564e11a0b4cd.
|
|
|
|
|
|
|
|
Test also x86_64 arch for PaX support. */
|
2012-07-07 14:13:57 +02:00
|
|
|
|
|
|
|
static void
|
|
|
|
linux_ptrace_test_ret_to_nx (void)
|
|
|
|
{
|
2012-09-17 20:27:58 +02:00
|
|
|
#if defined __i386__ || defined __x86_64__
|
2012-07-07 14:13:57 +02:00
|
|
|
pid_t child, got_pid;
|
|
|
|
gdb_byte *return_address, *pc;
|
|
|
|
long l;
|
2013-03-10 19:07:57 +01:00
|
|
|
int status, kill_status;
|
2012-07-07 14:13:57 +02:00
|
|
|
|
|
|
|
return_address = mmap (NULL, 2, PROT_READ | PROT_WRITE,
|
|
|
|
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
|
|
|
|
if (return_address == MAP_FAILED)
|
|
|
|
{
|
|
|
|
warning (_("linux_ptrace_test_ret_to_nx: Cannot mmap: %s"),
|
2015-01-20 18:38:23 +01:00
|
|
|
safe_strerror (errno));
|
2012-07-07 14:13:57 +02:00
|
|
|
return;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* Put there 'int3'. */
|
|
|
|
*return_address = 0xcc;
|
|
|
|
|
|
|
|
child = fork ();
|
|
|
|
switch (child)
|
|
|
|
{
|
|
|
|
case -1:
|
|
|
|
warning (_("linux_ptrace_test_ret_to_nx: Cannot fork: %s"),
|
2015-01-20 18:38:23 +01:00
|
|
|
safe_strerror (errno));
|
2012-07-07 14:13:57 +02:00
|
|
|
return;
|
|
|
|
|
|
|
|
case 0:
|
2013-08-23 01:46:30 +02:00
|
|
|
l = ptrace (PTRACE_TRACEME, 0, (PTRACE_TYPE_ARG3) NULL,
|
|
|
|
(PTRACE_TYPE_ARG4) NULL);
|
2012-07-07 14:13:57 +02:00
|
|
|
if (l != 0)
|
|
|
|
warning (_("linux_ptrace_test_ret_to_nx: Cannot PTRACE_TRACEME: %s"),
|
2015-01-20 18:38:23 +01:00
|
|
|
safe_strerror (errno));
|
2012-07-07 14:13:57 +02:00
|
|
|
else
|
|
|
|
{
|
2012-09-17 20:27:58 +02:00
|
|
|
#if defined __i386__
|
2012-07-07 14:13:57 +02:00
|
|
|
asm volatile ("pushl %0;"
|
|
|
|
".globl linux_ptrace_test_ret_to_nx_instr;"
|
|
|
|
"linux_ptrace_test_ret_to_nx_instr:"
|
|
|
|
"ret"
|
|
|
|
: : "r" (return_address) : "%esp", "memory");
|
2012-09-17 20:27:58 +02:00
|
|
|
#elif defined __x86_64__
|
|
|
|
asm volatile ("pushq %0;"
|
|
|
|
".globl linux_ptrace_test_ret_to_nx_instr;"
|
|
|
|
"linux_ptrace_test_ret_to_nx_instr:"
|
|
|
|
"ret"
|
2013-01-08 20:38:51 +01:00
|
|
|
: : "r" ((uint64_t) (uintptr_t) return_address)
|
|
|
|
: "%rsp", "memory");
|
2012-09-17 20:27:58 +02:00
|
|
|
#else
|
|
|
|
# error "!__i386__ && !__x86_64__"
|
|
|
|
#endif
|
2012-07-07 14:13:57 +02:00
|
|
|
gdb_assert_not_reached ("asm block did not terminate");
|
|
|
|
}
|
|
|
|
|
|
|
|
_exit (1);
|
|
|
|
}
|
|
|
|
|
2012-09-17 20:27:58 +02:00
|
|
|
errno = 0;
|
2012-07-07 14:13:57 +02:00
|
|
|
got_pid = waitpid (child, &status, 0);
|
2012-09-17 20:27:58 +02:00
|
|
|
if (got_pid != child)
|
|
|
|
{
|
|
|
|
warning (_("linux_ptrace_test_ret_to_nx: waitpid returned %ld: %s"),
|
2015-01-20 18:38:23 +01:00
|
|
|
(long) got_pid, safe_strerror (errno));
|
2012-09-17 20:27:58 +02:00
|
|
|
return;
|
|
|
|
}
|
|
|
|
|
|
|
|
if (WIFSIGNALED (status))
|
|
|
|
{
|
|
|
|
if (WTERMSIG (status) != SIGKILL)
|
|
|
|
warning (_("linux_ptrace_test_ret_to_nx: WTERMSIG %d is not SIGKILL!"),
|
|
|
|
(int) WTERMSIG (status));
|
|
|
|
else
|
|
|
|
warning (_("Cannot call inferior functions, Linux kernel PaX "
|
|
|
|
"protection forbids return to non-executable pages!"));
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
|
|
|
|
if (!WIFSTOPPED (status))
|
|
|
|
{
|
|
|
|
warning (_("linux_ptrace_test_ret_to_nx: status %d is not WIFSTOPPED!"),
|
|
|
|
status);
|
|
|
|
return;
|
|
|
|
}
|
2012-07-07 14:13:57 +02:00
|
|
|
|
|
|
|
/* We may get SIGSEGV due to missing PROT_EXEC of the return_address. */
|
2012-09-17 20:27:58 +02:00
|
|
|
if (WSTOPSIG (status) != SIGTRAP && WSTOPSIG (status) != SIGSEGV)
|
|
|
|
{
|
|
|
|
warning (_("linux_ptrace_test_ret_to_nx: "
|
|
|
|
"WSTOPSIG %d is neither SIGTRAP nor SIGSEGV!"),
|
|
|
|
(int) WSTOPSIG (status));
|
|
|
|
return;
|
|
|
|
}
|
2012-07-07 14:13:57 +02:00
|
|
|
|
|
|
|
errno = 0;
|
2012-09-17 20:27:58 +02:00
|
|
|
#if defined __i386__
|
2013-08-23 01:46:30 +02:00
|
|
|
l = ptrace (PTRACE_PEEKUSER, child, (PTRACE_TYPE_ARG3) (uintptr_t) (EIP * 4),
|
|
|
|
(PTRACE_TYPE_ARG4) NULL);
|
2012-09-17 20:27:58 +02:00
|
|
|
#elif defined __x86_64__
|
2013-08-23 01:46:30 +02:00
|
|
|
l = ptrace (PTRACE_PEEKUSER, child, (PTRACE_TYPE_ARG3) (uintptr_t) (RIP * 8),
|
|
|
|
(PTRACE_TYPE_ARG4) NULL);
|
2012-09-17 20:27:58 +02:00
|
|
|
#else
|
|
|
|
# error "!__i386__ && !__x86_64__"
|
|
|
|
#endif
|
|
|
|
if (errno != 0)
|
|
|
|
{
|
|
|
|
warning (_("linux_ptrace_test_ret_to_nx: Cannot PTRACE_PEEKUSER: %s"),
|
2015-01-20 18:38:23 +01:00
|
|
|
safe_strerror (errno));
|
2012-09-17 20:27:58 +02:00
|
|
|
return;
|
|
|
|
}
|
2012-07-07 14:13:57 +02:00
|
|
|
pc = (void *) (uintptr_t) l;
|
|
|
|
|
2013-03-10 19:07:57 +01:00
|
|
|
kill (child, SIGKILL);
|
2013-08-23 01:46:30 +02:00
|
|
|
ptrace (PTRACE_KILL, child, (PTRACE_TYPE_ARG3) NULL,
|
|
|
|
(PTRACE_TYPE_ARG4) NULL);
|
2013-03-10 19:07:57 +01:00
|
|
|
|
|
|
|
errno = 0;
|
|
|
|
got_pid = waitpid (child, &kill_status, 0);
|
|
|
|
if (got_pid != child)
|
2012-09-17 20:27:58 +02:00
|
|
|
{
|
2013-03-10 19:07:57 +01:00
|
|
|
warning (_("linux_ptrace_test_ret_to_nx: "
|
|
|
|
"PTRACE_KILL waitpid returned %ld: %s"),
|
2015-01-20 18:38:23 +01:00
|
|
|
(long) got_pid, safe_strerror (errno));
|
2012-09-17 20:27:58 +02:00
|
|
|
return;
|
|
|
|
}
|
2013-03-10 19:07:57 +01:00
|
|
|
if (!WIFSIGNALED (kill_status))
|
2012-07-07 14:13:57 +02:00
|
|
|
{
|
2013-03-10 19:07:57 +01:00
|
|
|
warning (_("linux_ptrace_test_ret_to_nx: "
|
|
|
|
"PTRACE_KILL status %d is not WIFSIGNALED!"),
|
|
|
|
status);
|
|
|
|
return;
|
2012-07-07 14:13:57 +02:00
|
|
|
}
|
|
|
|
|
|
|
|
/* + 1 is there as x86* stops after the 'int3' instruction. */
|
|
|
|
if (WSTOPSIG (status) == SIGTRAP && pc == return_address + 1)
|
|
|
|
{
|
|
|
|
/* PASS */
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* We may get SIGSEGV due to missing PROT_EXEC of the RETURN_ADDRESS page. */
|
|
|
|
if (WSTOPSIG (status) == SIGSEGV && pc == return_address)
|
|
|
|
{
|
|
|
|
/* PASS */
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
|
2012-09-17 20:27:58 +02:00
|
|
|
if ((void (*) (void)) pc != &linux_ptrace_test_ret_to_nx_instr)
|
|
|
|
warning (_("linux_ptrace_test_ret_to_nx: PC %p is neither near return "
|
|
|
|
"address %p nor is the return instruction %p!"),
|
|
|
|
pc, return_address, &linux_ptrace_test_ret_to_nx_instr);
|
|
|
|
else
|
2013-02-25 18:32:06 +01:00
|
|
|
warning (_("Cannot call inferior functions on this system - "
|
|
|
|
"Linux kernel with broken i386 NX (non-executable pages) "
|
|
|
|
"support detected!"));
|
2012-09-17 20:27:58 +02:00
|
|
|
#endif /* defined __i386__ || defined __x86_64__ */
|
2012-07-07 14:13:57 +02:00
|
|
|
}
|
|
|
|
|
2013-08-23 01:46:30 +02:00
|
|
|
/* Helper function to fork a process and make the child process call
|
|
|
|
the function FUNCTION, passing CHILD_STACK as parameter.
|
|
|
|
|
|
|
|
For MMU-less targets, clone is used instead of fork, and
|
|
|
|
CHILD_STACK is used as stack space for the cloned child. If NULL,
|
|
|
|
stack space is allocated via malloc (and subsequently passed to
|
|
|
|
FUNCTION). For MMU targets, CHILD_STACK is ignored. */
|
|
|
|
|
|
|
|
static int
|
|
|
|
linux_fork_to_function (gdb_byte *child_stack, void (*function) (gdb_byte *))
|
|
|
|
{
|
|
|
|
int child_pid;
|
|
|
|
|
|
|
|
/* Sanity check the function pointer. */
|
|
|
|
gdb_assert (function != NULL);
|
|
|
|
|
|
|
|
#if defined(__UCLIBC__) && defined(HAS_NOMMU)
|
|
|
|
#define STACK_SIZE 4096
|
|
|
|
|
|
|
|
if (child_stack == NULL)
|
|
|
|
child_stack = xmalloc (STACK_SIZE * 4);
|
|
|
|
|
|
|
|
/* Use CLONE_VM instead of fork, to support uClinux (no MMU). */
|
2013-08-23 04:34:34 +02:00
|
|
|
#ifdef __ia64__
|
2013-08-23 01:46:30 +02:00
|
|
|
child_pid = __clone2 (function, child_stack, STACK_SIZE,
|
|
|
|
CLONE_VM | SIGCHLD, child_stack + STACK_SIZE * 2);
|
2013-08-23 04:34:34 +02:00
|
|
|
#else /* !__ia64__ */
|
2013-08-23 01:46:30 +02:00
|
|
|
child_pid = clone (function, child_stack + STACK_SIZE,
|
|
|
|
CLONE_VM | SIGCHLD, child_stack + STACK_SIZE * 2);
|
2013-08-23 04:34:34 +02:00
|
|
|
#endif /* !__ia64__ */
|
2013-08-23 01:46:30 +02:00
|
|
|
#else /* !defined(__UCLIBC) && defined(HAS_NOMMU) */
|
|
|
|
child_pid = fork ();
|
|
|
|
|
|
|
|
if (child_pid == 0)
|
|
|
|
function (NULL);
|
|
|
|
#endif /* defined(__UCLIBC) && defined(HAS_NOMMU) */
|
|
|
|
|
|
|
|
if (child_pid == -1)
|
|
|
|
perror_with_name (("fork"));
|
|
|
|
|
|
|
|
return child_pid;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* A helper function for linux_check_ptrace_features, called after
|
|
|
|
the child forks a grandchild. */
|
|
|
|
|
|
|
|
static void
|
|
|
|
linux_grandchild_function (gdb_byte *child_stack)
|
|
|
|
{
|
|
|
|
/* Free any allocated stack. */
|
|
|
|
xfree (child_stack);
|
|
|
|
|
|
|
|
/* This code is only reacheable by the grandchild (child's child)
|
|
|
|
process. */
|
|
|
|
_exit (0);
|
|
|
|
}
|
|
|
|
|
|
|
|
/* A helper function for linux_check_ptrace_features, called after
|
|
|
|
the parent process forks a child. The child allows itself to
|
|
|
|
be traced by its parent. */
|
|
|
|
|
|
|
|
static void
|
|
|
|
linux_child_function (gdb_byte *child_stack)
|
|
|
|
{
|
|
|
|
ptrace (PTRACE_TRACEME, 0, (PTRACE_TYPE_ARG3) 0, (PTRACE_TYPE_ARG4) 0);
|
|
|
|
kill (getpid (), SIGSTOP);
|
|
|
|
|
|
|
|
/* Fork a grandchild. */
|
|
|
|
linux_fork_to_function (child_stack, linux_grandchild_function);
|
|
|
|
|
|
|
|
/* This code is only reacheable by the child (grandchild's parent)
|
|
|
|
process. */
|
|
|
|
_exit (0);
|
|
|
|
}
|
|
|
|
|
Always run the PTRACE_O_TRACESYSGOOD tests even if PTRACE_O_TRACEFORK is not supported.
If enabling PTRACE_O_TRACEFORK fails, we never test for
PTRACE_O_TRACESYSGOOD support. Before PTRACE_O_TRACESYSGOOD is checked,
we have:
/* First, set the PTRACE_O_TRACEFORK option. If this fails, we
know for sure that it is not supported. */
ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) PTRACE_O_TRACEFORK);
if (ret != 0)
{
ret = ptrace (PTRACE_KILL, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) 0);
if (ret != 0)
{
warning (_("linux_check_ptrace_features: failed to kill child"));
return;
}
ret = my_waitpid (child_pid, &status, 0);
if (ret != child_pid)
warning (_("linux_check_ptrace_features: failed "
"to wait for killed child"));
else if (!WIFSIGNALED (status))
warning (_("linux_check_ptrace_features: unexpected "
"wait status 0x%x from killed child"), status);
return; <<<<<<<<<<<<<<<<<
}
Note that early return. If PTRACE_O_TRACEFORK isn't supported, we're
not checking PTRACE_O_TRACESYSGOOD. This didn't use to be a problem
before the unification of this whole detection business in
linux-ptrace.c. Before, the sysgood detection was completely
separate:
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);
}
So we need to get back the decoupling somehow. I think it's cleaner
to split the seperate feature detections to separate functions. This
patch does that. The new functions are named for their counterparts
that existed before this code was moved to linux-ptrace.c.
Note I've used forward declarations for the new functions to make the
patch clearer, as otherwise the patch would look like I'd be adding a
bunch of new code. A reorder can be done in a follow up patch.
Tested on x86_64 Fedora 17.
gdb/
2013-10-03 Pedro Alves <palves@redhat.com>
* common/linux-ptrace.c (linux_check_ptrace_features): Factor out
the PTRACE_O_TRACESYSGOOD and PTRACE_O_TRACEFORK to separate
functions. Always test for PTRACE_O_TRACESYSGOOD even if
PTRACE_O_TRACEFORK is not supported.
(linux_test_for_tracesysgood): New function.
(linux_test_for_tracefork): New function, factored out from
linux_check_ptrace_features, and also don't kill child_pid here.
2013-10-03 12:13:34 +02:00
|
|
|
static void linux_test_for_tracesysgood (int child_pid);
|
|
|
|
static void linux_test_for_tracefork (int child_pid);
|
2014-11-11 07:07:21 +01:00
|
|
|
static void linux_test_for_exitkill (int child_pid);
|
Always run the PTRACE_O_TRACESYSGOOD tests even if PTRACE_O_TRACEFORK is not supported.
If enabling PTRACE_O_TRACEFORK fails, we never test for
PTRACE_O_TRACESYSGOOD support. Before PTRACE_O_TRACESYSGOOD is checked,
we have:
/* First, set the PTRACE_O_TRACEFORK option. If this fails, we
know for sure that it is not supported. */
ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) PTRACE_O_TRACEFORK);
if (ret != 0)
{
ret = ptrace (PTRACE_KILL, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) 0);
if (ret != 0)
{
warning (_("linux_check_ptrace_features: failed to kill child"));
return;
}
ret = my_waitpid (child_pid, &status, 0);
if (ret != child_pid)
warning (_("linux_check_ptrace_features: failed "
"to wait for killed child"));
else if (!WIFSIGNALED (status))
warning (_("linux_check_ptrace_features: unexpected "
"wait status 0x%x from killed child"), status);
return; <<<<<<<<<<<<<<<<<
}
Note that early return. If PTRACE_O_TRACEFORK isn't supported, we're
not checking PTRACE_O_TRACESYSGOOD. This didn't use to be a problem
before the unification of this whole detection business in
linux-ptrace.c. Before, the sysgood detection was completely
separate:
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);
}
So we need to get back the decoupling somehow. I think it's cleaner
to split the seperate feature detections to separate functions. This
patch does that. The new functions are named for their counterparts
that existed before this code was moved to linux-ptrace.c.
Note I've used forward declarations for the new functions to make the
patch clearer, as otherwise the patch would look like I'd be adding a
bunch of new code. A reorder can be done in a follow up patch.
Tested on x86_64 Fedora 17.
gdb/
2013-10-03 Pedro Alves <palves@redhat.com>
* common/linux-ptrace.c (linux_check_ptrace_features): Factor out
the PTRACE_O_TRACESYSGOOD and PTRACE_O_TRACEFORK to separate
functions. Always test for PTRACE_O_TRACESYSGOOD even if
PTRACE_O_TRACEFORK is not supported.
(linux_test_for_tracesysgood): New function.
(linux_test_for_tracefork): New function, factored out from
linux_check_ptrace_features, and also don't kill child_pid here.
2013-10-03 12:13:34 +02:00
|
|
|
|
2013-08-23 01:46:30 +02:00
|
|
|
/* Determine ptrace features available on this target. */
|
|
|
|
|
Identify remote fork event support
This patch implements a mechanism for GDB to determine whether fork
events are supported in gdbserver. This is a preparatory patch for
remote fork and exec event support.
Two new RSP packets are defined to represent fork and vfork event
support. These packets are used just like PACKET_multiprocess_feature
to denote whether the corresponding event is supported. GDB sends
fork-events+ and vfork-events+ to gdbserver to inquire about fork
event support. If the response enables these packets, then GDB
knows that gdbserver supports the corresponding events and will
enable them.
Target functions used to query for support are included along with
each new packet.
In order for gdbserver to know whether the events are supported at the
point where the qSupported packet arrives, the code in nat/linux-ptrace.c
had to be reorganized. Previously it would test for fork/exec event
support, then enable the events using the pid of the inferior. When the
qSupported packet arrives there may not be an inferior. So the mechanism
was split into two parts: a function that checks whether the events are
supported, called when gdbserver starts up, and another that enables the
events when the inferior stops for the first time.
Another gdbserver change was to add some global variables similar to
multi_process, one per new packet. These are used to control whether
the corresponding fork events are enabled. If GDB does not inquire
about the event support in the qSupported packet, then gdbserver will
not set these "report the event" flags. If the flags are not set, the
events are ignored like they were in the past. Thus, gdbserver will
never send fork event notification to an older GDB that doesn't
recognize fork events.
Tested on Ubuntu x64, native/remote/extended-remote, and as part of
subsequent patches in the series.
gdb/gdbserver/ChangeLog:
* linux-low.c (linux_supports_fork_events): New function.
(linux_supports_vfork_events): New function.
(linux_target_ops): Initialize new structure members.
(initialize_low): Call linux_check_ptrace_features.
* lynx-low.c (lynx_target_ops): Initialize new structure
members.
* server.c (report_fork_events, report_vfork_events):
New global flags.
(handle_query): Add new features to qSupported packet and
response.
(captured_main): Initialize new global variables.
* target.h (struct target_ops) <supports_fork_events>:
New member.
<supports_vfork_events>: New member.
(target_supports_fork_events): New macro.
(target_supports_vfork_events): New macro.
* win32-low.c (win32_target_ops): Initialize new structure
members.
gdb/ChangeLog:
* nat/linux-ptrace.c (linux_check_ptrace_features): Change
from static to extern.
* nat/linux-ptrace.h (linux_check_ptrace_features): Declare.
* remote.c (anonymous enum): <PACKET_fork_event_feature,
* PACKET_vfork_event_feature>: New enumeration constants.
(remote_protocol_features): Add table entries for new packets.
(remote_query_supported): Add new feature queries to qSupported
packet.
(_initialize_remote): Exempt new packets from the requirement
to have 'set remote' commands.
2015-05-12 18:52:41 +02:00
|
|
|
void
|
2013-08-23 01:46:30 +02:00
|
|
|
linux_check_ptrace_features (void)
|
|
|
|
{
|
|
|
|
int child_pid, ret, status;
|
|
|
|
|
|
|
|
/* Initialize the options. */
|
Extended-remote Linux follow fork
This patch implements basic support for follow-fork and detach-on-fork on
extended-remote Linux targets. Only 'fork' is supported in this patch;
'vfork' support is added n a subsequent patch. This patch depends on
the previous patches in the patch series.
Sufficient extended-remote functionality has been implemented here to pass
gdb.base/multi-forks.exp, as well as gdb.base/foll-fork.exp with the
catchpoint tests commented out. Some other fork tests fail with this
patch because it doesn't provide the architecture support needed for
watchpoint inheritance or fork catchpoints.
The implementation follows the same general structure as for the native
implementation as much as possible.
This implementation includes:
* enabling fork events in linux-low.c in initialize_low and
linux_enable_extended_features
* handling fork events in gdbserver/linux-low.c:handle_extended_wait
- when a fork event occurs in gdbserver, we must do the full creation
of the new process, thread, lwp, and breakpoint lists. This is
required whether or not the new child is destined to be
detached-on-fork, because GDB will make target calls that require all
the structures. In particular we need the breakpoint lists in order
to remove the breakpoints from a detaching child. If we are not
detaching the child we will need all these structures anyway.
- as part of this event handling we store the target_waitstatus in a new
member of the parent lwp_info structure, 'waitstatus'. This
is used to store extended event information for reporting to GDB.
- handle_extended_wait is given a return value, denoting whether the
handled event should be reported to GDB. Previously it had only
handled clone events, which were never reported.
* using a new predicate in gdbserver to control handling of the fork event
(and eventually all extended events) in linux_wait_1. The predicate,
extended_event_reported, checks a target_waitstatus.kind for an
extended ptrace event.
* implementing a new RSP 'T' Stop Reply Packet stop reason: "fork", in
gdbserver/remote-utils.c and remote.c.
* implementing new target and RSP support for target_follow_fork with
target extended-remote. (The RSP components were actually defined in
patch 1, but they see their first use here).
- remote target routine remote_follow_fork, which just sends the 'D;pid'
detach packet to detach the new fork child cleanly. We can't just
call target_detach because the data structures for the forked child
have not been allocated on the host side.
Tested on x64 Ubuntu Lucid, native, remote, extended-remote.
gdb/gdbserver/ChangeLog:
* linux-low.c (handle_extended_wait): Implement return value,
rename argument 'event_child' to 'event_lwp', handle
PTRACE_EVENT_FORK, call internal_error for unrecognized event.
(linux_low_ptrace_options): New function.
(linux_low_filter_event): Call linux_low_ptrace_options,
use different argument fo linux_enable_event_reporting,
use return value from handle_extended_wait.
(extended_event_reported): New function.
(linux_wait_1): Call extended_event_reported and set
status to report fork events.
(linux_write_memory): Add pid to debug message.
(reset_lwp_ptrace_options_callback): New function.
(linux_handle_new_gdb_connection): New function.
(linux_target_ops): Initialize new structure member.
* linux-low.h (struct lwp_info) <waitstatus>: New member.
* lynx-low.c: Initialize new structure member.
* remote-utils.c (prepare_resume_reply): Implement stop reason
"fork" for "T" stop message.
* server.c (handle_query): Call handle_new_gdb_connection.
* server.h (report_fork_events): Declare global flag.
* target.h (struct target_ops) <handle_new_gdb_connection>:
New member.
(target_handle_new_gdb_connection): New macro.
* win32-low.c: Initialize new structure member.
gdb/ChangeLog:
* linux-nat.c (linux_nat_ptrace_options): New function.
(linux_init_ptrace, wait_lwp, linux_nat_filter_event):
Call linux_nat_ptrace_options and use different argument to
linux_enable_event_reporting.
(_initialize_linux_nat): Delete call to
linux_ptrace_set_additional_flags.
* nat/linux-ptrace.c (current_ptrace_options): Rename to
supported_ptrace_options.
(additional_flags): Delete variable.
(linux_check_ptrace_features): Use supported_ptrace_options.
(linux_test_for_tracesysgood, linux_test_for_tracefork):
Likewise, and remove additional_flags check.
(linux_enable_event_reporting): Change 'attached' argument to
'options'. Use supported_ptrace_options.
(ptrace_supports_feature): Change comment. Use
supported_ptrace_options.
(linux_ptrace_set_additional_flags): Delete function.
* nat/linux-ptrace.h (linux_ptrace_set_additional_flags):
Delete function prototype.
* remote.c (remote_fork_event_p): New function.
(remote_detach_pid): New function.
(remote_detach_1): Call remote_detach_pid, don't mourn inferior
if doing detach-on-fork.
(remote_follow_fork): New function.
(remote_parse_stop_reply): Handle new "T" stop reason "fork".
(remote_pid_to_str): Print "process" strings for pid/0/0 ptids.
(init_extended_remote_ops): Initialize to_follow_fork.
2015-05-12 18:52:43 +02:00
|
|
|
supported_ptrace_options = 0;
|
2013-08-23 01:46:30 +02:00
|
|
|
|
|
|
|
/* Fork a child so we can do some testing. The child will call
|
|
|
|
linux_child_function and will get traced. The child will
|
|
|
|
eventually fork a grandchild so we can test fork event
|
|
|
|
reporting. */
|
|
|
|
child_pid = linux_fork_to_function (NULL, linux_child_function);
|
|
|
|
|
|
|
|
ret = my_waitpid (child_pid, &status, 0);
|
|
|
|
if (ret == -1)
|
|
|
|
perror_with_name (("waitpid"));
|
|
|
|
else if (ret != child_pid)
|
|
|
|
error (_("linux_check_ptrace_features: waitpid: unexpected result %d."),
|
|
|
|
ret);
|
|
|
|
if (! WIFSTOPPED (status))
|
|
|
|
error (_("linux_check_ptrace_features: waitpid: unexpected status %d."),
|
|
|
|
status);
|
|
|
|
|
Always run the PTRACE_O_TRACESYSGOOD tests even if PTRACE_O_TRACEFORK is not supported.
If enabling PTRACE_O_TRACEFORK fails, we never test for
PTRACE_O_TRACESYSGOOD support. Before PTRACE_O_TRACESYSGOOD is checked,
we have:
/* First, set the PTRACE_O_TRACEFORK option. If this fails, we
know for sure that it is not supported. */
ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) PTRACE_O_TRACEFORK);
if (ret != 0)
{
ret = ptrace (PTRACE_KILL, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) 0);
if (ret != 0)
{
warning (_("linux_check_ptrace_features: failed to kill child"));
return;
}
ret = my_waitpid (child_pid, &status, 0);
if (ret != child_pid)
warning (_("linux_check_ptrace_features: failed "
"to wait for killed child"));
else if (!WIFSIGNALED (status))
warning (_("linux_check_ptrace_features: unexpected "
"wait status 0x%x from killed child"), status);
return; <<<<<<<<<<<<<<<<<
}
Note that early return. If PTRACE_O_TRACEFORK isn't supported, we're
not checking PTRACE_O_TRACESYSGOOD. This didn't use to be a problem
before the unification of this whole detection business in
linux-ptrace.c. Before, the sysgood detection was completely
separate:
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);
}
So we need to get back the decoupling somehow. I think it's cleaner
to split the seperate feature detections to separate functions. This
patch does that. The new functions are named for their counterparts
that existed before this code was moved to linux-ptrace.c.
Note I've used forward declarations for the new functions to make the
patch clearer, as otherwise the patch would look like I'd be adding a
bunch of new code. A reorder can be done in a follow up patch.
Tested on x86_64 Fedora 17.
gdb/
2013-10-03 Pedro Alves <palves@redhat.com>
* common/linux-ptrace.c (linux_check_ptrace_features): Factor out
the PTRACE_O_TRACESYSGOOD and PTRACE_O_TRACEFORK to separate
functions. Always test for PTRACE_O_TRACESYSGOOD even if
PTRACE_O_TRACEFORK is not supported.
(linux_test_for_tracesysgood): New function.
(linux_test_for_tracefork): New function, factored out from
linux_check_ptrace_features, and also don't kill child_pid here.
2013-10-03 12:13:34 +02:00
|
|
|
linux_test_for_tracesysgood (child_pid);
|
2013-08-23 01:46:30 +02:00
|
|
|
|
Always run the PTRACE_O_TRACESYSGOOD tests even if PTRACE_O_TRACEFORK is not supported.
If enabling PTRACE_O_TRACEFORK fails, we never test for
PTRACE_O_TRACESYSGOOD support. Before PTRACE_O_TRACESYSGOOD is checked,
we have:
/* First, set the PTRACE_O_TRACEFORK option. If this fails, we
know for sure that it is not supported. */
ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) PTRACE_O_TRACEFORK);
if (ret != 0)
{
ret = ptrace (PTRACE_KILL, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) 0);
if (ret != 0)
{
warning (_("linux_check_ptrace_features: failed to kill child"));
return;
}
ret = my_waitpid (child_pid, &status, 0);
if (ret != child_pid)
warning (_("linux_check_ptrace_features: failed "
"to wait for killed child"));
else if (!WIFSIGNALED (status))
warning (_("linux_check_ptrace_features: unexpected "
"wait status 0x%x from killed child"), status);
return; <<<<<<<<<<<<<<<<<
}
Note that early return. If PTRACE_O_TRACEFORK isn't supported, we're
not checking PTRACE_O_TRACESYSGOOD. This didn't use to be a problem
before the unification of this whole detection business in
linux-ptrace.c. Before, the sysgood detection was completely
separate:
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);
}
So we need to get back the decoupling somehow. I think it's cleaner
to split the seperate feature detections to separate functions. This
patch does that. The new functions are named for their counterparts
that existed before this code was moved to linux-ptrace.c.
Note I've used forward declarations for the new functions to make the
patch clearer, as otherwise the patch would look like I'd be adding a
bunch of new code. A reorder can be done in a follow up patch.
Tested on x86_64 Fedora 17.
gdb/
2013-10-03 Pedro Alves <palves@redhat.com>
* common/linux-ptrace.c (linux_check_ptrace_features): Factor out
the PTRACE_O_TRACESYSGOOD and PTRACE_O_TRACEFORK to separate
functions. Always test for PTRACE_O_TRACESYSGOOD even if
PTRACE_O_TRACEFORK is not supported.
(linux_test_for_tracesysgood): New function.
(linux_test_for_tracefork): New function, factored out from
linux_check_ptrace_features, and also don't kill child_pid here.
2013-10-03 12:13:34 +02:00
|
|
|
linux_test_for_tracefork (child_pid);
|
|
|
|
|
2014-11-11 07:07:21 +01:00
|
|
|
linux_test_for_exitkill (child_pid);
|
|
|
|
|
Always run the PTRACE_O_TRACESYSGOOD tests even if PTRACE_O_TRACEFORK is not supported.
If enabling PTRACE_O_TRACEFORK fails, we never test for
PTRACE_O_TRACESYSGOOD support. Before PTRACE_O_TRACESYSGOOD is checked,
we have:
/* First, set the PTRACE_O_TRACEFORK option. If this fails, we
know for sure that it is not supported. */
ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) PTRACE_O_TRACEFORK);
if (ret != 0)
{
ret = ptrace (PTRACE_KILL, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) 0);
if (ret != 0)
{
warning (_("linux_check_ptrace_features: failed to kill child"));
return;
}
ret = my_waitpid (child_pid, &status, 0);
if (ret != child_pid)
warning (_("linux_check_ptrace_features: failed "
"to wait for killed child"));
else if (!WIFSIGNALED (status))
warning (_("linux_check_ptrace_features: unexpected "
"wait status 0x%x from killed child"), status);
return; <<<<<<<<<<<<<<<<<
}
Note that early return. If PTRACE_O_TRACEFORK isn't supported, we're
not checking PTRACE_O_TRACESYSGOOD. This didn't use to be a problem
before the unification of this whole detection business in
linux-ptrace.c. Before, the sysgood detection was completely
separate:
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);
}
So we need to get back the decoupling somehow. I think it's cleaner
to split the seperate feature detections to separate functions. This
patch does that. The new functions are named for their counterparts
that existed before this code was moved to linux-ptrace.c.
Note I've used forward declarations for the new functions to make the
patch clearer, as otherwise the patch would look like I'd be adding a
bunch of new code. A reorder can be done in a follow up patch.
Tested on x86_64 Fedora 17.
gdb/
2013-10-03 Pedro Alves <palves@redhat.com>
* common/linux-ptrace.c (linux_check_ptrace_features): Factor out
the PTRACE_O_TRACESYSGOOD and PTRACE_O_TRACEFORK to separate
functions. Always test for PTRACE_O_TRACESYSGOOD even if
PTRACE_O_TRACEFORK is not supported.
(linux_test_for_tracesysgood): New function.
(linux_test_for_tracefork): New function, factored out from
linux_check_ptrace_features, and also don't kill child_pid here.
2013-10-03 12:13:34 +02:00
|
|
|
/* Clean things up and kill any pending children. */
|
|
|
|
do
|
2013-08-23 01:46:30 +02:00
|
|
|
{
|
|
|
|
ret = ptrace (PTRACE_KILL, child_pid, (PTRACE_TYPE_ARG3) 0,
|
|
|
|
(PTRACE_TYPE_ARG4) 0);
|
|
|
|
if (ret != 0)
|
Always run the PTRACE_O_TRACESYSGOOD tests even if PTRACE_O_TRACEFORK is not supported.
If enabling PTRACE_O_TRACEFORK fails, we never test for
PTRACE_O_TRACESYSGOOD support. Before PTRACE_O_TRACESYSGOOD is checked,
we have:
/* First, set the PTRACE_O_TRACEFORK option. If this fails, we
know for sure that it is not supported. */
ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) PTRACE_O_TRACEFORK);
if (ret != 0)
{
ret = ptrace (PTRACE_KILL, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) 0);
if (ret != 0)
{
warning (_("linux_check_ptrace_features: failed to kill child"));
return;
}
ret = my_waitpid (child_pid, &status, 0);
if (ret != child_pid)
warning (_("linux_check_ptrace_features: failed "
"to wait for killed child"));
else if (!WIFSIGNALED (status))
warning (_("linux_check_ptrace_features: unexpected "
"wait status 0x%x from killed child"), status);
return; <<<<<<<<<<<<<<<<<
}
Note that early return. If PTRACE_O_TRACEFORK isn't supported, we're
not checking PTRACE_O_TRACESYSGOOD. This didn't use to be a problem
before the unification of this whole detection business in
linux-ptrace.c. Before, the sysgood detection was completely
separate:
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);
}
So we need to get back the decoupling somehow. I think it's cleaner
to split the seperate feature detections to separate functions. This
patch does that. The new functions are named for their counterparts
that existed before this code was moved to linux-ptrace.c.
Note I've used forward declarations for the new functions to make the
patch clearer, as otherwise the patch would look like I'd be adding a
bunch of new code. A reorder can be done in a follow up patch.
Tested on x86_64 Fedora 17.
gdb/
2013-10-03 Pedro Alves <palves@redhat.com>
* common/linux-ptrace.c (linux_check_ptrace_features): Factor out
the PTRACE_O_TRACESYSGOOD and PTRACE_O_TRACEFORK to separate
functions. Always test for PTRACE_O_TRACESYSGOOD even if
PTRACE_O_TRACEFORK is not supported.
(linux_test_for_tracesysgood): New function.
(linux_test_for_tracefork): New function, factored out from
linux_check_ptrace_features, and also don't kill child_pid here.
2013-10-03 12:13:34 +02:00
|
|
|
warning (_("linux_check_ptrace_features: failed to kill child"));
|
|
|
|
my_waitpid (child_pid, &status, 0);
|
2013-08-23 01:46:30 +02:00
|
|
|
}
|
Always run the PTRACE_O_TRACESYSGOOD tests even if PTRACE_O_TRACEFORK is not supported.
If enabling PTRACE_O_TRACEFORK fails, we never test for
PTRACE_O_TRACESYSGOOD support. Before PTRACE_O_TRACESYSGOOD is checked,
we have:
/* First, set the PTRACE_O_TRACEFORK option. If this fails, we
know for sure that it is not supported. */
ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) PTRACE_O_TRACEFORK);
if (ret != 0)
{
ret = ptrace (PTRACE_KILL, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) 0);
if (ret != 0)
{
warning (_("linux_check_ptrace_features: failed to kill child"));
return;
}
ret = my_waitpid (child_pid, &status, 0);
if (ret != child_pid)
warning (_("linux_check_ptrace_features: failed "
"to wait for killed child"));
else if (!WIFSIGNALED (status))
warning (_("linux_check_ptrace_features: unexpected "
"wait status 0x%x from killed child"), status);
return; <<<<<<<<<<<<<<<<<
}
Note that early return. If PTRACE_O_TRACEFORK isn't supported, we're
not checking PTRACE_O_TRACESYSGOOD. This didn't use to be a problem
before the unification of this whole detection business in
linux-ptrace.c. Before, the sysgood detection was completely
separate:
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);
}
So we need to get back the decoupling somehow. I think it's cleaner
to split the seperate feature detections to separate functions. This
patch does that. The new functions are named for their counterparts
that existed before this code was moved to linux-ptrace.c.
Note I've used forward declarations for the new functions to make the
patch clearer, as otherwise the patch would look like I'd be adding a
bunch of new code. A reorder can be done in a follow up patch.
Tested on x86_64 Fedora 17.
gdb/
2013-10-03 Pedro Alves <palves@redhat.com>
* common/linux-ptrace.c (linux_check_ptrace_features): Factor out
the PTRACE_O_TRACESYSGOOD and PTRACE_O_TRACEFORK to separate
functions. Always test for PTRACE_O_TRACESYSGOOD even if
PTRACE_O_TRACEFORK is not supported.
(linux_test_for_tracesysgood): New function.
(linux_test_for_tracefork): New function, factored out from
linux_check_ptrace_features, and also don't kill child_pid here.
2013-10-03 12:13:34 +02:00
|
|
|
while (WIFSTOPPED (status));
|
|
|
|
}
|
2013-08-23 01:46:30 +02:00
|
|
|
|
Always run the PTRACE_O_TRACESYSGOOD tests even if PTRACE_O_TRACEFORK is not supported.
If enabling PTRACE_O_TRACEFORK fails, we never test for
PTRACE_O_TRACESYSGOOD support. Before PTRACE_O_TRACESYSGOOD is checked,
we have:
/* First, set the PTRACE_O_TRACEFORK option. If this fails, we
know for sure that it is not supported. */
ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) PTRACE_O_TRACEFORK);
if (ret != 0)
{
ret = ptrace (PTRACE_KILL, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) 0);
if (ret != 0)
{
warning (_("linux_check_ptrace_features: failed to kill child"));
return;
}
ret = my_waitpid (child_pid, &status, 0);
if (ret != child_pid)
warning (_("linux_check_ptrace_features: failed "
"to wait for killed child"));
else if (!WIFSIGNALED (status))
warning (_("linux_check_ptrace_features: unexpected "
"wait status 0x%x from killed child"), status);
return; <<<<<<<<<<<<<<<<<
}
Note that early return. If PTRACE_O_TRACEFORK isn't supported, we're
not checking PTRACE_O_TRACESYSGOOD. This didn't use to be a problem
before the unification of this whole detection business in
linux-ptrace.c. Before, the sysgood detection was completely
separate:
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);
}
So we need to get back the decoupling somehow. I think it's cleaner
to split the seperate feature detections to separate functions. This
patch does that. The new functions are named for their counterparts
that existed before this code was moved to linux-ptrace.c.
Note I've used forward declarations for the new functions to make the
patch clearer, as otherwise the patch would look like I'd be adding a
bunch of new code. A reorder can be done in a follow up patch.
Tested on x86_64 Fedora 17.
gdb/
2013-10-03 Pedro Alves <palves@redhat.com>
* common/linux-ptrace.c (linux_check_ptrace_features): Factor out
the PTRACE_O_TRACESYSGOOD and PTRACE_O_TRACEFORK to separate
functions. Always test for PTRACE_O_TRACESYSGOOD even if
PTRACE_O_TRACEFORK is not supported.
(linux_test_for_tracesysgood): New function.
(linux_test_for_tracefork): New function, factored out from
linux_check_ptrace_features, and also don't kill child_pid here.
2013-10-03 12:13:34 +02:00
|
|
|
/* Determine if PTRACE_O_TRACESYSGOOD can be used to catch
|
|
|
|
syscalls. */
|
|
|
|
|
|
|
|
static void
|
|
|
|
linux_test_for_tracesysgood (int child_pid)
|
|
|
|
{
|
|
|
|
int ret;
|
|
|
|
|
2013-08-23 01:46:30 +02:00
|
|
|
ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0,
|
|
|
|
(PTRACE_TYPE_ARG4) PTRACE_O_TRACESYSGOOD);
|
2014-01-03 18:55:52 +01:00
|
|
|
|
2013-08-23 01:46:30 +02:00
|
|
|
if (ret == 0)
|
Extended-remote Linux follow fork
This patch implements basic support for follow-fork and detach-on-fork on
extended-remote Linux targets. Only 'fork' is supported in this patch;
'vfork' support is added n a subsequent patch. This patch depends on
the previous patches in the patch series.
Sufficient extended-remote functionality has been implemented here to pass
gdb.base/multi-forks.exp, as well as gdb.base/foll-fork.exp with the
catchpoint tests commented out. Some other fork tests fail with this
patch because it doesn't provide the architecture support needed for
watchpoint inheritance or fork catchpoints.
The implementation follows the same general structure as for the native
implementation as much as possible.
This implementation includes:
* enabling fork events in linux-low.c in initialize_low and
linux_enable_extended_features
* handling fork events in gdbserver/linux-low.c:handle_extended_wait
- when a fork event occurs in gdbserver, we must do the full creation
of the new process, thread, lwp, and breakpoint lists. This is
required whether or not the new child is destined to be
detached-on-fork, because GDB will make target calls that require all
the structures. In particular we need the breakpoint lists in order
to remove the breakpoints from a detaching child. If we are not
detaching the child we will need all these structures anyway.
- as part of this event handling we store the target_waitstatus in a new
member of the parent lwp_info structure, 'waitstatus'. This
is used to store extended event information for reporting to GDB.
- handle_extended_wait is given a return value, denoting whether the
handled event should be reported to GDB. Previously it had only
handled clone events, which were never reported.
* using a new predicate in gdbserver to control handling of the fork event
(and eventually all extended events) in linux_wait_1. The predicate,
extended_event_reported, checks a target_waitstatus.kind for an
extended ptrace event.
* implementing a new RSP 'T' Stop Reply Packet stop reason: "fork", in
gdbserver/remote-utils.c and remote.c.
* implementing new target and RSP support for target_follow_fork with
target extended-remote. (The RSP components were actually defined in
patch 1, but they see their first use here).
- remote target routine remote_follow_fork, which just sends the 'D;pid'
detach packet to detach the new fork child cleanly. We can't just
call target_detach because the data structures for the forked child
have not been allocated on the host side.
Tested on x64 Ubuntu Lucid, native, remote, extended-remote.
gdb/gdbserver/ChangeLog:
* linux-low.c (handle_extended_wait): Implement return value,
rename argument 'event_child' to 'event_lwp', handle
PTRACE_EVENT_FORK, call internal_error for unrecognized event.
(linux_low_ptrace_options): New function.
(linux_low_filter_event): Call linux_low_ptrace_options,
use different argument fo linux_enable_event_reporting,
use return value from handle_extended_wait.
(extended_event_reported): New function.
(linux_wait_1): Call extended_event_reported and set
status to report fork events.
(linux_write_memory): Add pid to debug message.
(reset_lwp_ptrace_options_callback): New function.
(linux_handle_new_gdb_connection): New function.
(linux_target_ops): Initialize new structure member.
* linux-low.h (struct lwp_info) <waitstatus>: New member.
* lynx-low.c: Initialize new structure member.
* remote-utils.c (prepare_resume_reply): Implement stop reason
"fork" for "T" stop message.
* server.c (handle_query): Call handle_new_gdb_connection.
* server.h (report_fork_events): Declare global flag.
* target.h (struct target_ops) <handle_new_gdb_connection>:
New member.
(target_handle_new_gdb_connection): New macro.
* win32-low.c: Initialize new structure member.
gdb/ChangeLog:
* linux-nat.c (linux_nat_ptrace_options): New function.
(linux_init_ptrace, wait_lwp, linux_nat_filter_event):
Call linux_nat_ptrace_options and use different argument to
linux_enable_event_reporting.
(_initialize_linux_nat): Delete call to
linux_ptrace_set_additional_flags.
* nat/linux-ptrace.c (current_ptrace_options): Rename to
supported_ptrace_options.
(additional_flags): Delete variable.
(linux_check_ptrace_features): Use supported_ptrace_options.
(linux_test_for_tracesysgood, linux_test_for_tracefork):
Likewise, and remove additional_flags check.
(linux_enable_event_reporting): Change 'attached' argument to
'options'. Use supported_ptrace_options.
(ptrace_supports_feature): Change comment. Use
supported_ptrace_options.
(linux_ptrace_set_additional_flags): Delete function.
* nat/linux-ptrace.h (linux_ptrace_set_additional_flags):
Delete function prototype.
* remote.c (remote_fork_event_p): New function.
(remote_detach_pid): New function.
(remote_detach_1): Call remote_detach_pid, don't mourn inferior
if doing detach-on-fork.
(remote_follow_fork): New function.
(remote_parse_stop_reply): Handle new "T" stop reason "fork".
(remote_pid_to_str): Print "process" strings for pid/0/0 ptids.
(init_extended_remote_ops): Initialize to_follow_fork.
2015-05-12 18:52:43 +02:00
|
|
|
supported_ptrace_options |= PTRACE_O_TRACESYSGOOD;
|
Always run the PTRACE_O_TRACESYSGOOD tests even if PTRACE_O_TRACEFORK is not supported.
If enabling PTRACE_O_TRACEFORK fails, we never test for
PTRACE_O_TRACESYSGOOD support. Before PTRACE_O_TRACESYSGOOD is checked,
we have:
/* First, set the PTRACE_O_TRACEFORK option. If this fails, we
know for sure that it is not supported. */
ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) PTRACE_O_TRACEFORK);
if (ret != 0)
{
ret = ptrace (PTRACE_KILL, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) 0);
if (ret != 0)
{
warning (_("linux_check_ptrace_features: failed to kill child"));
return;
}
ret = my_waitpid (child_pid, &status, 0);
if (ret != child_pid)
warning (_("linux_check_ptrace_features: failed "
"to wait for killed child"));
else if (!WIFSIGNALED (status))
warning (_("linux_check_ptrace_features: unexpected "
"wait status 0x%x from killed child"), status);
return; <<<<<<<<<<<<<<<<<
}
Note that early return. If PTRACE_O_TRACEFORK isn't supported, we're
not checking PTRACE_O_TRACESYSGOOD. This didn't use to be a problem
before the unification of this whole detection business in
linux-ptrace.c. Before, the sysgood detection was completely
separate:
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);
}
So we need to get back the decoupling somehow. I think it's cleaner
to split the seperate feature detections to separate functions. This
patch does that. The new functions are named for their counterparts
that existed before this code was moved to linux-ptrace.c.
Note I've used forward declarations for the new functions to make the
patch clearer, as otherwise the patch would look like I'd be adding a
bunch of new code. A reorder can be done in a follow up patch.
Tested on x86_64 Fedora 17.
gdb/
2013-10-03 Pedro Alves <palves@redhat.com>
* common/linux-ptrace.c (linux_check_ptrace_features): Factor out
the PTRACE_O_TRACESYSGOOD and PTRACE_O_TRACEFORK to separate
functions. Always test for PTRACE_O_TRACESYSGOOD even if
PTRACE_O_TRACEFORK is not supported.
(linux_test_for_tracesysgood): New function.
(linux_test_for_tracefork): New function, factored out from
linux_check_ptrace_features, and also don't kill child_pid here.
2013-10-03 12:13:34 +02:00
|
|
|
}
|
2013-08-23 01:46:30 +02:00
|
|
|
|
Always run the PTRACE_O_TRACESYSGOOD tests even if PTRACE_O_TRACEFORK is not supported.
If enabling PTRACE_O_TRACEFORK fails, we never test for
PTRACE_O_TRACESYSGOOD support. Before PTRACE_O_TRACESYSGOOD is checked,
we have:
/* First, set the PTRACE_O_TRACEFORK option. If this fails, we
know for sure that it is not supported. */
ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) PTRACE_O_TRACEFORK);
if (ret != 0)
{
ret = ptrace (PTRACE_KILL, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) 0);
if (ret != 0)
{
warning (_("linux_check_ptrace_features: failed to kill child"));
return;
}
ret = my_waitpid (child_pid, &status, 0);
if (ret != child_pid)
warning (_("linux_check_ptrace_features: failed "
"to wait for killed child"));
else if (!WIFSIGNALED (status))
warning (_("linux_check_ptrace_features: unexpected "
"wait status 0x%x from killed child"), status);
return; <<<<<<<<<<<<<<<<<
}
Note that early return. If PTRACE_O_TRACEFORK isn't supported, we're
not checking PTRACE_O_TRACESYSGOOD. This didn't use to be a problem
before the unification of this whole detection business in
linux-ptrace.c. Before, the sysgood detection was completely
separate:
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);
}
So we need to get back the decoupling somehow. I think it's cleaner
to split the seperate feature detections to separate functions. This
patch does that. The new functions are named for their counterparts
that existed before this code was moved to linux-ptrace.c.
Note I've used forward declarations for the new functions to make the
patch clearer, as otherwise the patch would look like I'd be adding a
bunch of new code. A reorder can be done in a follow up patch.
Tested on x86_64 Fedora 17.
gdb/
2013-10-03 Pedro Alves <palves@redhat.com>
* common/linux-ptrace.c (linux_check_ptrace_features): Factor out
the PTRACE_O_TRACESYSGOOD and PTRACE_O_TRACEFORK to separate
functions. Always test for PTRACE_O_TRACESYSGOOD even if
PTRACE_O_TRACEFORK is not supported.
(linux_test_for_tracesysgood): New function.
(linux_test_for_tracefork): New function, factored out from
linux_check_ptrace_features, and also don't kill child_pid here.
2013-10-03 12:13:34 +02:00
|
|
|
/* Determine if PTRACE_O_TRACEFORK can be used to follow fork
|
|
|
|
events. */
|
|
|
|
|
|
|
|
static void
|
|
|
|
linux_test_for_tracefork (int child_pid)
|
|
|
|
{
|
|
|
|
int ret, status;
|
|
|
|
long second_pid;
|
|
|
|
|
|
|
|
/* First, set the PTRACE_O_TRACEFORK option. If this fails, we
|
|
|
|
know for sure that it is not supported. */
|
|
|
|
ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0,
|
|
|
|
(PTRACE_TYPE_ARG4) PTRACE_O_TRACEFORK);
|
|
|
|
|
|
|
|
if (ret != 0)
|
|
|
|
return;
|
|
|
|
|
Extended-remote Linux follow fork
This patch implements basic support for follow-fork and detach-on-fork on
extended-remote Linux targets. Only 'fork' is supported in this patch;
'vfork' support is added n a subsequent patch. This patch depends on
the previous patches in the patch series.
Sufficient extended-remote functionality has been implemented here to pass
gdb.base/multi-forks.exp, as well as gdb.base/foll-fork.exp with the
catchpoint tests commented out. Some other fork tests fail with this
patch because it doesn't provide the architecture support needed for
watchpoint inheritance or fork catchpoints.
The implementation follows the same general structure as for the native
implementation as much as possible.
This implementation includes:
* enabling fork events in linux-low.c in initialize_low and
linux_enable_extended_features
* handling fork events in gdbserver/linux-low.c:handle_extended_wait
- when a fork event occurs in gdbserver, we must do the full creation
of the new process, thread, lwp, and breakpoint lists. This is
required whether or not the new child is destined to be
detached-on-fork, because GDB will make target calls that require all
the structures. In particular we need the breakpoint lists in order
to remove the breakpoints from a detaching child. If we are not
detaching the child we will need all these structures anyway.
- as part of this event handling we store the target_waitstatus in a new
member of the parent lwp_info structure, 'waitstatus'. This
is used to store extended event information for reporting to GDB.
- handle_extended_wait is given a return value, denoting whether the
handled event should be reported to GDB. Previously it had only
handled clone events, which were never reported.
* using a new predicate in gdbserver to control handling of the fork event
(and eventually all extended events) in linux_wait_1. The predicate,
extended_event_reported, checks a target_waitstatus.kind for an
extended ptrace event.
* implementing a new RSP 'T' Stop Reply Packet stop reason: "fork", in
gdbserver/remote-utils.c and remote.c.
* implementing new target and RSP support for target_follow_fork with
target extended-remote. (The RSP components were actually defined in
patch 1, but they see their first use here).
- remote target routine remote_follow_fork, which just sends the 'D;pid'
detach packet to detach the new fork child cleanly. We can't just
call target_detach because the data structures for the forked child
have not been allocated on the host side.
Tested on x64 Ubuntu Lucid, native, remote, extended-remote.
gdb/gdbserver/ChangeLog:
* linux-low.c (handle_extended_wait): Implement return value,
rename argument 'event_child' to 'event_lwp', handle
PTRACE_EVENT_FORK, call internal_error for unrecognized event.
(linux_low_ptrace_options): New function.
(linux_low_filter_event): Call linux_low_ptrace_options,
use different argument fo linux_enable_event_reporting,
use return value from handle_extended_wait.
(extended_event_reported): New function.
(linux_wait_1): Call extended_event_reported and set
status to report fork events.
(linux_write_memory): Add pid to debug message.
(reset_lwp_ptrace_options_callback): New function.
(linux_handle_new_gdb_connection): New function.
(linux_target_ops): Initialize new structure member.
* linux-low.h (struct lwp_info) <waitstatus>: New member.
* lynx-low.c: Initialize new structure member.
* remote-utils.c (prepare_resume_reply): Implement stop reason
"fork" for "T" stop message.
* server.c (handle_query): Call handle_new_gdb_connection.
* server.h (report_fork_events): Declare global flag.
* target.h (struct target_ops) <handle_new_gdb_connection>:
New member.
(target_handle_new_gdb_connection): New macro.
* win32-low.c: Initialize new structure member.
gdb/ChangeLog:
* linux-nat.c (linux_nat_ptrace_options): New function.
(linux_init_ptrace, wait_lwp, linux_nat_filter_event):
Call linux_nat_ptrace_options and use different argument to
linux_enable_event_reporting.
(_initialize_linux_nat): Delete call to
linux_ptrace_set_additional_flags.
* nat/linux-ptrace.c (current_ptrace_options): Rename to
supported_ptrace_options.
(additional_flags): Delete variable.
(linux_check_ptrace_features): Use supported_ptrace_options.
(linux_test_for_tracesysgood, linux_test_for_tracefork):
Likewise, and remove additional_flags check.
(linux_enable_event_reporting): Change 'attached' argument to
'options'. Use supported_ptrace_options.
(ptrace_supports_feature): Change comment. Use
supported_ptrace_options.
(linux_ptrace_set_additional_flags): Delete function.
* nat/linux-ptrace.h (linux_ptrace_set_additional_flags):
Delete function prototype.
* remote.c (remote_fork_event_p): New function.
(remote_detach_pid): New function.
(remote_detach_1): Call remote_detach_pid, don't mourn inferior
if doing detach-on-fork.
(remote_follow_fork): New function.
(remote_parse_stop_reply): Handle new "T" stop reason "fork".
(remote_pid_to_str): Print "process" strings for pid/0/0 ptids.
(init_extended_remote_ops): Initialize to_follow_fork.
2015-05-12 18:52:43 +02:00
|
|
|
/* Check if the target supports PTRACE_O_TRACEVFORKDONE. */
|
|
|
|
ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0,
|
|
|
|
(PTRACE_TYPE_ARG4) (PTRACE_O_TRACEFORK
|
|
|
|
| PTRACE_O_TRACEVFORKDONE));
|
|
|
|
if (ret == 0)
|
|
|
|
supported_ptrace_options |= PTRACE_O_TRACEVFORKDONE;
|
2013-08-23 01:46:30 +02:00
|
|
|
|
|
|
|
/* Setting PTRACE_O_TRACEFORK did not cause an error, however we
|
|
|
|
don't know for sure that the feature is available; old
|
|
|
|
versions of PTRACE_SETOPTIONS ignored unknown options.
|
|
|
|
Therefore, we attach to the child process, use PTRACE_SETOPTIONS
|
|
|
|
to enable fork tracing, and let it fork. If the process exits,
|
|
|
|
we assume that we can't use PTRACE_O_TRACEFORK; if we get the
|
|
|
|
fork notification, and we can extract the new child's PID, then
|
|
|
|
we assume that we can.
|
|
|
|
|
|
|
|
We do not explicitly check for vfork tracing here. It is
|
|
|
|
assumed that vfork tracing is available whenever fork tracing
|
|
|
|
is available. */
|
|
|
|
ret = ptrace (PTRACE_CONT, child_pid, (PTRACE_TYPE_ARG3) 0,
|
|
|
|
(PTRACE_TYPE_ARG4) 0);
|
|
|
|
if (ret != 0)
|
Always run the PTRACE_O_TRACESYSGOOD tests even if PTRACE_O_TRACEFORK is not supported.
If enabling PTRACE_O_TRACEFORK fails, we never test for
PTRACE_O_TRACESYSGOOD support. Before PTRACE_O_TRACESYSGOOD is checked,
we have:
/* First, set the PTRACE_O_TRACEFORK option. If this fails, we
know for sure that it is not supported. */
ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) PTRACE_O_TRACEFORK);
if (ret != 0)
{
ret = ptrace (PTRACE_KILL, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) 0);
if (ret != 0)
{
warning (_("linux_check_ptrace_features: failed to kill child"));
return;
}
ret = my_waitpid (child_pid, &status, 0);
if (ret != child_pid)
warning (_("linux_check_ptrace_features: failed "
"to wait for killed child"));
else if (!WIFSIGNALED (status))
warning (_("linux_check_ptrace_features: unexpected "
"wait status 0x%x from killed child"), status);
return; <<<<<<<<<<<<<<<<<
}
Note that early return. If PTRACE_O_TRACEFORK isn't supported, we're
not checking PTRACE_O_TRACESYSGOOD. This didn't use to be a problem
before the unification of this whole detection business in
linux-ptrace.c. Before, the sysgood detection was completely
separate:
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);
}
So we need to get back the decoupling somehow. I think it's cleaner
to split the seperate feature detections to separate functions. This
patch does that. The new functions are named for their counterparts
that existed before this code was moved to linux-ptrace.c.
Note I've used forward declarations for the new functions to make the
patch clearer, as otherwise the patch would look like I'd be adding a
bunch of new code. A reorder can be done in a follow up patch.
Tested on x86_64 Fedora 17.
gdb/
2013-10-03 Pedro Alves <palves@redhat.com>
* common/linux-ptrace.c (linux_check_ptrace_features): Factor out
the PTRACE_O_TRACESYSGOOD and PTRACE_O_TRACEFORK to separate
functions. Always test for PTRACE_O_TRACESYSGOOD even if
PTRACE_O_TRACEFORK is not supported.
(linux_test_for_tracesysgood): New function.
(linux_test_for_tracefork): New function, factored out from
linux_check_ptrace_features, and also don't kill child_pid here.
2013-10-03 12:13:34 +02:00
|
|
|
warning (_("linux_test_for_tracefork: failed to resume child"));
|
2013-08-23 01:46:30 +02:00
|
|
|
|
|
|
|
ret = my_waitpid (child_pid, &status, 0);
|
|
|
|
|
|
|
|
/* Check if we received a fork event notification. */
|
|
|
|
if (ret == child_pid && WIFSTOPPED (status)
|
2014-09-19 19:54:34 +02:00
|
|
|
&& linux_ptrace_get_extended_event (status) == PTRACE_EVENT_FORK)
|
2013-08-23 01:46:30 +02:00
|
|
|
{
|
|
|
|
/* We did receive a fork event notification. Make sure its PID
|
|
|
|
is reported. */
|
|
|
|
second_pid = 0;
|
|
|
|
ret = ptrace (PTRACE_GETEVENTMSG, child_pid, (PTRACE_TYPE_ARG3) 0,
|
|
|
|
(PTRACE_TYPE_ARG4) &second_pid);
|
|
|
|
if (ret == 0 && second_pid != 0)
|
|
|
|
{
|
|
|
|
int second_status;
|
|
|
|
|
|
|
|
/* We got the PID from the grandchild, which means fork
|
|
|
|
tracing is supported. */
|
Extended-remote Linux follow fork
This patch implements basic support for follow-fork and detach-on-fork on
extended-remote Linux targets. Only 'fork' is supported in this patch;
'vfork' support is added n a subsequent patch. This patch depends on
the previous patches in the patch series.
Sufficient extended-remote functionality has been implemented here to pass
gdb.base/multi-forks.exp, as well as gdb.base/foll-fork.exp with the
catchpoint tests commented out. Some other fork tests fail with this
patch because it doesn't provide the architecture support needed for
watchpoint inheritance or fork catchpoints.
The implementation follows the same general structure as for the native
implementation as much as possible.
This implementation includes:
* enabling fork events in linux-low.c in initialize_low and
linux_enable_extended_features
* handling fork events in gdbserver/linux-low.c:handle_extended_wait
- when a fork event occurs in gdbserver, we must do the full creation
of the new process, thread, lwp, and breakpoint lists. This is
required whether or not the new child is destined to be
detached-on-fork, because GDB will make target calls that require all
the structures. In particular we need the breakpoint lists in order
to remove the breakpoints from a detaching child. If we are not
detaching the child we will need all these structures anyway.
- as part of this event handling we store the target_waitstatus in a new
member of the parent lwp_info structure, 'waitstatus'. This
is used to store extended event information for reporting to GDB.
- handle_extended_wait is given a return value, denoting whether the
handled event should be reported to GDB. Previously it had only
handled clone events, which were never reported.
* using a new predicate in gdbserver to control handling of the fork event
(and eventually all extended events) in linux_wait_1. The predicate,
extended_event_reported, checks a target_waitstatus.kind for an
extended ptrace event.
* implementing a new RSP 'T' Stop Reply Packet stop reason: "fork", in
gdbserver/remote-utils.c and remote.c.
* implementing new target and RSP support for target_follow_fork with
target extended-remote. (The RSP components were actually defined in
patch 1, but they see their first use here).
- remote target routine remote_follow_fork, which just sends the 'D;pid'
detach packet to detach the new fork child cleanly. We can't just
call target_detach because the data structures for the forked child
have not been allocated on the host side.
Tested on x64 Ubuntu Lucid, native, remote, extended-remote.
gdb/gdbserver/ChangeLog:
* linux-low.c (handle_extended_wait): Implement return value,
rename argument 'event_child' to 'event_lwp', handle
PTRACE_EVENT_FORK, call internal_error for unrecognized event.
(linux_low_ptrace_options): New function.
(linux_low_filter_event): Call linux_low_ptrace_options,
use different argument fo linux_enable_event_reporting,
use return value from handle_extended_wait.
(extended_event_reported): New function.
(linux_wait_1): Call extended_event_reported and set
status to report fork events.
(linux_write_memory): Add pid to debug message.
(reset_lwp_ptrace_options_callback): New function.
(linux_handle_new_gdb_connection): New function.
(linux_target_ops): Initialize new structure member.
* linux-low.h (struct lwp_info) <waitstatus>: New member.
* lynx-low.c: Initialize new structure member.
* remote-utils.c (prepare_resume_reply): Implement stop reason
"fork" for "T" stop message.
* server.c (handle_query): Call handle_new_gdb_connection.
* server.h (report_fork_events): Declare global flag.
* target.h (struct target_ops) <handle_new_gdb_connection>:
New member.
(target_handle_new_gdb_connection): New macro.
* win32-low.c: Initialize new structure member.
gdb/ChangeLog:
* linux-nat.c (linux_nat_ptrace_options): New function.
(linux_init_ptrace, wait_lwp, linux_nat_filter_event):
Call linux_nat_ptrace_options and use different argument to
linux_enable_event_reporting.
(_initialize_linux_nat): Delete call to
linux_ptrace_set_additional_flags.
* nat/linux-ptrace.c (current_ptrace_options): Rename to
supported_ptrace_options.
(additional_flags): Delete variable.
(linux_check_ptrace_features): Use supported_ptrace_options.
(linux_test_for_tracesysgood, linux_test_for_tracefork):
Likewise, and remove additional_flags check.
(linux_enable_event_reporting): Change 'attached' argument to
'options'. Use supported_ptrace_options.
(ptrace_supports_feature): Change comment. Use
supported_ptrace_options.
(linux_ptrace_set_additional_flags): Delete function.
* nat/linux-ptrace.h (linux_ptrace_set_additional_flags):
Delete function prototype.
* remote.c (remote_fork_event_p): New function.
(remote_detach_pid): New function.
(remote_detach_1): Call remote_detach_pid, don't mourn inferior
if doing detach-on-fork.
(remote_follow_fork): New function.
(remote_parse_stop_reply): Handle new "T" stop reason "fork".
(remote_pid_to_str): Print "process" strings for pid/0/0 ptids.
(init_extended_remote_ops): Initialize to_follow_fork.
2015-05-12 18:52:43 +02:00
|
|
|
supported_ptrace_options |= PTRACE_O_TRACECLONE;
|
|
|
|
supported_ptrace_options |= (PTRACE_O_TRACEFORK
|
|
|
|
| PTRACE_O_TRACEVFORK
|
|
|
|
| PTRACE_O_TRACEEXEC);
|
2013-08-23 01:46:30 +02:00
|
|
|
|
|
|
|
/* Do some cleanup and kill the grandchild. */
|
|
|
|
my_waitpid (second_pid, &second_status, 0);
|
|
|
|
ret = ptrace (PTRACE_KILL, second_pid, (PTRACE_TYPE_ARG3) 0,
|
|
|
|
(PTRACE_TYPE_ARG4) 0);
|
|
|
|
if (ret != 0)
|
Always run the PTRACE_O_TRACESYSGOOD tests even if PTRACE_O_TRACEFORK is not supported.
If enabling PTRACE_O_TRACEFORK fails, we never test for
PTRACE_O_TRACESYSGOOD support. Before PTRACE_O_TRACESYSGOOD is checked,
we have:
/* First, set the PTRACE_O_TRACEFORK option. If this fails, we
know for sure that it is not supported. */
ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) PTRACE_O_TRACEFORK);
if (ret != 0)
{
ret = ptrace (PTRACE_KILL, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) 0);
if (ret != 0)
{
warning (_("linux_check_ptrace_features: failed to kill child"));
return;
}
ret = my_waitpid (child_pid, &status, 0);
if (ret != child_pid)
warning (_("linux_check_ptrace_features: failed "
"to wait for killed child"));
else if (!WIFSIGNALED (status))
warning (_("linux_check_ptrace_features: unexpected "
"wait status 0x%x from killed child"), status);
return; <<<<<<<<<<<<<<<<<
}
Note that early return. If PTRACE_O_TRACEFORK isn't supported, we're
not checking PTRACE_O_TRACESYSGOOD. This didn't use to be a problem
before the unification of this whole detection business in
linux-ptrace.c. Before, the sysgood detection was completely
separate:
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);
}
So we need to get back the decoupling somehow. I think it's cleaner
to split the seperate feature detections to separate functions. This
patch does that. The new functions are named for their counterparts
that existed before this code was moved to linux-ptrace.c.
Note I've used forward declarations for the new functions to make the
patch clearer, as otherwise the patch would look like I'd be adding a
bunch of new code. A reorder can be done in a follow up patch.
Tested on x86_64 Fedora 17.
gdb/
2013-10-03 Pedro Alves <palves@redhat.com>
* common/linux-ptrace.c (linux_check_ptrace_features): Factor out
the PTRACE_O_TRACESYSGOOD and PTRACE_O_TRACEFORK to separate
functions. Always test for PTRACE_O_TRACESYSGOOD even if
PTRACE_O_TRACEFORK is not supported.
(linux_test_for_tracesysgood): New function.
(linux_test_for_tracefork): New function, factored out from
linux_check_ptrace_features, and also don't kill child_pid here.
2013-10-03 12:13:34 +02:00
|
|
|
warning (_("linux_test_for_tracefork: "
|
2013-08-23 01:46:30 +02:00
|
|
|
"failed to kill second child"));
|
|
|
|
my_waitpid (second_pid, &status, 0);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
else
|
Always run the PTRACE_O_TRACESYSGOOD tests even if PTRACE_O_TRACEFORK is not supported.
If enabling PTRACE_O_TRACEFORK fails, we never test for
PTRACE_O_TRACESYSGOOD support. Before PTRACE_O_TRACESYSGOOD is checked,
we have:
/* First, set the PTRACE_O_TRACEFORK option. If this fails, we
know for sure that it is not supported. */
ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) PTRACE_O_TRACEFORK);
if (ret != 0)
{
ret = ptrace (PTRACE_KILL, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) 0);
if (ret != 0)
{
warning (_("linux_check_ptrace_features: failed to kill child"));
return;
}
ret = my_waitpid (child_pid, &status, 0);
if (ret != child_pid)
warning (_("linux_check_ptrace_features: failed "
"to wait for killed child"));
else if (!WIFSIGNALED (status))
warning (_("linux_check_ptrace_features: unexpected "
"wait status 0x%x from killed child"), status);
return; <<<<<<<<<<<<<<<<<
}
Note that early return. If PTRACE_O_TRACEFORK isn't supported, we're
not checking PTRACE_O_TRACESYSGOOD. This didn't use to be a problem
before the unification of this whole detection business in
linux-ptrace.c. Before, the sysgood detection was completely
separate:
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);
}
So we need to get back the decoupling somehow. I think it's cleaner
to split the seperate feature detections to separate functions. This
patch does that. The new functions are named for their counterparts
that existed before this code was moved to linux-ptrace.c.
Note I've used forward declarations for the new functions to make the
patch clearer, as otherwise the patch would look like I'd be adding a
bunch of new code. A reorder can be done in a follow up patch.
Tested on x86_64 Fedora 17.
gdb/
2013-10-03 Pedro Alves <palves@redhat.com>
* common/linux-ptrace.c (linux_check_ptrace_features): Factor out
the PTRACE_O_TRACESYSGOOD and PTRACE_O_TRACEFORK to separate
functions. Always test for PTRACE_O_TRACESYSGOOD even if
PTRACE_O_TRACEFORK is not supported.
(linux_test_for_tracesysgood): New function.
(linux_test_for_tracefork): New function, factored out from
linux_check_ptrace_features, and also don't kill child_pid here.
2013-10-03 12:13:34 +02:00
|
|
|
warning (_("linux_test_for_tracefork: unexpected result from waitpid "
|
2013-08-23 01:46:30 +02:00
|
|
|
"(%d, status 0x%x)"), ret, status);
|
|
|
|
}
|
|
|
|
|
2014-11-11 07:07:21 +01:00
|
|
|
/* Determine if PTRACE_O_EXITKILL can be used. */
|
|
|
|
|
|
|
|
static void
|
|
|
|
linux_test_for_exitkill (int child_pid)
|
|
|
|
{
|
|
|
|
int ret;
|
|
|
|
|
|
|
|
ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0,
|
|
|
|
(PTRACE_TYPE_ARG4) PTRACE_O_EXITKILL);
|
|
|
|
|
|
|
|
if (ret == 0)
|
Extended-remote Linux follow fork
This patch implements basic support for follow-fork and detach-on-fork on
extended-remote Linux targets. Only 'fork' is supported in this patch;
'vfork' support is added n a subsequent patch. This patch depends on
the previous patches in the patch series.
Sufficient extended-remote functionality has been implemented here to pass
gdb.base/multi-forks.exp, as well as gdb.base/foll-fork.exp with the
catchpoint tests commented out. Some other fork tests fail with this
patch because it doesn't provide the architecture support needed for
watchpoint inheritance or fork catchpoints.
The implementation follows the same general structure as for the native
implementation as much as possible.
This implementation includes:
* enabling fork events in linux-low.c in initialize_low and
linux_enable_extended_features
* handling fork events in gdbserver/linux-low.c:handle_extended_wait
- when a fork event occurs in gdbserver, we must do the full creation
of the new process, thread, lwp, and breakpoint lists. This is
required whether or not the new child is destined to be
detached-on-fork, because GDB will make target calls that require all
the structures. In particular we need the breakpoint lists in order
to remove the breakpoints from a detaching child. If we are not
detaching the child we will need all these structures anyway.
- as part of this event handling we store the target_waitstatus in a new
member of the parent lwp_info structure, 'waitstatus'. This
is used to store extended event information for reporting to GDB.
- handle_extended_wait is given a return value, denoting whether the
handled event should be reported to GDB. Previously it had only
handled clone events, which were never reported.
* using a new predicate in gdbserver to control handling of the fork event
(and eventually all extended events) in linux_wait_1. The predicate,
extended_event_reported, checks a target_waitstatus.kind for an
extended ptrace event.
* implementing a new RSP 'T' Stop Reply Packet stop reason: "fork", in
gdbserver/remote-utils.c and remote.c.
* implementing new target and RSP support for target_follow_fork with
target extended-remote. (The RSP components were actually defined in
patch 1, but they see their first use here).
- remote target routine remote_follow_fork, which just sends the 'D;pid'
detach packet to detach the new fork child cleanly. We can't just
call target_detach because the data structures for the forked child
have not been allocated on the host side.
Tested on x64 Ubuntu Lucid, native, remote, extended-remote.
gdb/gdbserver/ChangeLog:
* linux-low.c (handle_extended_wait): Implement return value,
rename argument 'event_child' to 'event_lwp', handle
PTRACE_EVENT_FORK, call internal_error for unrecognized event.
(linux_low_ptrace_options): New function.
(linux_low_filter_event): Call linux_low_ptrace_options,
use different argument fo linux_enable_event_reporting,
use return value from handle_extended_wait.
(extended_event_reported): New function.
(linux_wait_1): Call extended_event_reported and set
status to report fork events.
(linux_write_memory): Add pid to debug message.
(reset_lwp_ptrace_options_callback): New function.
(linux_handle_new_gdb_connection): New function.
(linux_target_ops): Initialize new structure member.
* linux-low.h (struct lwp_info) <waitstatus>: New member.
* lynx-low.c: Initialize new structure member.
* remote-utils.c (prepare_resume_reply): Implement stop reason
"fork" for "T" stop message.
* server.c (handle_query): Call handle_new_gdb_connection.
* server.h (report_fork_events): Declare global flag.
* target.h (struct target_ops) <handle_new_gdb_connection>:
New member.
(target_handle_new_gdb_connection): New macro.
* win32-low.c: Initialize new structure member.
gdb/ChangeLog:
* linux-nat.c (linux_nat_ptrace_options): New function.
(linux_init_ptrace, wait_lwp, linux_nat_filter_event):
Call linux_nat_ptrace_options and use different argument to
linux_enable_event_reporting.
(_initialize_linux_nat): Delete call to
linux_ptrace_set_additional_flags.
* nat/linux-ptrace.c (current_ptrace_options): Rename to
supported_ptrace_options.
(additional_flags): Delete variable.
(linux_check_ptrace_features): Use supported_ptrace_options.
(linux_test_for_tracesysgood, linux_test_for_tracefork):
Likewise, and remove additional_flags check.
(linux_enable_event_reporting): Change 'attached' argument to
'options'. Use supported_ptrace_options.
(ptrace_supports_feature): Change comment. Use
supported_ptrace_options.
(linux_ptrace_set_additional_flags): Delete function.
* nat/linux-ptrace.h (linux_ptrace_set_additional_flags):
Delete function prototype.
* remote.c (remote_fork_event_p): New function.
(remote_detach_pid): New function.
(remote_detach_1): Call remote_detach_pid, don't mourn inferior
if doing detach-on-fork.
(remote_follow_fork): New function.
(remote_parse_stop_reply): Handle new "T" stop reason "fork".
(remote_pid_to_str): Print "process" strings for pid/0/0 ptids.
(init_extended_remote_ops): Initialize to_follow_fork.
2015-05-12 18:52:43 +02:00
|
|
|
supported_ptrace_options |= PTRACE_O_EXITKILL;
|
2014-11-11 07:07:21 +01:00
|
|
|
}
|
|
|
|
|
|
|
|
/* Enable reporting of all currently supported ptrace events.
|
Extended-remote Linux follow fork
This patch implements basic support for follow-fork and detach-on-fork on
extended-remote Linux targets. Only 'fork' is supported in this patch;
'vfork' support is added n a subsequent patch. This patch depends on
the previous patches in the patch series.
Sufficient extended-remote functionality has been implemented here to pass
gdb.base/multi-forks.exp, as well as gdb.base/foll-fork.exp with the
catchpoint tests commented out. Some other fork tests fail with this
patch because it doesn't provide the architecture support needed for
watchpoint inheritance or fork catchpoints.
The implementation follows the same general structure as for the native
implementation as much as possible.
This implementation includes:
* enabling fork events in linux-low.c in initialize_low and
linux_enable_extended_features
* handling fork events in gdbserver/linux-low.c:handle_extended_wait
- when a fork event occurs in gdbserver, we must do the full creation
of the new process, thread, lwp, and breakpoint lists. This is
required whether or not the new child is destined to be
detached-on-fork, because GDB will make target calls that require all
the structures. In particular we need the breakpoint lists in order
to remove the breakpoints from a detaching child. If we are not
detaching the child we will need all these structures anyway.
- as part of this event handling we store the target_waitstatus in a new
member of the parent lwp_info structure, 'waitstatus'. This
is used to store extended event information for reporting to GDB.
- handle_extended_wait is given a return value, denoting whether the
handled event should be reported to GDB. Previously it had only
handled clone events, which were never reported.
* using a new predicate in gdbserver to control handling of the fork event
(and eventually all extended events) in linux_wait_1. The predicate,
extended_event_reported, checks a target_waitstatus.kind for an
extended ptrace event.
* implementing a new RSP 'T' Stop Reply Packet stop reason: "fork", in
gdbserver/remote-utils.c and remote.c.
* implementing new target and RSP support for target_follow_fork with
target extended-remote. (The RSP components were actually defined in
patch 1, but they see their first use here).
- remote target routine remote_follow_fork, which just sends the 'D;pid'
detach packet to detach the new fork child cleanly. We can't just
call target_detach because the data structures for the forked child
have not been allocated on the host side.
Tested on x64 Ubuntu Lucid, native, remote, extended-remote.
gdb/gdbserver/ChangeLog:
* linux-low.c (handle_extended_wait): Implement return value,
rename argument 'event_child' to 'event_lwp', handle
PTRACE_EVENT_FORK, call internal_error for unrecognized event.
(linux_low_ptrace_options): New function.
(linux_low_filter_event): Call linux_low_ptrace_options,
use different argument fo linux_enable_event_reporting,
use return value from handle_extended_wait.
(extended_event_reported): New function.
(linux_wait_1): Call extended_event_reported and set
status to report fork events.
(linux_write_memory): Add pid to debug message.
(reset_lwp_ptrace_options_callback): New function.
(linux_handle_new_gdb_connection): New function.
(linux_target_ops): Initialize new structure member.
* linux-low.h (struct lwp_info) <waitstatus>: New member.
* lynx-low.c: Initialize new structure member.
* remote-utils.c (prepare_resume_reply): Implement stop reason
"fork" for "T" stop message.
* server.c (handle_query): Call handle_new_gdb_connection.
* server.h (report_fork_events): Declare global flag.
* target.h (struct target_ops) <handle_new_gdb_connection>:
New member.
(target_handle_new_gdb_connection): New macro.
* win32-low.c: Initialize new structure member.
gdb/ChangeLog:
* linux-nat.c (linux_nat_ptrace_options): New function.
(linux_init_ptrace, wait_lwp, linux_nat_filter_event):
Call linux_nat_ptrace_options and use different argument to
linux_enable_event_reporting.
(_initialize_linux_nat): Delete call to
linux_ptrace_set_additional_flags.
* nat/linux-ptrace.c (current_ptrace_options): Rename to
supported_ptrace_options.
(additional_flags): Delete variable.
(linux_check_ptrace_features): Use supported_ptrace_options.
(linux_test_for_tracesysgood, linux_test_for_tracefork):
Likewise, and remove additional_flags check.
(linux_enable_event_reporting): Change 'attached' argument to
'options'. Use supported_ptrace_options.
(ptrace_supports_feature): Change comment. Use
supported_ptrace_options.
(linux_ptrace_set_additional_flags): Delete function.
* nat/linux-ptrace.h (linux_ptrace_set_additional_flags):
Delete function prototype.
* remote.c (remote_fork_event_p): New function.
(remote_detach_pid): New function.
(remote_detach_1): Call remote_detach_pid, don't mourn inferior
if doing detach-on-fork.
(remote_follow_fork): New function.
(remote_parse_stop_reply): Handle new "T" stop reason "fork".
(remote_pid_to_str): Print "process" strings for pid/0/0 ptids.
(init_extended_remote_ops): Initialize to_follow_fork.
2015-05-12 18:52:43 +02:00
|
|
|
OPTIONS is a bit mask of extended features we want enabled,
|
|
|
|
if supported by the kernel. PTRACE_O_TRACECLONE is always
|
|
|
|
enabled, if supported. */
|
2013-08-23 01:46:30 +02:00
|
|
|
|
|
|
|
void
|
Extended-remote Linux follow fork
This patch implements basic support for follow-fork and detach-on-fork on
extended-remote Linux targets. Only 'fork' is supported in this patch;
'vfork' support is added n a subsequent patch. This patch depends on
the previous patches in the patch series.
Sufficient extended-remote functionality has been implemented here to pass
gdb.base/multi-forks.exp, as well as gdb.base/foll-fork.exp with the
catchpoint tests commented out. Some other fork tests fail with this
patch because it doesn't provide the architecture support needed for
watchpoint inheritance or fork catchpoints.
The implementation follows the same general structure as for the native
implementation as much as possible.
This implementation includes:
* enabling fork events in linux-low.c in initialize_low and
linux_enable_extended_features
* handling fork events in gdbserver/linux-low.c:handle_extended_wait
- when a fork event occurs in gdbserver, we must do the full creation
of the new process, thread, lwp, and breakpoint lists. This is
required whether or not the new child is destined to be
detached-on-fork, because GDB will make target calls that require all
the structures. In particular we need the breakpoint lists in order
to remove the breakpoints from a detaching child. If we are not
detaching the child we will need all these structures anyway.
- as part of this event handling we store the target_waitstatus in a new
member of the parent lwp_info structure, 'waitstatus'. This
is used to store extended event information for reporting to GDB.
- handle_extended_wait is given a return value, denoting whether the
handled event should be reported to GDB. Previously it had only
handled clone events, which were never reported.
* using a new predicate in gdbserver to control handling of the fork event
(and eventually all extended events) in linux_wait_1. The predicate,
extended_event_reported, checks a target_waitstatus.kind for an
extended ptrace event.
* implementing a new RSP 'T' Stop Reply Packet stop reason: "fork", in
gdbserver/remote-utils.c and remote.c.
* implementing new target and RSP support for target_follow_fork with
target extended-remote. (The RSP components were actually defined in
patch 1, but they see their first use here).
- remote target routine remote_follow_fork, which just sends the 'D;pid'
detach packet to detach the new fork child cleanly. We can't just
call target_detach because the data structures for the forked child
have not been allocated on the host side.
Tested on x64 Ubuntu Lucid, native, remote, extended-remote.
gdb/gdbserver/ChangeLog:
* linux-low.c (handle_extended_wait): Implement return value,
rename argument 'event_child' to 'event_lwp', handle
PTRACE_EVENT_FORK, call internal_error for unrecognized event.
(linux_low_ptrace_options): New function.
(linux_low_filter_event): Call linux_low_ptrace_options,
use different argument fo linux_enable_event_reporting,
use return value from handle_extended_wait.
(extended_event_reported): New function.
(linux_wait_1): Call extended_event_reported and set
status to report fork events.
(linux_write_memory): Add pid to debug message.
(reset_lwp_ptrace_options_callback): New function.
(linux_handle_new_gdb_connection): New function.
(linux_target_ops): Initialize new structure member.
* linux-low.h (struct lwp_info) <waitstatus>: New member.
* lynx-low.c: Initialize new structure member.
* remote-utils.c (prepare_resume_reply): Implement stop reason
"fork" for "T" stop message.
* server.c (handle_query): Call handle_new_gdb_connection.
* server.h (report_fork_events): Declare global flag.
* target.h (struct target_ops) <handle_new_gdb_connection>:
New member.
(target_handle_new_gdb_connection): New macro.
* win32-low.c: Initialize new structure member.
gdb/ChangeLog:
* linux-nat.c (linux_nat_ptrace_options): New function.
(linux_init_ptrace, wait_lwp, linux_nat_filter_event):
Call linux_nat_ptrace_options and use different argument to
linux_enable_event_reporting.
(_initialize_linux_nat): Delete call to
linux_ptrace_set_additional_flags.
* nat/linux-ptrace.c (current_ptrace_options): Rename to
supported_ptrace_options.
(additional_flags): Delete variable.
(linux_check_ptrace_features): Use supported_ptrace_options.
(linux_test_for_tracesysgood, linux_test_for_tracefork):
Likewise, and remove additional_flags check.
(linux_enable_event_reporting): Change 'attached' argument to
'options'. Use supported_ptrace_options.
(ptrace_supports_feature): Change comment. Use
supported_ptrace_options.
(linux_ptrace_set_additional_flags): Delete function.
* nat/linux-ptrace.h (linux_ptrace_set_additional_flags):
Delete function prototype.
* remote.c (remote_fork_event_p): New function.
(remote_detach_pid): New function.
(remote_detach_1): Call remote_detach_pid, don't mourn inferior
if doing detach-on-fork.
(remote_follow_fork): New function.
(remote_parse_stop_reply): Handle new "T" stop reason "fork".
(remote_pid_to_str): Print "process" strings for pid/0/0 ptids.
(init_extended_remote_ops): Initialize to_follow_fork.
2015-05-12 18:52:43 +02:00
|
|
|
linux_enable_event_reporting (pid_t pid, int options)
|
2013-08-23 01:46:30 +02:00
|
|
|
{
|
|
|
|
/* Check if we have initialized the ptrace features for this
|
|
|
|
target. If not, do it now. */
|
Extended-remote Linux follow fork
This patch implements basic support for follow-fork and detach-on-fork on
extended-remote Linux targets. Only 'fork' is supported in this patch;
'vfork' support is added n a subsequent patch. This patch depends on
the previous patches in the patch series.
Sufficient extended-remote functionality has been implemented here to pass
gdb.base/multi-forks.exp, as well as gdb.base/foll-fork.exp with the
catchpoint tests commented out. Some other fork tests fail with this
patch because it doesn't provide the architecture support needed for
watchpoint inheritance or fork catchpoints.
The implementation follows the same general structure as for the native
implementation as much as possible.
This implementation includes:
* enabling fork events in linux-low.c in initialize_low and
linux_enable_extended_features
* handling fork events in gdbserver/linux-low.c:handle_extended_wait
- when a fork event occurs in gdbserver, we must do the full creation
of the new process, thread, lwp, and breakpoint lists. This is
required whether or not the new child is destined to be
detached-on-fork, because GDB will make target calls that require all
the structures. In particular we need the breakpoint lists in order
to remove the breakpoints from a detaching child. If we are not
detaching the child we will need all these structures anyway.
- as part of this event handling we store the target_waitstatus in a new
member of the parent lwp_info structure, 'waitstatus'. This
is used to store extended event information for reporting to GDB.
- handle_extended_wait is given a return value, denoting whether the
handled event should be reported to GDB. Previously it had only
handled clone events, which were never reported.
* using a new predicate in gdbserver to control handling of the fork event
(and eventually all extended events) in linux_wait_1. The predicate,
extended_event_reported, checks a target_waitstatus.kind for an
extended ptrace event.
* implementing a new RSP 'T' Stop Reply Packet stop reason: "fork", in
gdbserver/remote-utils.c and remote.c.
* implementing new target and RSP support for target_follow_fork with
target extended-remote. (The RSP components were actually defined in
patch 1, but they see their first use here).
- remote target routine remote_follow_fork, which just sends the 'D;pid'
detach packet to detach the new fork child cleanly. We can't just
call target_detach because the data structures for the forked child
have not been allocated on the host side.
Tested on x64 Ubuntu Lucid, native, remote, extended-remote.
gdb/gdbserver/ChangeLog:
* linux-low.c (handle_extended_wait): Implement return value,
rename argument 'event_child' to 'event_lwp', handle
PTRACE_EVENT_FORK, call internal_error for unrecognized event.
(linux_low_ptrace_options): New function.
(linux_low_filter_event): Call linux_low_ptrace_options,
use different argument fo linux_enable_event_reporting,
use return value from handle_extended_wait.
(extended_event_reported): New function.
(linux_wait_1): Call extended_event_reported and set
status to report fork events.
(linux_write_memory): Add pid to debug message.
(reset_lwp_ptrace_options_callback): New function.
(linux_handle_new_gdb_connection): New function.
(linux_target_ops): Initialize new structure member.
* linux-low.h (struct lwp_info) <waitstatus>: New member.
* lynx-low.c: Initialize new structure member.
* remote-utils.c (prepare_resume_reply): Implement stop reason
"fork" for "T" stop message.
* server.c (handle_query): Call handle_new_gdb_connection.
* server.h (report_fork_events): Declare global flag.
* target.h (struct target_ops) <handle_new_gdb_connection>:
New member.
(target_handle_new_gdb_connection): New macro.
* win32-low.c: Initialize new structure member.
gdb/ChangeLog:
* linux-nat.c (linux_nat_ptrace_options): New function.
(linux_init_ptrace, wait_lwp, linux_nat_filter_event):
Call linux_nat_ptrace_options and use different argument to
linux_enable_event_reporting.
(_initialize_linux_nat): Delete call to
linux_ptrace_set_additional_flags.
* nat/linux-ptrace.c (current_ptrace_options): Rename to
supported_ptrace_options.
(additional_flags): Delete variable.
(linux_check_ptrace_features): Use supported_ptrace_options.
(linux_test_for_tracesysgood, linux_test_for_tracefork):
Likewise, and remove additional_flags check.
(linux_enable_event_reporting): Change 'attached' argument to
'options'. Use supported_ptrace_options.
(ptrace_supports_feature): Change comment. Use
supported_ptrace_options.
(linux_ptrace_set_additional_flags): Delete function.
* nat/linux-ptrace.h (linux_ptrace_set_additional_flags):
Delete function prototype.
* remote.c (remote_fork_event_p): New function.
(remote_detach_pid): New function.
(remote_detach_1): Call remote_detach_pid, don't mourn inferior
if doing detach-on-fork.
(remote_follow_fork): New function.
(remote_parse_stop_reply): Handle new "T" stop reason "fork".
(remote_pid_to_str): Print "process" strings for pid/0/0 ptids.
(init_extended_remote_ops): Initialize to_follow_fork.
2015-05-12 18:52:43 +02:00
|
|
|
if (supported_ptrace_options == -1)
|
2013-08-23 01:46:30 +02:00
|
|
|
linux_check_ptrace_features ();
|
|
|
|
|
Extended-remote Linux follow fork
This patch implements basic support for follow-fork and detach-on-fork on
extended-remote Linux targets. Only 'fork' is supported in this patch;
'vfork' support is added n a subsequent patch. This patch depends on
the previous patches in the patch series.
Sufficient extended-remote functionality has been implemented here to pass
gdb.base/multi-forks.exp, as well as gdb.base/foll-fork.exp with the
catchpoint tests commented out. Some other fork tests fail with this
patch because it doesn't provide the architecture support needed for
watchpoint inheritance or fork catchpoints.
The implementation follows the same general structure as for the native
implementation as much as possible.
This implementation includes:
* enabling fork events in linux-low.c in initialize_low and
linux_enable_extended_features
* handling fork events in gdbserver/linux-low.c:handle_extended_wait
- when a fork event occurs in gdbserver, we must do the full creation
of the new process, thread, lwp, and breakpoint lists. This is
required whether or not the new child is destined to be
detached-on-fork, because GDB will make target calls that require all
the structures. In particular we need the breakpoint lists in order
to remove the breakpoints from a detaching child. If we are not
detaching the child we will need all these structures anyway.
- as part of this event handling we store the target_waitstatus in a new
member of the parent lwp_info structure, 'waitstatus'. This
is used to store extended event information for reporting to GDB.
- handle_extended_wait is given a return value, denoting whether the
handled event should be reported to GDB. Previously it had only
handled clone events, which were never reported.
* using a new predicate in gdbserver to control handling of the fork event
(and eventually all extended events) in linux_wait_1. The predicate,
extended_event_reported, checks a target_waitstatus.kind for an
extended ptrace event.
* implementing a new RSP 'T' Stop Reply Packet stop reason: "fork", in
gdbserver/remote-utils.c and remote.c.
* implementing new target and RSP support for target_follow_fork with
target extended-remote. (The RSP components were actually defined in
patch 1, but they see their first use here).
- remote target routine remote_follow_fork, which just sends the 'D;pid'
detach packet to detach the new fork child cleanly. We can't just
call target_detach because the data structures for the forked child
have not been allocated on the host side.
Tested on x64 Ubuntu Lucid, native, remote, extended-remote.
gdb/gdbserver/ChangeLog:
* linux-low.c (handle_extended_wait): Implement return value,
rename argument 'event_child' to 'event_lwp', handle
PTRACE_EVENT_FORK, call internal_error for unrecognized event.
(linux_low_ptrace_options): New function.
(linux_low_filter_event): Call linux_low_ptrace_options,
use different argument fo linux_enable_event_reporting,
use return value from handle_extended_wait.
(extended_event_reported): New function.
(linux_wait_1): Call extended_event_reported and set
status to report fork events.
(linux_write_memory): Add pid to debug message.
(reset_lwp_ptrace_options_callback): New function.
(linux_handle_new_gdb_connection): New function.
(linux_target_ops): Initialize new structure member.
* linux-low.h (struct lwp_info) <waitstatus>: New member.
* lynx-low.c: Initialize new structure member.
* remote-utils.c (prepare_resume_reply): Implement stop reason
"fork" for "T" stop message.
* server.c (handle_query): Call handle_new_gdb_connection.
* server.h (report_fork_events): Declare global flag.
* target.h (struct target_ops) <handle_new_gdb_connection>:
New member.
(target_handle_new_gdb_connection): New macro.
* win32-low.c: Initialize new structure member.
gdb/ChangeLog:
* linux-nat.c (linux_nat_ptrace_options): New function.
(linux_init_ptrace, wait_lwp, linux_nat_filter_event):
Call linux_nat_ptrace_options and use different argument to
linux_enable_event_reporting.
(_initialize_linux_nat): Delete call to
linux_ptrace_set_additional_flags.
* nat/linux-ptrace.c (current_ptrace_options): Rename to
supported_ptrace_options.
(additional_flags): Delete variable.
(linux_check_ptrace_features): Use supported_ptrace_options.
(linux_test_for_tracesysgood, linux_test_for_tracefork):
Likewise, and remove additional_flags check.
(linux_enable_event_reporting): Change 'attached' argument to
'options'. Use supported_ptrace_options.
(ptrace_supports_feature): Change comment. Use
supported_ptrace_options.
(linux_ptrace_set_additional_flags): Delete function.
* nat/linux-ptrace.h (linux_ptrace_set_additional_flags):
Delete function prototype.
* remote.c (remote_fork_event_p): New function.
(remote_detach_pid): New function.
(remote_detach_1): Call remote_detach_pid, don't mourn inferior
if doing detach-on-fork.
(remote_follow_fork): New function.
(remote_parse_stop_reply): Handle new "T" stop reason "fork".
(remote_pid_to_str): Print "process" strings for pid/0/0 ptids.
(init_extended_remote_ops): Initialize to_follow_fork.
2015-05-12 18:52:43 +02:00
|
|
|
/* We always want clone events. */
|
|
|
|
options |= PTRACE_O_TRACECLONE;
|
|
|
|
|
|
|
|
/* Filter out unsupported options. */
|
|
|
|
options &= supported_ptrace_options;
|
2014-11-11 07:07:21 +01:00
|
|
|
|
2013-08-23 01:46:30 +02:00
|
|
|
/* Set the options. */
|
|
|
|
ptrace (PTRACE_SETOPTIONS, pid, (PTRACE_TYPE_ARG3) 0,
|
Extended-remote Linux follow fork
This patch implements basic support for follow-fork and detach-on-fork on
extended-remote Linux targets. Only 'fork' is supported in this patch;
'vfork' support is added n a subsequent patch. This patch depends on
the previous patches in the patch series.
Sufficient extended-remote functionality has been implemented here to pass
gdb.base/multi-forks.exp, as well as gdb.base/foll-fork.exp with the
catchpoint tests commented out. Some other fork tests fail with this
patch because it doesn't provide the architecture support needed for
watchpoint inheritance or fork catchpoints.
The implementation follows the same general structure as for the native
implementation as much as possible.
This implementation includes:
* enabling fork events in linux-low.c in initialize_low and
linux_enable_extended_features
* handling fork events in gdbserver/linux-low.c:handle_extended_wait
- when a fork event occurs in gdbserver, we must do the full creation
of the new process, thread, lwp, and breakpoint lists. This is
required whether or not the new child is destined to be
detached-on-fork, because GDB will make target calls that require all
the structures. In particular we need the breakpoint lists in order
to remove the breakpoints from a detaching child. If we are not
detaching the child we will need all these structures anyway.
- as part of this event handling we store the target_waitstatus in a new
member of the parent lwp_info structure, 'waitstatus'. This
is used to store extended event information for reporting to GDB.
- handle_extended_wait is given a return value, denoting whether the
handled event should be reported to GDB. Previously it had only
handled clone events, which were never reported.
* using a new predicate in gdbserver to control handling of the fork event
(and eventually all extended events) in linux_wait_1. The predicate,
extended_event_reported, checks a target_waitstatus.kind for an
extended ptrace event.
* implementing a new RSP 'T' Stop Reply Packet stop reason: "fork", in
gdbserver/remote-utils.c and remote.c.
* implementing new target and RSP support for target_follow_fork with
target extended-remote. (The RSP components were actually defined in
patch 1, but they see their first use here).
- remote target routine remote_follow_fork, which just sends the 'D;pid'
detach packet to detach the new fork child cleanly. We can't just
call target_detach because the data structures for the forked child
have not been allocated on the host side.
Tested on x64 Ubuntu Lucid, native, remote, extended-remote.
gdb/gdbserver/ChangeLog:
* linux-low.c (handle_extended_wait): Implement return value,
rename argument 'event_child' to 'event_lwp', handle
PTRACE_EVENT_FORK, call internal_error for unrecognized event.
(linux_low_ptrace_options): New function.
(linux_low_filter_event): Call linux_low_ptrace_options,
use different argument fo linux_enable_event_reporting,
use return value from handle_extended_wait.
(extended_event_reported): New function.
(linux_wait_1): Call extended_event_reported and set
status to report fork events.
(linux_write_memory): Add pid to debug message.
(reset_lwp_ptrace_options_callback): New function.
(linux_handle_new_gdb_connection): New function.
(linux_target_ops): Initialize new structure member.
* linux-low.h (struct lwp_info) <waitstatus>: New member.
* lynx-low.c: Initialize new structure member.
* remote-utils.c (prepare_resume_reply): Implement stop reason
"fork" for "T" stop message.
* server.c (handle_query): Call handle_new_gdb_connection.
* server.h (report_fork_events): Declare global flag.
* target.h (struct target_ops) <handle_new_gdb_connection>:
New member.
(target_handle_new_gdb_connection): New macro.
* win32-low.c: Initialize new structure member.
gdb/ChangeLog:
* linux-nat.c (linux_nat_ptrace_options): New function.
(linux_init_ptrace, wait_lwp, linux_nat_filter_event):
Call linux_nat_ptrace_options and use different argument to
linux_enable_event_reporting.
(_initialize_linux_nat): Delete call to
linux_ptrace_set_additional_flags.
* nat/linux-ptrace.c (current_ptrace_options): Rename to
supported_ptrace_options.
(additional_flags): Delete variable.
(linux_check_ptrace_features): Use supported_ptrace_options.
(linux_test_for_tracesysgood, linux_test_for_tracefork):
Likewise, and remove additional_flags check.
(linux_enable_event_reporting): Change 'attached' argument to
'options'. Use supported_ptrace_options.
(ptrace_supports_feature): Change comment. Use
supported_ptrace_options.
(linux_ptrace_set_additional_flags): Delete function.
* nat/linux-ptrace.h (linux_ptrace_set_additional_flags):
Delete function prototype.
* remote.c (remote_fork_event_p): New function.
(remote_detach_pid): New function.
(remote_detach_1): Call remote_detach_pid, don't mourn inferior
if doing detach-on-fork.
(remote_follow_fork): New function.
(remote_parse_stop_reply): Handle new "T" stop reason "fork".
(remote_pid_to_str): Print "process" strings for pid/0/0 ptids.
(init_extended_remote_ops): Initialize to_follow_fork.
2015-05-12 18:52:43 +02:00
|
|
|
(PTRACE_TYPE_ARG4) (uintptr_t) options);
|
2013-08-23 01:46:30 +02:00
|
|
|
}
|
|
|
|
|
2014-06-08 13:11:09 +02:00
|
|
|
/* Disable reporting of all currently supported ptrace events. */
|
|
|
|
|
|
|
|
void
|
|
|
|
linux_disable_event_reporting (pid_t pid)
|
|
|
|
{
|
|
|
|
/* Set the options. */
|
|
|
|
ptrace (PTRACE_SETOPTIONS, pid, (PTRACE_TYPE_ARG3) 0, 0);
|
|
|
|
}
|
|
|
|
|
2013-08-23 01:46:30 +02:00
|
|
|
/* Returns non-zero if PTRACE_OPTIONS is contained within
|
Extended-remote Linux follow fork
This patch implements basic support for follow-fork and detach-on-fork on
extended-remote Linux targets. Only 'fork' is supported in this patch;
'vfork' support is added n a subsequent patch. This patch depends on
the previous patches in the patch series.
Sufficient extended-remote functionality has been implemented here to pass
gdb.base/multi-forks.exp, as well as gdb.base/foll-fork.exp with the
catchpoint tests commented out. Some other fork tests fail with this
patch because it doesn't provide the architecture support needed for
watchpoint inheritance or fork catchpoints.
The implementation follows the same general structure as for the native
implementation as much as possible.
This implementation includes:
* enabling fork events in linux-low.c in initialize_low and
linux_enable_extended_features
* handling fork events in gdbserver/linux-low.c:handle_extended_wait
- when a fork event occurs in gdbserver, we must do the full creation
of the new process, thread, lwp, and breakpoint lists. This is
required whether or not the new child is destined to be
detached-on-fork, because GDB will make target calls that require all
the structures. In particular we need the breakpoint lists in order
to remove the breakpoints from a detaching child. If we are not
detaching the child we will need all these structures anyway.
- as part of this event handling we store the target_waitstatus in a new
member of the parent lwp_info structure, 'waitstatus'. This
is used to store extended event information for reporting to GDB.
- handle_extended_wait is given a return value, denoting whether the
handled event should be reported to GDB. Previously it had only
handled clone events, which were never reported.
* using a new predicate in gdbserver to control handling of the fork event
(and eventually all extended events) in linux_wait_1. The predicate,
extended_event_reported, checks a target_waitstatus.kind for an
extended ptrace event.
* implementing a new RSP 'T' Stop Reply Packet stop reason: "fork", in
gdbserver/remote-utils.c and remote.c.
* implementing new target and RSP support for target_follow_fork with
target extended-remote. (The RSP components were actually defined in
patch 1, but they see their first use here).
- remote target routine remote_follow_fork, which just sends the 'D;pid'
detach packet to detach the new fork child cleanly. We can't just
call target_detach because the data structures for the forked child
have not been allocated on the host side.
Tested on x64 Ubuntu Lucid, native, remote, extended-remote.
gdb/gdbserver/ChangeLog:
* linux-low.c (handle_extended_wait): Implement return value,
rename argument 'event_child' to 'event_lwp', handle
PTRACE_EVENT_FORK, call internal_error for unrecognized event.
(linux_low_ptrace_options): New function.
(linux_low_filter_event): Call linux_low_ptrace_options,
use different argument fo linux_enable_event_reporting,
use return value from handle_extended_wait.
(extended_event_reported): New function.
(linux_wait_1): Call extended_event_reported and set
status to report fork events.
(linux_write_memory): Add pid to debug message.
(reset_lwp_ptrace_options_callback): New function.
(linux_handle_new_gdb_connection): New function.
(linux_target_ops): Initialize new structure member.
* linux-low.h (struct lwp_info) <waitstatus>: New member.
* lynx-low.c: Initialize new structure member.
* remote-utils.c (prepare_resume_reply): Implement stop reason
"fork" for "T" stop message.
* server.c (handle_query): Call handle_new_gdb_connection.
* server.h (report_fork_events): Declare global flag.
* target.h (struct target_ops) <handle_new_gdb_connection>:
New member.
(target_handle_new_gdb_connection): New macro.
* win32-low.c: Initialize new structure member.
gdb/ChangeLog:
* linux-nat.c (linux_nat_ptrace_options): New function.
(linux_init_ptrace, wait_lwp, linux_nat_filter_event):
Call linux_nat_ptrace_options and use different argument to
linux_enable_event_reporting.
(_initialize_linux_nat): Delete call to
linux_ptrace_set_additional_flags.
* nat/linux-ptrace.c (current_ptrace_options): Rename to
supported_ptrace_options.
(additional_flags): Delete variable.
(linux_check_ptrace_features): Use supported_ptrace_options.
(linux_test_for_tracesysgood, linux_test_for_tracefork):
Likewise, and remove additional_flags check.
(linux_enable_event_reporting): Change 'attached' argument to
'options'. Use supported_ptrace_options.
(ptrace_supports_feature): Change comment. Use
supported_ptrace_options.
(linux_ptrace_set_additional_flags): Delete function.
* nat/linux-ptrace.h (linux_ptrace_set_additional_flags):
Delete function prototype.
* remote.c (remote_fork_event_p): New function.
(remote_detach_pid): New function.
(remote_detach_1): Call remote_detach_pid, don't mourn inferior
if doing detach-on-fork.
(remote_follow_fork): New function.
(remote_parse_stop_reply): Handle new "T" stop reason "fork".
(remote_pid_to_str): Print "process" strings for pid/0/0 ptids.
(init_extended_remote_ops): Initialize to_follow_fork.
2015-05-12 18:52:43 +02:00
|
|
|
SUPPORTED_PTRACE_OPTIONS, therefore supported. Returns 0
|
2013-08-23 01:46:30 +02:00
|
|
|
otherwise. */
|
|
|
|
|
|
|
|
static int
|
|
|
|
ptrace_supports_feature (int ptrace_options)
|
|
|
|
{
|
Extended-remote Linux follow fork
This patch implements basic support for follow-fork and detach-on-fork on
extended-remote Linux targets. Only 'fork' is supported in this patch;
'vfork' support is added n a subsequent patch. This patch depends on
the previous patches in the patch series.
Sufficient extended-remote functionality has been implemented here to pass
gdb.base/multi-forks.exp, as well as gdb.base/foll-fork.exp with the
catchpoint tests commented out. Some other fork tests fail with this
patch because it doesn't provide the architecture support needed for
watchpoint inheritance or fork catchpoints.
The implementation follows the same general structure as for the native
implementation as much as possible.
This implementation includes:
* enabling fork events in linux-low.c in initialize_low and
linux_enable_extended_features
* handling fork events in gdbserver/linux-low.c:handle_extended_wait
- when a fork event occurs in gdbserver, we must do the full creation
of the new process, thread, lwp, and breakpoint lists. This is
required whether or not the new child is destined to be
detached-on-fork, because GDB will make target calls that require all
the structures. In particular we need the breakpoint lists in order
to remove the breakpoints from a detaching child. If we are not
detaching the child we will need all these structures anyway.
- as part of this event handling we store the target_waitstatus in a new
member of the parent lwp_info structure, 'waitstatus'. This
is used to store extended event information for reporting to GDB.
- handle_extended_wait is given a return value, denoting whether the
handled event should be reported to GDB. Previously it had only
handled clone events, which were never reported.
* using a new predicate in gdbserver to control handling of the fork event
(and eventually all extended events) in linux_wait_1. The predicate,
extended_event_reported, checks a target_waitstatus.kind for an
extended ptrace event.
* implementing a new RSP 'T' Stop Reply Packet stop reason: "fork", in
gdbserver/remote-utils.c and remote.c.
* implementing new target and RSP support for target_follow_fork with
target extended-remote. (The RSP components were actually defined in
patch 1, but they see their first use here).
- remote target routine remote_follow_fork, which just sends the 'D;pid'
detach packet to detach the new fork child cleanly. We can't just
call target_detach because the data structures for the forked child
have not been allocated on the host side.
Tested on x64 Ubuntu Lucid, native, remote, extended-remote.
gdb/gdbserver/ChangeLog:
* linux-low.c (handle_extended_wait): Implement return value,
rename argument 'event_child' to 'event_lwp', handle
PTRACE_EVENT_FORK, call internal_error for unrecognized event.
(linux_low_ptrace_options): New function.
(linux_low_filter_event): Call linux_low_ptrace_options,
use different argument fo linux_enable_event_reporting,
use return value from handle_extended_wait.
(extended_event_reported): New function.
(linux_wait_1): Call extended_event_reported and set
status to report fork events.
(linux_write_memory): Add pid to debug message.
(reset_lwp_ptrace_options_callback): New function.
(linux_handle_new_gdb_connection): New function.
(linux_target_ops): Initialize new structure member.
* linux-low.h (struct lwp_info) <waitstatus>: New member.
* lynx-low.c: Initialize new structure member.
* remote-utils.c (prepare_resume_reply): Implement stop reason
"fork" for "T" stop message.
* server.c (handle_query): Call handle_new_gdb_connection.
* server.h (report_fork_events): Declare global flag.
* target.h (struct target_ops) <handle_new_gdb_connection>:
New member.
(target_handle_new_gdb_connection): New macro.
* win32-low.c: Initialize new structure member.
gdb/ChangeLog:
* linux-nat.c (linux_nat_ptrace_options): New function.
(linux_init_ptrace, wait_lwp, linux_nat_filter_event):
Call linux_nat_ptrace_options and use different argument to
linux_enable_event_reporting.
(_initialize_linux_nat): Delete call to
linux_ptrace_set_additional_flags.
* nat/linux-ptrace.c (current_ptrace_options): Rename to
supported_ptrace_options.
(additional_flags): Delete variable.
(linux_check_ptrace_features): Use supported_ptrace_options.
(linux_test_for_tracesysgood, linux_test_for_tracefork):
Likewise, and remove additional_flags check.
(linux_enable_event_reporting): Change 'attached' argument to
'options'. Use supported_ptrace_options.
(ptrace_supports_feature): Change comment. Use
supported_ptrace_options.
(linux_ptrace_set_additional_flags): Delete function.
* nat/linux-ptrace.h (linux_ptrace_set_additional_flags):
Delete function prototype.
* remote.c (remote_fork_event_p): New function.
(remote_detach_pid): New function.
(remote_detach_1): Call remote_detach_pid, don't mourn inferior
if doing detach-on-fork.
(remote_follow_fork): New function.
(remote_parse_stop_reply): Handle new "T" stop reason "fork".
(remote_pid_to_str): Print "process" strings for pid/0/0 ptids.
(init_extended_remote_ops): Initialize to_follow_fork.
2015-05-12 18:52:43 +02:00
|
|
|
if (supported_ptrace_options == -1)
|
Linux: on attach, attach to lwps listed under /proc/$pid/task/
... instead of relying on libthread_db.
I wrote a test that attaches to a program that constantly spawns
short-lived threads, which exposed several issues. This is one of
them.
On Linux, we need to attach to all threads of a process (thread group)
individually. We currently rely on libthread_db to list the threads,
but that is problematic, because libthread_db relies on reading data
structures out of the inferior (which may well be corrupted). If
threads are being created or exiting just while we try to attach, we
may trip on inconsistencies in the inferior's thread list. To work
around that, when we see a seemingly corrupt list, we currently retry
a few times:
static void
thread_db_find_new_threads_2 (ptid_t ptid, int until_no_new)
{
...
if (until_no_new)
{
/* Require 4 successive iterations which do not find any new threads.
The 4 is a heuristic: there is an inherent race here, and I have
seen that 2 iterations in a row are not always sufficient to
"capture" all threads. */
...
That heuristic may well fail, and when it does, we end up with threads
in the program that aren't under GDB's control. That's obviously bad
and results in quite mistifying failures, like e.g., the process dying
for seeminly no reason when a thread that wasn't attached trips on a
breakpoint.
There's really no reason to rely on libthread_db for this nowadays
when we have /proc mounted. In that case, which is the usual case, we
can list the LWPs from /proc/PID/task/. In fact, GDBserver is already
doing this. The patch factors out that code that knows to walk the
task/ directory out of GDBserver, and makes GDB use it too.
Like GDBserver, the patch makes GDB attach to LWPs and _not_ wait for
them to stop immediately. Instead, we just tag the LWP as having an
expected stop. Because we can only set the ptrace options when the
thread stops, we need a new flag in the lwp structure to keep track of
whether we've already set the ptrace options, just like in GDBserver.
Note that nothing issues any ptrace command to the threads between the
PTRACE_ATTACH and the stop, so this is safe (unlike one scenario
described in gdbserver's linux-low.c).
When we attach to a program that has threads exiting while we attach,
it's easy to race with a thread just exiting as we try to attach to
it, like:
#1 - get current list of threads
#2 - attach to each listed thread
#3 - ooops, attach failed, thread is already gone
As this is pretty normal, we shouldn't be issuing a scary warning in
step #3.
When #3 happens, PTRACE_ATTACH usually fails with ESRCH, but sometimes
we'll see EPERM as well. That happens when the kernel still has the
thread in its task list, but the thread is marked as dead.
Unfortunately, EPERM is ambiguous and we'll get it also on other
scenarios where the thread isn't dead, and in those cases, it's useful
to get a warning. To distiguish the cases, when we get an EPERM
failure, we open /proc/PID/status, and check the thread's state -- if
the /proc file no longer exists, or the state is "Z (Zombie)" or "X
(Dead)", we ignore the EPERM error silently; otherwise, we'll warn.
Unfortunately, there seems to be a kernel race here. Sometimes I get
EPERM, and then the /proc state still indicates "R (Running)"... If
we wait a bit and retry, we do end up seeing X or Z state, or get an
ESRCH. I thought of making GDB retry the attach a few times, but even
with a 500ms wait and 4 retries, I still see the warning sometimes. I
haven't been able to identify the kernel path that causes this yet,
but in any case, it looks like a kernel bug to me. As this just
results failure to suppress a warning that we've been printing since
about forever anyway, I'm just making the test cope with it, and issue
an XFAIL.
gdb/gdbserver/
2015-01-09 Pedro Alves <palves@redhat.com>
* linux-low.c (linux_attach_fail_reason_string): Move to
nat/linux-ptrace.c, and rename.
(linux_attach_lwp): Update comment.
(attach_proc_task_lwp_callback): New function.
(linux_attach): Adjust to rename and use
linux_proc_attach_tgid_threads.
(linux_attach_fail_reason_string): Delete declaration.
gdb/
2015-01-09 Pedro Alves <palves@redhat.com>
* linux-nat.c (attach_proc_task_lwp_callback): New function.
(linux_nat_attach): Use linux_proc_attach_tgid_threads.
(wait_lwp, linux_nat_filter_event): If not set yet, set the lwp's
ptrace option flags.
* linux-nat.h (struct lwp_info) <must_set_ptrace_flags>: New
field.
* nat/linux-procfs.c: Include <dirent.h>.
(linux_proc_get_int): New parameter "warn". Handle it.
(linux_proc_get_tgid): Adjust.
(linux_proc_get_tracerpid): Rename to ...
(linux_proc_get_tracerpid_nowarn): ... this.
(linux_proc_pid_get_state): New function, factored out from
(linux_proc_pid_has_state): ... this. Add new parameter "warn"
and handle it.
(linux_proc_pid_is_gone): New function.
(linux_proc_pid_is_stopped): Adjust.
(linux_proc_pid_is_zombie_maybe_warn)
(linux_proc_pid_is_zombie_nowarn): New functions.
(linux_proc_pid_is_zombie): Use
linux_proc_pid_is_zombie_maybe_warn.
(linux_proc_attach_tgid_threads): New function.
* nat/linux-procfs.h (linux_proc_get_tgid): Update comment.
(linux_proc_get_tracerpid): Rename to ...
(linux_proc_get_tracerpid_nowarn): ... this, and update comment.
(linux_proc_pid_is_gone): New declaration.
(linux_proc_pid_is_zombie): Update comment.
(linux_proc_pid_is_zombie_nowarn): New declaration.
(linux_proc_attach_lwp_func): New typedef.
(linux_proc_attach_tgid_threads): New declaration.
* nat/linux-ptrace.c (linux_ptrace_attach_fail_reason): Adjust to
use nowarn functions.
(linux_ptrace_attach_fail_reason_string): Move here from
gdbserver/linux-low.c and rename.
(ptrace_supports_feature): If the current ptrace options are not
known yet, check them now, instead of asserting.
* nat/linux-ptrace.h (linux_ptrace_attach_fail_reason_string):
Declare.
2014-12-16 17:12:24 +01:00
|
|
|
linux_check_ptrace_features ();
|
2013-08-23 01:46:30 +02:00
|
|
|
|
Extended-remote Linux follow fork
This patch implements basic support for follow-fork and detach-on-fork on
extended-remote Linux targets. Only 'fork' is supported in this patch;
'vfork' support is added n a subsequent patch. This patch depends on
the previous patches in the patch series.
Sufficient extended-remote functionality has been implemented here to pass
gdb.base/multi-forks.exp, as well as gdb.base/foll-fork.exp with the
catchpoint tests commented out. Some other fork tests fail with this
patch because it doesn't provide the architecture support needed for
watchpoint inheritance or fork catchpoints.
The implementation follows the same general structure as for the native
implementation as much as possible.
This implementation includes:
* enabling fork events in linux-low.c in initialize_low and
linux_enable_extended_features
* handling fork events in gdbserver/linux-low.c:handle_extended_wait
- when a fork event occurs in gdbserver, we must do the full creation
of the new process, thread, lwp, and breakpoint lists. This is
required whether or not the new child is destined to be
detached-on-fork, because GDB will make target calls that require all
the structures. In particular we need the breakpoint lists in order
to remove the breakpoints from a detaching child. If we are not
detaching the child we will need all these structures anyway.
- as part of this event handling we store the target_waitstatus in a new
member of the parent lwp_info structure, 'waitstatus'. This
is used to store extended event information for reporting to GDB.
- handle_extended_wait is given a return value, denoting whether the
handled event should be reported to GDB. Previously it had only
handled clone events, which were never reported.
* using a new predicate in gdbserver to control handling of the fork event
(and eventually all extended events) in linux_wait_1. The predicate,
extended_event_reported, checks a target_waitstatus.kind for an
extended ptrace event.
* implementing a new RSP 'T' Stop Reply Packet stop reason: "fork", in
gdbserver/remote-utils.c and remote.c.
* implementing new target and RSP support for target_follow_fork with
target extended-remote. (The RSP components were actually defined in
patch 1, but they see their first use here).
- remote target routine remote_follow_fork, which just sends the 'D;pid'
detach packet to detach the new fork child cleanly. We can't just
call target_detach because the data structures for the forked child
have not been allocated on the host side.
Tested on x64 Ubuntu Lucid, native, remote, extended-remote.
gdb/gdbserver/ChangeLog:
* linux-low.c (handle_extended_wait): Implement return value,
rename argument 'event_child' to 'event_lwp', handle
PTRACE_EVENT_FORK, call internal_error for unrecognized event.
(linux_low_ptrace_options): New function.
(linux_low_filter_event): Call linux_low_ptrace_options,
use different argument fo linux_enable_event_reporting,
use return value from handle_extended_wait.
(extended_event_reported): New function.
(linux_wait_1): Call extended_event_reported and set
status to report fork events.
(linux_write_memory): Add pid to debug message.
(reset_lwp_ptrace_options_callback): New function.
(linux_handle_new_gdb_connection): New function.
(linux_target_ops): Initialize new structure member.
* linux-low.h (struct lwp_info) <waitstatus>: New member.
* lynx-low.c: Initialize new structure member.
* remote-utils.c (prepare_resume_reply): Implement stop reason
"fork" for "T" stop message.
* server.c (handle_query): Call handle_new_gdb_connection.
* server.h (report_fork_events): Declare global flag.
* target.h (struct target_ops) <handle_new_gdb_connection>:
New member.
(target_handle_new_gdb_connection): New macro.
* win32-low.c: Initialize new structure member.
gdb/ChangeLog:
* linux-nat.c (linux_nat_ptrace_options): New function.
(linux_init_ptrace, wait_lwp, linux_nat_filter_event):
Call linux_nat_ptrace_options and use different argument to
linux_enable_event_reporting.
(_initialize_linux_nat): Delete call to
linux_ptrace_set_additional_flags.
* nat/linux-ptrace.c (current_ptrace_options): Rename to
supported_ptrace_options.
(additional_flags): Delete variable.
(linux_check_ptrace_features): Use supported_ptrace_options.
(linux_test_for_tracesysgood, linux_test_for_tracefork):
Likewise, and remove additional_flags check.
(linux_enable_event_reporting): Change 'attached' argument to
'options'. Use supported_ptrace_options.
(ptrace_supports_feature): Change comment. Use
supported_ptrace_options.
(linux_ptrace_set_additional_flags): Delete function.
* nat/linux-ptrace.h (linux_ptrace_set_additional_flags):
Delete function prototype.
* remote.c (remote_fork_event_p): New function.
(remote_detach_pid): New function.
(remote_detach_1): Call remote_detach_pid, don't mourn inferior
if doing detach-on-fork.
(remote_follow_fork): New function.
(remote_parse_stop_reply): Handle new "T" stop reason "fork".
(remote_pid_to_str): Print "process" strings for pid/0/0 ptids.
(init_extended_remote_ops): Initialize to_follow_fork.
2015-05-12 18:52:43 +02:00
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return ((supported_ptrace_options & ptrace_options) == ptrace_options);
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2013-08-23 01:46:30 +02:00
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}
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/* Returns non-zero if PTRACE_EVENT_FORK is supported by ptrace,
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0 otherwise. Note that if PTRACE_EVENT_FORK is supported so is
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PTRACE_EVENT_CLONE, PTRACE_EVENT_EXEC and PTRACE_EVENT_VFORK,
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since they were all added to the kernel at the same time. */
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int
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linux_supports_tracefork (void)
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{
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return ptrace_supports_feature (PTRACE_O_TRACEFORK);
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}
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/* Returns non-zero if PTRACE_EVENT_CLONE is supported by ptrace,
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0 otherwise. Note that if PTRACE_EVENT_CLONE is supported so is
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PTRACE_EVENT_FORK, PTRACE_EVENT_EXEC and PTRACE_EVENT_VFORK,
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since they were all added to the kernel at the same time. */
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int
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linux_supports_traceclone (void)
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{
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return ptrace_supports_feature (PTRACE_O_TRACECLONE);
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}
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/* Returns non-zero if PTRACE_O_TRACEVFORKDONE is supported by
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ptrace, 0 otherwise. */
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int
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linux_supports_tracevforkdone (void)
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{
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return ptrace_supports_feature (PTRACE_O_TRACEVFORKDONE);
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}
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/* Returns non-zero if PTRACE_O_TRACESYSGOOD is supported by ptrace,
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0 otherwise. */
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int
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linux_supports_tracesysgood (void)
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{
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return ptrace_supports_feature (PTRACE_O_TRACESYSGOOD);
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}
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2012-07-07 14:13:57 +02:00
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/* Display possible problems on this system. Display them only once per GDB
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execution. */
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void
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linux_ptrace_init_warnings (void)
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{
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static int warned = 0;
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if (warned)
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return;
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warned = 1;
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linux_ptrace_test_ret_to_nx ();
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}
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2014-01-03 18:55:52 +01:00
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2014-09-19 19:54:34 +02:00
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/* Extract extended ptrace event from wait status. */
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int
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linux_ptrace_get_extended_event (int wstat)
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{
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return (wstat >> 16);
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}
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/* Determine whether wait status denotes an extended event. */
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int
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linux_is_extended_waitstatus (int wstat)
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{
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return (linux_ptrace_get_extended_event (wstat) != 0);
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}
|
2015-02-12 20:55:08 +01:00
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/* Return true if the event in LP may be caused by breakpoint. */
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int
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linux_wstatus_maybe_breakpoint (int wstat)
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{
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return (WIFSTOPPED (wstat)
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&& (WSTOPSIG (wstat) == SIGTRAP
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/* SIGILL and SIGSEGV are also treated as traps in case a
|
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breakpoint is inserted at the current PC. */
|
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|| WSTOPSIG (wstat) == SIGILL
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|| WSTOPSIG (wstat) == SIGSEGV));
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}
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