binutils-gdb/gdb/gdbserver
Joel Brobecker beed38b827 [Linux] Ask kernel to kill inferior when GDB terminates
This patch enhances GDB on GNU/Linux systems in the situation where
we are debugging an inferior that was created from GDB (as opposed
to attached to), by asking the kernel to kill the inferior if GDB
terminates without doing it itself.

This would typically happen when GDB encounters a problem and
crashes, or when it gets killed by an external process. This can
be observed by starting a program under GDB, and then killing
GDB with signal 9. After GDB is killed, the inferior still remains.

This patch also fixes GDBserver similarly.

This fix is conditional on the kernel supporting the PTRACE_O_EXITKILL
feature.  On older kernels, the behavior remains unchanged.

gdb/ChangeLog:

        * nat/linux-ptrace.h (PTRACE_O_EXITKILL): Define if not
        already defined.
        (linux_enable_event_reporting): Add parameter "attached".
        * nat/linux-ptrace.c (linux_test_for_exitkill): New forward
        declaration.  New function.
        (linux_check_ptrace_features): Add linux_test_for_exitkill call.
        (linux_enable_event_reporting): Add new parameter "attached".
        Do not call ptrace with the PTRACE_O_EXITKILL if ATTACHED is
        nonzero.
        * linux-nat.c (linux_init_ptrace): Add parameter "attached".
        Use it.  Update function description.
        (linux_child_post_attach, linux_child_post_startup_inferior):
        Update call to linux_enable_event_reporting.

gdb/gdbserver/ChangeLog:

        * linux-low.c (linux_low_filter_event): Update call to
        linux_enable_event_reporting following the addition of
        a new parameter to that function.

Tested on x86_64-linux, native and native-gdbserver.

I also verified by hand that the inferior gets killed when killing
GDB in the "run" case, while the inferior remains in the "attach"
case. Same for GDBserver.
2014-12-16 07:56:46 -05:00
..
.gitignore
acinclude.m4
aclocal.m4
ax.c
ax.h
ChangeLog [Linux] Ask kernel to kill inferior when GDB terminates 2014-12-16 07:56:46 -05:00
config.in Use readlink unconditionally 2014-11-28 18:37:52 +08:00
configure configure gdb/gnulib with --disable-largefile if largefile support disabled. 2014-12-13 09:45:57 -05:00
configure.ac configure gdb/gnulib with --disable-largefile if largefile support disabled. 2014-12-13 09:45:57 -05:00
configure.srv
debug.c
debug.h
dll.c
dll.h
event-loop.c
event-loop.h
gdb_proc_service.h
gdbreplay.c Include alloca.h unconditionally 2014-11-21 22:05:41 +08:00
gdbthread.h
hostio-errno.c
hostio.c Use readlink unconditionally 2014-11-28 18:37:52 +08:00
hostio.h
i387-fp.c
i387-fp.h
inferiors.c
inferiors.h
linux-aarch64-low.c aarch64/gdbserver: fix floating point registers display 2014-12-16 09:51:42 +02:00
linux-amd64-ipa.c
linux-arm-low.c
linux-bfin-low.c
linux-cris-low.c
linux-crisv32-low.c
linux-i386-ipa.c
linux-ia64-low.c
linux-low.c [Linux] Ask kernel to kill inferior when GDB terminates 2014-12-16 07:56:46 -05:00
linux-low.h
linux-m32r-low.c
linux-m68k-low.c
linux-mips-low.c
linux-nios2-low.c
linux-ppc-low.c
linux-s390-low.c S390: Fix gdbserver support for TDB 2014-12-12 14:15:07 +01:00
linux-sh-low.c
linux-sparc-low.c
linux-tic6x-low.c
linux-tile-low.c
linux-x86-low.c
linux-xtensa-low.c
lynx-i386-low.c
lynx-low.c Use PTRACE_SINGLESTEP_ONE when single-stepping one thread. 2014-12-15 09:53:56 -05:00
lynx-low.h
lynx-ppc-low.c
Makefile.in
mem-break.c
mem-break.h
notif.c
notif.h
nto-low.c
nto-low.h
nto-x86-low.c
proc-service.c
proc-service.list
README
regcache.c gdbserver: Prevent stale/random values in register cache 2014-12-12 14:15:07 +01:00
regcache.h
remote-utils.c
remote-utils.h
server.c GDBserver: clean up 'cont_thread' handling 2014-11-12 11:30:49 +00:00
server.h Include alloca.h unconditionally 2014-11-21 22:05:41 +08:00
spu-low.c
symbol.c
target.c
target.h
tdesc.c
tdesc.h
terminal.h
thread-db.c
tracepoint.c
tracepoint.h
utils.c
utils.h
win32-arm-low.c gdbserver/win32: Rewrite debug registers handling 2014-10-15 19:55:50 +01:00
win32-i386-low.c gdbserver/win32: Rewrite debug registers handling 2014-10-15 19:55:50 +01:00
win32-low.c gdbserver/win32: Rewrite debug registers handling 2014-10-15 19:55:50 +01:00
win32-low.h gdbserver/win32: Rewrite debug registers handling 2014-10-15 19:55:50 +01:00
wincecompat.c
wincecompat.h
x86-low.c
x86-low.h
xtensa-xtregs.c

		   README for GDBserver & GDBreplay
		    by Stu Grossman and Fred Fish

Introduction:

This is GDBserver, a remote server for Un*x-like systems.  It can be used to
control the execution of a program on a target system from a GDB on a different
host.  GDB and GDBserver communicate using the standard remote serial protocol
implemented in remote.c, and various *-stub.c files.  They communicate via
either a serial line or a TCP connection.

For more information about GDBserver, see the GDB manual.

Usage (server (target) side):

First, you need to have a copy of the program you want to debug put onto
the target system.  The program can be stripped to save space if needed, as
GDBserver doesn't care about symbols.  All symbol handling is taken care of by
the GDB running on the host system.

To use the server, you log on to the target system, and run the `gdbserver'
program.  You must tell it (a) how to communicate with GDB, (b) the name of
your program, and (c) its arguments.  The general syntax is:

	target> gdbserver COMM PROGRAM [ARGS ...]

For example, using a serial port, you might say:

	target> gdbserver /dev/com1 emacs foo.txt

This tells GDBserver to debug emacs with an argument of foo.txt, and to
communicate with GDB via /dev/com1.  GDBserver now waits patiently for the
host GDB to communicate with it.

To use a TCP connection, you could say:

	target> gdbserver host:2345 emacs foo.txt

This says pretty much the same thing as the last example, except that we are
going to communicate with the host GDB via TCP.  The `host:2345' argument means
that we are expecting to see a TCP connection from `host' to local TCP port
2345.  (Currently, the `host' part is ignored.)  You can choose any number you
want for the port number as long as it does not conflict with any existing TCP
ports on the target system.  This same port number must be used in the host
GDBs `target remote' command, which will be described shortly.  Note that if
you chose a port number that conflicts with another service, GDBserver will
print an error message and exit.

On some targets, GDBserver can also attach to running programs.  This is
accomplished via the --attach argument.  The syntax is:

	target> gdbserver --attach COMM PID

PID is the process ID of a currently running process.  It isn't necessary
to point GDBserver at a binary for the running process.

Usage (host side):

You need an unstripped copy of the target program on your host system, since
GDB needs to examine it's symbol tables and such.  Start up GDB as you normally
would, with the target program as the first argument.  (You may need to use the
--baud option if the serial line is running at anything except 9600 baud.)
Ie: `gdb TARGET-PROG', or `gdb --baud BAUD TARGET-PROG'.  After that, the only
new command you need to know about is `target remote'.  It's argument is either
a device name (usually a serial device, like `/dev/ttyb'), or a HOST:PORT
descriptor.  For example:

	(gdb) target remote /dev/ttyb

communicates with the server via serial line /dev/ttyb, and:

	(gdb) target remote the-target:2345

communicates via a TCP connection to port 2345 on host `the-target', where
you previously started up GDBserver with the same port number.  Note that for
TCP connections, you must start up GDBserver prior to using the `target remote'
command, otherwise you may get an error that looks something like
`Connection refused'.

Building GDBserver:

The supported targets as of November 2006 are:
	arm-*-linux*
	bfin-*-uclinux
	bfin-*-linux-uclibc
	crisv32-*-linux*
	cris-*-linux*
	i[34567]86-*-cygwin*
	i[34567]86-*-linux*
	i[34567]86-*-mingw*
	ia64-*-linux*
	m32r*-*-linux*
	m68*-*-linux*
	m68*-*-uclinux*
	mips*64*-*-linux*
	mips*-*-linux*
	powerpc[64]-*-linux*
	s390[x]-*-linux*
	sh-*-linux*
	spu*-*-*
	x86_64-*-linux*

Configuring GDBserver you should specify the same machine for host and
target (which are the machine that GDBserver is going to run on.  This
is not the same as the machine that GDB is going to run on; building
GDBserver automatically as part of building a whole tree of tools does
not currently work if cross-compilation is involved (we don't get the
right CC in the Makefile, to start with)).

Building GDBserver for your target is very straightforward.  If you build
GDB natively on a target which GDBserver supports, it will be built
automatically when you build GDB.  You can also build just GDBserver:

	% mkdir obj
	% cd obj
	% path-to-gdbserver-sources/configure
	% make

If you prefer to cross-compile to your target, then you can also build
GDBserver that way.  In a Bourne shell, for example:

	% export CC=your-cross-compiler
	% path-to-gdbserver-sources/configure your-target-name
	% make

Using GDBreplay:

A special hacked down version of GDBserver can be used to replay remote
debug log files created by GDB.  Before using the GDB "target" command to
initiate a remote debug session, use "set remotelogfile <filename>" to tell
GDB that you want to make a recording of the serial or tcp session.  Note
that when replaying the session, GDB communicates with GDBreplay via tcp,
regardless of whether the original session was via a serial link or tcp.

Once you are done with the remote debug session, start GDBreplay and
tell it the name of the log file and the host and port number that GDB
should connect to (typically the same as the host running GDB):

	$ gdbreplay logfile host:port

Then start GDB (preferably in a different screen or window) and use the
"target" command to connect to GDBreplay:

	(gdb) target remote host:port

Repeat the same sequence of user commands to GDB that you gave in the
original debug session.  GDB should not be able to tell that it is talking
to GDBreplay rather than a real target, all other things being equal.  Note
that GDBreplay echos the command lines to stderr, as well as the contents of
the packets it sends and receives.  The last command echoed by GDBreplay is
the next command that needs to be typed to GDB to continue the session in
sync with the original session.