Currently kgdb has absolutely no safety rails in place to discourage or
prevent a user from placing a breakpoint in dangerous places such as
the debugger's own trap entry/exit and other places where it is not safe
to take synchronous traps.
Introduce a new config symbol KGDB_HONOUR_BLOCKLIST and modify the
default implementation of kgdb_validate_break_address() so that we use
the kprobe blocklist to prohibit instrumentation of critical functions
if the config symbol is set. The config symbol dependencies are set to
ensure that the blocklist will be enabled by default if we enable KGDB
and are compiling for an architecture where we HAVE_KPROBES.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20200927211531.1380577-2-daniel.thompson@linaro.org
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
The XML packet could be supported by required architecture if the
architecture defines CONFIG_HAVE_ARCH_KGDB_QXFER_PKT and implement its own
kgdb_arch_handle_qxfer_pkt(). Except for the kgdb_arch_handle_qxfer_pkt(),
the architecture also needs to record the feature supported by gdb stub
into the kgdb_arch_gdb_stub_feature, and these features will be reported
to host gdb when gdb stub receives the qSupported packet.
Signed-off-by: Vincent Chen <vincent.chen@sifive.com>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
Using kgdb requires at least some level of architecture-level
initialization. If nothing else, it relies on the architecture to
pass breakpoints / crashes onto kgdb.
On some architectures this all works super early, specifically it
starts working at some point in time before Linux parses
early_params's. On other architectures it doesn't. A survey of a few
platforms:
a) x86: Presumably it all works early since "ekgdboc" is documented to
work here.
b) arm64: Catching crashes works; with a simple patch breakpoints can
also be made to work.
c) arm: Nothing in kgdb works until
paging_init() -> devicemaps_init() -> early_trap_init()
Let's be conservative and, by default, process "kgdbwait" (which tells
the kernel to drop into the debugger ASAP at boot) a bit later at
dbg_late_init() time. If an architecture has tested it and wants to
re-enable super early debugging, they can select the
ARCH_HAS_EARLY_DEBUG KConfig option. We'll do this for x86 to start.
It should be noted that dbg_late_init() is still called quite early in
the system.
Note that this patch doesn't affect when kgdb runs its init. If kgdb
is set to initialize early it will still initialize when parsing
early_param's. This patch _only_ inhibits the initial breakpoint from
"kgdbwait". This means:
* Without any extra patches arm64 platforms will at least catch
crashes after kgdb inits.
* arm platforms will catch crashes (and could handle a hardcoded
kgdb_breakpoint()) any time after early_trap_init() runs, even
before dbg_late_init().
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20200507130644.v4.4.I3113aea1b08d8ce36dc3720209392ae8b815201b@changeid
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Adjust indentation from spaces to tab (+optional two spaces) as in
coding style with command like:
$ sed -e 's/^ / /' -i */Kconfig
Link: http://lkml.kernel.org/r/20191120140140.19148-1-krzk@kernel.org
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add SPDX license identifiers to all Make/Kconfig files which:
- Have no license information of any form
These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:
GPL-2.0-only
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
With VT=n, the kernel build fails with:
drivers/built-in.o: In function `kgdboc_pre_exp_handler':
kgdboc.c:(.text+0x7b5aa): undefined reference to `fg_console'
kgdboc.c:(.text+0x7b5ce): undefined reference to `vc_cons'
kgdboc.c:(.text+0x7b5d5): undefined reference to `vc_cons'
kgdboc.o is built when KGDB_SERIAL_CONSOLE is set. So make
KGDB_SERIAL_CONSOLE depend on HW_CONSOLE which includes those symbols.
Link: http://lkml.kernel.org/r/1459412955-4696-1-git-send-email-jslaby@suse.cz
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Reported-by: "Jim Davis" <jim.epost@gmail.com>
Acked-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently kiosk mode must be explicitly requested by the bootloader or
userspace. It is convenient to be able to change the default value in a
similar manner to CONFIG_MAGIC_SYSRQ_DEFAULT_MASK.
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Correct spelling typo in printk within various drivers.
Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Cleanups
Remove kdb ssb command - there is no in kernel disassembler to support it
Remove kdb ll command - Always caused a kernel oops and there were no
bug reports so no one was using this command
Use kernel ARRAY_SIZE macro instead of array computations
Fixes
Stop oops in kdb if user executes kdb_defcmd with args
kdb help command truncated text
ppc64 support for kgdbts
Add missing kconfig option from original kdb port for dealing with
catastrophic kernel crashes such that you can reboot automatically
on continue from kdb
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Merge tag 'for_linux-3.9' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb
Pull KGDB/KDB fixes and cleanups from Jason Wessel:
"For a change we removed more code than we added. If people aren't
using it we shouldn't be carrying it. :-)
Cleanups:
- Remove kdb ssb command - there is no in kernel disassembler to
support it
- Remove kdb ll command - Always caused a kernel oops and there were
no bug reports so no one was using this command
- Use kernel ARRAY_SIZE macro instead of array computations
Fixes:
- Stop oops in kdb if user executes kdb_defcmd with args
- kdb help command truncated text
- ppc64 support for kgdbts
- Add missing kconfig option from original kdb port for dealing with
catastrophic kernel crashes such that you can reboot automatically
on continue from kdb"
* tag 'for_linux-3.9' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb:
kdb: Remove unhandled ssb command
kdb: Prevent kernel oops with kdb_defcmd
kdb: Remove the ll command
kdb_main: fix help print
kdb: Fix overlap in buffers with strcpy
Fixed dead ifdef block by adding missing Kconfig option.
kdb: Setup basic kdb state before invoking commands via kgdb
kdb: use ARRAY_SIZE where possible
kgdb/kgdbts: support ppc64
kdb: A fix for kdb command table expansion
Added missing Kconfig option KDB_CONTINUE_CATASTROPHIC which lead to a dead
ifdef block in kernel/debug/kdb/kdb_main.c:73-75.
The code using KDB_CONTINUE_CATASTROPHIC was originally introduced in
commit '5d5314d6795f3c1c0f415348ff8c51f7de042b77' by Jason Wessel.
This patchset ("kdb: core for kgdb back end (1 of 2)")
added platform independent part of kdb to the linux kernel.
The Kernel option however, even though it had the same options and
behaviour on all supported architectures, was part of the x86 and
ia64 patchset of KDB and therefore not pulled into the mainline kernel tree.
I actually took the originally written Kconfig by
Keith Owens <kaos@sgi.com> (2003-06-20 according to KDB changelog)
and changed it to reflect the correct behaviour,
as the KDUMP patchset is not part of the kernel and the expected
functionality is missing from it.
Signed-off-by: Robert Obermeier <obbi89@googlemail.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Here's the big tty/serial driver patches for 3.9-rc1.
More tty port rework and fixes from Jiri here, as well as lots of
individual serial driver updates and fixes.
All of these have been in the linux-next tree for a while.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'tty-3.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
Pull tty/serial patches from Greg Kroah-Hartman:
"Here's the big tty/serial driver patches for 3.9-rc1.
More tty port rework and fixes from Jiri here, as well as lots of
individual serial driver updates and fixes.
All of these have been in the linux-next tree for a while."
* tag 'tty-3.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (140 commits)
tty: mxser: improve error handling in mxser_probe() and mxser_module_init()
serial: imx: fix uninitialized variable warning
serial: tegra: assume CONFIG_OF
TTY: do not update atime/mtime on read/write
lguest: select CONFIG_TTY to build properly.
ARM defconfigs: add missing inclusions of linux/platform_device.h
fb/exynos: include platform_device.h
ARM: sa1100/assabet: include platform_device.h directly
serial: imx: Fix recursive locking bug
pps: Fix build breakage from decoupling pps from tty
tty: Remove ancient hardpps()
pps: Additional cleanups in uart_handle_dcd_change
pps: Move timestamp read into PPS code proper
pps: Don't crash the machine when exiting will do
pps: Fix a use-after free bug when unregistering a source.
pps: Use pps_lookup_dev to reduce ldisc coupling
pps: Add pps_lookup_dev() function
tty: serial: uartlite: Support uartlite on big and little endian systems
tty: serial: uartlite: Fix sparse and checkpatch warnings
serial/arc-uart: Miscll DT related updates (Grant's review comments)
...
Fix up trivial conflicts, mostly just due to the TTY config option
clashing with the EXPERIMENTAL removal.
The option allows you to remove TTY and compile without errors. This
saves space on systems that won't support TTY interfaces anyway.
bloat-o-meter output is below.
The bulk of this patch consists of Kconfig changes adding "depends on
TTY" to various serial devices and similar drivers that require the TTY
layer. Ideally, these dependencies would occur on a common intermediate
symbol such as SERIO, but most drivers "select SERIO" rather than
"depends on SERIO", and "select" does not respect dependencies.
bloat-o-meter output comparing our previous minimal to new minimal by
removing TTY. The list is filtered to not show removed entries with awk
'$3 != "-"' as the list was very long.
add/remove: 0/226 grow/shrink: 2/14 up/down: 6/-35356 (-35350)
function old new delta
chr_dev_init 166 170 +4
allow_signal 80 82 +2
static.__warned 143 142 -1
disallow_signal 63 62 -1
__set_special_pids 95 94 -1
unregister_console 126 121 -5
start_kernel 546 541 -5
register_console 593 588 -5
copy_from_user 45 40 -5
sys_setsid 128 120 -8
sys_vhangup 32 19 -13
do_exit 1543 1526 -17
bitmap_zero 60 40 -20
arch_local_irq_save 137 117 -20
release_task 674 652 -22
static.spin_unlock_irqrestore 308 260 -48
Signed-off-by: Joe Millenbach <jmillenbach@gmail.com>
Reviewed-by: Jamey Sharp <jamey@minilop.net>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The CONFIG_EXPERIMENTAL config item has not carried much meaning for a
while now and is almost always enabled by default. As agreed during the
Linux kernel summit, remove it from any "depends on" lines in Kconfigs.
CC: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
CC: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
CC: James Morris <james.l.morris@oracle.com>
CC: "Michael S. Tsirkin" <mst@redhat.com>
CC: Akinobu Mita <akinobu.mita@gmail.com>
CC: Ingo Molnar <mingo@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The only way the debugger can handle a trap in inside rcu_lock,
notify_die, or atomic_notifier_call_chain without a recursive fault is
to have a low level "first opportunity handler" do_trap_or_bp() handler.
Generally this will be something the vast majority of folks will not
need, but for those who need it, it is added as a kernel .config
option called KGDB_LOW_LEVEL_TRAP.
Also added was a die notification for oops such that kdb can catch an
oops for analysis.
There appeared to be no obvious way to pass the struct pt_regs from
the original exception back to the stack back tracer, so a special
case was added to show_stack() for when kdb is active because you
generally desire to generally look at the back trace of the original
exception.
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
The only way the debugger can handle a trap in inside rcu_lock,
notify_die, or atomic_notifier_call_chain without a triple fault is
to have a low level "first opportunity handler" in the int3 exception
handler.
Generally this will be something the vast majority of folks will not
need, but for those who need it, it is added as a kernel .config
option called KGDB_LOW_LEVEL_TRAP.
CC: Ingo Molnar <mingo@elte.hu>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: H. Peter Anvin <hpa@zytor.com>
CC: x86@kernel.org
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
This patch adds in the kdb PS/2 keyboard driver. This was mostly a
direct port from the original kdb where I cleaned up the code against
checkpatch.pl and added the glue to stitch it into kgdb.
This patch also enables early kdb debug via kgdbwait and the keyboard.
All the access to configure kdb using either a serial console or the
keyboard is done via kgdboc.
If you want to use only the keyboard and want to break in early you
would add to your kernel command arguments:
kgdboc=kbd kgdbwait
If you wanted serial and or the keyboard access you could use:
kgdboc=kbd,ttyS0
You can also configure kgdboc as a kernel module or at run time with
the sysfs where you can activate and deactivate kgdb.
Turn it on:
echo kbd,ttyS0 > /sys/module/kgdboc/parameters/kgdboc
Turn it off:
echo "" > /sys/module/kgdboc/parameters/kgdboc
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
These are the minimum changes to the kgdb core in order to enable an
API to connect a new front end (kdb) to the debug core.
This patch introduces the dbg_kdb_mode variable controls where the
user level I/O is routed. It will be routed to the gdbstub (kgdb) or
to the kdb front end which is a simple shell available over the kgdboc
connection.
You can switch back and forth between kdb or the gdb stub mode of
operation dynamically. From gdb stub mode you can blindly type
"$3#33", or from the kdb mode you can enter "kgdb" to switch to the
gdb stub.
The logic in the debug core depends on kdb to look for the typical gdb
connection sequences and return immediately with KGDB_PASS_EVENT if a
gdb serial command sequence is detected. That should allow a
reasonably seamless transition between kdb -> gdb without leaving the
kernel exception state. The two gdb serial queries that kdb is
responsible for detecting are the "?" and "qSupported" packets.
CC: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Acked-by: Martin Hicks <mort@sgi.com>
There is no technical reason that the kgdb core requires frame
pointers. It is up to the end user of KGDB to decide if they need
them or not.
[ anemo@mba.ocn.ne.jp: removed frame pointers on mips ]
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Remove HAVE_ARCH_KGDB_SHADOW_INFO because it does not
exist anywhere in the kernel mainline sources
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
This patch adds in the ability to compile the kgdb internal test
string into the kernel so as to run the tests at boot without changing
the kernel boot arguments. This patch also changes all the error
paths to invoke WARN_ON(1) which will emit the line number of the file
and dump the kernel stack when an error occurs.
You can disable the tests in a kernel that is built this way
using "kgdbts="
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch adds regression tests for testing the kgdb core and arch
specific implementation.
The kgdb test suite is designed to be built into the kernel and not as
a module because it uses a number of low level kernel and kgdb
primitives which should not be exported externally.
The kgdb test suite is designed as a KGDB I/O module which
simulates the communications that a debugger would have with kgdb.
The tests are broken up in to a line by line and referenced here as
a "get" which is kgdb requesting input and "put" which is kgdb
sending a response.
The kgdb suite can be invoked from the kernel command line
arguments system or executed dynamically at run time. The test
suite uses the variable "kgdbts" to obtain the information about
which tests to run and to configure the verbosity level. The
following are the various characters you can use with the kgdbts=
line:
When using the "kgdbts=" you only choose one of the following core
test types:
A = Run all the core tests silently
V1 = Run all the core tests with minimal output
V2 = Run all the core tests in debug mode
You can also specify optional tests:
N## = Go to sleep with interrupts of for ## seconds
to test the HW NMI watchdog
F## = Break at do_fork for ## iterations
S## = Break at sys_open for ## iterations
NOTE: that the do_fork and sys_open tests are mutually exclusive.
To invoke the kgdb test suite from boot you use a kernel start
argument as follows:
kgdbts=V1 kgdbwait
Or if you wanted to perform the NMI test for 6 seconds and do_fork
test for 100 forks, you could use:
kgdbts=V1N6F100 kgdbwait
The test suite can also be invoked at run time with:
echo kgdbts=V1N6F100 > /sys/module/kgdbts/parameters/kgdbts
Or as another example:
echo kgdbts=V2 > /sys/module/kgdbts/parameters/kgdbts
When developing a new kgdb arch specific implementation or
using these tests for the purpose of regression testing,
several invocations are required.
1) Boot with the test suite enabled by using the kernel arguments
"kgdbts=V1F100 kgdbwait"
## If kgdb arch specific implementation has NMI use
"kgdbts=V1N6F100
2) After the system boot run the basic test.
echo kgdbts=V1 > /sys/module/kgdbts/parameters/kgdbts
3) Run the concurrency tests. It is best to use n+1
while loops where n is the number of cpus you have
in your system. The example below uses only two
loops.
## This tests break points on sys_open
while [ 1 ] ; do find / > /dev/null 2>&1 ; done &
while [ 1 ] ; do find / > /dev/null 2>&1 ; done &
echo kgdbts=V1S10000 > /sys/module/kgdbts/parameters/kgdbts
fg # and hit control-c
fg # and hit control-c
## This tests break points on do_fork
while [ 1 ] ; do date > /dev/null ; done &
while [ 1 ] ; do date > /dev/null ; done &
echo kgdbts=V1F1000 > /sys/module/kgdbts/parameters/kgdbts
fg # and hit control-c
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
kgdb core code. Handles the protocol and the arch details.
[ mingo@elte.hu: heavily modified, simplified and cleaned up. ]
[ xemul@openvz.org: use find_task_by_pid_ns ]
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jan Kiszka <jan.kiszka@web.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Daniel Thompson
Vincent Chen
Douglas Anderson
Krzysztof Kozlowski
Thomas Gleixner
Mauro Carvalho Chehab
Jiri Slaby
Masanari Iida
Linus Torvalds
Robert Obermeier
Joe Millenbach
Kees Cook
Jason Wessel
Jan Engelhardt