When returning from the kernel debugger reset the rcu jiffies_stall
value to prevent the rcu stall detector from sending NMI events which
invoke a stack dump for each cpu in the system.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Move the various clock and watch dog syncs to a single function in
advance of adding another sync for the rcu stall detector.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

No real bugs I believe, just some dead code.
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: andi@firstfloor.org
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Sysrq operations do not accept tty argument anymore so no need to pass
it to us.

[Stephen Rothwell <sfr@canb.auug.org.au>: fix build breakage in drm code
 caused by sysrq using bool but not including linux/types.h]

[Sachin Sant <sachinp@in.ibm.com>: fix build breakage in s390 keyboadr
 driver]
Acked-by: NAlan Cox <alan@lxorguk.ukuu.org.uk>
Acked-by: NJason Wessel <jason.wessel@windriver.com>
Acked-by: NGreg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

Noone is using tty argument so let's get rid of it.
Acked-by: NAlan Cox <alan@lxorguk.ukuu.org.uk>
Acked-by: NJason Wessel <jason.wessel@windriver.com>
Acked-by: NGreg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

If CONFIG_KGDB_KDB is set and CONFIG_KALLSYMS is not set the kernel
will fail to build with the error:

kernel/built-in.o: In function `kallsyms_symbol_next':
kernel/debug/kdb/kdb_support.c:237: undefined reference to `kdb_walk_kallsyms'
kernel/built-in.o: In function `kallsyms_symbol_complete':
kernel/debug/kdb/kdb_support.c:193: undefined reference to `kdb_walk_kallsyms'

The kdb_walk_kallsyms needs a #ifdef proper header to match the C
implementation.  This patch also fixes the compiler warnings in
kdb_support.c when compiling without CONFIG_KALLSYMS set.  The
compiler warnings are a result of the kallsyms_lookup() macro not
initializing the two of the pass by reference variables.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>
Reported-by: NMichal Simek <monstr@monstr.eu>

The kernel console interface stores the number of lines it is
configured to use. The kdb debugger can greatly benefit by knowing how
many lines there are on the console for the pager functionality
without having the end user compile in the setting or have to
repeatedly change it at run time.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
CC: David Airlie <airlied@linux.ie>
CC: Andrew Morton <akpm@linux-foundation.org>

When an arch such as mips and microblaze does not implement either HW
or software single stepping the debug core should re-enter kdb.  The
kdb code will properly ignore the single step operation.  Attempting
to single step the kernel without software or hardware support causes
unpredictable kernel crashes.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Presently the usable registers definitions on x86 are not contiguous
for kgdb.  The x86 kgdb uses a case statement for the sparse register
accesses.  The array which defines the registers (dbg_reg_def) should
not be used directly in order to safely work with sparse register
definitions.

Specifically there was a problem when gdb accesses ORIG_AX, which is
accessed only through the case statement.

This patch encodes register memory using the size information provided
from the debugger which avoids the need to look up the size of the
register.  The dbg_set_reg() function always further validates the
inputs from the debugger.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>
Signed-off-by: NDongdong Deng <dongdong.deng@windriver.com>

The gdbserial 'p' and 'P' packets allow gdb to individually get and
set registers instead of querying for all the available registers.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

The kdb shell specification includes the ability to get and set
architecture specific registers by name.

For the time being individual register get and set will be implemented
on a per architecture basis.  If an architecture defines
DBG_MAX_REG_NUM > 0 then kdb and the gdbstub will use the capability
for individually getting and setting architecture specific registers.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

The gdb debugger understands how to parse short versions of the thread
reference string as long as the bytes are paired in sets of two
characters.  The kgdb implementation was always sending 8 leading
zeros which could be omitted, and further optimized in the case of
non-negative thread numbers.  The negative numbers are used to
reference a specific cpu in the case of kgdb.

An example of the previous i386 stop packet looks like:
    T05thread:00000000000003bb;

New stop packet response:
    T05thread:03bb;

The previous ThreadInfo response looks like:
    m00000000fffffffe,0000000000000001,0000000000000002,0000000000000003,0000000000000004,0000000000000005,0000000000000006,0000000000000007,000000000000000c,0000000000000088,000000000000008a,000000000000008b,000000000000008c,000000000000008d,000000000000008e,00000000000000d4,00000000000000d5,00000000000000dd

New ThreadInfo response:
    mfffffffe,01,02,03,04,05,06,07,0c,88,8a,8b,8c,8d,8e,d4,d5,dd

A few bytes saved means better response time when using kgdb over a
serial line.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Signed-off-by: NAndy Shevchenko <ext-andriy.shevchenko@nokia.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

The xtime cleanup missed the kgdb access to xtime. Fix it.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

The kdb code should not toggle the sysrq state in case an end user
wants to try and resume the normal kernel execution.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>
Acked-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

Immediately following an exit from the kdb shell the kgdb_connected
variable should be set to zero, unless there are breakpoints planted.
If the kgdb_connected variable is not zeroed out with kdb, it is
impossible to turn off kdb.

This patch is merely a work around for now, the real fix will check
for the breakpoints.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

In the process of merging kdb to the mainline, the kdb lsmod command
stopped printing the base load address of kernel modules.  This is
needed for using kdb in conjunction with external tools such as gdb.

Simply restore the functionality by adding a kdb_printf for the base
load address of the kernel modules.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

The gdbserial protocol handler should return an empty packet instead
of an error string when ever it responds to a command it does not
implement.

The problem cases come from a debugger client sending
qTBuffer, qTStatus, qSearch, qSupported.

The incorrect response from the gdbstub leads the debugger clients to
not function correctly.  Recent versions of gdb will not detach correctly as a result of this behavior.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>
Signed-off-by: NDongdong Deng <dongdong.deng@windriver.com>

Without this patch the "ll" linked-list traversal command won't
terminate when you hit q/Q.
Signed-off-by: NMartin Hicks <mort@sgi.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

pavel@suse.cz no longer works, replace it with working address.
Signed-off-by: NPavel Machek <pavel@ucw.cz>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

Linus changed the structure, and luckily this didn't compile any more.
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Martin Hicks <mort@sgi.com>

The kernel debugger can operate well before mm_init(), but the x86
hardware breakpoint code which uses the perf api requires that the
kernel allocators are initialized.

This means the kernel debug core needs to provide an optional arch
specific call back to allow the initialization functions to run after
the kernel has been further initialized.

The kdb shell already had a similar restriction with an early
initialization and late initialization.  The kdb_init() was moved into
the debug core's version of the late init which is called
dbg_late_init();

CC: kgdb-bugreport@lists.sourceforge.net
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

It is highly desirable to trap into kdb on panic.  The debug core will
attempt to register as the first in line for the panic notifier.

CC: Ingo Molnar <mingo@elte.hu>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

This allows kdb to debug a crash with in the kms code with a
single level recursive re-entry.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Certain calls from the kdb shell will call out to printk(), and any of
these calls should get vectored back to the kdb_printf() so that the
kdb pager and processing can be used, as well as to properly channel
I/O to the polled I/O devices.

CC: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>
Acked-by: NAndrew Morton <akpm@linux-foundation.org>

If kdb is open on a serial port that is not actually a console make
sure to call the poll routines to emit and receive characters.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>
Acked-by: NMartin Hicks <mort@sgi.com>

Some kgdb I/O modules require the ability to create a breakpoint
tasklet, such as kgdboc and external modules such as kgdboe.  The
breakpoint tasklet is used as an asynchronous entry point into the
debugger which will have a different function scope than the current
execution path where it might not be safe to have an inline
breakpoint.  This is true of some of the kgdb I/O drivers which share
code with kgdb and rest of the kernel users.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

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: NJason Wessel <jason.wessel@windriver.com>

Remove all the references to the kgdb_post_primary_code.  This
function serves no useful purpose because you can obtain the same
information from the "struct kgdb_state *ks" from with in the
debugger, if for some reason you want the data.

Also remove the unintentional duplicate assignment for ks->ex_vector.
Signed-off-by: NJason 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: NJason Wessel <jason.wessel@windriver.com>
Reviewed-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>

One of the driving forces behind integrating another front end (kdb)
to the debug core is to allow front end commands to be accessible via
gdb's monitor command.  It is true that you could write gdb macros to
get certain data, but you may want to just use gdb to access the
commands that are available in the kdb front end.

This patch implements the Rcmd gdb stub packet.  In gdb you access
this with the "monitor" command.  For instance you could type "monitor
help", "monitor lsmod" or "monitor ps A" etc...

There is no error checking or command restrictions on what you can and
cannot access at this point.  Doing something like trying to set
breakpoints with the monitor command is going to cause nothing but
problems.  Perhaps in the future only the commands that are actually
known to work with the gdb monitor command will be available.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

The design of the kdb shell requires that every device that can
provide input to kdb have a polling routine that exits immediately if
there is no character available.  This is required in order to get the
page scrolling mechanism working.

Changing the kernel debugger I/O API to require all polling character
routines to exit immediately if there is no data allows the kernel
debugger to process multiple input channels.

NO_POLL_CHAR will be the return code to the polling routine when ever
there is no character available.

CC: linux-serial@vger.kernel.org
Signed-off-by: NJason Wessel <jason.wessel@windriver.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: NJason Wessel <jason.wessel@windriver.com>
Acked-by: NMartin Hicks <mort@sgi.com>

This patch contains only the kdb core.  Because the change set was
large, it was split.  The next patch in the series includes the
instrumentation into the core kernel which are mainly helper functions
for kdb.

This work is directly derived from kdb v4.4 found at:

ftp://oss.sgi.com/projects/kdb/download/v4.4/

The kdb internals have been re-organized to make them mostly platform
independent and to connect everything to the debug core which is used by
gdbstub (which has long been known as kgdb).

The original version of kdb was 58,000 lines worth of changes to
support x86.  From that implementation only the kdb shell, and basic
commands for memory access, runcontrol, lsmod, and dmesg where carried
forward.

This is a generic implementation which aims to cover all the current
architectures using the kgdb core: ppc, arm, x86, mips, sparc, sh and
blackfin.  More archictectures can be added by implementing the
architecture specific kgdb functions.

[mort@sgi.com: Compile fix with hugepages enabled]
[mort@sgi.com: Clean breakpoint code renaming kdba_ -> kdb_]
[mort@sgi.com: fix new line after printing registers]
[mort@sgi.com: Remove the concept of global vs. local breakpoints]
[mort@sgi.com: Rework kdb_si_swapinfo to use more generic name]
[mort@sgi.com: fix the information dump macros, remove 'arch' from the names]
[sfr@canb.auug.org.au: include fixup to include linux/slab.h]

CC: linux-arch@vger.kernel.org
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>
Signed-off-by: NMartin Hicks <mort@sgi.com>

Split the former kernel/kgdb.c into debug_core.c which contains the
kernel debugger exception logic and to the gdbstub.c which contains
the logic for allowing gdb to talk to the debug core.

This also created a private include file called debug_core.h which
contains all the definitions to glue the debug_core to any other
debugger connections.

CC: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Move kgdb.c in preparation to separate the gdbstub from the debug
core and exception handling.

CC: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>