The function kgdb_breakpoint() sets up break point at
compile time by calling arch_kgdb_breakpoint();
Though this call is surrounded by wmb() barrier,
the compile can still re-order the break point,
because this scheduling barrier is not a code motion
barrier in gcc.

Making kgdb_breakpoint() as noinline solves this problem
of code reording around break point instruction and also
avoids problem of being called as inline function from
other places

More details about discussion on this can be found here
http://comments.gmane.org/gmane.linux.ports.arm.kernel/269732Signed-off-by: NVijaya Kumar K <Vijaya.Kumar@caviumnetworks.com>
Acked-by: NWill Deacon <will.deacon@arm.com>
Acked-by: NJason Wessel <jason.wessel@windriver.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

Some code added to the debug_core module had KDB dependencies
that it shouldn't have.  Move the KDB dependent REASON back to
the caller to remove the dependency in the debug core code.

Update the call from the UV NMI handler to conform to the new
interface.
Signed-off-by: NMike Travis <travis@sgi.com>
Reviewed-by: NHedi Berriche <hedi@sgi.com>
Cc: Russ Anderson <rja@sgi.com>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Link: http://lkml.kernel.org/r/20140114162551.318251993@asylum.americas.sgi.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

This patch adds a kgdb_nmicallin() interface that can be used by
external NMI handlers to call the KGDB/KDB handler.  The primary
need for this is for those types of NMI interrupts where all the
CPUs have already received the NMI signal.  Therefore no
send_IPI(NMI) is required, and in fact it will cause a 2nd
unhandled NMI to occur. This generates the "Dazed and Confuzed"
messages.

Since all the CPUs are getting the NMI at roughly the same time,
it's not guaranteed that the first CPU that hits the NMI handler
will manage to enter KGDB and set the dbg_master_lock before the
slaves start entering. The new argument "send_ready" was added
for KGDB to signal the NMI handler to release the slave CPUs for
entry into KGDB.
Signed-off-by: NMike Travis <travis@sgi.com>
Acked-by: NJason Wessel <jason.wessel@windriver.com>
Reviewed-by: NDimitri Sivanich <sivanich@sgi.com>
Reviewed-by: NHedi Berriche <hedi@sgi.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Link: http://lkml.kernel.org/r/20131002151417.928886849@asylum.americas.sgi.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

Currently help message of /proc/sysrq-trigger highlight its upper-case
characters, like below:

      SysRq : HELP : loglevel(0-9) reBoot Crash terminate-all-tasks(E)
      memory-full-oom-kill(F) kill-all-tasks(I) ...

this would confuse user trigger sysrq by upper-case character, which is
inconsistent with the real lower-case character registed key.

This inconsistent help message will also lead more confused when
26 upper-case letters put into use in future.

This patch fix kgdb sysrq key: "debug(g)"
Signed-off-by: Nzhangwei(Jovi) <jovi.zhangwei@huawei.com>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The 'ssb' command can only be handled when we have a disassembler, to check for
branches, so remove the 'ssb' command for now.
Signed-off-by: NVincent Stehlé <vincent.stehle@laposte.net>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

The kdb_defcmd can only be used to display the available command aliases
while using the kernel debug shell.  If you try to define a new macro
while the kernel debugger is active it will oops.  The debug shell
macros must use pre-allocated memory set aside at the time kdb_init()
is run, and the kdb_defcmd is restricted to only working at the time
that the kdb_init sequence is being run, which only occurs if you
actually activate the kernel debugger.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Recently some code inspection was done after fixing a problem with
kmalloc used while in the kernel debugger context (which is not
legal), and it turned up the fact that kdb ll command will oops the
kernel.

Given that there have been zero bug reports on the command combined
with the fact it will oops the kernel it is clearly not being used.
Instead of fixing it, it will be removed.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

The help command was chopping all the usage instructions such that
they were not readable.

Example:

bta             [D|R|S|T|C|Z|E|U|I| Backtrace all processes matching state flag
per_cpu         <sym> [<bytes>] [<c Display per_cpu variables

Where as it should look like:

bta             [D|R|S|T|C|Z|E|U|I|M|A]
                                    Backtrace all processes matching state flag
per_cpu         <sym> [<bytes>] [<cpu>]
                                    Display per_cpu variables

All that is needed is to check the how long the cmd_usage is and jump
to the next line when appropriate.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Maxime reported that strcpy(s->usage, s->usage+1) has no definitive
guarantee that it will work on all archs the same way when you have
overlapping memory.  The fix is simple for the kdb code because we
still have the original string memory in the function scope, so we
just have to use that as the argument instead.
Reported-by: NMaxime Villard <rustyBSD@gmx.fr>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Although invasive kdb commands are not supported via kgdb, some useful
non-invasive commands like bt* require basic kdb state to be setup before
calling into the kdb code. Factor out some of this code and call it before
and after executing kdb commands via kgdb.
Signed-off-by: NMatt Klein <mklein@twitter.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Signed-off-by: NSasha Levin <sasha.levin@oracle.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

When locally adding in some additional kdb commands, I stumbled
across an issue with the dynamic expansion of the kdb command table.
When the number of kdb commands exceeds the size of the statically
allocated kdb_base_commands[] array, additional space is allocated in
the kdb_register_repeat() routine.

The unused portion of the newly allocated array was not being initialized
to zero properly and this would result in segfaults when help '?' was
executed or when a search for a non-existing command would traverse the
command table beyond the end of valid command entries and then attempt
to use the non-zeroed area as actual command entries.
Signed-off-by: NJohn Blackwood <john.blackwood@ccur.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

There's no reason kgdb.h itself needs to include the 8250 serial port
header file.  So push it down to the _very_ limited number of individual
drivers that need the values in that file, and fix up the places where
people really wanted serial_core.h and platform_device.h.
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

You should never look at such a module, so it's excised from all paths
which traverse the modules list.

We add the state at the end, to avoid gratuitous ABI break (ksplice).
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

It is possible to miss data when using the kdb pager.  The kdb pager
does not pay attention to the maximum column constraint of the screen
or serial terminal.  This result is not incrementing the shown lines
correctly and the pager will print more lines that fit on the screen.
Obviously that is less than useful when using a VGA console where you
cannot scroll back.

The pager will now look at the kdb_buffer string to see how many
characters are printed.  It might not be perfect considering you can
output ASCII that might move the cursor position, but it is a
substantially better approximation for viewing dmesg and trace logs.

This also means that the vt screen needs to set the kdb COLUMNS
variable.

Cc: <stable@vger.kernel.org>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

If you press 'q' the pager should exit instead of printing everything
from dmesg which can really bog down a 9600 baud serial link.

The same is true for the bta command.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Allow gdb to auto load kernel modules when it is attached,
which makes it trivially easy to debug module init functions
or pre-set breakpoints in a kernel module that has not loaded yet.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

This command disables NMI-entry. If NMI source has been previously shared
with a serial console ("debug port"), this effectively releases the port
from KDB exclusive use, and makes the console available for normal use.

Of course, NMI can be reenabled, enable_nmi modparam is used for that:

	echo 1 > /sys/module/kdb/parameters/enable_nmi
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: NJason Wessel <jason.wessel@windriver.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The new arch callback should manage NMIs that usually cause KGDB to
enter. That is, not all NMIs should be enabled/disabled, but only
those that issue kgdb_handle_exception().

We must mask it as serial-line interrupt can be used as an NMI, so
if the original KGDB-entry cause was say a breakpoint, then every
input to KDB console will cause KGDB to reenter, which we don't want.
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: NJason Wessel <jason.wessel@windriver.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Currently kernel never set KGDB_REASON_NMI. We do now, when we enter
KGDB/KDB from an NMI.

This is not to be confused with kgdb_nmicallback(), NMI callback is
an entry for the slave CPUs during CPUs roundup, but REASON_NMI is the
entry for the master CPU.
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Having the CPU in the more prompt is completely redundent vs the
standard kdb prompt, and it also wastes 32 bytes on the stack.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

This code cleanup was missed in the original kdb merge, and this code
is simply not used at all.  The code that was previously used to set
the KDB_FLAG_ONLY_DO_DUMP was removed prior to the initial kdb merge.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

The locked variants are prone to deadlocks (suppose we got to the
debugger w/ the logbuf lock held), so let's switch to nolock variants.
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The function is no longer needed, so remove it.
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The kgdb dmesg command is broken after the printk rework.  The old logic
in kdb code makes no sense in terms of current printk/logging storage
format, and KDB simply hangs forever.

This patch revives the command by switching to kmsg_dumper iterator.

The code is now much more simpler and shorter.
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There is extra state information that needs to be exposed in the
kgdb_bpt structure for tracking how a breakpoint was installed.  The
debug_core only uses the the probe_kernel_write() to install
breakpoints, but this is not enough for all the archs.  Some arch such
as x86 need to use text_poke() in order to install a breakpoint into a
read only page.

Passing the kgdb_bpt structure to kgdb_arch_set_breakpoint() and
kgdb_arch_remove_breakpoint() allows other archs to set the type
variable which indicates how the breakpoint was installed.

Cc: stable@vger.kernel.org # >= 2.6.36
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

The Smatch tool warned that the change from commit b8adde8d
(kdb: Avoid using dbg_io_ops until it is initialized) should
add another null check later in the kdb_printf().

It is worth noting that the second use of dbg_io_ops->is_console
is protected by the KDB_PAGER state variable which would only
get set when kdb is fully active and initialized.  If we
ever encounter changes or defects in the KDB_PAGER state
we do not want to crash the kernel in a kdb_printf/printk.

CC: Tim Bird <tim.bird@am.sony.com>
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Remove all #inclusions of asm/system.h preparatory to splitting and killing
it.  Performed with the following command:

perl -p -i -e 's!^#\s*include\s*<asm/system[.]h>.*\n!!' `grep -Irl '^#\s*include\s*<asm/system[.]h>' *`
Signed-off-by: NDavid Howells <dhowells@redhat.com>

On x86, if CONFIG_DEBUG_RODATA is set, one cannot set breakpoints
via KDB.  Apparently this is a well-known problem, as at least one distribution
now ships with both KDB enabled and CONFIG_DEBUG_RODATA=y for security reasons.

This patch adds an printk message to the breakpoint failure case,
in order to provide suggestions about how to use the debugger.
Reported-by: NTim Bird <tim.bird@am.sony.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>
Acked-by: NTim Bird <tim.bird@am.sony.com>

This fixes a bug with setting a breakpoint during kdb initialization
(from kdb_cmds).  Any call to kdb_printf() before the initialization
of the kgdboc serial console driver (which happens much later during
bootup than kdb_init), results in kernel panic due to the use of
dbg_io_ops before it is initialized.
Signed-off-by: NTim Bird <tim.bird@am.sony.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Sometimes it is desirable to stop the kernel debugger before allowing
a system to reboot either with kdb or kgdb.  This patch adds the
ability to turn the reboot notifier on and off or enter the debugger
and stop kernel execution before rebooting.

It is possible to change the setting after booting the kernel with the
following:

echo 1 > /sys/module/debug_core/parameters/kgdbreboot

It is also possible to change this setting using kdb / kgdb to
manipulate the variable directly.

Using KDB:
   mm kgdbreboot 1

Using gdb:
   set kgdbreboot=1
Reported-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

This fixes the following problems:
1) Typematic-repeat of 'enter' gives warning message
   and leaks make/break if KDB exits. Repeats
   look something like 0x1c 0x1c .... 0x9c
2) Use of 'keypad enter' gives warning message and
   leaks the ENTER break/make code out if KDB exits.
   KP ENTER repeats look someting like 0xe0 0x1c
   0xe0 0x1c ... 0xe0 0x9c.
3) Lag on the order of seconds between "break" and "make" when
   expecting the enter "break" code. Seen under virtualized
   environments such as VMware ESX.

The existing special enter handler tries to glob the enter break code,
but this fails if the other (KP) enter was used, or if there was a key
repeat. It also fails if you mashed some keys along with enter, and
you ended up with a non-enter make or non-enter break code coming
after the enter make code. So first, we modify the handler to handle
these cases. But performing these actions on every enter is annoying
since now you can't hold ENTER down to scroll <more>d messages in
KDB. Since this special behaviour is only necessary to handle the
exiting KDB ('g' + ENTER) without leaking scancodes to the OS.  This
cleanup needs to get executed anytime the kdb_main loop exits.

Tested on QEMU. Set a bp on atkbd.c to verify no scan code was leaked.

Cc: Andrei Warkentin <andreiw@vmware.com>
[jason.wessel@windriver.com: move cleanup calls to kdb_main.c]
Signed-off-by: NAndrei Warkentin <andrey.warkentin@gmail.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

The gdbstub and kdb should get detached if the system is rebooting.
Calling gdbstub_exit() will set the proper debug core state and send a
message to any debugger that is connected to correctly detach.

An attached debugger will receive the exit code from
include/linux/reboot.h based on SYS_HALT, SYS_REBOOT, etc...
Reported-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Not all kgdb I/O drivers implement a flush operation. Adjust
gdbstub_exit accordingly.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Signed-off-by: NCong Wang <amwang@redhat.com>

module_ref contains two "unsigned int" fields.

Thats now too small, since some machines can open more than 2^32 files.

Check commit 518de9b3 (fs: allow for more than 2^31 files) for
reference.

We can add an aligned(2 * sizeof(unsigned long)) attribute to force
alloc_percpu() allocating module_ref areas in single cache lines.
Signed-off-by: NEric Dumazet <eric.dumazet@gmail.com>
CC: Rusty Russell <rusty@rustcorp.com.au>
CC: Tejun Heo <tj@kernel.org>
CC: Robin Holt <holt@sgi.com>
CC: David Miller <davem@davemloft.net>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Change from direct comparison of ->pid with zero to is_idle_task().
Signed-off-by: NPaul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Jason Wessel <jason.wessel@windriver.com>
Reviewed-by: NJosh Triplett <josh@joshtriplett.org>

There is no functional change.
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: NJesper Nilsson <jesper.nilsson@axis.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Koichi Yasutake <yasutake.koichi@jp.panasonic.com>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

These files were getting <linux/module.h> via an implicit non-obvious
path, but we want to crush those out of existence since they cost
time during compiles of processing thousands of lines of headers
for no reason.  Give them the lightweight header that just contains
the EXPORT_SYMBOL infrastructure.
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>

The first packet that gdb sends when the kernel is in kdb mode seems
to change with every release of gdb.  Instead of continuing to add
many different gdb packets, change kdb to automatically look for any
thing that looks like a gdb packet.

Example 1 cold start test:
echo g > /proc/sysrq-trigger
$D#44+

Example 2 cold start test:
echo g > /proc/sysrq-trigger
$3#33

The second one should re-enter kdb's shell right away and is purely a
test.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>