Currently kdb allows the output of comamnds to be filtered using the
| grep feature. This is useful but does not permit the output emitted
shortly after a string match to be examined without wading through the
entire unfiltered output of the command. Such a feature is particularly
useful to navigate function traces because these traces often have a
useful trigger string *before* the point of interest.

This patch reuses the existing filtering logic to introduce a simple
forward search to kdb that can be triggered from the more prompt.
Signed-off-by: NDaniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Currently when the "| grep" feature is used to filter the output of a
command then the prompt is not displayed for the subsequent command.
Likewise any characters typed by the user are also not echoed to the
display. This rather disconcerting problem eventually corrects itself
when the user presses Enter and the kdb_grepping_flag is cleared as
kdb_parse() tries to make sense of whatever they typed.

This patch resolves the problem by moving the clearing of this flag
from the middle of command processing to the beginning.
Signed-off-by: NDaniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Issuing a stack dump feels ergonomically wrong when entering due to NMI.

Entering due to NMI is normally a reaction to a user request, either the
NMI button on a server or a "magic knock" on a UART. Therefore the
backtrace behaviour on entry due to NMI should be like SysRq-g (no stack
dump) rather than like oops.

Note also that the stack dump does not offer any information that
cannot be trivial retrieved using the 'bt' command.
Signed-off-by: NDaniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

There was a follow on replacement patch against the prior
"kgdb: Timeout if secondary CPUs ignore the roundup".

See: https://lkml.org/lkml/2015/1/7/442

This patch is the delta vs the patch that was committed upstream:
  * Fix an off-by-one error in kdb_cpu().
  * Replace NR_CPUS with CONFIG_NR_CPUS to tell checkpatch that we
    really want a static limit.
  * Removed the "KGDB: " prefix from the pr_crit() in debug_core.c
    (kgdb-next contains a patch which introduced pr_fmt() to this file
    to the tag will now be applied automatically).

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

The output of KDB 'summary' command should report MemTotal, MemFree
and Buffers output in kB. Current codes report in unit of pages.

A define of K(x) as
is defined in the code, but not used.

This patch would apply the define to convert the values to kB.
Please include me on Cc on replies. I do not subscribe to linux-kernel.
Signed-off-by: NJay Lan <jlan@sgi.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

James Bottomley points out that it will be -1 during unload.  It's
only used for diagnostics, so let's not hide that as it could be a
clue as to what's gone wrong.

Cc: Jason Wessel <jason.wessel@windriver.com>
Acked-and-documention-added-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>
Reviewed-by: NMasami Hiramatsu <maasami.hiramatsu.pt@hitachi.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Currently if an active CPU fails to respond to a roundup request the CPU
that requested the roundup will become stuck.  This needlessly reduces the
robustness of the debugger.

This patch introduces a timeout allowing the system state to be examined
even when the system contains unresponsive processors.  It also modifies
kdb's cpu command to make it censor attempts to switch to unresponsive
processors and to report their state as (D)ead.
Signed-off-by: NDaniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

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: NDaniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Currently all kdb commands are enabled whenever kdb is deployed. This
makes it difficult to deploy kdb to help debug certain types of
systems.

Android phones provide one example; the FIQ debugger found on some
Android devices has a deliberately weak set of commands to allow the
debugger to enabled very late in the production cycle.

Certain kiosk environments offer another interesting case where an
engineer might wish to probe the system state using passive inspection
commands without providing sufficient power for a passer by to root it.

Without any restrictions, obtaining the root rights via KDB is a matter of
a few commands, and works everywhere. For example, log in as a normal
user:

cbou:~$ id
uid=1001(cbou) gid=1001(cbou) groups=1001(cbou)

Now enter KDB (for example via sysrq):

Entering kdb (current=0xffff8800065bc740, pid 920) due to Keyboard Entry
kdb> ps
23 sleeping system daemon (state M) processes suppressed,
use 'ps A' to see all.
Task Addr               Pid   Parent [*] cpu State Thread             Command
0xffff8800065bc740      920      919  1    0   R  0xffff8800065bca20 *bash

0xffff880007078000        1        0  0    0   S  0xffff8800070782e0  init
[...snip...]
0xffff8800065be3c0      918        1  0    0   S  0xffff8800065be6a0  getty
0xffff8800065b9c80      919        1  0    0   S  0xffff8800065b9f60  login
0xffff8800065bc740      920      919  1    0   R  0xffff8800065bca20 *bash

All we need is the offset of cred pointers. We can look up the offset in
the distro's kernel source, but it is unnecessary. We can just start
dumping init's task_struct, until we see the process name:

kdb> md 0xffff880007078000
0xffff880007078000 0000000000000001 ffff88000703c000   ................
0xffff880007078010 0040210000000002 0000000000000000   .....!@.........
[...snip...]
0xffff8800070782b0 ffff8800073e0580 ffff8800073e0580   ..>.......>.....
0xffff8800070782c0 0000000074696e69 0000000000000000   init............

^ Here, 'init'. Creds are just above it, so the offset is 0x02b0.

Now we set up init's creds for our non-privileged shell:

kdb> mm 0xffff8800065bc740+0x02b0 0xffff8800073e0580
0xffff8800065bc9f0 = 0xffff8800073e0580
kdb> mm 0xffff8800065bc740+0x02b8 0xffff8800073e0580
0xffff8800065bc9f8 = 0xffff8800073e0580

And thus gaining the root:

kdb> go
cbou:~$ id
uid=0(root) gid=0(root) groups=0(root)
cbou:~$ bash
root:~#

p.s. No distro enables kdb by default (although, with a nice KDB-over-KMS
feature availability, I would expect at least some would enable it), so
it's not actually some kind of a major issue.
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Signed-off-by: NDaniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

This patch introduces several new flags to collect kdb commands into
groups (later allowing them to be optionally disabled).

This follows similar prior art to enable/disable magic sysrq
commands.

The commands have been categorized as follows:

Always on:  go (w/o args), env, set, help, ?, cpu (w/o args), sr,
            dmesg, disable_nmi, defcmd, summary, grephelp
Mem read:   md, mdr, mdp, mds, ef, bt (with args), per_cpu
Mem write:  mm
Reg read:   rd
Reg write:  go (with args), rm
Inspect:    bt (w/o args), btp, bta, btc, btt, ps, pid, lsmod
Flow ctrl:  bp, bl, bph, bc, be, bd, ss
Signal:     kill
Reboot:     reboot
All:        cpu, kgdb, (and all of the above), nmi_console
Signed-off-by: NDaniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Since we now treat KDB_REPEAT_* as flags, there is no need to
pass KDB_REPEAT_NONE. It's just the default behaviour when no
flags are specified.
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Signed-off-by: NDaniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

The actual values of KDB_REPEAT_* enum values and overall logic stayed
the same, but we now treat the values as flags.

This makes it possible to add other flags and combine them, plus makes
the code a lot simpler and shorter. But functionality-wise, there should
be no changes.
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Signed-off-by: NDaniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

We're about to add more options for commands behaviour, so let's give
a more generic name to the low-level kdb command registration function.

There are just various renames, no functional changes.
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Signed-off-by: NDaniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

We're about to add more options for command behaviour, so let's expand
the meaning of kdb_repeat_t.

So far we just do various renames, there should be no functional changes.
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Signed-off-by: NDaniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

The struct member is never used in the code, so we can remove it.

We will introduce real flags soon by renaming cmd_repeat to cmd_flags.
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Signed-off-by: NDaniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

do_posix_clock_monotonic_gettime() is a leftover from the initial
posix timer implementation which maps to ktime_get_ts().
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Link: http://lkml.kernel.org/r/20140611234607.261629142@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

... instead of naked numbers.

Stuff in sysrq.c used to set it to 8 which is supposed to mean above
default level so set it to DEBUG instead as we're terminating/killing all
tasks and we want to be verbose there.

Also, correct the check in x86_64_start_kernel which should be >= as
we're clearly issuing the string there for all debug levels, not only
the magical 10.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Acked-by: NKees Cook <keescook@chromium.org>
Acked-by: NRandy Dunlap <rdunlap@infradead.org>
Cc: Joe Perches <joe@perches.com>
Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.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>

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>

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>

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>

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>

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>

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 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>

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>

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>

The DOING_KGDB2 was originally a state variable for one of the two
ways to automatically transition from kdb to kgdb.  Purge all these
variables and just use one single state for the transition.
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

The BTARGS and BTSYMARG variables do not have any function in the
mainline version of kdb.
Reported-by: NTim Bird <tim.bird@am.sony.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Fixes generated by 'codespell' and manually reviewed.
Signed-off-by: NLucas De Marchi <lucas.demarchi@profusion.mobi>

Signed-off-by: NNamhyung Kim <namhyung@gmail.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

It's better to use macro KDB_BASE_CMD_MAX instead of 50
Signed-off-by: NJovi Zhang <bookjovi@gmail.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

When the number of dyanmic kdb commands exceeds KDB_BASE_CMD_MAX, the
kernel will fault.
Signed-off-by: NJovi Zhang <bookjovi@gmail.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>

Call kfree in the error path as well as the success path in kdb_ll().
Signed-off-by: NJovi Zhang <bookjovi@gmail.com>
Signed-off-by: NJason Wessel <jason.wessel@windriver.com>