Commit Graph

53 Commits

Author SHA1 Message Date
Jovi Zhang
5450d90405 kdb: fix crash when KDB_BASE_CMD_MAX is exceeded
When the number of dyanmic kdb commands exceeds KDB_BASE_CMD_MAX, the
kernel will fault.

Signed-off-by: Jovi Zhang <bookjovi@gmail.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
2010-11-17 13:54:57 -06:00
Jovi Zhang
85e76ab50a kdb: fix memory leak in kdb_main.c
Call kfree in the error path as well as the success path in kdb_ll().

Signed-off-by: Jovi Zhang <bookjovi@gmail.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
2010-11-17 13:54:57 -06:00
Dongdong Deng
d7ba979d45 debug_core,x86,blackfin: Clean up hw debug disable API
The kgdb_disable_hw_debug() was an architecture specific function for
disabling all hardware breakpoints on a per cpu basis when entering
the debug core.

This patch will remove the weak function kdbg_disable_hw_debug() and
change it into a call back which lives with the rest of hw breakpoint
call backs in struct kgdb_arch.

Signed-off-by: Dongdong Deng <dongdong.deng@windriver.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
2010-10-29 13:14:41 -05:00
Jason Wessel
578bd4dfcd kdb: Fix early debugging crash regression
The kdb_current legally be equal to NULL in the early boot of the x86
arch.  The problem pcan be observed by booting with the kernel arguments:

    earlyprintk=vga ekgdboc=kbd kgdbwait

The kdb shell will oops on entry and recursively fault because it
cannot get past the final stage of shell initialization.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
2010-10-29 13:14:41 -05:00
Jason Wessel
931ea24819 kdb: fix per_cpu command to remove supress mask
Rusty pointed out that the per_cpu command uses up lots of space on
the stack and the cpu supress mask is probably not needed.

This patch removes the need for the supress mask as well as fixing up
the following problems with the kdb per_cpu command:
  * The per_cpu command should allow an address as an argument
  * When you have more data than can be displayed on one screen allow
    the user to break out of the print loop.

Reported-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
2010-10-29 13:14:40 -05:00
Jason Wessel
495363d380 kdb,debug_core: adjust master cpu switch logic against new debug_core locking
The kdb shell needs to enforce switching back to the original CPU that
took the exception before restoring normal kernel execution.  Resuming
from a different CPU than what took the original exception will cause
problems with spin locks that are freed from the a different processor
than had taken the lock.

The special logic in dbg_cpu_switch() can go away entirely with
because the state of what cpus want to be masters or slaves will
remain unchanged between entry and exit of the debug_core exception
context.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
2010-10-22 15:34:13 -05:00
Jason Wessel
dfee3a7b92 debug_core: refactor locking for master/slave cpus
For quite some time there have been problems with memory barriers and
various races with NMI on multi processor systems using the kernel
debugger.  The algorithm for entering the kernel debug core and
resuming kernel execution was racy and had several known edge case
problems with attempting to debug something on a heavily loaded system
using breakpoints that are hit repeatedly and quickly.

The prior "locking" design entry worked as follows:

  * The atomic counter kgdb_active was used with atomic exchange in
    order to elect a master cpu out of all the cpus that may have
    taken a debug exception.
  * The master cpu increments all elements of passive_cpu_wait[].
  * The master cpu issues the round up cpus message.
  * Each "slave cpu" that enters the debug core increments its own
    element in cpu_in_kgdb[].
  * Each "slave cpu" spins on passive_cpu_wait[] until it becomes 0.
  * The master cpu debugs the system.

The new scheme removes the two arrays of atomic counters and replaces
them with 2 single counters.  One counter is used to count the number
of cpus waiting to become a master cpu (because one or more hit an
exception). The second counter is use to indicate how many cpus have
entered as slave cpus.

The new entry logic works as follows:

  * One or more cpus enters via kgdb_handle_exception() and increments
    the masters_in_kgdb. Each cpu attempts to get the spin lock called
    dbg_master_lock.
  * The master cpu sets kgdb_active to the current cpu.
  * The master cpu takes the spinlock dbg_slave_lock.
  * The master cpu asks to round up all the other cpus.
  * Each slave cpu that is not already in kgdb_handle_exception()
    will enter and increment slaves_in_kgdb.  Each slave will now spin
    try_locking on dbg_slave_lock.
  * The master cpu waits for the sum of masters_in_kgdb and slaves_in_kgdb
    to be equal to the sum of the online cpus.
  * The master cpu debugs the system.

In the new design the kgdb_active can only be changed while holding
dbg_master_lock.  Stress testing has not turned up any further
entry/exit races that existed in the prior locking design.  The prior
locking design suffered from atomic variables not being truly atomic
(in the capacity as used by kgdb) along with memory barrier races.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Acked-by: Dongdong Deng <dongdong.deng@windriver.com>
2010-10-22 15:34:13 -05:00
Dongdong Deng
c1bb9a9c19 debug_core: disable hw_breakpoints on all cores in kgdb_cpu_enter()
The slave cpus do not have the hw breakpoints disabled upon entry to
the debug_core and as a result could cause unrecoverable recursive
faults on badly placed breakpoints, or get out of sync with the arch
specific hw breakpoint operations.

This patch addresses the problem by invoking kgdb_disable_hw_debug()
earlier in kgdb_enter_cpu for each cpu that enters the debug core.

The hw breakpoint dis/enable flow should be:

master_debug_cpu   slave_debug_cpu
         \              /
          kgdb_cpu_enter
                |
        kgdb_disable_hw_debug --> uninstall pre-enabled hw_breakpoint
                |
 do add/rm dis/enable operates to hw_breakpoints on master_debug_cpu..
                |
        correct_hw_break --> correct/install the enabled hw_breakpoint
                |
           leave_kgdb

Signed-off-by: Dongdong Deng <dongdong.deng@windriver.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
2010-10-22 15:34:12 -05:00
Jason Wessel
91b152aa85 kdb,kgdb: fix sparse fixups
Fix the following sparse warnings:

kdb_main.c:328:5: warning: symbol 'kdbgetu64arg' was not declared. Should it be static?
kgdboc.c:246:12: warning: symbol 'kgdboc_early_init' was not declared. Should it be static?
kgdb.c:652:26: warning: incorrect type in argument 1 (different address spaces)
kgdb.c:652:26:    expected void const *ptr
kgdb.c:652:26:    got struct perf_event *[noderef] <asn:3>*pev

The one in kgdb.c required the (void * __force) because of the return
code from register_wide_hw_breakpoint looking like:

        return (void __percpu __force *)ERR_PTR(err);

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
2010-10-22 15:34:12 -05:00
Jason Wessel
75d14edee5 kdb: Fix oops in kdb_unregister
Nothing should try to use kdb_commands directly as sometimes it is
null.  Instead, use the for_each_kdbcmd() iterator.

This particular problem dates back to the initial kdb merge (2.6.35),
but at that point nothing was dynamically unregistering commands from
the kdb shell.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
2010-10-22 15:34:12 -05:00
Jason Wessel
f7030bbc44 kdb: Allow kernel loadable modules to add kdb shell functions
In order to allow kernel modules to dynamically add a command to the
kdb shell the kdb_register, kdb_register_repeat, kdb_unregister, and
kdb_printf need to be exported as GPL symbols.

Any kernel module that adds a dynamic kdb shell function should only
need to include linux/kdb.h.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
2010-10-22 15:34:11 -05:00
Jason Wessel
fb70b5888b debug_core: stop rcu warnings on kernel resume
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: Jason Wessel <jason.wessel@windriver.com>
2010-10-22 15:34:10 -05:00
Jason Wessel
16cdc628c3 debug_core: move all watch dog syncs to a single function
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: Jason Wessel <jason.wessel@windriver.com>
2010-10-22 15:34:10 -05:00
Linus Torvalds
79637a41e4 Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  gcc-4.6: kernel/*: Fix unused but set warnings
  mutex: Fix annotations to include it in kernel-locking docbook
  pid: make setpgid() system call use RCU read-side critical section
  MAINTAINERS: Add RCU's public git tree
2010-09-08 11:13:42 -07:00
Andi Kleen
b3bd3de66f gcc-4.6: kernel/*: Fix unused but set warnings
No real bugs I believe, just some dead code.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: andi@firstfloor.org
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-09-05 14:36:58 +02:00
Linus Torvalds
2637d139fb Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
  Input: pxa27x_keypad - remove input_free_device() in pxa27x_keypad_remove()
  Input: mousedev - fix regression of inverting axes
  Input: uinput - add devname alias to allow module on-demand load
  Input: hil_kbd - fix compile error
  USB: drop tty argument from usb_serial_handle_sysrq_char()
  Input: sysrq - drop tty argument form handle_sysrq()
  Input: sysrq - drop tty argument from sysrq ops handlers
2010-08-28 13:55:31 -07:00
Dmitry Torokhov
f335397d17 Input: sysrq - drop tty argument form handle_sysrq()
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: Alan Cox <alan@lxorguk.ukuu.org.uk>
Acked-by: Jason Wessel <jason.wessel@windriver.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
2010-08-21 00:34:45 -07:00
Dmitry Torokhov
1495cc9df4 Input: sysrq - drop tty argument from sysrq ops handlers
Noone is using tty argument so let's get rid of it.

Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Acked-by: Jason Wessel <jason.wessel@windriver.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
2010-08-19 22:07:06 -07:00
Jason Wessel
b590cddfa6 kdb: fix compile error without CONFIG_KALLSYMS
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: Jason Wessel <jason.wessel@windriver.com>
Reported-by: Michal Simek <monstr@monstr.eu>
2010-08-16 15:58:29 -05:00
Linus Torvalds
b62ad9ab18 Merge branch 'timers-timekeeping-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'timers-timekeeping-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  um: Fix read_persistent_clock fallout
  kgdb: Do not access xtime directly
  powerpc: Clean up obsolete code relating to decrementer and timebase
  powerpc: Rework VDSO gettimeofday to prevent time going backwards
  clocksource: Add __clocksource_updatefreq_hz/khz methods
  x86: Convert common clocksources to use clocksource_register_hz/khz
  timekeeping: Make xtime and wall_to_monotonic static
  hrtimer: Cleanup direct access to wall_to_monotonic
  um: Convert to use read_persistent_clock
  timkeeping: Fix update_vsyscall to provide wall_to_monotonic offset
  powerpc: Cleanup xtime usage
  powerpc: Simplify update_vsyscall
  time: Kill off CONFIG_GENERIC_TIME
  time: Implement timespec_add
  x86: Fix vtime/file timestamp inconsistencies

Trivial conflicts in Documentation/feature-removal-schedule.txt

Much less trivial conflicts in arch/powerpc/kernel/time.c resolved as
per Thomas' earlier merge commit 47916be4e2 ("Merge branch
'powerpc.cherry-picks' into timers/clocksource")
2010-08-06 13:18:29 -07:00
Linus Torvalds
9779714c8a Merge branch 'kms-merge' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb
* 'kms-merge' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb:
  kgdb,docs: Update the kgdb docs to include kms
  drm_fb_helper: Preserve capability to use atomic kms
  i915: when kgdb is active display compression should be off
  drm/i915: use new fb debug hooks
  drm: add KGDB/KDB support
  fb: add hooks to handle KDB enter/exit
  kgdboc: Add call backs to allow kernel mode switching
  vt,console,kdb: automatically set kdb LINES variable
  vt,console,kdb: implement atomic console enter/leave functions
2010-08-05 16:00:44 -07:00
Linus Torvalds
89a6c8cb9e Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/linux-2.6-kgdb:
  debug_core,kdb: fix crash when arch does not have single step
  kgdb,x86: use macro HBP_NUM to replace magic number 4
  kgdb,mips: remove unused kgdb_cpu_doing_single_step operations
  mm,kdb,kgdb: Add a debug reference for the kdb kmap usage
  KGDB: Remove set but unused newPC
  ftrace,kdb: Allow dumping a specific cpu's buffer with ftdump
  ftrace,kdb: Extend kdb to be able to dump the ftrace buffer
  kgdb,powerpc: Replace hardcoded offset by BREAK_INSTR_SIZE
  arm,kgdb: Add ability to trap into debugger on notify_die
  gdbstub: do not directly use dbg_reg_def[] in gdb_cmd_reg_set()
  gdbstub: Implement gdbserial 'p' and 'P' packets
  kgdb,arm: Individual register get/set for arm
  kgdb,mips: Individual register get/set for mips
  kgdb,x86: Individual register get/set for x86
  kgdb,kdb: individual register set and and get API
  gdbstub: Optimize kgdb's "thread:" response for the gdb serial protocol
  kgdb: remove custom hex_to_bin()implementation
2010-08-05 15:59:48 -07:00
Jason Wessel
81d4450732 vt,console,kdb: automatically set kdb LINES variable
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: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
CC: David Airlie <airlied@linux.ie>
CC: Andrew Morton <akpm@linux-foundation.org>
2010-08-05 09:22:30 -05:00
Jason Wessel
3fa43aba08 debug_core,kdb: fix crash when arch does not have single step
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: Jason Wessel <jason.wessel@windriver.com>
2010-08-05 09:22:25 -05:00
Jason Wessel
6d855b1d83 gdbstub: do not directly use dbg_reg_def[] in gdb_cmd_reg_set()
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: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Dongdong Deng <dongdong.deng@windriver.com>
2010-08-05 09:22:22 -05:00
Jason Wessel
55751145dc gdbstub: Implement gdbserial 'p' and 'P' packets
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: Jason Wessel <jason.wessel@windriver.com>
2010-08-05 09:22:21 -05:00
Jason Wessel
534af10823 kgdb,kdb: individual register set and and get API
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: Jason Wessel <jason.wessel@windriver.com>
2010-08-05 09:22:20 -05:00
Jason Wessel
84a0bd5b28 gdbstub: Optimize kgdb's "thread:" response for the gdb serial protocol
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: Jason Wessel <jason.wessel@windriver.com>
2010-08-05 09:22:19 -05:00
Andy Shevchenko
a9fa20a7af kgdb: remove custom hex_to_bin()implementation
Signed-off-by: Andy Shevchenko <ext-andriy.shevchenko@nokia.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
2010-08-05 09:22:19 -05:00
Jiri Kosina
d790d4d583 Merge branch 'master' into for-next 2010-08-04 15:14:38 +02:00
Thomas Gleixner
157b1a2385 kgdb: Do not access xtime directly
The xtime cleanup missed the kgdb access to xtime. Fix it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2010-07-29 10:29:39 +02:00
Jason Wessel
edd63cb6b9 sysrq,kdb: Use __handle_sysrq() for kdb's sysrq function
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: Jason Wessel <jason.wessel@windriver.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
2010-07-21 19:27:07 -05:00
Jason Wessel
b0679c63db debug_core,kdb: fix kgdb_connected bit set in the wrong place
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: Jason Wessel <jason.wessel@windriver.com>
2010-07-21 19:27:07 -05:00
Jason Wessel
9e8b624fca Fix merge regression from external kdb to upstream kdb
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: Jason Wessel <jason.wessel@windriver.com>
2010-07-21 19:27:06 -05:00
Jason Wessel
fb82c0ff27 repair gdbstub to match the gdbserial protocol specification
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: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Dongdong Deng <dongdong.deng@windriver.com>
2010-07-21 19:27:05 -05:00
Martin Hicks
1396a21ba0 kdb: break out of kdb_ll() when command is terminated
Without this patch the "ll" linked-list traversal command won't
terminate when you hit q/Q.

Signed-off-by: Martin Hicks <mort@sgi.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
2010-07-21 19:27:05 -05:00
Pavel Machek
a2531293db update email address
pavel@suse.cz no longer works, replace it with working address.

Signed-off-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2010-07-19 10:56:54 +02:00
Rusty Russell
c8e21ced08 module: fix kdb's illicit use of struct module_use.
Linus changed the structure, and luckily this didn't compile any more.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Martin Hicks <mort@sgi.com>
2010-06-05 11:17:36 +09:30
Jason Wessel
0b4b3827db x86, kgdb, init: Add early and late debug states
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: Jason Wessel <jason.wessel@windriver.com>
2010-05-20 21:04:29 -05:00
Jason Wessel
4402c153cb kdb,debug_core: Allow the debug core to receive a panic notification
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: Jason Wessel <jason.wessel@windriver.com>
2010-05-20 21:04:28 -05:00
Jason Wessel
6d90634076 debug_core,kdb: Allow the debug core to process a recursive debug entry
This allows kdb to debug a crash with in the kms code with a
single level recursive re-entry.

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
2010-05-20 21:04:27 -05:00
Jason Wessel
d37d39ae3b printk,kdb: capture printk() when in kdb shell
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: Jason Wessel <jason.wessel@windriver.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
2010-05-20 21:04:27 -05:00
Jason Wessel
efe2f29e32 kgdboc,kdb: Allow kdb to work on a non open console port
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: Jason Wessel <jason.wessel@windriver.com>
Acked-by: Martin Hicks <mort@sgi.com>
2010-05-20 21:04:26 -05:00
Jason Wessel
1cee5e35f1 kgdb: Add the ability to schedule a breakpoint via a tasklet
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: Jason Wessel <jason.wessel@windriver.com>
2010-05-20 21:04:26 -05:00
Jason Wessel
f503b5ae53 x86,kgdb: Add low level debug hook
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>
2010-05-20 21:04:25 -05:00
Jason Wessel
98ec1878ca kgdb: remove post_primary_code references
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: Jason Wessel <jason.wessel@windriver.com>
2010-05-20 21:04:25 -05:00
Jason Wessel
ada64e4c98 kgdboc,keyboard: Keyboard driver for kdb with kgdb
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>
2010-05-20 21:04:24 -05:00
Jason Wessel
a0de055cf6 kgdb: gdb "monitor" -> kdb passthrough
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: Jason Wessel <jason.wessel@windriver.com>
2010-05-20 21:04:24 -05:00
Jason Wessel
f5316b4aea kgdb,8250,pl011: Return immediately from console poll
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: Jason Wessel <jason.wessel@windriver.com>
2010-05-20 21:04:22 -05:00
Jason Wessel
dcc7871128 kgdb: core changes to support kdb
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>
2010-05-20 21:04:21 -05:00