kdb: Get rid of custom debug heap allocator

Currently the only user for debug heap is kdbnearsym() which can be
modified to rather use statically allocated buffer for symbol name as
per it's current

kdb: Get rid of custom debug heap allocator

Currently the only user for debug heap is kdbnearsym() which can be
modified to rather use statically allocated buffer for symbol name as
per it's current usage. So do that and hence remove custom debug heap
allocator.

Note that this change puts a restriction on kdbnearsym() callers to
carefully use shared namebuf such that a caller should consume the symbol
returned immediately prior to another call to fetch a different symbol.

Also, this change uses standard KSYM_NAME_LEN macro for namebuf
allocation instead of local variable: knt1_size which should avoid any
conflicts caused by changes to KSYM_NAME_LEN macro value.

This change has been tested using kgdbtest on arm64 which doesn't show
any regressions.

Suggested-by: Daniel Thompson <[email protected]>
Signed-off-by: Sumit Garg <[email protected]>
Reviewed-by: Douglas Anderson <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Daniel Thompson <[email protected]>

show more ...

kernel: debug: Centralize dbg_[de]activate_sw_breakpoints

During debug trap execution we expect dbg_deactivate_sw_breakpoints()
to be paired with an dbg_activate_sw_breakpoint(). Currently although

kernel: debug: Centralize dbg_[de]activate_sw_breakpoints

During debug trap execution we expect dbg_deactivate_sw_breakpoints()
to be paired with an dbg_activate_sw_breakpoint(). Currently although
the calls are paired correctly they are needlessly smeared across three
different functions. Worse this also results in code to drive polled I/O
being called with breakpoints activated which, in turn, needlessly
increases the set of functions that will recursively trap if breakpointed.

Fix this by moving the activation of breakpoints into the debug core.

Reviewed-by: Douglas Anderson <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Daniel Thompson <[email protected]>

show more ...

kdb: Don't back trace on a cpu that didn't round up

If you have a CPU that fails to round up and then run 'btc' you'll end
up crashing in kdb becaue we dereferenced NULL. Let's add a check.
It's wi

kdb: Don't back trace on a cpu that didn't round up

If you have a CPU that fails to round up and then run 'btc' you'll end
up crashing in kdb becaue we dereferenced NULL. Let's add a check.
It's wise to also set the task to NULL when leaving the debugger so
that if we fail to round up on a later entry into the debugger we
won't backtrace a stale task.

Signed-off-by: Douglas Anderson <[email protected]>
Acked-by: Daniel Thompson <[email protected]>
Signed-off-by: Daniel Thompson <[email protected]>

show more ...

kgdb: timeout if secondary CPUs ignore the roundup

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

kgdb: timeout if secondary CPUs ignore the roundup

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: Daniel Thompson <[email protected]>
Cc: Jason Wessel <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Jason Wessel <[email protected]>

show more ...

kdb: Add support for external NMI handler to call KGDB/KDB

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

kdb: Add support for external NMI handler to call KGDB/KDB

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: Mike Travis <[email protected]>
Acked-by: Jason Wessel <[email protected]>
Reviewed-by: Dimitri Sivanich <[email protected]>
Reviewed-by: Hedi Berriche <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

show more ...

kdb: Remove unhandled ssb command

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: Vincent Stehlé <vince

kdb: Remove unhandled ssb command

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: Vincent Stehlé <[email protected]>
Signed-off-by: Jason Wessel <[email protected]>

show more ...

kdb: Setup basic kdb state before invoking commands via kgdb

Although invasive kdb commands are not supported via kgdb, some useful
non-invasive commands like bt* require basic kdb state to be setup

kdb: Setup basic kdb state before invoking commands via kgdb

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: Matt Klein <[email protected]>
Signed-off-by: Jason Wessel <[email protected]>

show more ...

kernel/debug: Make use of KGDB_REASON_NMI

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

kernel/debug: Make use of KGDB_REASON_NMI

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: Anton Vorontsov <[email protected]>
Signed-off-by: Jason Wessel <[email protected]>

show more ...

kernel: Fix files explicitly needing EXPORT_SYMBOL infrastructure

These files were getting <linux/module.h> via an implicit non-obvious
path, but we want to crush those out of existence since they c

kernel: Fix files explicitly needing EXPORT_SYMBOL infrastructure

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: Paul Gortmaker <[email protected]>

show more ...

kdb: Remove all references to DOING_KGDB2

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 us

kdb: Remove all references to DOING_KGDB2

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: Jason Wessel <[email protected]>

show more ...

kdb,kgdb: Implement switch and pass buffer from kdb -> gdb

When switching from kdb mode to kgdb mode packets were getting lost
depending on the size of the fifo queue of the serial chip. When gdb
i

kdb,kgdb: Implement switch and pass buffer from kdb -> gdb

When switching from kdb mode to kgdb mode packets were getting lost
depending on the size of the fifo queue of the serial chip. When gdb
initially connects if it is in kdb mode it should entirely send any
character buffer over to the gdbstub when switching connections.

Previously kdb was zero'ing out the character buffer and this could
lead to gdb failing to connect at all, or a lengthy pause could occur
on the initial connect.

Signed-off-by: Jason Wessel <[email protected]>

show more ...

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

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 <[email protected]>

show more ...

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 n

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: [email protected]
Signed-off-by: Jason Wessel <[email protected]>

show more ...

kdb: core for kgdb back end (1 of 2)

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

kdb: core for kgdb back end (1 of 2)

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.

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

CC: [email protected]
Signed-off-by: Jason Wessel <[email protected]>
Signed-off-by: Martin Hicks <[email protected]>

show more ...