linux-toradex.git/kernel/debug/kdb/kdb_debugger.c, branch v5.0-rc3

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

2018-12-30T08:31:23+00:00

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 
Acked-by: Daniel Thompson 
Signed-off-by: Daniel Thompson

kgdb: timeout if secondary CPUs ignore the roundup

2014-11-11T15:31:53+00:00

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 
Cc: Jason Wessel 
Signed-off-by: Andrew Morton 
Signed-off-by: Jason Wessel

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

2013-10-03T16:47:54+00:00

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 
Acked-by: Jason Wessel 
Reviewed-by: Dimitri Sivanich 
Reviewed-by: Hedi Berriche 
Cc: Peter Zijlstra 
Cc: Paul Mackerras 
Cc: Arnaldo Carvalho de Melo 
Link: http://lkml.kernel.org/r/20131002151417.928886849@asylum.americas.sgi.com
Signed-off-by: Ingo Molnar

kdb: Remove unhandled ssb command

2013-03-02T14:52:20+00:00

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 
Signed-off-by: Jason Wessel

kdb: Setup basic kdb state before invoking commands via kgdb

2013-03-02T14:52:17+00:00

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 
Signed-off-by: Jason Wessel

kernel/debug: Make use of KGDB_REASON_NMI

2012-07-31T13:16:43+00:00

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 
Signed-off-by: Jason Wessel

kernel: Fix files explicitly needing EXPORT_SYMBOL infrastructure

2011-10-31T23:30:05+00:00

These files were getting  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

kdb: Remove all references to DOING_KGDB2

2011-08-01T18:23:59+00:00

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

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

2011-08-01T18:23:59+00:00

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

kdb,debug_core: adjust master cpu switch logic against new debug_core locking

2010-10-22T20:34:13+00:00

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