linux.git/kernel/debug/kdb/kdb_debugger.c, branch v6.12.80

kdb: Get rid of custom debug heap allocator

2021-07-27T13:46:11+00:00

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 
Signed-off-by: Sumit Garg 
Reviewed-by: Douglas Anderson 
Link: https://lore.kernel.org/r/20210714055620.369915-1-sumit.garg@linaro.org
Signed-off-by: Daniel Thompson

kernel: debug: Centralize dbg_[de]activate_sw_breakpoints

2020-10-01T13:23:45+00:00

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 
Link: https://lore.kernel.org/r/20200927211531.1380577-4-daniel.thompson@linaro.org
Signed-off-by: Daniel Thompson

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