linux.git/lib/dynamic_debug.c, branch v6.12.80

dyndbg: use seq_putc() in ddebug_proc_show()

2024-09-02T03:43:29+00:00

Single characters should be put into a sequence.  Thus use the
corresponding function "seq_putc".

This issue was transformed by using the Coccinelle software.

Link: https://lkml.kernel.org/r/375b5b4b-6295-419e-bae9-da724a7a682d@web.de
Signed-off-by: Markus Elfring 
Cc: Jason Baron 
Cc: Jim Cromie 
Signed-off-by: Andrew Morton

dyndbg: fix old BUG_ON in >control parser

2024-04-30T07:20:48+00:00

Fix a BUG_ON from 2009.  Even if it looks "unreachable" (I didn't
really look), lets make sure by removing it, doing pr_err and return
-EINVAL instead.

Cc: stable 
Signed-off-by: Jim Cromie 
Link: https://lore.kernel.org/r/20240429193145.66543-2-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman

dyndbg: replace kstrdup() + strchr() with kstrdup_and_replace()

2024-03-06T21:07:39+00:00

Replace open coded functionalify of kstrdup_and_replace() with a call.

Link: https://lkml.kernel.org/r/20240213162741.3102810-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Andy Shevchenko 
Reviewed-by: Luis Chamberlain 
Cc: Jason Baron 
Cc: Jim Cromie 
Signed-off-by: Andrew Morton

dyndbg: add source filename to prefix

2023-08-04T13:28:41+00:00

Printing the line number without the file is of limited usefulness.

Knowing the filename also makes it also easier to relate the logged
information to the controlfile.

Example:

    # modprobe test_dynamic_debug
    # echo 'file test_dynamic_debug.c =pfsl' > /proc/dynamic_debug/control
    # echo 1 > /sys/module/test_dynamic_debug/parameters/do_prints
    # dmesg | tail -2
    [   71.802212] do_cats:lib/test_dynamic_debug.c:103: test_dd: doing categories
    [   71.802227] do_levels:lib/test_dynamic_debug.c:123: test_dd: doing levels

Signed-off-by: Thomas Weißschuh 
Acked-by: Jim Cromie 
Acked-by: Jason Baron 
Reviewed-by: Luis Chamberlain 
Link: https://lore.kernel.org/r/20230709-dyndbg-filename-v2-3-fd83beef0925@weissschuh.net
Signed-off-by: Greg Kroah-Hartman

dyndbg: increase PREFIX_SIZE to 128

2023-08-04T13:28:41+00:00

A follow-up patch will add the possibility to print the filename as part
of the prefix.
Increase the maximum prefix size to accommodate this.

Signed-off-by: Thomas Weißschuh 
Reviewed-by: Luis Chamberlain 
Link: https://lore.kernel.org/r/20230709-dyndbg-filename-v2-2-fd83beef0925@weissschuh.net
Signed-off-by: Greg Kroah-Hartman

dyndbg: constify opt_array

2023-08-04T13:28:40+00:00

It is never modified, so mark it const.

Signed-off-by: Thomas Weißschuh 
Reviewed-by: Luis Chamberlain 
Link: https://lore.kernel.org/r/20230709-dyndbg-filename-v2-1-fd83beef0925@weissschuh.net
Signed-off-by: Greg Kroah-Hartman

dyndbg: use the module notifier callbacks

2023-03-09T20:58:36+00:00

Bring dynamic debug in line with other subsystems by using the module
notifier callbacks. This results in a net decrease in core module
code.

Additionally, Jim Cromie has a new dynamic debug classmap feature,
which requires that jump labels be initialized prior to dynamic debug.
Specifically, the new feature toggles a jump label from the existing
dynamic_debug_setup() function. However, this does not currently work
properly, because jump labels are initialized via the
'module_notify_list' notifier chain, which is invoked after the
current call to dynamic_debug_setup(). Thus, this patch ensures that
jump labels are initialized prior to dynamic debug by setting the
dynamic debug notifier priority to 0, while jump labels have the
higher priority of 1.

Tested by Jim using his new test case, and I've verfied the correct
printing via: # modprobe test_dynamic_debug dyndbg.

Link: https://lore.kernel.org/lkml/20230113193016.749791-21-jim.cromie@gmail.com/
Reported-by: kernel test robot 
Link: https://lore.kernel.org/oe-kbuild-all/202302190427.9iIK2NfJ-lkp@intel.com/
Tested-by: Jim Cromie 
Reviewed-by: Vincenzo Palazzo 
Cc: Peter Zijlstra 
CC: Jim Cromie 
Cc: Luis Chamberlain 
Cc: Greg Kroah-Hartman 
Signed-off-by: Jason Baron 
Signed-off-by: Luis Chamberlain

dyndbg: remove unused 'base' arg from __ddebug_add_module()

2023-03-09T20:57:24+00:00

The 'base' parameter to __ddebug_add_module() is no longer in use
after: Commit b7b4eebdba7b ("dyndbg: gather __dyndbg[] state into
struct _ddebug_info").

Cc: Jim Cromie 
Cc: Greg Kroah-Hartman 
Tested-by: Jim Cromie 
Reviewed-by: Vincenzo Palazzo 
Signed-off-by: Jason Baron 
Signed-off-by: Luis Chamberlain

dyndbg: add drm.debug style (drm/parameters/debug) bitmap support

2022-09-07T15:04:49+00:00

Add kernel_param_ops and callbacks to use a class-map to validate and
apply input to a sysfs-node, which allows users to control classes
defined in that class-map.  This supports uses like:

  echo 0x3 > /sys/module/drm/parameters/debug

IE add these:

 - int param_set_dyndbg_classes()
 - int param_get_dyndbg_classes()
 - struct kernel_param_ops param_ops_dyndbg_classes

Following the model of kernel/params.c STANDARD_PARAM_DEFS, these are
non-static and exported.  This might be unnecessary here.

get/set use an augmented kernel_param; the arg refs a new struct
ddebug_class_param, which contains:

- A ptr to user's state-store; a union of &ulong for drm.debug, &int
  for nouveau level debug.  By ref'g the client's bit-state _var, code
  coordinates with existing code (like drm_debug_enabled) which uses
  it, so existing/remaining calls can work unchanged.  Changing
  drm.debug to a ulong allows use of BIT() etc.

- FLAGS: dyndbg.flags toggled by changes to bitmap. Usually just "p".

- MAP: a pointer to struct ddebug_classes_map, which maps those
  class-names to .class_ids 0..N that the module is using.  This
  class-map is declared & initialized by DECLARE_DYNDBG_CLASSMAP.

- map-type: 4 enums DD_CLASS_TYPE_* select 2 input forms and 2 meanings.

numeric input:
  DD_CLASS_TYPE_DISJOINT_BITS	integer input, independent bits. ie: drm.debug
  DD_CLASS_TYPE_LEVEL_NUM	integer input, 0..N levels

classnames-list (comma separated) input:
  DD_CLASS_TYPE_DISJOINT_NAMES	each name affects a bit, others preserved
  DD_CLASS_TYPE_LEVEL_NAMES	names have level meanings, like kern_levels.h

_NAMES    - comma-separated classnames (with optional +-)
_NUM      - numeric input, 0-N expected
_BITS     - numeric input, 0x1F bitmap form expected

_DISJOINT - bits are independent
_LEVEL    - (x /sys/module/drm/parameters/debug_catnames

A naive _LEVEL_NAMES use, with one class, that sets all in the
class-map according to (x /sys/module/test_dynamic_debug/parameters/p_level_names
  : problem solved
  echo -L1 > /sys/module/test_dynamic_debug/parameters/p_level_names

Note this artifact:

  : this is same as prev cmd (due to +/-)
  echo L0 > /sys/module/test_dynamic_debug/parameters/p_level_names

  : this is "even-more" off, but same wo __pr_debug_class(L0, "..").
  echo -L0 > /sys/module/test_dynamic_debug/parameters/p_level_names

A stress-test/make-work usage (kid toggling a light switch):

  echo +L7,L0,L7,L0,L7,L0,L7,L0,L7,L0,L7,L0,L7 \
       > /sys/module/test_dynamic_debug/parameters/p_level_names

ddebug_apply_class_bitmap(): inside-fn, works on bitmaps, receives
new-bits, finds diffs vs client-bitvector holding "current" state,
and issues exec_query to commit the adjustment.

param_set_dyndbg_classes(): interface fn, sends _NAMES to
param_set_dyndbg_classnames() and returns, falls thru to handle _BITS,
_NUM internally, and calls ddebug_apply_class_bitmap().  Finishes by
updating state.

param_set_dyndbg_classnames(): handles classnames-list in loop, calls
ddebug_apply_class_bitmap for each, then updates state.

NOTES:

_LEVEL_ is overlay on _DISJOINT_; inputs are converted to a bitmask,
by the callbacks.  IOW this is possible, and possibly confusing:

  echo class V3 +p > control
  echo class V1 -p > control

IMO thats ok, relative verbosity is an interface property.

_LEVEL_NUM maps still need class-names, even though the names are not
usable at the sysfs interface (unlike with _NAMES style).  The names
are the only way to >control the classes.

 - It must have a "V0" name,
   something below "V1" to turn "V1" off.
   __pr_debug_cls(V0,..) is printk, don't do that.

 - "class names" is required at the >control interface.
 - relative levels are not enforced at >control

_LEVEL_NAMES bear +/- signs, which alters the on-bit-pos by 1.  IOW,
+L2 means L0,L1,L2, and -L2 means just L0,L1.  This kinda spoils the
readback fidelity, since the L0 bit gets turned on by any use of any
L*, except "-L0".

All the interface uncertainty here pertains to the _NAMES features.
Nobody has actually asked for this, so its practical (if a little
tedious) to split it out.

Signed-off-by: Jim Cromie 
Link: https://lore.kernel.org/r/20220904214134.408619-21-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman

dyndbg: validate class FOO by checking with module

2022-09-07T15:04:49+00:00

Add module-to-class validation:

  #> echo class DRM_UT_KMS +p > /proc/dynamic_debug/control

If a query has "class FOO", then ddebug_find_valid_class(), called
from ddebug_change(), requires that FOO is known to module X,
otherwize the query is skipped entirely for X.  This protects each
module's class-space, other than the default:31.

The authors' choice of FOO is highly selective, giving isolation
and/or coordinated sharing of FOOs.  For example, only DRM modules
should know and respond to DRM_UT_KMS.

So this, combined with module's opt-in declaration of known classes,
effectively privatizes the .class_id space for each module (or
coordinated set of modules).

Notes:

For all "class FOO" queries, ddebug_find_valid_class() is called, it
returns the map matching the query, and sets valid_class via an
*outvar).

If no "class FOO" is supplied, valid_class = _CLASS_DFLT.  This
insures that legacy queries do not trample on new class'd callsites,
as they get added.

Also add a new column to control-file output, displaying non-default
class-name (when found) or the "unknown _id:", if it has not been
(correctly) declared with one of the declarator macros.

Signed-off-by: Jim Cromie 
Link: https://lore.kernel.org/r/20220904214134.408619-18-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman