Commit graph

138 commits

Author SHA1 Message Date
Thomas Weißschuh
31ed379b7c dyndbg: add source filename to prefix
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 <linux@weissschuh.net>
Acked-by: Jim Cromie <jim.cromie@gmail.com>
Acked-by: Jason Baron <jbaron@akamai.com>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20230709-dyndbg-filename-v2-3-fd83beef0925@weissschuh.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-08-04 15:28:41 +02:00
Thomas Weißschuh
3bdaf73905 dyndbg: increase PREFIX_SIZE to 128
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 <linux@weissschuh.net>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20230709-dyndbg-filename-v2-2-fd83beef0925@weissschuh.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-08-04 15:28:41 +02:00
Thomas Weißschuh
882f7a64ed dyndbg: constify opt_array
It is never modified, so mark it const.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20230709-dyndbg-filename-v2-1-fd83beef0925@weissschuh.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-08-04 15:28:40 +02:00
Jason Baron
7deabd6749 dyndbg: use the module notifier callbacks
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 <lkp@intel.com>
Link: https://lore.kernel.org/oe-kbuild-all/202302190427.9iIK2NfJ-lkp@intel.com/
Tested-by: Jim Cromie <jim.cromie@gmail.com>
Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
CC: Jim Cromie <jim.cromie@gmail.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jason Baron <jbaron@akamai.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
2023-03-09 12:58:36 -08:00
Jason Baron
85c37208b0 dyndbg: remove unused 'base' arg from __ddebug_add_module()
The 'base' parameter to __ddebug_add_module() is no longer in use
after: Commit b7b4eebdba ("dyndbg: gather __dyndbg[] state into
struct _ddebug_info").

Cc: Jim Cromie <jim.cromie@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Tested-by: Jim Cromie <jim.cromie@gmail.com>
Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Signed-off-by: Jason Baron <jbaron@akamai.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
2023-03-09 12:57:24 -08:00
Jim Cromie
b9400852c0 dyndbg: add drm.debug style (drm/parameters/debug) bitmap support
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<y) on bit-pos.

_DISJOINT treats input like a bit-vector (ala drm.debug), and sets
each bit accordingly.  LEVEL is layered on top of this.

_LEVEL treats input like a bit-pos:N, then sets bits(0..N)=1, and
bits(N+1..max)=0.  This applies (bit<N) semantics on top of disjoint
bits.

USAGES:

A potentially typical _DISJOINT_NAMES use:

  echo +DRM_UT_CORE,+DRM_UT_KMS,-DRM_UT_DRIVER,-DRM_UT_ATOMIC \
       > /sys/module/drm/parameters/debug_catnames

A naive _LEVEL_NAMES use, with one class, that sets all in the
class-map according to (x<y):

  : problem seen
  echo +L7 > /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 <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-21-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-07 17:04:49 +02:00
Jim Cromie
a4a2a42741 dyndbg: validate class FOO by checking with module
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 <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-18-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-07 17:04:49 +02:00
Jim Cromie
c45f67ace8 dyndbg: add ddebug_attach_module_classes
Add ddebug_attach_module_classes(), call it from ddebug_add_module().
It scans the classes/section its given, finds records where the
module-name matches the module being added, and adds them to the
module's maps list.  No locking here, since the record
isn't yet linked into the ddebug_tables list.

It is called indirectly from 2 sources:

 - from load_module(), where it scans the module's __dyndbg_classes
   section, which contains DYNAMIC_DEBUG_CLASSES definitions from just
   the module.

 - from dynamic_debug_init(), where all DYNAMIC_DEBUG_CLASSES
   definitions of each builtin module have been packed together.
   This is why ddebug_attach_module_classes() checks module-name.

NOTES

Its (highly) likely that builtin classes will be ordered by module
name (just like prdbg descriptors are in the __dyndbg section).  So
the list can be replaced by a vector (ptr + length), which will work
for loaded modules too.  This would imitate whats currently done for
the _ddebug descriptors.

That said, converting to vector,len is close to pointless; a small
minority of modules will ever define a class-map, and almost all of
them will have only 1 or 2 class-maps, so theres only a couple dozen
pointers to save.  TODO: re-evaluate for lines removable.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-17-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-07 17:04:49 +02:00
Jim Cromie
66f4006b6a kernel/module: add __dyndbg_classes section
Add __dyndbg_classes section, using __dyndbg as a model. Use it:

vmlinux.lds.h:

KEEP the new section, which also silences orphan section warning on
loadable modules.  Add (__start_/__stop_)__dyndbg_classes linker
symbols for the c externs (below).

kernel/module/main.c:
- fill new fields in find_module_sections(), using section_objs()
- extend callchain prototypes
  to pass classes, length
  load_module(): pass new info to dynamic_debug_setup()
  dynamic_debug_setup(): new params, pass through to ddebug_add_module()

dynamic_debug.c:
- add externs to the linker symbols.

ddebug_add_module():
- It currently builds a debug_table, and *will* find and attach classes.

dynamic_debug_init():
- add class fields to the _ddebug_info cursor var: di.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-16-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-07 17:04:49 +02:00
Jim Cromie
b7b4eebdba dyndbg: gather __dyndbg[] state into struct _ddebug_info
This new struct composes the linker provided (vector,len) section,
and provides a place to add other __dyndbg[] state-data later:

  descs - the vector of descriptors in __dyndbg section.
  num_descs - length of the data/section.

Use it, in several different ways, as follows:

In lib/dynamic_debug.c:

ddebug_add_module(): Alter params-list, replacing 2 args (array,index)
with a struct _ddebug_info * containing them both, with room for
expansion.  This helps future-proof the function prototype against the
looming addition of class-map info into the dyndbg-state, by providing
a place to add more member fields later.

NB: later add static struct _ddebug_info builtins_state declaration,
not needed yet.

ddebug_add_module() is called in 2 contexts:

In dynamic_debug_init(), declare, init a struct _ddebug_info di
auto-var to use as a cursor.  Then iterate over the prdbg blocks of
the builtin modules, and update the di cursor before calling
_add_module for each.

Its called from kernel/module/main.c:load_info() for each loaded
module:

In internal.h, alter struct load_info, replacing the dyndbg array,len
fields with an embedded _ddebug_info containing them both; and
populate its members in find_module_sections().

The 2 calling contexts differ in that _init deals with contiguous
subranges of __dyndbgs[] section, packed together, while loadable
modules are added one at a time.

So rename ddebug_add_module() into outer/__inner fns, call __inner
from _init, and provide the offset into the builtin __dyndbgs[] where
the module's prdbgs reside.  The cursor provides start, len of the
subrange for each.  The offset will be used later to pack the results
of builtin __dyndbg_sites[] de-duplication, and is 0 and unneeded for
loadable modules,

Note:

kernel/module/main.c includes <dynamic_debug.h> for struct
_ddeubg_info.  This might be prone to include loops, since its also
included by printk.h.  Nothing has broken in robot-land on this.

cc: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-12-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-07 17:04:48 +02:00
Jim Cromie
aa86a15453 dyndbg: cleanup auto vars in dynamic_debug_init
rework var-names for clarity, regularity
rename variables
  - n to mod_sites - it counts sites-per-module
  - entries to i - display only
  - iter_start to iter_mod_start - marks start of each module's subrange
  - modct to mod_ct - stylistic

new iterator var:
  - site - cursor parallel to iter
    1st step towards 'demotion' of iter->site, for removal later

treat vars as iters:
  - drop init at top
    init just above for-loop, in a textual block

Acked-by: Jason Baron <jbaron@akamai.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-11-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-07 17:04:48 +02:00
Jim Cromie
e26ef3af96 dyndbg: drop EXPORTed dynamic_debug_exec_queries
This exported fn is unused, and will not be needed. Lets dump it.

The export was added to let drm control pr_debugs, as part of using
them to avoid drm_debug_enabled overheads.  But its better to just
implement the drm.debug bitmap interface, then its available for
everyone.

Fixes: a2d375eda7 ("dyndbg: refine export, rename to dynamic_debug_exec_queries()")
Fixes: 4c0d77828d ("dyndbg: export ddebug_exec_queries")
Acked-by: Jason Baron <jbaron@akamai.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-10-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-07 16:58:23 +02:00
Jim Cromie
e75ef56f74 dyndbg: let query-modname override actual module name
dyndbg's control-parser: ddebug_parse_query(), requires that search
terms: module, func, file, lineno, are used only once in a query; a
thing cannot be named both foo and bar.

The cited commit added an overriding module modname, taken from the
module loader, which is authoritative.  So it set query.module 1st,
which disallowed its use in the query-string.

But now, its useful to allow a module-load to enable classes across a
whole (or part of) a subsystem at once.

  # enable (dynamic-debug in) drm only
  modprobe drm dyndbg="class DRM_UT_CORE +p"

  # get drm_helper too
  modprobe drm dyndbg="class DRM_UT_CORE module drm* +p"

  # get everything that knows DRM_UT_CORE
  modprobe drm dyndbg="class DRM_UT_CORE module * +p"

  # also for boot-args:
  drm.dyndbg="class DRM_UT_CORE module * +p"

So convert the override into a default, by filling it only when/after
the query-string omitted the module.

NB: the query class FOO handling is forthcoming.

Fixes: 8e59b5cfb9 dynamic_debug: add modname arg to exec_query callchain
Acked-by: Jason Baron <jbaron@akamai.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-8-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-07 16:58:23 +02:00
Jim Cromie
47ea6f99d0 dyndbg: use ESCAPE_SPACE for cat control
`cat control` currently does octal escape, so '\n' becomes "\012".
Change this to display as "\n" instead, which reads much cleaner.

   :#> head -n7 /proc/dynamic_debug/control
   # filename:lineno [module]function flags format
   init/main.c:1179 [main]initcall_blacklist =_ "blacklisting initcall %s\n"
   init/main.c:1218 [main]initcall_blacklisted =_ "initcall %s blacklisted\n"
   init/main.c:1424 [main]run_init_process =_ "  with arguments:\n"
   init/main.c:1426 [main]run_init_process =_ "    %s\n"
   init/main.c:1427 [main]run_init_process =_ "  with environment:\n"
   init/main.c:1429 [main]run_init_process =_ "    %s\n"

Acked-by: Jason Baron <jbaron@akamai.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-7-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-07 16:58:23 +02:00
Jim Cromie
773beabbb8 dyndbg: reverse module.callsite walk in cat control
Walk the module's vector of callsites backwards; ie N..0.  This
"corrects" the backwards appearance of a module's prdbg vector when
walked 0..N.  I think this is due to linker mechanics, which I'm
inclined to treat as immutable, and the order is fixable in display.

No functional changes.

Combined with previous commit, which reversed tables-list, we get:

  :#> head -n7 /proc/dynamic_debug/control
  # filename:lineno [module]function flags format
  init/main.c:1179 [main]initcall_blacklist =_ "blacklisting initcall %s\012"
  init/main.c:1218 [main]initcall_blacklisted =_ "initcall %s blacklisted\012"
  init/main.c:1424 [main]run_init_process =_ "  with arguments:\012"
  init/main.c:1426 [main]run_init_process =_ "    %s\012"
  init/main.c:1427 [main]run_init_process =_ "  with environment:\012"
  init/main.c:1429 [main]run_init_process =_ "    %s\012"

Acked-by: Jason Baron <jbaron@akamai.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-6-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-07 16:58:23 +02:00
Jim Cromie
2ad556f700 dyndbg: reverse module walk in cat control
/proc/dynamic_debug/control walks the prdbg catalog in "reverse",
fix this by adding new ddebug_tables to tail of list.

This puts init/main.c entries 1st, which looks more than coincidental.

no functional changes.

Acked-by: Jason Baron <jbaron@akamai.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-5-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-07 16:58:23 +02:00
Jim Cromie
bfa3ca448e dyndbg: show both old and new in change-info
print "old => new" flag values to the info("change") message.

no functional change.

Acked-by: Jason Baron <jbaron@akamai.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-4-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-07 16:58:23 +02:00
Jim Cromie
ee879be38b dyndbg: fix static_branch manipulation
In https://lore.kernel.org/lkml/20211209150910.GA23668@axis.com/

Vincent's patch commented on, and worked around, a bug toggling
static_branch's, when a 2nd PRINTK-ish flag was added.  The bug
results in a premature static_branch_disable when the 1st of 2 flags
was disabled.

The cited commit computed newflags, but then in the JUMP_LABEL block,
failed to use that result, instead using just one of the terms in it.
Using newflags instead made the code work properly.

This is Vincents test-case, reduced.  It needs the 2nd flag to
demonstrate the bug, but it's explanatory here.

pt_test() {
    echo 5 > /sys/module/dynamic_debug/verbose

    site="module tcp" # just one callsite
    echo " $site =_ " > /proc/dynamic_debug/control # clear it

    # A B ~A ~B
    for flg in +T +p "-T #broke here" -p; do
	echo " $site $flg " > /proc/dynamic_debug/control
    done;

    # A B ~B ~A
    for flg in +T +p "-p #broke here" -T; do
	echo " $site $flg " > /proc/dynamic_debug/control
    done
}
pt_test

Fixes: 84da83a6ff dyndbg: combine flags & mask into a struct, simplify with it
CC: vincent.whitchurch@axis.com
Acked-by: Jason Baron <jbaron@akamai.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20220904214134.408619-2-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-07 16:58:23 +02:00
Jim Cromie
09ee10ff80 dyndbg: refine verbosity 1-4 summary-detail
adjust current v*pr_info() calls to fit an overview..detail scheme:

1- module level activity: add/remove, etc
2- command ingest, splitting, summary of effects.
   per >control write
3- command parsing: op, flags, search terms
4- per-site change msg
   can yield ~3k x 2 logs per echo "+p;-p" > command.

Summarize these 4 levels in MODULE_PARM_DESC, and update verbose=3 in Doc.

2- is new, to isolate a problem where a stress-test script (which
feeds ~4kb multi-command strings) would produce short writes,
truncating last command and causing parsing errors, which confused
test results.  The script fix was to use syswrite, to deliver full
proper commands.

4- gets per-callsite "changed:" pr-infos, which are very noisy during
stress tests, and formerly obscured v1-3 messages, and overwhelmed the
static-key workload being tested.

The verbose parameter has previously seen adjustment:
commit 481c0e33f1 ("dyndbg: refine debug verbosity; 1 is basic, 2 more chatty")

The script driving these adjustments is:

 !/usr/bin/perl -w

=for Doc

1st purpose was to benchmark the effect of wildcard queries on query
performance; if wildcards are risk free cheap enough, we can deploy
them in the (floating) format search.  1st finding: wildcards take 2x
as long to process.

2nd purpose was to benchmark real static-key changes VS simple flag
changes.  Found ~100x decrease for the hard work.

The script maximizes workload per >control by packing it a ~4kb
string of "+p; -p;" commands; this uncovered some broken stuff.

The 85th query failed, and appears to be truncated, so is gramatically
incorrect.  Its either an error here, or in the kernel.  Its not
happening atm, retest.

Plot thickens: fail only happens doing +-p, not +-mf, likely load
dependent.  Error remains consistent.  Looks like a short write,
longer on writer than kernel-reader.  Try syswrite on handle to
control this.  That fixed short write.

=cut

use Getopt::Std;

getopts('vN:k:', \my %opts) or die <<EOH;
$0 options:
    -v		verbose
    -k=n	kernel dyndbg verbosity
    -N=n	number of loops.. tbrc
EOH
$opts{N} //= 10; # !undef, 0 tests too long.

my $ctrl = '/proc/dynamic_debug/control';

vx($opts{k}) if defined $opts{k}; # works on -k0

open(my $CTL, '>', $ctrl) or die "cant open $ctrl for writing: $!\n";

sub vx {
    my $arg = shift;
    my $cmd = "echo $arg > /sys/module/dynamic_debug/parameters/verbose";
    system($cmd);
    warn("vx problem: rc:$? err:$! qry: $cmd\n") if ($?);
}

sub qryOK {
    my $qry = shift;

    print "syntax test: <\n$qry>\n" if $opts{v};
    my $bytes = syswrite $CTL, $qry;
    printf "short read: $bytes / %d\n", length $qry if $bytes < length $qry;
    if ($?) {
	warn "rc:$? err:$! qry: $qry\n";
	return 0;
    }
    return 1;
}

sub build_queries {
    my ($cmd, $flags, $ct) = @_;

    # build experiment and reference queries

    my $cycle = " $cmd +$flags # on ; $cmd -$flags # off \n";
    my $ref   = " +$flags ; -$flags \n";

    my $len = length $cycle;
    my $max = int(4096 / $len); # break/fit to buffer size
    $ct |= $max;
    print "qry: ct:$max x << \n$cycle >>\n";

    return unless qryOK($ref);
    return unless qryOK($cycle);

    my $wild = $cycle x $ct;
    my $empty = $ref x $ct;

    printf "len: %d, %d\n", length $wild, length $empty;

    return { trial => $wild,
	     ref => $empty,
	     probe => $cycle,
	     zero => $ref,
	     count => $ct,
	     max => $max
    };
}

my $query_set = build_queries(' file "*" module "*" func "*" ', "mf");

qryOK($query_set->{zero});
qryOK($query_set->{probe});

qryOK($query_set->{ref});
qryOK($query_set->{trial});

use Benchmark;
sub dobatch {
    my ($cmd, $flags, $reps, $ct) = @_;
    $reps ||= $opts{N};

    my $qs = build_queries($cmd, $flags, $ct);

    timethese($reps,
	      {
		  wildcards => sub {
		      syswrite $CTL, $qs->{trial};
		  },
		  no_search => sub {
		      syswrite $CTL, $qs->{ref};
		  }
	      }
	);
}

sub bench_static_key_toggle {
    vx 0;
    dobatch(' file "*" module "*" func "*" ', "mf");
    dobatch(' file "*" module "*" func "*" ', "p");
}

sub bench_verbose_levels {
    for my $i (0..4) {
	vx $i;
	dobatch(' file "*" module "*" func "*" ', "mf");
    }
}

bench_static_key_toggle();

__END__

Heres how the test-script runs:

:: verbose=3 parsing info

[   48.401646] dyndbg: query 95: "file "*" module "*" func "*"  -mf # off " mod:*
[   48.402040] dyndbg: split into words: "file" "*" "module" "*" "func" "*" "-mf"
[   48.402456] dyndbg: op='-'
[   48.402615] dyndbg: flags=0x6
[   48.402779] dyndbg: *flagsp=0x0 *maskp=0xfffffff9
[   48.403033] dyndbg: parsed: func="*" file="*" module="*" format="" lineno=0-0
[   48.403674] dyndbg: applied: func="*" file="*" module="*" format="" lineno=0-0

:: verbose=2 >control summary.
   ~300k site matches/changes per 4kb command

[   48.404063] dyndbg: processed 96 queries, with 296160 matches, 0 errs

:: 2 queries against each other, no-search vs all-wildcard-search

qry: ct:48 x <<
  file "*" module "*" func "*"  +mf # on ;  file "*" module "*" func "*"  -mf # off
 >>
len: 4080, 576
Benchmark: timing 10 iterations of no_search, wildcards...
 no_search:  0 wallclock secs ( 0.00 usr +  0.03 sys =  0.03 CPU) @ 333.33/s (n=10)
            (warning: too few iterations for a reliable count)
 wildcards:  0 wallclock secs ( 0.00 usr +  0.09 sys =  0.09 CPU) @ 111.11/s (n=10)
            (warning: too few iterations for a reliable count)

:: 2 queries, both doing real work / changing stati-key states.

qry: ct:49 x <<
  file "*" module "*" func "*"  +p # on ;  file "*" module "*" func "*"  -p # off
 >>
len: 4067, 490
Benchmark: timing 10 iterations of no_search, wildcards...
 no_search: 20 wallclock secs ( 0.00 usr + 20.36 sys = 20.36 CPU) @  0.49/s (n=10)
 wildcards: 21 wallclock secs ( 0.00 usr + 21.08 sys = 21.08 CPU) @  0.47/s (n=10)
bash-5.1#

Thats 150k static-key-toggles / sec
  ~600x slower than simple flags
  on qemu --smp 3 run

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20211019210746.185307-1-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-21 13:01:25 +02:00
Jim Cromie
1f8818e352 dyndbg: fix spurious vNpr_info change
The cited commit inadvertently altered the verbose level of a
vpr_info, restore it to original.

Fixes: 216a0fc408 ("dyndbg: show module in vpr-info in dd-exec-queries")
Signed-off-By: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20211014223614.1952171-1-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-15 10:02:29 +02:00
Jim Cromie
7edde0c807 dyndbg: no vpr-info on empty queries
when `echo $cmd > control` contains multiple queries, extra query
separators (;\n) can parse as empty statements.  This is normal, and a
vpr-info on an empty command is just noise.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20211013220726.1280565-4-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-14 10:59:14 +02:00
Jim Cromie
7a5e202dfb dyndbg: vpr-info on remove-module complete, not starting
On qemu --smp 3 runs, remove-module can get called 3 times.
So don't print on entry; instead print "removed" after entry is
found and removed, so just once.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20211013220726.1280565-3-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-14 10:59:10 +02:00
Andrew Halaney
9c40e1aa84 dyndbg: Remove support for ddebug_query param
This param has been deprecated for a very long time now, let's rip it
out.

Signed-off-by: Andrew Halaney <ahalaney@redhat.com>
Signed-off-by: Jason Baron <jbaron@akamai.com>
Link: https://lore.kernel.org/r/1634139622-20667-3-git-send-email-jbaron@akamai.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-14 10:48:56 +02:00
Andrew Halaney
5ca1739748 dyndbg: make dyndbg a known cli param
Right now dyndbg shows up as an unknown parameter if used on boot:

    Unknown command line parameters: dyndbg=+p

That's because it is unknown, it doesn't sit in the __param
section, so the processing done to warn users supplying an unknown
parameter doesn't think it is legitimate.

Install a dummy handler to register it. dynamic debug needs to search
the whole command line for modules listed that are currently builtin,
so there's no real work to be done in this callback.

Fixes: 86d1919a4f ("init: print out unknown kernel parameters")
Tested-by: Jim Cromie <jim.cromie@gmail.com>
Signed-off-by: Andrew Halaney <ahalaney@redhat.com>
Signed-off-by: Jason Baron <jbaron@akamai.com>
Link: https://lore.kernel.org/r/1634139622-20667-2-git-send-email-jbaron@akamai.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-14 10:48:56 +02:00
Jim Cromie
216a0fc408 dyndbg: show module in vpr-info in dd-exec-queries
dynamic_debug_exec_queries() accepts a separate module arg (so it can
support $module.dyndbg boot arg), display that in the vpr-info for a
more useful user-debug context.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20211012183310.1016678-2-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-13 15:21:26 +02:00
Zhen Lei
9dbbc3b9d0 lib: fix spelling mistakes
Fix some spelling mistakes in comments:
permanentely ==> permanently
wont ==> won't
remaning ==> remaining
succed ==> succeed
shouldnt ==> shouldn't
alpha-numeric ==> alphanumeric
storeing ==> storing
funtion ==> function
documenation ==> documentation
Determin ==> Determine
intepreted ==> interpreted
ammount ==> amount
obious ==> obvious
interupts ==> interrupts
occured ==> occurred
asssociated ==> associated
taking into acount ==> taking into account
squence ==> sequence
stil ==> still
contiguos ==> contiguous
matchs ==> matches

Link: https://lkml.kernel.org/r/20210607072555.12416-1-thunder.leizhen@huawei.com
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-08 11:48:20 -07:00
Jim Cromie
7af5662826 dyndbg: display KiB of data memory used.
If booted with verbose>=1, dyndbg prints the memory usage in bytes,
of builtin modules' prdebugs.  KiB reads better.

no functional changes.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20210525033240.35260-1-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-05-27 14:41:57 +02:00
Jim Cromie
a3626bcf5f dyndbg: drop uninformative vpr_info
Remove a vpr_info which I added in 2012, when I knew even less than now.
In 2020, a simpler pr_fmt stripped it of context, and any remaining value.

no functional change.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20210504222235.1033685-3-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-05-13 20:50:23 +02:00
Jim Cromie
640d1eaff2 dyndbg: avoid calling dyndbg_emit_prefix when it has no work
Wrap function in a static-inline one, which checks flags to avoid
calling the function unnecessarily.

And hoist its output-buffer initialization to the grand-caller, which
is already allocating the buffer on the stack, and can trivially
initialize it too.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20210504222235.1033685-2-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-05-13 20:50:23 +02:00
Shuo Chen
7b1ae24827 dyndbg: fix parsing file query without a line-range suffix
Query like 'file tcp_input.c line 1234 +p' was broken by
commit aaebe329bf ("dyndbg: accept 'file foo.c:func1' and 'file
foo.c:10-100'") because a file name without a ':' now makes the loop in
ddebug_parse_query() exits early before parsing the 'line 1234' part.
As a result, all pr_debug() in tcp_input.c will be enabled, instead of only
the one on line 1234.  Changing 'break' to 'continue' fixes this.

Fixes: aaebe329bf ("dyndbg: accept 'file foo.c:func1' and 'file foo.c:10-100'")
Cc: stable <stable@vger.kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Shuo Chen <shuochen@google.com>
Acked-by: Jason Baron <jbaron@akamai.com>
Link: https://lore.kernel.org/r/20210414212400.2927281-1-giantchen@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-04-30 07:43:20 +02:00
Jim Cromie
3577afb005 dyndbg: fix use before null check
In commit a2d375eda7 ("dyndbg: refine export, rename to
dynamic_debug_exec_queries()"), a string is copied before checking it
isn't NULL.  Fix this, report a usage/interface error, and return the
proper error code.

Fixes: a2d375eda7 ("dyndbg: refine export, rename to dynamic_debug_exec_queries()")
Cc: stable@vger.kernel.org
--
-v2 drop comment tweak, improve commit message

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20201209183625.2432329-1-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-12-09 20:10:12 +01:00
Jim Cromie
e5e5fcef60 dyndbg: use keyword, arg varnames for query term pairs
optimize for clarity by replacing word[i,i+1] refs with temps.
no functional changes.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200921190433.1149521-3-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-09-27 14:32:09 +02:00
Greg Kroah-Hartman
952e934d7f Revert "dyndbg: accept query terms like file=bar and module=foo"
This reverts commit 14775b0496 as there
were still some parsing problems with it, and the follow-on patch for
it.

Let's revisit it later, just drop it for now.

Cc: <jbaron@akamai.com>
Cc: Jim Cromie <jim.cromie@gmail.com>
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Fixes: 14775b0496 ("dyndbg: accept query terms like file=bar and module=foo")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-09-10 18:45:03 +02:00
Greg Kroah-Hartman
7f6e1f3072 Revert "dyndbg: fix problem parsing format="foo bar""
This reverts commit 42f07816ac as it
still causes problems.  It will be resolved later, let's revert it so we
can also revert the original patch this was supposed to be helping with.

Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Fixes: 42f07816ac ("dyndbg: fix problem parsing format="foo bar"")
Cc: Jim Cromie <jim.cromie@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-09-10 18:42:38 +02:00
Jim Cromie
42f07816ac dyndbg: fix problem parsing format="foo bar"
commit 14775b0496 ("dyndbg: accept query terms like file=bar and
module=foo") added the combined keyword=value parsing poorly; revert
most of it, keeping the keyword & arg change.

Instead, fix the tokenizer for the new input, by terminating the
keyword (an unquoted word) on '=' as well as space, thus letting the
tokenizer work on the quoted argument, like it would have previously.

Also add a few debug-prints to show more parsing context, into
tokenizer and parse-query, and use "keyword, value" in others.

Fixes: 14775b0496 ("dyndbg: accept query terms like file=bar and module=foo")
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200831182210.850852-4-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-09-04 17:21:56 +02:00
Jim Cromie
a2d375eda7 dyndbg: refine export, rename to dynamic_debug_exec_queries()
commit 4c0d77828d ("dyndbg: export ddebug_exec_queries") had a few
problems:
 - broken non DYNAMIC_DEBUG_CORE configs, sparse warning
 - the exported function modifies query string, breaks on RO strings.
 - func name follows internal convention, shouldn't be exposed as is.

1st is fixed in header with ifdefd function prototype or stub defn.
Also remove an obsolete HAVE-symbol ifdef-comment, and add others.

Fix others by wrapping existing internal function with a new one,
named in accordance with module-prefix naming convention, before
export hits v5.9.0.  In new function, copy query string to a local
buffer, so users can pass hard-coded/RO queries, and internal function
can be used unchanged.

Fixes: 4c0d77828d ("dyndbg: export ddebug_exec_queries")
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200831182210.850852-3-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-09-04 17:21:56 +02:00
Jim Cromie
b52a95eac1 dyndbg: give %3u width in pr-format, cosmetic only
Specify the print-width so log entries line up nicely.

no functional changes.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200831182210.850852-2-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-09-04 17:21:56 +02:00
Jim Cromie
4c0d77828d dyndbg: export ddebug_exec_queries
Export ddebug_exec_queries() for use by modules.

This will allow module authors to control all their *pr_debug*s
dynamically.  And since ddebug_exec_queries() is what implements
"echo $query >control", it gives the same per-callsite control.

Virtues of this:
- simplicity. just an export.
- full control over any/all subsets of callsites.
- same "query/command-string" in code and console
- full callsite selectivity with module file line format

Format in particular deserves special attention; it is where
low-hanging fruit will be found.

Consider: drivers/gpu/drm/amd/display/include/logger_types.h:

  #define DC_LOG_SURFACE(...)          pr_debug("[SURFACE]:"__VA_ARGS__)
  #define DC_LOG_HW_LINK_TRAINING(...) pr_debug("[HW_LINK_TRAINING]:"__VA_ARGS__)
  .. 9 more ..

Thats 11 string prefixes, used in 804 places in drivers/gpu/**
Clearly this is a systematized classification of those callsites.
And one I'd expect to see repeated often.

Using ddebug_exec_queries(), authors can select on those prefixes
as a unitary set, equivalent to:

    echo "module=MODULE_NAME format=^[SURFACE]: +p" >control

Trivially, those sets can be subsected with the other query terms too,
say file=foo, should the author see fit.

Perhaps as important, users can modify the set of enabled callsites,
presumably to aid debugging by enabling helpful debug callsites, and
disabling those that just clutter the info.

Authors could even alter [fmlt] flags, though I dont see a good reason
why they would.  Perhaps harnessed by bug-logging automation to get
fuller, or more minimal bug-reports.

DRM

drm has both drm.debug, which defines 32 categories of drm_printk
logging, and entirely separate uses of pr_debug, which are dynamic on
this i915 laptop, running mainline.  So I can observe and report on
both.

The i915 driver has 118 dyndbg callsites, with following
"classifications" defined in drivers/gpu/drm/i915/gvt/**

$ grep 915 /proc/dynamic_debug/control | cut -d= -f2 | cut -d: -f1,2 | sort -u
_ "gvt: cmd
_ "gvt: core
_ "gvt: dpy
_ "gvt: el
_ "gvt: irq
_ "gvt: mm
_ "gvt: mmio
_ "gvt: render
_ "gvt: sched
_ "%s for root hub!\012"
_ "Vendor defined info completion code %u\012"

This classification is entirely out-of-band for control by drm.debug,
and is only available to root user at the console.  But module authors
can activate them with ddebug_exec_queries(sprintf("format=^%s +p")),
and then decide how to expose the groups to the user for max utility.

drm.debug

drm.debug has 32 bit-flags, and matching enum drm_debug_category
values to classify the ~2943 DRM_DEBUG*() callsites in drivers/gpu

The drm.debug callback could invoke ddebug_exec_queries() with 32
different hardcoded query strings, needing only (bit) ? " +p" : " -p"
added.

I briefly enabled drm.debug=0xff on my i915 laptop, which yielded
these unique prefixes: (dmesg | cut -c17- | cut -d\] -f1 | sort -u)

[drm:drm_atomic_check_only [drm
[drm:drm_atomic_get_crtc_state [drm
[drm:drm_atomic_get_plane_state [drm
[drm:drm_atomic_nonblocking_commit [drm
[drm:drm_atomic_set_fb_for_plane [drm
[drm:drm_atomic_state_default_clear [drm
[drm:__drm_atomic_state_free [drm
[drm:drm_atomic_state_init [drm
[drm:drm_crtc_vblank_helper_get_vblank_timestamp_internal [drm
[drm:drm_handle_vblank [drm
[drm:drm_ioctl [drm
[drm:drm_mode_addfb2 [drm
[drm:drm_mode_object_get [drm
[drm:drm_mode_object_put.part.0 [drm
[drm:drm_update_vblank_count [drm
[drm:drm_vblank_enable [drm
[drm:drm_vblank_restore [drm
[drm:vblank_disable_fn [drm
i915 0000:00:02.0: [drm:gen9_set_dc_state [i915
i915 0000:00:02.0: [drm:intel_atomic_get_global_obj_state [i915
i915 0000:00:02.0: [drm:__intel_display_power_get_domain.part.0 [i915
i915 0000:00:02.0: [drm:__intel_display_power_put_domain [i915
i915 0000:00:02.0: [drm:intel_plane_atomic_calc_changes [i915
i915 0000:00:02.0: [drm:skl_enable_dc6 [i915

Several good format=^prefixes are apparent there, and some misses.

 ^[drm:drm_atomic_	# misses: [drm:__drm_atomic_state_free [drm
 ^[drm:drm_ioctl
 ^[drm:drm_mode
 ^[drm:drm_vblank_	# misses: [drm:drm_update_vblank_count & [drm:vblank_disable_fn

Its not a perfect 1:1 single format-match per class, but the misses
above can be covered with 1 & 2 additional queries, which can be
concatenated together with ";" separators and submitted with 1 call.

Benefits:

For drm, adapting DRM_DEBUG to use dynamic-debug inside could
replicate (and thereby obsolete) lots of bit-checking in current
DRM_DEBUG callsites, at least with JUMP_LABEL optimized code.
ddebug_exec_queries() and a handful of fixed query-strings can select
and thereby control the already classified callsites.

With the classes mapped to queries, the enum type and parameter can be
eliminated (folded away with macro magic), at least for DYNAMIC_DEBUG
& JUMP_LABEL builds.

Is it safe ?

ddebug_exec_queries() is currently exposed to user space in
several limited ways;

1 it is called from module-load callback, where it implements the
  $modname.dyndbg=+p "fake" parameter provided to all modules.

2 it handles query input via >control directly

IOW, it is "fully" exposed to local root user; exposing the same
functionality to other kernel modules is no additional risk.

The other standard issue to check is locking:

dyndbg has a single mutex, taken by ddebug_change to handle >control,
and by ddebug_proc_(start|stop) to span `cat control`.  Queries
submitted via export will typically have module specified, which
dramatically cuts the scan by ddebug_change vs "module=* +p".
ISTM this proposed export presents no locking problems.

TLDR;

It would be interesting to see how drm.dyndbg=$QUERY and
drm.debug=$HEXY would interact; it might be order dependent, as
if given as modprobe args or in /etc/modprobe.d/

Acked-by: <jbaron@akamai.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200719231058.1586423-19-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-07-24 17:00:10 +02:00
Jim Cromie
5aa9ffbbae dyndbg: shorten our logging prefix, drop __func__
For log-message output, reduce column space consumed by current
pr_fmt by dropping __func__ and shortening "dynamic_debug" to
"dyndbg".  This improves readability on narrow consoles, and better
matches other kernel boot info messages.

Acked-by: <jbaron@akamai.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200719231058.1586423-18-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-07-24 17:00:10 +02:00
Jim Cromie
4b334484fa dyndbg: allow anchored match on format query term
This should work:

  echo module=amd* format=^[IF_TRACE]: +p  >/proc/dynamic_debug/control

consider drivers/gpu/drm/amd/display/include/logger_types.h:
It has 11 defines like:

  #define DC_LOG_IF_TRACE(...) pr_debug("[IF_TRACE]:"__VA_ARGS__)

These defines are used 804 times at recent count; they are a good use
case to evaluate existing format-message based classifications of
*pr_debug*.  Those macros prefix the supplied format with a fixed
string, I'd expect most existing message classification schemes to do
something similar.

Hence we want to be able to anchor our match to the beginning of the
format string, allowing easy construction of clear and precise
queries, leveraging the existing classification scheme to enable and
disable those callsites.

Note that unlike other search terms, formats are implicitly floating
substring matches, without the need for explicit wildcards.

This makes no attempt at wider regex features, just the one we need.

TLDR: Using the anchor also means the []s are less helpful for
disamiguating the prefix from a random in-message occurrence, allowing
shorter prefixes.

Acked-by: <jbaron@akamai.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200719231058.1586423-17-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-07-24 17:00:10 +02:00
Jim Cromie
84da83a6ff dyndbg: combine flags & mask into a struct, simplify with it
flags & mask are used together everywhere, and are passed around
together between multiple functions; they belong together in a struct,
call that struct flag_settings.

Use struct flag_settings to rework 3 functions:
 - ddebug_exec_query - declares query and flag-settings,
   		     calls other 2, passing flags
 - ddebug_parse_flags - fills flag_settings and returns
 - ddebug_change - test all callsites against query,
   		   modify passing sites.

benefits:
 - bit-banging always needs flags & mask, best together.
 - simpler function signatures
 - 1 less parameter, less stack overhead

no functional changes

Acked-by: <jbaron@akamai.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200719231058.1586423-16-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-07-24 17:00:09 +02:00
Jim Cromie
14775b0496 dyndbg: accept query terms like file=bar and module=foo
Current code expects "keyword" "arg" as 2 words, space separated.
Change to also accept "keyword=arg" form as well, and drop !(nwords%2)
requirement.  Then in rest of function, use new keyword, arg variables
instead of word[i], word[i+1]

Acked-by: <jbaron@akamai.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200719231058.1586423-15-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-07-24 17:00:09 +02:00
Jim Cromie
aaebe329bf dyndbg: accept 'file foo.c:func1' and 'file foo.c:10-100'
Accept these additional query forms:

   echo "file $filestr +_" > control

       path/to/file.c:100	# as from control, column 1
       path/to/file.c:1-100	# or any legal line-range
       path/to/file.c:func_A	# as from an editor/browser
       path/to/file.c:drm_*	# wildcards still work
       path/to/file.c:*_foo	# lead wildcard too

1st 2 examples are treated as line-ranges, 3-5 are treated as func's

Doc these changes, and sprinkle in a few extra wild-card examples and
trailing # explanation texts.

Acked-by: <jbaron@akamai.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200719231058.1586423-14-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-07-24 17:00:09 +02:00
Jim Cromie
8037072d81 dyndbg: refactor parse_linerange out of ddebug_parse_query
Make the code-block reusable to later handle "file foo.c:101-200" etc.
This is a 99% code move, with reindent, function wrap&call, +pr_debug.

no functional changes.

Acked-by: <jbaron@akamai.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200719231058.1586423-13-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-07-24 17:00:09 +02:00
Jim Cromie
f62fc08fdc dyndbg: use gcc ?: to reduce word count
reduce word count via gcc ?: extension, no actual code change.

Acked-by: <jbaron@akamai.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200719231058.1586423-12-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-07-24 17:00:09 +02:00
Jim Cromie
47e9f5a823 dyndbg: make ddebug_tables list LIFO for add/remove_module
loadable modules are the last in on this list, and are the only
modules that could be removed.  ddebug_remove_module() searches from
head, but ddebug_add_module() uses list_add_tail().  Change it to
list_add() for a micro-optimization.

Acked-by: <jbaron@akamai.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200719231058.1586423-11-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-07-24 17:00:09 +02:00
Jim Cromie
9c9d0acbe2 dyndbg: prefer declarative init in caller, to memset in callee
ddebug_exec_query declares an auto var, and passes it to
ddebug_parse_query, which memsets it before using it.  Drop that
memset, instead initialize the variable in the caller; let the
compiler decide how to do it.

Acked-by: <jbaron@akamai.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200719231058.1586423-10-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-07-24 17:00:09 +02:00
Jim Cromie
0b8f96be9b dyndbg: fix pr_err with empty string
this pr_err attempts to print the string after the OP, but the string
has been parsed and chopped up, so looks empty.

Acked-by: <jbaron@akamai.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200719231058.1586423-9-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-07-24 17:00:08 +02:00
Jim Cromie
f678ce8cc3 dyndbg: fix a BUG_ON in ddebug_describe_flags
ddebug_describe_flags() currently fills a caller provided string buffer,
after testing its size (also passed) in a BUG_ON.  Fix this by
replacing them with a known-big-enough string buffer wrapped in a
struct, and passing that instead.

Also simplify ddebug_describe_flags() flags parameter from a struct to
a member in that struct, and hoist the member deref up to the caller.
This makes the function reusable (soon) where flags are unpacked.

Acked-by: <jbaron@akamai.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200719231058.1586423-8-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-07-24 17:00:08 +02:00
Jim Cromie
81d0c2c609 dyndbg: fix overcounting of ram used by dyndbg
during dyndbg init, verbose logging prints its ram overhead.  It
counted strlens of struct _ddebug's 4 string members, in all callsite
entries, which would be approximately correct if each had been
mallocd.  But they are pointers into shared .rodata; for example, all
10 kobject callsites have identical filename, module values.

Its best not to count that memory at all, since we cannot know they
were linked in because of CONFIG_DYNAMIC_DEBUG=y, and we want to
report a number that reflects what ram is saved by deconfiguring it.

Also fix wording and size under-reporting of the __dyndbg section.

Heres my overhead, on a virtme-run VM on a fedora-31 laptop:

  dynamic_debug:dynamic_debug_init: 260 modules, 2479 entries \
    and 10400 bytes in ddebug tables, 138824 bytes in __dyndbg section

Acked-by: <jbaron@akamai.com>
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200719231058.1586423-7-jim.cromie@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-07-24 17:00:08 +02:00