hi Louis,
On Tue, Feb 25, 2025 at 7:16 AM Louis Chauvet <louis.chauvet@xxxxxxxxxxx> wrote:
>
>
>
> Le 25/01/2025 à 07:45, Jim Cromie a écrit :
> > DECLARE_DYNDBG_CLASSMAP() has a design error; its usage fails a basic
> > K&R rule: "define once, refer many times".
> >
> > It is used across DRM core & drivers, each use re-defines the classmap
> > understood by that module; and all must match for the modules to
> > respond together when DRM.debug categories are enabled. This is
> > brittle; a maintenance foot-gun.
> >
> > Further, its culpable in the CONFIG_DRM_USE_DYNAMIC_DEBUG=Y
> > regression; its use in both core & drivers obfuscates the 2 roles.
> > So 1st drm.ko loads, and dyndbg initializes its DRM.debug callsites,
> > then a drm-driver loads, but too late - it missed the DRM.debug
> > enablement.
> >
> > So replace it with 2 macros:
> > DYNDBG_CLASSMAP_DEFINE - invoked once from core - drm.ko
> > DYNDBG_CLASSMAP_USE - from all drm drivers and helpers.
> >
> > DYNDBG_CLASSMAP_DEFINE: it just modifies DECLARE_DYNDBG_CLASSMAP,
> > dropping drop the static qualifier, and exports it instead.
> >
> > DYNDBG_CLASSMAP_USE: then refers to the exported var by name:
> > used from drivers, helper-mods
> > lets us drop the repetitive "classname" declarations
> > fixes 2nd-defn problem
> > creates a ddebug_class_user record in new __dyndbg_class_users section
> > this allows ddebug_add_module(etal) to handle users differently.
> >
> > DECLARE_DYNDBG_CLASSMAP is preserved temporarily, to decouple DRM
> > adaptation work and avoid compile-errs before its done. IOW, DRM gets
> > fixed when they commit the adopt-new-api patches, and remove the
> > BROKEN marking.
> >
> > The DEFINE,USE distinction, and the separate classmap-use record,
> > allows dyndbg to initialize the driver's & helper's DRM.debug
> > callsites separately after each is modprobed.
> >
> > Basically, the classmap init-scan is repeated for classmap-users.
> >
> > To review, dyndbg's existing __dyndbg_classes[] section does:
> >
> > . catalogs the classmaps defined by a module (or builtin modules)
> > . tells dyndbg the module has class'd prdbgs, allowing >control
> > . DYNDBG_CLASSMAP_DEFINE creates classmaps in this section.
> >
> > This patch adds __dyndbg_class_users[] section:
> >
> > . catalogs uses/references to the classmap definitions.
> > . authorizes dyndbg to >control those class'd prdbgs in ref'g module.
> > . DYNDBG_CLASSMAP_USE() creates classmap-user records in this new section.
> >
> > Now ddebug_add_module(etal) can handle classmap-uses similar to (and
> > after) classmaps; when a dependent module is loaded, if it has
> > classmap-uses (to a classmap-def in another module), that module's
> > kernel params are scanned to find if it has a kparam that is wired to
> > dyndbg's param-ops, and whose classmap is the one being ref'd.
> >
> > To support this, theres a few data/header changes:
> >
> > new struct ddebug_class_user
> > contains: user-module-name, &classmap-defn
> > it records drm-driver's use of a classmap in the section, allowing lookup
> >
> > struct ddebug_info gets 2 new fields for the new sections:
> > class_users, num_class_users.
> > set by dynamic_debug_init() for builtins.
> > or by kernel/module/main:load_info() for loadable modules.
> >
> > vmlinux.lds.h: new BOUNDED_SECTION for __dyndbg_class_users
> >
> > dynamic_debug.c has 2 changes in ddebug_add_module(), ddebug_change():
> >
> > ddebug_add_module() already calls ddebug_attach_module_classes()
> > to handle classmaps DEFINEd by a module, now it also calls
> > ddebug_attach_user_module_classes() to handle USEd classmaps. To
> > avoid this work when possible, 1st scan the module's descriptors and
> > count the number of class'd pr_debugs.
> >
> > ddebug_attach_user_module_classes() scans the module's class_users
> > section, follows the refs to the parent's classmap, and calls
> > ddebug_apply_params() on each. It also avoids work by checking the
> > module's class-ct.
> >
> > ddebug_apply_params(new fn):
> >
> > It scans module's/builtin kernel-params, calls ddebug_match_apply_kparam
> > for each to find any params/sysfs-nodes which may be wired to a classmap.
> >
> > ddebug_match_apply_kparam(new fn):
> >
> > 1st, it tests the kernel-param.ops is dyndbg's; this guarantees that
> > the attached arg is a struct ddebug_class_param, which has a ref to
> > the param's state, and to the classmap defining the param's handling.
> >
> > 2nd, it requires that the classmap ref'd by the kparam is the one
> > we're called for; modules can use many separate classmaps (as
> > test_dynamic_debug does).
> >
> > Then apply the "parent" kparam's setting to the dependent module,
> > using ddebug_apply_class_bitmap().
> >
> > ddebug_change(and callees) also gets adjustments:
> >
> > ddebug_find_valid_class(): This does a search over the module's
> > classmaps, looking for the class FOO echo'd to >control. So now it
> > searches over __dyndbg_class_users[] after __dyndbg_classes[].
> >
> > ddebug_class_name(): return class-names for defined AND used classes.
> >
> > test_dynamic_debug.c, test_dynamic_debug_submod.c:
> >
> > This demonstrates the 2 types of classmaps & sysfs-params, following
> > the 4-part recipe:
> >
> > 1. define an enum for the classmap: DRM.debug has DRM_UT_{CORE,KMS,...}
> > multiple classes must share 0-62 classid space.
> > 2. DYNDBG_CLASSMAP_DEFINE(.. DRM_UT_{CORE,KMS,...})
> > 3. DYNDBG_CLASSMAP_PARAM* (classmap)
> > 4. DYNDBG_CLASSMAP_USE()
> > by _submod only, skipping 2,3
> >
> > Move all the enum declarations together, to better explain how they
> > share the 0..62 class-id space available to a module (non-overlapping
> > subranges).
> >
> > reorg macros 2,3 by name. This gives a tabular format, making it easy
> > to see the pattern of repetition, and the points of change.
> >
> > And extend the test to replicate the 2-module (parent & dependent)
> > scenario which caused the CONFIG_DRM_USE_DYNAMIC_DEBUG=y regression
> > seen in drm & drivers.
> >
> > The _submod.c is a 2-line file: #define _SUBMOD, #include parent.
> >
> > This gives identical complements of prdbgs in parent & _submod, and
> > thus identical print behavior when all of: >control, >params, and
> > parent->_submod propagation are working correctly.
> >
> > It also puts all the parent/_submod declarations together in the same
> > source, with the new ifdef _SUBMOD block invoking DYNDBG_CLASSMAP_USE
> > for the 2 test-interfaces. I think this is clearer.
> >
> > These 2 modules are both tristate, allowing 3 super/sub combos: Y/Y,
> > Y/M, M/M (not N/N). Y/Y testing exposed a missing __align(8) in the
> > _METADATA macro, which M/M didn't see because the module-loader memory
> > placement constrains it instead.
> >
> > NB: this patch ignores a checkpatch do-while warning which is fixed by
> > a preceding commit, which would be wrong for declarative macros like
> > module_param_named() etc.
> >
> > Fixes: aad0214f3026 ("dyndbg: add DECLARE_DYNDBG_CLASSMAP macro")
> > Signed-off-by: Jim Cromie <jim.cromie@xxxxxxxxx>
> > ---
> > v9 - commit-msg tweaks
> > DRM:CHECK warnings on macros: add parens
> > extern DEFINEd _var, static classnames
> > change ddebug_class_user.user_mod_name to .mod_name
> > simplify ddebug_find_valid_class
> > improve vpr_cm_info msg format
> > wrap (base) in macro body
> > move __DYNDBG_CLASSMAP_CHECK above kdoc for DYNDBG_CLASSMAP_DEFINE
> >
> > v8 - split drm parts to separate commits.
> > preserve DECLARE_DYNDBG_CLASSMAP to decouple DRM, no flag day.
> > fixup block comment
> >
> > v7 - previous submission-blocking bug:
> >
> > missing __align(8) in DYNAMIC_DEBUG_DECLARE_METADATA on
> > ddebug_class_user caused corrupt records, but only for builtin
> > modules; module loader code probably pinned allocations to the right
> > alignment naturally, hiding the bug for typical builds.
> >
> > v6- get rid of WARN_ON_ONCE
> > v?- fix _var expanded 2x in macro
> >
> > dyndbg:
> >
> > This fn formerly returned the map which contained the class (thus
> > validating it), and as a side-effect set the class-id in an outvar.
> >
> > But the caller didn't use the map (after checking its not null), only
> > the valid class-id. So simplify the fn to return the class-id of the
> > validated classname, or -ENOENT when the queried classname is not
> > found.
> >
> > Convey more useful info in the debug-msg: print class-names[0,last],
> > and [base,+len] instead of the class-type printout, which is currently
> > always "type:DISJOINT_BITS". And drop ddebug_classmap_typenames,
> > which is now unused.
> >
> > [root@v6 b0-dd]# modprobe test_dynamic_debug_submod
> > [ 18.864962] dyndbg: loaded classmap: test_dynamic_debug [16..24] V0..V7
> > [ 18.865046] dyndbg: found kp:p_level_num =0x0
> > [ 18.865048] dyndbg: mapped to: test_dynamic_debug [16..24] V0..V7
> > [ 18.865164] dyndbg: p_level_num: lvl:0 bits:0x0
> > [ 18.865217] dyndbg: loaded classmap: test_dynamic_debug [0..10] D2_CORE..D2_DRMRES
> > [ 18.865297] dyndbg: found kp:p_disjoint_bits =0x0
> > [ 18.865298] dyndbg: mapped to: test_dynamic_debug [0..10] D2_CORE..D2_DRMRES
> > [ 18.865424] dyndbg: p_disjoint_bits: classbits: 0x0
> > [ 18.865472] dyndbg: module:test_dynamic_debug attached 2 classmaps
> > [ 18.865533] dyndbg: 23 debug prints in module test_dynamic_debug
> > [ 18.866558] dyndbg: loaded classmap: test_dynamic_debug_submod [16..24] V0..V7
> > [ 18.866698] dyndbg: found kp:p_level_num =0x0
> > [ 18.866699] dyndbg: mapped to: test_dynamic_debug_submod [16..24] V0..V7
> > [ 18.866865] dyndbg: p_level_num: lvl:0 bits:0x0
> > [ 18.866926] dyndbg: loaded classmap: test_dynamic_debug_submod [0..10] D2_CORE..D2_DRMRES
> > [ 18.867026] dyndbg: found kp:p_disjoint_bits =0x0
> > [ 18.867027] dyndbg: mapped to: test_dynamic_debug_submod [0..10] D2_CORE..D2_DRMRES
> > [ 18.867193] dyndbg: p_disjoint_bits: classbits: 0x0
> > [ 18.867255] dyndbg: module:test_dynamic_debug_submod attached 2 classmap uses
> > [ 18.867351] dyndbg: 23 debug prints in module test_dynamic_debug_submod
> > ---
> > MAINTAINERS | 2 +-
> > include/asm-generic/vmlinux.lds.h | 1 +
> > include/linux/dynamic_debug.h | 83 ++++++++++--
> > kernel/module/main.c | 3 +
> > lib/Kconfig.debug | 24 +++-
> > lib/Makefile | 3 +
> > lib/dynamic_debug.c | 203 ++++++++++++++++++++++++------
> > lib/test_dynamic_debug.c | 111 +++++++++++-----
> > lib/test_dynamic_debug_submod.c | 10 ++
>
> Hi Jim,
>
> While reading the files test_dynamic_debug*, I was wondering, they are
> more samples than tests. Does it make sense to move them in samples/?
> There is no need to do it in this series.
>
> > 9 files changed, 355 insertions(+), 85 deletions(-)
> > create mode 100644 lib/test_dynamic_debug_submod.c
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 0fa7c5728f1e..38afccb3b71e 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -8041,7 +8041,7 @@ M: Jim Cromie <jim.cromie@xxxxxxxxx>
> > S: Maintained
> > F: include/linux/dynamic_debug.h
> > F: lib/dynamic_debug.c
> > -F: lib/test_dynamic_debug.c
> > +F: lib/test_dynamic_debug*.c
> >
> > DYNAMIC INTERRUPT MODERATION
> > M: Tal Gilboa <talgi@xxxxxxxxxx>
> > diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> > index 54504013c749..eb93fd09832b 100644
> > --- a/include/asm-generic/vmlinux.lds.h
> > +++ b/include/asm-generic/vmlinux.lds.h
> > @@ -366,6 +366,7 @@ defined(CONFIG_AUTOFDO_CLANG) || defined(CONFIG_PROPELLER_CLANG)
> > /* implement dynamic printk debug */ \
> > . = ALIGN(8); \
> > BOUNDED_SECTION_BY(__dyndbg_classes, ___dyndbg_classes) \
> > + BOUNDED_SECTION_BY(__dyndbg_class_users, ___dyndbg_class_users) \
> > BOUNDED_SECTION_BY(__dyndbg, ___dyndbg) \
> > CODETAG_SECTIONS() \
> > LIKELY_PROFILE() \
> > diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
> > index c8102e89beb2..dc610a12b91c 100644
> > --- a/include/linux/dynamic_debug.h
> > +++ b/include/linux/dynamic_debug.h
> > @@ -71,9 +71,28 @@ enum ddebug_class_map_type {
> > */
> > };
> >
> > +/*
BTW, Im gonna refine this ...
> > + * dyndbg-classmaps are devised to support DRM.debug directly:
> > + * 10 enum-vals: DRM_UT_* define the categories
> > + * ~23 categorized *_dbg() macros, each passing a DRM_UT_* val as 1st arg
> > + * 2 macros below them: drm_dev_dbg, __drm_dbg
> > + * ~5000 calls to the categorized macros, across all of drivers/gpu/drm/
> > + *
> > + * When CONFIG_DRM_USE_DYNAMIC_DEBUG=y, the 2 low macros are redefined
> > + * to invoke _dynamic_func_call_cls(). This compiles the category
> > + * into each callsite's class_id field, where dyndbg can select on it
> > + * and alter a callsite's patch-state, avoiding repeated __drm_debug
> > + * checks.
> > + *
> > + * To make the callsites manageable from the >control file, authors
> > + * provide a "classmap" of names to class_ids in use by the module(s),
> > + * usually by stringifying the enum-vals. Modules with multiple
> > + * classmaps must arrange to share the 0..62 class_id space.
> > + */
> > +
> > struct ddebug_class_map {
> > - struct module *mod;
> > - const char *mod_name; /* needed for builtins */
> > + const struct module *mod; /* NULL for builtins */
> > + const char *mod_name;
>
> Is this change belongs to this patch? If not can you move this in a
> "cleanup" patch?
It belongs, insofar as the mod field is actually NULL checked to determine
builtin vs modular, mod_name is backup.
Also its more specific than "needed for builtins"
But, grumble, ya, the above was an existing test, not a new one.
OTOH - I guess Ive just written the cleanup commit msg :-)
>
> > const char **class_names;
> > const int length;
> > const int base; /* index of 1st .class_id, allows split/shared space */
> > @@ -81,11 +100,34 @@ struct ddebug_class_map {
> > };
> >
> > /**
> > - * DECLARE_DYNDBG_CLASSMAP - declare classnames known by a module
> > - * @_var: a struct ddebug_class_map, passed to module_param_cb
> > - * @_type: enum class_map_type, chooses bits/verbose, numeric/symbolic
> > - * @_base: offset of 1st class-name. splits .class_id space
> > - * @classes: class-names used to control class'd prdbgs
> > + * DYNDBG_CLASSMAP_DEFINE - define debug classes used by a module.
> > + * @_var: name of the classmap, exported for other modules coordinated use.
> > + * @_mapty: enum ddebug_class_map_type: 0:DISJOINT - independent, 1:LEVEL - v2>v1> + * @_base: reserve N classids starting at _base, to split 0..62
> classid space
> > + * @classes: names of the N classes.
> > + *
> > + * This tells dyndbg what class_ids the module is using: _base..+N, by
> > + * mapping names onto them. This qualifies "class NAME" >controls on
> > + * the defining module, ignoring unknown names.
> > + */
> > +#define DYNDBG_CLASSMAP_DEFINE(_var, _mapty, _base, ...) \
> > + static const char *_var##_classnames[] = { __VA_ARGS__ }; \
> > + extern struct ddebug_class_map _var; \
> > + struct ddebug_class_map __aligned(8) __used \
> > + __section("__dyndbg_classes") _var = { \
> > + .mod = THIS_MODULE, \
> > + .mod_name = KBUILD_MODNAME, \
> > + .base = (_base), \
> > + .map_type = (_mapty), \
> > + .length = ARRAY_SIZE(_var##_classnames), \
> > + .class_names = _var##_classnames, \
> > + }; \
> > + EXPORT_SYMBOL(_var)
> > +
> > +/*
> > + * XXX: keep this until DRM adapts to use the DEFINE/USE api, it
> > + * differs from DYNDBG_CLASSMAP_DEFINE by the static replacing the
> > + * extern/EXPORT on the struct init.
> > */
> > #define DECLARE_DYNDBG_CLASSMAP(_var, _maptype, _base, ...) \
> > static const char *_var##_classnames[] = { __VA_ARGS__ }; \
> > @@ -99,12 +141,37 @@ struct ddebug_class_map {
> > .class_names = _var##_classnames, \
> > }
> >
> > +struct ddebug_class_user {
> > + char *mod_name;
> > + struct ddebug_class_map *map;
> > +};
> > +
> > +/**
> > + * DYNDBG_CLASSMAP_USE - refer to a classmap, DEFINEd elsewhere.
> > + * @_var: name of the exported classmap var
> > + *
> > + * This tells dyndbg that the module has prdbgs with classids defined
> > + * in the named classmap. This qualifies "class NAME" >controls on
> > + * the user module, ignoring unknown names.
> > + */
> > +#define DYNDBG_CLASSMAP_USE(_var) \
> > + DYNDBG_CLASSMAP_USE_(_var, __UNIQUE_ID(ddebug_class_user))
> > +#define DYNDBG_CLASSMAP_USE_(_var, _uname) \
> > + extern struct ddebug_class_map _var; \
> > + static struct ddebug_class_user __aligned(8) __used \
> > + __section("__dyndbg_class_users") _uname = { \
> > + .mod_name = KBUILD_MODNAME, \
> > + .map = &(_var), \
> > + }
> > +
>
> I'm not sure I understand properly how __section works, but can we use
> multiple DYNDBG_CLASSMAP_USE in one module? Can we also use
> DYNDBG_CLASSMAP_DEFINE while also importing an other classmap
> DYNDBG_CLASSMAP_USE?
>
Yes, its supposed to work that way.
I havent tested that specific scenario (yet), but
a _USEr module, like test-dynamic-debug-submod,
could also _DEFINE its own, as long as it honors
the class-id mapping it is using and therefore sharing.
The on-modprobe conflict check should catch this condition.
And __section (ISTM) accumulates entries, typically static struct var
initializations.
AFAICT, scanning the sections is how these { scoped statics } are
often reachable.
For example, dd's _METADATA_ builds a { static _ddebug } for every pr_debug.
They all go into the __dyndbg section (renamed with _descriptors suffix soon),
in the order their respective definer objects are linked.
include/asm-generic/vmlinux.lds.h then places the __dyndbg_* sections
into DATA, along with lots of other freight, for the various
mechanisms they serve.
> If not, does it make sense to allow it (for example MFD devices can
> touch multiple subsystems)?
We have another use case !
Do you know your way around that case ?
Note that DEFINEr & USEr calls set up linkage dependencies,
As long as these are consistent with other module deps,
it should work.
>
> > /* encapsulate linker provided built-in (or module) dyndbg data */
> > struct _ddebug_info {
> > struct _ddebug *descs;
> > struct ddebug_class_map *classes;
> > + struct ddebug_class_user *class_users;
> > unsigned int num_descs;
> > unsigned int num_classes;
> > + unsigned int num_class_users;
> > };
> >
> > struct ddebug_class_param {
> > @@ -205,7 +272,7 @@ void __dynamic_ibdev_dbg(struct _ddebug *descriptor,
> > * (|_no_desc): former gets callsite descriptor as 1st arg (for prdbgs)
> > */
> > #define __dynamic_func_call_cls(id, cls, fmt, func, ...) do { \
> > - DEFINE_DYNAMIC_DEBUG_METADATA_CLS(id, cls, fmt); \
> > + DEFINE_DYNAMIC_DEBUG_METADATA_CLS((id), cls, fmt); \
>
> Can you move this in a "cleanup" patch?
>
> > if (DYNAMIC_DEBUG_BRANCH(id)) \
> > func(&id, ##__VA_ARGS__); \
> > } while (0)
> > diff --git a/kernel/module/main.c b/kernel/module/main.c
> > index 5399c182b3cb..c394a0c6e8c6 100644
> > --- a/kernel/module/main.c
> > +++ b/kernel/module/main.c
> > @@ -2546,6 +2546,9 @@ static int find_module_sections(struct module *mod, struct load_info *info)
> > mod->dyndbg_info.classes = section_objs(info, "__dyndbg_classes",
> > sizeof(*mod->dyndbg_info.classes),
> > &mod->dyndbg_info.num_classes);
> > + mod->dyndbg_info.class_users = section_objs(info, "__dyndbg_class_users",
> > + sizeof(*mod->dyndbg_info.class_users),
> > + &mod->dyndbg_info.num_class_users);
> > #endif
> >
> > return 0;
> > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> > index f3d723705879..933f69ef87f8 100644
> > --- a/lib/Kconfig.debug
> > +++ b/lib/Kconfig.debug
> > @@ -2884,12 +2884,26 @@ config TEST_STATIC_KEYS
> > If unsure, say N.
> >
> > config TEST_DYNAMIC_DEBUG
> > - tristate "Test DYNAMIC_DEBUG"
> > - depends on DYNAMIC_DEBUG
> > + tristate "Build test-dynamic-debug module"
> > + depends on DYNAMIC_DEBUG || DYNAMIC_DEBUG_CORE
> > help
> > - This module registers a tracer callback to count enabled
> > - pr_debugs in a 'do_debugging' function, then alters their
> > - enablements, calls the function, and compares counts.
> > + This module exercises/demonstrates dyndbg's classmap API, by
> > + creating 2 classes: a DISJOINT classmap (supporting DRM.debug)
> > + and a LEVELS/VERBOSE classmap (like verbose2 > verbose1).
> > +
> > + If unsure, say N.
> > +
> > +config TEST_DYNAMIC_DEBUG_SUBMOD
> > + tristate "Build test-dynamic-debug submodule"
> > + default m
> > + depends on DYNAMIC_DEBUG || DYNAMIC_DEBUG_CORE
> > + depends on TEST_DYNAMIC_DEBUG
> > + help
> > + This sub-module uses a classmap defined and exported by the
> > + parent module, recapitulating drm & driver's shared use of
> > + drm.debug to control enabled debug-categories.
> > + It is tristate, independent of parent, to allow testing all
> > + proper combinations of parent=y/m submod=y/m.
> >
> > If unsure, say N.
> >
> > diff --git a/lib/Makefile b/lib/Makefile
> > index a8155c972f02..7f66fc1c163d 100644
> > --- a/lib/Makefile
> > +++ b/lib/Makefile
> > @@ -84,6 +84,7 @@ obj-$(CONFIG_TEST_SORT) += test_sort.o
> > obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_keys.o
> > obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_key_base.o
> > obj-$(CONFIG_TEST_DYNAMIC_DEBUG) += test_dynamic_debug.o
> > +obj-$(CONFIG_TEST_DYNAMIC_DEBUG_SUBMOD) += test_dynamic_debug_submod.o
> > obj-$(CONFIG_TEST_PRINTF) += test_printf.o
> > obj-$(CONFIG_TEST_SCANF) += test_scanf.o
> >
> > @@ -228,6 +229,8 @@ obj-$(CONFIG_ARCH_NEED_CMPXCHG_1_EMU) += cmpxchg-emu.o
> > obj-$(CONFIG_DYNAMIC_DEBUG_CORE) += dynamic_debug.o
> > #ensure exported functions have prototypes
> > CFLAGS_dynamic_debug.o := -DDYNAMIC_DEBUG_MODULE
> > +CFLAGS_test_dynamic_debug.o := -DDYNAMIC_DEBUG_MODULE
> > +CFLAGS_test_dynamic_debug_submod.o := -DDYNAMIC_DEBUG_MODULE
> >
> > obj-$(CONFIG_SYMBOLIC_ERRNAME) += errname.o
> >
> > diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
> > index 094d6e62a9d1..6bca0c6727d4 100644
> > --- a/lib/dynamic_debug.c
> > +++ b/lib/dynamic_debug.c
> > @@ -43,13 +43,16 @@ extern struct _ddebug __start___dyndbg[];
> > extern struct _ddebug __stop___dyndbg[];
> > extern struct ddebug_class_map __start___dyndbg_classes[];
> > extern struct ddebug_class_map __stop___dyndbg_classes[];
> > +extern struct ddebug_class_user __start___dyndbg_class_users[];
> > +extern struct ddebug_class_user __stop___dyndbg_class_users[];
> >
> > struct ddebug_table {
> > struct list_head link;
> > const char *mod_name;
> > struct _ddebug *ddebugs;
> > struct ddebug_class_map *classes;
> > - unsigned int num_ddebugs, num_classes;
> > + struct ddebug_class_user *class_users;
> > + unsigned int num_ddebugs, num_classes, num_class_users;
> > };
> >
> > struct ddebug_query {
> > @@ -148,23 +151,35 @@ static void vpr_info_dq(const struct ddebug_query *query, const char *msg)
> > query->first_lineno, query->last_lineno, query->class_string);
> > }
> >
> > -#define __outvar /* filled by callee */
> > -static struct ddebug_class_map *ddebug_find_valid_class(struct ddebug_table const *dt,
> > - const char *class_string,
> > - __outvar int *class_id)
> > +#define vpr_dt_info(dt_p, msg_p, ...) ({ \
> > + struct ddebug_table const *_dt = dt_p; \
> > + v2pr_info(msg_p " module:%s nd:%d nc:%d nu:%d\n", ##__VA_ARGS__, \
> > + _dt->mod_name, _dt->num_ddebugs, _dt->num_classes, \
> > + _dt->num_class_users); \
> > + })
> > +
> > +static int ddebug_find_valid_class(struct ddebug_table const *dt, const char *class_string)
> > {
> > struct ddebug_class_map *map;
> > + struct ddebug_class_user *cli;
> > int i, idx;
> >
> > - for (map = dt->classes, i = 0; i < dt->num_classes; i++, map++) {
> > + for (i = 0, map = dt->classes; i < dt->num_classes; i++, map++) {
> > idx = match_string(map->class_names, map->length, class_string);
> > if (idx >= 0) {
> > - *class_id = idx + map->base;
> > - return map;
> > + vpr_dt_info(dt, "good-class: %s.%s ", map->mod_name, class_string);
> > + return idx + map->base;
> > }
> > }
> > - *class_id = -ENOENT;
> > - return NULL;
> > + for (i = 0, cli = dt->class_users; i < dt->num_class_users; i++, cli++) {
> > + idx = match_string(cli->map->class_names, cli->map->length, class_string);
> > + if (idx >= 0) {
> > + vpr_dt_info(dt, "class-ref: %s -> %s.%s ",
> > + cli->mod_name, cli->map->mod_name, class_string);
> > + return idx + cli->map->base;
> > + }
> > + }
> > + return -ENOENT;
> > }
> >
> > /*
> > @@ -173,16 +188,14 @@ static struct ddebug_class_map *ddebug_find_valid_class(struct ddebug_table cons
> > * callsites, normally the same as number of changes. If verbose,
> > * logs the changes. Takes ddebug_lock.
> > */
> > -static int ddebug_change(const struct ddebug_query *query,
> > - struct flag_settings *modifiers)
> > +static int ddebug_change(const struct ddebug_query *query, struct flag_settings *modifiers)
> > {
> > int i;
> > struct ddebug_table *dt;
> > unsigned int newflags;
> > unsigned int nfound = 0;
> > struct flagsbuf fbuf, nbuf;
> > - struct ddebug_class_map *map = NULL;
> > - int __outvar valid_class;
> > + int valid_class;
> >
> > /* search for matching ddebugs */
> > mutex_lock(&ddebug_lock);
> > @@ -194,8 +207,8 @@ static int ddebug_change(const struct ddebug_query *query,
> > continue;
> >
> > if (query->class_string) {
> > - map = ddebug_find_valid_class(dt, query->class_string, &valid_class);
> > - if (!map)
> > + valid_class = ddebug_find_valid_class(dt, query->class_string);
> > + if (valid_class < 0)
> > continue;
> > } else {
> > /* constrain query, do not touch class'd callsites */
> > @@ -559,7 +572,7 @@ static int ddebug_exec_query(char *query_string, const char *modname)
> >
> > /* handle multiple queries in query string, continue on error, return
> > last error or number of matching callsites. Module name is either
> > - in param (for boot arg) or perhaps in query string.
> > + in the modname arg (for boot args) or perhaps in query string.
> > */
> > static int ddebug_exec_queries(char *query, const char *modname)
> > {
> > @@ -688,12 +701,12 @@ static int param_set_dyndbg_module_classes(const char *instr,
> > }
> >
> > /**
> > - * param_set_dyndbg_classes - class FOO >control
> > + * param_set_dyndbg_classes - set all classes in a classmap
> > * @instr: string echo>d to sysfs, input depends on map_type
> > - * @kp: kp->arg has state: bits/lvl, map, map_type
> > + * @kp: kp->arg has state: bits/lvl, classmap, map_type
> > *
> > - * Enable/disable prdbgs by their class, as given in the arguments to
> > - * DECLARE_DYNDBG_CLASSMAP. For LEVEL map-types, enforce relative
> > + * For all classes in the classmap, enable/disable them per the input
> > + * (depending on map_type). For LEVEL map-types, enforce relative
> > * levels by bitpos.
> > *
> > * Returns: 0 or <0 if error.
> > @@ -1038,12 +1051,17 @@ static void *ddebug_proc_next(struct seq_file *m, void *p, loff_t *pos)
> > static const char *ddebug_class_name(struct ddebug_table *dt, struct _ddebug *dp)
> > {
> > struct ddebug_class_map *map = dt->classes;
> > + struct ddebug_class_user *cli = dt->class_users;
> > int i;
> >
> > for (i = 0; i < dt->num_classes; i++, map++)
> > if (class_in_range(dp->class_id, map))
> > return map->class_names[dp->class_id - map->base];
> >
> > + for (i = 0; i < dt->num_class_users; i++, cli++)
> > + if (class_in_range(dp->class_id, cli->map))
> > + return cli->map->class_names[dp->class_id - cli->map->base];
> > +
> > return NULL;
> > }
> >
> > @@ -1124,31 +1142,129 @@ static const struct proc_ops proc_fops = {
> > .proc_write = ddebug_proc_write
> > };
> >
> > -static void ddebug_attach_module_classes(struct ddebug_table *dt, struct _ddebug_info *di)
> > +#define vpr_cm_info(cm_p, msg_fmt, ...) ({ \
> > + struct ddebug_class_map const *_cm = cm_p; \
> > + v2pr_info(msg_fmt " %s [%d..%d] %s..%s\n", ##__VA_ARGS__, \
> > + _cm->mod_name, _cm->base, _cm->base + _cm->length, \
> > + _cm->class_names[0], _cm->class_names[_cm->length - 1]); \
> > + })
> > +
> > +static void ddebug_sync_classbits(const struct kernel_param *kp, const char *modname)
> > +{
> > + const struct ddebug_class_param *dcp = kp->arg;
> > +
> > + /* clamp initial bitvec, mask off hi-bits */
> > + if (*dcp->bits & ~CLASSMAP_BITMASK(dcp->map->length)) {
> > + *dcp->bits &= CLASSMAP_BITMASK(dcp->map->length);
> > + v2pr_info("preset classbits: %lx\n", *dcp->bits);
> > + }
> > + /* force class'd prdbgs (in USEr module) to match (DEFINEr module) class-param */
> > + ddebug_apply_class_bitmap(dcp, dcp->bits, ~0, modname);
> > + ddebug_apply_class_bitmap(dcp, dcp->bits, 0, modname);
> > +}
> > +
> > +static void ddebug_match_apply_kparam(const struct kernel_param *kp,
> > + const struct ddebug_class_map *map,
> > + const char *modnm)
> > +{
> > + struct ddebug_class_param *dcp;
> > +
> > + if (kp->ops != ¶m_ops_dyndbg_classes)
> > + return;
> > +
> > + dcp = (struct ddebug_class_param *)kp->arg;
> > +
> > + if (map == dcp->map) {
> > + v2pr_info(" kp:%s.%s =0x%lx", modnm, kp->name, *dcp->bits);
> > + vpr_cm_info(map, " %s mapped to: ", modnm);
> > + ddebug_sync_classbits(kp, modnm);
> > + }
> > +}
> > +
> > +static void ddebug_apply_params(const struct ddebug_class_map *cm, const char *modnm)
> > +{
> > + const struct kernel_param *kp;
> > +#if IS_ENABLED(CONFIG_MODULES)
> > + int i;
> > +
> > + if (cm->mod) {
> > + vpr_cm_info(cm, "loaded classmap: %s", modnm);
> > + /* ifdef protects the cm->mod->kp deref */
> > + for (i = 0, kp = cm->mod->kp; i < cm->mod->num_kp; i++, kp++)
> > + ddebug_match_apply_kparam(kp, cm, modnm);
> > + }
> > +#endif
> > + if (!cm->mod) {
> > + vpr_cm_info(cm, "builtin classmap: %s", modnm);
> > + for (kp = __start___param; kp < __stop___param; kp++)
> > + ddebug_match_apply_kparam(kp, cm, modnm);
> > + }
> > +}
> > +
> > +/*
> > + * Find this module's classmaps in a sub/whole-range of the builtin/
> > + * modular classmap vector/section. Save the start and length of the
> > + * subrange at its edges.
> > + */
> > +static void ddebug_attach_module_classes(struct ddebug_table *dt,
> > + const struct _ddebug_info *di)
> > {
> > struct ddebug_class_map *cm;
> > int i, nc = 0;
> >
> > - /*
> > - * Find this module's classmaps in a subrange/wholerange of
> > - * the builtin/modular classmap vector/section. Save the start
> > - * and length of the subrange at its edges.
> > - */
> > - for (cm = di->classes, i = 0; i < di->num_classes; i++, cm++) {
> > -
> > + for (i = 0, cm = di->classes; i < di->num_classes; i++, cm++) {
> > if (!strcmp(cm->mod_name, dt->mod_name)) {
> > - if (!nc) {
> > - v2pr_info("start subrange, class[%d]: module:%s base:%d len:%d ty:%d\n",
> > - i, cm->mod_name, cm->base, cm->length, cm->map_type);
> > + vpr_cm_info(cm, "classes[%d]:", i);
> > + if (!nc++)
> > dt->classes = cm;
> > - }
> > - nc++;
> > }
> > }
> > - if (nc) {
> > - dt->num_classes = nc;
> > - vpr_info("module:%s attached %d classes\n", dt->mod_name, nc);
> > + if (!nc)
> > + return;
> > +
> > + vpr_info("module:%s attached %d classes\n", dt->mod_name, nc);
> > + dt->num_classes = nc;
> > +
> > + for (i = 0, cm = dt->classes; i < dt->num_classes; i++, cm++)
> > + ddebug_apply_params(cm, cm->mod_name);
> > +}
> > +
> > +/*
> > + * propagates class-params thru their classmaps to class-users. this
> > + * means a query against the dt/module, which means it must be on the
> > + * list to be seen by ddebug_change.
> > + */
> > +static void ddebug_attach_user_module_classes(struct ddebug_table *dt,
> > + const struct _ddebug_info *di)
> > +{
> > + struct ddebug_class_user *cli;
> > + int i, nc = 0;
> > +
> > + /*
> > + * For builtins: scan the array, find start/length of this
> > + * module's refs, save to dt. For loadables, this is the
> > + * whole array.
> > + */
> > + for (i = 0, cli = di->class_users; i < di->num_class_users; i++, cli++) {
> > + if (WARN_ON_ONCE(!cli || !cli->map || !cli->mod_name))
> > + continue;
> > + if (!strcmp(cli->mod_name, dt->mod_name)) {
> > + vpr_cm_info(cli->map, "class_ref[%d] %s -> %s", i,
> > + cli->mod_name, cli->map->mod_name);
> > + if (!nc++)
> > + dt->class_users = cli;
> > + }
> > }
> > + if (!nc)
> > + return;
> > +
> > + dt->num_class_users = nc;
> > +
> > + /* now iterate dt */
> > + for (i = 0, cli = dt->class_users; i < dt->num_class_users; i++, cli++)
> > + ddebug_apply_params(cli->map, cli->mod_name);
> > +
> > + vpr_dt_info(dt, "attach-client-module: ");
> > }
> >
> > /*
> > @@ -1158,6 +1274,8 @@ static void ddebug_attach_module_classes(struct ddebug_table *dt, struct _ddebug
> > static int ddebug_add_module(struct _ddebug_info *di, const char *modname)
> > {
> > struct ddebug_table *dt;
> > + struct _ddebug *iter;
> > + int i, class_ct = 0;
> >
> > if (!di->num_descs)
> > return 0;
> > @@ -1181,13 +1299,20 @@ static int ddebug_add_module(struct _ddebug_info *di, const char *modname)
> >
> > INIT_LIST_HEAD(&dt->link);
> >
> > - if (di->classes && di->num_classes)
> > + for (i = 0, iter = di->descs; i < di->num_descs; i++, iter++)
> > + if (iter->class_id != _DPRINTK_CLASS_DFLT)
> > + class_ct++;
> > +
> > + if (class_ct && di->num_classes)
> > ddebug_attach_module_classes(dt, di);
> >
> > mutex_lock(&ddebug_lock);
> > list_add_tail(&dt->link, &ddebug_tables);
> > mutex_unlock(&ddebug_lock);
> >
> > + if (class_ct && di->num_class_users)
> > + ddebug_attach_user_module_classes(dt, di);
> > +
> > vpr_info("%3u debug prints in module %s\n", di->num_descs, modname);
> > return 0;
> > }
> > @@ -1337,8 +1462,10 @@ static int __init dynamic_debug_init(void)
> > struct _ddebug_info di = {
> > .descs = __start___dyndbg,
> > .classes = __start___dyndbg_classes,
> > + .class_users = __start___dyndbg_class_users,
> > .num_descs = __stop___dyndbg - __start___dyndbg,
> > .num_classes = __stop___dyndbg_classes - __start___dyndbg_classes,
> > + .num_class_users = __stop___dyndbg_class_users - __start___dyndbg_class_users,
> > };
> >
> > #ifdef CONFIG_MODULES
> > diff --git a/lib/test_dynamic_debug.c b/lib/test_dynamic_debug.c
> > index 74d183ebf3e0..1838f62738c4 100644
> > --- a/lib/test_dynamic_debug.c
> > +++ b/lib/test_dynamic_debug.c
> > @@ -6,11 +6,15 @@
> > * Jim Cromie <jim.cromie@xxxxxxxxx>
> > */
> >
> > -#define pr_fmt(fmt) "test_dd: " fmt
> > +#if defined(TEST_DYNAMIC_DEBUG_SUBMOD)
> > + #define pr_fmt(fmt) "test_dd_submod: " fmt
> > +#else
> > + #define pr_fmt(fmt) "test_dd: " fmt
> > +#endif
> >
> > #include <linux/module.h>
> >
> > -/* run tests by reading or writing sysfs node: do_prints */
> > +/* re-gen output by reading or writing sysfs node: do_prints */
> >
> > static void do_prints(void); /* device under test */
> > static int param_set_do_prints(const char *instr, const struct kernel_param *kp)
> > @@ -29,24 +33,39 @@ static const struct kernel_param_ops param_ops_do_prints = {
> > };
> > module_param_cb(do_prints, ¶m_ops_do_prints, NULL, 0600);
> >
> > -/*
> > - * Using the CLASSMAP api:
> > - * - classmaps must have corresponding enum
> > - * - enum symbols must match/correlate with class-name strings in the map.
> > - * - base must equal enum's 1st value
> > - * - multiple maps must set their base to share the 0-30 class_id space !!
> > - * (build-bug-on tips welcome)
> > - * Additionally, here:
> > - * - tie together sysname, mapname, bitsname, flagsname
> > - */
> > -#define DD_SYS_WRAP(_model, _flags) \
> > - static unsigned long bits_##_model; \
> > - static struct ddebug_class_param _flags##_model = { \
> > +#define CLASSMAP_BITMASK(width, base) (((1UL << (width)) - 1) << (base))
> > +
> > +/* sysfs param wrapper, proto-API */
> > +#define DYNDBG_CLASSMAP_PARAM_(_model, _flags, _init) \
> > + static unsigned long bits_##_model = _init; \
> > + static struct ddebug_class_param _flags##_##_model = { \
> > .bits = &bits_##_model, \
> > .flags = #_flags, \
> > .map = &map_##_model, \
> > }; \
> > - module_param_cb(_flags##_##_model, ¶m_ops_dyndbg_classes, &_flags##_model, 0600)
> > + module_param_cb(_flags##_##_model, ¶m_ops_dyndbg_classes, \
> > + &_flags##_##_model, 0600)
> > +#ifdef DEBUG
> > +#define DYNDBG_CLASSMAP_PARAM(_model, _flags) DYNDBG_CLASSMAP_PARAM_(_model, _flags, ~0)
> > +#else
> > +#define DYNDBG_CLASSMAP_PARAM(_model, _flags) DYNDBG_CLASSMAP_PARAM_(_model, _flags, 0)
> > +#endif
> > +
> > +/*
> > + * Demonstrate/test all 4 class-typed classmaps with a sys-param.
> > + *
> > + * Each is 3 part: client-enum decl, _DEFINE, _PARAM.
> > + * Declare them in blocks to show patterns of use (repetitions and
> > + * changes) within each.
> > + *
> > + * 1st, dyndbg expects a client-provided enum-type as source of
> > + * category/classid truth. DRM has DRM_UT_<CORE,DRIVER,KMS,etc>.
> > + *
> > + * Modules with multiple CLASSMAPS must have enums with distinct
> > + * value-ranges, arranged below with explicit enum_sym = X inits.
> > + *
> > + * Declare all 4 enums now, for different types
> > + */
> >
> > /* numeric input, independent bits */
> > enum cat_disjoint_bits {
> > @@ -60,26 +79,51 @@ enum cat_disjoint_bits {
> > D2_LEASE,
> > D2_DP,
> > D2_DRMRES };
> > -DECLARE_DYNDBG_CLASSMAP(map_disjoint_bits, DD_CLASS_TYPE_DISJOINT_BITS, 0,
> > - "D2_CORE",
> > - "D2_DRIVER",
> > - "D2_KMS",
> > - "D2_PRIME",
> > - "D2_ATOMIC",
> > - "D2_VBL",
> > - "D2_STATE",
> > - "D2_LEASE",
> > - "D2_DP",
> > - "D2_DRMRES");
> > -DD_SYS_WRAP(disjoint_bits, p);
> > -DD_SYS_WRAP(disjoint_bits, T);
> >
> > /* numeric verbosity, V2 > V1 related */
> > enum cat_level_num { V0 = 14, V1, V2, V3, V4, V5, V6, V7 };
> > -DECLARE_DYNDBG_CLASSMAP(map_level_num, DD_CLASS_TYPE_LEVEL_NUM, 14,
> > - "V0", "V1", "V2", "V3", "V4", "V5", "V6", "V7");
> > -DD_SYS_WRAP(level_num, p);
> > -DD_SYS_WRAP(level_num, T);
> > +
> > +/* recapitulate DRM's parent(drm.ko) <-- _submod(drivers,helpers) */
> > +#if !defined(TEST_DYNAMIC_DEBUG_SUBMOD)
>
> It was not clear at first read that the test_dynamic_debug.c code is
> used twice.
>
Yes, that was a miss. Now in big comment block at the top of both,
right before the pr-fmt mod-name shortening for the logs.
> What do you think about creating a third file "common" with
> do_prints/do_levels/... implementations and avoid this #if !defined?
>
I'd rather not. I think the multi-module usage is sufficiently interconnected
(common enum, parent side, clone side) that all-in-one presentation
helps to communicate this "linkage".
I hope the new comments clearly elucidate this. PLMK if not.
> > +/*
> > + * In single user, or parent / coordinator (drm.ko) modules, define
> > + * classmaps on the client enums above, and then declares the PARAMS
> > + * ref'g the classmaps. Each is exported.
> > + */
> > +DYNDBG_CLASSMAP_DEFINE(map_disjoint_bits, DD_CLASS_TYPE_DISJOINT_BITS,
>
> map_disjoint_bits is defined in both test_dynamic_debug.c and
> test_dynamic_debug_submodule.c, is it normal/required?
Its the enum : cat_disjoint_bits, that is defined for both.
the _DEFINE itself is right after the ifdef TEST_MOD_SUBMOD.
do you think it needs a better MOD_SUBMOD name ?
or an ifndef ?
>
> > + D2_CORE,
> > + "D2_CORE",
> > + "D2_DRIVER",
> > + "D2_KMS",
> > + "D2_PRIME",
> > + "D2_ATOMIC",
> > + "D2_VBL",
> > + "D2_STATE",
> > + "D2_LEASE",
> > + "D2_DP",
> > + "D2_DRMRES");
> > +
> > +DYNDBG_CLASSMAP_DEFINE(map_level_num, DD_CLASS_TYPE_LEVEL_NUM,
> > + V0, "V0", "V1", "V2", "V3", "V4", "V5", "V6", "V7");
> > +
> > +/*
> > + * now add the sysfs-params
> > + */
> > +
> > +DYNDBG_CLASSMAP_PARAM(disjoint_bits, p);
> > +DYNDBG_CLASSMAP_PARAM(level_num, p);
> > +
> > +#else /* TEST_DYNAMIC_DEBUG_SUBMOD */
> > +
> > +/*
> > + * in submod/drm-drivers, use the classmaps defined in top/parent
> > + * module above.
> > + */
> > +
> > +DYNDBG_CLASSMAP_USE(map_disjoint_bits);
> > +DYNDBG_CLASSMAP_USE(map_level_num);
> > +
> > +#endif
> >
> > /* stand-in for all pr_debug etc */
> > #define prdbg(SYM) __pr_debug_cls(SYM, #SYM " msg\n")
> > @@ -115,6 +159,7 @@ static void do_levels(void)
> >
> > static void do_prints(void)
> > {
> > + pr_debug("do_prints:\n");
> > do_cats();
> > do_levels();
>
> I just observed it, is the ordering of logs garanteed in
> /proc/dynamic_debug/control?
>
Yes. the fully ordered table/__section is pretty important.
If its not true for descriptors, its probably not true for class-maps
or users either
and the list-iter --> vector-block conversion a few commits ago isnt
solid either.
its also an explicit assumption under these commits
773beabbb8e8 dyndbg: reverse module.callsite walk in cat control
2ad556f70043 dyndbg: reverse module walk in cat control
All in all, I think something would have broken by now.
> When I run this test, I have this order:
>
> do_cats =_ "doing categories\n"
> [...]
> do_levels =_ "doing levels\n"
> [...]
> do_prints =_ "do_prints:\n"
> test_dynamic_debug_init =_ "init start\n"
> test_dynamic_debug_init =_ "init done\n"
> test_dynamic_debug_exit =_ "exited\n"
>
> Which is clearly not the code execution order.
Youre correct.
the control file reflects compile link order.
Im pretty sure the appearance of init 1st in control derives from init/builtin.a
being built 1st and/or linked 1st.
>
> > }
> > diff --git a/lib/test_dynamic_debug_submod.c b/lib/test_dynamic_debug_submod.c
> > new file mode 100644
> > index 000000000000..9a893402ce1a
> > --- /dev/null
> > +++ b/lib/test_dynamic_debug_submod.c
> > @@ -0,0 +1,10 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Kernel module for testing dynamic_debug
> > + *
> > + * Authors:
> > + * Jim Cromie <jim.cromie@xxxxxxxxx>
> > + */
> > +
> > +#define TEST_DYNAMIC_DEBUG_SUBMOD
> > +#include "test_dynamic_debug.c"
>
> --
> Louis Chauvet, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com
>
thanks again Lous,
Jim
