[PATCH v2 17/59] dyndbg-API: replace DECLARE_DYNDBG_CLASSMAP
Louis Chauvet
louis.chauvet at bootlin.com
Mon Mar 24 15:16:44 UTC 2025
Le 20/03/2025 à 19:51, Jim Cromie a écrit :
> DECLARE_DYNDBG_CLASSMAP() has a design error; its usage fails a basic
> K&R rule: "define once, refer many times".
>
> When DRM_USE_DYNAMIC_DEBUG=y, it is used across DRM core & drivers;
> each invocation allocates/inits the classmap understood by that
> module. 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, that
> caused incomplete initialization when modprobing drivers:
>
> 1st drm.ko loads, and dyndbg initializes its DRM.debug callsites, then
> a drm-driver loads, but too late for the DRM.debug enablement.
>
> So retire it, replace with 2 macros:
> DYNAMIC_DEBUG_CLASSMAP_DEFINE - invoked once from core - drm.ko
> DYNAMIC_DEBUG_CLASSMAP_USE - from all drm drivers and helpers.
>
> DYNAMIC_DEBUG_CLASSMAP_DEFINE: this reworks DECLARE_DYNDBG_CLASSMAP,
> by dropping the static qualifier on the classmap, and exporting it
> instead.
>
> DYNAMIC_DEBUG_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
> new section is scanned "differently"
>
> DECLARE_DYNDBG_CLASSMAP is preserved temporarily, to decouple DRM
> adaptation work and avoid compile-errs before its done. IOW, DRM gets
> these fixes when they commit the adopt-new-api patches.
>
> 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 module's classmaps
> . tells dyndbg about them, allowing >control
> . DYNAMIC_DEBUG_CLASSMAP_DEFINE creates section records.
> . we rename it to: __dyndbg_class_maps[]
>
> Then this patch adds __dyndbg_class_users[] section:
>
> . catalogs users of classmap definitions elsewhere
> . authorizes dyndbg to >control user's class'd prdbgs
> . DYNAMIC_DEBUG_CLASSMAP_USE() creates section records.
>
> 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()
> called ddebug_attach_module_classes()
> now calls ddebug_apply_class_maps() & ddebug_apply_class_users()
> these both call ddebug_apply_params().
>
> 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. DYNAMIC_DEBUG_CLASSMAP_DEFINE(.. DRM_UT_{CORE,KMS,...})
> 3. DYNAMIC_DEBUG_CLASSMAP_PARAM* (classmap)
> 4. DYNAMIC_DEBUG_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 DYNAMIC_DEBUG_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/Y, since this is disallowed by dependence).
>
> 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.
>
> Fixes: aad0214f3026 ("dyndbg: add DECLARE_DYNDBG_CLASSMAP macro")
> cc: linux-doc at vger.kernel.org
> Signed-off-by: Jim Cromie <jim.cromie at gmail.com>
> ---
>
> v2 a. building 2 .ko's from 1 source file is weird; add a clear
> comment at the top to justify it (basically cloning)
> ln 138+ in commit-msg is insufficient.
>
> b. retire "DYNDBG_" name shortening b4 adding _CLASSMAP_* macros.
> c. s/dd_class/_ddebug_class/
> d. s/\bddebug\b/_$1/g in header: chgs 1 struct and UNIQUE_ID bases
>
> v1.9 - 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
>
> v1.8 - split drm parts to separate commits.
> preserve DECLARE_DYNDBG_CLASSMAP to decouple DRM, no flag day.
> fixup block comment
>
> v1.7 - 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 almost
> always "type:DISJOINT_BITS". And drop ddebug_classmap_typenames,
> which is now unused.
>
> [root at 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
>
> fixup-test-submod
>
> fixup-test
> ---
> MAINTAINERS | 2 +-
> include/asm-generic/vmlinux.lds.h | 1 +
> include/linux/dynamic_debug.h | 107 +++++++++++++++++---
> kernel/module/main.c | 3 +
> lib/Kconfig.debug | 24 ++++-
> lib/Makefile | 3 +
> lib/dynamic_debug.c | 157 ++++++++++++++++++++++++------
> lib/test_dynamic_debug.c | 132 ++++++++++++++++++-------
> lib/test_dynamic_debug_submod.c | 14 +++
> 9 files changed, 354 insertions(+), 89 deletions(-)
> create mode 100644 lib/test_dynamic_debug_submod.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index c9763412a508..f98aec07a46d 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -8136,7 +8136,7 @@ M: Jim Cromie <jim.cromie at gmail.com>
> 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 at nvidia.com>
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index f834ad1fb8c4..fa382caf2ae2 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -367,6 +367,7 @@ defined(CONFIG_AUTOFDO_CLANG) || defined(CONFIG_PROPELLER_CLANG)
> /* implement dynamic printk debug */ \
> . = ALIGN(8); \
> BOUNDED_SECTION_BY(__dyndbg_class_maps, ___dyndbg_class_maps) \
> + BOUNDED_SECTION_BY(__dyndbg_class_users, ___dyndbg_class_users) \
> BOUNDED_SECTION_BY(__dyndbg_descriptors, ___dyndbg_descs) \
> CODETAG_SECTIONS() \
> LIKELY_PROFILE() \
> diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
> index 9fb38d79216e..0e3e14ca4765 100644
> --- a/include/linux/dynamic_debug.h
> +++ b/include/linux/dynamic_debug.h
> @@ -73,9 +73,28 @@ enum ddebug_class_map_type {
> */
> };
>
> -struct ddebug_class_map {
> - struct module *mod;
> - const char *mod_name; /* needed for builtins */
> +/*
> + * 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 {
> + const struct module *mod; /* NULL for builtins */
> + const char *mod_name;
> const char **class_names;
> const int length;
> const int base; /* index of 1st .class_id, allows split/shared space */
> @@ -83,16 +102,39 @@ 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
> + * DYNAMIC_DEBUG_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 DYNAMIC_DEBUG_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_class_maps") _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 DYNAMIC_DEBUG_CLASSMAP_DEFINE by the lack of the
> + * extern/EXPORT on the struct init, and cascading thinkos.
> */
> #define DECLARE_DYNDBG_CLASSMAP(_var, _maptype, _base, ...) \
> static const char *_var##_classnames[] = { __VA_ARGS__ }; \
> - static struct ddebug_class_map __aligned(8) __used \
> - __section("__dyndbg_classes") _var = { \
> + static struct _ddebug_class_map __aligned(8) __used \
> + __section("__dyndbg_class_maps") _var = { \
> .mod = THIS_MODULE, \
> .mod_name = KBUILD_MODNAME, \
> .base = _base, \
> @@ -101,31 +143,64 @@ struct ddebug_class_map {
> .class_names = _var##_classnames, \
> }
>
> +struct _ddebug_class_user {
> + char *mod_name;
> + struct _ddebug_class_map *map;
> +};
> +
> +/**
> + * DYNAMIC_DEBUG_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 DYNAMIC_DEBUG_CLASSMAP_USE(_var) \
> + DYNAMIC_DEBUG_CLASSMAP_USE_(_var, __UNIQUE_ID(_ddebug_class_user))
> +#define DYNAMIC_DEBUG_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), \
> + }
> +
> /*
> - * @_ddebug_info: gathers module/builtin dyndbg_* __sections together.
> + * @_ddebug_info: gathers module/builtin __dyndbg_<T> __sections
> + * together, each is a vector: a struct { <T> *addr, int len }.
> + *
> * For builtins, it is used as a cursor, with the inner structs
> - * marking sub-vectors of the builtin __sections in DATA.
> + * marking sub-vectors of the builtin __sections in DATA_DATA
> */
> struct _ddebug_descs {
> struct _ddebug *start;
> int len;
> } __packed;
> +
> struct _ddebug_class_maps {
> - struct ddebug_class_map *start;
> + struct _ddebug_class_map *start;
> int len;
> } __packed;
> +
> +struct _ddebug_class_users {
> + struct _ddebug_class_user *start;
> + int len;
> +} __packed;
> +
> struct _ddebug_info {
> struct _ddebug_descs descs;
> struct _ddebug_class_maps maps;
> + struct _ddebug_class_users users;
> } __packed;
>
> -struct ddebug_class_param {
> +struct _ddebug_class_param {
> union {
> unsigned long *bits;
> unsigned long *lvl;
> };
> char flags[8];
> - const struct ddebug_class_map *map;
> + const struct _ddebug_class_map *map;
> };
>
> /*
> @@ -217,7 +292,7 @@ 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); \
> if (DYNAMIC_DEBUG_BRANCH(id)) \
> func(&id, ##__VA_ARGS__); \
> } while (0)
> diff --git a/kernel/module/main.c b/kernel/module/main.c
> index b60f728e36ac..c203b0694f7e 100644
> --- a/kernel/module/main.c
> +++ b/kernel/module/main.c
> @@ -2627,6 +2627,9 @@ static int find_module_sections(struct module *mod, struct load_info *info)
> mod->dyndbg_info.maps.start = section_objs(info, "__dyndbg_class_maps",
> sizeof(*mod->dyndbg_info.maps.start),
> &mod->dyndbg_info.maps.len);
> + mod->dyndbg_info.users.start = section_objs(info, "__dyndbg_class_users",
> + sizeof(*mod->dyndbg_info.users.start),
> + &mod->dyndbg_info.users.len);
> #endif
>
> return 0;
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index 35796c290ca3..91a75f724c1a 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -2905,12 +2905,26 @@ 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 d5cfc7afbbb8..2c344138d990 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
>
> @@ -226,6 +227,8 @@ 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 5df9cc732290..aebafa1be06a 100644
> --- a/lib/dynamic_debug.c
> +++ b/lib/dynamic_debug.c
> @@ -29,6 +29,7 @@
> #include <linux/string_helpers.h>
> #include <linux/uaccess.h>
> #include <linux/dynamic_debug.h>
> +
> #include <linux/debugfs.h>
> #include <linux/slab.h>
> #include <linux/jump_label.h>
> @@ -41,8 +42,10 @@
>
> extern struct _ddebug __start___dyndbg_descs[];
> extern struct _ddebug __stop___dyndbg_descs[];
> -extern struct ddebug_class_map __start___dyndbg_class_maps[];
> -extern struct ddebug_class_map __stop___dyndbg_class_maps[];
> +extern struct _ddebug_class_map __start___dyndbg_class_maps[];
> +extern struct _ddebug_class_map __stop___dyndbg_class_maps[];
> +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;
> @@ -167,23 +170,28 @@ static void vpr_info_dq(const struct ddebug_query *query, const char *msg)
> _dt->info.users.len); \
> })
>
> -#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)
> +static int ddebug_find_valid_class(struct ddebug_table const *dt, const char *class_string)
> {
> - struct ddebug_class_map *map;
> + struct _ddebug_class_map *map;
> + struct _ddebug_class_user *cli;
> int i, idx;
>
> for_subvec(i, map, &dt->info, maps) {
> 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_subvec(i, cli, &dt->info, users) {
> + 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;
> }
>
> /*
> @@ -192,16 +200,14 @@ 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);
> @@ -213,8 +219,8 @@ 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 */
> @@ -578,7 +584,7 @@ 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)
> {
> @@ -615,14 +621,14 @@ static int ddebug_exec_queries(char *query, const char *modname)
> }
>
> /* apply a new class-param setting */
> -static int ddebug_apply_class_bitmap(const struct ddebug_class_param *dcp,
> +static int ddebug_apply_class_bitmap(const struct _ddebug_class_param *dcp,
> const unsigned long *new_bits,
> const unsigned long old_bits,
> const char *query_modname)
> {
> #define QUERY_SIZE 128
> char query[QUERY_SIZE];
> - const struct ddebug_class_map *map = dcp->map;
> + const struct _ddebug_class_map *map = dcp->map;
> int matches = 0;
> int bi, ct;
>
> @@ -659,8 +665,8 @@ static int param_set_dyndbg_module_classes(const char *instr,
> const struct kernel_param *kp,
> const char *modnm)
> {
> - const struct ddebug_class_param *dcp = kp->arg;
> - const struct ddebug_class_map *map = dcp->map;
> + const struct _ddebug_class_param *dcp = kp->arg;
> + const struct _ddebug_class_map *map = dcp->map;
> unsigned long inrep, new_bits, old_bits;
> int rc, totct = 0;
> char *nl;
> @@ -709,7 +715,7 @@ static int param_set_dyndbg_module_classes(const char *instr,
> /**
> * param_set_dyndbg_classes - classmap kparam setter
> * @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 all class'd pr_debugs in the classmap. For LEVEL
> * map-types, enforce * relative levels by bitpos.
> @@ -735,8 +741,8 @@ EXPORT_SYMBOL(param_set_dyndbg_classes);
> */
> int param_get_dyndbg_classes(char *buffer, const struct kernel_param *kp)
> {
> - const struct ddebug_class_param *dcp = kp->arg;
> - const struct ddebug_class_map *map = dcp->map;
> + const struct _ddebug_class_param *dcp = kp->arg;
> + const struct _ddebug_class_map *map = dcp->map;
>
> switch (map->map_type) {
> case DD_CLASS_TYPE_DISJOINT_BITS:
> @@ -746,6 +752,7 @@ int param_get_dyndbg_classes(char *buffer, const struct kernel_param *kp)
> default:
> return -1;
> }
> + return 0;
> }
> EXPORT_SYMBOL(param_get_dyndbg_classes);
>
> @@ -1067,13 +1074,18 @@ 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;
> + struct _ddebug_class_map *map;
> + struct _ddebug_class_user *cli;
> int i;
>
> for_subvec(i, map, &dt->info, maps)
> if (class_in_range(dp->class_id, map))
> return map->class_names[dp->class_id - map->base];
>
> + for_subvec(i, cli, &dt->info, users)
> + if (class_in_range(dp->class_id, cli->map))
> + return cli->map->class_names[dp->class_id - cli->map->base];
> +
> return NULL;
> }
>
> @@ -1154,9 +1166,85 @@ 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)
> {
> - vpr_info("module:%s attached %d classes\n", dt->mod_name, dt->info.maps.len);
> + 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);
> + }
> +}
> +
> +static void ddebug_apply_class_maps(struct ddebug_table *dt)
> +{
> + struct _ddebug_class_map *cm;
> + int i;
> +
> + for_subvec(i, cm, &dt->info, maps)
> + ddebug_apply_params(cm, cm->mod_name);
> +
> + vpr_dt_info(dt, "attached %d classmaps to module: %s ", i, cm->mod_name);
> +}
> +
> +static void ddebug_apply_class_users(struct ddebug_table *dt)
> +{
> + struct _ddebug_class_user *cli;
> + int i;
> +
> + for_subvec(i, cli, &dt->info, users)
> + ddebug_apply_params(cli->map, cli->mod_name);
> +
> + vpr_dt_info(dt, "attached %d class-users to module: %s ", i, cli->mod_name);
> }
>
> /*
> @@ -1191,7 +1279,8 @@ 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_class_map *cm;
> + struct _ddebug_class_map *cm;
> + struct _ddebug_class_user *cli;
> int i;
>
> if (!di->descs.len)
> @@ -1221,14 +1310,18 @@ static int ddebug_add_module(struct _ddebug_info *di, const char *modname)
> * start,len of the vectors by mod_name, save to dt.
> */
> dd_mark_vector_subrange(i, dt, cm, di, maps);
> + dd_mark_vector_subrange(i, dt, cli, di, users);
>
> - if (di->maps.len)
> - ddebug_attach_module_classes(dt, di);
> + if (dt->info.maps.len)
> + ddebug_apply_class_maps(dt);
>
> mutex_lock(&ddebug_lock);
> list_add_tail(&dt->link, &ddebug_tables);
> mutex_unlock(&ddebug_lock);
>
> + if (dt->info.users.len)
> + ddebug_apply_class_users(dt);
> +
> vpr_info("%3u debug prints in module %s\n", di->descs.len, modname);
> return 0;
> }
> @@ -1378,8 +1471,10 @@ static int __init dynamic_debug_init(void)
> struct _ddebug_info di = {
> .descs.start = __start___dyndbg_descs,
> .maps.start = __start___dyndbg_class_maps,
> + .users.start = __start___dyndbg_class_users,
> .descs.len = __stop___dyndbg_descs - __start___dyndbg_descs,
> .maps.len = __stop___dyndbg_class_maps - __start___dyndbg_class_maps,
> + .users.len = __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..1070107f74f1 100644
> --- a/lib/test_dynamic_debug.c
> +++ b/lib/test_dynamic_debug.c
> @@ -6,11 +6,30 @@
> * Jim Cromie <jim.cromie at gmail.com>
> */
>
> -#define pr_fmt(fmt) "test_dd: " fmt
> +/*
> + * This file is built 2x, also making test_dynamic_debug_submod.ko,
> + * whose 2-line src file #includes this file. This gives us a _submod
> + * clone with identical pr_debugs, without further maintenance.
> + *
> + * If things are working properly, they should operate identically
> + * when printed or adjusted by >control. This eases visual perusal of
> + * the logs, and simplifies testing, by easing the proper accounting
> + * of expectations.
> + *
> + * It also puts both halves of the subsystem _DEFINE & _USE use case
> + * together, and integrates the common ENUM providing both class_ids
> + * and class-names to both _DEFINErs and _USERs. I think this makes
> + * the usage clearer.
> + */
> +#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 +48,39 @@ 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 DYNAMIC_DEBUG_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 DYNAMIC_DEBUG_CLASSMAP_PARAM(_model, _flags) \
> + DYNAMIC_DEBUG_CLASSMAP_PARAM_(_model, _flags, ~0)
> +#else
> +#define DYNAMIC_DEBUG_CLASSMAP_PARAM(_model, _flags) \
> + DYNAMIC_DEBUG_CLASSMAP_PARAM_(_model, _flags, 0)
> +#endif
> +
> +/*
> + * Demonstrate/test DISJOINT & LEVEL typed classmaps with a sys-param.
> + *
> + * To comport with DRM debug-category (an int), classmaps map names to
> + * ids (also an int). So a classmap starts with an enum; DRM has enum
> + * debug_category: with DRM_UT_<CORE,DRIVER,KMS,etc>. We use the enum
> + * values as class-ids, and stringified enum-symbols as classnames.
> + *
> + * Modules with multiple CLASSMAPS must have enums with distinct
> + * value-ranges, as arranged below with explicit enum_sym = X inits.
> + * To clarify this sharing, declare the 2 enums now, for the 2
> + * different classmap types
> + */
>
> /* numeric input, independent bits */
> enum cat_disjoint_bits {
> @@ -60,26 +94,51 @@ 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);
> +
> +/* numeric verbosity, V2 > V1 related. V0 is > D2_DRM_RES */
s/D2_DRM_RES/D2_DRMRES/
> +enum cat_level_num { V0 = 16, V1, V2, V3, V4, V5, V6, V7 };
> +
> +/* recapitulate DRM's multi-classmap setup */
> +#if !defined(TEST_DYNAMIC_DEBUG_SUBMOD)
> +/*
> + * 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.
> + */
> +DYNAMIC_DEBUG_CLASSMAP_DEFINE(map_disjoint_bits, DD_CLASS_TYPE_DISJOINT_BITS,
> + D2_CORE,
> + "D2_CORE",
> + "D2_DRIVER",
> + "D2_KMS",
> + "D2_PRIME",
> + "D2_ATOMIC",
> + "D2_VBL",
> + "D2_STATE",
> + "D2_LEASE",
> + "D2_DP",
> + "D2_DRMRES");
> +
> +DYNAMIC_DEBUG_CLASSMAP_DEFINE(map_level_num, DD_CLASS_TYPE_LEVEL_NUM,
> + V0, "V0", "V1", "V2", "V3", "V4", "V5", "V6", "V7");
> +
> +/*
> + * now add the sysfs-params
> + */
> +
> +DYNAMIC_DEBUG_CLASSMAP_PARAM(disjoint_bits, p);
> +DYNAMIC_DEBUG_CLASSMAP_PARAM(level_num, p);
> +
> +#else /* TEST_DYNAMIC_DEBUG_SUBMOD */
> +
> +/*
> + * in submod/drm-drivers, use the classmaps defined in top/parent
> + * module above.
> + */
> +
> +DYNAMIC_DEBUG_CLASSMAP_USE(map_disjoint_bits);
> +DYNAMIC_DEBUG_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 +174,7 @@ static void do_levels(void)
>
> static void do_prints(void)
> {
> + pr_debug("do_prints:\n");
> do_cats();
> do_levels();
> }
> diff --git a/lib/test_dynamic_debug_submod.c b/lib/test_dynamic_debug_submod.c
> new file mode 100644
> index 000000000000..672aabf40160
> --- /dev/null
> +++ b/lib/test_dynamic_debug_submod.c
> @@ -0,0 +1,14 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Kernel module for testing dynamic_debug
> + *
> + * Authors:
> + * Jim Cromie <jim.cromie at gmail.com>
> + */
> +
> +/*
> + * clone the parent, inherit all the properties, for consistency and
> + * simpler accounting in test expectations.
> + */
> +#define TEST_DYNAMIC_DEBUG_SUBMOD
> +#include "test_dynamic_debug.c"
--
Louis Chauvet, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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