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Message-ID: <CAJfuBxzkDvABq=gBxwKOYO7Y=k-wwyTLH274pKLkpL1KZr3Bew@mail.gmail.com>
Date: Tue, 15 Apr 2025 13:38:20 -0600
From: jim.cromie@...il.com
To: Louis Chauvet <louis.chauvet@...tlin.com>
Cc: jbaron@...mai.com, gregkh@...uxfoundation.org, ukaszb@...omium.org,
linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
amd-gfx@...ts.freedesktop.org, intel-gvt-dev@...ts.freedesktop.org,
intel-gfx@...ts.freedesktop.org, daniel.vetter@...ll.ch,
tvrtko.ursulin@...ux.intel.com, jani.nikula@...el.com,
ville.syrjala@...ux.intel.com, linux-doc@...r.kernel.org
Subject: Re: [PATCH v3 17/54] dyndbg-API: replace DECLARE_DYNDBG_CLASSMAP
On Tue, Apr 15, 2025 at 4:01 AM Louis Chauvet <louis.chauvet@...tlin.com> wrote:
>
>
>
> Le 02/04/2025 à 19:41, 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@...r.kernel.org
> > Signed-off-by: Jim Cromie <jim.cromie@...il.com>
> > ---
> > v3-
> > undo 1.9 simplification of ddebug_find_valid_class()
> > ddebug_change needs map to see its controlling param
> > change internal callchains to pass di, not dt
> >
> > 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 return val
> > 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@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
> >
> > Signed-off-by: Jim Cromie <jim.cromie@...il.com>
> > ---
> > MAINTAINERS | 2 +-
> > include/asm-generic/vmlinux.lds.h | 1 +
> > include/linux/dynamic_debug.h | 93 +++++++++++++++++---
> > kernel/module/main.c | 3 +
> > lib/Kconfig.debug | 24 ++++--
> > lib/Makefile | 3 +
> > lib/dynamic_debug.c | 137 +++++++++++++++++++++++++++---
> > lib/test_dynamic_debug.c | 132 ++++++++++++++++++++--------
> > lib/test_dynamic_debug_submod.c | 14 +++
> > 9 files changed, 343 insertions(+), 66 deletions(-)
> > create mode 100644 lib/test_dynamic_debug_submod.c
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 00e94bec401e..1c5fcbd9e408 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -8139,7 +8139,7 @@ M: Jim Cromie <jim.cromie@...il.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@...dia.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 769f02456c8e..9af825c84e70 100644
> > --- a/include/linux/dynamic_debug.h
> > +++ b/include/linux/dynamic_debug.h
> > @@ -71,9 +71,28 @@ enum ddebug_class_map_type {
> > */
> > };
> >
> > +/*
> > + * 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;
> > 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
> > + * 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__ }; \
> > @@ -99,10 +141,35 @@ 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
>
> DATA_DATA? Is it a typo?
>
No, its the actual name of the macro in vmlinux.lds.h
include/asm-generic/vmlinux.lds.h
355:#define DATA_DATA \
1155: DATA_DATA \
I chose it thinking it was much more specific than just DATA
but it is also used repeatedly elsewhere (as part of symbol-names)
drivers/accel/habanalabs/include/gaudi2/asic_reg/dcore0_sync_mngr_objs_masks.h
42:#define DCORE0_SYNC_MNGR_OBJS_MON_PAY_DATA_DATA_SHIFT 0
43:#define DCORE0_SYNC_MNGR_OBJS_MON_PAY_DATA_DATA_MASK 0xFFFFFFFF
drivers/accel/habanalabs/include/goya/asic_reg/tpc0_eml_cfg_masks.h
245:#define TPC0_EML_CFG_DBG_SPDATA_DATA_SHIFT 0
246:#define TPC0_EML_CFG_DBG_SPDATA_DATA_MASK
0xFFFFFFFF
267:#define TPC0_EML_CFG_DBG_AXIHBWDATA_DATA_SHIFT 0
268:#define TPC0_EML_CFG_DBG_AXIHBWDATA_DATA_MASK
0xFFFFFFFF
285:#define TPC0_EML_CFG_DBG_AXILBWDATA_DATA_SHIFT 0
286:#define TPC0_EML_CFG_DBG_AXILBWDATA_DATA_MASK
0xFFFFFFFF
> With this confirmed:
> Reviewed-by: Louis Chauvet <louis.chauvet@...tlin.com>
>
> > */
> > struct _ddebug_descs {
> > struct _ddebug *start;
> > @@ -114,10 +181,16 @@ struct _ddebug_class_maps {
> > int len;
> > } __packed;
> >
> > +struct _ddebug_class_users {
> > + struct _ddebug_class_user *start;
> > + int len;
> > +} __packed;
> > +
> > struct _ddebug_info {
> > const char *mod_name;
> > struct _ddebug_descs descs;
> > struct _ddebug_class_maps maps;
> > + struct _ddebug_class_users users;
> > } __packed;
> >
> > struct _ddebug_class_param {
> > @@ -218,7 +291,7 @@ 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 a7e1dbb6ead0..53e261dbf81e 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>
> > @@ -43,6 +44,8 @@ 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_user __start___dyndbg_class_users[];
> > +extern struct _ddebug_class_user __stop___dyndbg_class_users[];
> >
> > struct ddebug_table {
> > struct list_head link;
> > @@ -159,20 +162,37 @@ static void vpr_info_dq(const struct ddebug_query *query, const char *msg)
> > query->first_lineno, query->last_lineno, query->class_string);
> > }
> >
> > -static struct _ddebug_class_map *ddebug_find_valid_class(struct ddebug_table const *dt,
> > - const char *class_string,
> > - int *class_id)
> > +#define vpr_di_info(di_p, msg_p, ...) ({ \
> > + struct _ddebug_info const *_di = di_p; \
> > + v2pr_info(msg_p " module:%s nd:%d nc:%d nu:%d\n", ##__VA_ARGS__, \
> > + _di->mod_name, _di->descs.len, _di->maps.len, \
> > + _di->users.len); \
> > + })
> > +
> > +static struct _ddebug_class_map *
> > +ddebug_find_valid_class(struct _ddebug_info const *di, const char *query_class, int *class_id)
> > {
> > 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);
> > + for_subvec(i, map, di, maps) {
> > + idx = match_string(map->class_names, map->length, query_class);
> > if (idx >= 0) {
> > + vpr_di_info(di, "good-class: %s.%s ", map->mod_name, query_class);
> > *class_id = idx + map->base;
> > return map;
> > }
> > }
> > + for_subvec(i, cli, di, users) {
> > + idx = match_string(cli->map->class_names, cli->map->length, query_class);
> > + if (idx >= 0) {
> > + vpr_di_info(di, "class-ref: %s -> %s.%s ",
> > + cli->mod_name, cli->map->mod_name, query_class);
> > + *class_id = idx + cli->map->base;
> > + return cli->map;
> > + }
> > + }
> > *class_id = -ENOENT;
> > return NULL;
> > }
> > @@ -183,8 +203,7 @@ static struct _ddebug_class_map *ddebug_find_valid_class(struct ddebug_table con
> > * 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;
> > @@ -204,7 +223,8 @@ 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);
> > + map = ddebug_find_valid_class(&dt->info, query->class_string,
> > + &valid_class);
> > if (!map)
> > continue;
> > } else {
> > @@ -569,7 +589,7 @@ 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)
> > {
> > @@ -700,7 +720,7 @@ 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.
> > @@ -737,6 +757,7 @@ int param_get_dyndbg_classes(char *buffer, const struct kernel_param *kp)
> > default:
> > return -1;
> > }
> > + return 0;
> > }
> > EXPORT_SYMBOL(param_get_dyndbg_classes);
> >
> > @@ -1049,12 +1070,17 @@ static void *ddebug_proc_next(struct seq_file *m, void *p, loff_t *pos)
> > static const char *ddebug_class_name(struct _ddebug_info *di, struct _ddebug *dp)
> > {
> > struct _ddebug_class_map *map;
> > + struct _ddebug_class_user *cli;
> > int i;
> >
> > for_subvec(i, map, di, maps)
> > if (class_in_range(dp->class_id, map))
> > return map->class_names[dp->class_id - map->base];
> >
> > + for_subvec(i, cli, di, users)
> > + if (class_in_range(dp->class_id, cli->map))
> > + return cli->map->class_names[dp->class_id - cli->map->base];
> > +
> > return NULL;
> > }
> >
> > @@ -1135,9 +1161,85 @@ 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 *mod_name)
> > +{
> > + 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", mod_name, kp->name, *dcp->bits);
> > + vpr_cm_info(map, " %s mapped to: ", mod_name);
> > + ddebug_sync_classbits(kp, mod_name);
> > + }
> > +}
> > +
> > +static void ddebug_apply_params(const struct _ddebug_class_map *cm, const char *mod_name)
> > +{
> > + const struct kernel_param *kp;
> > +#if IS_ENABLED(CONFIG_MODULES)
> > + int i;
> > +
> > + if (cm->mod) {
> > + vpr_cm_info(cm, "loaded classmap: %s", mod_name);
> > + /* 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, mod_name);
> > + }
> > +#endif
> > + if (!cm->mod) {
> > + vpr_cm_info(cm, "builtin classmap: %s", mod_name);
> > + for (kp = __start___param; kp < __stop___param; kp++)
> > + ddebug_match_apply_kparam(kp, cm, mod_name);
> > + }
> > +}
> > +
> > +static void ddebug_apply_class_maps(const struct _ddebug_info *di)
> > +{
> > + struct _ddebug_class_map *cm;
> > + int i;
> > +
> > + for_subvec(i, cm, di, maps)
> > + ddebug_apply_params(cm, cm->mod_name);
> > +
> > + vpr_di_info(di, "attached %d classmaps to module: %s ", i, cm->mod_name);
> > +}
> > +
> > +static void ddebug_apply_class_users(const struct _ddebug_info *di)
> > {
> > - vpr_info("module:%s attached %d classes\n", dt->info.mod_name, dt->info.maps.len);
> > + struct _ddebug_class_user *cli;
> > + int i;
> > +
> > + for_subvec(i, cli, di, users)
> > + ddebug_apply_params(cli->map, cli->mod_name);
> > +
> > + vpr_di_info(di, "attached %d class-users to module: %s ", i, cli->mod_name);
> > }
> >
> > /*
> > @@ -1173,6 +1275,7 @@ static int ddebug_add_module(struct _ddebug_info *di)
> > {
> > struct ddebug_table *dt;
> > struct _ddebug_class_map *cm;
> > + struct _ddebug_class_user *cli;
> > int i;
> >
> > if (!di->descs.len)
> > @@ -1196,14 +1299,18 @@ static int ddebug_add_module(struct _ddebug_info *di)
> > INIT_LIST_HEAD(&dt->link);
> >
> > 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->info);
> >
> > 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->info);
> > +
> > vpr_info("%3u debug prints in module %s\n", di->descs.len, di->mod_name);
> > return 0;
> > }
> > @@ -1354,8 +1461,10 @@ 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 9c3e53cd26bd..1070107f74f1 100644
> > --- a/lib/test_dynamic_debug.c
> > +++ b/lib/test_dynamic_debug.c
> > @@ -6,11 +6,30 @@
> > * Jim Cromie <jim.cromie@...il.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 */
> > +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@...il.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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