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[98.38.17.99]) by smtp.googlemail.com with ESMTPSA id 006d021491bc7-680a63c7fd1sm12254208eaf.8.2026.04.08.13.02.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 08 Apr 2026 13:02:42 -0700 (PDT) From: Jim Cromie To: linux-kernel@vger.kernel.org Cc: gregkh@linuxfoundation.org, jbaron@akamai.com, louis.chauvet@bootlin.com, Jim Cromie Subject: [PATCH v13 27/36] dyndbg: check DYNAMIC_DEBUG_CLASSMAP_{DEFINE,USE_} args at compile-time Date: Wed, 8 Apr 2026 14:02:02 -0600 Message-ID: <20260408200211.43821-28-jim.cromie@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260408200211.43821-1-jim.cromie@gmail.com> References: <20260408200211.43821-1-jim.cromie@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add __DYNAMIC_DEBUG_CLASSMAP_CHECK to implement the following arg-checks at compile-time: 0 <= _base < 63 class_names is not empty class_names[0] is a string (class_names.length + _base) < 63 dd-map-type is known value These compile-time checks will prevent several simple misuses, and will issue obvious errors if violated. 4 such examples are added to test_dynamic_debug_submod.ko, and will fail compilation if -DDD_MACRO_ARGCHECK is added to cflags. This wouldn't be a useful CONFIG_ item, since it breaks the build. Signed-off-by: Jim Cromie --- -v13 reword 2 failing tests (active only when -DDD_MACRO_ARGCHECK is passed to cc) to better identify what error is being tested against -v12 check map-type at compile-time make base+len(classnames) check more explicit dyndbg-test: add more tests of compile-time CHECKs add 3 tests of static-asserts added to 2 macros: DYNAMIC_DEBUG_CLASSMAP_{DEFINE,USE_} _DEFINE(): 1- validates maptype, 2- validate classmap.length + base-offset < 63 _USE_(): 3- validate user-offset < 63 As before, these tests fail when activated: make KCPPFLAGS="-DDD_MACRO_ARGCHECK" lib/test_dynamic_debug_submod.o NOTE: _USE_() cannot test classmap.length, since its a property of the referent, not the macro itself. dyndbg-test: verify DYNAMIC_DEBUG_CLASSMAP_USE_() compile-time CHECK Add another failing use-case, this time to verify that _USE properly rejects an offset > 62. This is an incomplete test; the proper test is: classes.length + base + offset < 63, but the macro cannot test classes.length at compile-time. Signed-off-by: Jim Cromie --- include/linux/dynamic_debug.h | 12 ++++++++++++ lib/test_dynamic_debug.c | 15 +++++++++++++++ 2 files changed, 27 insertions(+) diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h index 71c91bc8d3a6..a1c75237abaa 100644 --- a/include/linux/dynamic_debug.h +++ b/include/linux/dynamic_debug.h @@ -181,6 +181,17 @@ struct _ddebug_class_param { * __pr_debug_cls(22, "no such class"); compiles but is not reachable */ +#define __DYNAMIC_DEBUG_CLASSMAP_CHECK(_clnames, _base, _mapty) \ + static_assert(((_base) >= 0 && (_base) < _DPRINTK_CLASS_DFLT), \ + "_base must be in 0..62"); \ + static_assert(ARRAY_SIZE(_clnames) > 0, \ + "classnames array size must be > 0"); \ + static_assert((ARRAY_SIZE(_clnames) + (_base)) < _DPRINTK_CLASS_DFLT, \ + "_base + classnames.length must be <= 62"); \ + static_assert(((_mapty) >= DD_CLASS_TYPE_DISJOINT_BITS) && \ + ((_mapty) <= DD_CLASS_TYPE_LEVEL_NUM), \ + "unknown class_map_type") + /** * DYNAMIC_DEBUG_CLASSMAP_DEFINE - define debug classes used by a module. * @_var: name of the classmap, exported for other modules coordinated use. @@ -194,6 +205,7 @@ struct _ddebug_class_param { */ #define DYNAMIC_DEBUG_CLASSMAP_DEFINE(_var, _mapty, _base, ...) \ static const char *_var##_classnames[] = { __VA_ARGS__ }; \ + __DYNAMIC_DEBUG_CLASSMAP_CHECK(_var##_classnames, (_base), (_mapty)); \ extern struct _ddebug_class_map _var; \ struct _ddebug_class_map __aligned(8) __used \ __section("__dyndbg_class_maps") _var = { \ diff --git a/lib/test_dynamic_debug.c b/lib/test_dynamic_debug.c index fc599bbe605e..2107d4821019 100644 --- a/lib/test_dynamic_debug.c +++ b/lib/test_dynamic_debug.c @@ -146,8 +146,23 @@ DYNAMIC_DEBUG_CLASSMAP_DEFINE(classid_range_conflict, 0, D2_CORE + 1, "D3_CORE") DYNAMIC_DEBUG_CLASSMAP_USE(map_disjoint_bits); DYNAMIC_DEBUG_CLASSMAP_USE(map_level_num); +#if defined(DD_MACRO_ARGCHECK) +/* + * Exersize compile-time arg-checks in DYNAMIC_DEBUG_CLASSMAP_DEFINE. + * These will break compilation. + */ +DYNAMIC_DEBUG_CLASSMAP_DEFINE(fail_base_neg, 0, -1, "NEGATIVE_BASE_ARG"); +DYNAMIC_DEBUG_CLASSMAP_DEFINE(fail_base_big, 0, 100, "TOOBIG_BASE_ARG"); +DYNAMIC_DEBUG_CLASSMAP_DEFINE(fail_str_type, 0, 0, 1 /* not a string */); +DYNAMIC_DEBUG_CLASSMAP_DEFINE(fail_emptyclass, 0, 0 /* ,empty */); +DYNAMIC_DEBUG_CLASSMAP_DEFINE(fail_maptype, 3, 10, "no such type"); +DYNAMIC_DEBUG_CLASSMAP_DEFINE(fail_base_len, 0, 60, + "base", "plus", "classes", "length", "too-big"); +DYNAMIC_DEBUG_CLASSMAP_USE_(fail_offset_big, 100); #endif +#endif /* TEST_DYNAMIC_DEBUG_SUBMOD */ + /* stand-in for all pr_debug etc */ #define prdbg(SYM) __pr_debug_cls(SYM, #SYM " msg\n") -- 2.53.0