[PATCH v4 21/58] dyndbg: check DYNAMIC_DEBUG_CLASSMAP_DEFINE args at compile-time
From: Jim Cromie <jim.cromie@gmail.com>
Date: 2025-08-03 03:59:05
Also in:
amd-gfx, dri-devel, intel-gfx, linux-arm-msm, lkml
Subsystem:
dynamic debug, library code, the rest · Maintainers:
Jason Baron, Jim Cromie, Andrew Morton, Linus Torvalds
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 These compile-time checks will prevent several misuses; 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 <jim.cromie@gmail.com> --- v3- $macro_name =~ s/DYNDBG/DYNAMIC_DEBUG/ prev- - split static-asserts to __DYNDBG_CLASSMAP_CHECK - move __DYNDBG_CLASSMAP_CHECK above kdoc for DYNDBG_CLASSMAP_DEFINE silences kernel-doc warnings --- include/linux/dynamic_debug.h | 9 +++++++++ lib/test_dynamic_debug.c | 11 +++++++++++ 2 files changed, 20 insertions(+)
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index c45f5b76763cc..9bcada421e88e 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h@@ -110,6 +110,14 @@ struct _ddebug_class_map { enum ddebug_class_map_type map_type; }; +#define __DYNAMIC_DEBUG_CLASSMAP_CHECK(_clnames, _base) \ + 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 exceeds range") + /** * DYNAMIC_DEBUG_CLASSMAP_DEFINE - define debug classes used by a module. * @_var: name of the classmap, exported for other modules coordinated use.
@@ -123,6 +131,7 @@ struct _ddebug_class_map { */ #define DYNAMIC_DEBUG_CLASSMAP_DEFINE(_var, _mapty, _base, ...) \ static const char *_var##_classnames[] = { __VA_ARGS__ }; \ + __DYNAMIC_DEBUG_CLASSMAP_CHECK(_var##_classnames, (_base)); \ 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 1ba4be9a403ae..e83b34b6d6b95 100644
--- a/lib/test_dynamic_debug.c
+++ b/lib/test_dynamic_debug.c@@ -146,8 +146,19 @@ DYNDBG_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 DYNDBG_CLASSMAP_DEFINE. + * These will break compilation. + */ +DYNDBG_CLASSMAP_DEFINE(fail_base_neg, 0, -1, "NEGATIVE_BASE_ARG"); +DYNDBG_CLASSMAP_DEFINE(fail_base_big, 0, 100, "TOOBIG_BASE_ARG"); +DYNDBG_CLASSMAP_DEFINE(fail_str_type, 0, 0, 1 /* not a string */); +DYNDBG_CLASSMAP_DEFINE(fail_emptyclass, 0, 0 /* ,empty */); #endif +#endif /* TEST_DYNAMIC_DEBUG_SUBMOD */ + /* stand-in for all pr_debug etc */ #define prdbg(SYM) __pr_debug_cls(SYM, #SYM " msg\n")
--
2.50.1