[PATCH v7 23/31] dyndbg: check DYNAMIC_DEBUG_CLASSMAP_DEFINE args at compile-time
From: Jim Cromie <jim.cromie@gmail.com>
Date: 2025-12-22 08:25:29
Also in:
amd-gfx, dri-devel, intel-gfx, linux-arm-kernel, linux-arm-msm
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 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 <jim.cromie@gmail.com> --- include/linux/dynamic_debug.h | 9 +++++++++ lib/test_dynamic_debug.c | 13 ++++++++++++- 2 files changed, 21 insertions(+), 1 deletion(-)
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index 905db0b49104..b19c9b1d53b6 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h@@ -180,6 +180,14 @@ struct _ddebug_class_param { * __pr_debug_cls(22, "no such class"); compiles but is not reachable */ +#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.
@@ -193,6 +201,7 @@ 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)); \ 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 1ba4be9a403a..b2bdfdfb6ba1 100644
--- a/lib/test_dynamic_debug.c
+++ b/lib/test_dynamic_debug.c@@ -133,7 +133,7 @@ DYNAMIC_DEBUG_CLASSMAP_PARAM(level_num, p); * Enable with -Dflag on compile to test overlapping class-id range * detection. This should warn on modprobes. */ -DYNDBG_CLASSMAP_DEFINE(classid_range_conflict, 0, D2_CORE + 1, "D3_CORE"); +DYNAMIC_DEBUG_CLASSMAP_DEFINE(classid_range_conflict, 0, D2_CORE + 1, "D3_CORE"); #endif #else /* TEST_DYNAMIC_DEBUG_SUBMOD */
@@ -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 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 */); #endif +#endif /* TEST_DYNAMIC_DEBUG_SUBMOD */ + /* stand-in for all pr_debug etc */ #define prdbg(SYM) __pr_debug_cls(SYM, #SYM " msg\n")
--
2.52.0