Code that runs outside the kernel proper, such as the EFI stub, gets nothing out of the counted_by annotations: the bounds checks they feed (FORTIFY_SOURCE, UBSAN_BOUNDS) are already disabled there.
The annotations can also break the build. A __counted_by_ptr() that names a member declared after the pointer needs Clang's '-fexperimental-late-parse-attributes', which the top-level Makefile adds to 'KBUILD_CFLAGS'. The x86 EFI stub builds its own cflags and does not get that flag, so it fails as soon as such a struct is pulled in through a common header. Overriding the macros from a Makefile doesn't work: 'compiler_types.h' is pulled in with '-include', which is processed after all -D/-U options, so it re-establishes the definitions. Follow the '__NO_FORTIFY' precedent instead: let a build define '__NO_COUNTED_BY' or '__NO_COUNTED_BY_PTR' to turn the corresponding annotation into a no-op. The two are kept separate but parallel so they can be folded together once all supported compilers handle '__counted_by' on pointers. Assisted-by: LLM Signed-off-by: Bill Wendling <[email protected]> --- include/linux/compiler_types.h | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h index c5921f139007..916a946f623c 100644 --- a/include/linux/compiler_types.h +++ b/include/linux/compiler_types.h @@ -371,8 +371,14 @@ struct ftrace_likely_data { * * __bdos on clang < 19.1.3 can be off by 4: * https://github.com/llvm/llvm-project/pull/112636 + * + * Code that runs outside the kernel proper (e.g. the EFI stub) can define + * __NO_COUNTED_BY to drop the annotation, since it gains nothing from the + * bounds checks. Kept in step with __NO_COUNTED_BY_PTR below so the two can + * be folded together once __counted_by covers pointers on all supported + * compilers. */ -#ifdef CONFIG_CC_HAS_COUNTED_BY +#if defined(CONFIG_CC_HAS_COUNTED_BY) && !defined(__NO_COUNTED_BY) # define __counted_by(member) __attribute__((__counted_by__(member))) #else # define __counted_by(member) @@ -387,8 +393,13 @@ struct ftrace_likely_data { * * gcc: https://gcc.gnu.org/pipermail/gcc-patches/2025-April/681727.html * clang: https://clang.llvm.org/docs/AttributeReference.html#counted-by-counted-by-or-null-sized-by-sized-by-or-null + * + * Code that runs outside the kernel proper (e.g. the EFI stub) can define + * __NO_COUNTED_BY_PTR to drop the annotation, as with __NO_COUNTED_BY. Such + * code may also lack the flag Clang needs to parse a reference to a + * later-declared member (-fexperimental-late-parse-attributes). */ -#ifdef CONFIG_CC_HAS_COUNTED_BY_PTR +#if defined(CONFIG_CC_HAS_COUNTED_BY_PTR) && !defined(__NO_COUNTED_BY_PTR) #define __counted_by_ptr(member) __attribute__((__counted_by__(member))) #else #define __counted_by_ptr(member) -- 2.56.0.rc1.315.gc6ed9934b7-goog
