Hi, On Mon, Oct 05, 2026 at 10:25:18AM +0000, Bill Wendling wrote: > 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 >
Reviewed-by: Justin Stitt <[email protected]> Thanks Justin
