In preparation for building efi/libstub with -mbranch-protection=none (EFI does not support branch protection features[1]), add no-op code to work around a Clang bug that emits an unwanted .note.gnu.property section for object files without code[2]. [1] https://lore.kernel.org/lkml/CAMj1kXHck12juGi=E=P4hWP_8vQhQ+-x3vBMc3TGeRWdQ-XkxQ@xxxxxxxxxxxxxx [2] https://bugs.llvm.org/show_bug.cgi?id=46480 Cc: Ard Biesheuvel <ardb@xxxxxxxxxx> Cc: Will Deacon <will@xxxxxxxxxx> Cc: Dave Martin <Dave.Martin@xxxxxxx> Cc: clang-built-linux@xxxxxxxxxxxxxxxx Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> --- lib/ctype.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/lib/ctype.c b/lib/ctype.c index c819fe269eb2..21245ed57d90 100644 --- a/lib/ctype.c +++ b/lib/ctype.c @@ -36,3 +36,13 @@ _L,_L,_L,_L,_L,_L,_L,_L,_L,_L,_L,_L,_L,_L,_L,_L, /* 224-239 */ _L,_L,_L,_L,_L,_L,_L,_P,_L,_L,_L,_L,_L,_L,_L,_L}; /* 240-255 */ EXPORT_SYMBOL(_ctype); + +/* + * Clang will generate .note.gnu.property sections for object files + * without code, even in the presence of -mbranch-protection=none. + * To work around this, define an unused static function. + * https://bugs.llvm.org/show_bug.cgi?id=46480 + */ +#ifdef CONFIG_CC_IS_CLANG +void __maybe_unused __clang_needs_code_here(void) { } +#endif -- 2.25.1
