On Wed, 12 Jun 2024 at 06:03, Masahiro Yamada <masahiroy@xxxxxxxxxx> wrote:
>
> Some instructions are only available on the 64-bit architecture.
>
> Bi-arch compilers that default to -m32 need the explicit -m64 option
> to evaluate them properly.
>
> Fixes: 18e66b695e78 ("x86/shstk: Add Kconfig option for shadow stack")
> Reported-by: Dmitry Safonov <0x7f454c46@xxxxxxxxx>
> Closes: https://lore.kernel.org/all/20240612-as-instr-opt-wrussq-v2-1-bd950f7eead7@xxxxxxxxx/
> Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
Thank you Masahiro, this works as well!
I guess I went on too generic path without an actual requirement for that.
Tested-by: Dmitry Safonov <0x7f454c46@xxxxxxxxx>
> ---
>
> arch/x86/Kconfig.assembler | 2 +-
> scripts/Kconfig.include | 3 ++-
> 2 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/Kconfig.assembler b/arch/x86/Kconfig.assembler
> index 59aedf32c4ea..6d20a6ce0507 100644
> --- a/arch/x86/Kconfig.assembler
> +++ b/arch/x86/Kconfig.assembler
> @@ -36,6 +36,6 @@ config AS_VPCLMULQDQ
> Supported by binutils >= 2.30 and LLVM integrated assembler
>
> config AS_WRUSS
> - def_bool $(as-instr,wrussq %rax$(comma)(%rbx))
> + def_bool $(as-instr64,wrussq %rax$(comma)(%rbx))
> help
> Supported by binutils >= 2.31 and LLVM integrated assembler
> diff --git a/scripts/Kconfig.include b/scripts/Kconfig.include
> index 3ee8ecfb8c04..3500a3d62f0d 100644
> --- a/scripts/Kconfig.include
> +++ b/scripts/Kconfig.include
> @@ -33,7 +33,8 @@ ld-option = $(success,$(LD) -v $(1))
>
> # $(as-instr,<instr>)
> # Return y if the assembler supports <instr>, n otherwise
> -as-instr = $(success,printf "%b\n" "$(1)" | $(CC) $(CLANG_FLAGS) -Wa$(comma)--fatal-warnings -c -x assembler-with-cpp -o /dev/null -)
> +as-instr = $(success,printf "%b\n" "$(1)" | $(CC) $(CLANG_FLAGS) $(2) -Wa$(comma)--fatal-warnings -c -x assembler-with-cpp -o /dev/null -)
> +as-instr64 = $(as-instr,$(1),$(m64-flag))
>
> # check if $(CC) and $(LD) exist
> $(error-if,$(failure,command -v $(CC)),C compiler '$(CC)' not found)
> --
> 2.43.0
>
--
Dmitry
