Re: [PATCH 01/13] kbuild: move objtool_args back to scripts/Makefile.build

Kees Cook
2021-08-19T02:45:37Z

On Thu, Aug 19, 2021 at 09:57:32AM +0900, Masahiro Yamada wrote:
> Commit b1a1a1a09b46 ("kbuild: lto: postpone objtool") moved objtool_args
> to Makefile.lib, so the arguments can be used in Makefile.modfinal as
> well as Makefile.build.
>
> With commit 2b1d7fc05467 ("kbuild: Fix TRIM_UNUSED_KSYMS with
> LTO_CLANG"), module LTO linking came back to scripts/Makefile.build
> again.
>
> So, there is no more reason to keep objtool_args separately in
> scripts/Makefile.lib.
>
> Get it back to the original place, close to the objtool command.

Ah, yup. Good point. Nice cleanup.

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> ---
>
> scripts/Makefile.build | 13 +++++++++++++
> scripts/Makefile.lib | 12 ------------
> 2 files changed, 13 insertions(+), 12 deletions(-)
>
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index ea549579bfb7..31154e44c251 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -222,6 +222,19 @@ cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)),
> endif # CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
>
> ifdef CONFIG_STACK_VALIDATION
> +
> +# Objtool arguments are also needed for modfinal with LTO, so we define
> +# then here to avoid duplication.
> +objtool_args = \
> + $(if $(CONFIG_UNWINDER_ORC),orc generate,check) \
> + $(if $(part-of-module), --module,) \
> + $(if $(CONFIG_FRAME_POINTER),, --no-fp) \
> + $(if $(or $(CONFIG_GCOV_KERNEL),$(CONFIG_LTO_CLANG)), \
> + --no-unreachable,) \
> + $(if $(CONFIG_RETPOLINE), --retpoline,) \
> + $(if $(CONFIG_X86_SMAP), --uaccess,) \
> + $(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount,)
> +
> ifndef CONFIG_LTO_CLANG
>
> __objtool_obj := $(objtree)/tools/objtool/objtool
> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
> index af1c920a585c..34c4c11c4bc1 100644
> --- a/scripts/Makefile.lib
> +++ b/scripts/Makefile.lib
> @@ -232,18 +232,6 @@ ifeq ($(CONFIG_LTO_CLANG),y)
> mod-prelink-ext := .lto
> endif
>
> -# Objtool arguments are also needed for modfinal with LTO, so we define
> -# then here to avoid duplication.
> -objtool_args = \
> - $(if $(CONFIG_UNWINDER_ORC),orc generate,check) \
> - $(if $(part-of-module), --module,) \
> - $(if $(CONFIG_FRAME_POINTER),, --no-fp) \
> - $(if $(or $(CONFIG_GCOV_KERNEL),$(CONFIG_LTO_CLANG)), \
> - --no-unreachable,) \
> - $(if $(CONFIG_RETPOLINE), --retpoline,) \
> - $(if $(CONFIG_X86_SMAP), --uaccess,) \
> - $(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount,)
> -
> # Useful for describing the dependency of composite objects
> # Usage:
> # $(call multi_depend, multi_used_targets, suffix_to_remove, suffix_to_add)
> --
> 2.30.2
>

--
Kees Cook