Re: [PATCH v2 05/13] kbuild: detect objtool update without using .SECONDEXPANSION

Kees Cook
2021-08-31T17:32:59Z

On Tue, Aug 31, 2021 at 04:39:56PM +0900, Masahiro Yamada wrote:
> Redo commit 8852c5524029 ("kbuild: Fix objtool dependency for
> 'OBJECT_FILES_NON_STANDARD_<obj> := n'") to add the objtool
> dependency in a cleaner way.
>
> Using .SECONDEXPANSION ends up with unreadable code due to escaped
> dollars. Also, it is not efficient because the second half of
> Makefile.build is parsed twice every time.
>
> Append the objtool dependency to the *.cmd files at the build time.
>
> This is what fixdep and gen_ksymdeps.sh already do. So, following the
> same pattern seems a natural solution.
>
> This allows us to drop $$(objtool_deps) entirely.
>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Okay, so IIUC, this means objtool (and args) now ends up in the .cmd
file instead of in the Makefile dep rules? That seems reasonable.

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

--
Kees Cook