linux-kernel - Re: [PATCH 12/13] kbuild: merge cmd_modversions_c and cmd_modversions

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Message-ID: <202108182005.AD31690E@keescook>
Date:   Wed, 18 Aug 2021 20:06:00 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Masahiro Yamada <masahiroy@...nel.org>
Cc:     linux-kbuild@...r.kernel.org,
        Sami Tolvanen <samitolvanen@...gle.com>,
        linux-kernel@...r.kernel.org,
        Michal Marek <michal.lkml@...kovi.net>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        clang-built-linux@...glegroups.com
Subject: Re: [PATCH 12/13] kbuild: merge cmd_modversions_c and
 cmd_modversions_S

On Thu, Aug 19, 2021 at 09:57:43AM +0900, Masahiro Yamada wrote:
> Now cmd_modversions_c and cmd_modversions_S are similar.
> 
> The latter uses $(OBJDUMP) -h, but it can be replaced with $(NM).
> 
> $(NM) works for both ELF and LLVM bitcode (if $(NM) is llvm-nm).
> 
> Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>

Ah yeah. That's nice consolidation.

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

-Kees

> ---
> 
>  scripts/Makefile.build | 15 ++++++---------
>  1 file changed, 6 insertions(+), 9 deletions(-)
> 
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index 874e84a1f3fc..97392c26ebd7 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -166,13 +166,16 @@ ifdef CONFIG_MODVERSIONS
>  
>  # Generate .o.symversions files for each .o with exported symbols, and link these
>  # to the kernel and/or modules at the end.
> -cmd_modversions_c =								\
> +cmd_modversions =								\
>  	if $(NM) $@ 2>/dev/null | grep -q __ksymtab; then			\
> -		$(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))	\
> +		$(call cmd_gensymtypes_$(1),$(KBUILD_SYMTYPES),$(@:.o=.symtypes)) \
>  		    > $@...mversions;						\
>  	else									\
>  		rm -f $@...mversions;						\
>  	fi;
> +
> +cmd_modversions_c = $(call cmd_modversions,c)
> +
>  endif
>  
>  ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
> @@ -327,14 +330,8 @@ ifdef CONFIG_ASM_MODVERSIONS
>  
>  # versioning matches the C process described above, with difference that
>  # we parse asm-prototypes.h C header to get function definitions.
> +cmd_modversions_S = $(call cmd_modversions,S)
>  
> -cmd_modversions_S =								\
> -	if $(OBJDUMP) -h $@ | grep -q __ksymtab; then				\
> -		$(call cmd_gensymtypes_S,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))	\
> -		    > $@...mversions;						\
> -	else									\
> -		rm -rf $@...mversions;						\
> -	fi
>  endif
>  
>  $(obj)/%.o: $(src)/%.S $(objtool_dep) FORCE
> -- 
> 2.30.2
> 

-- 
Kees Cook