linux-kernel - Re: [PATCH 08/13] kbuild: merge vmlinux_link() between ARCH=um and other architectures

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Date:   Wed, 18 Aug 2021 19:43:29 -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>,
        Nick Desaulniers <ndesaulniers@...gle.com>
Subject: Re: [PATCH 08/13] kbuild: merge vmlinux_link() between ARCH=um and
 other architectures

On Thu, Aug 19, 2021 at 09:57:39AM +0900, Masahiro Yamada wrote:
> For ARCH=um, ${CC} is used as the linker driver. Hence, the linker
> options are prefixed with -Wl, .
> 
> Merge the similar code.
> 
> I replaced the -T option with the long option --script= so that it
> works well with/without ${wl}.

And same for this one. So much better!

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

-Kees

> 
> Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
> ---
> 
>  scripts/link-vmlinux.sh | 56 +++++++++++++++++------------------------
>  1 file changed, 23 insertions(+), 33 deletions(-)
> 
> diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
> index 7b9c62e4d54a..d74cee5c4326 100755
> --- a/scripts/link-vmlinux.sh
> +++ b/scripts/link-vmlinux.sh
> @@ -149,13 +149,12 @@ objtool_link()
>  # ${2}, ${3}, ... - optional extra .o files
>  vmlinux_link()
>  {
> -	local lds="${objtree}/${KBUILD_LDS}"
>  	local output=${1}
> -	local objects
> -	local strip_debug
> -	local map_option
>  	local objs
>  	local libs
> +	local ld
> +	local ldflags
> +	local ldlibs
>  
>  	info LD ${output}
>  
> @@ -171,42 +170,33 @@ vmlinux_link()
>  		libs="${KBUILD_VMLINUX_LIBS}"
>  	fi
>  
> +	if [ "${SRCARCH}" = "um" ]; then
> +		wl=-Wl,
> +		ld="${CC}"
> +		ldflags="${CFLAGS_vmlinux}"
> +		ldlibs="-lutil -lrt -lpthread"
> +	else
> +		wl=
> +		ld="${LD}"
> +		ldflags="${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}"
> +		ldlibs=
> +	fi
> +
> +	ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}"
> +
>  	# The kallsyms linking does not need debug symbols included.
>  	if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
> -		strip_debug=-Wl,--strip-debug
> +		ldflags="${ldflags} ${wl}--strip-debug"
>  	fi
>  
>  	if [ -n "${CONFIG_VMLINUX_MAP}" ]; then
> -		map_option="-Map=${output}.map"
> +		ldflags="${ldflags} ${wl}-Map=${output}.map"
>  	fi
>  
> -	if [ "${SRCARCH}" != "um" ]; then
> -		objects="--whole-archive ${objs} --no-whole-archive	\
> -			 --start-group ${libs} --end-group		\
> -			 $@"
> -
> -		${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}	\
> -			${strip_debug#-Wl,}			\
> -			-o ${output}				\
> -			${map_option}				\
> -			-T ${lds} ${objects}
> -	else
> -		objects="-Wl,--whole-archive			\
> -			${KBUILD_VMLINUX_OBJS}			\
> -			-Wl,--no-whole-archive			\
> -			-Wl,--start-group			\
> -			${KBUILD_VMLINUX_LIBS}			\
> -			-Wl,--end-group				\
> -			${@}"
> -
> -		${CC} ${CFLAGS_vmlinux}				\
> -			${strip_debug}				\
> -			-o ${output}				\
> -			${map_option:+-Wl,${map_option}}	\
> -			-Wl,-T,${lds}				\
> -			${objects}				\
> -			-lutil -lrt -lpthread
> -	fi
> +	${ld} ${ldflags} -o ${output}					\
> +		${wl}--whole-archive ${objs} ${wl}--no-whole-archive	\
> +		${wl}--start-group ${libs} ${wl}--end-group		\
> +		$@ ${ldlibs}
>  }
>  
>  # generate .BTF typeinfo from DWARF debuginfo
> -- 
> 2.30.2
> 

-- 
Kees Cook