Commit ddf41329 authored by Masahiro Yamada's avatar Masahiro Yamada
Browse files

kbuild: refactor variables in scripts/link-vmlinux.sh 



Clean up the variables in scripts/link-vmlinux.sh

 - Specify the extra objects directly in vmlinux_link()
 - Move the AS rule to kallsyms()
 - Set kallsymso and btf_vmlinux_bin_o where they are generated
 - Remove unneeded variable, kallsymso_prev
 - Introduce the btf_data variable
 - Introduce the strip_debug flag instead of checking the output name

No functional change intended.

Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
Reviewed-by: default avatarNicolas Schier <nicolas@fjasle.eu>
parent 995150e4

scripts/link-vmlinux.sh

+34 −31
Original line number Diff line number Diff line
@@ -45,7 +45,6 @@ info() 


# Link of vmlinux

# ${1} - output file

# ${2}, ${3}, ... - optional extra .o files

vmlinux_link()

{

	local output=${1}
@@ -90,7 +89,7 @@ vmlinux_link() 
	ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}"



	# The kallsyms linking does not need debug symbols included.

	if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then

	if [ -n "${strip_debug}" ] ; then

		ldflags="${ldflags} ${wl}--strip-debug"

	fi
@@ -101,7 +100,7 @@ vmlinux_link() 
	${ld} ${ldflags} -o ${output}					\

		${wl}--whole-archive ${objs} ${wl}--no-whole-archive	\

		${wl}--start-group ${libs} ${wl}--end-group		\

		$@ ${ldlibs}

		${kallsymso} ${btf_vmlinux_bin_o} ${ldlibs}

}



# generate .BTF typeinfo from DWARF debuginfo
@@ -110,6 +109,7 @@ vmlinux_link() 
gen_btf()

{

	local pahole_ver

	local btf_data=${2}



	if ! [ -x "$(command -v ${PAHOLE})" ]; then

		echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available"
@@ -124,16 +124,16 @@ gen_btf() 


	vmlinux_link ${1}



	info "BTF" ${2}

	info BTF "${btf_data}"

	LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1}



	# Create ${2} which contains just .BTF section but no symbols. Add

	# Create ${btf_data} which contains just .BTF section but no symbols. Add

	# SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all

	# deletes all symbols including __start_BTF and __stop_BTF, which will

	# be redefined in the linker script. Add 2>/dev/null to suppress GNU

	# objcopy warnings: "empty loadable segment detected at ..."

	${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \

		--strip-all ${1} ${2} 2>/dev/null

		--strip-all ${1} "${btf_data}" 2>/dev/null

	# Change e_type to ET_REL so that it can be used to link final vmlinux.

	# GNU ld 2.35+ and lld do not allow an ET_EXEC input.

	if is_enabled CONFIG_CPU_BIG_ENDIAN; then
@@ -141,10 +141,12 @@ gen_btf() 
	else

		et_rel='\1\0'

	fi

	printf "${et_rel}" | dd of=${2} conv=notrunc bs=1 seek=16 status=none

	printf "${et_rel}" | dd of="${btf_data}" conv=notrunc bs=1 seek=16 status=none



	btf_vmlinux_bin_o=${btf_data}

}



# Create ${2} .S file with all symbols from the ${1} object file

# Create ${2}.o file with all symbols from the ${1} object file

kallsyms()

{

	local kallsymopt;
@@ -165,27 +167,25 @@ kallsyms() 
		kallsymopt="${kallsymopt} --lto-clang"

	fi



	info KSYMS ${2}

	scripts/kallsyms ${kallsymopt} ${1} > ${2}

	info KSYMS "${2}.S"

	scripts/kallsyms ${kallsymopt} "${1}" > "${2}.S"



	info AS "${2}.o"

	${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \

	      ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} -c -o "${2}.o" "${2}.S"



	kallsymso=${2}.o

}



# Perform one step in kallsyms generation, including temporary linking of

# vmlinux.

kallsyms_step()

{

	kallsymso_prev=${kallsymso}

	kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1}

	kallsymso=${kallsyms_vmlinux}.o

	kallsyms_S=${kallsyms_vmlinux}.S



	vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o}

	mksysmap ${kallsyms_vmlinux} ${kallsyms_vmlinux}.syms

	kallsyms ${kallsyms_vmlinux}.syms ${kallsyms_S}



	info AS ${kallsymso}

	${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \

	      ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \

	      -c -o ${kallsymso} ${kallsyms_S}

	vmlinux_link "${kallsyms_vmlinux}"

	mksysmap "${kallsyms_vmlinux}" "${kallsyms_vmlinux}.syms"

	kallsyms "${kallsyms_vmlinux}.syms" "${kallsyms_vmlinux}"

}



# Create map file with all symbols from ${1}
@@ -223,19 +223,18 @@ fi 


${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init init/version-timestamp.o



btf_vmlinux_bin_o=""

btf_vmlinux_bin_o=

kallsymso=

strip_debug=



if is_enabled CONFIG_DEBUG_INFO_BTF; then

	btf_vmlinux_bin_o=.btf.vmlinux.bin.o

	if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then

	if ! gen_btf .tmp_vmlinux.btf .btf.vmlinux.bin.o ; then

		echo >&2 "Failed to generate BTF for vmlinux"

		echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF"

		exit 1

	fi

fi



kallsymso=""

kallsymso_prev=""

kallsyms_vmlinux=""

if is_enabled CONFIG_KALLSYMS; then



	# kallsyms support
@@ -261,11 +260,13 @@ if is_enabled CONFIG_KALLSYMS; then 
	# a)  Verify that the System.map from vmlinux matches the map from

	#     ${kallsymso}.



	# The kallsyms linking does not need debug symbols included.

	strip_debug=1



	kallsyms_step 1

	kallsyms_step 2

	size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})



	# step 3

	size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev})

	kallsyms_step 2

	size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})



	if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
@@ -273,7 +274,9 @@ if is_enabled CONFIG_KALLSYMS; then 
	fi

fi



vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o}

strip_debug=



vmlinux_link vmlinux



# fill in BTF IDs

if is_enabled CONFIG_DEBUG_INFO_BTF && is_enabled CONFIG_BPF; then