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- #!/bin/sh
- # SPDX-License-Identifier: GPL-2.0
- #
- # link vmlinux
- #
- # vmlinux is linked from the objects selected by $(KBUILD_VMLINUX_OBJS) and
- # $(KBUILD_VMLINUX_LIBS). Most are built-in.a files from top-level directories
- # in the kernel tree, others are specified in arch/$(ARCH)/Makefile.
- # $(KBUILD_VMLINUX_LIBS) are archives which are linked conditionally
- # (not within --whole-archive), and do not require symbol indexes added.
- #
- # vmlinux
- # ^
- # |
- # +--< $(KBUILD_VMLINUX_OBJS)
- # | +--< init/built-in.a drivers/built-in.a mm/built-in.a + more
- # |
- # +--< $(KBUILD_VMLINUX_LIBS)
- # | +--< lib/lib.a + more
- # |
- # +-< ${kallsymso} (see description in KALLSYMS section)
- #
- # vmlinux version (uname -v) cannot be updated during normal
- # descending-into-subdirs phase since we do not yet know if we need to
- # update vmlinux.
- # Therefore this step is delayed until just before final link of vmlinux.
- #
- # System.map is generated to document addresses of all kernel symbols
- # Error out on error
- set -e
- LD="$1"
- KBUILD_LDFLAGS="$2"
- LDFLAGS_vmlinux="$3"
- # Nice output in kbuild format
- # Will be supressed by "make -s"
- info()
- {
- if [ "${quiet}" != "silent_" ]; then
- printf " %-7s %s\n" "${1}" "${2}"
- fi
- }
- # Generate a linker script to ensure correct ordering of initcalls.
- gen_initcalls()
- {
- info GEN .tmp_initcalls.lds
- ${PYTHON} ${srctree}/scripts/jobserver-exec \
- ${PERL} ${srctree}/scripts/generate_initcall_order.pl \
- ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS} \
- > .tmp_initcalls.lds
- }
- # If CONFIG_LTO_CLANG is selected, collect generated symbol versions into
- # .tmp_symversions.lds
- gen_symversions()
- {
- info GEN .tmp_symversions.lds
- rm -f .tmp_symversions.lds
- for o in ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS}; do
- if [ -f ${o}.symversions ]; then
- cat ${o}.symversions >> .tmp_symversions.lds
- fi
- done
- }
- # Link of vmlinux.o used for section mismatch analysis
- # ${1} output file
- modpost_link()
- {
- local objects
- local lds=""
- objects="--whole-archive \
- ${KBUILD_VMLINUX_OBJS} \
- --no-whole-archive \
- --start-group \
- ${KBUILD_VMLINUX_LIBS} \
- --end-group"
- if [ -n "${CONFIG_LTO_CLANG}" ]; then
- gen_initcalls
- lds="-T .tmp_initcalls.lds"
- if [ -n "${CONFIG_MODVERSIONS}" ]; then
- gen_symversions
- lds="${lds} -T .tmp_symversions.lds"
- fi
- # This might take a while, so indicate that we're doing
- # an LTO link
- info LTO ${1}
- else
- info LD ${1}
- fi
- ${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${lds} ${objects}
- }
- objtool_link()
- {
- local objtoolcmd;
- local objtoolopt;
- if [ "${CONFIG_LTO_CLANG} ${CONFIG_STACK_VALIDATION}" = "y y" ]; then
- # Don't perform vmlinux validation unless explicitly requested,
- # but run objtool on vmlinux.o now that we have an object file.
- if [ -n "${CONFIG_UNWINDER_ORC}" ]; then
- objtoolcmd="orc generate"
- fi
- objtoolopt="${objtoolopt} --duplicate"
- if [ -n "${CONFIG_FTRACE_MCOUNT_USE_OBJTOOL}" ]; then
- objtoolopt="${objtoolopt} --mcount"
- fi
- fi
- if [ -n "${CONFIG_VMLINUX_VALIDATION}" ]; then
- objtoolopt="${objtoolopt} --noinstr"
- fi
- if [ -n "${objtoolopt}" ]; then
- if [ -z "${objtoolcmd}" ]; then
- objtoolcmd="check"
- fi
- objtoolopt="${objtoolopt} --vmlinux"
- if [ -z "${CONFIG_FRAME_POINTER}" ]; then
- objtoolopt="${objtoolopt} --no-fp"
- fi
- if [ -n "${CONFIG_GCOV_KERNEL}" ] || [ -n "${CONFIG_LTO_CLANG}" ]; then
- objtoolopt="${objtoolopt} --no-unreachable"
- fi
- if [ -n "${CONFIG_RETPOLINE}" ]; then
- objtoolopt="${objtoolopt} --retpoline"
- fi
- if [ -n "${CONFIG_X86_SMAP}" ]; then
- objtoolopt="${objtoolopt} --uaccess"
- fi
- info OBJTOOL ${1}
- tools/objtool/objtool ${objtoolcmd} ${objtoolopt} ${1}
- fi
- }
- # Link of vmlinux
- # ${1} - output file
- # ${2}, ${3}, ... - optional extra .o files
- vmlinux_link()
- {
- local lds="${objtree}/${KBUILD_LDS}"
- local output=${1}
- local objects
- local strip_debug
- info LD ${output}
- # skip output file argument
- shift
- # The kallsyms linking does not need debug symbols included.
- if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
- strip_debug=-Wl,--strip-debug
- fi
- if [ "${SRCARCH}" != "um" ]; then
- if [ -n "${CONFIG_LTO_CLANG}" ]; then
- # Use vmlinux.o instead of performing the slow LTO
- # link again.
- objects="--whole-archive \
- vmlinux.o \
- --no-whole-archive \
- ${@}"
- else
- objects="--whole-archive \
- ${KBUILD_VMLINUX_OBJS} \
- --no-whole-archive \
- --start-group \
- ${KBUILD_VMLINUX_LIBS} \
- --end-group \
- ${@}"
- fi
- ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} \
- ${strip_debug#-Wl,} \
- -o ${output} \
- -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 ${output} \
- -Wl,-T,${lds} \
- ${objects} \
- -lutil -lrt -lpthread
- rm -f linux
- fi
- }
- # generate .BTF typeinfo from DWARF debuginfo
- # ${1} - vmlinux image
- # ${2} - file to dump raw BTF data into
- gen_btf()
- {
- local pahole_ver
- if ! [ -x "$(command -v ${PAHOLE})" ]; then
- echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available"
- return 1
- fi
- pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
- if [ "${pahole_ver}" -lt "116" ]; then
- echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.16"
- return 1
- fi
- vmlinux_link ${1}
- info "BTF" ${2}
- LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1}
- # Create ${2} 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} ${2} 2>/dev/null
- # Change e_type to ET_REL so that it can be used to link final vmlinux.
- # Unlike GNU ld, lld does not allow an ET_EXEC input.
- printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none
- }
- # Create ${2} .S file with all symbols from the ${1} object file
- kallsyms()
- {
- local kallsymopt;
- if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
- kallsymopt="${kallsymopt} --all-symbols"
- fi
- if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
- kallsymopt="${kallsymopt} --absolute-percpu"
- fi
- if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then
- kallsymopt="${kallsymopt} --base-relative"
- fi
- info KSYMS ${2}
- if [ -n "${CONFIG_CFI_CLANG}" ]; then
- ${PERL} ${srctree}/scripts/generate_cfi_kallsyms.pl ${1} | \
- sort -n > .tmp_kallsyms
- else
- ${NM} -n ${1} > .tmp_kallsyms
- fi
- scripts/kallsyms ${kallsymopt} < .tmp_kallsyms > ${2}
- }
- # Perform one step in kallsyms generation, including temporary linking of
- # vmlinux.
- kallsyms_step()
- {
- kallsymso_prev=${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}
- kallsyms ${kallsyms_vmlinux} ${kallsyms_S}
- info AS ${kallsyms_S}
- ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \
- ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \
- -c -o ${kallsymso} ${kallsyms_S}
- }
- # Create map file with all symbols from ${1}
- # See mksymap for additional details
- mksysmap()
- {
- ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
- }
- sorttable()
- {
- ${objtree}/scripts/sorttable ${1}
- }
- # Delete output files in case of error
- cleanup()
- {
- rm -f .btf.*
- rm -f .tmp_System.map
- rm -f .tmp_kallsyms
- rm -f .tmp_initcalls.lds
- rm -f .tmp_symversions.lds
- rm -f .tmp_vmlinux*
- rm -f System.map
- rm -f vmlinux
- rm -f vmlinux.o
- }
- on_exit()
- {
- if [ $? -ne 0 ]; then
- cleanup
- fi
- }
- trap on_exit EXIT
- on_signals()
- {
- exit 1
- }
- trap on_signals HUP INT QUIT TERM
- # Use "make V=1" to debug this script
- case "${KBUILD_VERBOSE}" in
- *1*)
- set -x
- ;;
- esac
- if [ "$1" = "clean" ]; then
- cleanup
- exit 0
- fi
- # We need access to CONFIG_ symbols
- . include/config/auto.conf
- # Update version
- info GEN .version
- if [ -r .version ]; then
- VERSION=$(expr 0$(cat .version) + 1)
- echo $VERSION > .version
- else
- rm -f .version
- echo 1 > .version
- fi;
- # final build of init/
- ${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1
- #link vmlinux.o
- modpost_link vmlinux.o
- objtool_link vmlinux.o
- # modpost vmlinux.o to check for section mismatches
- ${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1
- info MODINFO modules.builtin.modinfo
- ${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo
- info GEN modules.builtin
- # The second line aids cases where multiple modules share the same object.
- tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' |
- tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin
- btf_vmlinux_bin_o=""
- if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then
- btf_vmlinux_bin_o=.btf.vmlinux.bin.o
- if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then
- echo >&2 "Failed to generate BTF for vmlinux"
- echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF"
- exit 1
- fi
- fi
- kallsymso=""
- kallsymso_prev=""
- kallsyms_vmlinux=""
- if [ -n "${CONFIG_KALLSYMS}" ]; then
- # kallsyms support
- # Generate section listing all symbols and add it into vmlinux
- # It's a three step process:
- # 1) Link .tmp_vmlinux1 so it has all symbols and sections,
- # but __kallsyms is empty.
- # Running kallsyms on that gives us .tmp_kallsyms1.o with
- # the right size
- # 2) Link .tmp_vmlinux2 so it now has a __kallsyms section of
- # the right size, but due to the added section, some
- # addresses have shifted.
- # From here, we generate a correct .tmp_kallsyms2.o
- # 3) That link may have expanded the kernel image enough that
- # more linker branch stubs / trampolines had to be added, which
- # introduces new names, which further expands kallsyms. Do another
- # pass if that is the case. In theory it's possible this results
- # in even more stubs, but unlikely.
- # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
- # other bugs.
- # 4) The correct ${kallsymso} is linked into the final vmlinux.
- #
- # a) Verify that the System.map from vmlinux matches the map from
- # ${kallsymso}.
- kallsyms_step 1
- kallsyms_step 2
- # step 3
- size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev})
- size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
- if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
- kallsyms_step 3
- fi
- fi
- vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o}
- # fill in BTF IDs
- if [ -n "${CONFIG_DEBUG_INFO_BTF}" -a -n "${CONFIG_BPF}" ]; then
- info BTFIDS vmlinux
- ${RESOLVE_BTFIDS} vmlinux
- fi
- if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then
- info SORTTAB vmlinux
- if ! sorttable vmlinux; then
- echo >&2 Failed to sort kernel tables
- exit 1
- fi
- fi
- info SYSMAP System.map
- mksysmap vmlinux System.map
- # step a (see comment above)
- if [ -n "${CONFIG_KALLSYMS}" ]; then
- mksysmap ${kallsyms_vmlinux} .tmp_System.map
- if ! cmp -s System.map .tmp_System.map; then
- echo >&2 Inconsistent kallsyms data
- echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
- exit 1
- fi
- fi
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