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- #!/bin/sh
- # SPDX-License-Identifier: GPL-2.0
- #
- # link vmlinux
- #
- # vmlinux is linked from the objects in vmlinux.a and $(KBUILD_VMLINUX_LIBS).
- # vmlinux.a contains objects that are linked unconditionally.
- # $(KBUILD_VMLINUX_LIBS) are archives which are linked conditionally
- # (not within --whole-archive), and do not require symbol indexes added.
- #
- # vmlinux
- # ^
- # |
- # +--< vmlinux.a
- # |
- # +--< $(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"
- is_enabled() {
- grep -q "^$1=y" include/config/auto.conf
- }
- # Nice output in kbuild format
- # Will be supressed by "make -s"
- info()
- {
- printf " %-7s %s\n" "${1}" "${2}"
- }
- # Link of vmlinux
- # ${1} - output file
- # ${2}, ${3}, ... - optional extra .o files
- vmlinux_link()
- {
- local output=${1}
- local objs
- local libs
- local ld
- local ldflags
- local ldlibs
- info LD ${output}
- # skip output file argument
- shift
- if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then
- # Use vmlinux.o instead of performing the slow LTO link again.
- objs=vmlinux.o
- libs=
- else
- objs=vmlinux.a
- libs="${KBUILD_VMLINUX_LIBS}"
- fi
- if is_enabled CONFIG_MODULES; then
- objs="${objs} .vmlinux.export.o"
- fi
- objs="${objs} init/version-timestamp.o"
- 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" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
- ldflags="${ldflags} ${wl}--strip-debug"
- fi
- if is_enabled CONFIG_VMLINUX_MAP; then
- ldflags="${ldflags} ${wl}-Map=${output}.map"
- 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
- # ${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 ${PAHOLE_FLAGS} ${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 ${1} object file
- kallsyms()
- {
- local kallsymopt;
- if is_enabled CONFIG_KALLSYMS_ALL; then
- kallsymopt="${kallsymopt} --all-symbols"
- fi
- if is_enabled CONFIG_KALLSYMS_ABSOLUTE_PERCPU; then
- kallsymopt="${kallsymopt} --absolute-percpu"
- fi
- if is_enabled CONFIG_KALLSYMS_BASE_RELATIVE; then
- kallsymopt="${kallsymopt} --base-relative"
- fi
- if is_enabled CONFIG_LTO_CLANG; then
- kallsymopt="${kallsymopt} --lto-clang"
- fi
- info KSYMS ${2}
- scripts/kallsyms ${kallsymopt} ${1} > ${2}
- }
- # Perform one step in kallsyms generation, including temporary linking of
- # vmlinux.
- kallsyms_step()
- {
- kallsymso_prev=${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}
- mksysmap ${kallsyms_vmlinux} ${kallsyms_vmlinux}.syms
- kallsyms ${kallsyms_vmlinux}.syms ${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()
- {
- info NM ${2}
- ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
- }
- sorttable()
- {
- ${objtree}/scripts/sorttable ${1}
- }
- # Delete output files in case of error
- cleanup()
- {
- rm -f .btf.*
- rm -f System.map
- rm -f vmlinux
- rm -f vmlinux.map
- }
- # Use "make V=1" to debug this script
- case "${KBUILD_VERBOSE}" in
- *1*)
- set -x
- ;;
- esac
- if [ "$1" = "clean" ]; then
- cleanup
- exit 0
- fi
- ${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init init/version-timestamp.o
- btf_vmlinux_bin_o=""
- 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
- 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
- # Generate section listing all symbols and add it into vmlinux
- # It's a three step process:
- # 1) Link .tmp_vmlinux.kallsyms1 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_vmlinux.kallsyms2 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_vmlinux.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 is_enabled CONFIG_DEBUG_INFO_BTF && is_enabled CONFIG_BPF; then
- info BTFIDS vmlinux
- ${RESOLVE_BTFIDS} vmlinux
- fi
- mksysmap vmlinux System.map
- if is_enabled CONFIG_BUILDTIME_TABLE_SORT; then
- info SORTTAB vmlinux
- if ! sorttable vmlinux; then
- echo >&2 Failed to sort kernel tables
- exit 1
- fi
- fi
- # step a (see comment above)
- if is_enabled CONFIG_KALLSYMS; then
- if ! cmp -s System.map ${kallsyms_vmlinux}.syms; then
- echo >&2 Inconsistent kallsyms data
- echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
- exit 1
- fi
- fi
- # For fixdep
- echo "vmlinux: $0" > .vmlinux.d
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