diff options
Diffstat (limited to '')
| -rwxr-xr-x | scripts/link-vmlinux.sh | 300 |
1 files changed, 300 insertions, 0 deletions
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh new file mode 100755 index 000000000..32e573943 --- /dev/null +++ b/scripts/link-vmlinux.sh @@ -0,0 +1,300 @@ +#!/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 |