diff options
Diffstat (limited to 'scripts/link-vmlinux.sh')
| -rwxr-xr-x | scripts/link-vmlinux.sh | 375 |
1 files changed, 375 insertions, 0 deletions
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh new file mode 100755 index 000000000..acd07a70a --- /dev/null +++ b/scripts/link-vmlinux.sh @@ -0,0 +1,375 @@ +#!/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 +} + +# Link of vmlinux.o used for section mismatch analysis +# ${1} output file +modpost_link() +{ + local objects + + objects="--whole-archive \ + ${KBUILD_VMLINUX_OBJS} \ + --no-whole-archive \ + --start-group \ + ${KBUILD_VMLINUX_LIBS} \ + --end-group" + + ${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${objects} +} + +objtool_link() +{ + local objtoolopt; + + if [ -n "${CONFIG_VMLINUX_VALIDATION}" ]; then + objtoolopt="check" + if [ -n "${CONFIG_CPU_UNRET_ENTRY}" ]; then + objtoolopt="${objtoolopt} --unret" + fi + if [ -z "${CONFIG_FRAME_POINTER}" ]; then + objtoolopt="${objtoolopt} --no-fp" + fi + if [ -n "${CONFIG_GCOV_KERNEL}" ]; then + objtoolopt="${objtoolopt} --no-unreachable" + fi + if [ -n "${CONFIG_RETPOLINE}" ]; then + objtoolopt="${objtoolopt} --retpoline" + fi + if [ -n "${CONFIG_X86_SMAP}" ]; then + objtoolopt="${objtoolopt} --uaccess" + fi + if [ -n "${CONFIG_SLS}" ]; then + objtoolopt="${objtoolopt} --sls" + fi + info OBJTOOL ${1} + tools/objtool/objtool ${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 + objects="--whole-archive \ + ${KBUILD_VMLINUX_OBJS} \ + --no-whole-archive \ + --start-group \ + ${KBUILD_VMLINUX_LIBS} \ + --end-group \ + ${@}" + + ${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 ${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 ${1} object file +kallsyms() +{ + local kallsymopt; + + if [ -n "${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} + ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${2} +} + +# Perform one step in kallsyms generation, including temporary linking of +# vmlinux. +kallsyms_step() +{ + kallsymso_prev=${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_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 "${srctree}/scripts/Makefile.build" obj=init need-builtin=1 + +#link vmlinux.o +info LD vmlinux.o +modpost_link vmlinux.o +objtool_link vmlinux.o + +# modpost vmlinux.o to check for section mismatches +${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 |