#!/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="$3" # Nice output in kbuild format # Will be supressed by "make -s" info() { printf " %-7s %s\n" "${1}" "${2}" } # 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 local map_option local objs local libs info LD ${output} # skip output file argument shift if [ -n "${CONFIG_LTO_CLANG}" ]; then # Use vmlinux.o instead of performing the slow LTO link again. objs=vmlinux.o libs= else objs="${KBUILD_VMLINUX_OBJS}" libs="${KBUILD_VMLINUX_LIBS}" fi # The kallsyms linking does not need debug symbols included. if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then strip_debug=-Wl,--strip-debug fi if [ -n "${CONFIG_VMLINUX_MAP}" ]; then map_option="-Map=${output}.map" fi if [ "${SRCARCH}" != "um" ]; then objects="--whole-archive ${objs} --no-whole-archive \ --start-group ${libs} --end-group \ $@" ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} \ ${strip_debug#-Wl,} \ -o ${output} \ ${map_option} \ -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} \ ${map_option:+-Wl,${map_option}} \ -Wl,-T,${lds} \ ${objects} \ -lutil -lrt -lpthread rm -f linux fi } # generate .BTF typeinfo from DWARF debuginfo # ${1} - vmlinux image # ${2} - file to dump raw BTF data into gen_btf() { local pahole_ver local extra_paholeopt= if ! [ -x "$(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 ${1} if [ "${pahole_ver}" -ge "118" ] && [ "${pahole_ver}" -le "121" ]; then # pahole 1.18 through 1.21 can't handle zero-sized per-CPU vars extra_paholeopt="${extra_paholeopt} --skip_encoding_btf_vars" fi if [ "${pahole_ver}" -ge "121" ]; then extra_paholeopt="${extra_paholeopt} --btf_gen_floats" fi info "BTF" ${2} LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${extra_paholeopt} ${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 ${1} } # Delete output files in case of error cleanup() { rm -f .btf.* rm -f .tmp_System.map rm -f .tmp_initcalls.lds rm -f .tmp_symversions.lds rm -f .tmp_vmlinux* rm -f System.map rm -f vmlinux rm -f vmlinux.map rm -f vmlinux.o rm -f .vmlinux.d } # Use "make V=1" to debug this script case "${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 # For fixdep echo "vmlinux: $0" > .vmlinux.d