301 lines
7.5 KiB
Bash
301 lines
7.5 KiB
Bash
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#!/bin/sh
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# SPDX-License-Identifier: GPL-2.0
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#
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# link vmlinux
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#
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# vmlinux is linked from the objects in vmlinux.a and $(KBUILD_VMLINUX_LIBS).
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# vmlinux.a contains objects that are linked unconditionally.
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# $(KBUILD_VMLINUX_LIBS) are archives which are linked conditionally
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# (not within --whole-archive), and do not require symbol indexes added.
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#
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# vmlinux
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# ^
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# |
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# +--< vmlinux.a
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# |
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# +--< $(KBUILD_VMLINUX_LIBS)
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# | +--< lib/lib.a + more
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# |
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# +-< ${kallsymso} (see description in KALLSYMS section)
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#
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# vmlinux version (uname -v) cannot be updated during normal
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# descending-into-subdirs phase since we do not yet know if we need to
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# update vmlinux.
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# Therefore this step is delayed until just before final link of vmlinux.
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#
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# System.map is generated to document addresses of all kernel symbols
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# Error out on error
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set -e
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LD="$1"
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KBUILD_LDFLAGS="$2"
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LDFLAGS_vmlinux="$3"
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is_enabled() {
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grep -q "^$1=y" include/config/auto.conf
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}
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# Nice output in kbuild format
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# Will be supressed by "make -s"
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info()
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{
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printf " %-7s %s\n" "${1}" "${2}"
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}
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# Link of vmlinux
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# ${1} - output file
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# ${2}, ${3}, ... - optional extra .o files
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vmlinux_link()
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{
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local output=${1}
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local objs
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local libs
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local ld
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local ldflags
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local ldlibs
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info LD ${output}
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# skip output file argument
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shift
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if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then
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# Use vmlinux.o instead of performing the slow LTO link again.
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objs=vmlinux.o
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libs=
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else
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objs=vmlinux.a
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libs="${KBUILD_VMLINUX_LIBS}"
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fi
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if is_enabled CONFIG_MODULES; then
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objs="${objs} .vmlinux.export.o"
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fi
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objs="${objs} init/version-timestamp.o"
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if [ "${SRCARCH}" = "um" ]; then
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wl=-Wl,
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ld="${CC}"
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ldflags="${CFLAGS_vmlinux}"
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ldlibs="-lutil -lrt -lpthread"
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else
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wl=
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ld="${LD}"
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ldflags="${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}"
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ldlibs=
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fi
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ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}"
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# The kallsyms linking does not need debug symbols included.
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if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
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ldflags="${ldflags} ${wl}--strip-debug"
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fi
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if is_enabled CONFIG_VMLINUX_MAP; then
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ldflags="${ldflags} ${wl}-Map=${output}.map"
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fi
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${ld} ${ldflags} -o ${output} \
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${wl}--whole-archive ${objs} ${wl}--no-whole-archive \
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${wl}--start-group ${libs} ${wl}--end-group \
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$@ ${ldlibs}
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}
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# generate .BTF typeinfo from DWARF debuginfo
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# ${1} - vmlinux image
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# ${2} - file to dump raw BTF data into
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gen_btf()
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{
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local pahole_ver
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if ! [ -x "$(command -v ${PAHOLE})" ]; then
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echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available"
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return 1
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fi
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pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
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if [ "${pahole_ver}" -lt "116" ]; then
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echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.16"
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return 1
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fi
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vmlinux_link ${1}
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info "BTF" ${2}
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LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1}
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# Create ${2} which contains just .BTF section but no symbols. Add
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# SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all
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# deletes all symbols including __start_BTF and __stop_BTF, which will
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# be redefined in the linker script. Add 2>/dev/null to suppress GNU
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# objcopy warnings: "empty loadable segment detected at ..."
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${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \
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--strip-all ${1} ${2} 2>/dev/null
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# Change e_type to ET_REL so that it can be used to link final vmlinux.
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# Unlike GNU ld, lld does not allow an ET_EXEC input.
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printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none
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}
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# Create ${2} .S file with all symbols from the ${1} object file
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kallsyms()
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{
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local kallsymopt;
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if is_enabled CONFIG_KALLSYMS_ALL; then
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kallsymopt="${kallsymopt} --all-symbols"
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fi
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if is_enabled CONFIG_KALLSYMS_ABSOLUTE_PERCPU; then
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kallsymopt="${kallsymopt} --absolute-percpu"
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fi
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if is_enabled CONFIG_KALLSYMS_BASE_RELATIVE; then
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kallsymopt="${kallsymopt} --base-relative"
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fi
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if is_enabled CONFIG_LTO_CLANG; then
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kallsymopt="${kallsymopt} --lto-clang"
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fi
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info KSYMS ${2}
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scripts/kallsyms ${kallsymopt} ${1} > ${2}
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}
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# Perform one step in kallsyms generation, including temporary linking of
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# vmlinux.
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kallsyms_step()
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{
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kallsymso_prev=${kallsymso}
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kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1}
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kallsymso=${kallsyms_vmlinux}.o
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kallsyms_S=${kallsyms_vmlinux}.S
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vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o}
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mksysmap ${kallsyms_vmlinux} ${kallsyms_vmlinux}.syms
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kallsyms ${kallsyms_vmlinux}.syms ${kallsyms_S}
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info AS ${kallsyms_S}
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${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \
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${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \
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-c -o ${kallsymso} ${kallsyms_S}
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}
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# Create map file with all symbols from ${1}
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# See mksymap for additional details
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mksysmap()
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{
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info NM ${2}
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${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
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}
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sorttable()
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{
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${objtree}/scripts/sorttable ${1}
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}
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# Delete output files in case of error
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cleanup()
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{
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rm -f .btf.*
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rm -f System.map
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rm -f vmlinux
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rm -f vmlinux.map
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}
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# Use "make V=1" to debug this script
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case "${KBUILD_VERBOSE}" in
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*1*)
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set -x
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;;
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esac
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if [ "$1" = "clean" ]; then
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cleanup
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exit 0
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fi
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${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init init/version-timestamp.o
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btf_vmlinux_bin_o=""
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if is_enabled CONFIG_DEBUG_INFO_BTF; then
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btf_vmlinux_bin_o=.btf.vmlinux.bin.o
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if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then
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echo >&2 "Failed to generate BTF for vmlinux"
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echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF"
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exit 1
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fi
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fi
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kallsymso=""
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kallsymso_prev=""
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kallsyms_vmlinux=""
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if is_enabled CONFIG_KALLSYMS; then
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# kallsyms support
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# Generate section listing all symbols and add it into vmlinux
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# It's a three step process:
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# 1) Link .tmp_vmlinux.kallsyms1 so it has all symbols and sections,
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# but __kallsyms is empty.
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# Running kallsyms on that gives us .tmp_kallsyms1.o with
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# the right size
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# 2) Link .tmp_vmlinux.kallsyms2 so it now has a __kallsyms section of
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# the right size, but due to the added section, some
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# addresses have shifted.
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# From here, we generate a correct .tmp_vmlinux.kallsyms2.o
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# 3) That link may have expanded the kernel image enough that
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# more linker branch stubs / trampolines had to be added, which
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# introduces new names, which further expands kallsyms. Do another
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# pass if that is the case. In theory it's possible this results
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# in even more stubs, but unlikely.
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# KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
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# other bugs.
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# 4) The correct ${kallsymso} is linked into the final vmlinux.
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#
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# a) Verify that the System.map from vmlinux matches the map from
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# ${kallsymso}.
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kallsyms_step 1
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kallsyms_step 2
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# step 3
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size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev})
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size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
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if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
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kallsyms_step 3
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fi
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fi
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vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o}
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# fill in BTF IDs
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if is_enabled CONFIG_DEBUG_INFO_BTF && is_enabled CONFIG_BPF; then
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info BTFIDS vmlinux
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${RESOLVE_BTFIDS} vmlinux
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fi
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mksysmap vmlinux System.map
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if is_enabled CONFIG_BUILDTIME_TABLE_SORT; then
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info SORTTAB vmlinux
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if ! sorttable vmlinux; then
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echo >&2 Failed to sort kernel tables
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exit 1
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fi
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fi
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# step a (see comment above)
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if is_enabled CONFIG_KALLSYMS; then
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if ! cmp -s System.map ${kallsyms_vmlinux}.syms; then
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echo >&2 Inconsistent kallsyms data
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echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
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exit 1
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fi
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fi
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# For fixdep
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echo "vmlinux: $0" > .vmlinux.d
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