1#!/bin/sh 2# SPDX-License-Identifier: GPL-2.0 3# 4# link vmlinux 5# 6# vmlinux is linked from the objects in vmlinux.a and $(KBUILD_VMLINUX_LIBS). 7# vmlinux.a contains objects that are linked unconditionally. 8# $(KBUILD_VMLINUX_LIBS) are archives which are linked conditionally 9# (not within --whole-archive), and do not require symbol indexes added. 10# 11# vmlinux 12# ^ 13# | 14# +--< vmlinux.a 15# | 16# +--< $(KBUILD_VMLINUX_LIBS) 17# | +--< lib/lib.a + more 18# | 19# +-< ${kallsymso} (see description in KALLSYMS section) 20# 21# vmlinux version (uname -v) cannot be updated during normal 22# descending-into-subdirs phase since we do not yet know if we need to 23# update vmlinux. 24# Therefore this step is delayed until just before final link of vmlinux. 25# 26# System.map is generated to document addresses of all kernel symbols 27 28# Error out on error 29set -e 30 31LD="$1" 32KBUILD_LDFLAGS="$2" 33LDFLAGS_vmlinux="$3" 34 35is_enabled() { 36 grep -q "^$1=y" include/config/auto.conf 37} 38 39# Nice output in kbuild format 40# Will be supressed by "make -s" 41info() 42{ 43 printf " %-7s %s\n" "${1}" "${2}" 44} 45 46# Link of vmlinux 47# ${1} - output file 48# ${2}, ${3}, ... - optional extra .o files 49vmlinux_link() 50{ 51 local output=${1} 52 local objs 53 local libs 54 local ld 55 local ldflags 56 local ldlibs 57 58 info LD ${output} 59 60 # skip output file argument 61 shift 62 63 if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then 64 # Use vmlinux.o instead of performing the slow LTO link again. 65 objs=vmlinux.o 66 libs= 67 else 68 objs=vmlinux.a 69 libs="${KBUILD_VMLINUX_LIBS}" 70 fi 71 72 if is_enabled CONFIG_MODULES; then 73 objs="${objs} .vmlinux.export.o" 74 fi 75 76 objs="${objs} init/version-timestamp.o" 77 78 if [ "${SRCARCH}" = "um" ]; then 79 wl=-Wl, 80 ld="${CC}" 81 ldflags="${CFLAGS_vmlinux}" 82 ldlibs="-lutil -lrt -lpthread" 83 else 84 wl= 85 ld="${LD}" 86 ldflags="${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}" 87 ldlibs= 88 fi 89 90 ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}" 91 92 # The kallsyms linking does not need debug symbols included. 93 if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then 94 ldflags="${ldflags} ${wl}--strip-debug" 95 fi 96 97 if is_enabled CONFIG_VMLINUX_MAP; then 98 ldflags="${ldflags} ${wl}-Map=${output}.map" 99 fi 100 101 ${ld} ${ldflags} -o ${output} \ 102 ${wl}--whole-archive ${objs} ${wl}--no-whole-archive \ 103 ${wl}--start-group ${libs} ${wl}--end-group \ 104 $@ ${ldlibs} 105} 106 107# generate .BTF typeinfo from DWARF debuginfo 108# ${1} - vmlinux image 109# ${2} - file to dump raw BTF data into 110gen_btf() 111{ 112 local pahole_ver 113 114 if ! [ -x "$(command -v ${PAHOLE})" ]; then 115 echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available" 116 return 1 117 fi 118 119 pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/') 120 if [ "${pahole_ver}" -lt "116" ]; then 121 echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.16" 122 return 1 123 fi 124 125 vmlinux_link ${1} 126 127 info "BTF" ${2} 128 LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1} 129 130 # Create ${2} which contains just .BTF section but no symbols. Add 131 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all 132 # deletes all symbols including __start_BTF and __stop_BTF, which will 133 # be redefined in the linker script. Add 2>/dev/null to suppress GNU 134 # objcopy warnings: "empty loadable segment detected at ..." 135 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \ 136 --strip-all ${1} ${2} 2>/dev/null 137 # Change e_type to ET_REL so that it can be used to link final vmlinux. 138 # Unlike GNU ld, lld does not allow an ET_EXEC input. 139 printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none 140} 141 142# Create ${2} .S file with all symbols from the ${1} object file 143kallsyms() 144{ 145 local kallsymopt; 146 147 if is_enabled CONFIG_KALLSYMS_ALL; then 148 kallsymopt="${kallsymopt} --all-symbols" 149 fi 150 151 if is_enabled CONFIG_KALLSYMS_ABSOLUTE_PERCPU; then 152 kallsymopt="${kallsymopt} --absolute-percpu" 153 fi 154 155 if is_enabled CONFIG_KALLSYMS_BASE_RELATIVE; then 156 kallsymopt="${kallsymopt} --base-relative" 157 fi 158 159 if is_enabled CONFIG_LTO_CLANG; then 160 kallsymopt="${kallsymopt} --lto-clang" 161 fi 162 163 info KSYMS ${2} 164 scripts/kallsyms ${kallsymopt} ${1} > ${2} 165} 166 167# Perform one step in kallsyms generation, including temporary linking of 168# vmlinux. 169kallsyms_step() 170{ 171 kallsymso_prev=${kallsymso} 172 kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1} 173 kallsymso=${kallsyms_vmlinux}.o 174 kallsyms_S=${kallsyms_vmlinux}.S 175 176 vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o} 177 mksysmap ${kallsyms_vmlinux} ${kallsyms_vmlinux}.syms ${kallsymso_prev} 178 kallsyms ${kallsyms_vmlinux}.syms ${kallsyms_S} 179 180 info AS ${kallsyms_S} 181 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \ 182 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \ 183 -c -o ${kallsymso} ${kallsyms_S} 184} 185 186# Create map file with all symbols from ${1} 187# See mksymap for additional details 188mksysmap() 189{ 190 info NM ${2} 191 ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2} ${3} 192} 193 194sorttable() 195{ 196 ${objtree}/scripts/sorttable ${1} 197} 198 199# Delete output files in case of error 200cleanup() 201{ 202 rm -f .btf.* 203 rm -f System.map 204 rm -f vmlinux 205 rm -f vmlinux.map 206} 207 208# Use "make V=1" to debug this script 209case "${KBUILD_VERBOSE}" in 210*1*) 211 set -x 212 ;; 213esac 214 215if [ "$1" = "clean" ]; then 216 cleanup 217 exit 0 218fi 219 220${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init init/version-timestamp.o 221 222btf_vmlinux_bin_o="" 223if is_enabled CONFIG_DEBUG_INFO_BTF; then 224 btf_vmlinux_bin_o=.btf.vmlinux.bin.o 225 if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then 226 echo >&2 "Failed to generate BTF for vmlinux" 227 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF" 228 exit 1 229 fi 230fi 231 232kallsymso="" 233kallsymso_prev="" 234kallsyms_vmlinux="" 235if is_enabled CONFIG_KALLSYMS; then 236 237 # kallsyms support 238 # Generate section listing all symbols and add it into vmlinux 239 # It's a three step process: 240 # 1) Link .tmp_vmlinux.kallsyms1 so it has all symbols and sections, 241 # but __kallsyms is empty. 242 # Running kallsyms on that gives us .tmp_kallsyms1.o with 243 # the right size 244 # 2) Link .tmp_vmlinux.kallsyms2 so it now has a __kallsyms section of 245 # the right size, but due to the added section, some 246 # addresses have shifted. 247 # From here, we generate a correct .tmp_vmlinux.kallsyms2.o 248 # 3) That link may have expanded the kernel image enough that 249 # more linker branch stubs / trampolines had to be added, which 250 # introduces new names, which further expands kallsyms. Do another 251 # pass if that is the case. In theory it's possible this results 252 # in even more stubs, but unlikely. 253 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around 254 # other bugs. 255 # 4) The correct ${kallsymso} is linked into the final vmlinux. 256 # 257 # a) Verify that the System.map from vmlinux matches the map from 258 # ${kallsymso}. 259 260 kallsyms_step 1 261 kallsyms_step 2 262 263 # step 3 264 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev}) 265 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 266 267 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then 268 kallsyms_step 3 269 fi 270fi 271 272vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o} 273 274# fill in BTF IDs 275if is_enabled CONFIG_DEBUG_INFO_BTF && is_enabled CONFIG_BPF; then 276 info BTFIDS vmlinux 277 ${RESOLVE_BTFIDS} vmlinux 278fi 279 280mksysmap vmlinux System.map ${kallsymso} 281 282if is_enabled CONFIG_BUILDTIME_TABLE_SORT; then 283 info SORTTAB vmlinux 284 if ! sorttable vmlinux; then 285 echo >&2 Failed to sort kernel tables 286 exit 1 287 fi 288fi 289 290# step a (see comment above) 291if is_enabled CONFIG_KALLSYMS; then 292 if ! cmp -s System.map ${kallsyms_vmlinux}.syms; then 293 echo >&2 Inconsistent kallsyms data 294 echo >&2 'Try "make KALLSYMS_EXTRA_PASS=1" as a workaround' 295 exit 1 296 fi 297fi 298 299# For fixdep 300echo "vmlinux: $0" > .vmlinux.d 301