1#!/bin/sh 2# SPDX-License-Identifier: GPL-2.0 3# 4# link vmlinux 5# 6# vmlinux is linked from the objects selected by $(KBUILD_VMLINUX_OBJS) and 7# $(KBUILD_VMLINUX_LIBS). Most are built-in.a files from top-level directories 8# in the kernel tree, others are specified in arch/$(ARCH)/Makefile. 9# $(KBUILD_VMLINUX_LIBS) are archives which are linked conditionally 10# (not within --whole-archive), and do not require symbol indexes added. 11# 12# vmlinux 13# ^ 14# | 15# +--< $(KBUILD_VMLINUX_OBJS) 16# | +--< init/built-in.a drivers/built-in.a mm/built-in.a + more 17# | 18# +--< $(KBUILD_VMLINUX_LIBS) 19# | +--< lib/lib.a + more 20# | 21# +-< ${kallsymso} (see description in KALLSYMS section) 22# 23# vmlinux version (uname -v) cannot be updated during normal 24# descending-into-subdirs phase since we do not yet know if we need to 25# update vmlinux. 26# Therefore this step is delayed until just before final link of vmlinux. 27# 28# System.map is generated to document addresses of all kernel symbols 29 30# Error out on error 31set -e 32 33# Nice output in kbuild format 34# Will be supressed by "make -s" 35info() 36{ 37 if [ "${quiet}" != "silent_" ]; then 38 printf " %-7s %s\n" "${1}" "${2}" 39 fi 40} 41 42# Link of vmlinux.o used for section mismatch analysis 43# ${1} output file 44modpost_link() 45{ 46 local objects 47 48 objects="--whole-archive \ 49 ${KBUILD_VMLINUX_OBJS} \ 50 --no-whole-archive \ 51 --start-group \ 52 ${KBUILD_VMLINUX_LIBS} \ 53 --end-group" 54 55 ${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${objects} 56} 57 58# Link of vmlinux 59# ${1} - output file 60# ${2}, ${3}, ... - optional extra .o files 61vmlinux_link() 62{ 63 local lds="${objtree}/${KBUILD_LDS}" 64 local output=${1} 65 local objects 66 67 info LD ${output} 68 69 # skip output file argument 70 shift 71 72 if [ "${SRCARCH}" != "um" ]; then 73 objects="--whole-archive \ 74 ${KBUILD_VMLINUX_OBJS} \ 75 --no-whole-archive \ 76 --start-group \ 77 ${KBUILD_VMLINUX_LIBS} \ 78 --end-group \ 79 ${@}" 80 81 ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} \ 82 -o ${output} \ 83 -T ${lds} ${objects} 84 else 85 objects="-Wl,--whole-archive \ 86 ${KBUILD_VMLINUX_OBJS} \ 87 -Wl,--no-whole-archive \ 88 -Wl,--start-group \ 89 ${KBUILD_VMLINUX_LIBS} \ 90 -Wl,--end-group \ 91 ${@}" 92 93 ${CC} ${CFLAGS_vmlinux} \ 94 -o ${output} \ 95 -Wl,-T,${lds} \ 96 ${objects} \ 97 -lutil -lrt -lpthread 98 rm -f linux 99 fi 100} 101 102# generate .BTF typeinfo from DWARF debuginfo 103# ${1} - vmlinux image 104# ${2} - file to dump raw BTF data into 105gen_btf() 106{ 107 local pahole_ver 108 local bin_arch 109 110 if ! [ -x "$(command -v ${PAHOLE})" ]; then 111 info "BTF" "${1}: pahole (${PAHOLE}) is not available" 112 return 1 113 fi 114 115 pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/') 116 if [ "${pahole_ver}" -lt "113" ]; then 117 info "BTF" "${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.13" 118 return 1 119 fi 120 121 info "BTF" ${2} 122 vmlinux_link ${1} 123 LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1} 124 125 # dump .BTF section into raw binary file to link with final vmlinux 126 bin_arch=$(LANG=C ${OBJDUMP} -f ${1} | grep architecture | \ 127 cut -d, -f1 | cut -d' ' -f2) 128 bin_format=$(LANG=C ${OBJDUMP} -f ${1} | grep 'file format' | \ 129 awk '{print $4}') 130 ${OBJCOPY} --change-section-address .BTF=0 \ 131 --set-section-flags .BTF=alloc -O binary \ 132 --only-section=.BTF ${1} .btf.vmlinux.bin 133 ${OBJCOPY} -I binary -O ${bin_format} -B ${bin_arch} \ 134 --rename-section .data=.BTF .btf.vmlinux.bin ${2} 135} 136 137# Create ${2} .o file with all symbols from the ${1} object file 138kallsyms() 139{ 140 info KSYM ${2} 141 local kallsymopt; 142 143 if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then 144 kallsymopt="${kallsymopt} --all-symbols" 145 fi 146 147 if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then 148 kallsymopt="${kallsymopt} --absolute-percpu" 149 fi 150 151 if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then 152 kallsymopt="${kallsymopt} --base-relative" 153 fi 154 155 local aflags="${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \ 156 ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS}" 157 158 local afile="`basename ${2} .o`.S" 159 160 ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${afile} 161 ${CC} ${aflags} -c -o ${2} ${afile} 162} 163 164# Perform one step in kallsyms generation, including temporary linking of 165# vmlinux. 166kallsyms_step() 167{ 168 kallsymso_prev=${kallsymso} 169 kallsymso=.tmp_kallsyms${1}.o 170 kallsyms_vmlinux=.tmp_vmlinux${1} 171 172 vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o} 173 kallsyms ${kallsyms_vmlinux} ${kallsymso} 174} 175 176# Create map file with all symbols from ${1} 177# See mksymap for additional details 178mksysmap() 179{ 180 ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2} 181} 182 183sortextable() 184{ 185 ${objtree}/scripts/sortextable ${1} 186} 187 188# Delete output files in case of error 189cleanup() 190{ 191 rm -f .btf.* 192 rm -f .tmp_System.map 193 rm -f .tmp_kallsyms* 194 rm -f .tmp_vmlinux* 195 rm -f System.map 196 rm -f vmlinux 197 rm -f vmlinux.o 198} 199 200on_exit() 201{ 202 if [ $? -ne 0 ]; then 203 cleanup 204 fi 205} 206trap on_exit EXIT 207 208on_signals() 209{ 210 exit 1 211} 212trap on_signals HUP INT QUIT TERM 213 214# 215# 216# Use "make V=1" to debug this script 217case "${KBUILD_VERBOSE}" in 218*1*) 219 set -x 220 ;; 221esac 222 223if [ "$1" = "clean" ]; then 224 cleanup 225 exit 0 226fi 227 228# We need access to CONFIG_ symbols 229. include/config/auto.conf 230 231# Update version 232info GEN .version 233if [ -r .version ]; then 234 VERSION=$(expr 0$(cat .version) + 1) 235 echo $VERSION > .version 236else 237 rm -f .version 238 echo 1 > .version 239fi; 240 241# final build of init/ 242${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init 243 244#link vmlinux.o 245info LD vmlinux.o 246modpost_link vmlinux.o 247 248# modpost vmlinux.o to check for section mismatches 249${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1 250 251info MODINFO modules.builtin.modinfo 252${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo 253 254btf_vmlinux_bin_o="" 255if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then 256 if gen_btf .tmp_vmlinux.btf .btf.vmlinux.bin.o ; then 257 btf_vmlinux_bin_o=.btf.vmlinux.bin.o 258 else 259 echo >&2 "Failed to generate BTF for vmlinux" 260 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF" 261 exit 1 262 fi 263fi 264 265kallsymso="" 266kallsymso_prev="" 267kallsyms_vmlinux="" 268if [ -n "${CONFIG_KALLSYMS}" ]; then 269 270 # kallsyms support 271 # Generate section listing all symbols and add it into vmlinux 272 # It's a three step process: 273 # 1) Link .tmp_vmlinux1 so it has all symbols and sections, 274 # but __kallsyms is empty. 275 # Running kallsyms on that gives us .tmp_kallsyms1.o with 276 # the right size 277 # 2) Link .tmp_vmlinux2 so it now has a __kallsyms section of 278 # the right size, but due to the added section, some 279 # addresses have shifted. 280 # From here, we generate a correct .tmp_kallsyms2.o 281 # 3) That link may have expanded the kernel image enough that 282 # more linker branch stubs / trampolines had to be added, which 283 # introduces new names, which further expands kallsyms. Do another 284 # pass if that is the case. In theory it's possible this results 285 # in even more stubs, but unlikely. 286 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around 287 # other bugs. 288 # 4) The correct ${kallsymso} is linked into the final vmlinux. 289 # 290 # a) Verify that the System.map from vmlinux matches the map from 291 # ${kallsymso}. 292 293 kallsyms_step 1 294 kallsyms_step 2 295 296 # step 3 297 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev}) 298 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 299 300 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then 301 kallsyms_step 3 302 fi 303fi 304 305vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o} 306 307if [ -n "${CONFIG_BUILDTIME_EXTABLE_SORT}" ]; then 308 info SORTEX vmlinux 309 sortextable vmlinux 310fi 311 312info SYSMAP System.map 313mksysmap vmlinux System.map 314 315# step a (see comment above) 316if [ -n "${CONFIG_KALLSYMS}" ]; then 317 mksysmap ${kallsyms_vmlinux} .tmp_System.map 318 319 if ! cmp -s System.map .tmp_System.map; then 320 echo >&2 Inconsistent kallsyms data 321 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround 322 exit 1 323 fi 324fi 325