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 local strip_debug 67 68 info LD ${output} 69 70 # skip output file argument 71 shift 72 73 # The kallsyms linking does not need debug symbols included. 74 if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then 75 strip_debug=-Wl,--strip-debug 76 fi 77 78 if [ "${SRCARCH}" != "um" ]; then 79 objects="--whole-archive \ 80 ${KBUILD_VMLINUX_OBJS} \ 81 --no-whole-archive \ 82 --start-group \ 83 ${KBUILD_VMLINUX_LIBS} \ 84 --end-group \ 85 ${@}" 86 87 ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} \ 88 ${strip_debug#-Wl,} \ 89 -o ${output} \ 90 -T ${lds} ${objects} 91 else 92 objects="-Wl,--whole-archive \ 93 ${KBUILD_VMLINUX_OBJS} \ 94 -Wl,--no-whole-archive \ 95 -Wl,--start-group \ 96 ${KBUILD_VMLINUX_LIBS} \ 97 -Wl,--end-group \ 98 ${@}" 99 100 ${CC} ${CFLAGS_vmlinux} \ 101 ${strip_debug} \ 102 -o ${output} \ 103 -Wl,-T,${lds} \ 104 ${objects} \ 105 -lutil -lrt -lpthread 106 rm -f linux 107 fi 108} 109 110# generate .BTF typeinfo from DWARF debuginfo 111# ${1} - vmlinux image 112# ${2} - file to dump raw BTF data into 113gen_btf() 114{ 115 local pahole_ver 116 117 if ! [ -x "$(command -v ${PAHOLE})" ]; then 118 echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available" 119 return 1 120 fi 121 122 pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/') 123 if [ "${pahole_ver}" -lt "113" ]; then 124 echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.13" 125 return 1 126 fi 127 128 vmlinux_link ${1} 129 130 info "BTF" ${2} 131 LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1} 132 133 # Create ${2} which contains just .BTF section but no symbols. Add 134 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all 135 # deletes all symbols including __start_BTF and __stop_BTF, which will 136 # be redefined in the linker script. Add 2>/dev/null to suppress GNU 137 # objcopy warnings: "empty loadable segment detected at ..." 138 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \ 139 --strip-all ${1} ${2} 2>/dev/null 140 # Change e_type to ET_REL so that it can be used to link final vmlinux. 141 # Unlike GNU ld, lld does not allow an ET_EXEC input. 142 printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none 143} 144 145# Create ${2} .o file with all symbols from the ${1} object file 146kallsyms() 147{ 148 info KSYM ${2} 149 local kallsymopt; 150 151 if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then 152 kallsymopt="${kallsymopt} --all-symbols" 153 fi 154 155 if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then 156 kallsymopt="${kallsymopt} --absolute-percpu" 157 fi 158 159 if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then 160 kallsymopt="${kallsymopt} --base-relative" 161 fi 162 163 local aflags="${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \ 164 ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS}" 165 166 local afile="`basename ${2} .o`.S" 167 168 ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${afile} 169 ${CC} ${aflags} -c -o ${2} ${afile} 170} 171 172# Perform one step in kallsyms generation, including temporary linking of 173# vmlinux. 174kallsyms_step() 175{ 176 kallsymso_prev=${kallsymso} 177 kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1} 178 kallsymso=${kallsyms_vmlinux}.o 179 180 vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o} 181 kallsyms ${kallsyms_vmlinux} ${kallsymso} 182} 183 184# Create map file with all symbols from ${1} 185# See mksymap for additional details 186mksysmap() 187{ 188 ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2} 189} 190 191sorttable() 192{ 193 ${objtree}/scripts/sorttable ${1} 194} 195 196# Delete output files in case of error 197cleanup() 198{ 199 rm -f .btf.* 200 rm -f .tmp_System.map 201 rm -f .tmp_vmlinux* 202 rm -f System.map 203 rm -f vmlinux 204 rm -f vmlinux.o 205} 206 207on_exit() 208{ 209 if [ $? -ne 0 ]; then 210 cleanup 211 fi 212} 213trap on_exit EXIT 214 215on_signals() 216{ 217 exit 1 218} 219trap on_signals HUP INT QUIT TERM 220 221# 222# 223# Use "make V=1" to debug this script 224case "${KBUILD_VERBOSE}" in 225*1*) 226 set -x 227 ;; 228esac 229 230if [ "$1" = "clean" ]; then 231 cleanup 232 exit 0 233fi 234 235# We need access to CONFIG_ symbols 236. include/config/auto.conf 237 238# Update version 239info GEN .version 240if [ -r .version ]; then 241 VERSION=$(expr 0$(cat .version) + 1) 242 echo $VERSION > .version 243else 244 rm -f .version 245 echo 1 > .version 246fi; 247 248# final build of init/ 249${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1 250 251#link vmlinux.o 252info LD vmlinux.o 253modpost_link vmlinux.o 254 255# modpost vmlinux.o to check for section mismatches 256${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1 257 258info MODINFO modules.builtin.modinfo 259${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo 260info GEN modules.builtin 261# The second line aids cases where multiple modules share the same object. 262tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' | 263 tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin 264 265btf_vmlinux_bin_o="" 266if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then 267 btf_vmlinux_bin_o=.btf.vmlinux.bin.o 268 if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then 269 echo >&2 "Failed to generate BTF for vmlinux" 270 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF" 271 exit 1 272 fi 273fi 274 275kallsymso="" 276kallsymso_prev="" 277kallsyms_vmlinux="" 278if [ -n "${CONFIG_KALLSYMS}" ]; then 279 280 # kallsyms support 281 # Generate section listing all symbols and add it into vmlinux 282 # It's a three step process: 283 # 1) Link .tmp_vmlinux1 so it has all symbols and sections, 284 # but __kallsyms is empty. 285 # Running kallsyms on that gives us .tmp_kallsyms1.o with 286 # the right size 287 # 2) Link .tmp_vmlinux2 so it now has a __kallsyms section of 288 # the right size, but due to the added section, some 289 # addresses have shifted. 290 # From here, we generate a correct .tmp_kallsyms2.o 291 # 3) That link may have expanded the kernel image enough that 292 # more linker branch stubs / trampolines had to be added, which 293 # introduces new names, which further expands kallsyms. Do another 294 # pass if that is the case. In theory it's possible this results 295 # in even more stubs, but unlikely. 296 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around 297 # other bugs. 298 # 4) The correct ${kallsymso} is linked into the final vmlinux. 299 # 300 # a) Verify that the System.map from vmlinux matches the map from 301 # ${kallsymso}. 302 303 kallsyms_step 1 304 kallsyms_step 2 305 306 # step 3 307 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev}) 308 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 309 310 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then 311 kallsyms_step 3 312 fi 313fi 314 315vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o} 316 317if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then 318 info SORTTAB vmlinux 319 if ! sorttable vmlinux; then 320 echo >&2 Failed to sort kernel tables 321 exit 1 322 fi 323fi 324 325info SYSMAP System.map 326mksysmap vmlinux System.map 327 328# step a (see comment above) 329if [ -n "${CONFIG_KALLSYMS}" ]; then 330 mksysmap ${kallsyms_vmlinux} .tmp_System.map 331 332 if ! cmp -s System.map .tmp_System.map; then 333 echo >&2 Inconsistent kallsyms data 334 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround 335 exit 1 336 fi 337fi 338