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" 34VMLINUX="$4" 35 36is_enabled() { 37 grep -q "^$1=y" include/config/auto.conf 38} 39 40# Nice output in kbuild format 41# Will be supressed by "make -s" 42info() 43{ 44 printf " %-7s %s\n" "${1}" "${2}" 45} 46 47# Link of vmlinux 48# ${1} - output file 49vmlinux_link() 50{ 51 local output=${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_GENERIC_BUILTIN_DTB; then 73 objs="${objs} .builtin-dtbs.o" 74 fi 75 76 if is_enabled CONFIG_MODULES; then 77 objs="${objs} .vmlinux.export.o" 78 fi 79 80 objs="${objs} init/version-timestamp.o" 81 82 if [ "${SRCARCH}" = "um" ]; then 83 wl=-Wl, 84 ld="${CC}" 85 ldflags="${CFLAGS_vmlinux}" 86 ldlibs="-lutil -lrt -lpthread" 87 else 88 wl= 89 ld="${LD}" 90 ldflags="${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}" 91 ldlibs= 92 fi 93 94 ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}" 95 96 # The kallsyms linking does not need debug symbols included. 97 if [ -n "${strip_debug}" ] ; then 98 ldflags="${ldflags} ${wl}--strip-debug" 99 fi 100 101 if [ -n "${generate_map}" ]; then 102 ldflags="${ldflags} ${wl}-Map=vmlinux.map" 103 fi 104 105 ${ld} ${ldflags} -o ${output} \ 106 ${wl}--whole-archive ${objs} ${wl}--no-whole-archive \ 107 ${wl}--start-group ${libs} ${wl}--end-group \ 108 ${kallsymso} ${btf_vmlinux_bin_o} ${arch_vmlinux_o} ${ldlibs} 109} 110 111# generate .BTF typeinfo from DWARF debuginfo 112# ${1} - vmlinux image 113gen_btf() 114{ 115 local btf_data=${1}.btf.o 116 117 info BTF "${btf_data}" 118 LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1} 119 120 # Create ${btf_data} which contains just .BTF section but no symbols. Add 121 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all 122 # deletes all symbols including __start_BTF and __stop_BTF, which will 123 # be redefined in the linker script. Add 2>/dev/null to suppress GNU 124 # objcopy warnings: "empty loadable segment detected at ..." 125 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \ 126 --strip-all ${1} "${btf_data}" 2>/dev/null 127 # Change e_type to ET_REL so that it can be used to link final vmlinux. 128 # GNU ld 2.35+ and lld do not allow an ET_EXEC input. 129 if is_enabled CONFIG_CPU_BIG_ENDIAN; then 130 et_rel='\0\1' 131 else 132 et_rel='\1\0' 133 fi 134 printf "${et_rel}" | dd of="${btf_data}" conv=notrunc bs=1 seek=16 status=none 135 136 btf_vmlinux_bin_o=${btf_data} 137} 138 139# Create ${2}.o file with all symbols from the ${1} object file 140kallsyms() 141{ 142 local kallsymopt; 143 144 if is_enabled CONFIG_KALLSYMS_ALL; then 145 kallsymopt="${kallsymopt} --all-symbols" 146 fi 147 148 if is_enabled CONFIG_KALLSYMS_ABSOLUTE_PERCPU; then 149 kallsymopt="${kallsymopt} --absolute-percpu" 150 fi 151 152 info KSYMS "${2}.S" 153 scripts/kallsyms ${kallsymopt} "${1}" > "${2}.S" 154 155 info AS "${2}.o" 156 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \ 157 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} -c -o "${2}.o" "${2}.S" 158 159 kallsymso=${2}.o 160} 161 162# Perform kallsyms for the given temporary vmlinux. 163sysmap_and_kallsyms() 164{ 165 mksysmap "${1}" "${1}.syms" 166 kallsyms "${1}.syms" "${1}.kallsyms" 167 168 kallsyms_sysmap=${1}.syms 169} 170 171# Create map file with all symbols from ${1} 172# See mksymap for additional details 173mksysmap() 174{ 175 info NM ${2} 176 ${NM} -n "${1}" | sed -f "${srctree}/scripts/mksysmap" > "${2}" 177} 178 179sorttable() 180{ 181 ${objtree}/scripts/sorttable ${1} 182} 183 184cleanup() 185{ 186 rm -f .btf.* 187 rm -f System.map 188 rm -f vmlinux 189 rm -f vmlinux.map 190} 191 192# Use "make V=1" to debug this script 193case "${KBUILD_VERBOSE}" in 194*1*) 195 set -x 196 ;; 197esac 198 199if [ "$1" = "clean" ]; then 200 cleanup 201 exit 0 202fi 203 204${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init init/version-timestamp.o 205 206arch_vmlinux_o= 207if is_enabled CONFIG_ARCH_WANTS_PRE_LINK_VMLINUX; then 208 arch_vmlinux_o=arch/${SRCARCH}/tools/vmlinux.arch.o 209fi 210 211btf_vmlinux_bin_o= 212kallsymso= 213strip_debug= 214generate_map= 215 216if is_enabled CONFIG_KALLSYMS; then 217 true > .tmp_vmlinux0.syms 218 kallsyms .tmp_vmlinux0.syms .tmp_vmlinux0.kallsyms 219fi 220 221if is_enabled CONFIG_KALLSYMS || is_enabled CONFIG_DEBUG_INFO_BTF; then 222 223 # The kallsyms linking does not need debug symbols, but the BTF does. 224 if ! is_enabled CONFIG_DEBUG_INFO_BTF; then 225 strip_debug=1 226 fi 227 228 vmlinux_link .tmp_vmlinux1 229fi 230 231if is_enabled CONFIG_DEBUG_INFO_BTF; then 232 if ! gen_btf .tmp_vmlinux1; then 233 echo >&2 "Failed to generate BTF for vmlinux" 234 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF" 235 exit 1 236 fi 237fi 238 239if is_enabled CONFIG_KALLSYMS; then 240 241 # kallsyms support 242 # Generate section listing all symbols and add it into vmlinux 243 # It's a four step process: 244 # 0) Generate a dummy __kallsyms with empty symbol list. 245 # 1) Link .tmp_vmlinux1.kallsyms so it has all symbols and sections, 246 # with a dummy __kallsyms. 247 # Running kallsyms on that gives us .tmp_vmlinux1.kallsyms.o with 248 # the right size 249 # 2) Link .tmp_vmlinux2.kallsyms so it now has a __kallsyms section of 250 # the right size, but due to the added section, some 251 # addresses have shifted. 252 # From here, we generate a correct .tmp_vmlinux2.kallsyms.o 253 # 3) That link may have expanded the kernel image enough that 254 # more linker branch stubs / trampolines had to be added, which 255 # introduces new names, which further expands kallsyms. Do another 256 # pass if that is the case. In theory it's possible this results 257 # in even more stubs, but unlikely. 258 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around 259 # other bugs. 260 # 4) The correct ${kallsymso} is linked into the final vmlinux. 261 # 262 # a) Verify that the System.map from vmlinux matches the map from 263 # ${kallsymso}. 264 265 # The kallsyms linking does not need debug symbols included. 266 strip_debug=1 267 268 sysmap_and_kallsyms .tmp_vmlinux1 269 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 270 271 vmlinux_link .tmp_vmlinux2 272 sysmap_and_kallsyms .tmp_vmlinux2 273 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 274 275 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then 276 vmlinux_link .tmp_vmlinux3 277 sysmap_and_kallsyms .tmp_vmlinux3 278 fi 279fi 280 281strip_debug= 282 283if is_enabled CONFIG_VMLINUX_MAP; then 284 generate_map=1 285fi 286 287vmlinux_link "${VMLINUX}" 288 289# fill in BTF IDs 290if is_enabled CONFIG_DEBUG_INFO_BTF; then 291 info BTFIDS "${VMLINUX}" 292 RESOLVE_BTFIDS_ARGS="" 293 if is_enabled CONFIG_WERROR; then 294 RESOLVE_BTFIDS_ARGS=" --fatal_warnings " 295 fi 296 ${RESOLVE_BTFIDS} ${RESOLVE_BTFIDS_ARGS} "${VMLINUX}" 297fi 298 299mksysmap "${VMLINUX}" System.map 300 301if is_enabled CONFIG_BUILDTIME_TABLE_SORT; then 302 info SORTTAB "${VMLINUX}" 303 if ! sorttable "${VMLINUX}"; then 304 echo >&2 Failed to sort kernel tables 305 exit 1 306 fi 307fi 308 309# step a (see comment above) 310if is_enabled CONFIG_KALLSYMS; then 311 if ! cmp -s System.map "${kallsyms_sysmap}"; then 312 echo >&2 Inconsistent kallsyms data 313 echo >&2 'Try "make KALLSYMS_EXTRA_PASS=1" as a workaround' 314 exit 1 315 fi 316fi 317 318# For fixdep 319echo "${VMLINUX}: $0" > ".${VMLINUX}.d" 320