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# ${1} - output file 48vmlinux_link() 49{ 50 local output=${1} 51 local objs 52 local libs 53 local ld 54 local ldflags 55 local ldlibs 56 57 info LD ${output} 58 59 # skip output file argument 60 shift 61 62 if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then 63 # Use vmlinux.o instead of performing the slow LTO link again. 64 objs=vmlinux.o 65 libs= 66 else 67 objs=vmlinux.a 68 libs="${KBUILD_VMLINUX_LIBS}" 69 fi 70 71 if is_enabled CONFIG_GENERIC_BUILTIN_DTB; then 72 objs="${objs} .builtin-dtbs.o" 73 fi 74 75 if is_enabled CONFIG_MODULES; then 76 objs="${objs} .vmlinux.export.o" 77 fi 78 79 objs="${objs} init/version-timestamp.o" 80 81 if [ "${SRCARCH}" = "um" ]; then 82 wl=-Wl, 83 ld="${CC}" 84 ldflags="${CFLAGS_vmlinux}" 85 ldlibs="-lutil -lrt -lpthread" 86 else 87 wl= 88 ld="${LD}" 89 ldflags="${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}" 90 ldlibs= 91 fi 92 93 ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}" 94 95 # The kallsyms linking does not need debug symbols included. 96 if [ -n "${strip_debug}" ] ; then 97 ldflags="${ldflags} ${wl}--strip-debug" 98 fi 99 100 if is_enabled CONFIG_VMLINUX_MAP; then 101 ldflags="${ldflags} ${wl}-Map=${output}.map" 102 fi 103 104 ${ld} ${ldflags} -o ${output} \ 105 ${wl}--whole-archive ${objs} ${wl}--no-whole-archive \ 106 ${wl}--start-group ${libs} ${wl}--end-group \ 107 ${kallsymso} ${btf_vmlinux_bin_o} ${arch_vmlinux_o} ${ldlibs} 108} 109 110# generate .BTF typeinfo from DWARF debuginfo 111# ${1} - vmlinux image 112gen_btf() 113{ 114 local btf_data=${1}.btf.o 115 116 info BTF "${btf_data}" 117 LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1} 118 119 # Create ${btf_data} which contains just .BTF section but no symbols. Add 120 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all 121 # deletes all symbols including __start_BTF and __stop_BTF, which will 122 # be redefined in the linker script. Add 2>/dev/null to suppress GNU 123 # objcopy warnings: "empty loadable segment detected at ..." 124 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \ 125 --strip-all ${1} "${btf_data}" 2>/dev/null 126 # Change e_type to ET_REL so that it can be used to link final vmlinux. 127 # GNU ld 2.35+ and lld do not allow an ET_EXEC input. 128 if is_enabled CONFIG_CPU_BIG_ENDIAN; then 129 et_rel='\0\1' 130 else 131 et_rel='\1\0' 132 fi 133 printf "${et_rel}" | dd of="${btf_data}" conv=notrunc bs=1 seek=16 status=none 134 135 btf_vmlinux_bin_o=${btf_data} 136} 137 138# Create ${2}.o file with all symbols from the ${1} object file 139kallsyms() 140{ 141 local kallsymopt; 142 143 if is_enabled CONFIG_KALLSYMS_ALL; then 144 kallsymopt="${kallsymopt} --all-symbols" 145 fi 146 147 if is_enabled CONFIG_KALLSYMS_ABSOLUTE_PERCPU; then 148 kallsymopt="${kallsymopt} --absolute-percpu" 149 fi 150 151 info KSYMS "${2}.S" 152 scripts/kallsyms ${kallsymopt} "${1}" > "${2}.S" 153 154 info AS "${2}.o" 155 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \ 156 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} -c -o "${2}.o" "${2}.S" 157 158 kallsymso=${2}.o 159} 160 161# Perform kallsyms for the given temporary vmlinux. 162sysmap_and_kallsyms() 163{ 164 mksysmap "${1}" "${1}.syms" 165 kallsyms "${1}.syms" "${1}.kallsyms" 166 167 kallsyms_sysmap=${1}.syms 168} 169 170# Create map file with all symbols from ${1} 171# See mksymap for additional details 172mksysmap() 173{ 174 info NM ${2} 175 ${NM} -n "${1}" | sed -f "${srctree}/scripts/mksysmap" > "${2}" 176} 177 178sorttable() 179{ 180 ${NM} -S ${1} > .tmp_vmlinux.nm-sort 181 ${objtree}/scripts/sorttable -s .tmp_vmlinux.nm-sort ${1} 182} 183 184cleanup() 185{ 186 rm -f .btf.* 187 rm -f .tmp_vmlinux.nm-sort 188 rm -f System.map 189 rm -f vmlinux 190 rm -f vmlinux.map 191} 192 193# Use "make V=1" to debug this script 194case "${KBUILD_VERBOSE}" in 195*1*) 196 set -x 197 ;; 198esac 199 200if [ "$1" = "clean" ]; then 201 cleanup 202 exit 0 203fi 204 205${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init init/version-timestamp.o 206 207arch_vmlinux_o= 208if is_enabled CONFIG_ARCH_WANTS_PRE_LINK_VMLINUX; then 209 arch_vmlinux_o=arch/${SRCARCH}/tools/vmlinux.arch.o 210fi 211 212btf_vmlinux_bin_o= 213kallsymso= 214strip_debug= 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 283vmlinux_link vmlinux 284 285# fill in BTF IDs 286if is_enabled CONFIG_DEBUG_INFO_BTF; then 287 info BTFIDS vmlinux 288 RESOLVE_BTFIDS_ARGS="" 289 if is_enabled CONFIG_WERROR; then 290 RESOLVE_BTFIDS_ARGS=" --fatal_warnings " 291 fi 292 ${RESOLVE_BTFIDS} ${RESOLVE_BTFIDS_ARGS} vmlinux 293fi 294 295mksysmap vmlinux System.map 296 297if is_enabled CONFIG_BUILDTIME_TABLE_SORT; then 298 info SORTTAB vmlinux 299 if ! sorttable vmlinux; then 300 echo >&2 Failed to sort kernel tables 301 exit 1 302 fi 303fi 304 305# step a (see comment above) 306if is_enabled CONFIG_KALLSYMS; then 307 if ! cmp -s System.map "${kallsyms_sysmap}"; then 308 echo >&2 Inconsistent kallsyms data 309 echo >&2 'Try "make KALLSYMS_EXTRA_PASS=1" as a workaround' 310 exit 1 311 fi 312fi 313 314# For fixdep 315echo "vmlinux: $0" > .vmlinux.d 316