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_MODULES; then 72 objs="${objs} .vmlinux.export.o" 73 fi 74 75 objs="${objs} init/version-timestamp.o" 76 77 if [ "${SRCARCH}" = "um" ]; then 78 wl=-Wl, 79 ld="${CC}" 80 ldflags="${CFLAGS_vmlinux}" 81 ldlibs="-lutil -lrt -lpthread" 82 else 83 wl= 84 ld="${LD}" 85 ldflags="${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}" 86 ldlibs= 87 fi 88 89 ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}" 90 91 # The kallsyms linking does not need debug symbols included. 92 if [ -n "${strip_debug}" ] ; then 93 ldflags="${ldflags} ${wl}--strip-debug" 94 fi 95 96 if is_enabled CONFIG_VMLINUX_MAP; then 97 ldflags="${ldflags} ${wl}-Map=${output}.map" 98 fi 99 100 ${ld} ${ldflags} -o ${output} \ 101 ${wl}--whole-archive ${objs} ${wl}--no-whole-archive \ 102 ${wl}--start-group ${libs} ${wl}--end-group \ 103 ${kallsymso} ${btf_vmlinux_bin_o} ${ldlibs} 104} 105 106# generate .BTF typeinfo from DWARF debuginfo 107# ${1} - vmlinux image 108gen_btf() 109{ 110 local btf_data=${1}.btf.o 111 112 info BTF "${btf_data}" 113 LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1} 114 115 # Create ${btf_data} which contains just .BTF section but no symbols. Add 116 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all 117 # deletes all symbols including __start_BTF and __stop_BTF, which will 118 # be redefined in the linker script. Add 2>/dev/null to suppress GNU 119 # objcopy warnings: "empty loadable segment detected at ..." 120 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \ 121 --strip-all ${1} "${btf_data}" 2>/dev/null 122 # Change e_type to ET_REL so that it can be used to link final vmlinux. 123 # GNU ld 2.35+ and lld do not allow an ET_EXEC input. 124 if is_enabled CONFIG_CPU_BIG_ENDIAN; then 125 et_rel='\0\1' 126 else 127 et_rel='\1\0' 128 fi 129 printf "${et_rel}" | dd of="${btf_data}" conv=notrunc bs=1 seek=16 status=none 130 131 btf_vmlinux_bin_o=${btf_data} 132} 133 134# Create ${2}.o file with all symbols from the ${1} object file 135kallsyms() 136{ 137 local kallsymopt; 138 139 if is_enabled CONFIG_KALLSYMS_ALL; then 140 kallsymopt="${kallsymopt} --all-symbols" 141 fi 142 143 if is_enabled CONFIG_KALLSYMS_ABSOLUTE_PERCPU; then 144 kallsymopt="${kallsymopt} --absolute-percpu" 145 fi 146 147 info KSYMS "${2}.S" 148 scripts/kallsyms ${kallsymopt} "${1}" > "${2}.S" 149 150 info AS "${2}.o" 151 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \ 152 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} -c -o "${2}.o" "${2}.S" 153 154 kallsymso=${2}.o 155} 156 157# Perform kallsyms for the given temporary vmlinux. 158sysmap_and_kallsyms() 159{ 160 mksysmap "${1}" "${1}.syms" 161 kallsyms "${1}.syms" "${1}.kallsyms" 162 163 kallsyms_sysmap=${1}.syms 164} 165 166# Create map file with all symbols from ${1} 167# See mksymap for additional details 168mksysmap() 169{ 170 info NM ${2} 171 ${NM} -n "${1}" | sed -f "${srctree}/scripts/mksysmap" > "${2}" 172} 173 174sorttable() 175{ 176 ${objtree}/scripts/sorttable ${1} 177} 178 179cleanup() 180{ 181 rm -f .btf.* 182 rm -f System.map 183 rm -f vmlinux 184 rm -f vmlinux.map 185} 186 187# Use "make V=1" to debug this script 188case "${KBUILD_VERBOSE}" in 189*1*) 190 set -x 191 ;; 192esac 193 194if [ "$1" = "clean" ]; then 195 cleanup 196 exit 0 197fi 198 199${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init init/version-timestamp.o 200 201btf_vmlinux_bin_o= 202kallsymso= 203strip_debug= 204 205if is_enabled CONFIG_KALLSYMS; then 206 true > .tmp_vmlinux.kallsyms0.syms 207 kallsyms .tmp_vmlinux.kallsyms0.syms .tmp_vmlinux0.kallsyms 208fi 209 210if is_enabled CONFIG_KALLSYMS || is_enabled CONFIG_DEBUG_INFO_BTF; then 211 212 # The kallsyms linking does not need debug symbols, but the BTF does. 213 if ! is_enabled CONFIG_DEBUG_INFO_BTF; then 214 strip_debug=1 215 fi 216 217 vmlinux_link .tmp_vmlinux1 218fi 219 220if is_enabled CONFIG_DEBUG_INFO_BTF; then 221 if ! gen_btf .tmp_vmlinux1; then 222 echo >&2 "Failed to generate BTF for vmlinux" 223 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF" 224 exit 1 225 fi 226fi 227 228if is_enabled CONFIG_KALLSYMS; then 229 230 # kallsyms support 231 # Generate section listing all symbols and add it into vmlinux 232 # It's a four step process: 233 # 0) Generate a dummy __kallsyms with empty symbol list. 234 # 1) Link .tmp_vmlinux.kallsyms1 so it has all symbols and sections, 235 # with a dummy __kallsyms. 236 # Running kallsyms on that gives us .tmp_kallsyms1.o with 237 # the right size 238 # 2) Link .tmp_vmlinux.kallsyms2 so it now has a __kallsyms section of 239 # the right size, but due to the added section, some 240 # addresses have shifted. 241 # From here, we generate a correct .tmp_vmlinux.kallsyms2.o 242 # 3) That link may have expanded the kernel image enough that 243 # more linker branch stubs / trampolines had to be added, which 244 # introduces new names, which further expands kallsyms. Do another 245 # pass if that is the case. In theory it's possible this results 246 # in even more stubs, but unlikely. 247 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around 248 # other bugs. 249 # 4) The correct ${kallsymso} is linked into the final vmlinux. 250 # 251 # a) Verify that the System.map from vmlinux matches the map from 252 # ${kallsymso}. 253 254 # The kallsyms linking does not need debug symbols included. 255 strip_debug=1 256 257 sysmap_and_kallsyms .tmp_vmlinux1 258 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 259 260 vmlinux_link .tmp_vmlinux2 261 sysmap_and_kallsyms .tmp_vmlinux2 262 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 263 264 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then 265 vmlinux_link .tmp_vmlinux3 266 sysmap_and_kallsyms .tmp_vmlinux3 267 fi 268fi 269 270strip_debug= 271 272vmlinux_link vmlinux 273 274# fill in BTF IDs 275if is_enabled CONFIG_DEBUG_INFO_BTF; then 276 info BTFIDS vmlinux 277 ${RESOLVE_BTFIDS} vmlinux 278fi 279 280mksysmap vmlinux System.map 281 282if is_enabled CONFIG_BUILDTIME_TABLE_SORT; then 283 info SORTTAB vmlinux 284 if ! sorttable vmlinux; then 285 echo >&2 Failed to sort kernel tables 286 exit 1 287 fi 288fi 289 290# step a (see comment above) 291if is_enabled CONFIG_KALLSYMS; then 292 if ! cmp -s System.map "${kallsyms_sysmap}"; 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