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 ${objtree}/scripts/sorttable ${1} 181} 182 183cleanup() 184{ 185 rm -f .btf.* 186 rm -f System.map 187 rm -f vmlinux 188 rm -f vmlinux.map 189} 190 191# Use "make V=1" to debug this script 192case "${KBUILD_VERBOSE}" in 193*1*) 194 set -x 195 ;; 196esac 197 198if [ "$1" = "clean" ]; then 199 cleanup 200 exit 0 201fi 202 203${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init init/version-timestamp.o 204 205arch_vmlinux_o= 206if is_enabled CONFIG_ARCH_WANTS_PRE_LINK_VMLINUX; then 207 arch_vmlinux_o=arch/${SRCARCH}/tools/vmlinux.arch.o 208fi 209 210btf_vmlinux_bin_o= 211kallsymso= 212strip_debug= 213 214if is_enabled CONFIG_KALLSYMS; then 215 true > .tmp_vmlinux0.syms 216 kallsyms .tmp_vmlinux0.syms .tmp_vmlinux0.kallsyms 217fi 218 219if is_enabled CONFIG_KALLSYMS || is_enabled CONFIG_DEBUG_INFO_BTF; then 220 221 # The kallsyms linking does not need debug symbols, but the BTF does. 222 if ! is_enabled CONFIG_DEBUG_INFO_BTF; then 223 strip_debug=1 224 fi 225 226 vmlinux_link .tmp_vmlinux1 227fi 228 229if is_enabled CONFIG_DEBUG_INFO_BTF; then 230 if ! gen_btf .tmp_vmlinux1; then 231 echo >&2 "Failed to generate BTF for vmlinux" 232 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF" 233 exit 1 234 fi 235fi 236 237if is_enabled CONFIG_KALLSYMS; then 238 239 # kallsyms support 240 # Generate section listing all symbols and add it into vmlinux 241 # It's a four step process: 242 # 0) Generate a dummy __kallsyms with empty symbol list. 243 # 1) Link .tmp_vmlinux1.kallsyms so it has all symbols and sections, 244 # with a dummy __kallsyms. 245 # Running kallsyms on that gives us .tmp_vmlinux1.kallsyms.o with 246 # the right size 247 # 2) Link .tmp_vmlinux2.kallsyms so it now has a __kallsyms section of 248 # the right size, but due to the added section, some 249 # addresses have shifted. 250 # From here, we generate a correct .tmp_vmlinux2.kallsyms.o 251 # 3) That link may have expanded the kernel image enough that 252 # more linker branch stubs / trampolines had to be added, which 253 # introduces new names, which further expands kallsyms. Do another 254 # pass if that is the case. In theory it's possible this results 255 # in even more stubs, but unlikely. 256 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around 257 # other bugs. 258 # 4) The correct ${kallsymso} is linked into the final vmlinux. 259 # 260 # a) Verify that the System.map from vmlinux matches the map from 261 # ${kallsymso}. 262 263 # The kallsyms linking does not need debug symbols included. 264 strip_debug=1 265 266 sysmap_and_kallsyms .tmp_vmlinux1 267 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 268 269 vmlinux_link .tmp_vmlinux2 270 sysmap_and_kallsyms .tmp_vmlinux2 271 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 272 273 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then 274 vmlinux_link .tmp_vmlinux3 275 sysmap_and_kallsyms .tmp_vmlinux3 276 fi 277fi 278 279strip_debug= 280 281vmlinux_link vmlinux 282 283# fill in BTF IDs 284if is_enabled CONFIG_DEBUG_INFO_BTF; then 285 info BTFIDS vmlinux 286 ${RESOLVE_BTFIDS} vmlinux 287fi 288 289mksysmap vmlinux System.map 290 291if is_enabled CONFIG_BUILDTIME_TABLE_SORT; then 292 info SORTTAB vmlinux 293 if ! sorttable vmlinux; then 294 echo >&2 Failed to sort kernel tables 295 exit 1 296 fi 297fi 298 299# step a (see comment above) 300if is_enabled CONFIG_KALLSYMS; then 301 if ! cmp -s System.map "${kallsyms_sysmap}"; then 302 echo >&2 Inconsistent kallsyms data 303 echo >&2 'Try "make KALLSYMS_EXTRA_PASS=1" as a workaround' 304 exit 1 305 fi 306fi 307 308# For fixdep 309echo "vmlinux: $0" > .vmlinux.d 310