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# ${1} - vmlinux image 108gen_btf() 109{ 110 local pahole_ver 111 local btf_data=${1}.btf.o 112 113 if ! [ -x "$(command -v ${PAHOLE})" ]; then 114 echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available" 115 return 1 116 fi 117 118 pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/') 119 if [ "${pahole_ver}" -lt "116" ]; then 120 echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.16" 121 return 1 122 fi 123 124 info BTF "${btf_data}" 125 LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1} 126 127 # Create ${btf_data} which contains just .BTF section but no symbols. Add 128 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all 129 # deletes all symbols including __start_BTF and __stop_BTF, which will 130 # be redefined in the linker script. Add 2>/dev/null to suppress GNU 131 # objcopy warnings: "empty loadable segment detected at ..." 132 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \ 133 --strip-all ${1} "${btf_data}" 2>/dev/null 134 # Change e_type to ET_REL so that it can be used to link final vmlinux. 135 # GNU ld 2.35+ and lld do not allow an ET_EXEC input. 136 if is_enabled CONFIG_CPU_BIG_ENDIAN; then 137 et_rel='\0\1' 138 else 139 et_rel='\1\0' 140 fi 141 printf "${et_rel}" | dd of="${btf_data}" conv=notrunc bs=1 seek=16 status=none 142 143 btf_vmlinux_bin_o=${btf_data} 144} 145 146# Create ${2}.o file with all symbols from the ${1} object file 147kallsyms() 148{ 149 local kallsymopt; 150 151 if is_enabled CONFIG_KALLSYMS_ALL; then 152 kallsymopt="${kallsymopt} --all-symbols" 153 fi 154 155 if is_enabled CONFIG_KALLSYMS_ABSOLUTE_PERCPU; then 156 kallsymopt="${kallsymopt} --absolute-percpu" 157 fi 158 159 if is_enabled CONFIG_LTO_CLANG; then 160 kallsymopt="${kallsymopt} --lto-clang" 161 fi 162 163 info KSYMS "${2}.S" 164 scripts/kallsyms ${kallsymopt} "${1}" > "${2}.S" 165 166 info AS "${2}.o" 167 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \ 168 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} -c -o "${2}.o" "${2}.S" 169 170 kallsymso=${2}.o 171} 172 173# Perform kallsyms for the given temporary vmlinux. 174sysmap_and_kallsyms() 175{ 176 mksysmap "${1}" "${1}.syms" 177 kallsyms "${1}.syms" "${1}.kallsyms" 178 179 kallsyms_sysmap=${1}.syms 180} 181 182# Create map file with all symbols from ${1} 183# See mksymap for additional details 184mksysmap() 185{ 186 info NM ${2} 187 ${NM} -n "${1}" | sed -f "${srctree}/scripts/mksysmap" > "${2}" 188} 189 190sorttable() 191{ 192 ${objtree}/scripts/sorttable ${1} 193} 194 195cleanup() 196{ 197 rm -f .btf.* 198 rm -f System.map 199 rm -f vmlinux 200 rm -f vmlinux.map 201} 202 203# Use "make V=1" to debug this script 204case "${KBUILD_VERBOSE}" in 205*1*) 206 set -x 207 ;; 208esac 209 210if [ "$1" = "clean" ]; then 211 cleanup 212 exit 0 213fi 214 215${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init init/version-timestamp.o 216 217btf_vmlinux_bin_o= 218kallsymso= 219strip_debug= 220 221if is_enabled CONFIG_KALLSYMS; then 222 kallsyms /dev/null .tmp_vmlinux0.kallsyms 223fi 224 225if is_enabled CONFIG_KALLSYMS || is_enabled CONFIG_DEBUG_INFO_BTF; then 226 227 # The kallsyms linking does not need debug symbols, but the BTF does. 228 if ! is_enabled CONFIG_DEBUG_INFO_BTF; then 229 strip_debug=1 230 fi 231 232 vmlinux_link .tmp_vmlinux1 233fi 234 235if is_enabled CONFIG_DEBUG_INFO_BTF; then 236 if ! gen_btf .tmp_vmlinux1; then 237 echo >&2 "Failed to generate BTF for vmlinux" 238 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF" 239 exit 1 240 fi 241fi 242 243if is_enabled CONFIG_KALLSYMS; then 244 245 # kallsyms support 246 # Generate section listing all symbols and add it into vmlinux 247 # It's a four step process: 248 # 0) Generate a dummy __kallsyms with empty symbol list. 249 # 1) Link .tmp_vmlinux.kallsyms1 so it has all symbols and sections, 250 # with a dummy __kallsyms. 251 # Running kallsyms on that gives us .tmp_kallsyms1.o with 252 # the right size 253 # 2) Link .tmp_vmlinux.kallsyms2 so it now has a __kallsyms section of 254 # the right size, but due to the added section, some 255 # addresses have shifted. 256 # From here, we generate a correct .tmp_vmlinux.kallsyms2.o 257 # 3) That link may have expanded the kernel image enough that 258 # more linker branch stubs / trampolines had to be added, which 259 # introduces new names, which further expands kallsyms. Do another 260 # pass if that is the case. In theory it's possible this results 261 # in even more stubs, but unlikely. 262 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around 263 # other bugs. 264 # 4) The correct ${kallsymso} is linked into the final vmlinux. 265 # 266 # a) Verify that the System.map from vmlinux matches the map from 267 # ${kallsymso}. 268 269 # The kallsyms linking does not need debug symbols included. 270 strip_debug=1 271 272 sysmap_and_kallsyms .tmp_vmlinux1 273 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 274 275 vmlinux_link .tmp_vmlinux2 276 sysmap_and_kallsyms .tmp_vmlinux2 277 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 278 279 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then 280 vmlinux_link .tmp_vmlinux3 281 sysmap_and_kallsyms .tmp_vmlinux3 282 fi 283fi 284 285strip_debug= 286 287vmlinux_link vmlinux 288 289# fill in BTF IDs 290if is_enabled CONFIG_DEBUG_INFO_BTF && is_enabled CONFIG_BPF; then 291 info BTFIDS vmlinux 292 ${RESOLVE_BTFIDS} vmlinux 293fi 294 295mksysmap vmlinux System.map 296 297if is_enabled CONFIG_BUILDTIME_TABLE_SORT; then 298 info SORTTAB vmlinux 299 if ! sorttable vmlinux; then 300 echo >&2 Failed to sort kernel tables 301 exit 1 302 fi 303fi 304 305# step a (see comment above) 306if is_enabled CONFIG_KALLSYMS; then 307 if ! cmp -s System.map "${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