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 ${output} 59 60 # skip output file argument 61 shift 62 63 if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT || 64 is_enabled CONFIG_KLP_BUILD; then 65 # Use vmlinux.o instead of performing the slow LTO link again. 66 objs=vmlinux.o 67 libs= 68 else 69 objs=vmlinux.a 70 libs="${KBUILD_VMLINUX_LIBS}" 71 fi 72 73 if is_enabled CONFIG_GENERIC_BUILTIN_DTB; then 74 objs="${objs} .builtin-dtbs.o" 75 fi 76 77 objs="${objs} .vmlinux.export.o" 78 objs="${objs} init/version-timestamp.o" 79 80 if [ "${SRCARCH}" = "um" ]; then 81 wl=-Wl, 82 ld="${CC}" 83 ldflags="${CFLAGS_vmlinux}" 84 ldlibs="-lutil -lrt -lpthread" 85 else 86 wl= 87 ld="${LD}" 88 ldflags="${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}" 89 ldlibs= 90 fi 91 92 ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}" 93 94 # The kallsyms linking does not need debug symbols included. 95 if [ -n "${strip_debug}" ] ; then 96 ldflags="${ldflags} ${wl}--strip-debug" 97 fi 98 99 if [ -n "${generate_map}" ]; then 100 ldflags="${ldflags} ${wl}-Map=vmlinux.map" 101 fi 102 103 ${ld} ${ldflags} -o ${output} \ 104 ${wl}--whole-archive ${objs} ${wl}--no-whole-archive \ 105 ${wl}--start-group ${libs} ${wl}--end-group \ 106 ${kallsymso} ${btf_vmlinux_bin_o} ${arch_vmlinux_o} ${ldlibs} 107} 108 109# generate .BTF typeinfo from DWARF debuginfo 110# ${1} - vmlinux image 111gen_btf() 112{ 113 local btf_data=${1}.btf.o 114 115 info BTF "${btf_data}" 116 LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1} 117 118 # Create ${btf_data} which contains just .BTF section but no symbols. Add 119 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all 120 # deletes all symbols including __start_BTF and __stop_BTF, which will 121 # be redefined in the linker script. Add 2>/dev/null to suppress GNU 122 # objcopy warnings: "empty loadable segment detected at ..." 123 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \ 124 --strip-all ${1} "${btf_data}" 2>/dev/null 125 # Change e_type to ET_REL so that it can be used to link final vmlinux. 126 # GNU ld 2.35+ and lld do not allow an ET_EXEC input. 127 if is_enabled CONFIG_CPU_BIG_ENDIAN; then 128 et_rel='\0\1' 129 else 130 et_rel='\1\0' 131 fi 132 printf "${et_rel}" | dd of="${btf_data}" conv=notrunc bs=1 seek=16 status=none 133 134 btf_vmlinux_bin_o=${btf_data} 135} 136 137# Create ${2}.o file with all symbols from the ${1} object file 138kallsyms() 139{ 140 local kallsymopt; 141 142 if is_enabled CONFIG_KALLSYMS_ALL; then 143 kallsymopt="${kallsymopt} --all-symbols" 144 fi 145 146 if is_enabled CONFIG_64BIT || is_enabled CONFIG_RELOCATABLE; then 147 kallsymopt="${kallsymopt} --pc-relative" 148 fi 149 150 info KSYMS "${2}.S" 151 scripts/kallsyms ${kallsymopt} "${1}" > "${2}.S" 152 153 info AS "${2}.o" 154 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \ 155 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} -c -o "${2}.o" "${2}.S" 156 157 kallsymso=${2}.o 158} 159 160# Perform kallsyms for the given temporary vmlinux. 161sysmap_and_kallsyms() 162{ 163 mksysmap "${1}" "${1}.syms" 164 kallsyms "${1}.syms" "${1}.kallsyms" 165 166 kallsyms_sysmap=${1}.syms 167} 168 169# Create map file with all symbols from ${1} 170# See mksymap for additional details 171mksysmap() 172{ 173 info NM ${2} 174 ${NM} -n "${1}" | sed -f "${srctree}/scripts/mksysmap" > "${2}" 175} 176 177sorttable() 178{ 179 ${NM} -S ${1} > .tmp_vmlinux.nm-sort 180 ${objtree}/scripts/sorttable -s .tmp_vmlinux.nm-sort ${1} 181} 182 183cleanup() 184{ 185 rm -f .btf.* 186 rm -f .tmp_vmlinux.nm-sort 187 rm -f System.map 188 rm -f vmlinux 189 rm -f vmlinux.map 190} 191 192# Use "make V=1" to debug this script 193case "${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= 215 216# Use "make UT=1" to trigger warnings on unused tracepoints 217case "${WARN_ON_UNUSED_TRACEPOINTS}" in 218*1*) 219 ${objtree}/scripts/tracepoint-update vmlinux.o 220 ;; 221esac 222 223if is_enabled CONFIG_KALLSYMS; then 224 true > .tmp_vmlinux0.syms 225 kallsyms .tmp_vmlinux0.syms .tmp_vmlinux0.kallsyms 226fi 227 228if is_enabled CONFIG_KALLSYMS || is_enabled CONFIG_DEBUG_INFO_BTF; then 229 230 # The kallsyms linking does not need debug symbols, but the BTF does. 231 if ! is_enabled CONFIG_DEBUG_INFO_BTF; then 232 strip_debug=1 233 fi 234 235 vmlinux_link .tmp_vmlinux1 236fi 237 238if is_enabled CONFIG_DEBUG_INFO_BTF; then 239 if ! gen_btf .tmp_vmlinux1; then 240 echo >&2 "Failed to generate BTF for vmlinux" 241 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF" 242 exit 1 243 fi 244fi 245 246if is_enabled CONFIG_KALLSYMS; then 247 248 # kallsyms support 249 # Generate section listing all symbols and add it into vmlinux 250 # It's a four step process: 251 # 0) Generate a dummy __kallsyms with empty symbol list. 252 # 1) Link .tmp_vmlinux1.kallsyms so it has all symbols and sections, 253 # with a dummy __kallsyms. 254 # Running kallsyms on that gives us .tmp_vmlinux1.kallsyms.o with 255 # the right size 256 # 2) Link .tmp_vmlinux2.kallsyms so it now has a __kallsyms section of 257 # the right size, but due to the added section, some 258 # addresses have shifted. 259 # From here, we generate a correct .tmp_vmlinux2.kallsyms.o 260 # 3) That link may have expanded the kernel image enough that 261 # more linker branch stubs / trampolines had to be added, which 262 # introduces new names, which further expands kallsyms. Do another 263 # pass if that is the case. In theory it's possible this results 264 # in even more stubs, but unlikely. 265 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around 266 # other bugs. 267 # 4) The correct ${kallsymso} is linked into the final vmlinux. 268 # 269 # a) Verify that the System.map from vmlinux matches the map from 270 # ${kallsymso}. 271 272 # The kallsyms linking does not need debug symbols included. 273 strip_debug=1 274 275 sysmap_and_kallsyms .tmp_vmlinux1 276 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 277 278 vmlinux_link .tmp_vmlinux2 279 sysmap_and_kallsyms .tmp_vmlinux2 280 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 281 282 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then 283 vmlinux_link .tmp_vmlinux3 284 sysmap_and_kallsyms .tmp_vmlinux3 285 fi 286fi 287 288strip_debug= 289 290if is_enabled CONFIG_VMLINUX_MAP; then 291 generate_map=1 292fi 293 294vmlinux_link "${VMLINUX}" 295 296# fill in BTF IDs 297if is_enabled CONFIG_DEBUG_INFO_BTF; then 298 info BTFIDS "${VMLINUX}" 299 RESOLVE_BTFIDS_ARGS="" 300 if is_enabled CONFIG_WERROR; then 301 RESOLVE_BTFIDS_ARGS=" --fatal_warnings " 302 fi 303 ${RESOLVE_BTFIDS} ${RESOLVE_BTFIDS_ARGS} "${VMLINUX}" 304fi 305 306mksysmap "${VMLINUX}" System.map 307 308if is_enabled CONFIG_BUILDTIME_TABLE_SORT; then 309 info SORTTAB "${VMLINUX}" 310 if ! sorttable "${VMLINUX}"; then 311 echo >&2 Failed to sort kernel tables 312 exit 1 313 fi 314fi 315 316# step a (see comment above) 317if is_enabled CONFIG_KALLSYMS; then 318 if ! cmp -s System.map "${kallsyms_sysmap}"; then 319 echo >&2 Inconsistent kallsyms data 320 echo >&2 'Try "make KALLSYMS_EXTRA_PASS=1" as a workaround' 321 exit 1 322 fi 323fi 324 325# For fixdep 326echo "${VMLINUX}: $0" > ".${VMLINUX}.d" 327