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 ${output} 59 60 # skip output file argument 61 shift 62 63 if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then 64 # Use vmlinux.o instead of performing the slow LTO link again. 65 objs=vmlinux.o 66 libs= 67 else 68 objs=vmlinux.a 69 libs="${KBUILD_VMLINUX_LIBS}" 70 fi 71 72 if is_enabled CONFIG_GENERIC_BUILTIN_DTB; then 73 objs="${objs} .builtin-dtbs.o" 74 fi 75 76 objs="${objs} .vmlinux.export.o" 77 objs="${objs} init/version-timestamp.o" 78 79 if [ "${SRCARCH}" = "um" ]; then 80 wl=-Wl, 81 ld="${CC}" 82 ldflags="${CFLAGS_vmlinux}" 83 ldlibs="-lutil -lrt -lpthread" 84 else 85 wl= 86 ld="${LD}" 87 ldflags="${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}" 88 ldlibs= 89 fi 90 91 ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}" 92 93 # The kallsyms linking does not need debug symbols included. 94 if [ -n "${strip_debug}" ] ; then 95 ldflags="${ldflags} ${wl}--strip-debug" 96 fi 97 98 if [ -n "${generate_map}" ]; then 99 ldflags="${ldflags} ${wl}-Map=vmlinux.map" 100 fi 101 102 ${ld} ${ldflags} -o ${output} \ 103 ${wl}--whole-archive ${objs} ${wl}--no-whole-archive \ 104 ${wl}--start-group ${libs} ${wl}--end-group \ 105 ${kallsymso} ${btf_vmlinux_bin_o} ${arch_vmlinux_o} ${ldlibs} 106} 107 108# generate .BTF typeinfo from DWARF debuginfo 109# ${1} - vmlinux image 110gen_btf() 111{ 112 local btf_data=${1}.btf.o 113 114 info BTF "${btf_data}" 115 LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1} 116 117 # Create ${btf_data} which contains just .BTF section but no symbols. Add 118 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all 119 # deletes all symbols including __start_BTF and __stop_BTF, which will 120 # be redefined in the linker script. Add 2>/dev/null to suppress GNU 121 # objcopy warnings: "empty loadable segment detected at ..." 122 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \ 123 --strip-all ${1} "${btf_data}" 2>/dev/null 124 # Change e_type to ET_REL so that it can be used to link final vmlinux. 125 # GNU ld 2.35+ and lld do not allow an ET_EXEC input. 126 if is_enabled CONFIG_CPU_BIG_ENDIAN; then 127 et_rel='\0\1' 128 else 129 et_rel='\1\0' 130 fi 131 printf "${et_rel}" | dd of="${btf_data}" conv=notrunc bs=1 seek=16 status=none 132 133 btf_vmlinux_bin_o=${btf_data} 134} 135 136# Create ${2}.o file with all symbols from the ${1} object file 137kallsyms() 138{ 139 local kallsymopt; 140 141 if is_enabled CONFIG_KALLSYMS_ALL; then 142 kallsymopt="${kallsymopt} --all-symbols" 143 fi 144 145 info KSYMS "${2}.S" 146 scripts/kallsyms ${kallsymopt} "${1}" > "${2}.S" 147 148 info AS "${2}.o" 149 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \ 150 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} -c -o "${2}.o" "${2}.S" 151 152 kallsymso=${2}.o 153} 154 155# Perform kallsyms for the given temporary vmlinux. 156sysmap_and_kallsyms() 157{ 158 mksysmap "${1}" "${1}.syms" 159 kallsyms "${1}.syms" "${1}.kallsyms" 160 161 kallsyms_sysmap=${1}.syms 162} 163 164# Create map file with all symbols from ${1} 165# See mksymap for additional details 166mksysmap() 167{ 168 info NM ${2} 169 ${NM} -n "${1}" | sed -f "${srctree}/scripts/mksysmap" > "${2}" 170} 171 172sorttable() 173{ 174 ${NM} -S ${1} > .tmp_vmlinux.nm-sort 175 ${objtree}/scripts/sorttable -s .tmp_vmlinux.nm-sort ${1} 176} 177 178cleanup() 179{ 180 rm -f .btf.* 181 rm -f .tmp_vmlinux.nm-sort 182 rm -f System.map 183 rm -f vmlinux 184 rm -f vmlinux.map 185} 186 187# Use "make V=1" to debug this script 188case "${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 "${srctree}/scripts/Makefile.build" obj=init init/version-timestamp.o 200 201arch_vmlinux_o= 202if is_enabled CONFIG_ARCH_WANTS_PRE_LINK_VMLINUX; then 203 arch_vmlinux_o=arch/${SRCARCH}/tools/vmlinux.arch.o 204fi 205 206btf_vmlinux_bin_o= 207kallsymso= 208strip_debug= 209generate_map= 210 211if is_enabled CONFIG_KALLSYMS; then 212 true > .tmp_vmlinux0.syms 213 kallsyms .tmp_vmlinux0.syms .tmp_vmlinux0.kallsyms 214fi 215 216if is_enabled CONFIG_KALLSYMS || is_enabled CONFIG_DEBUG_INFO_BTF; then 217 218 # The kallsyms linking does not need debug symbols, but the BTF does. 219 if ! is_enabled CONFIG_DEBUG_INFO_BTF; then 220 strip_debug=1 221 fi 222 223 vmlinux_link .tmp_vmlinux1 224fi 225 226if is_enabled CONFIG_DEBUG_INFO_BTF; then 227 if ! gen_btf .tmp_vmlinux1; then 228 echo >&2 "Failed to generate BTF for vmlinux" 229 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF" 230 exit 1 231 fi 232fi 233 234if is_enabled CONFIG_KALLSYMS; then 235 236 # kallsyms support 237 # Generate section listing all symbols and add it into vmlinux 238 # It's a four step process: 239 # 0) Generate a dummy __kallsyms with empty symbol list. 240 # 1) Link .tmp_vmlinux1.kallsyms so it has all symbols and sections, 241 # with a dummy __kallsyms. 242 # Running kallsyms on that gives us .tmp_vmlinux1.kallsyms.o with 243 # the right size 244 # 2) Link .tmp_vmlinux2.kallsyms so it now has a __kallsyms section of 245 # the right size, but due to the added section, some 246 # addresses have shifted. 247 # From here, we generate a correct .tmp_vmlinux2.kallsyms.o 248 # 3) That link may have expanded the kernel image enough that 249 # more linker branch stubs / trampolines had to be added, which 250 # introduces new names, which further expands kallsyms. Do another 251 # pass if that is the case. In theory it's possible this results 252 # in even more stubs, but unlikely. 253 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around 254 # other bugs. 255 # 4) The correct ${kallsymso} is linked into the final vmlinux. 256 # 257 # a) Verify that the System.map from vmlinux matches the map from 258 # ${kallsymso}. 259 260 # The kallsyms linking does not need debug symbols included. 261 strip_debug=1 262 263 sysmap_and_kallsyms .tmp_vmlinux1 264 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 265 266 vmlinux_link .tmp_vmlinux2 267 sysmap_and_kallsyms .tmp_vmlinux2 268 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 269 270 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then 271 vmlinux_link .tmp_vmlinux3 272 sysmap_and_kallsyms .tmp_vmlinux3 273 fi 274fi 275 276strip_debug= 277 278if is_enabled CONFIG_VMLINUX_MAP; then 279 generate_map=1 280fi 281 282vmlinux_link "${VMLINUX}" 283 284# fill in BTF IDs 285if is_enabled CONFIG_DEBUG_INFO_BTF; then 286 info BTFIDS "${VMLINUX}" 287 RESOLVE_BTFIDS_ARGS="" 288 if is_enabled CONFIG_WERROR; then 289 RESOLVE_BTFIDS_ARGS=" --fatal_warnings " 290 fi 291 ${RESOLVE_BTFIDS} ${RESOLVE_BTFIDS_ARGS} "${VMLINUX}" 292fi 293 294mksysmap "${VMLINUX}" System.map 295 296if is_enabled CONFIG_BUILDTIME_TABLE_SORT; then 297 info SORTTAB "${VMLINUX}" 298 if ! sorttable "${VMLINUX}"; then 299 echo >&2 Failed to sort kernel tables 300 exit 1 301 fi 302fi 303 304# step a (see comment above) 305if is_enabled CONFIG_KALLSYMS; then 306 if ! cmp -s System.map "${kallsyms_sysmap}"; then 307 echo >&2 Inconsistent kallsyms data 308 echo >&2 'Try "make KALLSYMS_EXTRA_PASS=1" as a workaround' 309 exit 1 310 fi 311fi 312 313# For fixdep 314echo "${VMLINUX}: $0" > ".${VMLINUX}.d" 315