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 "^$1=y" include/config/auto.conf 38} 39 40# Nice output in kbuild format 41# Will be suppressed by "make -s" 42info() 43{ 44 printf " %-7s %s\n" "${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} ${wl}--strip-debug" 97 fi 98 99 # Only the final link actually requires the relocations. 100 if [ "${output}" = "${VMLINUX}" ] && is_enabled CONFIG_ARCH_VMLINUX_NEEDS_RELOCS; then 101 ldflags="${ldflags} ${wl}--emit-relocs" 102 fi 103 104 if [ -n "${generate_map}" ]; then 105 ldflags="${ldflags} ${wl}-Map=vmlinux.map" 106 fi 107 108 ${ld} ${ldflags} -o ${output} \ 109 ${wl}--whole-archive ${objs} ${wl}--no-whole-archive \ 110 ${wl}--start-group ${libs} ${wl}--end-group \ 111 ${kallsymso} ${btf_vmlinux_bin_o} ${arch_vmlinux_o} ${ldlibs} 112} 113 114# Check if kallsymso_prev and kallsymso differ 115# If symbol sizes within ${kallsymso} change, any symbols within vmlinux are 116# likely to shift, invalidating ${kallsymso}. 117# Since file size can remain unchanged even if symbol sizes change, compare the 118# actual symbols instead of relying on file size only. 119kallsymso_changed() 120{ 121 ${NM} -n "${kallsymso_prev}" > "${kallsymso_prev}.sym" 122 ${NM} -n "${kallsymso}" > "${kallsymso}.sym" 123 ! cmp -s "${kallsymso_prev}.sym" "${kallsymso}.sym" 124} 125 126# Create ${2}.o with the kallsyms tables for ${1} (the vmlinux, or an empty 127# listing for the first pass); list the symbols used in ${3} if given. 128kallsyms() 129{ 130 local kallsymopt; 131 132 if [ -n "${3:-}" ]; then 133 kallsymopt="--sysmap=${3}" 134 fi 135 if is_enabled CONFIG_KALLSYMS_ALL; then 136 kallsymopt="${kallsymopt} --all-symbols" 137 fi 138 139 if is_enabled CONFIG_64BIT || is_enabled CONFIG_RELOCATABLE; then 140 kallsymopt="${kallsymopt} --pc-relative" 141 fi 142 143 info KSYMS "${2}.S" 144 scripts/kallsyms ${kallsymopt} "${1}" "${2}.bin" > "${2}.S" 145 146 info AS "${2}.o" 147 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \ 148 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} -c -o "${2}.o" "${2}.S" 149 150 kallsymso_prev="${kallsymso:-}" 151 kallsymso=${2}.o 152} 153 154# Perform kallsyms for the given temporary vmlinux. 155sysmap_and_kallsyms() 156{ 157 kallsyms "${1}" "${1}.kallsyms" "${1}.syms" 158 kallsyms_sysmap=${1}.syms 159} 160 161# Create map file with all symbols from ${1} 162mksysmap() 163{ 164 info SYSMAP ${2} 165 scripts/kallsyms --sysmap="${2}" "${1}" 166} 167 168sorttable() 169{ 170 ${NM} -p -S ${1} > .tmp_vmlinux.nm-sort 171 ${objtree}/scripts/sorttable -s .tmp_vmlinux.nm-sort ${1} 172} 173 174cleanup() 175{ 176 rm -f .btf.* 177 rm -f .tmp_vmlinux.nm-sort 178 rm -f System.map 179 rm -f vmlinux 180 rm -f vmlinux.map 181} 182 183# Use "make V=1" to debug this script 184case "${KBUILD_VERBOSE}" in 185*1*) 186 set -x 187 ;; 188esac 189 190if [ "$1" = "clean" ]; then 191 cleanup 192 exit 0 193fi 194 195${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init init/version-timestamp.o 196 197arch_vmlinux_o= 198if is_enabled CONFIG_ARCH_WANTS_PRE_LINK_VMLINUX; then 199 arch_vmlinux_o=arch/${SRCARCH}/tools/vmlinux.arch.o 200fi 201 202btf_vmlinux_bin_o= 203btfids_vmlinux= 204kallsymso= 205strip_debug= 206generate_map= 207 208# Use "make UT=1" to trigger warnings on unused tracepoints 209case "${WARN_ON_UNUSED_TRACEPOINTS}" in 210*1*) 211 ${objtree}/scripts/tracepoint-update vmlinux.o 212 ;; 213esac 214 215if is_enabled CONFIG_KALLSYMS; then 216 true > .tmp_vmlinux0.syms 217 kallsyms .tmp_vmlinux0.syms .tmp_vmlinux0.kallsyms 218fi 219 220if is_enabled CONFIG_KALLSYMS || is_enabled CONFIG_DEBUG_INFO_BTF; then 221 222 # The kallsyms linking does not need debug symbols, but the BTF does. 223 if ! is_enabled CONFIG_DEBUG_INFO_BTF; then 224 strip_debug=1 225 fi 226 227 vmlinux_link .tmp_vmlinux1 228fi 229 230if is_enabled CONFIG_DEBUG_INFO_BTF; then 231 info BTF .tmp_vmlinux1 232 if ! ${CONFIG_SHELL} ${srctree}/scripts/gen-btf.sh .tmp_vmlinux1; then 233 echo >&2 "Failed to generate BTF for vmlinux" 234 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF" 235 exit 1 236 fi 237 btf_vmlinux_bin_o=.tmp_vmlinux1.btf.o 238 btfids_vmlinux=.tmp_vmlinux1.BTF_ids 239fi 240 241if is_enabled CONFIG_KALLSYMS; then 242 243 # kallsyms support 244 # Generate section listing all symbols and add it into vmlinux 245 # It's a four step process: 246 # 0) Generate a dummy __kallsyms with empty symbol list. 247 # 1) Link .tmp_vmlinux1.kallsyms so it has all symbols and sections, 248 # with a dummy __kallsyms. 249 # Running kallsyms on that gives us .tmp_vmlinux1.kallsyms.o with 250 # the right size 251 # 2) Link .tmp_vmlinux2.kallsyms so it now has a __kallsyms section of 252 # the right size, but due to the added section, some 253 # addresses have shifted. 254 # From here, we generate a correct .tmp_vmlinux2.kallsyms.o 255 # 3) That link may have expanded the kernel image enough that 256 # more linker branch stubs / trampolines had to be added, which 257 # introduces new names, which further expands kallsyms. Do another 258 # pass if that is the case. In theory it's possible this results 259 # in even more stubs, but unlikely. 260 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around 261 # other bugs. 262 # 4) The correct ${kallsymso} is linked into the final vmlinux. 263 # 264 # a) Verify that the System.map from vmlinux matches the map from 265 # ${kallsymso}. 266 267 # The kallsyms linking does not need debug symbols included. 268 strip_debug=1 269 270 sysmap_and_kallsyms .tmp_vmlinux1 271 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 272 273 vmlinux_link .tmp_vmlinux2 274 sysmap_and_kallsyms .tmp_vmlinux2 275 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 276 277 # Due to alignment, file size of the kallsymso object file might remain 278 # unchanged even if individual symbols within change size. Changed 279 # symbol sizes can still shift other symbols, though. Therefore, don't 280 # rely on file size alone. 281 if [ $size1 -ne $size2 ] || kallsymso_changed || \ 282 [ -n "${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 296if is_enabled CONFIG_DEBUG_INFO_BTF; then 297 info BTFIDS ${VMLINUX} 298 ${RESOLVE_BTFIDS} --patch_btfids ${btfids_vmlinux} ${VMLINUX} 299fi 300 301mksysmap "${VMLINUX}" System.map 302 303if is_enabled CONFIG_BUILDTIME_TABLE_SORT; then 304 info SORTTAB "${VMLINUX}" 305 if ! sorttable "${VMLINUX}"; then 306 echo >&2 Failed to sort kernel tables 307 exit 1 308 fi 309fi 310 311# step a (see comment above) 312if is_enabled CONFIG_KALLSYMS; then 313 if ! cmp -s System.map "${kallsyms_sysmap}"; then 314 echo >&2 Inconsistent kallsyms data 315 echo >&2 'Try "make KALLSYMS_EXTRA_PASS=1" as a workaround' 316 exit 1 317 fi 318fi 319 320# For fixdep 321echo "${VMLINUX}: $0" > ".${VMLINUX}.d" 322