1#!/bin/sh 2# SPDX-License-Identifier: GPL-2.0 3# 4# link vmlinux 5# 6# vmlinux is linked from the objects selected by $(KBUILD_VMLINUX_OBJS) and 7# $(KBUILD_VMLINUX_LIBS). Most are built-in.a files from top-level directories 8# in the kernel tree, others are specified in arch/$(ARCH)/Makefile. 9# $(KBUILD_VMLINUX_LIBS) are archives which are linked conditionally 10# (not within --whole-archive), and do not require symbol indexes added. 11# 12# vmlinux 13# ^ 14# | 15# +--< $(KBUILD_VMLINUX_OBJS) 16# | +--< init/built-in.a drivers/built-in.a mm/built-in.a + more 17# | 18# +--< $(KBUILD_VMLINUX_LIBS) 19# | +--< lib/lib.a + more 20# | 21# +-< ${kallsymso} (see description in KALLSYMS section) 22# 23# vmlinux version (uname -v) cannot be updated during normal 24# descending-into-subdirs phase since we do not yet know if we need to 25# update vmlinux. 26# Therefore this step is delayed until just before final link of vmlinux. 27# 28# System.map is generated to document addresses of all kernel symbols 29 30# Error out on error 31set -e 32 33LD="$1" 34KBUILD_LDFLAGS="$2" 35LDFLAGS_vmlinux="$3" 36 37is_enabled() { 38 grep -q "^$1=y" include/config/auto.conf 39} 40 41# Nice output in kbuild format 42# Will be supressed by "make -s" 43info() 44{ 45 printf " %-7s %s\n" "${1}" "${2}" 46} 47 48# Generate a linker script to ensure correct ordering of initcalls. 49gen_initcalls() 50{ 51 info GEN .tmp_initcalls.lds 52 53 ${PYTHON3} ${srctree}/scripts/jobserver-exec \ 54 ${PERL} ${srctree}/scripts/generate_initcall_order.pl \ 55 ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS} \ 56 > .tmp_initcalls.lds 57} 58 59# If CONFIG_LTO_CLANG is selected, collect generated symbol versions into 60# .tmp_symversions.lds 61gen_symversions() 62{ 63 info GEN .tmp_symversions.lds 64 rm -f .tmp_symversions.lds 65 66 for o in ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS}; do 67 if [ -f ${o}.symversions ]; then 68 cat ${o}.symversions >> .tmp_symversions.lds 69 fi 70 done 71} 72 73# Link of vmlinux.o used for section mismatch analysis 74# ${1} output file 75modpost_link() 76{ 77 local objects 78 local lds="" 79 80 objects="--whole-archive \ 81 ${KBUILD_VMLINUX_OBJS} \ 82 --no-whole-archive \ 83 --start-group \ 84 ${KBUILD_VMLINUX_LIBS} \ 85 --end-group" 86 87 if is_enabled CONFIG_LTO_CLANG; then 88 gen_initcalls 89 lds="-T .tmp_initcalls.lds" 90 91 if is_enabled CONFIG_MODVERSIONS; then 92 gen_symversions 93 lds="${lds} -T .tmp_symversions.lds" 94 fi 95 96 # This might take a while, so indicate that we're doing 97 # an LTO link 98 info LTO ${1} 99 else 100 info LD ${1} 101 fi 102 103 ${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${lds} ${objects} 104} 105 106objtool_link() 107{ 108 local objtoolcmd; 109 local objtoolopt; 110 111 if is_enabled CONFIG_STACK_VALIDATION && \ 112 ( is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT ); then 113 114 # Don't perform vmlinux validation unless explicitly requested, 115 # but run objtool on vmlinux.o now that we have an object file. 116 if is_enabled CONFIG_UNWINDER_ORC; then 117 objtoolcmd="orc generate" 118 fi 119 120 objtoolopt="${objtoolopt} --lto" 121 122 if is_enabled CONFIG_X86_KERNEL_IBT; then 123 objtoolopt="${objtoolopt} --ibt" 124 fi 125 126 if is_enabled CONFIG_FTRACE_MCOUNT_USE_OBJTOOL; then 127 objtoolopt="${objtoolopt} --mcount" 128 fi 129 fi 130 131 if is_enabled CONFIG_VMLINUX_VALIDATION; then 132 objtoolopt="${objtoolopt} --noinstr" 133 fi 134 135 if [ -n "${objtoolopt}" ]; then 136 if [ -z "${objtoolcmd}" ]; then 137 objtoolcmd="check" 138 fi 139 objtoolopt="${objtoolopt} --vmlinux" 140 if ! is_enabled CONFIG_FRAME_POINTER; then 141 objtoolopt="${objtoolopt} --no-fp" 142 fi 143 if is_enabled CONFIG_GCOV_KERNEL; then 144 objtoolopt="${objtoolopt} --no-unreachable" 145 fi 146 if is_enabled CONFIG_RETPOLINE; then 147 objtoolopt="${objtoolopt} --retpoline" 148 fi 149 if is_enabled CONFIG_X86_SMAP; then 150 objtoolopt="${objtoolopt} --uaccess" 151 fi 152 if is_enabled CONFIG_SLS; then 153 objtoolopt="${objtoolopt} --sls" 154 fi 155 info OBJTOOL ${1} 156 tools/objtool/objtool ${objtoolcmd} ${objtoolopt} ${1} 157 fi 158} 159 160# Link of vmlinux 161# ${1} - output file 162# ${2}, ${3}, ... - optional extra .o files 163vmlinux_link() 164{ 165 local output=${1} 166 local objs 167 local libs 168 local ld 169 local ldflags 170 local ldlibs 171 172 info LD ${output} 173 174 # skip output file argument 175 shift 176 177 if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then 178 # Use vmlinux.o instead of performing the slow LTO link again. 179 objs=vmlinux.o 180 libs= 181 else 182 objs="${KBUILD_VMLINUX_OBJS}" 183 libs="${KBUILD_VMLINUX_LIBS}" 184 fi 185 186 if [ "${SRCARCH}" = "um" ]; then 187 wl=-Wl, 188 ld="${CC}" 189 ldflags="${CFLAGS_vmlinux}" 190 ldlibs="-lutil -lrt -lpthread" 191 else 192 wl= 193 ld="${LD}" 194 ldflags="${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}" 195 ldlibs= 196 fi 197 198 ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}" 199 200 # The kallsyms linking does not need debug symbols included. 201 if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then 202 ldflags="${ldflags} ${wl}--strip-debug" 203 fi 204 205 if is_enabled CONFIG_VMLINUX_MAP; then 206 ldflags="${ldflags} ${wl}-Map=${output}.map" 207 fi 208 209 ${ld} ${ldflags} -o ${output} \ 210 ${wl}--whole-archive ${objs} ${wl}--no-whole-archive \ 211 ${wl}--start-group ${libs} ${wl}--end-group \ 212 $@ ${ldlibs} 213} 214 215# generate .BTF typeinfo from DWARF debuginfo 216# ${1} - vmlinux image 217# ${2} - file to dump raw BTF data into 218gen_btf() 219{ 220 local pahole_ver 221 222 if ! [ -x "$(command -v ${PAHOLE})" ]; then 223 echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available" 224 return 1 225 fi 226 227 pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/') 228 if [ "${pahole_ver}" -lt "116" ]; then 229 echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.16" 230 return 1 231 fi 232 233 vmlinux_link ${1} 234 235 info "BTF" ${2} 236 LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1} 237 238 # Create ${2} which contains just .BTF section but no symbols. Add 239 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all 240 # deletes all symbols including __start_BTF and __stop_BTF, which will 241 # be redefined in the linker script. Add 2>/dev/null to suppress GNU 242 # objcopy warnings: "empty loadable segment detected at ..." 243 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \ 244 --strip-all ${1} ${2} 2>/dev/null 245 # Change e_type to ET_REL so that it can be used to link final vmlinux. 246 # Unlike GNU ld, lld does not allow an ET_EXEC input. 247 printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none 248} 249 250# Create ${2} .S file with all symbols from the ${1} object file 251kallsyms() 252{ 253 local kallsymopt; 254 255 if is_enabled CONFIG_KALLSYMS_ALL; then 256 kallsymopt="${kallsymopt} --all-symbols" 257 fi 258 259 if is_enabled CONFIG_KALLSYMS_ABSOLUTE_PERCPU; then 260 kallsymopt="${kallsymopt} --absolute-percpu" 261 fi 262 263 if is_enabled CONFIG_KALLSYMS_BASE_RELATIVE; then 264 kallsymopt="${kallsymopt} --base-relative" 265 fi 266 267 info KSYMS ${2} 268 ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${2} 269} 270 271# Perform one step in kallsyms generation, including temporary linking of 272# vmlinux. 273kallsyms_step() 274{ 275 kallsymso_prev=${kallsymso} 276 kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1} 277 kallsymso=${kallsyms_vmlinux}.o 278 kallsyms_S=${kallsyms_vmlinux}.S 279 280 vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o} 281 kallsyms ${kallsyms_vmlinux} ${kallsyms_S} 282 283 info AS ${kallsyms_S} 284 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \ 285 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \ 286 -c -o ${kallsymso} ${kallsyms_S} 287} 288 289# Create map file with all symbols from ${1} 290# See mksymap for additional details 291mksysmap() 292{ 293 ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2} 294} 295 296sorttable() 297{ 298 ${objtree}/scripts/sorttable ${1} 299} 300 301# Delete output files in case of error 302cleanup() 303{ 304 rm -f .btf.* 305 rm -f .tmp_System.map 306 rm -f .tmp_initcalls.lds 307 rm -f .tmp_symversions.lds 308 rm -f .tmp_vmlinux* 309 rm -f System.map 310 rm -f vmlinux 311 rm -f vmlinux.map 312 rm -f vmlinux.o 313 rm -f .vmlinux.d 314} 315 316# Use "make V=1" to debug this script 317case "${KBUILD_VERBOSE}" in 318*1*) 319 set -x 320 ;; 321esac 322 323if [ "$1" = "clean" ]; then 324 cleanup 325 exit 0 326fi 327 328# Update version 329info GEN .version 330if [ -r .version ]; then 331 VERSION=$(expr 0$(cat .version) + 1) 332 echo $VERSION > .version 333else 334 rm -f .version 335 echo 1 > .version 336fi; 337 338# final build of init/ 339${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1 340 341#link vmlinux.o 342modpost_link vmlinux.o 343objtool_link vmlinux.o 344 345# modpost vmlinux.o to check for section mismatches 346${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1 347 348info MODINFO modules.builtin.modinfo 349${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo 350info GEN modules.builtin 351# The second line aids cases where multiple modules share the same object. 352tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' | 353 tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin 354 355btf_vmlinux_bin_o="" 356if is_enabled CONFIG_DEBUG_INFO_BTF; then 357 btf_vmlinux_bin_o=.btf.vmlinux.bin.o 358 if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then 359 echo >&2 "Failed to generate BTF for vmlinux" 360 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF" 361 exit 1 362 fi 363fi 364 365kallsymso="" 366kallsymso_prev="" 367kallsyms_vmlinux="" 368if is_enabled CONFIG_KALLSYMS; then 369 370 # kallsyms support 371 # Generate section listing all symbols and add it into vmlinux 372 # It's a three step process: 373 # 1) Link .tmp_vmlinux.kallsyms1 so it has all symbols and sections, 374 # but __kallsyms is empty. 375 # Running kallsyms on that gives us .tmp_kallsyms1.o with 376 # the right size 377 # 2) Link .tmp_vmlinux.kallsyms2 so it now has a __kallsyms section of 378 # the right size, but due to the added section, some 379 # addresses have shifted. 380 # From here, we generate a correct .tmp_vmlinux.kallsyms2.o 381 # 3) That link may have expanded the kernel image enough that 382 # more linker branch stubs / trampolines had to be added, which 383 # introduces new names, which further expands kallsyms. Do another 384 # pass if that is the case. In theory it's possible this results 385 # in even more stubs, but unlikely. 386 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around 387 # other bugs. 388 # 4) The correct ${kallsymso} is linked into the final vmlinux. 389 # 390 # a) Verify that the System.map from vmlinux matches the map from 391 # ${kallsymso}. 392 393 kallsyms_step 1 394 kallsyms_step 2 395 396 # step 3 397 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev}) 398 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 399 400 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then 401 kallsyms_step 3 402 fi 403fi 404 405vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o} 406 407# fill in BTF IDs 408if is_enabled CONFIG_DEBUG_INFO_BTF && is_enabled CONFIG_BPF; then 409 info BTFIDS vmlinux 410 ${RESOLVE_BTFIDS} vmlinux 411fi 412 413info SYSMAP System.map 414mksysmap vmlinux System.map 415 416if is_enabled CONFIG_BUILDTIME_TABLE_SORT; then 417 info SORTTAB vmlinux 418 if ! sorttable vmlinux; then 419 echo >&2 Failed to sort kernel tables 420 exit 1 421 fi 422fi 423 424# step a (see comment above) 425if is_enabled CONFIG_KALLSYMS; then 426 mksysmap ${kallsyms_vmlinux} .tmp_System.map 427 428 if ! cmp -s System.map .tmp_System.map; then 429 echo >&2 Inconsistent kallsyms data 430 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround 431 exit 1 432 fi 433fi 434 435# For fixdep 436echo "vmlinux: $0" > .vmlinux.d 437