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 fi 94 95 # This might take a while, so indicate that we're doing 96 # an LTO link 97 info LTO ${1} 98 else 99 info LD ${1} 100 fi 101 102 ${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${lds} ${objects} 103} 104 105objtool_link() 106{ 107 local objtoolcmd; 108 local objtoolopt; 109 110 if is_enabled CONFIG_STACK_VALIDATION && \ 111 ( is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT ); then 112 113 # Don't perform vmlinux validation unless explicitly requested, 114 # but run objtool on vmlinux.o now that we have an object file. 115 if is_enabled CONFIG_UNWINDER_ORC; then 116 objtoolcmd="orc generate" 117 fi 118 119 objtoolopt="${objtoolopt} --lto" 120 121 if is_enabled CONFIG_X86_KERNEL_IBT; then 122 objtoolopt="${objtoolopt} --ibt" 123 fi 124 125 if is_enabled CONFIG_FTRACE_MCOUNT_USE_OBJTOOL; then 126 objtoolopt="${objtoolopt} --mcount" 127 fi 128 fi 129 130 if is_enabled CONFIG_VMLINUX_VALIDATION; then 131 objtoolopt="${objtoolopt} --noinstr" 132 fi 133 134 if [ -n "${objtoolopt}" ]; then 135 if [ -z "${objtoolcmd}" ]; then 136 objtoolcmd="check" 137 fi 138 objtoolopt="${objtoolopt} --vmlinux" 139 if ! is_enabled CONFIG_FRAME_POINTER; then 140 objtoolopt="${objtoolopt} --no-fp" 141 fi 142 if is_enabled CONFIG_GCOV_KERNEL || is_enabled CONFIG_LTO_CLANG; then 143 objtoolopt="${objtoolopt} --no-unreachable" 144 fi 145 if is_enabled CONFIG_RETPOLINE; then 146 objtoolopt="${objtoolopt} --retpoline" 147 fi 148 if is_enabled CONFIG_X86_SMAP; then 149 objtoolopt="${objtoolopt} --uaccess" 150 fi 151 if is_enabled CONFIG_SLS; then 152 objtoolopt="${objtoolopt} --sls" 153 fi 154 info OBJTOOL ${1} 155 tools/objtool/objtool ${objtoolcmd} ${objtoolopt} ${1} 156 fi 157} 158 159# Link of vmlinux 160# ${1} - output file 161# ${2}, ${3}, ... - optional extra .o files 162vmlinux_link() 163{ 164 local output=${1} 165 local objs 166 local libs 167 local ld 168 local ldflags 169 local ldlibs 170 171 info LD ${output} 172 173 # skip output file argument 174 shift 175 176 if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then 177 # Use vmlinux.o instead of performing the slow LTO link again. 178 objs=vmlinux.o 179 libs= 180 else 181 objs="${KBUILD_VMLINUX_OBJS}" 182 libs="${KBUILD_VMLINUX_LIBS}" 183 fi 184 185 if is_enabled CONFIG_MODULES; then 186 objs="${objs} .vmlinux.export.o" 187 fi 188 189 if [ "${SRCARCH}" = "um" ]; then 190 wl=-Wl, 191 ld="${CC}" 192 ldflags="${CFLAGS_vmlinux}" 193 ldlibs="-lutil -lrt -lpthread" 194 else 195 wl= 196 ld="${LD}" 197 ldflags="${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}" 198 ldlibs= 199 fi 200 201 ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}" 202 203 # The kallsyms linking does not need debug symbols included. 204 if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then 205 ldflags="${ldflags} ${wl}--strip-debug" 206 fi 207 208 if is_enabled CONFIG_VMLINUX_MAP; then 209 ldflags="${ldflags} ${wl}-Map=${output}.map" 210 fi 211 212 ${ld} ${ldflags} -o ${output} \ 213 ${wl}--whole-archive ${objs} ${wl}--no-whole-archive \ 214 ${wl}--start-group ${libs} ${wl}--end-group \ 215 $@ ${ldlibs} 216} 217 218# generate .BTF typeinfo from DWARF debuginfo 219# ${1} - vmlinux image 220# ${2} - file to dump raw BTF data into 221gen_btf() 222{ 223 local pahole_ver 224 225 if ! [ -x "$(command -v ${PAHOLE})" ]; then 226 echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available" 227 return 1 228 fi 229 230 pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/') 231 if [ "${pahole_ver}" -lt "116" ]; then 232 echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.16" 233 return 1 234 fi 235 236 vmlinux_link ${1} 237 238 info "BTF" ${2} 239 LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1} 240 241 # Create ${2} which contains just .BTF section but no symbols. Add 242 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all 243 # deletes all symbols including __start_BTF and __stop_BTF, which will 244 # be redefined in the linker script. Add 2>/dev/null to suppress GNU 245 # objcopy warnings: "empty loadable segment detected at ..." 246 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \ 247 --strip-all ${1} ${2} 2>/dev/null 248 # Change e_type to ET_REL so that it can be used to link final vmlinux. 249 # Unlike GNU ld, lld does not allow an ET_EXEC input. 250 printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none 251} 252 253# Create ${2} .S file with all symbols from the ${1} object file 254kallsyms() 255{ 256 local kallsymopt; 257 258 if is_enabled CONFIG_KALLSYMS_ALL; then 259 kallsymopt="${kallsymopt} --all-symbols" 260 fi 261 262 if is_enabled CONFIG_KALLSYMS_ABSOLUTE_PERCPU; then 263 kallsymopt="${kallsymopt} --absolute-percpu" 264 fi 265 266 if is_enabled CONFIG_KALLSYMS_BASE_RELATIVE; then 267 kallsymopt="${kallsymopt} --base-relative" 268 fi 269 270 info KSYMS ${2} 271 ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${2} 272} 273 274# Perform one step in kallsyms generation, including temporary linking of 275# vmlinux. 276kallsyms_step() 277{ 278 kallsymso_prev=${kallsymso} 279 kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1} 280 kallsymso=${kallsyms_vmlinux}.o 281 kallsyms_S=${kallsyms_vmlinux}.S 282 283 vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o} 284 kallsyms ${kallsyms_vmlinux} ${kallsyms_S} 285 286 info AS ${kallsyms_S} 287 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \ 288 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \ 289 -c -o ${kallsymso} ${kallsyms_S} 290} 291 292# Create map file with all symbols from ${1} 293# See mksymap for additional details 294mksysmap() 295{ 296 ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2} 297} 298 299sorttable() 300{ 301 ${objtree}/scripts/sorttable ${1} 302} 303 304# Delete output files in case of error 305cleanup() 306{ 307 rm -f .btf.* 308 rm -f .tmp_System.map 309 rm -f .tmp_initcalls.lds 310 rm -f .tmp_symversions.lds 311 rm -f .tmp_vmlinux* 312 rm -f System.map 313 rm -f vmlinux 314 rm -f vmlinux.map 315 rm -f vmlinux.o 316 rm -f .vmlinux.d 317 rm -f .vmlinux.objs 318 rm -f .vmlinux.export.c 319} 320 321# Use "make V=1" to debug this script 322case "${KBUILD_VERBOSE}" in 323*1*) 324 set -x 325 ;; 326esac 327 328if [ "$1" = "clean" ]; then 329 cleanup 330 exit 0 331fi 332 333# Update version 334info GEN .version 335if [ -r .version ]; then 336 VERSION=$(expr 0$(cat .version) + 1) 337 echo $VERSION > .version 338else 339 rm -f .version 340 echo 1 > .version 341fi; 342 343# final build of init/ 344${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1 345 346#link vmlinux.o 347modpost_link vmlinux.o 348objtool_link vmlinux.o 349 350# Generate the list of objects in vmlinux 351for f in ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS}; do 352 case ${f} in 353 *.a) 354 ${AR} t ${f} ;; 355 *) 356 echo ${f} ;; 357 esac 358done > .vmlinux.objs 359 360# modpost vmlinux.o to check for section mismatches 361${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1 362 363info MODINFO modules.builtin.modinfo 364${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo 365info GEN modules.builtin 366# The second line aids cases where multiple modules share the same object. 367tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' | 368 tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin 369 370if is_enabled CONFIG_MODULES; then 371 ${MAKE} -f "${srctree}/scripts/Makefile.vmlinux" .vmlinux.export.o 372fi 373 374btf_vmlinux_bin_o="" 375if is_enabled CONFIG_DEBUG_INFO_BTF; then 376 btf_vmlinux_bin_o=.btf.vmlinux.bin.o 377 if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then 378 echo >&2 "Failed to generate BTF for vmlinux" 379 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF" 380 exit 1 381 fi 382fi 383 384kallsymso="" 385kallsymso_prev="" 386kallsyms_vmlinux="" 387if is_enabled CONFIG_KALLSYMS; then 388 389 # kallsyms support 390 # Generate section listing all symbols and add it into vmlinux 391 # It's a three step process: 392 # 1) Link .tmp_vmlinux.kallsyms1 so it has all symbols and sections, 393 # but __kallsyms is empty. 394 # Running kallsyms on that gives us .tmp_kallsyms1.o with 395 # the right size 396 # 2) Link .tmp_vmlinux.kallsyms2 so it now has a __kallsyms section of 397 # the right size, but due to the added section, some 398 # addresses have shifted. 399 # From here, we generate a correct .tmp_vmlinux.kallsyms2.o 400 # 3) That link may have expanded the kernel image enough that 401 # more linker branch stubs / trampolines had to be added, which 402 # introduces new names, which further expands kallsyms. Do another 403 # pass if that is the case. In theory it's possible this results 404 # in even more stubs, but unlikely. 405 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around 406 # other bugs. 407 # 4) The correct ${kallsymso} is linked into the final vmlinux. 408 # 409 # a) Verify that the System.map from vmlinux matches the map from 410 # ${kallsymso}. 411 412 kallsyms_step 1 413 kallsyms_step 2 414 415 # step 3 416 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev}) 417 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 418 419 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then 420 kallsyms_step 3 421 fi 422fi 423 424vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o} 425 426# fill in BTF IDs 427if is_enabled CONFIG_DEBUG_INFO_BTF && is_enabled CONFIG_BPF; then 428 info BTFIDS vmlinux 429 ${RESOLVE_BTFIDS} vmlinux 430fi 431 432info SYSMAP System.map 433mksysmap vmlinux System.map 434 435if is_enabled CONFIG_BUILDTIME_TABLE_SORT; then 436 info SORTTAB vmlinux 437 if ! sorttable vmlinux; then 438 echo >&2 Failed to sort kernel tables 439 exit 1 440 fi 441fi 442 443# step a (see comment above) 444if is_enabled CONFIG_KALLSYMS; then 445 mksysmap ${kallsyms_vmlinux} .tmp_System.map 446 447 if ! cmp -s System.map .tmp_System.map; then 448 echo >&2 Inconsistent kallsyms data 449 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround 450 exit 1 451 fi 452fi 453 454# For fixdep 455echo "vmlinux: $0" > .vmlinux.d 456