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