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="$3" 36 37# Nice output in kbuild format 38# Will be supressed by "make -s" 39info() 40{ 41 printf " %-7s %s\n" "${1}" "${2}" 42} 43 44# Generate a linker script to ensure correct ordering of initcalls. 45gen_initcalls() 46{ 47 info GEN .tmp_initcalls.lds 48 49 ${PYTHON} ${srctree}/scripts/jobserver-exec \ 50 ${PERL} ${srctree}/scripts/generate_initcall_order.pl \ 51 ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS} \ 52 > .tmp_initcalls.lds 53} 54 55# If CONFIG_LTO_CLANG is selected, collect generated symbol versions into 56# .tmp_symversions.lds 57gen_symversions() 58{ 59 info GEN .tmp_symversions.lds 60 rm -f .tmp_symversions.lds 61 62 for o in ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS}; do 63 if [ -f ${o}.symversions ]; then 64 cat ${o}.symversions >> .tmp_symversions.lds 65 fi 66 done 67} 68 69# Link of vmlinux.o used for section mismatch analysis 70# ${1} output file 71modpost_link() 72{ 73 local objects 74 local lds="" 75 76 objects="--whole-archive \ 77 ${KBUILD_VMLINUX_OBJS} \ 78 --no-whole-archive \ 79 --start-group \ 80 ${KBUILD_VMLINUX_LIBS} \ 81 --end-group" 82 83 if [ -n "${CONFIG_LTO_CLANG}" ]; then 84 gen_initcalls 85 lds="-T .tmp_initcalls.lds" 86 87 if [ -n "${CONFIG_MODVERSIONS}" ]; then 88 gen_symversions 89 lds="${lds} -T .tmp_symversions.lds" 90 fi 91 92 # This might take a while, so indicate that we're doing 93 # an LTO link 94 info LTO ${1} 95 else 96 info LD ${1} 97 fi 98 99 ${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${lds} ${objects} 100} 101 102objtool_link() 103{ 104 local objtoolcmd; 105 local objtoolopt; 106 107 if [ "${CONFIG_LTO_CLANG} ${CONFIG_STACK_VALIDATION}" = "y y" ]; then 108 # Don't perform vmlinux validation unless explicitly requested, 109 # but run objtool on vmlinux.o now that we have an object file. 110 if [ -n "${CONFIG_UNWINDER_ORC}" ]; then 111 objtoolcmd="orc generate" 112 fi 113 114 objtoolopt="${objtoolopt} --duplicate" 115 116 if [ -n "${CONFIG_FTRACE_MCOUNT_USE_OBJTOOL}" ]; then 117 objtoolopt="${objtoolopt} --mcount" 118 fi 119 fi 120 121 if [ -n "${CONFIG_VMLINUX_VALIDATION}" ]; then 122 objtoolopt="${objtoolopt} --noinstr" 123 fi 124 125 if [ -n "${objtoolopt}" ]; then 126 if [ -z "${objtoolcmd}" ]; then 127 objtoolcmd="check" 128 fi 129 objtoolopt="${objtoolopt} --vmlinux" 130 if [ -z "${CONFIG_FRAME_POINTER}" ]; then 131 objtoolopt="${objtoolopt} --no-fp" 132 fi 133 if [ -n "${CONFIG_GCOV_KERNEL}" ] || [ -n "${CONFIG_LTO_CLANG}" ]; then 134 objtoolopt="${objtoolopt} --no-unreachable" 135 fi 136 if [ -n "${CONFIG_RETPOLINE}" ]; then 137 objtoolopt="${objtoolopt} --retpoline" 138 fi 139 if [ -n "${CONFIG_X86_SMAP}" ]; then 140 objtoolopt="${objtoolopt} --uaccess" 141 fi 142 info OBJTOOL ${1} 143 tools/objtool/objtool ${objtoolcmd} ${objtoolopt} ${1} 144 fi 145} 146 147# Link of vmlinux 148# ${1} - output file 149# ${2}, ${3}, ... - optional extra .o files 150vmlinux_link() 151{ 152 local lds="${objtree}/${KBUILD_LDS}" 153 local output=${1} 154 local objects 155 local strip_debug 156 local map_option 157 158 info LD ${output} 159 160 # skip output file argument 161 shift 162 163 # The kallsyms linking does not need debug symbols included. 164 if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then 165 strip_debug=-Wl,--strip-debug 166 fi 167 168 if [ -n "${CONFIG_VMLINUX_MAP}" ]; then 169 map_option="-Map=${output}.map" 170 fi 171 172 if [ "${SRCARCH}" != "um" ]; then 173 if [ -n "${CONFIG_LTO_CLANG}" ]; then 174 # Use vmlinux.o instead of performing the slow LTO 175 # link again. 176 objects="--whole-archive \ 177 vmlinux.o \ 178 --no-whole-archive \ 179 ${@}" 180 else 181 objects="--whole-archive \ 182 ${KBUILD_VMLINUX_OBJS} \ 183 --no-whole-archive \ 184 --start-group \ 185 ${KBUILD_VMLINUX_LIBS} \ 186 --end-group \ 187 ${@}" 188 fi 189 190 ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} \ 191 ${strip_debug#-Wl,} \ 192 -o ${output} \ 193 ${map_option} \ 194 -T ${lds} ${objects} 195 else 196 objects="-Wl,--whole-archive \ 197 ${KBUILD_VMLINUX_OBJS} \ 198 -Wl,--no-whole-archive \ 199 -Wl,--start-group \ 200 ${KBUILD_VMLINUX_LIBS} \ 201 -Wl,--end-group \ 202 ${@}" 203 204 ${CC} ${CFLAGS_vmlinux} \ 205 ${strip_debug} \ 206 -o ${output} \ 207 ${map_option:+-Wl,${map_option}} \ 208 -Wl,-T,${lds} \ 209 ${objects} \ 210 -lutil -lrt -lpthread 211 rm -f linux 212 fi 213} 214 215# generate .BTF typeinfo from DWARF debuginfo 216# ${1} - vmlinux image 217# ${2} - file to dump raw BTF data into 218gen_btf() 219{ 220 local pahole_ver 221 local extra_paholeopt= 222 223 if ! [ -x "$(command -v ${PAHOLE})" ]; then 224 echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available" 225 return 1 226 fi 227 228 pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/') 229 if [ "${pahole_ver}" -lt "116" ]; then 230 echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.16" 231 return 1 232 fi 233 234 vmlinux_link ${1} 235 236 if [ "${pahole_ver}" -ge "121" ]; then 237 extra_paholeopt="${extra_paholeopt} --btf_gen_floats" 238 fi 239 240 info "BTF" ${2} 241 LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${extra_paholeopt} ${1} 242 243 # Create ${2} which contains just .BTF section but no symbols. Add 244 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all 245 # deletes all symbols including __start_BTF and __stop_BTF, which will 246 # be redefined in the linker script. Add 2>/dev/null to suppress GNU 247 # objcopy warnings: "empty loadable segment detected at ..." 248 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \ 249 --strip-all ${1} ${2} 2>/dev/null 250 # Change e_type to ET_REL so that it can be used to link final vmlinux. 251 # Unlike GNU ld, lld does not allow an ET_EXEC input. 252 printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none 253} 254 255# Create ${2} .S file with all symbols from the ${1} object file 256kallsyms() 257{ 258 local kallsymopt; 259 260 if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then 261 kallsymopt="${kallsymopt} --all-symbols" 262 fi 263 264 if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then 265 kallsymopt="${kallsymopt} --absolute-percpu" 266 fi 267 268 if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then 269 kallsymopt="${kallsymopt} --base-relative" 270 fi 271 272 info KSYMS ${2} 273 ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${2} 274} 275 276# Perform one step in kallsyms generation, including temporary linking of 277# vmlinux. 278kallsyms_step() 279{ 280 kallsymso_prev=${kallsymso} 281 kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1} 282 kallsymso=${kallsyms_vmlinux}.o 283 kallsyms_S=${kallsyms_vmlinux}.S 284 285 vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o} 286 kallsyms ${kallsyms_vmlinux} ${kallsyms_S} 287 288 info AS ${kallsyms_S} 289 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \ 290 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \ 291 -c -o ${kallsymso} ${kallsyms_S} 292} 293 294# Create map file with all symbols from ${1} 295# See mksymap for additional details 296mksysmap() 297{ 298 ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2} 299} 300 301sorttable() 302{ 303 ${objtree}/scripts/sorttable ${1} 304} 305 306# Delete output files in case of error 307cleanup() 308{ 309 rm -f .btf.* 310 rm -f .tmp_System.map 311 rm -f .tmp_initcalls.lds 312 rm -f .tmp_symversions.lds 313 rm -f .tmp_vmlinux* 314 rm -f System.map 315 rm -f vmlinux 316 rm -f vmlinux.map 317 rm -f vmlinux.o 318 rm -f .vmlinux.d 319} 320 321# Use "make V=1" to debug this script 322case "${KBUILD_VERBOSE}" in 323*1*) 324 set -x 325 ;; 326esac 327 328if [ "$1" = "clean" ]; then 329 cleanup 330 exit 0 331fi 332 333# We need access to CONFIG_ symbols 334. include/config/auto.conf 335 336# Update version 337info GEN .version 338if [ -r .version ]; then 339 VERSION=$(expr 0$(cat .version) + 1) 340 echo $VERSION > .version 341else 342 rm -f .version 343 echo 1 > .version 344fi; 345 346# final build of init/ 347${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1 348 349#link vmlinux.o 350modpost_link vmlinux.o 351objtool_link vmlinux.o 352 353# modpost vmlinux.o to check for section mismatches 354${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1 355 356info MODINFO modules.builtin.modinfo 357${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo 358info GEN modules.builtin 359# The second line aids cases where multiple modules share the same object. 360tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' | 361 tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin 362 363btf_vmlinux_bin_o="" 364if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then 365 btf_vmlinux_bin_o=.btf.vmlinux.bin.o 366 if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then 367 echo >&2 "Failed to generate BTF for vmlinux" 368 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF" 369 exit 1 370 fi 371fi 372 373kallsymso="" 374kallsymso_prev="" 375kallsyms_vmlinux="" 376if [ -n "${CONFIG_KALLSYMS}" ]; then 377 378 # kallsyms support 379 # Generate section listing all symbols and add it into vmlinux 380 # It's a three step process: 381 # 1) Link .tmp_vmlinux1 so it has all symbols and sections, 382 # but __kallsyms is empty. 383 # Running kallsyms on that gives us .tmp_kallsyms1.o with 384 # the right size 385 # 2) Link .tmp_vmlinux2 so it now has a __kallsyms section of 386 # the right size, but due to the added section, some 387 # addresses have shifted. 388 # From here, we generate a correct .tmp_kallsyms2.o 389 # 3) That link may have expanded the kernel image enough that 390 # more linker branch stubs / trampolines had to be added, which 391 # introduces new names, which further expands kallsyms. Do another 392 # pass if that is the case. In theory it's possible this results 393 # in even more stubs, but unlikely. 394 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around 395 # other bugs. 396 # 4) The correct ${kallsymso} is linked into the final vmlinux. 397 # 398 # a) Verify that the System.map from vmlinux matches the map from 399 # ${kallsymso}. 400 401 kallsyms_step 1 402 kallsyms_step 2 403 404 # step 3 405 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev}) 406 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 407 408 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then 409 kallsyms_step 3 410 fi 411fi 412 413vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o} 414 415# fill in BTF IDs 416if [ -n "${CONFIG_DEBUG_INFO_BTF}" -a -n "${CONFIG_BPF}" ]; then 417 info BTFIDS vmlinux 418 ${RESOLVE_BTFIDS} vmlinux 419fi 420 421if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then 422 info SORTTAB vmlinux 423 if ! sorttable vmlinux; then 424 echo >&2 Failed to sort kernel tables 425 exit 1 426 fi 427fi 428 429info SYSMAP System.map 430mksysmap vmlinux System.map 431 432# step a (see comment above) 433if [ -n "${CONFIG_KALLSYMS}" ]; then 434 mksysmap ${kallsyms_vmlinux} .tmp_System.map 435 436 if ! cmp -s System.map .tmp_System.map; then 437 echo >&2 Inconsistent kallsyms data 438 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround 439 exit 1 440 fi 441fi 442 443# For fixdep 444echo "vmlinux: $0" > .vmlinux.d 445