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