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# Link of vmlinux.o used for section mismatch analysis 60# ${1} output file 61modpost_link() 62{ 63 local objects 64 local lds="" 65 66 objects="--whole-archive \ 67 ${KBUILD_VMLINUX_OBJS} \ 68 --no-whole-archive \ 69 --start-group \ 70 ${KBUILD_VMLINUX_LIBS} \ 71 --end-group" 72 73 if is_enabled CONFIG_LTO_CLANG; then 74 gen_initcalls 75 lds="-T .tmp_initcalls.lds" 76 77 # This might take a while, so indicate that we're doing 78 # an LTO link 79 info LTO ${1} 80 else 81 info LD ${1} 82 fi 83 84 ${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${lds} ${objects} 85} 86 87objtool_link() 88{ 89 local objtoolcmd; 90 local objtoolopt; 91 92 if ! is_enabled CONFIG_OBJTOOL; then 93 return; 94 fi 95 96 if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then 97 98 # For LTO and IBT, objtool doesn't run on individual 99 # translation units. Run everything on vmlinux instead. 100 101 if is_enabled CONFIG_HAVE_JUMP_LABEL_HACK; then 102 objtoolopt="${objtoolopt} --hacks=jump_label" 103 fi 104 105 if is_enabled CONFIG_HAVE_NOINSTR_HACK; then 106 objtoolopt="${objtoolopt} --hacks=noinstr" 107 fi 108 109 if is_enabled CONFIG_X86_KERNEL_IBT; then 110 objtoolopt="${objtoolopt} --ibt" 111 fi 112 113 if is_enabled CONFIG_FTRACE_MCOUNT_USE_OBJTOOL; then 114 objtoolopt="${objtoolopt} --mcount" 115 fi 116 117 if is_enabled CONFIG_UNWINDER_ORC; then 118 objtoolopt="${objtoolopt} --orc" 119 fi 120 121 if is_enabled CONFIG_RETPOLINE; then 122 objtoolopt="${objtoolopt} --retpoline" 123 fi 124 125 if is_enabled CONFIG_SLS; then 126 objtoolopt="${objtoolopt} --sls" 127 fi 128 129 if is_enabled CONFIG_STACK_VALIDATION; then 130 objtoolopt="${objtoolopt} --stackval" 131 fi 132 133 if is_enabled CONFIG_HAVE_STATIC_CALL_INLINE; then 134 objtoolopt="${objtoolopt} --static-call" 135 fi 136 137 objtoolopt="${objtoolopt} --uaccess" 138 fi 139 140 if is_enabled CONFIG_NOINSTR_VALIDATION; then 141 objtoolopt="${objtoolopt} --noinstr" 142 fi 143 144 if [ -n "${objtoolopt}" ]; then 145 146 if is_enabled CONFIG_GCOV_KERNEL; then 147 objtoolopt="${objtoolopt} --no-unreachable" 148 fi 149 150 objtoolopt="${objtoolopt} --link" 151 152 info OBJTOOL ${1} 153 tools/objtool/objtool ${objtoolopt} ${1} 154 fi 155} 156 157# Link of vmlinux 158# ${1} - output file 159# ${2}, ${3}, ... - optional extra .o files 160vmlinux_link() 161{ 162 local output=${1} 163 local objs 164 local libs 165 local ld 166 local ldflags 167 local ldlibs 168 169 info LD ${output} 170 171 # skip output file argument 172 shift 173 174 if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then 175 # Use vmlinux.o instead of performing the slow LTO link again. 176 objs=vmlinux.o 177 libs= 178 else 179 objs="${KBUILD_VMLINUX_OBJS}" 180 libs="${KBUILD_VMLINUX_LIBS}" 181 fi 182 183 if is_enabled CONFIG_MODULES; then 184 objs="${objs} .vmlinux.export.o" 185 fi 186 187 if [ "${SRCARCH}" = "um" ]; then 188 wl=-Wl, 189 ld="${CC}" 190 ldflags="${CFLAGS_vmlinux}" 191 ldlibs="-lutil -lrt -lpthread" 192 else 193 wl= 194 ld="${LD}" 195 ldflags="${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}" 196 ldlibs= 197 fi 198 199 ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}" 200 201 # The kallsyms linking does not need debug symbols included. 202 if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then 203 ldflags="${ldflags} ${wl}--strip-debug" 204 fi 205 206 if is_enabled CONFIG_VMLINUX_MAP; then 207 ldflags="${ldflags} ${wl}-Map=${output}.map" 208 fi 209 210 ${ld} ${ldflags} -o ${output} \ 211 ${wl}--whole-archive ${objs} ${wl}--no-whole-archive \ 212 ${wl}--start-group ${libs} ${wl}--end-group \ 213 $@ ${ldlibs} 214} 215 216# generate .BTF typeinfo from DWARF debuginfo 217# ${1} - vmlinux image 218# ${2} - file to dump raw BTF data into 219gen_btf() 220{ 221 local pahole_ver 222 223 if ! [ -x "$(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 info "BTF" ${2} 237 LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1} 238 239 # Create ${2} which contains just .BTF section but no symbols. Add 240 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all 241 # deletes all symbols including __start_BTF and __stop_BTF, which will 242 # be redefined in the linker script. Add 2>/dev/null to suppress GNU 243 # objcopy warnings: "empty loadable segment detected at ..." 244 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \ 245 --strip-all ${1} ${2} 2>/dev/null 246 # Change e_type to ET_REL so that it can be used to link final vmlinux. 247 # Unlike GNU ld, lld does not allow an ET_EXEC input. 248 printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none 249} 250 251# Create ${2} .S file with all symbols from the ${1} object file 252kallsyms() 253{ 254 local kallsymopt; 255 256 if is_enabled CONFIG_KALLSYMS_ALL; then 257 kallsymopt="${kallsymopt} --all-symbols" 258 fi 259 260 if is_enabled CONFIG_KALLSYMS_ABSOLUTE_PERCPU; then 261 kallsymopt="${kallsymopt} --absolute-percpu" 262 fi 263 264 if is_enabled CONFIG_KALLSYMS_BASE_RELATIVE; then 265 kallsymopt="${kallsymopt} --base-relative" 266 fi 267 268 info KSYMS ${2} 269 ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${2} 270} 271 272# Perform one step in kallsyms generation, including temporary linking of 273# vmlinux. 274kallsyms_step() 275{ 276 kallsymso_prev=${kallsymso} 277 kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1} 278 kallsymso=${kallsyms_vmlinux}.o 279 kallsyms_S=${kallsyms_vmlinux}.S 280 281 vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o} 282 kallsyms ${kallsyms_vmlinux} ${kallsyms_S} 283 284 info AS ${kallsyms_S} 285 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \ 286 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \ 287 -c -o ${kallsymso} ${kallsyms_S} 288} 289 290# Create map file with all symbols from ${1} 291# See mksymap for additional details 292mksysmap() 293{ 294 ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2} 295} 296 297sorttable() 298{ 299 ${objtree}/scripts/sorttable ${1} 300} 301 302# Delete output files in case of error 303cleanup() 304{ 305 rm -f .btf.* 306 rm -f .tmp_System.map 307 rm -f .tmp_initcalls.lds 308 rm -f .tmp_vmlinux* 309 rm -f System.map 310 rm -f vmlinux 311 rm -f vmlinux.map 312 rm -f vmlinux.o 313 rm -f .vmlinux.d 314 rm -f .vmlinux.objs 315 rm -f .vmlinux.export.c 316} 317 318# Use "make V=1" to debug this script 319case "${KBUILD_VERBOSE}" in 320*1*) 321 set -x 322 ;; 323esac 324 325if [ "$1" = "clean" ]; then 326 cleanup 327 exit 0 328fi 329 330# Update version 331info GEN .version 332if [ -r .version ]; then 333 VERSION=$(expr 0$(cat .version) + 1) 334 echo $VERSION > .version 335else 336 rm -f .version 337 echo 1 > .version 338fi; 339 340# final build of init/ 341${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1 342 343#link vmlinux.o 344modpost_link vmlinux.o 345objtool_link vmlinux.o 346 347# Generate the list of objects in vmlinux 348for f in ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS}; do 349 case ${f} in 350 *.a) 351 ${AR} t ${f} ;; 352 *) 353 echo ${f} ;; 354 esac 355done > .vmlinux.objs 356 357# modpost vmlinux.o to check for section mismatches 358${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1 359 360info MODINFO modules.builtin.modinfo 361${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo 362info GEN modules.builtin 363# The second line aids cases where multiple modules share the same object. 364tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' | 365 tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin 366 367if is_enabled CONFIG_MODULES; then 368 ${MAKE} -f "${srctree}/scripts/Makefile.vmlinux" .vmlinux.export.o 369fi 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