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