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