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