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# ${2} - file to dump raw BTF data into 205gen_btf() 206{ 207 local pahole_ver 208 local extra_paholeopt= 209 210 if ! [ -x "$(command -v ${PAHOLE})" ]; then 211 echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available" 212 return 1 213 fi 214 215 pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/') 216 if [ "${pahole_ver}" -lt "116" ]; then 217 echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.16" 218 return 1 219 fi 220 221 vmlinux_link ${1} 222 223 if [ "${pahole_ver}" -ge "118" ] && [ "${pahole_ver}" -le "121" ]; then 224 # pahole 1.18 through 1.21 can't handle zero-sized per-CPU vars 225 extra_paholeopt="${extra_paholeopt} --skip_encoding_btf_vars" 226 fi 227 if [ "${pahole_ver}" -ge "121" ]; then 228 extra_paholeopt="${extra_paholeopt} --btf_gen_floats" 229 fi 230 231 info "BTF" ${2} 232 LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${extra_paholeopt} ${1} 233 234 # Create ${2} which contains just .BTF section but no symbols. Add 235 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all 236 # deletes all symbols including __start_BTF and __stop_BTF, which will 237 # be redefined in the linker script. Add 2>/dev/null to suppress GNU 238 # objcopy warnings: "empty loadable segment detected at ..." 239 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \ 240 --strip-all ${1} ${2} 2>/dev/null 241 # Change e_type to ET_REL so that it can be used to link final vmlinux. 242 # Unlike GNU ld, lld does not allow an ET_EXEC input. 243 printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none 244} 245 246# Create ${2} .S file with all symbols from the ${1} object file 247kallsyms() 248{ 249 local kallsymopt; 250 251 if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then 252 kallsymopt="${kallsymopt} --all-symbols" 253 fi 254 255 if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then 256 kallsymopt="${kallsymopt} --absolute-percpu" 257 fi 258 259 if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then 260 kallsymopt="${kallsymopt} --base-relative" 261 fi 262 263 info KSYMS ${2} 264 ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${2} 265} 266 267# Perform one step in kallsyms generation, including temporary linking of 268# vmlinux. 269kallsyms_step() 270{ 271 kallsymso_prev=${kallsymso} 272 kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1} 273 kallsymso=${kallsyms_vmlinux}.o 274 kallsyms_S=${kallsyms_vmlinux}.S 275 276 vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o} 277 kallsyms ${kallsyms_vmlinux} ${kallsyms_S} 278 279 info AS ${kallsyms_S} 280 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \ 281 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \ 282 -c -o ${kallsymso} ${kallsyms_S} 283} 284 285# Create map file with all symbols from ${1} 286# See mksymap for additional details 287mksysmap() 288{ 289 ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2} 290} 291 292sorttable() 293{ 294 ${objtree}/scripts/sorttable ${1} 295} 296 297# Delete output files in case of error 298cleanup() 299{ 300 rm -f .btf.* 301 rm -f .tmp_System.map 302 rm -f .tmp_initcalls.lds 303 rm -f .tmp_symversions.lds 304 rm -f .tmp_vmlinux* 305 rm -f System.map 306 rm -f vmlinux 307 rm -f vmlinux.map 308 rm -f vmlinux.o 309 rm -f .vmlinux.d 310} 311 312# Use "make V=1" to debug this script 313case "${KBUILD_VERBOSE}" in 314*1*) 315 set -x 316 ;; 317esac 318 319if [ "$1" = "clean" ]; then 320 cleanup 321 exit 0 322fi 323 324# We need access to CONFIG_ symbols 325. include/config/auto.conf 326 327# Update version 328info GEN .version 329if [ -r .version ]; then 330 VERSION=$(expr 0$(cat .version) + 1) 331 echo $VERSION > .version 332else 333 rm -f .version 334 echo 1 > .version 335fi; 336 337# final build of init/ 338${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1 339 340#link vmlinux.o 341modpost_link vmlinux.o 342objtool_link vmlinux.o 343 344# modpost vmlinux.o to check for section mismatches 345${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1 346 347info MODINFO modules.builtin.modinfo 348${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo 349info GEN modules.builtin 350# The second line aids cases where multiple modules share the same object. 351tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' | 352 tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin 353 354btf_vmlinux_bin_o="" 355if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then 356 btf_vmlinux_bin_o=.btf.vmlinux.bin.o 357 if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then 358 echo >&2 "Failed to generate BTF for vmlinux" 359 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF" 360 exit 1 361 fi 362fi 363 364kallsymso="" 365kallsymso_prev="" 366kallsyms_vmlinux="" 367if [ -n "${CONFIG_KALLSYMS}" ]; then 368 369 # kallsyms support 370 # Generate section listing all symbols and add it into vmlinux 371 # It's a three step process: 372 # 1) Link .tmp_vmlinux1 so it has all symbols and sections, 373 # but __kallsyms is empty. 374 # Running kallsyms on that gives us .tmp_kallsyms1.o with 375 # the right size 376 # 2) Link .tmp_vmlinux2 so it now has a __kallsyms section of 377 # the right size, but due to the added section, some 378 # addresses have shifted. 379 # From here, we generate a correct .tmp_kallsyms2.o 380 # 3) That link may have expanded the kernel image enough that 381 # more linker branch stubs / trampolines had to be added, which 382 # introduces new names, which further expands kallsyms. Do another 383 # pass if that is the case. In theory it's possible this results 384 # in even more stubs, but unlikely. 385 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around 386 # other bugs. 387 # 4) The correct ${kallsymso} is linked into the final vmlinux. 388 # 389 # a) Verify that the System.map from vmlinux matches the map from 390 # ${kallsymso}. 391 392 kallsyms_step 1 393 kallsyms_step 2 394 395 # step 3 396 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev}) 397 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 398 399 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then 400 kallsyms_step 3 401 fi 402fi 403 404vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o} 405 406# fill in BTF IDs 407if [ -n "${CONFIG_DEBUG_INFO_BTF}" -a -n "${CONFIG_BPF}" ]; then 408 info BTFIDS vmlinux 409 ${RESOLVE_BTFIDS} vmlinux 410fi 411 412if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then 413 info SORTTAB vmlinux 414 if ! sorttable vmlinux; then 415 echo >&2 Failed to sort kernel tables 416 exit 1 417 fi 418fi 419 420info SYSMAP System.map 421mksysmap vmlinux System.map 422 423# step a (see comment above) 424if [ -n "${CONFIG_KALLSYMS}" ]; then 425 mksysmap ${kallsyms_vmlinux} .tmp_System.map 426 427 if ! cmp -s System.map .tmp_System.map; then 428 echo >&2 Inconsistent kallsyms data 429 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround 430 exit 1 431 fi 432fi 433 434# For fixdep 435echo "vmlinux: $0" > .vmlinux.d 436