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="$3" 36 37# Nice output in kbuild format 38# Will be supressed by "make -s" 39info() 40{ 41 if [ "${quiet}" != "silent_" ]; then 42 printf " %-7s %s\n" "${1}" "${2}" 43 fi 44} 45 46# Generate a linker script to ensure correct ordering of initcalls. 47gen_initcalls() 48{ 49 info GEN .tmp_initcalls.lds 50 51 ${PYTHON} ${srctree}/scripts/jobserver-exec \ 52 ${PERL} ${srctree}/scripts/generate_initcall_order.pl \ 53 ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS} \ 54 > .tmp_initcalls.lds 55} 56 57# If CONFIG_LTO_CLANG is selected, collect generated symbol versions into 58# .tmp_symversions.lds 59gen_symversions() 60{ 61 info GEN .tmp_symversions.lds 62 rm -f .tmp_symversions.lds 63 64 for o in ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS}; do 65 if [ -f ${o}.symversions ]; then 66 cat ${o}.symversions >> .tmp_symversions.lds 67 fi 68 done 69} 70 71# Link of vmlinux.o used for section mismatch analysis 72# ${1} output file 73modpost_link() 74{ 75 local objects 76 local lds="" 77 78 objects="--whole-archive \ 79 ${KBUILD_VMLINUX_OBJS} \ 80 --no-whole-archive \ 81 --start-group \ 82 ${KBUILD_VMLINUX_LIBS} \ 83 --end-group" 84 85 if [ -n "${CONFIG_LTO_CLANG}" ]; then 86 gen_initcalls 87 lds="-T .tmp_initcalls.lds" 88 89 if [ -n "${CONFIG_MODVERSIONS}" ]; then 90 gen_symversions 91 lds="${lds} -T .tmp_symversions.lds" 92 fi 93 94 # This might take a while, so indicate that we're doing 95 # an LTO link 96 info LTO ${1} 97 else 98 info LD ${1} 99 fi 100 101 ${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${lds} ${objects} 102} 103 104objtool_link() 105{ 106 local objtoolcmd; 107 local objtoolopt; 108 109 if [ "${CONFIG_LTO_CLANG} ${CONFIG_STACK_VALIDATION}" = "y y" ]; then 110 # Don't perform vmlinux validation unless explicitly requested, 111 # but run objtool on vmlinux.o now that we have an object file. 112 if [ -n "${CONFIG_UNWINDER_ORC}" ]; then 113 objtoolcmd="orc generate" 114 fi 115 116 objtoolopt="${objtoolopt} --duplicate" 117 118 if [ -n "${CONFIG_FTRACE_MCOUNT_USE_OBJTOOL}" ]; then 119 objtoolopt="${objtoolopt} --mcount" 120 fi 121 fi 122 123 if [ -n "${CONFIG_VMLINUX_VALIDATION}" ]; then 124 objtoolopt="${objtoolopt} --noinstr" 125 fi 126 127 if [ -n "${objtoolopt}" ]; then 128 if [ -z "${objtoolcmd}" ]; then 129 objtoolcmd="check" 130 fi 131 objtoolopt="${objtoolopt} --vmlinux" 132 if [ -n "${CONFIG_CPU_UNRET_ENTRY}" ]; then 133 objtoolopt="${objtoolopt} --unret" 134 fi 135 if [ -z "${CONFIG_FRAME_POINTER}" ]; then 136 objtoolopt="${objtoolopt} --no-fp" 137 fi 138 if [ -n "${CONFIG_GCOV_KERNEL}" ] || [ -n "${CONFIG_LTO_CLANG}" ]; then 139 objtoolopt="${objtoolopt} --no-unreachable" 140 fi 141 if [ -n "${CONFIG_RETPOLINE}" ]; then 142 objtoolopt="${objtoolopt} --retpoline" 143 fi 144 if [ -n "${CONFIG_X86_SMAP}" ]; then 145 objtoolopt="${objtoolopt} --uaccess" 146 fi 147 if [ -n "${CONFIG_SLS}" ]; then 148 objtoolopt="${objtoolopt} --sls" 149 fi 150 info OBJTOOL ${1} 151 tools/objtool/objtool ${objtoolcmd} ${objtoolopt} ${1} 152 fi 153} 154 155# Link of vmlinux 156# ${1} - output file 157# ${2}, ${3}, ... - optional extra .o files 158vmlinux_link() 159{ 160 local lds="${objtree}/${KBUILD_LDS}" 161 local output=${1} 162 local objects 163 local strip_debug 164 165 info LD ${output} 166 167 # skip output file argument 168 shift 169 170 # The kallsyms linking does not need debug symbols included. 171 if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then 172 strip_debug=-Wl,--strip-debug 173 fi 174 175 if [ "${SRCARCH}" != "um" ]; then 176 if [ -n "${CONFIG_LTO_CLANG}" ]; then 177 # Use vmlinux.o instead of performing the slow LTO 178 # link again. 179 objects="--whole-archive \ 180 vmlinux.o \ 181 --no-whole-archive \ 182 ${@}" 183 else 184 objects="--whole-archive \ 185 ${KBUILD_VMLINUX_OBJS} \ 186 --no-whole-archive \ 187 --start-group \ 188 ${KBUILD_VMLINUX_LIBS} \ 189 --end-group \ 190 ${@}" 191 fi 192 193 ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} \ 194 ${strip_debug#-Wl,} \ 195 -o ${output} \ 196 -T ${lds} ${objects} 197 else 198 objects="-Wl,--whole-archive \ 199 ${KBUILD_VMLINUX_OBJS} \ 200 -Wl,--no-whole-archive \ 201 -Wl,--start-group \ 202 ${KBUILD_VMLINUX_LIBS} \ 203 -Wl,--end-group \ 204 ${@}" 205 206 ${CC} ${CFLAGS_vmlinux} \ 207 ${strip_debug} \ 208 -o ${output} \ 209 -Wl,-T,${lds} \ 210 ${objects} \ 211 -lutil -lrt -lpthread 212 rm -f linux 213 fi 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} ${2} 2>/dev/null 246 # Change e_type to ET_REL so that it can be used to link final vmlinux. 247 # GNU ld 2.35+ and lld do not allow an ET_EXEC input. 248 if [ -n "${CONFIG_CPU_BIG_ENDIAN}" ]; then 249 et_rel='\0\1' 250 else 251 et_rel='\1\0' 252 fi 253 printf "${et_rel}" | dd of=${2} conv=notrunc bs=1 seek=16 status=none 254} 255 256# Create ${2} .S file with all symbols from the ${1} object file 257kallsyms() 258{ 259 local kallsymopt; 260 261 if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then 262 kallsymopt="${kallsymopt} --all-symbols" 263 fi 264 265 if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then 266 kallsymopt="${kallsymopt} --absolute-percpu" 267 fi 268 269 if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then 270 kallsymopt="${kallsymopt} --base-relative" 271 fi 272 273 info KSYMS ${2} 274 275 if [ -n "${CONFIG_CFI_CLANG}" ]; then 276 ${PERL} ${srctree}/scripts/generate_cfi_kallsyms.pl ${1} | \ 277 sort -n > .tmp_kallsyms 278 else 279 ${NM} -n ${1} > .tmp_kallsyms 280 fi 281 282 scripts/kallsyms ${kallsymopt} < .tmp_kallsyms > ${2} 283} 284 285# Perform one step in kallsyms generation, including temporary linking of 286# vmlinux. 287kallsyms_step() 288{ 289 kallsymso_prev=${kallsymso} 290 kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1} 291 kallsymso=${kallsyms_vmlinux}.o 292 kallsyms_S=${kallsyms_vmlinux}.S 293 294 vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o} 295 kallsyms ${kallsyms_vmlinux} ${kallsyms_S} 296 297 info AS ${kallsyms_S} 298 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \ 299 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \ 300 -c -o ${kallsymso} ${kallsyms_S} 301} 302 303# Create map file with all symbols from ${1} 304# See mksymap for additional details 305mksysmap() 306{ 307 ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2} 308} 309 310sorttable() 311{ 312 ${objtree}/scripts/sorttable ${1} 313} 314 315# Delete output files in case of error 316cleanup() 317{ 318 rm -f .btf.* 319 rm -f .tmp_System.map 320 rm -f .tmp_kallsyms 321 rm -f .tmp_initcalls.lds 322 rm -f .tmp_symversions.lds 323 rm -f .tmp_vmlinux* 324 rm -f System.map 325 rm -f vmlinux 326 rm -f vmlinux.o 327} 328 329on_exit() 330{ 331 if [ $? -ne 0 ]; then 332 cleanup 333 fi 334} 335trap on_exit EXIT 336 337on_signals() 338{ 339 exit 1 340} 341trap on_signals HUP INT QUIT TERM 342 343# Use "make V=1" to debug this script 344case "${KBUILD_VERBOSE}" in 345*1*) 346 set -x 347 ;; 348esac 349 350if [ "$1" = "clean" ]; then 351 cleanup 352 exit 0 353fi 354 355# We need access to CONFIG_ symbols 356. include/config/auto.conf 357 358# Update version 359info GEN .version 360if [ -r .version ]; then 361 VERSION=$(expr 0$(cat .version) + 1) 362 echo $VERSION > .version 363else 364 rm -f .version 365 echo 1 > .version 366fi; 367 368# final build of init/ 369${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1 370 371#link vmlinux.o 372modpost_link vmlinux.o 373objtool_link vmlinux.o 374 375# modpost vmlinux.o to check for section mismatches 376${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1 377 378info MODINFO modules.builtin.modinfo 379${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo 380info GEN modules.builtin 381# The second line aids cases where multiple modules share the same object. 382tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' | 383 tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin 384 385btf_vmlinux_bin_o="" 386if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then 387 btf_vmlinux_bin_o=.btf.vmlinux.bin.o 388 if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then 389 echo >&2 "Failed to generate BTF for vmlinux" 390 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF" 391 exit 1 392 fi 393fi 394 395kallsymso="" 396kallsymso_prev="" 397kallsyms_vmlinux="" 398if [ -n "${CONFIG_KALLSYMS}" ]; then 399 400 # kallsyms support 401 # Generate section listing all symbols and add it into vmlinux 402 # It's a three step process: 403 # 1) Link .tmp_vmlinux1 so it has all symbols and sections, 404 # but __kallsyms is empty. 405 # Running kallsyms on that gives us .tmp_kallsyms1.o with 406 # the right size 407 # 2) Link .tmp_vmlinux2 so it now has a __kallsyms section of 408 # the right size, but due to the added section, some 409 # addresses have shifted. 410 # From here, we generate a correct .tmp_kallsyms2.o 411 # 3) That link may have expanded the kernel image enough that 412 # more linker branch stubs / trampolines had to be added, which 413 # introduces new names, which further expands kallsyms. Do another 414 # pass if that is the case. In theory it's possible this results 415 # in even more stubs, but unlikely. 416 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around 417 # other bugs. 418 # 4) The correct ${kallsymso} is linked into the final vmlinux. 419 # 420 # a) Verify that the System.map from vmlinux matches the map from 421 # ${kallsymso}. 422 423 kallsyms_step 1 424 kallsyms_step 2 425 426 # step 3 427 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev}) 428 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 429 430 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then 431 kallsyms_step 3 432 fi 433fi 434 435vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o} 436 437# fill in BTF IDs 438if [ -n "${CONFIG_DEBUG_INFO_BTF}" -a -n "${CONFIG_BPF}" ]; then 439 info BTFIDS vmlinux 440 ${RESOLVE_BTFIDS} vmlinux 441fi 442 443if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then 444 info SORTTAB vmlinux 445 if ! sorttable vmlinux; then 446 echo >&2 Failed to sort kernel tables 447 exit 1 448 fi 449fi 450 451info SYSMAP System.map 452mksysmap vmlinux System.map 453 454# step a (see comment above) 455if [ -n "${CONFIG_KALLSYMS}" ]; then 456 mksysmap ${kallsyms_vmlinux} .tmp_System.map 457 458 if ! cmp -s System.map .tmp_System.map; then 459 echo >&2 Inconsistent kallsyms data 460 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround 461 exit 1 462 fi 463fi 464