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} ${2} 2>/dev/null 246 # Change e_type to ET_REL so that it can be used to link final vmlinux. 247 # Unlike GNU ld, lld does not allow an ET_EXEC input. 248 printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none 249} 250 251# Create ${2} .S file with all symbols from the ${1} object file 252kallsyms() 253{ 254 local kallsymopt; 255 256 if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then 257 kallsymopt="${kallsymopt} --all-symbols" 258 fi 259 260 if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then 261 kallsymopt="${kallsymopt} --absolute-percpu" 262 fi 263 264 if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then 265 kallsymopt="${kallsymopt} --base-relative" 266 fi 267 268 info KSYMS ${2} 269 270 if [ -n "${CONFIG_CFI_CLANG}" ]; then 271 ${PERL} ${srctree}/scripts/generate_cfi_kallsyms.pl ${1} | \ 272 sort -n > .tmp_kallsyms 273 else 274 ${NM} -n ${1} > .tmp_kallsyms 275 fi 276 277 scripts/kallsyms ${kallsymopt} < .tmp_kallsyms > ${2} 278} 279 280# Perform one step in kallsyms generation, including temporary linking of 281# vmlinux. 282kallsyms_step() 283{ 284 kallsymso_prev=${kallsymso} 285 kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1} 286 kallsymso=${kallsyms_vmlinux}.o 287 kallsyms_S=${kallsyms_vmlinux}.S 288 289 vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o} 290 kallsyms ${kallsyms_vmlinux} ${kallsyms_S} 291 292 info AS ${kallsyms_S} 293 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \ 294 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \ 295 -c -o ${kallsymso} ${kallsyms_S} 296} 297 298# Create map file with all symbols from ${1} 299# See mksymap for additional details 300mksysmap() 301{ 302 ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2} 303} 304 305sorttable() 306{ 307 ${objtree}/scripts/sorttable ${1} 308} 309 310# Delete output files in case of error 311cleanup() 312{ 313 rm -f .btf.* 314 rm -f .tmp_System.map 315 rm -f .tmp_kallsyms 316 rm -f .tmp_initcalls.lds 317 rm -f .tmp_symversions.lds 318 rm -f .tmp_vmlinux* 319 rm -f System.map 320 rm -f vmlinux 321 rm -f vmlinux.o 322} 323 324on_exit() 325{ 326 if [ $? -ne 0 ]; then 327 cleanup 328 fi 329} 330trap on_exit EXIT 331 332on_signals() 333{ 334 exit 1 335} 336trap on_signals HUP INT QUIT TERM 337 338# Use "make V=1" to debug this script 339case "${KBUILD_VERBOSE}" in 340*1*) 341 set -x 342 ;; 343esac 344 345if [ "$1" = "clean" ]; then 346 cleanup 347 exit 0 348fi 349 350# We need access to CONFIG_ symbols 351. include/config/auto.conf 352 353# Update version 354info GEN .version 355if [ -r .version ]; then 356 VERSION=$(expr 0$(cat .version) + 1) 357 echo $VERSION > .version 358else 359 rm -f .version 360 echo 1 > .version 361fi; 362 363# final build of init/ 364${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1 365 366#link vmlinux.o 367modpost_link vmlinux.o 368objtool_link vmlinux.o 369 370# modpost vmlinux.o to check for section mismatches 371${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1 372 373info MODINFO modules.builtin.modinfo 374${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo 375info GEN modules.builtin 376# The second line aids cases where multiple modules share the same object. 377tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' | 378 tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin 379 380btf_vmlinux_bin_o="" 381if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then 382 btf_vmlinux_bin_o=.btf.vmlinux.bin.o 383 if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then 384 echo >&2 "Failed to generate BTF for vmlinux" 385 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF" 386 exit 1 387 fi 388fi 389 390kallsymso="" 391kallsymso_prev="" 392kallsyms_vmlinux="" 393if [ -n "${CONFIG_KALLSYMS}" ]; then 394 395 # kallsyms support 396 # Generate section listing all symbols and add it into vmlinux 397 # It's a three step process: 398 # 1) Link .tmp_vmlinux1 so it has all symbols and sections, 399 # but __kallsyms is empty. 400 # Running kallsyms on that gives us .tmp_kallsyms1.o with 401 # the right size 402 # 2) Link .tmp_vmlinux2 so it now has a __kallsyms section of 403 # the right size, but due to the added section, some 404 # addresses have shifted. 405 # From here, we generate a correct .tmp_kallsyms2.o 406 # 3) That link may have expanded the kernel image enough that 407 # more linker branch stubs / trampolines had to be added, which 408 # introduces new names, which further expands kallsyms. Do another 409 # pass if that is the case. In theory it's possible this results 410 # in even more stubs, but unlikely. 411 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around 412 # other bugs. 413 # 4) The correct ${kallsymso} is linked into the final vmlinux. 414 # 415 # a) Verify that the System.map from vmlinux matches the map from 416 # ${kallsymso}. 417 418 kallsyms_step 1 419 kallsyms_step 2 420 421 # step 3 422 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev}) 423 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 424 425 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then 426 kallsyms_step 3 427 fi 428fi 429 430vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o} 431 432# fill in BTF IDs 433if [ -n "${CONFIG_DEBUG_INFO_BTF}" -a -n "${CONFIG_BPF}" ]; then 434 info BTFIDS vmlinux 435 ${RESOLVE_BTFIDS} vmlinux 436fi 437 438if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then 439 info SORTTAB vmlinux 440 if ! sorttable vmlinux; then 441 echo >&2 Failed to sort kernel tables 442 exit 1 443 fi 444fi 445 446info SYSMAP System.map 447mksysmap vmlinux System.map 448 449# step a (see comment above) 450if [ -n "${CONFIG_KALLSYMS}" ]; then 451 mksysmap ${kallsyms_vmlinux} .tmp_System.map 452 453 if ! cmp -s System.map .tmp_System.map; then 454 echo >&2 Inconsistent kallsyms data 455 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround 456 exit 1 457 fi 458fi 459