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}, ${3}, ... - optional extra .o files 150vmlinux_link() 151{ 152 local lds="${objtree}/${KBUILD_LDS}" 153 local output=${1} 154 local objects 155 local strip_debug 156 local map_option 157 158 info LD ${output} 159 160 # skip output file argument 161 shift 162 163 # The kallsyms linking does not need debug symbols included. 164 if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then 165 strip_debug=-Wl,--strip-debug 166 fi 167 168 if [ -n "${CONFIG_VMLINUX_MAP}" ]; then 169 map_option="-Map=${output}.map" 170 fi 171 172 if [ "${SRCARCH}" != "um" ]; then 173 if [ -n "${CONFIG_LTO_CLANG}" ]; then 174 # Use vmlinux.o instead of performing the slow LTO 175 # link again. 176 objects="--whole-archive \ 177 vmlinux.o \ 178 --no-whole-archive \ 179 ${@}" 180 else 181 objects="--whole-archive \ 182 ${KBUILD_VMLINUX_OBJS} \ 183 --no-whole-archive \ 184 --start-group \ 185 ${KBUILD_VMLINUX_LIBS} \ 186 --end-group \ 187 ${@}" 188 fi 189 190 ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} \ 191 ${strip_debug#-Wl,} \ 192 -o ${output} \ 193 ${map_option} \ 194 -T ${lds} ${objects} 195 else 196 objects="-Wl,--whole-archive \ 197 ${KBUILD_VMLINUX_OBJS} \ 198 -Wl,--no-whole-archive \ 199 -Wl,--start-group \ 200 ${KBUILD_VMLINUX_LIBS} \ 201 -Wl,--end-group \ 202 ${@}" 203 204 ${CC} ${CFLAGS_vmlinux} \ 205 ${strip_debug} \ 206 -o ${output} \ 207 ${map_option:+-Wl,${map_option}} \ 208 -Wl,-T,${lds} \ 209 ${objects} \ 210 -lutil -lrt -lpthread 211 rm -f linux 212 fi 213} 214 215# generate .BTF typeinfo from DWARF debuginfo 216# ${1} - vmlinux image 217# ${2} - file to dump raw BTF data into 218gen_btf() 219{ 220 local pahole_ver 221 local extra_paholeopt= 222 223 if ! [ -x "$(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 ${1} 235 236 if [ "${pahole_ver}" -ge "118" ] && [ "${pahole_ver}" -le "121" ]; then 237 # pahole 1.18 through 1.21 can't handle zero-sized per-CPU vars 238 extra_paholeopt="${extra_paholeopt} --skip_encoding_btf_vars" 239 fi 240 if [ "${pahole_ver}" -ge "121" ]; then 241 extra_paholeopt="${extra_paholeopt} --btf_gen_floats" 242 fi 243 244 info "BTF" ${2} 245 LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${extra_paholeopt} ${1} 246 247 # Create ${2} which contains just .BTF section but no symbols. Add 248 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all 249 # deletes all symbols including __start_BTF and __stop_BTF, which will 250 # be redefined in the linker script. Add 2>/dev/null to suppress GNU 251 # objcopy warnings: "empty loadable segment detected at ..." 252 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \ 253 --strip-all ${1} ${2} 2>/dev/null 254 # Change e_type to ET_REL so that it can be used to link final vmlinux. 255 # Unlike GNU ld, lld does not allow an ET_EXEC input. 256 printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none 257} 258 259# Create ${2} .S file with all symbols from the ${1} object file 260kallsyms() 261{ 262 local kallsymopt; 263 264 if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then 265 kallsymopt="${kallsymopt} --all-symbols" 266 fi 267 268 if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then 269 kallsymopt="${kallsymopt} --absolute-percpu" 270 fi 271 272 if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then 273 kallsymopt="${kallsymopt} --base-relative" 274 fi 275 276 info KSYMS ${2} 277 ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${2} 278} 279 280# Perform one step in kallsyms generation, including temporary linking of 281# vmlinux. 282kallsyms_step() 283{ 284 kallsymso_prev=${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 ${1} 308} 309 310# Delete output files in case of error 311cleanup() 312{ 313 rm -f .btf.* 314 rm -f .tmp_System.map 315 rm -f .tmp_initcalls.lds 316 rm -f .tmp_symversions.lds 317 rm -f .tmp_vmlinux* 318 rm -f System.map 319 rm -f vmlinux 320 rm -f vmlinux.map 321 rm -f vmlinux.o 322 rm -f .vmlinux.d 323} 324 325# Use "make V=1" to debug this script 326case "${KBUILD_VERBOSE}" in 327*1*) 328 set -x 329 ;; 330esac 331 332if [ "$1" = "clean" ]; then 333 cleanup 334 exit 0 335fi 336 337# We need access to CONFIG_ symbols 338. include/config/auto.conf 339 340# Update version 341info GEN .version 342if [ -r .version ]; then 343 VERSION=$(expr 0$(cat .version) + 1) 344 echo $VERSION > .version 345else 346 rm -f .version 347 echo 1 > .version 348fi; 349 350# final build of init/ 351${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1 352 353#link vmlinux.o 354modpost_link vmlinux.o 355objtool_link vmlinux.o 356 357# modpost vmlinux.o to check for section mismatches 358${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1 359 360info MODINFO modules.builtin.modinfo 361${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo 362info GEN modules.builtin 363# The second line aids cases where multiple modules share the same object. 364tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' | 365 tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin 366 367btf_vmlinux_bin_o="" 368if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then 369 btf_vmlinux_bin_o=.btf.vmlinux.bin.o 370 if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then 371 echo >&2 "Failed to generate BTF for vmlinux" 372 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF" 373 exit 1 374 fi 375fi 376 377kallsymso="" 378kallsymso_prev="" 379kallsyms_vmlinux="" 380if [ -n "${CONFIG_KALLSYMS}" ]; then 381 382 # kallsyms support 383 # Generate section listing all symbols and add it into vmlinux 384 # It's a three step process: 385 # 1) Link .tmp_vmlinux1 so it has all symbols and sections, 386 # but __kallsyms is empty. 387 # Running kallsyms on that gives us .tmp_kallsyms1.o with 388 # the right size 389 # 2) Link .tmp_vmlinux2 so it now has a __kallsyms section of 390 # the right size, but due to the added section, some 391 # addresses have shifted. 392 # From here, we generate a correct .tmp_kallsyms2.o 393 # 3) That link may have expanded the kernel image enough that 394 # more linker branch stubs / trampolines had to be added, which 395 # introduces new names, which further expands kallsyms. Do another 396 # pass if that is the case. In theory it's possible this results 397 # in even more stubs, but unlikely. 398 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around 399 # other bugs. 400 # 4) The correct ${kallsymso} is linked into the final vmlinux. 401 # 402 # a) Verify that the System.map from vmlinux matches the map from 403 # ${kallsymso}. 404 405 kallsyms_step 1 406 kallsyms_step 2 407 408 # step 3 409 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev}) 410 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 411 412 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then 413 kallsyms_step 3 414 fi 415fi 416 417vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o} 418 419# fill in BTF IDs 420if [ -n "${CONFIG_DEBUG_INFO_BTF}" -a -n "${CONFIG_BPF}" ]; then 421 info BTFIDS vmlinux 422 ${RESOLVE_BTFIDS} vmlinux 423fi 424 425if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then 426 info SORTTAB vmlinux 427 if ! sorttable vmlinux; then 428 echo >&2 Failed to sort kernel tables 429 exit 1 430 fi 431fi 432 433info SYSMAP System.map 434mksysmap vmlinux System.map 435 436# step a (see comment above) 437if [ -n "${CONFIG_KALLSYMS}" ]; then 438 mksysmap ${kallsyms_vmlinux} .tmp_System.map 439 440 if ! cmp -s System.map .tmp_System.map; then 441 echo >&2 Inconsistent kallsyms data 442 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround 443 exit 1 444 fi 445fi 446 447# For fixdep 448echo "vmlinux: $0" > .vmlinux.d 449