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 ${PYTHON3} ${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} ${objects} 102} 103 104objtool_link() 105{ 106 local objtoolopt; 107 108 if [ -n "${CONFIG_VMLINUX_VALIDATION}" ]; then 109 objtoolopt="check" 110 if [ -n "${CONFIG_CPU_UNRET_ENTRY}" ]; then 111 objtoolopt="${objtoolopt} --unret" 112 fi 113 if [ -z "${CONFIG_FRAME_POINTER}" ]; then 114 objtoolopt="${objtoolopt} --no-fp" 115 fi 116 if [ -n "${CONFIG_GCOV_KERNEL}" ]; then 117 objtoolopt="${objtoolopt} --no-unreachable" 118 fi 119 if [ -n "${CONFIG_RETPOLINE}" ]; then 120 objtoolopt="${objtoolopt} --retpoline" 121 fi 122 if [ -n "${CONFIG_X86_SMAP}" ]; then 123 objtoolopt="${objtoolopt} --uaccess" 124 fi 125 if [ -n "${CONFIG_SLS}" ]; then 126 objtoolopt="${objtoolopt} --sls" 127 fi 128 info OBJTOOL ${1} 129 tools/objtool/objtool ${objtoolopt} ${1} 130 fi 131} 132 133# Link of vmlinux 134# ${1} - output file 135# ${2}, ${3}, ... - optional extra .o files 136vmlinux_link() 137{ 138 local lds="${objtree}/${KBUILD_LDS}" 139 local output=${1} 140 local objects 141 local strip_debug 142 143 info LD ${output} 144 145 # skip output file argument 146 shift 147 148 # The kallsyms linking does not need debug symbols included. 149 if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then 150 strip_debug=-Wl,--strip-debug 151 fi 152 153 if [ "${SRCARCH}" != "um" ]; then 154 if [ -n "${CONFIG_LTO_CLANG}" ]; then 155 # Use vmlinux.o instead of performing the slow LTO 156 # link again. 157 objects="--whole-archive \ 158 vmlinux.o \ 159 --no-whole-archive \ 160 ${@}" 161 else 162 objects="--whole-archive \ 163 ${KBUILD_VMLINUX_OBJS} \ 164 --no-whole-archive \ 165 --start-group \ 166 ${KBUILD_VMLINUX_LIBS} \ 167 --end-group \ 168 ${@}" 169 fi 170 171 ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} \ 172 ${strip_debug#-Wl,} \ 173 -o ${output} \ 174 -T ${lds} ${objects} 175 else 176 objects="-Wl,--whole-archive \ 177 ${KBUILD_VMLINUX_OBJS} \ 178 -Wl,--no-whole-archive \ 179 -Wl,--start-group \ 180 ${KBUILD_VMLINUX_LIBS} \ 181 -Wl,--end-group \ 182 ${@}" 183 184 ${CC} ${CFLAGS_vmlinux} \ 185 ${strip_debug} \ 186 -o ${output} \ 187 -Wl,-T,${lds} \ 188 ${objects} \ 189 -lutil -lrt -lpthread 190 rm -f linux 191 fi 192} 193 194# generate .BTF typeinfo from DWARF debuginfo 195# ${1} - vmlinux image 196# ${2} - file to dump raw BTF data into 197gen_btf() 198{ 199 local pahole_ver 200 201 if ! [ -x "$(command -v ${PAHOLE})" ]; then 202 echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available" 203 return 1 204 fi 205 206 pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/') 207 if [ "${pahole_ver}" -lt "116" ]; then 208 echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.16" 209 return 1 210 fi 211 212 vmlinux_link ${1} 213 214 info "BTF" ${2} 215 LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1} 216 217 # Create ${2} which contains just .BTF section but no symbols. Add 218 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all 219 # deletes all symbols including __start_BTF and __stop_BTF, which will 220 # be redefined in the linker script. Add 2>/dev/null to suppress GNU 221 # objcopy warnings: "empty loadable segment detected at ..." 222 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \ 223 --strip-all ${1} ${2} 2>/dev/null 224 # Change e_type to ET_REL so that it can be used to link final vmlinux. 225 # Unlike GNU ld, lld does not allow an ET_EXEC input. 226 printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none 227} 228 229# Create ${2} .S file with all symbols from the ${1} object file 230kallsyms() 231{ 232 local kallsymopt; 233 234 if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then 235 kallsymopt="${kallsymopt} --all-symbols" 236 fi 237 238 if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then 239 kallsymopt="${kallsymopt} --absolute-percpu" 240 fi 241 242 if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then 243 kallsymopt="${kallsymopt} --base-relative" 244 fi 245 246 info KSYMS ${2} 247 ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${2} 248} 249 250# Perform one step in kallsyms generation, including temporary linking of 251# vmlinux. 252kallsyms_step() 253{ 254 kallsymso_prev=${kallsymso} 255 kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1} 256 kallsymso=${kallsyms_vmlinux}.o 257 kallsyms_S=${kallsyms_vmlinux}.S 258 259 vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o} 260 kallsyms ${kallsyms_vmlinux} ${kallsyms_S} 261 262 info AS ${kallsyms_S} 263 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \ 264 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \ 265 -c -o ${kallsymso} ${kallsyms_S} 266} 267 268# Create map file with all symbols from ${1} 269# See mksymap for additional details 270mksysmap() 271{ 272 ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2} 273} 274 275sorttable() 276{ 277 ${objtree}/scripts/sorttable ${1} 278} 279 280# Delete output files in case of error 281cleanup() 282{ 283 rm -f .btf.* 284 rm -f .tmp_System.map 285 rm -f .tmp_initcalls.lds 286 rm -f .tmp_symversions.lds 287 rm -f .tmp_vmlinux* 288 rm -f System.map 289 rm -f vmlinux 290 rm -f vmlinux.o 291} 292 293on_exit() 294{ 295 if [ $? -ne 0 ]; then 296 cleanup 297 fi 298} 299trap on_exit EXIT 300 301on_signals() 302{ 303 exit 1 304} 305trap on_signals HUP INT QUIT TERM 306 307# Use "make V=1" to debug this script 308case "${KBUILD_VERBOSE}" in 309*1*) 310 set -x 311 ;; 312esac 313 314if [ "$1" = "clean" ]; then 315 cleanup 316 exit 0 317fi 318 319# We need access to CONFIG_ symbols 320. include/config/auto.conf 321 322# Update version 323info GEN .version 324if [ -r .version ]; then 325 VERSION=$(expr 0$(cat .version) + 1) 326 echo $VERSION > .version 327else 328 rm -f .version 329 echo 1 > .version 330fi; 331 332# final build of init/ 333${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1 334 335#link vmlinux.o 336modpost_link vmlinux.o 337objtool_link vmlinux.o 338 339# modpost vmlinux.o to check for section mismatches 340${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1 341 342info MODINFO modules.builtin.modinfo 343${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo 344info GEN modules.builtin 345# The second line aids cases where multiple modules share the same object. 346tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' | 347 tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin 348 349btf_vmlinux_bin_o="" 350if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then 351 btf_vmlinux_bin_o=.btf.vmlinux.bin.o 352 if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then 353 echo >&2 "Failed to generate BTF for vmlinux" 354 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF" 355 exit 1 356 fi 357fi 358 359kallsymso="" 360kallsymso_prev="" 361kallsyms_vmlinux="" 362if [ -n "${CONFIG_KALLSYMS}" ]; then 363 364 # kallsyms support 365 # Generate section listing all symbols and add it into vmlinux 366 # It's a three step process: 367 # 1) Link .tmp_vmlinux1 so it has all symbols and sections, 368 # but __kallsyms is empty. 369 # Running kallsyms on that gives us .tmp_kallsyms1.o with 370 # the right size 371 # 2) Link .tmp_vmlinux2 so it now has a __kallsyms section of 372 # the right size, but due to the added section, some 373 # addresses have shifted. 374 # From here, we generate a correct .tmp_kallsyms2.o 375 # 3) That link may have expanded the kernel image enough that 376 # more linker branch stubs / trampolines had to be added, which 377 # introduces new names, which further expands kallsyms. Do another 378 # pass if that is the case. In theory it's possible this results 379 # in even more stubs, but unlikely. 380 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around 381 # other bugs. 382 # 4) The correct ${kallsymso} is linked into the final vmlinux. 383 # 384 # a) Verify that the System.map from vmlinux matches the map from 385 # ${kallsymso}. 386 387 kallsyms_step 1 388 kallsyms_step 2 389 390 # step 3 391 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev}) 392 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 393 394 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then 395 kallsyms_step 3 396 fi 397fi 398 399vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o} 400 401# fill in BTF IDs 402if [ -n "${CONFIG_DEBUG_INFO_BTF}" -a -n "${CONFIG_BPF}" ]; then 403 info BTFIDS vmlinux 404 ${RESOLVE_BTFIDS} vmlinux 405fi 406 407if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then 408 info SORTTAB vmlinux 409 if ! sorttable vmlinux; then 410 echo >&2 Failed to sort kernel tables 411 exit 1 412 fi 413fi 414 415info SYSMAP System.map 416mksysmap vmlinux System.map 417 418# step a (see comment above) 419if [ -n "${CONFIG_KALLSYMS}" ]; then 420 mksysmap ${kallsyms_vmlinux} .tmp_System.map 421 422 if ! cmp -s System.map .tmp_System.map; then 423 echo >&2 Inconsistent kallsyms data 424 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround 425 exit 1 426 fi 427fi 428