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# +-< ${kallsymso} (see description in KALLSYMS section) 22# 23# vmlinux version (uname -v) cannot be updated during normal 24# descending-into-subdirs phase since we do not yet know if we need to 25# update vmlinux. 26# Therefore this step is delayed until just before final link of vmlinux. 27# 28# System.map is generated to document addresses of all kernel symbols 29 30# Error out on error 31set -e 32 33# Nice output in kbuild format 34# Will be supressed by "make -s" 35info() 36{ 37 if [ "${quiet}" != "silent_" ]; then 38 printf " %-7s %s\n" "${1}" "${2}" 39 fi 40} 41 42# If CONFIG_LTO_CLANG is selected, generate a linker script to ensure correct 43# ordering of initcalls, and with CONFIG_MODVERSIONS also enabled, collect the 44# previously generated symbol versions into the same script. 45lto_lds() 46{ 47 if [ -z "${CONFIG_LTO_CLANG}" ]; then 48 return 49 fi 50 51 ${srctree}/scripts/generate_initcall_order.pl \ 52 ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS} \ 53 > .tmp_lto.lds 54 55 if [ -n "${CONFIG_MODVERSIONS}" ]; then 56 for a in ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS}; do 57 for o in $(${AR} t $a 2>/dev/null); do 58 if [ -f ${o}.symversions ]; then 59 cat ${o}.symversions >> .tmp_lto.lds 60 fi 61 done 62 done 63 fi 64 65 echo "-T .tmp_lto.lds" 66} 67 68# Link of vmlinux.o used for section mismatch analysis 69# ${1} output file 70modpost_link() 71{ 72 local objects 73 74 objects="--whole-archive \ 75 ${KBUILD_VMLINUX_OBJS} \ 76 --no-whole-archive \ 77 --start-group \ 78 ${KBUILD_VMLINUX_LIBS} \ 79 --end-group" 80 81 if [ -n "${CONFIG_LTO_CLANG}" ]; then 82 # This might take a while, so indicate that we're doing 83 # an LTO link 84 info LTO ${1} 85 else 86 info LD ${1} 87 fi 88 89 ${LD} ${KBUILD_LDFLAGS} -r -o ${1} $(lto_lds) ${objects} 90} 91 92# If CONFIG_LTO_CLANG is selected, we postpone running recordmcount until 93# we have compiled LLVM IR to an object file. 94recordmcount() 95{ 96 if [ -z "${CONFIG_LTO_CLANG}" ]; then 97 return 98 fi 99 100 if [ -n "${CONFIG_FTRACE_MCOUNT_RECORD}" ]; then 101 scripts/recordmcount ${RECORDMCOUNT_FLAGS} $* 102 fi 103} 104 105# Link of vmlinux 106# ${1} - output file 107# ${2}, ${3}, ... - optional extra .o files 108vmlinux_link() 109{ 110 local lds="${objtree}/${KBUILD_LDS}" 111 local output=${1} 112 local objects 113 local strip_debug 114 115 info LD ${output} 116 117 # skip output file argument 118 shift 119 120 # The kallsyms linking does not need debug symbols included. 121 if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then 122 strip_debug=-Wl,--strip-debug 123 fi 124 125 if [ "${SRCARCH}" != "um" ]; then 126 if [ -n "${CONFIG_LTO_CLANG}" ]; then 127 # Use vmlinux.o instead of performing the slow LTO 128 # link again. 129 objects="--whole-archive \ 130 vmlinux.o \ 131 --no-whole-archive \ 132 ${@}" 133 else 134 objects="--whole-archive \ 135 ${KBUILD_VMLINUX_OBJS} \ 136 --no-whole-archive \ 137 --start-group \ 138 ${KBUILD_VMLINUX_LIBS} \ 139 --end-group \ 140 ${@}" 141 fi 142 143 ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} \ 144 ${strip_debug#-Wl,} \ 145 -o ${output} \ 146 -T ${lds} ${objects} 147 else 148 objects="-Wl,--whole-archive \ 149 ${KBUILD_VMLINUX_OBJS} \ 150 -Wl,--no-whole-archive \ 151 -Wl,--start-group \ 152 ${KBUILD_VMLINUX_LIBS} \ 153 -Wl,--end-group \ 154 ${@}" 155 156 ${CC} ${CFLAGS_vmlinux} \ 157 ${strip_debug} \ 158 -o ${output} \ 159 -Wl,-T,${lds} \ 160 ${objects} \ 161 -lutil -lrt -lpthread 162 rm -f linux 163 fi 164} 165 166# generate .BTF typeinfo from DWARF debuginfo 167# ${1} - vmlinux image 168# ${2} - file to dump raw BTF data into 169gen_btf() 170{ 171 local pahole_ver 172 173 if ! [ -x "$(command -v ${PAHOLE})" ]; then 174 echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available" 175 return 1 176 fi 177 178 pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/') 179 if [ "${pahole_ver}" -lt "113" ]; then 180 echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.13" 181 return 1 182 fi 183 184 vmlinux_link ${1} 185 186 info "BTF" ${2} 187 LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1} 188 189 # Create ${2} which contains just .BTF section but no symbols. Add 190 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all 191 # deletes all symbols including __start_BTF and __stop_BTF, which will 192 # be redefined in the linker script. Add 2>/dev/null to suppress GNU 193 # objcopy warnings: "empty loadable segment detected at ..." 194 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \ 195 --strip-all ${1} ${2} 2>/dev/null 196 # Change e_type to ET_REL so that it can be used to link final vmlinux. 197 # GNU ld 2.35+ and lld do not allow an ET_EXEC input. 198 if [ -n "${CONFIG_CPU_BIG_ENDIAN}" ]; then 199 et_rel='\0\1' 200 else 201 et_rel='\1\0' 202 fi 203 printf "${et_rel}" | dd of=${2} conv=notrunc bs=1 seek=16 status=none 204} 205 206# Create ${2} .o file with all symbols from the ${1} object file 207kallsyms() 208{ 209 info KSYM ${2} 210 local kallsymopt; 211 212 if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then 213 kallsymopt="${kallsymopt} --all-symbols" 214 fi 215 216 if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then 217 kallsymopt="${kallsymopt} --absolute-percpu" 218 fi 219 220 if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then 221 kallsymopt="${kallsymopt} --base-relative" 222 fi 223 224 local aflags="${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \ 225 ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS}" 226 227 local afile="`basename ${2} .o`.S" 228 229 ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${afile} 230 ${CC} ${aflags} -c -o ${2} ${afile} 231} 232 233# Perform one step in kallsyms generation, including temporary linking of 234# vmlinux. 235kallsyms_step() 236{ 237 kallsymso_prev=${kallsymso} 238 kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1} 239 kallsymso=${kallsyms_vmlinux}.o 240 241 vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o} 242 kallsyms ${kallsyms_vmlinux} ${kallsymso} 243} 244 245# Create map file with all symbols from ${1} 246# See mksymap for additional details 247mksysmap() 248{ 249 ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2} 250} 251 252sortextable() 253{ 254 ${objtree}/scripts/sortextable ${1} 255} 256 257# Delete output files in case of error 258cleanup() 259{ 260 rm -f .btf.* 261 rm -f .tmp_System.map 262 rm -f .tmp_lto.lds 263 rm -f .tmp_vmlinux* 264 rm -f System.map 265 rm -f vmlinux 266 rm -f vmlinux.o 267} 268 269on_exit() 270{ 271 if [ $? -ne 0 ]; then 272 cleanup 273 fi 274} 275trap on_exit EXIT 276 277on_signals() 278{ 279 exit 1 280} 281trap on_signals HUP INT QUIT TERM 282 283# 284# 285# Use "make V=1" to debug this script 286case "${KBUILD_VERBOSE}" in 287*1*) 288 set -x 289 ;; 290esac 291 292if [ "$1" = "clean" ]; then 293 cleanup 294 exit 0 295fi 296 297# We need access to CONFIG_ symbols 298. include/config/auto.conf 299 300# Update version 301info GEN .version 302if [ -r .version ]; then 303 VERSION=$(expr 0$(cat .version) + 1) 304 echo $VERSION > .version 305else 306 rm -f .version 307 echo 1 > .version 308fi; 309 310# final build of init/ 311${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init 312 313#link vmlinux.o 314modpost_link vmlinux.o 315 316# modpost vmlinux.o to check for section mismatches 317${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1 318 319if [ -n "${CONFIG_LTO_CLANG}" ]; then 320 # Call recordmcount if needed 321 recordmcount vmlinux.o 322fi 323 324info MODINFO modules.builtin.modinfo 325${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo 326 327btf_vmlinux_bin_o="" 328if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then 329 btf_vmlinux_bin_o=.btf.vmlinux.bin.o 330 if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then 331 echo >&2 "Failed to generate BTF for vmlinux" 332 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF" 333 exit 1 334 fi 335fi 336 337kallsymso="" 338kallsymso_prev="" 339kallsyms_vmlinux="" 340if [ -n "${CONFIG_KALLSYMS}" ]; then 341 342 # kallsyms support 343 # Generate section listing all symbols and add it into vmlinux 344 # It's a three step process: 345 # 1) Link .tmp_vmlinux1 so it has all symbols and sections, 346 # but __kallsyms is empty. 347 # Running kallsyms on that gives us .tmp_kallsyms1.o with 348 # the right size 349 # 2) Link .tmp_vmlinux2 so it now has a __kallsyms section of 350 # the right size, but due to the added section, some 351 # addresses have shifted. 352 # From here, we generate a correct .tmp_kallsyms2.o 353 # 3) That link may have expanded the kernel image enough that 354 # more linker branch stubs / trampolines had to be added, which 355 # introduces new names, which further expands kallsyms. Do another 356 # pass if that is the case. In theory it's possible this results 357 # in even more stubs, but unlikely. 358 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around 359 # other bugs. 360 # 4) The correct ${kallsymso} is linked into the final vmlinux. 361 # 362 # a) Verify that the System.map from vmlinux matches the map from 363 # ${kallsymso}. 364 365 kallsyms_step 1 366 kallsyms_step 2 367 368 # step 3 369 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev}) 370 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 371 372 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then 373 kallsyms_step 3 374 fi 375fi 376 377vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o} 378 379if [ -n "${CONFIG_BUILDTIME_EXTABLE_SORT}" ]; then 380 info SORTEX vmlinux 381 sortextable vmlinux 382fi 383 384info SYSMAP System.map 385mksysmap vmlinux System.map 386 387# step a (see comment above) 388if [ -n "${CONFIG_KALLSYMS}" ]; then 389 mksysmap ${kallsyms_vmlinux} .tmp_System.map 390 391 if ! cmp -s System.map .tmp_System.map; then 392 echo >&2 Inconsistent kallsyms data 393 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround 394 exit 1 395 fi 396fi 397