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# Link of vmlinux.o used for section mismatch analysis 43# ${1} output file 44modpost_link() 45{ 46 local objects 47 48 objects="--whole-archive \ 49 ${KBUILD_VMLINUX_OBJS} \ 50 --no-whole-archive \ 51 --start-group \ 52 ${KBUILD_VMLINUX_LIBS} \ 53 --end-group" 54 55 ${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${objects} 56} 57 58objtool_link() 59{ 60 local objtoolopt; 61 62 if [ -n "${CONFIG_VMLINUX_VALIDATION}" ]; then 63 objtoolopt="check" 64 if [ -z "${CONFIG_FRAME_POINTER}" ]; then 65 objtoolopt="${objtoolopt} --no-fp" 66 fi 67 if [ -n "${CONFIG_GCOV_KERNEL}" ]; then 68 objtoolopt="${objtoolopt} --no-unreachable" 69 fi 70 if [ -n "${CONFIG_RETPOLINE}" ]; then 71 objtoolopt="${objtoolopt} --retpoline" 72 fi 73 if [ -n "${CONFIG_X86_SMAP}" ]; then 74 objtoolopt="${objtoolopt} --uaccess" 75 fi 76 info OBJTOOL ${1} 77 tools/objtool/objtool ${objtoolopt} ${1} 78 fi 79} 80 81# Link of vmlinux 82# ${1} - output file 83# ${2}, ${3}, ... - optional extra .o files 84vmlinux_link() 85{ 86 local lds="${objtree}/${KBUILD_LDS}" 87 local output=${1} 88 local objects 89 local strip_debug 90 91 info LD ${output} 92 93 # skip output file argument 94 shift 95 96 # The kallsyms linking does not need debug symbols included. 97 if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then 98 strip_debug=-Wl,--strip-debug 99 fi 100 101 if [ "${SRCARCH}" != "um" ]; then 102 objects="--whole-archive \ 103 ${KBUILD_VMLINUX_OBJS} \ 104 --no-whole-archive \ 105 --start-group \ 106 ${KBUILD_VMLINUX_LIBS} \ 107 --end-group \ 108 ${@}" 109 110 ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} \ 111 ${strip_debug#-Wl,} \ 112 -o ${output} \ 113 -T ${lds} ${objects} 114 else 115 objects="-Wl,--whole-archive \ 116 ${KBUILD_VMLINUX_OBJS} \ 117 -Wl,--no-whole-archive \ 118 -Wl,--start-group \ 119 ${KBUILD_VMLINUX_LIBS} \ 120 -Wl,--end-group \ 121 ${@}" 122 123 ${CC} ${CFLAGS_vmlinux} \ 124 ${strip_debug} \ 125 -o ${output} \ 126 -Wl,-T,${lds} \ 127 ${objects} \ 128 -lutil -lrt -lpthread 129 rm -f linux 130 fi 131} 132 133# generate .BTF typeinfo from DWARF debuginfo 134# ${1} - vmlinux image 135# ${2} - file to dump raw BTF data into 136gen_btf() 137{ 138 local pahole_ver 139 140 if ! [ -x "$(command -v ${PAHOLE})" ]; then 141 echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available" 142 return 1 143 fi 144 145 pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/') 146 if [ "${pahole_ver}" -lt "113" ]; then 147 echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.13" 148 return 1 149 fi 150 151 vmlinux_link ${1} 152 153 info "BTF" ${2} 154 LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1} 155 156 # Create ${2} which contains just .BTF section but no symbols. Add 157 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all 158 # deletes all symbols including __start_BTF and __stop_BTF, which will 159 # be redefined in the linker script. Add 2>/dev/null to suppress GNU 160 # objcopy warnings: "empty loadable segment detected at ..." 161 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \ 162 --strip-all ${1} ${2} 2>/dev/null 163 # Change e_type to ET_REL so that it can be used to link final vmlinux. 164 # Unlike GNU ld, lld does not allow an ET_EXEC input. 165 printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none 166} 167 168# Create ${2} .o file with all symbols from the ${1} object file 169kallsyms() 170{ 171 info KSYM ${2} 172 local kallsymopt; 173 174 if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then 175 kallsymopt="${kallsymopt} --all-symbols" 176 fi 177 178 if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then 179 kallsymopt="${kallsymopt} --absolute-percpu" 180 fi 181 182 if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then 183 kallsymopt="${kallsymopt} --base-relative" 184 fi 185 186 local aflags="${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \ 187 ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS}" 188 189 local afile="`basename ${2} .o`.S" 190 191 ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${afile} 192 ${CC} ${aflags} -c -o ${2} ${afile} 193} 194 195# Perform one step in kallsyms generation, including temporary linking of 196# vmlinux. 197kallsyms_step() 198{ 199 kallsymso_prev=${kallsymso} 200 kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1} 201 kallsymso=${kallsyms_vmlinux}.o 202 203 vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o} 204 kallsyms ${kallsyms_vmlinux} ${kallsymso} 205} 206 207# Create map file with all symbols from ${1} 208# See mksymap for additional details 209mksysmap() 210{ 211 ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2} 212} 213 214sorttable() 215{ 216 ${objtree}/scripts/sorttable ${1} 217} 218 219# Delete output files in case of error 220cleanup() 221{ 222 rm -f .btf.* 223 rm -f .tmp_System.map 224 rm -f .tmp_vmlinux* 225 rm -f System.map 226 rm -f vmlinux 227 rm -f vmlinux.o 228} 229 230on_exit() 231{ 232 if [ $? -ne 0 ]; then 233 cleanup 234 fi 235} 236trap on_exit EXIT 237 238on_signals() 239{ 240 exit 1 241} 242trap on_signals HUP INT QUIT TERM 243 244# Use "make V=1" to debug this script 245case "${KBUILD_VERBOSE}" in 246*1*) 247 set -x 248 ;; 249esac 250 251if [ "$1" = "clean" ]; then 252 cleanup 253 exit 0 254fi 255 256# We need access to CONFIG_ symbols 257. include/config/auto.conf 258 259# Update version 260info GEN .version 261if [ -r .version ]; then 262 VERSION=$(expr 0$(cat .version) + 1) 263 echo $VERSION > .version 264else 265 rm -f .version 266 echo 1 > .version 267fi; 268 269# final build of init/ 270${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1 271 272#link vmlinux.o 273info LD vmlinux.o 274modpost_link vmlinux.o 275objtool_link vmlinux.o 276 277# modpost vmlinux.o to check for section mismatches 278${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1 279 280info MODINFO modules.builtin.modinfo 281${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo 282info GEN modules.builtin 283# The second line aids cases where multiple modules share the same object. 284tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' | 285 tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin 286 287btf_vmlinux_bin_o="" 288if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then 289 btf_vmlinux_bin_o=.btf.vmlinux.bin.o 290 if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then 291 echo >&2 "Failed to generate BTF for vmlinux" 292 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF" 293 exit 1 294 fi 295fi 296 297kallsymso="" 298kallsymso_prev="" 299kallsyms_vmlinux="" 300if [ -n "${CONFIG_KALLSYMS}" ]; then 301 302 # kallsyms support 303 # Generate section listing all symbols and add it into vmlinux 304 # It's a three step process: 305 # 1) Link .tmp_vmlinux1 so it has all symbols and sections, 306 # but __kallsyms is empty. 307 # Running kallsyms on that gives us .tmp_kallsyms1.o with 308 # the right size 309 # 2) Link .tmp_vmlinux2 so it now has a __kallsyms section of 310 # the right size, but due to the added section, some 311 # addresses have shifted. 312 # From here, we generate a correct .tmp_kallsyms2.o 313 # 3) That link may have expanded the kernel image enough that 314 # more linker branch stubs / trampolines had to be added, which 315 # introduces new names, which further expands kallsyms. Do another 316 # pass if that is the case. In theory it's possible this results 317 # in even more stubs, but unlikely. 318 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around 319 # other bugs. 320 # 4) The correct ${kallsymso} is linked into the final vmlinux. 321 # 322 # a) Verify that the System.map from vmlinux matches the map from 323 # ${kallsymso}. 324 325 kallsyms_step 1 326 kallsyms_step 2 327 328 # step 3 329 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev}) 330 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 331 332 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then 333 kallsyms_step 3 334 fi 335fi 336 337vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o} 338 339if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then 340 info SORTTAB vmlinux 341 if ! sorttable vmlinux; then 342 echo >&2 Failed to sort kernel tables 343 exit 1 344 fi 345fi 346 347info SYSMAP System.map 348mksysmap vmlinux System.map 349 350# step a (see comment above) 351if [ -n "${CONFIG_KALLSYMS}" ]; then 352 mksysmap ${kallsyms_vmlinux} .tmp_System.map 353 354 if ! cmp -s System.map .tmp_System.map; then 355 echo >&2 Inconsistent kallsyms data 356 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround 357 exit 1 358 fi 359fi 360