link-vmlinux.sh (9073B)
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 37is_enabled() { 38 grep -q "^$1=y" include/config/auto.conf 39} 40 41# Nice output in kbuild format 42# Will be supressed by "make -s" 43info() 44{ 45 printf " %-7s %s\n" "${1}" "${2}" 46} 47 48# Link of vmlinux 49# ${1} - output file 50# ${2}, ${3}, ... - optional extra .o files 51vmlinux_link() 52{ 53 local output=${1} 54 local objs 55 local libs 56 local ld 57 local ldflags 58 local ldlibs 59 60 info LD ${output} 61 62 # skip output file argument 63 shift 64 65 if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then 66 # Use vmlinux.o instead of performing the slow LTO link again. 67 objs=vmlinux.o 68 libs= 69 else 70 objs="${KBUILD_VMLINUX_OBJS}" 71 libs="${KBUILD_VMLINUX_LIBS}" 72 fi 73 74 if is_enabled CONFIG_MODULES; then 75 objs="${objs} .vmlinux.export.o" 76 fi 77 78 if [ "${SRCARCH}" = "um" ]; then 79 wl=-Wl, 80 ld="${CC}" 81 ldflags="${CFLAGS_vmlinux}" 82 ldlibs="-lutil -lrt -lpthread" 83 else 84 wl= 85 ld="${LD}" 86 ldflags="${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}" 87 ldlibs= 88 fi 89 90 ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}" 91 92 # The kallsyms linking does not need debug symbols included. 93 if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then 94 ldflags="${ldflags} ${wl}--strip-debug" 95 fi 96 97 if is_enabled CONFIG_VMLINUX_MAP; then 98 ldflags="${ldflags} ${wl}-Map=${output}.map" 99 fi 100 101 ${ld} ${ldflags} -o ${output} \ 102 ${wl}--whole-archive ${objs} ${wl}--no-whole-archive \ 103 ${wl}--start-group ${libs} ${wl}--end-group \ 104 $@ ${ldlibs} 105} 106 107# generate .BTF typeinfo from DWARF debuginfo 108# ${1} - vmlinux image 109# ${2} - file to dump raw BTF data into 110gen_btf() 111{ 112 local pahole_ver 113 114 if ! [ -x "$(command -v ${PAHOLE})" ]; then 115 echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available" 116 return 1 117 fi 118 119 pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/') 120 if [ "${pahole_ver}" -lt "116" ]; then 121 echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.16" 122 return 1 123 fi 124 125 vmlinux_link ${1} 126 127 info "BTF" ${2} 128 LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1} 129 130 # Create ${2} which contains just .BTF section but no symbols. Add 131 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all 132 # deletes all symbols including __start_BTF and __stop_BTF, which will 133 # be redefined in the linker script. Add 2>/dev/null to suppress GNU 134 # objcopy warnings: "empty loadable segment detected at ..." 135 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \ 136 --strip-all ${1} ${2} 2>/dev/null 137 # Change e_type to ET_REL so that it can be used to link final vmlinux. 138 # Unlike GNU ld, lld does not allow an ET_EXEC input. 139 printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none 140} 141 142# Create ${2} .S file with all symbols from the ${1} object file 143kallsyms() 144{ 145 local kallsymopt; 146 147 if is_enabled CONFIG_KALLSYMS_ALL; then 148 kallsymopt="${kallsymopt} --all-symbols" 149 fi 150 151 if is_enabled CONFIG_KALLSYMS_ABSOLUTE_PERCPU; then 152 kallsymopt="${kallsymopt} --absolute-percpu" 153 fi 154 155 if is_enabled CONFIG_KALLSYMS_BASE_RELATIVE; then 156 kallsymopt="${kallsymopt} --base-relative" 157 fi 158 159 info KSYMS ${2} 160 ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${2} 161} 162 163# Perform one step in kallsyms generation, including temporary linking of 164# vmlinux. 165kallsyms_step() 166{ 167 kallsymso_prev=${kallsymso} 168 kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1} 169 kallsymso=${kallsyms_vmlinux}.o 170 kallsyms_S=${kallsyms_vmlinux}.S 171 172 vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o} 173 kallsyms ${kallsyms_vmlinux} ${kallsyms_S} 174 175 info AS ${kallsyms_S} 176 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \ 177 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \ 178 -c -o ${kallsymso} ${kallsyms_S} 179} 180 181# Create map file with all symbols from ${1} 182# See mksymap for additional details 183mksysmap() 184{ 185 ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2} 186} 187 188sorttable() 189{ 190 ${objtree}/scripts/sorttable ${1} 191} 192 193# Delete output files in case of error 194cleanup() 195{ 196 rm -f .btf.* 197 rm -f System.map 198 rm -f vmlinux 199 rm -f vmlinux.map 200 rm -f .vmlinux.objs 201 rm -f .vmlinux.export.c 202} 203 204# Use "make V=1" to debug this script 205case "${KBUILD_VERBOSE}" in 206*1*) 207 set -x 208 ;; 209esac 210 211if [ "$1" = "clean" ]; then 212 cleanup 213 exit 0 214fi 215 216# Update version 217info GEN .version 218if [ -r .version ]; then 219 VERSION=$(expr 0$(cat .version) + 1) 220 echo $VERSION > .version 221else 222 rm -f .version 223 echo 1 > .version 224fi; 225 226# final build of init/ 227${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1 228 229#link vmlinux.o 230${MAKE} -f "${srctree}/scripts/Makefile.vmlinux_o" 231 232# Generate the list of in-tree objects in vmlinux 233# 234# This is used to retrieve symbol versions generated by genksyms. 235for f in ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS}; do 236 case ${f} in 237 *libgcc.a) 238 # Some architectures do '$(CC) --print-libgcc-file-name' to 239 # borrow libgcc.a from the toolchain. 240 # There is no EXPORT_SYMBOL in external objects. Ignore this. 241 ;; 242 *.a) 243 ${AR} t ${f} ;; 244 *) 245 echo ${f} ;; 246 esac 247done > .vmlinux.objs 248 249# modpost vmlinux.o to check for section mismatches 250${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1 251 252info MODINFO modules.builtin.modinfo 253${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo 254info GEN modules.builtin 255# The second line aids cases where multiple modules share the same object. 256tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' | 257 tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin 258 259if is_enabled CONFIG_MODULES; then 260 ${MAKE} -f "${srctree}/scripts/Makefile.vmlinux" .vmlinux.export.o 261fi 262 263btf_vmlinux_bin_o="" 264if is_enabled CONFIG_DEBUG_INFO_BTF; then 265 btf_vmlinux_bin_o=.btf.vmlinux.bin.o 266 if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then 267 echo >&2 "Failed to generate BTF for vmlinux" 268 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF" 269 exit 1 270 fi 271fi 272 273kallsymso="" 274kallsymso_prev="" 275kallsyms_vmlinux="" 276if is_enabled CONFIG_KALLSYMS; then 277 278 # kallsyms support 279 # Generate section listing all symbols and add it into vmlinux 280 # It's a three step process: 281 # 1) Link .tmp_vmlinux.kallsyms1 so it has all symbols and sections, 282 # but __kallsyms is empty. 283 # Running kallsyms on that gives us .tmp_kallsyms1.o with 284 # the right size 285 # 2) Link .tmp_vmlinux.kallsyms2 so it now has a __kallsyms section of 286 # the right size, but due to the added section, some 287 # addresses have shifted. 288 # From here, we generate a correct .tmp_vmlinux.kallsyms2.o 289 # 3) That link may have expanded the kernel image enough that 290 # more linker branch stubs / trampolines had to be added, which 291 # introduces new names, which further expands kallsyms. Do another 292 # pass if that is the case. In theory it's possible this results 293 # in even more stubs, but unlikely. 294 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around 295 # other bugs. 296 # 4) The correct ${kallsymso} is linked into the final vmlinux. 297 # 298 # a) Verify that the System.map from vmlinux matches the map from 299 # ${kallsymso}. 300 301 kallsyms_step 1 302 kallsyms_step 2 303 304 # step 3 305 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev}) 306 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 307 308 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then 309 kallsyms_step 3 310 fi 311fi 312 313vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o} 314 315# fill in BTF IDs 316if is_enabled CONFIG_DEBUG_INFO_BTF && is_enabled CONFIG_BPF; then 317 info BTFIDS vmlinux 318 ${RESOLVE_BTFIDS} vmlinux 319fi 320 321info SYSMAP System.map 322mksysmap vmlinux System.map 323 324if is_enabled CONFIG_BUILDTIME_TABLE_SORT; then 325 info SORTTAB vmlinux 326 if ! sorttable vmlinux; then 327 echo >&2 Failed to sort kernel tables 328 exit 1 329 fi 330fi 331 332# step a (see comment above) 333if is_enabled CONFIG_KALLSYMS; then 334 mksysmap ${kallsyms_vmlinux} .tmp_System.map 335 336 if ! cmp -s System.map .tmp_System.map; then 337 echo >&2 Inconsistent kallsyms data 338 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround 339 exit 1 340 fi 341fi 342 343# For fixdep 344echo "vmlinux: $0" > .vmlinux.d