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