1#!/bin/sh 2# SPDX-License-Identifier: GPL-2.0 3# 4# link vmlinux 5# 6# vmlinux is linked from the objects in vmlinux.a and $(KBUILD_VMLINUX_LIBS). 7# vmlinux.a contains objects that are linked unconditionally. 8# $(KBUILD_VMLINUX_LIBS) are archives which are linked conditionally 9# (not within --whole-archive), and do not require symbol indexes added. 10# 11# vmlinux 12# ^ 13# | 14# +--< vmlinux.a 15# | 16# +--< $(KBUILD_VMLINUX_LIBS) 17# | +--< lib/lib.a + more 18# | 19# +-< ${kallsymso} (see description in KALLSYMS section) 20# 21# vmlinux version (uname -v) cannot be updated during normal 22# descending-into-subdirs phase since we do not yet know if we need to 23# update vmlinux. 24# Therefore this step is delayed until just before final link of vmlinux. 25# 26# System.map is generated to document addresses of all kernel symbols 27 28# Error out on error 29set -e 30 31LD="$1" 32KBUILD_LDFLAGS="$2" 33LDFLAGS_vmlinux="$3" 34 35is_enabled() { 36 grep -q "^$1=y" include/config/auto.conf 37} 38 39# Nice output in kbuild format 40# Will be supressed by "make -s" 41info() 42{ 43 printf " %-7s %s\n" "${1}" "${2}" 44} 45 46# Link of vmlinux 47# ${1} - output file 48vmlinux_link() 49{ 50 local output=${1} 51 local objs 52 local libs 53 local ld 54 local ldflags 55 local ldlibs 56 57 info LD ${output} 58 59 # skip output file argument 60 shift 61 62 if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then 63 # Use vmlinux.o instead of performing the slow LTO link again. 64 objs=vmlinux.o 65 libs= 66 else 67 objs=vmlinux.a 68 libs="${KBUILD_VMLINUX_LIBS}" 69 fi 70 71 if is_enabled CONFIG_MODULES; then 72 objs="${objs} .vmlinux.export.o" 73 fi 74 75 objs="${objs} init/version-timestamp.o" 76 77 if [ "${SRCARCH}" = "um" ]; then 78 wl=-Wl, 79 ld="${CC}" 80 ldflags="${CFLAGS_vmlinux}" 81 ldlibs="-lutil -lrt -lpthread" 82 else 83 wl= 84 ld="${LD}" 85 ldflags="${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}" 86 ldlibs= 87 fi 88 89 ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}" 90 91 # The kallsyms linking does not need debug symbols included. 92 if [ -n "${strip_debug}" ] ; then 93 ldflags="${ldflags} ${wl}--strip-debug" 94 fi 95 96 if is_enabled CONFIG_VMLINUX_MAP; then 97 ldflags="${ldflags} ${wl}-Map=${output}.map" 98 fi 99 100 ${ld} ${ldflags} -o ${output} \ 101 ${wl}--whole-archive ${objs} ${wl}--no-whole-archive \ 102 ${wl}--start-group ${libs} ${wl}--end-group \ 103 ${kallsymso} ${btf_vmlinux_bin_o} ${ldlibs} 104} 105 106# generate .BTF typeinfo from DWARF debuginfo 107# ${1} - vmlinux image 108# ${2} - file to dump raw BTF data into 109gen_btf() 110{ 111 local pahole_ver 112 local btf_data=${2} 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 ${1} 126 127 info BTF "${btf_data}" 128 LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1} 129 130 # Create ${btf_data} 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 ${1} "${btf_data}" 2>/dev/null 137 # Change e_type to ET_REL so that it can be used to link final vmlinux. 138 # GNU ld 2.35+ and lld do not allow an ET_EXEC input. 139 if is_enabled CONFIG_CPU_BIG_ENDIAN; then 140 et_rel='\0\1' 141 else 142 et_rel='\1\0' 143 fi 144 printf "${et_rel}" | dd of="${btf_data}" conv=notrunc bs=1 seek=16 status=none 145 146 btf_vmlinux_bin_o=${btf_data} 147} 148 149# Create ${2}.o file with all symbols from the ${1} object file 150kallsyms() 151{ 152 local kallsymopt; 153 154 if is_enabled CONFIG_KALLSYMS_ALL; then 155 kallsymopt="${kallsymopt} --all-symbols" 156 fi 157 158 if is_enabled CONFIG_KALLSYMS_ABSOLUTE_PERCPU; then 159 kallsymopt="${kallsymopt} --absolute-percpu" 160 fi 161 162 if is_enabled CONFIG_KALLSYMS_BASE_RELATIVE; then 163 kallsymopt="${kallsymopt} --base-relative" 164 fi 165 166 if is_enabled CONFIG_LTO_CLANG; then 167 kallsymopt="${kallsymopt} --lto-clang" 168 fi 169 170 info KSYMS "${2}.S" 171 scripts/kallsyms ${kallsymopt} "${1}" > "${2}.S" 172 173 info AS "${2}.o" 174 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \ 175 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} -c -o "${2}.o" "${2}.S" 176 177 kallsymso=${2}.o 178} 179 180# Perform one step in kallsyms generation, including temporary linking of 181# vmlinux. 182kallsyms_step() 183{ 184 kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1} 185 186 vmlinux_link "${kallsyms_vmlinux}" 187 mksysmap "${kallsyms_vmlinux}" "${kallsyms_vmlinux}.syms" 188 kallsyms "${kallsyms_vmlinux}.syms" "${kallsyms_vmlinux}" 189} 190 191# Create map file with all symbols from ${1} 192# See mksymap for additional details 193mksysmap() 194{ 195 info NM ${2} 196 ${NM} -n "${1}" | sed -f "${srctree}/scripts/mksysmap" > "${2}" 197} 198 199sorttable() 200{ 201 ${objtree}/scripts/sorttable ${1} 202} 203 204cleanup() 205{ 206 rm -f .btf.* 207 rm -f System.map 208 rm -f vmlinux 209 rm -f vmlinux.map 210} 211 212# Use "make V=1" to debug this script 213case "${KBUILD_VERBOSE}" in 214*1*) 215 set -x 216 ;; 217esac 218 219if [ "$1" = "clean" ]; then 220 cleanup 221 exit 0 222fi 223 224${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init init/version-timestamp.o 225 226btf_vmlinux_bin_o= 227kallsymso= 228strip_debug= 229 230if is_enabled CONFIG_DEBUG_INFO_BTF; then 231 if ! gen_btf .tmp_vmlinux.btf .btf.vmlinux.bin.o ; then 232 echo >&2 "Failed to generate BTF for vmlinux" 233 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF" 234 exit 1 235 fi 236fi 237 238if is_enabled CONFIG_KALLSYMS; then 239 240 # kallsyms support 241 # Generate section listing all symbols and add it into vmlinux 242 # It's a three step process: 243 # 1) Link .tmp_vmlinux.kallsyms1 so it has all symbols and sections, 244 # but __kallsyms is empty. 245 # Running kallsyms on that gives us .tmp_kallsyms1.o with 246 # the right size 247 # 2) Link .tmp_vmlinux.kallsyms2 so it now has a __kallsyms section of 248 # the right size, but due to the added section, some 249 # addresses have shifted. 250 # From here, we generate a correct .tmp_vmlinux.kallsyms2.o 251 # 3) That link may have expanded the kernel image enough that 252 # more linker branch stubs / trampolines had to be added, which 253 # introduces new names, which further expands kallsyms. Do another 254 # pass if that is the case. In theory it's possible this results 255 # in even more stubs, but unlikely. 256 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around 257 # other bugs. 258 # 4) The correct ${kallsymso} is linked into the final vmlinux. 259 # 260 # a) Verify that the System.map from vmlinux matches the map from 261 # ${kallsymso}. 262 263 # The kallsyms linking does not need debug symbols included. 264 strip_debug=1 265 266 kallsyms_step 1 267 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 268 269 kallsyms_step 2 270 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 271 272 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then 273 kallsyms_step 3 274 fi 275fi 276 277strip_debug= 278 279vmlinux_link vmlinux 280 281# fill in BTF IDs 282if is_enabled CONFIG_DEBUG_INFO_BTF && is_enabled CONFIG_BPF; then 283 info BTFIDS vmlinux 284 ${RESOLVE_BTFIDS} vmlinux 285fi 286 287mksysmap vmlinux System.map 288 289if is_enabled CONFIG_BUILDTIME_TABLE_SORT; then 290 info SORTTAB vmlinux 291 if ! sorttable vmlinux; then 292 echo >&2 Failed to sort kernel tables 293 exit 1 294 fi 295fi 296 297# step a (see comment above) 298if is_enabled CONFIG_KALLSYMS; then 299 if ! cmp -s System.map ${kallsyms_vmlinux}.syms; then 300 echo >&2 Inconsistent kallsyms data 301 echo >&2 'Try "make KALLSYMS_EXTRA_PASS=1" as a workaround' 302 exit 1 303 fi 304fi 305 306# For fixdep 307echo "vmlinux: $0" > .vmlinux.d 308