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="${objs} .vmlinux.export.o" 73 if is_enabled CONFIG_MODULE_SIG_PROTECT; then 74 objs="${objs} .vmlinux.protected-exports.o" 75 fi 76 if is_enabled CONFIG_TRIM_UNUSED_KSYMS; then 77 objs="${objs} .vmlinux.permitted-imports.o" 78 fi 79 fi 80 81 objs="${objs} init/version-timestamp.o" 82 83 if [ "${SRCARCH}" = "um" ]; then 84 wl=-Wl, 85 ld="${CC}" 86 ldflags="${CFLAGS_vmlinux}" 87 ldlibs="-lutil -lrt -lpthread" 88 else 89 wl= 90 ld="${LD}" 91 ldflags="${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}" 92 ldlibs= 93 fi 94 95 ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}" 96 97 # The kallsyms linking does not need debug symbols included. 98 if [ -n "${strip_debug}" ] ; then 99 ldflags="${ldflags} ${wl}--strip-debug" 100 fi 101 102 if is_enabled CONFIG_VMLINUX_MAP; then 103 ldflags="${ldflags} ${wl}-Map=${output}.map" 104 fi 105 106 ${ld} ${ldflags} -o ${output} \ 107 ${wl}--whole-archive ${objs} ${wl}--no-whole-archive \ 108 ${wl}--start-group ${libs} ${wl}--end-group \ 109 ${kallsymso} ${btf_vmlinux_bin_o} ${ldlibs} 110} 111 112# generate .BTF typeinfo from DWARF debuginfo 113# ${1} - vmlinux image 114gen_btf() 115{ 116 local btf_data=${1}.btf.o 117 118 info BTF "${btf_data}" 119 LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1} 120 121 # Create ${btf_data} which contains just .BTF section but no symbols. Add 122 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all 123 # deletes all symbols including __start_BTF and __stop_BTF, which will 124 # be redefined in the linker script. Add 2>/dev/null to suppress GNU 125 # objcopy warnings: "empty loadable segment detected at ..." 126 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \ 127 --strip-all ${1} "${btf_data}" 2>/dev/null 128 # Change e_type to ET_REL so that it can be used to link final vmlinux. 129 # GNU ld 2.35+ and lld do not allow an ET_EXEC input. 130 if is_enabled CONFIG_CPU_BIG_ENDIAN; then 131 et_rel='\0\1' 132 else 133 et_rel='\1\0' 134 fi 135 printf "${et_rel}" | dd of="${btf_data}" conv=notrunc bs=1 seek=16 status=none 136 137 btf_vmlinux_bin_o=${btf_data} 138} 139 140# Create ${2}.o file with all symbols from the ${1} object file 141kallsyms() 142{ 143 local kallsymopt; 144 145 if is_enabled CONFIG_KALLSYMS_ALL; then 146 kallsymopt="${kallsymopt} --all-symbols" 147 fi 148 149 if is_enabled CONFIG_KALLSYMS_ABSOLUTE_PERCPU; then 150 kallsymopt="${kallsymopt} --absolute-percpu" 151 fi 152 153 info KSYMS "${2}.S" 154 scripts/kallsyms ${kallsymopt} "${1}" > "${2}.S" 155 156 info AS "${2}.o" 157 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \ 158 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} -c -o "${2}.o" "${2}.S" 159 160 kallsymso=${2}.o 161} 162 163# Perform kallsyms for the given temporary vmlinux. 164sysmap_and_kallsyms() 165{ 166 mksysmap "${1}" "${1}.syms" 167 kallsyms "${1}.syms" "${1}.kallsyms" 168 169 kallsyms_sysmap=${1}.syms 170} 171 172# Create map file with all symbols from ${1} 173# See mksymap for additional details 174mksysmap() 175{ 176 info NM ${2} 177 ${NM} -n "${1}" | sed -f "${srctree}/scripts/mksysmap" > "${2}" 178} 179 180sorttable() 181{ 182 ${objtree}/scripts/sorttable ${1} 183} 184 185cleanup() 186{ 187 rm -f .btf.* 188 rm -f System.map 189 rm -f vmlinux 190 rm -f vmlinux.map 191} 192 193# Use "make V=1" to debug this script 194case "${KBUILD_VERBOSE}" in 195*1*) 196 set -x 197 ;; 198esac 199 200if [ "$1" = "clean" ]; then 201 cleanup 202 exit 0 203fi 204 205${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init init/version-timestamp.o 206 207btf_vmlinux_bin_o= 208kallsymso= 209strip_debug= 210 211if is_enabled CONFIG_KALLSYMS; then 212 true > .tmp_vmlinux.kallsyms0.syms 213 kallsyms .tmp_vmlinux.kallsyms0.syms .tmp_vmlinux0.kallsyms 214fi 215 216if is_enabled CONFIG_KALLSYMS || is_enabled CONFIG_DEBUG_INFO_BTF; then 217 218 # The kallsyms linking does not need debug symbols, but the BTF does. 219 if ! is_enabled CONFIG_DEBUG_INFO_BTF; then 220 strip_debug=1 221 fi 222 223 vmlinux_link .tmp_vmlinux1 224fi 225 226if is_enabled CONFIG_DEBUG_INFO_BTF; then 227 if ! gen_btf .tmp_vmlinux1; then 228 echo >&2 "Failed to generate BTF for vmlinux" 229 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF" 230 exit 1 231 fi 232fi 233 234if is_enabled CONFIG_KALLSYMS; then 235 236 # kallsyms support 237 # Generate section listing all symbols and add it into vmlinux 238 # It's a four step process: 239 # 0) Generate a dummy __kallsyms with empty symbol list. 240 # 1) Link .tmp_vmlinux.kallsyms1 so it has all symbols and sections, 241 # with a dummy __kallsyms. 242 # Running kallsyms on that gives us .tmp_kallsyms1.o with 243 # the right size 244 # 2) Link .tmp_vmlinux.kallsyms2 so it now has a __kallsyms section of 245 # the right size, but due to the added section, some 246 # addresses have shifted. 247 # From here, we generate a correct .tmp_vmlinux.kallsyms2.o 248 # 3) That link may have expanded the kernel image enough that 249 # more linker branch stubs / trampolines had to be added, which 250 # introduces new names, which further expands kallsyms. Do another 251 # pass if that is the case. In theory it's possible this results 252 # in even more stubs, but unlikely. 253 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around 254 # other bugs. 255 # 4) The correct ${kallsymso} is linked into the final vmlinux. 256 # 257 # a) Verify that the System.map from vmlinux matches the map from 258 # ${kallsymso}. 259 260 # The kallsyms linking does not need debug symbols included. 261 strip_debug=1 262 263 sysmap_and_kallsyms .tmp_vmlinux1 264 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 265 266 vmlinux_link .tmp_vmlinux2 267 sysmap_and_kallsyms .tmp_vmlinux2 268 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 269 270 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then 271 vmlinux_link .tmp_vmlinux3 272 sysmap_and_kallsyms .tmp_vmlinux3 273 fi 274fi 275 276strip_debug= 277 278vmlinux_link vmlinux 279 280# fill in BTF IDs 281if is_enabled CONFIG_DEBUG_INFO_BTF; then 282 info BTFIDS vmlinux 283 ${RESOLVE_BTFIDS} vmlinux 284fi 285 286mksysmap vmlinux System.map 287 288if is_enabled CONFIG_BUILDTIME_TABLE_SORT; then 289 info SORTTAB vmlinux 290 if ! sorttable vmlinux; then 291 echo >&2 Failed to sort kernel tables 292 exit 1 293 fi 294fi 295 296# step a (see comment above) 297if is_enabled CONFIG_KALLSYMS; then 298 if ! cmp -s System.map "${kallsyms_sysmap}"; then 299 echo >&2 Inconsistent kallsyms data 300 echo >&2 'Try "make KALLSYMS_EXTRA_PASS=1" as a workaround' 301 exit 1 302 fi 303fi 304 305# For fixdep 306echo "vmlinux: $0" > .vmlinux.d 307