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" 34VMLINUX="$4" 35 36is_enabled() { 37 grep -q "^$1=y" include/config/auto.conf 38} 39 40# Nice output in kbuild format 41# Will be suppressed by "make -s" 42info() 43{ 44 printf " %-7s %s\n" "${1}" "${2}" 45} 46 47# Link of vmlinux 48# ${1} - output file 49vmlinux_link() 50{ 51 local output=${1} 52 local objs 53 local libs 54 local ld 55 local ldflags 56 local ldlibs 57 58 info LD ${output} 59 60 # skip output file argument 61 shift 62 63 if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT || 64 is_enabled CONFIG_KLP_BUILD; then 65 # Use vmlinux.o instead of performing the slow LTO link again. 66 objs=vmlinux.o 67 libs= 68 else 69 objs=vmlinux.a 70 libs="${KBUILD_VMLINUX_LIBS}" 71 fi 72 73 if is_enabled CONFIG_GENERIC_BUILTIN_DTB; then 74 objs="${objs} .builtin-dtbs.o" 75 fi 76 77 objs="${objs} .vmlinux.export.o" 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}/${KBUILD_LDS}" 93 94 # The kallsyms linking does not need debug symbols included. 95 if [ -n "${strip_debug}" ] ; then 96 ldflags="${ldflags} ${wl}--strip-debug" 97 fi 98 99 if [ -n "${generate_map}" ]; then 100 ldflags="${ldflags} ${wl}-Map=vmlinux.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 ${kallsymso} ${btf_vmlinux_bin_o} ${arch_vmlinux_o} ${ldlibs} 107} 108 109# Check if kallsymso_prev and kallsymso differ 110# If symbol sizes within ${kallsymso} change, any symbols within vmlinux are 111# likely to shift, invalidating ${kallsymso}. 112# Since file size can remain unchanged even if symbol sizes change, compare the 113# actual symbols instead of relying on file size only. 114kallsymso_changed() 115{ 116 ${NM} -n "${kallsymso_prev}" > "${kallsymso_prev}.sym" 117 ${NM} -n "${kallsymso}" > "${kallsymso}.sym" 118 ! cmp -s "${kallsymso_prev}.sym" "${kallsymso}.sym" 119} 120 121# Create ${2}.o file with all symbols from the ${1} object file 122kallsyms() 123{ 124 local kallsymopt; 125 126 if is_enabled CONFIG_KALLSYMS_ALL; then 127 kallsymopt="${kallsymopt} --all-symbols" 128 fi 129 130 if is_enabled CONFIG_64BIT || is_enabled CONFIG_RELOCATABLE; then 131 kallsymopt="${kallsymopt} --pc-relative" 132 fi 133 134 info KSYMS "${2}.S" 135 scripts/kallsyms ${kallsymopt} "${1}" > "${2}.S" 136 137 info AS "${2}.o" 138 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \ 139 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} -c -o "${2}.o" "${2}.S" 140 141 kallsymso_prev="${kallsymso:-}" 142 kallsymso=${2}.o 143} 144 145# Perform kallsyms for the given temporary vmlinux. 146sysmap_and_kallsyms() 147{ 148 mksysmap "${1}" "${1}.syms" 149 kallsyms "${1}.syms" "${1}.kallsyms" 150 151 kallsyms_sysmap=${1}.syms 152} 153 154# Create map file with all symbols from ${1} 155# See mksymap for additional details 156mksysmap() 157{ 158 info NM ${2} 159 ${NM} -n "${1}" | sed -f "${srctree}/scripts/mksysmap" > "${2}" 160} 161 162sorttable() 163{ 164 ${NM} -S ${1} > .tmp_vmlinux.nm-sort 165 ${objtree}/scripts/sorttable -s .tmp_vmlinux.nm-sort ${1} 166} 167 168cleanup() 169{ 170 rm -f .btf.* 171 rm -f .tmp_vmlinux.nm-sort 172 rm -f System.map 173 rm -f vmlinux 174 rm -f vmlinux.map 175} 176 177# Use "make V=1" to debug this script 178case "${KBUILD_VERBOSE}" in 179*1*) 180 set -x 181 ;; 182esac 183 184if [ "$1" = "clean" ]; then 185 cleanup 186 exit 0 187fi 188 189${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init init/version-timestamp.o 190 191arch_vmlinux_o= 192if is_enabled CONFIG_ARCH_WANTS_PRE_LINK_VMLINUX; then 193 arch_vmlinux_o=arch/${SRCARCH}/tools/vmlinux.arch.o 194fi 195 196btf_vmlinux_bin_o= 197btfids_vmlinux= 198kallsymso= 199strip_debug= 200generate_map= 201 202# Use "make UT=1" to trigger warnings on unused tracepoints 203case "${WARN_ON_UNUSED_TRACEPOINTS}" in 204*1*) 205 ${objtree}/scripts/tracepoint-update vmlinux.o 206 ;; 207esac 208 209if is_enabled CONFIG_KALLSYMS; then 210 true > .tmp_vmlinux0.syms 211 kallsyms .tmp_vmlinux0.syms .tmp_vmlinux0.kallsyms 212fi 213 214if is_enabled CONFIG_KALLSYMS || is_enabled CONFIG_DEBUG_INFO_BTF; then 215 216 # The kallsyms linking does not need debug symbols, but the BTF does. 217 if ! is_enabled CONFIG_DEBUG_INFO_BTF; then 218 strip_debug=1 219 fi 220 221 vmlinux_link .tmp_vmlinux1 222fi 223 224if is_enabled CONFIG_DEBUG_INFO_BTF; then 225 info BTF .tmp_vmlinux1 226 if ! ${CONFIG_SHELL} ${srctree}/scripts/gen-btf.sh .tmp_vmlinux1; then 227 echo >&2 "Failed to generate BTF for vmlinux" 228 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF" 229 exit 1 230 fi 231 btf_vmlinux_bin_o=.tmp_vmlinux1.btf.o 232 btfids_vmlinux=.tmp_vmlinux1.BTF_ids 233fi 234 235if is_enabled CONFIG_KALLSYMS; then 236 237 # kallsyms support 238 # Generate section listing all symbols and add it into vmlinux 239 # It's a four step process: 240 # 0) Generate a dummy __kallsyms with empty symbol list. 241 # 1) Link .tmp_vmlinux1.kallsyms so it has all symbols and sections, 242 # with a dummy __kallsyms. 243 # Running kallsyms on that gives us .tmp_vmlinux1.kallsyms.o with 244 # the right size 245 # 2) Link .tmp_vmlinux2.kallsyms so it now has a __kallsyms section of 246 # the right size, but due to the added section, some 247 # addresses have shifted. 248 # From here, we generate a correct .tmp_vmlinux2.kallsyms.o 249 # 3) That link may have expanded the kernel image enough that 250 # more linker branch stubs / trampolines had to be added, which 251 # introduces new names, which further expands kallsyms. Do another 252 # pass if that is the case. In theory it's possible this results 253 # in even more stubs, but unlikely. 254 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around 255 # other bugs. 256 # 4) The correct ${kallsymso} is linked into the final vmlinux. 257 # 258 # a) Verify that the System.map from vmlinux matches the map from 259 # ${kallsymso}. 260 261 # The kallsyms linking does not need debug symbols included. 262 strip_debug=1 263 264 sysmap_and_kallsyms .tmp_vmlinux1 265 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 266 267 vmlinux_link .tmp_vmlinux2 268 sysmap_and_kallsyms .tmp_vmlinux2 269 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso}) 270 271 # Due to alignment, file size of the kallsymso object file might remain 272 # unchanged even if individual symbols within change size. Changed 273 # symbol sizes can still shift other symbols, though. Therefore, don't 274 # rely on file size alone. 275 if [ $size1 -ne $size2 ] || kallsymso_changed || \ 276 [ -n "${KALLSYMS_EXTRA_PASS}" ]; then 277 vmlinux_link .tmp_vmlinux3 278 sysmap_and_kallsyms .tmp_vmlinux3 279 fi 280fi 281 282strip_debug= 283 284if is_enabled CONFIG_VMLINUX_MAP; then 285 generate_map=1 286fi 287 288vmlinux_link "${VMLINUX}" 289 290if is_enabled CONFIG_DEBUG_INFO_BTF; then 291 info BTFIDS ${VMLINUX} 292 ${RESOLVE_BTFIDS} --patch_btfids ${btfids_vmlinux} ${VMLINUX} 293fi 294 295mksysmap "${VMLINUX}" System.map 296 297if is_enabled CONFIG_BUILDTIME_TABLE_SORT; then 298 info SORTTAB "${VMLINUX}" 299 if ! sorttable "${VMLINUX}"; then 300 echo >&2 Failed to sort kernel tables 301 exit 1 302 fi 303fi 304 305# step a (see comment above) 306if is_enabled CONFIG_KALLSYMS; then 307 if ! cmp -s System.map "${kallsyms_sysmap}"; then 308 echo >&2 Inconsistent kallsyms data 309 echo >&2 'Try "make KALLSYMS_EXTRA_PASS=1" as a workaround' 310 exit 1 311 fi 312fi 313 314# For fixdep 315echo "${VMLINUX}: $0" > ".${VMLINUX}.d" 316