2 # SPDX-License-Identifier: GPL-2.0
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.
15 # +--< $(KBUILD_VMLINUX_OBJS)
16 # | +--< init/built-in.a drivers/built-in.a mm/built-in.a + more
18 # +--< $(KBUILD_VMLINUX_LIBS)
19 # | +--< lib/lib.a + more
21 # +-< ${kallsymso} (see description in KALLSYMS section)
23 # vmlinux version (uname -v) cannot be updated during normal
24 # descending-into-subdirs phase since we do not yet know if we need to
26 # Therefore this step is delayed until just before final link of vmlinux.
28 # System.map is generated to document addresses of all kernel symbols
37 # Nice output in kbuild format
38 # Will be supressed by "make -s"
41 if [ "${quiet}" != "silent_" ]; then
42 printf " %-7s %s\n" "${1}" "${2}"
46 # Generate a linker script to ensure correct ordering of initcalls.
49 info GEN .tmp_initcalls.lds
51 ${PYTHON} ${srctree}/scripts/jobserver-exec \
52 ${PERL} ${srctree}/scripts/generate_initcall_order.pl \
53 ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS} \
57 # If CONFIG_LTO_CLANG is selected, collect generated symbol versions into
58 # .tmp_symversions.lds
61 info GEN .tmp_symversions.lds
62 rm -f .tmp_symversions.lds
64 for o in ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS}; do
65 if [ -f ${o}.symversions ]; then
66 cat ${o}.symversions >> .tmp_symversions.lds
71 # Link of vmlinux.o used for section mismatch analysis
78 objects="--whole-archive \
79 ${KBUILD_VMLINUX_OBJS} \
82 ${KBUILD_VMLINUX_LIBS} \
85 if [ -n "${CONFIG_LTO_CLANG}" ]; then
87 lds="-T .tmp_initcalls.lds"
89 if [ -n "${CONFIG_MODVERSIONS}" ]; then
91 lds="${lds} -T .tmp_symversions.lds"
94 # This might take a while, so indicate that we're doing
101 ${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${lds} ${objects}
108 if [ -n "${CONFIG_VMLINUX_VALIDATION}" ]; then
110 if [ -z "${CONFIG_FRAME_POINTER}" ]; then
111 objtoolopt="${objtoolopt} --no-fp"
113 if [ -n "${CONFIG_GCOV_KERNEL}" ]; then
114 objtoolopt="${objtoolopt} --no-unreachable"
116 if [ -n "${CONFIG_RETPOLINE}" ]; then
117 objtoolopt="${objtoolopt} --retpoline"
119 if [ -n "${CONFIG_X86_SMAP}" ]; then
120 objtoolopt="${objtoolopt} --uaccess"
123 tools/objtool/objtool ${objtoolopt} ${1}
129 # ${2}, ${3}, ... - optional extra .o files
132 local lds="${objtree}/${KBUILD_LDS}"
139 # skip output file argument
142 # The kallsyms linking does not need debug symbols included.
143 if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
144 strip_debug=-Wl,--strip-debug
147 if [ "${SRCARCH}" != "um" ]; then
148 if [ -n "${CONFIG_LTO_CLANG}" ]; then
149 # Use vmlinux.o instead of performing the slow LTO
151 objects="--whole-archive \
156 objects="--whole-archive \
157 ${KBUILD_VMLINUX_OBJS} \
160 ${KBUILD_VMLINUX_LIBS} \
165 ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} \
166 ${strip_debug#-Wl,} \
170 objects="-Wl,--whole-archive \
171 ${KBUILD_VMLINUX_OBJS} \
172 -Wl,--no-whole-archive \
174 ${KBUILD_VMLINUX_LIBS} \
178 ${CC} ${CFLAGS_vmlinux} \
183 -lutil -lrt -lpthread
188 # generate .BTF typeinfo from DWARF debuginfo
189 # ${1} - vmlinux image
190 # ${2} - file to dump raw BTF data into
195 if ! [ -x "$(command -v ${PAHOLE})" ]; then
196 echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available"
200 pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
201 if [ "${pahole_ver}" -lt "116" ]; then
202 echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.16"
209 LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1}
211 # Create ${2} which contains just .BTF section but no symbols. Add
212 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all
213 # deletes all symbols including __start_BTF and __stop_BTF, which will
214 # be redefined in the linker script. Add 2>/dev/null to suppress GNU
215 # objcopy warnings: "empty loadable segment detected at ..."
216 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \
217 --strip-all ${1} ${2} 2>/dev/null
218 # Change e_type to ET_REL so that it can be used to link final vmlinux.
219 # Unlike GNU ld, lld does not allow an ET_EXEC input.
220 printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none
223 # Create ${2} .S file with all symbols from the ${1} object file
228 if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
229 kallsymopt="${kallsymopt} --all-symbols"
232 if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
233 kallsymopt="${kallsymopt} --absolute-percpu"
236 if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then
237 kallsymopt="${kallsymopt} --base-relative"
241 ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${2}
244 # Perform one step in kallsyms generation, including temporary linking of
248 kallsymso_prev=${kallsymso}
249 kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1}
250 kallsymso=${kallsyms_vmlinux}.o
251 kallsyms_S=${kallsyms_vmlinux}.S
253 vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o}
254 kallsyms ${kallsyms_vmlinux} ${kallsyms_S}
256 info AS ${kallsyms_S}
257 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \
258 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \
259 -c -o ${kallsymso} ${kallsyms_S}
262 # Create map file with all symbols from ${1}
263 # See mksymap for additional details
266 ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
271 ${objtree}/scripts/sorttable ${1}
274 # Delete output files in case of error
278 rm -f .tmp_System.map
279 rm -f .tmp_initcalls.lds
280 rm -f .tmp_symversions.lds
289 if [ $? -ne 0 ]; then
299 trap on_signals HUP INT QUIT TERM
301 # Use "make V=1" to debug this script
302 case "${KBUILD_VERBOSE}" in
308 if [ "$1" = "clean" ]; then
313 # We need access to CONFIG_ symbols
314 . include/config/auto.conf
318 if [ -r .version ]; then
319 VERSION=$(expr 0$(cat .version) + 1)
320 echo $VERSION > .version
326 # final build of init/
327 ${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1
330 modpost_link vmlinux.o
331 objtool_link vmlinux.o
333 # modpost vmlinux.o to check for section mismatches
334 ${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1
336 info MODINFO modules.builtin.modinfo
337 ${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo
338 info GEN modules.builtin
339 # The second line aids cases where multiple modules share the same object.
340 tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' |
341 tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin
344 if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then
345 btf_vmlinux_bin_o=.btf.vmlinux.bin.o
346 if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then
347 echo >&2 "Failed to generate BTF for vmlinux"
348 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF"
356 if [ -n "${CONFIG_KALLSYMS}" ]; then
359 # Generate section listing all symbols and add it into vmlinux
360 # It's a three step process:
361 # 1) Link .tmp_vmlinux1 so it has all symbols and sections,
362 # but __kallsyms is empty.
363 # Running kallsyms on that gives us .tmp_kallsyms1.o with
365 # 2) Link .tmp_vmlinux2 so it now has a __kallsyms section of
366 # the right size, but due to the added section, some
367 # addresses have shifted.
368 # From here, we generate a correct .tmp_kallsyms2.o
369 # 3) That link may have expanded the kernel image enough that
370 # more linker branch stubs / trampolines had to be added, which
371 # introduces new names, which further expands kallsyms. Do another
372 # pass if that is the case. In theory it's possible this results
373 # in even more stubs, but unlikely.
374 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
376 # 4) The correct ${kallsymso} is linked into the final vmlinux.
378 # a) Verify that the System.map from vmlinux matches the map from
385 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev})
386 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
388 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
393 vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o}
396 if [ -n "${CONFIG_DEBUG_INFO_BTF}" -a -n "${CONFIG_BPF}" ]; then
398 ${RESOLVE_BTFIDS} vmlinux
401 if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then
403 if ! sorttable vmlinux; then
404 echo >&2 Failed to sort kernel tables
409 info SYSMAP System.map
410 mksysmap vmlinux System.map
412 # step a (see comment above)
413 if [ -n "${CONFIG_KALLSYMS}" ]; then
414 mksysmap ${kallsyms_vmlinux} .tmp_System.map
416 if ! cmp -s System.map .tmp_System.map; then
417 echo >&2 Inconsistent kallsyms data
418 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround