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
38 grep -q "^$1=y" include/config/auto.conf
41 # Nice output in kbuild format
42 # Will be supressed by "make -s"
45 printf " %-7s %s\n" "${1}" "${2}"
48 # Generate a linker script to ensure correct ordering of initcalls.
51 info GEN .tmp_initcalls.lds
53 ${PYTHON} ${srctree}/scripts/jobserver-exec \
54 ${PERL} ${srctree}/scripts/generate_initcall_order.pl \
55 ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS} \
59 # If CONFIG_LTO_CLANG is selected, collect generated symbol versions into
60 # .tmp_symversions.lds
63 info GEN .tmp_symversions.lds
64 rm -f .tmp_symversions.lds
66 for o in ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS}; do
67 if [ -f ${o}.symversions ]; then
68 cat ${o}.symversions >> .tmp_symversions.lds
73 # Link of vmlinux.o used for section mismatch analysis
80 objects="--whole-archive \
81 ${KBUILD_VMLINUX_OBJS} \
84 ${KBUILD_VMLINUX_LIBS} \
87 if is_enabled CONFIG_LTO_CLANG; then
89 lds="-T .tmp_initcalls.lds"
91 if is_enabled CONFIG_MODVERSIONS; then
93 lds="${lds} -T .tmp_symversions.lds"
96 # This might take a while, so indicate that we're doing
103 ${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${lds} ${objects}
111 if is_enabled CONFIG_LTO_CLANG && is_enabled CONFIG_STACK_VALIDATION; then
112 # Don't perform vmlinux validation unless explicitly requested,
113 # but run objtool on vmlinux.o now that we have an object file.
114 if is_enabled CONFIG_UNWINDER_ORC; then
115 objtoolcmd="orc generate"
118 objtoolopt="${objtoolopt} --duplicate"
120 if is_enabled CONFIG_FTRACE_MCOUNT_USE_OBJTOOL; then
121 objtoolopt="${objtoolopt} --mcount"
125 if is_enabled CONFIG_VMLINUX_VALIDATION; then
126 objtoolopt="${objtoolopt} --noinstr"
129 if [ -n "${objtoolopt}" ]; then
130 if [ -z "${objtoolcmd}" ]; then
133 objtoolopt="${objtoolopt} --vmlinux"
134 if ! is_enabled CONFIG_FRAME_POINTER; then
135 objtoolopt="${objtoolopt} --no-fp"
137 if is_enabled CONFIG_GCOV_KERNEL || is_enabled CONFIG_LTO_CLANG; then
138 objtoolopt="${objtoolopt} --no-unreachable"
140 if is_enabled CONFIG_RETPOLINE; then
141 objtoolopt="${objtoolopt} --retpoline"
143 if is_enabled CONFIG_X86_SMAP; then
144 objtoolopt="${objtoolopt} --uaccess"
146 if is_enabled CONFIG_SLS; then
147 objtoolopt="${objtoolopt} --sls"
150 tools/objtool/objtool ${objtoolcmd} ${objtoolopt} ${1}
156 # ${2}, ${3}, ... - optional extra .o files
168 # skip output file argument
171 if is_enabled CONFIG_LTO_CLANG; then
172 # Use vmlinux.o instead of performing the slow LTO link again.
176 objs="${KBUILD_VMLINUX_OBJS}"
177 libs="${KBUILD_VMLINUX_LIBS}"
180 if [ "${SRCARCH}" = "um" ]; then
183 ldflags="${CFLAGS_vmlinux}"
184 ldlibs="-lutil -lrt -lpthread"
188 ldflags="${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}"
192 ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}"
194 # The kallsyms linking does not need debug symbols included.
195 if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
196 ldflags="${ldflags} ${wl}--strip-debug"
199 if is_enabled CONFIG_VMLINUX_MAP; then
200 ldflags="${ldflags} ${wl}-Map=${output}.map"
203 ${ld} ${ldflags} -o ${output} \
204 ${wl}--whole-archive ${objs} ${wl}--no-whole-archive \
205 ${wl}--start-group ${libs} ${wl}--end-group \
209 # generate .BTF typeinfo from DWARF debuginfo
210 # ${1} - vmlinux image
211 # ${2} - file to dump raw BTF data into
216 if ! [ -x "$(command -v ${PAHOLE})" ]; then
217 echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available"
221 pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
222 if [ "${pahole_ver}" -lt "116" ]; then
223 echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.16"
230 LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1}
232 # Create ${2} which contains just .BTF section but no symbols. Add
233 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all
234 # deletes all symbols including __start_BTF and __stop_BTF, which will
235 # be redefined in the linker script. Add 2>/dev/null to suppress GNU
236 # objcopy warnings: "empty loadable segment detected at ..."
237 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \
238 --strip-all ${1} ${2} 2>/dev/null
239 # Change e_type to ET_REL so that it can be used to link final vmlinux.
240 # Unlike GNU ld, lld does not allow an ET_EXEC input.
241 printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none
244 # Create ${2} .S file with all symbols from the ${1} object file
249 if is_enabled CONFIG_KALLSYMS_ALL; then
250 kallsymopt="${kallsymopt} --all-symbols"
253 if is_enabled CONFIG_KALLSYMS_ABSOLUTE_PERCPU; then
254 kallsymopt="${kallsymopt} --absolute-percpu"
257 if is_enabled CONFIG_KALLSYMS_BASE_RELATIVE; then
258 kallsymopt="${kallsymopt} --base-relative"
262 ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${2}
265 # Perform one step in kallsyms generation, including temporary linking of
269 kallsymso_prev=${kallsymso}
270 kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1}
271 kallsymso=${kallsyms_vmlinux}.o
272 kallsyms_S=${kallsyms_vmlinux}.S
274 vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o}
275 kallsyms ${kallsyms_vmlinux} ${kallsyms_S}
277 info AS ${kallsyms_S}
278 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \
279 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \
280 -c -o ${kallsymso} ${kallsyms_S}
283 # Create map file with all symbols from ${1}
284 # See mksymap for additional details
287 ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
292 ${objtree}/scripts/sorttable ${1}
295 # Delete output files in case of error
299 rm -f .tmp_System.map
300 rm -f .tmp_initcalls.lds
301 rm -f .tmp_symversions.lds
310 # Use "make V=1" to debug this script
311 case "${KBUILD_VERBOSE}" in
317 if [ "$1" = "clean" ]; then
324 if [ -r .version ]; then
325 VERSION=$(expr 0$(cat .version) + 1)
326 echo $VERSION > .version
332 # final build of init/
333 ${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1
336 modpost_link vmlinux.o
337 objtool_link vmlinux.o
339 # modpost vmlinux.o to check for section mismatches
340 ${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1
342 info MODINFO modules.builtin.modinfo
343 ${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo
344 info GEN modules.builtin
345 # The second line aids cases where multiple modules share the same object.
346 tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' |
347 tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin
350 if is_enabled CONFIG_DEBUG_INFO_BTF; then
351 btf_vmlinux_bin_o=.btf.vmlinux.bin.o
352 if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then
353 echo >&2 "Failed to generate BTF for vmlinux"
354 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF"
362 if is_enabled CONFIG_KALLSYMS; then
365 # Generate section listing all symbols and add it into vmlinux
366 # It's a three step process:
367 # 1) Link .tmp_vmlinux.kallsyms1 so it has all symbols and sections,
368 # but __kallsyms is empty.
369 # Running kallsyms on that gives us .tmp_kallsyms1.o with
371 # 2) Link .tmp_vmlinux.kallsyms2 so it now has a __kallsyms section of
372 # the right size, but due to the added section, some
373 # addresses have shifted.
374 # From here, we generate a correct .tmp_vmlinux.kallsyms2.o
375 # 3) That link may have expanded the kernel image enough that
376 # more linker branch stubs / trampolines had to be added, which
377 # introduces new names, which further expands kallsyms. Do another
378 # pass if that is the case. In theory it's possible this results
379 # in even more stubs, but unlikely.
380 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
382 # 4) The correct ${kallsymso} is linked into the final vmlinux.
384 # a) Verify that the System.map from vmlinux matches the map from
391 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev})
392 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
394 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
399 vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o}
402 if is_enabled CONFIG_DEBUG_INFO_BTF && is_enabled CONFIG_BPF; then
404 ${RESOLVE_BTFIDS} vmlinux
407 info SYSMAP System.map
408 mksysmap vmlinux System.map
410 if is_enabled CONFIG_BUILDTIME_TABLE_SORT; then
412 if ! sorttable vmlinux; then
413 echo >&2 Failed to sort kernel tables
418 # step a (see comment above)
419 if is_enabled CONFIG_KALLSYMS; then
420 mksysmap ${kallsyms_vmlinux} .tmp_System.map
422 if ! cmp -s System.map .tmp_System.map; then
423 echo >&2 Inconsistent kallsyms data
424 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
430 echo "vmlinux: $0" > .vmlinux.d