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 # +-< ${kallsymso} (see description in KALLSYMS section)
23 # vmlinux version (uname -v) cannot be updated during normal
24 # descending-into-subdirs phase since we do not yet know if we need to
26 # Therefore this step is delayed until just before final link of vmlinux.
28 # System.map is generated to document addresses of all kernel symbols
37 # Nice output in kbuild format
38 # Will be supressed by "make -s"
41 printf " %-7s %s\n" "${1}" "${2}"
44 # Generate a linker script to ensure correct ordering of initcalls.
47 info GEN .tmp_initcalls.lds
49 ${PYTHON} ${srctree}/scripts/jobserver-exec \
50 ${PERL} ${srctree}/scripts/generate_initcall_order.pl \
51 ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS} \
55 # If CONFIG_LTO_CLANG is selected, collect generated symbol versions into
56 # .tmp_symversions.lds
59 info GEN .tmp_symversions.lds
60 rm -f .tmp_symversions.lds
62 for o in ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS}; do
63 if [ -f ${o}.symversions ]; then
64 cat ${o}.symversions >> .tmp_symversions.lds
69 # Link of vmlinux.o used for section mismatch analysis
76 objects="--whole-archive \
77 ${KBUILD_VMLINUX_OBJS} \
80 ${KBUILD_VMLINUX_LIBS} \
83 if [ -n "${CONFIG_LTO_CLANG}" ]; then
85 lds="-T .tmp_initcalls.lds"
87 if [ -n "${CONFIG_MODVERSIONS}" ]; then
89 lds="${lds} -T .tmp_symversions.lds"
92 # This might take a while, so indicate that we're doing
99 ${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${lds} ${objects}
107 if [ "${CONFIG_LTO_CLANG} ${CONFIG_STACK_VALIDATION}" = "y y" ]; then
108 # Don't perform vmlinux validation unless explicitly requested,
109 # but run objtool on vmlinux.o now that we have an object file.
110 if [ -n "${CONFIG_UNWINDER_ORC}" ]; then
111 objtoolcmd="orc generate"
114 objtoolopt="${objtoolopt} --duplicate"
116 if [ -n "${CONFIG_FTRACE_MCOUNT_USE_OBJTOOL}" ]; then
117 objtoolopt="${objtoolopt} --mcount"
121 if [ -n "${CONFIG_VMLINUX_VALIDATION}" ]; then
122 objtoolopt="${objtoolopt} --noinstr"
123 if is_enabled CONFIG_CPU_UNRET_ENTRY; then
124 objtoolopt="${objtoolopt} --unret"
128 if [ -n "${objtoolopt}" ]; then
129 if [ -z "${objtoolcmd}" ]; then
132 objtoolopt="${objtoolopt} --vmlinux"
133 if [ -z "${CONFIG_FRAME_POINTER}" ]; then
134 objtoolopt="${objtoolopt} --no-fp"
136 if [ -n "${CONFIG_GCOV_KERNEL}" ] || [ -n "${CONFIG_LTO_CLANG}" ]; then
137 objtoolopt="${objtoolopt} --no-unreachable"
139 if [ -n "${CONFIG_RETPOLINE}" ]; then
140 objtoolopt="${objtoolopt} --retpoline"
142 if [ -n "${CONFIG_X86_SMAP}" ]; then
143 objtoolopt="${objtoolopt} --uaccess"
145 if [ -n "${CONFIG_SLS}" ]; then
146 objtoolopt="${objtoolopt} --sls"
149 tools/objtool/objtool ${objtoolcmd} ${objtoolopt} ${1}
155 # ${2}, ${3}, ... - optional extra .o files
167 # skip output file argument
170 if [ -n "${CONFIG_LTO_CLANG}" ]; then
171 # Use vmlinux.o instead of performing the slow LTO link again.
175 objs="${KBUILD_VMLINUX_OBJS}"
176 libs="${KBUILD_VMLINUX_LIBS}"
179 if [ "${SRCARCH}" = "um" ]; then
182 ldflags="${CFLAGS_vmlinux}"
183 ldlibs="-lutil -lrt -lpthread"
187 ldflags="${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}"
191 ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}"
193 # The kallsyms linking does not need debug symbols included.
194 if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
195 ldflags="${ldflags} ${wl}--strip-debug"
198 if [ -n "${CONFIG_VMLINUX_MAP}" ]; then
199 ldflags="${ldflags} ${wl}-Map=${output}.map"
202 ${ld} ${ldflags} -o ${output} \
203 ${wl}--whole-archive ${objs} ${wl}--no-whole-archive \
204 ${wl}--start-group ${libs} ${wl}--end-group \
208 # generate .BTF typeinfo from DWARF debuginfo
209 # ${1} - vmlinux image
210 # ${2} - file to dump raw BTF data into
214 local extra_paholeopt=
216 if ! [ -x "$(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"
229 if [ "${pahole_ver}" -ge "118" ] && [ "${pahole_ver}" -le "121" ]; then
230 # pahole 1.18 through 1.21 can't handle zero-sized per-CPU vars
231 extra_paholeopt="${extra_paholeopt} --skip_encoding_btf_vars"
233 if [ "${pahole_ver}" -ge "121" ]; then
234 extra_paholeopt="${extra_paholeopt} --btf_gen_floats"
238 LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${extra_paholeopt} ${1}
240 # Create ${2} which contains just .BTF section but no symbols. Add
241 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all
242 # deletes all symbols including __start_BTF and __stop_BTF, which will
243 # be redefined in the linker script. Add 2>/dev/null to suppress GNU
244 # objcopy warnings: "empty loadable segment detected at ..."
245 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \
246 --strip-all ${1} ${2} 2>/dev/null
247 # Change e_type to ET_REL so that it can be used to link final vmlinux.
248 # Unlike GNU ld, lld does not allow an ET_EXEC input.
249 printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none
252 # Create ${2} .S file with all symbols from the ${1} object file
257 if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
258 kallsymopt="${kallsymopt} --all-symbols"
261 if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
262 kallsymopt="${kallsymopt} --absolute-percpu"
265 if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then
266 kallsymopt="${kallsymopt} --base-relative"
270 ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${2}
273 # Perform one step in kallsyms generation, including temporary linking of
277 kallsymso_prev=${kallsymso}
278 kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1}
279 kallsymso=${kallsyms_vmlinux}.o
280 kallsyms_S=${kallsyms_vmlinux}.S
282 vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o}
283 kallsyms ${kallsyms_vmlinux} ${kallsyms_S}
285 info AS ${kallsyms_S}
286 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \
287 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \
288 -c -o ${kallsymso} ${kallsyms_S}
291 # Create map file with all symbols from ${1}
292 # See mksymap for additional details
295 ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
300 ${objtree}/scripts/sorttable ${1}
303 # Delete output files in case of error
307 rm -f .tmp_System.map
308 rm -f .tmp_initcalls.lds
309 rm -f .tmp_symversions.lds
318 # Use "make V=1" to debug this script
319 case "${KBUILD_VERBOSE}" in
325 if [ "$1" = "clean" ]; then
330 # We need access to CONFIG_ symbols
331 . include/config/auto.conf
335 if [ -r .version ]; then
336 VERSION=$(expr 0$(cat .version) + 1)
337 echo $VERSION > .version
343 # final build of init/
344 ${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1
347 modpost_link vmlinux.o
348 objtool_link vmlinux.o
350 # modpost vmlinux.o to check for section mismatches
351 ${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1
353 info MODINFO modules.builtin.modinfo
354 ${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo
355 info GEN modules.builtin
356 # The second line aids cases where multiple modules share the same object.
357 tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' |
358 tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin
361 if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then
362 btf_vmlinux_bin_o=.btf.vmlinux.bin.o
363 if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then
364 echo >&2 "Failed to generate BTF for vmlinux"
365 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF"
373 if [ -n "${CONFIG_KALLSYMS}" ]; then
376 # Generate section listing all symbols and add it into vmlinux
377 # It's a three step process:
378 # 1) Link .tmp_vmlinux1 so it has all symbols and sections,
379 # but __kallsyms is empty.
380 # Running kallsyms on that gives us .tmp_kallsyms1.o with
382 # 2) Link .tmp_vmlinux2 so it now has a __kallsyms section of
383 # the right size, but due to the added section, some
384 # addresses have shifted.
385 # From here, we generate a correct .tmp_kallsyms2.o
386 # 3) That link may have expanded the kernel image enough that
387 # more linker branch stubs / trampolines had to be added, which
388 # introduces new names, which further expands kallsyms. Do another
389 # pass if that is the case. In theory it's possible this results
390 # in even more stubs, but unlikely.
391 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
393 # 4) The correct ${kallsymso} is linked into the final vmlinux.
395 # a) Verify that the System.map from vmlinux matches the map from
402 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev})
403 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
405 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
410 vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o}
413 if [ -n "${CONFIG_DEBUG_INFO_BTF}" -a -n "${CONFIG_BPF}" ]; then
415 ${RESOLVE_BTFIDS} vmlinux
418 if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then
420 if ! sorttable vmlinux; then
421 echo >&2 Failed to sort kernel tables
426 info SYSMAP System.map
427 mksysmap vmlinux System.map
429 # step a (see comment above)
430 if [ -n "${CONFIG_KALLSYMS}" ]; then
431 mksysmap ${kallsyms_vmlinux} .tmp_System.map
433 if ! cmp -s System.map .tmp_System.map; then
434 echo >&2 Inconsistent kallsyms data
435 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
441 echo "vmlinux: $0" > .vmlinux.d