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 ${PYTHON3} ${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} ${objects}
111 if ! is_enabled CONFIG_OBJTOOL; then
115 if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then
117 # Don't perform vmlinux validation unless explicitly requested,
118 # but run objtool on vmlinux.o now that we have an object file.
120 if is_enabled CONFIG_X86_KERNEL_IBT; then
121 objtoolopt="${objtoolopt} --ibt"
124 if is_enabled CONFIG_FTRACE_MCOUNT_USE_OBJTOOL; then
125 objtoolopt="${objtoolopt} --mcount"
128 if is_enabled CONFIG_UNWINDER_ORC; then
129 objtoolopt="${objtoolopt} --orc"
132 if is_enabled CONFIG_RETPOLINE; then
133 objtoolopt="${objtoolopt} --retpoline"
136 if is_enabled CONFIG_SLS; then
137 objtoolopt="${objtoolopt} --sls"
140 if is_enabled CONFIG_STACK_VALIDATION; then
141 objtoolopt="${objtoolopt} --stackval"
144 if is_enabled CONFIG_X86_SMAP; then
145 objtoolopt="${objtoolopt} --uaccess"
149 objtoolopt="${objtoolopt} --lto"
152 if is_enabled CONFIG_VMLINUX_VALIDATION; then
153 objtoolopt="${objtoolopt} --noinstr"
156 if [ -n "${objtoolopt}" ]; then
158 if ! is_enabled CONFIG_FRAME_POINTER; then
159 objtoolopt="${objtoolopt} --no-fp"
162 if is_enabled CONFIG_GCOV_KERNEL; then
163 objtoolopt="${objtoolopt} --no-unreachable"
166 objtoolopt="${objtoolopt} --vmlinux"
169 tools/objtool/objtool ${objtoolopt} ${1}
175 # ${2}, ${3}, ... - optional extra .o files
187 # skip output file argument
190 if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then
191 # Use vmlinux.o instead of performing the slow LTO link again.
195 objs="${KBUILD_VMLINUX_OBJS}"
196 libs="${KBUILD_VMLINUX_LIBS}"
199 if [ "${SRCARCH}" = "um" ]; then
202 ldflags="${CFLAGS_vmlinux}"
203 ldlibs="-lutil -lrt -lpthread"
207 ldflags="${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}"
211 ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}"
213 # The kallsyms linking does not need debug symbols included.
214 if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
215 ldflags="${ldflags} ${wl}--strip-debug"
218 if is_enabled CONFIG_VMLINUX_MAP; then
219 ldflags="${ldflags} ${wl}-Map=${output}.map"
222 ${ld} ${ldflags} -o ${output} \
223 ${wl}--whole-archive ${objs} ${wl}--no-whole-archive \
224 ${wl}--start-group ${libs} ${wl}--end-group \
228 # generate .BTF typeinfo from DWARF debuginfo
229 # ${1} - vmlinux image
230 # ${2} - file to dump raw BTF data into
235 if ! [ -x "$(command -v ${PAHOLE})" ]; then
236 echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available"
240 pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
241 if [ "${pahole_ver}" -lt "116" ]; then
242 echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.16"
249 LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1}
251 # Create ${2} which contains just .BTF section but no symbols. Add
252 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all
253 # deletes all symbols including __start_BTF and __stop_BTF, which will
254 # be redefined in the linker script. Add 2>/dev/null to suppress GNU
255 # objcopy warnings: "empty loadable segment detected at ..."
256 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \
257 --strip-all ${1} ${2} 2>/dev/null
258 # Change e_type to ET_REL so that it can be used to link final vmlinux.
259 # Unlike GNU ld, lld does not allow an ET_EXEC input.
260 printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none
263 # Create ${2} .S file with all symbols from the ${1} object file
268 if is_enabled CONFIG_KALLSYMS_ALL; then
269 kallsymopt="${kallsymopt} --all-symbols"
272 if is_enabled CONFIG_KALLSYMS_ABSOLUTE_PERCPU; then
273 kallsymopt="${kallsymopt} --absolute-percpu"
276 if is_enabled CONFIG_KALLSYMS_BASE_RELATIVE; then
277 kallsymopt="${kallsymopt} --base-relative"
281 ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${2}
284 # Perform one step in kallsyms generation, including temporary linking of
288 kallsymso_prev=${kallsymso}
289 kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1}
290 kallsymso=${kallsyms_vmlinux}.o
291 kallsyms_S=${kallsyms_vmlinux}.S
293 vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o}
294 kallsyms ${kallsyms_vmlinux} ${kallsyms_S}
296 info AS ${kallsyms_S}
297 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \
298 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \
299 -c -o ${kallsymso} ${kallsyms_S}
302 # Create map file with all symbols from ${1}
303 # See mksymap for additional details
306 ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
311 ${objtree}/scripts/sorttable ${1}
314 # Delete output files in case of error
318 rm -f .tmp_System.map
319 rm -f .tmp_initcalls.lds
320 rm -f .tmp_symversions.lds
329 # Use "make V=1" to debug this script
330 case "${KBUILD_VERBOSE}" in
336 if [ "$1" = "clean" ]; then
343 if [ -r .version ]; then
344 VERSION=$(expr 0$(cat .version) + 1)
345 echo $VERSION > .version
351 # final build of init/
352 ${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1
355 modpost_link vmlinux.o
356 objtool_link vmlinux.o
358 # modpost vmlinux.o to check for section mismatches
359 ${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1
361 info MODINFO modules.builtin.modinfo
362 ${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo
363 info GEN modules.builtin
364 # The second line aids cases where multiple modules share the same object.
365 tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' |
366 tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin
369 if is_enabled CONFIG_DEBUG_INFO_BTF; then
370 btf_vmlinux_bin_o=.btf.vmlinux.bin.o
371 if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then
372 echo >&2 "Failed to generate BTF for vmlinux"
373 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF"
381 if is_enabled CONFIG_KALLSYMS; then
384 # Generate section listing all symbols and add it into vmlinux
385 # It's a three step process:
386 # 1) Link .tmp_vmlinux.kallsyms1 so it has all symbols and sections,
387 # but __kallsyms is empty.
388 # Running kallsyms on that gives us .tmp_kallsyms1.o with
390 # 2) Link .tmp_vmlinux.kallsyms2 so it now has a __kallsyms section of
391 # the right size, but due to the added section, some
392 # addresses have shifted.
393 # From here, we generate a correct .tmp_vmlinux.kallsyms2.o
394 # 3) That link may have expanded the kernel image enough that
395 # more linker branch stubs / trampolines had to be added, which
396 # introduces new names, which further expands kallsyms. Do another
397 # pass if that is the case. In theory it's possible this results
398 # in even more stubs, but unlikely.
399 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
401 # 4) The correct ${kallsymso} is linked into the final vmlinux.
403 # a) Verify that the System.map from vmlinux matches the map from
410 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev})
411 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
413 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
418 vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o}
421 if is_enabled CONFIG_DEBUG_INFO_BTF && is_enabled CONFIG_BPF; then
423 ${RESOLVE_BTFIDS} vmlinux
426 info SYSMAP System.map
427 mksysmap vmlinux System.map
429 if is_enabled CONFIG_BUILDTIME_TABLE_SORT; then
431 if ! sorttable vmlinux; then
432 echo >&2 Failed to sort kernel tables
437 # step a (see comment above)
438 if is_enabled CONFIG_KALLSYMS; then
439 mksysmap ${kallsyms_vmlinux} .tmp_System.map
441 if ! cmp -s System.map .tmp_System.map; then
442 echo >&2 Inconsistent kallsyms data
443 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
449 echo "vmlinux: $0" > .vmlinux.d