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}"
50 # ${2}, ${3}, ... - optional extra .o files
62 # skip output file argument
65 if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then
66 # Use vmlinux.o instead of performing the slow LTO link again.
70 objs="${KBUILD_VMLINUX_OBJS}"
71 libs="${KBUILD_VMLINUX_LIBS}"
74 if is_enabled CONFIG_MODULES; then
75 objs="${objs} .vmlinux.export.o"
78 objs="${objs} init/version-timestamp.o"
80 if [ "${SRCARCH}" = "um" ]; then
83 ldflags="${CFLAGS_vmlinux}"
84 ldlibs="-lutil -lrt -lpthread"
88 ldflags="${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}"
92 ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}"
94 # The kallsyms linking does not need debug symbols included.
95 if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
96 ldflags="${ldflags} ${wl}--strip-debug"
99 if is_enabled CONFIG_VMLINUX_MAP; then
100 ldflags="${ldflags} ${wl}-Map=${output}.map"
103 ${ld} ${ldflags} -o ${output} \
104 ${wl}--whole-archive ${objs} ${wl}--no-whole-archive \
105 ${wl}--start-group ${libs} ${wl}--end-group \
109 # generate .BTF typeinfo from DWARF debuginfo
110 # ${1} - vmlinux image
111 # ${2} - file to dump raw BTF data into
116 if ! [ -x "$(command -v ${PAHOLE})" ]; then
117 echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available"
121 pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
122 if [ "${pahole_ver}" -lt "116" ]; then
123 echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.16"
130 LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1}
132 # Create ${2} which contains just .BTF section but no symbols. Add
133 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all
134 # deletes all symbols including __start_BTF and __stop_BTF, which will
135 # be redefined in the linker script. Add 2>/dev/null to suppress GNU
136 # objcopy warnings: "empty loadable segment detected at ..."
137 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \
138 --strip-all ${1} ${2} 2>/dev/null
139 # Change e_type to ET_REL so that it can be used to link final vmlinux.
140 # Unlike GNU ld, lld does not allow an ET_EXEC input.
141 printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none
144 # Create ${2} .S file with all symbols from the ${1} object file
149 if is_enabled CONFIG_KALLSYMS_ALL; then
150 kallsymopt="${kallsymopt} --all-symbols"
153 if is_enabled CONFIG_KALLSYMS_ABSOLUTE_PERCPU; then
154 kallsymopt="${kallsymopt} --absolute-percpu"
157 if is_enabled CONFIG_KALLSYMS_BASE_RELATIVE; then
158 kallsymopt="${kallsymopt} --base-relative"
162 ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${2}
165 # Perform one step in kallsyms generation, including temporary linking of
169 kallsymso_prev=${kallsymso}
170 kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1}
171 kallsymso=${kallsyms_vmlinux}.o
172 kallsyms_S=${kallsyms_vmlinux}.S
174 vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o}
175 kallsyms ${kallsyms_vmlinux} ${kallsyms_S}
177 info AS ${kallsyms_S}
178 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \
179 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \
180 -c -o ${kallsymso} ${kallsyms_S}
183 # Create map file with all symbols from ${1}
184 # See mksymap for additional details
187 ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
192 ${objtree}/scripts/sorttable ${1}
195 # Delete output files in case of error
202 rm -f .vmlinux.export.c
205 # Use "make V=1" to debug this script
206 case "${KBUILD_VERBOSE}" in
212 if [ "$1" = "clean" ]; then
218 ${MAKE} -f "${srctree}/scripts/Makefile.vmlinux_o"
220 # modpost vmlinux.o to check for section mismatches
221 ${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1
223 info MODINFO modules.builtin.modinfo
224 ${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo
225 info GEN modules.builtin
226 # The second line aids cases where multiple modules share the same object.
227 tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' |
228 tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin
230 if is_enabled CONFIG_MODULES; then
231 ${MAKE} -f "${srctree}/scripts/Makefile.vmlinux" .vmlinux.export.o
234 ${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init init/version-timestamp.o
237 if is_enabled CONFIG_DEBUG_INFO_BTF; then
238 btf_vmlinux_bin_o=.btf.vmlinux.bin.o
239 if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then
240 echo >&2 "Failed to generate BTF for vmlinux"
241 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF"
249 if is_enabled CONFIG_KALLSYMS; then
252 # Generate section listing all symbols and add it into vmlinux
253 # It's a three step process:
254 # 1) Link .tmp_vmlinux.kallsyms1 so it has all symbols and sections,
255 # but __kallsyms is empty.
256 # Running kallsyms on that gives us .tmp_kallsyms1.o with
258 # 2) Link .tmp_vmlinux.kallsyms2 so it now has a __kallsyms section of
259 # the right size, but due to the added section, some
260 # addresses have shifted.
261 # From here, we generate a correct .tmp_vmlinux.kallsyms2.o
262 # 3) That link may have expanded the kernel image enough that
263 # more linker branch stubs / trampolines had to be added, which
264 # introduces new names, which further expands kallsyms. Do another
265 # pass if that is the case. In theory it's possible this results
266 # in even more stubs, but unlikely.
267 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
269 # 4) The correct ${kallsymso} is linked into the final vmlinux.
271 # a) Verify that the System.map from vmlinux matches the map from
278 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev})
279 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
281 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
286 vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o}
289 if is_enabled CONFIG_DEBUG_INFO_BTF && is_enabled CONFIG_BPF; then
291 ${RESOLVE_BTFIDS} vmlinux
294 info SYSMAP System.map
295 mksysmap vmlinux System.map
297 if is_enabled CONFIG_BUILDTIME_TABLE_SORT; then
299 if ! sorttable vmlinux; then
300 echo >&2 Failed to sort kernel tables
305 # step a (see comment above)
306 if is_enabled CONFIG_KALLSYMS; then
307 mksysmap ${kallsyms_vmlinux} .tmp_System.map
309 if ! cmp -s System.map .tmp_System.map; then
310 echo >&2 Inconsistent kallsyms data
311 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
317 echo "vmlinux: $0" > .vmlinux.d