1#!/bin/sh
2# SPDX-License-Identifier: GPL-2.0
3#
4# link vmlinux
5#
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.
11#
12# vmlinux
13#   ^
14#   |
15#   +--< $(KBUILD_VMLINUX_OBJS)
16#   |    +--< init/built-in.a drivers/built-in.a mm/built-in.a + more
17#   |
18#   +--< $(KBUILD_VMLINUX_LIBS)
19#   |    +--< lib/lib.a + more
20#   |
21#   +-< ${kallsymso} (see description in KALLSYMS section)
22#
23# vmlinux version (uname -v) cannot be updated during normal
24# descending-into-subdirs phase since we do not yet know if we need to
25# update vmlinux.
26# Therefore this step is delayed until just before final link of vmlinux.
27#
28# System.map is generated to document addresses of all kernel symbols
29
30# Error out on error
31set -e
32
33# Nice output in kbuild format
34# Will be supressed by "make -s"
35info()
36{
37	if [ "${quiet}" != "silent_" ]; then
38		printf "  %-7s %s\n" "${1}" "${2}"
39	fi
40}
41
42# Link of vmlinux.o used for section mismatch analysis
43# ${1} output file
44modpost_link()
45{
46	local objects
47
48	objects="--whole-archive				\
49		${KBUILD_VMLINUX_OBJS}				\
50		--no-whole-archive				\
51		--start-group					\
52		${KBUILD_VMLINUX_LIBS}				\
53		--end-group"
54
55	${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${objects}
56}
57
58# Link of vmlinux
59# ${1} - output file
60# ${2}, ${3}, ... - optional extra .o files
61vmlinux_link()
62{
63	local lds="${objtree}/${KBUILD_LDS}"
64	local output=${1}
65	local objects
66
67	info LD ${output}
68
69	# skip output file argument
70	shift
71
72	if [ "${SRCARCH}" != "um" ]; then
73		objects="--whole-archive			\
74			${KBUILD_VMLINUX_OBJS}			\
75			--no-whole-archive			\
76			--start-group				\
77			${KBUILD_VMLINUX_LIBS}			\
78			--end-group				\
79			${@}"
80
81		${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}	\
82			-o ${output}				\
83			-T ${lds} ${objects}
84	else
85		objects="-Wl,--whole-archive			\
86			${KBUILD_VMLINUX_OBJS}			\
87			-Wl,--no-whole-archive			\
88			-Wl,--start-group			\
89			${KBUILD_VMLINUX_LIBS}			\
90			-Wl,--end-group				\
91			${@}"
92
93		${CC} ${CFLAGS_vmlinux}				\
94			-o ${output}				\
95			-Wl,-T,${lds}				\
96			${objects}				\
97			-lutil -lrt -lpthread
98		rm -f linux
99	fi
100}
101
102# generate .BTF typeinfo from DWARF debuginfo
103# ${1} - vmlinux image
104# ${2} - file to dump raw BTF data into
105gen_btf()
106{
107	local pahole_ver
108	local bin_arch
109
110	if ! [ -x "$(command -v ${PAHOLE})" ]; then
111		info "BTF" "${1}: pahole (${PAHOLE}) is not available"
112		return 1
113	fi
114
115	pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
116	if [ "${pahole_ver}" -lt "113" ]; then
117		info "BTF" "${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.13"
118		return 1
119	fi
120
121	info "BTF" ${2}
122	vmlinux_link ${1}
123	LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1}
124
125	# dump .BTF section into raw binary file to link with final vmlinux
126	bin_arch=$(LANG=C ${OBJDUMP} -f ${1} | grep architecture | \
127		cut -d, -f1 | cut -d' ' -f2)
128	bin_format=$(LANG=C ${OBJDUMP} -f ${1} | grep 'file format' | \
129		awk '{print $4}')
130	${OBJCOPY} --dump-section .BTF=.btf.vmlinux.bin ${1} 2>/dev/null
131	${OBJCOPY} -I binary -O ${bin_format} -B ${bin_arch} \
132		--rename-section .data=.BTF .btf.vmlinux.bin ${2}
133}
134
135# Create ${2} .o file with all symbols from the ${1} object file
136kallsyms()
137{
138	info KSYM ${2}
139	local kallsymopt;
140
141	if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
142		kallsymopt="${kallsymopt} --all-symbols"
143	fi
144
145	if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
146		kallsymopt="${kallsymopt} --absolute-percpu"
147	fi
148
149	if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then
150		kallsymopt="${kallsymopt} --base-relative"
151	fi
152
153	local aflags="${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL}               \
154		      ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS}"
155
156	local afile="`basename ${2} .o`.S"
157
158	${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${afile}
159	${CC} ${aflags} -c -o ${2} ${afile}
160}
161
162# Perform one step in kallsyms generation, including temporary linking of
163# vmlinux.
164kallsyms_step()
165{
166	kallsymso_prev=${kallsymso}
167	kallsymso=.tmp_kallsyms${1}.o
168	kallsyms_vmlinux=.tmp_vmlinux${1}
169
170	vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o}
171	kallsyms ${kallsyms_vmlinux} ${kallsymso}
172}
173
174# Create map file with all symbols from ${1}
175# See mksymap for additional details
176mksysmap()
177{
178	${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
179}
180
181sortextable()
182{
183	${objtree}/scripts/sortextable ${1}
184}
185
186# Delete output files in case of error
187cleanup()
188{
189	rm -f .btf.*
190	rm -f .tmp_System.map
191	rm -f .tmp_kallsyms*
192	rm -f .tmp_vmlinux*
193	rm -f System.map
194	rm -f vmlinux
195	rm -f vmlinux.o
196}
197
198on_exit()
199{
200	if [ $? -ne 0 ]; then
201		cleanup
202	fi
203}
204trap on_exit EXIT
205
206on_signals()
207{
208	exit 1
209}
210trap on_signals HUP INT QUIT TERM
211
212#
213#
214# Use "make V=1" to debug this script
215case "${KBUILD_VERBOSE}" in
216*1*)
217	set -x
218	;;
219esac
220
221if [ "$1" = "clean" ]; then
222	cleanup
223	exit 0
224fi
225
226# We need access to CONFIG_ symbols
227. include/config/auto.conf
228
229# Update version
230info GEN .version
231if [ -r .version ]; then
232	VERSION=$(expr 0$(cat .version) + 1)
233	echo $VERSION > .version
234else
235	rm -f .version
236	echo 1 > .version
237fi;
238
239# final build of init/
240${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init
241
242#link vmlinux.o
243info LD vmlinux.o
244modpost_link vmlinux.o
245
246# modpost vmlinux.o to check for section mismatches
247${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1
248
249info MODINFO modules.builtin.modinfo
250${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo
251
252btf_vmlinux_bin_o=""
253if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then
254	if gen_btf .tmp_vmlinux.btf .btf.vmlinux.bin.o ; then
255		btf_vmlinux_bin_o=.btf.vmlinux.bin.o
256	fi
257fi
258
259kallsymso=""
260kallsymso_prev=""
261kallsyms_vmlinux=""
262if [ -n "${CONFIG_KALLSYMS}" ]; then
263
264	# kallsyms support
265	# Generate section listing all symbols and add it into vmlinux
266	# It's a three step process:
267	# 1)  Link .tmp_vmlinux1 so it has all symbols and sections,
268	#     but __kallsyms is empty.
269	#     Running kallsyms on that gives us .tmp_kallsyms1.o with
270	#     the right size
271	# 2)  Link .tmp_vmlinux2 so it now has a __kallsyms section of
272	#     the right size, but due to the added section, some
273	#     addresses have shifted.
274	#     From here, we generate a correct .tmp_kallsyms2.o
275	# 3)  That link may have expanded the kernel image enough that
276	#     more linker branch stubs / trampolines had to be added, which
277	#     introduces new names, which further expands kallsyms. Do another
278	#     pass if that is the case. In theory it's possible this results
279	#     in even more stubs, but unlikely.
280	#     KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
281	#     other bugs.
282	# 4)  The correct ${kallsymso} is linked into the final vmlinux.
283	#
284	# a)  Verify that the System.map from vmlinux matches the map from
285	#     ${kallsymso}.
286
287	kallsyms_step 1
288	kallsyms_step 2
289
290	# step 3
291	size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev})
292	size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
293
294	if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
295		kallsyms_step 3
296	fi
297fi
298
299vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o}
300
301if [ -n "${CONFIG_BUILDTIME_EXTABLE_SORT}" ]; then
302	info SORTEX vmlinux
303	sortextable vmlinux
304fi
305
306info SYSMAP System.map
307mksysmap vmlinux System.map
308
309# step a (see comment above)
310if [ -n "${CONFIG_KALLSYMS}" ]; then
311	mksysmap ${kallsyms_vmlinux} .tmp_System.map
312
313	if ! cmp -s System.map .tmp_System.map; then
314		echo >&2 Inconsistent kallsyms data
315		echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
316		exit 1
317	fi
318fi
319