xref: /openbmc/linux/scripts/link-vmlinux.sh (revision e7253313)
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} --change-section-address .BTF=0 \
131		--set-section-flags .BTF=alloc -O binary \
132		--only-section=.BTF ${1} .btf.vmlinux.bin
133	${OBJCOPY} -I binary -O ${bin_format} -B ${bin_arch} \
134		--rename-section .data=.BTF .btf.vmlinux.bin ${2}
135}
136
137# Create ${2} .o file with all symbols from the ${1} object file
138kallsyms()
139{
140	info KSYM ${2}
141	local kallsymopt;
142
143	if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
144		kallsymopt="${kallsymopt} --all-symbols"
145	fi
146
147	if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
148		kallsymopt="${kallsymopt} --absolute-percpu"
149	fi
150
151	if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then
152		kallsymopt="${kallsymopt} --base-relative"
153	fi
154
155	local aflags="${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL}               \
156		      ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS}"
157
158	local afile="`basename ${2} .o`.S"
159
160	${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${afile}
161	${CC} ${aflags} -c -o ${2} ${afile}
162}
163
164# Perform one step in kallsyms generation, including temporary linking of
165# vmlinux.
166kallsyms_step()
167{
168	kallsymso_prev=${kallsymso}
169	kallsymso=.tmp_kallsyms${1}.o
170	kallsyms_vmlinux=.tmp_vmlinux${1}
171
172	vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o}
173	kallsyms ${kallsyms_vmlinux} ${kallsymso}
174}
175
176# Create map file with all symbols from ${1}
177# See mksymap for additional details
178mksysmap()
179{
180	${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
181}
182
183sortextable()
184{
185	${objtree}/scripts/sortextable ${1}
186}
187
188# Delete output files in case of error
189cleanup()
190{
191	rm -f .btf.*
192	rm -f .tmp_System.map
193	rm -f .tmp_kallsyms*
194	rm -f .tmp_vmlinux*
195	rm -f System.map
196	rm -f vmlinux
197	rm -f vmlinux.o
198}
199
200on_exit()
201{
202	if [ $? -ne 0 ]; then
203		cleanup
204	fi
205}
206trap on_exit EXIT
207
208on_signals()
209{
210	exit 1
211}
212trap on_signals HUP INT QUIT TERM
213
214#
215#
216# Use "make V=1" to debug this script
217case "${KBUILD_VERBOSE}" in
218*1*)
219	set -x
220	;;
221esac
222
223if [ "$1" = "clean" ]; then
224	cleanup
225	exit 0
226fi
227
228# We need access to CONFIG_ symbols
229. include/config/auto.conf
230
231# Update version
232info GEN .version
233if [ -r .version ]; then
234	VERSION=$(expr 0$(cat .version) + 1)
235	echo $VERSION > .version
236else
237	rm -f .version
238	echo 1 > .version
239fi;
240
241# final build of init/
242${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init
243
244#link vmlinux.o
245info LD vmlinux.o
246modpost_link vmlinux.o
247
248# modpost vmlinux.o to check for section mismatches
249${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1
250
251info MODINFO modules.builtin.modinfo
252${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo
253
254btf_vmlinux_bin_o=""
255if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then
256	if gen_btf .tmp_vmlinux.btf .btf.vmlinux.bin.o ; then
257		btf_vmlinux_bin_o=.btf.vmlinux.bin.o
258	else
259		echo >&2 "Failed to generate BTF for vmlinux"
260		echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF"
261		exit 1
262	fi
263fi
264
265kallsymso=""
266kallsymso_prev=""
267kallsyms_vmlinux=""
268if [ -n "${CONFIG_KALLSYMS}" ]; then
269
270	# kallsyms support
271	# Generate section listing all symbols and add it into vmlinux
272	# It's a three step process:
273	# 1)  Link .tmp_vmlinux1 so it has all symbols and sections,
274	#     but __kallsyms is empty.
275	#     Running kallsyms on that gives us .tmp_kallsyms1.o with
276	#     the right size
277	# 2)  Link .tmp_vmlinux2 so it now has a __kallsyms section of
278	#     the right size, but due to the added section, some
279	#     addresses have shifted.
280	#     From here, we generate a correct .tmp_kallsyms2.o
281	# 3)  That link may have expanded the kernel image enough that
282	#     more linker branch stubs / trampolines had to be added, which
283	#     introduces new names, which further expands kallsyms. Do another
284	#     pass if that is the case. In theory it's possible this results
285	#     in even more stubs, but unlikely.
286	#     KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
287	#     other bugs.
288	# 4)  The correct ${kallsymso} is linked into the final vmlinux.
289	#
290	# a)  Verify that the System.map from vmlinux matches the map from
291	#     ${kallsymso}.
292
293	kallsyms_step 1
294	kallsyms_step 2
295
296	# step 3
297	size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev})
298	size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
299
300	if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
301		kallsyms_step 3
302	fi
303fi
304
305vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o}
306
307if [ -n "${CONFIG_BUILDTIME_EXTABLE_SORT}" ]; then
308	info SORTEX vmlinux
309	sortextable vmlinux
310fi
311
312info SYSMAP System.map
313mksysmap vmlinux System.map
314
315# step a (see comment above)
316if [ -n "${CONFIG_KALLSYMS}" ]; then
317	mksysmap ${kallsyms_vmlinux} .tmp_System.map
318
319	if ! cmp -s System.map .tmp_System.map; then
320		echo >&2 Inconsistent kallsyms data
321		echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
322		exit 1
323	fi
324fi
325