xref: /openbmc/linux/scripts/link-vmlinux.sh (revision 5d331b7f) 
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_INIT) and
7# $(KBUILD_VMLINUX_MAIN) and $(KBUILD_VMLINUX_LIBS). Most are built-in.a files
8# from top-level directories in the kernel tree, others are specified in
9# arch/$(ARCH)/Makefile. Ordering when linking is important, and
10# $(KBUILD_VMLINUX_INIT) must be first. $(KBUILD_VMLINUX_LIBS) are archives
11# which are linked conditionally (not within --whole-archive), and do not
12# require symbol indexes added.
13#
14# vmlinux
15#   ^
16#   |
17#   +-< $(KBUILD_VMLINUX_INIT)
18#   |   +--< init/version.o + more
19#   |
20#   +--< $(KBUILD_VMLINUX_MAIN)
21#   |    +--< drivers/built-in.a mm/built-in.a + more
22#   |
23#   +--< $(KBUILD_VMLINUX_LIBS)
24#   |    +--< lib/lib.a + more
25#   |
26#   +-< ${kallsymso} (see description in KALLSYMS section)
27#
28# vmlinux version (uname -v) cannot be updated during normal
29# descending-into-subdirs phase since we do not yet know if we need to
30# update vmlinux.
31# Therefore this step is delayed until just before final link of vmlinux.
32#
33# System.map is generated to document addresses of all kernel symbols
34
35# Error out on error
36set -e
37
38# Nice output in kbuild format
39# Will be supressed by "make -s"
40info()
41{
42	if [ "${quiet}" != "silent_" ]; then
43		printf "  %-7s %s\n" ${1} ${2}
44	fi
45}
46
47# Thin archive build here makes a final archive with symbol table and indexes
48# from vmlinux objects INIT and MAIN, which can be used as input to linker.
49# KBUILD_VMLINUX_LIBS archives should already have symbol table and indexes
50# added.
51#
52# Traditional incremental style of link does not require this step
53#
54# built-in.a output file
55#
56archive_builtin()
57{
58	info AR built-in.a
59	rm -f built-in.a;
60	${AR} rcsTP${KBUILD_ARFLAGS} built-in.a			\
61				${KBUILD_VMLINUX_INIT}		\
62				${KBUILD_VMLINUX_MAIN}
63}
64
65# Link of vmlinux.o used for section mismatch analysis
66# ${1} output file
67modpost_link()
68{
69	local objects
70
71	objects="--whole-archive				\
72		built-in.a					\
73		--no-whole-archive				\
74		--start-group					\
75		${KBUILD_VMLINUX_LIBS}				\
76		--end-group"
77
78	${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${objects}
79}
80
81# Link of vmlinux
82# ${1} - optional extra .o files
83# ${2} - output file
84vmlinux_link()
85{
86	local lds="${objtree}/${KBUILD_LDS}"
87	local objects
88
89	if [ "${SRCARCH}" != "um" ]; then
90		objects="--whole-archive			\
91			built-in.a				\
92			--no-whole-archive			\
93			--start-group				\
94			${KBUILD_VMLINUX_LIBS}			\
95			--end-group				\
96			${1}"
97
98		${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} -o ${2}	\
99			-T ${lds} ${objects}
100	else
101		objects="-Wl,--whole-archive			\
102			built-in.a				\
103			-Wl,--no-whole-archive			\
104			-Wl,--start-group			\
105			${KBUILD_VMLINUX_LIBS}			\
106			-Wl,--end-group				\
107			${1}"
108
109		${CC} ${CFLAGS_vmlinux} -o ${2}			\
110			-Wl,-T,${lds}				\
111			${objects}				\
112			-lutil -lrt -lpthread
113		rm -f linux
114	fi
115}
116
117
118# Create ${2} .o file with all symbols from the ${1} object file
119kallsyms()
120{
121	info KSYM ${2}
122	local kallsymopt;
123
124	if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
125		kallsymopt="${kallsymopt} --all-symbols"
126	fi
127
128	if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
129		kallsymopt="${kallsymopt} --absolute-percpu"
130	fi
131
132	if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then
133		kallsymopt="${kallsymopt} --base-relative"
134	fi
135
136	local aflags="${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL}               \
137		      ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS}"
138
139	local afile="`basename ${2} .o`.S"
140
141	${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${afile}
142	${CC} ${aflags} -c -o ${2} ${afile}
143}
144
145# Create map file with all symbols from ${1}
146# See mksymap for additional details
147mksysmap()
148{
149	${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
150}
151
152sortextable()
153{
154	${objtree}/scripts/sortextable ${1}
155}
156
157# Delete output files in case of error
158cleanup()
159{
160	rm -f .tmp_System.map
161	rm -f .tmp_kallsyms*
162	rm -f .tmp_vmlinux*
163	rm -f built-in.a
164	rm -f System.map
165	rm -f vmlinux
166	rm -f vmlinux.o
167}
168
169on_exit()
170{
171	if [ $? -ne 0 ]; then
172		cleanup
173	fi
174}
175trap on_exit EXIT
176
177on_signals()
178{
179	exit 1
180}
181trap on_signals HUP INT QUIT TERM
182
183#
184#
185# Use "make V=1" to debug this script
186case "${KBUILD_VERBOSE}" in
187*1*)
188	set -x
189	;;
190esac
191
192if [ "$1" = "clean" ]; then
193	cleanup
194	exit 0
195fi
196
197# We need access to CONFIG_ symbols
198case "${KCONFIG_CONFIG}" in
199*/*)
200	. "${KCONFIG_CONFIG}"
201	;;
202*)
203	# Force using a file from the current directory
204	. "./${KCONFIG_CONFIG}"
205esac
206
207# Update version
208info GEN .version
209if [ -r .version ]; then
210	VERSION=$(expr 0$(cat .version) + 1)
211	echo $VERSION > .version
212else
213	rm -f .version
214	echo 1 > .version
215fi;
216
217# final build of init/
218${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init
219
220archive_builtin
221
222#link vmlinux.o
223info LD vmlinux.o
224modpost_link vmlinux.o
225
226# modpost vmlinux.o to check for section mismatches
227${MAKE} -f "${srctree}/scripts/Makefile.modpost" vmlinux.o
228
229kallsymso=""
230kallsyms_vmlinux=""
231if [ -n "${CONFIG_KALLSYMS}" ]; then
232
233	# kallsyms support
234	# Generate section listing all symbols and add it into vmlinux
235	# It's a three step process:
236	# 1)  Link .tmp_vmlinux1 so it has all symbols and sections,
237	#     but __kallsyms is empty.
238	#     Running kallsyms on that gives us .tmp_kallsyms1.o with
239	#     the right size
240	# 2)  Link .tmp_vmlinux2 so it now has a __kallsyms section of
241	#     the right size, but due to the added section, some
242	#     addresses have shifted.
243	#     From here, we generate a correct .tmp_kallsyms2.o
244	# 3)  That link may have expanded the kernel image enough that
245	#     more linker branch stubs / trampolines had to be added, which
246	#     introduces new names, which further expands kallsyms. Do another
247	#     pass if that is the case. In theory it's possible this results
248	#     in even more stubs, but unlikely.
249	#     KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
250	#     other bugs.
251	# 4)  The correct ${kallsymso} is linked into the final vmlinux.
252	#
253	# a)  Verify that the System.map from vmlinux matches the map from
254	#     ${kallsymso}.
255
256	kallsymso=.tmp_kallsyms2.o
257	kallsyms_vmlinux=.tmp_vmlinux2
258
259	# step 1
260	vmlinux_link "" .tmp_vmlinux1
261	kallsyms .tmp_vmlinux1 .tmp_kallsyms1.o
262
263	# step 2
264	vmlinux_link .tmp_kallsyms1.o .tmp_vmlinux2
265	kallsyms .tmp_vmlinux2 .tmp_kallsyms2.o
266
267	# step 3
268	size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" .tmp_kallsyms1.o)
269	size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" .tmp_kallsyms2.o)
270
271	if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
272		kallsymso=.tmp_kallsyms3.o
273		kallsyms_vmlinux=.tmp_vmlinux3
274
275		vmlinux_link .tmp_kallsyms2.o .tmp_vmlinux3
276
277		kallsyms .tmp_vmlinux3 .tmp_kallsyms3.o
278	fi
279fi
280
281info LD vmlinux
282vmlinux_link "${kallsymso}" vmlinux
283
284if [ -n "${CONFIG_BUILDTIME_EXTABLE_SORT}" ]; then
285	info SORTEX vmlinux
286	sortextable vmlinux
287fi
288
289info SYSMAP System.map
290mksysmap vmlinux System.map
291
292# step a (see comment above)
293if [ -n "${CONFIG_KALLSYMS}" ]; then
294	mksysmap ${kallsyms_vmlinux} .tmp_System.map
295
296	if ! cmp -s System.map .tmp_System.map; then
297		echo >&2 Inconsistent kallsyms data
298		echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
299		exit 1
300	fi
301fi
302