xref: /openbmc/linux/scripts/link-vmlinux.sh (revision a5a92abb) 
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} ${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} ${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_HAVE_UNDERSCORE_SYMBOL_PREFIX}" ]; then
125		kallsymopt="${kallsymopt} --symbol-prefix=_"
126	fi
127
128	if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
129		kallsymopt="${kallsymopt} --all-symbols"
130	fi
131
132	if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
133		kallsymopt="${kallsymopt} --absolute-percpu"
134	fi
135
136	if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then
137		kallsymopt="${kallsymopt} --base-relative"
138	fi
139
140	local aflags="${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL}               \
141		      ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS}"
142
143	local afile="`basename ${2} .o`.S"
144
145	${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${afile}
146	${CC} ${aflags} -c -o ${2} ${afile}
147}
148
149# Create map file with all symbols from ${1}
150# See mksymap for additional details
151mksysmap()
152{
153	${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
154}
155
156sortextable()
157{
158	${objtree}/scripts/sortextable ${1}
159}
160
161# Delete output files in case of error
162cleanup()
163{
164	rm -f .tmp_System.map
165	rm -f .tmp_kallsyms*
166	rm -f .tmp_vmlinux*
167	rm -f built-in.a
168	rm -f System.map
169	rm -f vmlinux
170	rm -f vmlinux.o
171}
172
173on_exit()
174{
175	if [ $? -ne 0 ]; then
176		cleanup
177	fi
178}
179trap on_exit EXIT
180
181on_signals()
182{
183	exit 1
184}
185trap on_signals HUP INT QUIT TERM
186
187#
188#
189# Use "make V=1" to debug this script
190case "${KBUILD_VERBOSE}" in
191*1*)
192	set -x
193	;;
194esac
195
196if [ "$1" = "clean" ]; then
197	cleanup
198	exit 0
199fi
200
201# We need access to CONFIG_ symbols
202case "${KCONFIG_CONFIG}" in
203*/*)
204	. "${KCONFIG_CONFIG}"
205	;;
206*)
207	# Force using a file from the current directory
208	. "./${KCONFIG_CONFIG}"
209esac
210
211# Update version
212info GEN .version
213if [ -r .version ]; then
214	VERSION=$(expr 0$(cat .version) + 1)
215	echo $VERSION > .version
216else
217	rm -f .version
218	echo 1 > .version
219fi;
220
221# final build of init/
222${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init
223
224archive_builtin
225
226#link vmlinux.o
227info LD vmlinux.o
228modpost_link vmlinux.o
229
230# modpost vmlinux.o to check for section mismatches
231${MAKE} -f "${srctree}/scripts/Makefile.modpost" vmlinux.o
232
233kallsymso=""
234kallsyms_vmlinux=""
235if [ -n "${CONFIG_KALLSYMS}" ]; then
236
237	# kallsyms support
238	# Generate section listing all symbols and add it into vmlinux
239	# It's a three step process:
240	# 1)  Link .tmp_vmlinux1 so it has all symbols and sections,
241	#     but __kallsyms is empty.
242	#     Running kallsyms on that gives us .tmp_kallsyms1.o with
243	#     the right size
244	# 2)  Link .tmp_vmlinux2 so it now has a __kallsyms section of
245	#     the right size, but due to the added section, some
246	#     addresses have shifted.
247	#     From here, we generate a correct .tmp_kallsyms2.o
248	# 3)  That link may have expanded the kernel image enough that
249	#     more linker branch stubs / trampolines had to be added, which
250	#     introduces new names, which further expands kallsyms. Do another
251	#     pass if that is the case. In theory it's possible this results
252	#     in even more stubs, but unlikely.
253	#     KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
254	#     other bugs.
255	# 4)  The correct ${kallsymso} is linked into the final vmlinux.
256	#
257	# a)  Verify that the System.map from vmlinux matches the map from
258	#     ${kallsymso}.
259
260	kallsymso=.tmp_kallsyms2.o
261	kallsyms_vmlinux=.tmp_vmlinux2
262
263	# step 1
264	vmlinux_link "" .tmp_vmlinux1
265	kallsyms .tmp_vmlinux1 .tmp_kallsyms1.o
266
267	# step 2
268	vmlinux_link .tmp_kallsyms1.o .tmp_vmlinux2
269	kallsyms .tmp_vmlinux2 .tmp_kallsyms2.o
270
271	# step 3
272	size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" .tmp_kallsyms1.o)
273	size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" .tmp_kallsyms2.o)
274
275	if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
276		kallsymso=.tmp_kallsyms3.o
277		kallsyms_vmlinux=.tmp_vmlinux3
278
279		vmlinux_link .tmp_kallsyms2.o .tmp_vmlinux3
280
281		kallsyms .tmp_vmlinux3 .tmp_kallsyms3.o
282	fi
283fi
284
285info LD vmlinux
286vmlinux_link "${kallsymso}" vmlinux
287
288if [ -n "${CONFIG_BUILDTIME_EXTABLE_SORT}" ]; then
289	info SORTEX vmlinux
290	sortextable vmlinux
291fi
292
293info SYSMAP System.map
294mksysmap vmlinux System.map
295
296# step a (see comment above)
297if [ -n "${CONFIG_KALLSYMS}" ]; then
298	mksysmap ${kallsyms_vmlinux} .tmp_System.map
299
300	if ! cmp -s System.map .tmp_System.map; then
301		echo >&2 Inconsistent kallsyms data
302		echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
303		exit 1
304	fi
305fi
306