projects/linux·blob cba5e972 · refs

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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
33LD="$1"
34KBUILD_LDFLAGS="$2"
35LDFLAGS_vmlinux="$3"
36
37# Nice output in kbuild format
38# Will be supressed by "make -s"
39info()
40{
41 if [ "${quiet}" != "silent_" ]; then
42 printf " %-7s %s\n" "${1}" "${2}"
43 fi
44}
45
46# Generate a linker script to ensure correct ordering of initcalls.
47gen_initcalls()
48{
49 info GEN .tmp_initcalls.lds
50
51 ${PYTHON} ${srctree}/scripts/jobserver-exec \
52 ${PERL} ${srctree}/scripts/generate_initcall_order.pl \
53 ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS} \
54 > .tmp_initcalls.lds
55}
56
57# If CONFIG_LTO_CLANG is selected, collect generated symbol versions into
58# .tmp_symversions.lds
59gen_symversions()
60{
61 info GEN .tmp_symversions.lds
62 rm -f .tmp_symversions.lds
63
64 for o in ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS}; do
65 if [ -f ${o}.symversions ]; then
66 cat ${o}.symversions >> .tmp_symversions.lds
67 fi
68 done
69}
70
71# Link of vmlinux.o used for section mismatch analysis
72# ${1} output file
73modpost_link()
74{
75 local objects
76 local lds=""
77
78 objects="--whole-archive \
79 ${KBUILD_VMLINUX_OBJS} \
80 --no-whole-archive \
81 --start-group \
82 ${KBUILD_VMLINUX_LIBS} \
83 --end-group"
84
85 if [ -n "${CONFIG_LTO_CLANG}" ]; then
86 gen_initcalls
87 lds="-T .tmp_initcalls.lds"
88
89 if [ -n "${CONFIG_MODVERSIONS}" ]; then
90 gen_symversions
91 lds="${lds} -T .tmp_symversions.lds"
92 fi
93
94 # This might take a while, so indicate that we're doing
95 # an LTO link
96 info LTO ${1}
97 else
98 info LD ${1}
99 fi
100
101 ${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${lds} ${objects}
102}
103
104objtool_link()
105{
106 local objtoolcmd;
107 local objtoolopt;
108
109 if [ "${CONFIG_LTO_CLANG} ${CONFIG_STACK_VALIDATION}" = "y y" ]; then
110 # Don't perform vmlinux validation unless explicitly requested,
111 # but run objtool on vmlinux.o now that we have an object file.
112 if [ -n "${CONFIG_UNWINDER_ORC}" ]; then
113 objtoolcmd="orc generate"
114 fi
115
116 objtoolopt="${objtoolopt} --duplicate"
117
118 if [ -n "${CONFIG_FTRACE_MCOUNT_USE_OBJTOOL}" ]; then
119 objtoolopt="${objtoolopt} --mcount"
120 fi
121 fi
122
123 if [ -n "${CONFIG_VMLINUX_VALIDATION}" ]; then
124 objtoolopt="${objtoolopt} --noinstr"
125 fi
126
127 if [ -n "${objtoolopt}" ]; then
128 if [ -z "${objtoolcmd}" ]; then
129 objtoolcmd="check"
130 fi
131 objtoolopt="${objtoolopt} --vmlinux"
132 if [ -z "${CONFIG_FRAME_POINTER}" ]; then
133 objtoolopt="${objtoolopt} --no-fp"
134 fi
135 if [ -n "${CONFIG_GCOV_KERNEL}" ] || [ -n "${CONFIG_LTO_CLANG}" ]; then
136 objtoolopt="${objtoolopt} --no-unreachable"
137 fi
138 if [ -n "${CONFIG_RETPOLINE}" ]; then
139 objtoolopt="${objtoolopt} --retpoline"
140 fi
141 if [ -n "${CONFIG_X86_SMAP}" ]; then
142 objtoolopt="${objtoolopt} --uaccess"
143 fi
144 info OBJTOOL ${1}
145 tools/objtool/objtool ${objtoolcmd} ${objtoolopt} ${1}
146 fi
147}
148
149# Link of vmlinux
150# ${1} - output file
151# ${2}, ${3}, ... - optional extra .o files
152vmlinux_link()
153{
154 local lds="${objtree}/${KBUILD_LDS}"
155 local output=${1}
156 local objects
157 local strip_debug
158 local map_option
159
160 info LD ${output}
161
162 # skip output file argument
163 shift
164
165 # The kallsyms linking does not need debug symbols included.
166 if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
167 strip_debug=-Wl,--strip-debug
168 fi
169
170 if [ -n "${CONFIG_VMLINUX_MAP}" ]; then
171 map_option="-Map=${output}.map"
172 fi
173
174 if [ "${SRCARCH}" != "um" ]; then
175 if [ -n "${CONFIG_LTO_CLANG}" ]; then
176 # Use vmlinux.o instead of performing the slow LTO
177 # link again.
178 objects="--whole-archive \
179 vmlinux.o \
180 --no-whole-archive \
181 ${@}"
182 else
183 objects="--whole-archive \
184 ${KBUILD_VMLINUX_OBJS} \
185 --no-whole-archive \
186 --start-group \
187 ${KBUILD_VMLINUX_LIBS} \
188 --end-group \
189 ${@}"
190 fi
191
192 ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} \
193 ${strip_debug#-Wl,} \
194 -o ${output} \
195 ${map_option} \
196 -T ${lds} ${objects}
197 else
198 objects="-Wl,--whole-archive \
199 ${KBUILD_VMLINUX_OBJS} \
200 -Wl,--no-whole-archive \
201 -Wl,--start-group \
202 ${KBUILD_VMLINUX_LIBS} \
203 -Wl,--end-group \
204 ${@}"
205
206 ${CC} ${CFLAGS_vmlinux} \
207 ${strip_debug} \
208 -o ${output} \
209 ${map_option:+-Wl,${map_option}} \
210 -Wl,-T,${lds} \
211 ${objects} \
212 -lutil -lrt -lpthread
213 rm -f linux
214 fi
215}
216
217# generate .BTF typeinfo from DWARF debuginfo
218# ${1} - vmlinux image
219# ${2} - file to dump raw BTF data into
220gen_btf()
221{
222 local pahole_ver
223 local extra_paholeopt=
224
225 if ! [ -x "$(command -v ${PAHOLE})" ]; then
226 echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available"
227 return 1
228 fi
229
230 pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
231 if [ "${pahole_ver}" -lt "116" ]; then
232 echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.16"
233 return 1
234 fi
235
236 vmlinux_link ${1}
237
238 if [ "${pahole_ver}" -ge "121" ]; then
239 extra_paholeopt="${extra_paholeopt} --btf_gen_floats"
240 fi
241
242 info "BTF" ${2}
243 LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${extra_paholeopt} ${1}
244
245 # Create ${2} which contains just .BTF section but no symbols. Add
246 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all
247 # deletes all symbols including __start_BTF and __stop_BTF, which will
248 # be redefined in the linker script. Add 2>/dev/null to suppress GNU
249 # objcopy warnings: "empty loadable segment detected at ..."
250 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \
251 --strip-all ${1} ${2} 2>/dev/null
252 # Change e_type to ET_REL so that it can be used to link final vmlinux.
253 # Unlike GNU ld, lld does not allow an ET_EXEC input.
254 printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none
255}
256
257# Create ${2} .S file with all symbols from the ${1} object file
258kallsyms()
259{
260 local kallsymopt;
261
262 if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
263 kallsymopt="${kallsymopt} --all-symbols"
264 fi
265
266 if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
267 kallsymopt="${kallsymopt} --absolute-percpu"
268 fi
269
270 if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then
271 kallsymopt="${kallsymopt} --base-relative"
272 fi
273
274 info KSYMS ${2}
275 ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${2}
276}
277
278# Perform one step in kallsyms generation, including temporary linking of
279# vmlinux.
280kallsyms_step()
281{
282 kallsymso_prev=${kallsymso}
283 kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1}
284 kallsymso=${kallsyms_vmlinux}.o
285 kallsyms_S=${kallsyms_vmlinux}.S
286
287 vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o}
288 kallsyms ${kallsyms_vmlinux} ${kallsyms_S}
289
290 info AS ${kallsyms_S}
291 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \
292 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \
293 -c -o ${kallsymso} ${kallsyms_S}
294}
295
296# Create map file with all symbols from ${1}
297# See mksymap for additional details
298mksysmap()
299{
300 ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
301}
302
303sorttable()
304{
305 ${objtree}/scripts/sorttable ${1}
306}
307
308# Delete output files in case of error
309cleanup()
310{
311 rm -f .btf.*
312 rm -f .tmp_System.map
313 rm -f .tmp_initcalls.lds
314 rm -f .tmp_symversions.lds
315 rm -f .tmp_vmlinux*
316 rm -f System.map
317 rm -f vmlinux
318 rm -f vmlinux.map
319 rm -f vmlinux.o
320 rm -f .vmlinux.d
321}
322
323# Use "make V=1" to debug this script
324case "${KBUILD_VERBOSE}" in
325*1*)
326 set -x
327 ;;
328esac
329
330if [ "$1" = "clean" ]; then
331 cleanup
332 exit 0
333fi
334
335# We need access to CONFIG_ symbols
336. include/config/auto.conf
337
338# Update version
339info GEN .version
340if [ -r .version ]; then
341 VERSION=$(expr 0$(cat .version) + 1)
342 echo $VERSION > .version
343else
344 rm -f .version
345 echo 1 > .version
346fi;
347
348# final build of init/
349${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1
350
351#link vmlinux.o
352modpost_link vmlinux.o
353objtool_link vmlinux.o
354
355# modpost vmlinux.o to check for section mismatches
356${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1
357
358info MODINFO modules.builtin.modinfo
359${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo
360info GEN modules.builtin
361# The second line aids cases where multiple modules share the same object.
362tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' |
363 tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin
364
365btf_vmlinux_bin_o=""
366if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then
367 btf_vmlinux_bin_o=.btf.vmlinux.bin.o
368 if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then
369 echo >&2 "Failed to generate BTF for vmlinux"
370 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF"
371 exit 1
372 fi
373fi
374
375kallsymso=""
376kallsymso_prev=""
377kallsyms_vmlinux=""
378if [ -n "${CONFIG_KALLSYMS}" ]; then
379
380 # kallsyms support
381 # Generate section listing all symbols and add it into vmlinux
382 # It's a three step process:
383 # 1) Link .tmp_vmlinux1 so it has all symbols and sections,
384 # but __kallsyms is empty.
385 # Running kallsyms on that gives us .tmp_kallsyms1.o with
386 # the right size
387 # 2) Link .tmp_vmlinux2 so it now has a __kallsyms section of
388 # the right size, but due to the added section, some
389 # addresses have shifted.
390 # From here, we generate a correct .tmp_kallsyms2.o
391 # 3) That link may have expanded the kernel image enough that
392 # more linker branch stubs / trampolines had to be added, which
393 # introduces new names, which further expands kallsyms. Do another
394 # pass if that is the case. In theory it's possible this results
395 # in even more stubs, but unlikely.
396 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
397 # other bugs.
398 # 4) The correct ${kallsymso} is linked into the final vmlinux.
399 #
400 # a) Verify that the System.map from vmlinux matches the map from
401 # ${kallsymso}.
402
403 kallsyms_step 1
404 kallsyms_step 2
405
406 # step 3
407 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev})
408 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
409
410 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
411 kallsyms_step 3
412 fi
413fi
414
415vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o}
416
417# fill in BTF IDs
418if [ -n "${CONFIG_DEBUG_INFO_BTF}" -a -n "${CONFIG_BPF}" ]; then
419 info BTFIDS vmlinux
420 ${RESOLVE_BTFIDS} vmlinux
421fi
422
423if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then
424 info SORTTAB vmlinux
425 if ! sorttable vmlinux; then
426 echo >&2 Failed to sort kernel tables
427 exit 1
428 fi
429fi
430
431info SYSMAP System.map
432mksysmap vmlinux System.map
433
434# step a (see comment above)
435if [ -n "${CONFIG_KALLSYMS}" ]; then
436 mksysmap ${kallsyms_vmlinux} .tmp_System.map
437
438 if ! cmp -s System.map .tmp_System.map; then
439 echo >&2 Inconsistent kallsyms data
440 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
441 exit 1
442 fi
443fi
444
445# For fixdep
446echo "vmlinux: $0" > .vmlinux.d