projects/linux·blob v5.18 · refs

436 lines · 10.9 KiB

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
37is_enabled() {
38 grep -q "^$1=y" include/config/auto.conf
39}
40
41# Nice output in kbuild format
42# Will be supressed by "make -s"
43info()
44{
45 printf " %-7s %s\n" "${1}" "${2}"
46}
47
48# Generate a linker script to ensure correct ordering of initcalls.
49gen_initcalls()
50{
51 info GEN .tmp_initcalls.lds
52
53 ${PYTHON3} ${srctree}/scripts/jobserver-exec \
54 ${PERL} ${srctree}/scripts/generate_initcall_order.pl \
55 ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS} \
56 > .tmp_initcalls.lds
57}
58
59# If CONFIG_LTO_CLANG is selected, collect generated symbol versions into
60# .tmp_symversions.lds
61gen_symversions()
62{
63 info GEN .tmp_symversions.lds
64 rm -f .tmp_symversions.lds
65
66 for o in ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS}; do
67 if [ -f ${o}.symversions ]; then
68 cat ${o}.symversions >> .tmp_symversions.lds
69 fi
70 done
71}
72
73# Link of vmlinux.o used for section mismatch analysis
74# ${1} output file
75modpost_link()
76{
77 local objects
78 local lds=""
79
80 objects="--whole-archive \
81 ${KBUILD_VMLINUX_OBJS} \
82 --no-whole-archive \
83 --start-group \
84 ${KBUILD_VMLINUX_LIBS} \
85 --end-group"
86
87 if is_enabled CONFIG_LTO_CLANG; then
88 gen_initcalls
89 lds="-T .tmp_initcalls.lds"
90
91 if is_enabled CONFIG_MODVERSIONS; then
92 gen_symversions
93 lds="${lds} -T .tmp_symversions.lds"
94 fi
95
96 # This might take a while, so indicate that we're doing
97 # an LTO link
98 info LTO ${1}
99 else
100 info LD ${1}
101 fi
102
103 ${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${lds} ${objects}
104}
105
106objtool_link()
107{
108 local objtoolcmd;
109 local objtoolopt;
110
111 if is_enabled CONFIG_STACK_VALIDATION && \
112 ( is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT ); then
113
114 # Don't perform vmlinux validation unless explicitly requested,
115 # but run objtool on vmlinux.o now that we have an object file.
116 if is_enabled CONFIG_UNWINDER_ORC; then
117 objtoolcmd="orc generate"
118 fi
119
120 objtoolopt="${objtoolopt} --lto"
121
122 if is_enabled CONFIG_X86_KERNEL_IBT; then
123 objtoolopt="${objtoolopt} --ibt"
124 fi
125
126 if is_enabled CONFIG_FTRACE_MCOUNT_USE_OBJTOOL; then
127 objtoolopt="${objtoolopt} --mcount"
128 fi
129 fi
130
131 if is_enabled CONFIG_VMLINUX_VALIDATION; then
132 objtoolopt="${objtoolopt} --noinstr"
133 fi
134
135 if [ -n "${objtoolopt}" ]; then
136 if [ -z "${objtoolcmd}" ]; then
137 objtoolcmd="check"
138 fi
139 objtoolopt="${objtoolopt} --vmlinux"
140 if ! is_enabled CONFIG_FRAME_POINTER; then
141 objtoolopt="${objtoolopt} --no-fp"
142 fi
143 if is_enabled CONFIG_GCOV_KERNEL; then
144 objtoolopt="${objtoolopt} --no-unreachable"
145 fi
146 if is_enabled CONFIG_RETPOLINE; then
147 objtoolopt="${objtoolopt} --retpoline"
148 fi
149 if is_enabled CONFIG_X86_SMAP; then
150 objtoolopt="${objtoolopt} --uaccess"
151 fi
152 if is_enabled CONFIG_SLS; then
153 objtoolopt="${objtoolopt} --sls"
154 fi
155 info OBJTOOL ${1}
156 tools/objtool/objtool ${objtoolcmd} ${objtoolopt} ${1}
157 fi
158}
159
160# Link of vmlinux
161# ${1} - output file
162# ${2}, ${3}, ... - optional extra .o files
163vmlinux_link()
164{
165 local output=${1}
166 local objs
167 local libs
168 local ld
169 local ldflags
170 local ldlibs
171
172 info LD ${output}
173
174 # skip output file argument
175 shift
176
177 if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then
178 # Use vmlinux.o instead of performing the slow LTO link again.
179 objs=vmlinux.o
180 libs=
181 else
182 objs="${KBUILD_VMLINUX_OBJS}"
183 libs="${KBUILD_VMLINUX_LIBS}"
184 fi
185
186 if [ "${SRCARCH}" = "um" ]; then
187 wl=-Wl,
188 ld="${CC}"
189 ldflags="${CFLAGS_vmlinux}"
190 ldlibs="-lutil -lrt -lpthread"
191 else
192 wl=
193 ld="${LD}"
194 ldflags="${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}"
195 ldlibs=
196 fi
197
198 ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}"
199
200 # The kallsyms linking does not need debug symbols included.
201 if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
202 ldflags="${ldflags} ${wl}--strip-debug"
203 fi
204
205 if is_enabled CONFIG_VMLINUX_MAP; then
206 ldflags="${ldflags} ${wl}-Map=${output}.map"
207 fi
208
209 ${ld} ${ldflags} -o ${output} \
210 ${wl}--whole-archive ${objs} ${wl}--no-whole-archive \
211 ${wl}--start-group ${libs} ${wl}--end-group \
212 $@ ${ldlibs}
213}
214
215# generate .BTF typeinfo from DWARF debuginfo
216# ${1} - vmlinux image
217# ${2} - file to dump raw BTF data into
218gen_btf()
219{
220 local pahole_ver
221
222 if ! [ -x "$(command -v ${PAHOLE})" ]; then
223 echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available"
224 return 1
225 fi
226
227 pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
228 if [ "${pahole_ver}" -lt "116" ]; then
229 echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.16"
230 return 1
231 fi
232
233 vmlinux_link ${1}
234
235 info "BTF" ${2}
236 LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1}
237
238 # Create ${2} which contains just .BTF section but no symbols. Add
239 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all
240 # deletes all symbols including __start_BTF and __stop_BTF, which will
241 # be redefined in the linker script. Add 2>/dev/null to suppress GNU
242 # objcopy warnings: "empty loadable segment detected at ..."
243 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \
244 --strip-all ${1} ${2} 2>/dev/null
245 # Change e_type to ET_REL so that it can be used to link final vmlinux.
246 # Unlike GNU ld, lld does not allow an ET_EXEC input.
247 printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none
248}
249
250# Create ${2} .S file with all symbols from the ${1} object file
251kallsyms()
252{
253 local kallsymopt;
254
255 if is_enabled CONFIG_KALLSYMS_ALL; then
256 kallsymopt="${kallsymopt} --all-symbols"
257 fi
258
259 if is_enabled CONFIG_KALLSYMS_ABSOLUTE_PERCPU; then
260 kallsymopt="${kallsymopt} --absolute-percpu"
261 fi
262
263 if is_enabled CONFIG_KALLSYMS_BASE_RELATIVE; then
264 kallsymopt="${kallsymopt} --base-relative"
265 fi
266
267 info KSYMS ${2}
268 ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${2}
269}
270
271# Perform one step in kallsyms generation, including temporary linking of
272# vmlinux.
273kallsyms_step()
274{
275 kallsymso_prev=${kallsymso}
276 kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1}
277 kallsymso=${kallsyms_vmlinux}.o
278 kallsyms_S=${kallsyms_vmlinux}.S
279
280 vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o}
281 kallsyms ${kallsyms_vmlinux} ${kallsyms_S}
282
283 info AS ${kallsyms_S}
284 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \
285 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \
286 -c -o ${kallsymso} ${kallsyms_S}
287}
288
289# Create map file with all symbols from ${1}
290# See mksymap for additional details
291mksysmap()
292{
293 ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
294}
295
296sorttable()
297{
298 ${objtree}/scripts/sorttable ${1}
299}
300
301# Delete output files in case of error
302cleanup()
303{
304 rm -f .btf.*
305 rm -f .tmp_System.map
306 rm -f .tmp_initcalls.lds
307 rm -f .tmp_symversions.lds
308 rm -f .tmp_vmlinux*
309 rm -f System.map
310 rm -f vmlinux
311 rm -f vmlinux.map
312 rm -f vmlinux.o
313 rm -f .vmlinux.d
314}
315
316# Use "make V=1" to debug this script
317case "${KBUILD_VERBOSE}" in
318*1*)
319 set -x
320 ;;
321esac
322
323if [ "$1" = "clean" ]; then
324 cleanup
325 exit 0
326fi
327
328# Update version
329info GEN .version
330if [ -r .version ]; then
331 VERSION=$(expr 0$(cat .version) + 1)
332 echo $VERSION > .version
333else
334 rm -f .version
335 echo 1 > .version
336fi;
337
338# final build of init/
339${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1
340
341#link vmlinux.o
342modpost_link vmlinux.o
343objtool_link vmlinux.o
344
345# modpost vmlinux.o to check for section mismatches
346${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1
347
348info MODINFO modules.builtin.modinfo
349${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo
350info GEN modules.builtin
351# The second line aids cases where multiple modules share the same object.
352tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' |
353 tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin
354
355btf_vmlinux_bin_o=""
356if is_enabled CONFIG_DEBUG_INFO_BTF; then
357 btf_vmlinux_bin_o=.btf.vmlinux.bin.o
358 if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then
359 echo >&2 "Failed to generate BTF for vmlinux"
360 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF"
361 exit 1
362 fi
363fi
364
365kallsymso=""
366kallsymso_prev=""
367kallsyms_vmlinux=""
368if is_enabled CONFIG_KALLSYMS; then
369
370 # kallsyms support
371 # Generate section listing all symbols and add it into vmlinux
372 # It's a three step process:
373 # 1) Link .tmp_vmlinux.kallsyms1 so it has all symbols and sections,
374 # but __kallsyms is empty.
375 # Running kallsyms on that gives us .tmp_kallsyms1.o with
376 # the right size
377 # 2) Link .tmp_vmlinux.kallsyms2 so it now has a __kallsyms section of
378 # the right size, but due to the added section, some
379 # addresses have shifted.
380 # From here, we generate a correct .tmp_vmlinux.kallsyms2.o
381 # 3) That link may have expanded the kernel image enough that
382 # more linker branch stubs / trampolines had to be added, which
383 # introduces new names, which further expands kallsyms. Do another
384 # pass if that is the case. In theory it's possible this results
385 # in even more stubs, but unlikely.
386 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
387 # other bugs.
388 # 4) The correct ${kallsymso} is linked into the final vmlinux.
389 #
390 # a) Verify that the System.map from vmlinux matches the map from
391 # ${kallsymso}.
392
393 kallsyms_step 1
394 kallsyms_step 2
395
396 # step 3
397 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev})
398 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
399
400 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
401 kallsyms_step 3
402 fi
403fi
404
405vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o}
406
407# fill in BTF IDs
408if is_enabled CONFIG_DEBUG_INFO_BTF && is_enabled CONFIG_BPF; then
409 info BTFIDS vmlinux
410 ${RESOLVE_BTFIDS} vmlinux
411fi
412
413info SYSMAP System.map
414mksysmap vmlinux System.map
415
416if is_enabled CONFIG_BUILDTIME_TABLE_SORT; then
417 info SORTTAB vmlinux
418 if ! sorttable vmlinux; then
419 echo >&2 Failed to sort kernel tables
420 exit 1
421 fi
422fi
423
424# step a (see comment above)
425if is_enabled CONFIG_KALLSYMS; then
426 mksysmap ${kallsyms_vmlinux} .tmp_System.map
427
428 if ! cmp -s System.map .tmp_System.map; then
429 echo >&2 Inconsistent kallsyms data
430 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
431 exit 1
432 fi
433fi
434
435# For fixdep
436echo "vmlinux: $0" > .vmlinux.d