projects/linux·blob v6.10 · refs

304 lines · 7.6 KiB

1#!/bin/sh
2# SPDX-License-Identifier: GPL-2.0
3#
4# link vmlinux
5#
6# vmlinux is linked from the objects in vmlinux.a and $(KBUILD_VMLINUX_LIBS).
7# vmlinux.a contains objects that are linked unconditionally.
8# $(KBUILD_VMLINUX_LIBS) are archives which are linked conditionally
9# (not within --whole-archive), and do not require symbol indexes added.
10#
11# vmlinux
12# ^
13# |
14# +--< vmlinux.a
15# |
16# +--< $(KBUILD_VMLINUX_LIBS)
17# | +--< lib/lib.a + more
18# |
19# +-< ${kallsymso} (see description in KALLSYMS section)
20#
21# vmlinux version (uname -v) cannot be updated during normal
22# descending-into-subdirs phase since we do not yet know if we need to
23# update vmlinux.
24# Therefore this step is delayed until just before final link of vmlinux.
25#
26# System.map is generated to document addresses of all kernel symbols
27
28# Error out on error
29set -e
30
31LD="$1"
32KBUILD_LDFLAGS="$2"
33LDFLAGS_vmlinux="$3"
34
35is_enabled() {
36 grep -q "^$1=y" include/config/auto.conf
37}
38
39# Nice output in kbuild format
40# Will be supressed by "make -s"
41info()
42{
43 printf " %-7s %s\n" "${1}" "${2}"
44}
45
46# Link of vmlinux
47# ${1} - output file
48# ${2}, ${3}, ... - optional extra .o files
49vmlinux_link()
50{
51 local output=${1}
52 local objs
53 local libs
54 local ld
55 local ldflags
56 local ldlibs
57
58 info LD ${output}
59
60 # skip output file argument
61 shift
62
63 if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then
64 # Use vmlinux.o instead of performing the slow LTO link again.
65 objs=vmlinux.o
66 libs=
67 else
68 objs=vmlinux.a
69 libs="${KBUILD_VMLINUX_LIBS}"
70 fi
71
72 if is_enabled CONFIG_MODULES; then
73 objs="${objs} .vmlinux.export.o"
74 fi
75
76 objs="${objs} init/version-timestamp.o"
77
78 if [ "${SRCARCH}" = "um" ]; then
79 wl=-Wl,
80 ld="${CC}"
81 ldflags="${CFLAGS_vmlinux}"
82 ldlibs="-lutil -lrt -lpthread"
83 else
84 wl=
85 ld="${LD}"
86 ldflags="${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}"
87 ldlibs=
88 fi
89
90 ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}"
91
92 # The kallsyms linking does not need debug symbols included.
93 if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
94 ldflags="${ldflags} ${wl}--strip-debug"
95 fi
96
97 if is_enabled CONFIG_VMLINUX_MAP; then
98 ldflags="${ldflags} ${wl}-Map=${output}.map"
99 fi
100
101 ${ld} ${ldflags} -o ${output} \
102 ${wl}--whole-archive ${objs} ${wl}--no-whole-archive \
103 ${wl}--start-group ${libs} ${wl}--end-group \
104 $@ ${ldlibs}
105}
106
107# generate .BTF typeinfo from DWARF debuginfo
108# ${1} - vmlinux image
109# ${2} - file to dump raw BTF data into
110gen_btf()
111{
112 local pahole_ver
113
114 if ! [ -x "$(command -v ${PAHOLE})" ]; then
115 echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available"
116 return 1
117 fi
118
119 pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
120 if [ "${pahole_ver}" -lt "116" ]; then
121 echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.16"
122 return 1
123 fi
124
125 vmlinux_link ${1}
126
127 info "BTF" ${2}
128 LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1}
129
130 # Create ${2} which contains just .BTF section but no symbols. Add
131 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all
132 # deletes all symbols including __start_BTF and __stop_BTF, which will
133 # be redefined in the linker script. Add 2>/dev/null to suppress GNU
134 # objcopy warnings: "empty loadable segment detected at ..."
135 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \
136 --strip-all ${1} ${2} 2>/dev/null
137 # Change e_type to ET_REL so that it can be used to link final vmlinux.
138 # GNU ld 2.35+ and lld do not allow an ET_EXEC input.
139 if is_enabled CONFIG_CPU_BIG_ENDIAN; then
140 et_rel='\0\1'
141 else
142 et_rel='\1\0'
143 fi
144 printf "${et_rel}" | dd of=${2} conv=notrunc bs=1 seek=16 status=none
145}
146
147# Create ${2} .S file with all symbols from the ${1} object file
148kallsyms()
149{
150 local kallsymopt;
151
152 if is_enabled CONFIG_KALLSYMS_ALL; then
153 kallsymopt="${kallsymopt} --all-symbols"
154 fi
155
156 if is_enabled CONFIG_KALLSYMS_ABSOLUTE_PERCPU; then
157 kallsymopt="${kallsymopt} --absolute-percpu"
158 fi
159
160 if is_enabled CONFIG_KALLSYMS_BASE_RELATIVE; then
161 kallsymopt="${kallsymopt} --base-relative"
162 fi
163
164 if is_enabled CONFIG_LTO_CLANG; then
165 kallsymopt="${kallsymopt} --lto-clang"
166 fi
167
168 info KSYMS ${2}
169 scripts/kallsyms ${kallsymopt} ${1} > ${2}
170}
171
172# Perform one step in kallsyms generation, including temporary linking of
173# vmlinux.
174kallsyms_step()
175{
176 kallsymso_prev=${kallsymso}
177 kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1}
178 kallsymso=${kallsyms_vmlinux}.o
179 kallsyms_S=${kallsyms_vmlinux}.S
180
181 vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o}
182 mksysmap ${kallsyms_vmlinux} ${kallsyms_vmlinux}.syms
183 kallsyms ${kallsyms_vmlinux}.syms ${kallsyms_S}
184
185 info AS ${kallsymso}
186 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \
187 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \
188 -c -o ${kallsymso} ${kallsyms_S}
189}
190
191# Create map file with all symbols from ${1}
192# See mksymap for additional details
193mksysmap()
194{
195 info NM ${2}
196 ${NM} -n "${1}" | sed -f "${srctree}/scripts/mksysmap" > "${2}"
197}
198
199sorttable()
200{
201 ${objtree}/scripts/sorttable ${1}
202}
203
204cleanup()
205{
206 rm -f .btf.*
207 rm -f System.map
208 rm -f vmlinux
209 rm -f vmlinux.map
210}
211
212# Use "make V=1" to debug this script
213case "${KBUILD_VERBOSE}" in
214*1*)
215 set -x
216 ;;
217esac
218
219if [ "$1" = "clean" ]; then
220 cleanup
221 exit 0
222fi
223
224${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init init/version-timestamp.o
225
226btf_vmlinux_bin_o=""
227if is_enabled CONFIG_DEBUG_INFO_BTF; then
228 btf_vmlinux_bin_o=.btf.vmlinux.bin.o
229 if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then
230 echo >&2 "Failed to generate BTF for vmlinux"
231 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF"
232 exit 1
233 fi
234fi
235
236kallsymso=""
237kallsymso_prev=""
238kallsyms_vmlinux=""
239if is_enabled CONFIG_KALLSYMS; then
240
241 # kallsyms support
242 # Generate section listing all symbols and add it into vmlinux
243 # It's a three step process:
244 # 1) Link .tmp_vmlinux.kallsyms1 so it has all symbols and sections,
245 # but __kallsyms is empty.
246 # Running kallsyms on that gives us .tmp_kallsyms1.o with
247 # the right size
248 # 2) Link .tmp_vmlinux.kallsyms2 so it now has a __kallsyms section of
249 # the right size, but due to the added section, some
250 # addresses have shifted.
251 # From here, we generate a correct .tmp_vmlinux.kallsyms2.o
252 # 3) That link may have expanded the kernel image enough that
253 # more linker branch stubs / trampolines had to be added, which
254 # introduces new names, which further expands kallsyms. Do another
255 # pass if that is the case. In theory it's possible this results
256 # in even more stubs, but unlikely.
257 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
258 # other bugs.
259 # 4) The correct ${kallsymso} is linked into the final vmlinux.
260 #
261 # a) Verify that the System.map from vmlinux matches the map from
262 # ${kallsymso}.
263
264 kallsyms_step 1
265 kallsyms_step 2
266
267 # step 3
268 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev})
269 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
270
271 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
272 kallsyms_step 3
273 fi
274fi
275
276vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o}
277
278# fill in BTF IDs
279if is_enabled CONFIG_DEBUG_INFO_BTF && is_enabled CONFIG_BPF; then
280 info BTFIDS vmlinux
281 ${RESOLVE_BTFIDS} vmlinux
282fi
283
284mksysmap vmlinux System.map
285
286if is_enabled CONFIG_BUILDTIME_TABLE_SORT; then
287 info SORTTAB vmlinux
288 if ! sorttable vmlinux; then
289 echo >&2 Failed to sort kernel tables
290 exit 1
291 fi
292fi
293
294# step a (see comment above)
295if is_enabled CONFIG_KALLSYMS; then
296 if ! cmp -s System.map ${kallsyms_vmlinux}.syms; 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
303# For fixdep
304echo "vmlinux: $0" > .vmlinux.d