Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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# ${1} - output file
48vmlinux_link()
49{
50 local output=${1}
51 local objs
52 local libs
53 local ld
54 local ldflags
55 local ldlibs
56
57 info LD ${output}
58
59 # skip output file argument
60 shift
61
62 if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then
63 # Use vmlinux.o instead of performing the slow LTO link again.
64 objs=vmlinux.o
65 libs=
66 else
67 objs=vmlinux.a
68 libs="${KBUILD_VMLINUX_LIBS}"
69 fi
70
71 if is_enabled CONFIG_MODULES; then
72 objs="${objs} .vmlinux.export.o"
73 fi
74
75 objs="${objs} init/version-timestamp.o"
76
77 if [ "${SRCARCH}" = "um" ]; then
78 wl=-Wl,
79 ld="${CC}"
80 ldflags="${CFLAGS_vmlinux}"
81 ldlibs="-lutil -lrt -lpthread"
82 else
83 wl=
84 ld="${LD}"
85 ldflags="${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}"
86 ldlibs=
87 fi
88
89 ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}"
90
91 # The kallsyms linking does not need debug symbols included.
92 if [ -n "${strip_debug}" ] ; then
93 ldflags="${ldflags} ${wl}--strip-debug"
94 fi
95
96 if is_enabled CONFIG_VMLINUX_MAP; then
97 ldflags="${ldflags} ${wl}-Map=${output}.map"
98 fi
99
100 ${ld} ${ldflags} -o ${output} \
101 ${wl}--whole-archive ${objs} ${wl}--no-whole-archive \
102 ${wl}--start-group ${libs} ${wl}--end-group \
103 ${kallsymso} ${btf_vmlinux_bin_o} ${ldlibs}
104}
105
106# generate .BTF typeinfo from DWARF debuginfo
107# ${1} - vmlinux image
108gen_btf()
109{
110 local pahole_ver
111 local btf_data=${1}.btf.o
112
113 if ! [ -x "$(command -v ${PAHOLE})" ]; then
114 echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available"
115 return 1
116 fi
117
118 pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
119 if [ "${pahole_ver}" -lt "116" ]; then
120 echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.16"
121 return 1
122 fi
123
124 info BTF "${btf_data}"
125 LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1}
126
127 # Create ${btf_data} which contains just .BTF section but no symbols. Add
128 # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all
129 # deletes all symbols including __start_BTF and __stop_BTF, which will
130 # be redefined in the linker script. Add 2>/dev/null to suppress GNU
131 # objcopy warnings: "empty loadable segment detected at ..."
132 ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \
133 --strip-all ${1} "${btf_data}" 2>/dev/null
134 # Change e_type to ET_REL so that it can be used to link final vmlinux.
135 # GNU ld 2.35+ and lld do not allow an ET_EXEC input.
136 if is_enabled CONFIG_CPU_BIG_ENDIAN; then
137 et_rel='\0\1'
138 else
139 et_rel='\1\0'
140 fi
141 printf "${et_rel}" | dd of="${btf_data}" conv=notrunc bs=1 seek=16 status=none
142
143 btf_vmlinux_bin_o=${btf_data}
144}
145
146# Create ${2}.o file with all symbols from the ${1} object file
147kallsyms()
148{
149 local kallsymopt;
150
151 if is_enabled CONFIG_KALLSYMS_ALL; then
152 kallsymopt="${kallsymopt} --all-symbols"
153 fi
154
155 if is_enabled CONFIG_KALLSYMS_ABSOLUTE_PERCPU; then
156 kallsymopt="${kallsymopt} --absolute-percpu"
157 fi
158
159 if is_enabled CONFIG_LTO_CLANG; then
160 kallsymopt="${kallsymopt} --lto-clang"
161 fi
162
163 info KSYMS "${2}.S"
164 scripts/kallsyms ${kallsymopt} "${1}" > "${2}.S"
165
166 info AS "${2}.o"
167 ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \
168 ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} -c -o "${2}.o" "${2}.S"
169
170 kallsymso=${2}.o
171}
172
173# Perform kallsyms for the given temporary vmlinux.
174sysmap_and_kallsyms()
175{
176 mksysmap "${1}" "${1}.syms"
177 kallsyms "${1}.syms" "${1}.kallsyms"
178
179 kallsyms_sysmap=${1}.syms
180}
181
182# Create map file with all symbols from ${1}
183# See mksymap for additional details
184mksysmap()
185{
186 info NM ${2}
187 ${NM} -n "${1}" | sed -f "${srctree}/scripts/mksysmap" > "${2}"
188}
189
190sorttable()
191{
192 ${objtree}/scripts/sorttable ${1}
193}
194
195cleanup()
196{
197 rm -f .btf.*
198 rm -f System.map
199 rm -f vmlinux
200 rm -f vmlinux.map
201}
202
203# Use "make V=1" to debug this script
204case "${KBUILD_VERBOSE}" in
205*1*)
206 set -x
207 ;;
208esac
209
210if [ "$1" = "clean" ]; then
211 cleanup
212 exit 0
213fi
214
215${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init init/version-timestamp.o
216
217btf_vmlinux_bin_o=
218kallsymso=
219strip_debug=
220
221if is_enabled CONFIG_KALLSYMS; then
222 kallsyms /dev/null .tmp_vmlinux0.kallsyms
223fi
224
225if is_enabled CONFIG_KALLSYMS || is_enabled CONFIG_DEBUG_INFO_BTF; then
226
227 # The kallsyms linking does not need debug symbols, but the BTF does.
228 if ! is_enabled CONFIG_DEBUG_INFO_BTF; then
229 strip_debug=1
230 fi
231
232 vmlinux_link .tmp_vmlinux1
233fi
234
235if is_enabled CONFIG_DEBUG_INFO_BTF; then
236 if ! gen_btf .tmp_vmlinux1; then
237 echo >&2 "Failed to generate BTF for vmlinux"
238 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF"
239 exit 1
240 fi
241fi
242
243if is_enabled CONFIG_KALLSYMS; then
244
245 # kallsyms support
246 # Generate section listing all symbols and add it into vmlinux
247 # It's a four step process:
248 # 0) Generate a dummy __kallsyms with empty symbol list.
249 # 1) Link .tmp_vmlinux.kallsyms1 so it has all symbols and sections,
250 # with a dummy __kallsyms.
251 # Running kallsyms on that gives us .tmp_kallsyms1.o with
252 # the right size
253 # 2) Link .tmp_vmlinux.kallsyms2 so it now has a __kallsyms section of
254 # the right size, but due to the added section, some
255 # addresses have shifted.
256 # From here, we generate a correct .tmp_vmlinux.kallsyms2.o
257 # 3) That link may have expanded the kernel image enough that
258 # more linker branch stubs / trampolines had to be added, which
259 # introduces new names, which further expands kallsyms. Do another
260 # pass if that is the case. In theory it's possible this results
261 # in even more stubs, but unlikely.
262 # KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
263 # other bugs.
264 # 4) The correct ${kallsymso} is linked into the final vmlinux.
265 #
266 # a) Verify that the System.map from vmlinux matches the map from
267 # ${kallsymso}.
268
269 # The kallsyms linking does not need debug symbols included.
270 strip_debug=1
271
272 sysmap_and_kallsyms .tmp_vmlinux1
273 size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
274
275 vmlinux_link .tmp_vmlinux2
276 sysmap_and_kallsyms .tmp_vmlinux2
277 size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
278
279 if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
280 vmlinux_link .tmp_vmlinux3
281 sysmap_and_kallsyms .tmp_vmlinux3
282 fi
283fi
284
285strip_debug=
286
287vmlinux_link vmlinux
288
289# fill in BTF IDs
290if is_enabled CONFIG_DEBUG_INFO_BTF && is_enabled CONFIG_BPF; then
291 info BTFIDS vmlinux
292 ${RESOLVE_BTFIDS} vmlinux
293fi
294
295mksysmap vmlinux System.map
296
297if is_enabled CONFIG_BUILDTIME_TABLE_SORT; then
298 info SORTTAB vmlinux
299 if ! sorttable vmlinux; then
300 echo >&2 Failed to sort kernel tables
301 exit 1
302 fi
303fi
304
305# step a (see comment above)
306if is_enabled CONFIG_KALLSYMS; then
307 if ! cmp -s System.map "${kallsyms_sysmap}"; then
308 echo >&2 Inconsistent kallsyms data
309 echo >&2 'Try "make KALLSYMS_EXTRA_PASS=1" as a workaround'
310 exit 1
311 fi
312fi
313
314# For fixdep
315echo "vmlinux: $0" > .vmlinux.d