scripts/link-vmlinux.sh

   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 #   +-< ${kallsymso} (see description in KALLSYMS section)
  22 #
  23 # vmlinux version (uname -v) cannot be updated during normal
  24 # descending-into-subdirs phase since we do not yet know if we need to
  25 # update vmlinux.
  26 # Therefore this step is delayed until just before final link of vmlinux.
  27 #
  28 # System.map is generated to document addresses of all kernel symbols
  29
  30 # Error out on error
  31 set -e
  32
  33 # Nice output in kbuild format
  34 # Will be supressed by "make -s"
  35 info()
  36 {
  37         if [ "${quiet}" != "silent_" ]; then
  38                 printf "  %-7s %s\n" "${1}" "${2}"
  39         fi
  40 }
  41
  42 # Link of vmlinux.o used for section mismatch analysis
  43 # ${1} output file
  44 modpost_link()
  45 {
  46         local objects
  47
  48         objects="--whole-archive                                \
  49                 ${KBUILD_VMLINUX_OBJS}                          \
  50                 --no-whole-archive                              \
  51                 --start-group                                   \
  52                 ${KBUILD_VMLINUX_LIBS}                          \
  53                 --end-group"
  54
  55         ${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${objects}
  56 }
  57
  58 # Link of vmlinux
  59 # ${1} - output file
  60 # ${2}, ${3}, ... - optional extra .o files
  61 vmlinux_link()
  62 {
  63         local lds="${objtree}/${KBUILD_LDS}"
  64         local output=${1}
  65         local objects
  66
  67         # skip output file argument
  68         shift
  69
  70         if [ "${SRCARCH}" != "um" ]; then
  71                 objects="--whole-archive                        \
  72                         ${KBUILD_VMLINUX_OBJS}                  \
  73                         --no-whole-archive                      \
  74                         --start-group                           \
  75                         ${KBUILD_VMLINUX_LIBS}                  \
  76                         --end-group                             \
  77                         ${@}"
  78
  79                 ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}      \
  80                         -o ${output}                            \
  81                         -T ${lds} ${objects}
  82         else
  83                 objects="-Wl,--whole-archive                    \
  84                         ${KBUILD_VMLINUX_OBJS}                  \
  85                         -Wl,--no-whole-archive                  \
  86                         -Wl,--start-group                       \
  87                         ${KBUILD_VMLINUX_LIBS}                  \
  88                         -Wl,--end-group                         \
  89                         ${@}"
  90
  91                 ${CC} ${CFLAGS_vmlinux}                         \
  92                         -o ${output}                            \
  93                         -Wl,-T,${lds}                           \
  94                         ${objects}                              \
  95                         -lutil -lrt -lpthread
  96                 rm -f linux
  97         fi
  98 }
  99
 100 # generate .BTF typeinfo from DWARF debuginfo
 101 # ${1} - vmlinux image
 102 # ${2} - file to dump raw BTF data into
 103 gen_btf()
 104 {
 105         local pahole_ver
 106         local bin_arch
 107
 108         if ! [ -x "$(command -v ${PAHOLE})" ]; then
 109                 info "BTF" "${1}: pahole (${PAHOLE}) is not available"
 110                 return 1
 111         fi
 112
 113         pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
 114         if [ "${pahole_ver}" -lt "113" ]; then
 115                 info "BTF" "${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.13"
 116                 return 1
 117         fi
 118
 119         info "BTF" ${2}
 120         vmlinux_link ${1}
 121         LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1}
 122
 123         # dump .BTF section into raw binary file to link with final vmlinux
 124         bin_arch=$(LANG=C ${OBJDUMP} -f ${1} | grep architecture | \
 125                 cut -d, -f1 | cut -d' ' -f2)
 126         bin_format=$(LANG=C ${OBJDUMP} -f ${1} | grep 'file format' | \
 127                 awk '{print $4}')
 128         ${OBJCOPY} --dump-section .BTF=.btf.vmlinux.bin ${1} 2>/dev/null
 129         ${OBJCOPY} -I binary -O ${bin_format} -B ${bin_arch} \
 130                 --rename-section .data=.BTF .btf.vmlinux.bin ${2}
 131 }
 132
 133 # Create ${2} .o file with all symbols from the ${1} object file
 134 kallsyms()
 135 {
 136         info KSYM ${2}
 137         local kallsymopt;
 138
 139         if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
 140                 kallsymopt="${kallsymopt} --all-symbols"
 141         fi
 142
 143         if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
 144                 kallsymopt="${kallsymopt} --absolute-percpu"
 145         fi
 146
 147         if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then
 148                 kallsymopt="${kallsymopt} --base-relative"
 149         fi
 150
 151         local aflags="${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL}               \
 152                       ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS}"
 153
 154         local afile="`basename ${2} .o`.S"
 155
 156         ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${afile}
 157         ${CC} ${aflags} -c -o ${2} ${afile}
 158 }
 159
 160 # Create map file with all symbols from ${1}
 161 # See mksymap for additional details
 162 mksysmap()
 163 {
 164         ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
 165 }
 166
 167 sortextable()
 168 {
 169         ${objtree}/scripts/sortextable ${1}
 170 }
 171
 172 # Delete output files in case of error
 173 cleanup()
 174 {
 175         rm -f .btf.*
 176         rm -f .tmp_System.map
 177         rm -f .tmp_kallsyms*
 178         rm -f .tmp_vmlinux*
 179         rm -f System.map
 180         rm -f vmlinux
 181         rm -f vmlinux.o
 182 }
 183
 184 on_exit()
 185 {
 186         if [ $? -ne 0 ]; then
 187                 cleanup
 188         fi
 189 }
 190 trap on_exit EXIT
 191
 192 on_signals()
 193 {
 194         exit 1
 195 }
 196 trap on_signals HUP INT QUIT TERM
 197
 198 #
 199 #
 200 # Use "make V=1" to debug this script
 201 case "${KBUILD_VERBOSE}" in
 202 *1*)
 203         set -x
 204         ;;
 205 esac
 206
 207 if [ "$1" = "clean" ]; then
 208         cleanup
 209         exit 0
 210 fi
 211
 212 # We need access to CONFIG_ symbols
 213 . include/config/auto.conf
 214
 215 # Update version
 216 info GEN .version
 217 if [ -r .version ]; then
 218         VERSION=$(expr 0$(cat .version) + 1)
 219         echo $VERSION > .version
 220 else
 221         rm -f .version
 222         echo 1 > .version
 223 fi;
 224
 225 # final build of init/
 226 ${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init
 227
 228 #link vmlinux.o
 229 info LD vmlinux.o
 230 modpost_link vmlinux.o
 231
 232 # modpost vmlinux.o to check for section mismatches
 233 ${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1
 234
 235 info MODINFO modules.builtin.modinfo
 236 ${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo
 237
 238 btf_vmlinux_bin_o=""
 239 if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then
 240         if gen_btf .tmp_vmlinux.btf .btf.vmlinux.bin.o ; then
 241                 btf_vmlinux_bin_o=.btf.vmlinux.bin.o
 242         fi
 243 fi
 244
 245 kallsymso=""
 246 kallsyms_vmlinux=""
 247 if [ -n "${CONFIG_KALLSYMS}" ]; then
 248
 249         # kallsyms support
 250         # Generate section listing all symbols and add it into vmlinux
 251         # It's a three step process:
 252         # 1)  Link .tmp_vmlinux1 so it has all symbols and sections,
 253         #     but __kallsyms is empty.
 254         #     Running kallsyms on that gives us .tmp_kallsyms1.o with
 255         #     the right size
 256         # 2)  Link .tmp_vmlinux2 so it now has a __kallsyms section of
 257         #     the right size, but due to the added section, some
 258         #     addresses have shifted.
 259         #     From here, we generate a correct .tmp_kallsyms2.o
 260         # 3)  That link may have expanded the kernel image enough that
 261         #     more linker branch stubs / trampolines had to be added, which
 262         #     introduces new names, which further expands kallsyms. Do another
 263         #     pass if that is the case. In theory it's possible this results
 264         #     in even more stubs, but unlikely.
 265         #     KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
 266         #     other bugs.
 267         # 4)  The correct ${kallsymso} is linked into the final vmlinux.
 268         #
 269         # a)  Verify that the System.map from vmlinux matches the map from
 270         #     ${kallsymso}.
 271
 272         kallsymso=.tmp_kallsyms2.o
 273         kallsyms_vmlinux=.tmp_vmlinux2
 274
 275         # step 1
 276         vmlinux_link .tmp_vmlinux1 ${btf_vmlinux_bin_o}
 277         kallsyms .tmp_vmlinux1 .tmp_kallsyms1.o
 278
 279         # step 2
 280         vmlinux_link .tmp_vmlinux2 .tmp_kallsyms1.o ${btf_vmlinux_bin_o}
 281         kallsyms .tmp_vmlinux2 .tmp_kallsyms2.o
 282
 283         # step 3
 284         size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" .tmp_kallsyms1.o)
 285         size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" .tmp_kallsyms2.o)
 286
 287         if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
 288                 kallsymso=.tmp_kallsyms3.o
 289                 kallsyms_vmlinux=.tmp_vmlinux3
 290
 291                 vmlinux_link .tmp_vmlinux3 .tmp_kallsyms2.o ${btf_vmlinux_bin_o}
 292                 kallsyms .tmp_vmlinux3 .tmp_kallsyms3.o
 293         fi
 294 fi
 295
 296 info LD vmlinux
 297 vmlinux_link vmlinux "${kallsymso}" "${btf_vmlinux_bin_o}"
 298
 299 if [ -n "${CONFIG_BUILDTIME_EXTABLE_SORT}" ]; then
 300         info SORTEX vmlinux
 301         sortextable vmlinux
 302 fi
 303
 304 info SYSMAP System.map
 305 mksysmap vmlinux System.map
 306
 307 # step a (see comment above)
 308 if [ -n "${CONFIG_KALLSYMS}" ]; then
 309         mksysmap ${kallsyms_vmlinux} .tmp_System.map
 310
 311         if ! cmp -s System.map .tmp_System.map; then
 312                 echo >&2 Inconsistent kallsyms data
 313                 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
 314                 exit 1
 315         fi
 316 fi