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