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="$3"
  36
  37 # Nice output in kbuild format
  38 # Will be supressed by "make -s"
  39 info()
  40 {
  41         printf "  %-7s %s\n" "${1}" "${2}"
  42 }
  43
  44 # Generate a linker script to ensure correct ordering of initcalls.
  45 gen_initcalls()
  46 {
  47         info GEN .tmp_initcalls.lds
  48
  49         ${PYTHON} ${srctree}/scripts/jobserver-exec             \
  50         ${PERL} ${srctree}/scripts/generate_initcall_order.pl   \
  51                 ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS}   \
  52                 > .tmp_initcalls.lds
  53 }
  54
  55 # If CONFIG_LTO_CLANG is selected, collect generated symbol versions into
  56 # .tmp_symversions.lds
  57 gen_symversions()
  58 {
  59         info GEN .tmp_symversions.lds
  60         rm -f .tmp_symversions.lds
  61
  62         for o in ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS}; do
  63                 if [ -f ${o}.symversions ]; then
  64                         cat ${o}.symversions >> .tmp_symversions.lds
  65                 fi
  66         done
  67 }
  68
  69 # Link of vmlinux.o used for section mismatch analysis
  70 # ${1} output file
  71 modpost_link()
  72 {
  73         local objects
  74         local lds=""
  75
  76         objects="--whole-archive                                \
  77                 ${KBUILD_VMLINUX_OBJS}                          \
  78                 --no-whole-archive                              \
  79                 --start-group                                   \
  80                 ${KBUILD_VMLINUX_LIBS}                          \
  81                 --end-group"
  82
  83         if [ -n "${CONFIG_LTO_CLANG}" ]; then
  84                 gen_initcalls
  85                 lds="-T .tmp_initcalls.lds"
  86
  87                 if [ -n "${CONFIG_MODVERSIONS}" ]; then
  88                         gen_symversions
  89                         lds="${lds} -T .tmp_symversions.lds"
  90                 fi
  91
  92                 # This might take a while, so indicate that we're doing
  93                 # an LTO link
  94                 info LTO ${1}
  95         else
  96                 info LD ${1}
  97         fi
  98
  99         ${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${lds} ${objects}
 100 }
 101
 102 objtool_link()
 103 {
 104         local objtoolcmd;
 105         local objtoolopt;
 106
 107         if [ "${CONFIG_LTO_CLANG} ${CONFIG_STACK_VALIDATION}" = "y y" ]; then
 108                 # Don't perform vmlinux validation unless explicitly requested,
 109                 # but run objtool on vmlinux.o now that we have an object file.
 110                 if [ -n "${CONFIG_UNWINDER_ORC}" ]; then
 111                         objtoolcmd="orc generate"
 112                 fi
 113
 114                 objtoolopt="${objtoolopt} --duplicate"
 115
 116                 if [ -n "${CONFIG_FTRACE_MCOUNT_USE_OBJTOOL}" ]; then
 117                         objtoolopt="${objtoolopt} --mcount"
 118                 fi
 119         fi
 120
 121         if [ -n "${CONFIG_VMLINUX_VALIDATION}" ]; then
 122                 objtoolopt="${objtoolopt} --noinstr"
 123         fi
 124
 125         if [ -n "${objtoolopt}" ]; then
 126                 if [ -z "${objtoolcmd}" ]; then
 127                         objtoolcmd="check"
 128                 fi
 129                 objtoolopt="${objtoolopt} --vmlinux"
 130                 if [ -z "${CONFIG_FRAME_POINTER}" ]; then
 131                         objtoolopt="${objtoolopt} --no-fp"
 132                 fi
 133                 if [ -n "${CONFIG_GCOV_KERNEL}" ] || [ -n "${CONFIG_LTO_CLANG}" ]; then
 134                         objtoolopt="${objtoolopt} --no-unreachable"
 135                 fi
 136                 if [ -n "${CONFIG_RETPOLINE}" ]; then
 137                         objtoolopt="${objtoolopt} --retpoline"
 138                 fi
 139                 if [ -n "${CONFIG_X86_SMAP}" ]; then
 140                         objtoolopt="${objtoolopt} --uaccess"
 141                 fi
 142                 info OBJTOOL ${1}
 143                 tools/objtool/objtool ${objtoolcmd} ${objtoolopt} ${1}
 144         fi
 145 }
 146
 147 # Link of vmlinux
 148 # ${1} - output file
 149 # ${2}, ${3}, ... - optional extra .o files
 150 vmlinux_link()
 151 {
 152         local lds="${objtree}/${KBUILD_LDS}"
 153         local output=${1}
 154         local objects
 155         local strip_debug
 156         local map_option
 157         local objs
 158         local libs
 159
 160         info LD ${output}
 161
 162         # skip output file argument
 163         shift
 164
 165         if [ -n "${CONFIG_LTO_CLANG}" ]; then
 166                 # Use vmlinux.o instead of performing the slow LTO link again.
 167                 objs=vmlinux.o
 168                 libs=
 169         else
 170                 objs="${KBUILD_VMLINUX_OBJS}"
 171                 libs="${KBUILD_VMLINUX_LIBS}"
 172         fi
 173
 174         # The kallsyms linking does not need debug symbols included.
 175         if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
 176                 strip_debug=-Wl,--strip-debug
 177         fi
 178
 179         if [ -n "${CONFIG_VMLINUX_MAP}" ]; then
 180                 map_option="-Map=${output}.map"
 181         fi
 182
 183         if [ "${SRCARCH}" != "um" ]; then
 184                 objects="--whole-archive ${objs} --no-whole-archive     \
 185                          --start-group ${libs} --end-group              \
 186                          $@"
 187
 188                 ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}      \
 189                         ${strip_debug#-Wl,}                     \
 190                         -o ${output}                            \
 191                         ${map_option}                           \
 192                         -T ${lds} ${objects}
 193         else
 194                 objects="-Wl,--whole-archive                    \
 195                         ${KBUILD_VMLINUX_OBJS}                  \
 196                         -Wl,--no-whole-archive                  \
 197                         -Wl,--start-group                       \
 198                         ${KBUILD_VMLINUX_LIBS}                  \
 199                         -Wl,--end-group                         \
 200                         ${@}"
 201
 202                 ${CC} ${CFLAGS_vmlinux}                         \
 203                         ${strip_debug}                          \
 204                         -o ${output}                            \
 205                         ${map_option:+-Wl,${map_option}}        \
 206                         -Wl,-T,${lds}                           \
 207                         ${objects}                              \
 208                         -lutil -lrt -lpthread
 209         fi
 210 }
 211
 212 # generate .BTF typeinfo from DWARF debuginfo
 213 # ${1} - vmlinux image
 214 # ${2} - file to dump raw BTF data into
 215 gen_btf()
 216 {
 217         local pahole_ver
 218         local extra_paholeopt=
 219
 220         if ! [ -x "$(command -v ${PAHOLE})" ]; then
 221                 echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available"
 222                 return 1
 223         fi
 224
 225         pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
 226         if [ "${pahole_ver}" -lt "116" ]; then
 227                 echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.16"
 228                 return 1
 229         fi
 230
 231         vmlinux_link ${1}
 232
 233         if [ "${pahole_ver}" -ge "118" ] && [ "${pahole_ver}" -le "121" ]; then
 234                 # pahole 1.18 through 1.21 can't handle zero-sized per-CPU vars
 235                 extra_paholeopt="${extra_paholeopt} --skip_encoding_btf_vars"
 236         fi
 237         if [ "${pahole_ver}" -ge "121" ]; then
 238                 extra_paholeopt="${extra_paholeopt} --btf_gen_floats"
 239         fi
 240
 241         info "BTF" ${2}
 242         LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${extra_paholeopt} ${1}
 243
 244         # Create ${2} which contains just .BTF section but no symbols. Add
 245         # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all
 246         # deletes all symbols including __start_BTF and __stop_BTF, which will
 247         # be redefined in the linker script. Add 2>/dev/null to suppress GNU
 248         # objcopy warnings: "empty loadable segment detected at ..."
 249         ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \
 250                 --strip-all ${1} ${2} 2>/dev/null
 251         # Change e_type to ET_REL so that it can be used to link final vmlinux.
 252         # Unlike GNU ld, lld does not allow an ET_EXEC input.
 253         printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none
 254 }
 255
 256 # Create ${2} .S file with all symbols from the ${1} object file
 257 kallsyms()
 258 {
 259         local kallsymopt;
 260
 261         if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
 262                 kallsymopt="${kallsymopt} --all-symbols"
 263         fi
 264
 265         if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
 266                 kallsymopt="${kallsymopt} --absolute-percpu"
 267         fi
 268
 269         if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then
 270                 kallsymopt="${kallsymopt} --base-relative"
 271         fi
 272
 273         info KSYMS ${2}
 274         ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${2}
 275 }
 276
 277 # Perform one step in kallsyms generation, including temporary linking of
 278 # vmlinux.
 279 kallsyms_step()
 280 {
 281         kallsymso_prev=${kallsymso}
 282         kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1}
 283         kallsymso=${kallsyms_vmlinux}.o
 284         kallsyms_S=${kallsyms_vmlinux}.S
 285
 286         vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o}
 287         kallsyms ${kallsyms_vmlinux} ${kallsyms_S}
 288
 289         info AS ${kallsyms_S}
 290         ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \
 291               ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \
 292               -c -o ${kallsymso} ${kallsyms_S}
 293 }
 294
 295 # Create map file with all symbols from ${1}
 296 # See mksymap for additional details
 297 mksysmap()
 298 {
 299         ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
 300 }
 301
 302 sorttable()
 303 {
 304         ${objtree}/scripts/sorttable ${1}
 305 }
 306
 307 # Delete output files in case of error
 308 cleanup()
 309 {
 310         rm -f .btf.*
 311         rm -f .tmp_System.map
 312         rm -f .tmp_initcalls.lds
 313         rm -f .tmp_symversions.lds
 314         rm -f .tmp_vmlinux*
 315         rm -f System.map
 316         rm -f vmlinux
 317         rm -f vmlinux.map
 318         rm -f vmlinux.o
 319         rm -f .vmlinux.d
 320 }
 321
 322 # Use "make V=1" to debug this script
 323 case "${KBUILD_VERBOSE}" in
 324 *1*)
 325         set -x
 326         ;;
 327 esac
 328
 329 if [ "$1" = "clean" ]; then
 330         cleanup
 331         exit 0
 332 fi
 333
 334 # We need access to CONFIG_ symbols
 335 . include/config/auto.conf
 336
 337 # Update version
 338 info GEN .version
 339 if [ -r .version ]; then
 340         VERSION=$(expr 0$(cat .version) + 1)
 341         echo $VERSION > .version
 342 else
 343         rm -f .version
 344         echo 1 > .version
 345 fi;
 346
 347 # final build of init/
 348 ${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1
 349
 350 #link vmlinux.o
 351 modpost_link vmlinux.o
 352 objtool_link vmlinux.o
 353
 354 # modpost vmlinux.o to check for section mismatches
 355 ${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1
 356
 357 info MODINFO modules.builtin.modinfo
 358 ${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo
 359 info GEN modules.builtin
 360 # The second line aids cases where multiple modules share the same object.
 361 tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' |
 362         tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin
 363
 364 btf_vmlinux_bin_o=""
 365 if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then
 366         btf_vmlinux_bin_o=.btf.vmlinux.bin.o
 367         if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then
 368                 echo >&2 "Failed to generate BTF for vmlinux"
 369                 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF"
 370                 exit 1
 371         fi
 372 fi
 373
 374 kallsymso=""
 375 kallsymso_prev=""
 376 kallsyms_vmlinux=""
 377 if [ -n "${CONFIG_KALLSYMS}" ]; then
 378
 379         # kallsyms support
 380         # Generate section listing all symbols and add it into vmlinux
 381         # It's a three step process:
 382         # 1)  Link .tmp_vmlinux1 so it has all symbols and sections,
 383         #     but __kallsyms is empty.
 384         #     Running kallsyms on that gives us .tmp_kallsyms1.o with
 385         #     the right size
 386         # 2)  Link .tmp_vmlinux2 so it now has a __kallsyms section of
 387         #     the right size, but due to the added section, some
 388         #     addresses have shifted.
 389         #     From here, we generate a correct .tmp_kallsyms2.o
 390         # 3)  That link may have expanded the kernel image enough that
 391         #     more linker branch stubs / trampolines had to be added, which
 392         #     introduces new names, which further expands kallsyms. Do another
 393         #     pass if that is the case. In theory it's possible this results
 394         #     in even more stubs, but unlikely.
 395         #     KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
 396         #     other bugs.
 397         # 4)  The correct ${kallsymso} is linked into the final vmlinux.
 398         #
 399         # a)  Verify that the System.map from vmlinux matches the map from
 400         #     ${kallsymso}.
 401
 402         kallsyms_step 1
 403         kallsyms_step 2
 404
 405         # step 3
 406         size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev})
 407         size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
 408
 409         if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
 410                 kallsyms_step 3
 411         fi
 412 fi
 413
 414 vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o}
 415
 416 # fill in BTF IDs
 417 if [ -n "${CONFIG_DEBUG_INFO_BTF}" -a -n "${CONFIG_BPF}" ]; then
 418         info BTFIDS vmlinux
 419         ${RESOLVE_BTFIDS} vmlinux
 420 fi
 421
 422 if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then
 423         info SORTTAB vmlinux
 424         if ! sorttable vmlinux; then
 425                 echo >&2 Failed to sort kernel tables
 426                 exit 1
 427         fi
 428 fi
 429
 430 info SYSMAP System.map
 431 mksysmap vmlinux System.map
 432
 433 # step a (see comment above)
 434 if [ -n "${CONFIG_KALLSYMS}" ]; then
 435         mksysmap ${kallsyms_vmlinux} .tmp_System.map
 436
 437         if ! cmp -s System.map .tmp_System.map; then
 438                 echo >&2 Inconsistent kallsyms data
 439                 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
 440                 exit 1
 441         fi
 442 fi
 443
 444 # For fixdep
 445 echo "vmlinux: $0" > .vmlinux.d