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
 158         info LD ${output}
 159
 160         # skip output file argument
 161         shift
 162
 163         # The kallsyms linking does not need debug symbols included.
 164         if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
 165                 strip_debug=-Wl,--strip-debug
 166         fi
 167
 168         if [ -n "${CONFIG_VMLINUX_MAP}" ]; then
 169                 map_option="-Map=${output}.map"
 170         fi
 171
 172         if [ "${SRCARCH}" != "um" ]; then
 173                 if [ -n "${CONFIG_LTO_CLANG}" ]; then
 174                         # Use vmlinux.o instead of performing the slow LTO
 175                         # link again.
 176                         objects="--whole-archive                \
 177                                 vmlinux.o                       \
 178                                 --no-whole-archive              \
 179                                 ${@}"
 180                 else
 181                         objects="--whole-archive                \
 182                                 ${KBUILD_VMLINUX_OBJS}          \
 183                                 --no-whole-archive              \
 184                                 --start-group                   \
 185                                 ${KBUILD_VMLINUX_LIBS}          \
 186                                 --end-group                     \
 187                                 ${@}"
 188                 fi
 189
 190                 ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}      \
 191                         ${strip_debug#-Wl,}                     \
 192                         -o ${output}                            \
 193                         ${map_option}                           \
 194                         -T ${lds} ${objects}
 195         else
 196                 objects="-Wl,--whole-archive                    \
 197                         ${KBUILD_VMLINUX_OBJS}                  \
 198                         -Wl,--no-whole-archive                  \
 199                         -Wl,--start-group                       \
 200                         ${KBUILD_VMLINUX_LIBS}                  \
 201                         -Wl,--end-group                         \
 202                         ${@}"
 203
 204                 ${CC} ${CFLAGS_vmlinux}                         \
 205                         ${strip_debug}                          \
 206                         -o ${output}                            \
 207                         ${map_option:+-Wl,${map_option}}        \
 208                         -Wl,-T,${lds}                           \
 209                         ${objects}                              \
 210                         -lutil -lrt -lpthread
 211                 rm -f linux
 212         fi
 213 }
 214
 215 # generate .BTF typeinfo from DWARF debuginfo
 216 # ${1} - vmlinux image
 217 # ${2} - file to dump raw BTF data into
 218 gen_btf()
 219 {
 220         local pahole_ver
 221         local extra_paholeopt=
 222
 223         if ! [ -x "$(command -v ${PAHOLE})" ]; then
 224                 echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available"
 225                 return 1
 226         fi
 227
 228         pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
 229         if [ "${pahole_ver}" -lt "116" ]; then
 230                 echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.16"
 231                 return 1
 232         fi
 233
 234         vmlinux_link ${1}
 235
 236         if [ "${pahole_ver}" -ge "118" ] && [ "${pahole_ver}" -le "121" ]; then
 237                 # pahole 1.18 through 1.21 can't handle zero-sized per-CPU vars
 238                 extra_paholeopt="${extra_paholeopt} --skip_encoding_btf_vars"
 239         fi
 240         if [ "${pahole_ver}" -ge "121" ]; then
 241                 extra_paholeopt="${extra_paholeopt} --btf_gen_floats"
 242         fi
 243
 244         info "BTF" ${2}
 245         LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${extra_paholeopt} ${1}
 246
 247         # Create ${2} which contains just .BTF section but no symbols. Add
 248         # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all
 249         # deletes all symbols including __start_BTF and __stop_BTF, which will
 250         # be redefined in the linker script. Add 2>/dev/null to suppress GNU
 251         # objcopy warnings: "empty loadable segment detected at ..."
 252         ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \
 253                 --strip-all ${1} ${2} 2>/dev/null
 254         # Change e_type to ET_REL so that it can be used to link final vmlinux.
 255         # Unlike GNU ld, lld does not allow an ET_EXEC input.
 256         printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none
 257 }
 258
 259 # Create ${2} .S file with all symbols from the ${1} object file
 260 kallsyms()
 261 {
 262         local kallsymopt;
 263
 264         if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
 265                 kallsymopt="${kallsymopt} --all-symbols"
 266         fi
 267
 268         if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
 269                 kallsymopt="${kallsymopt} --absolute-percpu"
 270         fi
 271
 272         if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then
 273                 kallsymopt="${kallsymopt} --base-relative"
 274         fi
 275
 276         info KSYMS ${2}
 277         ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${2}
 278 }
 279
 280 # Perform one step in kallsyms generation, including temporary linking of
 281 # vmlinux.
 282 kallsyms_step()
 283 {
 284         kallsymso_prev=${kallsymso}
 285         kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1}
 286         kallsymso=${kallsyms_vmlinux}.o
 287         kallsyms_S=${kallsyms_vmlinux}.S
 288
 289         vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o}
 290         kallsyms ${kallsyms_vmlinux} ${kallsyms_S}
 291
 292         info AS ${kallsyms_S}
 293         ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \
 294               ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \
 295               -c -o ${kallsymso} ${kallsyms_S}
 296 }
 297
 298 # Create map file with all symbols from ${1}
 299 # See mksymap for additional details
 300 mksysmap()
 301 {
 302         ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
 303 }
 304
 305 sorttable()
 306 {
 307         ${objtree}/scripts/sorttable ${1}
 308 }
 309
 310 # Delete output files in case of error
 311 cleanup()
 312 {
 313         rm -f .btf.*
 314         rm -f .tmp_System.map
 315         rm -f .tmp_initcalls.lds
 316         rm -f .tmp_symversions.lds
 317         rm -f .tmp_vmlinux*
 318         rm -f System.map
 319         rm -f vmlinux
 320         rm -f vmlinux.map
 321         rm -f vmlinux.o
 322         rm -f .vmlinux.d
 323 }
 324
 325 # Use "make V=1" to debug this script
 326 case "${KBUILD_VERBOSE}" in
 327 *1*)
 328         set -x
 329         ;;
 330 esac
 331
 332 if [ "$1" = "clean" ]; then
 333         cleanup
 334         exit 0
 335 fi
 336
 337 # We need access to CONFIG_ symbols
 338 . include/config/auto.conf
 339
 340 # Update version
 341 info GEN .version
 342 if [ -r .version ]; then
 343         VERSION=$(expr 0$(cat .version) + 1)
 344         echo $VERSION > .version
 345 else
 346         rm -f .version
 347         echo 1 > .version
 348 fi;
 349
 350 # final build of init/
 351 ${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1
 352
 353 #link vmlinux.o
 354 modpost_link vmlinux.o
 355 objtool_link vmlinux.o
 356
 357 # modpost vmlinux.o to check for section mismatches
 358 ${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1
 359
 360 info MODINFO modules.builtin.modinfo
 361 ${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo
 362 info GEN modules.builtin
 363 # The second line aids cases where multiple modules share the same object.
 364 tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' |
 365         tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin
 366
 367 btf_vmlinux_bin_o=""
 368 if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then
 369         btf_vmlinux_bin_o=.btf.vmlinux.bin.o
 370         if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then
 371                 echo >&2 "Failed to generate BTF for vmlinux"
 372                 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF"
 373                 exit 1
 374         fi
 375 fi
 376
 377 kallsymso=""
 378 kallsymso_prev=""
 379 kallsyms_vmlinux=""
 380 if [ -n "${CONFIG_KALLSYMS}" ]; then
 381
 382         # kallsyms support
 383         # Generate section listing all symbols and add it into vmlinux
 384         # It's a three step process:
 385         # 1)  Link .tmp_vmlinux1 so it has all symbols and sections,
 386         #     but __kallsyms is empty.
 387         #     Running kallsyms on that gives us .tmp_kallsyms1.o with
 388         #     the right size
 389         # 2)  Link .tmp_vmlinux2 so it now has a __kallsyms section of
 390         #     the right size, but due to the added section, some
 391         #     addresses have shifted.
 392         #     From here, we generate a correct .tmp_kallsyms2.o
 393         # 3)  That link may have expanded the kernel image enough that
 394         #     more linker branch stubs / trampolines had to be added, which
 395         #     introduces new names, which further expands kallsyms. Do another
 396         #     pass if that is the case. In theory it's possible this results
 397         #     in even more stubs, but unlikely.
 398         #     KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
 399         #     other bugs.
 400         # 4)  The correct ${kallsymso} is linked into the final vmlinux.
 401         #
 402         # a)  Verify that the System.map from vmlinux matches the map from
 403         #     ${kallsymso}.
 404
 405         kallsyms_step 1
 406         kallsyms_step 2
 407
 408         # step 3
 409         size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev})
 410         size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
 411
 412         if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
 413                 kallsyms_step 3
 414         fi
 415 fi
 416
 417 vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o}
 418
 419 # fill in BTF IDs
 420 if [ -n "${CONFIG_DEBUG_INFO_BTF}" -a -n "${CONFIG_BPF}" ]; then
 421         info BTFIDS vmlinux
 422         ${RESOLVE_BTFIDS} vmlinux
 423 fi
 424
 425 if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then
 426         info SORTTAB vmlinux
 427         if ! sorttable vmlinux; then
 428                 echo >&2 Failed to sort kernel tables
 429                 exit 1
 430         fi
 431 fi
 432
 433 info SYSMAP System.map
 434 mksysmap vmlinux System.map
 435
 436 # step a (see comment above)
 437 if [ -n "${CONFIG_KALLSYMS}" ]; then
 438         mksysmap ${kallsyms_vmlinux} .tmp_System.map
 439
 440         if ! cmp -s System.map .tmp_System.map; then
 441                 echo >&2 Inconsistent kallsyms data
 442                 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
 443                 exit 1
 444         fi
 445 fi
 446
 447 # For fixdep
 448 echo "vmlinux: $0" > .vmlinux.d