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 # Generate a linker script to ensure correct ordering of initcalls.
  47 gen_initcalls()
  48 {
  49         info GEN .tmp_initcalls.lds
  50
  51         ${PYTHON} ${srctree}/scripts/jobserver-exec             \
  52         ${PERL} ${srctree}/scripts/generate_initcall_order.pl   \
  53                 ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS}   \
  54                 > .tmp_initcalls.lds
  55 }
  56
  57 # If CONFIG_LTO_CLANG is selected, collect generated symbol versions into
  58 # .tmp_symversions.lds
  59 gen_symversions()
  60 {
  61         info GEN .tmp_symversions.lds
  62         rm -f .tmp_symversions.lds
  63
  64         for o in ${KBUILD_VMLINUX_OBJS} ${KBUILD_VMLINUX_LIBS}; do
  65                 if [ -f ${o}.symversions ]; then
  66                         cat ${o}.symversions >> .tmp_symversions.lds
  67                 fi
  68         done
  69 }
  70
  71 # Link of vmlinux.o used for section mismatch analysis
  72 # ${1} output file
  73 modpost_link()
  74 {
  75         local objects
  76         local lds=""
  77
  78         objects="--whole-archive                                \
  79                 ${KBUILD_VMLINUX_OBJS}                          \
  80                 --no-whole-archive                              \
  81                 --start-group                                   \
  82                 ${KBUILD_VMLINUX_LIBS}                          \
  83                 --end-group"
  84
  85         if [ -n "${CONFIG_LTO_CLANG}" ]; then
  86                 gen_initcalls
  87                 lds="-T .tmp_initcalls.lds"
  88
  89                 if [ -n "${CONFIG_MODVERSIONS}" ]; then
  90                         gen_symversions
  91                         lds="${lds} -T .tmp_symversions.lds"
  92                 fi
  93
  94                 # This might take a while, so indicate that we're doing
  95                 # an LTO link
  96                 info LTO ${1}
  97         else
  98                 info LD ${1}
  99         fi
 100
 101         ${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${lds} ${objects}
 102 }
 103
 104 objtool_link()
 105 {
 106         local objtoolcmd;
 107         local objtoolopt;
 108
 109         if [ "${CONFIG_LTO_CLANG} ${CONFIG_STACK_VALIDATION}" = "y y" ]; then
 110                 # Don't perform vmlinux validation unless explicitly requested,
 111                 # but run objtool on vmlinux.o now that we have an object file.
 112                 if [ -n "${CONFIG_UNWINDER_ORC}" ]; then
 113                         objtoolcmd="orc generate"
 114                 fi
 115
 116                 objtoolopt="${objtoolopt} --duplicate"
 117
 118                 if [ -n "${CONFIG_FTRACE_MCOUNT_USE_OBJTOOL}" ]; then
 119                         objtoolopt="${objtoolopt} --mcount"
 120                 fi
 121         fi
 122
 123         if [ -n "${CONFIG_VMLINUX_VALIDATION}" ]; then
 124                 objtoolopt="${objtoolopt} --noinstr"
 125         fi
 126
 127         if [ -n "${objtoolopt}" ]; then
 128                 if [ -z "${objtoolcmd}" ]; then
 129                         objtoolcmd="check"
 130                 fi
 131                 objtoolopt="${objtoolopt} --vmlinux"
 132                 if [ -z "${CONFIG_FRAME_POINTER}" ]; then
 133                         objtoolopt="${objtoolopt} --no-fp"
 134                 fi
 135                 if [ -n "${CONFIG_GCOV_KERNEL}" ] || [ -n "${CONFIG_LTO_CLANG}" ]; then
 136                         objtoolopt="${objtoolopt} --no-unreachable"
 137                 fi
 138                 if [ -n "${CONFIG_RETPOLINE}" ]; then
 139                         objtoolopt="${objtoolopt} --retpoline"
 140                 fi
 141                 if [ -n "${CONFIG_X86_SMAP}" ]; then
 142                         objtoolopt="${objtoolopt} --uaccess"
 143                 fi
 144                 info OBJTOOL ${1}
 145                 tools/objtool/objtool ${objtoolcmd} ${objtoolopt} ${1}
 146         fi
 147 }
 148
 149 # Link of vmlinux
 150 # ${1} - output file
 151 # ${2}, ${3}, ... - optional extra .o files
 152 vmlinux_link()
 153 {
 154         local lds="${objtree}/${KBUILD_LDS}"
 155         local output=${1}
 156         local objects
 157         local strip_debug
 158         local map_option
 159
 160         info LD ${output}
 161
 162         # skip output file argument
 163         shift
 164
 165         # The kallsyms linking does not need debug symbols included.
 166         if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
 167                 strip_debug=-Wl,--strip-debug
 168         fi
 169
 170         if [ -n "${CONFIG_VMLINUX_MAP}" ]; then
 171                 map_option="-Map=${output}.map"
 172         fi
 173
 174         if [ "${SRCARCH}" != "um" ]; then
 175                 if [ -n "${CONFIG_LTO_CLANG}" ]; then
 176                         # Use vmlinux.o instead of performing the slow LTO
 177                         # link again.
 178                         objects="--whole-archive                \
 179                                 vmlinux.o                       \
 180                                 --no-whole-archive              \
 181                                 ${@}"
 182                 else
 183                         objects="--whole-archive                \
 184                                 ${KBUILD_VMLINUX_OBJS}          \
 185                                 --no-whole-archive              \
 186                                 --start-group                   \
 187                                 ${KBUILD_VMLINUX_LIBS}          \
 188                                 --end-group                     \
 189                                 ${@}"
 190                 fi
 191
 192                 ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}      \
 193                         ${strip_debug#-Wl,}                     \
 194                         -o ${output}                            \
 195                         ${map_option}                           \
 196                         -T ${lds} ${objects}
 197         else
 198                 objects="-Wl,--whole-archive                    \
 199                         ${KBUILD_VMLINUX_OBJS}                  \
 200                         -Wl,--no-whole-archive                  \
 201                         -Wl,--start-group                       \
 202                         ${KBUILD_VMLINUX_LIBS}                  \
 203                         -Wl,--end-group                         \
 204                         ${@}"
 205
 206                 ${CC} ${CFLAGS_vmlinux}                         \
 207                         ${strip_debug}                          \
 208                         -o ${output}                            \
 209                         ${map_option:+-Wl,${map_option}}        \
 210                         -Wl,-T,${lds}                           \
 211                         ${objects}                              \
 212                         -lutil -lrt -lpthread
 213                 rm -f linux
 214         fi
 215 }
 216
 217 # generate .BTF typeinfo from DWARF debuginfo
 218 # ${1} - vmlinux image
 219 # ${2} - file to dump raw BTF data into
 220 gen_btf()
 221 {
 222         local pahole_ver
 223         local extra_paholeopt=
 224
 225         if ! [ -x "$(command -v ${PAHOLE})" ]; then
 226                 echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available"
 227                 return 1
 228         fi
 229
 230         pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
 231         if [ "${pahole_ver}" -lt "116" ]; then
 232                 echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.16"
 233                 return 1
 234         fi
 235
 236         vmlinux_link ${1}
 237
 238         if [ "${pahole_ver}" -ge "118" ] && [ "${pahole_ver}" -le "121" ]; then
 239                 # pahole 1.18 through 1.21 can't handle zero-sized per-CPU vars
 240                 extra_paholeopt="${extra_paholeopt} --skip_encoding_btf_vars"
 241         fi
 242         if [ "${pahole_ver}" -ge "121" ]; then
 243                 extra_paholeopt="${extra_paholeopt} --btf_gen_floats"
 244         fi
 245
 246         info "BTF" ${2}
 247         LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${extra_paholeopt} ${1}
 248
 249         # Create ${2} which contains just .BTF section but no symbols. Add
 250         # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all
 251         # deletes all symbols including __start_BTF and __stop_BTF, which will
 252         # be redefined in the linker script. Add 2>/dev/null to suppress GNU
 253         # objcopy warnings: "empty loadable segment detected at ..."
 254         ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \
 255                 --strip-all ${1} ${2} 2>/dev/null
 256         # Change e_type to ET_REL so that it can be used to link final vmlinux.
 257         # Unlike GNU ld, lld does not allow an ET_EXEC input.
 258         printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none
 259 }
 260
 261 # Create ${2} .S file with all symbols from the ${1} object file
 262 kallsyms()
 263 {
 264         local kallsymopt;
 265
 266         if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
 267                 kallsymopt="${kallsymopt} --all-symbols"
 268         fi
 269
 270         if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
 271                 kallsymopt="${kallsymopt} --absolute-percpu"
 272         fi
 273
 274         if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then
 275                 kallsymopt="${kallsymopt} --base-relative"
 276         fi
 277
 278         info KSYMS ${2}
 279         ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${2}
 280 }
 281
 282 # Perform one step in kallsyms generation, including temporary linking of
 283 # vmlinux.
 284 kallsyms_step()
 285 {
 286         kallsymso_prev=${kallsymso}
 287         kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1}
 288         kallsymso=${kallsyms_vmlinux}.o
 289         kallsyms_S=${kallsyms_vmlinux}.S
 290
 291         vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o}
 292         kallsyms ${kallsyms_vmlinux} ${kallsyms_S}
 293
 294         info AS ${kallsyms_S}
 295         ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \
 296               ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \
 297               -c -o ${kallsymso} ${kallsyms_S}
 298 }
 299
 300 # Create map file with all symbols from ${1}
 301 # See mksymap for additional details
 302 mksysmap()
 303 {
 304         ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
 305 }
 306
 307 sorttable()
 308 {
 309         ${objtree}/scripts/sorttable ${1}
 310 }
 311
 312 # Delete output files in case of error
 313 cleanup()
 314 {
 315         rm -f .btf.*
 316         rm -f .tmp_System.map
 317         rm -f .tmp_initcalls.lds
 318         rm -f .tmp_symversions.lds
 319         rm -f .tmp_vmlinux*
 320         rm -f System.map
 321         rm -f vmlinux
 322         rm -f vmlinux.map
 323         rm -f vmlinux.o
 324         rm -f .vmlinux.d
 325 }
 326
 327 # Use "make V=1" to debug this script
 328 case "${KBUILD_VERBOSE}" in
 329 *1*)
 330         set -x
 331         ;;
 332 esac
 333
 334 if [ "$1" = "clean" ]; then
 335         cleanup
 336         exit 0
 337 fi
 338
 339 # We need access to CONFIG_ symbols
 340 . include/config/auto.conf
 341
 342 # Update version
 343 info GEN .version
 344 if [ -r .version ]; then
 345         VERSION=$(expr 0$(cat .version) + 1)
 346         echo $VERSION > .version
 347 else
 348         rm -f .version
 349         echo 1 > .version
 350 fi;
 351
 352 # final build of init/
 353 ${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1
 354
 355 #link vmlinux.o
 356 modpost_link vmlinux.o
 357 objtool_link vmlinux.o
 358
 359 # modpost vmlinux.o to check for section mismatches
 360 ${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1
 361
 362 info MODINFO modules.builtin.modinfo
 363 ${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo
 364 info GEN modules.builtin
 365 # The second line aids cases where multiple modules share the same object.
 366 tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' |
 367         tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin
 368
 369 btf_vmlinux_bin_o=""
 370 if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then
 371         btf_vmlinux_bin_o=.btf.vmlinux.bin.o
 372         if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then
 373                 echo >&2 "Failed to generate BTF for vmlinux"
 374                 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF"
 375                 exit 1
 376         fi
 377 fi
 378
 379 kallsymso=""
 380 kallsymso_prev=""
 381 kallsyms_vmlinux=""
 382 if [ -n "${CONFIG_KALLSYMS}" ]; then
 383
 384         # kallsyms support
 385         # Generate section listing all symbols and add it into vmlinux
 386         # It's a three step process:
 387         # 1)  Link .tmp_vmlinux1 so it has all symbols and sections,
 388         #     but __kallsyms is empty.
 389         #     Running kallsyms on that gives us .tmp_kallsyms1.o with
 390         #     the right size
 391         # 2)  Link .tmp_vmlinux2 so it now has a __kallsyms section of
 392         #     the right size, but due to the added section, some
 393         #     addresses have shifted.
 394         #     From here, we generate a correct .tmp_kallsyms2.o
 395         # 3)  That link may have expanded the kernel image enough that
 396         #     more linker branch stubs / trampolines had to be added, which
 397         #     introduces new names, which further expands kallsyms. Do another
 398         #     pass if that is the case. In theory it's possible this results
 399         #     in even more stubs, but unlikely.
 400         #     KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
 401         #     other bugs.
 402         # 4)  The correct ${kallsymso} is linked into the final vmlinux.
 403         #
 404         # a)  Verify that the System.map from vmlinux matches the map from
 405         #     ${kallsymso}.
 406
 407         kallsyms_step 1
 408         kallsyms_step 2
 409
 410         # step 3
 411         size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev})
 412         size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
 413
 414         if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
 415                 kallsyms_step 3
 416         fi
 417 fi
 418
 419 vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o}
 420
 421 # fill in BTF IDs
 422 if [ -n "${CONFIG_DEBUG_INFO_BTF}" -a -n "${CONFIG_BPF}" ]; then
 423         info BTFIDS vmlinux
 424         ${RESOLVE_BTFIDS} vmlinux
 425 fi
 426
 427 if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then
 428         info SORTTAB vmlinux
 429         if ! sorttable vmlinux; then
 430                 echo >&2 Failed to sort kernel tables
 431                 exit 1
 432         fi
 433 fi
 434
 435 info SYSMAP System.map
 436 mksysmap vmlinux System.map
 437
 438 # step a (see comment above)
 439 if [ -n "${CONFIG_KALLSYMS}" ]; then
 440         mksysmap ${kallsyms_vmlinux} .tmp_System.map
 441
 442         if ! cmp -s System.map .tmp_System.map; then
 443                 echo >&2 Inconsistent kallsyms data
 444                 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
 445                 exit 1
 446         fi
 447 fi
 448
 449 # For fixdep
 450 echo "vmlinux: $0" > .vmlinux.d