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