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}, ${3}, ... - optional extra .o files
 150 vmlinux_link()
 151 {
 152         local output=${1}
 153         local objs
 154         local libs
 155         local ld
 156         local ldflags
 157         local ldlibs
 158
 159         info LD ${output}
 160
 161         # skip output file argument
 162         shift
 163
 164         if [ -n "${CONFIG_LTO_CLANG}" ]; then
 165                 # Use vmlinux.o instead of performing the slow LTO link again.
 166                 objs=vmlinux.o
 167                 libs=
 168         else
 169                 objs="${KBUILD_VMLINUX_OBJS}"
 170                 libs="${KBUILD_VMLINUX_LIBS}"
 171         fi
 172
 173         if [ "${SRCARCH}" = "um" ]; then
 174                 wl=-Wl,
 175                 ld="${CC}"
 176                 ldflags="${CFLAGS_vmlinux}"
 177                 ldlibs="-lutil -lrt -lpthread"
 178         else
 179                 wl=
 180                 ld="${LD}"
 181                 ldflags="${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}"
 182                 ldlibs=
 183         fi
 184
 185         ldflags="${ldflags} ${wl}--script=${objtree}/${KBUILD_LDS}"
 186
 187         # The kallsyms linking does not need debug symbols included.
 188         if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
 189                 ldflags="${ldflags} ${wl}--strip-debug"
 190         fi
 191
 192         if [ -n "${CONFIG_VMLINUX_MAP}" ]; then
 193                 ldflags="${ldflags} ${wl}-Map=${output}.map"
 194         fi
 195
 196         ${ld} ${ldflags} -o ${output}                                   \
 197                 ${wl}--whole-archive ${objs} ${wl}--no-whole-archive    \
 198                 ${wl}--start-group ${libs} ${wl}--end-group             \
 199                 $@ ${ldlibs}
 200 }
 201
 202 # generate .BTF typeinfo from DWARF debuginfo
 203 # ${1} - vmlinux image
 204 # ${2} - file to dump raw BTF data into
 205 gen_btf()
 206 {
 207         local pahole_ver
 208
 209         if ! [ -x "$(command -v ${PAHOLE})" ]; then
 210                 echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available"
 211                 return 1
 212         fi
 213
 214         pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
 215         if [ "${pahole_ver}" -lt "116" ]; then
 216                 echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.16"
 217                 return 1
 218         fi
 219
 220         vmlinux_link ${1}
 221
 222         info "BTF" ${2}
 223         LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1}
 224
 225         # Create ${2} which contains just .BTF section but no symbols. Add
 226         # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all
 227         # deletes all symbols including __start_BTF and __stop_BTF, which will
 228         # be redefined in the linker script. Add 2>/dev/null to suppress GNU
 229         # objcopy warnings: "empty loadable segment detected at ..."
 230         ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \
 231                 --strip-all ${1} ${2} 2>/dev/null
 232         # Change e_type to ET_REL so that it can be used to link final vmlinux.
 233         # Unlike GNU ld, lld does not allow an ET_EXEC input.
 234         printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none
 235 }
 236
 237 # Create ${2} .S file with all symbols from the ${1} object file
 238 kallsyms()
 239 {
 240         local kallsymopt;
 241
 242         if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
 243                 kallsymopt="${kallsymopt} --all-symbols"
 244         fi
 245
 246         if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
 247                 kallsymopt="${kallsymopt} --absolute-percpu"
 248         fi
 249
 250         if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then
 251                 kallsymopt="${kallsymopt} --base-relative"
 252         fi
 253
 254         info KSYMS ${2}
 255         ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${2}
 256 }
 257
 258 # Perform one step in kallsyms generation, including temporary linking of
 259 # vmlinux.
 260 kallsyms_step()
 261 {
 262         kallsymso_prev=${kallsymso}
 263         kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1}
 264         kallsymso=${kallsyms_vmlinux}.o
 265         kallsyms_S=${kallsyms_vmlinux}.S
 266
 267         vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o}
 268         kallsyms ${kallsyms_vmlinux} ${kallsyms_S}
 269
 270         info AS ${kallsyms_S}
 271         ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \
 272               ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \
 273               -c -o ${kallsymso} ${kallsyms_S}
 274 }
 275
 276 # Create map file with all symbols from ${1}
 277 # See mksymap for additional details
 278 mksysmap()
 279 {
 280         ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
 281 }
 282
 283 sorttable()
 284 {
 285         ${objtree}/scripts/sorttable ${1}
 286 }
 287
 288 # Delete output files in case of error
 289 cleanup()
 290 {
 291         rm -f .btf.*
 292         rm -f .tmp_System.map
 293         rm -f .tmp_initcalls.lds
 294         rm -f .tmp_symversions.lds
 295         rm -f .tmp_vmlinux*
 296         rm -f System.map
 297         rm -f vmlinux
 298         rm -f vmlinux.map
 299         rm -f vmlinux.o
 300         rm -f .vmlinux.d
 301 }
 302
 303 # Use "make V=1" to debug this script
 304 case "${KBUILD_VERBOSE}" in
 305 *1*)
 306         set -x
 307         ;;
 308 esac
 309
 310 if [ "$1" = "clean" ]; then
 311         cleanup
 312         exit 0
 313 fi
 314
 315 # We need access to CONFIG_ symbols
 316 . include/config/auto.conf
 317
 318 # Update version
 319 info GEN .version
 320 if [ -r .version ]; then
 321         VERSION=$(expr 0$(cat .version) + 1)
 322         echo $VERSION > .version
 323 else
 324         rm -f .version
 325         echo 1 > .version
 326 fi;
 327
 328 # final build of init/
 329 ${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1
 330
 331 #link vmlinux.o
 332 modpost_link vmlinux.o
 333 objtool_link vmlinux.o
 334
 335 # modpost vmlinux.o to check for section mismatches
 336 ${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1
 337
 338 info MODINFO modules.builtin.modinfo
 339 ${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo
 340 info GEN modules.builtin
 341 # The second line aids cases where multiple modules share the same object.
 342 tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' |
 343         tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin
 344
 345 btf_vmlinux_bin_o=""
 346 if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then
 347         btf_vmlinux_bin_o=.btf.vmlinux.bin.o
 348         if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then
 349                 echo >&2 "Failed to generate BTF for vmlinux"
 350                 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF"
 351                 exit 1
 352         fi
 353 fi
 354
 355 kallsymso=""
 356 kallsymso_prev=""
 357 kallsyms_vmlinux=""
 358 if [ -n "${CONFIG_KALLSYMS}" ]; then
 359
 360         # kallsyms support
 361         # Generate section listing all symbols and add it into vmlinux
 362         # It's a three step process:
 363         # 1)  Link .tmp_vmlinux1 so it has all symbols and sections,
 364         #     but __kallsyms is empty.
 365         #     Running kallsyms on that gives us .tmp_kallsyms1.o with
 366         #     the right size
 367         # 2)  Link .tmp_vmlinux2 so it now has a __kallsyms section of
 368         #     the right size, but due to the added section, some
 369         #     addresses have shifted.
 370         #     From here, we generate a correct .tmp_kallsyms2.o
 371         # 3)  That link may have expanded the kernel image enough that
 372         #     more linker branch stubs / trampolines had to be added, which
 373         #     introduces new names, which further expands kallsyms. Do another
 374         #     pass if that is the case. In theory it's possible this results
 375         #     in even more stubs, but unlikely.
 376         #     KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
 377         #     other bugs.
 378         # 4)  The correct ${kallsymso} is linked into the final vmlinux.
 379         #
 380         # a)  Verify that the System.map from vmlinux matches the map from
 381         #     ${kallsymso}.
 382
 383         kallsyms_step 1
 384         kallsyms_step 2
 385
 386         # step 3
 387         size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev})
 388         size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
 389
 390         if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
 391                 kallsyms_step 3
 392         fi
 393 fi
 394
 395 vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o}
 396
 397 # fill in BTF IDs
 398 if [ -n "${CONFIG_DEBUG_INFO_BTF}" -a -n "${CONFIG_BPF}" ]; then
 399         info BTFIDS vmlinux
 400         ${RESOLVE_BTFIDS} vmlinux
 401 fi
 402
 403 if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then
 404         info SORTTAB vmlinux
 405         if ! sorttable vmlinux; then
 406                 echo >&2 Failed to sort kernel tables
 407                 exit 1
 408         fi
 409 fi
 410
 411 info SYSMAP System.map
 412 mksysmap vmlinux System.map
 413
 414 # step a (see comment above)
 415 if [ -n "${CONFIG_KALLSYMS}" ]; then
 416         mksysmap ${kallsyms_vmlinux} .tmp_System.map
 417
 418         if ! cmp -s System.map .tmp_System.map; then
 419                 echo >&2 Inconsistent kallsyms data
 420                 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
 421                 exit 1
 422         fi
 423 fi
 424
 425 # For fixdep
 426 echo "vmlinux: $0" > .vmlinux.d