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 # Link of vmlinux.o used for section mismatch analysis
  47 # ${1} output file
  48 modpost_link()
  49 {
  50         local objects
  51
  52         objects="--whole-archive                                \
  53                 ${KBUILD_VMLINUX_OBJS}                          \
  54                 --no-whole-archive                              \
  55                 --start-group                                   \
  56                 ${KBUILD_VMLINUX_LIBS}                          \
  57                 --end-group"
  58
  59         ${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${objects}
  60 }
  61
  62 objtool_link()
  63 {
  64         local objtoolopt;
  65
  66         if [ -n "${CONFIG_VMLINUX_VALIDATION}" ]; then
  67                 objtoolopt="check"
  68                 if [ -n "${CONFIG_CPU_UNRET_ENTRY}" ]; then
  69                         objtoolopt="${objtoolopt} --unret"
  70                 fi
  71                 if [ -z "${CONFIG_FRAME_POINTER}" ]; then
  72                         objtoolopt="${objtoolopt} --no-fp"
  73                 fi
  74                 if [ -n "${CONFIG_GCOV_KERNEL}" ]; then
  75                         objtoolopt="${objtoolopt} --no-unreachable"
  76                 fi
  77                 if [ -n "${CONFIG_RETPOLINE}" ]; then
  78                         objtoolopt="${objtoolopt} --retpoline"
  79                 fi
  80                 if [ -n "${CONFIG_X86_SMAP}" ]; then
  81                         objtoolopt="${objtoolopt} --uaccess"
  82                 fi
  83                 if [ -n "${CONFIG_SLS}" ]; then
  84                         objtoolopt="${objtoolopt} --sls"
  85                 fi
  86                 info OBJTOOL ${1}
  87                 tools/objtool/objtool ${objtoolopt} ${1}
  88         fi
  89 }
  90
  91 # Link of vmlinux
  92 # ${1} - output file
  93 # ${2}, ${3}, ... - optional extra .o files
  94 vmlinux_link()
  95 {
  96         local lds="${objtree}/${KBUILD_LDS}"
  97         local output=${1}
  98         local objects
  99         local strip_debug
 100
 101         info LD ${output}
 102
 103         # skip output file argument
 104         shift
 105
 106         # The kallsyms linking does not need debug symbols included.
 107         if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
 108                 strip_debug=-Wl,--strip-debug
 109         fi
 110
 111         if [ "${SRCARCH}" != "um" ]; then
 112                 objects="--whole-archive                        \
 113                         ${KBUILD_VMLINUX_OBJS}                  \
 114                         --no-whole-archive                      \
 115                         --start-group                           \
 116                         ${KBUILD_VMLINUX_LIBS}                  \
 117                         --end-group                             \
 118                         ${@}"
 119
 120                 ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}      \
 121                         ${strip_debug#-Wl,}                     \
 122                         -o ${output}                            \
 123                         -T ${lds} ${objects}
 124         else
 125                 objects="-Wl,--whole-archive                    \
 126                         ${KBUILD_VMLINUX_OBJS}                  \
 127                         -Wl,--no-whole-archive                  \
 128                         -Wl,--start-group                       \
 129                         ${KBUILD_VMLINUX_LIBS}                  \
 130                         -Wl,--end-group                         \
 131                         ${@}"
 132
 133                 ${CC} ${CFLAGS_vmlinux}                         \
 134                         ${strip_debug}                          \
 135                         -o ${output}                            \
 136                         -Wl,-T,${lds}                           \
 137                         ${objects}                              \
 138                         -lutil -lrt -lpthread
 139                 rm -f linux
 140         fi
 141 }
 142
 143 # generate .BTF typeinfo from DWARF debuginfo
 144 # ${1} - vmlinux image
 145 # ${2} - file to dump raw BTF data into
 146 gen_btf()
 147 {
 148         local pahole_ver
 149
 150         if ! [ -x "$(command -v ${PAHOLE})" ]; then
 151                 echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available"
 152                 return 1
 153         fi
 154
 155         pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
 156         if [ "${pahole_ver}" -lt "116" ]; then
 157                 echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.16"
 158                 return 1
 159         fi
 160
 161         vmlinux_link ${1}
 162
 163         info "BTF" ${2}
 164         LLVM_OBJCOPY="${OBJCOPY}" ${PAHOLE} -J ${PAHOLE_FLAGS} ${1}
 165
 166         # Create ${2} which contains just .BTF section but no symbols. Add
 167         # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all
 168         # deletes all symbols including __start_BTF and __stop_BTF, which will
 169         # be redefined in the linker script. Add 2>/dev/null to suppress GNU
 170         # objcopy warnings: "empty loadable segment detected at ..."
 171         ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \
 172                 --strip-all ${1} ${2} 2>/dev/null
 173         # Change e_type to ET_REL so that it can be used to link final vmlinux.
 174         # GNU ld 2.35+ and lld do not allow an ET_EXEC input.
 175         if [ -n "${CONFIG_CPU_BIG_ENDIAN}" ]; then
 176                 et_rel='\0\1'
 177         else
 178                 et_rel='\1\0'
 179         fi
 180         printf "${et_rel}" | dd of=${2} conv=notrunc bs=1 seek=16 status=none
 181 }
 182
 183 # Create ${2} .S file with all symbols from the ${1} object file
 184 kallsyms()
 185 {
 186         local kallsymopt;
 187
 188         if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
 189                 kallsymopt="${kallsymopt} --all-symbols"
 190         fi
 191
 192         if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
 193                 kallsymopt="${kallsymopt} --absolute-percpu"
 194         fi
 195
 196         if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then
 197                 kallsymopt="${kallsymopt} --base-relative"
 198         fi
 199
 200         info KSYMS ${2}
 201         ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${2}
 202 }
 203
 204 # Perform one step in kallsyms generation, including temporary linking of
 205 # vmlinux.
 206 kallsyms_step()
 207 {
 208         kallsymso_prev=${kallsymso}
 209         kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1}
 210         kallsymso=${kallsyms_vmlinux}.o
 211         kallsyms_S=${kallsyms_vmlinux}.S
 212
 213         vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o}
 214         kallsyms ${kallsyms_vmlinux} ${kallsyms_S}
 215
 216         info AS ${kallsyms_S}
 217         ${CC} ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS} \
 218               ${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL} \
 219               -c -o ${kallsymso} ${kallsyms_S}
 220 }
 221
 222 # Create map file with all symbols from ${1}
 223 # See mksymap for additional details
 224 mksysmap()
 225 {
 226         ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
 227 }
 228
 229 sorttable()
 230 {
 231         ${objtree}/scripts/sorttable ${1}
 232 }
 233
 234 # Delete output files in case of error
 235 cleanup()
 236 {
 237         rm -f .btf.*
 238         rm -f .tmp_System.map
 239         rm -f .tmp_vmlinux*
 240         rm -f System.map
 241         rm -f vmlinux
 242         rm -f vmlinux.o
 243 }
 244
 245 on_exit()
 246 {
 247         if [ $? -ne 0 ]; then
 248                 cleanup
 249         fi
 250 }
 251 trap on_exit EXIT
 252
 253 on_signals()
 254 {
 255         exit 1
 256 }
 257 trap on_signals HUP INT QUIT TERM
 258
 259 # Use "make V=1" to debug this script
 260 case "${KBUILD_VERBOSE}" in
 261 *1*)
 262         set -x
 263         ;;
 264 esac
 265
 266 if [ "$1" = "clean" ]; then
 267         cleanup
 268         exit 0
 269 fi
 270
 271 # We need access to CONFIG_ symbols
 272 . include/config/auto.conf
 273
 274 # Update version
 275 info GEN .version
 276 if [ -r .version ]; then
 277         VERSION=$(expr 0$(cat .version) + 1)
 278         echo $VERSION > .version
 279 else
 280         rm -f .version
 281         echo 1 > .version
 282 fi;
 283
 284 # final build of init/
 285 ${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1
 286
 287 #link vmlinux.o
 288 info LD vmlinux.o
 289 modpost_link vmlinux.o
 290 objtool_link vmlinux.o
 291
 292 # modpost vmlinux.o to check for section mismatches
 293 ${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1
 294
 295 info MODINFO modules.builtin.modinfo
 296 ${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo
 297 info GEN modules.builtin
 298 # The second line aids cases where multiple modules share the same object.
 299 tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' |
 300         tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin
 301
 302 btf_vmlinux_bin_o=""
 303 if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then
 304         btf_vmlinux_bin_o=.btf.vmlinux.bin.o
 305         if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then
 306                 echo >&2 "Failed to generate BTF for vmlinux"
 307                 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF"
 308                 exit 1
 309         fi
 310 fi
 311
 312 kallsymso=""
 313 kallsymso_prev=""
 314 kallsyms_vmlinux=""
 315 if [ -n "${CONFIG_KALLSYMS}" ]; then
 316
 317         # kallsyms support
 318         # Generate section listing all symbols and add it into vmlinux
 319         # It's a three step process:
 320         # 1)  Link .tmp_vmlinux1 so it has all symbols and sections,
 321         #     but __kallsyms is empty.
 322         #     Running kallsyms on that gives us .tmp_kallsyms1.o with
 323         #     the right size
 324         # 2)  Link .tmp_vmlinux2 so it now has a __kallsyms section of
 325         #     the right size, but due to the added section, some
 326         #     addresses have shifted.
 327         #     From here, we generate a correct .tmp_kallsyms2.o
 328         # 3)  That link may have expanded the kernel image enough that
 329         #     more linker branch stubs / trampolines had to be added, which
 330         #     introduces new names, which further expands kallsyms. Do another
 331         #     pass if that is the case. In theory it's possible this results
 332         #     in even more stubs, but unlikely.
 333         #     KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
 334         #     other bugs.
 335         # 4)  The correct ${kallsymso} is linked into the final vmlinux.
 336         #
 337         # a)  Verify that the System.map from vmlinux matches the map from
 338         #     ${kallsymso}.
 339
 340         kallsyms_step 1
 341         kallsyms_step 2
 342
 343         # step 3
 344         size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev})
 345         size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
 346
 347         if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
 348                 kallsyms_step 3
 349         fi
 350 fi
 351
 352 vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o}
 353
 354 # fill in BTF IDs
 355 if [ -n "${CONFIG_DEBUG_INFO_BTF}" -a -n "${CONFIG_BPF}" ]; then
 356         info BTFIDS vmlinux
 357         ${RESOLVE_BTFIDS} vmlinux
 358 fi
 359
 360 if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then
 361         info SORTTAB vmlinux
 362         if ! sorttable vmlinux; then
 363                 echo >&2 Failed to sort kernel tables
 364                 exit 1
 365         fi
 366 fi
 367
 368 info SYSMAP System.map
 369 mksysmap vmlinux System.map
 370
 371 # step a (see comment above)
 372 if [ -n "${CONFIG_KALLSYMS}" ]; then
 373         mksysmap ${kallsyms_vmlinux} .tmp_System.map
 374
 375         if ! cmp -s System.map .tmp_System.map; then
 376                 echo >&2 Inconsistent kallsyms data
 377                 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
 378                 exit 1
 379         fi
 380 fi