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 #   +-< ${kallsymso} (see description in KALLSYMS section)
  22 #
  23 # vmlinux version (uname -v) cannot be updated during normal
  24 # descending-into-subdirs phase since we do not yet know if we need to
  25 # update vmlinux.
  26 # Therefore this step is delayed until just before final link of vmlinux.
  27 #
  28 # System.map is generated to document addresses of all kernel symbols
  29
  30 # Error out on error
  31 set -e
  32
  33 # Nice output in kbuild format
  34 # Will be supressed by "make -s"
  35 info()
  36 {
  37         if [ "${quiet}" != "silent_" ]; then
  38                 printf "  %-7s %s\n" "${1}" "${2}"
  39         fi
  40 }
  41
  42 # Link of vmlinux.o used for section mismatch analysis
  43 # ${1} output file
  44 modpost_link()
  45 {
  46         local objects
  47
  48         objects="--whole-archive                                \
  49                 ${KBUILD_VMLINUX_OBJS}                          \
  50                 --no-whole-archive                              \
  51                 --start-group                                   \
  52                 ${KBUILD_VMLINUX_LIBS}                          \
  53                 --end-group"
  54
  55         ${LD} ${KBUILD_LDFLAGS} -r -o ${1} ${objects}
  56 }
  57
  58 objtool_link()
  59 {
  60         local objtoolopt;
  61
  62         if [ -n "${CONFIG_VMLINUX_VALIDATION}" ]; then
  63                 objtoolopt="check"
  64                 if [ -z "${CONFIG_FRAME_POINTER}" ]; then
  65                         objtoolopt="${objtoolopt} --no-fp"
  66                 fi
  67                 if [ -n "${CONFIG_GCOV_KERNEL}" ]; then
  68                         objtoolopt="${objtoolopt} --no-unreachable"
  69                 fi
  70                 if [ -n "${CONFIG_RETPOLINE}" ]; then
  71                         objtoolopt="${objtoolopt} --retpoline"
  72                 fi
  73                 if [ -n "${CONFIG_X86_SMAP}" ]; then
  74                         objtoolopt="${objtoolopt} --uaccess"
  75                 fi
  76                 info OBJTOOL ${1}
  77                 tools/objtool/objtool ${objtoolopt} ${1}
  78         fi
  79 }
  80
  81 # Link of vmlinux
  82 # ${1} - output file
  83 # ${2}, ${3}, ... - optional extra .o files
  84 vmlinux_link()
  85 {
  86         local lds="${objtree}/${KBUILD_LDS}"
  87         local output=${1}
  88         local objects
  89         local strip_debug
  90
  91         info LD ${output}
  92
  93         # skip output file argument
  94         shift
  95
  96         # The kallsyms linking does not need debug symbols included.
  97         if [ "$output" != "${output#.tmp_vmlinux.kallsyms}" ] ; then
  98                 strip_debug=-Wl,--strip-debug
  99         fi
 100
 101         if [ "${SRCARCH}" != "um" ]; then
 102                 objects="--whole-archive                        \
 103                         ${KBUILD_VMLINUX_OBJS}                  \
 104                         --no-whole-archive                      \
 105                         --start-group                           \
 106                         ${KBUILD_VMLINUX_LIBS}                  \
 107                         --end-group                             \
 108                         ${@}"
 109
 110                 ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}      \
 111                         ${strip_debug#-Wl,}                     \
 112                         -o ${output}                            \
 113                         -T ${lds} ${objects}
 114         else
 115                 objects="-Wl,--whole-archive                    \
 116                         ${KBUILD_VMLINUX_OBJS}                  \
 117                         -Wl,--no-whole-archive                  \
 118                         -Wl,--start-group                       \
 119                         ${KBUILD_VMLINUX_LIBS}                  \
 120                         -Wl,--end-group                         \
 121                         ${@}"
 122
 123                 ${CC} ${CFLAGS_vmlinux}                         \
 124                         ${strip_debug}                          \
 125                         -o ${output}                            \
 126                         -Wl,-T,${lds}                           \
 127                         ${objects}                              \
 128                         -lutil -lrt -lpthread
 129                 rm -f linux
 130         fi
 131 }
 132
 133 # generate .BTF typeinfo from DWARF debuginfo
 134 # ${1} - vmlinux image
 135 # ${2} - file to dump raw BTF data into
 136 gen_btf()
 137 {
 138         local pahole_ver
 139
 140         if ! [ -x "$(command -v ${PAHOLE})" ]; then
 141                 echo >&2 "BTF: ${1}: pahole (${PAHOLE}) is not available"
 142                 return 1
 143         fi
 144
 145         pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
 146         if [ "${pahole_ver}" -lt "116" ]; then
 147                 echo >&2 "BTF: ${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.16"
 148                 return 1
 149         fi
 150
 151         vmlinux_link ${1}
 152
 153         info "BTF" ${2}
 154         LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1}
 155
 156         # Create ${2} which contains just .BTF section but no symbols. Add
 157         # SHF_ALLOC because .BTF will be part of the vmlinux image. --strip-all
 158         # deletes all symbols including __start_BTF and __stop_BTF, which will
 159         # be redefined in the linker script. Add 2>/dev/null to suppress GNU
 160         # objcopy warnings: "empty loadable segment detected at ..."
 161         ${OBJCOPY} --only-section=.BTF --set-section-flags .BTF=alloc,readonly \
 162                 --strip-all ${1} ${2} 2>/dev/null
 163         # Change e_type to ET_REL so that it can be used to link final vmlinux.
 164         # Unlike GNU ld, lld does not allow an ET_EXEC input.
 165         printf '\1' | dd of=${2} conv=notrunc bs=1 seek=16 status=none
 166 }
 167
 168 # Create ${2} .o file with all symbols from the ${1} object file
 169 kallsyms()
 170 {
 171         info KSYM ${2}
 172         local kallsymopt;
 173
 174         if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
 175                 kallsymopt="${kallsymopt} --all-symbols"
 176         fi
 177
 178         if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
 179                 kallsymopt="${kallsymopt} --absolute-percpu"
 180         fi
 181
 182         if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then
 183                 kallsymopt="${kallsymopt} --base-relative"
 184         fi
 185
 186         local aflags="${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL}               \
 187                       ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS}"
 188
 189         local afile="`basename ${2} .o`.S"
 190
 191         ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${afile}
 192         ${CC} ${aflags} -c -o ${2} ${afile}
 193 }
 194
 195 # Perform one step in kallsyms generation, including temporary linking of
 196 # vmlinux.
 197 kallsyms_step()
 198 {
 199         kallsymso_prev=${kallsymso}
 200         kallsyms_vmlinux=.tmp_vmlinux.kallsyms${1}
 201         kallsymso=${kallsyms_vmlinux}.o
 202
 203         vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o}
 204         kallsyms ${kallsyms_vmlinux} ${kallsymso}
 205 }
 206
 207 # Create map file with all symbols from ${1}
 208 # See mksymap for additional details
 209 mksysmap()
 210 {
 211         ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
 212 }
 213
 214 sorttable()
 215 {
 216         ${objtree}/scripts/sorttable ${1}
 217 }
 218
 219 # Delete output files in case of error
 220 cleanup()
 221 {
 222         rm -f .btf.*
 223         rm -f .tmp_System.map
 224         rm -f .tmp_vmlinux*
 225         rm -f System.map
 226         rm -f vmlinux
 227         rm -f vmlinux.o
 228 }
 229
 230 on_exit()
 231 {
 232         if [ $? -ne 0 ]; then
 233                 cleanup
 234         fi
 235 }
 236 trap on_exit EXIT
 237
 238 on_signals()
 239 {
 240         exit 1
 241 }
 242 trap on_signals HUP INT QUIT TERM
 243
 244 # Use "make V=1" to debug this script
 245 case "${KBUILD_VERBOSE}" in
 246 *1*)
 247         set -x
 248         ;;
 249 esac
 250
 251 if [ "$1" = "clean" ]; then
 252         cleanup
 253         exit 0
 254 fi
 255
 256 # We need access to CONFIG_ symbols
 257 . include/config/auto.conf
 258
 259 # Update version
 260 info GEN .version
 261 if [ -r .version ]; then
 262         VERSION=$(expr 0$(cat .version) + 1)
 263         echo $VERSION > .version
 264 else
 265         rm -f .version
 266         echo 1 > .version
 267 fi;
 268
 269 # final build of init/
 270 ${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1
 271
 272 #link vmlinux.o
 273 info LD vmlinux.o
 274 modpost_link vmlinux.o
 275 objtool_link vmlinux.o
 276
 277 # modpost vmlinux.o to check for section mismatches
 278 ${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1
 279
 280 info MODINFO modules.builtin.modinfo
 281 ${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo
 282 info GEN modules.builtin
 283 # The second line aids cases where multiple modules share the same object.
 284 tr '\0' '\n' < modules.builtin.modinfo | sed -n 's/^[[:alnum:]:_]*\.file=//p' |
 285         tr ' ' '\n' | uniq | sed -e 's:^:kernel/:' -e 's/$/.ko/' > modules.builtin
 286
 287 btf_vmlinux_bin_o=""
 288 if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then
 289         btf_vmlinux_bin_o=.btf.vmlinux.bin.o
 290         if ! gen_btf .tmp_vmlinux.btf $btf_vmlinux_bin_o ; then
 291                 echo >&2 "Failed to generate BTF for vmlinux"
 292                 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF"
 293                 exit 1
 294         fi
 295 fi
 296
 297 kallsymso=""
 298 kallsymso_prev=""
 299 kallsyms_vmlinux=""
 300 if [ -n "${CONFIG_KALLSYMS}" ]; then
 301
 302         # kallsyms support
 303         # Generate section listing all symbols and add it into vmlinux
 304         # It's a three step process:
 305         # 1)  Link .tmp_vmlinux1 so it has all symbols and sections,
 306         #     but __kallsyms is empty.
 307         #     Running kallsyms on that gives us .tmp_kallsyms1.o with
 308         #     the right size
 309         # 2)  Link .tmp_vmlinux2 so it now has a __kallsyms section of
 310         #     the right size, but due to the added section, some
 311         #     addresses have shifted.
 312         #     From here, we generate a correct .tmp_kallsyms2.o
 313         # 3)  That link may have expanded the kernel image enough that
 314         #     more linker branch stubs / trampolines had to be added, which
 315         #     introduces new names, which further expands kallsyms. Do another
 316         #     pass if that is the case. In theory it's possible this results
 317         #     in even more stubs, but unlikely.
 318         #     KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
 319         #     other bugs.
 320         # 4)  The correct ${kallsymso} is linked into the final vmlinux.
 321         #
 322         # a)  Verify that the System.map from vmlinux matches the map from
 323         #     ${kallsymso}.
 324
 325         kallsyms_step 1
 326         kallsyms_step 2
 327
 328         # step 3
 329         size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev})
 330         size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
 331
 332         if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
 333                 kallsyms_step 3
 334         fi
 335 fi
 336
 337 vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o}
 338
 339 if [ -n "${CONFIG_BUILDTIME_TABLE_SORT}" ]; then
 340         info SORTTAB vmlinux
 341         if ! sorttable vmlinux; then
 342                 echo >&2 Failed to sort kernel tables
 343                 exit 1
 344         fi
 345 fi
 346
 347 info SYSMAP System.map
 348 mksysmap vmlinux System.map
 349
 350 # step a (see comment above)
 351 if [ -n "${CONFIG_KALLSYMS}" ]; then
 352         mksysmap ${kallsyms_vmlinux} .tmp_System.map
 353
 354         if ! cmp -s System.map .tmp_System.map; then
 355                 echo >&2 Inconsistent kallsyms data
 356                 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
 357                 exit 1
 358         fi
 359 fi