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