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 # Link of vmlinux
  59 # ${1} - output file
  60 # ${@:2} - optional extra .o files
  61 vmlinux_link()
  62 {
  63         local lds="${objtree}/${KBUILD_LDS}"
  64         local objects
  65
  66         if [ "${SRCARCH}" != "um" ]; then
  67                 objects="--whole-archive                        \
  68                         ${KBUILD_VMLINUX_OBJS}                  \
  69                         --no-whole-archive                      \
  70                         --start-group                           \
  71                         ${KBUILD_VMLINUX_LIBS}                  \
  72                         --end-group                             \
  73                         ${@:2}"
  74
  75                 ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} -o ${1}      \
  76                         -T ${lds} ${objects}
  77         else
  78                 objects="-Wl,--whole-archive                    \
  79                         ${KBUILD_VMLINUX_OBJS}                  \
  80                         -Wl,--no-whole-archive                  \
  81                         -Wl,--start-group                       \
  82                         ${KBUILD_VMLINUX_LIBS}                  \
  83                         -Wl,--end-group                         \
  84                         ${@:2}"
  85
  86                 ${CC} ${CFLAGS_vmlinux} -o ${1}                 \
  87                         -Wl,-T,${lds}                           \
  88                         ${objects}                              \
  89                         -lutil -lrt -lpthread
  90                 rm -f linux
  91         fi
  92 }
  93
  94 # generate .BTF typeinfo from DWARF debuginfo
  95 # ${1} - vmlinux image
  96 # ${2} - file to dump raw BTF data into
  97 gen_btf()
  98 {
  99         local pahole_ver
 100         local bin_arch
 101
 102         if ! [ -x "$(command -v ${PAHOLE})" ]; then
 103                 info "BTF" "${1}: pahole (${PAHOLE}) is not available"
 104                 return 1
 105         fi
 106
 107         pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
 108         if [ "${pahole_ver}" -lt "113" ]; then
 109                 info "BTF" "${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.13"
 110                 return 1
 111         fi
 112
 113         info "BTF" ${2}
 114         vmlinux_link ${1}
 115         LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1}
 116
 117         # dump .BTF section into raw binary file to link with final vmlinux
 118         bin_arch=$(${OBJDUMP} -f ${1} | grep architecture | \
 119                 cut -d, -f1 | cut -d' ' -f2)
 120         ${OBJCOPY} --dump-section .BTF=.btf.kernel.bin ${1} 2>/dev/null
 121         ${OBJCOPY} -I binary -O ${CONFIG_OUTPUT_FORMAT} -B ${bin_arch} \
 122                 --rename-section .data=.BTF .btf.kernel.bin ${2}
 123 }
 124
 125 # Create ${2} .o file with all symbols from the ${1} object file
 126 kallsyms()
 127 {
 128         info KSYM ${2}
 129         local kallsymopt;
 130
 131         if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
 132                 kallsymopt="${kallsymopt} --all-symbols"
 133         fi
 134
 135         if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
 136                 kallsymopt="${kallsymopt} --absolute-percpu"
 137         fi
 138
 139         if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then
 140                 kallsymopt="${kallsymopt} --base-relative"
 141         fi
 142
 143         local aflags="${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL}               \
 144                       ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS}"
 145
 146         local afile="`basename ${2} .o`.S"
 147
 148         ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${afile}
 149         ${CC} ${aflags} -c -o ${2} ${afile}
 150 }
 151
 152 # Create map file with all symbols from ${1}
 153 # See mksymap for additional details
 154 mksysmap()
 155 {
 156         ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
 157 }
 158
 159 sortextable()
 160 {
 161         ${objtree}/scripts/sortextable ${1}
 162 }
 163
 164 # Delete output files in case of error
 165 cleanup()
 166 {
 167         rm -f .btf.*
 168         rm -f .tmp_System.map
 169         rm -f .tmp_kallsyms*
 170         rm -f .tmp_vmlinux*
 171         rm -f System.map
 172         rm -f vmlinux
 173         rm -f vmlinux.o
 174 }
 175
 176 on_exit()
 177 {
 178         if [ $? -ne 0 ]; then
 179                 cleanup
 180         fi
 181 }
 182 trap on_exit EXIT
 183
 184 on_signals()
 185 {
 186         exit 1
 187 }
 188 trap on_signals HUP INT QUIT TERM
 189
 190 #
 191 #
 192 # Use "make V=1" to debug this script
 193 case "${KBUILD_VERBOSE}" in
 194 *1*)
 195         set -x
 196         ;;
 197 esac
 198
 199 if [ "$1" = "clean" ]; then
 200         cleanup
 201         exit 0
 202 fi
 203
 204 # We need access to CONFIG_ symbols
 205 . include/config/auto.conf
 206
 207 # Update version
 208 info GEN .version
 209 if [ -r .version ]; then
 210         VERSION=$(expr 0$(cat .version) + 1)
 211         echo $VERSION > .version
 212 else
 213         rm -f .version
 214         echo 1 > .version
 215 fi;
 216
 217 # final build of init/
 218 ${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init
 219
 220 #link vmlinux.o
 221 info LD vmlinux.o
 222 modpost_link vmlinux.o
 223
 224 # modpost vmlinux.o to check for section mismatches
 225 ${MAKE} -f "${srctree}/scripts/Makefile.modpost" vmlinux.o
 226
 227 info MODINFO modules.builtin.modinfo
 228 ${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo
 229
 230 btf_kernel_bin_o=""
 231 if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then
 232         if gen_btf .tmp_vmlinux.btf .btf.kernel.bin.o ; then
 233                 btf_kernel_bin_o=.btf.kernel.bin.o
 234         fi
 235 fi
 236
 237 kallsymso=""
 238 kallsyms_vmlinux=""
 239 if [ -n "${CONFIG_KALLSYMS}" ]; then
 240
 241         # kallsyms support
 242         # Generate section listing all symbols and add it into vmlinux
 243         # It's a three step process:
 244         # 1)  Link .tmp_vmlinux1 so it has all symbols and sections,
 245         #     but __kallsyms is empty.
 246         #     Running kallsyms on that gives us .tmp_kallsyms1.o with
 247         #     the right size
 248         # 2)  Link .tmp_vmlinux2 so it now has a __kallsyms section of
 249         #     the right size, but due to the added section, some
 250         #     addresses have shifted.
 251         #     From here, we generate a correct .tmp_kallsyms2.o
 252         # 3)  That link may have expanded the kernel image enough that
 253         #     more linker branch stubs / trampolines had to be added, which
 254         #     introduces new names, which further expands kallsyms. Do another
 255         #     pass if that is the case. In theory it's possible this results
 256         #     in even more stubs, but unlikely.
 257         #     KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
 258         #     other bugs.
 259         # 4)  The correct ${kallsymso} is linked into the final vmlinux.
 260         #
 261         # a)  Verify that the System.map from vmlinux matches the map from
 262         #     ${kallsymso}.
 263
 264         kallsymso=.tmp_kallsyms2.o
 265         kallsyms_vmlinux=.tmp_vmlinux2
 266
 267         # step 1
 268         vmlinux_link .tmp_vmlinux1 ${btf_kernel_bin_o}
 269         kallsyms .tmp_vmlinux1 .tmp_kallsyms1.o
 270
 271         # step 2
 272         vmlinux_link .tmp_vmlinux2 .tmp_kallsyms1.o ${btf_kernel_bin_o}
 273         kallsyms .tmp_vmlinux2 .tmp_kallsyms2.o
 274
 275         # step 3
 276         size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" .tmp_kallsyms1.o)
 277         size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" .tmp_kallsyms2.o)
 278
 279         if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
 280                 kallsymso=.tmp_kallsyms3.o
 281                 kallsyms_vmlinux=.tmp_vmlinux3
 282
 283                 vmlinux_link .tmp_vmlinux3 .tmp_kallsyms2.o ${btf_kernel_bin_o}
 284                 kallsyms .tmp_vmlinux3 .tmp_kallsyms3.o
 285         fi
 286 fi
 287
 288 info LD vmlinux
 289 vmlinux_link vmlinux "${kallsymso}" "${btf_kernel_bin_o}"
 290
 291 if [ -n "${CONFIG_BUILDTIME_EXTABLE_SORT}" ]; then
 292         info SORTEX vmlinux
 293         sortextable vmlinux
 294 fi
 295
 296 info SYSMAP System.map
 297 mksysmap vmlinux System.map
 298
 299 # step a (see comment above)
 300 if [ -n "${CONFIG_KALLSYMS}" ]; then
 301         mksysmap ${kallsyms_vmlinux} .tmp_System.map
 302
 303         if ! cmp -s System.map .tmp_System.map; then
 304                 echo >&2 Inconsistent kallsyms data
 305                 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
 306                 exit 1
 307         fi
 308 fi