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}, ${3}, ... - optional extra .o files
  61 vmlinux_link()
  62 {
  63         local lds="${objtree}/${KBUILD_LDS}"
  64         local output=${1}
  65         local objects
  66
  67         info LD ${output}
  68
  69         # skip output file argument
  70         shift
  71
  72         if [ "${SRCARCH}" != "um" ]; then
  73                 objects="--whole-archive                        \
  74                         ${KBUILD_VMLINUX_OBJS}                  \
  75                         --no-whole-archive                      \
  76                         --start-group                           \
  77                         ${KBUILD_VMLINUX_LIBS}                  \
  78                         --end-group                             \
  79                         ${@}"
  80
  81                 ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux}      \
  82                         -o ${output}                            \
  83                         -T ${lds} ${objects}
  84         else
  85                 objects="-Wl,--whole-archive                    \
  86                         ${KBUILD_VMLINUX_OBJS}                  \
  87                         -Wl,--no-whole-archive                  \
  88                         -Wl,--start-group                       \
  89                         ${KBUILD_VMLINUX_LIBS}                  \
  90                         -Wl,--end-group                         \
  91                         ${@}"
  92
  93                 ${CC} ${CFLAGS_vmlinux}                         \
  94                         -o ${output}                            \
  95                         -Wl,-T,${lds}                           \
  96                         ${objects}                              \
  97                         -lutil -lrt -lpthread
  98                 rm -f linux
  99         fi
 100 }
 101
 102 # generate .BTF typeinfo from DWARF debuginfo
 103 # ${1} - vmlinux image
 104 # ${2} - file to dump raw BTF data into
 105 gen_btf()
 106 {
 107         local pahole_ver
 108         local bin_arch
 109
 110         if ! [ -x "$(command -v ${PAHOLE})" ]; then
 111                 info "BTF" "${1}: pahole (${PAHOLE}) is not available"
 112                 return 1
 113         fi
 114
 115         pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
 116         if [ "${pahole_ver}" -lt "113" ]; then
 117                 info "BTF" "${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.13"
 118                 return 1
 119         fi
 120
 121         info "BTF" ${2}
 122         vmlinux_link ${1}
 123         LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1}
 124
 125         # dump .BTF section into raw binary file to link with final vmlinux
 126         bin_arch=$(LANG=C ${OBJDUMP} -f ${1} | grep architecture | \
 127                 cut -d, -f1 | cut -d' ' -f2)
 128         bin_format=$(LANG=C ${OBJDUMP} -f ${1} | grep 'file format' | \
 129                 awk '{print $4}')
 130         ${OBJCOPY} --change-section-address .BTF=0 \
 131                 --set-section-flags .BTF=alloc -O binary \
 132                 --only-section=.BTF ${1} .btf.vmlinux.bin
 133         ${OBJCOPY} -I binary -O ${bin_format} -B ${bin_arch} \
 134                 --rename-section .data=.BTF .btf.vmlinux.bin ${2}
 135 }
 136
 137 # Create ${2} .o file with all symbols from the ${1} object file
 138 kallsyms()
 139 {
 140         info KSYM ${2}
 141         local kallsymopt;
 142
 143         if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
 144                 kallsymopt="${kallsymopt} --all-symbols"
 145         fi
 146
 147         if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
 148                 kallsymopt="${kallsymopt} --absolute-percpu"
 149         fi
 150
 151         if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then
 152                 kallsymopt="${kallsymopt} --base-relative"
 153         fi
 154
 155         local aflags="${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL}               \
 156                       ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS}"
 157
 158         local afile="`basename ${2} .o`.S"
 159
 160         ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${afile}
 161         ${CC} ${aflags} -c -o ${2} ${afile}
 162 }
 163
 164 # Perform one step in kallsyms generation, including temporary linking of
 165 # vmlinux.
 166 kallsyms_step()
 167 {
 168         kallsymso_prev=${kallsymso}
 169         kallsymso=.tmp_kallsyms${1}.o
 170         kallsyms_vmlinux=.tmp_vmlinux${1}
 171
 172         vmlinux_link ${kallsyms_vmlinux} "${kallsymso_prev}" ${btf_vmlinux_bin_o}
 173         kallsyms ${kallsyms_vmlinux} ${kallsymso}
 174 }
 175
 176 # Create map file with all symbols from ${1}
 177 # See mksymap for additional details
 178 mksysmap()
 179 {
 180         ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
 181 }
 182
 183 sortextable()
 184 {
 185         ${objtree}/scripts/sortextable ${1}
 186 }
 187
 188 # Delete output files in case of error
 189 cleanup()
 190 {
 191         rm -f .btf.*
 192         rm -f .tmp_System.map
 193         rm -f .tmp_kallsyms*
 194         rm -f .tmp_vmlinux*
 195         rm -f System.map
 196         rm -f vmlinux
 197         rm -f vmlinux.o
 198 }
 199
 200 on_exit()
 201 {
 202         if [ $? -ne 0 ]; then
 203                 cleanup
 204         fi
 205 }
 206 trap on_exit EXIT
 207
 208 on_signals()
 209 {
 210         exit 1
 211 }
 212 trap on_signals HUP INT QUIT TERM
 213
 214 #
 215 #
 216 # Use "make V=1" to debug this script
 217 case "${KBUILD_VERBOSE}" in
 218 *1*)
 219         set -x
 220         ;;
 221 esac
 222
 223 if [ "$1" = "clean" ]; then
 224         cleanup
 225         exit 0
 226 fi
 227
 228 # We need access to CONFIG_ symbols
 229 . include/config/auto.conf
 230
 231 # Update version
 232 info GEN .version
 233 if [ -r .version ]; then
 234         VERSION=$(expr 0$(cat .version) + 1)
 235         echo $VERSION > .version
 236 else
 237         rm -f .version
 238         echo 1 > .version
 239 fi;
 240
 241 # final build of init/
 242 ${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init
 243
 244 #link vmlinux.o
 245 info LD vmlinux.o
 246 modpost_link vmlinux.o
 247
 248 # modpost vmlinux.o to check for section mismatches
 249 ${MAKE} -f "${srctree}/scripts/Makefile.modpost" MODPOST_VMLINUX=1
 250
 251 info MODINFO modules.builtin.modinfo
 252 ${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo
 253
 254 btf_vmlinux_bin_o=""
 255 if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then
 256         if gen_btf .tmp_vmlinux.btf .btf.vmlinux.bin.o ; then
 257                 btf_vmlinux_bin_o=.btf.vmlinux.bin.o
 258         else
 259                 echo >&2 "Failed to generate BTF for vmlinux"
 260                 echo >&2 "Try to disable CONFIG_DEBUG_INFO_BTF"
 261                 exit 1
 262         fi
 263 fi
 264
 265 kallsymso=""
 266 kallsymso_prev=""
 267 kallsyms_vmlinux=""
 268 if [ -n "${CONFIG_KALLSYMS}" ]; then
 269
 270         # kallsyms support
 271         # Generate section listing all symbols and add it into vmlinux
 272         # It's a three step process:
 273         # 1)  Link .tmp_vmlinux1 so it has all symbols and sections,
 274         #     but __kallsyms is empty.
 275         #     Running kallsyms on that gives us .tmp_kallsyms1.o with
 276         #     the right size
 277         # 2)  Link .tmp_vmlinux2 so it now has a __kallsyms section of
 278         #     the right size, but due to the added section, some
 279         #     addresses have shifted.
 280         #     From here, we generate a correct .tmp_kallsyms2.o
 281         # 3)  That link may have expanded the kernel image enough that
 282         #     more linker branch stubs / trampolines had to be added, which
 283         #     introduces new names, which further expands kallsyms. Do another
 284         #     pass if that is the case. In theory it's possible this results
 285         #     in even more stubs, but unlikely.
 286         #     KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
 287         #     other bugs.
 288         # 4)  The correct ${kallsymso} is linked into the final vmlinux.
 289         #
 290         # a)  Verify that the System.map from vmlinux matches the map from
 291         #     ${kallsymso}.
 292
 293         kallsyms_step 1
 294         kallsyms_step 2
 295
 296         # step 3
 297         size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso_prev})
 298         size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" ${kallsymso})
 299
 300         if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
 301                 kallsyms_step 3
 302         fi
 303 fi
 304
 305 vmlinux_link vmlinux "${kallsymso}" ${btf_vmlinux_bin_o}
 306
 307 if [ -n "${CONFIG_BUILDTIME_EXTABLE_SORT}" ]; then
 308         info SORTEX vmlinux
 309         sortextable vmlinux
 310 fi
 311
 312 info SYSMAP System.map
 313 mksysmap vmlinux System.map
 314
 315 # step a (see comment above)
 316 if [ -n "${CONFIG_KALLSYMS}" ]; then
 317         mksysmap ${kallsyms_vmlinux} .tmp_System.map
 318
 319         if ! cmp -s System.map .tmp_System.map; then
 320                 echo >&2 Inconsistent kallsyms data
 321                 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
 322                 exit 1
 323         fi
 324 fi