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_INIT) and
   7 # $(KBUILD_VMLINUX_MAIN) and $(KBUILD_VMLINUX_LIBS). Most are built-in.a files
   8 # from top-level directories in the kernel tree, others are specified in
   9 # arch/$(ARCH)/Makefile. Ordering when linking is important, and
  10 # $(KBUILD_VMLINUX_INIT) must be first. $(KBUILD_VMLINUX_LIBS) are archives
  11 # which are linked conditionally (not within --whole-archive), and do not
  12 # require symbol indexes added.
  13 #
  14 # vmlinux
  15 #   ^
  16 #   |
  17 #   +-< $(KBUILD_VMLINUX_INIT)
  18 #   |   +--< init/version.o + more
  19 #   |
  20 #   +--< $(KBUILD_VMLINUX_MAIN)
  21 #   |    +--< drivers/built-in.a mm/built-in.a + more
  22 #   |
  23 #   +--< $(KBUILD_VMLINUX_LIBS)
  24 #   |    +--< lib/lib.a + more
  25 #   |
  26 #   +-< ${kallsymso} (see description in KALLSYMS section)
  27 #
  28 # vmlinux version (uname -v) cannot be updated during normal
  29 # descending-into-subdirs phase since we do not yet know if we need to
  30 # update vmlinux.
  31 # Therefore this step is delayed until just before final link of vmlinux.
  32 #
  33 # System.map is generated to document addresses of all kernel symbols
  34
  35 # Error out on error
  36 set -e
  37
  38 # Nice output in kbuild format
  39 # Will be supressed by "make -s"
  40 info()
  41 {
  42         if [ "${quiet}" != "silent_" ]; then
  43                 printf "  %-7s %s\n" ${1} ${2}
  44         fi
  45 }
  46
  47 # Thin archive build here makes a final archive with symbol table and indexes
  48 # from vmlinux objects INIT and MAIN, which can be used as input to linker.
  49 # KBUILD_VMLINUX_LIBS archives should already have symbol table and indexes
  50 # added.
  51 #
  52 # Traditional incremental style of link does not require this step
  53 #
  54 # built-in.a output file
  55 #
  56 archive_builtin()
  57 {
  58         info AR built-in.a
  59         rm -f built-in.a;
  60         ${AR} rcsTP${KBUILD_ARFLAGS} built-in.a                 \
  61                                 ${KBUILD_VMLINUX_INIT}          \
  62                                 ${KBUILD_VMLINUX_MAIN}
  63 }
  64
  65 # Link of vmlinux.o used for section mismatch analysis
  66 # ${1} output file
  67 modpost_link()
  68 {
  69         local objects
  70
  71         objects="--whole-archive                                \
  72                 built-in.a                                      \
  73                 --no-whole-archive                              \
  74                 --start-group                                   \
  75                 ${KBUILD_VMLINUX_LIBS}                          \
  76                 --end-group"
  77
  78         ${LD} ${LDFLAGS} -r -o ${1} ${objects}
  79 }
  80
  81 # Link of vmlinux
  82 # ${1} - optional extra .o files
  83 # ${2} - output file
  84 vmlinux_link()
  85 {
  86         local lds="${objtree}/${KBUILD_LDS}"
  87         local objects
  88
  89         if [ "${SRCARCH}" != "um" ]; then
  90                 objects="--whole-archive                        \
  91                         built-in.a                              \
  92                         --no-whole-archive                      \
  93                         --start-group                           \
  94                         ${KBUILD_VMLINUX_LIBS}                  \
  95                         --end-group                             \
  96                         ${1}"
  97
  98                 ${LD} ${LDFLAGS} ${LDFLAGS_vmlinux} -o ${2}     \
  99                         -T ${lds} ${objects}
 100         else
 101                 objects="-Wl,--whole-archive                    \
 102                         built-in.a                              \
 103                         -Wl,--no-whole-archive                  \
 104                         -Wl,--start-group                       \
 105                         ${KBUILD_VMLINUX_LIBS}                  \
 106                         -Wl,--end-group                         \
 107                         ${1}"
 108
 109                 ${CC} ${CFLAGS_vmlinux} -o ${2}                 \
 110                         -Wl,-T,${lds}                           \
 111                         ${objects}                              \
 112                         -lutil -lrt -lpthread
 113                 rm -f linux
 114         fi
 115 }
 116
 117
 118 # Create ${2} .o file with all symbols from the ${1} object file
 119 kallsyms()
 120 {
 121         info KSYM ${2}
 122         local kallsymopt;
 123
 124         if [ -n "${CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX}" ]; then
 125                 kallsymopt="${kallsymopt} --symbol-prefix=_"
 126         fi
 127
 128         if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
 129                 kallsymopt="${kallsymopt} --all-symbols"
 130         fi
 131
 132         if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
 133                 kallsymopt="${kallsymopt} --absolute-percpu"
 134         fi
 135
 136         if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then
 137                 kallsymopt="${kallsymopt} --base-relative"
 138         fi
 139
 140         local aflags="${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL}               \
 141                       ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS}"
 142
 143         local afile="`basename ${2} .o`.S"
 144
 145         ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${afile}
 146         ${CC} ${aflags} -c -o ${2} ${afile}
 147 }
 148
 149 # Create map file with all symbols from ${1}
 150 # See mksymap for additional details
 151 mksysmap()
 152 {
 153         ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
 154 }
 155
 156 sortextable()
 157 {
 158         ${objtree}/scripts/sortextable ${1}
 159 }
 160
 161 # Delete output files in case of error
 162 cleanup()
 163 {
 164         rm -f .tmp_System.map
 165         rm -f .tmp_kallsyms*
 166         rm -f .tmp_vmlinux*
 167         rm -f built-in.a
 168         rm -f System.map
 169         rm -f vmlinux
 170         rm -f vmlinux.o
 171 }
 172
 173 on_exit()
 174 {
 175         if [ $? -ne 0 ]; then
 176                 cleanup
 177         fi
 178 }
 179 trap on_exit EXIT
 180
 181 on_signals()
 182 {
 183         exit 1
 184 }
 185 trap on_signals HUP INT QUIT TERM
 186
 187 #
 188 #
 189 # Use "make V=1" to debug this script
 190 case "${KBUILD_VERBOSE}" in
 191 *1*)
 192         set -x
 193         ;;
 194 esac
 195
 196 if [ "$1" = "clean" ]; then
 197         cleanup
 198         exit 0
 199 fi
 200
 201 # We need access to CONFIG_ symbols
 202 case "${KCONFIG_CONFIG}" in
 203 */*)
 204         . "${KCONFIG_CONFIG}"
 205         ;;
 206 *)
 207         # Force using a file from the current directory
 208         . "./${KCONFIG_CONFIG}"
 209 esac
 210
 211 # Update version
 212 info GEN .version
 213 if [ -r .version ]; then
 214         VERSION=$(expr 0$(cat .version) + 1)
 215         echo $VERSION > .version
 216 else
 217         rm -f .version
 218         echo 1 > .version
 219 fi;
 220
 221 # final build of init/
 222 ${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init
 223
 224 archive_builtin
 225
 226 #link vmlinux.o
 227 info LD vmlinux.o
 228 modpost_link vmlinux.o
 229
 230 # modpost vmlinux.o to check for section mismatches
 231 ${MAKE} -f "${srctree}/scripts/Makefile.modpost" vmlinux.o
 232
 233 kallsymso=""
 234 kallsyms_vmlinux=""
 235 if [ -n "${CONFIG_KALLSYMS}" ]; then
 236
 237         # kallsyms support
 238         # Generate section listing all symbols and add it into vmlinux
 239         # It's a three step process:
 240         # 1)  Link .tmp_vmlinux1 so it has all symbols and sections,
 241         #     but __kallsyms is empty.
 242         #     Running kallsyms on that gives us .tmp_kallsyms1.o with
 243         #     the right size
 244         # 2)  Link .tmp_vmlinux2 so it now has a __kallsyms section of
 245         #     the right size, but due to the added section, some
 246         #     addresses have shifted.
 247         #     From here, we generate a correct .tmp_kallsyms2.o
 248         # 3)  That link may have expanded the kernel image enough that
 249         #     more linker branch stubs / trampolines had to be added, which
 250         #     introduces new names, which further expands kallsyms. Do another
 251         #     pass if that is the case. In theory it's possible this results
 252         #     in even more stubs, but unlikely.
 253         #     KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
 254         #     other bugs.
 255         # 4)  The correct ${kallsymso} is linked into the final vmlinux.
 256         #
 257         # a)  Verify that the System.map from vmlinux matches the map from
 258         #     ${kallsymso}.
 259
 260         kallsymso=.tmp_kallsyms2.o
 261         kallsyms_vmlinux=.tmp_vmlinux2
 262
 263         # step 1
 264         vmlinux_link "" .tmp_vmlinux1
 265         kallsyms .tmp_vmlinux1 .tmp_kallsyms1.o
 266
 267         # step 2
 268         vmlinux_link .tmp_kallsyms1.o .tmp_vmlinux2
 269         kallsyms .tmp_vmlinux2 .tmp_kallsyms2.o
 270
 271         # step 3
 272         size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" .tmp_kallsyms1.o)
 273         size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" .tmp_kallsyms2.o)
 274
 275         if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
 276                 kallsymso=.tmp_kallsyms3.o
 277                 kallsyms_vmlinux=.tmp_vmlinux3
 278
 279                 vmlinux_link .tmp_kallsyms2.o .tmp_vmlinux3
 280
 281                 kallsyms .tmp_vmlinux3 .tmp_kallsyms3.o
 282         fi
 283 fi
 284
 285 info LD vmlinux
 286 vmlinux_link "${kallsymso}" vmlinux
 287
 288 if [ -n "${CONFIG_BUILDTIME_EXTABLE_SORT}" ]; then
 289         info SORTEX vmlinux
 290         sortextable vmlinux
 291 fi
 292
 293 info SYSMAP System.map
 294 mksysmap vmlinux System.map
 295
 296 # step a (see comment above)
 297 if [ -n "${CONFIG_KALLSYMS}" ]; then
 298         mksysmap ${kallsyms_vmlinux} .tmp_System.map
 299
 300         if ! cmp -s System.map .tmp_System.map; then
 301                 echo >&2 Inconsistent kallsyms data
 302                 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
 303                 exit 1
 304         fi
 305 fi