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 $(KBUILD_VMLINUX_LIBS). Most are built-in.o files
   8 # from top-level directories in the kernel tree, others are specified in
   9 # arch/$(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.o mm/built-in.o + 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} ${2}
  44         fi
  45 }
  46
  47 # Thin archive build here makes a final archive with symbol table and indexes
  48 # from vmlinux objects INIT and MAIN, which can be used as input to linker.
  49 # KBUILD_VMLINUX_LIBS archives should already have symbol table and indexes
  50 # added.
  51 #
  52 # Traditional incremental style of link does not require this step
  53 #
  54 # built-in.o output file
  55 #
  56 archive_builtin()
  57 {
  58         if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then
  59                 info AR built-in.o
  60                 rm -f built-in.o;
  61                 ${AR} rcsTP${KBUILD_ARFLAGS} built-in.o                 \
  62                                         ${KBUILD_VMLINUX_INIT}          \
  63                                         ${KBUILD_VMLINUX_MAIN}
  64         fi
  65 }
  66
  67 # Link of vmlinux.o used for section mismatch analysis
  68 # ${1} output file
  69 modpost_link()
  70 {
  71         local objects
  72
  73         if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then
  74                 objects="--whole-archive                                \
  75                         built-in.o                                      \
  76                         --no-whole-archive                              \
  77                         --start-group                                   \
  78                         ${KBUILD_VMLINUX_LIBS}                          \
  79                         --end-group"
  80         else
  81                 objects="${KBUILD_VMLINUX_INIT}                         \
  82                         --start-group                                   \
  83                         ${KBUILD_VMLINUX_MAIN}                          \
  84                         ${KBUILD_VMLINUX_LIBS}                          \
  85                         --end-group"
  86         fi
  87         ${LD} ${LDFLAGS} -r -o ${1} ${objects}
  88 }
  89
  90 # Link of vmlinux
  91 # ${1} - optional extra .o files
  92 # ${2} - output file
  93 vmlinux_link()
  94 {
  95         local lds="${objtree}/${KBUILD_LDS}"
  96         local objects
  97
  98         if [ "${SRCARCH}" != "um" ]; then
  99                 if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then
 100                         objects="--whole-archive                        \
 101                                 built-in.o                              \
 102                                 --no-whole-archive                      \
 103                                 --start-group                           \
 104                                 ${KBUILD_VMLINUX_LIBS}                  \
 105                                 --end-group                             \
 106                                 ${1}"
 107                 else
 108                         objects="${KBUILD_VMLINUX_INIT}                 \
 109                                 --start-group                           \
 110                                 ${KBUILD_VMLINUX_MAIN}                  \
 111                                 ${KBUILD_VMLINUX_LIBS}                  \
 112                                 --end-group                             \
 113                                 ${1}"
 114                 fi
 115
 116                 ${LD} ${LDFLAGS} ${LDFLAGS_vmlinux} -o ${2}             \
 117                         -T ${lds} ${objects}
 118         else
 119                 if [ -n "${CONFIG_THIN_ARCHIVES}" ]; then
 120                         objects="-Wl,--whole-archive                    \
 121                                 built-in.o                              \
 122                                 -Wl,--no-whole-archive                  \
 123                                 -Wl,--start-group                       \
 124                                 ${KBUILD_VMLINUX_LIBS}                  \
 125                                 -Wl,--end-group                         \
 126                                 ${1}"
 127                 else
 128                         objects="${KBUILD_VMLINUX_INIT}                 \
 129                                 -Wl,--start-group                       \
 130                                 ${KBUILD_VMLINUX_MAIN}                  \
 131                                 ${KBUILD_VMLINUX_LIBS}                  \
 132                                 -Wl,--end-group                         \
 133                                 ${1}"
 134                 fi
 135
 136                 ${CC} ${CFLAGS_vmlinux} -o ${2}                         \
 137                         -Wl,-T,${lds}                                   \
 138                         ${objects}                                      \
 139                         -lutil -lrt -lpthread
 140                 rm -f linux
 141         fi
 142 }
 143
 144
 145 # Create ${2} .o file with all symbols from the ${1} object file
 146 kallsyms()
 147 {
 148         info KSYM ${2}
 149         local kallsymopt;
 150
 151         if [ -n "${CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX}" ]; then
 152                 kallsymopt="${kallsymopt} --symbol-prefix=_"
 153         fi
 154
 155         if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
 156                 kallsymopt="${kallsymopt} --all-symbols"
 157         fi
 158
 159         if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
 160                 kallsymopt="${kallsymopt} --absolute-percpu"
 161         fi
 162
 163         if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then
 164                 kallsymopt="${kallsymopt} --base-relative"
 165         fi
 166
 167         local aflags="${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL}               \
 168                       ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS}"
 169
 170         local afile="`basename ${2} .o`.S"
 171
 172         ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${afile}
 173         ${CC} ${aflags} -c -o ${2} ${afile}
 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 .tmp_System.map
 192         rm -f .tmp_kallsyms*
 193         rm -f .tmp_vmlinux*
 194         rm -f built-in.o
 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 [ "$1" = "clean" ]; then
 224         cleanup
 225         exit 0
 226 fi
 227
 228 # We need access to CONFIG_ symbols
 229 case "${KCONFIG_CONFIG}" in
 230 */*)
 231         . "${KCONFIG_CONFIG}"
 232         ;;
 233 *)
 234         # Force using a file from the current directory
 235         . "./${KCONFIG_CONFIG}"
 236 esac
 237
 238 # Update version
 239 info GEN .version
 240 if [ -r .version ]; then
 241         VERSION=$(expr 0$(cat .version) + 1)
 242         echo $VERSION > .version
 243 else
 244         rm -f .version
 245         echo 1 > .version
 246 fi;
 247
 248 # final build of init/
 249 ${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init GCC_PLUGINS_CFLAGS="${GCC_PLUGINS_CFLAGS}"
 250
 251 archive_builtin
 252
 253 #link vmlinux.o
 254 info LD vmlinux.o
 255 modpost_link vmlinux.o
 256
 257 # modpost vmlinux.o to check for section mismatches
 258 ${MAKE} -f "${srctree}/scripts/Makefile.modpost" vmlinux.o
 259
 260 kallsymso=""
 261 kallsyms_vmlinux=""
 262 if [ -n "${CONFIG_KALLSYMS}" ]; then
 263
 264         # kallsyms support
 265         # Generate section listing all symbols and add it into vmlinux
 266         # It's a three step process:
 267         # 1)  Link .tmp_vmlinux1 so it has all symbols and sections,
 268         #     but __kallsyms is empty.
 269         #     Running kallsyms on that gives us .tmp_kallsyms1.o with
 270         #     the right size
 271         # 2)  Link .tmp_vmlinux2 so it now has a __kallsyms section of
 272         #     the right size, but due to the added section, some
 273         #     addresses have shifted.
 274         #     From here, we generate a correct .tmp_kallsyms2.o
 275         # 3)  That link may have expanded the kernel image enough that
 276         #     more linker branch stubs / trampolines had to be added, which
 277         #     introduces new names, which further expands kallsyms. Do another
 278         #     pass if that is the case. In theory it's possible this results
 279         #     in even more stubs, but unlikely.
 280         #     KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
 281         #     other bugs.
 282         # 4)  The correct ${kallsymso} is linked into the final vmlinux.
 283         #
 284         # a)  Verify that the System.map from vmlinux matches the map from
 285         #     ${kallsymso}.
 286
 287         kallsymso=.tmp_kallsyms2.o
 288         kallsyms_vmlinux=.tmp_vmlinux2
 289
 290         # step 1
 291         vmlinux_link "" .tmp_vmlinux1
 292         kallsyms .tmp_vmlinux1 .tmp_kallsyms1.o
 293
 294         # step 2
 295         vmlinux_link .tmp_kallsyms1.o .tmp_vmlinux2
 296         kallsyms .tmp_vmlinux2 .tmp_kallsyms2.o
 297
 298         # step 3
 299         size1=$(stat -c "%s" .tmp_kallsyms1.o)
 300         size2=$(stat -c "%s" .tmp_kallsyms2.o)
 301
 302         if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
 303                 kallsymso=.tmp_kallsyms3.o
 304                 kallsyms_vmlinux=.tmp_vmlinux3
 305
 306                 vmlinux_link .tmp_kallsyms2.o .tmp_vmlinux3
 307
 308                 kallsyms .tmp_vmlinux3 .tmp_kallsyms3.o
 309         fi
 310 fi
 311
 312 info LD vmlinux
 313 vmlinux_link "${kallsymso}" vmlinux
 314
 315 if [ -n "${CONFIG_BUILDTIME_EXTABLE_SORT}" ]; then
 316         info SORTEX vmlinux
 317         sortextable vmlinux
 318 fi
 319
 320 info SYSMAP System.map
 321 mksysmap vmlinux System.map
 322
 323 # step a (see comment above)
 324 if [ -n "${CONFIG_KALLSYMS}" ]; then
 325         mksysmap ${kallsyms_vmlinux} .tmp_System.map
 326
 327         if ! cmp -s System.map .tmp_System.map; then
 328                 echo >&2 Inconsistent kallsyms data
 329                 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
 330                 exit 1
 331         fi
 332 fi