scripts/link-vmlinux.sh

   1 #!/bin/sh
   2 #
   3 # link vmlinux
   4 #
   5 # vmlinux is linked from the objects selected by $(KBUILD_VMLINUX_INIT) and
   6 # $(KBUILD_VMLINUX_MAIN) and $(KBUILD_VMLINUX_LIBS). Most are built-in.a files
   7 # from top-level directories in the kernel tree, others are specified in
   8 # arch/$(ARCH)/Makefile. Ordering when linking is important, and
   9 # $(KBUILD_VMLINUX_INIT) must be first. $(KBUILD_VMLINUX_LIBS) are archives
  10 # which are linked conditionally (not within --whole-archive), and do not
  11 # require symbol indexes added.
  12 #
  13 # vmlinux
  14 #   ^
  15 #   |
  16 #   +-< $(KBUILD_VMLINUX_INIT)
  17 #   |   +--< init/version.o + more
  18 #   |
  19 #   +--< $(KBUILD_VMLINUX_MAIN)
  20 #   |    +--< drivers/built-in.a mm/built-in.a + more
  21 #   |
  22 #   +--< $(KBUILD_VMLINUX_LIBS)
  23 #   |    +--< lib/lib.a + more
  24 #   |
  25 #   +-< ${kallsymso} (see description in KALLSYMS section)
  26 #
  27 # vmlinux version (uname -v) cannot be updated during normal
  28 # descending-into-subdirs phase since we do not yet know if we need to
  29 # update vmlinux.
  30 # Therefore this step is delayed until just before final link of vmlinux.
  31 #
  32 # System.map is generated to document addresses of all kernel symbols
  33
  34 # Error out on error
  35 set -e
  36
  37 # Nice output in kbuild format
  38 # Will be supressed by "make -s"
  39 info()
  40 {
  41         if [ "${quiet}" != "silent_" ]; then
  42                 printf "  %-7s %s\n" ${1} ${2}
  43         fi
  44 }
  45
  46 # Thin archive build here makes a final archive with symbol table and indexes
  47 # from vmlinux objects INIT and MAIN, which can be used as input to linker.
  48 # KBUILD_VMLINUX_LIBS archives should already have symbol table and indexes
  49 # added.
  50 #
  51 # Traditional incremental style of link does not require this step
  52 #
  53 # built-in.a output file
  54 #
  55 archive_builtin()
  56 {
  57         info AR built-in.a
  58         rm -f built-in.a;
  59         ${AR} rcsTP${KBUILD_ARFLAGS} built-in.a                 \
  60                                 ${KBUILD_VMLINUX_INIT}          \
  61                                 ${KBUILD_VMLINUX_MAIN}
  62
  63         # rebuild with llvm-ar to update the symbol table
  64         if [ -n "${CONFIG_LTO_CLANG}" ]; then
  65                 mv -f built-in.a built-in.a.tmp
  66                 ${LLVM_AR} rcsT${KBUILD_ARFLAGS} built-in.a $(${AR} t built-in.a.tmp)
  67                 rm -f built-in.a.tmp
  68         fi
  69 }
  70
  71 # If CONFIG_LTO_CLANG is selected, collect generated symbol versions into
  72 # .tmp_symversions
  73 modversions()
  74 {
  75         if [ -z "${CONFIG_LTO_CLANG}" ]; then
  76                 return
  77         fi
  78
  79         if [ -z "${CONFIG_MODVERSIONS}" ]; then
  80                 return
  81         fi
  82
  83         rm -f .tmp_symversions
  84
  85         for a in built-in.a ${KBUILD_VMLINUX_LIBS}; do
  86                 for o in $(${AR} t $a); do
  87                         if [ -f ${o}.symversions ]; then
  88                                 cat ${o}.symversions >> .tmp_symversions
  89                         fi
  90                 done
  91         done
  92
  93         echo "-T .tmp_symversions"
  94 }
  95
  96 # Link of vmlinux.o used for section mismatch analysis
  97 # ${1} output file
  98 modpost_link()
  99 {
 100         local objects
 101
 102         objects="--whole-archive                                \
 103                 built-in.a                                      \
 104                 --no-whole-archive                              \
 105                 --start-group                                   \
 106                 ${KBUILD_VMLINUX_LIBS}                          \
 107                 --end-group"
 108
 109         if [ -n "${CONFIG_LTO_CLANG}" ]; then
 110                 # This might take a while, so indicate that we're doing
 111                 # an LTO link
 112                 info LTO vmlinux.o
 113         fi
 114
 115         ${LD} ${LDFLAGS} -r -o ${1} $(modversions) ${objects}
 116 }
 117
 118 # If CONFIG_LTO_CLANG is selected, we postpone running recordmcount until
 119 # we have compiled LLVM IR to an object file.
 120 recordmcount()
 121 {
 122         if [ -z "${CONFIG_LTO_CLANG}" ]; then
 123                 return
 124         fi
 125
 126         if [ -n "${CONFIG_FTRACE_MCOUNT_RECORD}" ]; then
 127                 scripts/recordmcount ${RECORDMCOUNT_FLAGS} $*
 128         fi
 129 }
 130
 131 # Link of vmlinux
 132 # ${1} - optional extra .o files
 133 # ${2} - output file
 134 vmlinux_link()
 135 {
 136         local lds="${objtree}/${KBUILD_LDS}"
 137         local objects
 138
 139         if [ "${SRCARCH}" != "um" ]; then
 140                 if [ -z "${CONFIG_LTO_CLANG}" ]; then
 141                         objects="--whole-archive                \
 142                                 built-in.a                      \
 143                                 --no-whole-archive              \
 144                                 --start-group                   \
 145                                 ${KBUILD_VMLINUX_LIBS}          \
 146                                 --end-group                     \
 147                                 ${1}"
 148                 else
 149                         objects="--start-group                  \
 150                                 vmlinux.o                       \
 151                                 --end-group                     \
 152                                 ${1}"
 153                 fi
 154
 155                 ${LD} ${LDFLAGS} ${LDFLAGS_vmlinux} -o ${2}     \
 156                         -T ${lds} ${objects}
 157         else
 158                 objects="-Wl,--whole-archive                    \
 159                         built-in.a                              \
 160                         -Wl,--no-whole-archive                  \
 161                         -Wl,--start-group                       \
 162                         ${KBUILD_VMLINUX_LIBS}                  \
 163                         -Wl,--end-group                         \
 164                         ${1}"
 165
 166                 ${CC} ${CFLAGS_vmlinux} -o ${2}                 \
 167                         -Wl,-T,${lds}                           \
 168                         ${objects}                              \
 169                         -lutil -lrt -lpthread
 170                 rm -f linux
 171         fi
 172 }
 173
 174 # Create ${2} .o file with all symbols from the ${1} object file
 175 kallsyms()
 176 {
 177         info KSYM ${2}
 178         local kallsymopt;
 179
 180         if [ -n "${CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX}" ]; then
 181                 kallsymopt="${kallsymopt} --symbol-prefix=_"
 182         fi
 183
 184         if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
 185                 kallsymopt="${kallsymopt} --all-symbols"
 186         fi
 187
 188         if [ -n "${CONFIG_ARM}" ] && [ -z "${CONFIG_XIP_KERNEL}" ] && [ -n "${CONFIG_PAGE_OFFSET}" ]; then
 189                 kallsymopt="${kallsymopt} --page-offset=$CONFIG_PAGE_OFFSET"
 190         fi
 191
 192         if [ -n "${CONFIG_X86_64}" ]; then
 193                 kallsymopt="${kallsymopt} --absolute-percpu"
 194         fi
 195
 196         local aflags="${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL}               \
 197                       ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS}"
 198
 199         ${NM} -n ${1} | \
 200                 scripts/kallsyms ${kallsymopt} | \
 201                 ${CC} ${aflags} -c -o ${2} -x assembler-with-cpp -
 202 }
 203
 204 # Create map file with all symbols from ${1}
 205 # See mksymap for additional details
 206 mksysmap()
 207 {
 208         ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
 209 }
 210
 211 sortextable()
 212 {
 213         ${objtree}/scripts/sortextable ${1}
 214 }
 215
 216 # Delete output files in case of error
 217 cleanup()
 218 {
 219         rm -f .old_version
 220         rm -f .tmp_System.map
 221         rm -f .tmp_kallsyms*
 222         rm -f .tmp_symversions
 223         rm -f .tmp_version
 224         rm -f .tmp_vmlinux*
 225         rm -f built-in.a
 226         rm -f System.map
 227         rm -f vmlinux
 228         rm -f vmlinux.o
 229 }
 230
 231 on_exit()
 232 {
 233         if [ $? -ne 0 ]; then
 234                 cleanup
 235         fi
 236 }
 237 trap on_exit EXIT
 238
 239 on_signals()
 240 {
 241         exit 1
 242 }
 243 trap on_signals HUP INT QUIT TERM
 244
 245 #
 246 #
 247 # Use "make V=1" to debug this script
 248 case "${KBUILD_VERBOSE}" in
 249 *1*)
 250         set -x
 251         ;;
 252 esac
 253
 254 if [ "$1" = "clean" ]; then
 255         cleanup
 256         exit 0
 257 fi
 258
 259 # We need access to CONFIG_ symbols
 260 case "${KCONFIG_CONFIG}" in
 261 */*)
 262         . "${KCONFIG_CONFIG}"
 263         ;;
 264 *)
 265         # Force using a file from the current directory
 266         . "./${KCONFIG_CONFIG}"
 267 esac
 268
 269 # Update version
 270 info GEN .version
 271 if [ ! -r .version ]; then
 272         rm -f .version;
 273         echo 1 >.version;
 274 else
 275         mv .version .old_version;
 276         expr 0$(cat .old_version) + 1 >.version;
 277 fi;
 278
 279 # final build of init/
 280 ${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init
 281
 282 archive_builtin
 283
 284 #link vmlinux.o
 285 modpost_link vmlinux.o
 286
 287 # modpost vmlinux.o to check for section mismatches
 288 ${MAKE} -f "${srctree}/scripts/Makefile.modpost" vmlinux.o
 289
 290 if [ -n "${CONFIG_LTO_CLANG}" ]; then
 291         # Call recordmcount if needed
 292         recordmcount vmlinux.o
 293 fi
 294
 295 kallsymso=""
 296 kallsyms_vmlinux=""
 297 if [ -n "${CONFIG_KALLSYMS}" ]; then
 298
 299         # kallsyms support
 300         # Generate section listing all symbols and add it into vmlinux
 301         # It's a three step process:
 302         # 1)  Link .tmp_vmlinux1 so it has all symbols and sections,
 303         #     but __kallsyms is empty.
 304         #     Running kallsyms on that gives us .tmp_kallsyms1.o with
 305         #     the right size
 306         # 2)  Link .tmp_vmlinux2 so it now has a __kallsyms section of
 307         #     the right size, but due to the added section, some
 308         #     addresses have shifted.
 309         #     From here, we generate a correct .tmp_kallsyms2.o
 310         # 2a) We may use an extra pass as this has been necessary to
 311         #     woraround some alignment related bugs.
 312         #     KALLSYMS_EXTRA_PASS=1 is used to trigger this.
 313         # 3)  The correct ${kallsymso} is linked into the final vmlinux.
 314         #
 315         # a)  Verify that the System.map from vmlinux matches the map from
 316         #     ${kallsymso}.
 317
 318         kallsymso=.tmp_kallsyms2.o
 319         kallsyms_vmlinux=.tmp_vmlinux2
 320
 321         # step 1
 322         vmlinux_link "" .tmp_vmlinux1
 323         kallsyms .tmp_vmlinux1 .tmp_kallsyms1.o
 324
 325         # step 2
 326         vmlinux_link .tmp_kallsyms1.o .tmp_vmlinux2
 327         kallsyms .tmp_vmlinux2 .tmp_kallsyms2.o
 328
 329         # step 2a
 330         if [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
 331                 kallsymso=.tmp_kallsyms3.o
 332                 kallsyms_vmlinux=.tmp_vmlinux3
 333
 334                 vmlinux_link .tmp_kallsyms2.o .tmp_vmlinux3
 335
 336                 kallsyms .tmp_vmlinux3 .tmp_kallsyms3.o
 337         fi
 338 fi
 339
 340 info LD vmlinux
 341 vmlinux_link "${kallsymso}" vmlinux
 342
 343 if [ -n "${CONFIG_BUILDTIME_EXTABLE_SORT}" ]; then
 344         info SORTEX vmlinux
 345         sortextable vmlinux
 346 fi
 347
 348 info SYSMAP System.map
 349 mksysmap vmlinux System.map
 350
 351 # step a (see comment above)
 352 if [ -n "${CONFIG_KALLSYMS}" ]; then
 353         mksysmap ${kallsyms_vmlinux} .tmp_System.map
 354
 355         if ! cmp -s System.map .tmp_System.map; then
 356                 echo >&2 Inconsistent kallsyms data
 357                 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
 358                 exit 1
 359         fi
 360 fi
 361
 362 # We made a new kernel - delete old version file
 363 rm -f .old_version