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} - optional extra .o files
  60 # ${2} - output file
  61 vmlinux_link()
  62 {
  63         local lds="${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                         ${1}"
  74
  75                 ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} -o ${2}      \
  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                         ${1}"
  85
  86                 ${CC} ${CFLAGS_vmlinux} -o ${2}                 \
  87                         -Wl,-T,${lds}                           \
  88                         ${objects}                              \
  89                         -lutil -lrt -lpthread
  90                 rm -f linux
  91         fi
  92 }
  93
  94 # generate .BTF typeinfo from DWARF debuginfo
  95 gen_btf()
  96 {
  97         local pahole_ver;
  98
  99         if ! [ -x "$(command -v ${PAHOLE})" ]; then
 100                 info "BTF" "${1}: pahole (${PAHOLE}) is not available"
 101                 return 0
 102         fi
 103
 104         pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
 105         if [ "${pahole_ver}" -lt "113" ]; then
 106                 info "BTF" "${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.13"
 107                 return 0
 108         fi
 109
 110         info "BTF" ${1}
 111         LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1}
 112 }
 113
 114 # Create ${2} .o file with all symbols from the ${1} object file
 115 kallsyms()
 116 {
 117         info KSYM ${2}
 118         local kallsymopt;
 119
 120         if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then
 121                 kallsymopt="${kallsymopt} --all-symbols"
 122         fi
 123
 124         if [ -n "${CONFIG_KALLSYMS_ABSOLUTE_PERCPU}" ]; then
 125                 kallsymopt="${kallsymopt} --absolute-percpu"
 126         fi
 127
 128         if [ -n "${CONFIG_KALLSYMS_BASE_RELATIVE}" ]; then
 129                 kallsymopt="${kallsymopt} --base-relative"
 130         fi
 131
 132         local aflags="${KBUILD_AFLAGS} ${KBUILD_AFLAGS_KERNEL}               \
 133                       ${NOSTDINC_FLAGS} ${LINUXINCLUDE} ${KBUILD_CPPFLAGS}"
 134
 135         local afile="`basename ${2} .o`.S"
 136
 137         ${NM} -n ${1} | scripts/kallsyms ${kallsymopt} > ${afile}
 138         ${CC} ${aflags} -c -o ${2} ${afile}
 139 }
 140
 141 # Create map file with all symbols from ${1}
 142 # See mksymap for additional details
 143 mksysmap()
 144 {
 145         ${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}
 146 }
 147
 148 sortextable()
 149 {
 150         ${objtree}/scripts/sortextable ${1}
 151 }
 152
 153 # Delete output files in case of error
 154 cleanup()
 155 {
 156         rm -f .tmp_System.map
 157         rm -f .tmp_kallsyms*
 158         rm -f .tmp_vmlinux*
 159         rm -f System.map
 160         rm -f vmlinux
 161         rm -f vmlinux.o
 162 }
 163
 164 on_exit()
 165 {
 166         if [ $? -ne 0 ]; then
 167                 cleanup
 168         fi
 169 }
 170 trap on_exit EXIT
 171
 172 on_signals()
 173 {
 174         exit 1
 175 }
 176 trap on_signals HUP INT QUIT TERM
 177
 178 #
 179 #
 180 # Use "make V=1" to debug this script
 181 case "${KBUILD_VERBOSE}" in
 182 *1*)
 183         set -x
 184         ;;
 185 esac
 186
 187 if [ "$1" = "clean" ]; then
 188         cleanup
 189         exit 0
 190 fi
 191
 192 # We need access to CONFIG_ symbols
 193 . include/config/auto.conf
 194
 195 # Update version
 196 info GEN .version
 197 if [ -r .version ]; then
 198         VERSION=$(expr 0$(cat .version) + 1)
 199         echo $VERSION > .version
 200 else
 201         rm -f .version
 202         echo 1 > .version
 203 fi;
 204
 205 # final build of init/
 206 ${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init
 207
 208 #link vmlinux.o
 209 info LD vmlinux.o
 210 modpost_link vmlinux.o
 211
 212 # modpost vmlinux.o to check for section mismatches
 213 ${MAKE} -f "${srctree}/scripts/Makefile.modpost" vmlinux.o
 214
 215 info MODINFO modules.builtin.modinfo
 216 ${OBJCOPY} -j .modinfo -O binary vmlinux.o modules.builtin.modinfo
 217
 218 kallsymso=""
 219 kallsyms_vmlinux=""
 220 if [ -n "${CONFIG_KALLSYMS}" ]; then
 221
 222         # kallsyms support
 223         # Generate section listing all symbols and add it into vmlinux
 224         # It's a three step process:
 225         # 1)  Link .tmp_vmlinux1 so it has all symbols and sections,
 226         #     but __kallsyms is empty.
 227         #     Running kallsyms on that gives us .tmp_kallsyms1.o with
 228         #     the right size
 229         # 2)  Link .tmp_vmlinux2 so it now has a __kallsyms section of
 230         #     the right size, but due to the added section, some
 231         #     addresses have shifted.
 232         #     From here, we generate a correct .tmp_kallsyms2.o
 233         # 3)  That link may have expanded the kernel image enough that
 234         #     more linker branch stubs / trampolines had to be added, which
 235         #     introduces new names, which further expands kallsyms. Do another
 236         #     pass if that is the case. In theory it's possible this results
 237         #     in even more stubs, but unlikely.
 238         #     KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
 239         #     other bugs.
 240         # 4)  The correct ${kallsymso} is linked into the final vmlinux.
 241         #
 242         # a)  Verify that the System.map from vmlinux matches the map from
 243         #     ${kallsymso}.
 244
 245         kallsymso=.tmp_kallsyms2.o
 246         kallsyms_vmlinux=.tmp_vmlinux2
 247
 248         # step 1
 249         vmlinux_link "" .tmp_vmlinux1
 250         kallsyms .tmp_vmlinux1 .tmp_kallsyms1.o
 251
 252         # step 2
 253         vmlinux_link .tmp_kallsyms1.o .tmp_vmlinux2
 254         kallsyms .tmp_vmlinux2 .tmp_kallsyms2.o
 255
 256         # step 3
 257         size1=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" .tmp_kallsyms1.o)
 258         size2=$(${CONFIG_SHELL} "${srctree}/scripts/file-size.sh" .tmp_kallsyms2.o)
 259
 260         if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
 261                 kallsymso=.tmp_kallsyms3.o
 262                 kallsyms_vmlinux=.tmp_vmlinux3
 263
 264                 vmlinux_link .tmp_kallsyms2.o .tmp_vmlinux3
 265
 266                 kallsyms .tmp_vmlinux3 .tmp_kallsyms3.o
 267         fi
 268 fi
 269
 270 info LD vmlinux
 271 vmlinux_link "${kallsymso}" vmlinux
 272
 273 if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then
 274         gen_btf vmlinux
 275 fi
 276
 277 if [ -n "${CONFIG_BUILDTIME_EXTABLE_SORT}" ]; then
 278         info SORTEX vmlinux
 279         sortextable vmlinux
 280 fi
 281
 282 info SYSMAP System.map
 283 mksysmap vmlinux System.map
 284
 285 # step a (see comment above)
 286 if [ -n "${CONFIG_KALLSYMS}" ]; then
 287         mksysmap ${kallsyms_vmlinux} .tmp_System.map
 288
 289         if ! cmp -s System.map .tmp_System.map; then
 290                 echo >&2 Inconsistent kallsyms data
 291                 echo >&2 Try "make KALLSYMS_EXTRA_PASS=1" as a workaround
 292                 exit 1
 293         fi
 294 fi