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