arch/powerpc/kernel/prom_init_check.sh

   1 #!/bin/sh
   2 # SPDX-License-Identifier: GPL-2.0-or-later
   3 #
   4 # Copyright © 2008 IBM Corporation
   5 #
   6
   7 # This script checks prom_init.o to see what external symbols it
   8 # is using, if it finds symbols not in the whitelist it returns
   9 # an error. The point of this is to discourage people from
  10 # intentionally or accidentally adding new code to prom_init.c
  11 # which has side effects on other parts of the kernel.
  12
  13 # If you really need to reference something from prom_init.o add
  14 # it to the list below:
  15
  16 has_renamed_memintrinsics()
  17 {
  18         grep -q "^CONFIG_KASAN=y$" ${KCONFIG_CONFIG} && \
  19                 ! grep -q "^CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX=y" ${KCONFIG_CONFIG}
  20 }
  21
  22 if has_renamed_memintrinsics
  23 then
  24         MEM_FUNCS="__memcpy __memset"
  25 else
  26         MEM_FUNCS="memcpy memset"
  27 fi
  28
  29 WHITELIST="add_reloc_offset __bss_start __bss_stop copy_and_flush
  30 _end enter_prom $MEM_FUNCS reloc_offset __secondary_hold
  31 __secondary_hold_acknowledge __secondary_hold_spinloop __start
  32 logo_linux_clut224 btext_prepare_BAT
  33 reloc_got2 kernstart_addr memstart_addr linux_banner _stext
  34 btext_setup_display TOC. relocate"
  35
  36 NM="$1"
  37 OBJ="$2"
  38
  39 ERROR=0
  40
  41 check_section()
  42 {
  43     file=$1
  44     section=$2
  45     size=$(objdump -h -j $section $file 2>/dev/null | awk "\$2 == \"$section\" {print \$3}")
  46     size=${size:-0}
  47     if [ $size -ne 0 ]; then
  48         ERROR=1
  49         echo "Error: Section $section not empty in prom_init.c" >&2
  50     fi
  51 }
  52
  53 for UNDEF in $($NM -u $OBJ | awk '{print $2}')
  54 do
  55         # On 64-bit nm gives us the function descriptors, which have
  56         # a leading . on the name, so strip it off here.
  57         UNDEF="${UNDEF#.}"
  58
  59         case "$KBUILD_VERBOSE" in
  60         *1*)
  61                 echo "Checking prom_init.o symbol '$UNDEF'" ;;
  62         esac
  63
  64         OK=0
  65         for WHITE in $WHITELIST
  66         do
  67                 if [ "$UNDEF" = "$WHITE" ]; then
  68                         OK=1
  69                         break
  70                 fi
  71         done
  72
  73         # ignore register save/restore funcitons
  74         case $UNDEF in
  75         _restgpr_*|_restgpr0_*|_rest32gpr_*)
  76                 OK=1
  77                 ;;
  78         _savegpr_*|_savegpr0_*|_save32gpr_*)
  79                 OK=1
  80                 ;;
  81         esac
  82
  83         if [ $OK -eq 0 ]; then
  84                 ERROR=1
  85                 echo "Error: External symbol '$UNDEF' referenced" \
  86                      "from prom_init.c" >&2
  87         fi
  88 done
  89
  90 check_section $OBJ .data
  91 check_section $OBJ .bss
  92 check_section $OBJ .init.data
  93
  94 exit $ERROR