name : prom_init_check.sh #!/bin/sh # SPDX-License-Identifier: GPL-2.0-or-later # # Copyright © 2008 IBM Corporation # # This script checks prom_init.o to see what external symbols it # is using, if it finds symbols not in the whitelist it returns # an error. The point of this is to discourage people from # intentionally or accidentally adding new code to prom_init.c # which has side effects on other parts of the kernel. # If you really need to reference something from prom_init.o add # it to the list below: has_renamed_memintrinsics() { grep -q "^CONFIG_KASAN=y$" ${KCONFIG_CONFIG} && \ ! grep -q "^CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX=y" ${KCONFIG_CONFIG} } if has_renamed_memintrinsics then MEM_FUNCS="__memcpy __memset" else MEM_FUNCS="memcpy memset" fi WHITELIST="add_reloc_offset __bss_start __bss_stop copy_and_flush _end enter_prom $MEM_FUNCS reloc_offset __secondary_hold __secondary_hold_acknowledge __secondary_hold_spinloop __start logo_linux_clut224 btext_prepare_BAT reloc_got2 kernstart_addr memstart_addr linux_banner _stext btext_setup_display TOC. relocate" NM="$1" OBJ="$2" ERROR=0 check_section() { file=$1 section=$2 size=$(objdump -h -j $section $file 2>/dev/null | awk "\$2 == \"$section\" {print \$3}") size=${size:-0} if [ $size -ne 0 ]; then ERROR=1 echo "Error: Section $section not empty in prom_init.c" >&2 fi } for UNDEF in $($NM -u $OBJ | awk '{print $2}') do # On 64-bit nm gives us the function descriptors, which have # a leading . on the name, so strip it off here. UNDEF="${UNDEF#.}" case "$KBUILD_VERBOSE" in *1*) echo "Checking prom_init.o symbol '$UNDEF'" ;; esac OK=0 for WHITE in $WHITELIST do if [ "$UNDEF" = "$WHITE" ]; then OK=1 break fi done # ignore register save/restore funcitons case $UNDEF in _restgpr_*|_restgpr0_*|_rest32gpr_*) OK=1 ;; _savegpr_*|_savegpr0_*|_save32gpr_*) OK=1 ;; esac if [ $OK -eq 0 ]; then ERROR=1 echo "Error: External symbol '$UNDEF' referenced" \ "from prom_init.c" >&2 fi done check_section $OBJ .data check_section $OBJ .bss check_section $OBJ .init.data exit $ERROR