linux/arch/powerpc/kernel/prom_init_check.sh
Thiago Jung Bauermann 05d9a95283 powerpc/prom_init: Undo relocation before entering secure mode
The ultravisor will do an integrity check of the kernel image but we
relocated it so the check will fail. Restore the original image by
relocating it back to the kernel virtual base address.

This works because during build vmlinux is linked with an expected
virtual runtime address of KERNELBASE.

Fixes: 6a9c930bd7 ("powerpc/prom_init: Add the ESM call to prom_init")
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Tested-by: Michael Anderson <andmike@linux.ibm.com>
[mpe: Add IS_ENABLED() to fix the CONFIG_RELOCATABLE=n build]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190911163433.12822-1-bauerman@linux.ibm.com
2019-10-29 15:12:17 +11:00

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#!/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:
grep "^CONFIG_KASAN=y$" .config >/dev/null
if [ $? -eq 0 ]
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
__prom_init_toc_start __prom_init_toc_end 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#.}"
if [ $KBUILD_VERBOSE ]; then
if [ $KBUILD_VERBOSE -ne 0 ]; then
echo "Checking prom_init.o symbol '$UNDEF'"
fi
fi
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