1 files changed, 91 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/prom_init_check.sh b/arch/powerpc/kernel/prom_init_check.sh
new file mode 100644
index 000000000..dfa5f729f
--- /dev/null
+++ b/arch/powerpc/kernel/prom_init_check.sh
@@ -0,0 +1,91 @@
+#!/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$" ${KCONFIG_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