1#!/bin/sh
2#
3# Copyright © 2008 IBM Corporation
4#
5# This program is free software; you can redistribute it and/or
6# modify it under the terms of the GNU General Public License
7# as published by the Free Software Foundation; either version
8# 2 of the License, or (at your option) any later version.
9
10# This script checks prom_init.o to see what external symbols it
11# is using, if it finds symbols not in the whitelist it returns
12# an error. The point of this is to discourage people from
13# intentionally or accidentally adding new code to prom_init.c
14# which has side effects on other parts of the kernel.
15
16# If you really need to reference something from prom_init.o add
17# it to the list below:
18
19WHITELIST="add_reloc_offset __bss_start __bss_stop copy_and_flush
20_end enter_prom memcpy memset reloc_offset __secondary_hold
21__secondary_hold_acknowledge __secondary_hold_spinloop __start
22strcmp strcpy strlcpy strlen strncmp strstr kstrtobool logo_linux_clut224
23reloc_got2 kernstart_addr memstart_addr linux_banner _stext
24__prom_init_toc_start __prom_init_toc_end btext_setup_display TOC."
25
26NM="$1"
27OBJ="$2"
28
29ERROR=0
30
31for UNDEF in $($NM -u $OBJ | awk '{print $2}')
32do
33	# On 64-bit nm gives us the function descriptors, which have
34	# a leading . on the name, so strip it off here.
35	UNDEF="${UNDEF#.}"
36
37	if [ $KBUILD_VERBOSE ]; then
38		if [ $KBUILD_VERBOSE -ne 0 ]; then
39			echo "Checking prom_init.o symbol '$UNDEF'"
40		fi
41	fi
42
43	OK=0
44	for WHITE in $WHITELIST
45	do
46		if [ "$UNDEF" = "$WHITE" ]; then
47			OK=1
48			break
49		fi
50	done
51
52	# ignore register save/restore funcitons
53	case $UNDEF in
54	_restgpr_*|_restgpr0_*|_rest32gpr_*)
55		OK=1
56		;;
57	_savegpr_*|_savegpr0_*|_save32gpr_*)
58		OK=1
59		;;
60	esac
61
62	if [ $OK -eq 0 ]; then
63		ERROR=1
64		echo "Error: External symbol '$UNDEF' referenced" \
65		     "from prom_init.c" >&2
66	fi
67done
68
69exit $ERROR
70