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 logo_linux_clut224
23reloc_got2 kernstart_addr memstart_addr linux_banner"
24
25NM="$1"
26OBJ="$2"
27
28ERROR=0
29
30for UNDEF in $($NM -u $OBJ | awk '{print $2}')
31do
32	# On 64-bit nm gives us the function descriptors, which have
33	# a leading . on the name, so strip it off here.
34	UNDEF="${UNDEF#.}"
35
36	if [ $KBUILD_VERBOSE ]; then
37		if [ $KBUILD_VERBOSE -ne 0 ]; then
38			echo "Checking prom_init.o symbol '$UNDEF'"
39		fi
40	fi
41
42	OK=0
43	for WHITE in $WHITELIST
44	do
45		if [ "$UNDEF" = "$WHITE" ]; then
46			OK=1
47			break
48		fi
49	done
50
51	# ignore register save/restore funcitons
52	if [ "${UNDEF:0:9}" = "_restgpr_" ]; then
53		OK=1
54	fi
55	if [ "${UNDEF:0:11}" = "_rest32gpr_" ]; then
56		OK=1
57	fi
58	if [ "${UNDEF:0:9}" = "_savegpr_" ]; then
59		OK=1
60	fi
61	if [ "${UNDEF:0:11}" = "_save32gpr_" ]; then
62		OK=1
63	fi
64
65	if [ $OK -eq 0 ]; then
66		ERROR=1
67		echo "Error: External symbol '$UNDEF' referenced" \
68		     "from prom_init.c" >&2
69	fi
70done
71
72exit $ERROR
73