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 _stext
24opal_query_takeover opal_do_takeover opal_enter_rtas opal_secondary_entry
25boot_command_line __prom_init_toc_start __prom_init_toc_end
26btext_setup_display"
27
28NM="$1"
29OBJ="$2"
30
31ERROR=0
32
33for UNDEF in $($NM -u $OBJ | awk '{print $2}')
34do
35	# On 64-bit nm gives us the function descriptors, which have
36	# a leading . on the name, so strip it off here.
37	UNDEF="${UNDEF#.}"
38
39	if [ $KBUILD_VERBOSE ]; then
40		if [ $KBUILD_VERBOSE -ne 0 ]; then
41			echo "Checking prom_init.o symbol '$UNDEF'"
42		fi
43	fi
44
45	OK=0
46	for WHITE in $WHITELIST
47	do
48		if [ "$UNDEF" = "$WHITE" ]; then
49			OK=1
50			break
51		fi
52	done
53
54	# ignore register save/restore funcitons
55	if [ "${UNDEF:0:9}" = "_restgpr_" ]; then
56		OK=1
57	fi
58	if [ "${UNDEF:0:10}" = "_restgpr0_" ]; then
59		OK=1
60	fi
61	if [ "${UNDEF:0:11}" = "_rest32gpr_" ]; then
62		OK=1
63	fi
64	if [ "${UNDEF:0:9}" = "_savegpr_" ]; then
65		OK=1
66	fi
67	if [ "${UNDEF:0:10}" = "_savegpr0_" ]; then
68		OK=1
69	fi
70	if [ "${UNDEF:0:11}" = "_save32gpr_" ]; then
71		OK=1
72	fi
73
74	if [ $OK -eq 0 ]; then
75		ERROR=1
76		echo "Error: External symbol '$UNDEF' referenced" \
77		     "from prom_init.c" >&2
78	fi
79done
80
81exit $ERROR
82