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
31function check_section()
32{
33    file=$1
34    section=$2
35    size=$(objdump -h -j $section $file 2>/dev/null | awk "\$2 == \"$section\" {print \$3}")
36    size=${size:-0}
37    if [ $size -ne 0 ]; then
38	ERROR=1
39	echo "Error: Section $section not empty in prom_init.c" >&2
40    fi
41}
42
43for UNDEF in $($NM -u $OBJ | awk '{print $2}')
44do
45	# On 64-bit nm gives us the function descriptors, which have
46	# a leading . on the name, so strip it off here.
47	UNDEF="${UNDEF#.}"
48
49	if [ $KBUILD_VERBOSE ]; then
50		if [ $KBUILD_VERBOSE -ne 0 ]; then
51			echo "Checking prom_init.o symbol '$UNDEF'"
52		fi
53	fi
54
55	OK=0
56	for WHITE in $WHITELIST
57	do
58		if [ "$UNDEF" = "$WHITE" ]; then
59			OK=1
60			break
61		fi
62	done
63
64	# ignore register save/restore funcitons
65	case $UNDEF in
66	_restgpr_*|_restgpr0_*|_rest32gpr_*)
67		OK=1
68		;;
69	_savegpr_*|_savegpr0_*|_save32gpr_*)
70		OK=1
71		;;
72	esac
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
81check_section $OBJ .data
82check_section $OBJ .bss
83check_section $OBJ .init.data
84
85exit $ERROR
86