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
19grep "^CONFIG_KASAN=y$" .config >/dev/null
20if [ $? -eq 0 ]
21then
22	MEM_FUNCS="__memcpy __memset"
23else
24	MEM_FUNCS="memcpy memset"
25fi
26
27WHITELIST="add_reloc_offset __bss_start __bss_stop copy_and_flush
28_end enter_prom $MEM_FUNCS reloc_offset __secondary_hold
29__secondary_hold_acknowledge __secondary_hold_spinloop __start
30logo_linux_clut224
31reloc_got2 kernstart_addr memstart_addr linux_banner _stext
32__prom_init_toc_start __prom_init_toc_end btext_setup_display TOC."
33
34NM="$1"
35OBJ="$2"
36
37ERROR=0
38
39function check_section()
40{
41    file=$1
42    section=$2
43    size=$(objdump -h -j $section $file 2>/dev/null | awk "\$2 == \"$section\" {print \$3}")
44    size=${size:-0}
45    if [ $size -ne 0 ]; then
46	ERROR=1
47	echo "Error: Section $section not empty in prom_init.c" >&2
48    fi
49}
50
51for UNDEF in $($NM -u $OBJ | awk '{print $2}')
52do
53	# On 64-bit nm gives us the function descriptors, which have
54	# a leading . on the name, so strip it off here.
55	UNDEF="${UNDEF#.}"
56
57	if [ $KBUILD_VERBOSE ]; then
58		if [ $KBUILD_VERBOSE -ne 0 ]; then
59			echo "Checking prom_init.o symbol '$UNDEF'"
60		fi
61	fi
62
63	OK=0
64	for WHITE in $WHITELIST
65	do
66		if [ "$UNDEF" = "$WHITE" ]; then
67			OK=1
68			break
69		fi
70	done
71
72	# ignore register save/restore funcitons
73	case $UNDEF in
74	_restgpr_*|_restgpr0_*|_rest32gpr_*)
75		OK=1
76		;;
77	_savegpr_*|_savegpr0_*|_save32gpr_*)
78		OK=1
79		;;
80	esac
81
82	if [ $OK -eq 0 ]; then
83		ERROR=1
84		echo "Error: External symbol '$UNDEF' referenced" \
85		     "from prom_init.c" >&2
86	fi
87done
88
89check_section $OBJ .data
90check_section $OBJ .bss
91check_section $OBJ .init.data
92
93exit $ERROR
94