1#!/bin/sh
2# SPDX-License-Identifier: GPL-2.0-or-later
3#
4# Copyright © 2008 IBM Corporation
5#
6
7# This script checks prom_init.o to see what external symbols it
8# is using, if it finds symbols not in the whitelist it returns
9# an error. The point of this is to discourage people from
10# intentionally or accidentally adding new code to prom_init.c
11# which has side effects on other parts of the kernel.
12
13# If you really need to reference something from prom_init.o add
14# it to the list below:
15
16grep "^CONFIG_KASAN=y$" ${KCONFIG_CONFIG} >/dev/null
17if [ $? -eq 0 ]
18then
19	MEM_FUNCS="__memcpy __memset"
20else
21	MEM_FUNCS="memcpy memset"
22fi
23
24WHITELIST="add_reloc_offset __bss_start __bss_stop copy_and_flush
25_end enter_prom $MEM_FUNCS reloc_offset __secondary_hold
26__secondary_hold_acknowledge __secondary_hold_spinloop __start
27logo_linux_clut224 btext_prepare_BAT
28reloc_got2 kernstart_addr memstart_addr linux_banner _stext
29btext_setup_display TOC. relocate"
30
31NM="$1"
32OBJ="$2"
33
34ERROR=0
35
36check_section()
37{
38    file=$1
39    section=$2
40    size=$(objdump -h -j $section $file 2>/dev/null | awk "\$2 == \"$section\" {print \$3}")
41    size=${size:-0}
42    if [ $size -ne 0 ]; then
43	ERROR=1
44	echo "Error: Section $section not empty in prom_init.c" >&2
45    fi
46}
47
48for UNDEF in $($NM -u $OBJ | awk '{print $2}')
49do
50	# On 64-bit nm gives us the function descriptors, which have
51	# a leading . on the name, so strip it off here.
52	UNDEF="${UNDEF#.}"
53
54	case "$KBUILD_VERBOSE" in
55	*1*)
56		echo "Checking prom_init.o symbol '$UNDEF'" ;;
57	esac
58
59	OK=0
60	for WHITE in $WHITELIST
61	do
62		if [ "$UNDEF" = "$WHITE" ]; then
63			OK=1
64			break
65		fi
66	done
67
68	# ignore register save/restore funcitons
69	case $UNDEF in
70	_restgpr_*|_restgpr0_*|_rest32gpr_*)
71		OK=1
72		;;
73	_savegpr_*|_savegpr0_*|_save32gpr_*)
74		OK=1
75		;;
76	esac
77
78	if [ $OK -eq 0 ]; then
79		ERROR=1
80		echo "Error: External symbol '$UNDEF' referenced" \
81		     "from prom_init.c" >&2
82	fi
83done
84
85check_section $OBJ .data
86check_section $OBJ .bss
87check_section $OBJ .init.data
88
89exit $ERROR
90