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
16 has_renamed_memintrinsics()
17 {
18 grep -q "^CONFIG_KASAN=y$" ${KCONFIG_CONFIG} && \
19 ! grep -q "^CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX=y" ${KCONFIG_CONFIG}
20 }
21
22 if has_renamed_memintrinsics
23 then
24 MEM_FUNCS="__memcpy __memset"
25 else
26 MEM_FUNCS="memcpy memset"
27 fi
28
29 WHITELIST="add_reloc_offset __bss_start __bss_stop copy_and_flush
30 _end enter_prom $MEM_FUNCS reloc_offset __secondary_hold
31 __secondary_hold_acknowledge __secondary_hold_spinloop __start
32 logo_linux_clut224 btext_prepare_BAT
33 reloc_got2 kernstart_addr memstart_addr linux_banner _stext
34 btext_setup_display TOC. relocate"
35
36 NM="$1"
37 OBJ="$2"
38
39 ERROR=0
40
41 check_section()
42 {
43 file=$1
44 section=$2
45 size=$(objdump -h -j $section $file 2>/dev/null | awk "\$2 == \"$section\" {print \$3}")
46 size=${size:-0}
47 if [ $size -ne 0 ]; then
48 ERROR=1
49 echo "Error: Section $section not empty in prom_init.c" >&2
50 fi
51 }
52
53 for UNDEF in $($NM -u $OBJ | awk '{print $2}')
54 do
55 # On 64-bit nm gives us the function descriptors, which have
56 # a leading . on the name, so strip it off here.
57 UNDEF="${UNDEF#.}"
58
59 case "$KBUILD_VERBOSE" in
60 *1*)
61 echo "Checking prom_init.o symbol '$UNDEF'" ;;
62 esac
63
64 OK=0
65 for WHITE in $WHITELIST
66 do
67 if [ "$UNDEF" = "$WHITE" ]; then
68 OK=1
69 break
70 fi
71 done
72
73 # ignore register save/restore funcitons
74 case $UNDEF in
75 _restgpr_*|_restgpr0_*|_rest32gpr_*)
76 OK=1
77 ;;
78 _savegpr_*|_savegpr0_*|_save32gpr_*)
79 OK=1
80 ;;
81 esac
82
83 if [ $OK -eq 0 ]; then
84 ERROR=1
85 echo "Error: External symbol '$UNDEF' referenced" \
86 "from prom_init.c" >&2
87 fi
88 done
89
90 check_section $OBJ .data
91 check_section $OBJ .bss
92 check_section $OBJ .init.data
93
94 exit $ERROR
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