1#!/bin/bash
 2# SPDX-License-Identifier: GPL-2.0+
 3# Copyright © 2016,2020 IBM Corporation
 4#
 5# This script checks the unrelocated code of a vmlinux for "suspicious"
 6# branches to relocated code (head_64.S code).
 7
 8# Have Kbuild supply the path to objdump and nm so we handle cross compilation.
 9objdump="$1"
10nm="$2"
11vmlinux="$3"
12
13kstart=0xc000000000000000
14
15end_intr=0x$($nm -p "$vmlinux" |
16	sed -E -n '/\s+[[:alpha:]]\s+__end_interrupts\s*$/{s///p;q}')
17if [ "$end_intr" = "0x" ]; then
18	exit 0
19fi
20
21# we know that there is a correct branch to
22# __start_initialization_multiplatform, so find its address
23# so we can exclude it.
24sim=0x$($nm -p "$vmlinux" |
25	sed -E -n '/\s+[[:alpha:]]\s+__start_initialization_multiplatform\s*$/{s///p;q}')
26
27$objdump -D --no-show-raw-insn --start-address="$kstart" --stop-address="$end_intr" "$vmlinux" |
28sed -E -n '
29# match lines that start with a kernel address
30/^c[0-9a-f]*:\s*b/ {
31	# drop branches via ctr or lr
32	/\<b.?.?(ct|l)r/d
33	# cope with some differences between Clang and GNU objdumps
34	s/\<bt.?\s*[[:digit:]]+,/beq/
35	s/\<bf.?\s*[[:digit:]]+,/bne/
36	# tidy up
37	s/\s0x/ /
38	s/://
39	# format for the loop below
40	s/^(\S+)\s+(\S+)\s+(\S+)\s*(\S*).*$/\1:\2:\3:\4/
41	# strip out condition registers
42	s/:cr[0-7],/:/
43	p
44}' | {
45
46all_good=true
47while IFS=: read -r from branch to sym; do
48	case "$to" in
49	c*)	to="0x$to"
50		;;
51	.+*)
52		to=${to#.+}
53		if [ "$branch" = 'b' ]; then
54			if (( to >= 0x2000000 )); then
55				to=$(( to - 0x4000000 ))
56			fi
57		elif (( to >= 0x8000 )); then
58			to=$(( to - 0x10000 ))
59		fi
60		printf -v to '0x%x' $(( "0x$from" + to ))
61		;;
62	*)	printf 'Unkown branch format\n'
63		;;
64	esac
65	if [ "$to" = "$sim" ]; then
66		continue
67	fi
68	if (( to > end_intr )); then
69		if $all_good; then
70			printf '%s\n' 'WARNING: Unrelocated relative branches'
71			all_good=false
72		fi
73		printf '%s %s-> %s %s\n' "$from" "$branch" "$to" "$sym"
74	fi
75done
76
77$all_good
78
79}