1#!/bin/bash
2# SPDX-License-Identifier: GPL-2.0
3# Disassemble the Code: line in Linux oopses
4# usage: decodecode < oops.file
5#
6# options: set env. variable AFLAGS=options to pass options to "as";
7# e.g., to decode an i386 oops on an x86_64 system, use:
8# AFLAGS=--32 decodecode < 386.oops
9# PC=hex - the PC (program counter) the oops points to
10
11faultlinenum=1
12
13cleanup() {
14	rm -f $T $T.s $T.o $T.oo $T.aa $T.dis
15	exit 1
16}
17
18die() {
19	echo "$@"
20	exit 1
21}
22
23trap cleanup EXIT
24
25T=`mktemp` || die "cannot create temp file"
26code=
27cont=
28
29while read i ; do
30
31case "$i" in
32*Code:*)
33	code=$i
34	cont=yes
35	;;
36*)
37	[ -n "$cont" ] && {
38		xdump="$(echo $i | grep '^[[:xdigit:]<>[:space:]]\+$')"
39		if [ -n "$xdump" ]; then
40			code="$code $xdump"
41		else
42			cont=
43		fi
44	}
45	;;
46esac
47
48done
49
50if [ -z "$code" ]; then
51	rm $T
52	exit
53fi
54
55echo $code
56code=`echo $code | sed -e 's/.*Code: //'`
57
58width=`expr index "$code" ' '`
59width=$((($width-1)/2))
60case $width in
611) type=byte ;;
622) type=2byte ;;
634) type=4byte ;;
64esac
65
66if [ -z "$ARCH" ]; then
67    case `uname -m` in
68	aarch64*) ARCH=arm64 ;;
69	arm*) ARCH=arm ;;
70	loongarch*) ARCH=loongarch ;;
71    esac
72fi
73
74# Params: (tmp_file, pc_sub)
75disas() {
76	t=$1
77	pc_sub=$2
78
79	${CROSS_COMPILE}as $AFLAGS -o $t.o $t.s > /dev/null 2>&1
80
81	if [ "$ARCH" = "arm" ]; then
82		if [ $width -eq 2 ]; then
83			OBJDUMPFLAGS="-M force-thumb"
84		fi
85
86		${CROSS_COMPILE}strip $t.o
87	fi
88
89	if [ "$ARCH" = "arm64" ]; then
90		if [ $width -eq 4 ]; then
91			type=inst
92		fi
93
94		${CROSS_COMPILE}strip $t.o
95	fi
96
97	if [ "$ARCH" = "riscv" ]; then
98		OBJDUMPFLAGS="-M no-aliases --section=.text -D"
99		${CROSS_COMPILE}strip $t.o
100	fi
101
102	if [ "$ARCH" = "loongarch" ]; then
103		${CROSS_COMPILE}strip $t.o
104	fi
105
106	if [ $pc_sub -ne 0 ]; then
107		if [ $PC ]; then
108			adj_vma=$(( $PC - $pc_sub ))
109			OBJDUMPFLAGS="$OBJDUMPFLAGS --adjust-vma=$adj_vma"
110		fi
111	fi
112
113	${CROSS_COMPILE}objdump $OBJDUMPFLAGS -S $t.o | \
114		grep -v "/tmp\|Disassembly\|\.text\|^$" > $t.dis 2>&1
115}
116
117# Match the maximum number of opcode bytes from @op_bytes contained within
118# @opline
119#
120# Params:
121# @op_bytes: The string of bytes from the Code: line
122# @opline: The disassembled line coming from objdump
123#
124# Returns:
125# The max number of opcode bytes from the beginning of @op_bytes which match
126# the opcode bytes in the objdump line.
127get_substr_opcode_bytes_num()
128{
129	local op_bytes=$1
130	local opline=$2
131
132	local retval=0
133	substr=""
134
135	for opc in $op_bytes;
136	do
137		substr+="$opc"
138
139		opcode="$substr"
140		if [ "$ARCH" = "riscv" ]; then
141			opcode=$(echo $opcode | tr ' ' '\n' | tac | tr -d '\n')
142		fi
143
144		# return if opcode bytes do not match @opline anymore
145		if ! echo $opline | grep -q "$opcode";
146		then
147			break
148		fi
149
150		# add trailing space
151		substr+=" "
152		retval=$((retval+1))
153	done
154
155	return $retval
156}
157
158# Return the line number in objdump output to where the IP marker in the Code:
159# line points to
160#
161# Params:
162# @all_code: code in bytes without the marker
163# @dis_file: disassembled file
164# @ip_byte: The byte to which the IP points to
165get_faultlinenum()
166{
167	local all_code="$1"
168	local dis_file="$2"
169
170	# num bytes including IP byte
171	local num_bytes_ip=$(( $3 + 1 * $width ))
172
173	# Add the two header lines (we're counting from 1).
174	local retval=3
175
176	# remove marker
177	all_code=$(echo $all_code | sed -e 's/[<>()]//g')
178
179	while read line
180	do
181		get_substr_opcode_bytes_num "$all_code" "$line"
182		ate_opcodes=$?
183
184		if ! (( $ate_opcodes )); then
185			continue
186		fi
187
188		num_bytes_ip=$((num_bytes_ip - ($ate_opcodes * $width) ))
189		if (( $num_bytes_ip <= 0 )); then
190			break
191		fi
192
193		# Delete matched opcode bytes from all_code. For that, compute
194		# how many chars those opcodes are represented by and include
195		# trailing space.
196		#
197		# a byte is 2 chars, ate_opcodes is also the number of trailing
198		# spaces
199		del_chars=$(( ($ate_opcodes * $width * 2) + $ate_opcodes ))
200
201		all_code=$(echo $all_code | sed -e "s!^.\{$del_chars\}!!")
202
203		let "retval+=1"
204
205	done < $dis_file
206
207	return $retval
208}
209
210marker=`expr index "$code" "\<"`
211if [ $marker -eq 0 ]; then
212	marker=`expr index "$code" "\("`
213fi
214
215touch $T.oo
216if [ $marker -ne 0 ]; then
217	# How many bytes to subtract from the program counter
218	# in order to get to the beginning virtual address of the
219	# Code:
220	pc_sub=$(( (($marker - 1) / (2 * $width + 1)) * $width ))
221	echo All code >> $T.oo
222	echo ======== >> $T.oo
223	beforemark=`echo "$code"`
224	echo -n "	.$type 0x" > $T.s
225
226	echo $beforemark | sed -e 's/ /,0x/g; s/[<>()]//g' >> $T.s
227
228	disas $T $pc_sub
229
230	cat $T.dis >> $T.oo
231
232	get_faultlinenum "$code" "$T.dis" $pc_sub
233	faultlinenum=$?
234
235	# and fix code at-and-after marker
236	code=`echo "$code" | cut -c$((${marker} + 1))-`
237
238	rm -f $T.o $T.s $T.dis
239fi
240
241echo Code starting with the faulting instruction  > $T.aa
242echo =========================================== >> $T.aa
243code=`echo $code | sed -e 's/\r//;s/ [<(]/ /;s/[>)] / /;s/ /,0x/g; s/[>)]$//'`
244echo -n "	.$type 0x" > $T.s
245echo $code >> $T.s
246disas $T 0
247cat $T.dis >> $T.aa
248
249cat $T.oo | sed -e "${faultlinenum}s/^\([^:]*:\)\(.*\)/\1\*\2\t\t<-- trapping instruction/"
250echo
251cat $T.aa
252cleanup
253