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 
11 faultlinenum=1
12 
13 cleanup() {
14 	rm -f $T $T.s $T.o $T.oo $T.aa $T.dis
15 	exit 1
16 }
17 
18 die() {
19 	echo "$@"
20 	exit 1
21 }
22 
23 trap cleanup EXIT
24 
25 T=`mktemp` || die "cannot create temp file"
26 code=
27 cont=
28 
29 while read i ; do
30 
31 case "$i" in
32 *Code:*)
33 	code=$i
34 	cont=yes
35 	;;
36 *)
37 	[ -n "$cont" ] && {
38 		xdump="$(echo $i | grep '^[[:xdigit:]<>[:space:]]\+$')"
39 		if [ -n "$xdump" ]; then
40 			code="$code $xdump"
41 		else
42 			cont=
43 		fi
44 	}
45 	;;
46 esac
47 
48 done
49 
50 if [ -z "$code" ]; then
51 	rm $T
52 	exit
53 fi
54 
55 echo $code
56 code=`echo $code | sed -e 's/.*Code: //'`
57 
58 width=`expr index "$code" ' '`
59 width=$((($width-1)/2))
60 case $width in
61 1) type=byte ;;
62 2) type=2byte ;;
63 4) type=4byte ;;
64 esac
65 
66 if [ -z "$ARCH" ]; then
67     case `uname -m` in
68 	aarch64*) ARCH=arm64 ;;
69 	arm*) ARCH=arm ;;
70 	loongarch*) ARCH=loongarch ;;
71     esac
72 fi
73 
74 # Params: (tmp_file, pc_sub)
75 disas() {
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.
127 get_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
165 get_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 $retval
208 }
209 
210 marker=`expr index "$code" "\<"`
211 if [ $marker -eq 0 ]; then
212 	marker=`expr index "$code" "\("`
213 fi
214 
215 touch $T.oo
216 if [ $marker -ne 0 ]; then
217 	# How many bytes to subtract from the program counter
218 	# in order to get to the beginning virtual address of the
219 	# Code:
220 	pc_sub=$(( (($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
239 fi
240 
241 echo Code starting with the faulting instruction  > $T.aa
242 echo =========================================== >> $T.aa
243 code=`echo $code | sed -e 's/\r//;s/ [<(]/ /;s/[>)] / /;s/ /,0x/g; s/[>)]$//'`
244 echo -n "	.$type 0x" > $T.s
245 echo $code >> $T.s
246 disas $T 0
247 cat $T.dis >> $T.aa
248 
249 cat $T.oo | sed -e "${faultlinenum}s/^\([^:]*:\)\(.*\)/\1\*\2\t\t<-- trapping instruction/"
250 echo
251 cat $T.aa
252 cleanup
253