xref: /linux/scripts/faddr2line (revision e58e871becec2d3b04ed91c0c16fe8deac9c9dfa) 
1#!/bin/bash
2#
3# Translate stack dump function offsets.
4#
5# addr2line doesn't work with KASLR addresses.  This works similarly to
6# addr2line, but instead takes the 'func+0x123' format as input:
7#
8#   $ ./scripts/faddr2line ~/k/vmlinux meminfo_proc_show+0x5/0x568
9#   meminfo_proc_show+0x5/0x568:
10#   meminfo_proc_show at fs/proc/meminfo.c:27
11#
12# If the address is part of an inlined function, the full inline call chain is
13# printed:
14#
15#   $ ./scripts/faddr2line ~/k/vmlinux native_write_msr+0x6/0x27
16#   native_write_msr+0x6/0x27:
17#   arch_static_branch at arch/x86/include/asm/msr.h:121
18#    (inlined by) static_key_false at include/linux/jump_label.h:125
19#    (inlined by) native_write_msr at arch/x86/include/asm/msr.h:125
20#
21# The function size after the '/' in the input is optional, but recommended.
22# It's used to help disambiguate any duplicate symbol names, which can occur
23# rarely.  If the size is omitted for a duplicate symbol then it's possible for
24# multiple code sites to be printed:
25#
26#   $ ./scripts/faddr2line ~/k/vmlinux raw_ioctl+0x5
27#   raw_ioctl+0x5/0x20:
28#   raw_ioctl at drivers/char/raw.c:122
29#
30#   raw_ioctl+0x5/0xb1:
31#   raw_ioctl at net/ipv4/raw.c:876
32#
33# Multiple addresses can be specified on a single command line:
34#
35#   $ ./scripts/faddr2line ~/k/vmlinux type_show+0x10/45 free_reserved_area+0x90
36#   type_show+0x10/0x2d:
37#   type_show at drivers/video/backlight/backlight.c:213
38#
39#   free_reserved_area+0x90/0x123:
40#   free_reserved_area at mm/page_alloc.c:6429 (discriminator 2)
41
42
43set -o errexit
44set -o nounset
45
46command -v awk >/dev/null 2>&1 || die "awk isn't installed"
47command -v readelf >/dev/null 2>&1 || die "readelf isn't installed"
48command -v addr2line >/dev/null 2>&1 || die "addr2line isn't installed"
49
50usage() {
51	echo "usage: faddr2line <object file> <func+offset> <func+offset>..." >&2
52	exit 1
53}
54
55warn() {
56	echo "$1" >&2
57}
58
59die() {
60	echo "ERROR: $1" >&2
61	exit 1
62}
63
64# Try to figure out the source directory prefix so we can remove it from the
65# addr2line output.  HACK ALERT: This assumes that start_kernel() is in
66# kernel/init.c!  This only works for vmlinux.  Otherwise it falls back to
67# printing the absolute path.
68find_dir_prefix() {
69	local objfile=$1
70
71	local start_kernel_addr=$(readelf -sW $objfile | awk '$8 == "start_kernel" {printf "0x%s", $2}')
72	[[ -z $start_kernel_addr ]] && return
73
74	local file_line=$(addr2line -e $objfile $start_kernel_addr)
75	[[ -z $file_line ]] && return
76
77	local prefix=${file_line%init/main.c:*}
78	if [[ -z $prefix ]] || [[ $prefix = $file_line ]]; then
79		return
80	fi
81
82	DIR_PREFIX=$prefix
83	return 0
84}
85
86__faddr2line() {
87	local objfile=$1
88	local func_addr=$2
89	local dir_prefix=$3
90	local print_warnings=$4
91
92	local func=${func_addr%+*}
93	local offset=${func_addr#*+}
94	offset=${offset%/*}
95	local size=
96	[[ $func_addr =~ "/" ]] && size=${func_addr#*/}
97
98	if [[ -z $func ]] || [[ -z $offset ]] || [[ $func = $func_addr ]]; then
99		warn "bad func+offset $func_addr"
100		DONE=1
101		return
102	fi
103
104	# Go through each of the object's symbols which match the func name.
105	# In rare cases there might be duplicates.
106	while read symbol; do
107		local fields=($symbol)
108		local sym_base=0x${fields[0]}
109		local sym_type=${fields[1]}
110		local sym_end=0x${fields[3]}
111
112		# calculate the size
113		local sym_size=$(($sym_end - $sym_base))
114		if [[ -z $sym_size ]] || [[ $sym_size -le 0 ]]; then
115			warn "bad symbol size: base: $sym_base end: $sym_end"
116			DONE=1
117			return
118		fi
119		sym_size=0x$(printf %x $sym_size)
120
121		# calculate the address
122		local addr=$(($sym_base + $offset))
123		if [[ -z $addr ]] || [[ $addr = 0 ]]; then
124			warn "bad address: $sym_base + $offset"
125			DONE=1
126			return
127		fi
128		addr=0x$(printf %x $addr)
129
130		# weed out non-function symbols
131		if [[ $sym_type != t ]] && [[ $sym_type != T ]]; then
132			[[ $print_warnings = 1 ]] &&
133				echo "skipping $func address at $addr due to non-function symbol of type '$sym_type'"
134			continue
135		fi
136
137		# if the user provided a size, make sure it matches the symbol's size
138		if [[ -n $size ]] && [[ $size -ne $sym_size ]]; then
139			[[ $print_warnings = 1 ]] &&
140				echo "skipping $func address at $addr due to size mismatch ($size != $sym_size)"
141			continue;
142		fi
143
144		# make sure the provided offset is within the symbol's range
145		if [[ $offset -gt $sym_size ]]; then
146			[[ $print_warnings = 1 ]] &&
147				echo "skipping $func address at $addr due to size mismatch ($offset > $sym_size)"
148			continue
149		fi
150
151		# separate multiple entries with a blank line
152		[[ $FIRST = 0 ]] && echo
153		FIRST=0
154
155		# pass real address to addr2line
156		echo "$func+$offset/$sym_size:"
157		addr2line -fpie $objfile $addr | sed "s; $dir_prefix\(\./\)*; ;"
158		DONE=1
159
160	done < <(nm -n $objfile | awk -v fn=$func '$3 == fn { found=1; line=$0; start=$1; next } found == 1 { found=0; print line, $1 }')
161}
162
163[[ $# -lt 2 ]] && usage
164
165objfile=$1
166[[ ! -f $objfile ]] && die "can't find objfile $objfile"
167shift
168
169DIR_PREFIX=supercalifragilisticexpialidocious
170find_dir_prefix $objfile
171
172FIRST=1
173while [[ $# -gt 0 ]]; do
174	func_addr=$1
175	shift
176
177	# print any matches found
178	DONE=0
179	__faddr2line $objfile $func_addr $DIR_PREFIX 0
180
181	# if no match was found, print warnings
182	if [[ $DONE = 0 ]]; then
183		__faddr2line $objfile $func_addr $DIR_PREFIX 1
184		warn "no match for $func_addr"
185	fi
186done
187