scripts/faddr2line

   1 #!/bin/bash
   2 # SPDX-License-Identifier: GPL-2.0
   3 #
   4 # Translate stack dump function offsets.
   5 #
   6 # addr2line doesn't work with KASLR addresses.  This works similarly to
   7 # addr2line, but instead takes the 'func+0x123' format as input:
   8 #
   9 #   $ ./scripts/faddr2line ~/k/vmlinux meminfo_proc_show+0x5/0x568
  10 #   meminfo_proc_show+0x5/0x568:
  11 #   meminfo_proc_show at fs/proc/meminfo.c:27
  12 #
  13 # If the address is part of an inlined function, the full inline call chain is
  14 # printed:
  15 #
  16 #   $ ./scripts/faddr2line ~/k/vmlinux native_write_msr+0x6/0x27
  17 #   native_write_msr+0x6/0x27:
  18 #   arch_static_branch at arch/x86/include/asm/msr.h:121
  19 #    (inlined by) static_key_false at include/linux/jump_label.h:125
  20 #    (inlined by) native_write_msr at arch/x86/include/asm/msr.h:125
  21 #
  22 # The function size after the '/' in the input is optional, but recommended.
  23 # It's used to help disambiguate any duplicate symbol names, which can occur
  24 # rarely.  If the size is omitted for a duplicate symbol then it's possible for
  25 # multiple code sites to be printed:
  26 #
  27 #   $ ./scripts/faddr2line ~/k/vmlinux raw_ioctl+0x5
  28 #   raw_ioctl+0x5/0x20:
  29 #   raw_ioctl at drivers/char/raw.c:122
  30 #
  31 #   raw_ioctl+0x5/0xb1:
  32 #   raw_ioctl at net/ipv4/raw.c:876
  33 #
  34 # Multiple addresses can be specified on a single command line:
  35 #
  36 #   $ ./scripts/faddr2line ~/k/vmlinux type_show+0x10/45 free_reserved_area+0x90
  37 #   type_show+0x10/0x2d:
  38 #   type_show at drivers/video/backlight/backlight.c:213
  39 #
  40 #   free_reserved_area+0x90/0x123:
  41 #   free_reserved_area at mm/page_alloc.c:6429 (discriminator 2)
  42
  43
  44 set -o errexit
  45 set -o nounset
  46
  47 READELF="${CROSS_COMPILE:-}readelf"
  48 ADDR2LINE="${CROSS_COMPILE:-}addr2line"
  49 SIZE="${CROSS_COMPILE:-}size"
  50 NM="${CROSS_COMPILE:-}nm"
  51
  52 command -v awk >/dev/null 2>&1 || die "awk isn't installed"
  53 command -v ${READELF} >/dev/null 2>&1 || die "readelf isn't installed"
  54 command -v ${ADDR2LINE} >/dev/null 2>&1 || die "addr2line isn't installed"
  55 command -v ${SIZE} >/dev/null 2>&1 || die "size isn't installed"
  56 command -v ${NM} >/dev/null 2>&1 || die "nm isn't installed"
  57
  58 usage() {
  59         echo "usage: faddr2line <object file> <func+offset> <func+offset>..." >&2
  60         exit 1
  61 }
  62
  63 warn() {
  64         echo "$1" >&2
  65 }
  66
  67 die() {
  68         echo "ERROR: $1" >&2
  69         exit 1
  70 }
  71
  72 # Try to figure out the source directory prefix so we can remove it from the
  73 # addr2line output.  HACK ALERT: This assumes that start_kernel() is in
  74 # kernel/init.c!  This only works for vmlinux.  Otherwise it falls back to
  75 # printing the absolute path.
  76 find_dir_prefix() {
  77         local objfile=$1
  78
  79         local start_kernel_addr=$(${READELF} -sW $objfile | awk '$8 == "start_kernel" {printf "0x%s", $2}')
  80         [[ -z $start_kernel_addr ]] && return
  81
  82         local file_line=$(${ADDR2LINE} -e $objfile $start_kernel_addr)
  83         [[ -z $file_line ]] && return
  84
  85         local prefix=${file_line%init/main.c:*}
  86         if [[ -z $prefix ]] || [[ $prefix = $file_line ]]; then
  87                 return
  88         fi
  89
  90         DIR_PREFIX=$prefix
  91         return 0
  92 }
  93
  94 __faddr2line() {
  95         local objfile=$1
  96         local func_addr=$2
  97         local dir_prefix=$3
  98         local print_warnings=$4
  99
 100         local func=${func_addr%+*}
 101         local offset=${func_addr#*+}
 102         offset=${offset%/*}
 103         local size=
 104         [[ $func_addr =~ "/" ]] && size=${func_addr#*/}
 105
 106         if [[ -z $func ]] || [[ -z $offset ]] || [[ $func = $func_addr ]]; then
 107                 warn "bad func+offset $func_addr"
 108                 DONE=1
 109                 return
 110         fi
 111
 112         # Go through each of the object's symbols which match the func name.
 113         # In rare cases there might be duplicates.
 114         file_end=$(${SIZE} -Ax $objfile | awk '$1 == ".text" {print $2}')
 115         while read symbol; do
 116                 local fields=($symbol)
 117                 local sym_base=0x${fields[0]}
 118                 local sym_type=${fields[1]}
 119                 local sym_end=${fields[3]}
 120
 121                 # calculate the size
 122                 local sym_size=$(($sym_end - $sym_base))
 123                 if [[ -z $sym_size ]] || [[ $sym_size -le 0 ]]; then
 124                         warn "bad symbol size: base: $sym_base end: $sym_end"
 125                         DONE=1
 126                         return
 127                 fi
 128                 sym_size=0x$(printf %x $sym_size)
 129
 130                 # calculate the address
 131                 local addr=$(($sym_base + $offset))
 132                 if [[ -z $addr ]] || [[ $addr = 0 ]]; then
 133                         warn "bad address: $sym_base + $offset"
 134                         DONE=1
 135                         return
 136                 fi
 137                 addr=0x$(printf %x $addr)
 138
 139                 # weed out non-function symbols
 140                 if [[ $sym_type != t ]] && [[ $sym_type != T ]]; then
 141                         [[ $print_warnings = 1 ]] &&
 142                                 echo "skipping $func address at $addr due to non-function symbol of type '$sym_type'"
 143                         continue
 144                 fi
 145
 146                 # if the user provided a size, make sure it matches the symbol's size
 147                 if [[ -n $size ]] && [[ $size -ne $sym_size ]]; then
 148                         [[ $print_warnings = 1 ]] &&
 149                                 echo "skipping $func address at $addr due to size mismatch ($size != $sym_size)"
 150                         continue;
 151                 fi
 152
 153                 # make sure the provided offset is within the symbol's range
 154                 if [[ $offset -gt $sym_size ]]; then
 155                         [[ $print_warnings = 1 ]] &&
 156                                 echo "skipping $func address at $addr due to size mismatch ($offset > $sym_size)"
 157                         continue
 158                 fi
 159
 160                 # separate multiple entries with a blank line
 161                 [[ $FIRST = 0 ]] && echo
 162                 FIRST=0
 163
 164                 # pass real address to addr2line
 165                 echo "$func+$offset/$sym_size:"
 166                 ${ADDR2LINE} -fpie $objfile $addr | sed "s; $dir_prefix\(\./\)*; ;"
 167                 DONE=1
 168
 169         done < <(${NM} -n $objfile | awk -v fn=$func -v end=$file_end '$3 == fn { found=1; line=$0; start=$1; next } found == 1 { found=0; print line, "0x"$1 } END {if (found == 1) print line, end; }')
 170 }
 171
 172 [[ $# -lt 2 ]] && usage
 173
 174 objfile=$1
 175 [[ ! -f $objfile ]] && die "can't find objfile $objfile"
 176 shift
 177
 178 DIR_PREFIX=supercalifragilisticexpialidocious
 179 find_dir_prefix $objfile
 180
 181 FIRST=1
 182 while [[ $# -gt 0 ]]; do
 183         func_addr=$1
 184         shift
 185
 186         # print any matches found
 187         DONE=0
 188         __faddr2line $objfile $func_addr $DIR_PREFIX 0
 189
 190         # if no match was found, print warnings
 191         if [[ $DONE = 0 ]]; then
 192                 __faddr2line $objfile $func_addr $DIR_PREFIX 1
 193                 warn "no match for $func_addr"
 194         fi
 195 done