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 command -v awk >/dev/null 2>&1 || die "awk isn't installed"
  48 command -v readelf >/dev/null 2>&1 || die "readelf isn't installed"
  49 command -v addr2line >/dev/null 2>&1 || die "addr2line isn't installed"
  50
  51 usage() {
  52         echo "usage: faddr2line <object file> <func+offset> <func+offset>..." >&2
  53         exit 1
  54 }
  55
  56 warn() {
  57         echo "$1" >&2
  58 }
  59
  60 die() {
  61         echo "ERROR: $1" >&2
  62         exit 1
  63 }
  64
  65 # Try to figure out the source directory prefix so we can remove it from the
  66 # addr2line output.  HACK ALERT: This assumes that start_kernel() is in
  67 # kernel/init.c!  This only works for vmlinux.  Otherwise it falls back to
  68 # printing the absolute path.
  69 find_dir_prefix() {
  70         local objfile=$1
  71
  72         local start_kernel_addr=$(readelf -sW $objfile | awk '$8 == "start_kernel" {printf "0x%s", $2}')
  73         [[ -z $start_kernel_addr ]] && return
  74
  75         local file_line=$(addr2line -e $objfile $start_kernel_addr)
  76         [[ -z $file_line ]] && return
  77
  78         local prefix=${file_line%init/main.c:*}
  79         if [[ -z $prefix ]] || [[ $prefix = $file_line ]]; then
  80                 return
  81         fi
  82
  83         DIR_PREFIX=$prefix
  84         return 0
  85 }
  86
  87 __faddr2line() {
  88         local objfile=$1
  89         local func_addr=$2
  90         local dir_prefix=$3
  91         local print_warnings=$4
  92
  93         local func=${func_addr%+*}
  94         local offset=${func_addr#*+}
  95         offset=${offset%/*}
  96         local size=
  97         [[ $func_addr =~ "/" ]] && size=${func_addr#*/}
  98
  99         if [[ -z $func ]] || [[ -z $offset ]] || [[ $func = $func_addr ]]; then
 100                 warn "bad func+offset $func_addr"
 101                 DONE=1
 102                 return
 103         fi
 104
 105         # Go through each of the object's symbols which match the func name.
 106         # In rare cases there might be duplicates.
 107         file_end=$(size -Ax $objfile | awk '$1 == ".text" {print $2}')
 108         while read symbol; do
 109                 local fields=($symbol)
 110                 local sym_base=0x${fields[0]}
 111                 local sym_type=${fields[1]}
 112                 local sym_end=${fields[3]}
 113
 114                 # calculate the size
 115                 local sym_size=$(($sym_end - $sym_base))
 116                 if [[ -z $sym_size ]] || [[ $sym_size -le 0 ]]; then
 117                         warn "bad symbol size: base: $sym_base end: $sym_end"
 118                         DONE=1
 119                         return
 120                 fi
 121                 sym_size=0x$(printf %x $sym_size)
 122
 123                 # calculate the address
 124                 local addr=$(($sym_base + $offset))
 125                 if [[ -z $addr ]] || [[ $addr = 0 ]]; then
 126                         warn "bad address: $sym_base + $offset"
 127                         DONE=1
 128                         return
 129                 fi
 130                 addr=0x$(printf %x $addr)
 131
 132                 # weed out non-function symbols
 133                 if [[ $sym_type != t ]] && [[ $sym_type != T ]]; then
 134                         [[ $print_warnings = 1 ]] &&
 135                                 echo "skipping $func address at $addr due to non-function symbol of type '$sym_type'"
 136                         continue
 137                 fi
 138
 139                 # if the user provided a size, make sure it matches the symbol's size
 140                 if [[ -n $size ]] && [[ $size -ne $sym_size ]]; then
 141                         [[ $print_warnings = 1 ]] &&
 142                                 echo "skipping $func address at $addr due to size mismatch ($size != $sym_size)"
 143                         continue;
 144                 fi
 145
 146                 # make sure the provided offset is within the symbol's range
 147                 if [[ $offset -gt $sym_size ]]; then
 148                         [[ $print_warnings = 1 ]] &&
 149                                 echo "skipping $func address at $addr due to size mismatch ($offset > $sym_size)"
 150                         continue
 151                 fi
 152
 153                 # separate multiple entries with a blank line
 154                 [[ $FIRST = 0 ]] && echo
 155                 FIRST=0
 156
 157                 # pass real address to addr2line
 158                 echo "$func+$offset/$sym_size:"
 159                 addr2line -fpie $objfile $addr | sed "s; $dir_prefix\(\./\)*; ;"
 160                 DONE=1
 161
 162         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; }')
 163 }
 164
 165 [[ $# -lt 2 ]] && usage
 166
 167 objfile=$1
 168 [[ ! -f $objfile ]] && die "can't find objfile $objfile"
 169 shift
 170
 171 DIR_PREFIX=supercalifragilisticexpialidocious
 172 find_dir_prefix $objfile
 173
 174 FIRST=1
 175 while [[ $# -gt 0 ]]; do
 176         func_addr=$1
 177         shift
 178
 179         # print any matches found
 180         DONE=0
 181         __faddr2line $objfile $func_addr $DIR_PREFIX 0
 182
 183         # if no match was found, print warnings
 184         if [[ $DONE = 0 ]]; then
 185                 __faddr2line $objfile $func_addr $DIR_PREFIX 1
 186                 warn "no match for $func_addr"
 187         fi
 188 done