scripts/faddr2line

   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
  43 set -o errexit
  44 set -o nounset
  45
  46 command -v awk >/dev/null 2>&1 || die "awk isn't installed"
  47 command -v readelf >/dev/null 2>&1 || die "readelf isn't installed"
  48 command -v addr2line >/dev/null 2>&1 || die "addr2line isn't installed"
  49
  50 usage() {
  51         echo "usage: faddr2line <object file> <func+offset> <func+offset>..." >&2
  52         exit 1
  53 }
  54
  55 warn() {
  56         echo "$1" >&2
  57 }
  58
  59 die() {
  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.
  68 find_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 $func_addr"
 100                 DONE=1
 101                 return
 102         fi
 103
 104         # Go through each of the object's symbols which match the func name.
 105         # In rare cases there might be duplicates.
 106         file_end=$(size -Ax $objfile | awk '$1 == ".text" {print $2}')
 107         while read symbol; do
 108                 local fields=($symbol)
 109                 local sym_base=0x${fields[0]}
 110                 local sym_type=${fields[1]}
 111                 local sym_end=${fields[3]}
 112
 113                 # calculate the size
 114                 local sym_size=$(($sym_end - $sym_base))
 115                 if [[ -z $sym_size ]] || [[ $sym_size -le 0 ]]; then
 116                         warn "bad symbol size: base: $sym_base end: $sym_end"
 117                         DONE=1
 118                         return
 119                 fi
 120                 sym_size=0x$(printf %x $sym_size)
 121
 122                 # calculate the address
 123                 local addr=$(($sym_base + $offset))
 124                 if [[ -z $addr ]] || [[ $addr = 0 ]]; then
 125                         warn "bad address: $sym_base + $offset"
 126                         DONE=1
 127                         return
 128                 fi
 129                 addr=0x$(printf %x $addr)
 130
 131                 # weed out non-function symbols
 132                 if [[ $sym_type != t ]] && [[ $sym_type != T ]]; then
 133                         [[ $print_warnings = 1 ]] &&
 134                                 echo "skipping $func address at $addr due to non-function symbol of type '$sym_type'"
 135                         continue
 136                 fi
 137
 138                 # if the user provided a size, make sure it matches the symbol's size
 139                 if [[ -n $size ]] && [[ $size -ne $sym_size ]]; then
 140                         [[ $print_warnings = 1 ]] &&
 141                                 echo "skipping $func address at $addr due to size mismatch ($size != $sym_size)"
 142                         continue;
 143                 fi
 144
 145                 # make sure the provided offset is within the symbol's range
 146                 if [[ $offset -gt $sym_size ]]; then
 147                         [[ $print_warnings = 1 ]] &&
 148                                 echo "skipping $func address at $addr due to size mismatch ($offset > $sym_size)"
 149                         continue
 150                 fi
 151
 152                 # separate multiple entries with a blank line
 153                 [[ $FIRST = 0 ]] && echo
 154                 FIRST=0
 155
 156                 # pass real address to addr2line
 157                 echo "$func+$offset/$sym_size:"
 158                 addr2line -fpie $objfile $addr | sed "s; $dir_prefix\(\./\)*; ;"
 159                 DONE=1
 160
 161         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; }')
 162 }
 163
 164 [[ $# -lt 2 ]] && usage
 165
 166 objfile=$1
 167 [[ ! -f $objfile ]] && die "can't find objfile $objfile"
 168 shift
 169
 170 DIR_PREFIX=supercalifragilisticexpialidocious
 171 find_dir_prefix $objfile
 172
 173 FIRST=1
 174 while [[ $# -gt 0 ]]; do
 175         func_addr=$1
 176         shift
 177
 178         # print any matches found
 179         DONE=0
 180         __faddr2line $objfile $func_addr $DIR_PREFIX 0
 181
 182         # if no match was found, print warnings
 183         if [[ $DONE = 0 ]]; then
 184                 __faddr2line $objfile $func_addr $DIR_PREFIX 1
 185                 warn "no match for $func_addr"
 186         fi
 187 done