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 usage() {
  48         echo "usage: faddr2line [--list] <object file> <func+offset> <func+offset>..." >&2
  49         exit 1
  50 }
  51
  52 warn() {
  53         echo "$1" >&2
  54 }
  55
  56 die() {
  57         echo "ERROR: $1" >&2
  58         exit 1
  59 }
  60
  61 READELF="${CROSS_COMPILE:-}readelf"
  62 ADDR2LINE="${CROSS_COMPILE:-}addr2line"
  63 AWK="awk"
  64
  65 command -v ${AWK} >/dev/null 2>&1 || die "${AWK} isn't installed"
  66 command -v ${READELF} >/dev/null 2>&1 || die "${READELF} isn't installed"
  67 command -v ${ADDR2LINE} >/dev/null 2>&1 || die "${ADDR2LINE} isn't installed"
  68
  69 # Try to figure out the source directory prefix so we can remove it from the
  70 # addr2line output.  HACK ALERT: This assumes that start_kernel() is in
  71 # init/main.c!  This only works for vmlinux.  Otherwise it falls back to
  72 # printing the absolute path.
  73 find_dir_prefix() {
  74         local objfile=$1
  75
  76         local start_kernel_addr=$(${READELF} --symbols --wide $objfile | ${AWK} '$8 == "start_kernel" {printf "0x%s", $2}')
  77         [[ -z $start_kernel_addr ]] && return
  78
  79         local file_line=$(${ADDR2LINE} -e $objfile $start_kernel_addr)
  80         [[ -z $file_line ]] && return
  81
  82         local prefix=${file_line%init/main.c:*}
  83         if [[ -z $prefix ]] || [[ $prefix = $file_line ]]; then
  84                 return
  85         fi
  86
  87         DIR_PREFIX=$prefix
  88         return 0
  89 }
  90
  91 __faddr2line() {
  92         local objfile=$1
  93         local func_addr=$2
  94         local dir_prefix=$3
  95         local print_warnings=$4
  96
  97         local sym_name=${func_addr%+*}
  98         local func_offset=${func_addr#*+}
  99         func_offset=${func_offset%/*}
 100         local user_size=
 101         local file_type
 102         local is_vmlinux=0
 103         [[ $func_addr =~ "/" ]] && user_size=${func_addr#*/}
 104
 105         if [[ -z $sym_name ]] || [[ -z $func_offset ]] || [[ $sym_name = $func_addr ]]; then
 106                 warn "bad func+offset $func_addr"
 107                 DONE=1
 108                 return
 109         fi
 110
 111         # vmlinux uses absolute addresses in the section table rather than
 112         # section offsets.
 113         local file_type=$(${READELF} --file-header $objfile |
 114                 ${AWK} '$1 == "Type:" { print $2; exit }')
 115         [[ $file_type = "EXEC" ]] && is_vmlinux=1
 116
 117         # Go through each of the object's symbols which match the func name.
 118         # In rare cases there might be duplicates, in which case we print all
 119         # matches.
 120         while read line; do
 121                 local fields=($line)
 122                 local sym_addr=0x${fields[1]}
 123                 local sym_elf_size=${fields[2]}
 124                 local sym_sec=${fields[6]}
 125                 local sec_size
 126                 local sec_name
 127
 128                 # Get the section size:
 129                 sec_size=$(${READELF} --section-headers --wide $objfile |
 130                         sed 's/\[ /\[/' |
 131                         ${AWK} -v sec=$sym_sec '$1 == "[" sec "]" { print "0x" $6; exit }')
 132
 133                 if [[ -z $sec_size ]]; then
 134                         warn "bad section size: section: $sym_sec"
 135                         DONE=1
 136                         return
 137                 fi
 138
 139                 # Get the section name:
 140                 sec_name=$(${READELF} --section-headers --wide $objfile |
 141                         sed 's/\[ /\[/' |
 142                         ${AWK} -v sec=$sym_sec '$1 == "[" sec "]" { print $2; exit }')
 143
 144                 if [[ -z $sec_name ]]; then
 145                         warn "bad section name: section: $sym_sec"
 146                         DONE=1
 147                         return
 148                 fi
 149
 150                 # Calculate the symbol size.
 151                 #
 152                 # Unfortunately we can't use the ELF size, because kallsyms
 153                 # also includes the padding bytes in its size calculation.  For
 154                 # kallsyms, the size calculation is the distance between the
 155                 # symbol and the next symbol in a sorted list.
 156                 local sym_size
 157                 local cur_sym_addr
 158                 local found=0
 159                 while read line; do
 160                         local fields=($line)
 161                         cur_sym_addr=0x${fields[1]}
 162                         local cur_sym_elf_size=${fields[2]}
 163                         local cur_sym_name=${fields[7]:-}
 164
 165                         if [[ $cur_sym_addr = $sym_addr ]] &&
 166                            [[ $cur_sym_elf_size = $sym_elf_size ]] &&
 167                            [[ $cur_sym_name = $sym_name ]]; then
 168                                 found=1
 169                                 continue
 170                         fi
 171
 172                         if [[ $found = 1 ]]; then
 173                                 sym_size=$(($cur_sym_addr - $sym_addr))
 174                                 [[ $sym_size -lt $sym_elf_size ]] && continue;
 175                                 found=2
 176                                 break
 177                         fi
 178                 done < <(${READELF} --symbols --wide $objfile | ${AWK} -v sec=$sym_sec '$7 == sec' | sort --key=2)
 179
 180                 if [[ $found = 0 ]]; then
 181                         warn "can't find symbol: sym_name: $sym_name sym_sec: $sym_sec sym_addr: $sym_addr sym_elf_size: $sym_elf_size"
 182                         DONE=1
 183                         return
 184                 fi
 185
 186                 # If nothing was found after the symbol, assume it's the last
 187                 # symbol in the section.
 188                 [[ $found = 1 ]] && sym_size=$(($sec_size - $sym_addr))
 189
 190                 if [[ -z $sym_size ]] || [[ $sym_size -le 0 ]]; then
 191                         warn "bad symbol size: sym_addr: $sym_addr cur_sym_addr: $cur_sym_addr"
 192                         DONE=1
 193                         return
 194                 fi
 195
 196                 sym_size=0x$(printf %x $sym_size)
 197
 198                 # Calculate the address from user-supplied offset:
 199                 local addr=$(($sym_addr + $func_offset))
 200                 if [[ -z $addr ]] || [[ $addr = 0 ]]; then
 201                         warn "bad address: $sym_addr + $func_offset"
 202                         DONE=1
 203                         return
 204                 fi
 205                 addr=0x$(printf %x $addr)
 206
 207                 # If the user provided a size, make sure it matches the symbol's size:
 208                 if [[ -n $user_size ]] && [[ $user_size -ne $sym_size ]]; then
 209                         [[ $print_warnings = 1 ]] &&
 210                                 echo "skipping $sym_name address at $addr due to size mismatch ($user_size != $sym_size)"
 211                         continue;
 212                 fi
 213
 214                 # Make sure the provided offset is within the symbol's range:
 215                 if [[ $func_offset -gt $sym_size ]]; then
 216                         [[ $print_warnings = 1 ]] &&
 217                                 echo "skipping $sym_name address at $addr due to size mismatch ($func_offset > $sym_size)"
 218                         continue
 219                 fi
 220
 221                 # In case of duplicates or multiple addresses specified on the
 222                 # cmdline, separate multiple entries with a blank line:
 223                 [[ $FIRST = 0 ]] && echo
 224                 FIRST=0
 225
 226                 echo "$sym_name+$func_offset/$sym_size:"
 227
 228                 # Pass section address to addr2line and strip absolute paths
 229                 # from the output:
 230                 local args="--functions --pretty-print --inlines --exe=$objfile"
 231                 [[ $is_vmlinux = 0 ]] && args="$args --section=$sec_name"
 232                 local output=$(${ADDR2LINE} $args $addr | sed "s; $dir_prefix\(\./\)*; ;")
 233                 [[ -z $output ]] && continue
 234
 235                 # Default output (non --list):
 236                 if [[ $LIST = 0 ]]; then
 237                         echo "$output" | while read -r line
 238                         do
 239                                 echo $line
 240                         done
 241                         DONE=1;
 242                         continue
 243                 fi
 244
 245                 # For --list, show each line with its corresponding source code:
 246                 echo "$output" | while read -r line
 247                 do
 248                         echo
 249                         echo $line
 250                         n=$(echo $line | sed 's/.*:\([0-9]\+\).*/\1/g')
 251                         n1=$[$n-5]
 252                         n2=$[$n+5]
 253                         f=$(echo $line | sed 's/.*at \(.\+\):.*/\1/g')
 254                         ${AWK} 'NR>=strtonum("'$n1'") && NR<=strtonum("'$n2'") { if (NR=='$n') printf(">%d<", NR); else printf(" %d ", NR); printf("\t%s\n", $0)}' $f
 255                 done
 256
 257                 DONE=1
 258
 259         done < <(${READELF} --symbols --wide $objfile | ${AWK} -v fn=$sym_name '$4 == "FUNC" && $8 == fn')
 260 }
 261
 262 [[ $# -lt 2 ]] && usage
 263
 264 objfile=$1
 265
 266 LIST=0
 267 [[ "$objfile" == "--list" ]] && LIST=1 && shift && objfile=$1
 268
 269 [[ ! -f $objfile ]] && die "can't find objfile $objfile"
 270 shift
 271
 272 DIR_PREFIX=supercalifragilisticexpialidocious
 273 find_dir_prefix $objfile
 274
 275 FIRST=1
 276 while [[ $# -gt 0 ]]; do
 277         func_addr=$1
 278         shift
 279
 280         # print any matches found
 281         DONE=0
 282         __faddr2line $objfile $func_addr $DIR_PREFIX 0
 283
 284         # if no match was found, print warnings
 285         if [[ $DONE = 0 ]]; then
 286                 __faddr2line $objfile $func_addr $DIR_PREFIX 1
 287                 warn "no match for $func_addr"
 288         fi
 289 done