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