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: $1" >&2
  58         exit 1
  59 }
  60
  61 UTIL_SUFFIX=""
  62 if [[ "${LLVM:-}" == "" ]]; then
  63         UTIL_PREFIX=${CROSS_COMPILE:-}
  64 else
  65         UTIL_PREFIX=llvm-
  66
  67         if [[ "${LLVM}" == *"/" ]]; then
  68                 UTIL_PREFIX=${LLVM}${UTIL_PREFIX}
  69         elif [[ "${LLVM}" == "-"* ]]; then
  70                 UTIL_SUFFIX=${LLVM}
  71         fi
  72 fi
  73
  74 READELF="${UTIL_PREFIX}readelf${UTIL_SUFFIX}"
  75 ADDR2LINE="${UTIL_PREFIX}addr2line${UTIL_SUFFIX}"
  76 AWK="awk"
  77 GREP="grep"
  78
  79 command -v ${AWK} >/dev/null 2>&1 || die "${AWK} isn't installed"
  80 command -v ${READELF} >/dev/null 2>&1 || die "${READELF} isn't installed"
  81 command -v ${ADDR2LINE} >/dev/null 2>&1 || die "${ADDR2LINE} isn't installed"
  82
  83 # Try to figure out the source directory prefix so we can remove it from the
  84 # addr2line output.  HACK ALERT: This assumes that start_kernel() is in
  85 # init/main.c!  This only works for vmlinux.  Otherwise it falls back to
  86 # printing the absolute path.
  87 find_dir_prefix() {
  88         local objfile=$1
  89
  90         local start_kernel_addr=$(${READELF} --symbols --wide $objfile | sed 's/\[.*\]//' |
  91                 ${AWK} '$8 == "start_kernel" {printf "0x%s", $2}')
  92         [[ -z $start_kernel_addr ]] && return
  93
  94         local file_line=$(${ADDR2LINE} -e $objfile $start_kernel_addr)
  95         [[ -z $file_line ]] && return
  96
  97         local prefix=${file_line%init/main.c:*}
  98         if [[ -z $prefix ]] || [[ $prefix = $file_line ]]; then
  99                 return
 100         fi
 101
 102         DIR_PREFIX=$prefix
 103         return 0
 104 }
 105
 106 __faddr2line() {
 107         local objfile=$1
 108         local func_addr=$2
 109         local dir_prefix=$3
 110         local print_warnings=$4
 111
 112         local sym_name=${func_addr%+*}
 113         local func_offset=${func_addr#*+}
 114         func_offset=${func_offset%/*}
 115         local user_size=
 116         local file_type
 117         local is_vmlinux=0
 118         [[ $func_addr =~ "/" ]] && user_size=${func_addr#*/}
 119
 120         if [[ -z $sym_name ]] || [[ -z $func_offset ]] || [[ $sym_name = $func_addr ]]; then
 121                 warn "bad func+offset $func_addr"
 122                 DONE=1
 123                 return
 124         fi
 125
 126         # vmlinux uses absolute addresses in the section table rather than
 127         # section offsets.
 128         local file_type=$(${READELF} --file-header $objfile |
 129                 ${AWK} '$1 == "Type:" { print $2; exit }')
 130         if [[ $file_type = "EXEC" ]] || [[ $file_type == "DYN" ]]; then
 131                 is_vmlinux=1
 132         fi
 133
 134         # Go through each of the object's symbols which match the func name.
 135         # In rare cases there might be duplicates, in which case we print all
 136         # matches.
 137         while read line; do
 138                 local fields=($line)
 139                 local sym_addr=0x${fields[1]}
 140                 local sym_elf_size=${fields[2]}
 141                 local sym_sec=${fields[6]}
 142                 local sec_size
 143                 local sec_name
 144
 145                 # Get the section size:
 146                 sec_size=$(${READELF} --section-headers --wide $objfile |
 147                         sed 's/\[ /\[/' |
 148                         ${AWK} -v sec=$sym_sec '$1 == "[" sec "]" { print "0x" $6; exit }')
 149
 150                 if [[ -z $sec_size ]]; then
 151                         warn "bad section size: section: $sym_sec"
 152                         DONE=1
 153                         return
 154                 fi
 155
 156                 # Get the section name:
 157                 sec_name=$(${READELF} --section-headers --wide $objfile |
 158                         sed 's/\[ /\[/' |
 159                         ${AWK} -v sec=$sym_sec '$1 == "[" sec "]" { print $2; exit }')
 160
 161                 if [[ -z $sec_name ]]; then
 162                         warn "bad section name: section: $sym_sec"
 163                         DONE=1
 164                         return
 165                 fi
 166
 167                 # Calculate the symbol size.
 168                 #
 169                 # Unfortunately we can't use the ELF size, because kallsyms
 170                 # also includes the padding bytes in its size calculation.  For
 171                 # kallsyms, the size calculation is the distance between the
 172                 # symbol and the next symbol in a sorted list.
 173                 local sym_size
 174                 local cur_sym_addr
 175                 local found=0
 176                 while read line; do
 177                         local fields=($line)
 178                         cur_sym_addr=0x${fields[1]}
 179                         local cur_sym_elf_size=${fields[2]}
 180                         local cur_sym_name=${fields[7]:-}
 181
 182                         # is_mapping_symbol(cur_sym_name)
 183                         if [[ ${cur_sym_name} =~ ^(\.L|L0|\$) ]]; then
 184                                 continue
 185                         fi
 186
 187                         if [[ $cur_sym_addr = $sym_addr ]] &&
 188                            [[ $cur_sym_elf_size = $sym_elf_size ]] &&
 189                            [[ $cur_sym_name = $sym_name ]]; then
 190                                 found=1
 191                                 continue
 192                         fi
 193
 194                         if [[ $found = 1 ]]; then
 195                                 sym_size=$(($cur_sym_addr - $sym_addr))
 196                                 [[ $sym_size -lt $sym_elf_size ]] && continue;
 197                                 found=2
 198                                 break
 199                         fi
 200                 done < <(${READELF} --symbols --wide $objfile | sed 's/\[.*\]//' | ${AWK} -v sec=$sym_sec '$7 == sec' | sort --key=2)
 201
 202                 if [[ $found = 0 ]]; then
 203                         warn "can't find symbol: sym_name: $sym_name sym_sec: $sym_sec sym_addr: $sym_addr sym_elf_size: $sym_elf_size"
 204                         DONE=1
 205                         return
 206                 fi
 207
 208                 # If nothing was found after the symbol, assume it's the last
 209                 # symbol in the section.
 210                 [[ $found = 1 ]] && sym_size=$(($sec_size - $sym_addr))
 211
 212                 if [[ -z $sym_size ]] || [[ $sym_size -le 0 ]]; then
 213                         warn "bad symbol size: sym_addr: $sym_addr cur_sym_addr: $cur_sym_addr"
 214                         DONE=1
 215                         return
 216                 fi
 217
 218                 sym_size=0x$(printf %x $sym_size)
 219
 220                 # Calculate the address from user-supplied offset:
 221                 local addr=$(($sym_addr + $func_offset))
 222                 if [[ -z $addr ]] || [[ $addr = 0 ]]; then
 223                         warn "bad address: $sym_addr + $func_offset"
 224                         DONE=1
 225                         return
 226                 fi
 227                 addr=0x$(printf %x $addr)
 228
 229                 # If the user provided a size, make sure it matches the symbol's size:
 230                 if [[ -n $user_size ]] && [[ $user_size -ne $sym_size ]]; then
 231                         [[ $print_warnings = 1 ]] &&
 232                                 echo "skipping $sym_name address at $addr due to size mismatch ($user_size != $sym_size)"
 233                         continue;
 234                 fi
 235
 236                 # Make sure the provided offset is within the symbol's range:
 237                 if [[ $func_offset -gt $sym_size ]]; then
 238                         [[ $print_warnings = 1 ]] &&
 239                                 echo "skipping $sym_name address at $addr due to size mismatch ($func_offset > $sym_size)"
 240                         continue
 241                 fi
 242
 243                 # In case of duplicates or multiple addresses specified on the
 244                 # cmdline, separate multiple entries with a blank line:
 245                 [[ $FIRST = 0 ]] && echo
 246                 FIRST=0
 247
 248                 echo "$sym_name+$func_offset/$sym_size:"
 249
 250                 # Pass section address to addr2line and strip absolute paths
 251                 # from the output:
 252                 local args="--functions --pretty-print --inlines --exe=$objfile"
 253                 [[ $is_vmlinux = 0 ]] && args="$args --section=$sec_name"
 254                 local output=$(${ADDR2LINE} $args $addr | sed "s; $dir_prefix\(\./\)*; ;")
 255                 [[ -z $output ]] && continue
 256
 257                 # Default output (non --list):
 258                 if [[ $LIST = 0 ]]; then
 259                         echo "$output" | while read -r line
 260                         do
 261                                 echo $line
 262                         done
 263                         DONE=1;
 264                         continue
 265                 fi
 266
 267                 # For --list, show each line with its corresponding source code:
 268                 echo "$output" | while read -r line
 269                 do
 270                         echo
 271                         echo $line
 272                         n=$(echo $line | sed 's/.*:\([0-9]\+\).*/\1/g')
 273                         n1=$[$n-5]
 274                         n2=$[$n+5]
 275                         f=$(echo $line | sed 's/.*at \(.\+\):.*/\1/g')
 276                         ${AWK} 'NR>=strtonum("'$n1'") && NR<=strtonum("'$n2'") { if (NR=='$n') printf(">%d<", NR); else printf(" %d ", NR); printf("\t%s\n", $0)}' $f
 277                 done
 278
 279                 DONE=1
 280
 281         done < <(${READELF} --symbols --wide $objfile | sed 's/\[.*\]//' | ${AWK} -v fn=$sym_name '$8 == fn')
 282 }
 283
 284 [[ $# -lt 2 ]] && usage
 285
 286 objfile=$1
 287
 288 LIST=0
 289 [[ "$objfile" == "--list" ]] && LIST=1 && shift && objfile=$1
 290
 291 [[ ! -f $objfile ]] && die "can't find objfile $objfile"
 292 shift
 293
 294 ${READELF} --section-headers --wide $objfile | ${GREP} -q '\.debug_info' || die "CONFIG_DEBUG_INFO not enabled"
 295
 296 DIR_PREFIX=supercalifragilisticexpialidocious
 297 find_dir_prefix $objfile
 298
 299 FIRST=1
 300 while [[ $# -gt 0 ]]; do
 301         func_addr=$1
 302         shift
 303
 304         # print any matches found
 305         DONE=0
 306         __faddr2line $objfile $func_addr $DIR_PREFIX 0
 307
 308         # if no match was found, print warnings
 309         if [[ $DONE = 0 ]]; then
 310                 __faddr2line $objfile $func_addr $DIR_PREFIX 1
 311                 warn "no match for $func_addr"
 312         fi
 313 done