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 start_kernel_addr=$(echo "${ELF_SYMS}" | sed 's/\[.*\]//' |
  89                 ${AWK} '$8 == "start_kernel" {printf "0x%s", $2}')
  90         [[ -z $start_kernel_addr ]] && return
  91
  92         run_addr2line ${start_kernel_addr} ""
  93         [[ -z $ADDR2LINE_OUT ]] && return
  94
  95         local file_line=${ADDR2LINE_OUT#* at }
  96         if [[ -z $file_line ]] || [[ $file_line = $ADDR2LINE_OUT ]]; then
  97                 return
  98         fi
  99         local prefix=${file_line%init/main.c:*}
 100         if [[ -z $prefix ]] || [[ $prefix = $file_line ]]; then
 101                 return
 102         fi
 103
 104         DIR_PREFIX=$prefix
 105         return 0
 106 }
 107
 108 run_readelf() {
 109         local objfile=$1
 110         local out=$(${READELF} --file-header --section-headers --symbols --wide $objfile)
 111
 112         # This assumes that readelf first prints the file header, then the section headers, then the symbols.
 113         # Note: It seems that GNU readelf does not prefix section headers with the "There are X section headers"
 114         # line when multiple options are given, so let's also match with the "Section Headers:" line.
 115         ELF_FILEHEADER=$(echo "${out}" | sed -n '/There are [0-9]* section headers, starting at offset\|Section Headers:/q;p')
 116         ELF_SECHEADERS=$(echo "${out}" | sed -n '/There are [0-9]* section headers, starting at offset\|Section Headers:/,$p' | sed -n '/Symbol table .* contains [0-9]* entries:/q;p')
 117         ELF_SYMS=$(echo "${out}" | sed -n '/Symbol table .* contains [0-9]* entries:/,$p')
 118 }
 119
 120 check_vmlinux() {
 121         # vmlinux uses absolute addresses in the section table rather than
 122         # section offsets.
 123         IS_VMLINUX=0
 124         local file_type=$(echo "${ELF_FILEHEADER}" |
 125                 ${AWK} '$1 == "Type:" { print $2; exit }')
 126         if [[ $file_type = "EXEC" ]] || [[ $file_type == "DYN" ]]; then
 127                 IS_VMLINUX=1
 128         fi
 129 }
 130
 131 init_addr2line() {
 132         local objfile=$1
 133
 134         check_vmlinux
 135
 136         ADDR2LINE_ARGS="--functions --pretty-print --inlines --addresses --exe=$objfile"
 137         if [[ $IS_VMLINUX = 1 ]]; then
 138                 # If the executable file is vmlinux, we don't pass section names to
 139                 # addr2line, so we can launch it now as a single long-running process.
 140                 coproc ADDR2LINE_PROC (${ADDR2LINE} ${ADDR2LINE_ARGS})
 141         fi
 142 }
 143
 144 run_addr2line() {
 145         local addr=$1
 146         local sec_name=$2
 147
 148         if [[ $IS_VMLINUX = 1 ]]; then
 149                 # We send to the addr2line process: (1) the address, then (2) a sentinel
 150                 # value, i.e., something that can't be interpreted as a valid address
 151                 # (i.e., ","). This causes addr2line to write out: (1) the answer for
 152                 # our address, then (2) either "?? ??:0" or "0x0...0: ..." (if
 153                 # using binutils' addr2line), or "," (if using LLVM's addr2line).
 154                 echo ${addr} >& "${ADDR2LINE_PROC[1]}"
 155                 echo "," >& "${ADDR2LINE_PROC[1]}"
 156                 local first_line
 157                 read -r first_line <& "${ADDR2LINE_PROC[0]}"
 158                 ADDR2LINE_OUT=$(echo "${first_line}" | sed 's/^0x[0-9a-fA-F]*: //')
 159                 while read -r line <& "${ADDR2LINE_PROC[0]}"; do
 160                         if [[ "$line" == "?? ??:0" ]] || [[ "$line" == "," ]] || [[ $(echo "$line" | ${GREP} "^0x00*: ") ]]; then
 161                                 break
 162                         fi
 163                         ADDR2LINE_OUT+=$'\n'$(echo "$line" | sed 's/^0x[0-9a-fA-F]*: //')
 164                 done
 165         else
 166                 # Run addr2line as a single invocation.
 167                 local sec_arg
 168                 [[ -z $sec_name ]] && sec_arg="" || sec_arg="--section=${sec_name}"
 169                 ADDR2LINE_OUT=$(${ADDR2LINE} ${ADDR2LINE_ARGS} ${sec_arg} ${addr} | sed 's/^0x[0-9a-fA-F]*: //')
 170         fi
 171 }
 172
 173 __faddr2line() {
 174         local objfile=$1
 175         local func_addr=$2
 176         local dir_prefix=$3
 177         local print_warnings=$4
 178
 179         local sym_name=${func_addr%+*}
 180         local func_offset=${func_addr#*+}
 181         func_offset=${func_offset%/*}
 182         local user_size=
 183         [[ $func_addr =~ "/" ]] && user_size=${func_addr#*/}
 184
 185         if [[ -z $sym_name ]] || [[ -z $func_offset ]] || [[ $sym_name = $func_addr ]]; then
 186                 warn "bad func+offset $func_addr"
 187                 DONE=1
 188                 return
 189         fi
 190
 191         # Go through each of the object's symbols which match the func name.
 192         # In rare cases there might be duplicates, in which case we print all
 193         # matches.
 194         while read line; do
 195                 local fields=($line)
 196                 local sym_addr=0x${fields[1]}
 197                 local sym_elf_size=${fields[2]}
 198                 local sym_sec=${fields[6]}
 199                 local sec_size
 200                 local sec_name
 201
 202                 # Get the section size:
 203                 sec_size=$(echo "${ELF_SECHEADERS}" | sed 's/\[ /\[/' |
 204                         ${AWK} -v sec=$sym_sec '$1 == "[" sec "]" { print "0x" $6; exit }')
 205
 206                 if [[ -z $sec_size ]]; then
 207                         warn "bad section size: section: $sym_sec"
 208                         DONE=1
 209                         return
 210                 fi
 211
 212                 # Get the section name:
 213                 sec_name=$(echo "${ELF_SECHEADERS}" | sed 's/\[ /\[/' |
 214                         ${AWK} -v sec=$sym_sec '$1 == "[" sec "]" { print $2; exit }')
 215
 216                 if [[ -z $sec_name ]]; then
 217                         warn "bad section name: section: $sym_sec"
 218                         DONE=1
 219                         return
 220                 fi
 221
 222                 # Calculate the symbol size.
 223                 #
 224                 # Unfortunately we can't use the ELF size, because kallsyms
 225                 # also includes the padding bytes in its size calculation.  For
 226                 # kallsyms, the size calculation is the distance between the
 227                 # symbol and the next symbol in a sorted list.
 228                 local sym_size
 229                 local cur_sym_addr
 230                 local found=0
 231                 while read line; do
 232                         local fields=($line)
 233                         cur_sym_addr=0x${fields[1]}
 234                         local cur_sym_elf_size=${fields[2]}
 235                         local cur_sym_name=${fields[7]:-}
 236
 237                         # is_mapping_symbol(cur_sym_name)
 238                         if [[ ${cur_sym_name} =~ ^(\.L|L0|\$) ]]; then
 239                                 continue
 240                         fi
 241
 242                         if [[ $cur_sym_addr = $sym_addr ]] &&
 243                            [[ $cur_sym_elf_size = $sym_elf_size ]] &&
 244                            [[ $cur_sym_name = $sym_name ]]; then
 245                                 found=1
 246                                 continue
 247                         fi
 248
 249                         if [[ $found = 1 ]]; then
 250                                 sym_size=$(($cur_sym_addr - $sym_addr))
 251                                 [[ $sym_size -lt $sym_elf_size ]] && continue;
 252                                 found=2
 253                                 break
 254                         fi
 255                 done < <(echo "${ELF_SYMS}" | sed 's/\[.*\]//' | ${AWK} -v sec=$sym_sec '$7 == sec' | sort --key=2 | ${GREP} -A1 --no-group-separator " ${sym_name}$")
 256
 257                 if [[ $found = 0 ]]; then
 258                         warn "can't find symbol: sym_name: $sym_name sym_sec: $sym_sec sym_addr: $sym_addr sym_elf_size: $sym_elf_size"
 259                         DONE=1
 260                         return
 261                 fi
 262
 263                 # If nothing was found after the symbol, assume it's the last
 264                 # symbol in the section.
 265                 [[ $found = 1 ]] && sym_size=$(($sec_size - $sym_addr))
 266
 267                 if [[ -z $sym_size ]] || [[ $sym_size -le 0 ]]; then
 268                         warn "bad symbol size: sym_addr: $sym_addr cur_sym_addr: $cur_sym_addr"
 269                         DONE=1
 270                         return
 271                 fi
 272
 273                 sym_size=0x$(printf %x $sym_size)
 274
 275                 # Calculate the address from user-supplied offset:
 276                 local addr=$(($sym_addr + $func_offset))
 277                 if [[ -z $addr ]] || [[ $addr = 0 ]]; then
 278                         warn "bad address: $sym_addr + $func_offset"
 279                         DONE=1
 280                         return
 281                 fi
 282                 addr=0x$(printf %x $addr)
 283
 284                 # If the user provided a size, make sure it matches the symbol's size:
 285                 if [[ -n $user_size ]] && [[ $user_size -ne $sym_size ]]; then
 286                         [[ $print_warnings = 1 ]] &&
 287                                 echo "skipping $sym_name address at $addr due to size mismatch ($user_size != $sym_size)"
 288                         continue;
 289                 fi
 290
 291                 # Make sure the provided offset is within the symbol's range:
 292                 if [[ $func_offset -gt $sym_size ]]; then
 293                         [[ $print_warnings = 1 ]] &&
 294                                 echo "skipping $sym_name address at $addr due to size mismatch ($func_offset > $sym_size)"
 295                         continue
 296                 fi
 297
 298                 # In case of duplicates or multiple addresses specified on the
 299                 # cmdline, separate multiple entries with a blank line:
 300                 [[ $FIRST = 0 ]] && echo
 301                 FIRST=0
 302
 303                 echo "$sym_name+$func_offset/$sym_size:"
 304
 305                 # Pass section address to addr2line and strip absolute paths
 306                 # from the output:
 307                 run_addr2line $addr $sec_name
 308                 local output=$(echo "${ADDR2LINE_OUT}" | sed "s; $dir_prefix\(\./\)*; ;")
 309                 [[ -z $output ]] && continue
 310
 311                 # Default output (non --list):
 312                 if [[ $LIST = 0 ]]; then
 313                         echo "$output" | while read -r line
 314                         do
 315                                 echo $line
 316                         done
 317                         DONE=1;
 318                         continue
 319                 fi
 320
 321                 # For --list, show each line with its corresponding source code:
 322                 echo "$output" | while read -r line
 323                 do
 324                         echo
 325                         echo $line
 326                         n=$(echo $line | sed 's/.*:\([0-9]\+\).*/\1/g')
 327                         n1=$[$n-5]
 328                         n2=$[$n+5]
 329                         f=$(echo $line | sed 's/.*at \(.\+\):.*/\1/g')
 330                         ${AWK} 'NR>=strtonum("'$n1'") && NR<=strtonum("'$n2'") { if (NR=='$n') printf(">%d<", NR); else printf(" %d ", NR); printf("\t%s\n", $0)}' $f
 331                 done
 332
 333                 DONE=1
 334
 335         done < <(echo "${ELF_SYMS}" | sed 's/\[.*\]//' | ${AWK} -v fn=$sym_name '$8 == fn')
 336 }
 337
 338 [[ $# -lt 2 ]] && usage
 339
 340 objfile=$1
 341
 342 LIST=0
 343 [[ "$objfile" == "--list" ]] && LIST=1 && shift && objfile=$1
 344
 345 [[ ! -f $objfile ]] && die "can't find objfile $objfile"
 346 shift
 347
 348 run_readelf $objfile
 349
 350 echo "${ELF_SECHEADERS}" | ${GREP} -q '\.debug_info' || die "CONFIG_DEBUG_INFO not enabled"
 351
 352 init_addr2line $objfile
 353
 354 DIR_PREFIX=supercalifragilisticexpialidocious
 355 find_dir_prefix
 356
 357 FIRST=1
 358 while [[ $# -gt 0 ]]; do
 359         func_addr=$1
 360         shift
 361
 362         # print any matches found
 363         DONE=0
 364         __faddr2line $objfile $func_addr $DIR_PREFIX 0
 365
 366         # if no match was found, print warnings
 367         if [[ $DONE = 0 ]]; then
 368                 __faddr2line $objfile $func_addr $DIR_PREFIX 1
 369                 warn "no match for $func_addr"
 370         fi
 371 done