linux/scripts/faddr2line
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   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
  44set -o errexit
  45set -o nounset
  46
  47READELF="${CROSS_COMPILE:-}readelf"
  48ADDR2LINE="${CROSS_COMPILE:-}addr2line"
  49SIZE="${CROSS_COMPILE:-}size"
  50NM="${CROSS_COMPILE:-}nm"
  51
  52command -v awk >/dev/null 2>&1 || die "awk isn't installed"
  53command -v ${READELF} >/dev/null 2>&1 || die "readelf isn't installed"
  54command -v ${ADDR2LINE} >/dev/null 2>&1 || die "addr2line isn't installed"
  55command -v ${SIZE} >/dev/null 2>&1 || die "size isn't installed"
  56command -v ${NM} >/dev/null 2>&1 || die "nm isn't installed"
  57
  58usage() {
  59        echo "usage: faddr2line [--list] <object file> <func+offset> <func+offset>..." >&2
  60        exit 1
  61}
  62
  63warn() {
  64        echo "$1" >&2
  65}
  66
  67die() {
  68        echo "ERROR: $1" >&2
  69        exit 1
  70}
  71
  72# Try to figure out the source directory prefix so we can remove it from the
  73# addr2line output.  HACK ALERT: This assumes that start_kernel() is in
  74# kernel/init.c!  This only works for vmlinux.  Otherwise it falls back to
  75# printing the absolute path.
  76find_dir_prefix() {
  77        local objfile=$1
  78
  79        local start_kernel_addr=$(${READELF} -sW $objfile | awk '$8 == "start_kernel" {printf "0x%s", $2}')
  80        [[ -z $start_kernel_addr ]] && return
  81
  82        local file_line=$(${ADDR2LINE} -e $objfile $start_kernel_addr)
  83        [[ -z $file_line ]] && return
  84
  85        local prefix=${file_line%init/main.c:*}
  86        if [[ -z $prefix ]] || [[ $prefix = $file_line ]]; then
  87                return
  88        fi
  89
  90        DIR_PREFIX=$prefix
  91        return 0
  92}
  93
  94__faddr2line() {
  95        local objfile=$1
  96        local func_addr=$2
  97        local dir_prefix=$3
  98        local print_warnings=$4
  99
 100        local func=${func_addr%+*}
 101        local offset=${func_addr#*+}
 102        offset=${offset%/*}
 103        local size=
 104        [[ $func_addr =~ "/" ]] && size=${func_addr#*/}
 105
 106        if [[ -z $func ]] || [[ -z $offset ]] || [[ $func = $func_addr ]]; then
 107                warn "bad func+offset $func_addr"
 108                DONE=1
 109                return
 110        fi
 111
 112        # Go through each of the object's symbols which match the func name.
 113        # In rare cases there might be duplicates.
 114        file_end=$(${SIZE} -Ax $objfile | awk '$1 == ".text" {print $2}')
 115        while read symbol; do
 116                local fields=($symbol)
 117                local sym_base=0x${fields[0]}
 118                local sym_type=${fields[1]}
 119                local sym_end=${fields[3]}
 120
 121                # calculate the size
 122                local sym_size=$(($sym_end - $sym_base))
 123                if [[ -z $sym_size ]] || [[ $sym_size -le 0 ]]; then
 124                        warn "bad symbol size: base: $sym_base end: $sym_end"
 125                        DONE=1
 126                        return
 127                fi
 128                sym_size=0x$(printf %x $sym_size)
 129
 130                # calculate the address
 131                local addr=$(($sym_base + $offset))
 132                if [[ -z $addr ]] || [[ $addr = 0 ]]; then
 133                        warn "bad address: $sym_base + $offset"
 134                        DONE=1
 135                        return
 136                fi
 137                addr=0x$(printf %x $addr)
 138
 139                # weed out non-function symbols
 140                if [[ $sym_type != t ]] && [[ $sym_type != T ]]; then
 141                        [[ $print_warnings = 1 ]] &&
 142                                echo "skipping $func address at $addr due to non-function symbol of type '$sym_type'"
 143                        continue
 144                fi
 145
 146                # if the user provided a size, make sure it matches the symbol's size
 147                if [[ -n $size ]] && [[ $size -ne $sym_size ]]; then
 148                        [[ $print_warnings = 1 ]] &&
 149                                echo "skipping $func address at $addr due to size mismatch ($size != $sym_size)"
 150                        continue;
 151                fi
 152
 153                # make sure the provided offset is within the symbol's range
 154                if [[ $offset -gt $sym_size ]]; then
 155                        [[ $print_warnings = 1 ]] &&
 156                                echo "skipping $func address at $addr due to size mismatch ($offset > $sym_size)"
 157                        continue
 158                fi
 159
 160                # separate multiple entries with a blank line
 161                [[ $FIRST = 0 ]] && echo
 162                FIRST=0
 163
 164                # pass real address to addr2line
 165                echo "$func+$offset/$sym_size:"
 166                local file_lines=$(${ADDR2LINE} -fpie $objfile $addr | sed "s; $dir_prefix\(\./\)*; ;")
 167                [[ -z $file_lines ]] && return
 168
 169                if [[ $LIST = 0 ]]; then
 170                        echo "$file_lines" | while read -r line
 171                        do
 172                                echo $line
 173                        done
 174                        DONE=1;
 175                        return
 176                fi
 177
 178                # show each line with context
 179                echo "$file_lines" | while read -r line
 180                do
 181                        echo
 182                        echo $line
 183                        n=$(echo $line | sed 's/.*:\([0-9]\+\).*/\1/g')
 184                        n1=$[$n-5]
 185                        n2=$[$n+5]
 186                        f=$(echo $line | sed 's/.*at \(.\+\):.*/\1/g')
 187                        awk 'NR>=strtonum("'$n1'") && NR<=strtonum("'$n2'") { if (NR=='$n') printf(">%d<", NR); else printf(" %d ", NR); printf("\t%s\n", $0)}' $f
 188                done
 189
 190                DONE=1
 191
 192        done < <(${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; }')
 193}
 194
 195[[ $# -lt 2 ]] && usage
 196
 197objfile=$1
 198
 199LIST=0
 200[[ "$objfile" == "--list" ]] && LIST=1 && shift && objfile=$1
 201
 202[[ ! -f $objfile ]] && die "can't find objfile $objfile"
 203shift
 204
 205DIR_PREFIX=supercalifragilisticexpialidocious
 206find_dir_prefix $objfile
 207
 208FIRST=1
 209while [[ $# -gt 0 ]]; do
 210        func_addr=$1
 211        shift
 212
 213        # print any matches found
 214        DONE=0
 215        __faddr2line $objfile $func_addr $DIR_PREFIX 0
 216
 217        # if no match was found, print warnings
 218        if [[ $DONE = 0 ]]; then
 219                __faddr2line $objfile $func_addr $DIR_PREFIX 1
 220                warn "no match for $func_addr"
 221        fi
 222done
 223