#!/bin/bash
  #
  # Translate stack dump function offsets.
  #
  # addr2line doesn't work with KASLR addresses.  This works similarly to
  # addr2line, but instead takes the 'func+0x123' format as input:
  #
  #   $ ./scripts/faddr2line ~/k/vmlinux meminfo_proc_show+0x5/0x568
  #   meminfo_proc_show+0x5/0x568:
  #   meminfo_proc_show at fs/proc/meminfo.c:27
  #
  # If the address is part of an inlined function, the full inline call chain is
  # printed:
  #
  #   $ ./scripts/faddr2line ~/k/vmlinux native_write_msr+0x6/0x27
  #   native_write_msr+0x6/0x27:
  #   arch_static_branch at arch/x86/include/asm/msr.h:121
  #    (inlined by) static_key_false at include/linux/jump_label.h:125
  #    (inlined by) native_write_msr at arch/x86/include/asm/msr.h:125
  #
  # The function size after the '/' in the input is optional, but recommended.
  # It's used to help disambiguate any duplicate symbol names, which can occur
  # rarely.  If the size is omitted for a duplicate symbol then it's possible for
  # multiple code sites to be printed:
  #
  #   $ ./scripts/faddr2line ~/k/vmlinux raw_ioctl+0x5
  #   raw_ioctl+0x5/0x20:
  #   raw_ioctl at drivers/char/raw.c:122
  #
  #   raw_ioctl+0x5/0xb1:
  #   raw_ioctl at net/ipv4/raw.c:876
  #
  # Multiple addresses can be specified on a single command line:
  #
  #   $ ./scripts/faddr2line ~/k/vmlinux type_show+0x10/45 free_reserved_area+0x90
  #   type_show+0x10/0x2d:
  #   type_show at drivers/video/backlight/backlight.c:213
  #
  #   free_reserved_area+0x90/0x123:
  #   free_reserved_area at mm/page_alloc.c:6429 (discriminator 2)
  
  
  set -o errexit
  set -o nounset
  
  command -v awk >/dev/null 2>&1 || die "awk isn't installed"
  command -v readelf >/dev/null 2>&1 || die "readelf isn't installed"
  command -v addr2line >/dev/null 2>&1 || die "addr2line isn't installed"
  
  usage() {
  	echo "usage: faddr2line <object file> <func+offset> <func+offset>..." >&2
  	exit 1
  }
  
  warn() {
  	echo "$1" >&2
  }
  
  die() {
  	echo "ERROR: $1" >&2
  	exit 1
  }
  
  # Try to figure out the source directory prefix so we can remove it from the
  # addr2line output.  HACK ALERT: This assumes that start_kernel() is in
  # kernel/init.c!  This only works for vmlinux.  Otherwise it falls back to
  # printing the absolute path.
  find_dir_prefix() {
  	local objfile=$1
  
  	local start_kernel_addr=$(readelf -sW $objfile | awk '$8 == "start_kernel" {printf "0x%s", $2}')
  	[[ -z $start_kernel_addr ]] && return
  
  	local file_line=$(addr2line -e $objfile $start_kernel_addr)
  	[[ -z $file_line ]] && return
  
  	local prefix=${file_line%init/main.c:*}
  	if [[ -z $prefix ]] || [[ $prefix = $file_line ]]; then
  		return
  	fi
  
  	DIR_PREFIX=$prefix
  	return 0
  }
  
  __faddr2line() {
  	local objfile=$1
  	local func_addr=$2
  	local dir_prefix=$3
  	local print_warnings=$4
  
  	local func=${func_addr%+*}
  	local offset=${func_addr#*+}
  	offset=${offset%/*}
  	local size=
  	[[ $func_addr =~ "/" ]] && size=${func_addr#*/}
  
  	if [[ -z $func ]] || [[ -z $offset ]] || [[ $func = $func_addr ]]; then
  		warn "bad func+offset $func_addr"
  		DONE=1
  		return
  	fi
  
  	# Go through each of the object's symbols which match the func name.
  	# In rare cases there might be duplicates.

  	file_end=$(size -Ax $objfile | awk '$1 == ".text" {print $2}')

  	while read symbol; do
  		local fields=($symbol)

  		local sym_base=0x${fields[0]}
  		local sym_type=${fields[1]}

  		local sym_end=${fields[3]}

  
  		# calculate the size
  		local sym_size=$(($sym_end - $sym_base))
  		if [[ -z $sym_size ]] || [[ $sym_size -le 0 ]]; then
  			warn "bad symbol size: base: $sym_base end: $sym_end"
  			DONE=1
  			return
  		fi
  		sym_size=0x$(printf %x $sym_size)

  
  		# calculate the address
  		local addr=$(($sym_base + $offset))
  		if [[ -z $addr ]] || [[ $addr = 0 ]]; then
  			warn "bad address: $sym_base + $offset"
  			DONE=1
  			return
  		fi

  		addr=0x$(printf %x $addr)

  
  		# weed out non-function symbols

  		if [[ $sym_type != t ]] && [[ $sym_type != T ]]; then

  			[[ $print_warnings = 1 ]] &&

  				echo "skipping $func address at $addr due to non-function symbol of type '$sym_type'"

  			continue
  		fi
  
  		# if the user provided a size, make sure it matches the symbol's size
  		if [[ -n $size ]] && [[ $size -ne $sym_size ]]; then
  			[[ $print_warnings = 1 ]] &&

  				echo "skipping $func address at $addr due to size mismatch ($size != $sym_size)"

  			continue;
  		fi
  
  		# make sure the provided offset is within the symbol's range
  		if [[ $offset -gt $sym_size ]]; then
  			[[ $print_warnings = 1 ]] &&

  				echo "skipping $func address at $addr due to size mismatch ($offset > $sym_size)"

  			continue
  		fi
  
  		# separate multiple entries with a blank line
  		[[ $FIRST = 0 ]] && echo
  		FIRST=0

  		# pass real address to addr2line
  		echo "$func+$offset/$sym_size:"
  		addr2line -fpie $objfile $addr | sed "s; $dir_prefix\(\./\)*; ;"

  		DONE=1

  	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; }')

  }
  
  [[ $# -lt 2 ]] && usage
  
  objfile=$1
  [[ ! -f $objfile ]] && die "can't find objfile $objfile"
  shift
  
  DIR_PREFIX=supercalifragilisticexpialidocious
  find_dir_prefix $objfile
  
  FIRST=1
  while [[ $# -gt 0 ]]; do
  	func_addr=$1
  	shift
  
  	# print any matches found
  	DONE=0
  	__faddr2line $objfile $func_addr $DIR_PREFIX 0
  
  	# if no match was found, print warnings
  	if [[ $DONE = 0 ]]; then
  		__faddr2line $objfile $func_addr $DIR_PREFIX 1
  		warn "no match for $func_addr"
  	fi
  done