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Commit d2b1dc3a authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Greg Kroah-Hartman
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scripts/faddr2line: Fix overlapping text section failures 



[ Upstream commit 1d1a0e7c5100d332583e20b40aa8c0a8ed3d7849 ]

There have been some recent reports of faddr2line failures:

  $ scripts/faddr2line sound/soundcore.ko sound_devnode+0x5/0x35
  bad symbol size: base: 0x0000000000000000 end: 0x0000000000000000

  $ ./scripts/faddr2line vmlinux.o enter_from_user_mode+0x24
  bad symbol size: base: 0x0000000000005fe0 end: 0x0000000000005fe0

The problem is that faddr2line is based on 'nm', which has a major
limitation: it doesn't know how to distinguish between different text
sections.  So if an offset exists in multiple text sections in the
object, it may fail.

Rewrite faddr2line to be section-aware, by basing it on readelf.

Fixes: 67326666 ("scripts: add script for translating stack dump function offsets")
Reported-by: default avatarKaiwan N Billimoria <kaiwan.billimoria@gmail.com>
Reported-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/29ff99f86e3da965b6e46c1cc2d72ce6528c17c3.1652382321.git.jpoimboe@kernel.org


Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 0be5d9da

scripts/faddr2line

+97 −53
Original line number Diff line number Diff line
@@ -44,17 +44,6 @@ 
set -o errexit

set -o nounset



READELF="${CROSS_COMPILE:-}readelf"

ADDR2LINE="${CROSS_COMPILE:-}addr2line"

SIZE="${CROSS_COMPILE:-}size"

NM="${CROSS_COMPILE:-}nm"



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"

command -v ${SIZE} >/dev/null 2>&1 || die "size isn't installed"

command -v ${NM} >/dev/null 2>&1 || die "nm isn't installed"



usage() {

	echo "usage: faddr2line [--list] <object file> <func+offset> <func+offset>..." >&2

	exit 1
@@ -69,6 +58,14 @@ die() { 
	exit 1

}



READELF="${CROSS_COMPILE:-}readelf"

ADDR2LINE="${CROSS_COMPILE:-}addr2line"

AWK="awk"



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"



# 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

# init/main.c!  This only works for vmlinux.  Otherwise it falls back to
@@ -76,7 +73,7 @@ die() { 
find_dir_prefix() {

	local objfile=$1



	local start_kernel_addr=$(${READELF} -sW $objfile | awk '$8 == "start_kernel" {printf "0x%s", $2}')

	local start_kernel_addr=$(${READELF} --symbols --wide $objfile | ${AWK} '$8 == "start_kernel" {printf "0x%s", $2}')

	[[ -z $start_kernel_addr ]] && return



	local file_line=$(${ADDR2LINE} -e $objfile $start_kernel_addr)
@@ -97,86 +94,133 @@ __faddr2line() { 
	local dir_prefix=$3

	local print_warnings=$4



	local func=${func_addr%+*}

	local sym_name=${func_addr%+*}

	local offset=${func_addr#*+}

	offset=${offset%/*}

	local size=

	[[ $func_addr =~ "/" ]] && size=${func_addr#*/}

	local user_size=

	[[ $func_addr =~ "/" ]] && user_size=${func_addr#*/}



	if [[ -z $func ]] || [[ -z $offset ]] || [[ $func = $func_addr ]]; then

	if [[ -z $sym_name ]] || [[ -z $offset ]] || [[ $sym_name = $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))

	# In rare cases there might be duplicates, in which case we print all

	# matches.

	while read line; do

		local fields=($line)

		local sym_addr=0x${fields[1]}

		local sym_elf_size=${fields[2]}

		local sym_sec=${fields[6]}



		# Get the section size:

		local sec_size=$(${READELF} --section-headers --wide $objfile |

			sed 's/\[ /\[/' |

			${AWK} -v sec=$sym_sec '$1 == "[" sec "]" { print "0x" $6; exit }')



		if [[ -z $sec_size ]]; then

			warn "bad section size: section: $sym_sec"

			DONE=1

			return

		fi



		# Calculate the symbol size.

		#

		# Unfortunately we can't use the ELF size, because kallsyms

		# also includes the padding bytes in its size calculation.  For

		# kallsyms, the size calculation is the distance between the

		# symbol and the next symbol in a sorted list.

		local sym_size

		local cur_sym_addr

		local found=0

		while read line; do

			local fields=($line)

			cur_sym_addr=0x${fields[1]}

			local cur_sym_elf_size=${fields[2]}

			local cur_sym_name=${fields[7]:-}



			if [[ $cur_sym_addr = $sym_addr ]] &&

			   [[ $cur_sym_elf_size = $sym_elf_size ]] &&

			   [[ $cur_sym_name = $sym_name ]]; then

				found=1

				continue

			fi



			if [[ $found = 1 ]]; then

				sym_size=$(($cur_sym_addr - $sym_addr))

				[[ $sym_size -lt $sym_elf_size ]] && continue;

				found=2

				break

			fi

		done < <(${READELF} --symbols --wide $objfile | ${AWK} -v sec=$sym_sec '$7 == sec' | sort --key=2)



		if [[ $found = 0 ]]; then

			warn "can't find symbol: sym_name: $sym_name sym_sec: $sym_sec sym_addr: $sym_addr sym_elf_size: $sym_elf_size"

			DONE=1

			return

		fi



		# If nothing was found after the symbol, assume it's the last

		# symbol in the section.

		[[ $found = 1 ]] && sym_size=$(($sec_size - $sym_addr))



		if [[ -z $sym_size ]] || [[ $sym_size -le 0 ]]; then

			warn "bad symbol size: base: $sym_base end: $sym_end"

			warn "bad symbol size: sym_addr: $sym_addr cur_sym_addr: $cur_sym_addr"

			DONE=1

			return

		fi



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



		# calculate the address

		local addr=$(($sym_base + $offset))

		# Calculate the section address from user-supplied offset:

		local addr=$(($sym_addr + $offset))

		if [[ -z $addr ]] || [[ $addr = 0 ]]; then

			warn "bad address: $sym_base + $offset"

			warn "bad address: $sym_addr + $offset"

			DONE=1

			return

		fi

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



		# weed out non-function symbols

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

		# If the user provided a size, make sure it matches the symbol's size:

		if [[ -n $user_size ]] && [[ $user_size -ne $sym_size ]]; 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)"

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

			continue;

		fi



		# make sure the provided offset is within the symbol's range

		# 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)"

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

			continue

		fi



		# separate multiple entries with a blank line

		# In case of duplicates or multiple addresses specified on the

		# cmdline, separate multiple entries with a blank line:

		[[ $FIRST = 0 ]] && echo

		FIRST=0



		# pass real address to addr2line

		echo "$func+$offset/$sym_size:"

		local file_lines=$(${ADDR2LINE} -fpie $objfile $addr | sed "s; $dir_prefix\(\./\)*; ;")

		[[ -z $file_lines ]] && return

		echo "$sym_name+$offset/$sym_size:"



		# Pass section address to addr2line and strip absolute paths

		# from the output:

		local output=$(${ADDR2LINE} -fpie $objfile $addr | sed "s; $dir_prefix\(\./\)*; ;")

		[[ -z $output ]] && continue



		# Default output (non --list):

		if [[ $LIST = 0 ]]; then

			echo "$file_lines" | while read -r line

			echo "$output" | while read -r line

			do

				echo $line

			done

			DONE=1;

			return

			continue

		fi



		# show each line with context

		echo "$file_lines" | while read -r line

		# For --list, show each line with its corresponding source code:

		echo "$output" | while read -r line

		do

			echo

			echo $line
@@ -184,12 +228,12 @@ __faddr2line() { 
			n1=$[$n-5]

			n2=$[$n+5]

			f=$(echo $line | sed 's/.*at \(.\+\):.*/\1/g')

			awk 'NR>=strtonum("'$n1'") && NR<=strtonum("'$n2'") { if (NR=='$n') printf(">%d<", NR); else printf(" %d ", NR); printf("\t%s\n", $0)}' $f

			${AWK} 'NR>=strtonum("'$n1'") && NR<=strtonum("'$n2'") { if (NR=='$n') printf(">%d<", NR); else printf(" %d ", NR); printf("\t%s\n", $0)}' $f

		done



		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; }')

	done < <(${READELF} --symbols --wide $objfile | ${AWK} -v fn=$sym_name '$4 == "FUNC" && $8 == fn')

}



[[ $# -lt 2 ]] && usage