Commit e36b69e9 authored by Brian Johannesmeyer's avatar Brian Johannesmeyer Committed by Josh Poimboeuf
Browse files

scripts/faddr2line: Invoke addr2line as a single long-running process 

Rather than invoking a separate addr2line process for each address, invoke
a single addr2line coprocess, and pass each address to its stdin. Previous
work [0] applied a similar change to perf, leading to a ~60x speed-up [1].

If using an object file that is _not_ vmlinux, faddr2line passes a section
name argument to addr2line. Because we do not know until runtime which
section names will be passed to addr2line, we cannot apply this change to
non-vmlinux object files. Hence, it only applies to vmlinux.

[0] commit be8ecc57 ("perf srcline: Use long-running addr2line per
DSO")
[1] Link:
https://eighty-twenty.org/2021/09/09/perf-addr2line-speed-improvement



Signed-off-by: default avatarBrian Johannesmeyer <bjohannesmeyer@gmail.com>
Link: https://lore.kernel.org/r/20240415145538.1938745-6-bjohannesmeyer@gmail.com


Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
parent 5b280de4

scripts/faddr2line

+45 −7
Original line number Diff line number Diff line
@@ -126,6 +126,48 @@ check_vmlinux() { 
	fi

}



init_addr2line() {

	local objfile=$1



	check_vmlinux



	ADDR2LINE_ARGS="--functions --pretty-print --inlines --addresses --exe=$objfile"

	if [[ $IS_VMLINUX = 1 ]]; then

		# If the executable file is vmlinux, we don't pass section names to

		# addr2line, so we can launch it now as a single long-running process.

		coproc ADDR2LINE_PROC (${ADDR2LINE} ${ADDR2LINE_ARGS})

	fi

}



run_addr2line() {

	local addr=$1

	local sec_name=$2



	if [[ $IS_VMLINUX = 1 ]]; then

		# We send to the addr2line process: (1) the address, then (2) a sentinel

		# value, i.e., something that can't be interpreted as a valid address

		# (i.e., ","). This causes addr2line to write out: (1) the answer for

		# our address, then (2) either "?? ??:0" or "0x0...0: ..." (if

		# using binutils' addr2line), or "," (if using LLVM's addr2line).

		echo ${addr} >& "${ADDR2LINE_PROC[1]}"

		echo "," >& "${ADDR2LINE_PROC[1]}"

		local first_line

		read -r first_line <& "${ADDR2LINE_PROC[0]}"

		ADDR2LINE_OUT=$(echo "${first_line}" | sed 's/^0x[0-9a-fA-F]*: //')

		while read -r line <& "${ADDR2LINE_PROC[0]}"; do

			if [[ "$line" == "?? ??:0" ]] || [[ "$line" == "," ]] || [[ $(echo "$line" | ${GREP} "^0x00*: ") ]]; then

				break

			fi

			ADDR2LINE_OUT+=$'\n'$(echo "$line" | sed 's/^0x[0-9a-fA-F]*: //')

		done

	else

		# Run addr2line as a single invocation.

		local sec_arg

		[[ -z $sec_name ]] && sec_arg="" || sec_arg="--section=${sec_name}"

		ADDR2LINE_OUT=$(${ADDR2LINE} ${ADDR2LINE_ARGS} ${sec_arg} ${addr} | sed 's/^0x[0-9a-fA-F]*: //')

	fi

}



__faddr2line() {

	local objfile=$1

	local func_addr=$2
@@ -260,12 +302,8 @@ __faddr2line() { 


		# Pass section address to addr2line and strip absolute paths

		# from the output:

		local args="--functions --pretty-print --inlines --addresses --exe=$objfile"

		[[ $IS_VMLINUX = 0 ]] && args="$args --section=$sec_name"

		local output_with_addr=$(${ADDR2LINE} $args $addr | sed "s; $dir_prefix\(\./\)*; ;")

		[[ -z $output_with_addr ]] && continue



		local output=$(echo "${output_with_addr}" | sed 's/^0x[0-9a-fA-F]*: //')

		run_addr2line $addr $sec_name

		local output=$(echo "${ADDR2LINE_OUT}" | sed "s; $dir_prefix\(\./\)*; ;")

		[[ -z $output ]] && continue



		# Default output (non --list):
@@ -309,7 +347,7 @@ run_readelf $objfile 


echo "${ELF_SECHEADERS}" | ${GREP} -q '\.debug_info' || die "CONFIG_DEBUG_INFO not enabled"



check_vmlinux

init_addr2line $objfile



DIR_PREFIX=supercalifragilisticexpialidocious

find_dir_prefix $objfile