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

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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 be8ecc57f1 ("perf srcline: Use long-running addr2line per
DSO")
[1] Link:
https://eighty-twenty.org/2021/09/09/perf-addr2line-speed-improvement

Signed-off-by: Brian Johannesmeyer <bjohannesmeyer@gmail.com>
Link: https://lore.kernel.org/r/20240415145538.1938745-6-bjohannesmeyer@gmail.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
This commit is contained in:
Brian Johannesmeyer 2024-04-15 16:55:36 +02:00 committed by Josh Poimboeuf
parent 5b280de46d
commit e36b69e918
1 changed files with 45 additions and 7 deletions
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52
scripts/faddr2line
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@ -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