scripts/faddr2line: Check vmlinux only once

Rather than checking whether the object file is vmlinux for each invocation
of __faddr2line, check it only once beforehand.

Signed-off-by: Brian Johannesmeyer <bjohannesmeyer@gmail.com>
Link: https://lore.kernel.org/r/20240415145538.1938745-4-bjohannesmeyer@gmail.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

Author: bjohannesmeyer

scripts/faddr2line

@@ -115,6 +115,17 @@ run_readelf() {
 	ELF_SYMS=$(echo "${out}" | sed -n '/Symbol table .* contains [0-9]* entries:/,$p')
 }
 
+check_vmlinux() {
+	# vmlinux uses absolute addresses in the section table rather than
+	# section offsets.
+	IS_VMLINUX=0
+	local file_type=$(echo "${ELF_FILEHEADER}" |
+		${AWK} '$1 == "Type:" { print $2; exit }')
+	if [[ $file_type = "EXEC" ]] || [[ $file_type == "DYN" ]]; then
+		IS_VMLINUX=1
+	fi
+}
+
 __faddr2line() {
 	local objfile=$1
 	local func_addr=$2
@@ -125,8 +136,6 @@ __faddr2line() {
 	local func_offset=${func_addr#*+}
 	func_offset=${func_offset%/*}
 	local user_size=
-	local file_type
-	local is_vmlinux=0
 	[[ $func_addr =~ "/" ]] && user_size=${func_addr#*/}
 
 	if [[ -z $sym_name ]] || [[ -z $func_offset ]] || [[ $sym_name = $func_addr ]]; then
@@ -135,14 +144,6 @@ __faddr2line() {
 		return
 	fi
 
-	# vmlinux uses absolute addresses in the section table rather than
-	# section offsets.
-	local file_type=$(echo "${ELF_FILEHEADER}" |
-		${AWK} '$1 == "Type:" { print $2; exit }')
-	if [[ $file_type = "EXEC" ]] || [[ $file_type == "DYN" ]]; then
-		is_vmlinux=1
-	fi
-
 	# Go through each of the object's symbols which match the func name.
 	# In rare cases there might be duplicates, in which case we print all
 	# matches.
@@ -260,7 +261,7 @@ __faddr2line() {
 		# Pass section address to addr2line and strip absolute paths
 		# from the output:
 		local args="--functions --pretty-print --inlines --exe=$objfile"
-		[[ $is_vmlinux = 0 ]] && args="$args --section=$sec_name"
+		[[ $IS_VMLINUX = 0 ]] && args="$args --section=$sec_name"
 		local output=$(${ADDR2LINE} $args $addr | sed "s; $dir_prefix\(\./\)*; ;")
 		[[ -z $output ]] && continue
 
@@ -305,6 +306,8 @@ run_readelf $objfile
 
 echo "${ELF_SECHEADERS}" | ${GREP} -q '\.debug_info' || die "CONFIG_DEBUG_INFO not enabled"
 
+check_vmlinux
+
 DIR_PREFIX=supercalifragilisticexpialidocious
 find_dir_prefix $objfile