scripts/decode_stacktrace.sh: support old bash version

[ Upstream commit 3af8acf ]

Old bash version don't support associative array variables.  Avoid to use
associative array variables to avoid error.

Without this, old bash version will report error as fellowing
[   15.954042] Kernel panic - not syncing: sysrq triggered crash
[   15.955252] CPU: 1 PID: 167 Comm: sh Not tainted 5.18.0-rc1-00208-gb7d075db2fd5 #4
[   15.956472] Hardware name: Hobot J5 Virtual development board (DT)
[   15.957856] Call trace:
./scripts/decode_stacktrace.sh: line 128: ,dump_backtrace: syntax error: operand expected (error token is ",dump_backtrace")

Link: https://lkml.kernel.org/r/20220409180331.24047-1-schspa@gmail.com
Signed-off-by: Schspa Shi <schspa@gmail.com>
Cc: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stable-dep-of: efbd63983533 ("scripts/decode_stacktrace.sh: optionally use LLVM utilities")
Signed-off-by: Sasha Levin <sashal@kernel.org>

scripts/decode_stacktrace.sh

@@ -45,8 +45,13 @@ else
 	fi
 fi
 
-declare -A cache
-declare -A modcache
+declare aarray_support=true
+declare -A cache 2>/dev/null
+if [[ $? != 0 ]]; then
+	aarray_support=false
+else
+	declare -A modcache
+fi
 
 find_module() {
 	if [[ -n $debuginfod ]] ; then
@@ -97,15 +102,17 @@ parse_symbol() {
 
 	if [[ $module == "" ]] ; then
 		local objfile=$vmlinux
-	elif [[ "${modcache[$module]+isset}" == "isset" ]]; then
+	elif [[ $aarray_support == true && "${modcache[$module]+isset}" == "isset" ]]; then
 		local objfile=${modcache[$module]}
 	else
 		local objfile=$(find_module)
 		if [[ $objfile == "" ]] ; then
 			echo "WARNING! Modules path isn't set, but is needed to parse this symbol" >&2
 			return
 		fi
-		modcache[$module]=$objfile
+		if [[ $aarray_support == true ]]; then
+			modcache[$module]=$objfile
+		fi
 	fi
 
 	# Remove the englobing parenthesis
@@ -125,15 +132,17 @@ parse_symbol() {
 	# Use 'nm vmlinux' to figure out the base address of said symbol.
 	# It's actually faster to call it every time than to load it
 	# all into bash.
-	if [[ "${cache[$module,$name]+isset}" == "isset" ]]; then
+	if [[ $aarray_support == true && "${cache[$module,$name]+isset}" == "isset" ]]; then
 		local base_addr=${cache[$module,$name]}
 	else
 		local base_addr=$(nm "$objfile" 2>/dev/null | awk '$3 == "'$name'" && ($2 == "t" || $2 == "T") {print $1; exit}')
 		if [[ $base_addr == "" ]] ; then
 			# address not found
 			return
 		fi
-		cache[$module,$name]="$base_addr"
+		if [[ $aarray_support == true ]]; then
+			cache[$module,$name]="$base_addr"
+		fi
 	fi
 	# Let's start doing the math to get the exact address into the
 	# symbol. First, strip out the symbol total length.
@@ -149,11 +158,13 @@ parse_symbol() {
 
 	# Pass it to addr2line to get filename and line number
 	# Could get more than one result
-	if [[ "${cache[$module,$address]+isset}" == "isset" ]]; then
+	if [[ $aarray_support == true && "${cache[$module,$address]+isset}" == "isset" ]]; then
 		local code=${cache[$module,$address]}
 	else
 		local code=$(${CROSS_COMPILE}addr2line -i -e "$objfile" "$address" 2>/dev/null)
-		cache[$module,$address]=$code
+		if [[ $aarray_support == true ]]; then
+			cache[$module,$address]=$code
+		fi
 	fi
 
 	# addr2line doesn't return a proper error code if it fails, so