[PATCH] scripts/decode_stacktrace.sh: better support to ARM32 module stack trace

[xndcn]

Since System.map is generated by cross-compile nm tool, we should use it
here too. Otherwise host nm may not recognize thumb2 function address well.

Beside, sometimes special characters around module name, such as ARM32
with BACKTRACE_VERBOSE in "(%pS)" format, such as:
[<806e4845>] (dump_stack_lvl) from [<7f806013>] (hello_init+0x13/0x1000 [test])

After stripping other characters around "[module]", it can be finally decoded:
(dump_stack_lvl) from hello_init (/foo/test.c:10) test

Signed-off-by: xndcn <xndchn@xxxxxxxxx>
---
 scripts/decode_stacktrace.sh | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/scripts/decode_stacktrace.sh b/scripts/decode_stacktrace.sh
index fa5be6f57b0..324e4a6c260 100755
--- a/scripts/decode_stacktrace.sh
+++ b/scripts/decode_stacktrace.sh
@@ -30,6 +30,7 @@ fi
 
 READELF=${UTIL_PREFIX}readelf${UTIL_SUFFIX}
 ADDR2LINE=${UTIL_PREFIX}addr2line${UTIL_SUFFIX}
+NM=${UTIL_PREFIX}nm${UTIL_SUFFIX}
 
 if [[ $1 == "-r" ]] ; then
 	vmlinux=""
@@ -158,7 +159,7 @@ parse_symbol() {
 	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 $1; exit}')
+		local base_addr=$(${NM} "$objfile" 2>/dev/null | awk '$3 == "'$name'" && ($2 == "t" || $2 == "T") {print $1; exit}')
 		if [[ $base_addr == "" ]] ; then
 			# address not found
 			return
@@ -282,8 +283,8 @@ handle_line() {
 
 	if [[ ${words[$last]} =~ \[([^]]+)\] ]]; then
 		module=${words[$last]}
-		module=${module#\[}
-		module=${module%\]}
+		module=${module#*\[}
+		module=${module%\]*}
 		modbuildid=${module#* }
 		module=${module% *}
 		if [[ $modbuildid == $module ]]; then
-- 
2.25.1