From 431151b64af6c8ebec85ee1db3597b56a613f526 Mon Sep 17 00:00:00 2001
From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Date: Thu, 6 Aug 2020 23:17:41 -0700
Subject: scripts/decode_stacktrace.sh: guess path to modules

Try to find module in directory with vmlinux (for fresh build).  Then try
standard paths where debuginfo are usually placed.  Pick first file which
have elf section '.debug_line'.

Before:

$ echo 'tap_open+0x0/0x0 [tap]' |
  ./scripts/decode_stacktrace.sh /usr/lib/debug/boot/vmlinux-5.4.0-37-generic
WARNING! Modules path isn't set, but is needed to parse this symbol
tap_open+0x0/0x0 tap

After:

$ echo 'tap_open+0x0/0x0 [tap]' |
  ./scripts/decode_stacktrace.sh /usr/lib/debug/boot/vmlinux-5.4.0-37-generic
tap_open (drivers/net/tap.c:502) tap

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Sasha Levin <sashal@kernel.org>
Link: http://lkml.kernel.org/r/159282923068.248444.5461337458421616083.stgit@buzz
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 scripts/decode_stacktrace.sh | 36 +++++++++++++++++++++++++++++++++---
 1 file changed, 33 insertions(+), 3 deletions(-)

(limited to 'scripts/decode_stacktrace.sh')

diff --git a/scripts/decode_stacktrace.sh b/scripts/decode_stacktrace.sh
index 62a70ede7f3e..e31e253fe5bd 100755
--- a/scripts/decode_stacktrace.sh
+++ b/scripts/decode_stacktrace.sh
@@ -12,9 +12,40 @@ fi
 vmlinux=$1
 basepath=${2-auto}
 modpath=$3
+release=""
+
 declare -A cache
 declare -A modcache
 
+find_module() {
+	if [[ "$modpath" != "" ]] ; then
+		for fn in $(find "$modpath" -name "${module//_/[-_]}.ko*") ; do
+			if readelf -WS "$fn" | grep -qwF .debug_line ; then
+				echo $fn
+				return
+			fi
+		done
+		return 1
+	fi
+
+	modpath=$(dirname "$vmlinux")
+	find_module && return
+
+	if [[ $release == "" ]] ; then
+		release=$(gdb -ex 'print init_uts_ns.name.release' -ex 'quit' -quiet -batch "$vmlinux" | sed -n 's/\$1 = "\(.*\)".*/\1/p')
+	fi
+
+	for dn in {/usr/lib/debug,}/lib/modules/$release ; do
+		if [ -e "$dn" ] ; then
+			modpath="$dn"
+			find_module && return
+		fi
+	done
+
+	modpath=""
+	return 1
+}
+
 parse_symbol() {
 	# The structure of symbol at this point is:
 	#   ([name]+[offset]/[total length])
@@ -27,12 +58,11 @@ parse_symbol() {
 	elif [[ "${modcache[$module]+isset}" == "isset" ]]; then
 		local objfile=${modcache[$module]}
 	else
-		if [[ $modpath == "" ]]; then
+		local objfile=$(find_module)
+		if [[ $objfile == "" ]] ; then
 			echo "WARNING! Modules path isn't set, but is needed to parse this symbol" >&2
 			return
 		fi
-		local objfile=$(find "$modpath" -name "${module//_/[-_]}.ko*" -print -quit)
-		[[ $objfile == "" ]] && return
 		modcache[$module]=$objfile
 	fi
 
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