[patch 012/163] scripts/decode_stacktrace.sh: guess path to modules

Andrew Morton
2020-08-07T06:17:44Z

From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
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

Link: http://lkml.kernel.org/r/159282923068.248444.5461337458421616083.stgit@buzz
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Sasha Levin <sashal@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

scripts/decode_stacktrace.sh | 36 ++++++++++++++++++++++++++++++---
1 file changed, 33 insertions(+), 3 deletions(-)

--- a/scripts/decode_stacktrace.sh~scripts-decode_stacktrace-guess-path-to-modules
+++ a/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

_