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>

diff --git a/scripts/decode_stacktrace.sh b/scripts/decode_stacktrace.sh
index 62a70ede7f3e8eba313c3ae7239ed267d2750542..e31e253fe5bd6ba3f9f9e0ad4d452f0845f4a9a1 100755 (executable)
--- 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