[PATCH 1/4] scripts/decode_stacktrace: skip missing symbols

[PATCH 1/4] scripts/decode_stacktrace: skip missing symbols

[Konstantin Khlebnikov]

For now script turns missing symbols into '0' and make bogus decode.
Skip them instead. Also simplify parsing output of 'nm'.

Before:

$ echo 'xxx+0x0/0x0' | ./scripts/decode_stacktrace.sh vmlinux ""
xxx (home/khlebnikov/src/linux/./arch/x86/include/asm/processor.h:398)

After:

$ echo 'xxx+0x0/0x0' | ./scripts/decode_stacktrace.sh vmlinux ""
xxx+0x0/0x0

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
---
 scripts/decode_stacktrace.sh |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/scripts/decode_stacktrace.sh b/scripts/decode_stacktrace.sh
index 66a6d511b524..6ec8d6dff86c 100755
--- a/scripts/decode_stacktrace.sh
+++ b/scripts/decode_stacktrace.sh
@@ -56,7 +56,11 @@ parse_symbol() {
 	if [[ "${cache[$module,$name]+isset}" == "isset" ]]; then
 		local base_addr=${cache[$module,$name]}
 	else
-		local base_addr=$(nm "$objfile" | grep -i ' t ' | awk "/ $name\$/ {print \$1}" | head -n1)
+		local base_addr=$(nm "$objfile" | awk '$3 == "'$name'" && ($2 == "t" || $2 == "T") {print $1; exit}')
+		if [[ $base_addr == "" ]] ; then
+			# address not found
+			return
+		fi
 		cache[$module,$name]="$base_addr"
 	fi
 	# Let's start doing the math to get the exact address into the

[PATCH 2/4] scripts/decode_stacktrace: guess basepath if not specified

[Konstantin Khlebnikov]

Guess path to kernel sources using known location of symbol "kernel_init".
Make basepath argument optional.

Before:

$ echo 'vfs_open+0x0/0x0' | ./scripts/decode_stacktrace.sh vmlinux ""
vfs_open (home/khlebnikov/src/linux/fs/open.c:912)

After:

$ echo 'vfs_open+0x0/0x0' | ./scripts/decode_stacktrace.sh vmlinux
vfs_open (fs/open.c:912)

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
---
 scripts/decode_stacktrace.sh |   14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/scripts/decode_stacktrace.sh b/scripts/decode_stacktrace.sh
index 6ec8d6dff86c..b1b85a7b2115 100755
--- a/scripts/decode_stacktrace.sh
+++ b/scripts/decode_stacktrace.sh
@@ -3,14 +3,14 @@
 # (c) 2014, Sasha Levin <sasha.levin@oracle.com>
 #set -x
 
-if [[ $# < 2 ]]; then
+if [[ $# < 1 ]]; then
 	echo "Usage:"
-	echo "	$0 [vmlinux] [base path] [modules path]"
+	echo "	$0 <vmlinux> [base path] [modules path]"
 	exit 1
 fi
 
 vmlinux=$1
-basepath=$2
+basepath=${2-auto}
 modpath=$3
 declare -A cache
 declare -A modcache
@@ -152,6 +152,14 @@ handle_line() {
 	echo "${words[@]}" "$symbol $module"
 }
 
+if [[ $basepath == "auto" ]] ; then
+	module=""
+	symbol="kernel_init+0x0/0x0"
+	parse_symbol
+	basepath=${symbol#kernel_init (}
+	basepath=${basepath%/init/main.c:*)}
+fi
+
 while read line; do
 	# Let's see if we have an address in the line
 	if [[ $line =~ \[\<([^]]+)\>\] ]] ||

[PATCH 3/4] scripts/decode_stacktrace: guess path to modules

[Konstantin Khlebnikov]

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

diff --git a/scripts/decode_stacktrace.sh b/scripts/decode_stacktrace.sh
index b1b85a7b2115..7f18ac10af03 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
 

[PATCH 4/4] scripts/decode_stacktrace: guess path to vmlinux by release name

[Konstantin Khlebnikov]

Add option decode_stacktrace -r <release> to specify only release name.
This is enough to guess standard paths to vmlinux and modules:

$ echo -e 'schedule+0x0/0x0\ntap_open+0x0/0x0 [tap]' |
	./scripts/decode_stacktrace.sh -r 5.4.0-37-generic
schedule (kernel/sched/core.c:4138)
tap_open (drivers/net/tap.c:502) tap

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
---
 scripts/decode_stacktrace.sh |   29 ++++++++++++++++++++++++-----
 1 file changed, 24 insertions(+), 5 deletions(-)

diff --git a/scripts/decode_stacktrace.sh b/scripts/decode_stacktrace.sh
index 7f18ac10af03..4bdcb6d8c605 100755
--- a/scripts/decode_stacktrace.sh
+++ b/scripts/decode_stacktrace.sh
@@ -5,14 +5,33 @@
 
 if [[ $# < 1 ]]; then
 	echo "Usage:"
-	echo "	$0 <vmlinux> [base path] [modules path]"
+	echo "	$0 -r <release> | <vmlinux> [base path] [modules path]"
 	exit 1
 fi
 
-vmlinux=$1
-basepath=${2-auto}
-modpath=$3
-release=""
+if [[ $1 == "-r" ]] ; then
+	vmlinux=""
+	basepath="auto"
+	modpath=""
+	release=$2
+
+	for fn in {,/usr/lib/debug}/boot/vmlinux-$release{,.debug} /lib/modules/$release{,/build}/vmlinux ; do
+		if [ -e "$fn" ] ; then
+			vmlinux=$fn
+			break
+		fi
+	done
+
+	if [[ $vmlinux == "" ]] ; then
+		echo "ERROR! vmlinux image for release $release is not found" >&2
+		exit 2
+	fi
+else
+	vmlinux=$1
+	basepath=${2-auto}
+	modpath=$3
+	release=""
+fi
 
 declare -A cache
 declare -A modcache