scripts/decode_stacktrace.sh: support debuginfod

Now that stacktraces contain the build ID information we can update this
script to use debuginfod-find to locate the debuginfo for the vmlinux and
modules automatically.  This can replace the existing code that requires
specifying a path to vmlinux or tries to find the vmlinux and modules
automatically by using the release number.  Work it into the script as a
fallback option if the vmlinux isn't specified on the commandline.

Link: https://lkml.kernel.org/r/20210511003845.2429846-9-swboyd@chromium.org
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Evan Green <evgreen@chromium.org>
Cc: Hsin-Yi Wang <hsinyi@chromium.org>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/decode_stacktrace.sh

@@ -3,11 +3,10 @@
 # (c) 2014, Sasha Levin <sasha.levin@oracle.com>
 #set -x
 
-if [[ $# < 1 ]]; then
+usage() {
 	echo "Usage:"
 	echo "	$0 -r <release> | <vmlinux> [base path] [modules path]"
-	exit 1
-fi
+}
 
 if [[ $1 == "-r" ]] ; then
 	vmlinux=""
@@ -24,6 +23,7 @@ if [[ $1 == "-r" ]] ; then
 
 	if [[ $vmlinux == "" ]] ; then
 		echo "ERROR! vmlinux image for release $release is not found" >&2
+		usage
 		exit 2
 	fi
 else
@@ -31,12 +31,35 @@ else
 	basepath=${2-auto}
 	modpath=$3
 	release=""
+	debuginfod=
+
+	# Can we use debuginfod-find?
+	if type debuginfod-find >/dev/null 2>&1 ; then
+		debuginfod=${1-only}
+	fi
+
+	if [[ $vmlinux == "" && -z $debuginfod ]] ; then
+		echo "ERROR! vmlinux image must be specified" >&2
+		usage
+		exit 1
+	fi
 fi
 
 declare -A cache
 declare -A modcache
 
 find_module() {
+	if [[ -n $debuginfod ]] ; then
+		if [[ -n $modbuildid ]] ; then
+			debuginfod-find debuginfo $modbuildid && return
+		fi
+
+		# Only using debuginfod so don't try to find vmlinux module path
+		if [[ $debuginfod == "only" ]] ; then
+			return
+		fi
+	fi
+
 	if [[ "$modpath" != "" ]] ; then
 		for fn in $(find "$modpath" -name "${module//_/[-_]}.ko*") ; do
 			if readelf -WS "$fn" | grep -qwF .debug_line ; then
@@ -150,6 +173,27 @@ parse_symbol() {
 	symbol="$segment$name ($code)"
 }
 
+debuginfod_get_vmlinux() {
+	local vmlinux_buildid=${1##* }
+
+	if [[ $vmlinux != "" ]]; then
+		return
+	fi
+
+	if [[ $vmlinux_buildid =~ ^[0-9a-f]+ ]]; then
+		vmlinux=$(debuginfod-find debuginfo $vmlinux_buildid)
+		if [[ $? -ne 0 ]] ; then
+			echo "ERROR! vmlinux image not found via debuginfod-find" >&2
+			usage
+			exit 2
+		fi
+		return
+	fi
+	echo "ERROR! Build ID for vmlinux not found. Try passing -r or specifying vmlinux" >&2
+	usage
+	exit 2
+}
+
 decode_code() {
 	local scripts=`dirname "${BASH_SOURCE[0]}"`
 
@@ -157,6 +201,14 @@ decode_code() {
 }
 
 handle_line() {
+	if [[ $basepath == "auto" && $vmlinux != "" ]] ; then
+		module=""
+		symbol="kernel_init+0x0/0x0"
+		parse_symbol
+		basepath=${symbol#kernel_init (}
+		basepath=${basepath%/init/main.c:*)}
+	fi
+
 	local words
 
 	# Tokenize
@@ -182,16 +234,28 @@ handle_line() {
 		fi
 	done
 
+	if [[ ${words[$last]} =~ ^[0-9a-f]+\] ]]; then
+		words[$last-1]="${words[$last-1]} ${words[$last]}"
+		unset words[$last]
+		last=$(( $last - 1 ))
+	fi
+
 	if [[ ${words[$last]} =~ \[([^]]+)\] ]]; then
 		module=${words[$last]}
 		module=${module#\[}
 		module=${module%\]}
+		modbuildid=${module#* }
+		module=${module% *}
+		if [[ $modbuildid == $module ]]; then
+			modbuildid=
+		fi
 		symbol=${words[$last-1]}
 		unset words[$last-1]
 	else
 		# The symbol is the last element, process it
 		symbol=${words[$last]}
 		module=
+		modbuildid=
 	fi
 
 	unset words[$last]
@@ -201,14 +265,6 @@ handle_line() {
 	echo "${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 =~ \[\<([^]]+)\>\] ]] ||
@@ -218,6 +274,9 @@ while read line; do
 	# Is it a code line?
 	elif [[ $line == *Code:* ]]; then
 		decode_code "$line"
+	# Is it a version line?
+	elif [[ -n $debuginfod && $line =~ PID:\ [0-9]+\ Comm: ]]; then
+		debuginfod_get_vmlinux "$line"
 	else
 		# Nothing special in this line, show it as is
 		echo "$line"