linux-kernel - [PATCH PATCH 1/2] selftests: livepatch: add new ftrace helpers functions

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Message-Id: <20250306-ftrace-sftest-livepatch-v1-1-a6f1dfc30e17@gmail.com>
Date: Thu, 06 Mar 2025 18:51:42 -0300
From: Filipe Xavier <felipeaggger@...il.com>
To: Josh Poimboeuf <jpoimboe@...nel.org>, Jiri Kosina <jikos@...nel.org>, 
 Miroslav Benes <mbenes@...e.cz>, Petr Mladek <pmladek@...e.com>, 
 Joe Lawrence <joe.lawrence@...hat.com>, Shuah Khan <shuah@...nel.org>, 
 Marcos Paulo de Souza <mpdesouza@...e.com>
Cc: live-patching@...r.kernel.org, linux-kselftest@...r.kernel.org, 
 linux-kernel@...r.kernel.org, felipe_life@...e.com, 
 Filipe Xavier <felipeaggger@...il.com>
Subject: [PATCH PATCH 1/2] selftests: livepatch: add new ftrace helpers
 functions

Add new ftrace helpers functions cleanup_tracing, trace_function and
check_traced_function.

Signed-off-by: Filipe Xavier <felipeaggger@...il.com>
---
 tools/testing/selftests/livepatch/functions.sh | 45 ++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/tools/testing/selftests/livepatch/functions.sh b/tools/testing/selftests/livepatch/functions.sh
index 15601402dee6567837c2c49ba342eb357e410d18..512ab3a9c20cc5691bbf0863d837ffa0d40a15e9 100644
--- a/tools/testing/selftests/livepatch/functions.sh
+++ b/tools/testing/selftests/livepatch/functions.sh
@@ -10,6 +10,7 @@ SYSFS_KERNEL_DIR="/sys/kernel"
 SYSFS_KLP_DIR="$SYSFS_KERNEL_DIR/livepatch"
 SYSFS_DEBUG_DIR="$SYSFS_KERNEL_DIR/debug"
 SYSFS_KPROBES_DIR="$SYSFS_DEBUG_DIR/kprobes"
+SYSFS_TRACING_DIR="$SYSFS_DEBUG_DIR/tracing"
 
 # Kselftest framework requirement - SKIP code is 4
 ksft_skip=4
@@ -62,6 +63,9 @@ function push_config() {
 			awk -F'[: ]' '{print "file " $1 " line " $2 " " $4}')
 	FTRACE_ENABLED=$(sysctl --values kernel.ftrace_enabled)
 	KPROBE_ENABLED=$(cat "$SYSFS_KPROBES_DIR/enabled")
+	TRACING_ON=$(cat "$SYSFS_TRACING_DIR/tracing_on")
+	CURRENT_TRACER=$(cat "$SYSFS_TRACING_DIR/current_tracer")
+	FTRACE_FILTER=$(cat "$SYSFS_TRACING_DIR/set_ftrace_filter")
 }
 
 function pop_config() {
@@ -74,6 +78,17 @@ function pop_config() {
 	if [[ -n "$KPROBE_ENABLED" ]]; then
 		echo "$KPROBE_ENABLED" > "$SYSFS_KPROBES_DIR/enabled"
 	fi
+	if [[ -n "$TRACING_ON" ]]; then
+		echo "$TRACING_ON" > "$SYSFS_TRACING_DIR/tracing_on"
+	fi
+	if [[ -n "$CURRENT_TRACER" ]]; then
+		echo "$CURRENT_TRACER" > "$SYSFS_TRACING_DIR/current_tracer"
+	fi
+	if [[ -n "$FTRACE_FILTER" ]]; then
+		echo "$FTRACE_FILTER" \
+			| sed -e "/#### all functions enabled ####/d"
+			> "$SYSFS_TRACING_DIR/set_ftrace_filter"
+	fi
 }
 
 function set_dynamic_debug() {
@@ -352,3 +367,33 @@ function check_sysfs_value() {
 		die "Unexpected value in $path: $expected_value vs. $value"
 	fi
 }
+
+# cleanup_tracing() - stop and clean up function tracing
+function cleanup_tracing() {
+	echo 0 > "$SYSFS_TRACING_DIR/tracing_on"
+	echo "" > "$SYSFS_TRACING_DIR/set_ftrace_filter"
+	echo "nop" > "$SYSFS_TRACING_DIR/current_tracer"
+	echo "" > "$SYSFS_TRACING_DIR/trace"
+}
+
+# trace_function(function) - start tracing of a function
+#	function - to be traced function
+function trace_function() {
+	local function="$1"; shift
+
+	cleanup_tracing
+
+	echo "function" > "$SYSFS_TRACING_DIR/current_tracer"
+	echo "$function" > "$SYSFS_TRACING_DIR/set_ftrace_filter"
+	echo 1 > "$SYSFS_TRACING_DIR/tracing_on"
+}
+
+# check_traced_function(function) - check whether function appeared in trace log
+#	function - to be traced function
+function check_traced_function() {
+	local function="$1"; shift
+
+	if ! grep -q "$function" "$SYSFS_TRACING_DIR/trace" ; then
+		die "Function ($function) did not appear in the trace"
+	fi
+}

-- 
2.46.2