linux-kernel - [PATCH] selftests: livepatch: test if ftrace can trace a livepatched function

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Message-Id: <20250102-ftrace-selftest-livepatch-v1-1-84880baefc1b@gmail.com>
Date: Thu, 02 Jan 2025 15:42:10 -0300
From: Filipe Xavier <felipeaggger@...il.com>
To: Marcos Paulo de Souza <mpdesouza@...e.com>, 
 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>
Cc: live-patching@...r.kernel.org, linux-kselftest@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Felipe Xavier <felipe_life@...e.com>, 
 Filipe Xavier <felipeaggger@...il.com>
Subject: [PATCH] selftests: livepatch: test if ftrace can trace a
 livepatched function

This new test makes sure that ftrace can trace a
function that was introduced by a livepatch.

Signed-off-by: Filipe Xavier <felipeaggger@...il.com>
---
 tools/testing/selftests/livepatch/test-ftrace.sh | 37 ++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/tools/testing/selftests/livepatch/test-ftrace.sh b/tools/testing/selftests/livepatch/test-ftrace.sh
index fe14f248913acbec46fb6c0fec38a2fc84209d39..5f0d5308c88669e84210393ce7b8aa138b694ebd 100755
--- a/tools/testing/selftests/livepatch/test-ftrace.sh
+++ b/tools/testing/selftests/livepatch/test-ftrace.sh
@@ -61,4 +61,41 @@ livepatch: '$MOD_LIVEPATCH': unpatching complete
 % rmmod $MOD_LIVEPATCH"
 
 
+# - verify livepatch can load
+# - check traces if have a patched function
+# - unload livepatch and reset trace
+
+start_test "livepatch trace patched function and check that the live patch remains in effect"
+
+TRACE_FILE="$SYSFS_DEBUG_DIR/tracing/trace"
+FUNCTION_NAME="livepatch_cmdline_proc_show"
+
+load_lp $MOD_LIVEPATCH
+
+echo $FUNCTION_NAME > $SYSFS_DEBUG_DIR/tracing/set_ftrace_filter
+echo "function" > $SYSFS_DEBUG_DIR/tracing/current_tracer
+echo "" > $TRACE_FILE
+
+if [[ "$(cat /proc/cmdline)" != "$MOD_LIVEPATCH: this has been live patched" ]] ; then
+	echo -e "FAIL\n\n"
+	die "livepatch kselftest(s) failed"
+fi
+
+grep -q $FUNCTION_NAME $TRACE_FILE
+FOUND=$?
+
+disable_lp $MOD_LIVEPATCH
+unload_lp $MOD_LIVEPATCH
+
+# Reset tracing
+echo "nop" > $SYSFS_DEBUG_DIR/tracing/current_tracer
+echo "" > $SYSFS_DEBUG_DIR/tracing/set_ftrace_filter
+echo "" > $TRACE_FILE
+
+if [ "$FOUND" -eq 1 ]; then
+	echo -e "FAIL\n\n"
+	die "livepatch kselftest(s) failed"
+fi
+
+
 exit 0

---
base-commit: fc033cf25e612e840e545f8d5ad2edd6ba613ed5
change-id: 20250101-ftrace-selftest-livepatch-161fb77dbed8

Best regards,
-- 
Filipe Xavier <felipeaggger@...il.com>