selftests: livepatch: test-ftrace: livepatch a traced function

This is basically the inverse case of commit 474eecc
("selftests: livepatch: test if ftrace can trace a livepatched function")
but ensuring that livepatch would work on a traced function.

Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Tested-by: Petr Mladek <pmladek@suse.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Link: https://patch.msgid.link/20260220-lp-test-trace-v1-1-4b6703cd01a6@suse.com
[pmladek: Fixed a typo found by Joe.]
Signed-off-by: Petr Mladek <pmladek@suse.com>

Author: marcosps

tools/testing/selftests/livepatch/test-ftrace.sh

@@ -95,4 +95,40 @@ livepatch: '$MOD_LIVEPATCH': completing unpatching transition
 livepatch: '$MOD_LIVEPATCH': unpatching complete
 % rmmod $MOD_LIVEPATCH"
 
+
+# - trace a function
+# - verify livepatch can load targgeting on the same traced function
+# - check if the livepatch is in effect
+# - reset trace and unload livepatch
+
+start_test "livepatch a traced function and check that the live patch remains in effect"
+
+FUNCTION_NAME="cmdline_proc_show"
+
+trace_function "$FUNCTION_NAME"
+load_lp $MOD_LIVEPATCH
+
+if [[ "$(cat /proc/cmdline)" == "$MOD_LIVEPATCH: this has been live patched" ]] ; then
+	log "livepatch: ok"
+fi
+
+check_traced_functions "$FUNCTION_NAME"
+
+disable_lp $MOD_LIVEPATCH
+unload_lp $MOD_LIVEPATCH
+
+check_result "% insmod test_modules/$MOD_LIVEPATCH.ko
+livepatch: enabling patch '$MOD_LIVEPATCH'
+livepatch: '$MOD_LIVEPATCH': initializing patching transition
+livepatch: '$MOD_LIVEPATCH': starting patching transition
+livepatch: '$MOD_LIVEPATCH': completing patching transition
+livepatch: '$MOD_LIVEPATCH': patching complete
+livepatch: ok
+% echo 0 > $SYSFS_KLP_DIR/$MOD_LIVEPATCH/enabled
+livepatch: '$MOD_LIVEPATCH': initializing unpatching transition
+livepatch: '$MOD_LIVEPATCH': starting unpatching transition
+livepatch: '$MOD_LIVEPATCH': completing unpatching transition
+livepatch: '$MOD_LIVEPATCH': unpatching complete
+% rmmod $MOD_LIVEPATCH"
+
 exit 0