selftests/livepatch: Make dynamic debug setup and restore generic

Livepatch selftests currently save the current dynamic debug config and
tweak it for the selftests. The config is restored at the end. Make the
infrastructure generic, so that more variables can be saved and
restored.

Link: http://lkml.kernel.org/r/20191016113316.13415-3-mbenes@suse.cz

Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tools/testing/selftests/livepatch/functions.sh

@@ -29,29 +29,33 @@ function die() {
 	exit 1
 }
 
-function push_dynamic_debug() {
-        DYNAMIC_DEBUG=$(grep '^kernel/livepatch' /sys/kernel/debug/dynamic_debug/control | \
-                awk -F'[: ]' '{print "file " $1 " line " $2 " " $4}')
+function push_config() {
+	DYNAMIC_DEBUG=$(grep '^kernel/livepatch' /sys/kernel/debug/dynamic_debug/control | \
+			awk -F'[: ]' '{print "file " $1 " line " $2 " " $4}')
 }
 
-function pop_dynamic_debug() {
+function pop_config() {
 	if [[ -n "$DYNAMIC_DEBUG" ]]; then
 		echo -n "$DYNAMIC_DEBUG" > /sys/kernel/debug/dynamic_debug/control
 	fi
 }
 
-# set_dynamic_debug() - save the current dynamic debug config and tweak
-# 			it for the self-tests.  Set a script exit trap
-#			that restores the original config.
 function set_dynamic_debug() {
-        push_dynamic_debug
-        trap pop_dynamic_debug EXIT INT TERM HUP
         cat <<-EOF > /sys/kernel/debug/dynamic_debug/control
 		file kernel/livepatch/* +p
 		func klp_try_switch_task -p
 		EOF
 }
 
+# setup_config - save the current config and set a script exit trap that
+#		 restores the original config.  Setup the dynamic debug
+#		 for verbose livepatching output.
+function setup_config() {
+	push_config
+	set_dynamic_debug
+	trap pop_config EXIT INT TERM HUP
+}
+
 # loop_until(cmd) - loop a command until it is successful or $MAX_RETRIES,
 #		    sleep $RETRY_INTERVAL between attempts
 #	cmd - command and its arguments to run

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

@@ -9,7 +9,7 @@ MOD_LIVEPATCH2=test_klp_callbacks_demo2
 MOD_TARGET=test_klp_callbacks_mod
 MOD_TARGET_BUSY=test_klp_callbacks_busy
 
-set_dynamic_debug
+setup_config
 
 
 # TEST: target module before livepatch

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

@@ -7,7 +7,7 @@
 MOD_LIVEPATCH=test_klp_livepatch
 MOD_REPLACE=test_klp_atomic_replace
 
-set_dynamic_debug
+setup_config
 
 
 # TEST: basic function patching

tools/testing/selftests/livepatch/test-shadow-vars.sh

@@ -6,7 +6,7 @@
 
 MOD_TEST=test_klp_shadow_vars
 
-set_dynamic_debug
+setup_config
 
 
 # TEST: basic shadow variable API