[app][uefi] Call kernel at an identity mapped stack

lib/uefi/switch_stack.S

@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+ 
+#include <lk/asm.h>
+
+
+// int call_with_stack(void *stack, int (*fp)(), int param1, int param2);
+FUNCTION(call_with_stack)
+stp     fp, lr, [sp, #-16]!
+mov     fp, sp
+
+sub     x0,x0,16
+mov     x6,sp
+str     x6,[x0]
+mov     sp,x0
+mov     x5,x1
+mov     x0,x2
+mov     x1,x3
+blr     x5
+ldr     x6,[sp]
+mov     sp,x6
+
+ldp     fp, lr, [sp], 16
+ret     lr