1/*
2 * Copyright (c) 2015, ARM Limited and Contributors. All rights reserved.
3 *
4 * SPDX-License-Identifier: BSD-3-Clause
5 */
6
7#include <asm_macros.S>
8#include "tlkd_private.h"
9
10	.global tlkd_enter_sp
11	.global tlkd_exit_sp
12
13	/* ---------------------------------------------
14	 * This function is called with SP_EL0 as stack.
15	 * Here we stash our EL3 callee-saved registers
16	 * on to the stack as a part of saving the C
17	 * runtime and enter the secure payload.
18	 * 'x0' contains a pointer to the memory where
19	 * the address of the C runtime context is to be
20	 * saved.
21	 * ---------------------------------------------
22	 */
23func tlkd_enter_sp
24	/* Make space for the registers that we're going to save */
25	mov	x3, sp
26	str	x3, [x0, #0]
27	sub	sp, sp, #TLKD_C_RT_CTX_SIZE
28
29	/* Save callee-saved registers on to the stack */
30	stp	x19, x20, [sp, #TLKD_C_RT_CTX_X19]
31	stp	x21, x22, [sp, #TLKD_C_RT_CTX_X21]
32	stp	x23, x24, [sp, #TLKD_C_RT_CTX_X23]
33	stp	x25, x26, [sp, #TLKD_C_RT_CTX_X25]
34	stp	x27, x28, [sp, #TLKD_C_RT_CTX_X27]
35	stp	x29, x30, [sp, #TLKD_C_RT_CTX_X29]
36
37	/* ----------------------------------------------
38	 * Everything is setup now. el3_exit() will
39	 * use the secure context to restore to the
40	 * general purpose and EL3 system registers to
41	 * ERET into the secure payload.
42	 * ----------------------------------------------
43	 */
44	b	el3_exit
45endfunc tlkd_enter_sp
46
47	/* ----------------------------------------------
48	 * This function is called with 'x0' pointing to
49	 * a C runtime context saved in tlkd_enter_sp().
50	 * It restores the saved registers and jumps to
51	 * that runtime with 'x0' as the new sp. This
52	 * destroys the C runtime context that had been
53	 * built on the stack below the saved context by
54	 * the caller. Later the second parameter 'x1'
55	 * is passed as return value to the caller
56	 * ----------------------------------------------
57	 */
58func tlkd_exit_sp
59	/* Restore the previous stack */
60	mov	sp, x0
61
62	/* Restore callee-saved registers on to the stack */
63	ldp	x19, x20, [x0, #(TLKD_C_RT_CTX_X19 - TLKD_C_RT_CTX_SIZE)]
64	ldp	x21, x22, [x0, #(TLKD_C_RT_CTX_X21 - TLKD_C_RT_CTX_SIZE)]
65	ldp	x23, x24, [x0, #(TLKD_C_RT_CTX_X23 - TLKD_C_RT_CTX_SIZE)]
66	ldp	x25, x26, [x0, #(TLKD_C_RT_CTX_X25 - TLKD_C_RT_CTX_SIZE)]
67	ldp	x27, x28, [x0, #(TLKD_C_RT_CTX_X27 - TLKD_C_RT_CTX_SIZE)]
68	ldp	x29, x30, [x0, #(TLKD_C_RT_CTX_X29 - TLKD_C_RT_CTX_SIZE)]
69
70	/* ------------------------------------------------
71	 * This should take us back to the instruction
72	 * after the call to the last tlkd_enter_sp().
73	 * Place the second parameter to x0 so that the
74	 * caller will see it as a return value from the
75	 * original entry call
76	 * ------------------------------------------------
77	 */
78	mov	x0, x1
79	ret
80endfunc tlkd_exit_sp
81