1 // SPDX-License-Identifier: GPL-2.0+
3 * Switch to non-secure mode
5 * Copyright (c) 2018 Heinrich Schuchardt
7 * This module contains the ARMv8 specific code required to adjust the exception
8 * level before booting an operating system.
15 #include <asm/cache.h>
16 #include <asm/setjmp.h>
19 * entry_non_secure() - entry point when switching to non-secure mode
21 * When switching to non-secure mode switch_to_non_secure_mode() calls this
22 * function passing a jump buffer. We use this jump buffer to restore the
23 * original stack and register state.
25 * @non_secure_jmp: jump buffer for restoring stack and registers
27 static void entry_non_secure(struct jmp_buf_data *non_secure_jmp)
30 debug("Reached non-secure mode\n");
32 /* Restore stack and registers saved in switch_to_non_secure_mode() */
33 longjmp(non_secure_jmp, 1);
37 * switch_to_non_secure_mode() - switch to non-secure mode
39 * Exception level EL3 is meant to be used by the secure monitor only (ARM
40 * trusted firmware being one embodiment). The operating system shall be
41 * started at exception level EL2. So here we check the exception level
42 * and switch it if necessary.
44 void switch_to_non_secure_mode(void)
46 struct jmp_buf_data non_secure_jmp;
48 /* On AArch64 we need to make sure we call our payload in < EL3 */
49 if (current_el() == 3) {
50 if (setjmp(&non_secure_jmp))
52 dcache_disable(); /* flush cache before switch to EL2 */
54 /* Move into EL2 and keep running there */
55 armv8_switch_to_el2((uintptr_t)&non_secure_jmp, 0, 0, 0,
56 (uintptr_t)entry_non_secure, ES_TO_AARCH64);