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1 | // SPDX-License-Identifier: GPL-2.0+ |
2 | /* | |
3 | * Switch to non-secure mode | |
4 | * | |
5 | * Copyright (c) 2018 Heinrich Schuchardt | |
6 | * | |
7 | * This module contains the ARMv8 specific code required to adjust the exception | |
8 | * level before booting an operating system. | |
9 | */ | |
10 | ||
11 | #include <common.h> | |
12 | #include <bootm.h> | |
9edefc27 | 13 | #include <cpu_func.h> |
90526e9f | 14 | #include <asm/cache.h> |
f6c6df7e HS |
15 | #include <asm/setjmp.h> |
16 | ||
17 | /** | |
18 | * entry_non_secure() - entry point when switching to non-secure mode | |
19 | * | |
20 | * When switching to non-secure mode switch_to_non_secure_mode() calls this | |
21 | * function passing a jump buffer. We use this jump buffer to restore the | |
22 | * original stack and register state. | |
23 | * | |
24 | * @non_secure_jmp: jump buffer for restoring stack and registers | |
25 | */ | |
26 | static void entry_non_secure(struct jmp_buf_data *non_secure_jmp) | |
27 | { | |
28 | dcache_enable(); | |
29 | debug("Reached non-secure mode\n"); | |
30 | ||
31 | /* Restore stack and registers saved in switch_to_non_secure_mode() */ | |
32 | longjmp(non_secure_jmp, 1); | |
33 | } | |
34 | ||
35 | /** | |
36 | * switch_to_non_secure_mode() - switch to non-secure mode | |
37 | * | |
38 | * Exception level EL3 is meant to be used by the secure monitor only (ARM | |
39 | * trusted firmware being one embodiment). The operating system shall be | |
40 | * started at exception level EL2. So here we check the exception level | |
41 | * and switch it if necessary. | |
42 | */ | |
43 | void switch_to_non_secure_mode(void) | |
44 | { | |
45 | struct jmp_buf_data non_secure_jmp; | |
46 | ||
47 | /* On AArch64 we need to make sure we call our payload in < EL3 */ | |
48 | if (current_el() == 3) { | |
49 | if (setjmp(&non_secure_jmp)) | |
50 | return; | |
51 | dcache_disable(); /* flush cache before switch to EL2 */ | |
52 | ||
53 | /* Move into EL2 and keep running there */ | |
54 | armv8_switch_to_el2((uintptr_t)&non_secure_jmp, 0, 0, 0, | |
55 | (uintptr_t)entry_non_secure, ES_TO_AARCH64); | |
56 | } | |
57 | } |