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 ARMv7 specific code required for leaving the
8  * secure mode before booting an operating system.
9  */
10 
11 #include <common.h>
12 #include <bootm.h>
13 #include <asm/armv7.h>
14 #include <asm/secure.h>
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  * Operating systems may expect to run in non-secure mode. Here we check if
39  * we are running in secure mode and switch to non-secure mode if necessary.
40  */
41 void switch_to_non_secure_mode(void)
42 {
43 	static bool is_nonsec;
44 	struct jmp_buf_data non_secure_jmp;
45 
46 	if (armv7_boot_nonsec() && !is_nonsec) {
47 		if (setjmp(&non_secure_jmp))
48 			return;
49 		dcache_disable();	/* flush cache before switch to HYP */
50 		armv7_init_nonsec();
51 		is_nonsec = true;
52 		secure_ram_addr(_do_nonsec_entry)(entry_non_secure,
53 						  (uintptr_t)&non_secure_jmp,
54 						  0, 0);
55 	}
56 }
57