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 <bootm.h>
12 #include <cpu_func.h>
13 #include <log.h>
14 #include <setjmp.h>
15 #include <asm/armv7.h>
16 #include <asm/secure.h>
17 
18 /**
19  * entry_non_secure() - entry point when switching to non-secure mode
20  *
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.
24  *
25  * @non_secure_jmp:	jump buffer for restoring stack and registers
26  */
entry_non_secure(jmp_buf non_secure_jmp)27 static void entry_non_secure(jmp_buf non_secure_jmp)
28 {
29 	dcache_enable();
30 	debug("Reached non-secure mode\n");
31 
32 	/* Restore stack and registers saved in switch_to_non_secure_mode() */
33 	longjmp(non_secure_jmp, 1);
34 }
35 
36 /**
37  * switch_to_non_secure_mode() - switch to non-secure mode
38  *
39  * Operating systems may expect to run in non-secure mode. Here we check if
40  * we are running in secure mode and switch to non-secure mode if necessary.
41  */
switch_to_non_secure_mode(void)42 void switch_to_non_secure_mode(void)
43 {
44 	static bool is_nonsec;
45 	jmp_buf non_secure_jmp;
46 
47 	if (armv7_boot_nonsec() && !is_nonsec) {
48 		if (setjmp(non_secure_jmp))
49 			return;
50 		dcache_disable();	/* flush cache before switch to HYP */
51 		armv7_init_nonsec();
52 		is_nonsec = true;
53 		secure_ram_addr(_do_nonsec_entry)(entry_non_secure,
54 						  (uintptr_t)&non_secure_jmp,
55 						  0, 0);
56 	}
57 }
58