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