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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 <common.h>
- #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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