u-boot/arch/arm/cpu/armv7/exception_level.c

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// SPDX-License-Identifier: GPL-2.0+
/*
* Switch to non-secure mode
*
* Copyright (c) 2018 Heinrich Schuchardt
*
* This module contains the ARMv7 specific code required for leaving the
* secure mode before booting an operating system.
*/
#include <common.h>
#include <bootm.h>
#include <asm/armv7.h>
#include <asm/secure.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
*
* Operating systems may expect to run in non-secure mode. Here we check if
* we are running in secure mode and switch to non-secure mode if necessary.
*/
void switch_to_non_secure_mode(void)
{
static bool is_nonsec;
struct jmp_buf_data non_secure_jmp;
if (armv7_boot_nonsec() && !is_nonsec) {
if (setjmp(&non_secure_jmp))
return;
dcache_disable(); /* flush cache before switch to HYP */
armv7_init_nonsec();
is_nonsec = true;
secure_ram_addr(_do_nonsec_entry)(entry_non_secure,
(uintptr_t)&non_secure_jmp,
0, 0);
}
}