arch/arm/core/aarch64/reset.S

/*
 * Copyright (c) 2019 Carlo Caione <ccaione@baylibre.com>
 *
 * SPDX-License-Identifier: Apache-2.0
 */

/**
 * @file
 * @brief Reset handler
 *
 * Reset handler that prepares the system for running C code.
 */

#include <toolchain.h>
#include <linker/sections.h>
#include <arch/cpu.h>
#include "vector_table.h"
#include "macro_priv.inc"

_ASM_FILE_PROLOGUE

/*
 * Platform may do platform specific init at EL3.
 * The function implementation must preserve callee saved registers as per
 * Aarch64 ABI PCS.
 */
WTEXT(z_arch_el3_plat_init)
SECTION_FUNC(TEXT,z_arch_el3_plat_init)
ret

/**
 *
 * @brief Reset vector
 *
 * Ran when the system comes out of reset. The processor is in thread mode with
 * privileged level. At this point, neither SP_EL0 nor SP_ELx point to a valid
 * area in SRAM.
 *
 * When these steps are completed, jump to z_arm64_prep_c(), which will finish
 * setting up the system for running C code.
 *
 * @return N/A
 */
GTEXT(__reset)
SECTION_SUBSEC_FUNC(TEXT,_reset_section,__reset)

/*
 * The entry point is located at the __reset symbol, which is fetched by a XIP
 * image playing the role of a bootloader, which jumps to it, not through the
 * reset vector mechanism. Such bootloaders might want to search for a __start
 * symbol instead, so create that alias here.
 */
GTEXT(__start)
SECTION_SUBSEC_FUNC(TEXT,_reset_section,__start)

	/* Setup vector table */
	adr	x19, _vector_table

	switch_el x1, 3f, 2f, 1f
3:
	/* Initialize VBAR */
	msr	vbar_el3, x19
	isb

	/* Initialize sctlr_el3 to reset value */
	mov_imm	x1, SCTLR_EL3_RES1
	mrs     x0, sctlr_el3
	orr	x0, x0, x1
	msr	sctlr_el3, x0
	isb

	/* SError, IRQ and FIQ routing enablement in EL3 */
	mrs	x0, scr_el3
	orr	x0, x0, #(SCR_EL3_IRQ | SCR_EL3_FIQ | SCR_EL3_EA)
	msr	scr_el3, x0

	/*
	* Disable access traps to EL3 for CPACR, Trace, FP, ASIMD,
	* SVE from lower EL.
	*/
	mov_imm	x0, CPTR_EL3_RES_VAL
	mov_imm	x1, (CPTR_EL3_TTA | CPTR_EL3_TFP | CPTR_EL3_TCPAC)
	bic	x0, x0, x1
	orr	x0, x0, #(CPTR_EL3_EZ)
	msr	cptr_el3, x0
	isb

	/* Platform specific configurations needed in EL3 */
	bl	z_arch_el3_plat_init

#ifdef CONFIG_SWITCH_TO_EL1
	/*
	* Zephyr entry happened in EL3. Do EL3 specific init before
	* dropping to lower EL.
	*/
	/* Enable access control configuration from lower EL */
	mrs	x0, actlr_el3
	orr     x0, x0, #(ACTLR_EL3_L2ACTLR | ACTLR_EL3_L2ECTLR \
			 | ACTLR_EL3_L2CTLR)
	orr     x0, x0, #(ACTLR_EL3_CPUACTLR | ACTLR_EL3_CPUECTLR)
	msr	actlr_el3, x0

	/* Initialize sctlr_el1 to reset value */
	mov_imm	x0, SCTLR_EL1_RES1
	msr	sctlr_el1, x0

	/* Disable EA/IRQ/FIQ routing to EL3 and set EL1 to AArch64 */
	mov	x0, xzr
	orr	x0, x0, #(SCR_EL3_RW)
	msr	scr_el3, x0

	/* On eret return to secure EL1h with DAIF masked */
	mov	x0, xzr
	orr	x0, x0, #(DAIF_MASK)
	orr	x0, x0, #(SPSR_EL3_TO_EL1)
	orr	x0, x0, #(SPSR_EL3_h)
	msr	spsr_el3, x0

	adr	x0, 1f
	msr	elr_el3, x0
	eret
#endif
	/*
	 * Enable the instruction cache, stack pointer and data access
	 * alignment checks.
	 */
	mov	x1, #(SCTLR_I_BIT | SCTLR_A_BIT | SCTLR_SA_BIT)
	mrs	x0, sctlr_el3
	orr	x0, x0, x1
	msr	sctlr_el3, x0
	isb
	b	0f

2:
	/* Initialize VBAR */
	msr	vbar_el2, x19

	/* SError, IRQ and FIQ routing enablement in EL2 */
	mrs	x0, hcr_el2
	orr	x0, x0, #(HCR_EL2_FMO | HCR_EL2_IMO | HCR_EL2_AMO)
	msr	hcr_el2, x0

	/* Disable access trapping in EL2 for NEON/FP */
	msr	cptr_el2, xzr

	/*
	 * Enable the instruction cache, stack pointer and data access
	 * alignment checks.
	 */
	mov	x1, #(SCTLR_I_BIT | SCTLR_A_BIT | SCTLR_SA_BIT)
	mrs	x0, sctlr_el2
	orr	x0, x0, x1
	msr	sctlr_el2, x0
	b	0f

1:
	/* Initialize VBAR */
	msr	vbar_el1, x19

	/* Disable access trapping in EL1 for NEON/FP */
	mov	x0, #(CPACR_EL1_FPEN_NOTRAP)
	msr	cpacr_el1, x0

	/*
	 * Enable the instruction cache and el1 stack alignment check.
	 */
	mov	x1, #(SCTLR_I_BIT | SCTLR_SA_BIT)
	mrs	x0, sctlr_el1
	orr	x0, x0, x1
	msr	sctlr_el1, x0

0:
	isb

	/* Enable the SError interrupt */
	msr	daifclr, #(DAIFSET_ABT)

	/* Switch to SP_ELn and setup the stack */
	msr	spsel, #1
	ldr	x0, =(z_interrupt_stacks)
	add	x0, x0, #(CONFIG_ISR_STACK_SIZE)
	mov	sp, x0

	bl	z_arm64_prep_c