• Yatharth Kochar's avatar
    Call reset handlers upon BL3-1 entry. · 79a97b2e
    Yatharth Kochar authored
    This patch adds support to call the reset_handler() function in BL3-1 in the
    cold and warm boot paths when another Boot ROM reset_handler() has already run.
    
    This means the BL1 and BL3-1 versions of the CPU and platform specific reset
    handlers may execute different code to each other. This enables a developer to
    perform additional actions or undo actions already performed during the first
    call of the reset handlers e.g. apply additional errata workarounds.
    
    Typically, the reset handler will be first called from the BL1 Boot ROM. Any
    additional functionality can be added to the reset handler when it is called
    from BL3-1 resident in RW memory. The constant FIRST_RESET_HANDLER_CALL is used
    to identify whether this is the first version of the reset handler code to be
    executed or an overridden version of the code.
    
    The Cortex-A57 errata workarounds are applied only if they have not already been
    applied.
    
    Fixes ARM-software/tf-issue#275
    
    Change-Id: Id295f106e4fda23d6736debdade2ac7f2a9a9053
    79a97b2e
bl31_entrypoint.S 6.78 KB
/*
 * Copyright (c) 2013-2014, ARM Limited and Contributors. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of ARM nor the names of its contributors may be used
 * to endorse or promote products derived from this software without specific
 * prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <arch.h>
#include <asm_macros.S>
#include <bl_common.h>

	.globl	bl31_entrypoint


	/* -----------------------------------------------------
	 * bl31_entrypoint() is the cold boot entrypoint,
	 * executed only by the primary cpu.
	 * -----------------------------------------------------
	 */

func bl31_entrypoint
	/* ---------------------------------------------------------------
	 * Preceding bootloader has populated x0 with a pointer to a
	 * 'bl31_params' structure & x1 with a pointer to platform
	 * specific structure
	 * ---------------------------------------------------------------
	 */
#if !RESET_TO_BL31
	mov	x20, x0
	mov	x21, x1
#else
	/* ---------------------------------------------
	 * Set the CPU endianness before doing anything
	 * that might involve memory reads or writes.
	 * ---------------------------------------------
	 */
	mrs	x0, sctlr_el3
	bic	x0, x0, #SCTLR_EE_BIT
	msr	sctlr_el3, x0
	isb
#endif

	/* ---------------------------------------------
	 * When RESET_TO_BL31 is true, perform any
	 * processor specific actions upon reset e.g.
	 * cache, tlb invalidations, errata workarounds
	 * etc.
	 * When RESET_TO_BL31 is false, perform any
	 * processor specific actions which undo or are
	 * in addition to the actions performed by the
	 * reset handler in the Boot ROM (BL1).
	 * ---------------------------------------------
	 */
	bl	reset_handler

	/* ---------------------------------------------
	 * 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

	/* ---------------------------------------------
	 * Initialise cpu_data early to enable crash
	 * reporting to have access to crash stack.
	 * Since crash reporting depends on cpu_data to
	 * report the unhandled exception, not
	 * doing so can lead to recursive exceptions due
	 * to a NULL TPIDR_EL3
	 * ---------------------------------------------
	 */
	bl	init_cpu_data_ptr

	/* ---------------------------------------------
	 * Set the exception vector.
	 * ---------------------------------------------
	 */
	adr	x1, runtime_exceptions
	msr	vbar_el3, x1
	isb

	/* ---------------------------------------------
	 * Enable the SError interrupt now that the
	 * exception vectors have been setup.
	 * ---------------------------------------------
	 */
	msr	daifclr, #DAIF_ABT_BIT

	/* ---------------------------------------------------------------------
	 * The initial state of the Architectural feature trap register
	 * (CPTR_EL3) is unknown and it must be set to a known state. All
	 * feature traps are disabled. Some bits in this register are marked as
	 * Reserved and should not be modified.
	 *
	 * CPTR_EL3.TCPAC: This causes a direct access to the CPACR_EL1 from EL1
	 *  or the CPTR_EL2 from EL2 to trap to EL3 unless it is trapped at EL2.
	 * CPTR_EL3.TTA: This causes access to the Trace functionality to trap
	 *  to EL3 when executed from EL0, EL1, EL2, or EL3. If system register
	 *  access to trace functionality is not supported, this bit is RES0.
	 * CPTR_EL3.TFP: This causes instructions that access the registers
	 *  associated with Floating Point and Advanced SIMD execution to trap
	 *  to EL3 when executed from any exception level, unless trapped to EL1
	 *  or EL2.
	 * ---------------------------------------------------------------------
	 */
	mrs	x1, cptr_el3
	bic	w1, w1, #TCPAC_BIT
	bic	w1, w1, #TTA_BIT
	bic	w1, w1, #TFP_BIT
	msr	cptr_el3, x1

#if RESET_TO_BL31
	/* -------------------------------------------------------
	 * Will not return from this macro if it is a warm boot.
	 * -------------------------------------------------------
	 */
	wait_for_entrypoint
	bl	platform_mem_init
#endif

	/* ---------------------------------------------
	 * Zero out NOBITS sections. There are 2 of them:
	 *   - the .bss section;
	 *   - the coherent memory section.
	 * ---------------------------------------------
	 */
	ldr	x0, =__BSS_START__
	ldr	x1, =__BSS_SIZE__
	bl	zeromem16

#if USE_COHERENT_MEM
	ldr	x0, =__COHERENT_RAM_START__
	ldr	x1, =__COHERENT_RAM_UNALIGNED_SIZE__
	bl	zeromem16
#endif

	/* ---------------------------------------------
	 * Initialize the cpu_ops pointer.
	 * ---------------------------------------------
	 */
	bl	init_cpu_ops

	/* ---------------------------------------------
	 * Use SP_EL0 for the C runtime stack.
	 * ---------------------------------------------
	 */
	msr	spsel, #0

	/* --------------------------------------------
	 * Allocate a stack whose memory will be marked
	 * as Normal-IS-WBWA when the MMU is enabled.
	 * There is no risk of reading stale stack
	 * memory after enabling the MMU as only the
	 * primary cpu is running at the moment.
	 * --------------------------------------------
	 */
	mrs	x0, mpidr_el1
	bl	platform_set_stack

	/* ---------------------------------------------
	 * Perform platform specific early arch. setup
	 * ---------------------------------------------
	 */
#if RESET_TO_BL31
	mov	x0, 0
	mov	x1, 0
#else
	mov	x0, x20
	mov	x1, x21
#endif

	bl	bl31_early_platform_setup
	bl	bl31_plat_arch_setup

	/* ---------------------------------------------
	 * Jump to main function.
	 * ---------------------------------------------
	 */
	bl	bl31_main

	b	el3_exit