bl31_entrypoint.S

/*
 * Copyright (c) 2013-2016, 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 <bl_common.h>
#include <el3_common_macros.S>
#include <xlat_tables.h>

	.globl	bl31_entrypoint
	.globl	bl31_warm_entrypoint

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

func bl31_entrypoint
#if !RESET_TO_BL31
	/* ---------------------------------------------------------------
	 * Preceding bootloader has populated x0 with a pointer to a
	 * 'bl31_params' structure & x1 with a pointer to platform
	 * specific structure
	 * ---------------------------------------------------------------
	 */
	mov	x20, x0
	mov	x21, x1

	/* ---------------------------------------------------------------------
	 * For !RESET_TO_BL31 systems, only the primary CPU ever reaches
	 * bl31_entrypoint() during the cold boot flow, so the cold/warm boot
	 * and primary/secondary CPU logic should not be executed in this case.
	 *
	 * Also, assume that the previous bootloader has already set up the CPU
	 * endianness and has initialised the memory.
	 * ---------------------------------------------------------------------
	 */
	el3_entrypoint_common					\
		_set_endian=0					\
		_warm_boot_mailbox=0				\
		_secondary_cold_boot=0				\
		_init_memory=0					\
		_init_c_runtime=1				\
		_exception_vectors=runtime_exceptions

	/* ---------------------------------------------------------------------
	 * Relay the previous bootloader's arguments to the platform layer
	 * ---------------------------------------------------------------------
	 */
	mov	x0, x20
	mov	x1, x21
#else
	/* ---------------------------------------------------------------------
	 * For RESET_TO_BL31 systems which have a programmable reset address,
	 * bl31_entrypoint() is executed only on the cold boot path so we can
	 * skip the warm boot mailbox mechanism.
	 * ---------------------------------------------------------------------
	 */
	el3_entrypoint_common					\
		_set_endian=1					\
		_warm_boot_mailbox=!PROGRAMMABLE_RESET_ADDRESS	\
		_secondary_cold_boot=!COLD_BOOT_SINGLE_CPU	\
		_init_memory=1					\
		_init_c_runtime=1				\
		_exception_vectors=runtime_exceptions

	/* ---------------------------------------------------------------------
	 * For RESET_TO_BL31 systems, BL31 is the first bootloader to run so
	 * there's no argument to relay from a previous bootloader. Zero the
	 * arguments passed to the platform layer to reflect that.
	 * ---------------------------------------------------------------------
	 */
	mov	x0, 0
	mov	x1, 0
#endif /* RESET_TO_BL31 */

	/* ---------------------------------------------
	 * Perform platform specific early arch. setup
	 * ---------------------------------------------
	 */
	bl	bl31_early_platform_setup
	bl	bl31_plat_arch_setup

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

	/* -------------------------------------------------------------
	 * Clean the .data & .bss sections to main memory. This ensures
	 * that any global data which was initialised by the primary CPU
	 * is visible to secondary CPUs before they enable their data
	 * caches and participate in coherency.
	 * -------------------------------------------------------------
	 */
	adr	x0, __DATA_START__
	adr	x1, __DATA_END__
	sub	x1, x1, x0
	bl	clean_dcache_range

	adr	x0, __BSS_START__
	adr	x1, __BSS_END__
	sub	x1, x1, x0
	bl	clean_dcache_range

	b	el3_exit
endfunc bl31_entrypoint

	/* --------------------------------------------------------------------
	 * This CPU has been physically powered up. It is either resuming from
	 * suspend or has simply been turned on. In both cases, call the BL31
	 * warmboot entrypoint
	 * --------------------------------------------------------------------
	 */
func bl31_warm_entrypoint
	/*
	 * On the warm boot path, most of the EL3 initialisations performed by
	 * 'el3_entrypoint_common' must be skipped:
	 *
	 *  - Only when the platform bypasses the BL1/BL31 entrypoint by
	 *    programming the reset address do we need to set the CPU endianness.
	 *    In other cases, we assume this has been taken care by the
	 *    entrypoint code.
	 *
	 *  - No need to determine the type of boot, we know it is a warm boot.
	 *
	 *  - Do not try to distinguish between primary and secondary CPUs, this
	 *    notion only exists for a cold boot.
	 *
	 *  - No need to initialise the memory or the C runtime environment,
	 *    it has been done once and for all on the cold boot path.
	 */
	el3_entrypoint_common					\
		_set_endian=PROGRAMMABLE_RESET_ADDRESS		\
		_warm_boot_mailbox=0				\
		_secondary_cold_boot=0				\
		_init_memory=0					\
		_init_c_runtime=0				\
		_exception_vectors=runtime_exceptions

	/* --------------------------------------------
	 * Enable the MMU with the DCache disabled. It
	 * is safe to use stacks allocated in normal
	 * memory as a result. All memory accesses are
	 * marked nGnRnE when the MMU is disabled. So
	 * all the stack writes will make it to memory.
	 * All memory accesses are marked Non-cacheable
	 * when the MMU is enabled but D$ is disabled.
	 * So used stack memory is guaranteed to be
	 * visible immediately after the MMU is enabled
	 * Enabling the DCache at the same time as the
	 * MMU can lead to speculatively fetched and
	 * possibly stale stack memory being read from
	 * other caches. This can lead to coherency
	 * issues.
	 * --------------------------------------------
	 */
	mov	x0, #DISABLE_DCACHE
	bl	bl31_plat_enable_mmu

	bl	psci_warmboot_entrypoint

	b	el3_exit
endfunc bl31_warm_entrypoint