• John Tsichritzis's avatar
    Apply stricter speculative load restriction · 02b57943
    John Tsichritzis authored
    
    The SCTLR.DSSBS bit is zero by default thus disabling speculative loads.
    However, we also explicitly set it to zero for BL2 and TSP images when
    each image initialises its context. This is done to ensure that the
    image environment is initialised in a safe state, regardless of the
    reset value of the bit.
    
    Change-Id: If25a8396641edb640f7f298b8d3309d5cba3cd79
    Signed-off-by: default avatarJohn Tsichritzis <john.tsichritzis@arm.com>
    02b57943
bl2_entrypoint.S 3.41 KB
/*
 * Copyright (c) 2016-2019, ARM Limited and Contributors. All rights reserved.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

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

	.globl	bl2_vector_table
	.globl	bl2_entrypoint


vector_base bl2_vector_table
	b	bl2_entrypoint
	b	report_exception	/* Undef */
	b	report_exception	/* SVC call */
	b	report_exception	/* Prefetch abort */
	b	report_exception	/* Data abort */
	b	report_exception	/* Reserved */
	b	report_exception	/* IRQ */
	b	report_exception	/* FIQ */


func bl2_entrypoint
	/*---------------------------------------------
	 * Save arguments x0 - x3 from BL1 for future
	 * use.
	 * ---------------------------------------------
	 */
	mov	r9, r0
	mov	r10, r1
	mov	r11, r2
	mov	r12, r3

	/* ---------------------------------------------
	 * Set the exception vector to something sane.
	 * ---------------------------------------------
	 */
	ldr	r0, =bl2_vector_table
	stcopr	r0, VBAR
	isb

	/* --------------------------------------------------------
	 * Enable the instruction cache - disable speculative loads
	 * --------------------------------------------------------
	 */
	ldcopr	r0, SCTLR
	orr	r0, r0, #SCTLR_I_BIT
	bic	r0, r0, #SCTLR_DSSBS_BIT
	stcopr	r0, SCTLR
	isb

	/* ---------------------------------------------
	 * Since BL2 executes after BL1, it is assumed
	 * here that BL1 has already has done the
	 * necessary register initializations.
	 * ---------------------------------------------
	 */

	/* ---------------------------------------------
	 * Invalidate the RW memory used by the BL2
	 * image. This includes the data and NOBITS
	 * sections. This is done to safeguard against
	 * possible corruption of this memory by dirty
	 * cache lines in a system cache as a result of
	 * use by an earlier boot loader stage.
	 * ---------------------------------------------
	 */
	ldr	r0, =__RW_START__
	ldr	r1, =__RW_END__
	sub	r1, r1, r0
	bl	inv_dcache_range

	/* ---------------------------------------------
	 * Zero out NOBITS sections. There are 2 of them:
	 *   - the .bss section;
	 *   - the coherent memory section.
	 * ---------------------------------------------
	 */
	ldr	r0, =__BSS_START__
	ldr	r1, =__BSS_SIZE__
	bl	zeromem

#if USE_COHERENT_MEM
	ldr	r0, =__COHERENT_RAM_START__
	ldr	r1, =__COHERENT_RAM_UNALIGNED_SIZE__
	bl	zeromem
#endif

	/* --------------------------------------------
	 * 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.
	 * --------------------------------------------
	 */
	bl	plat_set_my_stack

	/* ---------------------------------------------
	 * Initialize the stack protector canary before
	 * any C code is called.
	 * ---------------------------------------------
	 */
#if STACK_PROTECTOR_ENABLED
	bl	update_stack_protector_canary
#endif

	/* ---------------------------------------------
	 * Perform BL2 setup
	 * ---------------------------------------------
	 */
	mov	r0, r9
	mov	r1, r10
	mov	r2, r11
	mov	r3, r12

	bl	bl2_setup

	/* ---------------------------------------------
	 * Jump to main function.
	 * ---------------------------------------------
	 */
	bl	bl2_main

	/* ---------------------------------------------
	 * Should never reach this point.
	 * ---------------------------------------------
	 */
	no_ret	plat_panic_handler

endfunc bl2_entrypoint