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/*
* Based on arch/arm/include/asm/cacheflush.h
*
* Copyright (C) 1999-2002 Russell King.
* Copyright (C) 2012 ARM Ltd.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <arch/asm.h>
#include <arch/cache_helpers.h>
/*
* Bring an ARMv8 processor we just gained control of (e.g. from IROM) into a
* known state regarding caches/SCTLR/PSTATE. Completely cleans and invalidates
* icache/dcache, disables MMU and dcache (if active), and enables unaligned
* accesses, icache and branch prediction (if inactive). Seeds the stack and
* initializes SP_EL0. Clobbers R22 and R23.
*/
ENTRY(arm64_init_cpu)
/* Initialize PSTATE (unmask all exceptions, select SP_EL0). */
msr SPSel, #0
msr DAIFClr, #0xf
/* TODO: This is where we'd put non-boot CPUs into WFI if needed. */
/* x22: SCTLR, return address: x23 (callee-saved by subroutine) */
mov x23, x30
/* TODO: Assert that we always start running at EL3 */
mrs x22, sctlr_el3
/* Activate ICache (12) already for speed during cache flush below. */
orr x22, x22, #(1 << 12)
msr sctlr_el3, x22
isb
/* Flush and invalidate dcache */
mov x0, #DCCISW
bl flush_dcache_all
/* Deactivate MMU (0), Alignment Check (1) and DCache (2) */
and x22, x22, # ~(1 << 0) & ~(1 << 1) & ~(1 << 2)
/* Activate Stack Alignment (3) because why not */
orr x22, x22, #(1 << 3)
/* Set to little-endian (25) */
and x22, x22, # ~(1 << 25)
/* Deactivate write-xor-execute enforcement (19) */
and x22, x22, # ~(1 << 19)
msr sctlr_el3, x22
/* Invalidate icache and TLB for good measure */
ic iallu
tlbi alle3
dsb sy
isb
/* Initialize stack with sentinel value to later check overflow. */
ldr x2, =0xdeadbeefdeadbeef
ldr x0, =_stack
ldr x1, =_estack
1:
stp x2, x2, [x0], #16
cmp x0, x1
bne 1b
/* Leave a line of beef dead for easier visibility in stack dumps. */
sub sp, x0, #16
ret x23
ENDPROC(arm64_init_cpu)
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