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Atmosphere/exosphere/start.s
TuxSH a00e68e94a Write a significant chunk of coldboot init...
...merge start.cold.s and start.warm.s, other changes, etc.
2018-02-25 03:34:15 +01:00

148 lines
4.1 KiB
ArmAsm

.macro ERRATUM_INVALIDATE_BTB_AT_BOOT
/* Nintendo copy-pasted https://github.com/ARM-software/arm-trusted-firmware/blob/master/plat/nvidia/tegra/common/aarch64/tegra_helpers.S#L312 */
/*
* Copyright (c) 2015-2017, ARM Limited and Contributors. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
/* The following comments are mine. */
/* mask all interrupts */
msr daifset, 0b1111
/*
Enable invalidates of branch target buffer, then flush
the entire instruction cache at the local level, and
with the reg change, the branch target buffer, then disable
invalidates of the branch target buffer again.
*/
mrs x0, cpuactlr_el1
orr x0, x0, #1
msr cpuactlr_el1, x0
dsb sy
isb
ic iallu
dsb sy
isb
mrs x0, cpuactlr_el1
bic x0, x0, #1
msr cpuactlr_el1, x0
.rept 7
nop /* wait long enough for the write to cpuactlr_el1 to have completed */
.endr
/* if the OS lock is set, disable it and request a warm reset */
mrs x0, oslsr_el1
ands x0, x0, #2
b.eq _set_lock_and_sp
mov x0, xzr
msr oslar_el1, x0
mov x0, #(1 << 63)
msr cpuactlr_el1, x0 /* disable regional clock gating */
isb
mov x0, #3
msr rmr_el3, x0
isb
dsb sy
/* Nintendo forgot to copy-paste the branch instruction below. */
_reset_wfi:
wfi
b _reset_wfi
.rept 65
nop /* guard against speculative excecution */
.endr
_set_lock_and_sp:
/* set the OS lock */
mov x0, #1
msr oslar_el1, x0
.endm
.align 6
.section .text.cold.start, "ax", %progbits
.global __start_cold
__start_cold:
ERRATUM_INVALIDATE_BTB_AT_BOOT
msr spsel, #0
bl get_coldboot_crt0_stack_address /* should be optimized so it doesn't make function calls */
mov sp, x0
bl coldboot_init
ldr x16, =__jump_to_main_cold
br x16
.align 6
.section .text.warm.start, "ax", %progbits
.global __start_warm
__start_warm:
ERRATUM_INVALIDATE_BTB_AT_BOOT
/* For some reasons, Nintendo uses spsel, #1 here, causing issues if an exception occurs */
msr spsel, #0
bl get_warmboot_crt0_stack_address /* should be optimized so it doesn't make function calls */
mov sp, x0
bl warmboot_init
ldr x16, =__jump_to_main_warm
br x16
.section .text.__jump_to_main_cold, "ax", %progbits
__jump_to_main_cold:
bl __set_exception_entry_stack_pointer
bl get_pk2ldr_stack_address
mov sp, x0
bl load_package2
mov w0, #3 /* use core3 stack temporarily */
bl get_exception_entry_stack_address
mov sp, x0
b coldboot_main
.section .text.__jump_to_main_warm, "ax", %progbits
__jump_to_main_warm:
/* Nintendo doesn't do that here, causing issues if an exception occurs */
bl __set_exception_entry_stack_pointer
bl get_pk2ldr_stack_address
mov sp, x0
bl load_package2
mov w0, #3 /* use core0,1,2 stack bottom + 0x800 (VA of warmboot crt0 sp) temporarily */
bl get_exception_entry_stack_address
add sp, x0, #0x800
b warmboot_main
.section .text.__set_exception_entry_stack, "ax", %progbits
.type __set_exception_entry_stack, %function
.global __set_exception_entry_stack
__set_exception_entry_stack_pointer:
/* If SPSel == 1 on entry, make sure your function doesn't use stack variables! */
mov x16, lr
mrs x17, spsel
msr x0, mpidr_el1
and w0, w0, #3
bl get_exception_entry_stack_address /* should be optimized so it doesn't make function calls */
msr spsel, #1
mov sp, x0
msr spsel, x17
mov lr, x16
ret
.section .text.__jump_to_lower_el, "ax", %progbits
.global __jump_to_lower_el
.type __jump_to_lower_el, %function
__jump_to_lower_el:
/* x0: arg (context ID), x1: entrypoint, w2: exception level */
msr elr_el3, x1
mov x1, #((0b1111 << 6) | 1) /* DAIF set and SP = SP_ELx*/
orr x1, w2, lsl#2
msr spsr_el3, x1
bl __set_exception_entry_stack_pointer
isb
eret