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Atmosphere/thermosphere/src/start.s
2021-02-19 21:51:19 +00:00

79 lines
1.8 KiB
ArmAsm

/*
* Copyright (c) 2019 Atmosphère-NX
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope 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.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/* For some reason GAS doesn't know about it, even with .cpu cortex-a57 */
#define cpuactlr_el1 s3_1_c15_c2_0
#define cpuectlr_el1 s3_1_c15_c2_1
.section .crt0, "ax", %progbits
.align 3
.global _start
.type _start, %function
_start:
b start
nop
.global g_kernelEntrypoint
g_kernelEntrypoint:
.quad 0
start:
// Disable interrupts, select sp_el2
msr daifset, 0b1111
msr spsel, #1
// Save arg, load entrypoint & spsr
mov x19, x0
ldr x8, g_kernelEntrypoint
msr elr_el2, x8
mov x8, #(0b1111 << 6 | 0b0101) // EL1h+DAIF
msr spsr_el2, x8
// Make sure the regs have been set
dsb sy
isb
// Set VBAR
ldr x8, =__vectors_start__
msr vbar_el2, x8
// Set tmp stack
ldr x8, =__stacks_top__
mov sp, x8
// Make sure the regs have been set
dsb sy
isb
// Don't call init array to save space?
// Clear BSS
ldr x0, =__bss_start__
mov w1, #0
ldr x2, =__end__
sub x2, x2, x0
bl memset
// TODO
bl main
// Jump to kernel
mov x0, x19
dsb sy
isb
eret
.pool