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Atmosphere/thermosphere/src/start.s

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/*
* 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/>.
*/
.section .crt0, "ax", %progbits
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.align 3
.global _start
.type _start, %function
_start:
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b start
b start2
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.global g_initialKernelEntrypoint
g_initialKernelEntrypoint:
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.quad 0
start:
mov x19, #1
b _startCommon
.global start2
.type start2, %function
start2:
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mov x19, xzr
_startCommon:
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// Disable interrupts, select sp_el2
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msr daifset, 0b1111
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msr spsel, #1
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// Set VBAR
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adrp x8, __vectors_start__
add x8, x8, #:lo12:__vectors_start__
msr vbar_el2, x8
// Set system to sane defaults, aarch64 for el1
mov x4, #0x0838
movk x4, #0xC5, lsl #16
orr x1, x4, #0x30000000
mov x2, #(1 << 31)
mov x3, #0xFFFFFFFF
msr sctlr_el2, x1
msr hcr_el2, x2
msr dacr32_el2, x3
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msr sctlr_el1, x4
dsb sy
isb
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mov x2, x0
// Get core ID
// Ensure Aff0 is 4-1 at most (4 cores), and that Aff1, 2 and 3 are 0 (1 cluster only)
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mrs x0, mpidr_el1
tst x0, #(0xFF << 32)
bne .
and x0, x0, #0x00FFFFFF // Aff0 to 2
cmp x0, #4
bhs .
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// Set tmp stack (__stacks_top__ is aligned)
adrp x8, __stacks_top__
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lsl x9, x0, #10
sub sp, x8, x9
// Set up x18
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mov w1, w19
bl coreCtxInit
stp x18, xzr, [sp, #-0x10]!
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// Don't call init array to save space?
// Clear BSS & call main for the first core executing this code
cbz x19, _enable_mmu
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adrp x0, __bss_start__
add x0, x0, #:lo12:__bss_start__
mov w1, wzr
adrp x2, __end__
add x2, x2, #:lo12:__end__
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sub x2, x2, x0
bl memset
_enable_mmu:
bl configureMemoryMapEnableMmu
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dsb sy
isb
bl main
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// Jump to kernel
mov x8, #(0b1111 << 6 | 0b0101) // EL1h+DAIF
msr spsr_el2, x8
ldp x0, x1, [x18]
msr elr_el2, x1
dsb sy
isb
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eret
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.pool