Chloe M.
99 lines
1.7 KiB
ArmAsm
99 lines
1.7 KiB
ArmAsm
/*
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* Copyright (c) 2026, Chloe M.
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* Provided under the BSD-3 clause.
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*
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* Description: Low-level processor init
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* Author: Chloe M.
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*/
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.text
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.globl _start
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_start:
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cli /* Just in case */
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xor %rbp, %rbp /* Terminate callstack */
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lea g_GDTR(%rip), %rdi
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call MdGdtLoad
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mfence /* Flush caches */
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1: cli /* Disable interrupts */
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hlt /* Suspend processor */
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.text
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.globl MdGdtLoad
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MdGdtLoad:
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push %r12
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push %r13
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push %r14
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push %r15
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push %rbx
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push %rbp
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lgdt (%rdi) /* Load our own GDT */
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push $0x08 /* Kernel CS */
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lea 1f(%rip), %rbx /* Drop point */
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push %rbx /* RIP */
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lretq /* Flush prefetch + reload CS */
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1: mov $0x10, %ax /* Kernel DS */
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mov %ax, %ds
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mov %ax, %es
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mov %ax, %ss
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mov %ax, %fs
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xor %ax, %ax
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mov %ax, %gs
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pop %rbp
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pop %rbx
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pop %r15
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pop %r14
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pop %r13
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pop %r12
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retq
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.section .data
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.globl g_GDT
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g_GDT:
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.NULL:
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.word 0x0000
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.word 0x0000
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.byte 0x00
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.byte 0b00000000
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.byte 0b00000000
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.byte 0x00
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.CODE:
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.word 0x0000
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.word 0x0000
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.byte 0x00
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.byte 0b10011010
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.byte 0b00100000
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.byte 0x00
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.DATA:
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.word 0x0000
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.word 0x0000
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.byte 0x00
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.byte 0b10010010
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.byte 0b00000000
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.byte 0x00
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.UCODE:
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.word 0x0000
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.word 0x0000
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.byte 0x00
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.byte 0b11111010
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.byte 0b10101111
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.byte 0x00
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.UDATA:
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.word 0x0000
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.word 0x0000
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.byte 0x00
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.byte 0b11110010
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.byte 0b00000000
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.byte 0x00
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.TSS:
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.quad 0x00
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.quad 0x00
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.globl g_GDTR
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g_GDTR:
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.word g_GDTR - g_GDT
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.quad g_GDT
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