Chloe M.
88 lines
2.4 KiB
ArmAsm
88 lines
2.4 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: Interrupt descriptor table
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* Author: Chloe M.
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*/
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#include <machine/idt.h>
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#include <machine/gdt.h>
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#define IDT_VECTOR_SHIFT 4
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.text
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.globl MdIdtSetEntry
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MdIdtSetEntry:
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/*
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* Set an IDT entry
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*
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* @[RDI]: Interrupt vector of entry to set
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* @[RSI]: Interrupt service routine base
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* @[RDX]: Interrupt gate type
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* @[RCX]: Interrupt stack table index
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*/
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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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shl $IDT_VECTOR_SHIFT, %rdi /* Scale the vector by IDT size */
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lea IdtTable(%rip), %rbx /* IDT base -> RBX */
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add %rdi, %rbx /* Obtain the entry */
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mov %rsi, %rax /* ISR base -> RAX */
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and $0xFFFF, %rax /* Obtain ISR[15:0] */
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mov %ax, 0(%rbx) /* Set the ISR base */
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movw $GDT_KCODE, 2(%rbx) /* Set the code selector */
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xor %rax, %rax /* Clear out RAX */
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and $0x3, %cl /* Ensure we only have 3 bits */
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or %cl, %al /* Merge it with RAX */
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and $0xF, %rdx /* Ensure we only get 4 bits */
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shl $8, %rdx /* Prepare to merge it */
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or %rdx, %rax /* Merge it */
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or $1<<15, %rax /* Mark as present */
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cmpb $IDT_USER_GATE, %dl /* Is this DPL3? */
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jne 1f /* No, skip .Dpl3 */
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.Dpl3:
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or $3<<13, %rax /* Set DPL 3 */
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1: mov %rsi, %r12 /* Copy ISR base to R12 */
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shr $16, %r12 /* Obtain the middle 16-bits */
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and $0xFFFF, %r12 /* Isolate it */
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shl $16, %r12 /* Shift it back up */
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or %r12, %rax /* Merge it */
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mov %rax, 4(%rbx) /* Set the second dword */
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mov %rsi, %r12 /* Copy ISR base to R12 */
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shr $32, %r12 /* Isolate the upper dword */
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mov %r12, 8(%rbx) /* Write it */
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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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.globl MdIdtLoad
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MdIdtLoad:
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lea Idtr(%rip), %rax
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lidt (%rax)
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retq
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.section .data
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Idtr:
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.word 4095
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.quad IdtTable
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.section .bss
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.align 8
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IdtTable:
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.skip 4096, 0
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