220 lines
7.2 KiB
C
220 lines
7.2 KiB
C
// ke_idt.c - GDT, IDT, and TSS initialisation
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//
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// GDT layout (matches segment selectors in ke_switch.asm / ke_syscall.asm):
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// 0x00 null
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// 0x08 ring-0 code (64-bit)
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// 0x10 ring-0 data
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// 0x18 ring-3 code (64-bit, DPL=3)
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// 0x20 ring-3 data (DPL=3) - note: 0x1B/0x23 = 0x18|3 / 0x20|3
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// 0x28 TSS low
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// 0x30 TSS high
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#include <stdint.h>
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#include <string.h>
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#include <ke_idt.h>
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// External assembly procedures
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extern void KeFlushGdt(void* pGdtr, uint16_t codeSel, uint16_t dataSel, uint16_t tssSel);
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extern void KeFlushIdt(void* pIdtr);
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extern void KeIrqStub0(void);
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extern void KeIrqStub1(void);
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extern void KeIrqStub2(void);
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extern void KeIrqStub3(void);
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extern void KeIrqStub4(void);
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extern void KeIrqStub5(void);
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extern void KeIrqStub6(void);
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extern void KeIrqStub7(void);
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extern void KeIrqStub8(void);
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extern void KeIrqStub9(void);
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extern void KeIrqStub10(void);
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extern void KeIrqStub11(void);
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extern void KeIrqStub12(void);
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extern void KeIrqStub13(void);
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extern void KeIrqStub14(void);
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extern void KeIrqStub15(void);
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extern void KeIrqStub16(void);
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extern void KeIrqStub17(void);
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extern void KeIrqStub18(void);
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extern void KeIrqStub19(void);
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extern void KeIrqStub20(void);
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extern void KeIrqStub21(void);
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extern void KeIrqStub22(void);
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extern void KeIrqStub23(void);
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extern void KeFaultDB(void);
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extern void KeFaultNMI(void);
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extern void KeFaultBP(void);
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extern void KeFaultOF(void);
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extern void KeFaultBR(void);
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extern void KeFaultUD(void);
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extern void KeFaultNM(void);
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extern void KeFaultDF(void);
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extern void KeFaultCSO(void);
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extern void KeFaultTS(void);
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extern void KeFaultNP(void);
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extern void KeFaultSS(void);
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extern void KeFaultRSV15(void);
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extern void KeFaultMF(void);
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extern void KeFaultAC(void);
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extern void KeFaultMC(void);
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extern void KeFaultXM(void);
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extern void KeFaultVE(void);
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extern void KeFaultCP(void);
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extern void KeFaultRSV22(void);
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extern void KeFaultRSV23(void);
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extern void KeFaultRSV24(void);
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extern void KeFaultRSV25(void);
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extern void KeFaultRSV26(void);
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extern void KeFaultRSV27(void);
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extern void KeFaultHV(void);
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extern void KeFaultVC(void);
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extern void KeFaultSX(void);
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extern void KeFaultRSV31(void);
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#define NUM_IRQS 24
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// ---------------------------------------------------------------------------
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// GDT
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// ---------------------------------------------------------------------------
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#define GDT_ENTRIES 8
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#define KERNEL_IST_STACK_SIZE 0x4000
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static uint64_t gGdt[GDT_ENTRIES];
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static uint8_t gKernelStack[KERNEL_IST_STACK_SIZE];
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#pragma pack(push, 1)
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typedef struct { uint16_t Limit; uint64_t Base; } GDTR;
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#pragma pack(pop)
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static void KiGdtSetEntry(int idx, uint32_t base, uint32_t limit,
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uint8_t access, uint8_t flags) {
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gGdt[idx] =
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((uint64_t)(limit & 0xFFFF)) |
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((uint64_t)(base & 0xFFFFFF) << 16) |
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((uint64_t)access << 40) |
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((uint64_t)(limit >> 16 & 0xF)<< 48) |
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((uint64_t)(flags & 0xF) << 52) |
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((uint64_t)(base >> 24 & 0xFF)<< 56);
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}
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static void KiGdtSetTss(int idx, uintptr_t base, uint32_t limit) {
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// TSS descriptor is 16 bytes (two GDT slots).
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gGdt[idx] = 0;
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gGdt[idx+1] = 0;
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gGdt[idx] =
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((uint64_t)(limit & 0xFFFF)) |
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((uint64_t)(base & 0xFFFFFF) << 16) |
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(0x89ULL << 40) | // P=1,DPL=0,type=TSS64 avail
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((uint64_t)((limit>>16)&0xF) << 48) |
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((uint64_t)(base>>24 & 0xFF) << 56);
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gGdt[idx+1] = (base >> 32);
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}
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TSS64 gTssStruct;
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TSS64* gTss = &gTssStruct;
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void KeInitializeGdt(void) {
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memset(gGdt, 0, sizeof(gGdt));
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memset(&gTssStruct, 0, sizeof(gTssStruct));
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// 0x00: Null
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KiGdtSetEntry(0, 0, 0, 0, 0);
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// 0x08: Ring-0 Code (Access 0x9A, Flags 0xA for 64-bit)
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KiGdtSetEntry(1, 0, 0xFFFFF, 0x9A, 0xA);
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// 0x10: Ring-0 Data
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KiGdtSetEntry(2, 0, 0xFFFFF, 0x92, 0xC);
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// 0x18: Ring-3 Code
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KiGdtSetEntry(3, 0, 0xFFFFF, 0xFA, 0xA);
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// 0x20: Ring-3 Data
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KiGdtSetEntry(4, 0, 0xFFFFF, 0xF2, 0xC);
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// 0x28: TSS (Occupies two slots: 0x28 and 0x30)
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gTssStruct.IoMapBase = sizeof(TSS64);
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gTssStruct.RSP0 = (uint64_t)(gKernelStack + KERNEL_IST_STACK_SIZE); // top of stack
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KiGdtSetTss(5, (uintptr_t)&gTssStruct, sizeof(TSS64) - 1);
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GDTR gdtr = { sizeof(gGdt) - 1, (uint64_t)gGdt };
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// Call the MASM64 proc to reload everything
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// Selectors: CS=0x08, Data=0x10, TSS=0x28
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KeFlushGdt(&gdtr, 0x08, 0x10, 0x28);
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}
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// ---------------------------------------------------------------------------
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// IDT
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// ---------------------------------------------------------------------------
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#define IDT_ENTRIES 256
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#pragma pack(push, 1)
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typedef struct {
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uint16_t OffsetLow;
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uint16_t Selector;
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uint8_t Ist;
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uint8_t TypeAttr;
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uint16_t OffsetMid;
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uint32_t OffsetHigh;
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uint32_t Reserved;
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} IDT_ENTRY;
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#pragma pack(pop)
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static IDT_ENTRY gIdt[IDT_ENTRIES];
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#pragma pack(push, 1)
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typedef struct { uint16_t Limit; uint64_t Base; } IDTR;
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#pragma pack(pop)
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static void KiIdtSetGate(int vec, uintptr_t handler,
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uint8_t typeAttr, uint8_t ist) {
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gIdt[vec].OffsetLow = (uint16_t)(handler & 0xFFFF);
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gIdt[vec].Selector = 0x08; // ring-0 code segment
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gIdt[vec].Ist = ist;
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gIdt[vec].TypeAttr = typeAttr;
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gIdt[vec].OffsetMid = (uint16_t)((handler >> 16) & 0xFFFF);
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gIdt[vec].OffsetHigh = (uint32_t)((handler >> 32) & 0xFFFFFFFF);
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gIdt[vec].Reserved = 0;
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}
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void KeInitializeIdt(void) {
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memset(gIdt, 0, sizeof(gIdt));
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static void* faultStubs[32] = {
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(void*)KeFaultDE, (void*)KeFaultDB, (void*)KeFaultNMI,
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(void*)KeFaultBP, (void*)KeFaultOF, (void*)KeFaultBR,
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(void*)KeFaultUD, (void*)KeFaultNM, (void*)KeFaultDF,
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(void*)KeFaultCSO, (void*)KeFaultTS, (void*)KeFaultNP,
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(void*)KeFaultSS, (void*)KeFaultGP, (void*)KeFaultPF,
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(void*)KeFaultRSV15, (void*)KeFaultMF, (void*)KeFaultAC,
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(void*)KeFaultMC, (void*)KeFaultXM, (void*)KeFaultVE,
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(void*)KeFaultCP, (void*)KeFaultRSV22, (void*)KeFaultRSV23,
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(void*)KeFaultRSV24, (void*)KeFaultRSV25, (void*)KeFaultRSV26,
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(void*)KeFaultRSV27, (void*)KeFaultHV, (void*)KeFaultVC,
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(void*)KeFaultSX, (void*)KeFaultRSV31,
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};
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for (int i = 0; i < 32; i++)
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KiIdtSetGate(i, (uintptr_t)faultStubs[i], 0x8E, 0);
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KiIdtSetGate(0x40, (uintptr_t)KeSyscallEntry, 0xEE, 0);
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static void *irqStubs[NUM_IRQS] = {
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(void*)KeIrqStub0, (void*)KeIrqStub1, (void*)KeIrqStub2,
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(void*)KeIrqStub3, (void*)KeIrqStub4, (void*)KeIrqStub5,
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(void*)KeIrqStub6, (void*)KeIrqStub7, (void*)KeIrqStub8,
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(void*)KeIrqStub9, (void*)KeIrqStub10, (void*)KeIrqStub11,
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(void*)KeIrqStub12, (void*)KeIrqStub13, (void*)KeIrqStub14,
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(void*)KeIrqStub15, (void*)KeIrqStub16, (void*)KeIrqStub17,
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(void*)KeIrqStub18, (void*)KeIrqStub19, (void*)KeIrqStub20,
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(void*)KeIrqStub21, (void*)KeIrqStub22, (void*)KeIrqStub23,
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};
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for (int i = 0; i < NUM_IRQS; i++)
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KiIdtSetGate(0x20 + i, (uintptr_t)irqStubs[i], 0x8E, 0);
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IDTR idtr = { sizeof(gIdt) - 1, (uint64_t)gIdt };
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// Call the MASM64 proc to load IDT
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KeFlushIdt(&idtr);
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}
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