99 lines
2.1 KiB
C
99 lines
2.1 KiB
C
#ifndef GDT_H
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#define GDT_H
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#include <stdint.h>
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extern void* stack_top;
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//! set access bit
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#define I86_GDT_DESC_ACCESS 0x0001 //00000001
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//! descriptor is readable and writable. default: read only
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#define I86_GDT_DESC_READWRITE 0x0002 //00000010
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//! set expansion direction bit
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#define I86_GDT_DESC_EXPANSION 0x0004 //00000100
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//! executable code segment. Default: data segment
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#define I86_GDT_DESC_EXEC_CODE 0x0008 //00001000
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//! set code or data descriptor. defult: system defined descriptor
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#define I86_GDT_DESC_CODEDATA 0x0010 //00010000
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//! set dpl bits
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#define I86_GDT_DESC_DPL 0x0060 //01100000
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//! set "in memory" bit
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#define I86_GDT_DESC_MEMORY 0x0080 //10000000
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/** gdt descriptor grandularity bit flags ***/
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//! masks out limitHi (High 4 bits of limit)
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#define I86_GDT_GRAND_LIMITHI_MASK 0x0f //00001111
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//! set os defined bit
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#define I86_GDT_GRAND_OS 0x10 //00010000
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//! set if 32bit. default: 16 bit
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#define I86_GDT_GRAND_32BIT 0x40 //01000000
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//! 4k grandularity. default: none
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#define I86_GDT_GRAND_4K 0x80 //10000000
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typedef struct gdt_entry_t Gdt_entry;
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struct gdt_entry_t
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{
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uint16_t limit_low;
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uint16_t base_low;
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uint8_t base_middle;
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uint8_t access;
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uint8_t granularity;
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uint8_t base_high;
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} __attribute__((packed));
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typedef struct gdt_ptr_t Gdt_ptr;
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struct gdt_ptr_t
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{
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uint16_t limit;
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uint32_t base;
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} __attribute__((packed));
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static void gdt_set_gate(uint8_t num, uint32_t base, uint32_t limit, uint8_t access, uint8_t granularity);
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void gdt_install();
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void set_kernel_stack(uint32_t stack);
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typedef struct tss_entry_t Tss_entry;
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struct tss_entry_t
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{
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uint32_t prevTss;
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uint32_t esp0;
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uint32_t ss0;
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uint32_t esp1;
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uint32_t ss1;
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uint32_t esp2;
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uint32_t ss2;
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uint32_t cr3;
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uint32_t eip;
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uint32_t eflags;
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uint32_t eax;
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uint32_t ecx;
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uint32_t edx;
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uint32_t ebx;
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uint32_t esp;
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uint32_t ebp;
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uint32_t esi;
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uint32_t edi;
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uint32_t es;
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uint32_t cs;
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uint32_t ss;
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uint32_t ds;
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uint32_t fs;
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uint32_t gs;
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uint32_t ldt;
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uint16_t trap;
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uint16_t iomap;
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uint16_t iopb_off;
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} __attribute__((packed));
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#endif |