idt.h

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/*******************************************************************************/
/*  © Université de Lille, The Pip Development Team (2015-2021)                */
/*                                                                             */
/*  This software is a computer program whose purpose is to run a minimal,     */
/*  hypervisor relying on proven properties such as memory isolation.          */
/*                                                                             */
/*  This software is governed by the CeCILL license under French law and       */
/*  abiding by the rules of distribution of free software.  You can  use,      */
/*  modify and/ or redistribute the software under the terms of the CeCILL     */
/*  license as circulated by CEA, CNRS and INRIA at the following URL          */
/*  "http://www.cecill.info".                                                  */
/*                                                                             */
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/*******************************************************************************/

#ifndef __IDT__
#define __IDT__

#include <stdint.h>

struct idt_int_trap_entry_s {
    unsigned offset_low  : 16; //<! Lower bits of handler address
    unsigned segment     : 16; //<! Segment selector
    unsigned rfu         :  5; //<! Reserved
    unsigned zero        :  3; //<! Always zero smh
    unsigned type        :  5; //<! TRAP_GATE_TYPE or INTERRUPT_GATE_TYPE
    unsigned dpl         :  2; //<! Descriptor Privilege Level
    unsigned present     :  1; //<! Present flag (validity)
    unsigned offset_high : 16; //<! Higher bits of handler address
};
typedef struct idt_int_trap_entry_s idt_trap_entry_t;
typedef struct idt_int_trap_entry_s idt_int_entry_t;


struct idt_task_entry_s {
    unsigned rfu0    : 16; //<! Reserved
    unsigned segment : 16; //<! TSS segment selector
    unsigned rfu1    :  8; //<! Reserved
    unsigned type    :  5; //<! TASK_GATE_TYPE
    unsigned dpl     :  2; //<! Descriptor Privilege Level
    unsigned present :  1; //<! Present flag (validity)
    unsigned rfu2    : 16; //<! Reserved
};
typedef struct idt_task_entry_s idt_task_entry_t;

union idt_entry_u {
    idt_int_entry_t  interrupt;
    idt_trap_entry_t trap;
    idt_task_entry_t task;
};
typedef union idt_entry_u idt_entry_t;

#define TASK_GATE_TYPE      0b00101
#define INTERRUPT_GATE_TYPE 0b01110
#define TRAP_GATE_TYPE      0b01111

struct idt_ptr_s
{
    uint16_t limit;     
    idt_entry_t *base;  
} __attribute__((packed));

typedef struct idt_ptr_s idt_ptr_t;

void idt_init(void);

#endif