idt.h

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#ifndef _CPU_IDT_H
#define _CPU_IDT_H
 
#include <stdint.h>
 
// Flags (strikingly similar to GDT)
#define IDT_PRESENT  0x80
#define IDT_RING_0   0x00
#define IDT_RING_1   0x20
#define IDT_RING_2   0x40
#define IDT_RING_3   0x60
#define IDT_INT_GATE 0x0E
#define IDT_TRAP_GATE 0x0F
 
#define IDT_KTRAP_GATE (IDT_PRESENT + IDT_RING_0 + IDT_TRAP_GATE)
#define IDT_KINT_GATE (IDT_PRESENT + IDT_RING_0 + IDT_INT_GATE)
 
#define IDT_ENTRY_CREATE(addr, selector, ist, flags) {     \
        (addr)       & 0xffff, /* 16-bit address (low)  */ \
        (selector)   & 0xffff, /* 16-bit Code Selector  */ \
        (ist)        & 0xff,   /* Interrupt Stack Table */ \
        (flags)      & 0xff,   /* Flags (one byte)      */ \
        (addr) >> 16 & 0xffff, /* Second two low bytes  */ \
        (addr) >> 32,          /* Four high bytes       */ \
        0,                     /* Reserved (four bytes) */ \
}
 
// A IDT is necessary to handle interrupts
struct cpu_idt_entry {
        uint16_t address_low;
        uint16_t selector;
        uint8_t  ist;
        uint8_t  flags;
        uint16_t address_mid;
        uint32_t address_high;
        uint32_t reserved;
} __attribute__((packed));
 
// Represents the contents of the IDTR in memory
struct cpu_idt_register {
        uint16_t limit;
        uint64_t base;
} __attribute__((packed));
 
// The data structure placed on the stack
// by the CPU when an ISR is invoked
struct cpu_idt_iframe {
        uint64_t rip;
        uint64_t cs;
        uint64_t rflags;
        uint64_t rsp;
        uint64_t ss;
};
 
// Represents the state of the CPU following an interrupt
struct cpu_idt_interrupt_state {
        uint64_t r15;
        uint64_t r14;
        uint64_t r13;
        uint64_t r12;
        uint64_t r11;
        uint64_t r10;
        uint64_t  r9;
        uint64_t  r8;
        uint64_t rsi;
        uint64_t rdi;
        uint64_t rdx;
        uint64_t rcx;
        uint64_t rbx;
        uint64_t rax;
        uint64_t vector;
        uint64_t error_code;
        struct cpu_idt_iframe iframe;
};
 
 
// Advertise the kernel's idt to the CPU
void cpu_idt_bind(void);
// Describe the currently loaded IDT.
void cpu_idt_describe(char *buf, uint64_t bufsz);
 
static inline void enable_interrupts() {
        asm("sti");
}
 
static inline void disable_interrupts() {
        asm("cli");
}
 
#endif