metalsvm/arch/x86/include/asm/idt.h
2011-08-02 15:58:20 +02:00

130 lines
3.8 KiB
C

/*
* Copyright 2010 Stefan Lankes, Chair for Operating Systems,
* RWTH Aachen University
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* This file is part of MetalSVM.
*/
/**
* @author Stefan Lankes
* @file arch/x86/include/asm/idt.h
* @brief Definition of IDT flags and functions to set interrupts
*
* This file contains define-constants for interrupt flags
* and installer functions for interrupt gates.\n
* See idt.c for structure definitions.
*/
#ifndef __ARCH_IDT_H__
#define __ARCH_IDT_H__
#include <metalsvm/stddef.h>
/// This bit shall be set to 0 if the IDT slot is empty
#define IDT_FLAG_PRESENT 0x80
/// Interrupt can be called from within RING0
#define IDT_FLAG_RING0 0x00
/// Interrupt can be called from within RING1 and lower
#define IDT_FLAG_RING1 0x20
/// Interrupt can be called from within RING2 and lower
#define IDT_FLAG_RING2 0x40
/// Interrupt can be called from within RING3 and lower
#define IDT_FLAG_RING3 0x60
/// Size of gate is 16 bit
#define IDT_FLAG_16BIT 0x00
/// Size of gate is 32 bit
#define IDT_FLAG_32BIT 0x08
/// The entry describes an interrupt gate
#define IDT_FLAG_INTTRAP 0x06
/// The entry describes a trap gate
#define IDT_FLAG_TRAPGATE 0x07
/// The entry describes a task gate
#define IDT_FLAG_TASKGATE 0x05
/*
* This is not IDT-flag related. It's the segment selectors for kernel code and data.
*/
#define KERNEL_CODE_SELECTOR 0x08
#define KERNEL_DATA_SELECTOR 0x10
#ifdef __cplusplus
extern "C" {
#endif
/** @brief Defines an IDT entry
*
* This structure defines interrupt descriptor table entries.\n
* They consist of the handling function's base address, some flags
* and a segment selector.
*/
typedef struct {
/// Handler function's lower 16 address bits
unsigned short base_lo;
/// Handler function's segment selector.
unsigned short sel;
/// These bits are reserved by Intel
unsigned char always0;
/// These 8 bits contain flags. Exact use depends on the type of interrupt gate.
unsigned char flags;
/// Higher 16 bits of handler function's base address
unsigned short base_hi;
} __attribute__ ((packed)) idt_entry_t;
/** @brief Defines the idt pointer structure.
*
* This structure keeps information about
* base address and size of the interrupt descriptor table.
*/
typedef struct {
/// Size of the IDT in bytes (not the number of entries!)
unsigned short limit;
/// Base address of the IDT
unsigned int base;
} __attribute__ ((packed)) idt_ptr_t;
/** @brief Installs IDT
*
* The installation involves the following steps:
* - Set up the IDT pointer
* - Set up int 0x80 for syscalls
* - process idt_load()
*/
void idt_install(void);
/** @brief Set an entry in the IDT
*
* @param num index in the IDT
* @param base base-address of the handler function being installed
* @param sel Segment the IDT will use
* @param flags Flags this entry will have
*/
void idt_set_gate(unsigned char num, size_t base, unsigned short sel,
unsigned char flags);
/** @brief Configures and returns a IDT entry with chosen attributes
*
* Just feed this function with base, selector and the flags
* you have seen in idt.h
*
* @return a preconfigured idt descriptor
*/
idt_entry_t configure_idt_entry(size_t base, unsigned short sel,
unsigned char flags);
#ifdef __cplusplus
}
#endif
#endif