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