138 lines
4.6 KiB
C
138 lines
4.6 KiB
C
/*
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* Copyright (c) 2010, Stefan Lankes, RWTH Aachen University
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this
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* software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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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 <eduos/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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uint16_t base_lo;
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/// Handler function's segment selector.
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uint16_t sel;
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/// These bits are reserved by Intel
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uint8_t always0;
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/// These 8 bits contain flags. Exact use depends on the type of interrupt gate.
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uint8_t flags;
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/// Higher 16 bits of handler function's base address
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uint16_t 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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uint16_t limit;
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/// Base address of the IDT
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size_t 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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void configure_idt_entry(idt_entry_t *dest_entry, size_t base,
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unsigned short sel, 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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