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x86: Initialize Interrupt Descriptor Table

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This patch adds code to handle Interrupt Descriptor Table (IDT)
initialization. The IDT is initialized with null descriptors
therefore any interrupt at this point will cause a triple fault.
The IDT initialization is part of x86 CPU initialization.

Strictly speaking, there is no need to use attribute packed in struct
intr_gate_desc however we use it for readability reasons.
This commit is contained in:
Andre Guedes 2015-04-15 15:03:51 -03:00 committed by Jesus Sanchez-Palencia
parent b8feaea30d
commit 13d92cf67a
3 changed files with 129 additions and 1 deletions
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2
cpu/x86/Makefile.x86
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@ -1,6 +1,6 @@
CONTIKI_CPU_DIRS = .
CONTIKI_SOURCEFILES += mtarch.c gdt.c helpers.S
CONTIKI_SOURCEFILES += mtarch.c gdt.c helpers.S idt.c
### Compiler definitions
CC = gcc

89
cpu/x86/idt.c Normal file
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/*
* Copyright (C) 2015, Intel Corporation. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* 3. Neither the name of the copyright holder nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <stdint.h>
#include "helpers.h"
#define NUM_DESC 256
typedef struct idtr {
uint16_t limit;
uint32_t base;
} __attribute__((packed)) idtr_t;
typedef struct intr_gate_desc {
uint16_t offset_low;
uint16_t selector; /* Segment Selector for destination code segment */
uint16_t fixed:11;
uint16_t d:1; /* Size of gate: 1 = 32 bits; 0 = 16 bits */
uint16_t pad:1;
uint16_t dpl:2; /* Descriptor Privilege Level */
uint16_t p:1; /* Segment Present flag */
uint16_t offset_high;
} __attribute__((packed)) intr_gate_desc_t;
/* According to Intel Combined Manual, Vol. 3, Section 6.10, the base addresses
* of the IDT should be aligned on an 8-byte boundary to maximize performance
* of cache line fills.
*/
static intr_gate_desc_t idt[NUM_DESC] __attribute__ ((aligned(8)));
void
idt_set_intr_gate_desc(int intr_num, uint32_t offset)
{
intr_gate_desc_t *desc = &idt[intr_num];
desc->offset_low = offset & 0xFFFF;
desc->selector = 0x08; /* Offset in GDT for code segment */
desc->fixed = BIT(9) | BIT(10);
desc->d = 1;
desc->dpl = 0;
desc->p = 1;
desc->offset_high = (offset >> 16) & 0xFFFF;
}
/*---------------------------------------------------------------------------*/
/* Initialize Interrupt Descriptor Table. The IDT is initialized with
* null descriptors. Therefore, any interrupt at this point will cause
* a triple fault.
*/
void
idt_init(void)
{
idtr_t idtr;
/* Initialize idtr structure */
idtr.limit = (sizeof(intr_gate_desc_t) * NUM_DESC) - 1;
idtr.base = (uint32_t)&idt;
/* Load IDTR register */
__asm__("lidt %0\n\t" :: "m" (idtr));
}

39
cpu/x86/idt.h Normal file
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/*
* Copyright (C) 2015, Intel Corporation. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* 3. Neither the name of the copyright holder nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef IDT_H
#define IDT_H
#include <stdint.h>
void idt_init(void);
void idt_set_intr_gate_desc(int intr_num, uint32_t offset);
#endif /* IDT_H */