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Added sequence to remap PIC

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Wrote GDT code in C
Added routines to initialize GDT and IDT
This commit is contained in:
ngiddings
2021-04-16 01:45:40 -05:00
parent 8e6589b472
commit 6138766c49
7 changed files with 223 additions and 74 deletions
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178
src/x86/interrupts.c
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@@ -1,14 +1,85 @@
#include "interrupts.h"
#include "isr.h"
#include "string.h"
#include <stddef.h>
struct idt_info_t
#define idt_size 256
#define gdt_size 6
enum segment_type_t
{
SEGMENT_KERNEL_CODE,
SEGMENT_KERNEL_DATA,
SEGMENT_USER_CODE,
SEGMENT_USER_DATA,
SEGMENT_TSS
};
struct gdt_entry_t
{
unsigned int limit_low : 16;
unsigned int base_low : 24;
unsigned int accessed : 1;
unsigned int read_write : 1;
unsigned int conforming_expand_down : 1;
unsigned int code : 1;
unsigned int code_data_segment : 1;
unsigned int dpl : 2;
unsigned int present : 1;
unsigned int limit_high : 4;
unsigned int available : 1;
unsigned int long_mode : 1;
unsigned int big : 1;
unsigned int gran : 1;
unsigned int base_high : 8;
} __attribute__ ((packed));
struct tss_t
{
};
struct interrupt_descriptor_t
{
uint16_t offset_1;
uint16_t selector;
uint16_t zero : 8;
uint16_t type : 4;
uint16_t storage : 1;
uint16_t dpl : 2;
uint16_t present : 1;
uint16_t offset_2;
};
struct descriptor_table_info_t
{
uint16_t size;
void *location;
} __attribute__ ((packed));
void lidt(struct interrupt_descriptor_t *idt)
struct tss_t tss;
void load_gdt(struct gdt_entry_t *gdt)
{
struct idt_info_t idt_info;
struct descriptor_table_info_t gdt_info;
gdt_info.size = sizeof(struct gdt_entry_t) * 6 - 1;
gdt_info.location = (void *)gdt;
asm("lgdt (%0);"
"jmp $8, $.ldcs;"
".ldcs:;"
"mov $16, %%ax;"
"mov %%ax, %%ds;"
"mov %%ax, %%es;"
"mov %%ax, %%gs;"
"mov %%ax, %%fs;"
"mov %%ax, %%ss;"
:
: "r"(&gdt_info));
}
void load_idt(struct interrupt_descriptor_t *idt)
{
struct descriptor_table_info_t idt_info;
idt_info.size = sizeof(struct interrupt_descriptor_t) * 256 - 1;
idt_info.location = (void *)idt;
asm("lidt (%0)"
@@ -27,3 +98,104 @@ void create_interrupt_descriptor(struct interrupt_descriptor_t *descriptor, void
descriptor->dpl = privilage;
descriptor->present = 1;
}
void create_segment_descriptor(struct gdt_entry_t *descriptor, size_t base, size_t limit, enum segment_type_t type)
{
descriptor->limit_low = limit;
descriptor->limit_high = (limit & (0xf << 16)) >> 16;
descriptor->base_low = base;
descriptor->base_high = (base & (0xff << 24)) >> 24;
descriptor->present = 1;
switch(type)
{
case SEGMENT_KERNEL_CODE:
descriptor->accessed = 0;
descriptor->read_write = 1;
descriptor->conforming_expand_down = 0;
descriptor->code = 1;
descriptor->code_data_segment = 1;
descriptor->dpl = 0;
descriptor->available = 0;
descriptor->long_mode = 0;
descriptor->big = 1;
descriptor->gran = 1;
break;
case SEGMENT_KERNEL_DATA:
descriptor->accessed = 0;
descriptor->read_write = 1;
descriptor->conforming_expand_down = 0;
descriptor->code = 0;
descriptor->code_data_segment = 1;
descriptor->dpl = 0;
descriptor->available = 0;
descriptor->long_mode = 0;
descriptor->big = 1;
descriptor->gran = 1;
break;
case SEGMENT_USER_CODE:
descriptor->accessed = 0;
descriptor->read_write = 1;
descriptor->conforming_expand_down = 0;
descriptor->code = 1;
descriptor->code_data_segment = 1;
descriptor->dpl = 3;
descriptor->available = 0;
descriptor->long_mode = 0;
descriptor->big = 1;
descriptor->gran = 1;
break;
case SEGMENT_USER_DATA:
descriptor->accessed = 0;
descriptor->read_write = 1;
descriptor->conforming_expand_down = 0;
descriptor->code = 0;
descriptor->code_data_segment = 1;
descriptor->dpl = 3;
descriptor->available = 0;
descriptor->long_mode = 0;
descriptor->big = 1;
descriptor->gran = 1;
break;
case SEGMENT_TSS:
descriptor->accessed = 1;
descriptor->read_write = 0;
descriptor->conforming_expand_down = 0;
descriptor->code = 1;
descriptor->code_data_segment = 0;
descriptor->dpl = 3;
descriptor->available = 0;
descriptor->long_mode = 0;
descriptor->big = 0;
descriptor->gran = 0;
}
}
void initialize_gdt()
{
static struct gdt_entry_t gdt[gdt_size];
memset(gdt, 0, sizeof(struct gdt_entry_t) * gdt_size);
create_segment_descriptor(&gdt[1], 0, 0xFFFFF, SEGMENT_KERNEL_CODE);
create_segment_descriptor(&gdt[2], 0, 0xFFFFF, SEGMENT_KERNEL_DATA);
create_segment_descriptor(&gdt[3], 0, 0xFFFFF, SEGMENT_USER_CODE);
create_segment_descriptor(&gdt[4], 0, 0xFFFFF, SEGMENT_USER_DATA);
//create_segment_descriptor(&gdt[5], (size_t)&tss, sizeof(struct tss_t), SEGMENT_TSS);
load_gdt(gdt);
}
void initialize_idt()
{
static struct interrupt_descriptor_t idt[idt_size];
memset(idt, 0, sizeof(struct interrupt_descriptor_t) * idt_size);
for(int i = 0; i < idt_size; i++)
{
create_interrupt_descriptor(&idt[i], (void*)isr_generic, INTERRPUT_INT32, 0);
}
create_interrupt_descriptor(&idt[EXCEPTION_DIV_BY_0], (void*)isr_division_by_zero, INTERRPUT_INT32, 0);
create_interrupt_descriptor(&idt[EXCEPTION_GPF], (void*)isr_gp_fault, INTERRPUT_INT32, 0);
create_interrupt_descriptor(&idt[EXCEPTION_PAGE_FAULT], (void*)isr_page_fault, INTERRPUT_INT32, 0);
create_interrupt_descriptor(&idt[EXCEPTION_DOUBLE_FAULT], (void*)isr_double_fault, INTERRPUT_INT32, 0);
create_interrupt_descriptor(&idt[ISR_APIC_TIMER], (void*)isr_timer, INTERRPUT_INT32, 0);
create_interrupt_descriptor(&idt[ISR_AP_START], (void*)isr_ap_start, INTERRPUT_INT32, 0);
create_interrupt_descriptor(&idt[ISR_SYSCALL], (void*)isr_syscall, INTERRPUT_INT32, 0);
load_idt(idt);
}