79 lines
1.9 KiB
C
79 lines
1.9 KiB
C
#include <paging.h>
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
|
|
uint32_t page_dir[1024] __attribute__((aligned(4096)));
|
|
uint32_t page_table[1024] __attribute__((aligned(4096)));
|
|
|
|
void page_fault(registers_t regs) {
|
|
uint32_t faulting_address;
|
|
__asm__ volatile("mov %%cr2, %0" : "=r" (faulting_address));
|
|
|
|
// The error code gives us details of what happened.
|
|
int present = !(regs.err_code & 0x1); // Page not present
|
|
int rw = regs.err_code & 0x2; // Write operation?
|
|
int us = regs.err_code & 0x4; // Processor was in user-mode?
|
|
int reserved = regs.err_code & 0x8; // Overwritten CPU-reserved bits of page entry?
|
|
//int id = regs.err_code & 0x10; // Caused by an instruction fetch?
|
|
|
|
kprintf("Page fault: ( ");
|
|
if (present) {kprintf("present ");}
|
|
if (rw) {kprintf("read-only ");}
|
|
if (us) {kprintf("user-mode ");}
|
|
if (reserved) {kprintf("reserved ");}
|
|
kprintf(") at 0x%x\n", faulting_address);
|
|
kprintf("PAGE FAULT\n");
|
|
}
|
|
|
|
void load_directory(uint32_t *dir) {
|
|
__asm__ volatile("mov %0, %%cr3":: "r"(dir));
|
|
}
|
|
|
|
void enable_paging() {
|
|
uint32_t cr0;
|
|
__asm__ volatile("mov %%cr0, %0": "=r"(cr0));
|
|
cr0 |= 0x80000001; // Enable paging!
|
|
__asm__ volatile("mov %0, %%cr0":: "r"(cr0));
|
|
}
|
|
|
|
extern uint32_t endkernel;
|
|
|
|
page_t *next_page;
|
|
page_t *free_pages = 0;
|
|
|
|
page_t *kalloc_frame(){
|
|
page_t *temp;
|
|
if (free_pages == 0) {
|
|
temp = next_page;
|
|
next_page += PAGE_SIZE;
|
|
} else {
|
|
temp = free_pages;
|
|
free_pages = free_pages->next;
|
|
}
|
|
return temp;
|
|
}
|
|
|
|
void kfree_frame(page_t *page) {
|
|
page->next = free_pages;
|
|
free_pages = page;
|
|
}
|
|
|
|
void paging_init() {
|
|
unsigned int i;
|
|
for(i = 0; i < 1024; i++) {
|
|
page_dir[i] = 0x00000002;
|
|
}
|
|
|
|
next_page = (page_t*)endkernel;
|
|
|
|
for(i = 0; i < 1024; i++) {
|
|
page_table[i] = (i * 0x1000) | 3;
|
|
}
|
|
|
|
page_dir[0] = ((unsigned int)page_table) | 3;
|
|
|
|
register_interrupt_handler(14, &page_fault);
|
|
load_directory(page_dir);
|
|
enable_paging();
|
|
}
|