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