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#include <types.h>
#include <paging.h>
#include <libk/stdio.h>
#include <debug.h>
void load_pt_lvl4(uint64_t*);
__attribute__((aligned(4096))) uint64_t page_table_lvl4[512];
__attribute__((aligned(4096))) uint64_t page_table_lvl3[512];
__attribute__((aligned(4096))) uint64_t page_table_lvl2_0[512];
__attribute__((aligned(4096))) uint64_t page_table_lvl2_1[512];
__attribute__((aligned(4096))) uint64_t page_table_lvl2_2[512];
__attribute__((aligned(4096))) uint64_t page_table_lvl2_3[512];
void map_addr(uint64_t virt, uint64_t phys, uint32_t flags)
{
virt -= virt % 0x00200000;
phys -= phys % 0x00200000;
// i is in range [0, 511]
size_t pt_lvl4_i = (virt >> 39) % 0x200; // 512gb entry
size_t pt_lvl3_i = (virt >> 30) % 0x200; // 1gb entry
size_t pt_lvl2_i = (virt >> 21) % 0x200; // 2mb entry
// size_t pt_lvl1_i = (virt >> 12) % 0x200; // 4kb entry
// first 4gb
if (pt_lvl4_i == 0) {
switch(pt_lvl3_i) {
case 0:
page_table_lvl2_0[pt_lvl2_i] = phys | flags;
break;
case 1:
page_table_lvl2_1[pt_lvl2_i] = phys | flags;
break;
case 2:
page_table_lvl2_2[pt_lvl2_i] = phys | flags;
break;
case 3:
page_table_lvl2_3[pt_lvl2_i] = phys | flags;
break;
}
}
}
void init_paging(void)
{
page_table_lvl4[0] = (uint64_t)page_table_lvl3 + FLAG_PRESENT + FLAG_WRITABLE - KERNEL_VMA;
page_table_lvl3[0] = (uint64_t)page_table_lvl2_0 + FLAG_PRESENT + FLAG_WRITABLE - KERNEL_VMA;
page_table_lvl3[1] = (uint64_t)page_table_lvl2_1 + FLAG_PRESENT + FLAG_WRITABLE - KERNEL_VMA;
page_table_lvl3[2] = (uint64_t)page_table_lvl2_2 + FLAG_PRESENT + FLAG_WRITABLE - KERNEL_VMA;
page_table_lvl3[3] = (uint64_t)page_table_lvl2_3 + FLAG_PRESENT + FLAG_WRITABLE - KERNEL_VMA;
// higher half map first 4mb
map_addr(KERNEL_VMA, 0x00000000, FLAG_PRESENT + FLAG_WRITABLE + FLAG_HUGE);
map_addr(KERNEL_VMA + PAGE_SIZE, 0x00000000 + PAGE_SIZE, FLAG_PRESENT + FLAG_WRITABLE + FLAG_HUGE);
load_pt_lvl4(page_table_lvl4);
}
void page_fault(uint64_t error)
{
uint64_t addr;
__asm__ volatile ("mov %%cr2, %0;" : "=r"(addr) : : "memory");
map_addr(addr, addr, FLAG_PRESENT | FLAG_WRITABLE | FLAG_HUGE);
printf("address: 0x%x, error code: %d\n", addr, error);
}
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