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#include <types.h>
#include <paging.h>
#include <panic.h>
#include <heap.h>
#include <libk/serial_stdio.h>
#include <libk/stdio.h>
#include <libk/string.h>
#include <kernel_vma.h>
uint64_t __attribute__((aligned(4096))) page_table_lvl4[512];
uint64_t __attribute__((aligned(4096))) page_table_lvl3[512];
uint64_t __attribute__((aligned(4096))) page_table_lvl2[512];
void map_addr(uint64_t virt, uint64_t phys, uint32_t flags)
{
virt -= virt % PAGE_SIZE;
phys -= phys % PAGE_SIZE;
// 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
uint64_t* pt_lvl3 = (uint64_t*)(page_table_lvl4[pt_lvl4_i] + KERNEL_VMA);
if (!((uint64_t)pt_lvl3 & FLAG_PRESENT)) {
pt_lvl3 = (uint64_t*)kalloc(4096);
memset(pt_lvl3, 0, 4096);
page_table_lvl4[pt_lvl4_i] = ((uint64_t)pt_lvl3 - KERNEL_VMA) | flags;
} else {
pt_lvl3 = (uint64_t*)((uint64_t)pt_lvl3 - (uint64_t)pt_lvl3 % 4096);
}
uint64_t* pt_lvl2 = (uint64_t*)(pt_lvl3[pt_lvl3_i] + KERNEL_VMA);
if (!((uint64_t)pt_lvl2 & FLAG_PRESENT)) {
pt_lvl2 = (uint64_t*)kalloc(4096);
memset(pt_lvl2, 0, 4096);
pt_lvl3[pt_lvl3_i] = ((uint64_t)pt_lvl2 - KERNEL_VMA) | flags;
} else {
pt_lvl2 = (uint64_t*)((uint64_t)pt_lvl2 - (uint64_t)pt_lvl2 % 4096);
}
pt_lvl2[pt_lvl2_i] = phys | flags | FLAG_HUGE;
}
void init_paging(void)
{
page_table_lvl4[511] = (uint64_t)page_table_lvl3 - KERNEL_VMA + (FLAG_PRESENT | FLAG_WRITABLE | FLAG_USER);
page_table_lvl3[510] = (uint64_t)page_table_lvl2 - KERNEL_VMA + (FLAG_PRESENT | FLAG_WRITABLE | FLAG_USER);
// 16mb kernel + 32mb heap + 2mb (32kb stack * 64 threads) = first 50mb
for (size_t i = 0; i < 25; i++) {
page_table_lvl2[i] = (uint64_t)0x0 + PAGE_SIZE * i + (FLAG_PRESENT | FLAG_WRITABLE | FLAG_USER | 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");
printf("address: 0x%x, error code: 0x%x\n", addr, error);
if (error == 7) {
panic("Accessing privileged page in usermode\n");
}
map_addr(addr, addr, FLAG_PRESENT | FLAG_WRITABLE | FLAG_USER);
}
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