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#include <kernel/paging.h>
#include <kernel/asm.h>
#include <kernel/pmem.h>
#include <kernel/panic.h>
#include <kernel/syscall.h>
#include <libk/io.h>
#include <libk/string.h>
#include <libk/errno.h>
uintptr_t *kpgdir = NULL;
static uintptr_t kernel_pd[1024] __attribute__((aligned(PAGE_SIZE)));
static uintptr_t kernel_pt[1024] __attribute__((aligned(PAGE_SIZE)));
static uintptr_t accnt_pt[1024] __attribute__((aligned(PAGE_SIZE)));
static int paging_enabled = 0;
void _copy_kernel_maps(uintptr_t *new_pd) {
int pdx = GET_PDX(GET_VADDR(KSTART));
new_pd[pdx] = GET_PADDR(kernel_pt) | PD_PRES | PD_RW;
new_pd[832] = GET_PADDR(accnt_pt) | PD_PRES | PD_RW;
}
uintptr_t* init_page_table(void) {
uintptr_t *ret = (uintptr_t*)pfa_alloc();
if ((uintptr_t)ret == PFA_ALLOC_ERR)
return NULL;
map_page(NULL, (uintptr_t)ret, (uintptr_t)ret+0x20000000, PD_PRES | PD_RW);
memset((char*)ret, 0, PAGE_SIZE);
unmap_page(NULL, (uintptr_t)ret);
return ret;
}
uintptr_t* init_page_directory(void) {
uintptr_t *ret = (uintptr_t*)pfa_alloc();
if ((uintptr_t)ret == PFA_ALLOC_ERR)
return NULL;
map_page(NULL, (uintptr_t)ret, (uintptr_t)ret, PD_PRES | PD_RW);
memset(ret, 0, PAGE_SIZE);
_copy_kernel_maps(ret);
unmap_page(NULL, (uintptr_t)ret);
return ret;
}
void paging_init(void) {
if (paging_enabled == 1)
return;
_copy_kernel_maps(kernel_pd);
for (uintptr_t i = KSTART; i < KEND; i += PAGE_SIZE)
map_page(kernel_pd, i, GET_VADDR(i), PD_PRES);
map_page(kernel_pd, 0xB8000, 0xC03FF000, PD_PRES | PD_RW);
kpgdir = kernel_pd;
enable_paging(GET_PADDR(kpgdir));
paging_enabled = 1;
return;
}
void map_page(uint32_t *pd, uintptr_t paddr, uintptr_t vaddr, uint32_t flags) {
if (pd == NULL)
pd = kpgdir;
paddr = PGROUNDDN(paddr);
vaddr = PGROUNDDN(vaddr);
uintptr_t pdindex = GET_PDX(vaddr);
uintptr_t ptindex = GET_PTX(vaddr);
uintptr_t *pt = (uintptr_t*)(GET_VADDR(pd[pdindex]) & 0xFFFFF000);
if (pd[pdindex] == 0)
pd[pdindex] = (uintptr_t)init_page_table();
uintptr_t *pte = (uintptr_t*)(&pt[ptindex]);
*pte |= paddr | (flags & 0xFFF) | 0x01;
invlpg((void*)vaddr);
}
void unmap_page(uint32_t *pd, uintptr_t vaddr) {
if (pd == NULL)
pd = kpgdir;
uintptr_t pdindex = GET_PDX(vaddr);
uintptr_t ptindex = GET_PTX(vaddr);
uintptr_t *pt = (uintptr_t*)(GET_VADDR(pd[pdindex]) & 0xFFFFF000);
if (pd[pdindex] == 0)
return;
uintptr_t *pte = (uintptr_t*)(&pt[ptindex]);
*pte &= 0;
invlpg((void*)vaddr);
}
void page_fault_handler(struct isr_frame *frame) {
uintptr_t fault_addr;
__asm__ volatile("movl %%cr2, %0" : "=r"(fault_addr));
switch (frame->isr_err) {
case 0:
map_page((uintptr_t*)GET_VADDR(frame->cr3), pfa_alloc(), fault_addr, PD_PRES);
break;
case 1:
panic("Kernel process caused protection fault on read\n");
break;
case 2:
map_page((uintptr_t*)GET_VADDR(frame->cr3), pfa_alloc(), fault_addr, PD_PRES | PD_RW);
break;
case 3:
panic("Kernel process caused protection fault on write\n");
break;
case 4:
map_page((uintptr_t*)GET_VADDR(frame->cr3), pfa_alloc(), fault_addr, PD_PRES | PD_USR);
break;
case 5:
// TODO: instead of panicking, kill process
panic("User process caused protection fault on read\n");
break;
case 6:
map_page((uintptr_t*)GET_VADDR(frame->cr3), pfa_alloc(), fault_addr, PD_PRES | PD_RW | PD_USR);
break;
case 7:
// TODO: see case 101
panic("USER process caused protection fault on write\n");
break;
default:
kprintf("Unknown paging error occured on address %x\n", fault_addr);
panic("Paging error");
break;
}
}
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