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paging.c
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paging.c
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#include "buddy_allocator.h"
#include "paging.h"
#include "mmap.h"
#include "memory.h"
#include "boot_allocator.h"
#include "print.h"
#include "strings.h"
#include "list.h"
#include "process.h"
#define TWO_GB (0x80000000)
static paging_map_region AFTER_HOLE = {
.phys_start = 0,
.virt_start = VA(0)
};
static paging_map_region KERNEL_HIGH = {
.phys_start = 0,
.virt_start = KERNEL_VIRT(0),
.len = TWO_GB
};
static pte_t * pml4;
static inline pte_t * __pml4e(pte_t * pml4, virt_t addr) {
return pml4 + pml4_i(addr);
}
static inline pte_t * __pdpte(pte_t * pml4, virt_t addr) {
return pte_level_addr(*__pml4e(pml4, addr)) + pml3_i(addr);
}
static inline pte_t * __pde(pte_t * pml4, virt_t addr) {
return pte_level_addr(*__pdpte(pml4, addr)) + pml2_i(addr);
}
#define BOOT_ALLOC 0
#define BUDDY_ALLOC 1
static int mode = BOOT_ALLOC;
static void rewrite_addr_with_flags(pte_t * addr, phys_t phys, int page_flags){
*addr = phys | page_flags;
}
static void rewrite_entry(pte_t * addr, int page_flags){
void * new_page_addr;
if(mode == BOOT_ALLOC) {
new_page_addr = boot_allocator_alloc(PAGE_SIZE, PAGE_SIZE);
} else {
new_page_addr = buddy_allocate_page(0);
}
memset(new_page_addr, 0, PAGE_SIZE);
rewrite_addr_with_flags(addr, pa(new_page_addr), page_flags);
}
static void add_map_entry(pte_t * pml4, phys_t paddr, virt_t virtaddr, int flags){
pte_t * pml4e = __pml4e(pml4, virtaddr);
if(!pte_present(*pml4e)){
rewrite_entry(pml4e, (PTE_PRESENT | flags) & (~PTE_LARGE) );
}
pte_t * pdpte = __pdpte(pml4, virtaddr);
if(!pte_present(*pdpte)){
rewrite_entry(pdpte, (PTE_PRESENT | flags) & (~PTE_LARGE));
}
pte_t * pde = __pde(pml4, virtaddr);
rewrite_addr_with_flags(pde, paddr, PTE_PRESENT | flags | PTE_LARGE);
}
static void remove_map_entry(virt_t virtaddr){
pte_t * pml4e = __pml4e(pml4, virtaddr);
if(!pte_present(*pml4e)){
return;
}
pte_t * pdpte = __pdpte(pml4, virtaddr);
if(!pte_present(*pdpte)){
return;
}
pte_t * pde = __pde(pml4, virtaddr);
*pde = 0;
}
static void recalculate_map_region_lens(){
AFTER_HOLE.len = mmap_get_high_memory_level();
}
static uint64_t paging_get_region_mem(paging_map_region * region){
return (region->len / PAGE_SIZE_2M + 1) * PAGE_SIZE * 2;
}
static void __paging_mmap_region(pte_t * pml4, paging_map_region * region, int flags){
for(phys_t i = region->phys_start;
i < region->phys_start + region->len;
i += PAGE_SIZE_2M){
add_map_entry(pml4, i, region->virt_start + (i - region->phys_start), flags);
}
}
static void __paging_ummap_region(paging_map_region * region) {
for(phys_t i = region->phys_start;
i < region->phys_start + region->len;
i += PAGE_SIZE_2M){
remove_map_entry(region->virt_start + (i - region->phys_start));
}
}
void paging_mmap_region(paging_map_region * region, int flags){
__paging_mmap_region(pml4, region, flags);
store_pml4(pa(pml4));
}
void paging_ummap_region(paging_map_region * region) {
__paging_ummap_region(region);
store_pml4(pa(pml4));
}
uint64_t paging_get_component_size(){
recalculate_map_region_lens();
return paging_get_region_mem(&AFTER_HOLE) +
paging_get_region_mem(&KERNEL_HIGH) + PAGE_SIZE;
}
void paging_ummap_region_defaut_holem(paging_map_region * region){
paging_map_region new_region = {
.phys_start = PA(region->virt_start),
.virt_start = region->virt_start,
.len = region->len
};
paging_mmap_region(&new_region, PTE_WRITE);
}
void paging_init(){
recalculate_map_region_lens();
pml4 = boot_allocator_alloc(PAGE_SIZE, PAGE_SIZE);
memset(pml4, 0, PAGE_SIZE);
__paging_mmap_region(pml4, &AFTER_HOLE, PTE_WRITE);
__paging_mmap_region(pml4, &KERNEL_HIGH, PTE_WRITE);
store_pml4(pa(pml4));
mode = BUDDY_ALLOC;
}
pte_t * paging_create_newpml_from_process_mm_list(struct list_head *head) {
pte_t * new_pml4 = boot_allocator_alloc(PAGE_SIZE, PAGE_SIZE);
memset(new_pml4, 0, PAGE_SIZE);
__paging_mmap_region(new_pml4, &AFTER_HOLE, PTE_WRITE);
__paging_mmap_region(new_pml4, &KERNEL_HIGH, PTE_WRITE);
LIST_FOR_EACH(ptr, head) {
p_mm_entry * entry = LIST_ENTRY(ptr, p_mm_entry, list);
__paging_mmap_region(new_pml4, &entry->region, PTE_WRITE | PTE_USER);
}
return new_pml4;
}