paging

kernel/memory/mm.c

@@ -13,6 +13,8 @@ static uint32_t max_address = 0;
 static uint32_t total_available_memory = 0;
 static uint8_t memory_bitmap[BITMAP_SIZE];
 
+uint32_t* page_directory;
+
 static void mark_free(uint32_t addr) {
     uint32_t page_index = addr / PAGE_SIZE;
     uint32_t byte_index = page_index / 8;
@@ -111,4 +113,20 @@ void* alloc_page() {
 
 void free_page(void* addr) {
     mark_free((uint32_t)addr);
+}
+
+void init_paging() {
+    page_directory = alloc_page();
+    for (int i = 0; i < 1024; i++) {
+        page_directory[i] = 0x0; 
+    }
+
+    uint32_t* page_table = alloc_page();
+    page_directory[0] = (uint32_t)(page_table) | 0x3;
+    for (int i = 0; i < 1024; i++) {
+        page_table[i] = (i * PAGE_SIZE) | 0x3;
+    }
+
+    extern void load_page_directory(uint32_t* pd);
+    load_page_directory(page_directory);
 }

kernel/memory/mm.h

@@ -13,4 +13,7 @@ uint32_t total_free_memory();
 void* alloc_page();
 void free_page(void* addr);
 
-#endif 
+void init_paging();
+void enable_paging();
+
+#endif 

kernel/memory/mm_stubs.S

@@ -0,0 +1,21 @@
+.code32 
+.global load_page_directory
+load_page_directory: 
+    push %ebp 
+    mov %esp, %ebp 
+    
+    mov 8(%ebp), %eax
+    mov %eax, %cr3
+
+    leave 
+    ret
+
+.global enable_paging
+enable_paging:
+    mov %eax, %cr0
+    orl $0x80000000, %eax
+    mov %cr0, %eax
+    jmp 1f
+1:
+    ret
+