Rework x86_64 paging and vmm

kernel/hal/x86_64/vmm.h

@@ -0,0 +1,45 @@
+#ifndef HAL_VMM_H_
+#define HAL_VMM_H_
+
+#include <stdint.h>
+#include <stdbool.h>
+#include "compiler/attr.h"
+
+enum {
+  HAL_PG_PRESENT = 1<<0,
+  HAL_PG_RW      = 1<<1,
+  HAL_PG_USER    = 1<<2,
+};
+
+typedef struct {
+  uint64_t pml4;
+  uint64_t pml3;
+  uint64_t pml2;
+  uint64_t pml1;
+} PACKED PgIndex;
+
+typedef struct {
+  bool present: 1;
+  bool rw: 1;
+  bool user: 1;
+  bool writethrough: 1;
+  bool cachedisabled: 1;
+  bool accessed: 1;
+  bool zero0: 1;
+  bool size: 1;
+  bool zero1: 1;
+  uint8_t avail: 3;
+  uint64_t addr: 52;
+} PACKED Pte;
+
+typedef struct {
+  Pte ents[512];
+} PACKED PgTable;
+
+extern PgTable *KERNEL_CR3;
+
+void hal_vmm_init(void);
+void hal_vmm_unmap_page(PgTable *pml4, uint64_t virtaddr, uint64_t physaddr);
+void hal_vmm_map_page(PgTable *pml4, uint64_t virtaddr, uint64_t physaddr, uint32_t flags);
+
+#endif // HAL_VMM_H_