Rework x86_64 paging and vmm

kernel/hal/x86_64/vmm.c

@@ -0,0 +1,65 @@
+#include <stddef.h>
+#include <stdint.h>
+#include "vmm.h"
+#include "hal/hal.h"
+#include "bootinfo/bootinfo.h"
+#include "pmm/pmm.h"
+
+PgTable *KERNEL_CR3 = NULL;
+
+PgTable *hal_vmm_current_cr3(void) {
+  PgTable *cr3;
+  asm volatile("mov %%cr3, %0" : "=r"(cr3));
+  return cr3;
+}
+
+PgIndex hal_vmm_pageindex(uint64_t vaddr) {
+  PgIndex ret;
+
+  ret.pml4 = (vaddr & ((uint64_t)0x1ff < 39)) >> 39;
+  ret.pml3 = (vaddr & ((uint64_t)0x1ff < 30)) >> 30;
+  ret.pml2 = (vaddr & ((uint64_t)0x1ff < 21)) >> 21;
+  ret.pml1 = (vaddr & ((uint64_t)0x1ff < 12)) >> 12;
+
+  return ret;
+}
+
+uint64_t *hal_vmm_nexttable(uint64_t *table, uint64_t ent) {
+  uint8_t *addr;
+
+  if (table[ent] & HAL_PG_PRESENT) {
+    addr = (uint8_t *)(table[ent] & ~((uint64_t)0xfff));
+  } else {
+    addr = pmm_alloc(1);
+    hal_memset(BOOT_INFO.hhdm_off + addr, 0, HAL_PAGE_SIZE);
+    table[ent] = (uint64_t)addr | HAL_PG_USER | HAL_PG_RW | HAL_PG_PRESENT;
+  }
+
+  return (uint64_t *)(BOOT_INFO.hhdm_off + addr);
+}
+
+void hal_vmm_map_page(PgTable *pml4, uint64_t virtaddr, uint64_t physaddr, uint32_t flags) {
+  PgIndex pi = hal_vmm_pageindex(virtaddr);
+
+  uint64_t *pml3 = hal_vmm_nexttable((uint64_t *)pml4, pi.pml4);
+  uint64_t *pml2 = hal_vmm_nexttable((uint64_t *)pml3, pi.pml3);
+  uint64_t *pml1 = hal_vmm_nexttable((uint64_t *)pml2, pi.pml2);
+  uint64_t *pte = &pml1[pi.pml1];
+
+  *pte = physaddr | (flags & 0x7);
+}
+
+void hal_vmm_unmap_page(PgTable *pml4, uint64_t virtaddr, uint64_t physaddr) {
+  PgIndex pi = hal_vmm_pageindex(virtaddr);
+
+  uint64_t *pml3 = hal_vmm_nexttable((uint64_t *)pml4, pi.pml4);
+  uint64_t *pml2 = hal_vmm_nexttable((uint64_t *)pml3, pi.pml3);
+  uint64_t *pml1 = hal_vmm_nexttable((uint64_t *)pml2, pi.pml2);
+  uint64_t *pte = &pml1[pi.pml1];
+
+  *pte = physaddr & (~0x7);
+}
+
+void hal_vmm_init(void) {
+  KERNEL_CR3 = hal_vmm_current_cr3();
+}