WIP 4.6 a few issues left

kernel/vm.c

@@ -377,13 +377,27 @@ int load_from_file(char* file,
   }
 
 int do_allocate(pagetable_t pagetable, struct proc* p, uint64 addr){
+  struct vma *  this_vma;
+  uint64 pa;
+
+  if((this_vma = get_memory_area(p, addr)) == 0){
+    return ENOVMA;
+  }
   
   pte_t* pte = walk(pagetable, addr, 0);
-  if(pte == 0 || !(*pte & PTE_V)){
-    return ENOMEM;
+  if (pte) {
+    if(!(*pte & PTE_U))
+      return EBADPERM;
+    
+    return 0;
   }
-  if(!(*pte & PTE_U)){
-    return EBADPERM;
+
+  if((pa = (uint64)kalloc()) == 0)
+    return ENOMEM;
+  
+  if (mappages(pagetable, PGROUNDDOWN(addr), PGSIZE, pa, PTE_R | PTE_W | PTE_X | PTE_U) == -1) {
+    kfree(&pa);
+    return EMAPFAILED;
   }
   return 0;
 }