4.6 passes tests

kernel/vm.c

@@ -377,29 +377,32 @@ 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){
+pte_t* pt_entry;
+  if ( !get_memory_area(p, addr)){
     return ENOVMA;
   }
-  
-  pte_t* pte = walk(pagetable, addr, 0);
-  if (pte) {
-    if(!(*pte & PTE_U))
+  pt_entry = walk(pagetable, addr, 0);
+  if(pt_entry){
+    if( PTE_V & *pt_entry ){
+      if( PTE_U & *pt_entry){
+        return 0;
+      }
       return EBADPERM;
-    
-    return 0;
+    }
   }
+  //page not present -> do allocation
+  uint64* phy_addr = kalloc();
 
-  if((pa = (uint64)kalloc()) == 0)
+  if(phy_addr == 0){
     return ENOMEM;
+  }
   
-  if (mappages(pagetable, PGROUNDDOWN(addr), PGSIZE, pa, PTE_R | PTE_W | PTE_X | PTE_U) == -1) {
-    kfree(&pa);
+  if(mappages( pagetable, addr, PGSIZE, (uint64)phy_addr, PTE_W | PTE_X | PTE_R | PTE_U)){
+    kfree(phy_addr);
     return EMAPFAILED;
   }
   return 0;
+
 }
 
 int do_allocate_range(pagetable_t pagetable, struct proc* p, uint64 addr, uint64 len){