usertests and optional finished

kernel/sysproc.c

@@ -163,3 +163,42 @@ sys_pgaccess(void)
 
    return 0;
  }
+
+#ifdef LAB_PGTBL
+uint64
+sys_dirtypages(void)
+{
+  struct proc *p = myproc();
+  unsigned int dbits = 0;
+
+  uint64 addr;
+  argaddr(0, &addr);
+
+  int num;
+  argint(1, &num);
+
+  uint64 dest;
+  argaddr(2, &dest);
+
+  // Check each page in the range
+  for(int i = 0; i < num; i++){
+    uint64 query_addr = addr + i * PGSIZE;
+
+    pte_t *pte = walk(p->pagetable, query_addr, 0);
+    if(pte == 0)
+      continue;  // Skip pages that don't exist
+    
+    if(*pte & PTE_D) {
+      dbits = dbits | (1 << i);
+      // Clear the dirty bit after reading it
+      *pte = (*pte) & (~PTE_D);
+    }
+  }
+
+  // Copy the result back to user space
+  if(copyout(p->pagetable, dest, (char*)&dbits, sizeof(dbits)) < 0)
+    return -1;
+
+  return 0;
+}
+#endif