lab detect which pages have been accessed finished

Nowherechan · Mar 8, 2023 · d2497df · d2497df
1 parent 6ad90d2
commit d2497df
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diff --git a/kernel/riscv.h b/kernel/riscv.h
@@ -343,6 +343,7 @@ typedef uint64 *pagetable_t; // 512 PTEs
 #define PTE_W (1L << 2)
 #define PTE_X (1L << 3)
 #define PTE_U (1L << 4) // user can access
+#define PTE_A (1L << 6) // accessed, for pgtbl-lab 3
 
 // shift a physical address to the right place for a PTE.
 #define PA2PTE(pa) ((((uint64)pa) >> 12) << 10)

diff --git a/kernel/sysproc.c b/kernel/sysproc.c
@@ -75,6 +75,29 @@ int
 sys_pgaccess(void)
 {
   // lab pgtbl: your code here.
+  uint64 va, buf;
+  int num;
+  unsigned int kbuf = 0;
+  argaddr(0, &va);
+  argint(1, &num);
+  argaddr(2, &buf);
+  pagetable_t pagetable = myproc()->pagetable;
+  va = PGROUNDDOWN(va);
+
+  if (num > 32) { // limit
+    return -1;
+  }
+
+  for (int i = 0; i < num; i++) {
+    pte_t *pte = walk(pagetable, va, 0);
+    va += PGSIZE;
+    if ((*pte) & PTE_A) {
+      kbuf |= (1L << i);
+    }
+    (*pte) &= ~PTE_A;
+  }
+
+  copyout(pagetable, buf, (char*)&kbuf, 4);
   return 0;
 }
 #endif