Lab pgtbl: vmprint

foyoodo · Mar 16, 2021 · 5d14570 · 5d14570
1 parent 773d70b
commit 5d14570
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Showing 3 changed files with 29 additions and 0 deletions.
diff --git a/kernel/defs.h b/kernel/defs.h
@@ -178,6 +178,7 @@ uint64          walkaddr(pagetable_t, uint64);
 int             copyout(pagetable_t, uint64, char *, uint64);
 int             copyin(pagetable_t, char *, uint64, uint64);
 int             copyinstr(pagetable_t, char *, uint64, uint64);
+void            vmprint(pagetable_t);
 
 // plic.c
 void            plicinit(void);

diff --git a/kernel/exec.c b/kernel/exec.c
@@ -116,6 +116,8 @@ exec(char *path, char **argv)
   p->trapframe->sp = sp; // initial stack pointer
   proc_freepagetable(oldpagetable, oldsz);
 
+  if (p->pid == 1) vmprint(p->pagetable);
+
   return argc; // this ends up in a0, the first argument to main(argc, argv)
 
  bad:

diff --git a/kernel/vm.c b/kernel/vm.c
@@ -440,3 +440,29 @@ copyinstr(pagetable_t pagetable, char *dst, uint64 srcva, uint64 max)
     return -1;
   }
 }
+
+void
+vmprintwalk(pagetable_t pagetable, int deep)
+{
+  // there are 2^9 = 512 PTEs in a page table.
+  for (int i = 0; i < 512; i++) {
+    pte_t pte = pagetable[i];
+    if (pte & PTE_V) {
+      for (int i = 0; i <= deep; ++i) printf(".. ");
+      printf("%d: pte %p pa %p\n", i, pte, PTE2PA(pte));
+
+      if ((pte & (PTE_R | PTE_W | PTE_X)) == 0) {
+        // this PTE points to a lower-level page table.
+        uint64 child = PTE2PA(pte);
+        vmprintwalk((pagetable_t)child, deep + 1);
+      }
+    }
+  }
+}
+
+void
+vmprint(pagetable_t pagetable)
+{
+  printf("page table %p\n", pagetable);
+  vmprintwalk(pagetable, 0);
+}