1  typedef struct {
       2      unsigned long pmd0;
       3      unsigned long pmd1;
       4  } pmd_t;
       5  typedef unsigned int pgd_t;
       6  struct mm_struct {
       7      pgd_t * pgd;
       8  };
       9  extern inline int pmd_bad(pmd_t pmd)
      10  {
      11  }
      12  extern inline void pmd_clear(pmd_t * pmdp)
      13  {
      14    ((*pmdp).pmd0) = 0x20 | 0x00;
      15    ((*pmdp).pmd1) = 0x20 | 0x00;
      16  }
      17  static inline void free_one_pmd(pmd_t * dir)
      18  {
      19    if (pmd_bad(*dir)) {
      20        pmd_clear(dir);
      21    }
      22  }
      23  static inline void free_one_pgd(pgd_t * dir)
      24  {
      25    int j;
      26    pmd_t * pmd;
      27    pmd = ((pmd_t *) ((unsigned long) (void *)(__pgd_val(dir) & (~((1UL << 12)-1)))) + (((0) >> 21) & (512 - 1)));
      28    for (j = 0; j < 512 ; j++) {
      29        free_one_pmd(pmd+j);
      30    }
      31  }
      32  void clear_page_tables(struct mm_struct *mm, unsigned long first, int nr)
      33  {
      34    pgd_t * page_dir = mm->pgd;
      35    do {
      36        free_one_pgd(page_dir);
      37    } while (--nr);
      38  }