pgtable-2level.h

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#ifndef _ASM_X86_PGTABLE_2LEVEL_H
#define _ASM_X86_PGTABLE_2LEVEL_H

#define pte_ERROR(e) \
    pr_err("%s:%d: bad pte %08lx\n", __FILE__, __LINE__, (e).pte_low)
#define pgd_ERROR(e) \
    pr_err("%s:%d: bad pgd %08lx\n", __FILE__, __LINE__, pgd_val(e))

/*
 * Certain architectures need to do special things when PTEs
 * within a page table are directly modified.  Thus, the following
 * hook is made available.
 */
static inline void native_set_pte(pte_t *ptep , pte_t pte)
{
    *ptep = pte;
}

static inline void native_set_pmd(pmd_t *pmdp, pmd_t pmd)
{
    *pmdp = pmd;
}

static inline void native_set_pte_atomic(pte_t *ptep, pte_t pte)
{
    native_set_pte(ptep, pte);
}

static inline void native_pmd_clear(pmd_t *pmdp)
{
    native_set_pmd(pmdp, __pmd(0));
}

static inline void native_pte_clear(struct mm_struct *mm,
                    unsigned long addr, pte_t *xp)
{
    *xp = native_make_pte(0);
}

#ifdef CONFIG_SMP
static inline pte_t native_ptep_get_and_clear(pte_t *xp)
{
    return __pte(xchg(&xp->pte_low, 0));
}
#else
#define native_ptep_get_and_clear(xp) native_local_ptep_get_and_clear(xp)
#endif

#ifdef CONFIG_SMP
static inline pmd_t native_pmdp_get_and_clear(pmd_t *xp)
{
    return __pmd(xchg((pmdval_t *)xp, 0));
}
#else
#define native_pmdp_get_and_clear(xp) native_local_pmdp_get_and_clear(xp)
#endif

/*
 * Bits _PAGE_BIT_PRESENT, _PAGE_BIT_FILE and _PAGE_BIT_PROTNONE are taken,
 * split up the 29 bits of offset into this range:
 */
#define PTE_FILE_MAX_BITS   29
#define PTE_FILE_SHIFT1     (_PAGE_BIT_PRESENT + 1)
#if _PAGE_BIT_FILE < _PAGE_BIT_PROTNONE
#define PTE_FILE_SHIFT2     (_PAGE_BIT_FILE + 1)
#define PTE_FILE_SHIFT3     (_PAGE_BIT_PROTNONE + 1)
#else
#define PTE_FILE_SHIFT2     (_PAGE_BIT_PROTNONE + 1)
#define PTE_FILE_SHIFT3     (_PAGE_BIT_FILE + 1)
#endif
#define PTE_FILE_BITS1      (PTE_FILE_SHIFT2 - PTE_FILE_SHIFT1 - 1)
#define PTE_FILE_BITS2      (PTE_FILE_SHIFT3 - PTE_FILE_SHIFT2 - 1)

#define pte_to_pgoff(pte)                       \
    ((((pte).pte_low >> PTE_FILE_SHIFT1)                \
      & ((1U << PTE_FILE_BITS1) - 1))               \
     + ((((pte).pte_low >> PTE_FILE_SHIFT2)             \
         & ((1U << PTE_FILE_BITS2) - 1)) << PTE_FILE_BITS1)     \
     + (((pte).pte_low >> PTE_FILE_SHIFT3)              \
        << (PTE_FILE_BITS1 + PTE_FILE_BITS2)))

#define pgoff_to_pte(off)                       \
    ((pte_t) { .pte_low =                       \
     (((off) & ((1U << PTE_FILE_BITS1) - 1)) << PTE_FILE_SHIFT1)    \
     + ((((off) >> PTE_FILE_BITS1) & ((1U << PTE_FILE_BITS2) - 1))  \
        << PTE_FILE_SHIFT2)                     \
     + (((off) >> (PTE_FILE_BITS1 + PTE_FILE_BITS2))        \
        << PTE_FILE_SHIFT3)                     \
     + _PAGE_FILE })

/* Encode and de-code a swap entry */
#if _PAGE_BIT_FILE < _PAGE_BIT_PROTNONE
#define SWP_TYPE_BITS (_PAGE_BIT_FILE - _PAGE_BIT_PRESENT - 1)
#define SWP_OFFSET_SHIFT (_PAGE_BIT_PROTNONE + 1)
#else
#define SWP_TYPE_BITS (_PAGE_BIT_PROTNONE - _PAGE_BIT_PRESENT - 1)
#define SWP_OFFSET_SHIFT (_PAGE_BIT_FILE + 1)
#endif

#define MAX_SWAPFILES_CHECK() BUILD_BUG_ON(MAX_SWAPFILES_SHIFT > SWP_TYPE_BITS)

#define __swp_type(x)           (((x).val >> (_PAGE_BIT_PRESENT + 1)) \
                     & ((1U << SWP_TYPE_BITS) - 1))
#define __swp_offset(x)         ((x).val >> SWP_OFFSET_SHIFT)
#define __swp_entry(type, offset)   ((swp_entry_t) { \
                     ((type) << (_PAGE_BIT_PRESENT + 1)) \
                     | ((offset) << SWP_OFFSET_SHIFT) })
#define __pte_to_swp_entry(pte)     ((swp_entry_t) { (pte).pte_low })
#define __swp_entry_to_pte(x)       ((pte_t) { .pte = (x).val })

#endif /* _ASM_X86_PGTABLE_2LEVEL_H */