root/arch/x86/include/asm/pgtable-2level.h

INCLUDED FROM

DEFINITIONS

1. native_set_pte
2. native_set_pmd
3. native_set_pte_atomic
4. native_pmd_clear
5. native_pte_clear
6. native_ptep_get_and_clear
7. native_pmdp_get_and_clear
8. pte_bitop
9. pte_to_pgoff
10. pgoff_to_pte

#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

/* Bit manipulation helper on pte/pgoff entry */
static inline unsigned long pte_bitop(unsigned long value, unsigned int rightshift,
                                      unsigned long mask, unsigned int leftshift)
{
        return ((value >> rightshift) & mask) << leftshift;
}

/*
 * 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)
#define PTE_FILE_SHIFT2         (_PAGE_BIT_FILE + 1)
#define PTE_FILE_SHIFT3         (_PAGE_BIT_PROTNONE + 1)
#define PTE_FILE_BITS1          (PTE_FILE_SHIFT2 - PTE_FILE_SHIFT1 - 1)
#define PTE_FILE_BITS2          (PTE_FILE_SHIFT3 - PTE_FILE_SHIFT2 - 1)

#define PTE_FILE_MASK1          ((1U << PTE_FILE_BITS1) - 1)
#define PTE_FILE_MASK2          ((1U << PTE_FILE_BITS2) - 1)

#define PTE_FILE_LSHIFT2        (PTE_FILE_BITS1)
#define PTE_FILE_LSHIFT3        (PTE_FILE_BITS1 + PTE_FILE_BITS2)

static __always_inline pgoff_t pte_to_pgoff(pte_t pte)
{
        return (pgoff_t)
                (pte_bitop(pte.pte_low, PTE_FILE_SHIFT1, PTE_FILE_MASK1,  0)                +
                 pte_bitop(pte.pte_low, PTE_FILE_SHIFT2, PTE_FILE_MASK2,  PTE_FILE_LSHIFT2) +
                 pte_bitop(pte.pte_low, PTE_FILE_SHIFT3,           -1UL,  PTE_FILE_LSHIFT3));
}

static __always_inline pte_t pgoff_to_pte(pgoff_t off)
{
        return (pte_t){
                .pte_low =
                        pte_bitop(off,                0, PTE_FILE_MASK1,  PTE_FILE_SHIFT1) +
                        pte_bitop(off, PTE_FILE_LSHIFT2, PTE_FILE_MASK2,  PTE_FILE_SHIFT2) +
                        pte_bitop(off, PTE_FILE_LSHIFT3,           -1UL,  PTE_FILE_SHIFT3) +
                        _PAGE_FILE,
        };
}

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

#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 */