Commit 152125b7 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

s390/mm: implement dirty bits for large segment table entries 



The large segment table entry format has block of bits for the
ACC/F values for the large page. These bits are valid only if
another bit (AV bit 0x10000) of the segment table entry is set.
The ACC/F bits do not have a meaning if the AV bit is off.
This allows to put the THP splitting bit, the segment young bit
and the new segment dirty bit into the ACC/F bits as long as
the AV bit stays off. The dirty and young information is only
available if the pmd is large.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 55e4283c

arch/s390/include/asm/pgtable.h

+109 −88
Original line number Diff line number Diff line
@@ -287,7 +287,14 @@ extern unsigned long MODULES_END; 
#define _SEGMENT_ENTRY_INVALID	0x20	/* invalid segment table entry	    */

#define _SEGMENT_ENTRY_COMMON	0x10	/* common segment bit		    */

#define _SEGMENT_ENTRY_PTL	0x0f	/* page table length		    */

#define _SEGMENT_ENTRY_NONE	_SEGMENT_ENTRY_PROTECT



#define _SEGMENT_ENTRY_DIRTY	0	/* No sw dirty bit for 31-bit */

#define _SEGMENT_ENTRY_YOUNG	0	/* No sw young bit for 31-bit */

#define _SEGMENT_ENTRY_READ	0	/* No sw read bit for 31-bit */

#define _SEGMENT_ENTRY_WRITE	0	/* No sw write bit for 31-bit */

#define _SEGMENT_ENTRY_LARGE	0	/* No large pages for 31-bit */

#define _SEGMENT_ENTRY_BITS_LARGE 0

#define _SEGMENT_ENTRY_ORIGIN_LARGE 0



#define _SEGMENT_ENTRY		(_SEGMENT_ENTRY_PTL)

#define _SEGMENT_ENTRY_EMPTY	(_SEGMENT_ENTRY_INVALID)
@@ -350,7 +357,7 @@ extern unsigned long MODULES_END; 


/* Bits in the segment table entry */

#define _SEGMENT_ENTRY_BITS	0xfffffffffffffe33UL

#define _SEGMENT_ENTRY_BITS_LARGE 0xfffffffffff1ff33UL

#define _SEGMENT_ENTRY_BITS_LARGE 0xfffffffffff0ff33UL

#define _SEGMENT_ENTRY_ORIGIN_LARGE ~0xfffffUL /* large page address	    */

#define _SEGMENT_ENTRY_ORIGIN	~0x7ffUL/* segment table origin		    */

#define _SEGMENT_ENTRY_PROTECT	0x200	/* page protection bit		    */
@@ -359,30 +366,34 @@ extern unsigned long MODULES_END; 
#define _SEGMENT_ENTRY		(0)

#define _SEGMENT_ENTRY_EMPTY	(_SEGMENT_ENTRY_INVALID)



#define _SEGMENT_ENTRY_LARGE	0x400	/* STE-format control, large page   */

#define _SEGMENT_ENTRY_CO	0x100	/* change-recording override   */

#define _SEGMENT_ENTRY_SPLIT	0x001	/* THP splitting bit */

#define _SEGMENT_ENTRY_YOUNG	0x002	/* SW segment young bit */

#define _SEGMENT_ENTRY_NONE	_SEGMENT_ENTRY_YOUNG

#define _SEGMENT_ENTRY_DIRTY	0x2000	/* SW segment dirty bit */

#define _SEGMENT_ENTRY_YOUNG	0x1000	/* SW segment young bit */

#define _SEGMENT_ENTRY_SPLIT	0x0800	/* THP splitting bit */

#define _SEGMENT_ENTRY_LARGE	0x0400	/* STE-format control, large page */

#define _SEGMENT_ENTRY_CO	0x0100	/* change-recording override   */

#define _SEGMENT_ENTRY_READ	0x0002	/* SW segment read bit */

#define _SEGMENT_ENTRY_WRITE	0x0001	/* SW segment write bit */



/*

 * Segment table entry encoding (R = read-only, I = invalid, y = young bit):

 *			..R...I...y.

 * prot-none, old	..0...1...1.

 * prot-none, young	..1...1...1.

 * read-only, old	..1...1...0.

 * read-only, young	..1...0...1.

 * read-write, old	..0...1...0.

 * read-write, young	..0...0...1.

 *				dy..R...I...wr

 * prot-none, clean, old	00..1...1...00

 * prot-none, clean, young	01..1...1...00

 * prot-none, dirty, old	10..1...1...00

 * prot-none, dirty, young	11..1...1...00

 * read-only, clean, old	00..1...1...01

 * read-only, clean, young	01..1...0...01

 * read-only, dirty, old	10..1...1...01

 * read-only, dirty, young	11..1...0...01

 * read-write, clean, old	00..1...1...11

 * read-write, clean, young	01..1...0...11

 * read-write, dirty, old	10..0...1...11

 * read-write, dirty, young	11..0...0...11

 * The segment table origin is used to distinguish empty (origin==0) from

 * read-write, old segment table entries (origin!=0)

 */



#define _SEGMENT_ENTRY_SPLIT_BIT 0	/* THP splitting bit number */



/* Set of bits not changed in pmd_modify */

#define _SEGMENT_CHG_MASK	(_SEGMENT_ENTRY_ORIGIN | _SEGMENT_ENTRY_LARGE \

				 | _SEGMENT_ENTRY_SPLIT | _SEGMENT_ENTRY_CO)

#define _SEGMENT_ENTRY_SPLIT_BIT 11	/* THP splitting bit number */



/* Page status table bits for virtualization */

#define PGSTE_ACC_BITS	0xf000000000000000UL
@@ -455,10 +466,11 @@ extern unsigned long MODULES_END; 
 * Segment entry (large page) protection definitions.

 */

#define SEGMENT_NONE	__pgprot(_SEGMENT_ENTRY_INVALID | \

				 _SEGMENT_ENTRY_NONE)

#define SEGMENT_READ	__pgprot(_SEGMENT_ENTRY_INVALID | \

				 _SEGMENT_ENTRY_PROTECT)

#define SEGMENT_WRITE	__pgprot(_SEGMENT_ENTRY_INVALID)

#define SEGMENT_READ	__pgprot(_SEGMENT_ENTRY_PROTECT | \

				 _SEGMENT_ENTRY_READ)

#define SEGMENT_WRITE	__pgprot(_SEGMENT_ENTRY_READ | \

				 _SEGMENT_ENTRY_WRITE)



static inline int mm_has_pgste(struct mm_struct *mm)

{
@@ -569,25 +581,23 @@ static inline int pmd_none(pmd_t pmd) 


static inline int pmd_large(pmd_t pmd)

{

#ifdef CONFIG_64BIT

	return (pmd_val(pmd) & _SEGMENT_ENTRY_LARGE) != 0;

#else

	return 0;

#endif

}



static inline int pmd_prot_none(pmd_t pmd)

static inline int pmd_pfn(pmd_t pmd)

{

	return (pmd_val(pmd) & _SEGMENT_ENTRY_INVALID) &&

		(pmd_val(pmd) & _SEGMENT_ENTRY_NONE);

	unsigned long origin_mask;



	origin_mask = _SEGMENT_ENTRY_ORIGIN;

	if (pmd_large(pmd))

		origin_mask = _SEGMENT_ENTRY_ORIGIN_LARGE;

	return (pmd_val(pmd) & origin_mask) >> PAGE_SHIFT;

}



static inline int pmd_bad(pmd_t pmd)

{

#ifdef CONFIG_64BIT

	if (pmd_large(pmd))

		return (pmd_val(pmd) & ~_SEGMENT_ENTRY_BITS_LARGE) != 0;

#endif

	return (pmd_val(pmd) & ~_SEGMENT_ENTRY_BITS) != 0;

}
@@ -607,20 +617,22 @@ extern int pmdp_clear_flush_young(struct vm_area_struct *vma, 
#define __HAVE_ARCH_PMD_WRITE

static inline int pmd_write(pmd_t pmd)

{

	if (pmd_prot_none(pmd))

		return 0;

	return (pmd_val(pmd) & _SEGMENT_ENTRY_PROTECT) == 0;

	return (pmd_val(pmd) & _SEGMENT_ENTRY_WRITE) != 0;

}



static inline int pmd_dirty(pmd_t pmd)

{

	int dirty = 1;

	if (pmd_large(pmd))

		dirty = (pmd_val(pmd) & _SEGMENT_ENTRY_DIRTY) != 0;

	return dirty;

}



static inline int pmd_young(pmd_t pmd)

{

	int young = 0;

#ifdef CONFIG_64BIT

	if (pmd_prot_none(pmd))

		young = (pmd_val(pmd) & _SEGMENT_ENTRY_PROTECT) != 0;

	else

	int young = 1;

	if (pmd_large(pmd))

		young = (pmd_val(pmd) & _SEGMENT_ENTRY_YOUNG) != 0;

#endif

	return young;

}
@@ -1391,7 +1403,7 @@ static inline pmd_t *pmd_offset(pud_t *pud, unsigned long address) 
#define pte_pfn(x) (pte_val(x) >> PAGE_SHIFT)

#define pte_page(x) pfn_to_page(pte_pfn(x))



#define pmd_page(pmd) pfn_to_page(pmd_val(pmd) >> PAGE_SHIFT)

#define pmd_page(pmd) pfn_to_page(pmd_pfn(pmd))



/* Find an entry in the lowest level page table.. */

#define pte_offset(pmd, addr) ((pte_t *) pmd_deref(*(pmd)) + pte_index(addr))
@@ -1413,41 +1425,75 @@ static inline unsigned long massage_pgprot_pmd(pgprot_t pgprot) 
	return pgprot_val(SEGMENT_WRITE);

}



static inline pmd_t pmd_mkyoung(pmd_t pmd)

static inline pmd_t pmd_wrprotect(pmd_t pmd)

{

#ifdef CONFIG_64BIT

	if (pmd_prot_none(pmd)) {

	pmd_val(pmd) &= ~_SEGMENT_ENTRY_WRITE;

	pmd_val(pmd) |= _SEGMENT_ENTRY_PROTECT;

	} else {

	return pmd;

}



static inline pmd_t pmd_mkwrite(pmd_t pmd)

{

	pmd_val(pmd) |= _SEGMENT_ENTRY_WRITE;

	if (pmd_large(pmd) && !(pmd_val(pmd) & _SEGMENT_ENTRY_DIRTY))

		return pmd;

	pmd_val(pmd) &= ~_SEGMENT_ENTRY_PROTECT;

	return pmd;

}



static inline pmd_t pmd_mkclean(pmd_t pmd)

{

	if (pmd_large(pmd)) {

		pmd_val(pmd) &= ~_SEGMENT_ENTRY_DIRTY;

		pmd_val(pmd) |= _SEGMENT_ENTRY_PROTECT;

	}

	return pmd;

}



static inline pmd_t pmd_mkdirty(pmd_t pmd)

{

	if (pmd_large(pmd)) {

		pmd_val(pmd) |= _SEGMENT_ENTRY_DIRTY;

		if (pmd_val(pmd) & _SEGMENT_ENTRY_WRITE)

			pmd_val(pmd) &= ~_SEGMENT_ENTRY_PROTECT;

	}

	return pmd;

}



static inline pmd_t pmd_mkyoung(pmd_t pmd)

{

	if (pmd_large(pmd)) {

		pmd_val(pmd) |= _SEGMENT_ENTRY_YOUNG;

		if (pmd_val(pmd) & _SEGMENT_ENTRY_READ)

			pmd_val(pmd) &= ~_SEGMENT_ENTRY_INVALID;

	}

#endif

	return pmd;

}



static inline pmd_t pmd_mkold(pmd_t pmd)

{

#ifdef CONFIG_64BIT

	if (pmd_prot_none(pmd)) {

		pmd_val(pmd) &= ~_SEGMENT_ENTRY_PROTECT;

	} else {

	if (pmd_large(pmd)) {

		pmd_val(pmd) &= ~_SEGMENT_ENTRY_YOUNG;

		pmd_val(pmd) |= _SEGMENT_ENTRY_INVALID;

	}

#endif

	return pmd;

}



static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)

{

	int young;



	young = pmd_young(pmd);

	pmd_val(pmd) &= _SEGMENT_CHG_MASK;

	if (pmd_large(pmd)) {

		pmd_val(pmd) &= _SEGMENT_ENTRY_ORIGIN_LARGE |

			_SEGMENT_ENTRY_DIRTY | _SEGMENT_ENTRY_YOUNG |

			_SEGMENT_ENTRY_LARGE | _SEGMENT_ENTRY_SPLIT;

		pmd_val(pmd) |= massage_pgprot_pmd(newprot);

		if (!(pmd_val(pmd) & _SEGMENT_ENTRY_DIRTY))

			pmd_val(pmd) |= _SEGMENT_ENTRY_PROTECT;

		if (!(pmd_val(pmd) & _SEGMENT_ENTRY_YOUNG))

			pmd_val(pmd) |= _SEGMENT_ENTRY_INVALID;

		return pmd;

	}

	pmd_val(pmd) &= _SEGMENT_ENTRY_ORIGIN;

	pmd_val(pmd) |= massage_pgprot_pmd(newprot);

	if (young)

		pmd = pmd_mkyoung(pmd);

	return pmd;

}
@@ -1455,16 +1501,9 @@ static inline pmd_t mk_pmd_phys(unsigned long physpage, pgprot_t pgprot) 
{

	pmd_t __pmd;

	pmd_val(__pmd) = physpage + massage_pgprot_pmd(pgprot);

	return pmd_mkyoung(__pmd);

	return __pmd;

}



static inline pmd_t pmd_mkwrite(pmd_t pmd)

{

	/* Do not clobber PROT_NONE segments! */

	if (!pmd_prot_none(pmd))

		pmd_val(pmd) &= ~_SEGMENT_ENTRY_PROTECT;

	return pmd;

}

#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLB_PAGE */



static inline void __pmdp_csp(pmd_t *pmdp)
@@ -1555,37 +1594,24 @@ extern pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp); 


static inline int pmd_trans_splitting(pmd_t pmd)

{

	return pmd_val(pmd) & _SEGMENT_ENTRY_SPLIT;

	return (pmd_val(pmd) & _SEGMENT_ENTRY_LARGE) &&

		(pmd_val(pmd) & _SEGMENT_ENTRY_SPLIT);

}



static inline void set_pmd_at(struct mm_struct *mm, unsigned long addr,

			      pmd_t *pmdp, pmd_t entry)

{

	if (!(pmd_val(entry) & _SEGMENT_ENTRY_INVALID) && MACHINE_HAS_EDAT1)

		pmd_val(entry) |= _SEGMENT_ENTRY_CO;

	*pmdp = entry;

}



static inline pmd_t pmd_mkhuge(pmd_t pmd)

{

	pmd_val(pmd) |= _SEGMENT_ENTRY_LARGE;

	return pmd;

}



static inline pmd_t pmd_wrprotect(pmd_t pmd)

{

	/* Do not clobber PROT_NONE segments! */

	if (!pmd_prot_none(pmd))

	pmd_val(pmd) |= _SEGMENT_ENTRY_YOUNG;

	pmd_val(pmd) |= _SEGMENT_ENTRY_PROTECT;

	return pmd;

}



static inline pmd_t pmd_mkdirty(pmd_t pmd)

{

	/* No dirty bit in the segment table entry. */

	return pmd;

}



#define __HAVE_ARCH_PMDP_TEST_AND_CLEAR_YOUNG

static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma,

					    unsigned long address, pmd_t *pmdp)
@@ -1647,11 +1673,6 @@ static inline int has_transparent_hugepage(void) 
{

	return MACHINE_HAS_HPAGE ? 1 : 0;

}



static inline unsigned long pmd_pfn(pmd_t pmd)

{

	return pmd_val(pmd) >> PAGE_SHIFT;

}

#endif /* CONFIG_TRANSPARENT_HUGEPAGE */



/*

arch/s390/mm/hugetlbpage.c

+47 −56
Original line number Diff line number Diff line
@@ -10,42 +10,33 @@ 


static inline pmd_t __pte_to_pmd(pte_t pte)

{

	int none, young, prot;

	pmd_t pmd;



	/*

	 * Convert encoding		  pte bits	   pmd bits

	 *				.IR...wrdytp	..R...I...y.

	 * empty			.10...000000 -> ..0...1...0.

	 * prot-none, clean, old	.11...000001 -> ..0...1...1.

	 * prot-none, clean, young	.11...000101 -> ..1...1...1.

	 * prot-none, dirty, old	.10...001001 -> ..0...1...1.

	 * prot-none, dirty, young	.10...001101 -> ..1...1...1.

	 * read-only, clean, old	.11...010001 -> ..1...1...0.

	 * read-only, clean, young	.01...010101 -> ..1...0...1.

	 * read-only, dirty, old	.11...011001 -> ..1...1...0.

	 * read-only, dirty, young	.01...011101 -> ..1...0...1.

	 * read-write, clean, old	.11...110001 -> ..0...1...0.

	 * read-write, clean, young	.01...110101 -> ..0...0...1.

	 * read-write, dirty, old	.10...111001 -> ..0...1...0.

	 * read-write, dirty, young	.00...111101 -> ..0...0...1.

	 * Huge ptes are dirty by definition, a clean pte is made dirty

	 * by the conversion.

	 *				.IR...wrdytp	dy..R...I...wr

	 * empty			.10...000000 -> 00..0...1...00

	 * prot-none, clean, old	.11...000001 -> 00..1...1...00

	 * prot-none, clean, young	.11...000101 -> 01..1...1...00

	 * prot-none, dirty, old	.10...001001 -> 10..1...1...00

	 * prot-none, dirty, young	.10...001101 -> 11..1...1...00

	 * read-only, clean, old	.11...010001 -> 00..1...1...01

	 * read-only, clean, young	.01...010101 -> 01..1...0...01

	 * read-only, dirty, old	.11...011001 -> 10..1...1...01

	 * read-only, dirty, young	.01...011101 -> 11..1...0...01

	 * read-write, clean, old	.11...110001 -> 00..0...1...11

	 * read-write, clean, young	.01...110101 -> 01..0...0...11

	 * read-write, dirty, old	.10...111001 -> 10..0...1...11

	 * read-write, dirty, young	.00...111101 -> 11..0...0...11

	 */

	if (pte_present(pte)) {

		pmd_val(pmd) = pte_val(pte) & PAGE_MASK;

		if (pte_val(pte) & _PAGE_INVALID)

			pmd_val(pmd) |= _SEGMENT_ENTRY_INVALID;

		none = (pte_val(pte) & _PAGE_PRESENT) &&

			!(pte_val(pte) & _PAGE_READ) &&

			!(pte_val(pte) & _PAGE_WRITE);

		prot = (pte_val(pte) & _PAGE_PROTECT) &&

			!(pte_val(pte) & _PAGE_WRITE);

		young = pte_val(pte) & _PAGE_YOUNG;

		if (none || young)

			pmd_val(pmd) |= _SEGMENT_ENTRY_YOUNG;

		if (prot || (none && young))

			pmd_val(pmd) |= _SEGMENT_ENTRY_PROTECT;

		pmd_val(pmd) |= (pte_val(pte) & _PAGE_READ) >> 4;

		pmd_val(pmd) |= (pte_val(pte) & _PAGE_WRITE) >> 4;

		pmd_val(pmd) |=	(pte_val(pte) & _PAGE_INVALID) >> 5;

		pmd_val(pmd) |= (pte_val(pte) & _PAGE_PROTECT);

		pmd_val(pmd) |= (pte_val(pte) & _PAGE_DIRTY) << 10;

		pmd_val(pmd) |= (pte_val(pte) & _PAGE_YOUNG) << 10;

	} else

		pmd_val(pmd) = _SEGMENT_ENTRY_INVALID;

	return pmd;
@@ -57,33 +48,30 @@ static inline pte_t __pmd_to_pte(pmd_t pmd) 


	/*

	 * Convert encoding		   pmd bits	    pte bits

	 *			..R...I...y.	.IR...wrdytp

	 * empty		..0...1...0. -> .10...000000

	 * prot-none, old	..0...1...1. -> .10...001001

	 * prot-none, young	..1...1...1. -> .10...001101

	 * read-only, old	..1...1...0. -> .11...011001

	 * read-only, young	..1...0...1. -> .01...011101

	 * read-write, old	..0...1...0. -> .10...111001

	 * read-write, young	..0...0...1. -> .00...111101

	 * Huge ptes are dirty by definition

	 *				dy..R...I...wr	  .IR...wrdytp

	 * empty			00..0...1...00 -> .10...001100

	 * prot-none, clean, old	00..0...1...00 -> .10...000001

	 * prot-none, clean, young	01..0...1...00 -> .10...000101

	 * prot-none, dirty, old	10..0...1...00 -> .10...001001

	 * prot-none, dirty, young	11..0...1...00 -> .10...001101

	 * read-only, clean, old	00..1...1...01 -> .11...010001

	 * read-only, clean, young	01..1...1...01 -> .11...010101

	 * read-only, dirty, old	10..1...1...01 -> .11...011001

	 * read-only, dirty, young	11..1...1...01 -> .11...011101

	 * read-write, clean, old	00..0...1...11 -> .10...110001

	 * read-write, clean, young	01..0...1...11 -> .10...110101

	 * read-write, dirty, old	10..0...1...11 -> .10...111001

	 * read-write, dirty, young	11..0...1...11 -> .10...111101

	 */

	if (pmd_present(pmd)) {

		pte_val(pte) = _PAGE_PRESENT | _PAGE_LARGE | _PAGE_DIRTY |

			(pmd_val(pmd) & PAGE_MASK);

		if (pmd_val(pmd) & _SEGMENT_ENTRY_INVALID)

			pte_val(pte) |= _PAGE_INVALID;

		if (pmd_prot_none(pmd)) {

			if (pmd_val(pmd) & _SEGMENT_ENTRY_PROTECT)

				pte_val(pte) |= _PAGE_YOUNG;

		} else {

			pte_val(pte) |= _PAGE_READ;

			if (pmd_val(pmd) & _SEGMENT_ENTRY_PROTECT)

				pte_val(pte) |= _PAGE_PROTECT;

			else

				pte_val(pte) |= _PAGE_WRITE;

			if (pmd_val(pmd) & _SEGMENT_ENTRY_YOUNG)

				pte_val(pte) |= _PAGE_YOUNG;

		}

		pte_val(pte) = pmd_val(pmd) & _SEGMENT_ENTRY_ORIGIN_LARGE;

		pte_val(pte) |= _PAGE_LARGE | _PAGE_PRESENT;

		pte_val(pte) |= (pmd_val(pmd) & _SEGMENT_ENTRY_READ) << 4;

		pte_val(pte) |= (pmd_val(pmd) & _SEGMENT_ENTRY_WRITE) << 4;

		pte_val(pte) |= (pmd_val(pmd) & _SEGMENT_ENTRY_INVALID) << 5;

		pte_val(pte) |= (pmd_val(pmd) & _SEGMENT_ENTRY_PROTECT);

		pmd_val(pmd) |= (pte_val(pte) & _PAGE_DIRTY) << 10;

		pmd_val(pmd) |= (pte_val(pte) & _PAGE_YOUNG) << 10;

	} else

		pte_val(pte) = _PAGE_INVALID;

	return pte;
@@ -96,6 +84,7 @@ void set_huge_pte_at(struct mm_struct *mm, unsigned long addr, 


	pmd = __pte_to_pmd(pte);

	if (!MACHINE_HAS_HPAGE) {

		/* Emulated huge ptes loose the dirty and young bit */

		pmd_val(pmd) &= ~_SEGMENT_ENTRY_ORIGIN;

		pmd_val(pmd) |= pte_page(pte)[1].index;

	} else
@@ -113,6 +102,8 @@ pte_t huge_ptep_get(pte_t *ptep) 
		origin = pmd_val(pmd) & _SEGMENT_ENTRY_ORIGIN;

		pmd_val(pmd) &= ~_SEGMENT_ENTRY_ORIGIN;

		pmd_val(pmd) |= *(unsigned long *) origin;

		/* Emulated huge ptes are young and dirty by definition */

		pmd_val(pmd) |= _SEGMENT_ENTRY_YOUNG | _SEGMENT_ENTRY_DIRTY;

	}

	return __pmd_to_pte(pmd);

}

arch/s390/mm/pgtable.c

+3 −0
Original line number Diff line number Diff line
@@ -1433,6 +1433,9 @@ int pmdp_set_access_flags(struct vm_area_struct *vma, 
{

	VM_BUG_ON(address & ~HPAGE_PMD_MASK);



	entry = pmd_mkyoung(entry);

	if (dirty)

		entry = pmd_mkdirty(entry);

	if (pmd_same(*pmdp, entry))

		return 0;

	pmdp_invalidate(vma, address, pmdp);

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