arch/s390/mm/hugetlbpage.c

   1 /*
   2  *  IBM System z Huge TLB Page Support for Kernel.
   3  *
   4  *    Copyright IBM Corp. 2007
   5  *    Author(s): Gerald Schaefer <gerald.schaefer@de.ibm.com>
   6  */
   7
   8 #include <linux/mm.h>
   9 #include <linux/hugetlb.h>
  10
  11 static inline pmd_t __pte_to_pmd(pte_t pte)
  12 {
  13         pmd_t pmd;
  14
  15         /*
  16          * Convert encoding               pte bits         pmd bits
  17          *                              lIR.uswrdy.p    dy..R...I...wr
  18          * empty                        010.000000.0 -> 00..0...1...00
  19          * prot-none, clean, old        111.000000.1 -> 00..1...1...00
  20          * prot-none, clean, young      111.000001.1 -> 01..1...1...00
  21          * prot-none, dirty, old        111.000010.1 -> 10..1...1...00
  22          * prot-none, dirty, young      111.000011.1 -> 11..1...1...00
  23          * read-only, clean, old        111.000100.1 -> 00..1...1...01
  24          * read-only, clean, young      101.000101.1 -> 01..1...0...01
  25          * read-only, dirty, old        111.000110.1 -> 10..1...1...01
  26          * read-only, dirty, young      101.000111.1 -> 11..1...0...01
  27          * read-write, clean, old       111.001100.1 -> 00..1...1...11
  28          * read-write, clean, young     101.001101.1 -> 01..1...0...11
  29          * read-write, dirty, old       110.001110.1 -> 10..0...1...11
  30          * read-write, dirty, young     100.001111.1 -> 11..0...0...11
  31          * HW-bits: R read-only, I invalid
  32          * SW-bits: p present, y young, d dirty, r read, w write, s special,
  33          *          u unused, l large
  34          */
  35         if (pte_present(pte)) {
  36                 pmd_val(pmd) = pte_val(pte) & PAGE_MASK;
  37                 pmd_val(pmd) |= (pte_val(pte) & _PAGE_READ) >> 4;
  38                 pmd_val(pmd) |= (pte_val(pte) & _PAGE_WRITE) >> 4;
  39                 pmd_val(pmd) |= (pte_val(pte) & _PAGE_INVALID) >> 5;
  40                 pmd_val(pmd) |= (pte_val(pte) & _PAGE_PROTECT);
  41                 pmd_val(pmd) |= (pte_val(pte) & _PAGE_DIRTY) << 10;
  42                 pmd_val(pmd) |= (pte_val(pte) & _PAGE_YOUNG) << 10;
  43         } else
  44                 pmd_val(pmd) = _SEGMENT_ENTRY_INVALID;
  45         return pmd;
  46 }
  47
  48 static inline pte_t __pmd_to_pte(pmd_t pmd)
  49 {
  50         pte_t pte;
  51
  52         /*
  53          * Convert encoding                pmd bits         pte bits
  54          *                              dy..R...I...wr    lIR.uswrdy.p
  55          * empty                        00..0...1...00 -> 010.000000.0
  56          * prot-none, clean, old        00..1...1...00 -> 111.000000.1
  57          * prot-none, clean, young      01..1...1...00 -> 111.000001.1
  58          * prot-none, dirty, old        10..1...1...00 -> 111.000010.1
  59          * prot-none, dirty, young      11..1...1...00 -> 111.000011.1
  60          * read-only, clean, old        00..1...1...01 -> 111.000100.1
  61          * read-only, clean, young      01..1...0...01 -> 101.000101.1
  62          * read-only, dirty, old        10..1...1...01 -> 111.000110.1
  63          * read-only, dirty, young      11..1...0...01 -> 101.000111.1
  64          * read-write, clean, old       00..1...1...11 -> 111.001100.1
  65          * read-write, clean, young     01..1...0...11 -> 101.001101.1
  66          * read-write, dirty, old       10..0...1...11 -> 110.001110.1
  67          * read-write, dirty, young     11..0...0...11 -> 100.001111.1
  68          * HW-bits: R read-only, I invalid
  69          * SW-bits: p present, y young, d dirty, r read, w write, s special,
  70          *          u unused, l large
  71          */
  72         if (pmd_present(pmd)) {
  73                 pte_val(pte) = pmd_val(pmd) & _SEGMENT_ENTRY_ORIGIN_LARGE;
  74                 pte_val(pte) |= _PAGE_LARGE | _PAGE_PRESENT;
  75                 pte_val(pte) |= (pmd_val(pmd) & _SEGMENT_ENTRY_READ) << 4;
  76                 pte_val(pte) |= (pmd_val(pmd) & _SEGMENT_ENTRY_WRITE) << 4;
  77                 pte_val(pte) |= (pmd_val(pmd) & _SEGMENT_ENTRY_INVALID) << 5;
  78                 pte_val(pte) |= (pmd_val(pmd) & _SEGMENT_ENTRY_PROTECT);
  79                 pte_val(pte) |= (pmd_val(pmd) & _SEGMENT_ENTRY_DIRTY) >> 10;
  80                 pte_val(pte) |= (pmd_val(pmd) & _SEGMENT_ENTRY_YOUNG) >> 10;
  81         } else
  82                 pte_val(pte) = _PAGE_INVALID;
  83         return pte;
  84 }
  85
  86 void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
  87                      pte_t *ptep, pte_t pte)
  88 {
  89         pmd_t pmd = __pte_to_pmd(pte);
  90
  91         pmd_val(pmd) |= _SEGMENT_ENTRY_LARGE;
  92         *(pmd_t *) ptep = pmd;
  93 }
  94
  95 pte_t huge_ptep_get(pte_t *ptep)
  96 {
  97         pmd_t pmd = *(pmd_t *) ptep;
  98
  99         return __pmd_to_pte(pmd);
 100 }
 101
 102 pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
 103                               unsigned long addr, pte_t *ptep)
 104 {
 105         pmd_t *pmdp = (pmd_t *) ptep;
 106         pte_t pte = huge_ptep_get(ptep);
 107
 108         pmdp_flush_direct(mm, addr, pmdp);
 109         pmd_val(*pmdp) = _SEGMENT_ENTRY_EMPTY;
 110         return pte;
 111 }
 112
 113 pte_t *huge_pte_alloc(struct mm_struct *mm,
 114                         unsigned long addr, unsigned long sz)
 115 {
 116         pgd_t *pgdp;
 117         pud_t *pudp;
 118         pmd_t *pmdp = NULL;
 119
 120         pgdp = pgd_offset(mm, addr);
 121         pudp = pud_alloc(mm, pgdp, addr);
 122         if (pudp)
 123                 pmdp = pmd_alloc(mm, pudp, addr);
 124         return (pte_t *) pmdp;
 125 }
 126
 127 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
 128 {
 129         pgd_t *pgdp;
 130         pud_t *pudp;
 131         pmd_t *pmdp = NULL;
 132
 133         pgdp = pgd_offset(mm, addr);
 134         if (pgd_present(*pgdp)) {
 135                 pudp = pud_offset(pgdp, addr);
 136                 if (pud_present(*pudp))
 137                         pmdp = pmd_offset(pudp, addr);
 138         }
 139         return (pte_t *) pmdp;
 140 }
 141
 142 int pmd_huge(pmd_t pmd)
 143 {
 144         return pmd_large(pmd);
 145 }
 146
 147 int pud_huge(pud_t pud)
 148 {
 149         return 0;
 150 }