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
  12 void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
  13                                    pte_t *pteptr, pte_t pteval)
  14 {
  15         pmd_t *pmdp = (pmd_t *) pteptr;
  16         unsigned long mask;
  17
  18         if (!MACHINE_HAS_HPAGE) {
  19                 pteptr = (pte_t *) pte_page(pteval)[1].index;
  20                 mask = pte_val(pteval) &
  21                                 (_SEGMENT_ENTRY_INV | _SEGMENT_ENTRY_RO);
  22                 pte_val(pteval) = (_SEGMENT_ENTRY + __pa(pteptr)) | mask;
  23         }
  24
  25         pmd_val(*pmdp) = pte_val(pteval);
  26 }
  27
  28 int arch_prepare_hugepage(struct page *page)
  29 {
  30         unsigned long addr = page_to_phys(page);
  31         pte_t pte;
  32         pte_t *ptep;
  33         int i;
  34
  35         if (MACHINE_HAS_HPAGE)
  36                 return 0;
  37
  38         ptep = (pte_t *) pte_alloc_one(&init_mm, addr);
  39         if (!ptep)
  40                 return -ENOMEM;
  41
  42         pte = mk_pte(page, PAGE_RW);
  43         for (i = 0; i < PTRS_PER_PTE; i++) {
  44                 set_pte_at(&init_mm, addr + i * PAGE_SIZE, ptep + i, pte);
  45                 pte_val(pte) += PAGE_SIZE;
  46         }
  47         page[1].index = (unsigned long) ptep;
  48         return 0;
  49 }
  50
  51 void arch_release_hugepage(struct page *page)
  52 {
  53         pte_t *ptep;
  54
  55         if (MACHINE_HAS_HPAGE)
  56                 return;
  57
  58         ptep = (pte_t *) page[1].index;
  59         if (!ptep)
  60                 return;
  61         clear_table((unsigned long *) ptep, _PAGE_TYPE_EMPTY,
  62                     PTRS_PER_PTE * sizeof(pte_t));
  63         page_table_free(&init_mm, (unsigned long *) ptep);
  64         page[1].index = 0;
  65 }
  66
  67 pte_t *huge_pte_alloc(struct mm_struct *mm,
  68                         unsigned long addr, unsigned long sz)
  69 {
  70         pgd_t *pgdp;
  71         pud_t *pudp;
  72         pmd_t *pmdp = NULL;
  73
  74         pgdp = pgd_offset(mm, addr);
  75         pudp = pud_alloc(mm, pgdp, addr);
  76         if (pudp)
  77                 pmdp = pmd_alloc(mm, pudp, addr);
  78         return (pte_t *) pmdp;
  79 }
  80
  81 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
  82 {
  83         pgd_t *pgdp;
  84         pud_t *pudp;
  85         pmd_t *pmdp = NULL;
  86
  87         pgdp = pgd_offset(mm, addr);
  88         if (pgd_present(*pgdp)) {
  89                 pudp = pud_offset(pgdp, addr);
  90                 if (pud_present(*pudp))
  91                         pmdp = pmd_offset(pudp, addr);
  92         }
  93         return (pte_t *) pmdp;
  94 }
  95
  96 int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
  97 {
  98         return 0;
  99 }
 100
 101 struct page *follow_huge_addr(struct mm_struct *mm, unsigned long address,
 102                               int write)
 103 {
 104         return ERR_PTR(-EINVAL);
 105 }
 106
 107 int pmd_huge(pmd_t pmd)
 108 {
 109         if (!MACHINE_HAS_HPAGE)
 110                 return 0;
 111
 112         return !!(pmd_val(pmd) & _SEGMENT_ENTRY_LARGE);
 113 }
 114
 115 int pud_huge(pud_t pud)
 116 {
 117         return 0;
 118 }
 119
 120 struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address,
 121                              pmd_t *pmdp, int write)
 122 {
 123         struct page *page;
 124
 125         if (!MACHINE_HAS_HPAGE)
 126                 return NULL;
 127
 128         page = pmd_page(*pmdp);
 129         if (page)
 130                 page += ((address & ~HPAGE_MASK) >> PAGE_SHIFT);
 131         return page;
 132 }