arch/s390/mm/hugetlbpage.c

   1 /*
   2  *  IBM System z Huge TLB Page Support for Kernel.
   3  *
   4  *    Copyright 2007 IBM Corp.
   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         pte_t shadow_pteval = pteval;
  17         unsigned long mask;
  18
  19         if (!MACHINE_HAS_HPAGE) {
  20                 pteptr = (pte_t *) pte_page(pteval)[1].index;
  21                 mask = pte_val(pteval) &
  22                                 (_SEGMENT_ENTRY_INV | _SEGMENT_ENTRY_RO);
  23                 pte_val(pteval) = (_SEGMENT_ENTRY + __pa(pteptr)) | mask;
  24                 if (mm->context.noexec) {
  25                         pteptr += PTRS_PER_PTE;
  26                         pte_val(shadow_pteval) =
  27                                         (_SEGMENT_ENTRY + __pa(pteptr)) | mask;
  28                 }
  29         }
  30
  31         pmd_val(*pmdp) = pte_val(pteval);
  32         if (mm->context.noexec) {
  33                 pmdp = get_shadow_table(pmdp);
  34                 pmd_val(*pmdp) = pte_val(shadow_pteval);
  35         }
  36 }
  37
  38 int arch_prepare_hugepage(struct page *page)
  39 {
  40         unsigned long addr = page_to_phys(page);
  41         pte_t pte;
  42         pte_t *ptep;
  43         int i;
  44
  45         if (MACHINE_HAS_HPAGE)
  46                 return 0;
  47
  48         ptep = (pte_t *) pte_alloc_one(&init_mm, address);
  49         if (!ptep)
  50                 return -ENOMEM;
  51
  52         pte = mk_pte(page, PAGE_RW);
  53         for (i = 0; i < PTRS_PER_PTE; i++) {
  54                 set_pte_at(&init_mm, addr + i * PAGE_SIZE, ptep + i, pte);
  55                 pte_val(pte) += PAGE_SIZE;
  56         }
  57         page[1].index = (unsigned long) ptep;
  58         return 0;
  59 }
  60
  61 void arch_release_hugepage(struct page *page)
  62 {
  63         pte_t *ptep;
  64
  65         if (MACHINE_HAS_HPAGE)
  66                 return;
  67
  68         ptep = (pte_t *) page[1].index;
  69         if (!ptep)
  70                 return;
  71         pte_free(&init_mm, ptep);
  72         page[1].index = 0;
  73 }
  74
  75 pte_t *huge_pte_alloc(struct mm_struct *mm,
  76                         unsigned long addr, unsigned long sz)
  77 {
  78         pgd_t *pgdp;
  79         pud_t *pudp;
  80         pmd_t *pmdp = NULL;
  81
  82         pgdp = pgd_offset(mm, addr);
  83         pudp = pud_alloc(mm, pgdp, addr);
  84         if (pudp)
  85                 pmdp = pmd_alloc(mm, pudp, addr);
  86         return (pte_t *) pmdp;
  87 }
  88
  89 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
  90 {
  91         pgd_t *pgdp;
  92         pud_t *pudp;
  93         pmd_t *pmdp = NULL;
  94
  95         pgdp = pgd_offset(mm, addr);
  96         if (pgd_present(*pgdp)) {
  97                 pudp = pud_offset(pgdp, addr);
  98                 if (pud_present(*pudp))
  99                         pmdp = pmd_offset(pudp, addr);
 100         }
 101         return (pte_t *) pmdp;
 102 }
 103
 104 int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
 105 {
 106         return 0;
 107 }
 108
 109 struct page *follow_huge_addr(struct mm_struct *mm, unsigned long address,
 110                               int write)
 111 {
 112         return ERR_PTR(-EINVAL);
 113 }
 114
 115 int pmd_huge(pmd_t pmd)
 116 {
 117         if (!MACHINE_HAS_HPAGE)
 118                 return 0;
 119
 120         return !!(pmd_val(pmd) & _SEGMENT_ENTRY_LARGE);
 121 }
 122
 123 int pud_huge(pud_t pud)
 124 {
 125         return 0;
 126 }
 127
 128 struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address,
 129                              pmd_t *pmdp, int write)
 130 {
 131         struct page *page;
 132
 133         if (!MACHINE_HAS_HPAGE)
 134                 return NULL;
 135
 136         page = pmd_page(*pmdp);
 137         if (page)
 138                 page += ((address & ~HPAGE_MASK) >> PAGE_SHIFT);
 139         return page;
 140 }