linux/arch/s390/mm/hugetlbpage.c
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   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
  12void 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
  38int 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
  61void 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        page_table_free(&init_mm, (unsigned long *) ptep);
  72        page[1].index = 0;
  73}
  74
  75pte_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
  89pte_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
 104int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
 105{
 106        return 0;
 107}
 108
 109struct page *follow_huge_addr(struct mm_struct *mm, unsigned long address,
 110                              int write)
 111{
 112        return ERR_PTR(-EINVAL);
 113}
 114
 115int 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
 123int pud_huge(pud_t pud)
 124{
 125        return 0;
 126}
 127
 128struct 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}
 141