Linux Kernel  3.7.1
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hugetlbpage.c
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1 /*
2  * IBM System z Huge TLB Page Support for Kernel.
3  *
4  * Copyright IBM Corp. 2007
5  * Author(s): Gerald Schaefer <[email protected]>
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 }
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