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, unsigned long addr) 76 { 77 pgd_t *pgdp; 78 pud_t *pudp; 79 pmd_t *pmdp = NULL; 80 81 pgdp = pgd_offset(mm, addr); 82 pudp = pud_alloc(mm, pgdp, addr); 83 if (pudp) 84 pmdp = pmd_alloc(mm, pudp, addr); 85 return (pte_t *) pmdp; 86 } 87 88 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr) 89 { 90 pgd_t *pgdp; 91 pud_t *pudp; 92 pmd_t *pmdp = NULL; 93 94 pgdp = pgd_offset(mm, addr); 95 if (pgd_present(*pgdp)) { 96 pudp = pud_offset(pgdp, addr); 97 if (pud_present(*pudp)) 98 pmdp = pmd_offset(pudp, addr); 99 } 100 return (pte_t *) pmdp; 101 } 102 103 int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep) 104 { 105 return 0; 106 } 107 108 struct page *follow_huge_addr(struct mm_struct *mm, unsigned long address, 109 int write) 110 { 111 return ERR_PTR(-EINVAL); 112 } 113 114 int pmd_huge(pmd_t pmd) 115 { 116 if (!MACHINE_HAS_HPAGE) 117 return 0; 118 119 return !!(pmd_val(pmd) & _SEGMENT_ENTRY_LARGE); 120 } 121 122 struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address, 123 pmd_t *pmdp, int write) 124 { 125 struct page *page; 126 127 if (!MACHINE_HAS_HPAGE) 128 return NULL; 129 130 page = pmd_page(*pmdp); 131 if (page) 132 page += ((address & ~HPAGE_MASK) >> PAGE_SHIFT); 133 return page; 134 } 135