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   1 /*
   2  *  IBM System z Huge TLB Page Support for Kernel.
   3  *
   4  *    Copyright IBM Corp. 2008
   5  *    Author(s): Gerald Schaefer <gerald.schaefer@de.ibm.com>
   6  */
   7
   8 #ifndef _ASM_S390_HUGETLB_H
   9 #define _ASM_S390_HUGETLB_H
  10
  11 #include <asm/page.h>
  12 #include <asm/pgtable.h>
  13
  14
  15 #define is_hugepage_only_range(mm, addr, len)   0
  16 #define hugetlb_free_pgd_range                  free_pgd_range
  17
  18 void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
  19                      pte_t *ptep, pte_t pte);
  20
  21 /*
  22  * If the arch doesn't supply something else, assume that hugepage
  23  * size aligned regions are ok without further preparation.
  24  */
  25 static inline int prepare_hugepage_range(unsigned long addr, unsigned long len)
  26 {
  27         if (len & ~HPAGE_MASK)
  28                 return -EINVAL;
  29         if (addr & ~HPAGE_MASK)
  30                 return -EINVAL;
  31         return 0;
  32 }
  33
  34 #define hugetlb_prefault_arch_hook(mm)          do { } while (0)
  35
  36 int arch_prepare_hugepage(struct page *page);
  37 void arch_release_hugepage(struct page *page);
  38
  39 static inline pte_t pte_mkhuge(pte_t pte)
  40 {
  41         /*
  42          * PROT_NONE needs to be remapped from the pte type to the ste type.
  43          * The HW invalid bit is also different for pte and ste. The pte
  44          * invalid bit happens to be the same as the ste _SEGMENT_ENTRY_LARGE
  45          * bit, so we don't have to clear it.
  46          */
  47         if (pte_val(pte) & _PAGE_INVALID) {
  48                 if (pte_val(pte) & _PAGE_SWT)
  49                         pte_val(pte) |= _HPAGE_TYPE_NONE;
  50                 pte_val(pte) |= _SEGMENT_ENTRY_INV;
  51         }
  52         /*
  53          * Clear SW pte bits SWT and SWX, there are no SW bits in a segment
  54          * table entry.
  55          */
  56         pte_val(pte) &= ~(_PAGE_SWT | _PAGE_SWX);
  57         /*
  58          * Also set the change-override bit because we don't need dirty bit
  59          * tracking for hugetlbfs pages.
  60          */
  61         pte_val(pte) |= (_SEGMENT_ENTRY_LARGE | _SEGMENT_ENTRY_CO);
  62         return pte;
  63 }
  64
  65 static inline pte_t huge_pte_wrprotect(pte_t pte)
  66 {
  67         pte_val(pte) |= _PAGE_RO;
  68         return pte;
  69 }
  70
  71 static inline int huge_pte_none(pte_t pte)
  72 {
  73         return (pte_val(pte) & _SEGMENT_ENTRY_INV) &&
  74                 !(pte_val(pte) & _SEGMENT_ENTRY_RO);
  75 }
  76
  77 static inline pte_t huge_ptep_get(pte_t *ptep)
  78 {
  79         pte_t pte = *ptep;
  80         unsigned long mask;
  81
  82         if (!MACHINE_HAS_HPAGE) {
  83                 ptep = (pte_t *) (pte_val(pte) & _SEGMENT_ENTRY_ORIGIN);
  84                 if (ptep) {
  85                         mask = pte_val(pte) &
  86                                 (_SEGMENT_ENTRY_INV | _SEGMENT_ENTRY_RO);
  87                         pte = pte_mkhuge(*ptep);
  88                         pte_val(pte) |= mask;
  89                 }
  90         }
  91         return pte;
  92 }
  93
  94 static inline pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
  95                                             unsigned long addr, pte_t *ptep)
  96 {
  97         pte_t pte = huge_ptep_get(ptep);
  98
  99         pmd_clear((pmd_t *) ptep);
 100         return pte;
 101 }
 102
 103 static inline void __pmd_csp(pmd_t *pmdp)
 104 {
 105         register unsigned long reg2 asm("2") = pmd_val(*pmdp);
 106         register unsigned long reg3 asm("3") = pmd_val(*pmdp) |
 107                                                _SEGMENT_ENTRY_INV;
 108         register unsigned long reg4 asm("4") = ((unsigned long) pmdp) + 5;
 109
 110         asm volatile(
 111                 "       csp %1,%3"
 112                 : "=m" (*pmdp)
 113                 : "d" (reg2), "d" (reg3), "d" (reg4), "m" (*pmdp) : "cc");
 114         pmd_val(*pmdp) = _SEGMENT_ENTRY_INV | _SEGMENT_ENTRY;
 115 }
 116
 117 static inline void __pmd_idte(unsigned long address, pmd_t *pmdp)
 118 {
 119         unsigned long sto = (unsigned long) pmdp -
 120                                 pmd_index(address) * sizeof(pmd_t);
 121
 122         if (!(pmd_val(*pmdp) & _SEGMENT_ENTRY_INV)) {
 123                 asm volatile(
 124                         "       .insn   rrf,0xb98e0000,%2,%3,0,0"
 125                         : "=m" (*pmdp)
 126                         : "m" (*pmdp), "a" (sto),
 127                           "a" ((address & HPAGE_MASK))
 128                 );
 129         }
 130         pmd_val(*pmdp) = _SEGMENT_ENTRY_INV | _SEGMENT_ENTRY;
 131 }
 132
 133 static inline void huge_ptep_invalidate(struct mm_struct *mm,
 134                                         unsigned long address, pte_t *ptep)
 135 {
 136         pmd_t *pmdp = (pmd_t *) ptep;
 137
 138         if (!MACHINE_HAS_IDTE) {
 139                 __pmd_csp(pmdp);
 140                 if (mm->context.noexec) {
 141                         pmdp = get_shadow_table(pmdp);
 142                         __pmd_csp(pmdp);
 143                 }
 144                 return;
 145         }
 146
 147         __pmd_idte(address, pmdp);
 148         if (mm->context.noexec) {
 149                 pmdp = get_shadow_table(pmdp);
 150                 __pmd_idte(address, pmdp);
 151         }
 152         return;
 153 }
 154
 155 #define huge_ptep_set_access_flags(__vma, __addr, __ptep, __entry, __dirty) \
 156 ({                                                                          \
 157         int __changed = !pte_same(huge_ptep_get(__ptep), __entry);          \
 158         if (__changed) {                                                    \
 159                 huge_ptep_invalidate((__vma)->vm_mm, __addr, __ptep);       \
 160                 set_huge_pte_at((__vma)->vm_mm, __addr, __ptep, __entry);   \
 161         }                                                                   \
 162         __changed;                                                          \
 163 })
 164
 165 #define huge_ptep_set_wrprotect(__mm, __addr, __ptep)                   \
 166 ({                                                                      \
 167         pte_t __pte = huge_ptep_get(__ptep);                            \
 168         if (pte_write(__pte)) {                                         \
 169                 if (atomic_read(&(__mm)->mm_users) > 1 ||               \
 170                     (__mm) != current->active_mm)                       \
 171                         huge_ptep_invalidate(__mm, __addr, __ptep);     \
 172                 set_huge_pte_at(__mm, __addr, __ptep,                   \
 173                                 huge_pte_wrprotect(__pte));             \
 174         }                                                               \
 175 })
 176
 177 static inline void huge_ptep_clear_flush(struct vm_area_struct *vma,
 178                                          unsigned long address, pte_t *ptep)
 179 {
 180         huge_ptep_invalidate(vma->vm_mm, address, ptep);
 181 }
 182
 183 #endif /* _ASM_S390_HUGETLB_H */