arch/s390/include/asm/tlb.h

   1 #ifndef _S390_TLB_H
   2 #define _S390_TLB_H
   3
   4 /*
   5  * TLB flushing on s390 is complicated. The following requirement
   6  * from the principles of operation is the most arduous:
   7  *
   8  * "A valid table entry must not be changed while it is attached
   9  * to any CPU and may be used for translation by that CPU except to
  10  * (1) invalidate the entry by using INVALIDATE PAGE TABLE ENTRY,
  11  * or INVALIDATE DAT TABLE ENTRY, (2) alter bits 56-63 of a page
  12  * table entry, or (3) make a change by means of a COMPARE AND SWAP
  13  * AND PURGE instruction that purges the TLB."
  14  *
  15  * The modification of a pte of an active mm struct therefore is
  16  * a two step process: i) invalidate the pte, ii) store the new pte.
  17  * This is true for the page protection bit as well.
  18  * The only possible optimization is to flush at the beginning of
  19  * a tlb_gather_mmu cycle if the mm_struct is currently not in use.
  20  *
  21  * Pages used for the page tables is a different story. FIXME: more
  22  */
  23
  24 #include <linux/mm.h>
  25 #include <linux/pagemap.h>
  26 #include <linux/swap.h>
  27 #include <asm/processor.h>
  28 #include <asm/pgalloc.h>
  29 #include <asm/tlbflush.h>
  30
  31 struct mmu_gather {
  32         struct mm_struct *mm;
  33         struct mmu_table_batch *batch;
  34         unsigned int fullmm;
  35         unsigned long start, end;
  36 };
  37
  38 struct mmu_table_batch {
  39         struct rcu_head         rcu;
  40         unsigned int            nr;
  41         void                    *tables[0];
  42 };
  43
  44 #define MAX_TABLE_BATCH         \
  45         ((PAGE_SIZE - sizeof(struct mmu_table_batch)) / sizeof(void *))
  46
  47 extern void tlb_table_flush(struct mmu_gather *tlb);
  48 extern void tlb_remove_table(struct mmu_gather *tlb, void *table);
  49
  50 static inline void
  51 arch_tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
  52                         unsigned long start, unsigned long end)
  53 {
  54         tlb->mm = mm;
  55         tlb->start = start;
  56         tlb->end = end;
  57         tlb->fullmm = !(start | (end+1));
  58         tlb->batch = NULL;
  59 }
  60
  61 static inline void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
  62 {
  63         __tlb_flush_mm_lazy(tlb->mm);
  64 }
  65
  66 static inline void tlb_flush_mmu_free(struct mmu_gather *tlb)
  67 {
  68         tlb_table_flush(tlb);
  69 }
  70
  71
  72 static inline void tlb_flush_mmu(struct mmu_gather *tlb)
  73 {
  74         tlb_flush_mmu_tlbonly(tlb);
  75         tlb_flush_mmu_free(tlb);
  76 }
  77
  78 static inline void
  79 arch_tlb_finish_mmu(struct mmu_gather *tlb,
  80                 unsigned long start, unsigned long end, bool force)
  81 {
  82         if (force) {
  83                 tlb->start = start;
  84                 tlb->end = end;
  85         }
  86
  87         tlb_flush_mmu(tlb);
  88 }
  89
  90 /*
  91  * Release the page cache reference for a pte removed by
  92  * tlb_ptep_clear_flush. In both flush modes the tlb for a page cache page
  93  * has already been freed, so just do free_page_and_swap_cache.
  94  */
  95 static inline bool __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
  96 {
  97         free_page_and_swap_cache(page);
  98         return false; /* avoid calling tlb_flush_mmu */
  99 }
 100
 101 static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 102 {
 103         free_page_and_swap_cache(page);
 104 }
 105
 106 static inline bool __tlb_remove_page_size(struct mmu_gather *tlb,
 107                                           struct page *page, int page_size)
 108 {
 109         return __tlb_remove_page(tlb, page);
 110 }
 111
 112 static inline void tlb_remove_page_size(struct mmu_gather *tlb,
 113                                         struct page *page, int page_size)
 114 {
 115         return tlb_remove_page(tlb, page);
 116 }
 117
 118 /*
 119  * pte_free_tlb frees a pte table and clears the CRSTE for the
 120  * page table from the tlb.
 121  */
 122 static inline void pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
 123                                 unsigned long address)
 124 {
 125         page_table_free_rcu(tlb, (unsigned long *) pte, address);
 126 }
 127
 128 /*
 129  * pmd_free_tlb frees a pmd table and clears the CRSTE for the
 130  * segment table entry from the tlb.
 131  * If the mm uses a two level page table the single pmd is freed
 132  * as the pgd. pmd_free_tlb checks the asce_limit against 2GB
 133  * to avoid the double free of the pmd in this case.
 134  */
 135 static inline void pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd,
 136                                 unsigned long address)
 137 {
 138         if (tlb->mm->context.asce_limit <= _REGION3_SIZE)
 139                 return;
 140         pgtable_pmd_page_dtor(virt_to_page(pmd));
 141         tlb_remove_table(tlb, pmd);
 142 }
 143
 144 /*
 145  * p4d_free_tlb frees a pud table and clears the CRSTE for the
 146  * region second table entry from the tlb.
 147  * If the mm uses a four level page table the single p4d is freed
 148  * as the pgd. p4d_free_tlb checks the asce_limit against 8PB
 149  * to avoid the double free of the p4d in this case.
 150  */
 151 static inline void p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d,
 152                                 unsigned long address)
 153 {
 154         if (tlb->mm->context.asce_limit <= _REGION1_SIZE)
 155                 return;
 156         tlb_remove_table(tlb, p4d);
 157 }
 158
 159 /*
 160  * pud_free_tlb frees a pud table and clears the CRSTE for the
 161  * region third table entry from the tlb.
 162  * If the mm uses a three level page table the single pud is freed
 163  * as the pgd. pud_free_tlb checks the asce_limit against 4TB
 164  * to avoid the double free of the pud in this case.
 165  */
 166 static inline void pud_free_tlb(struct mmu_gather *tlb, pud_t *pud,
 167                                 unsigned long address)
 168 {
 169         if (tlb->mm->context.asce_limit <= _REGION2_SIZE)
 170                 return;
 171         tlb_remove_table(tlb, pud);
 172 }
 173
 174 #define tlb_start_vma(tlb, vma)                 do { } while (0)
 175 #define tlb_end_vma(tlb, vma)                   do { } while (0)
 176 #define tlb_remove_tlb_entry(tlb, ptep, addr)   do { } while (0)
 177 #define tlb_remove_pmd_tlb_entry(tlb, pmdp, addr)       do { } while (0)
 178 #define tlb_migrate_finish(mm)                  do { } while (0)
 179 #define tlb_remove_huge_tlb_entry(h, tlb, ptep, address)        \
 180         tlb_remove_tlb_entry(tlb, ptep, address)
 181
 182 #define tlb_remove_check_page_size_change tlb_remove_check_page_size_change
 183 static inline void tlb_remove_check_page_size_change(struct mmu_gather *tlb,
 184                                                      unsigned int page_size)
 185 {
 186 }
 187
 188 #endif /* _S390_TLB_H */