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 tlb_gather_mmu(struct mmu_gather *tlb,
  51                                   struct mm_struct *mm,
  52                                   unsigned long start,
  53                                   unsigned long end)
  54 {
  55         tlb->mm = mm;
  56         tlb->start = start;
  57         tlb->end = end;
  58         tlb->fullmm = !(start | (end+1));
  59         tlb->batch = NULL;
  60 }
  61
  62 static inline void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
  63 {
  64         __tlb_flush_mm_lazy(tlb->mm);
  65 }
  66
  67 static inline void tlb_flush_mmu_free(struct mmu_gather *tlb)
  68 {
  69         tlb_table_flush(tlb);
  70 }
  71
  72
  73 static inline void tlb_flush_mmu(struct mmu_gather *tlb)
  74 {
  75         tlb_flush_mmu_tlbonly(tlb);
  76         tlb_flush_mmu_free(tlb);
  77 }
  78
  79 static inline void tlb_finish_mmu(struct mmu_gather *tlb,
  80                                   unsigned long start, unsigned long end)
  81 {
  82         tlb_flush_mmu(tlb);
  83 }
  84
  85 /*
  86  * Release the page cache reference for a pte removed by
  87  * tlb_ptep_clear_flush. In both flush modes the tlb for a page cache page
  88  * has already been freed, so just do free_page_and_swap_cache.
  89  */
  90 static inline int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
  91 {
  92         free_page_and_swap_cache(page);
  93         return 1; /* avoid calling tlb_flush_mmu */
  94 }
  95
  96 static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
  97 {
  98         free_page_and_swap_cache(page);
  99 }
 100
 101 /*
 102  * pte_free_tlb frees a pte table and clears the CRSTE for the
 103  * page table from the tlb.
 104  */
 105 static inline void pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
 106                                 unsigned long address)
 107 {
 108         page_table_free_rcu(tlb, (unsigned long *) pte, address);
 109 }
 110
 111 /*
 112  * pmd_free_tlb frees a pmd table and clears the CRSTE for the
 113  * segment table entry from the tlb.
 114  * If the mm uses a two level page table the single pmd is freed
 115  * as the pgd. pmd_free_tlb checks the asce_limit against 2GB
 116  * to avoid the double free of the pmd in this case.
 117  */
 118 static inline void pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd,
 119                                 unsigned long address)
 120 {
 121         if (tlb->mm->context.asce_limit <= (1UL << 31))
 122                 return;
 123         pgtable_pmd_page_dtor(virt_to_page(pmd));
 124         tlb_remove_table(tlb, pmd);
 125 }
 126
 127 /*
 128  * pud_free_tlb frees a pud table and clears the CRSTE for the
 129  * region third table entry from the tlb.
 130  * If the mm uses a three level page table the single pud is freed
 131  * as the pgd. pud_free_tlb checks the asce_limit against 4TB
 132  * to avoid the double free of the pud in this case.
 133  */
 134 static inline void pud_free_tlb(struct mmu_gather *tlb, pud_t *pud,
 135                                 unsigned long address)
 136 {
 137         if (tlb->mm->context.asce_limit <= (1UL << 42))
 138                 return;
 139         tlb_remove_table(tlb, pud);
 140 }
 141
 142 #define tlb_start_vma(tlb, vma)                 do { } while (0)
 143 #define tlb_end_vma(tlb, vma)                   do { } while (0)
 144 #define tlb_remove_tlb_entry(tlb, ptep, addr)   do { } while (0)
 145 #define tlb_remove_pmd_tlb_entry(tlb, pmdp, addr)       do { } while (0)
 146 #define tlb_migrate_finish(mm)                  do { } while (0)
 147
 148 #endif /* _S390_TLB_H */