LXR linux/arch/s390/include/asm/tlb.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef _S390_TLB_H
   3#define _S390_TLB_H
   4
   5/*
   6 * TLB flushing on s390 is complicated. The following requirement
   7 * from the principles of operation is the most arduous:
   8 *
   9 * "A valid table entry must not be changed while it is attached
  10 * to any CPU and may be used for translation by that CPU except to
  11 * (1) invalidate the entry by using INVALIDATE PAGE TABLE ENTRY,
  12 * or INVALIDATE DAT TABLE ENTRY, (2) alter bits 56-63 of a page
  13 * table entry, or (3) make a change by means of a COMPARE AND SWAP
  14 * AND PURGE instruction that purges the TLB."
  15 *
  16 * The modification of a pte of an active mm struct therefore is
  17 * a two step process: i) invalidate the pte, ii) store the new pte.
  18 * This is true for the page protection bit as well.
  19 * The only possible optimization is to flush at the beginning of
  20 * a tlb_gather_mmu cycle if the mm_struct is currently not in use.
  21 *
  22 * Pages used for the page tables is a different story. FIXME: more
  23 */
  24
  25void __tlb_remove_table(void *_table);
  26static inline void tlb_flush(struct mmu_gather *tlb);
  27static inline bool __tlb_remove_page_size(struct mmu_gather *tlb,
  28                                          struct page *page, int page_size);
  29
  30#define tlb_start_vma(tlb, vma)                 do { } while (0)
  31#define tlb_end_vma(tlb, vma)                   do { } while (0)
  32
  33#define tlb_flush tlb_flush
  34#define pte_free_tlb pte_free_tlb
  35#define pmd_free_tlb pmd_free_tlb
  36#define p4d_free_tlb p4d_free_tlb
  37#define pud_free_tlb pud_free_tlb
  38
  39#include <asm/pgalloc.h>
  40#include <asm/tlbflush.h>
  41#include <asm-generic/tlb.h>
  42
  43/*
  44 * Release the page cache reference for a pte removed by
  45 * tlb_ptep_clear_flush. In both flush modes the tlb for a page cache page
  46 * has already been freed, so just do free_page_and_swap_cache.
  47 */
  48static inline bool __tlb_remove_page_size(struct mmu_gather *tlb,
  49                                          struct page *page, int page_size)
  50{
  51        free_page_and_swap_cache(page);
  52        return false;
  53}
  54
  55static inline void tlb_flush(struct mmu_gather *tlb)
  56{
  57        __tlb_flush_mm_lazy(tlb->mm);
  58}
  59
  60/*
  61 * pte_free_tlb frees a pte table and clears the CRSTE for the
  62 * page table from the tlb.
  63 */
  64static inline void pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
  65                                unsigned long address)
  66{
  67        __tlb_adjust_range(tlb, address, PAGE_SIZE);
  68        tlb->mm->context.flush_mm = 1;
  69        tlb->freed_tables = 1;
  70        tlb->cleared_pmds = 1;
  71        /*
  72         * page_table_free_rcu takes care of the allocation bit masks
  73         * of the 2K table fragments in the 4K page table page,
  74         * then calls tlb_remove_table.
  75         */
  76        page_table_free_rcu(tlb, (unsigned long *) pte, address);
  77}
  78
  79/*
  80 * pmd_free_tlb frees a pmd table and clears the CRSTE for the
  81 * segment table entry from the tlb.
  82 * If the mm uses a two level page table the single pmd is freed
  83 * as the pgd. pmd_free_tlb checks the asce_limit against 2GB
  84 * to avoid the double free of the pmd in this case.
  85 */
  86static inline void pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd,
  87                                unsigned long address)
  88{
  89        if (mm_pmd_folded(tlb->mm))
  90                return;
  91        pgtable_pmd_page_dtor(virt_to_page(pmd));
  92        __tlb_adjust_range(tlb, address, PAGE_SIZE);
  93        tlb->mm->context.flush_mm = 1;
  94        tlb->freed_tables = 1;
  95        tlb->cleared_puds = 1;
  96        tlb_remove_table(tlb, pmd);
  97}
  98
  99/*
 100 * p4d_free_tlb frees a pud table and clears the CRSTE for the
 101 * region second table entry from the tlb.
 102 * If the mm uses a four level page table the single p4d is freed
 103 * as the pgd. p4d_free_tlb checks the asce_limit against 8PB
 104 * to avoid the double free of the p4d in this case.
 105 */
 106static inline void p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d,
 107                                unsigned long address)
 108{
 109        if (mm_p4d_folded(tlb->mm))
 110                return;
 111        __tlb_adjust_range(tlb, address, PAGE_SIZE);
 112        tlb->mm->context.flush_mm = 1;
 113        tlb->freed_tables = 1;
 114        tlb_remove_table(tlb, p4d);
 115}
 116
 117/*
 118 * pud_free_tlb frees a pud table and clears the CRSTE for the
 119 * region third table entry from the tlb.
 120 * If the mm uses a three level page table the single pud is freed
 121 * as the pgd. pud_free_tlb checks the asce_limit against 4TB
 122 * to avoid the double free of the pud in this case.
 123 */
 124static inline void pud_free_tlb(struct mmu_gather *tlb, pud_t *pud,
 125                                unsigned long address)
 126{
 127        if (mm_pud_folded(tlb->mm))
 128                return;
 129        tlb->mm->context.flush_mm = 1;
 130        tlb->freed_tables = 1;
 131        tlb->cleared_p4ds = 1;
 132        tlb_remove_table(tlb, pud);
 133}
 134
 135
 136#endif /* _S390_TLB_H */
 137