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linux
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
31struct mmu_gather {
32 struct mm_struct *mm;
33 struct mmu_table_batch *batch;
34 unsigned int fullmm;
35};
36
37struct mmu_table_batch {
38 struct rcu_head rcu;
39 unsigned int nr;
40 void *tables[0];
41};
42
43#define MAX_TABLE_BATCH \
44 ((PAGE_SIZE - sizeof(struct mmu_table_batch)) / sizeof(void *))
45
46extern void tlb_table_flush(struct mmu_gather *tlb);
47extern void tlb_remove_table(struct mmu_gather *tlb, void *table);
48
49static inline void tlb_gather_mmu(struct mmu_gather *tlb,
50 struct mm_struct *mm,
51 unsigned int full_mm_flush)
52{
53 tlb->mm = mm;
54 tlb->fullmm = full_mm_flush;
55 tlb->batch = NULL;
56 if (tlb->fullmm)
57 __tlb_flush_mm(mm);
58}
59
60static inline void tlb_flush_mmu(struct mmu_gather *tlb)
61{
62 tlb_table_flush(tlb);
63}
64
65static inline void tlb_finish_mmu(struct mmu_gather *tlb,
66 unsigned long start, unsigned long end)
67{
68 tlb_table_flush(tlb);
69}
70
71/*
72 * Release the page cache reference for a pte removed by
73 * tlb_ptep_clear_flush. In both flush modes the tlb for a page cache page
74 * has already been freed, so just do free_page_and_swap_cache.
75 */
76static inline int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
77{
78 free_page_and_swap_cache(page);
79 return 1; /* avoid calling tlb_flush_mmu */
80}
81
82static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
83{
84 free_page_and_swap_cache(page);
85}
86
87/*
88 * pte_free_tlb frees a pte table and clears the CRSTE for the
89 * page table from the tlb.
90 */
91static inline void pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
92 unsigned long address)
93{
94 if (!tlb->fullmm)
95 return page_table_free_rcu(tlb, (unsigned long *) pte);
96 page_table_free(tlb->mm, (unsigned long *) pte);
97}
98
99/*
100 * pmd_free_tlb frees a pmd table and clears the CRSTE for the
101 * segment table entry from the tlb.
102 * If the mm uses a two level page table the single pmd is freed
103 * as the pgd. pmd_free_tlb checks the asce_limit against 2GB
104 * to avoid the double free of the pmd in this case.
105 */
106static inline void pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd,
107 unsigned long address)
108{
109#ifdef CONFIG_64BIT
110 if (tlb->mm->context.asce_limit <= (1UL << 31))
111 return;
112 if (!tlb->fullmm)
113 return tlb_remove_table(tlb, pmd);
114 crst_table_free(tlb->mm, (unsigned long *) pmd);
115#endif
116}
117
118/*
119 * pud_free_tlb frees a pud table and clears the CRSTE for the
120 * region third table entry from the tlb.
121 * If the mm uses a three level page table the single pud is freed
122 * as the pgd. pud_free_tlb checks the asce_limit against 4TB
123 * to avoid the double free of the pud in this case.
124 */
125static inline void pud_free_tlb(struct mmu_gather *tlb, pud_t *pud,
126 unsigned long address)
127{
128#ifdef CONFIG_64BIT
129 if (tlb->mm->context.asce_limit <= (1UL << 42))
130 return;
131 if (!tlb->fullmm)
132 return tlb_remove_table(tlb, pud);
133 crst_table_free(tlb->mm, (unsigned long *) pud);
134#endif
135}
136
137#define tlb_start_vma(tlb, vma) do { } while (0)
138#define tlb_end_vma(tlb, vma) do { } while (0)
139#define tlb_remove_tlb_entry(tlb, ptep, addr) do { } while (0)
140#define tlb_migrate_finish(mm) do { } while (0)
141
142#endif /* _S390_TLB_H */