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	unsigned long start, end;
36};
37
38struct 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
47extern void tlb_table_flush(struct mmu_gather *tlb);
48extern void tlb_remove_table(struct mmu_gather *tlb, void *table);
49
50static 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
62static inline void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
63{
64	__tlb_flush_mm_lazy(tlb->mm);
65}
66
67static inline void tlb_flush_mmu_free(struct mmu_gather *tlb)
68{
69	tlb_table_flush(tlb);
70}
71
72
73static inline void tlb_flush_mmu(struct mmu_gather *tlb)
74{
75	tlb_flush_mmu_tlbonly(tlb);
76	tlb_flush_mmu_free(tlb);
77}
78
79static 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 */
90static 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
96static 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 */
105static 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 */
118static inline void pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd,
119				unsigned long address)
120{
121#ifdef CONFIG_64BIT
122	if (tlb->mm->context.asce_limit <= (1UL << 31))
123		return;
124	tlb_remove_table(tlb, pmd);
125#endif
126}
127
128/*
129 * pud_free_tlb frees a pud table and clears the CRSTE for the
130 * region third table entry from the tlb.
131 * If the mm uses a three level page table the single pud is freed
132 * as the pgd. pud_free_tlb checks the asce_limit against 4TB
133 * to avoid the double free of the pud in this case.
134 */
135static inline void pud_free_tlb(struct mmu_gather *tlb, pud_t *pud,
136				unsigned long address)
137{
138#ifdef CONFIG_64BIT
139	if (tlb->mm->context.asce_limit <= (1UL << 42))
140		return;
141	tlb_remove_table(tlb, pud);
142#endif
143}
144
145#define tlb_start_vma(tlb, vma)			do { } while (0)
146#define tlb_end_vma(tlb, vma)			do { } while (0)
147#define tlb_remove_tlb_entry(tlb, ptep, addr)	do { } while (0)
148#define tlb_remove_pmd_tlb_entry(tlb, pmdp, addr)	do { } while (0)
149#define tlb_migrate_finish(mm)			do { } while (0)
150
151#endif /* _S390_TLB_H */
152