1 /* include/asm-generic/tlb.h
2 *
3 * Generic TLB shootdown code
4 *
5 * Copyright 2001 Red Hat, Inc.
6 * Based on code from mm/memory.c Copyright Linus Torvalds and others.
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License
10 * as published by the Free Software Foundation; either version
11 * 2 of the License, or (at your option) any later version.
12 */
13 #ifndef _ASM_GENERIC__TLB_H
14 #define _ASM_GENERIC__TLB_H
15
16 #include <linux/swap.h>
17 #include <asm/pgalloc.h>
18 #include <asm/tlbflush.h>
19
20 /*
21 * For UP we don't need to worry about TLB flush
22 * and page free order so much..
23 */
24 #ifdef CONFIG_SMP
25 #ifdef ARCH_FREE_PTR_NR
26 #define FREE_PTR_NR ARCH_FREE_PTR_NR
27 #else
28 #define FREE_PTE_NR 506
29 #endif
30 #define tlb_fast_mode(tlb) ((tlb)->nr == ~0U)
31 #else
32 #define FREE_PTE_NR 1
33 #define tlb_fast_mode(tlb) 1
34 #endif
35
36 /* struct mmu_gather is an opaque type used by the mm code for passing around
37 * any data needed by arch specific code for tlb_remove_page.
38 */
39 struct mmu_gather {
40 struct mm_struct *mm;
41 unsigned int nr; /* set to ~0U means fast mode */
42 unsigned int need_flush;/* Really unmapped some ptes? */
43 unsigned int fullmm; /* non-zero means full mm flush */
44 struct page * pages[FREE_PTE_NR];
45 };
46
47 /* Users of the generic TLB shootdown code must declare this storage space. */
48 DECLARE_PER_CPU(struct mmu_gather, mmu_gathers);
49
50 /* tlb_gather_mmu
51 * Return a pointer to an initialized struct mmu_gather.
52 */
53 static inline struct mmu_gather *
54 tlb_gather_mmu(struct mm_struct *mm, unsigned int full_mm_flush)
55 {
56 struct mmu_gather *tlb = &get_cpu_var(mmu_gathers);
57
58 tlb->mm = mm;
59
60 /* Use fast mode if only one CPU is online */
61 tlb->nr = num_online_cpus() > 1 ? 0U : ~0U;
62
63 tlb->fullmm = full_mm_flush;
64
65 return tlb;
66 }
67
68 static inline void
69 tlb_flush_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
70 {
71 if (!tlb->need_flush)
72 return;
73 tlb->need_flush = 0;
74 tlb_flush(tlb);
75 if (!tlb_fast_mode(tlb)) {
76 free_pages_and_swap_cache(tlb->pages, tlb->nr);
77 tlb->nr = 0;
78 }
79 }
80
81 /* tlb_finish_mmu
82 * Called at the end of the shootdown operation to free up any resources
83 * that were required.
84 */
85 static inline void
86 tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
87 {
88 tlb_flush_mmu(tlb, start, end);
89
90 /* keep the page table cache within bounds */
91 check_pgt_cache();
92
93 put_cpu_var(mmu_gathers);
94 }
95
96 /* tlb_remove_page
97 * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
98 * handling the additional races in SMP caused by other CPUs caching valid
99 * mappings in their TLBs.
100 */
101 static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
102 {
103 tlb->need_flush = 1;
104 if (tlb_fast_mode(tlb)) {
105 free_page_and_swap_cache(page);
106 return;
107 }
108 tlb->pages[tlb->nr++] = page;
109 if (tlb->nr >= FREE_PTE_NR)
110 tlb_flush_mmu(tlb, 0, 0);
111 }
112
113 /**
114 * tlb_remove_tlb_entry - remember a pte unmapping for later tlb invalidation.
115 *
116 * Record the fact that pte's were really umapped in ->need_flush, so we can
117 * later optimise away the tlb invalidate. This helps when userspace is
118 * unmapping already-unmapped pages, which happens quite a lot.
119 */
120 #define tlb_remove_tlb_entry(tlb, ptep, address) \
121 do { \
122 tlb->need_flush = 1; \
123 __tlb_remove_tlb_entry(tlb, ptep, address); \
124 } while (0)
125
126 #define pte_free_tlb(tlb, ptep) \
127 do { \
128 tlb->need_flush = 1; \
129 __pte_free_tlb(tlb, ptep); \
130 } while (0)
131
132 #ifndef __ARCH_HAS_4LEVEL_HACK
133 #define pud_free_tlb(tlb, pudp) \
134 do { \
135 tlb->need_flush = 1; \
136 __pud_free_tlb(tlb, pudp); \
137 } while (0)
138 #endif
139
140 #define pmd_free_tlb(tlb, pmdp) \
141 do { \
142 tlb->need_flush = 1; \
143 __pmd_free_tlb(tlb, pmdp); \
144 } while (0)
145
146 #define tlb_migrate_finish(mm) do {} while (0)
147
148 #endif /* _ASM_GENERIC__TLB_H */
149
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