1 /* 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/config.h>
17 #include <linux/swap.h>
18 #include <asm/pgalloc.h>
19 #include <asm/tlbflush.h>
20
21 /*
22 * For UP we don't need to worry about TLB flush
23 * and page free order so much..
24 */
25 #ifdef CONFIG_SMP
26 #define FREE_PTE_NR 506
27 #define tlb_fast_mode(tlb) ((tlb)->nr == ~0U)
28 #else
29 #define FREE_PTE_NR 1
30 #define tlb_fast_mode(tlb) 1
31 #endif
32
33 /* struct mmu_gather is an opaque type used by the mm code for passing around
34 * any data needed by arch specific code for tlb_remove_page. This structure
35 * can be per-CPU or per-MM as the page table lock is held for the duration of
36 * TLB shootdown.
37 */
38 struct mmu_gather {
39 struct mm_struct *mm;
40 unsigned int nr; /* set to ~0U means fast mode */
41 unsigned int need_flush;/* Really unmapped some ptes? */
42 unsigned int fullmm; /* non-zero means full mm flush */
43 unsigned long freed;
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 = &per_cpu(mmu_gathers, smp_processor_id());
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 tlb->freed = 0;
65
66 return tlb;
67 }
68
69 static inline void
70 tlb_flush_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
71 {
72 if (!tlb->need_flush)
73 return;
74 tlb->need_flush = 0;
75 tlb_flush(tlb);
76 if (!tlb_fast_mode(tlb)) {
77 free_pages_and_swap_cache(tlb->pages, tlb->nr);
78 tlb->nr = 0;
79 }
80 }
81
82 /* tlb_finish_mmu
83 * Called at the end of the shootdown operation to free up any resources
84 * that were required. The page table lock is still held at this point.
85 */
86 static inline void
87 tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
88 {
89 int freed = tlb->freed;
90 struct mm_struct *mm = tlb->mm;
91 int rss = mm->rss;
92
93 if (rss < freed)
94 freed = rss;
95 mm->rss = rss - freed;
96 tlb_flush_mmu(tlb, start, end);
97
98 /* keep the page table cache within bounds */
99 check_pgt_cache();
100 }
101
102 static inline unsigned int
103 tlb_is_full_mm(struct mmu_gather *tlb)
104 {
105 return tlb->fullmm;
106 }
107
108 /* tlb_remove_page
109 * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
110 * handling the additional races in SMP caused by other CPUs caching valid
111 * mappings in their TLBs.
112 */
113 static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
114 {
115 tlb->need_flush = 1;
116 if (tlb_fast_mode(tlb)) {
117 free_page_and_swap_cache(page);
118 return;
119 }
120 tlb->pages[tlb->nr++] = page;
121 if (tlb->nr >= FREE_PTE_NR)
122 tlb_flush_mmu(tlb, 0, 0);
123 }
124
125 /**
126 * tlb_remove_tlb_entry - remember a pte unmapping for later tlb invalidation.
127 *
128 * Record the fact that pte's were really umapped in ->need_flush, so we can
129 * later optimise away the tlb invalidate. This helps when userspace is
130 * unmapping already-unmapped pages, which happens quite a lot.
131 */
132 #define tlb_remove_tlb_entry(tlb, ptep, address) \
133 do { \
134 tlb->need_flush = 1; \
135 __tlb_remove_tlb_entry(tlb, ptep, address); \
136 } while (0)
137
138 #define pte_free_tlb(tlb, ptep) \
139 do { \
140 tlb->need_flush = 1; \
141 __pte_free_tlb(tlb, ptep); \
142 } while (0)
143
144 #ifndef __ARCH_HAS_4LEVEL_HACK
145 #define pud_free_tlb(tlb, pudp) \
146 do { \
147 tlb->need_flush = 1; \
148 __pud_free_tlb(tlb, pudp); \
149 } while (0)
150 #endif
151
152 #define pmd_free_tlb(tlb, pmdp) \
153 do { \
154 tlb->need_flush = 1; \
155 __pmd_free_tlb(tlb, pmdp); \
156 } while (0)
157
158 #define tlb_migrate_finish(mm) do {} while (0)
159
160 #endif /* _ASM_GENERIC__TLB_H */
161
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