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 int cpu;
45 struct page * pages[FREE_PTE_NR];
46 };
47
48 /* Users of the generic TLB shootdown code must declare this storage space. */
49 DECLARE_PER_CPU_LOCKED(struct mmu_gather, mmu_gathers);
50
51 /* tlb_gather_mmu
52 * Return a pointer to an initialized struct mmu_gather.
53 */
54 static inline struct mmu_gather *
55 tlb_gather_mmu(struct mm_struct *mm, unsigned int full_mm_flush)
56 {
57 int cpu;
58 struct mmu_gather *tlb = &get_cpu_var_locked(mmu_gathers, &cpu);
59
60 tlb->cpu = cpu;
61 tlb->mm = mm;
62
63 /* Use fast mode if only one CPU is online */
64 tlb->nr = num_online_cpus() > 1 ? 0U : ~0U;
65
66 tlb->fullmm = full_mm_flush;
67
68 return tlb;
69 }
70
71 static inline void
72 tlb_flush_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
73 {
74 if (!tlb->need_flush)
75 return;
76 tlb->need_flush = 0;
77 tlb_flush(tlb);
78 if (!tlb_fast_mode(tlb)) {
79 free_pages_and_swap_cache(tlb->pages, tlb->nr);
80 tlb->nr = 0;
81 }
82 }
83
84 /* tlb_finish_mmu
85 * Called at the end of the shootdown operation to free up any resources
86 * that were required.
87 */
88 static inline void
89 tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
90 {
91 tlb_flush_mmu(tlb, start, end);
92
93 /* keep the page table cache within bounds */
94 check_pgt_cache();
95
96 put_cpu_var_locked(mmu_gathers, tlb->cpu);
97 }
98
99 /* tlb_remove_page
100 * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
101 * handling the additional races in SMP caused by other CPUs caching valid
102 * mappings in their TLBs.
103 */
104 static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
105 {
106 tlb->need_flush = 1;
107 if (tlb_fast_mode(tlb)) {
108 free_page_and_swap_cache(page);
109 return;
110 }
111 tlb->pages[tlb->nr++] = page;
112 if (tlb->nr >= FREE_PTE_NR)
113 tlb_flush_mmu(tlb, 0, 0);
114 }
115
116 /**
117 * tlb_remove_tlb_entry - remember a pte unmapping for later tlb invalidation.
118 *
119 * Record the fact that pte's were really umapped in ->need_flush, so we can
120 * later optimise away the tlb invalidate. This helps when userspace is
121 * unmapping already-unmapped pages, which happens quite a lot.
122 */
123 #define tlb_remove_tlb_entry(tlb, ptep, address) \
124 do { \
125 tlb->need_flush = 1; \
126 __tlb_remove_tlb_entry(tlb, ptep, address); \
127 } while (0)
128
129 #define pte_free_tlb(tlb, ptep) \
130 do { \
131 tlb->need_flush = 1; \
132 __pte_free_tlb(tlb, ptep); \
133 } while (0)
134
135 #ifndef __ARCH_HAS_4LEVEL_HACK
136 #define pud_free_tlb(tlb, pudp) \
137 do { \
138 tlb->need_flush = 1; \
139 __pud_free_tlb(tlb, pudp); \
140 } while (0)
141 #endif
142
143 #define pmd_free_tlb(tlb, pmdp) \
144 do { \
145 tlb->need_flush = 1; \
146 __pmd_free_tlb(tlb, pmdp); \
147 } while (0)
148
149 #define tlb_migrate_finish(mm) do {} while (0)
150
151 #endif /* _ASM_GENERIC__TLB_H */
152
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