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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 | |
2b4a0815 AK |
26 | #ifdef ARCH_FREE_PTR_NR |
27 | #define FREE_PTR_NR ARCH_FREE_PTR_NR | |
28 | #else | |
29 | #define FREE_PTE_NR 506 | |
30 | #endif | |
1da177e4 LT |
31 | #define tlb_fast_mode(tlb) ((tlb)->nr == ~0U) |
32 | #else | |
33 | #define FREE_PTE_NR 1 | |
34 | #define tlb_fast_mode(tlb) 1 | |
35 | #endif | |
36 | ||
37 | /* struct mmu_gather is an opaque type used by the mm code for passing around | |
38 | * any data needed by arch specific code for tlb_remove_page. This structure | |
39 | * can be per-CPU or per-MM as the page table lock is held for the duration of | |
40 | * TLB shootdown. | |
41 | */ | |
42 | struct mmu_gather { | |
43 | struct mm_struct *mm; | |
44 | unsigned int nr; /* set to ~0U means fast mode */ | |
45 | unsigned int need_flush;/* Really unmapped some ptes? */ | |
46 | unsigned int fullmm; /* non-zero means full mm flush */ | |
47 | unsigned long freed; | |
48 | struct page * pages[FREE_PTE_NR]; | |
49 | }; | |
50 | ||
51 | /* Users of the generic TLB shootdown code must declare this storage space. */ | |
52 | DECLARE_PER_CPU(struct mmu_gather, mmu_gathers); | |
53 | ||
54 | /* tlb_gather_mmu | |
55 | * Return a pointer to an initialized struct mmu_gather. | |
56 | */ | |
57 | static inline struct mmu_gather * | |
58 | tlb_gather_mmu(struct mm_struct *mm, unsigned int full_mm_flush) | |
59 | { | |
60 | struct mmu_gather *tlb = &per_cpu(mmu_gathers, smp_processor_id()); | |
61 | ||
62 | tlb->mm = mm; | |
63 | ||
64 | /* Use fast mode if only one CPU is online */ | |
65 | tlb->nr = num_online_cpus() > 1 ? 0U : ~0U; | |
66 | ||
67 | tlb->fullmm = full_mm_flush; | |
68 | tlb->freed = 0; | |
69 | ||
70 | return tlb; | |
71 | } | |
72 | ||
73 | static inline void | |
74 | tlb_flush_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end) | |
75 | { | |
76 | if (!tlb->need_flush) | |
77 | return; | |
78 | tlb->need_flush = 0; | |
79 | tlb_flush(tlb); | |
80 | if (!tlb_fast_mode(tlb)) { | |
81 | free_pages_and_swap_cache(tlb->pages, tlb->nr); | |
82 | tlb->nr = 0; | |
83 | } | |
84 | } | |
85 | ||
86 | /* tlb_finish_mmu | |
87 | * Called at the end of the shootdown operation to free up any resources | |
88 | * that were required. The page table lock is still held at this point. | |
89 | */ | |
90 | static inline void | |
91 | tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end) | |
92 | { | |
93 | int freed = tlb->freed; | |
94 | struct mm_struct *mm = tlb->mm; | |
95 | int rss = get_mm_counter(mm, rss); | |
96 | ||
97 | if (rss < freed) | |
98 | freed = rss; | |
99 | add_mm_counter(mm, rss, -freed); | |
100 | tlb_flush_mmu(tlb, start, end); | |
101 | ||
102 | /* keep the page table cache within bounds */ | |
103 | check_pgt_cache(); | |
104 | } | |
105 | ||
106 | static inline unsigned int | |
107 | tlb_is_full_mm(struct mmu_gather *tlb) | |
108 | { | |
109 | return tlb->fullmm; | |
110 | } | |
111 | ||
112 | /* tlb_remove_page | |
113 | * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while | |
114 | * handling the additional races in SMP caused by other CPUs caching valid | |
115 | * mappings in their TLBs. | |
116 | */ | |
117 | static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page) | |
118 | { | |
119 | tlb->need_flush = 1; | |
120 | if (tlb_fast_mode(tlb)) { | |
121 | free_page_and_swap_cache(page); | |
122 | return; | |
123 | } | |
124 | tlb->pages[tlb->nr++] = page; | |
125 | if (tlb->nr >= FREE_PTE_NR) | |
126 | tlb_flush_mmu(tlb, 0, 0); | |
127 | } | |
128 | ||
129 | /** | |
130 | * tlb_remove_tlb_entry - remember a pte unmapping for later tlb invalidation. | |
131 | * | |
132 | * Record the fact that pte's were really umapped in ->need_flush, so we can | |
133 | * later optimise away the tlb invalidate. This helps when userspace is | |
134 | * unmapping already-unmapped pages, which happens quite a lot. | |
135 | */ | |
136 | #define tlb_remove_tlb_entry(tlb, ptep, address) \ | |
137 | do { \ | |
138 | tlb->need_flush = 1; \ | |
139 | __tlb_remove_tlb_entry(tlb, ptep, address); \ | |
140 | } while (0) | |
141 | ||
142 | #define pte_free_tlb(tlb, ptep) \ | |
143 | do { \ | |
144 | tlb->need_flush = 1; \ | |
145 | __pte_free_tlb(tlb, ptep); \ | |
146 | } while (0) | |
147 | ||
148 | #ifndef __ARCH_HAS_4LEVEL_HACK | |
149 | #define pud_free_tlb(tlb, pudp) \ | |
150 | do { \ | |
151 | tlb->need_flush = 1; \ | |
152 | __pud_free_tlb(tlb, pudp); \ | |
153 | } while (0) | |
154 | #endif | |
155 | ||
156 | #define pmd_free_tlb(tlb, pmdp) \ | |
157 | do { \ | |
158 | tlb->need_flush = 1; \ | |
159 | __pmd_free_tlb(tlb, pmdp); \ | |
160 | } while (0) | |
161 | ||
162 | #define tlb_migrate_finish(mm) do {} while (0) | |
163 | ||
164 | #endif /* _ASM_GENERIC__TLB_H */ |