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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 | * Copyright 2011 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com> | |
9 | * | |
10 | * This program is free software; you can redistribute it and/or | |
11 | * modify it under the terms of the GNU General Public License | |
12 | * as published by the Free Software Foundation; either version | |
13 | * 2 of the License, or (at your option) any later version. | |
14 | */ | |
15 | #ifndef _ASM_GENERIC__TLB_H | |
16 | #define _ASM_GENERIC__TLB_H | |
17 | ||
18 | #include <linux/swap.h> | |
19 | #include <asm/pgalloc.h> | |
20 | #include <asm/tlbflush.h> | |
21 | ||
22 | #ifdef CONFIG_HAVE_RCU_TABLE_FREE | |
23 | /* | |
24 | * Semi RCU freeing of the page directories. | |
25 | * | |
26 | * This is needed by some architectures to implement software pagetable walkers. | |
27 | * | |
28 | * gup_fast() and other software pagetable walkers do a lockless page-table | |
29 | * walk and therefore needs some synchronization with the freeing of the page | |
30 | * directories. The chosen means to accomplish that is by disabling IRQs over | |
31 | * the walk. | |
32 | * | |
33 | * Architectures that use IPIs to flush TLBs will then automagically DTRT, | |
34 | * since we unlink the page, flush TLBs, free the page. Since the disabling of | |
35 | * IRQs delays the completion of the TLB flush we can never observe an already | |
36 | * freed page. | |
37 | * | |
38 | * Architectures that do not have this (PPC) need to delay the freeing by some | |
39 | * other means, this is that means. | |
40 | * | |
41 | * What we do is batch the freed directory pages (tables) and RCU free them. | |
42 | * We use the sched RCU variant, as that guarantees that IRQ/preempt disabling | |
43 | * holds off grace periods. | |
44 | * | |
45 | * However, in order to batch these pages we need to allocate storage, this | |
46 | * allocation is deep inside the MM code and can thus easily fail on memory | |
47 | * pressure. To guarantee progress we fall back to single table freeing, see | |
48 | * the implementation of tlb_remove_table_one(). | |
49 | * | |
50 | */ | |
51 | struct mmu_table_batch { | |
52 | struct rcu_head rcu; | |
53 | unsigned int nr; | |
54 | void *tables[0]; | |
55 | }; | |
56 | ||
57 | #define MAX_TABLE_BATCH \ | |
58 | ((PAGE_SIZE - sizeof(struct mmu_table_batch)) / sizeof(void *)) | |
59 | ||
60 | extern void tlb_table_flush(struct mmu_gather *tlb); | |
61 | extern void tlb_remove_table(struct mmu_gather *tlb, void *table); | |
62 | ||
63 | #endif | |
64 | ||
65 | /* | |
66 | * If we can't allocate a page to make a big batch of page pointers | |
67 | * to work on, then just handle a few from the on-stack structure. | |
68 | */ | |
69 | #define MMU_GATHER_BUNDLE 8 | |
70 | ||
71 | struct mmu_gather_batch { | |
72 | struct mmu_gather_batch *next; | |
73 | unsigned int nr; | |
74 | unsigned int max; | |
75 | struct page *pages[0]; | |
76 | }; | |
77 | ||
78 | #define MAX_GATHER_BATCH \ | |
79 | ((PAGE_SIZE - sizeof(struct mmu_gather_batch)) / sizeof(void *)) | |
80 | ||
81 | /* struct mmu_gather is an opaque type used by the mm code for passing around | |
82 | * any data needed by arch specific code for tlb_remove_page. | |
83 | */ | |
84 | struct mmu_gather { | |
85 | struct mm_struct *mm; | |
86 | #ifdef CONFIG_HAVE_RCU_TABLE_FREE | |
87 | struct mmu_table_batch *batch; | |
88 | #endif | |
89 | unsigned long start; | |
90 | unsigned long end; | |
91 | unsigned int need_flush : 1, /* Did free PTEs */ | |
92 | fast_mode : 1; /* No batching */ | |
93 | ||
94 | unsigned int fullmm; | |
95 | ||
96 | struct mmu_gather_batch *active; | |
97 | struct mmu_gather_batch local; | |
98 | struct page *__pages[MMU_GATHER_BUNDLE]; | |
99 | }; | |
100 | ||
101 | #define HAVE_GENERIC_MMU_GATHER | |
102 | ||
103 | static inline int tlb_fast_mode(struct mmu_gather *tlb) | |
104 | { | |
105 | #ifdef CONFIG_SMP | |
106 | return tlb->fast_mode; | |
107 | #else | |
108 | /* | |
109 | * For UP we don't need to worry about TLB flush | |
110 | * and page free order so much.. | |
111 | */ | |
112 | return 1; | |
113 | #endif | |
114 | } | |
115 | ||
116 | void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, bool fullmm); | |
117 | void tlb_flush_mmu(struct mmu_gather *tlb); | |
118 | void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, | |
119 | unsigned long end); | |
120 | int __tlb_remove_page(struct mmu_gather *tlb, struct page *page); | |
121 | ||
122 | /* tlb_remove_page | |
123 | * Similar to __tlb_remove_page but will call tlb_flush_mmu() itself when | |
124 | * required. | |
125 | */ | |
126 | static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page) | |
127 | { | |
128 | if (!__tlb_remove_page(tlb, page)) | |
129 | tlb_flush_mmu(tlb); | |
130 | } | |
131 | ||
132 | /** | |
133 | * tlb_remove_tlb_entry - remember a pte unmapping for later tlb invalidation. | |
134 | * | |
135 | * Record the fact that pte's were really umapped in ->need_flush, so we can | |
136 | * later optimise away the tlb invalidate. This helps when userspace is | |
137 | * unmapping already-unmapped pages, which happens quite a lot. | |
138 | */ | |
139 | #define tlb_remove_tlb_entry(tlb, ptep, address) \ | |
140 | do { \ | |
141 | tlb->need_flush = 1; \ | |
142 | __tlb_remove_tlb_entry(tlb, ptep, address); \ | |
143 | } while (0) | |
144 | ||
145 | /** | |
146 | * tlb_remove_pmd_tlb_entry - remember a pmd mapping for later tlb invalidation | |
147 | * This is a nop so far, because only x86 needs it. | |
148 | */ | |
149 | #ifndef __tlb_remove_pmd_tlb_entry | |
150 | #define __tlb_remove_pmd_tlb_entry(tlb, pmdp, address) do {} while (0) | |
151 | #endif | |
152 | ||
153 | #define tlb_remove_pmd_tlb_entry(tlb, pmdp, address) \ | |
154 | do { \ | |
155 | tlb->need_flush = 1; \ | |
156 | __tlb_remove_pmd_tlb_entry(tlb, pmdp, address); \ | |
157 | } while (0) | |
158 | ||
159 | #define pte_free_tlb(tlb, ptep, address) \ | |
160 | do { \ | |
161 | tlb->need_flush = 1; \ | |
162 | __pte_free_tlb(tlb, ptep, address); \ | |
163 | } while (0) | |
164 | ||
165 | #ifndef __ARCH_HAS_4LEVEL_HACK | |
166 | #define pud_free_tlb(tlb, pudp, address) \ | |
167 | do { \ | |
168 | tlb->need_flush = 1; \ | |
169 | __pud_free_tlb(tlb, pudp, address); \ | |
170 | } while (0) | |
171 | #endif | |
172 | ||
173 | #define pmd_free_tlb(tlb, pmdp, address) \ | |
174 | do { \ | |
175 | tlb->need_flush = 1; \ | |
176 | __pmd_free_tlb(tlb, pmdp, address); \ | |
177 | } while (0) | |
178 | ||
179 | #define tlb_migrate_finish(mm) do {} while (0) | |
180 | ||
181 | #endif /* _ASM_GENERIC__TLB_H */ |