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f30c2269 | 1 | /* include/asm-generic/tlb.h |
1da177e4 LT |
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 | * | |
d16dfc55 PZ |
8 | * Copyright 2011 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com> |
9 | * | |
1da177e4 LT |
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 | ||
1da177e4 | 18 | #include <linux/swap.h> |
62152d0e | 19 | #include <asm/pgalloc.h> |
1da177e4 LT |
20 | #include <asm/tlbflush.h> |
21 | ||
22 | /* | |
23 | * For UP we don't need to worry about TLB flush | |
24 | * and page free order so much.. | |
25 | */ | |
26 | #ifdef CONFIG_SMP | |
1da177e4 LT |
27 | #define tlb_fast_mode(tlb) ((tlb)->nr == ~0U) |
28 | #else | |
1da177e4 LT |
29 | #define tlb_fast_mode(tlb) 1 |
30 | #endif | |
31 | ||
26723911 PZ |
32 | #ifdef CONFIG_HAVE_RCU_TABLE_FREE |
33 | /* | |
34 | * Semi RCU freeing of the page directories. | |
35 | * | |
36 | * This is needed by some architectures to implement software pagetable walkers. | |
37 | * | |
38 | * gup_fast() and other software pagetable walkers do a lockless page-table | |
39 | * walk and therefore needs some synchronization with the freeing of the page | |
40 | * directories. The chosen means to accomplish that is by disabling IRQs over | |
41 | * the walk. | |
42 | * | |
43 | * Architectures that use IPIs to flush TLBs will then automagically DTRT, | |
44 | * since we unlink the page, flush TLBs, free the page. Since the disabling of | |
45 | * IRQs delays the completion of the TLB flush we can never observe an already | |
46 | * freed page. | |
47 | * | |
48 | * Architectures that do not have this (PPC) need to delay the freeing by some | |
49 | * other means, this is that means. | |
50 | * | |
51 | * What we do is batch the freed directory pages (tables) and RCU free them. | |
52 | * We use the sched RCU variant, as that guarantees that IRQ/preempt disabling | |
53 | * holds off grace periods. | |
54 | * | |
55 | * However, in order to batch these pages we need to allocate storage, this | |
56 | * allocation is deep inside the MM code and can thus easily fail on memory | |
57 | * pressure. To guarantee progress we fall back to single table freeing, see | |
58 | * the implementation of tlb_remove_table_one(). | |
59 | * | |
60 | */ | |
61 | struct mmu_table_batch { | |
62 | struct rcu_head rcu; | |
63 | unsigned int nr; | |
64 | void *tables[0]; | |
65 | }; | |
66 | ||
67 | #define MAX_TABLE_BATCH \ | |
68 | ((PAGE_SIZE - sizeof(struct mmu_table_batch)) / sizeof(void *)) | |
69 | ||
70 | extern void tlb_table_flush(struct mmu_gather *tlb); | |
71 | extern void tlb_remove_table(struct mmu_gather *tlb, void *table); | |
72 | ||
73 | #endif | |
74 | ||
d16dfc55 PZ |
75 | /* |
76 | * If we can't allocate a page to make a big batch of page pointers | |
77 | * to work on, then just handle a few from the on-stack structure. | |
78 | */ | |
79 | #define MMU_GATHER_BUNDLE 8 | |
80 | ||
1da177e4 | 81 | /* struct mmu_gather is an opaque type used by the mm code for passing around |
15a23ffa | 82 | * any data needed by arch specific code for tlb_remove_page. |
1da177e4 LT |
83 | */ |
84 | struct mmu_gather { | |
85 | struct mm_struct *mm; | |
26723911 PZ |
86 | #ifdef CONFIG_HAVE_RCU_TABLE_FREE |
87 | struct mmu_table_batch *batch; | |
88 | #endif | |
1da177e4 | 89 | unsigned int nr; /* set to ~0U means fast mode */ |
d16dfc55 | 90 | unsigned int max; /* nr < max */ |
1da177e4 LT |
91 | unsigned int need_flush;/* Really unmapped some ptes? */ |
92 | unsigned int fullmm; /* non-zero means full mm flush */ | |
d16dfc55 PZ |
93 | struct page **pages; |
94 | struct page *local[MMU_GATHER_BUNDLE]; | |
1da177e4 LT |
95 | }; |
96 | ||
d16dfc55 PZ |
97 | static inline void __tlb_alloc_page(struct mmu_gather *tlb) |
98 | { | |
99 | unsigned long addr = __get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0); | |
100 | ||
101 | if (addr) { | |
102 | tlb->pages = (void *)addr; | |
103 | tlb->max = PAGE_SIZE / sizeof(struct page *); | |
104 | } | |
105 | } | |
1da177e4 LT |
106 | |
107 | /* tlb_gather_mmu | |
d16dfc55 PZ |
108 | * Called to initialize an (on-stack) mmu_gather structure for page-table |
109 | * tear-down from @mm. The @fullmm argument is used when @mm is without | |
110 | * users and we're going to destroy the full address space (exit/execve). | |
1da177e4 | 111 | */ |
d16dfc55 PZ |
112 | static inline void |
113 | tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, bool fullmm) | |
1da177e4 | 114 | { |
1da177e4 LT |
115 | tlb->mm = mm; |
116 | ||
d16dfc55 PZ |
117 | tlb->max = ARRAY_SIZE(tlb->local); |
118 | tlb->pages = tlb->local; | |
119 | ||
120 | if (num_online_cpus() > 1) { | |
121 | tlb->nr = 0; | |
122 | __tlb_alloc_page(tlb); | |
123 | } else /* Use fast mode if only one CPU is online */ | |
124 | tlb->nr = ~0U; | |
1da177e4 | 125 | |
d16dfc55 | 126 | tlb->fullmm = fullmm; |
1da177e4 | 127 | |
26723911 PZ |
128 | #ifdef CONFIG_HAVE_RCU_TABLE_FREE |
129 | tlb->batch = NULL; | |
d16dfc55 | 130 | #endif |
1da177e4 LT |
131 | } |
132 | ||
133 | static inline void | |
d16dfc55 | 134 | tlb_flush_mmu(struct mmu_gather *tlb) |
1da177e4 LT |
135 | { |
136 | if (!tlb->need_flush) | |
137 | return; | |
138 | tlb->need_flush = 0; | |
139 | tlb_flush(tlb); | |
26723911 PZ |
140 | #ifdef CONFIG_HAVE_RCU_TABLE_FREE |
141 | tlb_table_flush(tlb); | |
142 | #endif | |
1da177e4 LT |
143 | if (!tlb_fast_mode(tlb)) { |
144 | free_pages_and_swap_cache(tlb->pages, tlb->nr); | |
145 | tlb->nr = 0; | |
d16dfc55 PZ |
146 | /* |
147 | * If we are using the local on-stack array of pages for MMU | |
148 | * gather, try allocating an off-stack array again as we have | |
149 | * recently freed pages. | |
150 | */ | |
151 | if (tlb->pages == tlb->local) | |
152 | __tlb_alloc_page(tlb); | |
1da177e4 LT |
153 | } |
154 | } | |
155 | ||
156 | /* tlb_finish_mmu | |
157 | * Called at the end of the shootdown operation to free up any resources | |
15a23ffa | 158 | * that were required. |
1da177e4 LT |
159 | */ |
160 | static inline void | |
161 | tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end) | |
162 | { | |
d16dfc55 | 163 | tlb_flush_mmu(tlb); |
1da177e4 LT |
164 | |
165 | /* keep the page table cache within bounds */ | |
166 | check_pgt_cache(); | |
15a23ffa | 167 | |
d16dfc55 PZ |
168 | if (tlb->pages != tlb->local) |
169 | free_pages((unsigned long)tlb->pages, 0); | |
1da177e4 LT |
170 | } |
171 | ||
d16dfc55 | 172 | /* __tlb_remove_page |
1da177e4 LT |
173 | * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while |
174 | * handling the additional races in SMP caused by other CPUs caching valid | |
d16dfc55 PZ |
175 | * mappings in their TLBs. Returns the number of free page slots left. |
176 | * When out of page slots we must call tlb_flush_mmu(). | |
1da177e4 | 177 | */ |
d16dfc55 | 178 | static inline int __tlb_remove_page(struct mmu_gather *tlb, struct page *page) |
1da177e4 LT |
179 | { |
180 | tlb->need_flush = 1; | |
181 | if (tlb_fast_mode(tlb)) { | |
182 | free_page_and_swap_cache(page); | |
d16dfc55 | 183 | return 1; /* avoid calling tlb_flush_mmu() */ |
1da177e4 LT |
184 | } |
185 | tlb->pages[tlb->nr++] = page; | |
d16dfc55 PZ |
186 | VM_BUG_ON(tlb->nr > tlb->max); |
187 | ||
188 | return tlb->max - tlb->nr; | |
189 | } | |
190 | ||
191 | /* tlb_remove_page | |
192 | * Similar to __tlb_remove_page but will call tlb_flush_mmu() itself when | |
193 | * required. | |
194 | */ | |
195 | static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page) | |
196 | { | |
197 | if (!__tlb_remove_page(tlb, page)) | |
198 | tlb_flush_mmu(tlb); | |
1da177e4 LT |
199 | } |
200 | ||
201 | /** | |
202 | * tlb_remove_tlb_entry - remember a pte unmapping for later tlb invalidation. | |
203 | * | |
204 | * Record the fact that pte's were really umapped in ->need_flush, so we can | |
205 | * later optimise away the tlb invalidate. This helps when userspace is | |
206 | * unmapping already-unmapped pages, which happens quite a lot. | |
207 | */ | |
208 | #define tlb_remove_tlb_entry(tlb, ptep, address) \ | |
209 | do { \ | |
210 | tlb->need_flush = 1; \ | |
211 | __tlb_remove_tlb_entry(tlb, ptep, address); \ | |
212 | } while (0) | |
213 | ||
9e1b32ca | 214 | #define pte_free_tlb(tlb, ptep, address) \ |
1da177e4 LT |
215 | do { \ |
216 | tlb->need_flush = 1; \ | |
9e1b32ca | 217 | __pte_free_tlb(tlb, ptep, address); \ |
1da177e4 LT |
218 | } while (0) |
219 | ||
220 | #ifndef __ARCH_HAS_4LEVEL_HACK | |
9e1b32ca | 221 | #define pud_free_tlb(tlb, pudp, address) \ |
1da177e4 LT |
222 | do { \ |
223 | tlb->need_flush = 1; \ | |
9e1b32ca | 224 | __pud_free_tlb(tlb, pudp, address); \ |
1da177e4 LT |
225 | } while (0) |
226 | #endif | |
227 | ||
9e1b32ca | 228 | #define pmd_free_tlb(tlb, pmdp, address) \ |
1da177e4 LT |
229 | do { \ |
230 | tlb->need_flush = 1; \ | |
9e1b32ca | 231 | __pmd_free_tlb(tlb, pmdp, address); \ |
1da177e4 LT |
232 | } while (0) |
233 | ||
234 | #define tlb_migrate_finish(mm) do {} while (0) | |
235 | ||
236 | #endif /* _ASM_GENERIC__TLB_H */ |