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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 | |
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 | /* | |
82 | * Limit the maximum number of mmu_gather batches to reduce a risk of soft | |
83 | * lockups for non-preemptible kernels on huge machines when a lot of memory | |
84 | * is zapped during unmapping. | |
85 | * 10K pages freed at once should be safe even without a preemption point. | |
86 | */ | |
87 | #define MAX_GATHER_BATCH_COUNT (10000UL/MAX_GATHER_BATCH) | |
88 | ||
89 | /* struct mmu_gather is an opaque type used by the mm code for passing around | |
90 | * any data needed by arch specific code for tlb_remove_page. | |
91 | */ | |
92 | struct mmu_gather { | |
93 | struct mm_struct *mm; | |
94 | #ifdef CONFIG_HAVE_RCU_TABLE_FREE | |
95 | struct mmu_table_batch *batch; | |
96 | #endif | |
97 | unsigned long start; | |
98 | unsigned long end; | |
99 | /* we are in the middle of an operation to clear | |
100 | * a full mm and can make some optimizations */ | |
101 | unsigned int fullmm : 1, | |
102 | /* we have performed an operation which | |
103 | * requires a complete flush of the tlb */ | |
104 | need_flush_all : 1; | |
105 | ||
106 | struct mmu_gather_batch *active; | |
107 | struct mmu_gather_batch local; | |
108 | struct page *__pages[MMU_GATHER_BUNDLE]; | |
109 | unsigned int batch_count; | |
110 | int page_size; | |
111 | }; | |
112 | ||
113 | #define HAVE_GENERIC_MMU_GATHER | |
114 | ||
115 | void arch_tlb_gather_mmu(struct mmu_gather *tlb, | |
116 | struct mm_struct *mm, unsigned long start, unsigned long end); | |
117 | void tlb_flush_mmu(struct mmu_gather *tlb); | |
118 | void arch_tlb_finish_mmu(struct mmu_gather *tlb, | |
119 | unsigned long start, unsigned long end, bool force); | |
120 | extern bool __tlb_remove_page_size(struct mmu_gather *tlb, struct page *page, | |
121 | int page_size); | |
122 | ||
123 | static inline void __tlb_adjust_range(struct mmu_gather *tlb, | |
124 | unsigned long address, | |
125 | unsigned int range_size) | |
126 | { | |
127 | tlb->start = min(tlb->start, address); | |
128 | tlb->end = max(tlb->end, address + range_size); | |
129 | } | |
130 | ||
131 | static inline void __tlb_reset_range(struct mmu_gather *tlb) | |
132 | { | |
133 | if (tlb->fullmm) { | |
134 | tlb->start = tlb->end = ~0; | |
135 | } else { | |
136 | tlb->start = TASK_SIZE; | |
137 | tlb->end = 0; | |
138 | } | |
139 | } | |
140 | ||
141 | static inline void tlb_remove_page_size(struct mmu_gather *tlb, | |
142 | struct page *page, int page_size) | |
143 | { | |
144 | if (__tlb_remove_page_size(tlb, page, page_size)) | |
145 | tlb_flush_mmu(tlb); | |
146 | } | |
147 | ||
148 | static inline bool __tlb_remove_page(struct mmu_gather *tlb, struct page *page) | |
149 | { | |
150 | return __tlb_remove_page_size(tlb, page, PAGE_SIZE); | |
151 | } | |
152 | ||
153 | /* tlb_remove_page | |
154 | * Similar to __tlb_remove_page but will call tlb_flush_mmu() itself when | |
155 | * required. | |
156 | */ | |
157 | static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page) | |
158 | { | |
159 | return tlb_remove_page_size(tlb, page, PAGE_SIZE); | |
160 | } | |
161 | ||
162 | #ifndef tlb_remove_check_page_size_change | |
163 | #define tlb_remove_check_page_size_change tlb_remove_check_page_size_change | |
164 | static inline void tlb_remove_check_page_size_change(struct mmu_gather *tlb, | |
165 | unsigned int page_size) | |
166 | { | |
167 | /* | |
168 | * We don't care about page size change, just update | |
169 | * mmu_gather page size here so that debug checks | |
170 | * doesn't throw false warning. | |
171 | */ | |
172 | #ifdef CONFIG_DEBUG_VM | |
173 | tlb->page_size = page_size; | |
174 | #endif | |
175 | } | |
176 | #endif | |
177 | ||
178 | /* | |
179 | * In the case of tlb vma handling, we can optimise these away in the | |
180 | * case where we're doing a full MM flush. When we're doing a munmap, | |
181 | * the vmas are adjusted to only cover the region to be torn down. | |
182 | */ | |
183 | #ifndef tlb_start_vma | |
184 | #define tlb_start_vma(tlb, vma) do { } while (0) | |
185 | #endif | |
186 | ||
187 | #define __tlb_end_vma(tlb, vma) \ | |
188 | do { \ | |
189 | if (!tlb->fullmm && tlb->end) { \ | |
190 | tlb_flush(tlb); \ | |
191 | __tlb_reset_range(tlb); \ | |
192 | } \ | |
193 | } while (0) | |
194 | ||
195 | #ifndef tlb_end_vma | |
196 | #define tlb_end_vma __tlb_end_vma | |
197 | #endif | |
198 | ||
199 | #ifndef __tlb_remove_tlb_entry | |
200 | #define __tlb_remove_tlb_entry(tlb, ptep, address) do { } while (0) | |
201 | #endif | |
202 | ||
203 | /** | |
204 | * tlb_remove_tlb_entry - remember a pte unmapping for later tlb invalidation. | |
205 | * | |
206 | * Record the fact that pte's were really unmapped by updating the range, | |
207 | * so we can later optimise away the tlb invalidate. This helps when | |
208 | * userspace is unmapping already-unmapped pages, which happens quite a lot. | |
209 | */ | |
210 | #define tlb_remove_tlb_entry(tlb, ptep, address) \ | |
211 | do { \ | |
212 | __tlb_adjust_range(tlb, address, PAGE_SIZE); \ | |
213 | __tlb_remove_tlb_entry(tlb, ptep, address); \ | |
214 | } while (0) | |
215 | ||
216 | #define tlb_remove_huge_tlb_entry(h, tlb, ptep, address) \ | |
217 | do { \ | |
218 | __tlb_adjust_range(tlb, address, huge_page_size(h)); \ | |
219 | __tlb_remove_tlb_entry(tlb, ptep, address); \ | |
220 | } while (0) | |
221 | ||
222 | /** | |
223 | * tlb_remove_pmd_tlb_entry - remember a pmd mapping for later tlb invalidation | |
224 | * This is a nop so far, because only x86 needs it. | |
225 | */ | |
226 | #ifndef __tlb_remove_pmd_tlb_entry | |
227 | #define __tlb_remove_pmd_tlb_entry(tlb, pmdp, address) do {} while (0) | |
228 | #endif | |
229 | ||
230 | #define tlb_remove_pmd_tlb_entry(tlb, pmdp, address) \ | |
231 | do { \ | |
232 | __tlb_adjust_range(tlb, address, HPAGE_PMD_SIZE); \ | |
233 | __tlb_remove_pmd_tlb_entry(tlb, pmdp, address); \ | |
234 | } while (0) | |
235 | ||
236 | /** | |
237 | * tlb_remove_pud_tlb_entry - remember a pud mapping for later tlb | |
238 | * invalidation. This is a nop so far, because only x86 needs it. | |
239 | */ | |
240 | #ifndef __tlb_remove_pud_tlb_entry | |
241 | #define __tlb_remove_pud_tlb_entry(tlb, pudp, address) do {} while (0) | |
242 | #endif | |
243 | ||
244 | #define tlb_remove_pud_tlb_entry(tlb, pudp, address) \ | |
245 | do { \ | |
246 | __tlb_adjust_range(tlb, address, HPAGE_PUD_SIZE); \ | |
247 | __tlb_remove_pud_tlb_entry(tlb, pudp, address); \ | |
248 | } while (0) | |
249 | ||
250 | /* | |
251 | * For things like page tables caches (ie caching addresses "inside" the | |
252 | * page tables, like x86 does), for legacy reasons, flushing an | |
253 | * individual page had better flush the page table caches behind it. This | |
254 | * is definitely how x86 works, for example. And if you have an | |
255 | * architected non-legacy page table cache (which I'm not aware of | |
256 | * anybody actually doing), you're going to have some architecturally | |
257 | * explicit flushing for that, likely *separate* from a regular TLB entry | |
258 | * flush, and thus you'd need more than just some range expansion.. | |
259 | * | |
260 | * So if we ever find an architecture | |
261 | * that would want something that odd, I think it is up to that | |
262 | * architecture to do its own odd thing, not cause pain for others | |
263 | * http://lkml.kernel.org/r/CA+55aFzBggoXtNXQeng5d_mRoDnaMBE5Y+URs+PHR67nUpMtaw@mail.gmail.com | |
264 | * | |
265 | * For now w.r.t page table cache, mark the range_size as PAGE_SIZE | |
266 | */ | |
267 | ||
268 | #define pte_free_tlb(tlb, ptep, address) \ | |
269 | do { \ | |
270 | __tlb_adjust_range(tlb, address, PAGE_SIZE); \ | |
271 | __pte_free_tlb(tlb, ptep, address); \ | |
272 | } while (0) | |
273 | ||
274 | #define pmd_free_tlb(tlb, pmdp, address) \ | |
275 | do { \ | |
276 | __tlb_adjust_range(tlb, address, PAGE_SIZE); \ | |
277 | __pmd_free_tlb(tlb, pmdp, address); \ | |
278 | } while (0) | |
279 | ||
280 | #ifndef __ARCH_HAS_4LEVEL_HACK | |
281 | #define pud_free_tlb(tlb, pudp, address) \ | |
282 | do { \ | |
283 | __tlb_adjust_range(tlb, address, PAGE_SIZE); \ | |
284 | __pud_free_tlb(tlb, pudp, address); \ | |
285 | } while (0) | |
286 | #endif | |
287 | ||
288 | #ifndef __ARCH_HAS_5LEVEL_HACK | |
289 | #define p4d_free_tlb(tlb, pudp, address) \ | |
290 | do { \ | |
291 | __tlb_adjust_range(tlb, address, PAGE_SIZE); \ | |
292 | __p4d_free_tlb(tlb, pudp, address); \ | |
293 | } while (0) | |
294 | #endif | |
295 | ||
296 | #define tlb_migrate_finish(mm) do {} while (0) | |
297 | ||
298 | #endif /* _ASM_GENERIC__TLB_H */ |