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/mmu_notifier.h> |
19 | #include <linux/swap.h> |
20 | #include <asm/pgalloc.h> |
21 | #include <asm/tlbflush.h> |
22 | |
23 | #ifdef CONFIG_MMU |
24 | |
25 | #ifdef CONFIG_HAVE_RCU_TABLE_FREE |
26 | /* |
27 | * Semi RCU freeing of the page directories. |
28 | * |
29 | * This is needed by some architectures to implement software pagetable walkers. |
30 | * |
31 | * gup_fast() and other software pagetable walkers do a lockless page-table |
32 | * walk and therefore needs some synchronization with the freeing of the page |
33 | * directories. The chosen means to accomplish that is by disabling IRQs over |
34 | * the walk. |
35 | * |
36 | * Architectures that use IPIs to flush TLBs will then automagically DTRT, |
37 | * since we unlink the page, flush TLBs, free the page. Since the disabling of |
38 | * IRQs delays the completion of the TLB flush we can never observe an already |
39 | * freed page. |
40 | * |
41 | * Architectures that do not have this (PPC) need to delay the freeing by some |
42 | * other means, this is that means. |
43 | * |
44 | * What we do is batch the freed directory pages (tables) and RCU free them. |
45 | * We use the sched RCU variant, as that guarantees that IRQ/preempt disabling |
46 | * holds off grace periods. |
47 | * |
48 | * However, in order to batch these pages we need to allocate storage, this |
49 | * allocation is deep inside the MM code and can thus easily fail on memory |
50 | * pressure. To guarantee progress we fall back to single table freeing, see |
51 | * the implementation of tlb_remove_table_one(). |
52 | * |
53 | */ |
54 | struct mmu_table_batch { |
55 | struct rcu_head rcu; |
56 | unsigned int nr; |
57 | void *tables[0]; |
58 | }; |
59 | |
60 | #define MAX_TABLE_BATCH \ |
61 | ((PAGE_SIZE - sizeof(struct mmu_table_batch)) / sizeof(void *)) |
62 | |
63 | extern void tlb_table_flush(struct mmu_gather *tlb); |
64 | extern void tlb_remove_table(struct mmu_gather *tlb, void *table); |
65 | |
66 | #endif |
67 | |
68 | /* |
69 | * If we can't allocate a page to make a big batch of page pointers |
70 | * to work on, then just handle a few from the on-stack structure. |
71 | */ |
72 | #define MMU_GATHER_BUNDLE 8 |
73 | |
74 | struct mmu_gather_batch { |
75 | struct mmu_gather_batch *next; |
76 | unsigned int nr; |
77 | unsigned int max; |
78 | struct page *pages[0]; |
79 | }; |
80 | |
81 | #define MAX_GATHER_BATCH \ |
82 | ((PAGE_SIZE - sizeof(struct mmu_gather_batch)) / sizeof(void *)) |
83 | |
84 | /* |
85 | * Limit the maximum number of mmu_gather batches to reduce a risk of soft |
86 | * lockups for non-preemptible kernels on huge machines when a lot of memory |
87 | * is zapped during unmapping. |
88 | * 10K pages freed at once should be safe even without a preemption point. |
89 | */ |
90 | #define MAX_GATHER_BATCH_COUNT (10000UL/MAX_GATHER_BATCH) |
91 | |
92 | /* struct mmu_gather is an opaque type used by the mm code for passing around |
93 | * any data needed by arch specific code for tlb_remove_page. |
94 | */ |
95 | struct mmu_gather { |
96 | struct mm_struct *mm; |
97 | #ifdef CONFIG_HAVE_RCU_TABLE_FREE |
98 | struct mmu_table_batch *batch; |
99 | #endif |
100 | unsigned long start; |
101 | unsigned long end; |
102 | /* |
103 | * we are in the middle of an operation to clear |
104 | * a full mm and can make some optimizations |
105 | */ |
106 | unsigned int fullmm : 1; |
107 | |
108 | /* |
109 | * we have performed an operation which |
110 | * requires a complete flush of the tlb |
111 | */ |
112 | unsigned int need_flush_all : 1; |
113 | |
114 | /* |
115 | * we have removed page directories |
116 | */ |
117 | unsigned int freed_tables : 1; |
118 | |
119 | /* |
120 | * at which levels have we cleared entries? |
121 | */ |
122 | unsigned int cleared_ptes : 1; |
123 | unsigned int cleared_pmds : 1; |
124 | unsigned int cleared_puds : 1; |
125 | unsigned int cleared_p4ds : 1; |
126 | |
127 | struct mmu_gather_batch *active; |
128 | struct mmu_gather_batch local; |
129 | struct page *__pages[MMU_GATHER_BUNDLE]; |
130 | unsigned int batch_count; |
131 | int page_size; |
132 | }; |
133 | |
134 | #define HAVE_GENERIC_MMU_GATHER |
135 | |
136 | void arch_tlb_gather_mmu(struct mmu_gather *tlb, |
137 | struct mm_struct *mm, unsigned long start, unsigned long end); |
138 | void tlb_flush_mmu(struct mmu_gather *tlb); |
139 | void arch_tlb_finish_mmu(struct mmu_gather *tlb, |
140 | unsigned long start, unsigned long end, bool force); |
141 | void tlb_flush_mmu_free(struct mmu_gather *tlb); |
142 | extern bool __tlb_remove_page_size(struct mmu_gather *tlb, struct page *page, |
143 | int page_size); |
144 | |
145 | static inline void __tlb_adjust_range(struct mmu_gather *tlb, |
146 | unsigned long address, |
147 | unsigned int range_size) |
148 | { |
149 | tlb->start = min(tlb->start, address); |
150 | tlb->end = max(tlb->end, address + range_size); |
151 | } |
152 | |
153 | static inline void __tlb_reset_range(struct mmu_gather *tlb) |
154 | { |
155 | if (tlb->fullmm) { |
156 | tlb->start = tlb->end = ~0; |
157 | } else { |
158 | tlb->start = TASK_SIZE; |
159 | tlb->end = 0; |
160 | } |
161 | tlb->freed_tables = 0; |
162 | tlb->cleared_ptes = 0; |
163 | tlb->cleared_pmds = 0; |
164 | tlb->cleared_puds = 0; |
165 | tlb->cleared_p4ds = 0; |
166 | } |
167 | |
168 | static inline void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb) |
169 | { |
170 | if (!tlb->end) |
171 | return; |
172 | |
173 | tlb_flush(tlb); |
174 | mmu_notifier_invalidate_range(tlb->mm, tlb->start, tlb->end); |
175 | __tlb_reset_range(tlb); |
176 | } |
177 | |
178 | static inline void tlb_remove_page_size(struct mmu_gather *tlb, |
179 | struct page *page, int page_size) |
180 | { |
181 | if (__tlb_remove_page_size(tlb, page, page_size)) |
182 | tlb_flush_mmu(tlb); |
183 | } |
184 | |
185 | static inline bool __tlb_remove_page(struct mmu_gather *tlb, struct page *page) |
186 | { |
187 | return __tlb_remove_page_size(tlb, page, PAGE_SIZE); |
188 | } |
189 | |
190 | /* tlb_remove_page |
191 | * Similar to __tlb_remove_page but will call tlb_flush_mmu() itself when |
192 | * required. |
193 | */ |
194 | static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page) |
195 | { |
196 | return tlb_remove_page_size(tlb, page, PAGE_SIZE); |
197 | } |
198 | |
199 | #ifndef tlb_remove_check_page_size_change |
200 | #define tlb_remove_check_page_size_change tlb_remove_check_page_size_change |
201 | static inline void tlb_remove_check_page_size_change(struct mmu_gather *tlb, |
202 | unsigned int page_size) |
203 | { |
204 | /* |
205 | * We don't care about page size change, just update |
206 | * mmu_gather page size here so that debug checks |
207 | * doesn't throw false warning. |
208 | */ |
209 | #ifdef CONFIG_DEBUG_VM |
210 | tlb->page_size = page_size; |
211 | #endif |
212 | } |
213 | #endif |
214 | |
215 | static inline unsigned long tlb_get_unmap_shift(struct mmu_gather *tlb) |
216 | { |
217 | if (tlb->cleared_ptes) |
218 | return PAGE_SHIFT; |
219 | if (tlb->cleared_pmds) |
220 | return PMD_SHIFT; |
221 | if (tlb->cleared_puds) |
222 | return PUD_SHIFT; |
223 | if (tlb->cleared_p4ds) |
224 | return P4D_SHIFT; |
225 | |
226 | return PAGE_SHIFT; |
227 | } |
228 | |
229 | static inline unsigned long tlb_get_unmap_size(struct mmu_gather *tlb) |
230 | { |
231 | return 1UL << tlb_get_unmap_shift(tlb); |
232 | } |
233 | |
234 | /* |
235 | * In the case of tlb vma handling, we can optimise these away in the |
236 | * case where we're doing a full MM flush. When we're doing a munmap, |
237 | * the vmas are adjusted to only cover the region to be torn down. |
238 | */ |
239 | #ifndef tlb_start_vma |
240 | #define tlb_start_vma(tlb, vma) do { } while (0) |
241 | #endif |
242 | |
243 | #define __tlb_end_vma(tlb, vma) \ |
244 | do { \ |
245 | if (!tlb->fullmm) \ |
246 | tlb_flush_mmu_tlbonly(tlb); \ |
247 | } while (0) |
248 | |
249 | #ifndef tlb_end_vma |
250 | #define tlb_end_vma __tlb_end_vma |
251 | #endif |
252 | |
253 | #ifndef __tlb_remove_tlb_entry |
254 | #define __tlb_remove_tlb_entry(tlb, ptep, address) do { } while (0) |
255 | #endif |
256 | |
257 | /** |
258 | * tlb_remove_tlb_entry - remember a pte unmapping for later tlb invalidation. |
259 | * |
260 | * Record the fact that pte's were really unmapped by updating the range, |
261 | * so we can later optimise away the tlb invalidate. This helps when |
262 | * userspace is unmapping already-unmapped pages, which happens quite a lot. |
263 | */ |
264 | #define tlb_remove_tlb_entry(tlb, ptep, address) \ |
265 | do { \ |
266 | __tlb_adjust_range(tlb, address, PAGE_SIZE); \ |
267 | tlb->cleared_ptes = 1; \ |
268 | __tlb_remove_tlb_entry(tlb, ptep, address); \ |
269 | } while (0) |
270 | |
271 | #define tlb_remove_huge_tlb_entry(h, tlb, ptep, address) \ |
272 | do { \ |
273 | unsigned long _sz = huge_page_size(h); \ |
274 | __tlb_adjust_range(tlb, address, _sz); \ |
275 | if (_sz == PMD_SIZE) \ |
276 | tlb->cleared_pmds = 1; \ |
277 | else if (_sz == PUD_SIZE) \ |
278 | tlb->cleared_puds = 1; \ |
279 | __tlb_remove_tlb_entry(tlb, ptep, address); \ |
280 | } while (0) |
281 | |
282 | /** |
283 | * tlb_remove_pmd_tlb_entry - remember a pmd mapping for later tlb invalidation |
284 | * This is a nop so far, because only x86 needs it. |
285 | */ |
286 | #ifndef __tlb_remove_pmd_tlb_entry |
287 | #define __tlb_remove_pmd_tlb_entry(tlb, pmdp, address) do {} while (0) |
288 | #endif |
289 | |
290 | #define tlb_remove_pmd_tlb_entry(tlb, pmdp, address) \ |
291 | do { \ |
292 | __tlb_adjust_range(tlb, address, HPAGE_PMD_SIZE); \ |
293 | tlb->cleared_pmds = 1; \ |
294 | __tlb_remove_pmd_tlb_entry(tlb, pmdp, address); \ |
295 | } while (0) |
296 | |
297 | /** |
298 | * tlb_remove_pud_tlb_entry - remember a pud mapping for later tlb |
299 | * invalidation. This is a nop so far, because only x86 needs it. |
300 | */ |
301 | #ifndef __tlb_remove_pud_tlb_entry |
302 | #define __tlb_remove_pud_tlb_entry(tlb, pudp, address) do {} while (0) |
303 | #endif |
304 | |
305 | #define tlb_remove_pud_tlb_entry(tlb, pudp, address) \ |
306 | do { \ |
307 | __tlb_adjust_range(tlb, address, HPAGE_PUD_SIZE); \ |
308 | tlb->cleared_puds = 1; \ |
309 | __tlb_remove_pud_tlb_entry(tlb, pudp, address); \ |
310 | } while (0) |
311 | |
312 | /* |
313 | * For things like page tables caches (ie caching addresses "inside" the |
314 | * page tables, like x86 does), for legacy reasons, flushing an |
315 | * individual page had better flush the page table caches behind it. This |
316 | * is definitely how x86 works, for example. And if you have an |
317 | * architected non-legacy page table cache (which I'm not aware of |
318 | * anybody actually doing), you're going to have some architecturally |
319 | * explicit flushing for that, likely *separate* from a regular TLB entry |
320 | * flush, and thus you'd need more than just some range expansion.. |
321 | * |
322 | * So if we ever find an architecture |
323 | * that would want something that odd, I think it is up to that |
324 | * architecture to do its own odd thing, not cause pain for others |
325 | * http://lkml.kernel.org/r/CA+55aFzBggoXtNXQeng5d_mRoDnaMBE5Y+URs+PHR67nUpMtaw@mail.gmail.com |
326 | * |
327 | * For now w.r.t page table cache, mark the range_size as PAGE_SIZE |
328 | */ |
329 | |
330 | #ifndef pte_free_tlb |
331 | #define pte_free_tlb(tlb, ptep, address) \ |
332 | do { \ |
333 | __tlb_adjust_range(tlb, address, PAGE_SIZE); \ |
334 | tlb->freed_tables = 1; \ |
335 | tlb->cleared_pmds = 1; \ |
336 | __pte_free_tlb(tlb, ptep, address); \ |
337 | } while (0) |
338 | #endif |
339 | |
340 | #ifndef pmd_free_tlb |
341 | #define pmd_free_tlb(tlb, pmdp, address) \ |
342 | do { \ |
343 | __tlb_adjust_range(tlb, address, PAGE_SIZE); \ |
344 | tlb->freed_tables = 1; \ |
345 | tlb->cleared_puds = 1; \ |
346 | __pmd_free_tlb(tlb, pmdp, address); \ |
347 | } while (0) |
348 | #endif |
349 | |
350 | #ifndef __ARCH_HAS_4LEVEL_HACK |
351 | #ifndef pud_free_tlb |
352 | #define pud_free_tlb(tlb, pudp, address) \ |
353 | do { \ |
354 | __tlb_adjust_range(tlb, address, PAGE_SIZE); \ |
355 | tlb->freed_tables = 1; \ |
356 | tlb->cleared_p4ds = 1; \ |
357 | __pud_free_tlb(tlb, pudp, address); \ |
358 | } while (0) |
359 | #endif |
360 | #endif |
361 | |
362 | #ifndef __ARCH_HAS_5LEVEL_HACK |
363 | #ifndef p4d_free_tlb |
364 | #define p4d_free_tlb(tlb, pudp, address) \ |
365 | do { \ |
366 | __tlb_adjust_range(tlb, address, PAGE_SIZE); \ |
367 | tlb->freed_tables = 1; \ |
368 | __p4d_free_tlb(tlb, pudp, address); \ |
369 | } while (0) |
370 | #endif |
371 | #endif |
372 | |
373 | #endif /* CONFIG_MMU */ |
374 | |
375 | #define tlb_migrate_finish(mm) do {} while (0) |
376 | |
377 | #endif /* _ASM_GENERIC__TLB_H */ |
378 | |