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1 /*
2 * arch/arm/include/asm/tlb.h
3 *
4 * Copyright (C) 2002 Russell King
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * Experimentation shows that on a StrongARM, it appears to be faster
11 * to use the "invalidate whole tlb" rather than "invalidate single
12 * tlb" for this.
13 *
14 * This appears true for both the process fork+exit case, as well as
15 * the munmap-large-area case.
16 */
17 #ifndef __ASMARM_TLB_H
18 #define __ASMARM_TLB_H
19
20 #include <asm/cacheflush.h>
21
22 #ifndef CONFIG_MMU
23
24 #include <linux/pagemap.h>
25
26 #define tlb_flush(tlb) ((void) tlb)
27
28 #include <asm-generic/tlb.h>
29
30 #else /* !CONFIG_MMU */
31
32 #include <linux/swap.h>
33 #include <asm/pgalloc.h>
34 #include <asm/tlbflush.h>
35
36 #define MMU_GATHER_BUNDLE 8
37
38 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
39 static inline void __tlb_remove_table(void *_table)
40 {
41 free_page_and_swap_cache((struct page *)_table);
42 }
43
44 struct mmu_table_batch {
45 struct rcu_head rcu;
46 unsigned int nr;
47 void *tables[0];
48 };
49
50 #define MAX_TABLE_BATCH \
51 ((PAGE_SIZE - sizeof(struct mmu_table_batch)) / sizeof(void *))
52
53 extern void tlb_table_flush(struct mmu_gather *tlb);
54 extern void tlb_remove_table(struct mmu_gather *tlb, void *table);
55
56 #define tlb_remove_entry(tlb, entry) tlb_remove_table(tlb, entry)
57 #else
58 #define tlb_remove_entry(tlb, entry) tlb_remove_page(tlb, entry)
59 #endif /* CONFIG_HAVE_RCU_TABLE_FREE */
60
61 /*
62 * TLB handling. This allows us to remove pages from the page
63 * tables, and efficiently handle the TLB issues.
64 */
65 struct mmu_gather {
66 struct mm_struct *mm;
67 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
68 struct mmu_table_batch *batch;
69 unsigned int need_flush;
70 #endif
71 unsigned int fullmm;
72 struct vm_area_struct *vma;
73 unsigned long start, end;
74 unsigned long range_start;
75 unsigned long range_end;
76 unsigned int nr;
77 unsigned int max;
78 struct page **pages;
79 struct page *local[MMU_GATHER_BUNDLE];
80 };
81
82 DECLARE_PER_CPU(struct mmu_gather, mmu_gathers);
83
84 /*
85 * This is unnecessarily complex. There's three ways the TLB shootdown
86 * code is used:
87 * 1. Unmapping a range of vmas. See zap_page_range(), unmap_region().
88 * tlb->fullmm = 0, and tlb_start_vma/tlb_end_vma will be called.
89 * tlb->vma will be non-NULL.
90 * 2. Unmapping all vmas. See exit_mmap().
91 * tlb->fullmm = 1, and tlb_start_vma/tlb_end_vma will be called.
92 * tlb->vma will be non-NULL. Additionally, page tables will be freed.
93 * 3. Unmapping argument pages. See shift_arg_pages().
94 * tlb->fullmm = 0, but tlb_start_vma/tlb_end_vma will not be called.
95 * tlb->vma will be NULL.
96 */
97 static inline void tlb_flush(struct mmu_gather *tlb)
98 {
99 if (tlb->fullmm || !tlb->vma)
100 flush_tlb_mm(tlb->mm);
101 else if (tlb->range_end > 0) {
102 flush_tlb_range(tlb->vma, tlb->range_start, tlb->range_end);
103 tlb->range_start = TASK_SIZE;
104 tlb->range_end = 0;
105 }
106 }
107
108 static inline void tlb_add_flush(struct mmu_gather *tlb, unsigned long addr)
109 {
110 if (!tlb->fullmm) {
111 if (addr < tlb->range_start)
112 tlb->range_start = addr;
113 if (addr + PAGE_SIZE > tlb->range_end)
114 tlb->range_end = addr + PAGE_SIZE;
115 }
116 }
117
118 static inline void __tlb_alloc_page(struct mmu_gather *tlb)
119 {
120 unsigned long addr = __get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
121
122 if (addr) {
123 tlb->pages = (void *)addr;
124 tlb->max = PAGE_SIZE / sizeof(struct page *);
125 }
126 }
127
128 static inline void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
129 {
130 tlb_flush(tlb);
131 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
132 tlb_table_flush(tlb);
133 #endif
134 }
135
136 static inline void tlb_flush_mmu_free(struct mmu_gather *tlb)
137 {
138 free_pages_and_swap_cache(tlb->pages, tlb->nr);
139 tlb->nr = 0;
140 if (tlb->pages == tlb->local)
141 __tlb_alloc_page(tlb);
142 }
143
144 static inline void tlb_flush_mmu(struct mmu_gather *tlb)
145 {
146 tlb_flush_mmu_tlbonly(tlb);
147 tlb_flush_mmu_free(tlb);
148 }
149
150 static inline void
151 arch_tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
152 unsigned long start, unsigned long end)
153 {
154 tlb->mm = mm;
155 tlb->fullmm = !(start | (end+1));
156 tlb->start = start;
157 tlb->end = end;
158 tlb->vma = NULL;
159 tlb->max = ARRAY_SIZE(tlb->local);
160 tlb->pages = tlb->local;
161 tlb->nr = 0;
162 __tlb_alloc_page(tlb);
163
164 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
165 tlb->batch = NULL;
166 #endif
167 }
168
169 static inline void
170 arch_tlb_finish_mmu(struct mmu_gather *tlb,
171 unsigned long start, unsigned long end, bool force)
172 {
173 if (force) {
174 tlb->range_start = start;
175 tlb->range_end = end;
176 }
177
178 tlb_flush_mmu(tlb);
179
180 /* keep the page table cache within bounds */
181 check_pgt_cache();
182
183 if (tlb->pages != tlb->local)
184 free_pages((unsigned long)tlb->pages, 0);
185 }
186
187 /*
188 * Memorize the range for the TLB flush.
189 */
190 static inline void
191 tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep, unsigned long addr)
192 {
193 tlb_add_flush(tlb, addr);
194 }
195
196 #define tlb_remove_huge_tlb_entry(h, tlb, ptep, address) \
197 tlb_remove_tlb_entry(tlb, ptep, address)
198 /*
199 * In the case of tlb vma handling, we can optimise these away in the
200 * case where we're doing a full MM flush. When we're doing a munmap,
201 * the vmas are adjusted to only cover the region to be torn down.
202 */
203 static inline void
204 tlb_start_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
205 {
206 if (!tlb->fullmm) {
207 flush_cache_range(vma, vma->vm_start, vma->vm_end);
208 tlb->vma = vma;
209 tlb->range_start = TASK_SIZE;
210 tlb->range_end = 0;
211 }
212 }
213
214 static inline void
215 tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
216 {
217 if (!tlb->fullmm)
218 tlb_flush(tlb);
219 }
220
221 static inline bool __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
222 {
223 tlb->pages[tlb->nr++] = page;
224 VM_WARN_ON(tlb->nr > tlb->max);
225 if (tlb->nr == tlb->max)
226 return true;
227 return false;
228 }
229
230 static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
231 {
232 if (__tlb_remove_page(tlb, page))
233 tlb_flush_mmu(tlb);
234 }
235
236 static inline bool __tlb_remove_page_size(struct mmu_gather *tlb,
237 struct page *page, int page_size)
238 {
239 return __tlb_remove_page(tlb, page);
240 }
241
242 static inline void tlb_remove_page_size(struct mmu_gather *tlb,
243 struct page *page, int page_size)
244 {
245 return tlb_remove_page(tlb, page);
246 }
247
248 static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
249 unsigned long addr)
250 {
251 pgtable_page_dtor(pte);
252
253 #ifdef CONFIG_ARM_LPAE
254 tlb_add_flush(tlb, addr);
255 #else
256 /*
257 * With the classic ARM MMU, a pte page has two corresponding pmd
258 * entries, each covering 1MB.
259 */
260 addr &= PMD_MASK;
261 tlb_add_flush(tlb, addr + SZ_1M - PAGE_SIZE);
262 tlb_add_flush(tlb, addr + SZ_1M);
263 #endif
264
265 tlb_remove_entry(tlb, pte);
266 }
267
268 static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp,
269 unsigned long addr)
270 {
271 #ifdef CONFIG_ARM_LPAE
272 tlb_add_flush(tlb, addr);
273 tlb_remove_entry(tlb, virt_to_page(pmdp));
274 #endif
275 }
276
277 static inline void
278 tlb_remove_pmd_tlb_entry(struct mmu_gather *tlb, pmd_t *pmdp, unsigned long addr)
279 {
280 tlb_add_flush(tlb, addr);
281 }
282
283 #define pte_free_tlb(tlb, ptep, addr) __pte_free_tlb(tlb, ptep, addr)
284 #define pmd_free_tlb(tlb, pmdp, addr) __pmd_free_tlb(tlb, pmdp, addr)
285 #define pud_free_tlb(tlb, pudp, addr) pud_free((tlb)->mm, pudp)
286
287 #define tlb_migrate_finish(mm) do { } while (0)
288
289 #define tlb_remove_check_page_size_change tlb_remove_check_page_size_change
290 static inline void tlb_remove_check_page_size_change(struct mmu_gather *tlb,
291 unsigned int page_size)
292 {
293 }
294
295 #endif /* CONFIG_MMU */
296 #endif