Line data Source code
1 : /* SPDX-License-Identifier: GPL-2.0 */
2 : #ifndef _LINUX_HIGHMEM_H
3 : #define _LINUX_HIGHMEM_H
4 :
5 : #include <linux/fs.h>
6 : #include <linux/kernel.h>
7 : #include <linux/bug.h>
8 : #include <linux/mm.h>
9 : #include <linux/uaccess.h>
10 : #include <linux/hardirq.h>
11 :
12 : #include <asm/cacheflush.h>
13 :
14 : #include "highmem-internal.h"
15 :
16 : /**
17 : * kmap - Map a page for long term usage
18 : * @page: Pointer to the page to be mapped
19 : *
20 : * Returns: The virtual address of the mapping
21 : *
22 : * Can only be invoked from preemptible task context because on 32bit
23 : * systems with CONFIG_HIGHMEM enabled this function might sleep.
24 : *
25 : * For systems with CONFIG_HIGHMEM=n and for pages in the low memory area
26 : * this returns the virtual address of the direct kernel mapping.
27 : *
28 : * The returned virtual address is globally visible and valid up to the
29 : * point where it is unmapped via kunmap(). The pointer can be handed to
30 : * other contexts.
31 : *
32 : * For highmem pages on 32bit systems this can be slow as the mapping space
33 : * is limited and protected by a global lock. In case that there is no
34 : * mapping slot available the function blocks until a slot is released via
35 : * kunmap().
36 : */
37 : static inline void *kmap(struct page *page);
38 :
39 : /**
40 : * kunmap - Unmap the virtual address mapped by kmap()
41 : * @addr: Virtual address to be unmapped
42 : *
43 : * Counterpart to kmap(). A NOOP for CONFIG_HIGHMEM=n and for mappings of
44 : * pages in the low memory area.
45 : */
46 : static inline void kunmap(struct page *page);
47 :
48 : /**
49 : * kmap_to_page - Get the page for a kmap'ed address
50 : * @addr: The address to look up
51 : *
52 : * Returns: The page which is mapped to @addr.
53 : */
54 : static inline struct page *kmap_to_page(void *addr);
55 :
56 : /**
57 : * kmap_flush_unused - Flush all unused kmap mappings in order to
58 : * remove stray mappings
59 : */
60 : static inline void kmap_flush_unused(void);
61 :
62 : /**
63 : * kmap_local_page - Map a page for temporary usage
64 : * @page: Pointer to the page to be mapped
65 : *
66 : * Returns: The virtual address of the mapping
67 : *
68 : * Can be invoked from any context.
69 : *
70 : * Requires careful handling when nesting multiple mappings because the map
71 : * management is stack based. The unmap has to be in the reverse order of
72 : * the map operation:
73 : *
74 : * addr1 = kmap_local_page(page1);
75 : * addr2 = kmap_local_page(page2);
76 : * ...
77 : * kunmap_local(addr2);
78 : * kunmap_local(addr1);
79 : *
80 : * Unmapping addr1 before addr2 is invalid and causes malfunction.
81 : *
82 : * Contrary to kmap() mappings the mapping is only valid in the context of
83 : * the caller and cannot be handed to other contexts.
84 : *
85 : * On CONFIG_HIGHMEM=n kernels and for low memory pages this returns the
86 : * virtual address of the direct mapping. Only real highmem pages are
87 : * temporarily mapped.
88 : *
89 : * While it is significantly faster than kmap() for the higmem case it
90 : * comes with restrictions about the pointer validity. Only use when really
91 : * necessary.
92 : *
93 : * On HIGHMEM enabled systems mapping a highmem page has the side effect of
94 : * disabling migration in order to keep the virtual address stable across
95 : * preemption. No caller of kmap_local_page() can rely on this side effect.
96 : */
97 : static inline void *kmap_local_page(struct page *page);
98 :
99 : /**
100 : * kmap_atomic - Atomically map a page for temporary usage - Deprecated!
101 : * @page: Pointer to the page to be mapped
102 : *
103 : * Returns: The virtual address of the mapping
104 : *
105 : * Effectively a wrapper around kmap_local_page() which disables pagefaults
106 : * and preemption.
107 : *
108 : * Do not use in new code. Use kmap_local_page() instead.
109 : */
110 : static inline void *kmap_atomic(struct page *page);
111 :
112 : /**
113 : * kunmap_atomic - Unmap the virtual address mapped by kmap_atomic()
114 : * @addr: Virtual address to be unmapped
115 : *
116 : * Counterpart to kmap_atomic().
117 : *
118 : * Effectively a wrapper around kunmap_local() which additionally undoes
119 : * the side effects of kmap_atomic(), i.e. reenabling pagefaults and
120 : * preemption.
121 : */
122 :
123 : /* Highmem related interfaces for management code */
124 : static inline unsigned int nr_free_highpages(void);
125 : static inline unsigned long totalhigh_pages(void);
126 :
127 : #ifndef ARCH_HAS_FLUSH_ANON_PAGE
128 7770 : static inline void flush_anon_page(struct vm_area_struct *vma, struct page *page, unsigned long vmaddr)
129 : {
130 7770 : }
131 : #endif
132 :
133 : #ifndef ARCH_HAS_FLUSH_KERNEL_DCACHE_PAGE
134 8477 : static inline void flush_kernel_dcache_page(struct page *page)
135 : {
136 8477 : }
137 0 : static inline void flush_kernel_vmap_range(void *vaddr, int size)
138 : {
139 0 : }
140 : static inline void invalidate_kernel_vmap_range(void *vaddr, int size)
141 : {
142 : }
143 : #endif
144 :
145 : /* when CONFIG_HIGHMEM is not set these will be plain clear/copy_page */
146 : #ifndef clear_user_highpage
147 9718 : static inline void clear_user_highpage(struct page *page, unsigned long vaddr)
148 : {
149 9718 : void *addr = kmap_atomic(page);
150 9718 : clear_user_page(addr, vaddr, page);
151 9718 : kunmap_atomic(addr);
152 9718 : }
153 : #endif
154 :
155 : #ifndef __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE
156 : /**
157 : * __alloc_zeroed_user_highpage - Allocate a zeroed HIGHMEM page for a VMA with caller-specified movable GFP flags
158 : * @movableflags: The GFP flags related to the pages future ability to move like __GFP_MOVABLE
159 : * @vma: The VMA the page is to be allocated for
160 : * @vaddr: The virtual address the page will be inserted into
161 : *
162 : * This function will allocate a page for a VMA but the caller is expected
163 : * to specify via movableflags whether the page will be movable in the
164 : * future or not
165 : *
166 : * An architecture may override this function by defining
167 : * __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE and providing their own
168 : * implementation.
169 : */
170 : static inline struct page *
171 : __alloc_zeroed_user_highpage(gfp_t movableflags,
172 : struct vm_area_struct *vma,
173 : unsigned long vaddr)
174 : {
175 : struct page *page = alloc_page_vma(GFP_HIGHUSER | movableflags,
176 : vma, vaddr);
177 :
178 : if (page)
179 : clear_user_highpage(page, vaddr);
180 :
181 : return page;
182 : }
183 : #endif
184 :
185 : /**
186 : * alloc_zeroed_user_highpage_movable - Allocate a zeroed HIGHMEM page for a VMA that the caller knows can move
187 : * @vma: The VMA the page is to be allocated for
188 : * @vaddr: The virtual address the page will be inserted into
189 : *
190 : * This function will allocate a page for a VMA that the caller knows will
191 : * be able to migrate in the future using move_pages() or reclaimed
192 : */
193 : static inline struct page *
194 30318 : alloc_zeroed_user_highpage_movable(struct vm_area_struct *vma,
195 : unsigned long vaddr)
196 : {
197 30318 : return __alloc_zeroed_user_highpage(__GFP_MOVABLE, vma, vaddr);
198 : }
199 :
200 84839 : static inline void clear_highpage(struct page *page)
201 : {
202 84839 : void *kaddr = kmap_atomic(page);
203 84842 : clear_page(kaddr);
204 84836 : kunmap_atomic(kaddr);
205 84837 : }
206 :
207 : /*
208 : * If we pass in a base or tail page, we can zero up to PAGE_SIZE.
209 : * If we pass in a head page, we can zero up to the size of the compound page.
210 : */
211 : #if defined(CONFIG_HIGHMEM) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
212 : void zero_user_segments(struct page *page, unsigned start1, unsigned end1,
213 : unsigned start2, unsigned end2);
214 : #else /* !HIGHMEM || !TRANSPARENT_HUGEPAGE */
215 631 : static inline void zero_user_segments(struct page *page,
216 : unsigned start1, unsigned end1,
217 : unsigned start2, unsigned end2)
218 : {
219 631 : void *kaddr = kmap_atomic(page);
220 631 : unsigned int i;
221 :
222 631 : BUG_ON(end1 > page_size(page) || end2 > page_size(page));
223 :
224 631 : if (end1 > start1)
225 495 : memset(kaddr + start1, 0, end1 - start1);
226 :
227 631 : if (end2 > start2)
228 136 : memset(kaddr + start2, 0, end2 - start2);
229 :
230 631 : kunmap_atomic(kaddr);
231 1262 : for (i = 0; i < compound_nr(page); i++)
232 631 : flush_dcache_page(page + i);
233 631 : }
234 : #endif /* !HIGHMEM || !TRANSPARENT_HUGEPAGE */
235 :
236 80 : static inline void zero_user_segment(struct page *page,
237 : unsigned start, unsigned end)
238 : {
239 80 : zero_user_segments(page, start, end, 0, 0);
240 29 : }
241 :
242 2 : static inline void zero_user(struct page *page,
243 : unsigned start, unsigned size)
244 : {
245 2 : zero_user_segments(page, start, start + size, 0, 0);
246 0 : }
247 :
248 : #ifndef __HAVE_ARCH_COPY_USER_HIGHPAGE
249 :
250 37990 : static inline void copy_user_highpage(struct page *to, struct page *from,
251 : unsigned long vaddr, struct vm_area_struct *vma)
252 : {
253 37990 : char *vfrom, *vto;
254 :
255 37990 : vfrom = kmap_atomic(from);
256 37992 : vto = kmap_atomic(to);
257 37990 : copy_user_page(vto, vfrom, vaddr, to);
258 37989 : kunmap_atomic(vto);
259 37989 : kunmap_atomic(vfrom);
260 37989 : }
261 :
262 : #endif
263 :
264 : #ifndef __HAVE_ARCH_COPY_HIGHPAGE
265 :
266 0 : static inline void copy_highpage(struct page *to, struct page *from)
267 : {
268 0 : char *vfrom, *vto;
269 :
270 0 : vfrom = kmap_atomic(from);
271 0 : vto = kmap_atomic(to);
272 0 : copy_page(vto, vfrom);
273 0 : kunmap_atomic(vto);
274 0 : kunmap_atomic(vfrom);
275 0 : }
276 :
277 : #endif
278 :
279 : static inline void memcpy_page(struct page *dst_page, size_t dst_off,
280 : struct page *src_page, size_t src_off,
281 : size_t len)
282 : {
283 : char *dst = kmap_local_page(dst_page);
284 : char *src = kmap_local_page(src_page);
285 :
286 : VM_BUG_ON(dst_off + len > PAGE_SIZE || src_off + len > PAGE_SIZE);
287 : memcpy(dst + dst_off, src + src_off, len);
288 : kunmap_local(src);
289 : kunmap_local(dst);
290 : }
291 :
292 : static inline void memmove_page(struct page *dst_page, size_t dst_off,
293 : struct page *src_page, size_t src_off,
294 : size_t len)
295 : {
296 : char *dst = kmap_local_page(dst_page);
297 : char *src = kmap_local_page(src_page);
298 :
299 : VM_BUG_ON(dst_off + len > PAGE_SIZE || src_off + len > PAGE_SIZE);
300 : memmove(dst + dst_off, src + src_off, len);
301 : kunmap_local(src);
302 : kunmap_local(dst);
303 : }
304 :
305 : static inline void memset_page(struct page *page, size_t offset, int val,
306 : size_t len)
307 : {
308 : char *addr = kmap_local_page(page);
309 :
310 : VM_BUG_ON(offset + len > PAGE_SIZE);
311 : memset(addr + offset, val, len);
312 : kunmap_local(addr);
313 : }
314 :
315 576 : static inline void memcpy_from_page(char *to, struct page *page,
316 : size_t offset, size_t len)
317 : {
318 576 : char *from = kmap_local_page(page);
319 :
320 576 : VM_BUG_ON(offset + len > PAGE_SIZE);
321 576 : memcpy(to, from + offset, len);
322 576 : kunmap_local(from);
323 576 : }
324 :
325 0 : static inline void memcpy_to_page(struct page *page, size_t offset,
326 : const char *from, size_t len)
327 : {
328 0 : char *to = kmap_local_page(page);
329 :
330 0 : VM_BUG_ON(offset + len > PAGE_SIZE);
331 0 : memcpy(to + offset, from, len);
332 0 : kunmap_local(to);
333 0 : }
334 :
335 : #endif /* _LINUX_HIGHMEM_H */
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