| 1 |
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| 2 | #ifndef _LINUX_HIGHMEM_H
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| 3 | #define _LINUX_HIGHMEM_H
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| 4 |
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| 5 | #include <linux/fs.h>
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| 6 | #include <linux/kernel.h>
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| 7 | #include <linux/bug.h>
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| 8 | #include <linux/cacheflush.h>
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| 9 | #include <linux/kmsan.h>
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| 10 | #include <linux/mm.h>
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| 11 | #include <linux/uaccess.h>
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| 12 | #include <linux/hardirq.h>
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| 13 |
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| 14 | #include "highmem-internal.h"
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| 15 |
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| 16 | |
| 17 | * kmap - Map a page for long term usage
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| 18 | * @page: Pointer to the page to be mapped
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| 19 | *
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| 20 | * Returns: The virtual address of the mapping
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| 21 | *
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| 22 | * Can only be invoked from preemptible task context because on 32bit
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| 23 | * systems with CONFIG_HIGHMEM enabled this function might sleep.
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| 24 | *
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| 25 | * For systems with CONFIG_HIGHMEM=n and for pages in the low memory area
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| 26 | * this returns the virtual address of the direct kernel mapping.
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| 27 | *
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| 28 | * The returned virtual address is globally visible and valid up to the
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| 29 | * point where it is unmapped via kunmap(). The pointer can be handed to
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| 30 | * other contexts.
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| 31 | *
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| 32 | * For highmem pages on 32bit systems this can be slow as the mapping space
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| 33 | * is limited and protected by a global lock. In case that there is no
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| 34 | * mapping slot available the function blocks until a slot is released via
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| 35 | * kunmap().
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| 36 |
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| 37 | static inline void *kmap(struct page *page);
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| 38 |
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| 39 | |
| 40 | * kunmap - Unmap the virtual address mapped by kmap()
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| 41 | * @page: Pointer to the page which was mapped by kmap()
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| 42 | *
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| 43 | * Counterpart to kmap(). A NOOP for CONFIG_HIGHMEM=n and for mappings of
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| 44 | * pages in the low memory area.
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| 45 |
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| 46 | static inline void kunmap(struct page *page);
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| 47 |
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| 48 | |
| 49 | * kmap_to_page - Get the page for a kmap'ed address
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| 50 | * @addr: The address to look up
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| 51 | *
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| 52 | * Returns: The page which is mapped to @addr.
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| 53 |
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| 54 | static inline struct page *kmap_to_page(void *addr);
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| 55 |
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| 56 | |
| 57 | * kmap_flush_unused - Flush all unused kmap mappings in order to
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| 58 | * remove stray mappings
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| 59 |
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| 60 | static inline void kmap_flush_unused(void);
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| 61 |
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| 62 | |
| 63 | * kmap_local_page - Map a page for temporary usage
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| 64 | * @page: Pointer to the page to be mapped
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| 65 | *
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| 66 | * Returns: The virtual address of the mapping
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| 67 | *
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| 68 | * Can be invoked from any context, including interrupts.
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| 69 | *
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| 70 | * Requires careful handling when nesting multiple mappings because the map
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| 71 | * management is stack based. The unmap has to be in the reverse order of
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| 72 | * the map operation:
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| 73 | *
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| 74 | * addr1 = kmap_local_page(page1);
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| 75 | * addr2 = kmap_local_page(page2);
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| 76 | * ...
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| 77 | * kunmap_local(addr2);
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| 78 | * kunmap_local(addr1);
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| 79 | *
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| 80 | * Unmapping addr1 before addr2 is invalid and causes malfunction.
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| 81 | *
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| 82 | * Contrary to kmap() mappings the mapping is only valid in the context of
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| 83 | * the caller and cannot be handed to other contexts.
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| 84 | *
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| 85 | * On CONFIG_HIGHMEM=n kernels and for low memory pages this returns the
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| 86 | * virtual address of the direct mapping. Only real highmem pages are
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| 87 | * temporarily mapped.
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| 88 | *
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| 89 | * While kmap_local_page() is significantly faster than kmap() for the highmem
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| 90 | * case it comes with restrictions about the pointer validity.
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| 91 | *
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| 92 | * On HIGHMEM enabled systems mapping a highmem page has the side effect of
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| 93 | * disabling migration in order to keep the virtual address stable across
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| 94 | * preemption. No caller of kmap_local_page() can rely on this side effect.
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| 95 |
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| 96 | static inline void *kmap_local_page(struct page *page);
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| 97 |
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| 98 | |
| 99 | * kmap_local_folio - Map a page in this folio for temporary usage
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| 100 | * @folio: The folio containing the page.
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| 101 | * @offset: The byte offset within the folio which identifies the page.
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| 102 | *
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| 103 | * Requires careful handling when nesting multiple mappings because the map
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| 104 | * management is stack based. The unmap has to be in the reverse order of
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| 105 | * the map operation::
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| 106 | *
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| 107 | * addr1 = kmap_local_folio(folio1, offset1);
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| 108 | * addr2 = kmap_local_folio(folio2, offset2);
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| 109 | * ...
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| 110 | * kunmap_local(addr2);
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| 111 | * kunmap_local(addr1);
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| 112 | *
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| 113 | * Unmapping addr1 before addr2 is invalid and causes malfunction.
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| 114 | *
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| 115 | * Contrary to kmap() mappings the mapping is only valid in the context of
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| 116 | * the caller and cannot be handed to other contexts.
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| 117 | *
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| 118 | * On CONFIG_HIGHMEM=n kernels and for low memory pages this returns the
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| 119 | * virtual address of the direct mapping. Only real highmem pages are
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| 120 | * temporarily mapped.
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| 121 | *
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| 122 | * While it is significantly faster than kmap() for the highmem case it
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| 123 | * comes with restrictions about the pointer validity.
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| 124 | *
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| 125 | * On HIGHMEM enabled systems mapping a highmem page has the side effect of
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| 126 | * disabling migration in order to keep the virtual address stable across
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| 127 | * preemption. No caller of kmap_local_folio() can rely on this side effect.
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| 128 | *
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| 129 | * Context: Can be invoked from any context.
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| 130 | * Return: The virtual address of @offset.
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| 131 |
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| 132 | static inline void *kmap_local_folio(struct folio *folio, size_t offset);
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| 133 |
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| 134 | |
| 135 | * kmap_atomic - Atomically map a page for temporary usage - Deprecated!
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| 136 | * @page: Pointer to the page to be mapped
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| 137 | *
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| 138 | * Returns: The virtual address of the mapping
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| 139 | *
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| 140 | * In fact a wrapper around kmap_local_page() which also disables pagefaults
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| 141 | * and, depending on PREEMPT_RT configuration, also CPU migration and
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| 142 | * preemption. Therefore users should not count on the latter two side effects.
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| 143 | *
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| 144 | * Mappings should always be released by kunmap_atomic().
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| 145 | *
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| 146 | * Do not use in new code. Use kmap_local_page() instead.
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| 147 | *
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| 148 | * It is used in atomic context when code wants to access the contents of a
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| 149 | * page that might be allocated from high memory (see __GFP_HIGHMEM), for
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| 150 | * example a page in the pagecache. The API has two functions, and they
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| 151 | * can be used in a manner similar to the following::
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| 152 | *
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| 153 | * // Find the page of interest.
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| 154 | * struct page *page = find_get_page(mapping, offset);
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| 155 | *
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| 156 | * // Gain access to the contents of that page.
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| 157 | * void *vaddr = kmap_atomic(page);
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| 158 | *
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| 159 | * // Do something to the contents of that page.
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| 160 | * memset(vaddr, 0, PAGE_SIZE);
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| 161 | *
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| 162 | * // Unmap that page.
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| 163 | * kunmap_atomic(vaddr);
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| 164 | *
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| 165 | * Note that the kunmap_atomic() call takes the result of the kmap_atomic()
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| 166 | * call, not the argument.
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| 167 | *
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| 168 | * If you need to map two pages because you want to copy from one page to
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| 169 | * another you need to keep the kmap_atomic calls strictly nested, like:
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| 170 | *
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| 171 | * vaddr1 = kmap_atomic(page1);
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| 172 | * vaddr2 = kmap_atomic(page2);
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| 173 | *
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| 174 | * memcpy(vaddr1, vaddr2, PAGE_SIZE);
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| 175 | *
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| 176 | * kunmap_atomic(vaddr2);
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| 177 | * kunmap_atomic(vaddr1);
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| 178 |
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| 179 | static inline void *kmap_atomic(struct page *page);
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| 180 |
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| 181 |
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| 182 | static inline unsigned long nr_free_highpages(void);
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| 183 | static inline unsigned long totalhigh_pages(void);
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| 184 |
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| 185 | #ifndef ARCH_HAS_FLUSH_ANON_PAGE
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| 186 | static inline void flush_anon_page(struct vm_area_struct *vma, struct page *page, unsigned long vmaddr)
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| 187 | {
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| 188 | }
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| 189 | #endif
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| 190 |
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| 191 | #ifndef ARCH_IMPLEMENTS_FLUSH_KERNEL_VMAP_RANGE
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| 192 | static inline void flush_kernel_vmap_range(void *vaddr, int size)
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| 193 | {
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| 194 | }
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| 195 | static inline void invalidate_kernel_vmap_range(void *vaddr, int size)
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| 196 | {
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| 197 | }
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| 198 | #endif
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| 199 |
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| 200 |
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| 201 | #ifndef clear_user_highpage
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| 202 | static inline void clear_user_highpage(struct page *page, unsigned long vaddr)
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| 203 | {
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| 204 | void *addr = kmap_local_page(page);
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| 205 | clear_user_page(addr, vaddr, page);
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| 206 | kunmap_local(addr);
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| 207 | }
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| 208 | #endif
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| 209 |
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| 210 | #ifndef vma_alloc_zeroed_movable_folio
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| 211 | |
| 212 | * vma_alloc_zeroed_movable_folio - Allocate a zeroed page for a VMA.
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| 213 | * @vma: The VMA the page is to be allocated for.
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| 214 | * @vaddr: The virtual address the page will be inserted into.
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| 215 | *
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| 216 | * This function will allocate a page suitable for inserting into this
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| 217 | * VMA at this virtual address. It may be allocated from highmem or
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| 218 | * the movable zone. An architecture may provide its own implementation.
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| 219 | *
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| 220 | * Return: A folio containing one allocated and zeroed page or NULL if
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| 221 | * we are out of memory.
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| 222 |
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| 223 | static inline
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| 224 | struct folio *vma_alloc_zeroed_movable_folio(struct vm_area_struct *vma,
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| 225 | unsigned long vaddr)
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| 226 | {
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| 227 | struct folio *folio;
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| 228 |
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| 229 | folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, vaddr);
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| 230 | if (folio && user_alloc_needs_zeroing())
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| 231 | clear_user_highpage(&folio->page, vaddr);
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| 232 |
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| 233 | return folio;
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| 234 | }
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| 235 | #endif
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| 236 |
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| 237 | static inline void clear_highpage(struct page *page)
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| 238 | {
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| 239 | void *kaddr = kmap_local_page(page);
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| 240 | clear_page(kaddr);
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| 241 | kunmap_local(kaddr);
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| 242 | }
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| 243 |
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| 244 | static inline void clear_highpage_kasan_tagged(struct page *page)
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| 245 | {
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| 246 | void *kaddr = kmap_local_page(page);
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| 247 |
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| 248 | clear_page(kasan_reset_tag(kaddr));
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| 249 | kunmap_local(kaddr);
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| 250 | }
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| 251 |
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| 252 | #ifndef __HAVE_ARCH_TAG_CLEAR_HIGHPAGE
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| 253 |
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| 254 | static inline void tag_clear_highpage(struct page *page)
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| 255 | {
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| 256 | }
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| 257 |
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| 258 | #endif
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| 259 |
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| 260 | |
| 261 | * If we pass in a base or tail page, we can zero up to PAGE_SIZE.
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| 262 | * If we pass in a head page, we can zero up to the size of the compound page.
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| 263 |
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| 264 | #ifdef CONFIG_HIGHMEM
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| 265 | void zero_user_segments(struct page *page, unsigned start1, unsigned end1,
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| 266 | unsigned start2, unsigned end2);
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| 267 | #else
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| 268 | static inline void zero_user_segments(struct page *page,
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| 269 | unsigned start1, unsigned end1,
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| 270 | unsigned start2, unsigned end2)
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| 271 | {
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| 272 | void *kaddr = kmap_local_page(page);
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| 273 | unsigned int i;
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| 274 |
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| 275 | BUG_ON(end1 > page_size(page) || end2 > page_size(page));
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| 276 |
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| 277 | if (end1 > start1)
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| 278 | memset(kaddr + start1, 0, end1 - start1);
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| 279 |
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| 280 | if (end2 > start2)
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| 281 | memset(kaddr + start2, 0, end2 - start2);
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| 282 |
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| 283 | kunmap_local(kaddr);
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| 284 | for (i = 0; i < compound_nr(page); i++)
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| 285 | flush_dcache_page(page + i);
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| 286 | }
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| 287 | #endif
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| 288 |
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| 289 | static inline void zero_user_segment(struct page *page,
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| 290 | unsigned start, unsigned end)
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| 291 | {
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| 292 | zero_user_segments(page, start, end, 0, 0);
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| 293 | }
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| 294 |
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| 295 | static inline void zero_user(struct page *page,
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| 296 | unsigned start, unsigned size)
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| 297 | {
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| 298 | zero_user_segments(page, start, start + size, 0, 0);
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| 299 | }
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| 300 |
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| 301 | #ifndef __HAVE_ARCH_COPY_USER_HIGHPAGE
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| 302 |
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| 303 | static inline void copy_user_highpage(struct page *to, struct page *from,
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| 304 | unsigned long vaddr, struct vm_area_struct *vma)
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| 305 | {
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| 306 | char *vfrom, *vto;
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| 307 |
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| 308 | vfrom = kmap_local_page(from);
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| 309 | vto = kmap_local_page(to);
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| 310 | copy_user_page(vto, vfrom, vaddr, to);
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| 311 | kmsan_unpoison_memory(page_address(to), PAGE_SIZE);
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| 312 | kunmap_local(vto);
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| 313 | kunmap_local(vfrom);
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| 314 | }
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| 315 |
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| 316 | #endif
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| 317 |
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| 318 | #ifndef __HAVE_ARCH_COPY_HIGHPAGE
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| 319 |
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| 320 | static inline void copy_highpage(struct page *to, struct page *from)
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| 321 | {
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| 322 | char *vfrom, *vto;
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| 323 |
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| 324 | vfrom = kmap_local_page(from);
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| 325 | vto = kmap_local_page(to);
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| 326 | copy_page(vto, vfrom);
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| 327 | kmsan_copy_page_meta(to, from);
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| 328 | kunmap_local(vto);
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| 329 | kunmap_local(vfrom);
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| 330 | }
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| 331 |
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| 332 | #endif
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| 333 |
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| 334 | #ifdef copy_mc_to_kernel
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| 335 | |
| 336 | * If architecture supports machine check exception handling, define the
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| 337 | * #MC versions of copy_user_highpage and copy_highpage. They copy a memory
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| 338 | * page with #MC in source page (@from) handled, and return the number
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| 339 | * of bytes not copied if there was a #MC, otherwise 0 for success.
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| 340 |
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| 341 | static inline int copy_mc_user_highpage(struct page *to, struct page *from,
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| 342 | unsigned long vaddr, struct vm_area_struct *vma)
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| 343 | {
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| 344 | unsigned long ret;
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| 345 | char *vfrom, *vto;
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| 346 |
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| 347 | vfrom = kmap_local_page(from);
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| 348 | vto = kmap_local_page(to);
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| 349 | ret = copy_mc_to_kernel(vto, vfrom, PAGE_SIZE);
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| 350 | if (!ret)
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| 351 | kmsan_unpoison_memory(page_address(to), PAGE_SIZE);
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| 352 | kunmap_local(vto);
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| 353 | kunmap_local(vfrom);
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| 354 |
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| 355 | if (ret)
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| 356 | memory_failure_queue(page_to_pfn(from), 0);
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| 357 |
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| 358 | return ret;
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| 359 | }
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| 360 |
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| 361 | static inline int copy_mc_highpage(struct page *to, struct page *from)
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| 362 | {
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| 363 | unsigned long ret;
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| 364 | char *vfrom, *vto;
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| 365 |
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| 366 | vfrom = kmap_local_page(from);
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| 367 | vto = kmap_local_page(to);
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| 368 | ret = copy_mc_to_kernel(vto, vfrom, PAGE_SIZE);
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| 369 | if (!ret)
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| 370 | kmsan_copy_page_meta(to, from);
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| 371 | kunmap_local(vto);
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| 372 | kunmap_local(vfrom);
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| 373 |
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| 374 | if (ret)
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| 375 | memory_failure_queue(page_to_pfn(from), 0);
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| 376 |
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| 377 | return ret;
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| 378 | }
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| 379 | #else
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| 380 | static inline int copy_mc_user_highpage(struct page *to, struct page *from,
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| 381 | unsigned long vaddr, struct vm_area_struct *vma)
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| 382 | {
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| 383 | copy_user_highpage(to, from, vaddr, vma);
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| 384 | return 0;
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| 385 | }
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| 386 |
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| 387 | static inline int copy_mc_highpage(struct page *to, struct page *from)
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| 388 | {
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| 389 | copy_highpage(to, from);
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| 390 | return 0;
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| 391 | }
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| 392 | #endif
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| 393 |
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| 394 | static inline void memcpy_page(struct page *dst_page, size_t dst_off,
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| 395 | struct page *src_page, size_t src_off,
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| 396 | size_t len)
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| 397 | {
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| 398 | char *dst = kmap_local_page(dst_page);
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| 399 | char *src = kmap_local_page(src_page);
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| 400 |
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| 401 | VM_BUG_ON(dst_off + len > PAGE_SIZE || src_off + len > PAGE_SIZE);
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| 402 | memcpy(dst + dst_off, src + src_off, len);
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| 403 | kunmap_local(src);
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| 404 | kunmap_local(dst);
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| 405 | }
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| 406 |
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| 407 | static inline void memcpy_folio(struct folio *dst_folio, size_t dst_off,
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| 408 | struct folio *src_folio, size_t src_off, size_t len)
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| 409 | {
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| 410 | VM_BUG_ON(dst_off + len > folio_size(dst_folio));
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| 411 | VM_BUG_ON(src_off + len > folio_size(src_folio));
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| 412 |
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| 413 | do {
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| 414 | char *dst = kmap_local_folio(dst_folio, dst_off);
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| 415 | const char *src = kmap_local_folio(src_folio, src_off);
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| 416 | size_t chunk = len;
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| 417 |
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| 418 | if (folio_test_highmem(dst_folio) &&
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| 419 | chunk > PAGE_SIZE - offset_in_page(dst_off))
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| 420 | chunk = PAGE_SIZE - offset_in_page(dst_off);
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| 421 | if (folio_test_highmem(src_folio) &&
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| 422 | chunk > PAGE_SIZE - offset_in_page(src_off))
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| 423 | chunk = PAGE_SIZE - offset_in_page(src_off);
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| 424 | memcpy(dst, src, chunk);
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| 425 | kunmap_local(src);
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| 426 | kunmap_local(dst);
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| 427 |
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| 428 | dst_off += chunk;
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| 429 | src_off += chunk;
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| 430 | len -= chunk;
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| 431 | } while (len > 0);
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| 432 | }
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| 433 |
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| 434 | static inline void memset_page(struct page *page, size_t offset, int val,
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| 435 | size_t len)
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| 436 | {
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| 437 | char *addr = kmap_local_page(page);
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| 438 |
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| 439 | VM_BUG_ON(offset + len > PAGE_SIZE);
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| 440 | memset(addr + offset, val, len);
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| 441 | kunmap_local(addr);
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| 442 | }
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| 443 |
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| 444 | static inline void memcpy_from_page(char *to, struct page *page,
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| 445 | size_t offset, size_t len)
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| 446 | {
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| 447 | char *from = kmap_local_page(page);
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| 448 |
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| 449 | VM_BUG_ON(offset + len > PAGE_SIZE);
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| 450 | memcpy(to, from + offset, len);
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| 451 | kunmap_local(from);
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| 452 | }
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| 453 |
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| 454 | static inline void memcpy_to_page(struct page *page, size_t offset,
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| 455 | const char *from, size_t len)
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| 456 | {
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| 457 | char *to = kmap_local_page(page);
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| 458 |
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| 459 | VM_BUG_ON(offset + len > PAGE_SIZE);
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| 460 | memcpy(to + offset, from, len);
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| 461 | flush_dcache_page(page);
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| 462 | kunmap_local(to);
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| 463 | }
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| 464 |
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| 465 | static inline void memzero_page(struct page *page, size_t offset, size_t len)
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| 466 | {
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| 467 | char *addr = kmap_local_page(page);
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| 468 |
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| 469 | VM_BUG_ON(offset + len > PAGE_SIZE);
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| 470 | memset(addr + offset, 0, len);
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| 471 | flush_dcache_page(page);
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| 472 | kunmap_local(addr);
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| 473 | }
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| 474 |
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| 475 | |
| 476 | * memcpy_from_folio - Copy a range of bytes from a folio.
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| 477 | * @to: The memory to copy to.
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| 478 | * @folio: The folio to read from.
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| 479 | * @offset: The first byte in the folio to read.
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| 480 | * @len: The number of bytes to copy.
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| 481 |
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| 482 | static inline void memcpy_from_folio(char *to, struct folio *folio,
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| 483 | size_t offset, size_t len)
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| 484 | {
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| 485 | VM_BUG_ON(offset + len > folio_size(folio));
|
| 486 |
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| 487 | do {
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| 488 | const char *from = kmap_local_folio(folio, offset);
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| 489 | size_t chunk = len;
|
| 490 |
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| 491 | if (folio_test_partial_kmap(folio) &&
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| 492 | chunk > PAGE_SIZE - offset_in_page(offset))
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| 493 | chunk = PAGE_SIZE - offset_in_page(offset);
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| 494 | memcpy(to, from, chunk);
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| 495 | kunmap_local(from);
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| 496 |
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| 497 | to += chunk;
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| 498 | offset += chunk;
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| 499 | len -= chunk;
|
| 500 | } while (len > 0);
|
| 501 | }
|
| 502 |
|
| 503 | |
| 504 | * memcpy_to_folio - Copy a range of bytes to a folio.
|
| 505 | * @folio: The folio to write to.
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| 506 | * @offset: The first byte in the folio to store to.
|
| 507 | * @from: The memory to copy from.
|
| 508 | * @len: The number of bytes to copy.
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| 509 |
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| 510 | static inline void memcpy_to_folio(struct folio *folio, size_t offset,
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| 511 | const char *from, size_t len)
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| 512 | {
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| 513 | VM_BUG_ON(offset + len > folio_size(folio));
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| 514 |
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| 515 | do {
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| 516 | char *to = kmap_local_folio(folio, offset);
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| 517 | size_t chunk = len;
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| 518 |
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| 519 | if (folio_test_partial_kmap(folio) &&
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| 520 | chunk > PAGE_SIZE - offset_in_page(offset))
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| 521 | chunk = PAGE_SIZE - offset_in_page(offset);
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| 522 | memcpy(to, from, chunk);
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| 523 | kunmap_local(to);
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| 524 |
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| 525 | from += chunk;
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| 526 | offset += chunk;
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| 527 | len -= chunk;
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| 528 | } while (len > 0);
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| 529 |
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| 530 | flush_dcache_folio(folio);
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| 531 | }
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| 532 |
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| 533 | |
| 534 | * folio_zero_tail - Zero the tail of a folio.
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| 535 | * @folio: The folio to zero.
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| 536 | * @offset: The byte offset in the folio to start zeroing at.
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| 537 | * @kaddr: The address the folio is currently mapped to.
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| 538 | *
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| 539 | * If you have already used kmap_local_folio() to map a folio, written
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| 540 | * some data to it and now need to zero the end of the folio (and flush
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| 541 | * the dcache), you can use this function. If you do not have the
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| 542 | * folio kmapped (eg the folio has been partially populated by DMA),
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| 543 | * use folio_zero_range() or folio_zero_segment() instead.
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| 544 | *
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| 545 | * Return: An address which can be passed to kunmap_local().
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| 546 |
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| 547 | static inline __must_check void *folio_zero_tail(struct folio *folio,
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| 548 | size_t offset, void *kaddr)
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| 549 | {
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| 550 | size_t len = folio_size(folio) - offset;
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| 551 |
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| 552 | if (folio_test_partial_kmap(folio)) {
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| 553 | size_t max = PAGE_SIZE - offset_in_page(offset);
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| 554 |
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| 555 | while (len > max) {
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| 556 | memset(kaddr, 0, max);
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| 557 | kunmap_local(kaddr);
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| 558 | len -= max;
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| 559 | offset += max;
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| 560 | max = PAGE_SIZE;
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| 561 | kaddr = kmap_local_folio(folio, offset);
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| 562 | }
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| 563 | }
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| 564 |
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| 565 | memset(kaddr, 0, len);
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| 566 | flush_dcache_folio(folio);
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| 567 |
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| 568 | return kaddr;
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| 569 | }
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| 570 |
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| 571 | |
| 572 | * folio_fill_tail - Copy some data to a folio and pad with zeroes.
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| 573 | * @folio: The destination folio.
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| 574 | * @offset: The offset into @folio at which to start copying.
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| 575 | * @from: The data to copy.
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| 576 | * @len: How many bytes of data to copy.
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| 577 | *
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| 578 | * This function is most useful for filesystems which support inline data.
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| 579 | * When they want to copy data from the inode into the page cache, this
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| 580 | * function does everything for them. It supports large folios even on
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| 581 | * HIGHMEM configurations.
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| 582 |
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| 583 | static inline void folio_fill_tail(struct folio *folio, size_t offset,
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| 584 | const char *from, size_t len)
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| 585 | {
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| 586 | char *to = kmap_local_folio(folio, offset);
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| 587 |
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| 588 | VM_BUG_ON(offset + len > folio_size(folio));
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| 589 |
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| 590 | if (folio_test_partial_kmap(folio)) {
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| 591 | size_t max = PAGE_SIZE - offset_in_page(offset);
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| 592 |
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| 593 | while (len > max) {
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| 594 | memcpy(to, from, max);
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| 595 | kunmap_local(to);
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| 596 | len -= max;
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| 597 | from += max;
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| 598 | offset += max;
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| 599 | max = PAGE_SIZE;
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| 600 | to = kmap_local_folio(folio, offset);
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| 601 | }
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| 602 | }
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| 603 |
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| 604 | memcpy(to, from, len);
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| 605 | to = folio_zero_tail(folio, offset + len, to + len);
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| 606 | kunmap_local(to);
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| 607 | }
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| 608 |
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| 609 | |
| 610 | * memcpy_from_file_folio - Copy some bytes from a file folio.
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| 611 | * @to: The destination buffer.
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| 612 | * @folio: The folio to copy from.
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| 613 | * @pos: The position in the file.
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| 614 | * @len: The maximum number of bytes to copy.
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| 615 | *
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| 616 | * Copy up to @len bytes from this folio. This may be limited by PAGE_SIZE
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| 617 | * if the folio comes from HIGHMEM, and by the size of the folio.
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| 618 | *
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| 619 | * Return: The number of bytes copied from the folio.
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| 620 |
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| 621 | static inline size_t memcpy_from_file_folio(char *to, struct folio *folio,
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| 622 | loff_t pos, size_t len)
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| 623 | {
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| 624 | size_t offset = offset_in_folio(folio, pos);
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| 625 | char *from = kmap_local_folio(folio, offset);
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| 626 |
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| 627 | if (folio_test_partial_kmap(folio)) {
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| 628 | offset = offset_in_page(offset);
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| 629 | len = min_t(size_t, len, PAGE_SIZE - offset);
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| 630 | } else
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| 631 | len = min(len, folio_size(folio) - offset);
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| 632 |
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| 633 | memcpy(to, from, len);
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| 634 | kunmap_local(from);
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| 635 |
|
| 636 | return len;
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| 637 | }
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| 638 |
|
| 639 | |
| 640 | * folio_zero_segments() - Zero two byte ranges in a folio.
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| 641 | * @folio: The folio to write to.
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| 642 | * @start1: The first byte to zero.
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| 643 | * @xend1: One more than the last byte in the first range.
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| 644 | * @start2: The first byte to zero in the second range.
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| 645 | * @xend2: One more than the last byte in the second range.
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| 646 |
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| 647 | static inline void folio_zero_segments(struct folio *folio,
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| 648 | size_t start1, size_t xend1, size_t start2, size_t xend2)
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| 649 | {
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| 650 | zero_user_segments(&folio->page, start1, xend1, start2, xend2);
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| 651 | }
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| 652 |
|
| 653 | |
| 654 | * folio_zero_segment() - Zero a byte range in a folio.
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| 655 | * @folio: The folio to write to.
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| 656 | * @start: The first byte to zero.
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| 657 | * @xend: One more than the last byte to zero.
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| 658 |
|
| 659 | static inline void folio_zero_segment(struct folio *folio,
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| 660 | size_t start, size_t xend)
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| 661 | {
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| 662 | zero_user_segments(&folio->page, start, xend, 0, 0);
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| 663 | }
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| 664 |
|
| 665 | |
| 666 | * folio_zero_range() - Zero a byte range in a folio.
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| 667 | * @folio: The folio to write to.
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| 668 | * @start: The first byte to zero.
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| 669 | * @length: The number of bytes to zero.
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| 670 |
|
| 671 | static inline void folio_zero_range(struct folio *folio,
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| 672 | size_t start, size_t length)
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| 673 | {
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| 674 | zero_user_segments(&folio->page, start, start + length, 0, 0);
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| 675 | }
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| 676 |
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| 677 | |
| 678 | * folio_release_kmap - Unmap a folio and drop a refcount.
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| 679 | * @folio: The folio to release.
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| 680 | * @addr: The address previously returned by a call to kmap_local_folio().
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| 681 | *
|
| 682 | * It is common, eg in directory handling to kmap a folio. This function
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| 683 | * unmaps the folio and drops the refcount that was being held to keep the
|
| 684 | * folio alive while we accessed it.
|
| 685 |
|
| 686 | static inline void folio_release_kmap(struct folio *folio, void *addr)
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| 687 | {
|
| 688 | kunmap_local(addr);
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| 689 | folio_put(folio);
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| 690 | }
|
| 691 |
|
| 692 | static inline void unmap_and_put_page(struct page *page, void *addr)
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| 693 | {
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| 694 | folio_release_kmap(page_folio(page), addr);
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| 695 | }
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| 696 |
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| 697 | #endif
|