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- /* SPDX-License-Identifier: GPL-2.0 */
- #ifndef _LINUX_HIGHMEM_H
- #define _LINUX_HIGHMEM_H
- #include <linux/fs.h>
- #include <linux/kernel.h>
- #include <linux/bug.h>
- #include <linux/cacheflush.h>
- #include <linux/kmsan.h>
- #include <linux/mm.h>
- #include <linux/uaccess.h>
- #include <linux/hardirq.h>
- #include "highmem-internal.h"
- /**
- * kmap - Map a page for long term usage
- * @page: Pointer to the page to be mapped
- *
- * Returns: The virtual address of the mapping
- *
- * Can only be invoked from preemptible task context because on 32bit
- * systems with CONFIG_HIGHMEM enabled this function might sleep.
- *
- * For systems with CONFIG_HIGHMEM=n and for pages in the low memory area
- * this returns the virtual address of the direct kernel mapping.
- *
- * The returned virtual address is globally visible and valid up to the
- * point where it is unmapped via kunmap(). The pointer can be handed to
- * other contexts.
- *
- * For highmem pages on 32bit systems this can be slow as the mapping space
- * is limited and protected by a global lock. In case that there is no
- * mapping slot available the function blocks until a slot is released via
- * kunmap().
- */
- static inline void *kmap(struct page *page);
- /**
- * kunmap - Unmap the virtual address mapped by kmap()
- * @page: Pointer to the page which was mapped by kmap()
- *
- * Counterpart to kmap(). A NOOP for CONFIG_HIGHMEM=n and for mappings of
- * pages in the low memory area.
- */
- static inline void kunmap(struct page *page);
- /**
- * kmap_to_page - Get the page for a kmap'ed address
- * @addr: The address to look up
- *
- * Returns: The page which is mapped to @addr.
- */
- static inline struct page *kmap_to_page(void *addr);
- /**
- * kmap_flush_unused - Flush all unused kmap mappings in order to
- * remove stray mappings
- */
- static inline void kmap_flush_unused(void);
- /**
- * kmap_local_page - Map a page for temporary usage
- * @page: Pointer to the page to be mapped
- *
- * Returns: The virtual address of the mapping
- *
- * Can be invoked from any context, including interrupts.
- *
- * Requires careful handling when nesting multiple mappings because the map
- * management is stack based. The unmap has to be in the reverse order of
- * the map operation:
- *
- * addr1 = kmap_local_page(page1);
- * addr2 = kmap_local_page(page2);
- * ...
- * kunmap_local(addr2);
- * kunmap_local(addr1);
- *
- * Unmapping addr1 before addr2 is invalid and causes malfunction.
- *
- * Contrary to kmap() mappings the mapping is only valid in the context of
- * the caller and cannot be handed to other contexts.
- *
- * On CONFIG_HIGHMEM=n kernels and for low memory pages this returns the
- * virtual address of the direct mapping. Only real highmem pages are
- * temporarily mapped.
- *
- * While it is significantly faster than kmap() for the higmem case it
- * comes with restrictions about the pointer validity.
- *
- * On HIGHMEM enabled systems mapping a highmem page has the side effect of
- * disabling migration in order to keep the virtual address stable across
- * preemption. No caller of kmap_local_page() can rely on this side effect.
- */
- static inline void *kmap_local_page(struct page *page);
- /**
- * kmap_local_folio - Map a page in this folio for temporary usage
- * @folio: The folio containing the page.
- * @offset: The byte offset within the folio which identifies the page.
- *
- * Requires careful handling when nesting multiple mappings because the map
- * management is stack based. The unmap has to be in the reverse order of
- * the map operation::
- *
- * addr1 = kmap_local_folio(folio1, offset1);
- * addr2 = kmap_local_folio(folio2, offset2);
- * ...
- * kunmap_local(addr2);
- * kunmap_local(addr1);
- *
- * Unmapping addr1 before addr2 is invalid and causes malfunction.
- *
- * Contrary to kmap() mappings the mapping is only valid in the context of
- * the caller and cannot be handed to other contexts.
- *
- * On CONFIG_HIGHMEM=n kernels and for low memory pages this returns the
- * virtual address of the direct mapping. Only real highmem pages are
- * temporarily mapped.
- *
- * While it is significantly faster than kmap() for the higmem case it
- * comes with restrictions about the pointer validity. Only use when really
- * necessary.
- *
- * On HIGHMEM enabled systems mapping a highmem page has the side effect of
- * disabling migration in order to keep the virtual address stable across
- * preemption. No caller of kmap_local_folio() can rely on this side effect.
- *
- * Context: Can be invoked from any context.
- * Return: The virtual address of @offset.
- */
- static inline void *kmap_local_folio(struct folio *folio, size_t offset);
- /**
- * kmap_atomic - Atomically map a page for temporary usage - Deprecated!
- * @page: Pointer to the page to be mapped
- *
- * Returns: The virtual address of the mapping
- *
- * In fact a wrapper around kmap_local_page() which also disables pagefaults
- * and, depending on PREEMPT_RT configuration, also CPU migration and
- * preemption. Therefore users should not count on the latter two side effects.
- *
- * Mappings should always be released by kunmap_atomic().
- *
- * Do not use in new code. Use kmap_local_page() instead.
- *
- * It is used in atomic context when code wants to access the contents of a
- * page that might be allocated from high memory (see __GFP_HIGHMEM), for
- * example a page in the pagecache. The API has two functions, and they
- * can be used in a manner similar to the following::
- *
- * // Find the page of interest.
- * struct page *page = find_get_page(mapping, offset);
- *
- * // Gain access to the contents of that page.
- * void *vaddr = kmap_atomic(page);
- *
- * // Do something to the contents of that page.
- * memset(vaddr, 0, PAGE_SIZE);
- *
- * // Unmap that page.
- * kunmap_atomic(vaddr);
- *
- * Note that the kunmap_atomic() call takes the result of the kmap_atomic()
- * call, not the argument.
- *
- * If you need to map two pages because you want to copy from one page to
- * another you need to keep the kmap_atomic calls strictly nested, like:
- *
- * vaddr1 = kmap_atomic(page1);
- * vaddr2 = kmap_atomic(page2);
- *
- * memcpy(vaddr1, vaddr2, PAGE_SIZE);
- *
- * kunmap_atomic(vaddr2);
- * kunmap_atomic(vaddr1);
- */
- static inline void *kmap_atomic(struct page *page);
- /* Highmem related interfaces for management code */
- static inline unsigned int nr_free_highpages(void);
- static inline unsigned long totalhigh_pages(void);
- #ifndef ARCH_HAS_FLUSH_ANON_PAGE
- static inline void flush_anon_page(struct vm_area_struct *vma, struct page *page, unsigned long vmaddr)
- {
- }
- #endif
- #ifndef ARCH_IMPLEMENTS_FLUSH_KERNEL_VMAP_RANGE
- static inline void flush_kernel_vmap_range(void *vaddr, int size)
- {
- }
- static inline void invalidate_kernel_vmap_range(void *vaddr, int size)
- {
- }
- #endif
- /* when CONFIG_HIGHMEM is not set these will be plain clear/copy_page */
- #ifndef clear_user_highpage
- static inline void clear_user_highpage(struct page *page, unsigned long vaddr)
- {
- void *addr = kmap_local_page(page);
- clear_user_page(addr, vaddr, page);
- kunmap_local(addr);
- }
- #endif
- #ifndef __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE_MOVABLE
- /**
- * alloc_zeroed_user_highpage_movable - Allocate a zeroed HIGHMEM page for a VMA that the caller knows can move
- * @vma: The VMA the page is to be allocated for
- * @vaddr: The virtual address the page will be inserted into
- *
- * Returns: The allocated and zeroed HIGHMEM page
- *
- * This function will allocate a page for a VMA that the caller knows will
- * be able to migrate in the future using move_pages() or reclaimed
- *
- * An architecture may override this function by defining
- * __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE_MOVABLE and providing their own
- * implementation.
- */
- static inline struct page *
- alloc_zeroed_user_highpage_movable(struct vm_area_struct *vma,
- unsigned long vaddr)
- {
- struct page *page = alloc_page_vma(GFP_HIGHUSER_MOVABLE | __GFP_CMA, vma, vaddr);
- if (page)
- clear_user_highpage(page, vaddr);
- return page;
- }
- #endif
- static inline void clear_highpage(struct page *page)
- {
- void *kaddr = kmap_local_page(page);
- clear_page(kaddr);
- kunmap_local(kaddr);
- }
- static inline void clear_highpage_kasan_tagged(struct page *page)
- {
- u8 tag;
- tag = page_kasan_tag(page);
- page_kasan_tag_reset(page);
- clear_highpage(page);
- page_kasan_tag_set(page, tag);
- }
- #ifndef __HAVE_ARCH_TAG_CLEAR_HIGHPAGE
- static inline void tag_clear_highpage(struct page *page)
- {
- }
- #endif
- /*
- * If we pass in a base or tail page, we can zero up to PAGE_SIZE.
- * If we pass in a head page, we can zero up to the size of the compound page.
- */
- #ifdef CONFIG_HIGHMEM
- void zero_user_segments(struct page *page, unsigned start1, unsigned end1,
- unsigned start2, unsigned end2);
- #else
- static inline void zero_user_segments(struct page *page,
- unsigned start1, unsigned end1,
- unsigned start2, unsigned end2)
- {
- void *kaddr = kmap_local_page(page);
- unsigned int i;
- BUG_ON(end1 > page_size(page) || end2 > page_size(page));
- if (end1 > start1)
- memset(kaddr + start1, 0, end1 - start1);
- if (end2 > start2)
- memset(kaddr + start2, 0, end2 - start2);
- kunmap_local(kaddr);
- for (i = 0; i < compound_nr(page); i++)
- flush_dcache_page(page + i);
- }
- #endif
- static inline void zero_user_segment(struct page *page,
- unsigned start, unsigned end)
- {
- zero_user_segments(page, start, end, 0, 0);
- }
- static inline void zero_user(struct page *page,
- unsigned start, unsigned size)
- {
- zero_user_segments(page, start, start + size, 0, 0);
- }
- #ifndef __HAVE_ARCH_COPY_USER_HIGHPAGE
- static inline void copy_user_highpage(struct page *to, struct page *from,
- unsigned long vaddr, struct vm_area_struct *vma)
- {
- char *vfrom, *vto;
- vfrom = kmap_local_page(from);
- vto = kmap_local_page(to);
- copy_user_page(vto, vfrom, vaddr, to);
- kmsan_unpoison_memory(page_address(to), PAGE_SIZE);
- kunmap_local(vto);
- kunmap_local(vfrom);
- }
- #endif
- #ifdef copy_mc_to_kernel
- static inline int copy_mc_user_highpage(struct page *to, struct page *from,
- unsigned long vaddr, struct vm_area_struct *vma)
- {
- unsigned long ret;
- char *vfrom, *vto;
- vfrom = kmap_local_page(from);
- vto = kmap_local_page(to);
- ret = copy_mc_to_kernel(vto, vfrom, PAGE_SIZE);
- if (!ret)
- kmsan_unpoison_memory(page_address(to), PAGE_SIZE);
- kunmap_local(vto);
- kunmap_local(vfrom);
- return ret;
- }
- #else
- static inline int copy_mc_user_highpage(struct page *to, struct page *from,
- unsigned long vaddr, struct vm_area_struct *vma)
- {
- copy_user_highpage(to, from, vaddr, vma);
- return 0;
- }
- #endif
- #ifndef __HAVE_ARCH_COPY_HIGHPAGE
- static inline void copy_highpage(struct page *to, struct page *from)
- {
- char *vfrom, *vto;
- vfrom = kmap_local_page(from);
- vto = kmap_local_page(to);
- copy_page(vto, vfrom);
- kmsan_copy_page_meta(to, from);
- kunmap_local(vto);
- kunmap_local(vfrom);
- }
- #endif
- static inline void memcpy_page(struct page *dst_page, size_t dst_off,
- struct page *src_page, size_t src_off,
- size_t len)
- {
- char *dst = kmap_local_page(dst_page);
- char *src = kmap_local_page(src_page);
- VM_BUG_ON(dst_off + len > PAGE_SIZE || src_off + len > PAGE_SIZE);
- memcpy(dst + dst_off, src + src_off, len);
- kunmap_local(src);
- kunmap_local(dst);
- }
- static inline void memset_page(struct page *page, size_t offset, int val,
- size_t len)
- {
- char *addr = kmap_local_page(page);
- VM_BUG_ON(offset + len > PAGE_SIZE);
- memset(addr + offset, val, len);
- kunmap_local(addr);
- }
- static inline void memcpy_from_page(char *to, struct page *page,
- size_t offset, size_t len)
- {
- char *from = kmap_local_page(page);
- VM_BUG_ON(offset + len > PAGE_SIZE);
- memcpy(to, from + offset, len);
- kunmap_local(from);
- }
- static inline void memcpy_to_page(struct page *page, size_t offset,
- const char *from, size_t len)
- {
- char *to = kmap_local_page(page);
- VM_BUG_ON(offset + len > PAGE_SIZE);
- memcpy(to + offset, from, len);
- flush_dcache_page(page);
- kunmap_local(to);
- }
- static inline void memzero_page(struct page *page, size_t offset, size_t len)
- {
- char *addr = kmap_local_page(page);
- VM_BUG_ON(offset + len > PAGE_SIZE);
- memset(addr + offset, 0, len);
- flush_dcache_page(page);
- kunmap_local(addr);
- }
- /**
- * folio_zero_segments() - Zero two byte ranges in a folio.
- * @folio: The folio to write to.
- * @start1: The first byte to zero.
- * @xend1: One more than the last byte in the first range.
- * @start2: The first byte to zero in the second range.
- * @xend2: One more than the last byte in the second range.
- */
- static inline void folio_zero_segments(struct folio *folio,
- size_t start1, size_t xend1, size_t start2, size_t xend2)
- {
- zero_user_segments(&folio->page, start1, xend1, start2, xend2);
- }
- /**
- * folio_zero_segment() - Zero a byte range in a folio.
- * @folio: The folio to write to.
- * @start: The first byte to zero.
- * @xend: One more than the last byte to zero.
- */
- static inline void folio_zero_segment(struct folio *folio,
- size_t start, size_t xend)
- {
- zero_user_segments(&folio->page, start, xend, 0, 0);
- }
- /**
- * folio_zero_range() - Zero a byte range in a folio.
- * @folio: The folio to write to.
- * @start: The first byte to zero.
- * @length: The number of bytes to zero.
- */
- static inline void folio_zero_range(struct folio *folio,
- size_t start, size_t length)
- {
- zero_user_segments(&folio->page, start, start + length, 0, 0);
- }
- #endif /* _LINUX_HIGHMEM_H */
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