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