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![Ira Weiny](/assets/img/avatar_default.png)
Patch series "btrfs: Convert kmap/memset/kunmap to memzero_user()". Lifting memzero_user(), convert it to kmap_local_page() and then use it in btrfs. This patch (of 3): memzero_page() can replace the kmap/memset/kunmap pattern in other places in the code. While zero_user() has the same interface it is not the same call and its use should be limited and some of those calls may be better converted from zero_user() to memzero_page().[1] But that is not addressed in this series. Lift memzero_page() to highmem. [1] https://lore.kernel.org/lkml/CAHk-=wijdojzo56FzYqE5TOYw2Vws7ik3LEMGj9SPQaJJ+Z73Q@mail.gmail.com/ Link: https://lkml.kernel.org/r/20210309212137.2610186-1-ira.weiny@intel.com Link: https://lkml.kernel.org/r/20210309212137.2610186-2-ira.weiny@intel.com Signed-off-by: Ira Weiny <ira.weiny@intel.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: David Sterba <dsterba@suse.com> Cc: Chris Mason <clm@fb.com> Cc: Josef Bacik <josef@toxicpanda.com> Cc: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
342 lines
9.5 KiB
C
342 lines
9.5 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/mm.h>
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#include <linux/uaccess.h>
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#include <linux/hardirq.h>
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#include <asm/cacheflush.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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* @addr: Virtual address to be unmapped
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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.
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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 it is significantly faster than kmap() for the higmem case it
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* comes with restrictions about the pointer validity. Only use when really
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* necessary.
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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_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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* Effectively a wrapper around kmap_local_page() which disables pagefaults
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* and preemption.
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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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static inline void *kmap_atomic(struct page *page);
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/**
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* kunmap_atomic - Unmap the virtual address mapped by kmap_atomic()
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* @addr: Virtual address to be unmapped
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*
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* Counterpart to kmap_atomic().
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*
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* Effectively a wrapper around kunmap_local() which additionally undoes
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* the side effects of kmap_atomic(), i.e. reenabling pagefaults and
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* preemption.
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*/
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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_HAS_FLUSH_KERNEL_DCACHE_PAGE
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static inline void flush_kernel_dcache_page(struct page *page)
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{
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}
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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_atomic(page);
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clear_user_page(addr, vaddr, page);
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kunmap_atomic(addr);
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}
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#endif
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#ifndef __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE
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/**
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* __alloc_zeroed_user_highpage - Allocate a zeroed HIGHMEM page for a VMA with caller-specified movable GFP flags
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* @movableflags: The GFP flags related to the pages future ability to move like __GFP_MOVABLE
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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 for a VMA but the caller is expected
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* to specify via movableflags whether the page will be movable in the
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* future or not
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*
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* An architecture may override this function by defining
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* __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE and providing their own
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* implementation.
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*/
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static inline struct page *
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__alloc_zeroed_user_highpage(gfp_t movableflags,
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struct vm_area_struct *vma,
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unsigned long vaddr)
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{
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struct page *page = alloc_page_vma(GFP_HIGHUSER | movableflags,
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vma, vaddr);
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if (page)
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clear_user_highpage(page, vaddr);
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return page;
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}
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#endif
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/**
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* alloc_zeroed_user_highpage_movable - Allocate a zeroed HIGHMEM page for a VMA that the caller knows can move
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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 for a VMA that the caller knows will
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* be able to migrate in the future using move_pages() or reclaimed
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*/
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static inline struct page *
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alloc_zeroed_user_highpage_movable(struct vm_area_struct *vma,
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unsigned long vaddr)
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{
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return __alloc_zeroed_user_highpage(__GFP_MOVABLE, vma, vaddr);
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}
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static inline void clear_highpage(struct page *page)
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{
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void *kaddr = kmap_atomic(page);
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clear_page(kaddr);
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kunmap_atomic(kaddr);
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}
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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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#if defined(CONFIG_HIGHMEM) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
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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 /* !HIGHMEM || !TRANSPARENT_HUGEPAGE */
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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_atomic(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_atomic(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 /* !HIGHMEM || !TRANSPARENT_HUGEPAGE */
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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_atomic(from);
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vto = kmap_atomic(to);
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copy_user_page(vto, vfrom, vaddr, to);
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kunmap_atomic(vto);
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kunmap_atomic(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_atomic(from);
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vto = kmap_atomic(to);
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copy_page(vto, vfrom);
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kunmap_atomic(vto);
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kunmap_atomic(vfrom);
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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 memmove_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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memmove(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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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_atomic(page);
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memset(addr + offset, 0, len);
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kunmap_atomic(addr);
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}
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#endif /* _LINUX_HIGHMEM_H */
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