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![Chintan Pandya](/assets/img/avatar_default.png)
__kmap_atomic_idx is per_cpu variable. Each CPU can use KM_TYPE_NR entries from FIXMAP i.e. from 0 to KM_TYPE_NR - 1. Allowing __kmap_atomic_idx to over- shoot to KM_TYPE_NR can mess up with next CPU's 0th entry which is a bug. Hence BUG_ON if __kmap_atomic_idx >= KM_TYPE_NR. Fix the off-by-on in this test. Signed-off-by: Chintan Pandya <cpandya@codeaurora.org> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
249 lines
5.8 KiB
C
249 lines
5.8 KiB
C
#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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#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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#include <asm/kmap_types.h>
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#ifdef CONFIG_HIGHMEM
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#include <asm/highmem.h>
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/* declarations for linux/mm/highmem.c */
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unsigned int nr_free_highpages(void);
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extern unsigned long totalhigh_pages;
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void kmap_flush_unused(void);
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struct page *kmap_to_page(void *addr);
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#else /* CONFIG_HIGHMEM */
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static inline unsigned int nr_free_highpages(void) { return 0; }
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static inline struct page *kmap_to_page(void *addr)
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{
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return virt_to_page(addr);
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}
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#define totalhigh_pages 0UL
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#ifndef ARCH_HAS_KMAP
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static inline void *kmap(struct page *page)
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{
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might_sleep();
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return page_address(page);
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}
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static inline void kunmap(struct page *page)
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{
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}
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static inline void *kmap_atomic(struct page *page)
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{
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pagefault_disable();
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return page_address(page);
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}
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#define kmap_atomic_prot(page, prot) kmap_atomic(page)
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static inline void __kunmap_atomic(void *addr)
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{
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pagefault_enable();
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}
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#define kmap_atomic_pfn(pfn) kmap_atomic(pfn_to_page(pfn))
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#define kmap_atomic_to_page(ptr) virt_to_page(ptr)
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#define kmap_flush_unused() do {} while(0)
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#endif
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#endif /* CONFIG_HIGHMEM */
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#if defined(CONFIG_HIGHMEM) || defined(CONFIG_X86_32)
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DECLARE_PER_CPU(int, __kmap_atomic_idx);
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static inline int kmap_atomic_idx_push(void)
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{
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int idx = __this_cpu_inc_return(__kmap_atomic_idx) - 1;
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#ifdef CONFIG_DEBUG_HIGHMEM
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WARN_ON_ONCE(in_irq() && !irqs_disabled());
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BUG_ON(idx >= KM_TYPE_NR);
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#endif
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return idx;
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}
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static inline int kmap_atomic_idx(void)
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{
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return __this_cpu_read(__kmap_atomic_idx) - 1;
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}
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static inline void kmap_atomic_idx_pop(void)
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{
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#ifdef CONFIG_DEBUG_HIGHMEM
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int idx = __this_cpu_dec_return(__kmap_atomic_idx);
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BUG_ON(idx < 0);
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#else
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__this_cpu_dec(__kmap_atomic_idx);
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#endif
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}
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#endif
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/*
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* Prevent people trying to call kunmap_atomic() as if it were kunmap()
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* kunmap_atomic() should get the return value of kmap_atomic, not the page.
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*/
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#define kunmap_atomic(addr) \
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do { \
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BUILD_BUG_ON(__same_type((addr), struct page *)); \
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__kunmap_atomic(addr); \
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} while (0)
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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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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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BUG_ON(end1 > PAGE_SIZE || end2 > PAGE_SIZE);
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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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flush_dcache_page(page);
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}
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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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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 /* _LINUX_HIGHMEM_H */
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