a6ca1b99ed
Give non-highmem architectures access to the kmap API for the purposes of
overriding (this is what the attached patch does).
The proposal is that we should now require all architectures with coherence
issues to manage data coherence via the kmap/kunmap API. Thus driver
writers never have to write code like
kmap(page)
modify data in page
flush_kernel_dcache_page(page)
kunmap(page)
instead, kmap/kunmap will manage the coherence and driver (and filesystem)
writers don't need to worry about how to flush between kmap and kunmap.
For most architectures, the page only needs to be flushed if it was
actually written to *and* there are user mappings of it, so the best
implementation looks to be: clear the page dirty pte bit in the kernel page
tables on kmap and on kunmap, check page->mappings for user maps, and then
the dirty bit, and only flush if it both has user mappings and is dirty.
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
119 lines
2.8 KiB
C
119 lines
2.8 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/mm.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 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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#endif
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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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#else /* CONFIG_HIGHMEM */
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static inline unsigned int nr_free_highpages(void) { return 0; }
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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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#define kunmap(page) do { (void) (page); } while (0)
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#define kmap_atomic(page, idx) page_address(page)
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#define kunmap_atomic(addr, idx) do { } while (0)
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#define kmap_atomic_pfn(pfn, idx) page_address(pfn_to_page(pfn))
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#define kmap_atomic_to_page(ptr) virt_to_page(ptr)
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#endif
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#endif /* CONFIG_HIGHMEM */
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/* when CONFIG_HIGHMEM is not set these will be plain clear/copy_page */
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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, KM_USER0);
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clear_user_page(addr, vaddr, page);
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kunmap_atomic(addr, KM_USER0);
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/* Make sure this page is cleared on other CPU's too before using it */
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smp_wmb();
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}
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#ifndef __HAVE_ARCH_ALLOC_ZEROED_USER_HIGHPAGE
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static inline struct page *
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alloc_zeroed_user_highpage(struct vm_area_struct *vma, unsigned long vaddr)
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{
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struct page *page = alloc_page_vma(GFP_HIGHUSER, 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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static inline void clear_highpage(struct page *page)
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{
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void *kaddr = kmap_atomic(page, KM_USER0);
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clear_page(kaddr);
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kunmap_atomic(kaddr, KM_USER0);
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}
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/*
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* Same but also flushes aliased cache contents to RAM.
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*/
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static inline void memclear_highpage_flush(struct page *page, unsigned int offset, unsigned int size)
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{
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void *kaddr;
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BUG_ON(offset + size > PAGE_SIZE);
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kaddr = kmap_atomic(page, KM_USER0);
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memset((char *)kaddr + offset, 0, size);
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flush_dcache_page(page);
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kunmap_atomic(kaddr, KM_USER0);
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}
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static inline void copy_user_highpage(struct page *to, struct page *from, unsigned long vaddr)
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{
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char *vfrom, *vto;
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vfrom = kmap_atomic(from, KM_USER0);
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vto = kmap_atomic(to, KM_USER1);
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copy_user_page(vto, vfrom, vaddr, to);
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kunmap_atomic(vfrom, KM_USER0);
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kunmap_atomic(vto, KM_USER1);
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/* Make sure this page is cleared on other CPU's too before using it */
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smp_wmb();
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}
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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, KM_USER0);
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vto = kmap_atomic(to, KM_USER1);
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copy_page(vto, vfrom);
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kunmap_atomic(vfrom, KM_USER0);
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kunmap_atomic(vto, KM_USER1);
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}
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#endif /* _LINUX_HIGHMEM_H */
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