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[ARM] copypage: provide our own copy_user_highpage()

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We used to override the copy_user_page() function.  However, this
is not only inefficient, it also causes additional complexity for
highmem support, since we convert from a struct page to a kernel
direct mapped address and back to a struct page again.

Moreover, with highmem support, we end up pointlessly setting up
kmap entries for pages which we're going to remap.  So, push the
kmapping down into the copypage implementation files where it's
required.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Russell King
2008-10-31 15:08:35 +00:00
committed by Russell King
parent d73e60b714
commit 063b0a4207
10 changed files with 161 additions and 83 deletions
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23
arch/arm/include/asm/page.h
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@@ -108,30 +108,35 @@
#error Unknown user operations model
#endif
struct page;
struct cpu_user_fns {
void (*cpu_clear_user_page)(void *p, unsigned long user);
void (*cpu_copy_user_page)(void *to, const void *from,
unsigned long user);
void (*cpu_copy_user_highpage)(struct page *to, struct page *from,
unsigned long vaddr);
};
#ifdef MULTI_USER
extern struct cpu_user_fns cpu_user;
#define __cpu_clear_user_page cpu_user.cpu_clear_user_page
#define __cpu_copy_user_page cpu_user.cpu_copy_user_page
#define __cpu_clear_user_page cpu_user.cpu_clear_user_page
#define __cpu_copy_user_highpage cpu_user.cpu_copy_user_highpage
#else
#define __cpu_clear_user_page __glue(_USER,_clear_user_page)
#define __cpu_copy_user_page __glue(_USER,_copy_user_page)
#define __cpu_clear_user_page __glue(_USER,_clear_user_page)
#define __cpu_copy_user_highpage __glue(_USER,_copy_user_highpage)
extern void __cpu_clear_user_page(void *p, unsigned long user);
extern void __cpu_copy_user_page(void *to, const void *from,
unsigned long user);
extern void __cpu_copy_user_highpage(struct page *to, struct page *from,
unsigned long vaddr);
#endif
#define clear_user_page(addr,vaddr,pg) __cpu_clear_user_page(addr, vaddr)
#define copy_user_page(to,from,vaddr,pg) __cpu_copy_user_page(to, from, vaddr)
#define __HAVE_ARCH_COPY_USER_HIGHPAGE
#define copy_user_highpage(to,from,vaddr,vma) \
__cpu_copy_user_highpage(to, from, vaddr)
#define clear_page(page) memzero((void *)(page), PAGE_SIZE)
extern void copy_page(void *to, const void *from);