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Commit 03beb076 authored by James Bottomley's avatar James Bottomley Committed by Linus Torvalds
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[PATCH] Add API for flushing Anon pages 



Currently, get_user_pages() returns fully coherent pages to the kernel for
anything other than anonymous pages.  This is a problem for things like
fuse and the SCSI generic ioctl SG_IO which can potentially wish to do DMA
to anonymous pages passed in by users.

The fix is to add a new memory management API: flush_anon_page() which
is used in get_user_pages() to make anonymous pages coherent.

Signed-off-by: default avatarJames Bottomley <James.Bottomley@SteelEye.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 64a07bd8

Documentation/cachetlb.txt

+9 −0
Original line number Diff line number Diff line
@@ -362,6 +362,15 @@ maps this page at its virtual address. 
	likely that you will need to flush the instruction cache

	for copy_to_user_page().



  void flush_anon_page(struct page *page, unsigned long vmaddr)

  	When the kernel needs to access the contents of an anonymous

	page, it calls this function (currently only

	get_user_pages()).  Note: flush_dcache_page() deliberately

	doesn't work for an anonymous page.  The default

	implementation is a nop (and should remain so for all coherent

	architectures).  For incoherent architectures, it should flush

	the cache of the page at vmaddr in the current user process.



  void flush_icache_range(unsigned long start, unsigned long end)

  	When the kernel stores into addresses that it will execute

	out of (eg when loading modules), this function is called.

include/linux/highmem.h

+6 −0
Original line number Diff line number Diff line
@@ -7,6 +7,12 @@ 


#include <asm/cacheflush.h>



#ifndef ARCH_HAS_FLUSH_ANON_PAGE

static inline void flush_anon_page(struct page *page, unsigned long vmaddr)

{

}

#endif



#ifdef CONFIG_HIGHMEM



#include <asm/highmem.h>

mm/memory.c

+2 −0
Original line number Diff line number Diff line
@@ -1071,6 +1071,8 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 
			}

			if (pages) {

				pages[i] = page;



				flush_anon_page(page, start);

				flush_dcache_page(page);

			}

			if (vmas)