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[PATCH] Add API for flushing Anon pages

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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: James Bottomley <James.Bottomley@SteelEye.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
James Bottomley 2006-03-26 01:36:57 -08:00 committed by Linus Torvalds
parent 64a07bd82e
commit 03beb07664
3 changed files with 17 additions and 0 deletions
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9
Documentation/cachetlb.txt
View File

@ -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.

6
include/linux/highmem.h
View File

@ -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>

2
mm/memory.c
View File

@ -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)