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| author | James Bottomley <James.Bottomley@SteelEye.com> | 2006-03-26 01:36:57 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-03-26 08:56:53 -0800 |
| commit | 03beb07664d768db97bf454ae5c9581cd4737bb4 (patch) | |
| tree | b906c4db3a70627a58363193f3f843e7e2132ca1 | |
| parent | 64a07bd82ed526d813b64b0957543eef55bdf9c0 (diff) | |
| download | lwn-03beb07664d768db97bf454ae5c9581cd4737bb4.tar.gz lwn-03beb07664d768db97bf454ae5c9581cd4737bb4.zip | |
[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: 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>
| -rw-r--r-- | Documentation/cachetlb.txt | 9 | ||||
| -rw-r--r-- | include/linux/highmem.h | 6 | ||||
| -rw-r--r-- | mm/memory.c | 2 |
3 files changed, 17 insertions, 0 deletions
diff --git a/Documentation/cachetlb.txt b/Documentation/cachetlb.txt index 4ae418889b88..1f312a9893d9 100644 --- a/Documentation/cachetlb.txt +++ b/Documentation/cachetlb.txt @@ -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. diff --git a/include/linux/highmem.h b/include/linux/highmem.h index 6bece9280eb7..7bd2593dbef9 100644 --- a/include/linux/highmem.h +++ b/include/linux/highmem.h @@ -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> diff --git a/mm/memory.c b/mm/memory.c index e347e106ca3a..67686048f094 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -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) |