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authorJames Bottomley <James.Bottomley@SteelEye.com>2006-03-26 01:36:57 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-03-26 08:56:53 -0800
commit03beb07664d768db97bf454ae5c9581cd4737bb4 (patch)
treeb906c4db3a70627a58363193f3f843e7e2132ca1
parent64a07bd82ed526d813b64b0957543eef55bdf9c0 (diff)
[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.txt9
-rw-r--r--include/linux/highmem.h6
-rw-r--r--mm/memory.c2
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)