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authorJames Bottomley <James.Bottomley@SteelEye.com>2006-03-26 01:36:59 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-03-26 08:56:53 -0800
commit5a3a5a98b6422d05c39eaa32c8b3f83840c7b768 (patch)
treee96a8f5543c94c57eb2b761fa94df9f7a9412e52
parent03beb07664d768db97bf454ae5c9581cd4737bb4 (diff)
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[PATCH] Add flush_kernel_dcache_page() API
We have a problem in a lot of emulated storage in that it takes a page from get_user_pages() and does something like kmap_atomic(page) modify page kunmap_atomic(page) However, nothing has flushed the kernel cache view of the page before the kunmap. We need a lightweight API to do this, so this new API would specifically be for flushing the kernel cache view of a user page which the kernel has modified. The driver would need to add flush_kernel_dcache_page(page) before the final kunmap. 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.txt12
-rw-r--r--include/linux/highmem.h6
2 files changed, 18 insertions, 0 deletions
diff --git a/Documentation/cachetlb.txt b/Documentation/cachetlb.txt
index 1f312a9..53245c4 100644
--- a/Documentation/cachetlb.txt
+++ b/Documentation/cachetlb.txt
@@ -371,6 +371,18 @@ maps this page at its virtual address.
architectures). For incoherent architectures, it should flush
the cache of the page at vmaddr in the current user process.
+ void flush_kernel_dcache_page(struct page *page)
+ When the kernel needs to modify a user page is has obtained
+ with kmap, it calls this function after all modifications are
+ complete (but before kunmapping it) to bring the underlying
+ page up to date. It is assumed here that the user has no
+ incoherent cached copies (i.e. the original page was obtained
+ from a mechanism like get_user_pages()). The default
+ implementation is a nop and should remain so on all coherent
+ architectures. On incoherent architectures, this should flush
+ the kernel cache for page (using page_address(page)).
+
+
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 7bd2593..892c4ea 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -13,6 +13,12 @@ static inline void flush_anon_page(struct page *page, unsigned long vmaddr)
}
#endif
+#ifndef ARCH_HAS_FLUSH_KERNEL_DCACHE_PAGE
+static inline void flush_kernel_dcache_page(struct page *page)
+{
+}
+#endif
+
#ifdef CONFIG_HIGHMEM
#include <asm/highmem.h>
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