path: root/Documentation/cachetlb.txt
diff options
authorJames Bottomley <>2006-03-26 01:36:59 -0800
committerLinus Torvalds <>2006-03-26 08:56:53 -0800
commit5a3a5a98b6422d05c39eaa32c8b3f83840c7b768 (patch)
treee96a8f5543c94c57eb2b761fa94df9f7a9412e52 /Documentation/cachetlb.txt
parent03beb07664d768db97bf454ae5c9581cd4737bb4 (diff)
[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 <> Cc: Russell King <> Cc: "David S. Miller" <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'Documentation/cachetlb.txt')
1 files changed, 12 insertions, 0 deletions
diff --git a/Documentation/cachetlb.txt b/Documentation/cachetlb.txt
index 1f312a9893d9..53245c429f7d 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.