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 <[email protected]>
Index: BUILD-2.6/Documentation/cachetlb.txt
===================================================================
--- BUILD-2.6.orig/Documentation/cachetlb.txt 2006-03-21 13:37:45.000000000 -0600
+++ BUILD-2.6/Documentation/cachetlb.txt 2006-03-21 13:37:54.000000000 -0600
@@ -371,6 +371,18 @@
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.
Index: BUILD-2.6/include/linux/highmem.h
===================================================================
--- BUILD-2.6.orig/include/linux/highmem.h 2006-03-21 13:37:19.000000000 -0600
+++ BUILD-2.6/include/linux/highmem.h 2006-03-21 13:37:54.000000000 -0600
@@ -13,6 +13,12 @@
}
#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>
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
