ARM: 5794/1: Flush the D-cache during copy_user_highpage()

The I and D caches for copy-on-write pages on processors with
write-allocate caches become incoherent causing problems on application
relying on CoW for text pages (dynamic linker relocating symbols in a
text page). This patch flushes the D-cache for such pages.

Cc: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/mm/copypage-v6.c b/arch/arm/mm/copypage-v6.c
index 4127a7bddfe5cef91f4a340cfe4225e6200330a6..841f355319bfee86725ef6348d07d96b9b4f446e 100644 (file)
--- a/arch/arm/mm/copypage-v6.c
+++ b/arch/arm/mm/copypage-v6.c
@@ -41,6 +41,14 @@ static void v6_copy_user_highpage_nonaliasing(struct page *to,
        kfrom = kmap_atomic(from, KM_USER0);
        kto = kmap_atomic(to, KM_USER1);
        copy_page(kto, kfrom);
+#ifdef CONFIG_HIGHMEM
+       /*
+        * kmap_atomic() doesn't set the page virtual address, and
+        * kunmap_atomic() takes care of cache flushing already.
+        */
+       if (page_address(to) != NULL)
+#endif
+               __cpuc_flush_dcache_page(kto);
        kunmap_atomic(kto, KM_USER1);
        kunmap_atomic(kfrom, KM_USER0);
 }