From 1bc39742aab09248169ef9d3727c9def3528b3f3 Mon Sep 17 00:00:00 2001
From: Simon Baatz <gmbnomis@gmail.com>
Date: Mon, 10 Jun 2013 21:10:12 +0100
Subject: ARM: 7755/1: handle user space mapped pages in
flush_kernel_dcache_page
Commit f8b63c1 made flush_kernel_dcache_page a no-op assuming that
the pages it needs to handle are kernel mapped only. However, for
example when doing direct I/O, pages with user space mappings may
occur.
Thus, continue to do lazy flushing if there are no user space
mappings. Otherwise, flush the kernel cache lines directly.
Signed-off-by: Simon Baatz <gmbnomis@gmail.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: <stable@vger.kernel.org> # 3.2+
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
arch/arm/mm/flush.c | 33 +++++++++++++++++++++++++++++++++
1 file changed, 33 insertions(+)
(limited to 'arch/arm/mm/flush.c')
diff --git a/arch/arm/mm/flush.c b/arch/arm/mm/flush.c
index 0d473cce501..32aa5861119 100644
--- a/arch/arm/mm/flush.c
+++ b/arch/arm/mm/flush.c
@@ -300,6 +300,39 @@ void flush_dcache_page(struct page *page)
}
EXPORT_SYMBOL(flush_dcache_page);
+/*
+ * Ensure cache coherency for the kernel mapping of this page. We can
+ * assume that the page is pinned via kmap.
+ *
+ * If the page only exists in the page cache and there are no user
+ * space mappings, this is a no-op since the page was already marked
+ * dirty at creation. Otherwise, we need to flush the dirty kernel
+ * cache lines directly.
+ */
+void flush_kernel_dcache_page(struct page *page)
+{
+ if (cache_is_vivt() || cache_is_vipt_aliasing()) {
+ struct address_space *mapping;
+
+ mapping = page_mapping(page);
+
+ if (!mapping || mapping_mapped(mapping)) {
+ void *addr;
+
+ addr = page_address(page);
+ /*
+ * kmap_atomic() doesn't set the page virtual
+ * address for highmem pages, and
+ * kunmap_atomic() takes care of cache
+ * flushing already.
+ */
+ if (!IS_ENABLED(CONFIG_HIGHMEM) || addr)
+ __cpuc_flush_dcache_area(addr, PAGE_SIZE);
+ }
+ }
+}
+EXPORT_SYMBOL(flush_kernel_dcache_page);
+
/*
* Flush an anonymous page so that users of get_user_pages()
* can safely access the data. The expected sequence is:
--
cgit v1.2.3-70-g09d2