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@xxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # 3.0
---
This is the backport of commits 1bc39742aab09248169ef9d3727c9def3528b3f3
(ARM: 7755/1) and 63384fd0b1509acf522a8a8fcede09087eedb7df (ARM: 7772/1)
for the 3.0 stable kernel. The changes should only be syntactical;
IS_ENABLED is not available in this kernel and thus, #ifdef is used.
- Simon
arch/arm/include/asm/cacheflush.h | 4 +---
arch/arm/mm/flush.c | 34 ++++++++++++++++++++++++++++++++++
arch/arm/mm/nommu.c | 6 ++++++
3 files changed, 41 insertions(+), 3 deletions(-)
diff --git a/arch/arm/include/asm/cacheflush.h b/arch/arm/include/asm/cacheflush.h
index 42dec04..0a5e8a5 100644
--- a/arch/arm/include/asm/cacheflush.h
+++ b/arch/arm/include/asm/cacheflush.h
@@ -305,9 +305,7 @@ static inline void flush_anon_page(struct vm_area_struct *vma,
}
#define ARCH_HAS_FLUSH_KERNEL_DCACHE_PAGE
-static inline void flush_kernel_dcache_page(struct page *page)
-{
-}
+extern void flush_kernel_dcache_page(struct page *);
#define flush_dcache_mmap_lock(mapping) \
spin_lock_irq(&(mapping)->tree_lock)
diff --git a/arch/arm/mm/flush.c b/arch/arm/mm/flush.c
index 8fda9f7..32f6372 100644
--- a/arch/arm/mm/flush.c
+++ b/arch/arm/mm/flush.c
@@ -304,6 +304,40 @@ 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);
+#ifdef CONFIG_HIGHMEM
+ /*
+ * kmap_atomic() doesn't set the page virtual
+ * address, and kunmap_atomic() takes care of
+ * cache flushing already.
+ */
+ if (addr)
+#endif
+ __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:
*
diff --git a/arch/arm/mm/nommu.c b/arch/arm/mm/nommu.c
index 941a98c..a5018fb 100644
--- a/arch/arm/mm/nommu.c
+++ b/arch/arm/mm/nommu.c
@@ -53,6 +53,12 @@ void flush_dcache_page(struct page *page)
}
EXPORT_SYMBOL(flush_dcache_page);
+void flush_kernel_dcache_page(struct page *page)
+{
+ __cpuc_flush_dcache_area(page_address(page), PAGE_SIZE);
+}
+EXPORT_SYMBOL(flush_kernel_dcache_page);
+
void copy_to_user_page(struct vm_area_struct *vma, struct page *page,
unsigned long uaddr, void *dst, const void *src,
unsigned long len)
--
1.7.9.5
--
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