@@ -307,6 +307,10 @@ 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 *);
+ /* highmem pages are always flushed upon kunmap already */
+ if (!PageHighMem(page))
+ __flush_kernel_dcache_page(page);
}
#define flush_dcache_mmap_lock(mapping) \
@@ -192,6 +192,45 @@ void __flush_dcache_page(struct address_space *mapping, struct page *page)
page->index << PAGE_CACHE_SHIFT);
}
+/*
+ * Ensure cache coherency for the kernel mapping of this page.
+ *
+ * If the page only exists in the page cache and there are no user
+ * space mappings, we can be lazy and remember that we may have dirty
+ * kernel cache lines for later. Otherwise, we need to flush the
+ * dirty kernel cache lines directly.
+ *
+ * Note that we disable the lazy flush for SMP configurations where
+ * the cache maintenance operations are not automatically broadcasted.
+ *
+ * We can assume that the page is no high mem page, see
+ * flush_kernel_dcache_page.
+ */
+void __flush_kernel_dcache_page(struct page *page)
+{
+ struct address_space *mapping;
+
+ /*
+ * The zero page is never written to, so never has any dirty
+ * cache lines, and therefore never needs to be flushed.
+ */
+ if (page == ZERO_PAGE(0))
+ return;
+
+ mapping = page_mapping(page);
+
+ if (!cache_ops_need_broadcast() &&
+ mapping && !mapping_mapped(mapping))
+ clear_bit(PG_dcache_clean, &page->flags);
+ else {
+ __cpuc_flush_dcache_area(page_address(page), PAGE_SIZE);
+ if (mapping && !cache_is_vivt())
+ __flush_icache_all();
+ set_bit(PG_dcache_clean, &page->flags);
+ }
+}
+EXPORT_SYMBOL(__flush_kernel_dcache_page);
+
static void __flush_dcache_aliases(struct address_space *mapping, struct page *page)
{
struct mm_struct *mm = current->active_mm;
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, do lazy flushing like in flush_dcache_page() if there are no user space mappings. Otherwise, flush the kernel cache lines directly. Signed-off-by: Simon Baatz <gmbnomis@gmail.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Russell King <linux@arm.linux.org.uk> --- Changes in v2: - flush_kernel_dcache_page() follows flush_dcache_page() now, except that it does not flush the user mappings arch/arm/include/asm/cacheflush.h | 4 ++++ arch/arm/mm/flush.c | 39 +++++++++++++++++++++++++++++++++++++ 2 files changed, 43 insertions(+)