1 files changed, 94 insertions, 0 deletions

diff --git a/arch/arm/mm/flush.c b/arch/arm/mm/flush.c
new file mode 100644
index 000000000000..c6de48d89503
--- /dev/null
+++ b/arch/arm/mm/flush.c
@@ -0,0 +1,94 @@
+/*
+ *  linux/arch/arm/mm/flush.c
+ *
+ *  Copyright (C) 1995-2002 Russell King
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/module.h>
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+
+#include <asm/cacheflush.h>
+#include <asm/system.h>
+
+static void __flush_dcache_page(struct address_space *mapping, struct page *page)
+{
+        struct mm_struct *mm = current->active_mm;
+        struct vm_area_struct *mpnt;
+        struct prio_tree_iter iter;
+        pgoff_t pgoff;
+
+        /*
+         * Writeback any data associated with the kernel mapping of this
+         * page.  This ensures that data in the physical page is mutually
+         * coherent with the kernels mapping.
+         */
+        __cpuc_flush_dcache_page(page_address(page));
+
+        /*
+         * If there's no mapping pointer here, then this page isn't
+         * visible to userspace yet, so there are no cache lines
+         * associated with any other aliases.
+         */
+        if (!mapping)
+                return;
+
+        /*
+         * There are possible user space mappings of this page:
+         * - VIVT cache: we need to also write back and invalidate all user
+         *   data in the current VM view associated with this page.
+         * - aliasing VIPT: we only need to find one mapping of this page.
+         */
+        pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
+
+        flush_dcache_mmap_lock(mapping);
+        vma_prio_tree_foreach(mpnt, &iter, &mapping->i_mmap, pgoff, pgoff) {
+                unsigned long offset;
+
+                /*
+                 * If this VMA is not in our MM, we can ignore it.
+                 */
+                if (mpnt->vm_mm != mm)
+                        continue;
+                if (!(mpnt->vm_flags & VM_MAYSHARE))
+                        continue;
+                offset = (pgoff - mpnt->vm_pgoff) << PAGE_SHIFT;
+                flush_cache_page(mpnt, mpnt->vm_start + offset, page_to_pfn(page));
+                if (cache_is_vipt())
+                        break;
+        }
+        flush_dcache_mmap_unlock(mapping);
+}
+
+/*
+ * Ensure cache coherency between kernel mapping and userspace mapping
+ * of this page.
+ *
+ * We have three cases to consider:
+ *  - VIPT non-aliasing cache: fully coherent so nothing required.
+ *  - VIVT: fully aliasing, so we need to handle every alias in our
+ *          current VM view.
+ *  - VIPT aliasing: need to handle one alias in our current VM view.
+ *
+ * If we need to handle aliasing:
+ *  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 assume we have
+ *  aliasing mappings.
+ */
+void flush_dcache_page(struct page *page)
+{
+        struct address_space *mapping = page_mapping(page);
+
+        if (cache_is_vipt_nonaliasing())
+                return;
+
+        if (mapping && !mapping_mapped(mapping))
+                set_bit(PG_dcache_dirty, &page->flags);
+        else
+                __flush_dcache_page(mapping, page);
+}
+EXPORT_SYMBOL(flush_dcache_page);