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-rw-r--r--include/linux/pfn.h10
1 files changed, 10 insertions, 0 deletions
diff --git a/include/linux/pfn.h b/include/linux/pfn.h
index 7646637221f3..1132953235c0 100644
--- a/include/linux/pfn.h
+++ b/include/linux/pfn.h
@@ -3,11 +3,21 @@
#ifndef __ASSEMBLY__
#include <linux/types.h>
+
+/*
+ * pfn_t: encapsulates a page-frame number that is optionally backed
+ * by memmap (struct page). Whether a pfn_t has a 'struct page'
+ * backing is indicated by flags in the high bits of the value.
+ */
+typedef struct {
+ u64 val;
+} pfn_t;
#endif
#define PFN_ALIGN(x) (((unsigned long)(x) + (PAGE_SIZE - 1)) & PAGE_MASK)
#define PFN_UP(x) (((x) + PAGE_SIZE-1) >> PAGE_SHIFT)
#define PFN_DOWN(x) ((x) >> PAGE_SHIFT)
#define PFN_PHYS(x) ((phys_addr_t)(x) << PAGE_SHIFT)
+#define PHYS_PFN(x) ((unsigned long)((x) >> PAGE_SHIFT))
#endif