1 files changed, 23 insertions, 0 deletions

diff --git a/arch/unicore32/include/asm/io.h b/arch/unicore32/include/asm/io.h
index d6920301465a..cb1d8fd2b16b 100644
--- a/arch/unicore32/include/asm/io.h
+++ b/arch/unicore32/include/asm/io.h
@@ -48,5 +48,28 @@ extern void __uc32_iounmap(volatile void __iomem *addr);
 #define PIO_MASK                (unsigned int)(IO_SPACE_LIMIT)
 #define PIO_RESERVED            (PIO_OFFSET + PIO_MASK + 1)
 
+#ifdef CONFIG_STRICT_DEVMEM
+
+#include <linux/ioport.h>
+#include <linux/mm.h>
+
+/*
+ * devmem_is_allowed() checks to see if /dev/mem access to a certain
+ * address is valid. The argument is a physical page number.
+ * We mimic x86 here by disallowing access to system RAM as well as
+ * device-exclusive MMIO regions. This effectively disable read()/write()
+ * on /dev/mem.
+ */
+static inline int devmem_is_allowed(unsigned long pfn)
+{
+        if (iomem_is_exclusive(pfn << PAGE_SHIFT))
+                return 0;
+        if (!page_is_ram(pfn))
+                return 1;
+        return 0;
+}
+
+#endif /* CONFIG_STRICT_DEVMEM */
+
 #endif  /* __KERNEL__ */
 #endif  /* __UNICORE_IO_H__ */