sh: Preliminary support for SH-X2 MMU.

This adds some preliminary support for the SH-X2 MMU, used by
newer SH-4A parts (particularly SH7785).

This MMU implements a 'compat' mode with SH-X MMUs and an
'extended' mode for SH-X2 extended features. Extended features
include additional page sizes (8kB, 4MB, 64MB), as well as the
addition of page execute permissions.

The extended mode attributes are placed in a second data array,
which requires us to switch to 64-bit PTEs when in X2 mode.

With the addition of the exec perms, we also overhaul the mmap
prots somewhat, now that it's possible to handle them more
intelligently.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/include/asm-sh/elf.h b/include/asm-sh/elf.h
index fc050fd..43ca244 100644
--- a/include/asm-sh/elf.h
+++ b/include/asm-sh/elf.h
@@ -74,7 +74,7 @@
 #define ELF_ARCH	EM_SH
 
 #define USE_ELF_CORE_DUMP
-#define ELF_EXEC_PAGESIZE	4096
+#define ELF_EXEC_PAGESIZE	PAGE_SIZE
 
 /* This is the location that an ET_DYN program is loaded if exec'ed.  Typical
    use of this is to invoke "./ld.so someprog" to test out a new version of