arch/tile: support building big-endian kernel

The toolchain supports big-endian mode now, so add support for building
the kernel to run big-endian as well.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
diff --git a/arch/tile/lib/strlen_64.c b/arch/tile/lib/strlen_64.c
index 1c92d46..9583fc3 100644
--- a/arch/tile/lib/strlen_64.c
+++ b/arch/tile/lib/strlen_64.c
@@ -15,8 +15,7 @@
 #include <linux/types.h>
 #include <linux/string.h>
 #include <linux/module.h>
-
-#undef strlen
+#include "string-endian.h"
 
 size_t strlen(const char *s)
 {
@@ -24,15 +23,13 @@
 	const uintptr_t s_int = (uintptr_t) s;
 	const uint64_t *p = (const uint64_t *)(s_int & -8);
 
-	/* Read the first word, but force bytes before the string to be nonzero.
-	 * This expression works because we know shift counts are taken mod 64.
-	 */
-	uint64_t v = *p | ((1ULL << (s_int << 3)) - 1);
+	/* Read and MASK the first word. */
+	uint64_t v = *p | MASK(s_int);
 
 	uint64_t bits;
 	while ((bits = __insn_v1cmpeqi(v, 0)) == 0)
 		v = *++p;
 
-	return ((const char *)p) + (__insn_ctz(bits) >> 3) - s;
+	return ((const char *)p) + (CFZ(bits) >> 3) - s;
 }
 EXPORT_SYMBOL(strlen);