ARM: make cr_alignment read-only #ifndef CONFIG_CPU_CP15

This makes cr_alignment a constant 0 to break code that tries to modify
the value as it's likely that it's built on wrong assumption when
CONFIG_CPU_CP15 isn't defined. For code that is only reading the value 0
is more or less a fine value to report.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Message-Id: 1358413196-5609-2-git-send-email-u.kleine-koenig@pengutronix.de (v8)

1 files changed, 15 insertions, 1 deletions

diff --git a/arch/arm/include/asm/cp15.h b/arch/arm/include/asm/cp15.h
index 5ef4d8015a60..1f3262e99d81 100644
--- a/arch/arm/include/asm/cp15.h
+++ b/arch/arm/include/asm/cp15.h
@@ -42,6 +42,8 @@
 #define vectors_high()  (0)
 #endif
 
+#ifdef CONFIG_CPU_CP15
+
 extern unsigned long cr_no_alignment;   /* defined in entry-armv.S */
 extern unsigned long cr_alignment;      /* defined in entry-armv.S */
 
@@ -82,6 +84,18 @@ static inline void set_copro_access(unsigned int val)
         isb();
 }
 
-#endif
+#else /* ifdef CONFIG_CPU_CP15 */
+
+/*
+ * cr_alignment and cr_no_alignment are tightly coupled to cp15 (at least in the
+ * minds of the developers). Yielding 0 for machines without a cp15 (and making
+ * it read-only) is fine for most cases and saves quite some #ifdeffery.
+ */
+#define cr_no_alignment UL(0)
+#define cr_alignment    UL(0)
+
+#endif /* ifdef CONFIG_CPU_CP15 / else */
+
+#endif /* ifndef __ASSEMBLY__ */
 
 #endif