Merge pull request #229 from sandrine-bailleux/sb/tf-issue-273

Prevent optimisation of sysregs accessors calls

include/lib/aarch64/arch_helpers.h

@@ -44,20 +44,20 @@
 static inline uint64_t read_ ## _name(void)			\
 {								\
 	uint64_t v;						\
-	__asm__ ("mrs %0, " #_reg_name : "=r" (v));	\
+	__asm__ volatile ("mrs %0, " #_reg_name : "=r" (v));	\
 	return v;						\
 }
 
 #define _DEFINE_SYSREG_WRITE_FUNC(_name, _reg_name)			\
 static inline void write_ ## _name(uint64_t v)				\
 {									\
-	__asm__ ("msr " #_reg_name ", %0" : : "r" (v));	\
+	__asm__ volatile ("msr " #_reg_name ", %0" : : "r" (v));	\
 }
 
 #define _DEFINE_SYSREG_WRITE_CONST_FUNC(_name, _reg_name)		\
 static inline void write_ ## _name(const uint64_t v)			\
 {									\
-	__asm__ ("msr " #_reg_name ", %0" : : "i" (v));	\
+	__asm__ volatile ("msr " #_reg_name ", %0" : : "i" (v));	\
 }
 
 /* Define read function for system register */