arch: arm: error: fix ARMv6-M assembly for Z_ARCH_EXCEPT

As we are allowed to pass any integer value as as software
fatal exception reason, we need to fix the inline assembly
for ARMv6-M, to accept large immediate offsets. We do this
by changing the way we write the exception reason to R0.

Signed-off-by: Ioannis Glaropoulos <[email protected]>

Author: ioannisg

include/arch/arm/error.h

@@ -31,13 +31,14 @@ extern "C" {
  * schedule a new thread until they are unlocked which is not what we want.
  * Force them unlocked as well.
  */
-#define Z_ARCH_EXCEPT(reason_p) do { \
+#define Z_ARCH_EXCEPT(reason_p) \
+register u32_t r0 __asm__("r0") = reason_p; \
+do { \
 	__asm__ volatile ( \
 		"cpsie i\n\t" \
-		"movs r0, %[reason]\n\t" \
 		"svc %[id]\n\t" \
 		: \
-		: [reason] "i" (reason_p), [id] "i" (_SVC_CALL_RUNTIME_EXCEPT) \
+		: "r" (r0), [id] "i" (_SVC_CALL_RUNTIME_EXCEPT) \
 		: "memory"); \
 	CODE_UNREACHABLE; \
 } while (false)