SPARC: implement ARCH_EXCEPT()

Introduce a new software trap 15 which is generated by the
ARCH_EXCEPT() function macro.

The handler for this software trap calls z_sparc_fatal_error() and
finally z_fatal_error() with "reason" and ESF as arguments.

Signed-off-by: Martin Åberg <martin.aberg@gaisler.com>

include/arch/sparc/arch.h

@@ -34,6 +34,7 @@
  */
 #define SPARC_SW_TRAP_FLUSH_WINDOWS     0x03
 #define SPARC_SW_TRAP_SET_PIL           0x09
+#define SPARC_SW_TRAP_EXCEPT            0x0F
 
 #ifndef _ASMLANGUAGE
 #include <sys/util.h>
@@ -111,6 +112,19 @@ struct __esf {
 
 typedef struct __esf z_arch_esf_t;
 
+#define ARCH_EXCEPT(reason_p)						\
+do {									\
+	register uint32_t _g1 __asm__("g1") = reason_p;			\
+									\
+	__asm__ volatile (						\
+		"ta %[vector]\n\t"					\
+		:							\
+		: [vector] "i" (SPARC_SW_TRAP_EXCEPT), "r" (_g1)	\
+		: "memory"						\
+	);								\
+	CODE_UNREACHABLE;						\
+} while (false)
+
 #ifdef __cplusplus
 }
 #endif