math-emu: Add support for reporting exact invalid exception

Some architectures (like powerpc) provide status information on the exact
type of invalid exception.  This is pretty straight forward as we already
report invalid exceptions via FP_SET_EXCEPTION.

We add new flags (FP_EX_INVALID_*) the architecture code can define if it
wants the exact invalid exception reported.

We had to split out the INF/INF and 0/0 cases for divide to allow reporting
the two invalid forms properly.
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Acked-by: David S. Miller <davem@davemloft.net>

include/math-emu/op-common.h

@@ -73,7 +73,7 @@ do {									\
 	X##_c = FP_CLS_NAN;						\
 	/* Check for signaling NaN */					\
 	if (!(_FP_FRAC_HIGH_RAW_##fs(X) & _FP_QNANBIT_##fs))		\
-	  FP_SET_EXCEPTION(FP_EX_INVALID);				\
+	  FP_SET_EXCEPTION(FP_EX_INVALID | FP_EX_INVALID_SNAN);		\
       }									\
     break;								\
   }									\
@@ -324,7 +324,7 @@ do {									     \
 	_FP_FRAC_SET_##wc(R, _FP_NANFRAC_##fs);				     \
 	R##_s = _FP_NANSIGN_##fs;					     \
 	R##_c = FP_CLS_NAN;						     \
-	FP_SET_EXCEPTION(FP_EX_INVALID);				     \
+	FP_SET_EXCEPTION(FP_EX_INVALID | FP_EX_INVALID_ISI);		     \
 	break;								     \
       }									     \
     /* FALLTHRU */							     \
@@ -431,7 +431,7 @@ do {							\
     R##_s = _FP_NANSIGN_##fs;				\
     R##_c = FP_CLS_NAN;					\
     _FP_FRAC_SET_##wc(R, _FP_NANFRAC_##fs);		\
-    FP_SET_EXCEPTION(FP_EX_INVALID);			\
+    FP_SET_EXCEPTION(FP_EX_INVALID | FP_EX_INVALID_IMZ);\
     break;						\
 							\
   default:						\
@@ -490,11 +490,15 @@ do {							\
     break;						\
 							\
   case _FP_CLS_COMBINE(FP_CLS_INF,FP_CLS_INF):		\
+    R##_s = _FP_NANSIGN_##fs;				\
+    R##_c = FP_CLS_NAN;					\
+    _FP_FRAC_SET_##wc(R, _FP_NANFRAC_##fs);		\
+    FP_SET_EXCEPTION(FP_EX_INVALID | FP_EX_INVALID_IDI);\
   case _FP_CLS_COMBINE(FP_CLS_ZERO,FP_CLS_ZERO):	\
     R##_s = _FP_NANSIGN_##fs;				\
     R##_c = FP_CLS_NAN;					\
     _FP_FRAC_SET_##wc(R, _FP_NANFRAC_##fs);		\
-    FP_SET_EXCEPTION(FP_EX_INVALID);			\
+    FP_SET_EXCEPTION(FP_EX_INVALID | FP_EX_INVALID_ZDZ);\
     break;						\
 							\
   default:						\

include/math-emu/soft-fp.h

@@ -51,6 +51,25 @@
 #ifndef FP_EX_INVALID
 #define FP_EX_INVALID		0
 #endif
+#ifndef FP_EX_INVALID_SNAN
+#define FP_EX_INVALID_SNAN	0
+#endif
+/* inf - inf */
+#ifndef FP_EX_INVALID_ISI
+#define FP_EX_INVALID_ISI	0
+#endif
+/* inf / inf */
+#ifndef FP_EX_INVALID_IDI
+#define FP_EX_INVALID_IDI	0
+#endif
+/* 0 / 0 */
+#ifndef FP_EX_INVALID_ZDZ
+#define FP_EX_INVALID_ZDZ	0
+#endif
+/* inf * 0 */
+#ifndef FP_EX_INVALID_IMZ
+#define FP_EX_INVALID_IMZ	0
+#endif
 #ifndef FP_EX_OVERFLOW
 #define FP_EX_OVERFLOW		0
 #endif