[PATCH] Fix x87 FPU exception status check

From Dave Richards (drichards@mahinetworks.com)

  "While diagnosing an MMX/FPU problem I found a minor problem in the
   code which diagnoses and generates signals for FPU exceptions.  On
   x86 Stack Fault Exception are a subclass of Invalid Operation.  Thus,
   the FPU status register will have both the SF and IF bits set when a
   stack fault occurs.  The code which turns FPU exceptions into signals
   was assuming IF would be clear".

arch/i386/kernel/traps.c

@@ -629,9 +629,10 @@ void math_error(void *eip)
 		default:
 			break;
 		case 0x001: /* Invalid Op */
-		case 0x040: /* Stack Fault */
-		case 0x240: /* Stack Fault | Direction */
+		case 0x041: /* Stack Fault */
+		case 0x241: /* Stack Fault | Direction */
 			info.si_code = FPE_FLTINV;
+			/* Should we clear the SF or let user space do it ???? */
 			break;
 		case 0x002: /* Denormalize */
 		case 0x010: /* Underflow */