[ARM] Fix VFP NaN flag handling.

The special non-signalling NaN flag was escaping and setting some
FPSCR exception enable flags.  Ensure that this flag is masked out
before we update the FPSCR.

arch/arm/vfp/vfp.h

@@ -337,3 +337,8 @@ extern u32 vfp_get_sys(unsigned int reg);
 extern void vfp_put_sys(unsigned int reg, u32 val);
 
 u32 vfp_estimate_sqrt_significand(u32 exponent, u32 significand);
+
+/*
+ * A special flag to tell the normalisation code not to normalise.
+ */
+#define VFP_NAN_FLAG	0x100

arch/arm/vfp/vfpdouble.c

@@ -195,7 +195,7 @@ u32 vfp_double_normaliseround(int dd, struct vfp_double *vd, u32 fpscr, u32 exce
 			 dd, d, exceptions);
 		vfp_put_double(dd, d);
 	}
-	return exceptions;
+	return exceptions & ~VFP_NAN_FLAG;
 }
 
 /*
@@ -240,7 +240,7 @@ vfp_propagate_nan(struct vfp_double *vdd, struct vfp_double *vdn,
 	/*
 	 * If one was a signalling NAN, raise invalid operation.
 	 */
-	return tn == VFP_SNAN || tm == VFP_SNAN ? FPSCR_IOC : 0x100;
+	return tn == VFP_SNAN || tm == VFP_SNAN ? FPSCR_IOC : VFP_NAN_FLAG;
 }
 
 /*

arch/arm/vfp/vfpsingle.c

@@ -201,7 +201,7 @@ u32 vfp_single_normaliseround(int sd, struct vfp_single *vs, u32 fpscr, u32 exce
 		vfp_put_float(sd, d);
 	}
 
-	return exceptions;
+	return exceptions & ~VFP_NAN_FLAG;
 }
 
 /*
@@ -246,7 +246,7 @@ vfp_propagate_nan(struct vfp_single *vsd, struct vfp_single *vsn,
 	/*
 	 * If one was a signalling NAN, raise invalid operation.
 	 */
-	return tn == VFP_SNAN || tm == VFP_SNAN ? FPSCR_IOC : 0x100;
+	return tn == VFP_SNAN || tm == VFP_SNAN ? FPSCR_IOC : VFP_NAN_FLAG;
 }