MIPS: math-emu: Reinstate sNaN quieting handlers

Revert the changes made by commit fdffbafb [Lots of FPU bug fixes from
Kjeld Borch Egevang.] to `ieee754sp_nanxcpt' and `ieee754dp_nanxcpt'
sNaN quieting handlers and their callers so that sNaN processing is done
within the handlers againg.  Pass the sNaN causing an IEEE 754 invalid
operation exception down to the relevant handler.  Pass the sNaN in `fs'
where two sNaNs are supplied to a binary operation.

Set the Invalid Operation FCSR exception bits in the quieting handlers
rather than at their call sites throughout.  Make the handlers exclusive
for sNaN processing.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9688/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 7 insertions, 9 deletions

diff --git a/arch/mips/math-emu/ieee754sp.c b/arch/mips/math-emu/ieee754sp.c
index 7bde3c204d02..21899ce05171 100644
--- a/arch/mips/math-emu/ieee754sp.c
+++ b/arch/mips/math-emu/ieee754sp.c
@@ -42,18 +42,16 @@ static inline int ieee754sp_issnan(union ieee754sp x)
 }
 
 
+/*
+ * Raise the Invalid Operation IEEE 754 exception
+ * and convert the signaling NaN supplied to a quiet NaN.
+ */
 union ieee754sp __cold ieee754sp_nanxcpt(union ieee754sp r)
 {
-	assert(ieee754sp_isnan(r));
-
-	if (!ieee754sp_issnan(r))	/* QNAN does not cause invalid op !! */
-		return r;
-
-	/* If not enabled convert to a quiet NaN.  */
-	if (!ieee754_setandtestcx(IEEE754_INVALID_OPERATION))
-		return ieee754sp_indef();
+	assert(ieee754sp_issnan(r));
 
-	return r;
+	ieee754_setcx(IEEE754_INVALID_OPERATION);
+	return ieee754sp_indef();
 }
 
 static unsigned ieee754sp_get_rounding(int sn, unsigned xm)