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/ieee754dp.c b/arch/mips/math-emu/ieee754dp.c
index 9723a518e5ad..49c811a920b5 100644
--- a/arch/mips/math-emu/ieee754dp.c
+++ b/arch/mips/math-emu/ieee754dp.c
@@ -42,18 +42,16 @@ static inline int ieee754dp_issnan(union ieee754dp x)
 }
 
 
+/*
+ * Raise the Invalid Operation IEEE 754 exception
+ * and convert the signaling NaN supplied to a quiet NaN.
+ */
 union ieee754dp __cold ieee754dp_nanxcpt(union ieee754dp r)
 {
-	assert(ieee754dp_isnan(r));
-
-	if (!ieee754dp_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 ieee754dp_indef();
+	assert(ieee754dp_issnan(r));
 
-	return r;
+	ieee754_setcx(IEEE754_INVALID_OPERATION);
+	return ieee754dp_indef();
 }
 
 static u64 ieee754dp_get_rounding(int sn, u64 xm)