MIPS: math-emu: Fix m{add,sub}.s shifts

The code in _sp_maddf (formerly ieee754sp_madd) appears to have been
copied verbatim from ieee754sp_add, and although it's adding the
unpacked "r" & "z" floats it kept using macros that operate on "x" &
"y". This led to the addition being carried out incorrectly on some
mismash of the product, accumulator & multiplicand fields. Typically
this would lead to the assertions "ze == re" & "ze <= SP_EMAX" failing
since ze & re hadn't been operated upon.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Fixes: e24c3bec3e8e ("MIPS: math-emu: Add support for the MIPS R6 MADDF FPU instruction")
Cc: Adam Buchbinder <adam.buchbinder@gmail.com>
Cc: Maciej W. Rozycki <macro@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/13159/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 7 insertions, 9 deletions

diff --git a/arch/mips/math-emu/ieee754sp.h b/arch/mips/math-emu/ieee754sp.h
index b24fdff..8476067 100644
--- a/arch/mips/math-emu/ieee754sp.h
+++ b/arch/mips/math-emu/ieee754sp.h
@@ -46,19 +46,17 @@ static inline int ieee754sp_finite(union ieee754sp x)
 }
 
 /* 3bit extended single precision sticky right shift */
-#define SPXSRSXn(rs)							\
-	(xe += rs,							\
-	 xm = (rs > (SP_FBITS+3))?1:((xm) >> (rs)) | ((xm) << (32-(rs)) != 0))
+#define XSPSRS(v, rs)						\
+	((rs > (SP_FBITS+3))?1:((v) >> (rs)) | ((v) << (32-(rs)) != 0))
 
-#define SPXSRSX1() \
-	(xe++, (xm = (xm >> 1) | (xm & 1)))
+#define XSPSRS1(m) \
+	((m >> 1) | (m & 1))
 
-#define SPXSRSYn(rs)								\
-	(ye+=rs,								\
-	 ym = (rs > (SP_FBITS+3))?1:((ym) >> (rs)) | ((ym) << (32-(rs)) != 0))
+#define SPXSRSX1() \
+	(xe++, (xm = XSPSRS1(xm)))
 
 #define SPXSRSY1() \
-	(ye++, (ym = (ym >> 1) | (ym & 1)))
+	(ye++, (ym = XSPSRS1(ym)))
 
 /* convert denormal to normalized with extended exponent */
 #define SPDNORMx(m,e) \