[MIPS] ieee754[sd]p_neg workaround
It looks glibc's pow() assumes an unary '-' operation for any number
(including NaNs) always inverts its sign bit (though IEEE754 does not
specify the sign bit for NaNs). This patch make the kernel math-emu
emulates real MIPS neg.[ds] instruction.
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/math-emu/dp_simple.c b/arch/mips/math-emu/dp_simple.c
index 495c1ac..1c555e6 100644
--- a/arch/mips/math-emu/dp_simple.c
+++ b/arch/mips/math-emu/dp_simple.c
@@ -48,16 +48,22 @@
CLEARCX;
FLUSHXDP;
+ /*
+ * Invert the sign ALWAYS to prevent an endless recursion on
+ * pow() in libc.
+ */
+ /* quick fix up */
+ DPSIGN(x) ^= 1;
+
if (xc == IEEE754_CLASS_SNAN) {
+ ieee754dp y = ieee754dp_indef();
SETCX(IEEE754_INVALID_OPERATION);
- return ieee754dp_nanxcpt(ieee754dp_indef(), "neg");
+ DPSIGN(y) = DPSIGN(x);
+ return ieee754dp_nanxcpt(y, "neg");
}
if (ieee754dp_isnan(x)) /* but not infinity */
return ieee754dp_nanxcpt(x, "neg", x);
-
- /* quick fix up */
- DPSIGN(x) ^= 1;
return x;
}
diff --git a/arch/mips/math-emu/sp_simple.c b/arch/mips/math-emu/sp_simple.c
index c809830..770f0f4 100644
--- a/arch/mips/math-emu/sp_simple.c
+++ b/arch/mips/math-emu/sp_simple.c
@@ -48,16 +48,22 @@
CLEARCX;
FLUSHXSP;
+ /*
+ * Invert the sign ALWAYS to prevent an endless recursion on
+ * pow() in libc.
+ */
+ /* quick fix up */
+ SPSIGN(x) ^= 1;
+
if (xc == IEEE754_CLASS_SNAN) {
+ ieee754sp y = ieee754sp_indef();
SETCX(IEEE754_INVALID_OPERATION);
- return ieee754sp_nanxcpt(ieee754sp_indef(), "neg");
+ SPSIGN(y) = SPSIGN(x);
+ return ieee754sp_nanxcpt(y, "neg");
}
if (ieee754sp_isnan(x)) /* but not infinity */
return ieee754sp_nanxcpt(x, "neg", x);
-
- /* quick fix up */
- SPSIGN(x) ^= 1;
return x;
}
