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Commit c5033d78 authored by Atsushi Nemoto's avatar Atsushi Nemoto Committed by Ralf Baechle
Browse files

[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: default avatarAtsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent d4264f18

arch/mips/math-emu/dp_simple.c

+10 −4
Original line number Diff line number Diff line
@@ -48,16 +48,22 @@ ieee754dp ieee754dp_neg(ieee754dp x) 
	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;

}

arch/mips/math-emu/sp_simple.c

+10 −4
Original line number Diff line number Diff line
@@ -48,16 +48,22 @@ ieee754sp ieee754sp_neg(ieee754sp x) 
	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;

}