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Patch "MIPS: math-emu: <MAX|MIN>.<D|S>: Fix cases of both inputs negative" has been added to the 4.13-stable tree

PATCH [email protected] 1 participant 1 message Sep 21, 2017

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This is a note to let you know that I've just added the patch titled

MIPS: math-emu: <MAX|MIN>.<D|S>: Fix cases of both inputs negative

to the 4.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
mips-math-emu-max-min-.-d-s-fix-cases-of-both-inputs-negative.patch
and it can be found in the queue-4.13 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From aabf5cf02e22ebc4e541adf835910f388b6c3e65 Mon Sep 17 00:00:00 2001

From: Aleksandar Markovic <[email protected]>
Date: Thu, 27 Jul 2017 18:08:50 +0200
Subject: MIPS: math-emu: <MAX|MIN>.<D|S>: Fix cases of both inputs negative

From: Aleksandar Markovic <[email protected]>

commit aabf5cf02e22ebc4e541adf835910f388b6c3e65 upstream.

Fix the value returned by <MAX|MIN>.<D|S>, if both inputs are negative normal fp numbers. The previous logic did not take into account that if both inputs have the same sign, there should be separate treatment of the cases when both inputs are negative and when both inputs are positive.

A relevant example:

MAX.S fd,fs,ft:
If fs contains -5.0, and ft contains -7.0, fd is going to contain -5.0 (without this patch, it used to contain -7.0).

Fixes a79f5f9ba508 ("MIPS: math-emu: Add support for the MIPS R6 MAX{, A} FPU instruction")
Fixes 4e9561b20e2f ("MIPS: math-emu: Add support for the MIPS R6 MIN{, A} FPU instruction")
Signed-off-by Miodrag Dinic <[email protected]>
Signed-off-by Goran Ferenc <[email protected]>
Signed-off-by Aleksandar Markovic <[email protected]>
Reviewed-by James Hogan <[email protected]>
Cc Bo Hu <[email protected]>
Cc Douglas Leung <[email protected]>
Cc Jin Qian <[email protected]>
Cc Paul Burton <[email protected]>
Cc Petar Jovanovic <[email protected]>
Cc Raghu Gandham <[email protected]>
Cc [email protected]
Cc [email protected]

Patchwork: https://patchwork.linux-mips.org/patch/16882/

Signed-off-by Ralf Baechle <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 arch/mips/math-emu/dp_fmax.c |   32 ++++++++++++++++++++++++--------
 arch/mips/math-emu/dp_fmin.c |   32 ++++++++++++++++++++++++--------
 arch/mips/math-emu/sp_fmax.c |   32 ++++++++++++++++++++++++--------
 arch/mips/math-emu/sp_fmin.c |   32 ++++++++++++++++++++++++--------
 4 files changed, 96 insertions(+), 32 deletions(-)
arch/mips/math-emu/dp_fmax.c +24 -8
@@ -116,16 +116,32 @@ union ieee754dp ieee754dp_fmax(union iee
 	else if (xs < ys)
 		return x;
 
-	/* Compare exponent */
-	if (xe > ye)
-		return x;
-	else if (xe < ye)
-		return y;
+	/* Signs of inputs are equal, let's compare exponents */
+	if (xs == 0) {
+		/* Inputs are both positive */
+		if (xe > ye)
+			return x;
+		else if (xe < ye)
+			return y;
+	} else {
+		/* Inputs are both negative */
+		if (xe > ye)
+			return y;
+		else if (xe < ye)
+			return x;
+	}
 
-	/* Compare mantissa */
+	/* Signs and exponents of inputs are equal, let's compare mantissas */
+	if (xs == 0) {
+		/* Inputs are both positive, with equal signs and exponents */
+		if (xm <= ym)
+			return y;
+		return x;
+	}
+	/* Inputs are both negative, with equal signs and exponents */
 	if (xm <= ym)
-		return y;
-	return x;
+		return x;
+	return y;
 }
 
 union ieee754dp ieee754dp_fmaxa(union ieee754dp x, union ieee754dp y)
arch/mips/math-emu/dp_fmin.c +24 -8
@@ -116,16 +116,32 @@ union ieee754dp ieee754dp_fmin(union iee
 	else if (xs < ys)
 		return y;
 
-	/* Compare exponent */
-	if (xe > ye)
-		return y;
-	else if (xe < ye)
-		return x;
+	/* Signs of inputs are the same, let's compare exponents */
+	if (xs == 0) {
+		/* Inputs are both positive */
+		if (xe > ye)
+			return y;
+		else if (xe < ye)
+			return x;
+	} else {
+		/* Inputs are both negative */
+		if (xe > ye)
+			return x;
+		else if (xe < ye)
+			return y;
+	}
 
-	/* Compare mantissa */
+	/* Signs and exponents of inputs are equal, let's compare mantissas */
+	if (xs == 0) {
+		/* Inputs are both positive, with equal signs and exponents */
+		if (xm <= ym)
+			return x;
+		return y;
+	}
+	/* Inputs are both negative, with equal signs and exponents */
 	if (xm <= ym)
-		return x;
-	return y;
+		return y;
+	return x;
 }
 
 union ieee754dp ieee754dp_fmina(union ieee754dp x, union ieee754dp y)
arch/mips/math-emu/sp_fmax.c +24 -8
@@ -116,16 +116,32 @@ union ieee754sp ieee754sp_fmax(union iee
 	else if (xs < ys)
 		return x;
 
-	/* Compare exponent */
-	if (xe > ye)
-		return x;
-	else if (xe < ye)
-		return y;
+	/* Signs of inputs are equal, let's compare exponents */
+	if (xs == 0) {
+		/* Inputs are both positive */
+		if (xe > ye)
+			return x;
+		else if (xe < ye)
+			return y;
+	} else {
+		/* Inputs are both negative */
+		if (xe > ye)
+			return y;
+		else if (xe < ye)
+			return x;
+	}
 
-	/* Compare mantissa */
+	/* Signs and exponents of inputs are equal, let's compare mantissas */
+	if (xs == 0) {
+		/* Inputs are both positive, with equal signs and exponents */
+		if (xm <= ym)
+			return y;
+		return x;
+	}
+	/* Inputs are both negative, with equal signs and exponents */
 	if (xm <= ym)
-		return y;
-	return x;
+		return x;
+	return y;
 }
 
 union ieee754sp ieee754sp_fmaxa(union ieee754sp x, union ieee754sp y)
arch/mips/math-emu/sp_fmin.c +24 -8
@@ -116,16 +116,32 @@ union ieee754sp ieee754sp_fmin(union iee
 	else if (xs < ys)
 		return y;
 
-	/* Compare exponent */
-	if (xe > ye)
-		return y;
-	else if (xe < ye)
-		return x;
+	/* Signs of inputs are the same, let's compare exponents */
+	if (xs == 0) {
+		/* Inputs are both positive */
+		if (xe > ye)
+			return y;
+		else if (xe < ye)
+			return x;
+	} else {
+		/* Inputs are both negative */
+		if (xe > ye)
+			return x;
+		else if (xe < ye)
+			return y;
+	}
 
-	/* Compare mantissa */
+	/* Signs and exponents of inputs are equal, let's compare mantissas */
+	if (xs == 0) {
+		/* Inputs are both positive, with equal signs and exponents */
+		if (xm <= ym)
+			return x;
+		return y;
+	}
+	/* Inputs are both negative, with equal signs and exponents */
 	if (xm <= ym)
-		return x;
-	return y;
+		return y;
+	return x;
 }
 
 union ieee754sp ieee754sp_fmina(union ieee754sp x, union ieee754sp y)

Patches currently in stable-queue which might be from [email protected] are

queue-4.13/mips-math-emu-maddf-msubf-.-d-s-fix-nan-propagation.patch queue-4.13/mips-math-emu-max-maxa-min-mina-.-d-s-fix-cases-of-both-inputs-zero.patch queue-4.13/mips-math-emu-max-min-.-d-s-fix-cases-of-both-inputs-negative.patch queue-4.13/mips-math-emu-max-maxa-min-mina-.-d-s-fix-quiet-nan-propagation.patch queue-4.13/mips-math-emu-maddf-msubf-.d-fix-accuracy-64-bit-case.patch queue-4.13/mips-math-emu-maddf-msubf-.s-fix-accuracy-32-bit-case.patch queue-4.13/mips-math-emu-maxa-mina-.-d-s-fix-cases-of-input-values-with-opposite-signs.patch queue-4.13/mips-math-emu-maxa-mina-.-d-s-fix-cases-of-both-infinite-inputs.patch queue-4.13/mips-math-emu-mina.-d-s-fix-some-cases-of-infinity-and-zero-inputs.patch queue-4.13/mips-math-emu-maddf-msubf-.-d-s-fix-some-cases-of-zero-inputs.patch queue-4.13/mips-math-emu-maddf-msubf-.-d-s-clean-up-maddf_flags-enumeration.patch queue-4.13/mips-math-emu-maddf-msubf-.-d-s-fix-some-cases-of-infinite-inputs.patch