4.13-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Aleksandar Markovic <aleksandar.marko...@imgtec.com>

commit e78bf0dc4789bdea1453595ae89e8db65918e22e upstream.

Fix the value returned by <MAX|MAXA|MIN|MINA>.<D|S> fd,fs,ft, if both
inputs are quiet NaNs. The <MAX|MAXA|MIN|MINA>.<D|S> specifications
state that the returned value in such cases should be the quiet NaN
contained in register fs.

A relevant example:

MAX.S fd,fs,ft:
  If fs contains qNaN1, and ft contains qNaN2, fd is going to contain
  qNaN1 (without this patch, it used to contain qNaN2).

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 <miodrag.di...@imgtec.com>
Signed-off-by: Goran Ferenc <goran.fer...@imgtec.com>
Signed-off-by: Aleksandar Markovic <aleksandar.marko...@imgtec.com>
Reviewed-by: James Hogan <james.ho...@imgtec.com>
Cc: Bo Hu <b...@google.com>
Cc: Douglas Leung <douglas.le...@imgtec.com>
Cc: Jin Qian <jinq...@google.com>
Cc: Paul Burton <paul.bur...@imgtec.com>
Cc: Petar Jovanovic <petar.jovano...@imgtec.com>
Cc: Raghu Gandham <raghu.gand...@imgtec.com>
Cc: linux-m...@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/16880/
Signed-off-by: Ralf Baechle <r...@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 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, 112 insertions(+), 16 deletions(-)

--- a/arch/mips/math-emu/dp_fmax.c
+++ b/arch/mips/math-emu/dp_fmax.c
@@ -47,14 +47,26 @@ union ieee754dp ieee754dp_fmax(union iee
        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
                return ieee754dp_nanxcpt(x);
 
-       /* numbers are preferred to NaNs */
+       /*
+        * Quiet NaN handling
+        */
+
+       /*
+        *    The case of both inputs quiet NaNs
+        */
+       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
+               return x;
+
+       /*
+        *    The cases of exactly one input quiet NaN (numbers
+        *    are here preferred as returned values to NaNs)
+        */
        case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
                return x;
 
-       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
@@ -147,14 +159,26 @@ union ieee754dp ieee754dp_fmaxa(union ie
        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
                return ieee754dp_nanxcpt(x);
 
-       /* numbers are preferred to NaNs */
+       /*
+        * Quiet NaN handling
+        */
+
+       /*
+        *    The case of both inputs quiet NaNs
+        */
+       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
+               return x;
+
+       /*
+        *    The cases of exactly one input quiet NaN (numbers
+        *    are here preferred as returned values to NaNs)
+        */
        case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
                return x;
 
-       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
--- a/arch/mips/math-emu/dp_fmin.c
+++ b/arch/mips/math-emu/dp_fmin.c
@@ -47,14 +47,26 @@ union ieee754dp ieee754dp_fmin(union iee
        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
                return ieee754dp_nanxcpt(x);
 
-       /* numbers are preferred to NaNs */
+       /*
+        * Quiet NaN handling
+        */
+
+       /*
+        *    The case of both inputs quiet NaNs
+        */
+       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
+               return x;
+
+       /*
+        *    The cases of exactly one input quiet NaN (numbers
+        *    are here preferred as returned values to NaNs)
+        */
        case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
                return x;
 
-       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
@@ -147,14 +159,26 @@ union ieee754dp ieee754dp_fmina(union ie
        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
                return ieee754dp_nanxcpt(x);
 
-       /* numbers are preferred to NaNs */
+       /*
+        * Quiet NaN handling
+        */
+
+       /*
+        *    The case of both inputs quiet NaNs
+        */
+       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
+               return x;
+
+       /*
+        *    The cases of exactly one input quiet NaN (numbers
+        *    are here preferred as returned values to NaNs)
+        */
        case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
                return x;
 
-       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
--- a/arch/mips/math-emu/sp_fmax.c
+++ b/arch/mips/math-emu/sp_fmax.c
@@ -47,14 +47,26 @@ union ieee754sp ieee754sp_fmax(union iee
        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
                return ieee754sp_nanxcpt(x);
 
-       /* numbers are preferred to NaNs */
+       /*
+        * Quiet NaN handling
+        */
+
+       /*
+        *    The case of both inputs quiet NaNs
+        */
+       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
+               return x;
+
+       /*
+        *    The cases of exactly one input quiet NaN (numbers
+        *    are here preferred as returned values to NaNs)
+        */
        case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
                return x;
 
-       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
@@ -147,14 +159,26 @@ union ieee754sp ieee754sp_fmaxa(union ie
        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
                return ieee754sp_nanxcpt(x);
 
-       /* numbers are preferred to NaNs */
+       /*
+        * Quiet NaN handling
+        */
+
+       /*
+        *    The case of both inputs quiet NaNs
+        */
+       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
+               return x;
+
+       /*
+        *    The cases of exactly one input quiet NaN (numbers
+        *    are here preferred as returned values to NaNs)
+        */
        case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
                return x;
 
-       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
--- a/arch/mips/math-emu/sp_fmin.c
+++ b/arch/mips/math-emu/sp_fmin.c
@@ -47,14 +47,26 @@ union ieee754sp ieee754sp_fmin(union iee
        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
                return ieee754sp_nanxcpt(x);
 
-       /* numbers are preferred to NaNs */
+       /*
+        * Quiet NaN handling
+        */
+
+       /*
+        *    The case of both inputs quiet NaNs
+        */
+       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
+               return x;
+
+       /*
+        *    The cases of exactly one input quiet NaN (numbers
+        *    are here preferred as returned values to NaNs)
+        */
        case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
                return x;
 
-       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
@@ -147,14 +159,26 @@ union ieee754sp ieee754sp_fmina(union ie
        case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
                return ieee754sp_nanxcpt(x);
 
-       /* numbers are preferred to NaNs */
+       /*
+        * Quiet NaN handling
+        */
+
+       /*
+        *    The case of both inputs quiet NaNs
+        */
+       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
+               return x;
+
+       /*
+        *    The cases of exactly one input quiet NaN (numbers
+        *    are here preferred as returned values to NaNs)
+        */
        case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
                return x;
 
-       case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
        case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):


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