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[PATCH 4.13 018/109] MIPS: math-emu: <MAX|MAXA|MIN|MINA>.<D|S>: Fix cases of both inputs zero

From Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Newsgroups linux.kernel
Subject [PATCH 4.13 018/109] MIPS: math-emu: <MAX|MAXA|MIN|MINA>.<D|S>: Fix cases of both inputs zero
Date 2017-09-24 23:10 +0200
Message-ID <utmk1-5jg-3@gated-at.bofh.it> (permalink)
References <utm0F-4Xd-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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

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

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

commit 15560a58bfd4ff82cdd16b2270d4ef9b06d2cc4d upstream.

Fix the value returned by <MAX|MAXA|MIN|MINA>.<D|S>, if both inputs
are zeros. The right behavior in such cases is stated in instruction
reference manual and is as follows:

   fs  ft       MAX     MIN       MAXA    MINA
  ---------------------------------------------
    0   0        0       0         0       0
    0  -0        0      -0         0      -0
   -0   0        0      -0         0      -0
   -0  -0       -0      -0        -0      -0

Prior to this patch, some of the above cases were yielding correct
results. However, for the sake of code consistency, all such cases
are rewritten in this patch.

A relevant example:

MAX.S fd,fs,ft:
  If fs contains +0.0, and ft contains -0.0, fd is going to contain
  +0.0 (without this patch, it used to contain -0.0).

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 <miodrag.dinic@imgtec.com>
Signed-off-by: Goran Ferenc <goran.ferenc@imgtec.com>
Signed-off-by: Aleksandar Markovic <aleksandar.markovic@imgtec.com>
Reviewed-by: James Hogan <james.hogan@imgtec.com>
Cc: Bo Hu <bohu@google.com>
Cc: Douglas Leung <douglas.leung@imgtec.com>
Cc: Jin Qian <jinqian@google.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Petar Jovanovic <petar.jovanovic@imgtec.com>
Cc: Raghu Gandham <raghu.gandham@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/16881/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/mips/math-emu/dp_fmax.c |    8 ++------
 arch/mips/math-emu/dp_fmin.c |    8 ++------
 arch/mips/math-emu/sp_fmax.c |    8 ++------
 arch/mips/math-emu/sp_fmin.c |    8 ++------
 4 files changed, 8 insertions(+), 24 deletions(-)

--- a/arch/mips/math-emu/dp_fmax.c
+++ b/arch/mips/math-emu/dp_fmax.c
@@ -92,9 +92,7 @@ union ieee754dp ieee754dp_fmax(union iee
 		return ys ? x : y;
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
-		if (xs == ys)
-			return x;
-		return ieee754dp_zero(1);
+		return ieee754dp_zero(xs & ys);
 
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
 		DPDNORMX;
@@ -204,9 +202,7 @@ union ieee754dp ieee754dp_fmaxa(union ie
 		return y;
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
-		if (xs == ys)
-			return x;
-		return ieee754dp_zero(1);
+		return ieee754dp_zero(xs & ys);
 
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
 		DPDNORMX;
--- a/arch/mips/math-emu/dp_fmin.c
+++ b/arch/mips/math-emu/dp_fmin.c
@@ -92,9 +92,7 @@ union ieee754dp ieee754dp_fmin(union iee
 		return ys ? y : x;
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
-		if (xs == ys)
-			return x;
-		return ieee754dp_zero(1);
+		return ieee754dp_zero(xs | ys);
 
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
 		DPDNORMX;
@@ -204,9 +202,7 @@ union ieee754dp ieee754dp_fmina(union ie
 		return y;
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
-		if (xs == ys)
-			return x;
-		return ieee754dp_zero(1);
+		return ieee754dp_zero(xs | ys);
 
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
 		DPDNORMX;
--- a/arch/mips/math-emu/sp_fmax.c
+++ b/arch/mips/math-emu/sp_fmax.c
@@ -92,9 +92,7 @@ union ieee754sp ieee754sp_fmax(union iee
 		return ys ? x : y;
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
-		if (xs == ys)
-			return x;
-		return ieee754sp_zero(1);
+		return ieee754sp_zero(xs & ys);
 
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
 		SPDNORMX;
@@ -204,9 +202,7 @@ union ieee754sp ieee754sp_fmaxa(union ie
 		return y;
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
-		if (xs == ys)
-			return x;
-		return ieee754sp_zero(1);
+		return ieee754sp_zero(xs & ys);
 
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
 		SPDNORMX;
--- a/arch/mips/math-emu/sp_fmin.c
+++ b/arch/mips/math-emu/sp_fmin.c
@@ -92,9 +92,7 @@ union ieee754sp ieee754sp_fmin(union iee
 		return ys ? y : x;
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
-		if (xs == ys)
-			return x;
-		return ieee754sp_zero(1);
+		return ieee754sp_zero(xs | ys);
 
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
 		SPDNORMX;
@@ -204,9 +202,7 @@ union ieee754sp ieee754sp_fmina(union ie
 		return y;
 
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
-		if (xs == ys)
-			return x;
-		return ieee754sp_zero(1);
+		return ieee754sp_zero(xs | ys);
 
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
 		SPDNORMX;

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[PATCH 4.13 000/109] 4.13.4-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 058/109] scsi: qedi: off by one in qedi_get_cmd_from_tid() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 041/109] powerpc/powernv/npu: Move tlb flush before launching ATSD Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 088/109] media: venus: fix copy/paste error in return_buf_error Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 066/109] scsi: sg: fixup infoleak when using SG_GET_REQUEST_TABLE Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 031/109] crypto: scompress - dont sleep with preemption disabled Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 060/109] scsi: megaraid_sas: mismatch of allocated MFI frame size and length exposed in MFI MPT pass through command Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 039/109] ext4: fix quota inconsistency during orphan cleanup for read-only mounts Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 067/109] scsi: qla2xxx: Update fw_started flags at qpair creation. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 054/109] scsi: zfcp: fix missing trace records for early returns in TMF eh handlers Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 083/109] net/netfilter/nf_conntrack_core: Fix net_conntrack_lock() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 028/109] MIPS: math-emu: <MADDF|MSUBF>.D: Fix accuracy (64-bit case) Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 049/109] skd: Submit requests to firmware before triggering the doorbell Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 085/109] s390/mm: fix race on mm->context.flush_mm Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 062/109] scsi: megaraid_sas: Check valid aen class range to avoid kernel panic Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 036/109] wcn36xx: Introduce mutual exclusion of fw configuration Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 037/109] ext4: in ext4_seek_{hole,data}, return -ENXIO for negative offsets Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 078/109] tracing: Fix clear of RECORDED_TGID flag when disabling trace event Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 051/109] scsi: zfcp: add handling for FCP_RESID_OVER to the fcp ingress path Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 059/109] scsi: aacraid: Fix command send race condition Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 027/109] MIPS: math-emu: <MADDF|MSUBF>.S: Fix accuracy (32-bit case) Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 052/109] scsi: zfcp: fix capping of unsuccessful GPN_FT SAN response trace records Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 079/109] tracing: Apply trace_clock changes to instance max buffer Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 055/109] scsi: zfcp: fix payload with full FCP_RSP IU in SCSI trace records Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 026/109] MIPS: math-emu: <MADDF|MSUBF>.<D|S>: Clean up "maddf_flags" enumeration Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 029/109] docs: disable KASLR when debugging kernel Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 043/109] powerpc: Fix DAR reporting when alignment handler faults Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 046/109] md/bitmap: copy correct data for bitmap super Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 075/109] ftrace: Fix selftest goto location on error Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 081/109] PCI: shpchp: Enable bridge bus mastering if MSI is enabled Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:00 +0200
  [PATCH 4.13 018/109] MIPS: math-emu: <MAX|MAXA|MIN|MINA>.<D|S>: Fix cases of both inputs zero Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.13 024/109] MIPS: math-emu: <MADDF|MSUBF>.<D|S>: Fix some cases of infinite inputs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.13 016/109] Input: i8042 - add Gigabyte P57 to the keyboard reset table Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.13 008/109] Input: xpad - validate USB endpoint type during probe Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.13 020/109] MIPS: math-emu: <MAXA|MINA>.<D|S>: Fix cases of input values with opposite signs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.13 023/109] MIPS: math-emu: <MADDF|MSUBF>.<D|S>: Fix NaN propagation Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.13 009/109] drm/amdgpu: read reg in each iterator of psp_wait_for loop Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.13 010/109] tty: improve tty_insert_flip_char() fast path Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.13 014/109] pinctrl: samsung: Fix NULL pointer exception on external interrupts on S3C24xx Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.13 022/109] MIPS: math-emu: MINA.<D|S>: Fix some cases of infinity and zero inputs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.13 011/109] tty: improve tty_insert_flip_char() slow path Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.13 019/109] MIPS: math-emu: <MAX|MIN>.<D|S>: Fix cases of both inputs negative Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.13 001/109] orangefs: Dont clear SGID when inheriting ACLs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
    Re: [PATCH 4.13 001/109] orangefs: Dont clear SGID when inheriting ACLs Mike Marshall <hubcap@omnibond.com> - 2017-09-26 02:10 +0200
  [PATCH 4.13 004/109] IB/{qib, hfi1}: Avoid flow control testing for RDMA write operation Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.13 006/109] srcu: Provide ordering for CPU not involved in grace period Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  [PATCH 4.13 017/109] MIPS: math-emu: <MAX|MAXA|MIN|MINA>.<D|S>: Fix quiet NaN propagation Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-24 23:10 +0200
  Re: [PATCH 4.13 000/109] 4.13.4-stable review Guenter Roeck <linux@roeck-us.net> - 2017-09-25 03:10 +0200
    Re: [PATCH 4.13 000/109] 4.13.4-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-25 08:40 +0200
  Re: [PATCH 4.13 000/109] 4.13.4-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2017-09-26 01:20 +0200
    Re: [PATCH 4.13 000/109] 4.13.4-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-26 09:40 +0200

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