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[PATCH 4.13 019/109] MIPS: math-emu: <MAX|MIN>.<D|S>: Fix cases of both inputs negative

From Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Newsgroups linux.kernel
Subject [PATCH 4.13 019/109] MIPS: math-emu: <MAX|MIN>.<D|S>: Fix cases of both inputs negative
Date 2017-09-24 23:10 +0200
Message-ID <utmk3-5jg-71@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 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 <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/16882/
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 |   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(-)

--- a/arch/mips/math-emu/dp_fmax.c
+++ b/arch/mips/math-emu/dp_fmax.c
@@ -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)
--- a/arch/mips/math-emu/dp_fmin.c
+++ b/arch/mips/math-emu/dp_fmin.c
@@ -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)
--- a/arch/mips/math-emu/sp_fmax.c
+++ b/arch/mips/math-emu/sp_fmax.c
@@ -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)
--- a/arch/mips/math-emu/sp_fmin.c
+++ b/arch/mips/math-emu/sp_fmin.c
@@ -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)

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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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