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Date: Thu, 21 Apr 2016 14:04:54 +0100
From: Paul Burton <paul.burton@...tec.com>
To: <linux-mips@...ux-mips.org>, Ralf Baechle <ralf@...ux-mips.org>
CC: Paul Burton <paul.burton@...tec.com>,
Adam Buchbinder <adam.buchbinder@...il.com>,
"Maciej W. Rozycki" <macro@...tec.com>,
<linux-kernel@...r.kernel.org>,
Markos Chandras <markos.chandras@...tec.com>
Subject: [PATCH 10/11] MIPS: math-emu: Fix m{add,sub}.s shifts
The code in _sp_maddf (formerly ieee754sp_madd) appears to have been
copied verbatim from ieee754sp_add, and although it's adding the
unpacked "r" & "z" floats it kept using macros that operate on "x" &
"y". This led to the addition being carried out incorrectly on some
mismash of the product, accumulator & multiplicand fields. Typically
this would lead to the assertions "ze == re" & "ze <= SP_EMAX" failing
since ze & re hadn't been operated upon.
Signed-off-by: Paul Burton <paul.burton@...tec.com>
Fixes: e24c3bec3e8e ("MIPS: math-emu: Add support for the MIPS R6 MADDF FPU instruction")
---
arch/mips/math-emu/ieee754sp.c | 3 ++-
arch/mips/math-emu/ieee754sp.h | 16 +++++++---------
arch/mips/math-emu/sp_add.c | 6 ++++--
arch/mips/math-emu/sp_maddf.c | 13 ++++++++-----
arch/mips/math-emu/sp_sub.c | 6 ++++--
5 files changed, 25 insertions(+), 19 deletions(-)
diff --git a/arch/mips/math-emu/ieee754sp.c b/arch/mips/math-emu/ieee754sp.c
index e0b2c45..2de0c09 100644
--- a/arch/mips/math-emu/ieee754sp.c
+++ b/arch/mips/math-emu/ieee754sp.c
@@ -138,7 +138,8 @@ union ieee754sp ieee754sp_format(int sn, int xe, unsigned xm)
} else {
/* sticky right shift es bits
*/
- SPXSRSXn(es);
+ xm = XSPSRS(xm, es);
+ xe += es;
assert((xm & (SP_HIDDEN_BIT << 3)) == 0);
assert(xe == SP_EMIN);
}
diff --git a/arch/mips/math-emu/ieee754sp.h b/arch/mips/math-emu/ieee754sp.h
index b24fdff..8476067 100644
--- a/arch/mips/math-emu/ieee754sp.h
+++ b/arch/mips/math-emu/ieee754sp.h
@@ -46,19 +46,17 @@ static inline int ieee754sp_finite(union ieee754sp x)
}
/* 3bit extended single precision sticky right shift */
-#define SPXSRSXn(rs) \
- (xe += rs, \
- xm = (rs > (SP_FBITS+3))?1:((xm) >> (rs)) | ((xm) << (32-(rs)) != 0))
+#define XSPSRS(v, rs) \
+ ((rs > (SP_FBITS+3))?1:((v) >> (rs)) | ((v) << (32-(rs)) != 0))
-#define SPXSRSX1() \
- (xe++, (xm = (xm >> 1) | (xm & 1)))
+#define XSPSRS1(m) \
+ ((m >> 1) | (m & 1))
-#define SPXSRSYn(rs) \
- (ye+=rs, \
- ym = (rs > (SP_FBITS+3))?1:((ym) >> (rs)) | ((ym) << (32-(rs)) != 0))
+#define SPXSRSX1() \
+ (xe++, (xm = XSPSRS1(xm)))
#define SPXSRSY1() \
- (ye++, (ym = (ym >> 1) | (ym & 1)))
+ (ye++, (ym = XSPSRS1(ym)))
/* convert denormal to normalized with extended exponent */
#define SPDNORMx(m,e) \
diff --git a/arch/mips/math-emu/sp_add.c b/arch/mips/math-emu/sp_add.c
index f1c87b0..c55c0c0 100644
--- a/arch/mips/math-emu/sp_add.c
+++ b/arch/mips/math-emu/sp_add.c
@@ -132,13 +132,15 @@ union ieee754sp ieee754sp_add(union ieee754sp x, union ieee754sp y)
* Have to shift y fraction right to align.
*/
s = xe - ye;
- SPXSRSYn(s);
+ ym = XSPSRS(ym, s);
+ ye += s;
} else if (ye > xe) {
/*
* Have to shift x fraction right to align.
*/
s = ye - xe;
- SPXSRSXn(s);
+ xm = XSPSRS(xm, s);
+ xe += s;
}
assert(xe == ye);
assert(xe <= SP_EMAX);
diff --git a/arch/mips/math-emu/sp_maddf.c b/arch/mips/math-emu/sp_maddf.c
index 86e1d0b..a8cd8b4 100644
--- a/arch/mips/math-emu/sp_maddf.c
+++ b/arch/mips/math-emu/sp_maddf.c
@@ -214,16 +214,18 @@ static union ieee754sp _sp_maddf(union ieee754sp z, union ieee754sp x,
if (ze > re) {
/*
- * Have to shift y fraction right to align.
+ * Have to shift r fraction right to align.
*/
s = ze - re;
- SPXSRSYn(s);
+ rm = XSPSRS(rm, s);
+ re += s;
} else if (re > ze) {
/*
- * Have to shift x fraction right to align.
+ * Have to shift z fraction right to align.
*/
s = re - ze;
- SPXSRSYn(s);
+ zm = XSPSRS(zm, s);
+ ze += s;
}
assert(ze == re);
assert(ze <= SP_EMAX);
@@ -236,7 +238,8 @@ static union ieee754sp _sp_maddf(union ieee754sp z, union ieee754sp x,
zm = zm + rm;
if (zm >> (SP_FBITS + 1 + 3)) { /* carry out */
- SPXSRSX1();
+ zm = XSPSRS1(zm);
+ ze++;
}
} else {
if (zm >= rm) {
diff --git a/arch/mips/math-emu/sp_sub.c b/arch/mips/math-emu/sp_sub.c
index ec5f937..dc998ed 100644
--- a/arch/mips/math-emu/sp_sub.c
+++ b/arch/mips/math-emu/sp_sub.c
@@ -134,13 +134,15 @@ union ieee754sp ieee754sp_sub(union ieee754sp x, union ieee754sp y)
* have to shift y fraction right to align
*/
s = xe - ye;
- SPXSRSYn(s);
+ ym = XSPSRS(ym, s);
+ ye += s;
} else if (ye > xe) {
/*
* have to shift x fraction right to align
*/
s = ye - xe;
- SPXSRSXn(s);
+ xm = XSPSRS(xm, s);
+ xe += s;
}
assert(xe == ye);
assert(xe <= SP_EMAX);
--
2.8.0
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