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Message-Id: <20200508123126.046827568@linuxfoundation.org>
Date: Fri, 8 May 2020 14:30:13 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Paul Burton <paul.burton@...tec.com>,
Adam Buchbinder <adam.buchbinder@...il.com>,
"Maciej W. Rozycki" <macro@...tec.com>, linux-mips@...ux-mips.org,
Ralf Baechle <ralf@...ux-mips.org>
Subject: [PATCH 4.4 022/312] MIPS: math-emu: Fix m{add,sub}.s shifts
From: Paul Burton <paul.burton@...tec.com>
commit db57f29d50683afd75c7f8b9908af7669837c3a9 upstream.
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")
Cc: Adam Buchbinder <adam.buchbinder@...il.com>
Cc: Maciej W. Rozycki <macro@...tec.com>
Cc: linux-mips@...ux-mips.org
Cc: linux-kernel@...r.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/13159/
Signed-off-by: Ralf Baechle <ralf@...ux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
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(-)
--- a/arch/mips/math-emu/ieee754sp.c
+++ b/arch/mips/math-emu/ieee754sp.c
@@ -130,7 +130,8 @@ union ieee754sp ieee754sp_format(int sn,
} 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);
}
--- a/arch/mips/math-emu/ieee754sp.h
+++ b/arch/mips/math-emu/ieee754sp.h
@@ -46,19 +46,17 @@ static inline int ieee754sp_finite(union
}
/* 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) \
--- 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 ieee
* 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);
--- a/arch/mips/math-emu/sp_maddf.c
+++ b/arch/mips/math-emu/sp_maddf.c
@@ -208,16 +208,18 @@ union ieee754sp ieee754sp_maddf(union ie
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);
@@ -230,7 +232,8 @@ union ieee754sp ieee754sp_maddf(union ie
zm = zm + rm;
if (zm >> (SP_FBITS + 1 + 3)) { /* carry out */
- SPXSRSX1();
+ zm = XSPSRS1(zm);
+ ze++;
}
} else {
if (zm >= rm) {
--- 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 ieee
* 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);
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