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@imgtec.com>
Fixes: e24c3bec3e8e ("MIPS: math-emu: Add support for the MIPS R6 MADDF FPU instruction")
Cc: Adam Buchbinder <adam.buchbinder@gmail.com>
Cc: Maciej W. Rozycki <macro@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/13159/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/math-emu/ieee754sp.c b/arch/mips/math-emu/ieee754sp.c
index 860e916..260e6896 100644
--- a/arch/mips/math-emu/ieee754sp.c
+++ b/arch/mips/math-emu/ieee754sp.c
@@ -141,7 +141,8 @@
} 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 @@
}
/* 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 XSPSRS1(m) \
+ ((m >> 1) | (m & 1))
#define SPXSRSX1() \
- (xe++, (xm = (xm >> 1) | (xm & 1)))
-
-#define SPXSRSYn(rs) \
- (ye+=rs, \
- ym = (rs > (SP_FBITS+3))?1:((ym) >> (rs)) | ((ym) << (32-(rs)) != 0))
+ (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 @@
* 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 @@
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 @@
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 @@
* 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);
