[PATCH] ARM: VFP: Fix emulation of multiply accumulate instructions

[Jay Foad]

The emulation for single and double precision multiply accumulate
instructions correctly normalised any denormal values in the operand
registers, but failed to normalise the destination (accumulator)
register.

This fixes https://bugzilla.kernel.org/show_bug.cgi?id=70501

Signed-off-by: Jay Foad <jay.foad@xxxxxxxxx>
---
 arch/arm/vfp/vfpdouble.c | 2 ++
 arch/arm/vfp/vfpsingle.c | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/arch/arm/vfp/vfpdouble.c b/arch/arm/vfp/vfpdouble.c
index 6cac43bd1d86..423f56dd4028 100644
--- a/arch/arm/vfp/vfpdouble.c
+++ b/arch/arm/vfp/vfpdouble.c
@@ -866,6 +866,8 @@ vfp_double_multiply_accumulate(int dd, int dn, int dm, u32 fpscr, u32 negate, ch
 		vdp.sign = vfp_sign_negate(vdp.sign);
 
 	vfp_double_unpack(&vdn, vfp_get_double(dd));
+	if (vdn.exponent == 0 && vdn.significand)
+		vfp_double_normalise_denormal(&vdn);
 	if (negate & NEG_SUBTRACT)
 		vdn.sign = vfp_sign_negate(vdn.sign);
 
diff --git a/arch/arm/vfp/vfpsingle.c b/arch/arm/vfp/vfpsingle.c
index b252631b406b..4f96c1617aae 100644
--- a/arch/arm/vfp/vfpsingle.c
+++ b/arch/arm/vfp/vfpsingle.c
@@ -915,6 +915,8 @@ vfp_single_multiply_accumulate(int sd, int sn, s32 m, u32 fpscr, u32 negate, cha
 	v = vfp_get_float(sd);
 	pr_debug("VFP: s%u = %08x\n", sd, v);
 	vfp_single_unpack(&vsn, v);
+	if (vsn.exponent == 0 && vsn.significand)
+		vfp_single_normalise_denormal(&vsn);
 	if (negate & NEG_SUBTRACT)
 		vsn.sign = vfp_sign_negate(vsn.sign);
 
-- 
1.8.3.2

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/