From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932254AbaDHNNu (ORCPT ); Tue, 8 Apr 2014 09:13:50 -0400 Received: from fw-tnat.cambridge.arm.com ([217.140.96.21]:54671 "EHLO cam-smtp0.cambridge.arm.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S932233AbaDHNNr (ORCPT ); Tue, 8 Apr 2014 09:13:47 -0400 Date: Tue, 8 Apr 2014 14:13:11 +0100 From: Dave Martin To: Jay Foad Cc: linux@arm.linux.org.uk, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] ARM: VFP: Fix emulation of multiply accumulate instructions Message-ID: <20140408131256.GA5637@e103592.cambridge.arm.com> References: <1395852549-2745-1-git-send-email-jay.foad@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1395852549-2745-1-git-send-email-jay.foad@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 26, 2014 at 04:49:09PM +0000, Jay Foad wrote: > 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 Reviewed-by: Dave Martin This appears to be clean and straightforward, so if nobody else has commented on this by the time -rc1 comes out, I suggest you rebase it and send it to the patch system. (See http://www.arm.linux.org.uk/developer/patches/info.php for details -- make sure you read it carefully.) Has this issue been hitting real-world users of the kernel, or is this fixing a latent bug? Cheers ---Dave > --- > 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 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel