From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [103.22.144.67]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 1A8851A17FC for ; Fri, 15 Jan 2016 16:54:25 +1100 (AEDT) Received: from mail-pf0-x242.google.com (mail-pf0-x242.google.com [IPv6:2607:f8b0:400e:c00::242]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 8B9F1140328 for ; Fri, 15 Jan 2016 16:54:24 +1100 (AEDT) Received: by mail-pf0-x242.google.com with SMTP id n128so8152374pfn.3 for ; Thu, 14 Jan 2016 21:54:24 -0800 (PST) Date: Fri, 15 Jan 2016 16:54:16 +1100 From: Cyril Bur To: Michael Neuling Cc: linuxppc-dev@ozlabs.org Subject: Re: [PATCH V2 4/8] powerpc: Explicitly disable math features when copying thread Message-ID: <20160115165416.2f7328ae@camb691> In-Reply-To: <1452836542.25634.33.camel@neuling.org> References: <1452834254-22078-1-git-send-email-cyrilbur@gmail.com> <1452834254-22078-5-git-send-email-cyrilbur@gmail.com> <1452836542.25634.33.camel@neuling.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, 15 Jan 2016 16:42:22 +1100 Michael Neuling wrote: > On Fri, 2016-01-15 at 16:04 +1100, Cyril Bur wrote: > > With threads leaving the math bits enabled in their saved MSR to indicate > > that the hardware is hot and a restore is not needed, children need to turn > > it off as when they do get scheduled, there's no way their registers could > > have been hot. > > Is this a bug in the current code? > You're very consistent: https://lists.ozlabs.org/pipermail/linuxppc-dev/2015-November/136469.html ;) > Mikey > > > Signed-off-by: Cyril Bur > > --- > > arch/powerpc/kernel/process.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/arch/powerpc/kernel/process.c > > b/arch/powerpc/kernel/process.c > > index dccc87e..e0c3d2d 100644 > > --- a/arch/powerpc/kernel/process.c > > +++ b/arch/powerpc/kernel/process.c > > @@ -1307,6 +1307,7 @@ int copy_thread(unsigned long clone_flags, > > unsigned long usp, > > > > f = ret_from_fork; > > } > > + childregs->msr &= ~(MSR_FP|MSR_VEC|MSR_VSX); > > sp -= STACK_FRAME_OVERHEAD; > > > > /*