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From: Will Deacon <will.deacon@arm.com>
To: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: "André Hentschel" <nerv@dawncrow.de>,
	"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>
Subject: Re: [PATCHv2] arm: Preserve TPIDRURW on context switch
Date: Mon, 22 Apr 2013 16:18:37 +0100	[thread overview]
Message-ID: <20130422151836.GA15665@mudshark.cambridge.arm.com> (raw)
In-Reply-To: <20130422143616.GP14496@n2100.arm.linux.org.uk>

On Mon, Apr 22, 2013 at 03:36:16PM +0100, Russell King - ARM Linux wrote:
> On Fri, Apr 19, 2013 at 05:54:35PM +0200, André Hentschel wrote:
> > From: =?UTF-8?q?Andr=C3=A9=20Hentschel?= <nerv@dawncrow.de>
> > 
> > There are more and more applications coming to WinRT, Wine could support them,
> > but mostly they expect to have the thread environment block (TEB) in TPIDRURW.
> > This register must be preserved per thread instead of being cleared.
> > 
> > Signed-off-by: André Hentschel <nerv@dawncrow.de>
> 
> This actually makes things less efficient all round, because you
> now use the value immediately after loading, which means it will cause
> pipeline stalls, certainly on older CPUs.
> 
> Could you please rework the patch to try avoiding soo many modifications
> to the way things have been done here?

copy_thread also needs updating so that the *register* value for the parent
is copied to the child, since the parent may have written the register
after the last context-switch, meaning that tp_value is out-of-date.

Will

  reply	other threads:[~2013-04-22 15:18 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-04-19 15:54 [PATCHv2] arm: Preserve TPIDRURW on context switch André Hentschel
2013-04-19 15:54 ` André Hentschel
2013-04-22 14:36 ` Russell King - ARM Linux
2013-04-22 15:18   ` Will Deacon [this message]
2013-04-22 21:07     ` André Hentschel
2013-04-23  9:15       ` Will Deacon
2013-04-23  9:15         ` Will Deacon
2013-04-23 22:42         ` André Hentschel
2013-04-24  9:42           ` Will Deacon
2013-04-24  9:42             ` Will Deacon
2013-04-24 21:44             ` André Hentschel
2013-05-02 19:54             ` André Hentschel
2013-05-03  9:21               ` Jonathan Austin
2013-05-03  9:55                 ` Russell King - ARM Linux
2013-05-03 15:24                   ` Jonathan Austin
2013-05-04 15:54                     ` André Hentschel
2013-05-06 22:27                     ` André Hentschel
2013-05-06 22:27                       ` André Hentschel
2013-05-07 10:16                       ` Jonathan Austin

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