Re: [PATCH] arm: Preserve TPIDRURW on context switch

From: André Hentschel
Date: Sat Feb 09 2013 - 11:44:37 EST

Am 08.02.2013 16:48, schrieb Will Deacon:
> On Wed, Feb 06, 2013 at 11:01:23PM +0000, André Hentschel wrote:
>> Am 06.02.2013 23:51, schrieb Russell King - ARM Linux:
>>> On Wed, Feb 06, 2013 at 11:43:10PM +0100, André Hentschel wrote:
>>>> 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.
>>> I'd prefer this was done a little more sensitively to those CPUs where
>>> loads/stores are expensive, namely:
>>>> +
>>>> + @ preserve TPIDRURW register state
>>>> + get_tls2 r3, r4, r5
>>>> + str r3, [r1, #TI_TP2_VALUE]
>>>> + ldr r3, [r2, #TI_TP2_VALUE]
>>>> + set_tls2 r3, r4, r5
>>> those two loads/stores get omitted from the thread switching if the CPU
>>> doesn't support it. Do you think that's something you could do?
>> No, i'm not sure how to improve this. How does the process can continue, can you or someone else fix that and add his Signed-off-by?
> How about something like the (completely untested) diff below?
> Andre: if this works for you, I'm happy to write a commit message etc.
> Cheers,
> Will
> --->8

I'll try the next days and report back, thx.

Best Regards, André Hentschel
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