[PATCH v2] arm64: Preserve the user r/w register tpidr_el0 on context switch and fork in compat mode

[André Hentschel]

Am 27.05.2015 um 16:36 schrieb Will Deacon:
> Hi André,
> 
> On Wed, May 20, 2015 at 05:18:29PM +0100, André Hentschel wrote:
>> From: André Hentschel <nerv at dawncrow.de>
>>
>> Since commit a4780adeefd042482f624f5e0d577bf9cdcbb760 the user writeable TLS
>> register on ARM is preserved per thread.
>>
>> This patch does it analogous to the ARM patch, but for compat mode on ARM64.
>>
>> Signed-off-by: André Hentschel <nerv at dawncrow.de>
>> Cc: Will Deacon <will.deacon at arm.com>
>> Cc: Catalin Marinas <catalin.marinas at arm.com>
>>
>> ---
>> This patch is against Linux 4.1-rc1 (b787f68c36d49bb1d9236f403813641efa74a031)
>>
>> v2: Trying to address suggestions by Will Deacon
>>
>> @Will Deacon: 	The macro you suggested is not helpful it seems, instead i introduced
>> 		static functions. They also could be macros i guess, but it seems
>> 		much cleaner to me to use functions as it only affects one file.
> 
> I wanted to understand in more detail why the macro didn't work out for
> you, so I trued hacking together my own version of the patch (see below).
> It seems to hold up to light testing, so it would be good to know where
> you ran into problems.
> 
>> Should the final version be send to rmk's patchtracker or will someone
>> else pick it up?
> 
> This is an arm64 patch, so either Catalin or me will pick it up directly
> when it's ready to be merged.
> 
> Will

Your patch works, you can add me as Tested-by. :)
My bad was that i didn't know that macro style (returning a variable conditionally with c code)
Sadly no new commit by me :(