[PATCH] power: Fix VSCR position on ucontext

[Rogerio Alves]

I am sending patch v4 attached in this email with the fixes proposed 
here. Thank you all for the review on this patch.

Regards

Em 10-12-2018 16:38, Tulio Magno Quites Machado Filho escreveu:
> "Gabriel F. T. Gomes" <gabriel@inconstante.eti.br> writes:
> 
>> On Fri, 07 Dec 2018, Gabriel F. T. Gomes wrote:
>>
>>> On Fri, 07 Dec 2018, Rogerio Alves wrote:
>>>
>>>> +/* This test is supported only on POWER 5 or higher.  */
>>>> +#define PPC_CPU_SUPPORTED (PPC_FEATURE_POWER5 | PPC_FEATURE_POWER5_PLUS | \
>>>> +                           PPC_FEATURE_ARCH_2_05 | PPC_FEATURE_ARCH_2_06 | \
>>>> +                           PPC_FEATURE2_ARCH_2_07)
>>>
>>> Is this actually needed?  Glibc has code to fill all the bits for older
>>> architectures in sysdeps/powerpc/hwcapinfo.c [1].  So, as far as I can
>>> see, you only need to test for AT_HWCAP & PPC_FEATURE_POWER5.
>>>
>>> [1] https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/powerpc/hwcapinfo.c;h=a09b18309324423d0cdf04e88367899a4396bab7;hb=HEAD#l47
>>
>> Hrm, that's only true for the hwcap info that is copied into the TCB, not
>> when accessing it with getauxval, so my comment is wrong (as Rogerio
>> kindly pointed out to me in a private message...  thanks).
>>
>> So, nevermind this comment.
>>
>>
>> On the other hand, on powerpc64 builds configured with --with-cpu set to
>> power4, power5, and power6, (but not to power8 or power7), I got the
>> following error message:
>>
>> ../sysdeps/powerpc/powerpc64/tst-ucontext-ppc64-vscr.c: In function ‘do_test’:
>> ../sysdeps/powerpc/powerpc64/tst-ucontext-ppc64-vscr.c:51:3: error: inconsistent operand constraints in an ‘asm’
>>     asm volatile ("vspltisb %0,0\n"
>>     ^~~
>>
>> I guess we didn't get this error message before, because of the
>> `#ifdef ARCH_PWR8' statement.  So, unless you know a better way to fix
>> this, you should reintroduce the `#ifdef' statement (now, you could use
>> ARCH_PWR7).
> 
> You can use:
> 
>      .machine push;
>      .machine "power7";
>      ...
>      .machine pop
> 
> It should be safe to use with the current minimum required Binutils i.e.
> support for POWER7 was already available in GNU Binutils 2.25 (even P8 was
> supported).
> 

Done. Using your suggestion fixed the issue thanks
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