[PATCH v2] powerpc: select ARCH_HAS_MEMBARRIER_SYNC_CORE

[Nicholas Piggin]

Excerpts from Andreas Schwab's message of July 15, 2020 8:08 pm:
> On Jul 15 2020, Nicholas Piggin wrote:
> 
>> diff --git a/arch/powerpc/include/asm/exception-64e.h b/arch/powerpc/include/asm/exception-64e.h
>> index 54a98ef7d7fe..071d7ccb830f 100644
>> --- a/arch/powerpc/include/asm/exception-64e.h
>> +++ b/arch/powerpc/include/asm/exception-64e.h
>> @@ -204,7 +204,11 @@ exc_##label##_book3e:
>>  	LOAD_REG_ADDR(r3,interrupt_base_book3e);\
>>  	ori	r3,r3,vector_offset at l;		\
>>  	mtspr	SPRN_IVOR##vector_number,r3;
>> -
>> +/*
>> + * powerpc relies on return from interrupt/syscall being context synchronising
>> + * (which rfi is) to support ARCH_HAS_MEMBARRIER_SYNC_CORE without additional
>> + * additional synchronisation instructions.
> 
> s/additonal//

Will fix in a respin.

Thanks,
Nick