Re: [PATCH v2] perf test amd ibs: avoid using executable heap

[Ravi Bangoria]

>>>> permission under SELinux (things like JIT or regex compilation need it
>>>> as well). mmap() with MAP_ANONYMOUS will give us a zeroed mapping that
>>>> begins on a page boundary, so the result is equivalent to the original
>>>> code even without a memset() or the page-alignment dance.
>>>
>>> I would argue that having RWX is a problem, you really want RW->RO->RX
>>> transitions, so even with mmap() you want to combine with mprotect().
>>
>> My original intent for using RWX was to generate sufficient Icache miss
>> samples for the IBS Fetch unit by overwriting the code prior to execution.
>> I am wondering whether it would be possible to achieve the same result
>> by using CLFLUSH with RX permissions. Something like below (build tested
>> only).
> 
> So for a test it is fine to have RWX

Sure, makes sense.

Thanks,
Ravi