[openssl-dev] [openssl.org #4162] [PATCH] Removing vrsave load and store

[Leonidas Da Silva Barbosa via RT]

On Tue, Dec 01, 2015 at 09:03:56AM +0000, Andy Polyakov via RT wrote:
> Hi,
> 
> Well, OpenSSL doesn't target exclusively post-ABI-update systems and the
> rationale for unconditional removal is questionable. I mean you say
> yourself "since update" and "our performance", but what about "prior
> update" and other OSes? Do *all*, i.e. even big-endian, Linux systems
> implement new ABI? AIX? MacOS X/PPC? 
Yes, I agree. We can only speak to Linux ABI V1/V2.

> Well, one can say the last one is
> dead, and even if it's not, modules in question [POWER8-specific] won't
> ever execute under it, but one before is not... IBM also pushes for
> POWER8 to be more open, so wouldn't it be more appropriate to keep
> options open? And why just POWER8-specific modules? I finally managed to
> find a copy of new specification and it classifies vrsave as reserved
> for system use. So that correct course of action is to make instructions
> reading/writing vrsave conditional, formulate the condition, and express
> it in code. I'd suggest to implement this in ppc-xlate. I.e. recognize
> 'mtspr 256,rA' and conditionally replace it with some kind of nop, e.g.
> or rA,rA,rA. 'mfspr rD,256' can be replaced with li rD,-1. This way one
> can affect all modules at once without having to examine each one of
> them. I can make suggestion a little bit later...
> 
I totally agree with your suggestions. I'll redo my patch according to
them.

Thanks a lot!