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Date: Mon, 19 Oct 2015 19:28:31 +0200
From: magnum <john.magnum@...hmail.com>
To: john-dev@...ts.openwall.com
Subject: Re: 64-bit rotate on AMD GCN

On 2015-10-19 18:52, Solar Designer wrote:
> On Fri, Oct 16, 2015 at 11:08:55AM +0300, Pavel Semjanov wrote:
>> #define sigma0_512(x)    (ROR((x),1)  ^ ROR((x),8)  ^ ((x)>>7))
>>                 T1 = X15=U64(0x220);
>>                  ...
>>                 s0 = sigma0_512(X15);
>>                  ...
>>
>> (Yes, it's SHA-512 ;)
>
> Maybe I've just managed to reproduce this.  It turns out that our
> pbkdf2-hmac-sha512-opencl was failing on AMD GPUs (but working fine on
> NVIDIA).  I didn't notice when playing with ror() before because I was
> focusing on sha512crypt-opencl (which worked fine on all of the GPUs).
>
> Changing this line in opencl_sha2.h:
>
> #define sigma0_64(x) ((ror64(x,1))  ^ (ror64(x,8)) ^ (x >> 7))
>
> to:
>
> #define sigma0_64(x) ((ror64(x,1))  ^ (rotate(x,56UL)) ^ (x >> 7))
>
> makes the problem go away for Tahiti (but the speed is poor, at about
> 1/4 of Titan X, unlike for sha512crypt where these GPUs are similar).
> Juniper is still failing (could be a different problem; I haven't looked
> into that).
> (...)
> magnum - would you take this problem from here?

I tested this format specifically. Maybe that was on 15.9? I'll open an 
issue and investigate.

magnum

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