From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Subject: Re: [PATCHv2] arm: crypto: Add optimized SHA-256/224
Date: Tue, 24 Mar 2015 15:46:58 +0100
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Cc: Sami Tolvanen <samitolvanen@google.com>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	"David S. Miller" <davem@davemloft.net>
To: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>,
	Andy Polyakov <appro@openssl.org>
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Sender: linux-crypto-owner@vger.kernel.org

On 24 March 2015 at 14:06, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:
> On 24 March 2015 at 14:05, Jean-Christophe PLAGNIOL-VILLARD
> <plagnioj@jcrosoft.com> wrote:
>>  >> +     '&eor   ($t0,$t0,$a,"ror#".($Sigma0[2]-$Sigma0[0]))',   # Sigma0(a)
>>> >> +     '&add   ($h,$h,$t1)',                   # h+=Ch(e,f,g)
>>> >> +     '&ldr   ($t1,sprintf "[sp,#%d]",4*(($j+1)&15))  if (($j&15)!=15);'.
>>> >> +     '&ldr   ($t1,"[$Ktbl]")                         if ($j==15);'.
>>> >> +     '&ldr   ($t1,"[sp,#64]")                        if ($j==31)',
>>> >> +     '&and   ($t3,$t3,$t2)',                 # (b^c)&=(a^b)
>>> >> +     '&add   ($d,$d,$h)',                    # d+=h
>>> >> +     '&add   ($h,$h,$t0,"ror#$Sigma0[0]");'. # h+=Sigma0(a)
>>> >> +     '&eor   ($t3,$t3,$b)',                  # Maj(a,b,c)
>>> >> +     '$j++;  unshift(@V,pop(@V)); ($t2,$t3)=($t3,$t2);'
>>> >> +     )
>>> >> +}
>>> >> +
>>> >> +$code.=<<___;
>>> >> +#if __ARM_MAX_ARCH__>=7
>>> > this will be compile on armv4 but gcc will not allow it
>>> >
>>> > we need to drop the neon code for older non v7 build
>>> >
>>>
>>> The .arch and .fpu declarations ensure that it can be built regardless
>>> of the platform you are compiling for, unless you have a really old
>>> toolchain.
>> I known but does not work for me
>>> The glue code ensures that the module can only be loaded if HWCAP_NEON is set.
>>>
>>> Did you get errors trying to build it?
>>
>> yes I do
>>
>> I use
>>
>> arm-none-linux-gnueabi-gcc (Sourcery CodeBench Lite 2014.05-29) 4.8.3 20140320
>> (prerelease)
>> Copyright (C) 2013 Free Software Foundation, Inc.
>> This is free software; see the source for copying conditions.  There is NO
>> warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
>>
>> so it's not that old
>>
>
> Could you share the error log please?

OK, I spotted one issue with this code:

arch/arm/crypto/sha256-core.S: Assembler messages:
arch/arm/crypto/sha256-core.S:1847: Error: invalid constant (ffffefb0)
after fixup

This is caused by the fact that, when building the integer-only code
for an older architecture, the conditional compilation produces a
slightly bigger preceding function, and the symbol K256 is out of
range for the adr instruction.

@Jean-Christophe: is that the same problem that you hit?

@Andy: I propose we do something similar as in the bsaes code:

#ifdef __thumb__
#define adrl adr
#endif

and replace the offending line with

adrl r14,K256

@Herbert: we will need to respin this, so please don't pull it yet.

Regards,
-- 
Ard.