Re: [PATCH] x86, crypto: Check if gas supports CRC32

From: Mathias Krause
Date: Thu Jul 31 2014 - 01:57:31 EST

On 31 July 2014 00:11, Borislav Petkov <bp@xxxxxxxxx> wrote:
> On Wed, Jul 30, 2014 at 11:28:14PM +0200, Mathias Krause wrote:
> > Gah, CONFIG_AS_CRC32 gets defined as a preprocessor symbol only so
> > cannot be used in makefiles. So crc32c-pcl-intel-asm_64.S needs a
> > "#ifdef CONFIG_AS_CRC32" guard and still be compiled for CONFIG_64BIT,
> > as it is now. It'll be an empty object for older binutils versions not
> > supporting the crc32 instruction.
> Yeah, that makes it all even simpler, thanks!
> We're still b0rked though:
> arch/x86/crypto/crct10dif-pcl-asm_64.S: Assembler messages:
> arch/x86/crypto/crct10dif-pcl-asm_64.S:147: Error: no such instruction: `pclmulqdq $0x0,%xmm10,%xmm0'
> arch/x86/crypto/crct10dif-pcl-asm_64.S:148: Error: no such instruction: `pclmulqdq $0x11,%xmm10,%xmm8'
> arch/x86/crypto/crct10dif-pcl-asm_64.S:149: Error: no such instruction: `pclmulqdq $0x0,%xmm10,%xmm1'
> ...
> and need checking for more instructions. I'll play with this more
> tomorrow.

You probably can reuse the AVX test for this -- either the
CONFIG_AS_AVX preprocessor one or the $(avx_supported) make one, local
to arch/x86/crypto/Makefile.
Even though the CLMUL feature has not much to with AVX (it has a
dedicated CPUID feature bit), support for it in binutils was added
together with AVX support, see;a=commit;h=c0f3af977b0f28a0dc5a620110b8dcf9d8286f84


> Good night :-)
> --
> Regards/Gruss,
> Boris.
> Sent from a fat crate under my desk. Formatting is fine.
> --
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