Re: [PATCH] crypto: arm: workaround for building with old binutils

[Herbert Xu <herbert@gondor.apana.org.au>]

On Sat, Apr 11, 2015 at 03:32:34PM +0200, Ard Biesheuvel wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> How about something like this:
> 
> A warning will be emitted by make when descending into the arch/arm/crypto
> directory, but only if any ARMv8 Crypto modules were in fact selected.
> 
> /home/ard/linux-2.6/arch/arm/crypto/Makefile:22: These ARMv8 Crypto Extensions modules need binutils 2.23 or higher
> /home/ard/linux-2.6/arch/arm/crypto/Makefile:23: aes-arm-ce.o sha1-arm-ce.o sha2-arm-ce.o ghash-arm-ce.o
> 
> 
> ----------------->8------------------
> Old versions of binutils (before 2.23) do not yet understand the
> crypto-neon-fp-armv8 fpu instructions, and an attempt to build these
> files results in a build failure:
> 
> arch/arm/crypto/aes-ce-core.S:133: Error: selected processor does not support ARM mode `vld1.8 {q10-q11},[ip]!'
> arch/arm/crypto/aes-ce-core.S:133: Error: bad instruction `aese.8 q0,q8'
> arch/arm/crypto/aes-ce-core.S:133: Error: bad instruction `aesmc.8 q0,q0'
> arch/arm/crypto/aes-ce-core.S:133: Error: bad instruction `aese.8 q0,q9'
> arch/arm/crypto/aes-ce-core.S:133: Error: bad instruction `aesmc.8 q0,q0'
> 
> Since the affected versions are still in widespread use, and this breaks
> 'allmodconfig' builds, we should try to at least get a successful kernel
> build. Unfortunately, I could not come up with a way to make the Kconfig
> symbol depend on the binutils version, which would be the nicest solution.
> 
> Instead, this patch uses the 'as-instr' Kbuild macro to find out whether
> the support is present in the assembler, and otherwise emits a non-fatal
> warning indicating which selected modules could not be built.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Link: http://storage.kernelci.org/next/next-20150410/arm-allmodconfig/build.log
> Fixes: 864cbeed4ab22d ("crypto: arm - add support for SHA1 using ARMv8 Crypto Instructions")
> [ard.biesheuvel:
>  - omit modules entirely instead of building empty ones if binutils is too old
>  - update commit log accordingly]
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

Patch applied.
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
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