Re: [PATCH 07/10] crypto: Use ARCH_DMA_MINALIGN instead of ARCH_KMALLOC_MINALIGN

Herbert Xu
2022-04-07T11:41:41Z

On Thu, Apr 07, 2022 at 12:01:02PM +0100, Catalin Marinas wrote:
>
> The only issue is whether the compiler gets confused by a pointer to a
> structure with a smaller alignment than alignof(struct ...). I don't see
> a performance or correctness issue on arm64 here. It would be a problem
> if instead of 16 we went down to 8 or 4 due to unaligned accesses but
> from 128 to 64 (or even 16), I don't think it matters.

The issue is that there's code in the Crypto API which assumes
that all pointers returned by kmalloc are aligned to CRYPTO_MINALIGN,
if you break that then all that code would need to be modified.

However, I think it's better to change the code that assumes
CRYPTO_MINALIGN guarantees DMA alignment.

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