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Message-ID: <Ynqciq2p8mtTg98n@arm.com>
Date: Tue, 10 May 2022 18:10:34 +0100
From: Catalin Marinas <catalin.marinas@....com>
To: Herbert Xu <herbert@...dor.apana.org.au>
Cc: Ard Biesheuvel <ardb@...nel.org>, Will Deacon <will@...nel.org>,
Marc Zyngier <maz@...nel.org>, Arnd Bergmann <arnd@...db.de>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Linux Memory Management List <linux-mm@...ck.org>,
Linux ARM <linux-arm-kernel@...ts.infradead.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
"David S. Miller" <davem@...emloft.net>,
Linux Crypto Mailing List <linux-crypto@...r.kernel.org>
Subject: Re: [RFC PATCH 2/7] crypto: api - Add crypto_tfm_ctx_dma
Hi Herbert,
Thanks for putting this together.
On Tue, May 10, 2022 at 07:07:10PM +0800, Herbert Xu wrote:
> diff --git a/include/crypto/algapi.h b/include/crypto/algapi.h
> index f50c5d1725da5..cdf12e51c53a0 100644
> --- a/include/crypto/algapi.h
> +++ b/include/crypto/algapi.h
> @@ -189,10 +189,34 @@ static inline void crypto_xor_cpy(u8 *dst, const u8 *src1, const u8 *src2,
> }
> }
>
> +static inline void *crypto_tfm_ctx(struct crypto_tfm *tfm)
> +{
> + return tfm->__crt_ctx;
> +}
> +
> +static inline void *crypto_tfm_ctx_align(struct crypto_tfm *tfm,
> + unsigned int align)
> +{
> + if (align <= crypto_tfm_ctx_alignment())
> + align = 1;
> +
> + return PTR_ALIGN(crypto_tfm_ctx(tfm), align);
> +}
> +
> static inline void *crypto_tfm_ctx_aligned(struct crypto_tfm *tfm)
> {
> - return PTR_ALIGN(crypto_tfm_ctx(tfm),
> - crypto_tfm_alg_alignmask(tfm) + 1);
> + return crypto_tfm_ctx_align(tfm, crypto_tfm_alg_alignmask(tfm) + 1);
> +}
> +
> +static inline void *crypto_tfm_ctx_dma(struct crypto_tfm *tfm)
> +{
> + unsigned int align = 1;
> +
> +#ifdef ARCH_DMA_MINALIGN
> + align = ARCH_DMA_MINALIGN;
> +#endif
> +
> + return crypto_tfm_ctx_align(tfm, align);
> }
Is there a case where a driver needs the minimum alignment between
ARCH_DMA_MINALIGN and crypto_tfm_alg_alignmask()+1? Maybe for platforms
where ARCH_DMA_MINALIGN is 8 (fully coherent) but the device's bus
master alignment requirements are higher.
My plan is to have ARCH_DMA_MINALIGN always defined but potentially
higher than ARCH_KMALLOC_MINALIGN on specific architectures. I think
crypto_tfm_ctx_dma() should use ARCH_KMALLOC_MINALIGN (and no #ifdefs)
until I get my patches sorted and I'll replace it with ARCH_DMA_MINALIGN
once it's defined globally (still no #ifdefs). Currently in mainline
it's ARCH_KMALLOC_MINALIGN that gives the static DMA alignment.
With the explicit crypto_tfm_ctx_dma(), can CRYPTO_MINALIGN_ATTR be
dropped entirely? This may be beneficial in reducing the structure size
when no DMA is required.
--
Catalin
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