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Date:   Mon, 18 Apr 2022 16:37:17 +0800
From:   Herbert Xu <herbert@gondor.apana.org.au>
To:     Catalin Marinas <catalin.marinas@arm.com>
Cc:     Ard Biesheuvel <ardb@kernel.org>, Will Deacon <will@kernel.org>,
        Marc Zyngier <maz@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Linux Memory Management List <linux-mm@kvack.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        "David S. Miller" <davem@davemloft.net>
Subject: Re: [PATCH 07/10] crypto: Use ARCH_DMA_MINALIGN instead of
 ARCH_KMALLOC_MINALIGN
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On Sun, Apr 17, 2022 at 05:30:27PM +0100, Catalin Marinas wrote:
>
> Do you mean as per Ard's proposal here:
> 
> https://lore.kernel.org/r/CAMj1kXH0x5Va7Wgs+mU1ONDwwsazOBuN4z4ihVzO2uG-n41Kbg@mail.gmail.com
> 
> struct crypto_request {
> 	union {
> 		struct {
> 			... fields ...
> 		};
> 		u8 __padding[ARCH_DMA_MINALIGN];
> 	};
> 	void __ctx[]  __aligned(CRYPTO_MINALIGN);
> };
> 
> If CRYPTO_MINALIGN is lowered to, say, 8 (to be the same as lowest
> ARCH_KMALLOC_MINALIGN), the __alignof__(req->__ctx) would be 8.
> Functions like crypto_tfm_ctx_alignment() will return 8 when what you
> need is 128. We can change those functions to return ARCH_DMA_MINALIGN
> instead or always bump cra_alignmask to ARCH_DMA_MINALIGN-1.

OK, at this point I think we need to let the code do the talking :)

I've seen Ard's patches already and I think I understand what your
needs are.  So let me whip up some code to show you guys what I
think needs to be done.

Please bear with me for a few days.

Thanks,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt