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Date:   Thu, 10 Mar 2022 18:36:47 +0000
From:   Eric Biggers <ebiggers@kernel.org>
To:     Keith Busch <kbusch@kernel.org>
Cc:     Vasily Gorbik <gor@linux.ibm.com>, linux-nvme@lists.infradead.org,
        linux-block@vger.kernel.org, linux-crypto@vger.kernel.org,
        linux-kernel@vger.kernel.org, axboe@kernel.dk, hch@lst.de,
        martin.petersen@oracle.com,
        Herbert Xu <herbert@gondor.apana.org.au>
Subject: Re: [PATCHv4 6/8] crypto: add rocksoft 64b crc guard tag framework
Message-ID: <YipFP8B8MxMxTVBR@gmail.com>
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On Thu, Mar 10, 2022 at 07:39:59AM -0800, Keith Busch wrote:
> On Wed, Mar 09, 2022 at 07:49:07PM +0000, Eric Biggers wrote:
> > The issue is that every other "shash" algorithm besides crct10dif, including
> > crc32 and crc32c, follow the convention of treating the digest as bytes.  Doing
> > otherwise is unusual for the crypto API.  So I have a slight preference for
> > treating it as bytes.  Perhaps see what Herbert Xu (maintainer of the crypto
> > API, Cc'ed) recommends?
> 
> I'm okay either way, they're both simple enough. Here is an update atop
> this series to match the other shash conventions if this is preferred
> over my?previous fix:
> 
> ---
> diff --git a/block/t10-pi.c b/block/t10-pi.c
> index 914d8cddd43a..f9eb45571bc7 100644
> --- a/block/t10-pi.c
> +++ b/block/t10-pi.c
> @@ -282,7 +282,7 @@ EXPORT_SYMBOL(t10_pi_type3_ip);
>  
>  static __be64 ext_pi_crc64(void *data, unsigned int len)
>  {
> -	return cpu_to_be64(crc64_rocksoft(data, len));
> +	return cpu_to_be64(le64_to_cpu(crc64_rocksoft(data, len)));
>  }
>  
>  static blk_status_t ext_pi_crc64_generate(struct blk_integrity_iter *iter,
> diff --git a/crypto/testmgr.h b/crypto/testmgr.h
> index f1a22794c404..f9e5f601c657 100644
> --- a/crypto/testmgr.h
> +++ b/crypto/testmgr.h
> @@ -3686,11 +3686,11 @@ static const struct hash_testvec crc64_rocksoft_tv_template[] = {
>  	{
>  		.plaintext	= zeroes,
>  		.psize		= 4096,
> -		.digest		= (u8 *)(u64[]){ 0x6482d367eb22b64eull },
> +		.digest		= "\x4e\xb6\x22\xeb\x67\xd3\x82\x64",
>  	}, {
>  		.plaintext	= ones,
>  		.psize		= 4096,
> -		.digest		= (u8 *)(u64[]){ 0xc0ddba7302eca3acull },
> +		.digest		= "\xac\xa3\xec\x02\x73\xba\xdd\xc0",
>  	}
>  };
>  
> diff --git a/include/linux/crc64.h b/include/linux/crc64.h
> index e044c60d1e61..5319f9a9fc19 100644
> --- a/include/linux/crc64.h
> +++ b/include/linux/crc64.h
> @@ -12,7 +12,7 @@
>  u64 __pure crc64_be(u64 crc, const void *p, size_t len);
>  u64 __pure crc64_rocksoft_generic(u64 crc, const void *p, size_t len);
>  
> -u64 crc64_rocksoft(const unsigned char *buffer, size_t len);
> -u64 crc64_rocksoft_update(u64 crc, const unsigned char *buffer, size_t len);
> +__le64 crc64_rocksoft(const unsigned char *buffer, size_t len);
> +__le64 crc64_rocksoft_update(u64 crc, const unsigned char *buffer, size_t len);
>  
>  #endif /* _LINUX_CRC64_H */
> diff --git a/lib/crc64-rocksoft.c b/lib/crc64-rocksoft.c
> index fc9ae0da5df7..215acb79a15d 100644
> --- a/lib/crc64-rocksoft.c
> +++ b/lib/crc64-rocksoft.c
> @@ -54,16 +54,16 @@ static struct notifier_block crc64_rocksoft_nb = {
>  	.notifier_call = crc64_rocksoft_notify,
>  };
>  
> -u64 crc64_rocksoft_update(u64 crc, const unsigned char *buffer, size_t len)
> +__le64 crc64_rocksoft_update(u64 crc, const unsigned char *buffer, size_t len)
>  {
>  	struct {
>  		struct shash_desc shash;
> -		u64 crc;
> +		__le64 crc;
>  	} desc;
>  	int err;
>  
>  	if (static_branch_unlikely(&crc64_rocksoft_fallback))
> -		return crc64_rocksoft_generic(crc, buffer, len);
> +		return cpu_to_le64(crc64_rocksoft_generic(crc, buffer, len));
>  
>  	rcu_read_lock();
>  	desc.shash.tfm = rcu_dereference(crc64_rocksoft_tfm);
> @@ -77,7 +77,7 @@ u64 crc64_rocksoft_update(u64 crc, const unsigned char *buffer, size_t len)
>  }
>  EXPORT_SYMBOL_GPL(crc64_rocksoft_update);
>  
> -u64 crc64_rocksoft(const unsigned char *buffer, size_t len)
> +__le64 crc64_rocksoft(const unsigned char *buffer, size_t len)
>  {
>  	return crc64_rocksoft_update(0, buffer, len);
>  }
> --

I think the lib functions should still use native endianness, like what crc32
does.

- Eric