linux-kernel - Re: [PATCH] crypto: Zhaoxin: Hardware Engine Driver for SHA1/256/384/512

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Date:   Thu, 3 Aug 2023 09:49:02 +0800
From:   Tony W Wang-oc <TonyWWang-oc@...oxin.com>
To:     Dave Hansen <dave.hansen@...el.com>, <tglx@...utronix.de>,
        <mingo@...hat.com>, <bp@...en8.de>, <dave.hansen@...ux.intel.com>,
        <hpa@...or.com>, <x86@...nel.org>, <linux-kernel@...r.kernel.org>,
        <herbert@...dor.apana.org.au>, <davem@...emloft.net>,
        <seanjc@...gle.com>, <kim.phillips@....com>,
        <peterz@...radead.org>, <pbonzini@...hat.com>,
        <pawan.kumar.gupta@...ux.intel.com>, <babu.moger@....com>,
        <jiaxi.chen@...ux.intel.com>, <jmattson@...gle.com>,
        <sandipan.das@....com>, <linux-crypto@...r.kernel.org>
CC:     <CobeChen@...oxin.com>, <TimGuo@...oxin.com>,
        <LeoLiu-oc@...oxin.com>, <GeorgeXue@...oxin.com>
Subject: Re: [PATCH] crypto: Zhaoxin: Hardware Engine Driver for
 SHA1/256/384/512

Dear Dave,
Thanks for your review. will refactor this patch per your suggestions.

On 8/2/23 22:20, Dave Hansen wrote:
> This code looks pretty rough.
> 
>> +static int zhaoxin_sha1_update(struct shash_desc *desc,
>> +			const u8 *data,	unsigned int len)
>> +{
>> +	struct sha1_state *sctx = shash_desc_ctx(desc);
>> +	unsigned int partial, done;
>> +	const u8 *src;
>> +	/*The PHE require the out buffer must 128 bytes and 16-bytes aligned*/
>> +	u8 buf[128 + ZHAOXIN_SHA_ALIGNMENT - STACK_ALIGN] __attribute__
>> +		((aligned(STACK_ALIGN)));
>> +	u8 *dst = PTR_ALIGN(&buf[0], ZHAOXIN_SHA_ALIGNMENT);
> 
> All of the different alignments here are pretty dazzling.
> 
>> +	partial = sctx->count & 0x3f;
> 
> "0x3f" is a random magic number.
> 
>> +	sctx->count += len;
>> +	done = 0;
>> +	src = data;
>> +	memcpy(dst, (u8 *)(sctx->state), SHA1_DIGEST_SIZE);
>> +
>> +	if ((partial + len) >= SHA1_BLOCK_SIZE) {
>> +
>> +		/* Append the bytes in state's buffer to a block to handle */
>> +		if (partial) {
>> +			done = -partial;
>> +			memcpy(sctx->buffer + partial, data,
>> +				done + SHA1_BLOCK_SIZE);
>> +			src = sctx->buffer;
>> +			asm volatile (".byte 0xf3,0x0f,0xa6,0xc8"
>> +			: "+S"(src), "+D"(dst)
>> +			: "a"((long)-1), "c"(1UL));
> 
> Please look around the codebase for examples on how to do this.  We
> usually try to use real instructions when binutils supports them and
> also don't repeatedly open-code the ".byte ...".
> 
>> +			done += SHA1_BLOCK_SIZE;
>> +			src = data + done;
>> +		}
>> +
>> +		/* Process the left bytes from the input data */
>> +		if (len - done >= SHA1_BLOCK_SIZE) {
>> +			asm volatile (".byte 0xf3,0x0f,0xa6,0xc8"
>> +			: "+S"(src), "+D"(dst)
>> +			: "a"((long)-1),
>> +			"c"((unsigned long)((len - done) / SHA1_BLOCK_SIZE)));
>> +			done += ((len - done) - (len - done) % SHA1_BLOCK_SIZE);
>> +			src = data + done;
>> +		}
>> +		partial = 0;
>> +	}
>> +	memcpy((u8 *)(sctx->state), dst, SHA1_DIGEST_SIZE);
> 
> What's the purpose of the cast?
> 
>> +	memcpy(sctx->buffer + partial, src, len - done);
>> +
>> +	return 0;
>> +}
>> +
>> +static int zhaoxin_sha1_final(struct shash_desc *desc, u8 *out)
>> +{
>> +	struct sha1_state *state = (struct sha1_state *)shash_desc_ctx(desc);
> 
> What's the purpose of *this* cast?
> 
>> +	unsigned int partial, padlen;
>> +	__be64 bits;
>> +	static const u8 padding[64] = { 0x80, };
>> +
>> +	bits = cpu_to_be64(state->count << 3);
>> +
>> +	/* Pad out to 56 mod 64 */
>> +	partial = state->count & 0x3f;
>> +	padlen = (partial < 56) ? (56 - partial) : ((64+56) - partial);
>> +	zhaoxin_sha1_update(desc, padding, padlen);
>> +
>> +	/* Append length field bytes */
>> +	zhaoxin_sha1_update(desc, (const u8 *)&bits, sizeof(bits));
>> +
>> +	/* Swap to output */
>> +	zhaoxin_output_block((uint32_t *)(state->state), (uint32_t *)out, 5);
>> +
>> +	return 0;
>> +}
>> +
>> +static int zhaoxin_sha256_init(struct shash_desc *desc)
>> +{
>> +	struct sha256_state *sctx = shash_desc_ctx(desc);
>> +
>> +	*sctx = (struct sha256_state){
>> +		.state = { SHA256_H0, SHA256_H1, SHA256_H2, SHA256_H3,
>> +				SHA256_H4, SHA256_H5, SHA256_H6, SHA256_H7},
>> +	};
>> +
>> +	return 0;
>> +}
>> +
>> +static int zhaoxin_sha256_update(struct shash_desc *desc, const u8 *data,
>> +			  unsigned int len)
>> +{
>> +	struct sha256_state *sctx = shash_desc_ctx(desc);
>> +	unsigned int partial, done;
>> +	const u8 *src;
>> +	/*The PHE require the out buffer must 128 bytes and 16-bytes aligned*/
>> +	u8 buf[128 + ZHAOXIN_SHA_ALIGNMENT - STACK_ALIGN] __attribute__
>> +		((aligned(STACK_ALIGN)));
>> +	u8 *dst = PTR_ALIGN(&buf[0], ZHAOXIN_SHA_ALIGNMENT);
>> +
>> +	partial = sctx->count & 0x3f;
>> +	sctx->count += len;
>> +	done = 0;
>> +	src = data;
>> +	memcpy(dst, (u8 *)(sctx->state), SHA256_DIGEST_SIZE);
> 
> That looks familiar.
> 
> This patch needs some serious cleanups and refactoring.  It seems to be
> missing even the basics like avoiding copy-and-pasting code.  The
> changelog is quite sparse.
> 
> Could you spend some more time on this and give it another go, please?