Re: [PATCH v6 4/4] crypto: Add Allwinner Security System crypto accelerator

[Corentin LABBE <clabbe.montjoie-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Le 26/03/2015 19:31, Boris Brezillon a écrit :
> Hi Corentin,
> 
> Here is a quick review, there surely are a lot of other things I didn't
> spot.
> 
> On Mon, 16 Mar 2015 20:01:22 +0100
> LABBE Corentin <clabbe.montjoie-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> 
>> Add support for the Security System included in Allwinner SoC A20.
>> The Security System is a hardware cryptographic accelerator that support:
>> - MD5 and SHA1 hash algorithms
>> - AES block cipher in CBC mode with 128/196/256bits keys.
>> - DES and 3DES block cipher in CBC mode
>>
>> Signed-off-by: LABBE Corentin <clabbe.montjoie-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>> ---
> 
> [...]
> 
>> +static int sunxi_ss_cipher(struct ablkcipher_request *areq, u32 mode)
>> +{
>> +	struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(areq);
>> +	struct sunxi_tfm_ctx *op = crypto_ablkcipher_ctx(tfm);
>> +	const char *cipher_type;
>> +	struct sunxi_ss_ctx *ss = op->ss;
>> +
>> +	if (areq->nbytes == 0)
>> +		return 0;
>> +
>> +	if (areq->info == NULL) {
>> +		dev_err(ss->dev, "ERROR: Empty IV\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	if (areq->src == NULL || areq->dst == NULL) {
>> +		dev_err(ss->dev, "ERROR: Some SGs are NULL\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	cipher_type = crypto_tfm_alg_name(crypto_ablkcipher_tfm(tfm));
>> +
>> +	if (strcmp("cbc(aes)", cipher_type) == 0) {
>> +		mode |= SS_OP_AES | SS_CBC | SS_ENABLED | op->keymode;
>> +		return sunxi_ss_aes_poll(areq, mode);
>> +	}
>> +
>> +	if (strcmp("cbc(des)", cipher_type) == 0) {
>> +		mode |= SS_OP_DES | SS_CBC | SS_ENABLED | op->keymode;
>> +		return sunxi_ss_des_poll(areq, mode);
>> +	}
>> +
>> +	if (strcmp("cbc(des3_ede)", cipher_type) == 0) {
>> +		mode |= SS_OP_3DES | SS_CBC | SS_ENABLED | op->keymode;
>> +		return sunxi_ss_des_poll(areq, mode);
>> +	}
> 
> Hm, I'm not sure doing these string comparisons in the crypto operation
> path is a good idea.
> Moreover, you're doing 3 string comparisons, even though only one can
> be valid at a time (using 'else if' would have been a bit better).
> 
> Anyway, IMHO this function should be split into 3 functions, and
> referenced by your alg template definitions.
> Something like:
> 
> int sunxi_ss_xxx_encrypt(struct ablkcipher_request *areq)
> {
> 	/* put your cipher specific intialization here */
> 
> 	return sunxi_ss_xxx_poll(areq, SS_ENCRYPTION);
> }
> 
> int sunxi_ss_xxx_decrypt(struct ablkcipher_request *areq)
> {
> 	/* put your cipher specific intialization here */
> 
> 	return sunxi_ss_xxx_poll(areq, SS_DECRYPTION);
> }
> 

You are right, I have added more block mode, and that was added too much strcmp.
So splitting in simplier functions is good.

> 
>> +
>> +int sunxi_ss_cipher_init(struct crypto_tfm *tfm)
>> +{
>> +	const char *name = crypto_tfm_alg_name(tfm);
>> +	struct sunxi_tfm_ctx *op = crypto_tfm_ctx(tfm);
>> +	struct crypto_alg *alg = tfm->__crt_alg;
>> +	struct sunxi_ss_alg_template *algt;
>> +	struct sunxi_ss_ctx *ss;
>> +
>> +	memset(op, 0, sizeof(struct sunxi_tfm_ctx));
>> +
>> +	algt = container_of(alg, struct sunxi_ss_alg_template, alg.crypto);
>> +	ss = algt->ss;
>> +	op->ss = algt->ss;
>> +
>> +	/* fallback is needed only for DES/3DES */
>> +	if (strcmp("cbc(des)", name) == 0 ||
>> +			strcmp("cbc(des3_ede)", name) == 0) {
>> +		op->fallback = crypto_alloc_ablkcipher(name, 0,
>> +				CRYPTO_ALG_ASYNC | CRYPTO_ALG_NEED_FALLBACK);
>> +		if (IS_ERR(op->fallback)) {
>> +			dev_err(ss->dev, "ERROR: allocating fallback algo %s\n",
>> +					name);
>> +			return PTR_ERR(op->fallback);
>> +		}
>> +	}
> 
> Ditto: just create a specific init function for the des case:
> 
> int sunxi_ss_cbc_des_init(struct crypto_tfm *tfm)
> {
> 	sunxi_ss_cipher_init(tfm);
> 
> 	op->fallback = crypto_alloc_ablkcipher(name, 0,
> 				CRYPTO_ALG_ASYNC |
> 				CRYPTO_ALG_NEED_FALLBACK);
> 	if (IS_ERR(op->fallback)) {
> 		dev_err(ss->dev, "ERROR: allocating fallback algo %s\n",
> 			name);
> 		return PTR_ERR(op->fallback);
> 	}
> 
> 	return 0;
> }
> 

Ok

> 
> [..]
> 
>> +/*
>> + * Optimized function for the case where we have only one SG,
>> + * so we can use kmap_atomic
>> + */
>> +static int sunxi_ss_aes_poll_atomic(struct ablkcipher_request *areq)
>> +{
>> +	u32 spaces;
>> +	struct scatterlist *in_sg = areq->src;
>> +	struct scatterlist *out_sg = areq->dst;
>> +	void *src_addr;
>> +	void *dst_addr;
>> +	unsigned int ileft = areq->nbytes;
>> +	unsigned int oleft = areq->nbytes;
>> +	unsigned int todo;
>> +	u32 *src32;
>> +	u32 *dst32;
>> +	u32 rx_cnt = 32;
>> +	u32 tx_cnt = 0;
>> +	int i;
>> +	struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(areq);
>> +	struct sunxi_tfm_ctx *op = crypto_ablkcipher_ctx(tfm);
>> +	struct sunxi_ss_ctx *ss = op->ss;
>> +
>> +	src_addr = kmap_atomic(sg_page(in_sg)) + in_sg->offset;
>> +	if (src_addr == NULL) {
>> +		dev_err(ss->dev, "kmap_atomic error for src SG\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	dst_addr = kmap_atomic(sg_page(out_sg)) + out_sg->offset;
>> +	if (dst_addr == NULL) {
>> +		dev_err(ss->dev, "kmap_atomic error for dst SG\n");
>> +		kunmap_atomic(src_addr);
>> +		return -EINVAL;
>> +	}
>> +
>> +	src32 = (u32 *)src_addr;
>> +	dst32 = (u32 *)dst_addr;
>> +	ileft = areq->nbytes / 4;
>> +	oleft = areq->nbytes / 4;
>> +	i = 0;
>> +	do {
>> +		if (ileft > 0 && rx_cnt > 0) {
>> +			todo = min(rx_cnt, ileft);
>> +			ileft -= todo;
>> +			writesl(ss->base + SS_RXFIFO, src32, todo);
>> +			src32 += todo;
>> +		}
>> +		if (tx_cnt > 0) {
>> +			todo = min(tx_cnt, oleft);
>> +			oleft -= todo;
>> +			readsl(ss->base + SS_TXFIFO, dst32, todo);
>> +			dst32 += todo;
>> +		}
>> +		spaces = readl(ss->base + SS_FCSR);
>> +		rx_cnt = SS_RXFIFO_SPACES(spaces);
>> +		tx_cnt = SS_TXFIFO_SPACES(spaces);
>> +	} while (oleft > 0);
>> +	kunmap_atomic(dst_addr);
>> +	kunmap_atomic(src_addr);
>> +	return 0;
>> +}
>> +
>> +int sunxi_ss_aes_poll(struct ablkcipher_request *areq, u32 mode)
>> +{
>> +	u32 spaces;
>> +	struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(areq);
>> +	struct sunxi_tfm_ctx *op = crypto_ablkcipher_ctx(tfm);
>> +	struct sunxi_ss_ctx *ss = op->ss;
>> +	unsigned int ivsize = crypto_ablkcipher_ivsize(tfm);
>> +	/* when activating SS, the default FIFO space is 32 */
>> +	u32 rx_cnt = 32;
>> +	u32 tx_cnt = 0;
>> +	u32 v;
>> +	int i, err = 0;
>> +	struct scatterlist *in_sg = areq->src;
>> +	struct scatterlist *out_sg = areq->dst;
>> +	void *src_addr;
>> +	void *dst_addr;
>> +	unsigned int ileft = areq->nbytes;
>> +	unsigned int oleft = areq->nbytes;
>> +	unsigned int sgileft = areq->src->length;
>> +	unsigned int sgoleft = areq->dst->length;
>> +	unsigned int todo;
>> +	u32 *src32;
>> +	u32 *dst32;
>> +	unsigned long flags;
>> +
>> +	spin_lock_irqsave(&ss->slock, flags);
>> +
>> +	for (i = 0; i < op->keylen; i += 4)
>> +		writel(*(op->key + i/4), ss->base + SS_KEY0 + i);
>> +
>> +	if (areq->info != NULL) {
>> +		for (i = 0; i < 4 && i < ivsize / 4; i++) {
>> +			v = *(u32 *)(areq->info + i * 4);
>> +			writel(v, ss->base + SS_IV0 + i * 4);
>> +		}
>> +	}
>> +	writel(mode, ss->base + SS_CTL);
>> +
>> +	/* If we have only one SG, we can use kmap_atomic */
>> +	if (sg_next(in_sg) == NULL && sg_next(out_sg) == NULL) {
>> +		err = sunxi_ss_aes_poll_atomic(areq);
>> +		goto release_ss;
>> +	}
>> +
>> +	/*
>> +	 * If we have more than one SG, we cannot use kmap_atomic since
>> +	 * we hold the mapping too long
>> +	 */
>> +	src_addr = kmap(sg_page(in_sg)) + in_sg->offset;
>> +	if (src_addr == NULL) {
>> +		dev_err(ss->dev, "KMAP error for src SG\n");
>> +		err = -EINVAL;
>> +		goto release_ss;
>> +	}
>> +	dst_addr = kmap(sg_page(out_sg)) + out_sg->offset;
>> +	if (dst_addr == NULL) {
>> +		kunmap(sg_page(in_sg));
>> +		dev_err(ss->dev, "KMAP error for dst SG\n");
>> +		err = -EINVAL;
>> +		goto release_ss;
>> +	}
>> +	src32 = (u32 *)src_addr;
>> +	dst32 = (u32 *)dst_addr;
>> +	ileft = areq->nbytes / 4;
>> +	oleft = areq->nbytes / 4;
>> +	sgileft = in_sg->length / 4;
>> +	sgoleft = out_sg->length / 4;
>> +	do {
>> +		spaces = readl_relaxed(ss->base + SS_FCSR);
>> +		rx_cnt = SS_RXFIFO_SPACES(spaces);
>> +		tx_cnt = SS_TXFIFO_SPACES(spaces);
>> +		todo = min3(rx_cnt, ileft, sgileft);
>> +		if (todo > 0) {
>> +			ileft -= todo;
>> +			sgileft -= todo;
>> +			writesl(ss->base + SS_RXFIFO, src32, todo);
>> +			src32 += todo;
>> +		}
>> +		if (in_sg != NULL && sgileft == 0 && ileft > 0) {
>> +			kunmap(sg_page(in_sg));
>> +			in_sg = sg_next(in_sg);
>> +			while (in_sg != NULL && in_sg->length == 0)
>> +				in_sg = sg_next(in_sg);
>> +			if (in_sg != NULL && ileft > 0) {
>> +				src_addr = kmap(sg_page(in_sg)) + in_sg->offset;
>> +				if (src_addr == NULL) {
>> +					dev_err(ss->dev, "ERROR: KMAP for src SG\n");
>> +					err = -EINVAL;
>> +					goto release_ss;
>> +				}
>> +				src32 = src_addr;
>> +				sgileft = in_sg->length / 4;
>> +			}
>> +		}
>> +		/* do not test oleft since when oleft == 0 we have finished */
>> +		todo = min3(tx_cnt, oleft, sgoleft);
>> +		if (todo > 0) {
>> +			oleft -= todo;
>> +			sgoleft -= todo;
>> +			readsl(ss->base + SS_TXFIFO, dst32, todo);
>> +			dst32 += todo;
>> +		}
>> +		if (out_sg != NULL && sgoleft == 0 && oleft >= 0) {
>> +			kunmap(sg_page(out_sg));
>> +			out_sg = sg_next(out_sg);
>> +			while (out_sg != NULL && out_sg->length == 0)
>> +				out_sg = sg_next(out_sg);
>> +			if (out_sg != NULL && oleft > 0) {
>> +				dst_addr = kmap(sg_page(out_sg)) +
>> +					out_sg->offset;
>> +				if (dst_addr == NULL) {
>> +					dev_err(ss->dev, "KMAP error\n");
>> +					err = -EINVAL;
>> +					goto release_ss;
>> +				}
>> +				dst32 = dst_addr;
>> +				sgoleft = out_sg->length / 4;
>> +			}
>> +		}
>> +	} while (oleft > 0);
>> +
>> +release_ss:
>> +	writel_relaxed(0, ss->base + SS_CTL);
>> +	spin_unlock_irqrestore(&ss->slock, flags);
>> +	return err;
>> +}
> 
> Do you really need to have both an "optimized" and "non-optimized"
> function ?
> 
> BTW, you should take a look at the sg_copy_buffer function [1], which
> is doing pretty much what you're doing here.
> If you don't want to directly use sg_copy_buffer, you should at least
> use the sg_miter_xxx function to iterate over you're sg list (it's
> taking care of calling kmap or kmap_atomic depending on the
> SG_MITER_ATOMIC flag).
> 

I have dropped sg_copy_buffer that I used for DES/3DES some times ago for handling SG with length not multiple of 4.
And using sg_miter is not usefull.
It could be usefull for DES/3DEs for non 4 bytes multiple SG, but I use a fallback for that case.

>> +
>> +/* Pure CPU driven way of doing DES/3DES with SS */
>> +int sunxi_ss_des_poll(struct ablkcipher_request *areq, u32 mode)
>> +{
>> +	struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(areq);
>> +	struct sunxi_tfm_ctx *op = crypto_ablkcipher_ctx(tfm);
>> +	struct sunxi_ss_ctx *ss = op->ss;
>> +	int i, err = 0;
>> +	int no_chunk = 1;
>> +	struct scatterlist *in_sg = areq->src;
>> +	struct scatterlist *out_sg = areq->dst;
>> +	u8 kkey[256 / 8];
>> +
>> +	/*
>> +	 * if we have only SGs with size multiple of 4,
>> +	 * we can use the SS AES function
>> +	 */
>> +	while (in_sg != NULL && no_chunk == 1) {
>> +		if ((in_sg->length % 4) != 0)
>> +			no_chunk = 0;
>> +		in_sg = sg_next(in_sg);
>> +	}
>> +	while (out_sg != NULL && no_chunk == 1) {
>> +		if ((out_sg->length % 4) != 0)
>> +			no_chunk = 0;
>> +		out_sg = sg_next(out_sg);
>> +	}
>> +
>> +	if (no_chunk == 1)
>> +		return sunxi_ss_aes_poll(areq, mode);
>> +
> 
> Given your explanations, I'm not sure the names sunxi_ss_aes_poll and
> sunxi_ss_des_poll are appropriate.
> 
> What about sunxi_ss_aligned_cipher_op_poll and sunxi_ss_cipher_op_poll.

The difference is not about aligned or not since according to my understanding, the data will always be aligned following cra_alignmask.

Thanks for your review

> 
> That's all I got for now.
> I haven't reviewed the hash part yet, but I guess some of my comments
> apply to this code too.
> 
> Best Regards,
> 
> Boris
> 
> 
> [1]http://lxr.free-electrons.com/source/lib/scatterlist.c#L621
> 

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