Subject: [PATCH v4 2/2] crypto: stm32 - Support for STM32 CRYP crypto module

From: [email-masked] (Corentin Labbe)
Date: Thu, 19 Oct 2017 12:34:54 +0200

Hello

I have some minor comment below

On Thu, Oct 19, 2017 at 11:03:59AM +0200, Fabien Dessenne wrote:
> This module registers block cipher algorithms that make use of the
> STMicroelectronics STM32 crypto "CRYP1" hardware.
> The following algorithms are supported:
> - aes: ecb, cbc, ctr
> - des: ecb, cbc
> - tdes: ecb, cbc
> 
> Signed-off-by: Fabien Dessennie <[email-masked]>
> ---
>  drivers/crypto/stm32/Kconfig      |    9 +
>  drivers/crypto/stm32/Makefile     |    3 +-
>  drivers/crypto/stm32/stm32-cryp.c | 1188 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 1199 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/crypto/stm32/stm32-cryp.c
> 
> diff --git a/drivers/crypto/stm32/Kconfig b/drivers/crypto/stm32/Kconfig
> index 602332e..61ef00b 100644
> --- a/drivers/crypto/stm32/Kconfig
> +++ b/drivers/crypto/stm32/Kconfig
[...]
> +/* Bit [0] encrypt / decrypt */
> +#define FLG_ENCRYPT             BIT(0)
> +/* Bit [8..1] algo & operation mode */
> +#define FLG_AES                 BIT(1)
> +#define FLG_DES                 BIT(2)
> +#define FLG_TDES                BIT(3)
> +#define FLG_ECB                 BIT(4)
> +#define FLG_CBC                 BIT(5)
> +#define FLG_CTR                 BIT(6)
> +/* Mode mask = bits [15..0] */
> +#define FLG_MODE_MASK           GENMASK(15, 0)
> +
> +/* Registers */
> +#define CRYP_CR                 0x00000000
> +#define CRYP_SR                 0x00000004
> +#define CRYP_DIN                0x00000008
> +#define CRYP_DOUT               0x0000000C
> +#define CRYP_DMACR              0x00000010
> +#define CRYP_IMSCR              0x00000014
> +#define CRYP_RISR               0x00000018
> +#define CRYP_MISR               0x0000001C
> +#define CRYP_K0LR               0x00000020
> +#define CRYP_K0RR               0x00000024
> +#define CRYP_K1LR               0x00000028
> +#define CRYP_K1RR               0x0000002C
> +#define CRYP_K2LR               0x00000030
> +#define CRYP_K2RR               0x00000034
> +#define CRYP_K3LR               0x00000038
> +#define CRYP_K3RR               0x0000003C
> +#define CRYP_IV0LR              0x00000040
> +#define CRYP_IV0RR              0x00000044
> +#define CRYP_IV1LR              0x00000048
> +#define CRYP_IV1RR              0x0000004C
> +
> +/* Registers values */
> +#define CR_DEC_NOT_ENC          0x00000004
> +#define CR_TDES_ECB             0x00000000
> +#define CR_TDES_CBC             0x00000008
> +#define CR_DES_ECB              0x00000010
> +#define CR_DES_CBC              0x00000018
> +#define CR_AES_ECB              0x00000020
> +#define CR_AES_CBC              0x00000028
> +#define CR_AES_CTR              0x00000030
> +#define CR_AES_KP               0x00000038
> +#define CR_AES_UNKNOWN          0xFFFFFFFF
> +#define CR_ALGO_MASK            0x00080038
> +#define CR_DATA32               0x00000000
> +#define CR_DATA16               0x00000040
> +#define CR_DATA8                0x00000080
> +#define CR_DATA1                0x000000C0
> +#define CR_KEY128               0x00000000
> +#define CR_KEY192               0x00000100
> +#define CR_KEY256               0x00000200
> +#define CR_FFLUSH               0x00004000
> +#define CR_CRYPEN               0x00008000

Why not using BIT(x) ?
Why not using also directly FLG_XX since CR_XX are arbitray values ? like using instead CR_AES_CBC = FLG_AES | FLG_CBC

[...]
> +static inline void stm32_cryp_wait_enable(struct stm32_cryp *cryp)
> +{
> +	while (stm32_cryp_read(cryp, CRYP_CR) & CR_CRYPEN)
> +		cpu_relax();
> +}

This function is not used, so you could remove it

> +
> +static inline void stm32_cryp_wait_busy(struct stm32_cryp *cryp)
> +{
> +	while (stm32_cryp_read(cryp, CRYP_SR) & SR_BUSY)
> +		cpu_relax();
> +}

No timeout ?

> +
> +static inline void stm32_cryp_wait_output(struct stm32_cryp *cryp)
> +{
> +	while (!(stm32_cryp_read(cryp, CRYP_SR) & SR_OFNE))
> +		cpu_relax();
> +}

This function is not used, so you could remove it

[...]
> +static int stm32_cryp_check_aligned(struct scatterlist *sg, size_t total,
> +				    size_t align)
> +{
> +	int len = 0;
> +
> +	if (!total)
> +		return 0;
> +
> +	if (!IS_ALIGNED(total, align))
> +		return -EINVAL;
> +
> +	while (sg) {
> +		if (!IS_ALIGNED(sg->offset, sizeof(u32)))
> +			return -1;

-1 is not a good return value, prefer any -Exxxx

> +
> +		if (!IS_ALIGNED(sg->length, align))
> +			return -1;
> +
> +		len += sg->length;
> +		sg = sg_next(sg);
> +	}
> +
> +	if (len != total)
> +		return -1;
[...]
> +static int stm32_cryp_copy_sgs(struct stm32_cryp *cryp)
> +{
> +	void *buf_in, *buf_out;
> +	int pages, total_in, total_out;
> +
> +	if (!stm32_cryp_check_io_aligned(cryp)) {
> +		cryp->sgs_copied = 0;
> +		return 0;
> +	}
> +
> +	total_in = ALIGN(cryp->total_in, cryp->hw_blocksize);
> +	pages = total_in ? get_order(total_in) : 1;
> +	buf_in = (void *)__get_free_pages(GFP_ATOMIC, pages);
> +
> +	total_out = ALIGN(cryp->total_out, cryp->hw_blocksize);
> +	pages = total_out ? get_order(total_out) : 1;
> +	buf_out = (void *)__get_free_pages(GFP_ATOMIC, pages);
> +
> +	if (!buf_in || !buf_out) {
> +		pr_err("Couldn't allocate pages for unaligned cases.\n");

You must use dev_err() instead. without it, it will be hard to know which subsystem said that error message.

[...]
> +static int stm32_cryp_cra_init(struct crypto_tfm *tfm)
> +{
> +	tfm->crt_ablkcipher.reqsize = sizeof(struct stm32_cryp_reqctx);
> +
> +	return 0;
> +}

You could simply remove this function

[...]
> +
> +static void stm32_cryp_cra_exit(struct crypto_tfm *tfm)
> +{
> +}
> +
> +static int stm32_cryp_crypt(struct ablkcipher_request *req, unsigned long mode)
> +{
> +	struct stm32_cryp_ctx *ctx = crypto_ablkcipher_ctx(
> +			crypto_ablkcipher_reqtfm(req));
> +	struct stm32_cryp_reqctx *rctx = ablkcipher_request_ctx(req);
> +	struct stm32_cryp *cryp = stm32_cryp_find_dev(ctx);
> +
> +	if (!cryp)
> +		return -ENODEV;
> +
> +	rctx->mode = mode;
> +
> +	return crypto_transfer_cipher_request_to_engine(cryp->engine, req);
> +}
> +
> +static int stm32_cryp_setkey(struct crypto_ablkcipher *tfm, const u8 *key,
> +			     unsigned int keylen)
> +{
> +	struct stm32_cryp_ctx *ctx = crypto_ablkcipher_ctx(tfm);
> +
> +	memcpy(ctx->key, key, keylen);
> +	ctx->keylen = keylen;

You never zeroize the key after request.

[...]
> +static const struct of_device_id stm32_dt_ids[] = {
> +	{ .compatible = "st,stm32f756-cryp", },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, sti_dt_ids);
> +
> +static int stm32_cryp_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct stm32_cryp *cryp;
> +	struct resource *res;
> +	struct reset_control *rst;
> +	const struct of_device_id *match;
> +	int irq, ret;
> +
> +	cryp = devm_kzalloc(dev, sizeof(*cryp), GFP_KERNEL);
> +	if (!cryp)
> +		return -ENOMEM;
> +
> +	match = of_match_device(stm32_dt_ids, dev);
> +	if (!match)
> +		return -ENODEV;

I think this test is unnecessary, at least it should be before the devm_kzalloc

Regards