linux-kernel - Re: [PATCH v3 1/1] crypto: caam/rng: Add support for PRNG

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Date:   Wed, 27 Apr 2022 14:48:39 +0300
From:   Horia Geantă <horia.geanta@....com>
To:     Meenakshi Aggarwal <meenakshi.aggarwal@....com>,
        Pankaj Gupta <pankaj.gupta@....com>,
        Gaurav Jain <gaurav.jain@....com>,
        Varun Sethi <V.Sethi@....com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S . Miller" <davem@...emloft.net>
Cc:     "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>
Subject: Re: [PATCH v3 1/1] crypto: caam/rng: Add support for PRNG

On 4/20/2022 9:38 AM, Meenakshi Aggarwal wrote:
> +static void caam_prng_done(struct device *jrdev, u32 *desc, u32 err,
> +			  void *context)
> +{
> +	struct caam_prng_ctx *jctx = context;
> +
> +	if (err >> JRSTA_SSRC_SHIFT)
> +		jctx->err = caam_jr_strstatus(jrdev, err);
The details of error handling are in error.c, let's keep this abstraction.

> +	else
> +		jctx->err = 0;
> +
> +	complete(&jctx->done);
> +}
> +
[...]
> +static int caam_prng_seed(struct crypto_rng *tfm,
> +			 const u8 *seed, unsigned int slen)
> +{
> +	struct caam_prng_ctx ctx;
> +	struct device *jrdev;
> +	dma_addr_t seed_dma;
> +	u32 *desc;
> +	u8 *buf;
> +	int ret = 0;
> +
> +	if (seed == NULL) {
> +		pr_err("Seed not provided\n");
> +		return ret;
> +	}
> +
> +	buf = kzalloc(slen, GFP_KERNEL);
> +	if (!buf)
> +		return -ENOMEM;
> +
> +	jrdev = caam_jr_alloc();
> +	ret = PTR_ERR_OR_ZERO(jrdev);
> +	if (ret) {
> +		pr_err("Job Ring Device allocation failed\n");
> +		kfree(buf);
> +		return ret;
> +	}
> +
> +	desc = kzalloc(CAAM_PRNG_DESC_LEN, GFP_KERNEL | GFP_DMA);
> +	if (!desc) {
> +		ret = -ENOMEM;
> +		goto out1;
> +	}
> +
> +	memcpy(buf, seed, slen);
> +
> +	seed_dma = dma_map_single(jrdev, buf, slen, DMA_FROM_DEVICE);
Now that seedsize is 0, the .seed callback is called with slen = 0.
Reseed descriptor should be updated too.

Horia