Re: [PATCH v1] crypto: driver for tegra AES hardware

[Varun Wadekar <vwadekar-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>]

> That doesn't make the duplicate memset/copy cease to be redundant.
>
> Why not copy the key to where it goes, then memset the rest of the data;
> wouldn't that be as simple as:
>
> memcpy(dd->ivkey_base, ctx->key, ctx->keylen);
> memset(dd->ivkey_base + ctx->keylen, 0, AES_HW_KEY_TABLE_LENGTH_BYTES - ctx->keylen);

Seems like the same thing to me. Kim is inclined towards removing the
memset completely, which I think should not be done. We need the memset
to clear the entire key table.

> Related to this, I wonder why:
>
> /*
>  * The key table length is 64 bytes
>  * (This includes first upto 32 bytes key + 16 bytes original initial vector
>  * and 16 bytes updated initial vector)
>  */ 
> #define AES_HW_KEY_TABLE_LENGTH_BYTES 64
>
> Yet:
>
> dd->ivkey_base = dma_alloc_coherent(dev, SZ_512, &dd->ivkey_phys_base, ...
>
> Why is SZ_512 used to during alloc instead of AES_HW_KEY_TABLE_LENGTH_BYTES?

Correct. Will fix this.