Re: [EXT] Re: [PATCH v5 4/5] crypto: caam - add in-kernel interface for blob generator

[Ahmad Fatoum]

Hello Pankaj,

On 25.02.22 13:20, Pankaj Gupta wrote:
>>>> +static u32 *caam_blob_alloc_desc(size_t keymod_len) {
>>>> +    size_t len;
>>>> +
>>>> +    /* header + (key mod immediate) + 2x pointers + op */
>>>> +    len = 4 + (4 + ALIGN(keymod_len, 4)) + 2*(4 + 4 +
>>>> + CAAM_PTR_SZ_MAX) + 4;
>>>
>>> Nit: the amount of magic numbers is overwhelming here. I neither
>>> understand the statement nor how that comment should help me to
>> understand it.
>>
>> header              =  4
>> (key mod immediate) = (4 + ALIGN(keymod_len, 4))
>> 2x pointer          =  2 * (4 + 4 + CAAM_PTR_SZ_MAX)
>> op                  =  4
> 
> Instead of the function caam_blob_alloc_desc(), it will be great if the caller functions caam_encap_blob()/caam_encap_blob (), could add local array:
> uint32_t desc[CAAM_DESC_BYTES_MAX];

I just looked into this and placing desc on stack is not possible
as it is used for DMA inside caam_jr_enqueue().

Cheers,
Ahmad


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