Re: [PATCH] crypto: gcm - fix cacheline sharing

[Ard Biesheuvel]

On Thu, 30 May 2019 at 15:58, Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> wrote:
>
> On Thu, May 30, 2019 at 01:45:47PM +0000, Iuliana Prodan wrote:
> >
> > On the current structure of caamalg, to work, iv needs to be copied
> > before memcpy(iv, req->iv, ivsize), from skcipher_edesc_alloc function.
> > For this we need edesc, but this cannot be allocated before knowing how
> > much memory we need. So, to make it work, we'll need to modify more in CAAM.
>
> All the copying does is:
>
>         if (ivsize)
>                 scatterwalk_map_and_copy(req->iv, req->src, req->cryptlen -
>                                          ivsize, ivsize, 0);
>
> Why do you need to allocate the edesc before doing this?
>

Because that is where the incoming iv is currently consumed. Copying
it out like this wipes the input IV from memory.