linux-kernel - Re: [PATCH v3 2/4] crypto: talitos

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Date:   Sat, 15 Jun 2019 10:18:06 +0200
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Horia Geanta <horia.geanta@....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>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH v3 2/4] crypto: talitos - fix hash on SEC1.



Le 14/06/2019 à 13:32, Horia Geanta a écrit :
> On 6/13/2019 3:48 PM, Christophe Leroy wrote:
>> @@ -336,15 +336,18 @@ static void flush_channel(struct device *dev, int ch, int error, int reset_ch)
>>   	tail = priv->chan[ch].tail;
>>   	while (priv->chan[ch].fifo[tail].desc) {
>>   		__be32 hdr;
>> +		struct talitos_edesc *edesc;
>>   
>>   		request = &priv->chan[ch].fifo[tail];
>> +		edesc = container_of(request->desc, struct talitos_edesc, desc);
> Not needed for all cases, should be moved to the block that uses it.

Ok.

> 
>>   
>>   		/* descriptors with their done bits set don't get the error */
>>   		rmb();
>>   		if (!is_sec1)
>>   			hdr = request->desc->hdr;
>>   		else if (request->desc->next_desc)
>> -			hdr = (request->desc + 1)->hdr1;
>> +			hdr = ((struct talitos_desc *)
>> +			       (edesc->buf + edesc->dma_len))->hdr1;
>>   		else
>>   			hdr = request->desc->hdr1;
>>   
> [snip]
>> @@ -2058,7 +2065,18 @@ static int ahash_process_req(struct ahash_request *areq, unsigned int nbytes)
>>   		sg_copy_to_buffer(areq->src, nents,
>>   				  ctx_buf + req_ctx->nbuf, offset);
>>   		req_ctx->nbuf += offset;
>> -		req_ctx->psrc = areq->src;
>> +		for (sg = areq->src; sg && offset >= sg->length;
>> +		     offset -= sg->length, sg = sg_next(sg))
>> +			;
>> +		if (offset) {
>> +			sg_init_table(req_ctx->bufsl, 2);
>> +			sg_set_buf(req_ctx->bufsl, sg_virt(sg) + offset,
>> +				   sg->length - offset);
>> +			sg_chain(req_ctx->bufsl, 2, sg_next(sg));
>> +			req_ctx->psrc = req_ctx->bufsl;
> Isn't this what scatterwalk_ffwd() does?

Thanks for pointing this, I wasn't aware of that function. Looking at it 
it seems to do the same. Unfortunately, some tests fails with 'wrong 
result' when using it instead.

Comparing the results of scatterwalk_ffwd() with what I get with my open 
codying, I see the following difference:

scatterwalk_ffwd() uses sg_page(sg) + sg->offset + len

while my open codying results in virt_to_page(sg_virt(sg) + len)

When sg->offset + len is greater than PAGE_SIZE, the resulting SG entry 
is different allthough valid in both cases. I think this difference 
results in sg_copy_to_buffer() failing. I'm still investigating. Any idea ?

Christophe

> 
> Horia
>