On 26/06/2020 07:31, Herbert Xu wrote:
On Mon, Jun 15, 2020 at 10:14:48AM +0300, Tero Kristo wrote:+static int sa_sha_update(struct ahash_request *req) +{ + struct sa_sha_req_ctx *rctx = ahash_request_ctx(req); + struct scatterlist *sg; + void *buf; + int pages; + struct page *pg; + + if (!req->nbytes) + return 0; + + if (rctx->buf_free >= req->nbytes) { + pg = sg_page(rctx->sg_next); + buf = kmap_atomic(pg); + scatterwalk_map_and_copy(buf + rctx->offset, req->src, 0, + req->nbytes, 0); + kunmap_atomic(buf); + rctx->buf_free -= req->nbytes; + rctx->sg_next->length += req->nbytes; + rctx->offset += req->nbytes; + } else { + pages = get_order(req->nbytes); + buf = (void *)__get_free_pages(GFP_ATOMIC, pages); + if (!buf) + return -ENOMEM; + + sg = kzalloc(sizeof(*sg) * 2, GFP_KERNEL); + if (!sg) + return -ENOMEM; + + sg_init_table(sg, 1); + sg_set_buf(sg, buf, req->nbytes); + scatterwalk_map_and_copy(buf, req->src, 0, req->nbytes, 0); + + rctx->buf_free = (PAGE_SIZE << pages) - req->nbytes; + + if (rctx->sg_next) { + sg_unmark_end(rctx->sg_next); + sg_chain(rctx->sg_next, 2, sg); + } else { + rctx->src = sg; + } + + rctx->sg_next = sg; + rctx->src_nents++; + + rctx->offset = req->nbytes; + } + + rctx->len += req->nbytes; + + return 0; +}This is not how it's supposed to work. To support the partial hashing interface, you must actually hash the data and not just save it in your context. Otherwise your export is completely meaningless.
I have been experimenting with an alternate approach, where I have a small buffer within the context, this would be more like the way other drivers do this. If the buffer is closed before running out of space, I can push this to be processed by HW, otherwise I must fallback to SW. Does this sound like a better approach?
If your hardware cannot export partially hashed state, then you should use a software fallback for everything but digest.
Yea, HW can't support partial hashes. -Tero -- Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
