On 26.09.2017 12:34, Gilad Ben-Yossef wrote: > On Tue, Sep 26, 2017 at 12:36 PM, Christophe LEROY > <christophe.leroy@xxxxxx> wrote: >> Hello, >> >> Today, the talitos driver dma maps/unmaps context and keys at every single >> request. >> I'm looking at doing the dma mapping at hash init and doing unmapping at >> final/finup/digest >> >> However, I'm wondering how to manage hash exports and imports. I was >> initially thinking about doing a dma_sync_for_cpu() before any export and a >> dma_sync_for_device() after any export, but that supposes that the dma area >> is already mapped, which means that we have done the init and not yet done a >> final/finup/digest. >> >> I'm a bit sceptic when reading the following text in include/crypto/hash.h : >> >> @export: Export partial state of the transformation. This function dumps the >> * entire state of the ongoing transformation into a provided block >> of >> * data so it can be @import 'ed back later on. This is useful in >> case >> * you want to save partial result of the transformation after >> * processing certain amount of data and reload this partial result >> * multiple times later on for multiple re-use >> >> >> Does it mean that import may be called in lieu of hash init, or is hash init >> always called before doing an import ? >> > > I believe import is called in lieu of init. > > See the example is testmgr.c here: > http://elixir.free-electrons.com/linux/latest/source > > import is called on a freshly allocated request (save for set_crypt > and set_callback), followed by > a call to update. Both import()/export() are synchronous op, this means they are not allowed to return -EINPROGRESS nor call complete(). Can import() be called without _any_ init(), for example after reboot of machine ? Is following scenario valid: init(), update() 0 or more times, export(), save exported data to pernament storage reboot machine load crypto driver, import() saved state ? -- Best regards, Kamil Konieczny Samsung R&D Institute Poland
