Re: [PATCH v1 ] ALSA: core: memalloc: add page alignment for iram

[Takashi Iwai]

On Thu, 17 Dec 2020 10:43:45 +0100,
Lars-Peter Clausen wrote:
> 
> On 12/17/20 5:15 PM, Robin Gong wrote:
> > Since mmap for userspace is based on page alignment, add page alignment
> > for iram alloc from pool, otherwise, some good data located in the same
> > page of dmab->area maybe touched wrongly by userspace like pulseaudio.
> >
> I wonder, do we also have to align size to be a multiple of PAGE_SIZE
> to avoid leaking unrelated data?

Hm, a good question.  Basically the PCM buffer size itself shouldn't
be influenced by that (i.e. no hw-constraint or such is needed), but
the padding should be cleared indeed.  I somehow left those to the
allocator side, but maybe it's safer to clear the whole buffer in
sound/core/memalloc.c commonly.


thanks,

Takashi