[PATCH v4 08/12] bloblist: Handle alignment with a void entry

[Simon Glass]

Hi Ilias,

On Thu, Dec 28, 2023 at 11:32 AM Ilias Apalodimas
<ilias.apalodimas at linaro.org> wrote:
>
> Hi Raymond,
>
> On Wed, 27 Dec 2023 at 23:08, Raymond Mao <raymond.mao at linaro.org> wrote:
> >
> > From: Simon Glass <sjg at chromium.org>
> >
> > Rather than setting the alignment using the header size, add an entirely
> > new entry to cover the gap left by the alignment.
> >
> > Signed-off-by: Simon Glass <sjg at chromium.org>
> > Co-developed-by: Raymond Mao <raymond.mao at linaro.org>
> > Signed-off-by: Raymond Mao <raymond.mao at linaro.org>
> > Reviewed-by: Simon Glass <sjg at chromium.org>
> > ---
> >  common/bloblist.c | 23 +++++++++++++++++++----
> >  1 file changed, 19 insertions(+), 4 deletions(-)
> >
> > diff --git a/common/bloblist.c b/common/bloblist.c
> > index 705d9c6ae9..73dbbc01c0 100644
> > --- a/common/bloblist.c
> > +++ b/common/bloblist.c
> > @@ -142,7 +142,7 @@ static int bloblist_addrec(uint tag, int size, int align_log2,
> >  {
> >         struct bloblist_hdr *hdr = gd->bloblist;
> >         struct bloblist_rec *rec;
> > -       int data_start, new_alloced;
> > +       int data_start, aligned_start, new_alloced;
> >
> >         if (!align_log2)
> >                 align_log2 = BLOBLIST_ALIGN_LOG2;
> > @@ -151,10 +151,25 @@ static int bloblist_addrec(uint tag, int size, int align_log2,
> >         data_start = map_to_sysmem(hdr) + hdr->alloced + sizeof(*rec);
> >
> >         /* Align the address and then calculate the offset from ->alloced */
> > -       data_start = ALIGN(data_start, 1U << align_log2) - map_to_sysmem(hdr);
> > +       aligned_start = ALIGN(data_start, 1U << align_log2) - data_start;
> > +
> > +       /* If we need to create a dummy record, create it */
> > +       if (aligned_start) {
> > +               int void_size = aligned_start - sizeof(*rec);
> > +               struct bloblist_rec *vrec;
> > +               int ret;
> > +
> > +               ret = bloblist_addrec(BLOBLISTT_VOID, void_size, 0, &vrec);
>
> I just noticed the 'BLOBLISTT'. Is that on purpose? or a typo?

It means 'bloblist tag'

>
> > +               if (ret)
> > +                       return log_msg_ret("void", ret);
> > +
> > +               /* start the record after that */
> > +               data_start = map_to_sysmem(hdr) + hdr->alloced + sizeof(*vrec);
> > +       }
> >
> >         /* Calculate the new allocated total */
> > -       new_alloced = data_start + ALIGN(size, 1U << align_log2);
> > +       new_alloced = data_start - map_to_sysmem(hdr) +
> > +               ALIGN(size, 1U << align_log2);
>
> So, wouldn't it make more sense to add the dummy record and align the
> whole thing *after* we've added the entry?
> Doing it like this might leave the last entry on an unaligned boundary, no?

I will let Raymond respond as I'm not sure what this means.

>
> Thanks
> /Ilias
> >
> >         if (new_alloced > hdr->size) {
> >                 log_err("Failed to allocate %x bytes size=%x, need size=%x\n",
> > @@ -164,7 +179,7 @@ static int bloblist_addrec(uint tag, int size, int align_log2,
> >         rec = (void *)hdr + hdr->alloced;
> >
> >         rec->tag = tag;
> > -       rec->hdr_size = data_start - hdr->alloced;
> > +       rec->hdr_size = sizeof(struct bloblist_rec);
> >         rec->size = size;
> >
> >         /* Zero the record data */
> > --
> > 2.25.1
> >

Regards,
Simon