Re: [PATCH v2 06/15] ppc/vof: Fix unaligned FDT property access

[David Gibson]

On Fri, Jun 28, 2024 at 04:20:02PM +0100, Peter Maydell wrote:
> On Thu, 27 Jun 2024 at 14:39, Akihiko Odaki <akihiko.odaki@daynix.com> wrote:
> >
> > FDT properties are aligned by 4 bytes, not 8 bytes.
> >
> > Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
> > ---
> >  hw/ppc/vof.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/hw/ppc/vof.c b/hw/ppc/vof.c
> > index e3b430a81f4f..b5b6514d79fc 100644
> > --- a/hw/ppc/vof.c
> > +++ b/hw/ppc/vof.c
> > @@ -646,7 +646,7 @@ static void vof_dt_memory_available(void *fdt, GArray 
> > *claimed, uint64_t base)
> >      mem0_reg = fdt_getprop(fdt, offset, "reg", &proplen);
> >      g_assert(mem0_reg && proplen == sizeof(uint32_t) * (ac + sc));
> >      if (sc == 2) {
> > -        mem0_end = be64_to_cpu(*(uint64_t *)(mem0_reg + sizeof(uint32_t) * 
> > ac));
> > +        mem0_end = ldq_be_p(mem0_reg + sizeof(uint32_t) * ac);
> >      } else {
> >          mem0_end = be32_to_cpu(*(uint32_t *)(mem0_reg + sizeof(uint32_t) * 
> > ac));
> >      }
> 
> I did wonder if there was a better way to do what this is doing,
> but neither we (in system/device_tree.c) nor libfdt seem to
> provide one.

libfdt does provide unaligned access helpers (fdt32_ld() etc.), but
not an automatic aligned-or-unaligned helper.   Maybe we should add that?

-- 
David Gibson (he or they)       | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you, not the other way
                                | around.
http://www.ozlabs.org/~dgibson

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