Re: [PATCH 05/14] ppc/vof: Fix unaligned FDT property access

[Akihiko Odaki]

On 2024/06/27 23:02, Philippe Mathieu-Daudé wrote:
> On 27/6/24 15:12, Akihiko Odaki wrote:
> > On 2024/06/26 21:03, Philippe Mathieu-Daudé wrote:
> > > On 26/6/24 13:06, Akihiko Odaki 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));
> > >
> > > OK but please keep API uses consistent, so convert other uses please.
> >
> > This is the only unaligned access.
>
> What I mean with consistent API use is either use the be64_to_cpu and
> be32_to_cpu API, or ldq_be_p and ldl_be_p. A mix of both makes review
> more confusing.

The desired semantics are different in these two cases so I believe it 
is natural to use different APIs; ldq_be_p() for an unaligned 64-bit 
access and be32_to_cpu(*(uint32_t *)) for an aligned 32-bit access.