Hi Adrian,
On Thu, Jun 18, 2020 at 10:46 PM John Paul Adrian Glaubitz
<glaub...@physik.fu-berlin.de> wrote:
> On 6/18/20 12:10 PM, John Paul Adrian Glaubitz wrote:
> > Reported upstream [1].
>
> It's an alignment issue and can be trivially fixed with this patch:
>
> diff --git a/op.h b/op.h
> index fc21f03cda..480c95245b 100644
> --- a/op.h
> +++ b/op.h
> @@ -698,7 +698,7 @@ struct opslot {
> U16 opslot_size; /* size of this slot (in pointers) */
> U16 opslot_offset; /* offset from start of slab (in ptr
> units) */
> OP opslot_op; /* the op itself */
> -};
> +} __attribute__ ((aligned (4)));
>
> struct opslab {
> OPSLAB * opslab_next; /* next slab */
In the mean time, you changed this to add explicit padding instead:
https://github.com/Perl/perl5/issues/17871
> diff --git a/op.h b/op.h
> index fc21f03cda..fb9f538e23 100644
> --- a/op.h
> +++ b/op.h
> @@ -714,6 +714,7 @@ struct opslab {
> # ifdef PERL_DEBUG_READONLY_OPS
> bool opslab_readonly;
> # endif
> + U16 opslab_padding; /* padding to ensure proper
> alignment */
> OPSLOT opslab_slots; /* slots begin here */
> };
I take it PERL_DEBUG_READONLY_OPS is enabled?
Hence the padding should be moved inside the #ifdef,
Furthermore, sizeof(bool) = 1, right? So you still have an implicit
hole, and it would be better to add 3 bytes of explicit padding
instead one 16-bit quantity.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
