Re: [Qemu-riscv] [Qemu-devel] [PATCH] riscv: rv32: Root page table address can be larger than 32-bit

[Bin Meng]

Hi Richard,

On Thu, Aug 1, 2019 at 1:35 AM Richard Henderson
<address@hidden> wrote:
>
> On 7/31/19 5:45 AM, Bin Meng wrote:
> > -    target_ulong base;
> > +    hwaddr base;
> ...
> > -        target_ulong pte_addr = base + idx * ptesize;
> > +        hwaddr pte_addr = base + idx * ptesize;
>
> I believe that you either need
>
>     base + (hwaddr)idx * ptesize
>
> or change the type of idx to hwaddr above.
>
> Otherwise the multiply overflows before it gets promoted with the add.
>

I am not sure how (idx * ptesize) could overflow. It represents the
offset by a page table which is [0, 4096).

Regards,
Bin