Re: [PATCH 2/2] hw/misc/allwinner-h3-dramc: enforce 64-bit multiply when calculating row mirror address

[Niek Linnenbank <nieklinnenbank@gmail.com>]

[-- Attachment #1: Type: text/plain, Size: 1931 bytes --]

Hi Peter,

On Sun, Mar 22, 2020 at 10:18 PM Peter Maydell <peter.maydell@linaro.org>
wrote:

> On Sun, 22 Mar 2020 at 20:54, Niek Linnenbank <nieklinnenbank@gmail.com>
> wrote:
> >
> > The allwinner_h3_dramc_map_rows function simulates row addressing
> behavior
> > when bootloader software attempts to detect the amount of available
> SDRAM.
> >
> > Currently the line that calculates the 64-bit address of the mirrored row
> > uses a signed 32-bit multiply operation that in theory could result in
> the
> > upper 32-bit be all 1s. This commit ensures that the row mirror address
> > is calculated using only 64-bit operations.
> >
> > Reported-by: Peter Maydell <peter.maydell@linaro.org>
> > Signed-off-by: Niek Linnenbank <nieklinnenbank@gmail.com>
> > ---
> >  hw/misc/allwinner-h3-dramc.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/hw/misc/allwinner-h3-dramc.c b/hw/misc/allwinner-h3-dramc.c
> > index 2b5260260e..f9f05b5384 100644
> > --- a/hw/misc/allwinner-h3-dramc.c
> > +++ b/hw/misc/allwinner-h3-dramc.c
> > @@ -85,8 +85,8 @@ static void
> allwinner_h3_dramc_map_rows(AwH3DramCtlState *s, uint8_t row_bits,
> >
> >      } else if (row_bits_actual) {
> >          /* Row bits not matching ram_size, install the rows mirror */
> > -        hwaddr row_mirror = s->ram_addr + ((1 << (row_bits_actual +
> > -                                                  bank_bits)) *
> page_size);
> > +        hwaddr row_mirror = s->ram_addr + ((1UL << (row_bits_actual +
> > +                                                    bank_bits)) *
> page_size);
>
> This needs to be a "ULL" suffix... (I just sent a different email
> with the rationale).
>

Ah ofcourse, it should be ULL indeed. And I can't think of any reason why I
made this mistake.
I simply overlooked it, thanks. I'm resending this patch with the proper
ULL suffix.

Regards,
Niek


>
> thanks
> -- PMM
>


-- 
Niek Linnenbank

[-- Attachment #2: Type: text/html, Size: 3038 bytes --]