Re: [PATCH 1/3] mci: imx-esdhc: Bail out if DMA address is larger than 32-bits

[Andrey Smirnov <andrew.smirnov@gmail.com>]

On Sun, Aug 26, 2018 at 11:53 PM Sascha Hauer <s.hauer@pengutronix.de> wrote:
>
> On Thu, Aug 23, 2018 at 08:05:09PM -0700, Andrey Smirnov wrote:
> > On 64-bit SoCs it becomes possible to end up with a DMA buffer
> > allocated in the region of memory inaccessible to ESDHC
> > controller. Change the code to bail out if that happens to avoid
> > silent failures.
> >
> > Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
> > ---
> >  drivers/mci/imx-esdhc.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/mci/imx-esdhc.c b/drivers/mci/imx-esdhc.c
> > index db96a8139..f6451e204 100644
> > --- a/drivers/mci/imx-esdhc.c
> > +++ b/drivers/mci/imx-esdhc.c
> > @@ -304,6 +304,9 @@ esdhc_send_cmd(struct mci_host *mci, struct mci_cmd *cmd, struct mci_data *data)
> >                       dma = dma_map_single(host->dev, ptr, num_bytes, dir);
> >                       if (dma_mapping_error(host->dev, dma))
> >                               return -EIO;
> > +
> > +                     if (dma > U32_MAX)
> > +                             return -EFAULT;
> >               }
>
> If struct device_d had a dma_mask member, it could be initialized by the
> esdhc driver probe function and dma_map_single() would already fail on
> addresses > 32bit without additional checks.
>
> That's what Linux does and I think we should do the same.
>

Good idea, will do in v2.

Thanks,
Andrey Smirnov

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