Re: [PATCHv8 RESEND 03/15] remoteproc/omap: Add a sanity check for DSP boot address alignment

[Mathieu Poirier]

On Fri, Mar 13, 2020 at 07:43:34PM -0500, Suman Anna wrote:
> The DSP remote processors on OMAP SoCs require a boot register to
> be programmed with a boot address, and this boot address needs to
> be on a 1KB boundary. The current code is simply masking the boot
> address appropriately without performing any sanity checks before
> releasing the resets. An unaligned boot address results in an
> undefined execution behavior and can result in various bus errors
> like MMU Faults or L3 NoC errors. Such errors are hard to debug and
> can be easily avoided by adding a sanity check for the alignment
> before booting a DSP remote processor.
> 
> Signed-off-by: Suman Anna <s-anna@xxxxxx>
> Signed-off-by: Tero Kristo <t-kristo@xxxxxx>
> Reviewed-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
> Reviewed-by: Andrew F. Davis <afd@xxxxxx>
> Acked-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
> ---
> v8-Resend: Updated to fix compilation issues against rproc-next
> 
>  drivers/remoteproc/omap_remoteproc.c | 20 ++++++++++++++++----
>  1 file changed, 16 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/remoteproc/omap_remoteproc.c b/drivers/remoteproc/omap_remoteproc.c
> index d47d5ded651a..fe11cb709770 100644
> --- a/drivers/remoteproc/omap_remoteproc.c
> +++ b/drivers/remoteproc/omap_remoteproc.c
> @@ -121,14 +121,23 @@ static void omap_rproc_kick(struct rproc *rproc, int vqid)
>   * @rproc: handle of a remote processor
>   *
>   * Set boot address for a supported DSP remote processor.
> + *
> + * Return: 0 on success, or -EINVAL if boot address is not aligned properly
>   */
> -static void omap_rproc_write_dsp_boot_addr(struct rproc *rproc)
> +static int omap_rproc_write_dsp_boot_addr(struct rproc *rproc)
>  {
> +	struct device *dev = rproc->dev.parent;
>  	struct omap_rproc *oproc = rproc->priv;
>  	struct omap_rproc_boot_data *bdata = oproc->boot_data;
>  	u32 offset = bdata->boot_reg;
>  
> -	regmap_write(bdata->syscon, offset, rproc->bootaddr);
> +	if (rproc->bootaddr & (SZ_1K - 1)) {
> +		dev_err(dev, "invalid boot address 0x%llx, must be aligned on a 1KB boundary\n",
> +			rproc->bootaddr);

Yes it does fix the compilation problem but after that patch 7 doesn't apply
anymore.

> +		return -EINVAL;
> +	}
> +
> +	return regmap_write(bdata->syscon, offset, rproc->bootaddr);
>  }
>  
>  /*
> @@ -145,8 +154,11 @@ static int omap_rproc_start(struct rproc *rproc)
>  	int ret;
>  	struct mbox_client *client = &oproc->client;
>  
> -	if (oproc->boot_data)
> -		omap_rproc_write_dsp_boot_addr(rproc);
> +	if (oproc->boot_data) {
> +		ret = omap_rproc_write_dsp_boot_addr(rproc);
> +		if (ret)
> +			return ret;
> +	}
>  
>  	client->dev = dev;
>  	client->tx_done = NULL;
> -- 
> 2.23.0
>