[RFC PATCH 2/7] iommu/arm-smmu-v3: Do resource size checks based on smmu option PAGE0_REGS_ONLY

Robin Murphy
2017-04-11T15:43:03Z

On 11/04/17 15:42, linucherian at gmail.com wrote:
> From: Linu Cherian <linu.cherian@cavium.com>
>
> With implementations supporting only page 0 of register space,
> resource size can be 64k as well and hence perform size checks
> based on smmu option PAGE0_REGS_ONLY.

What harm comes of mapping page 1 if we don't access it?

Robin.

> For this, arm_smmu_device_dt_probe/acpi_probe has been moved before
> platform_get_resource call, so that smmu options are set beforehand.
>
> Signed-off-by: Linu Cherian <linu.cherian@cavium.com>
> ---
> drivers/iommu/arm-smmu-v3.c | 26 +++++++++++++++++---------
> 1 file changed, 17 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
> index df9f27b..b326195 100644
> --- a/drivers/iommu/arm-smmu-v3.c
> +++ b/drivers/iommu/arm-smmu-v3.c
> @@ -2669,6 +2669,14 @@ static int arm_smmu_device_dt_probe(struct platform_device *pdev,
> return ret;
> }
>
> +static unsigned long arm_smmu_resource_size(struct arm_smmu_device *smmu)
> +{
> + if (ARM_SMMU_PAGE0_REGS_ONLY(smmu))
> + return SZ_64K;
> + else
> + return SZ_128K;
> +}
> +
> static int arm_smmu_device_probe(struct platform_device *pdev)
> {
> int irq, ret;
> @@ -2685,9 +2693,17 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
> }
> smmu->dev = dev;
>
> + if (dev->of_node) {
> + ret = arm_smmu_device_dt_probe(pdev, smmu);
> + } else {
> + ret = arm_smmu_device_acpi_probe(pdev, smmu);
> + if (ret == -ENODEV)
> + return ret;
> + }
> +
> /* Base address */
> res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> - if (resource_size(res) + 1 < SZ_128K) {
> + if (resource_size(res) + 1 < arm_smmu_resource_size(smmu)) {
> dev_err(dev, "MMIO region too small (%pr)\n", res);
> return -EINVAL;
> }
> @@ -2714,14 +2730,6 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
> if (irq > 0)
> smmu->gerr_irq = irq;
>
> - if (dev->of_node) {
> - ret = arm_smmu_device_dt_probe(pdev, smmu);
> - } else {
> - ret = arm_smmu_device_acpi_probe(pdev, smmu);
> - if (ret == -ENODEV)
> - return ret;
> - }
> -
> /* Set bypass mode according to firmware probing result */
> bypass = !!ret;
>
>