[PATCH 4/4] perf/smmuv3: fix crash when platdata not specified

[Robin Murphy]

On 2020-07-12 17:33, Ajay Kumar wrote:
> The arm_smmuv3_pmu driver assumes platform data is always
> available and exposes a possible NULL pointer deferencing
> at the below line.
> 
> model = *(u32 *)dev_get_platdata(smmu_pmu->dev);
> 
> This patch fixes the bug by adding a check prior to the
> deferencing of the platform data pointer.
> 
> Signed-off-by: Ajay Kumar <ajaykumar.rs at samsung.com>
> ---
>   drivers/perf/arm_smmuv3_pmu.c | 5 +++--
>   1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/perf/arm_smmuv3_pmu.c b/drivers/perf/arm_smmuv3_pmu.c
> index 25feab718c20..f7a27ae2f8d8 100644
> --- a/drivers/perf/arm_smmuv3_pmu.c
> +++ b/drivers/perf/arm_smmuv3_pmu.c
> @@ -710,9 +710,10 @@ static void smmu_pmu_reset(struct smmu_pmu *smmu_pmu)
>   
>   static void smmu_pmu_get_acpi_options(struct smmu_pmu *smmu_pmu)
>   {
> -	u32 model;
> +	u32 model = 0;
>   
> -	model = *(u32 *)dev_get_platdata(smmu_pmu->dev);
> +	if (dev_get_platdata(smmu_pmu->dev))
> +		model = *(u32 *)dev_get_platdata(smmu_pmu->dev);

As I commented on the other series, ideally this could be something like:

	if (dev->of_node)
		model = of_device_get_match_data(dev->of_node);
	else
		model = *(u32 *)dev_get_platdata(dev); /* from IORT */

(and lose the "acpi_" from the function name, obviously)

Robin.

>   
>   	switch (model) {
>   	case IORT_SMMU_V3_PMCG_HISI_HIP08:
>