Hi Robin,
Please see my comment inline.
> -----Original Message-----
> From: Robin Murphy <robin.murphy@xxxxxxx>
> Sent: Thursday, December 14, 2023 10:31 AM
> To: will@xxxxxxxxxx
> Cc: mark.rutland@xxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx;
> devicetree@xxxxxxxxxxxxxxx; suzuki.poulose@xxxxxxx;
> ilkka@xxxxxxxxxxxxxxxxxxxxxx; Besar Wicaksono
> <bwicaksono@xxxxxxxxxx>; Yifei Wan <YWan@xxxxxxxxxx>; Richard Wiley
> <rwiley@xxxxxxxxxx>
> Subject: [PATCH v2 5/5] perf/arm_cspmu: Add devicetree support
>
> External email: Use caution opening links or attachments
>
>
> Hook up devicetree probing support. For now let's hope that people
> implement PMIIDR properly and we don't need an override property or
> match data mechanism.
>
> Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
> ---
> v2: Use APMT node to distinguish ACPI; adjust for binding change
> ---
> drivers/perf/arm_cspmu/arm_cspmu.c | 63 ++++++++++++++++++++++++-
> -----
> 1 file changed, 52 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/perf/arm_cspmu/arm_cspmu.c
> b/drivers/perf/arm_cspmu/arm_cspmu.c
> index b64de4d800c7..6c76c135a0cf 100644
> --- a/drivers/perf/arm_cspmu/arm_cspmu.c
> +++ b/drivers/perf/arm_cspmu/arm_cspmu.c
> @@ -27,6 +27,7 @@
> #include <linux/io-64-nonatomic-lo-hi.h>
> #include <linux/module.h>
> #include <linux/mutex.h>
> +#include <linux/of.h>
> #include <linux/perf_event.h>
> #include <linux/platform_device.h>
>
> @@ -310,6 +311,10 @@ static const char *arm_cspmu_get_name(const
> struct arm_cspmu *cspmu)
>
> dev = cspmu->dev;
> apmt_node = arm_cspmu_apmt_node(dev);
> + if (!apmt_node)
I got a segmentation fault due to null pointer access when calling
arm_cspmu_apmt_node in device tree environment. arm_cspmu_apmt_node
doesn't check a null platform data before dereferencing.
Snipet from arm_cspmu_apmt_node:
return *(struct acpi_apmt_node **)dev_get_platdata(dev);
> + return devm_kasprintf(dev, GFP_KERNEL, PMUNAME "_%u",
> + atomic_fetch_inc(&pmu_idx[0]));
> +
> pmu_type = apmt_node->type;
>
> if (pmu_type >= ACPI_APMT_NODE_TYPE_COUNT) {
> @@ -425,7 +430,7 @@ static int arm_cspmu_init_impl_ops(struct
> arm_cspmu *cspmu)
> };
>
> /* Firmware may override implementer/product ID from PMIIDR */
> - if (apmt_node->impl_id)
> + if (apmt_node && apmt_node->impl_id)
> cspmu->impl.pmiidr = apmt_node->impl_id;
>
> /* Find implementer specific attribute ops. */
> @@ -940,7 +945,14 @@ static struct arm_cspmu *arm_cspmu_alloc(struct
> platform_device *pdev)
> platform_set_drvdata(pdev, cspmu);
>
> apmt_node = arm_cspmu_apmt_node(dev);
> - cspmu->has_atomic_dword = apmt_node->flags &
> ACPI_APMT_FLAGS_ATOMIC;
> + if (apmt_node) {
> + cspmu->has_atomic_dword = apmt_node->flags &
> ACPI_APMT_FLAGS_ATOMIC;
> + } else {
> + u32 width = 0;
> +
> + device_property_read_u32(dev, "reg-io-width", &width);
> + cspmu->has_atomic_dword = (width == 8);
> + }
>
> return cspmu;
> }
> @@ -1133,11 +1145,6 @@ static int arm_cspmu_acpi_get_cpus(struct
> arm_cspmu *cspmu)
> }
> }
>
> - if (cpumask_empty(&cspmu->associated_cpus)) {
> - dev_dbg(cspmu->dev, "No cpu associated with the PMU\n");
> - return -ENODEV;
> - }
> -
> return 0;
> }
> #else
> @@ -1147,9 +1154,36 @@ static int arm_cspmu_acpi_get_cpus(struct
> arm_cspmu *cspmu)
> }
> #endif
>
> +static int arm_cspmu_of_get_cpus(struct arm_cspmu *cspmu)
> +{
> + struct of_phandle_iterator it;
> + int ret, cpu;
> +
> + of_for_each_phandle(&it, ret, dev_of_node(cspmu->dev), "cpus", NULL,
> 0) {
> + cpu = of_cpu_node_to_id(it.node);
> + if (cpu < 0)
> + continue;
> + cpumask_set_cpu(cpu, &cspmu->associated_cpus);
> + }
> + return ret;
The ret gives -ENOENT after finish iterating "cpus". I think we could return 0
or void since there is a check for empty associated_cpus down the line.
Thanks,
Besar
> +}
> +
> static int arm_cspmu_get_cpus(struct arm_cspmu *cspmu)
> {
> - return arm_cspmu_acpi_get_cpus(cspmu);
> + int ret = 0;
> +
> + if (arm_cspmu_apmt_node(cspmu->dev))
> + ret = arm_cspmu_acpi_get_cpus(cspmu);
> + else if (device_property_present(cspmu->dev, "cpus"))
> + ret = arm_cspmu_of_get_cpus(cspmu);
> + else
> + cpumask_copy(&cspmu->associated_cpus, cpu_possible_mask);
> +
> + if (!ret && cpumask_empty(&cspmu->associated_cpus)) {
> + dev_dbg(cspmu->dev, "No cpu associated with the PMU\n");
> + ret = -ENODEV;
> + }
> + return ret;
> }
>
> static int arm_cspmu_register_pmu(struct arm_cspmu *cspmu)
> @@ -1246,11 +1280,18 @@ static const struct platform_device_id
> arm_cspmu_id[] = {
> };
> MODULE_DEVICE_TABLE(platform, arm_cspmu_id);
>
> +static const struct of_device_id arm_cspmu_of_match[] = {
> + { .compatible = "arm,coresight-pmu" },
> + {}
> +};
> +MODULE_DEVICE_TABLE(of, arm_cspmu_of_match);
> +
> static struct platform_driver arm_cspmu_driver = {
> .driver = {
> - .name = DRVNAME,
> - .suppress_bind_attrs = true,
> - },
> + .name = DRVNAME,
> + .of_match_table = arm_cspmu_of_match,
> + .suppress_bind_attrs = true,
> + },
> .probe = arm_cspmu_device_probe,
> .remove = arm_cspmu_device_remove,
> .id_table = arm_cspmu_id,
> --
> 2.39.2.101.g768bb238c484.dirty
