Re: [PATCH v3 1/4] RISC-V: Create unique identification for SoC PMU

Sunil V L
2022-06-14T10:17:37Z

Hi Nikita,

On Tue, Jun 07, 2022 at 04:16:44PM +0300, Nikita Shubin wrote:
> From: João Mário Domingos <joao.mario@tecnico.ulisboa.pt>
>
> The SBI PMU platform driver did not provide any identification for
> perf events matching. This patch introduces a new sysfs file inside the
> platform device (soc:pmu/id) for pmu identification.
>
> The identification is a 64-bit value generated as:
> [63-32]: mvendorid;
> [31]: marchid[MSB];
> [30-16]: marchid[15-0];
> [15-0]: mimpid[15MSBs];
>
> The CSRs are detailed in the RISC-V privileged spec [1].
> The marchid is split in MSB + 15LSBs, due to the MSB being used for
> open-source architecture identification.
>
> [1] https://github.com/riscv/riscv-isa-manual
>
> Signed-off-by: João Mário Domingos <joao.mario@tecnico.ulisboa.pt>
> Tested-by: Nikita Shubin <n.shubin@yadro.com>
> ---
> arch/riscv/kernel/sbi.c | 3 +++
> drivers/perf/riscv_pmu_sbi.c | 47 ++++++++++++++++++++++++++++++++++++
> 2 files changed, 50 insertions(+)
>
> diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c
> index 775d3322b422..50dd9b6ecc9e 100644
> --- a/arch/riscv/kernel/sbi.c
> +++ b/arch/riscv/kernel/sbi.c
> @@ -627,16 +627,19 @@ long sbi_get_mvendorid(void)
> {
> return __sbi_base_ecall(SBI_EXT_BASE_GET_MVENDORID);
> }
> +EXPORT_SYMBOL(sbi_get_mvendorid);
>
> long sbi_get_marchid(void)
> {
> return __sbi_base_ecall(SBI_EXT_BASE_GET_MARCHID);
> }
> +EXPORT_SYMBOL(sbi_get_marchid);
>
> long sbi_get_mimpid(void)
> {
> return __sbi_base_ecall(SBI_EXT_BASE_GET_MIMPID);
> }
> +EXPORT_SYMBOL(sbi_get_mimpid);
>
> static void sbi_send_cpumask_ipi(const struct cpumask *target)
> {
> diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c
> index a1317a483512..15ab3dc68e7a 100644
> --- a/drivers/perf/riscv_pmu_sbi.c
> +++ b/drivers/perf/riscv_pmu_sbi.c
> @@ -693,6 +693,46 @@ static int pmu_sbi_setup_irqs(struct riscv_pmu *pmu, struct platform_device *pde
> return 0;
> }
>
> +static uint64_t pmu_sbi_get_pmu_id(void)
> +{
> + union sbi_pmu_id {
> + uint64_t value;
> + struct {
> + uint16_t imp:16;
> + uint16_t arch:16;
> + uint32_t vendor:32;
> + };
> + } pmuid;
> +
> + pmuid.value = 0;
> + pmuid.vendor = (uint32_t) sbi_get_mvendorid();
> + pmuid.arch = (sbi_get_marchid() >> (63 - 15) & (1 << 15)) | (sbi_get_marchid() & 0x7FFF);

This statement generates below warning in rv32 build.

drivers/perf/riscv_pmu_sbi.c: In function 'pmu_sbi_get_pmu_id':
drivers/perf/riscv_pmu_sbi.c:715:41: warning: right shift count >=
width of type [-Wshift-count-overflow]
715 | pmuid.arch = (sbi_get_marchid() >> (63 - 15) & (1 << 15))
| (sbi_get_marchid() & 0x7FFF);

Please take care of this when you rework this patch.

Thanks
Sunil

> + pmuid.imp = (sbi_get_mimpid() >> 16);
> +
> + return pmuid.value;
> +}
> +
> +static ssize_t pmu_sbi_id_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + int len;
> +
> + len = sprintf(buf, "0x%llx\n", pmu_sbi_get_pmu_id());
> + if (len <= 0)
> + dev_err(dev, "mydrv: Invalid sprintf len: %dn", len);
> +
> + return len;
> +}
> +
> +static DEVICE_ATTR(id, S_IRUGO | S_IWUSR, pmu_sbi_id_show, 0);
> +
> +static struct attribute *pmu_sbi_attrs[] = {
> + &dev_attr_id.attr,
> + NULL
> +};
> +
> +ATTRIBUTE_GROUPS(pmu_sbi);
> +
> static int pmu_sbi_device_probe(struct platform_device *pdev)
> {
> struct riscv_pmu *pmu = NULL;
> @@ -729,6 +769,13 @@ static int pmu_sbi_device_probe(struct platform_device *pdev)
> pmu->ctr_clear_idx = pmu_sbi_ctr_clear_idx;
> pmu->ctr_read = pmu_sbi_ctr_read;
>
> + ret = sysfs_create_group(&pdev->dev.kobj, &pmu_sbi_group);
> + if (ret) {
> + dev_err(&pdev->dev, "sysfs creation failed\n");
> + return ret;
> + }
> + pdev->dev.groups = pmu_sbi_groups;
> +
> ret = cpuhp_state_add_instance(CPUHP_AP_PERF_RISCV_STARTING, &pmu->node);
> if (ret)
> return ret;
> --
> 2.35.1
>
>
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