Re: [PATCH 2/5] ARC: perf: introduce Kernel PMU events support

[Vineet Gupta]

On 12/5/18 9:06 AM, Eugeniy Paltsev wrote:
> Export all available ARC architected hardware events as
> kernel PMU events to make non-generic events accessible.
> 
> ARC PMU HW allow us to read the list of all available
> events names. So we generate kernel PMU event list
> dynamically in arc_pmu_device_probe() using
> human-readable events names we got from HW instead of
> using pre-defined events list.
> 
> -------------------------->8--------------------------
> $ perf list
>   [snip]
>   arc_pmu/bdata64/                  [Kernel PMU event]
>   arc_pmu/bdcstall/                 [Kernel PMU event]
>   arc_pmu/bdslot/                   [Kernel PMU event]
>   arc_pmu/bfbmp/                    [Kernel PMU event]
>   arc_pmu/bfirqex/                  [Kernel PMU event]
>   arc_pmu/bflgstal/                 [Kernel PMU event]
>   arc_pmu/bflush/                   [Kernel PMU event]
> -------------------------->8--------------------------


@Peter do you have any comments on this patch. I'd really like to have this
upstream for next release, so any thoughts you have are more than welcome.

-Vineet

> Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@xxxxxxxxxxxx>

> ---
>  arch/arc/kernel/perf_event.c | 107 ++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 106 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arc/kernel/perf_event.c b/arch/arc/kernel/perf_event.c
> index 811a07a2ca21..97b88b00c418 100644
> --- a/arch/arc/kernel/perf_event.c
> +++ b/arch/arc/kernel/perf_event.c
> @@ -22,12 +22,28 @@
>  /* HW holds 8 symbols + one for null terminator */
>  #define ARCPMU_EVENT_NAME_LEN	9
>  
> +enum arc_pmu_attr_groups {
> +	ARCPMU_ATTR_GR_EVENTS,
> +	ARCPMU_ATTR_GR_FORMATS,
> +	ARCPMU_NR_ATTR_GR
> +};
> +
> +struct arc_pmu_raw_event_entry {
> +	char name[ARCPMU_EVENT_NAME_LEN];
> +};
> +
>  struct arc_pmu {
>  	struct pmu	pmu;
>  	unsigned int	irq;
>  	int		n_counters;
> +	int		n_events;
>  	u64		max_period;
>  	int		ev_hw_idx[PERF_COUNT_ARC_HW_MAX];
> +
> +	struct arc_pmu_raw_event_entry	*raw_entry;
> +	struct attribute		**attrs;
> +	struct perf_pmu_events_attr	*attr;
> +	const struct attribute_group	*attr_groups[ARCPMU_NR_ATTR_GR + 1];
>  };
>  
>  struct arc_pmu_cpu {
> @@ -196,6 +212,17 @@ static int arc_pmu_event_init(struct perf_event *event)
>  			 (int)hwc->config, arc_pmu_ev_hw_map[ret]);
>  		return 0;
>  
> +	case PERF_TYPE_RAW:
> +		if (event->attr.config >= arc_pmu->n_events)
> +			return -ENOENT;
> +
> +		hwc->config |= event->attr.config;
> +		pr_debug("init raw event with idx %lld \'%s\'\n",
> +			 event->attr.config,
> +			 arc_pmu->raw_entry[event->attr.config].name);
> +
> +		return 0;
> +
>  	default:
>  		return -ENOENT;
>  	}
> @@ -446,6 +473,68 @@ static void arc_cpu_pmu_irq_init(void *data)
>  	write_aux_reg(ARC_REG_PCT_INT_ACT, 0xffffffff);
>  }
>  
> +/* Event field occupies the bottom 15 bits of our config field */
> +PMU_FORMAT_ATTR(event, "config:0-14");
> +static struct attribute *arc_pmu_format_attrs[] = {
> +	&format_attr_event.attr,
> +	NULL,
> +};
> +
> +static struct attribute_group arc_pmu_format_attr_gr = {
> +	.name = "format",
> +	.attrs = arc_pmu_format_attrs,
> +};
> +
> +static ssize_t
> +arc_pmu_events_sysfs_show(struct device *dev,
> +			  struct device_attribute *attr, char *page)
> +{
> +	struct perf_pmu_events_attr *pmu_attr;
> +
> +	pmu_attr = container_of(attr, struct perf_pmu_events_attr, attr);
> +	return sprintf(page, "event=0x%04llx\n", pmu_attr->id);
> +}
> +
> +/*
> + * We don't add attrs here as we don't have pre-defined list of perf events.
> + * We will generate and add attrs dynamically in probe() after we read HW
> + * configuration.
> + */
> +static struct attribute_group arc_pmu_events_attr_gr = {
> +	.name = "events",
> +};
> +
> +static void arc_pmu_add_raw_event_attr(int j, char *str)
> +{
> +	memmove(arc_pmu->raw_entry[j].name, str, ARCPMU_EVENT_NAME_LEN - 1);
> +	arc_pmu->attr[j].attr.attr.name = arc_pmu->raw_entry[j].name;
> +	arc_pmu->attr[j].attr.attr.mode = VERIFY_OCTAL_PERMISSIONS(0444);
> +	arc_pmu->attr[j].attr.show = arc_pmu_events_sysfs_show;
> +	arc_pmu->attr[j].id = j;
> +	arc_pmu->attrs[j] = &(arc_pmu->attr[j].attr.attr);
> +}
> +
> +static int arc_pmu_raw_alloc(struct device *dev)
> +{
> +	arc_pmu->attr = devm_kmalloc_array(dev, arc_pmu->n_events + 1,
> +		sizeof(struct perf_pmu_events_attr), GFP_KERNEL | __GFP_ZERO);
> +	if (!arc_pmu->attr)
> +		return -ENOMEM;
> +
> +	arc_pmu->attrs = devm_kmalloc_array(dev, arc_pmu->n_events + 1,
> +		sizeof(*arc_pmu->attrs), GFP_KERNEL | __GFP_ZERO);
> +	if (!arc_pmu->attrs)
> +		return -ENOMEM;
> +
> +	arc_pmu->raw_entry = devm_kmalloc_array(dev, arc_pmu->n_events,
> +		sizeof(struct arc_pmu_raw_event_entry),
> +		GFP_KERNEL | __GFP_ZERO);
> +	if (!arc_pmu->raw_entry)
> +		return -ENOMEM;
> +
> +	return 0;
> +}
> +
>  static int arc_pmu_device_probe(struct platform_device *pdev)
>  {
>  	struct arc_reg_pct_build pct_bcr;
> @@ -477,6 +566,11 @@ static int arc_pmu_device_probe(struct platform_device *pdev)
>  	if (!arc_pmu)
>  		return -ENOMEM;
>  
> +	arc_pmu->n_events = cc_bcr.c;
> +
> +	if (arc_pmu_raw_alloc(&pdev->dev))
> +		return -ENOMEM;
> +
>  	has_interrupts = is_isa_arcv2() ? pct_bcr.i : 0;
>  
>  	arc_pmu->n_counters = pct_bcr.c;
> @@ -508,8 +602,14 @@ static int arc_pmu_device_probe(struct platform_device *pdev)
>  				arc_pmu->ev_hw_idx[i] = j;
>  			}
>  		}
> +
> +		arc_pmu_add_raw_event_attr(j, cc_name.str);
>  	}
>  
> +	arc_pmu_events_attr_gr.attrs = arc_pmu->attrs;
> +	arc_pmu->attr_groups[ARCPMU_ATTR_GR_EVENTS] = &arc_pmu_events_attr_gr;
> +	arc_pmu->attr_groups[ARCPMU_ATTR_GR_FORMATS] = &arc_pmu_format_attr_gr;
> +
>  	arc_pmu->pmu = (struct pmu) {
>  		.pmu_enable	= arc_pmu_enable,
>  		.pmu_disable	= arc_pmu_disable,
> @@ -519,6 +619,7 @@ static int arc_pmu_device_probe(struct platform_device *pdev)
>  		.start		= arc_pmu_start,
>  		.stop		= arc_pmu_stop,
>  		.read		= arc_pmu_read,
> +		.attr_groups	= arc_pmu->attr_groups,
>  	};
>  
>  	if (has_interrupts) {
> @@ -540,7 +641,11 @@ static int arc_pmu_device_probe(struct platform_device *pdev)
>  	} else
>  		arc_pmu->pmu.capabilities |= PERF_PMU_CAP_NO_INTERRUPT;
>  
> -	return perf_pmu_register(&arc_pmu->pmu, pdev->name, PERF_TYPE_RAW);
> +	/*
> +	 * perf parser doesn't really like '-' symbol in events name, so let's
> +	 * use '_' in arc pmu name as it goes to kernel PMU event prefix.
> +	 */
> +	return perf_pmu_register(&arc_pmu->pmu, "arc_pmu", PERF_TYPE_RAW);
>  }
>  
>  #ifdef CONFIG_OF
>