Re: [PATCH v4 04/10] coresight: etm-perf: update to handle configuration selection
From: Mike Leach
Date: Thu Mar 04 2021 - 09:21:06 EST
Hi Suzuki,
On Thu, 4 Mar 2021 at 12:13, Suzuki K Poulose <suzuki.poulose@xxxxxxx> wrote:
>
> On 1/28/21 5:09 PM, Mike Leach wrote:
> > Loaded coresight configurations are registered in the cs_etm\cs_config sub
> > directory. This extends the etm-perf code to handle these registrations,
> > and the cs_syscfg driver to perform the registration on load.
> >
> > Signed-off-by: Mike Leach <mike.leach@xxxxxxxxxx>
> > ---
> > .../hwtracing/coresight/coresight-config.h | 5 +-
> > .../hwtracing/coresight/coresight-etm-perf.c | 164 +++++++++++++++---
> > .../hwtracing/coresight/coresight-etm-perf.h | 8 +
> > .../hwtracing/coresight/coresight-syscfg.c | 13 +-
> > 4 files changed, 166 insertions(+), 24 deletions(-)
> >
> > diff --git a/drivers/hwtracing/coresight/coresight-config.h b/drivers/hwtracing/coresight/coresight-config.h
> > index 9d66e0071f38..98380b496046 100644
> > --- a/drivers/hwtracing/coresight/coresight-config.h
> > +++ b/drivers/hwtracing/coresight/coresight-config.h
> > @@ -154,7 +154,8 @@ struct cscfg_config_feat_ref {
> > * @nr_presets: Number of sets of presets supplied by this configuration.
> > * @nr_total_params: Sum of all parameters declared by used features
> > * @presets: Array of preset values.
> > - *
> > + * @id_ea: Extended attribute for perf configid value
> > + * @event_ea: Extended attribute for perf event value
> > */
> > struct cscfg_config_desc {
> > const char *name;
> > @@ -165,6 +166,8 @@ struct cscfg_config_desc {
> > int nr_presets;
> > int nr_total_params;
> > const u64 *presets; /* nr_presets * nr_total_params */
> > + struct dev_ext_attribute *id_ea;
> > + struct dev_ext_attribute *event_ea;
> > };
> >
> > /**
> > diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c
> > index a608081bd446..e270bb1e0f7d 100644
> > --- a/drivers/hwtracing/coresight/coresight-etm-perf.c
> > +++ b/drivers/hwtracing/coresight/coresight-etm-perf.c
> > @@ -18,8 +18,10 @@
> > #include <linux/types.h>
> > #include <linux/workqueue.h>
> >
> > +#include "coresight-config.h"
> > #include "coresight-etm-perf.h"
> > #include "coresight-priv.h"
> > +#include "coresight-syscfg.h"
> >
> > static struct pmu etm_pmu;
> > static bool etm_perf_up;
> > @@ -32,8 +34,13 @@ PMU_FORMAT_ATTR(cycacc, "config:" __stringify(ETM_OPT_CYCACC));
> > PMU_FORMAT_ATTR(contextid, "config:" __stringify(ETM_OPT_CTXTID));
> > PMU_FORMAT_ATTR(timestamp, "config:" __stringify(ETM_OPT_TS));
> > PMU_FORMAT_ATTR(retstack, "config:" __stringify(ETM_OPT_RETSTK));
> > +/* preset - if sink ID is used as a configuration selector */
> > +PMU_FORMAT_ATTR(preset, "config:0-3");
> > /* Sink ID - same for all ETMs */
> > PMU_FORMAT_ATTR(sinkid, "config2:0-31");
> > +/* config ID - set if a system configuration is selected */
> > +PMU_FORMAT_ATTR(configid, "config2:32-63");
> > +
> >
> > static struct attribute *etm_config_formats_attr[] = {
> > &format_attr_cycacc.attr,
> > @@ -41,6 +48,8 @@ static struct attribute *etm_config_formats_attr[] = {
> > &format_attr_timestamp.attr,
> > &format_attr_retstack.attr,
> > &format_attr_sinkid.attr,
> > + &format_attr_preset.attr,
> > + &format_attr_configid.attr,
> > NULL,
> > };
> >
> > @@ -58,9 +67,29 @@ static const struct attribute_group etm_pmu_sinks_group = {
> > .attrs = etm_config_sinks_attr,
> > };
> >
> > +static struct attribute *etm_config_cscfg_attr[] = {
> > + NULL,
> > +};
> > +
> > +static const struct attribute_group etm_pmu_cscfg_group = {
> > + .name = "configurations",
> > + .attrs = etm_config_cscfg_attr,
> > +};
> > +
> > +static struct attribute *etm_config_events_attr[] = {
> > + NULL,
> > +};
> > +
> > +static const struct attribute_group etm_pmu_events_group = {
> > + .name = "events",
> > + .attrs = etm_config_events_attr,
> > +};
> > +
> > static const struct attribute_group *etm_pmu_attr_groups[] = {
> > &etm_pmu_format_group,
> > &etm_pmu_sinks_group,
> > + &etm_pmu_cscfg_group,
> > + &etm_pmu_events_group,
> > NULL,
> > };
> >
> > @@ -219,7 +248,7 @@ static void *etm_setup_aux(struct perf_event *event, void **pages,
> > INIT_WORK(&event_data->work, free_event_data);
> >
> > /* First get the selected sink from user space. */
> > - if (event->attr.config2) {
> > + if (event->attr.config2 & GENMASK_ULL(31, 0)) {
> > id = (u32)event->attr.config2;
> > sink = coresight_get_sink_by_id(id);
> > }
> > @@ -537,21 +566,17 @@ static ssize_t etm_perf_sink_name_show(struct device *dev,
> > return scnprintf(buf, PAGE_SIZE, "0x%lx\n", (unsigned long)(ea->var));
> > }
> >
> > -int etm_perf_add_symlink_sink(struct coresight_device *csdev)
> > +int etm_perf_add_symlink_group(struct device *dev,
> > + struct dev_ext_attribute **ext_attr,
> > + const char *name,
> > + const char *group_name)
>
> Couple of nits:
>
> This could be:
>
> struct dev_ext_attribute *
> etm_perf_add_to_group_hashed(struct device *dev,
> const char *group,
> const char *name)
> {
> }
>
>
> This could return the ea on success avoiding the **ext_attr as argument.
> Also the name of the function indicates what it does.
>
OK - I'll look at this.
>
> > {
> > - int ret;
> > + struct dev_ext_attribute *ea;
> > unsigned long hash;
> > - const char *name;
> > + int ret;
> > struct device *pmu_dev = etm_pmu.dev;
> > - struct device *dev = &csdev->dev;
> > - struct dev_ext_attribute *ea;
> >
> > - if (csdev->type != CORESIGHT_DEV_TYPE_SINK &&
> > - csdev->type != CORESIGHT_DEV_TYPE_LINKSINK)
> > - return -EINVAL;
> > -
> > - if (csdev->ea != NULL)
> > - return -EINVAL;
> > + *ext_attr = NULL;
> >
> > if (!etm_perf_up)
> > return -EPROBE_DEFER;
> > @@ -560,7 +585,6 @@ int etm_perf_add_symlink_sink(struct coresight_device *csdev)
> > if (!ea)
> > return -ENOMEM;
> >
> > - name = dev_name(dev);
> > /* See function coresight_get_sink_by_id() to know where this is used */
> > hash = hashlen_hash(hashlen_string(NULL, name));
> >
> > @@ -574,31 +598,127 @@ int etm_perf_add_symlink_sink(struct coresight_device *csdev)
> > ea->var = (unsigned long *)hash;
> >
> > ret = sysfs_add_file_to_group(&pmu_dev->kobj,
> > - &ea->attr.attr, "sinks");
> > -
> > + &ea->attr.attr, group_name);
> > if (!ret)
> > - csdev->ea = ea;
> > -
> > + *ext_attr = ea;
> > return ret;
>
>
>
>
>
> > }
> >
> > -void etm_perf_del_symlink_sink(struct coresight_device *csdev)
> > +int etm_perf_add_symlink_sink(struct coresight_device *csdev)
> > +{
> > + const char *name;
> > + struct device *dev = &csdev->dev;
> > +
> > + if (csdev->type != CORESIGHT_DEV_TYPE_SINK &&
> > + csdev->type != CORESIGHT_DEV_TYPE_LINKSINK)
> > + return -EINVAL;
> > +
> > + if (csdev->ea != NULL)
> > + return -EINVAL;
> > +
> > + name = dev_name(dev);
> > + return etm_perf_add_symlink_group(dev, &csdev->ea, name, "sinks");
> > +}
> > +
> > +void etm_perf_del_symlink_group(struct dev_ext_attribute *ea, const char *group_name)
>
> void etm_perf_del_from_group(group, ea)
>
> >
> > +/* string to contain the attribute value */
> > +#define CSCFG_EVENT_STR_SIZE 32
> > +
> > +static ssize_t etm_perf_cscfg_event_show(struct device *dev,
> > + struct device_attribute *dattr,
> > + char *buf)
> > +{
> > + struct dev_ext_attribute *ea;
> > +
> > + ea = container_of(dattr, struct dev_ext_attribute, attr);
> > + return scnprintf(buf, PAGE_SIZE, "%s\n", (const char *)(ea->var));
> > +}
>
> "configid=0x%lx", (unsigned long)ea->var ?
>
ea->var _is_ "configid=0x%lx" due to the way perf handles the events
sub-dir entries.
> > +
> > +static int etm_perf_add_cscfg_event(struct device *dev, struct cscfg_config_desc *cs_cfg)
> > +{
> > + struct dev_ext_attribute *ea;
> > + unsigned long hash;
> > + int ret;
> > + struct device *pmu_dev = etm_pmu.dev;
> > +
> > + ea = devm_kzalloc(dev, sizeof(*ea), GFP_KERNEL);
> > + if (!ea)
> > + return -ENOMEM;
> > +
> > + hash = (unsigned long)cs_cfg->id_ea->var;
> > +
> > + sysfs_attr_init(&ea->attr.attr);
> > + ea->attr.attr.name = devm_kstrdup(dev, cs_cfg->name, GFP_KERNEL);
> > + if (!ea->attr.attr.name)
> > + return -ENOMEM;
> > +
> > + /*
> > + * attribute value is "configid=<hash>".
> > + * this will be what perf evaluates when the config name is used
> > + * on the command line.
> > + */
> > + ea->var = devm_kzalloc(dev, CSCFG_EVENT_STR_SIZE, GFP_KERNEL);
> > + if (!ea->var)
> > + return -ENOMEM;
>
> Could we drop this string and use the "hash" instead ?
>
No. My understanding is that we have added an events directory to
cs_etm, and add the configurations in there:-
cs_etm/events/autofdo
Now the contents of autofdo are "configid=0x<hash-value>" - where
hash-value is the hash of "autofdo".
On the perf command line:-
perf record -e cs_etm/autofdo/ .....
will result in perf parsing autofdo, looking in the events dir for
cs_etm, seeing the configid=-string, and parsing that to assign to
configid attribute - which we have allocated to config2:63:32 - this
will then appear as a value in the perf_event and we can load the
configuration when starting up the event on the ETM etc.
> > +
> > + scnprintf(ea->var, CSCFG_EVENT_STR_SIZE, "configid=0x%lx", hash);
> > + ea->attr.attr.mode = 0444;
> > + ea->attr.show = etm_perf_cscfg_event_show;
> > +
> > + ret = sysfs_add_file_to_group(&pmu_dev->kobj,
> > + &ea->attr.attr, "events");
> > + if (!ret)
> > + cs_cfg->event_ea = ea;
> > + return ret;
> > +}
> > +
> > +int etm_perf_add_symlink_cscfg(struct device *dev, struct cscfg_config_desc *cs_cfg)
>
> etm_perf_add_cscfg() ?
>
> > +{
> > + int err;
> > +
> > + if (cs_cfg->id_ea != NULL)
> > + return 0;
> > +
> > + err = etm_perf_add_symlink_group(dev, &cs_cfg->id_ea,
> > + cs_cfg->name, "configurations");
> > +
> > + if (!err)
> > + err = etm_perf_add_cscfg_event(dev, cs_cfg);
> > +
> > + return err;
> > +}
> > +
> > +void etm_perf_del_symlink_cscfg(struct cscfg_config_desc *cs_cfg)
>
> etm_perf_del_cscfg() ?
>
Both these seem reasonable.
Regards
Mike
> Suzuki
--
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK