Message-ID: <CAJ9a7VhgmTN+t80_Dd0UsNwwJo8MLR5qYHu40HmNaFRNDrP34A@mail.gmail.com>
Date:   Fri, 26 Feb 2021 19:26:23 +0000
From:   Mike Leach <mike.leach@...aro.org>
To:     Mathieu Poirier <mathieu.poirier@...aro.org>
Cc:     linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Coresight ML <coresight@...ts.linaro.org>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        "Suzuki K. Poulose" <suzuki.poulose@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Yabin Cui <yabinc@...gle.com>,
        Jonathan Corbet <corbet@....net>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Tingwei Zhang <tingwei@...eaurora.org>,
        Leo Yan <leo.yan@...aro.org>
Subject: Re: [PATCH v4 04/10] coresight: etm-perf: update to handle
 configuration selection

HI Mathieu.

On Wed, 24 Feb 2021 at 18:33, Mathieu Poirier
<mathieu.poirier@...aro.org> wrote:
>
> On Thu, Jan 28, 2021 at 05:09:30PM +0000, 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@...aro.org>
> > ---
> >  .../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,
>
> I would rename this to etm_perf_name_show() so that it doesn't look bizarre when
> finding it in etm_perf_add_symlink_group().
>
OK.

> >       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)
> >  {
> > -     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 */
>
> I would also update this comment.  If @name is a sink then the hash will be
> used in coresight_get_sink_by_id(), and if it is a configuration it will be used
> in etm_perf_add_cscfg_event() and cscfg_activate_config().
>

OK.

> >       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)
> >  {
> >       struct device *pmu_dev = etm_pmu.dev;
> > -     struct dev_ext_attribute *ea = csdev->ea;
> >
> > +     sysfs_remove_file_from_group(&pmu_dev->kobj,
> > +                                  &ea->attr.attr, group_name);
> > +}
> > +
> > +void etm_perf_del_symlink_sink(struct coresight_device *csdev)
> > +{
> >       if (csdev->type != CORESIGHT_DEV_TYPE_SINK &&
> >           csdev->type != CORESIGHT_DEV_TYPE_LINKSINK)
> >               return;
> >
> > -     if (!ea)
> > +     if (!csdev->ea)
> >               return;
> >
> > -     sysfs_remove_file_from_group(&pmu_dev->kobj,
> > -                                  &ea->attr.attr, "sinks");
> > +     etm_perf_del_symlink_group(csdev->ea, "sinks");
> >       csdev->ea = NULL;
> >  }
> >
> > +/* 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));
> > +}
> > +
> > +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;
> > +
> > +     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)
> > +{
> > +     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");
>
> Do we need configurations to be advertised under
> /sys/bus/event_source/devices/cs_etm given that they are already found in
> /sys/kernel/config/coresight-syscfg?  And the events already carry the hash if
> someone is really keen using the "configid=" syntax.
>
> In my opinion we can get by with what is in configfs and do away with the
> "configurations" directory here.
>

Agreed - since stuff is now in events then this does become redundant.

> > +
> > +     if (!err)
> > +             err = etm_perf_add_cscfg_event(dev, cs_cfg);
> > +
>
> That we definitely need.
>
> Thanks,
> Mathieu
>
> > +     return err;
> > +}
> > +
> > +void etm_perf_del_symlink_cscfg(struct cscfg_config_desc *cs_cfg)
> > +{
> > +     if (!cs_cfg->id_ea)
> > +             return;
> > +
> > +     etm_perf_del_symlink_group(cs_cfg->id_ea, "configurations");
> > +     etm_perf_del_symlink_group(cs_cfg->event_ea, "events");
> > +     cs_cfg->id_ea = NULL;
> > +     cs_cfg->event_ea = NULL;
> > +}
> > +
> >  int __init etm_perf_init(void)
> >  {
> >       int ret;
> > diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.h b/drivers/hwtracing/coresight/coresight-etm-perf.h
> > index 29d90dfeba31..3646a3837a0b 100644
> > --- a/drivers/hwtracing/coresight/coresight-etm-perf.h
> > +++ b/drivers/hwtracing/coresight/coresight-etm-perf.h
> > @@ -11,6 +11,7 @@
> >  #include "coresight-priv.h"
> >
> >  struct coresight_device;
> > +struct cscfg_config_desc;
> >
> >  /*
> >   * In both ETMv3 and v4 the maximum number of address comparator implentable
> > @@ -69,6 +70,9 @@ static inline void *etm_perf_sink_config(struct perf_output_handle *handle)
> >               return data->snk_config;
> >       return NULL;
> >  }
> > +int etm_perf_add_symlink_cscfg(struct device *dev,
> > +                            struct cscfg_config_desc *cscfg_desc);
> > +void etm_perf_del_symlink_cscfg(struct cscfg_config_desc *cscfg_desc);
> >  #else
> >  static inline int etm_perf_symlink(struct coresight_device *csdev, bool link)
> >  { return -EINVAL; }
> > @@ -79,6 +83,10 @@ static inline void *etm_perf_sink_config(struct perf_output_handle *handle)
> >  {
> >       return NULL;
> >  }
> > +int etm_perf_add_symlink_cscfg(struct device *dev,
> > +                            struct cscfg_config_desc *cscfg_desc)
> > +{ return -EINVAL; }
> > +void etm_perf_del_symlink_cscfg(struct cscfg_config_desc *cscfg_desc) {}
> >
> >  #endif /* CONFIG_CORESIGHT */
> >
> > diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c
> > index 4b8e4e35e3e7..a070f135eca3 100644
> > --- a/drivers/hwtracing/coresight/coresight-syscfg.c
> > +++ b/drivers/hwtracing/coresight/coresight-syscfg.c
> > @@ -7,6 +7,7 @@
> >  #include <linux/platform_device.h>
> >
> >  #include "coresight-config.h"
> > +#include "coresight-etm-perf.h"
> >  #include "coresight-syscfg.h"
> >
> >  /*
> > @@ -100,6 +101,7 @@ static int cscfg_add_csdev_cfg(struct coresight_device *csdev,
> >                       dev_cfg->feats[dev_cfg->nr_feat++] = feat;
> >               }
> >       }
> > +
> >       /* if matched features, add config to device.*/
> >       if (dev_cfg) {
> >               mutex_lock(&cscfg_csdev_mutex);
> > @@ -290,8 +292,12 @@ static int cscfg_load_config(struct cscfg_config_desc *cfg_desc)
> >       if (err)
> >               return err;
> >
> > -     list_add(&cfg_desc->item, &cscfg_mgr->data.config_desc_list);
> > +     /* add config to perf fs to allow selection */
> > +     err = etm_perf_add_symlink_cscfg(to_device_cscfg(), cfg_desc);
> > +     if (err)
> > +             return err;
> >
> > +     list_add(&cfg_desc->item, &cscfg_mgr->data.config_desc_list);
> >       return 0;
> >  }
> >
> > @@ -517,7 +523,12 @@ int cscfg_create_device(void)
> >
> >  void cscfg_clear_device(void)
> >  {
> > +     struct cscfg_config_desc *cfg_desc;
> > +
> >       mutex_lock(&cscfg_mutex);
> > +     list_for_each_entry(cfg_desc, &cscfg_mgr->data.config_desc_list, item) {
> > +             etm_perf_del_symlink_cscfg(cfg_desc);
> > +     }
> >       device_unregister(to_device_cscfg());
> >       mutex_unlock(&cscfg_mutex);
> >  }
> > --
> > 2.17.1
> >
> >
> > _______________________________________________
> > linux-arm-kernel mailing list
> > linux-arm-kernel@...ts.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Thanks

Mike

-- 
Mike Leach
Principal Engineer, ARM Ltd.
Manchester Design Centre. UK

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