HI Mathieu.

On Wed, 24 Feb 2021 at 18:33, Mathieu Poirier
[off-list ref] wrote:

On Thu, Jan 28, 2021 at 05:09:30PM +0000, Mike Leach wrote:

quoted

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 <redacted>
---
 .../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.

quoted

      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.

quoted

      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.

quoted

+
+     if (!err)
+             err = etm_perf_add_cscfg_event(dev, cs_cfg);
+

That we definitely need.

Thanks,
Mathieu

quoted

+     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


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Thanks

Mike

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