Re: [RFC PATCH 4/8] coresight: configfs: Allow configfs to activate configuration.

[Mike Leach <mike.leach@linaro.org>]

Hi Mathieu,

On Tue, 18 May 2021 at 20:36, Mathieu Poirier
<mathieu.poirier@linaro.org> wrote:
>
> Please remove the '.' on every patch header.
>

Sorry - will do. Correct punctuation seems to be a habit that is hard to break!

> On Wed, May 12, 2021 at 10:17:48PM +0100, Mike Leach wrote:
> > Adds configfs attributes to allow a configuration to be enabled for use
> > when sysfs is used to control CoreSight.
> >
> > perf retains independent enabling of configurations.
> >
> > Signed-off-by: Mike Leach <mike.leach@linaro.org>
> > ---
> >  .../coresight/coresight-etm4x-core.c          |   5 +
> >  .../coresight/coresight-syscfg-configfs.c     |  67 +++++++++
> >  .../coresight/coresight-syscfg-configfs.h     |   2 +
> >  .../hwtracing/coresight/coresight-syscfg.c    | 129 ++++++++++++++----
> >  .../hwtracing/coresight/coresight-syscfg.h    |   7 +-
> >  5 files changed, 182 insertions(+), 28 deletions(-)
> >
> > diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> > index b7a4aeaa2bc7..2637096c4621 100644
> > --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
> > +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
> > @@ -688,6 +688,11 @@ static int etm4_enable_sysfs(struct coresight_device *csdev)
> >       struct etm4_enable_arg arg = { };
> >       int ret;
> >
> > +     /* enable any config activated by configfs */
> > +     ret = cscfg_csdev_enable_active_config(csdev, 0, 0);
> > +     if (ret)
> > +             return ret;
> > +
> >       spin_lock(&drvdata->spinlock);
> >
> >       /*
> > diff --git a/drivers/hwtracing/coresight/coresight-syscfg-configfs.c b/drivers/hwtracing/coresight/coresight-syscfg-configfs.c
> > index 345a62f1b728..ae79ae8b1d7e 100644
> > --- a/drivers/hwtracing/coresight/coresight-syscfg-configfs.c
> > +++ b/drivers/hwtracing/coresight/coresight-syscfg-configfs.c
> > @@ -6,6 +6,7 @@
> >
> >  #include <linux/configfs.h>
> >
> > +#include "coresight-config.h"
> >  #include "coresight-syscfg-configfs.h"
> >
> >  /* create a default ci_type. */
> > @@ -87,9 +88,75 @@ static ssize_t cscfg_cfg_values_show(struct config_item *item, char *page)
> >  }
> >  CONFIGFS_ATTR_RO(cscfg_cfg_, values);
> >
> > +static ssize_t cscfg_cfg_activate_show(struct config_item *item, char *page)
> > +{
> > +     struct cscfg_fs_config *fs_config = container_of(to_config_group(item),
> > +                                                      struct cscfg_fs_config, group);
> > +
> > +     return scnprintf(page, PAGE_SIZE, "%d\n", fs_config->active);
> > +}
> > +
> > +static ssize_t cscfg_cfg_activate_store(struct config_item *item,
> > +                                     const char *page, size_t count)
> > +{
> > +     struct cscfg_fs_config *fs_config = container_of(to_config_group(item),
> > +                                                      struct cscfg_fs_config, group);
> > +     int err;
> > +     bool val;
> > +
> > +     err = kstrtobool(page, &val);
> > +     if (!err)
> > +             err = cscfg_config_sysfs_activation(fs_config->config_desc, val);
> > +     if (!err) {
> > +             fs_config->active = val;
> > +             if (val)
> > +                     cscfg_config_sysfs_preset(fs_config->preset);
> > +     }
> > +     return err ? err : count;
> > +}
> > +CONFIGFS_ATTR(cscfg_cfg_, activate);
> > +
> > +static ssize_t cscfg_cfg_active_preset_show(struct config_item *item, char *page)
> > +{
> > +     struct cscfg_fs_config *fs_config = container_of(to_config_group(item),
> > +                                                      struct cscfg_fs_config, group);
> > +
> > +     return scnprintf(page, PAGE_SIZE, "%d\n", fs_config->preset);
> > +}
> > +
> > +static ssize_t cscfg_cfg_active_preset_store(struct config_item *item,
> > +                                          const char *page, size_t count)
> > +{
> > +     struct cscfg_fs_config *fs_config = container_of(to_config_group(item),
> > +                                                      struct cscfg_fs_config, group);
> > +     int preset, err;
> > +
> > +     err = kstrtoint(page, 0, &preset);
> > +     if (!err) {
> > +             /*
> > +              * presets start at 1, and go up to max (15),
> > +              * but the config may provide fewer.
> > +              */
> > +             if ((preset < 1) || (preset > fs_config->config_desc->nr_presets))
> > +                     err = -EINVAL;
> > +     }
> > +
> > +     if (!err) {
> > +             /* set new value */
> > +             fs_config->preset = preset;
> > +             /* set on system if active */
> > +             if (fs_config->active)
> > +                     cscfg_config_sysfs_preset(fs_config->preset);
> > +     }
> > +     return err ? err : count;
> > +}
> > +CONFIGFS_ATTR(cscfg_cfg_, active_preset);
> > +
> >  static struct configfs_attribute *cscfg_config_view_attrs[] = {
> >       &cscfg_cfg_attr_description,
> >       &cscfg_cfg_attr_feature_refs,
> > +     &cscfg_cfg_attr_activate,
> > +     &cscfg_cfg_attr_active_preset,
> >       NULL,
> >  };
> >
> > diff --git a/drivers/hwtracing/coresight/coresight-syscfg-configfs.h b/drivers/hwtracing/coresight/coresight-syscfg-configfs.h
> > index ea1e54d29f7f..373d84d43268 100644
> > --- a/drivers/hwtracing/coresight/coresight-syscfg-configfs.h
> > +++ b/drivers/hwtracing/coresight/coresight-syscfg-configfs.h
> > @@ -15,6 +15,8 @@
> >  struct cscfg_fs_config {
> >       struct cscfg_config_desc *config_desc;
> >       struct config_group group;
> > +     bool active;
> > +     int preset;
> >  };
> >
> >  /* container for feature view */
> > diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c
> > index 26c1a244c2b1..ab74e33b892b 100644
> > --- a/drivers/hwtracing/coresight/coresight-syscfg.c
> > +++ b/drivers/hwtracing/coresight/coresight-syscfg.c
> > @@ -743,32 +743,23 @@ void cscfg_csdev_reset_feats(struct coresight_device *csdev)
> >  }
> >  EXPORT_SYMBOL_GPL(cscfg_csdev_reset_feats);
> >
> > -/**
> > - * cscfg_activate_config -  Mark a configuration descriptor as active.
> > - *
> > - * This will be seen when csdev devices are enabled in the system.
> > - * Only activated configurations can be enabled on individual devices.
> > - * Activation protects the configuration from alteration or removal while
> > - * active.
> > - *
> > - * Selection by hash value - generated from the configuration name when it
> > - * was loaded and added to the cs_etm/configurations file system for selection
> > - * by perf.
> > +/*
> > + * This activate configuration for either perf or sysfs. Perf can have multiple
> > + * active configs, selected per event, sysfs is limited to one.
> >   *
> >   * Increments the configuration descriptor active count and the global active
> >   * count.
> >   *
> >   * @cfg_hash: Hash value of the selected configuration name.
> >   */
> > -int cscfg_activate_config(unsigned long cfg_hash)
> > +static int _cscfg_activate_config(unsigned long cfg_hash)
> >  {
> >       struct cscfg_config_desc *config_desc;
> >       int err = -EINVAL;
> >
> > -     mutex_lock(&cscfg_mutex);
> > -
> >       list_for_each_entry(config_desc, &cscfg_mgr->config_desc_list, item) {
> >               if ((unsigned long)config_desc->event_ea->var == cfg_hash) {
> > +
>
> Spurious newline
>
> >                       /* must ensure that config cannot be unloaded in use */
> >                       err = cscfg_owner_get(config_desc->load_owner);
> >                       if (err)
> > @@ -790,6 +781,88 @@ int cscfg_activate_config(unsigned long cfg_hash)
> >                       break;
> >               }
> >       }
> > +     return err;
> > +}
> > +
> > +static void _cscfg_deactivate_config(unsigned long cfg_hash)
> > +{
> > +     struct cscfg_config_desc *config_desc;
> > +
> > +     list_for_each_entry(config_desc, &cscfg_mgr->config_desc_list, item) {
> > +             if ((unsigned long)config_desc->event_ea->var == cfg_hash) {
> > +                     atomic_dec(&config_desc->active_cnt);
> > +                     atomic_dec(&cscfg_mgr->sys_active_cnt);
> > +                     cscfg_owner_put(config_desc->load_owner);
> > +                     dev_dbg(cscfg_device(), "Deactivate config %s.\n", config_desc->name);
> > +                     break;
> > +             }
> > +     }
> > +}
> > +
> > +/*
> > + * called from configfs to set/clear the active configuration for use when
> > + * using sysfs to control trace.
> > + */
> > +int cscfg_config_sysfs_activation(struct cscfg_config_desc *config_desc, bool activate)
> > +{
> > +     unsigned long cfg_hash_desc;
> > +     int err = 0;
> > +
> > +     mutex_lock(&cscfg_mutex);
> > +
> > +     cfg_hash_desc = (unsigned long)config_desc->event_ea->var;
> > +
> > +     if (activate) {
> > +             /* cannot be a current active value to activate this */
> > +             if (cscfg_mgr->sysfs_active_config) {
> > +                     err = -EBUSY;
> > +                     goto exit_unlock;
> > +             }
> > +             err = _cscfg_activate_config(cfg_hash_desc);
> > +             if (!err)
> > +                     cscfg_mgr->sysfs_active_config = cfg_hash_desc;
> > +     } else {
> > +             /* disable if matching current value */
> > +             if (cscfg_mgr->sysfs_active_config == cfg_hash_desc) {
> > +                     _cscfg_deactivate_config(cfg_hash_desc);
> > +                     cscfg_mgr->sysfs_active_config = 0;
> > +             } else
> > +                     err = -EINVAL;
> > +     }
> > +
> > +exit_unlock:
> > +     mutex_unlock(&cscfg_mutex);
> > +     return err;
> > +}
> > +
> > +/* set the sysfs preset value */
> > +void cscfg_config_sysfs_preset(int preset)
> > +{
> > +     mutex_lock(&cscfg_mutex);
> > +     cscfg_mgr->sysfs_active_preset = preset;
> > +     mutex_unlock(&cscfg_mutex);
> > +}
> > +
> > +/**
> > + * cscfg_activate_config -  Mark a configuration descriptor as active.
> > + *
> > + * This will be seen when csdev devices are enabled in the system.
> > + * Only activated configurations can be enabled on individual devices.
> > + * Activation protects the configuration from alteration or removal while
> > + * active.
> > + *
> > + * Selection by hash value - generated from the configuration name when it
> > + * was loaded and added to the cs_etm/configurations file system for selection
> > + * by perf.
> > + *
> > + * @cfg_hash: Hash value of the selected configuration name.
> > + */
> > +int cscfg_activate_config(unsigned long cfg_hash)
> > +{
> > +     int err = 0;
> > +
> > +     mutex_lock(&cscfg_mutex);
> > +     err = _cscfg_activate_config(cfg_hash);
> >       mutex_unlock(&cscfg_mutex);
> >
> >       return err;
> > @@ -805,19 +878,8 @@ EXPORT_SYMBOL_GPL(cscfg_activate_config);
> >   */
> >  void cscfg_deactivate_config(unsigned long cfg_hash)
> >  {
> > -     struct cscfg_config_desc *config_desc;
> > -
> >       mutex_lock(&cscfg_mutex);
> > -
> > -     list_for_each_entry(config_desc, &cscfg_mgr->config_desc_list, item) {
> > -             if ((unsigned long)config_desc->event_ea->var == cfg_hash) {
> > -                     atomic_dec(&config_desc->active_cnt);
> > -                     atomic_dec(&cscfg_mgr->sys_active_cnt);
> > -                     cscfg_owner_put(config_desc->load_owner);
> > -                     dev_dbg(cscfg_device(), "Deactivate config %s.\n", config_desc->name);
> > -                     break;
> > -             }
> > -     }
> > +     _cscfg_deactivate_config(cfg_hash);
> >       mutex_unlock(&cscfg_mutex);
> >  }
> >  EXPORT_SYMBOL_GPL(cscfg_deactivate_config);
> > @@ -826,7 +888,8 @@ EXPORT_SYMBOL_GPL(cscfg_deactivate_config);
> >   * cscfg_csdev_enable_active_config - Enable matching active configuration for device.
> >   *
> >   * Enables the configuration selected by @cfg_hash if the configuration is supported
> > - * on the device and has been activated.
> > + * on the device and has been activated. A @cfg_hash value of 0 is used if the device
> > + * is being programmed from sysfs, to select the current sysfs active config.
> >   *
> >   * If active and supported the CoreSight device @csdev will be programmed with the
> >   * configuration, using @preset parameters.
> > @@ -850,6 +913,16 @@ int cscfg_csdev_enable_active_config(struct coresight_device *csdev,
> >               return 0;
> >
> >       mutex_lock(&cscfg_csdev_mutex);
> > +
> > +     /* sysfs controlled coresight will call with cfg_hash == 0 */
> > +     if (!cfg_hash) {
> > +             if (!cscfg_mgr->sysfs_active_config)
> > +                     goto exit_unlock;
> > +
> > +             cfg_hash = cscfg_mgr->sysfs_active_config;
> > +             preset = cscfg_mgr->sysfs_active_preset;
> > +     }
>
> I'm worried about this snippet.  For the time being it works but the function is
> now entangled with the "if (attr->config2 ...) of etm4_parse_event_config().
> That being said I spent a fair amount of time trying to find a better solution
> and I can't come up with one.  The best option is probably to keep it for now.
>
>
> > +
> >       list_for_each_entry(config_csdev_item, &csdev->config_csdev_list, node) {
> >               config_desc = config_csdev_item->config_desc;
> >               if ((atomic_read(&config_desc->active_cnt)) &&
> > @@ -863,6 +936,8 @@ int cscfg_csdev_enable_active_config(struct coresight_device *csdev,
> >               if (!err)
> >                       csdev->active_cscfg_ctxt = (void *)config_csdev_active;
> >       }
> > +
> > +exit_unlock:
> >       mutex_unlock(&cscfg_csdev_mutex);
> >       return err;
> >  }
> > diff --git a/drivers/hwtracing/coresight/coresight-syscfg.h b/drivers/hwtracing/coresight/coresight-syscfg.h
> > index 1da37874f70f..e07e1b872806 100644
> > --- a/drivers/hwtracing/coresight/coresight-syscfg.h
> > +++ b/drivers/hwtracing/coresight/coresight-syscfg.h
> > @@ -28,6 +28,8 @@
> >   * @load_order_list:    Ordered list of owners for dynamically loaded configurations.
> >   * @sys_active_cnt:  Total number of active config descriptor references.
> >   * @cfgfs_subsys:    configfs subsystem used to manage configurations.
> > + * @sysfs_active_config:Active config hash used if CoreSight controlled from sysfs.
> > + * @sysfs_active_preset:Active preset index used if CoreSight controlled from sysfs.
> >   */
> >  struct cscfg_manager {
> >       struct device dev;
> > @@ -37,6 +39,8 @@ struct cscfg_manager {
> >       struct list_head load_order_list;
> >       atomic_t sys_active_cnt;
> >       struct configfs_subsystem cfgfs_subsys;
> > +     u32 sysfs_active_config;
> > +     int sysfs_active_preset;
> >  };
> >
> >  /* get reference to dev in cscfg_manager */
> > @@ -88,7 +92,8 @@ int cscfg_preload(void *owner_handle);
> >  const struct cscfg_feature_desc *cscfg_get_named_feat_desc(const char *name);
> >  int cscfg_update_feat_param_val(struct cscfg_feature_desc *feat_desc,
> >                               int param_idx, u64 value);
> > -
> > +int cscfg_config_sysfs_activation(struct cscfg_config_desc *cfg_desc, bool activate);
> > +void cscfg_config_sysfs_preset(int preset);
>
> With the above:
>
> Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
>

Thanks.

Regards

Mike

> >
> >  /* syscfg manager external API */
> >  int cscfg_load_config_sets(struct cscfg_config_desc **cfg_descs,
> > --
> > 2.17.1
> >



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

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