Date:   Thu, 1 Apr 2021 14:45:59 +0100
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>,
        Yabin Cui <yabinc@...gle.com>,
        Jonathan Corbet <corbet@....net>, Leo Yan <leo.yan@...aro.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Tingwei Zhang <tingwei@...eaurora.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 04/10] coresight: etm-perf: update to handle
 configuration selection

Hi Mathieu,

On Wed, 31 Mar 2021 at 21:49, Mathieu Poirier
<mathieu.poirier@...aro.org> wrote:
>
> On Tue, Mar 16, 2021 at 06:03:54PM +0000, Mike Leach wrote:
> > Loaded coresight configurations are registered in the cs_etm\cs_config sub
>
> This changelog is obsolete - cs_config is no longer under cs_etm.
>
Agreed.

> > 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    |   2 +
> >  .../hwtracing/coresight/coresight-etm-perf.c  | 139 ++++++++++++++----
> >  .../hwtracing/coresight/coresight-etm-perf.h  |   8 +
> >  .../hwtracing/coresight/coresight-syscfg.c    |  12 ++
> >  4 files changed, 130 insertions(+), 31 deletions(-)
> >
> > diff --git a/drivers/hwtracing/coresight/coresight-config.h b/drivers/hwtracing/coresight/coresight-config.h
> > index f70561c1504b..38fd1c71eb05 100644
> > --- a/drivers/hwtracing/coresight/coresight-config.h
> > +++ b/drivers/hwtracing/coresight/coresight-config.h
> > @@ -126,6 +126,7 @@ struct cscfg_feature_desc {
> >   * @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.
> > + * @event_ea:                Extended attribute for perf event value
> >   *
> >   */
> >  struct cscfg_config_desc {
> > @@ -137,6 +138,7 @@ struct cscfg_config_desc {
> >       int nr_presets;
> >       int nr_total_params;
> >       const u64 *presets; /* nr_presets * nr_total_params */
> > +     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 0e392513b2d6..66bda452a2f4 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;
> > @@ -38,8 +40,13 @@ PMU_FORMAT_ATTR(contextid1,        "config:" __stringify(ETM_OPT_CTXTID));
> >  PMU_FORMAT_ATTR(contextid2,  "config:" __stringify(ETM_OPT_CTXTID2));
> >  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");
> > +
> >
> >  /*
> >   * contextid always traces the "PID".  The PID is in CONTEXTIDR_EL1
> > @@ -69,6 +76,8 @@ 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,
> >  };
> >
> > @@ -86,9 +95,19 @@ static const struct attribute_group etm_pmu_sinks_group = {
> >       .attrs  = etm_config_sinks_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_events_group,
> >       NULL,
> >  };
> >
> > @@ -247,7 +266,7 @@ 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);
> >       }
> > @@ -555,9 +574,9 @@ int etm_perf_symlink(struct coresight_device *csdev, bool link)
> >  }
> >  EXPORT_SYMBOL_GPL(etm_perf_symlink);
> >
> > -static ssize_t etm_perf_sink_name_show(struct device *dev,
> > -                                    struct device_attribute *dattr,
> > -                                    char *buf)
>
> Because we now have etm_perf_cscfg_event_show(), this could have remained
> unchanged.
>
> > +static ssize_t etm_perf_name_show(struct device *dev,
> > +                               struct device_attribute *dattr,
> > +                               char *buf)
> >  {
> >       struct dev_ext_attribute *ea;
> >
> > @@ -565,68 +584,126 @@ 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)
> > +static struct dev_ext_attribute *
> > +etm_perf_add_symlink_group(struct device *dev, 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;
> >
> >       if (!etm_perf_up)
> > -             return -EPROBE_DEFER;
> > +             return ERR_PTR(-EPROBE_DEFER);
> >
> >       ea = devm_kzalloc(dev, sizeof(*ea), GFP_KERNEL);
> >       if (!ea)
> > -             return -ENOMEM;
> > +             return ERR_PTR(-ENOMEM);
> >
> > -     name = dev_name(dev);
> > -     /* See function coresight_get_sink_by_id() to know where this is used */
> > +     /*
> > +      * If this function is called adding a sink then the hash is used for
> > +      * sink selection - see function coresight_get_sink_by_id().
> > +      * If adding a configuration then the hash is used for selection in
> > +      * cscfg_activate_config()
> > +      */
> >       hash = hashlen_hash(hashlen_string(NULL, name));
> >
> >       sysfs_attr_init(&ea->attr.attr);
> >       ea->attr.attr.name = devm_kstrdup(dev, name, GFP_KERNEL);
> >       if (!ea->attr.attr.name)
> > -             return -ENOMEM;
> > +             return ERR_PTR(-ENOMEM);
> >
> >       ea->attr.attr.mode = 0444;
> > -     ea->attr.show = etm_perf_sink_name_show;
> > +     ea->attr.show = etm_perf_name_show;
>
> I would have removed the assignment entirely from this function and moved it to
> etm_perf_add_symlink_cscfg() (like you already did) and
> etm_perf_add_symlink_link().
>
OK

> >       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;
> > +     return ret ? ERR_PTR(ret) : ea;
> > +}
> >
> > -     return ret;
> > +int etm_perf_add_symlink_sink(struct coresight_device *csdev)
> > +{
> > +     const char *name;
> > +     struct device *dev = &csdev->dev;
> > +     int err = 0;
> > +
> > +     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);
> > +     csdev->ea = etm_perf_add_symlink_group(dev, name, "sinks");
> > +     if (IS_ERR(csdev->ea)) {
> > +             err = PTR_ERR(csdev->ea);
> > +             csdev->ea = NULL;
> > +     }
> > +     return err;
> >  }
> >
> > -void etm_perf_del_symlink_sink(struct coresight_device *csdev)
> > +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;
> >  }
> >
> > +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, "configid=0x%lx\n", (unsigned long)(ea->var));
> > +}
> > +
> > +int etm_perf_add_symlink_cscfg(struct device *dev, struct cscfg_config_desc *config_desc)
> > +{
> > +     int err = 0;
> > +
> > +     if (config_desc->event_ea != NULL)
> > +             return 0;
> > +
> > +     config_desc->event_ea = etm_perf_add_symlink_group(dev, config_desc->name, "events");
> > +
> > +     /* override the show function to the custom cscfg event */
> > +     if (!IS_ERR(config_desc->event_ea))
> > +             config_desc->event_ea->attr.show = etm_perf_cscfg_event_show;
> > +     else {
> > +             err = PTR_ERR(config_desc->event_ea);
> > +             config_desc->event_ea = NULL;
> > +     }
> > +
> > +     return err;
> > +}
> > +
> > +void etm_perf_del_symlink_cscfg(struct cscfg_config_desc *config_desc)
> > +{
> > +     if (!config_desc->event_ea)
> > +             return;
> > +
> > +     etm_perf_del_symlink_group(config_desc->event_ea, "events");
> > +     config_desc->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..ba617fe2217e 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 *config_desc);
> > +void etm_perf_del_symlink_cscfg(struct cscfg_config_desc *config_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 *config_desc)
> > +{ return -EINVAL; }
> > +void etm_perf_del_symlink_cscfg(struct cscfg_config_desc *config_desc) {}
> >
> >  #endif /* CONFIG_CORESIGHT */
> >
> > diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c
> > index 11d1422f0ed3..03014a2142c1 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"
> >
> >  /*
> > @@ -86,6 +87,7 @@ static int cscfg_add_csdev_cfg(struct coresight_device *csdev,
> >                       config_csdev->feats_csdev[config_csdev->nr_feat++] = feat_csdev;
> >               }
> >       }
> > +
>
> Spurious newline.
>
> If you end up respinning:
>
> Reviewed-by: Mathieu Poirier <mathieu.poirier@...aro.org>
>
> Otherwise I have fixed it on my side.
>
> Thanks,
> Mathieu
>

I have a v6 underway that picks up the kernel robot issues and a
couple of minor fixes I spotted in patches 5 (missing NULL assignment
for the enabled config on disable)  and 8 (unused #define) while
re-basing the follow-up dynamic config load / unload set. Only one in
patch 5 has potential to actually cause incorrect behaviour - then
only when configs have been unloaded - but it is part of the baseline
code so must be fixed there.

Assuming no major issues from your reviews of the rest of this set, v6
should be available quickly.

Thanks

Mike

> >       /* if matched features, add config to device.*/
> >       if (config_csdev) {
> >               mutex_lock(&cscfg_csdev_mutex);
> > @@ -276,6 +278,11 @@ static int cscfg_load_config(struct cscfg_config_desc *config_desc)
> >       if (err)
> >               return err;
> >
> > +     /* add config to perf fs to allow selection */
> > +     err = etm_perf_add_symlink_cscfg(cscfg_device(), config_desc);
> > +     if (err)
> > +             return err;
> > +
> >       list_add(&config_desc->item, &cscfg_mgr->config_desc_list);
> >       return 0;
> >  }
> > @@ -490,7 +497,12 @@ 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->config_desc_list, item) {
> > +             etm_perf_del_symlink_cscfg(cfg_desc);
> > +     }
> >       device_unregister(cscfg_device());
> >       mutex_unlock(&cscfg_mutex);
> >  }
> > --
> > 2.17.1
> >



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

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