Re: [PATCH 05/10] coresight: etm3x: Use trace ID API to allocate IDs

[Mike Leach]

Hii

On Tue, 5 Apr 2022 at 18:22, Mathieu Poirier <mathieu.poirier@xxxxxxxxxx> wrote:
>
> On Tue, Mar 08, 2022 at 08:49:55PM +0000, Mike Leach wrote:
> > Use the TraceID API to allocate ETM trace IDs dynamically.
> >
> > As with the etm4x we allocate on enable / disable for perf,
> > allocate on enable / reset for sysfs.
> >
> > Additionally we allocate on sysfs file read as both perf and sysfs
> > can read the ID before enabling the hardware.
> >
> > Remove sysfs option to write trace ID - which is inconsistent with
> > both the dynamic allocation method and the fixed allocation method
> > previously used.
> >
> > Signed-off-by: Mike Leach <mike.leach@xxxxxxxxxx>
> > ---
> >  drivers/hwtracing/coresight/coresight-etm.h   |  2 +
> >  .../coresight/coresight-etm3x-core.c          | 72 ++++++++++++++++---
> >  .../coresight/coresight-etm3x-sysfs.c         | 28 +++-----
> >  3 files changed, 71 insertions(+), 31 deletions(-)
> >
> > diff --git a/drivers/hwtracing/coresight/coresight-etm.h b/drivers/hwtracing/coresight/coresight-etm.h
> > index f3ab96eaf44e..3667428d38b6 100644
> > --- a/drivers/hwtracing/coresight/coresight-etm.h
> > +++ b/drivers/hwtracing/coresight/coresight-etm.h
> > @@ -287,4 +287,6 @@ int etm_get_trace_id(struct etm_drvdata *drvdata);
> >  void etm_set_default(struct etm_config *config);
> >  void etm_config_trace_mode(struct etm_config *config);
> >  struct etm_config *get_etm_config(struct etm_drvdata *drvdata);
> > +int etm_read_alloc_trace_id(struct etm_drvdata *drvdata);
> > +void etm_release_trace_id(struct etm_drvdata *drvdata);
> >  #endif
> > diff --git a/drivers/hwtracing/coresight/coresight-etm3x-core.c b/drivers/hwtracing/coresight/coresight-etm3x-core.c
> > index 7d413ba8b823..98213503bd09 100644
> > --- a/drivers/hwtracing/coresight/coresight-etm3x-core.c
> > +++ b/drivers/hwtracing/coresight/coresight-etm3x-core.c
> > @@ -32,6 +32,7 @@
> >
> >  #include "coresight-etm.h"
> >  #include "coresight-etm-perf.h"
> > +#include "coresight-trace-id.h"
> >
> >  /*
> >   * Not really modular but using module_param is the easiest way to
> > @@ -490,18 +491,57 @@ static int etm_trace_id(struct coresight_device *csdev)
> >       return etm_get_trace_id(drvdata);
> >  }
> >
> > +int etm_read_alloc_trace_id(struct etm_drvdata *drvdata)
> > +{
> > +     int trace_id;
> > +
> > +     /*
> > +      * This will allocate a trace ID to the cpu,
> > +      * or return the one currently allocated.
> > +      */
> > +     trace_id = coresight_trace_id_get_cpu_id(drvdata->cpu,
> > +                                              coresight_get_trace_id_map());
> > +     if (trace_id > 0) {
> > +             spin_lock(&drvdata->spinlock);
> > +             drvdata->traceid = (u8)trace_id;
> > +             spin_unlock(&drvdata->spinlock);
> > +     } else {
> > +             pr_err("Failed to allocate trace ID for %s on CPU%d\n",
> > +                    dev_name(&drvdata->csdev->dev), drvdata->cpu);
> > +     }
> > +     return trace_id;
> > +}
> > +
> > +void etm_release_trace_id(struct etm_drvdata *drvdata)
> > +{
> > +     coresight_trace_id_put_cpu_id(drvdata->cpu,
> > +                                   coresight_get_trace_id_map());
> > +     spin_lock(&drvdata->spinlock);
> > +     drvdata->traceid = 0;
> > +     spin_unlock(&drvdata->spinlock);
> > +}
> > +
> >  static int etm_enable_perf(struct coresight_device *csdev,
> >                          struct perf_event *event)
> >  {
> >       struct etm_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
> > +     int ret;
> >
> >       if (WARN_ON_ONCE(drvdata->cpu != smp_processor_id()))
> >               return -EINVAL;
> >
> > +     ret = etm_read_alloc_trace_id(drvdata);
> > +     if (ret < 0)
> > +             return ret;
> >
>
> For etm4x, this was done after etm_parse_event_config().  Please do the same
> here.
>
>
> >       /* Configure the tracer based on the session's specifics */
> >       etm_parse_event_config(drvdata, event);
> >       /* And enable it */
> > -     return etm_enable_hw(drvdata);
> > +     ret = etm_enable_hw(drvdata);
> > +
> > +     if (ret)
> > +             etm_release_trace_id(drvdata);
> > +     return ret;
> >  }
> >
> >  static int etm_enable_sysfs(struct coresight_device *csdev)
> > @@ -510,6 +550,10 @@ static int etm_enable_sysfs(struct coresight_device *csdev)
> >       struct etm_enable_arg arg = { };
> >       int ret;
> >
> > +     ret = etm_read_alloc_trace_id(drvdata);
> > +     if (ret < 0)
> > +             return ret;
> > +
>
> Please add the same comment as in etm4_disable_sysfs() in etm_disable_sysfs().
>

Agreed for both comments on this patch

Thanks

Mike


> >       spin_lock(&drvdata->spinlock);
> >
> >       /*
> > @@ -532,6 +576,8 @@ static int etm_enable_sysfs(struct coresight_device *csdev)
> >
> >       if (!ret)
> >               dev_dbg(&csdev->dev, "ETM tracing enabled\n");
> > +     else
> > +             etm_release_trace_id(drvdata);
> >       return ret;
> >  }
> >
> > @@ -611,6 +657,8 @@ static void etm_disable_perf(struct coresight_device *csdev)
> >       coresight_disclaim_device_unlocked(csdev);
> >
> >       CS_LOCK(drvdata->base);
> > +
> > +     etm_release_trace_id(drvdata);
> >  }
> >
> >  static void etm_disable_sysfs(struct coresight_device *csdev)
> > @@ -781,11 +829,6 @@ static void etm_init_arch_data(void *info)
> >       CS_LOCK(drvdata->base);
> >  }
> >
> > -static void etm_init_trace_id(struct etm_drvdata *drvdata)
> > -{
> > -     drvdata->traceid = coresight_get_trace_id(drvdata->cpu);
> > -}
> > -
> >  static int __init etm_hp_setup(void)
> >  {
> >       int ret;
> > @@ -871,7 +914,6 @@ static int etm_probe(struct amba_device *adev, const struct amba_id *id)
> >       if (etm_arch_supported(drvdata->arch) == false)
> >               return -EINVAL;
> >
> > -     etm_init_trace_id(drvdata);
> >       etm_set_default(&drvdata->config);
> >
> >       pdata = coresight_get_platform_data(dev);
> > @@ -891,10 +933,12 @@ static int etm_probe(struct amba_device *adev, const struct amba_id *id)
> >               return PTR_ERR(drvdata->csdev);
> >
> >       ret = etm_perf_symlink(drvdata->csdev, true);
> > -     if (ret) {
> > -             coresight_unregister(drvdata->csdev);
> > -             return ret;
> > -     }
> > +     if (ret)
> > +             goto cs_unregister;
> > +
> > +     ret = etm_read_alloc_trace_id(drvdata);
> > +     if (ret < 0)
> > +             goto cs_unregister;
> >
> >       etmdrvdata[drvdata->cpu] = drvdata;
> >
> > @@ -907,6 +951,10 @@ static int etm_probe(struct amba_device *adev, const struct amba_id *id)
> >       }
> >
> >       return 0;
> > +
> > +cs_unregister:
> > +     coresight_unregister(drvdata->csdev);
> > +     return ret;
> >  }
> >
> >  static void clear_etmdrvdata(void *info)
> > @@ -922,6 +970,8 @@ static void etm_remove(struct amba_device *adev)
> >
> >       etm_perf_symlink(drvdata->csdev, false);
> >
> > +     etm_release_trace_id(drvdata);
> > +
> >       /*
> >        * Taking hotplug lock here to avoid racing between etm_remove and
> >        * CPU hotplug call backs.
> > diff --git a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
> > index e8c7649f123e..3ee70b174240 100644
> > --- a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
> > +++ b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
> > @@ -86,6 +86,8 @@ static ssize_t reset_store(struct device *dev,
> >
> >               etm_set_default(config);
> >               spin_unlock(&drvdata->spinlock);
> > +             /* release trace id outside the spinlock as this fn uses it */
> > +             etm_release_trace_id(drvdata);
> >       }
> >
> >       return size;
> > @@ -1189,30 +1191,16 @@ static DEVICE_ATTR_RO(cpu);
> >  static ssize_t traceid_show(struct device *dev,
> >                           struct device_attribute *attr, char *buf)
> >  {
> > -     unsigned long val;
> > -     struct etm_drvdata *drvdata = dev_get_drvdata(dev->parent);
> > -
> > -     val = etm_get_trace_id(drvdata);
> > -
> > -     return sprintf(buf, "%#lx\n", val);
> > -}
> > -
> > -static ssize_t traceid_store(struct device *dev,
> > -                          struct device_attribute *attr,
> > -                          const char *buf, size_t size)
> > -{
> > -     int ret;
> > -     unsigned long val;
> > +     int trace_id;
> >       struct etm_drvdata *drvdata = dev_get_drvdata(dev->parent);
> >
> > -     ret = kstrtoul(buf, 16, &val);
> > -     if (ret)
> > -             return ret;
> > +     trace_id = etm_read_alloc_trace_id(drvdata);
> > +     if (trace_id < 0)
> > +             return trace_id;
> >
> > -     drvdata->traceid = val & ETM_TRACEID_MASK;
> > -     return size;
> > +     return sprintf(buf, "%#x\n", trace_id);
> >  }
> > -static DEVICE_ATTR_RW(traceid);
> > +static DEVICE_ATTR_RO(traceid);
> >
> >  static struct attribute *coresight_etm_attrs[] = {
> >       &dev_attr_nr_addr_cmp.attr,
> > --
> > 2.17.1
> >



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