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Date: Wed, 6 Apr 2022 20:47:08 +0100
From: Mike Leach <mike.leach@...aro.org>
To: Mathieu Poirier <mathieu.poirier@...aro.org>
Cc: suzuki.poulose@....com, coresight@...ts.linaro.org,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
linux-perf-users@...r.kernel.org, leo.yan@...aro.org
Subject: Re: [PATCH 05/10] coresight: etm3x: Use trace ID API to allocate IDs
Hii
On Tue, 5 Apr 2022 at 18:22, Mathieu Poirier <mathieu.poirier@...aro.org> 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@...aro.org>
> > ---
> > 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
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