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Date: Tue, 5 Apr 2022 11:22:00 -0600
From: Mathieu Poirier <mathieu.poirier@...aro.org>
To: Mike Leach <mike.leach@...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
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().
> 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
>
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