[v5,06/14] coresight: etm3x: Update ETM3 driver to use Trace ID API
Commit Message
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@linaro.org>
---
drivers/hwtracing/coresight/coresight-etm.h | 2 +
.../coresight/coresight-etm3x-core.c | 69 +++++++++++++++++--
.../coresight/coresight-etm3x-sysfs.c | 27 ++------
3 files changed, 72 insertions(+), 26 deletions(-)
Comments
On 01/11/2022 16:30, 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@linaro.org>
> ---
> drivers/hwtracing/coresight/coresight-etm.h | 2 +
> .../coresight/coresight-etm3x-core.c | 69 +++++++++++++++++--
> .../coresight/coresight-etm3x-sysfs.c | 27 ++------
> 3 files changed, 72 insertions(+), 26 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 d0ab9933472b..9a7a9e974d41 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
> @@ -490,16 +491,59 @@ 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 function has its own lock
> + */
> + trace_id = coresight_trace_id_get_cpu_id(drvdata->cpu);
> + if (IS_VALID_ID(trace_id))
> + drvdata->traceid = (u8)trace_id;
> + else
> + dev_err(&drvdata->csdev->dev,
> + "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);
> +}
> +
> static int etm_enable_perf(struct coresight_device *csdev,
> struct perf_event *event)
> {
> struct etm_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
> + int trace_id;
>
> if (WARN_ON_ONCE(drvdata->cpu != smp_processor_id()))
> return -EINVAL;
>
> /* Configure the tracer based on the session's specifics */
> etm_parse_event_config(drvdata, event);
> +
> + /*
> + * perf allocates cpu ids as part of _setup_aux() - device needs to use
> + * the allocated ID. This reads the current version without allocation.
> + *
> + * This does not use the trace id lock to prevent lock_dep issues
> + * with perf locks - we know the ID cannot change until perf shuts down
> + * the session
> + */
> + trace_id = coresight_trace_id_read_cpu_id(drvdata->cpu);
> + if (!IS_VALID_ID(trace_id)) {
> + dev_err(&drvdata->csdev->dev, "Failed to set trace ID for %s on CPU%d\n",
> + dev_name(&drvdata->csdev->dev), drvdata->cpu);
> + return -EINVAL;
> + }
> + drvdata->traceid = (u8)trace_id;
> +
> /* And enable it */
> return etm_enable_hw(drvdata);
> }
> @@ -512,6 +556,11 @@ static int etm_enable_sysfs(struct coresight_device *csdev)
>
> spin_lock(&drvdata->spinlock);
>
> + /* sysfs needs to allocate and set a trace ID */
> + ret = etm_read_alloc_trace_id(drvdata);
> + if (ret < 0)
> + goto unlock_enable_sysfs;
> +
> /*
> * Configure the ETM only if the CPU is online. If it isn't online
> * hw configuration will take place on the local CPU during bring up.
> @@ -528,6 +577,10 @@ static int etm_enable_sysfs(struct coresight_device *csdev)
> ret = -ENODEV;
> }
>
> + if (ret)
> + etm_release_trace_id(drvdata);
> +
> +unlock_enable_sysfs:
> spin_unlock(&drvdata->spinlock);
>
> if (!ret)
> @@ -611,6 +664,9 @@ static void etm_disable_perf(struct coresight_device *csdev)
> coresight_disclaim_device_unlocked(csdev);
>
> CS_LOCK(drvdata->base);
> +
> + /* perf will release trace ids when _free_aux() is called at the end of the session */
Minor nit: Please split the line.
With that
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
@@ -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
@@ -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
@@ -490,16 +491,59 @@ 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 function has its own lock
+ */
+ trace_id = coresight_trace_id_get_cpu_id(drvdata->cpu);
+ if (IS_VALID_ID(trace_id))
+ drvdata->traceid = (u8)trace_id;
+ else
+ dev_err(&drvdata->csdev->dev,
+ "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);
+}
+
static int etm_enable_perf(struct coresight_device *csdev,
struct perf_event *event)
{
struct etm_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+ int trace_id;
if (WARN_ON_ONCE(drvdata->cpu != smp_processor_id()))
return -EINVAL;
/* Configure the tracer based on the session's specifics */
etm_parse_event_config(drvdata, event);
+
+ /*
+ * perf allocates cpu ids as part of _setup_aux() - device needs to use
+ * the allocated ID. This reads the current version without allocation.
+ *
+ * This does not use the trace id lock to prevent lock_dep issues
+ * with perf locks - we know the ID cannot change until perf shuts down
+ * the session
+ */
+ trace_id = coresight_trace_id_read_cpu_id(drvdata->cpu);
+ if (!IS_VALID_ID(trace_id)) {
+ dev_err(&drvdata->csdev->dev, "Failed to set trace ID for %s on CPU%d\n",
+ dev_name(&drvdata->csdev->dev), drvdata->cpu);
+ return -EINVAL;
+ }
+ drvdata->traceid = (u8)trace_id;
+
/* And enable it */
return etm_enable_hw(drvdata);
}
@@ -512,6 +556,11 @@ static int etm_enable_sysfs(struct coresight_device *csdev)
spin_lock(&drvdata->spinlock);
+ /* sysfs needs to allocate and set a trace ID */
+ ret = etm_read_alloc_trace_id(drvdata);
+ if (ret < 0)
+ goto unlock_enable_sysfs;
+
/*
* Configure the ETM only if the CPU is online. If it isn't online
* hw configuration will take place on the local CPU during bring up.
@@ -528,6 +577,10 @@ static int etm_enable_sysfs(struct coresight_device *csdev)
ret = -ENODEV;
}
+ if (ret)
+ etm_release_trace_id(drvdata);
+
+unlock_enable_sysfs:
spin_unlock(&drvdata->spinlock);
if (!ret)
@@ -611,6 +664,9 @@ static void etm_disable_perf(struct coresight_device *csdev)
coresight_disclaim_device_unlocked(csdev);
CS_LOCK(drvdata->base);
+
+ /* perf will release trace ids when _free_aux() is called at the end of the session */
+
}
static void etm_disable_sysfs(struct coresight_device *csdev)
@@ -635,6 +691,13 @@ static void etm_disable_sysfs(struct coresight_device *csdev)
spin_unlock(&drvdata->spinlock);
cpus_read_unlock();
+ /*
+ * we only release trace IDs when resetting sysfs.
+ * This permits sysfs users to read the trace ID after the trace
+ * session has completed. This maintains operational behaviour with
+ * prior trace id allocation method
+ */
+
dev_dbg(&csdev->dev, "ETM tracing disabled\n");
}
@@ -781,11 +844,6 @@ 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 +929,6 @@ 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);
@@ -85,6 +85,7 @@ static ssize_t reset_store(struct device *dev,
}
etm_set_default(config);
+ etm_release_trace_id(drvdata);
spin_unlock(&drvdata->spinlock);
}
@@ -1189,30 +1190,16 @@ 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 sysfs_emit(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,