[PATCH v6 06/14] coresight: etm3x: Update ETM3 driver to use Trace ID API
From: Mike Leach
Date: Wed Nov 23 2022 - 14:50:58 EST
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>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
---
drivers/hwtracing/coresight/coresight-etm.h | 2 +
.../coresight/coresight-etm3x-core.c | 72 +++++++++++++++++--
.../coresight/coresight-etm3x-sysfs.c | 27 ++-----
3 files changed, 75 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..090b6fbf6305 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_CS_TRACE_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_CS_TRACE_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 +664,12 @@ 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 +694,13 @@ 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 +847,6 @@ 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 +932,6 @@ 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);
diff --git a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
index fd81eca3ec18..2f271b7fb048 100644
--- a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
+++ b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c
@@ -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,
--
2.17.1