coresight: etm3x: Update ETM3 driver to use Trace ID API

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>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20230116124928.5440-7-mike.leach@linaro.org

diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-etm3x b/Documentation/ABI/testing/sysfs-bus-coresight-devices-etm3x
index 651602a61eac82af31d878a9ba1670aa18bab798..234c33fbdb55f85c4e736d372bb948d5554295bd 100644 (file)
--- a/Documentation/ABI/testing/sysfs-bus-coresight-devices-etm3x
+++ b/Documentation/ABI/testing/sysfs-bus-coresight-devices-etm3x
@@ -236,7 +236,7 @@ What:               /sys/bus/coresight/devices/<memory_map>.[etm|ptm]/traceid
 Date:          November 2014
 KernelVersion: 3.19
 Contact:       Mathieu Poirier <mathieu.poirier@linaro.org>
-Description:   (RW) Holds the trace ID that will appear in the trace stream
+Description:   (RO) Holds the trace ID that will appear in the trace stream
                coming from this trace entity.
 
 What:          /sys/bus/coresight/devices/<memory_map>.[etm|ptm]/trigger_event

diff --git a/drivers/hwtracing/coresight/coresight-etm.h b/drivers/hwtracing/coresight/coresight-etm.h
index f3ab96eaf44e5446e389d64d7ba836be070198cd..3667428d38b6bc64b3b86c728088799ef6dc4b4e 100644 (file)
--- 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 d0ab9933472bcfa5974e0546d37e1d90bee9f85b..090b6fbf6305335a50a68bc7bbe31ed20ab727d1 100644 (file)
--- 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 fd81eca3ec182d4fabbace79986a69ce8b2480ac..2f271b7fb048cf00153ca61fac5c8b2c26056a0f 100644 (file)
--- 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,