diff options
| -rw-r--r-- | drivers/hwtracing/coresight/coresight-etb10.c | 43 |
1 files changed, 39 insertions, 4 deletions
diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c index eeae375c7aed..4ee4c80a4354 100644 --- a/drivers/hwtracing/coresight/coresight-etb10.c +++ b/drivers/hwtracing/coresight/coresight-etb10.c @@ -72,6 +72,8 @@ * @miscdev: specifics to handle "/dev/xyz.etb" entry. * @spinlock: only one at a time pls. * @reading: synchronise user space access to etb buffer. + * @pid: Process ID of the process being monitored by the session + * that is using this component. * @buf: area of memory where ETB buffer content gets sent. * @mode: this ETB is being used. * @buffer_depth: size of @buf. @@ -85,6 +87,7 @@ struct etb_drvdata { struct miscdevice miscdev; spinlock_t spinlock; local_t reading; + pid_t pid; u8 *buf; u32 mode; u32 buffer_depth; @@ -169,28 +172,49 @@ out: static int etb_enable_perf(struct coresight_device *csdev, void *data) { int ret = 0; + pid_t pid; unsigned long flags; struct etb_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent); + struct perf_output_handle *handle = data; spin_lock_irqsave(&drvdata->spinlock, flags); - /* No need to continue if the component is already in use. */ - if (drvdata->mode != CS_MODE_DISABLED) { + /* No need to continue if the component is already in used by sysFS. */ + if (drvdata->mode == CS_MODE_SYSFS) { + ret = -EBUSY; + goto out; + } + + /* Get a handle on the pid of the process to monitor */ + pid = task_pid_nr(handle->event->owner); + + if (drvdata->pid != -1 && drvdata->pid != pid) { ret = -EBUSY; goto out; } /* + * No HW configuration is needed if the sink is already in + * use for this session. + */ + if (drvdata->pid == pid) { + atomic_inc(csdev->refcnt); + goto out; + } + + /* * We don't have an internal state to clean up if we fail to setup * the perf buffer. So we can perform the step before we turn the * ETB on and leave without cleaning up. */ - ret = etb_set_buffer(csdev, (struct perf_output_handle *)data); + ret = etb_set_buffer(csdev, handle); if (ret) goto out; ret = etb_enable_hw(drvdata); if (!ret) { + /* Associate with monitored process. */ + drvdata->pid = pid; drvdata->mode = CS_MODE_PERF; atomic_inc(csdev->refcnt); } @@ -336,6 +360,8 @@ static int etb_disable(struct coresight_device *csdev) /* Complain if we (somehow) got out of sync */ WARN_ON_ONCE(drvdata->mode == CS_MODE_DISABLED); etb_disable_hw(drvdata); + /* Dissociate from monitored process. */ + drvdata->pid = -1; drvdata->mode = CS_MODE_DISABLED; spin_unlock_irqrestore(&drvdata->spinlock, flags); @@ -406,7 +432,7 @@ static unsigned long etb_update_buffer(struct coresight_device *csdev, const u32 *barrier; u32 read_ptr, write_ptr, capacity; u32 status, read_data; - unsigned long offset, to_read, flags; + unsigned long offset, to_read = 0, flags; struct cs_buffers *buf = sink_config; struct etb_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent); @@ -416,6 +442,11 @@ static unsigned long etb_update_buffer(struct coresight_device *csdev, capacity = drvdata->buffer_depth * ETB_FRAME_SIZE_WORDS; spin_lock_irqsave(&drvdata->spinlock, flags); + + /* Don't do anything if another tracer is using this sink */ + if (atomic_read(csdev->refcnt) != 1) + goto out; + __etb_disable_hw(drvdata); CS_UNLOCK(drvdata->base); @@ -526,6 +557,7 @@ static unsigned long etb_update_buffer(struct coresight_device *csdev, } __etb_enable_hw(drvdata); CS_LOCK(drvdata->base); +out: spin_unlock_irqrestore(&drvdata->spinlock, flags); return to_read; @@ -733,6 +765,9 @@ static int etb_probe(struct amba_device *adev, const struct amba_id *id) if (!drvdata->buf) return -ENOMEM; + /* This device is not associated with a session */ + drvdata->pid = -1; + desc.type = CORESIGHT_DEV_TYPE_SINK; desc.subtype.sink_subtype = CORESIGHT_DEV_SUBTYPE_SINK_BUFFER; desc.ops = &etb_cs_ops; |