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-rw-r--r--drivers/hwtracing/coresight/coresight-etb10.c43
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;