aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorMathieu Poirier <mathieu.poirier@linaro.org>2019-04-26 13:59:37 -0600
committerMathieu Poirier <mathieu.poirier@linaro.org>2019-05-03 09:35:28 -0600
commit527c29fbd89f69c186d29280cae5279f5d1a494e (patch)
tree2add1e9ab915b4b1b84f29b7f1f2d759be319d2a
parentde0df8545a54fb9aa6c7e8d5f365d272399fa13d (diff)
downloadcoresight-527c29fbd89f69c186d29280cae5279f5d1a494e.tar.gz
coresight: perf: Don't set the truncated flag in snapshot mode
This patch avoids setting the truncated flag when operaring in snapshot mode since the trace buffer is expected to be truncated and discontinuous from one snapshot to another. Moreover when the truncated flag is set the perf core stops enabling the event, waiting for user space to consume the data. In snapshot mode this is clearly not what we want since it results in stale data. Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
-rw-r--r--drivers/hwtracing/coresight/coresight-etb10.c8
-rw-r--r--drivers/hwtracing/coresight/coresight-tmc-etf.c8
-rw-r--r--drivers/hwtracing/coresight/coresight-tmc-etr.c8
3 files changed, 21 insertions, 3 deletions
diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c
index 0764647b92bc..6ff48be91f61 100644
--- a/drivers/hwtracing/coresight/coresight-etb10.c
+++ b/drivers/hwtracing/coresight/coresight-etb10.c
@@ -535,7 +535,13 @@ static unsigned long etb_update_buffer(struct coresight_device *csdev,
lost = true;
}
- if (lost)
+ /*
+ * Don't set the TRUNCATED flag in snapshot mode because 1) the
+ * captured buffer is expected to be truncated and 2) a full buffer
+ * prevents the event from being re-enabled by the perf core,
+ * resulting in stale data being send to user space.
+ */
+ if (!buf->snapshot && lost)
perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
/* finally tell HW where we want to start reading from */
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c
index d3025634f5e6..8039bd389034 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
@@ -538,7 +538,13 @@ static unsigned long tmc_update_etf_buffer(struct coresight_device *csdev,
lost = true;
}
- if (lost)
+ /*
+ * Don't set the TRUNCATED flag in snapshot mode because 1) the
+ * captured buffer is expected to be truncated and 2) a full buffer
+ * prevents the event from being re-enabled by the perf core,
+ * resulting in stale data being send to user space.
+ */
+ if (!buf->snapshot && lost)
perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
cur = buf->cur;
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index b9881d6d41ba..718586a083af 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -1516,7 +1516,13 @@ tmc_update_etr_buffer(struct coresight_device *csdev,
lost |= etr_buf->full;
out:
- if (lost)
+ /*
+ * Don't set the TRUNCATED flag in snapshot mode because 1) the
+ * captured buffer is expected to be truncated and 2) a full buffer
+ * prevents the event from being re-enabled by the perf core,
+ * resulting in stale data being send to user space.
+ */
+ if (!etr_perf->snapshot && lost)
perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
return size;
}