1 files changed, 26 insertions, 17 deletions

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c
index 2527b5d3b65e..23b7ff00af5c 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
@@ -280,7 +280,6 @@ static int tmc_enable_etf_sink(struct coresight_device *csdev,
 			       u32 mode, void *data)
 {
 	int ret;
-	struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
 
 	switch (mode) {
 	case CS_MODE_SYSFS:
@@ -298,7 +297,7 @@ static int tmc_enable_etf_sink(struct coresight_device *csdev,
 	if (ret)
 		return ret;
 
-	dev_dbg(drvdata->dev, "TMC-ETB/ETF enabled\n");
+	dev_dbg(&csdev->dev, "TMC-ETB/ETF enabled\n");
 	return 0;
 }
 
@@ -328,7 +327,7 @@ static int tmc_disable_etf_sink(struct coresight_device *csdev)
 
 	spin_unlock_irqrestore(&drvdata->spinlock, flags);
 
-	dev_dbg(drvdata->dev, "TMC-ETB/ETF disabled\n");
+	dev_dbg(&csdev->dev, "TMC-ETB/ETF disabled\n");
 	return 0;
 }
 
@@ -351,7 +350,7 @@ static int tmc_enable_etf_link(struct coresight_device *csdev,
 	spin_unlock_irqrestore(&drvdata->spinlock, flags);
 
 	if (!ret)
-		dev_dbg(drvdata->dev, "TMC-ETF enabled\n");
+		dev_dbg(&csdev->dev, "TMC-ETF enabled\n");
 	return ret;
 }
 
@@ -371,19 +370,17 @@ static void tmc_disable_etf_link(struct coresight_device *csdev,
 	drvdata->mode = CS_MODE_DISABLED;
 	spin_unlock_irqrestore(&drvdata->spinlock, flags);
 
-	dev_dbg(drvdata->dev, "TMC-ETF disabled\n");
+	dev_dbg(&csdev->dev, "TMC-ETF disabled\n");
 }
 
 static void *tmc_alloc_etf_buffer(struct coresight_device *csdev,
 				  struct perf_event *event, void **pages,
 				  int nr_pages, bool overwrite)
 {
-	int node, cpu = event->cpu;
+	int node;
 	struct cs_buffers *buf;
 
-	if (cpu == -1)
-		cpu = smp_processor_id();
-	node = cpu_to_node(cpu);
+	node = (event->cpu == -1) ? NUMA_NO_NODE : cpu_to_node(event->cpu);
 
 	/* Allocate memory structure for interaction with Perf */
 	buf = kzalloc_node(sizeof(struct cs_buffers), GFP_KERNEL, node);
@@ -477,9 +474,11 @@ static unsigned long tmc_update_etf_buffer(struct coresight_device *csdev,
 	/*
 	 * The TMC RAM buffer may be bigger than the space available in the
 	 * perf ring buffer (handle->size).  If so advance the RRP so that we
-	 * get the latest trace data.
+	 * get the latest trace data.  In snapshot mode none of that matters
+	 * since we are expected to clobber stale data in favour of the latest
+	 * traces.
 	 */
-	if (to_read > handle->size) {
+	if (!buf->snapshot && to_read > handle->size) {
 		u32 mask = 0;
 
 		/*
@@ -516,7 +515,13 @@ 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;
@@ -542,11 +547,15 @@ static unsigned long tmc_update_etf_buffer(struct coresight_device *csdev,
 		}
 	}
 
-	/* In snapshot mode we have to update the head */
-	if (buf->snapshot) {
-		handle->head = (cur * PAGE_SIZE) + offset;
-		to_read = buf->nr_pages << PAGE_SHIFT;
-	}
+	/*
+	 * In snapshot mode we simply increment the head by the number of byte
+	 * that were written.  User space function  cs_etm_find_snapshot() will
+	 * figure out how many bytes to get from the AUX buffer based on the
+	 * position of the head.
+	 */
+	if (buf->snapshot)
+		handle->head += to_read;
+
 	CS_LOCK(drvdata->base);
 out:
 	spin_unlock_irqrestore(&drvdata->spinlock, flags);