1 files changed, 24 insertions, 5 deletions

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index bae47272de98..625882bc8b08 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -1418,10 +1418,11 @@ free_etr_perf_buffer:
  * buffer to the perf ring buffer.
  */
 static void tmc_etr_sync_perf_buffer(struct etr_perf_buffer *etr_perf,
+				     unsigned long src_offset,
 				     unsigned long to_copy)
 {
 	long bytes;
-	long pg_idx, pg_offset, src_offset;
+	long pg_idx, pg_offset;
 	unsigned long head = etr_perf->head;
 	char **dst_pages, *src_buf;
 	struct etr_buf *etr_buf = etr_perf->etr_buf;
@@ -1430,7 +1431,6 @@ static void tmc_etr_sync_perf_buffer(struct etr_perf_buffer *etr_perf,
 	pg_idx = head >> PAGE_SHIFT;
 	pg_offset = head & (PAGE_SIZE - 1);
 	dst_pages = (char **)etr_perf->pages;
-	src_offset = etr_buf->offset + etr_buf->len - to_copy;
 
 	while (to_copy > 0) {
 		/*
@@ -1478,7 +1478,7 @@ tmc_update_etr_buffer(struct coresight_device *csdev,
 		      void *config)
 {
 	bool lost = false;
-	unsigned long flags, size = 0;
+	unsigned long flags, offset, size = 0;
 	struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
 	struct etr_perf_buffer *etr_perf = config;
 	struct etr_buf *etr_buf = etr_perf->etr_buf;
@@ -1506,16 +1506,35 @@ tmc_update_etr_buffer(struct coresight_device *csdev,
 	spin_unlock_irqrestore(&drvdata->spinlock, flags);
 
 	lost = etr_buf->full;
+	offset = etr_buf->offset;
 	size = etr_buf->len;
+
+	/*
+	 * The ETR buffer may be bigger than the space available in the
+	 * perf ring buffer (handle->size).  If so advance the offset so that we
+	 * 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 (!etr_perf->snapshot && size > handle->size) {
-		size = handle->size;
+		u32 mask = tmc_get_memwidth_mask(drvdata);
+
+		/*
+		 * Make sure the new size is aligned in accordance with the
+		 * requirement explained in function tmc_get_memwidth_mask().
+		 */
+		size = handle->size & mask;
+		offset = etr_buf->offset + etr_buf->len - size;
+
+		if (offset >= etr_buf->size)
+			offset -= etr_buf->size;
 		lost = true;
 	}
 
 	/* Insert barrier packets at the beginning, if there was an overflow */
 	if (lost)
 		tmc_etr_buf_insert_barrier_packet(etr_buf, etr_buf->offset);
-	tmc_etr_sync_perf_buffer(etr_perf, size);
+	tmc_etr_sync_perf_buffer(etr_perf, offset, size);
 
 	/*
 	 * In snapshot mode we simply increment the head by the number of byte