From 810c398bc09b2f2dfde52a7d2483a710612c5fb8 Mon Sep 17 00:00:00 2001 From: Adrian Hunter Date: Fri, 23 Sep 2016 17:38:41 +0300 Subject: [PATCH] perf intel-pt: Fix snapshot overlap detection decoder errors Fix occasional decoder errors decoding trace data collected in snapshot mode. Snapshot mode can take successive snapshots of trace which might overlap. The decoder checks whether there is an overlap but only looks at the current and previous buffer. However buffers that do not contain synchronization (i.e. PSB) packets cannot be decoded or used for overlap checking. That means the decoder actually needs to check overlaps between the current buffer and the previous buffer that contained usable data. Make that change. Signed-off-by: Adrian Hunter Cc: Jiri Olsa Cc: Masami Hiramatsu Cc: Mathieu Poirier Cc: stable@vger.kernel.org # v4.3+ Link: http://lkml.kernel.org/r/1474641528-18776-10-git-send-email-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/intel-pt.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c index b9cc353cace2..b744ea812a2e 100644 --- a/tools/perf/util/intel-pt.c +++ b/tools/perf/util/intel-pt.c @@ -241,7 +241,7 @@ static int intel_pt_get_trace(struct intel_pt_buffer *b, void *data) } queue = &ptq->pt->queues.queue_array[ptq->queue_nr]; - +next: buffer = auxtrace_buffer__next(queue, buffer); if (!buffer) { if (old_buffer) @@ -264,9 +264,6 @@ static int intel_pt_get_trace(struct intel_pt_buffer *b, void *data) intel_pt_do_fix_overlap(ptq->pt, old_buffer, buffer)) return -ENOMEM; - if (old_buffer) - auxtrace_buffer__drop_data(old_buffer); - if (buffer->use_data) { b->len = buffer->use_size; b->buf = buffer->use_data; @@ -276,6 +273,16 @@ static int intel_pt_get_trace(struct intel_pt_buffer *b, void *data) } b->ref_timestamp = buffer->reference; + /* + * If in snapshot mode and the buffer has no usable data, get next + * buffer and again check overlap against old_buffer. + */ + if (ptq->pt->snapshot_mode && !b->len) + goto next; + + if (old_buffer) + auxtrace_buffer__drop_data(old_buffer); + if (!old_buffer || ptq->pt->sampling_mode || (ptq->pt->snapshot_mode && !buffer->consecutive)) { b->consecutive = false;